5121 - Copley Controls

5121 - Copley Controls
Models 5121, 5131, 5211, 5221, 5231, 5321
DC Brushless Servo Amplifiers
FEATURES
•
Complete servo amplifier for dc
brushless-motors with 60° or 120°
Halls
•
Wide power supply range
+24 to +225VDC
±5 to ±15A continuous
±10 to ±30A peak
•
+5V @ 200mA powers motors
with “commutating encoders”
•
VELOCITY MODE OPTIONS
Hall or encoder tach
Brushless tachometer
•
BRAKE feature with
current-limiting
•
FAIL-SAFE ENABLE INPUT
with ground or +5V
active level selection
•
FAULT PROTECTIONS
Short-circuits
output to output
output to gnd
Over / under voltage
Over temperature
Self-reset or latch-off
•
•
3kHz Bandwidth
Wide load inductance range
0.2 to 40 mH.
•
Independent settings for continu
ous and peak current, and peaktime
•
Surface mount technology
APPLICATIONS
•
•
•
X-Y stages
Robotics
MODEL
5121
5131
5211
5221
5231
5321
POWER
+24 to +90 VDC
+24 to +90 VDC
+24 to +180 VDC
+24 to +180 VDC
+24 to +180 VDC
+24 to +225 VDC
I-CONT (A)
10
15
5
10
15
10
I-PEAK (A)
20
30
10
20
30
20
FEATURES
The 5xx1 models are third-generation amplifiers for Hall commutated
dc brushless motors. Operating from +24 to +225 VDC transformerisolated unregulated power supplies, models output peak currents
from ±10 to ±30A, and continuous currents of ±5 to ±15A.
Built with surface-mount technology, these amplifiers offer a full
complement of features for DC brushless motor control. Torquemode operation is standard, and there are three choices for velocityloop operation. Brush tachometers can be used with the standard
amplifier. Brushless tachometers are supported with the “U” option.
Frequency to voltage conversion of Hall or encoder signals gives
tachless velocity-loop operation with the “V” option.
Torque mode is used typically with digital controllers that calculate
position and velocity from the motors encoder. Velocity loops using
brush or brushless tachometers give the best low-speed control. Hall
tach operation works well for high speed applications such as
spindles. Encoder tach velocity loops give a wide speed range and
lower ripple near zero velocity.
Separate current-limits provide protection for motors while optimizing
acceleration characteristics. Peak current, continuous current, and
peak-time are individually settable.
THE OEM ADVANTAGE
The /Enable input active logic-level is switch-selectable to ground or
+5V to interface with all types of control cards. Fail-safe operation in
either polarity results from an internal jumper that selects the default
input level so that the amplifier shuts down with no input.
•
Conservative design
for high MTBF
An active brake feature decelerates the motor to zero velocity with
current-limiting and adjustable gain.
•
Flexibility: internal header config
ures amp for wide range of
applications
Mosfet H-bridge output stage delivers four-quadrant power for bidirectional acceleration and deceleration of motors.
Automated assembly machinery
An internal 40-pin solderless socket lets the user configure the
various gain and current limit settings to customize the amplifiers for
a wide range of loads and applications.
Header components permit compensation over a wide range of load
inductances to maximize bandwidth with different motors.
All models are protected against output short circuits ( output to
output and output to ground ) and heatplate overtemperature. With
the /Reset input open the amplifier will latch off until powered-down
or the /Reset input is toggled. The amplifier will reset itself automatically from faults if the /Reset input is wired to GND.
187
Models 5121, 5131, 5211, 5221, 5231, 5321
DC Brushless Servo Amplifiers
Typical at 25°C ambient, Load = 200µH. in series with 1 Ω.
TECHNICAL SPECIFICATIONS
MODEL
5121
5131
5211
5221
5231
5321
OUTPUT POWER
Peak power
Peak time
Continuous power
±20A @ ±83V
±10A @ ±85V
±30A @ ±83V
±10A @ ±171V
±20A @ ±171V
1 sec at peak power or 2 secs. after polarity reversal
±15A @ ±85V
±5A @ ±173V
±10A @ ±173V
Ro = 0.2
±Vout = (±HV)×(0.97) - (Ro)×(Io)
Ro = 0.4
OUTPUT VOLTAGE
LOAD INDUCTANCE
BANDWIDTH
Ro = 0.15
±30A @ ±172V
±20A @ ±214V
±15A @ ±173V
±10A @ ±216V
Ro = 0.1
Ro = 0.2
Ro = 0.2
200 µH to 40mH typical. Selectable with components on header socket
Small signal
-3dB @ 3kHz with 200µH load at maximum supply voltage, varies with load inductance and RH20, CH18 values
PWM SWITCHING FREQUENCY
25kHz
REFERENCE INPUT
Differential, 94KΩ between inputs, ±20V maximum
GAINS
Input differential amplifier
PWM transconductance stage
POTS
Ref Gain
Tach Gain
Loop Gain
Integ Freq
Balance/Test
Default = CW
Default = CCW
Default = CCW
Default = CCW
Default = center
CCW attenuates Reference input from x1 to 0
CW increases speed ( decreases feedback from tachometer ). Note: fully CW = open-loop
CW increases loop gain in velocity mode, current gain in torque mode
Integrator zero-gain frequency in velocity mode. CW increases stiffness
Use to set output current or rpm to zero; or use as ±10V test input if RH9 set to 50kΩ
DIP SWITCHES
S1: /Enable input active level
Default = OFF
ON
Default = ON
OFF
GND enables, open or >2.5V inhibits ( Note: S1 has no effect on /Pos or /Neg enables )
Open or >2.5V enables, GND inhibits
Integrator disabled for torque mode
Integrator enabled for velocity mode
S2: Integrator control
X1
Ipeak / 6V
(Volt / Volt)
(Amps / Volt)
LOGIC INPUTS
/Enable
/POS enable, /NEG enable
/Brake
/Reset
Input resistance
Logic threshold voltage
Input voltage range
Default = GND
GND enables amplifier, open or >2.5V inhibits with S1 OFF. If S1 ON then GND inhibits
Default = GND
GND enables, open or >2.5V inhibits positive/negative output currents ( S1 has no effect )
Default = OPEN
GND brakes motor. ( Wire to +5V for brake-OFF condition if J4 is jumpered to GND )
Default = OPEN
GND resets latching fault condition, ground for self-reset every 50 ms.
10kΩ ( Jumper J4 selects connection to +5V or ground ), R-C filters on inputs
2.5V ( Schmitt trigger inputs with hysteresis, 74HC14 )
0V to +32VDC
FAIL-SAFE OPERATION
Internal jumper J4 selects +5V or GND connection for input pull-up resistors to /Enable, /Pos Enable, /Neg Enable, /Reset, and /Brake
so that amplifier will default to disabled condition if inputs are open-circuit, or wires are broken. ( See Applications section for details )
LOGIC OUTPUT
+Fault ( /Normal )
HI output voltage
LO output voltage
LO ( current sinking ) when Normal LED is ON; HI when LED is OFF
+5V ( no load ). Output is N-channel mosfet drain terminal with10kΩ pullup resistor to +5V
1.25V @ max output current of 250mA. On resistance Ro = 5Ω, max voltage = 50VDC
INDICATORS (LED’s)
Normal ( Green )
Power OK ( Green )
Fault ( Red )
MONITOR OUTPUTS
ON = Amplifier enabled AND HV within normal limits AND NOT Fault ( overtemp or output short circuits )
ON = Power OK ( +HV >24V AND +HV < 92V for 51x1, or <182V for 52x1, or <230V for 5321 )
ON = Output short-circuit or over-temperature condition
Current Ref
Current Monitor
DC POWER OUTPUTS
Demand signal to PWM stage: ±6V = ±Ipeak
Response from motor: ±6V @ ±Ipeak (1kΩ, 33nF R-C filter)
+15VDC @ 5 mA ( J2-2, J3-1, and internal header at position 19 )
-15VDC @ 5mA ( J3-3, and internal header at position 22 )
+5V @ 250 mA max ( J2-3 )
Note: maximum power from all dc outputs not to exceed 1.4W
PROTECTIVE FEATURES
Short circuit (output to output, output to ground)
Overtemperature
Undervoltage
Overvoltage
Current-limiting (foldback)
Latches unit OFF ( Power off/on, or ground at /Reset input resets )
Latches unit OFF at 70°C on heatplate ( Power off/on, or ground at /Reset input resets)
Wire /Reset input to ground for automatic reset after latching fault
Shutdown at +HV < 22VDC
Shutdown at +HV > 92VDC( 51x1), or +HV > 182VDC ( 52x1), or +HV >230VDC ( 5321 )
( Amplifier operation resumes when power is NOT undervoltage or NOT overvoltage )
Output current set by header components (peak, continuous, & peak-time)
POWER REQUIREMENTS
DC power (+HV)
Watts minimum
Watts @ Icont
+24 to +90VDC ( 51x1), +24 to +180VDC ( 52x1), +24 to +225VDC ( 5321 ) Transformer isolated
2.5W
2.7W
2.5W
3W
4W
25W
41W
20W
54W
53W
THERMAL REQUIREMENTS
Storage temperature range -30°C to +85°C
Operating temperature range 0° to 70°C baseplate temperature
MECHANICAL
3.82 x 6.57 x 1.37 in. ( 97 x 167 x 34.8 mm. ) without optional heatsink
3.82 x 6.57 x 2.9 in. ( 97 x 167 x 74 mm. ) with optional heatsink mounted
1.1 lb ( 0.48 kg.) without optional heatsink. Add 1.0 lb ( 0.45 kg ) for heatsink.
Size
Weight
188
4W
50W
HALLS
J2 HALLS
& OPTIONS
(See Below )
GND
+15 @ 10mA
+5 @ 250mA
W
V
U
OPTION-A
1
2
3
4
5
6
7
8
9
8
CURRENT
MONITOR
+/-6.5V @ +/-Ipk
OPTION-B
9
CURRENT
REFERENCE
+/-6.5V @ +/-Ipk
10
3
-15V @ 5mA
OPTION-C
2
GND
7
6
5
4
1
GND or TACH(+)
TACH (-)
REF(-)
REF(+)
16
+15V @ 5mA
J3 SIGNALS
TACH
CONTROL
SYSTEM
AUX
22NF
1K
47K
47K
1K
47K
RH7
1K
U,V,W
-5
CW
100K
RH6
RH1
+
-
RH12
CH13
Total power from +5V <= 1250mW
SEL
G = X1
HDR 10
GNDS
PEAK
RH15
HDR19
+/-5 mA max
+15 -15
19
22
301k
-
-15
+15
+5
CURRENT
ERROR
AMP
+
RH20
49.9K
+HV
OUTPUT
CURRENT
SENSE
Gv = +HV
10
PWM
STAGE
MOSFET
"H"
BRIDGE
10k
DC / DC
CONVERTER
G
LED
NORMAL
LOGIC
CONTROL
&
STATUS
+5V
JP4
123
POWER GROUND AND SIGNAL GROUNDS ARE COMMON
12.1K
12.1K
33NF
0.22UF
SW1
470 PF
CH18
1.5NF
+
-
CH2
SW2
LOOP GAIN
INTEG FREQ
500K
50K
CW
1K
PEAK TIME
RH17
1K
CW
100 PF
60.4K
220 PF
CURRENT REF
SEL
CONT
RH16
CURRENT LIMIT SECTION
4.99M
RH9
CH5
CH8
100K
RH3
60 / 120 DEGREE
SELECTION IS AUTOMATIC
OPTIONS
ETACH
50K
+5
TACH GAIN
50K
cw
RH4
RH11
REF GAIN
DIFF AMP
BALANCE
HALL
LOGIC
3.3NF
10K
33NF
1K
-15V
+15V
CW
50K
1K
ETACH
+
-
47K
33NF
100K
OFF = ENABLE
ON = ENABLE
4
5
6
1
2
3
16
10
(DC-)
(n.c.)
(DC+)
MOTOR
GND
+HV
J1 MOTOR & POWER
W
V
U
J3 SIGNALS
GND
BRAKE
ENABLE
POS ENABLE
NEG ENABLE
NORMAL
RESET
CASE GROUND
NOT CONNECTED
TO CIRCUIT GROUND
GROUND CASE FOR SHIELDING
11
12
13
14
15
MOMENTARY SWITCH RESETS FAULT
WIRE RESET TO GROUND FOR SELF-RESET
Models 5121, 5131, 5211, 5221, 5231, 5321
DC Brushless Servo Amplifiers
FUNCTIONAL DIAGRAM
189
Models 5121, 5131, 5211, 5221, 5231, 5321
DC Brushless Servo Amplifiers
COMPONENT HEADER
DEFAULT 21
VALUES
20
LOAD INDUCTANCE COMPENSATION
RH20
-15V
+15V
HDR19
CH18
SEE CHART FOR
"MOTOR INDUCTANCE SETTING"
RH17
RH20
HEADER LOCATION
( COVER REMOVED )
LOAD INDUCTANCE COMPENSATION
PEAK TIME LIMIT
RH16
CONTINUOUS CURRENT LIMIT
RH15
PEAK CURRENT LIMIT
RH14
BRAKE GAIN
220 PF
CH13
60.4K
RH12
100K
RH11
PREAMP DC GAIN, HI FREQ ROLLOFF
GND
GND
AUX INPUT
HEADER GROUND TERMINALS
10 MEG
OPTION CARD LOCATION
BRUSHLESS TACH
OR
HALL / ENCODER TACH
HEADER INTERNAL VOLTAGES
RH9
BALANCE/TEST
CH8
RH7
RH1
RH6
100K
JP4
TACH INPUT LEAD NETWORK
TACH INPUT
CH5
321
REF INPUT LEAD NETWORK
RH4
100K
RH3
0.22 UF
CH2
RH1
JP4 SETTINGS
DIP SWITCH
/ENABLE
ACTIVE LEVEL
FOR FAIL-SAFE
ENABLE INPUTS
S1 S2
GND
+5V
1-2 PULL-UP TO +5V (DEFAULT)
2-3 PULL-DOWN TO GROUND
40
REFERENCE INPUT
INTEGRATOR R-C
1
MODE
SELECT
VELOCITY
TORQUE
NOTE DIP SWITCH POLARITY!
ON
OFF
S1 S2
MOTOR INDUCTANCE SETTING
Model
Load (mH)
0.2 to 0.5
0.6 to 1.9
2 to 5.9
6 to 19
20 to 40
5121
C
R
20k
6.8
68k
100k
220k
330k
5131
C
R
30k
6.8
68k
150k
220k
470k
5211
C
R
10k
6.8
15k
47k
68k
150k
5221
C
R
10k
6.8
30k
68k
150k
220k
5231
C
R
15k
6.8
30k
68k
150k
330k
5321
C
R
10k
6.8
40.2k
82k
150k
300k
Note: Values in bold & italics are factory default values. R = RH20 resistance in Ω, C = CH18 capacitance in nF.
Values shown are for 90V (5121, 5131), 180V (5211, 5221, 5231), and 225V (5321). At lower supply voltages
RH20 may be increased and CH20 decreased. Test for best results: short CH18, select RH20 for best
step response in current-mode, next test CH18 for lowest value that does not degrade step response.
PEAK CURRENT TIME-LIMIT
Tpeak (s)
RH17 (Ω)
1.5
open 1
1.0
2M
0.5
560k
Times shown are for 100% step from 0A
PEAK CURRENT LIMIT
Ipeak (%)
100
80
60
40
20
190
RH15 (Ω)
open 1
20k
9.1k
4.3k
1.5k
1. Values in bold & italics are factory default values.
2. Peak times double after polarity reversal.
3. Peak current limit should always be set greater than
or equal to continuous current limit
CONTINUOUS CURRENT LIMIT
Icont (%)
100
80
60
40
20
RH16 (Ω)
open 1
47k
20k
6.8k
510
Models 5121, 5131, 5211, 5221, 5231, 5321
DC Brushless Servo Amplifiers
AMPLIFIER CONNECTIONS
5XX1 Amplifier
J2
1 +15V @ 5mA
USER
CONTROL
GN D 1
2 GN D
3 -15V @ 5mA
+15V @ 10mA 2
4 REF+
+5V @ 250mA 3
+5V
+/-10V
W
GND
HALL W 4
5 REF-
V
HALLS
HALL V 5
U
HALL U 6
0V
GND 7
6 TACH
OPTION A 8
OPTION B 9
7 GN D
OPTION C 10
+5V
ENCODER
8 CURR MON
GND 7
9 CURR REF
OPTION A 8
10 /BRAKE
OPTION B 9
11 /ENABLE
Note 2
OPTION C 10
12 /POS ENAB
JP4 = 2-3
JP4 = 1-2
GND
-U OPTION
U
V
W
BRUSHLESS
TACHOMETER
J2
13 /NEG ENAB
NOTE: MOTOR CONNECTIONS
MAY VARY WITH MOTOR TYPE
TEST FOR BEST RESULTS
14 +FAULT
15 /RESET
MOTOR W 1
16 AUX
MOTOR V 2
FAIL-SAFE CONNECTIONS
J3
MOTOR
MOT OR U 3
GN D 4
3 2 1
+5V
GN D 5
10k
+HV 6
I NPUT
Notes
-V OPTION
0V
TACHOMETER
JP4
A
B
+
J1
1. All amplifier grounds are common (J1-3,4 & J2-2,7)
Case/heatplate is isolated from amplifier grounds.
2. /Enable input is ground active with S1 in the OFF ( default ) position: GND will enable the amplifier.
For +5V active enables, set S1 ON ( open inputs will enable amplifier via internal pullups to +5V).
3. For best noise immunity, use twisted shielded pair cable for reference and tachometer inputs.
Twist motor and power cables and shield to reduce radiated electrical noise from pwm outputs.
SWITCH AND POTENTIOMETER SETTINGS ( SEE APPLICATION SECTION FOR DETAILS )
S2
Ref Gain pot
TORQUE MODE
ON
Sets current-gain
Default
ON
CW
Tach Gain pot
n/a
CCW
Loop Gain Pot
Integ. Freq Pot
CCW
n/a
CCW
CCW
VELOCITY MODE
OFF for operation, ON for initial setup ( see Integ Freq Pot below)
RPM/Vref ratio, use after tach-loop settings are complete CCW reduces
speed
Begin full CCW, adjust CW to increase speed. Sets Vtach/Vref ratio. Readjust Loop Gain, Integ. Freq pots after changing
CW until oscillation, then back off 1-2 turns
Adjust Loop-Gain pot with S2 ON, then with S2 OFF, adjust CW for best
stiffness without oscillation
191
Models 5121, 5131, 5211, 5221, 5231, 5321
DC Brushless Servo Amplifiers
APPLICATION INFORMATION
INTRODUCTION
Operating from transformer-isolated DC power supplies,
the 5xx1 family of amplifiers has been designed to drive
three-phase DC ( permanent-magnet ) brushless motors in
either torque or velocity mode. Hall detectors mounted in
the motor provide commutation information for ‘trapezoidal’
or 6-step drive. Adjustable current limits for peak, continuous, and peak time provide protection for smaller motors.
The “U” option supports motors using brushless tachometers for velocity loop operation. And, the “V” option uses
frequency to voltage conversion techniques to deliver
velocity loop operation from A/B channel digital encoders,
or the motors own Hall signals. The sections that follow
describe the initial setup of the amplifier and connection to
power sources, as well as the operation of the amplifiers
with their options.
POWER SUPPLIES & GROUNDING
Transformer-isolated power supplies are required, and in
most cases these are unregulated power supplies consisting of transformer, rectifier, and filter capacitor. The choice
of power supply voltage should take into consideration the
variation in the mains voltage, and the no-load to full-load
change in power supply output voltage. For example:
common 120VAC lines may vary from 105 to 132VAC, and
power supply output may change from 5 to 10% from the
no-load condition The goal then becomes to find a power
supply voltage that is adequate to power the motor at full
load at low-line conditions, and that will not cause the
amplifier to shutdown for overvoltage fault under high-line
and no-load conditions. This equation is a shortcut way to
find the highest power supply voltage where:
VDC = Power supply full load output voltage
MaxBuss = amplifier maximum power supply rating
Vmains:High = Maximum mains voltage
Vmains:Low = Minimum mains voltage
%Reg = power supply regulation in percent:
Example: Find the highest voltage for a model 5121 power
supply operating from 120V mains. The amplifiers normal
operating range is +24 to +90VDC, the mains voltage is
132V maximum and 105V minimum, and the supply
regulation will be 5%.. Solving this equation gives 68V.
Note that this does not reflect any tolerance for “pump-up”
of the power supply due to regenerative power transfer
during deceleration of heavy loads.
Higher voltages could be used, but you would need some
assurance that the AC mains would stay within a narrower
margin at your site if you want to be prepared for the worstcase conditions.
AMPLIFIER WIRING & CABLING
Power supply and motor connections should be done with
wire that has a rating to support the amplifiers continuous
current ratings. AWG 14 wire will support all amplifiers in
this series.
To minimize noise radiation from motor and power cabling,
wires should be twisted, and shielded if possible.
Hall and encoder signals are frequently routed near to
motor phase winding cables. To minimize coupling of PWM
noise, Hall wiring should be multiple-conductor shielded
cable. Grounding the motor case will also reduce coupling
between motor windings and Hall and/or encoder.
192
If amplifiers are more than 1m. from power supply capacitor, use a small (500-1000µF.) capacitor between the +HV
and Gnd inputs for local bypassing.
GROUNDING
Power ground and signal ground are common ( internally
connected ) in these amplifiers. All grounds are isolated
from the amplifier case which can then be grounded for
best shielding while not affecting the power circuits.
Currents flowing in the power supply connections create
noise that appears on the amplifier grounds. To minimize
this cable noise, the best approach is to ground the
amplifiers at J1-4, and to leave the minus side of the power
supply capacitor floating.
Wiring noise will be rejected by the differential amplifier at
the reference input, but will appear at the digital inputs.
These are filtered, but this noise must be considered when
multiple amplifiers are mounted more than 1-2 m from the
power supply.
MULTIPLE AMPLIFIER CONNECTIONS
When installing multiple amplifiers, each amplifier should
have its own twisted-pair cable running to terminals of the
power supply filter capacitor. Don’t “daisy-chain” cables
from one amplifier to the next. This will aggravate cable
noise and cause the noise from amplifiers to add to each
other. The “star” wiring configuration will minimize wiring
noise.
MOTOR HALL SIGNAL CONNECTIONS
Different manufactures use various naming conventions for
the Halls and motor phase windings. Copley uses the U-VW convention, but you may also see R-S-T, A-B-C or
others. In all cases there are three Hall signals and three
motor phase wires.
Most Halls operate from +5V. This, and +15V is available at
J2. Connect the Hall power & ground, and then wire the
Hall signals to the U-V-W inputs in the same order ( i.e., RS-T, A-B-C ).
Use shielded cable if possible, grounding the shield at the
amplifier and letting the motor end float. Once wired, you
will not have to change these connections during the
phasing process.
Regardless of the order in which the Halls are connected,
the motor windings can be phased correctly. We take the
approach that wires the Halls first, and then changes the
motor windings as needed simply because the motor
connections are screw terminals and are easily changed.
MOTOR PHASE CONNECTIONS
Connect the motor phase windings in the same U-V-W
order to begin the phasing process. Some motors are set
up to work well with this wiring scheme. If it is not the right
one, then there are only five other possible combinations of
wiring remaining, and one of these will be the right one.
AMPLIFIER CONTROL SIGNALS
Two type of controls signals are used: analog and digital.
The reference input(s) ( one input, two wires in differential
mode, see following ) is an analog input that takes the
industry-standard ±10V to control motor torque or velocity.
Digital signals connect to the /Enable, /Pos Enable, /Neg
Enable, /Reset, and /Brake inputs to control these functions in an ON/OFF mode. These signals can be TTL,
CMOS, or relays, but all share the characteristic that they
are two-state signals ( HI/LOW, ON/OFF, 0/+5V, open/
closed contact, etc. ).
Models 5121, 5131, 5211, 5221, 5231, 5321
DC Brushless Servo Amplifiers
REFERENCE INPUTS
The reference input is the input for the “command” signal to
the amplifier. There are two reference inputs ( Ref(+) and
Ref(-) ), and both should be used.
A differential amplifier operates like a voltmeter, measuring
the voltage between two points. In the case of a servo
amplifier, the voltage to be measured is typically the output
of a control system. You may think that your control card
has a single output, ±10V, for example, but that voltage is
relative to the ground at the control card. In practice this
ground may be at a different potential than the ground at
the amplifier ( see the previous section about wiring and
cabling ).
By connecting the Ref(+) input to the output of the control
card, and Ref(-) to ground at the control card, the amplifier
will correctly measure the cards output and reject any
noise between the grounds.
Do nott connect Ref(-) to the amplifier signal ground, and
Ref(+) to the control card output. This connection will now
measure not only the cards output voltage, but will also
pick up as an input any noise that exists between card and
amplifier grounds! This can cause oscillation or erratic
operation.
/ENABLE INPUT
This input functions as the “ON/OFF” switch for the
amplifier. Without removing DC power from the amplifier,
this signal will completely disable the amplifier outputs, and
reset the integrators in the PWM and preamplifier stages
so that the amplifier will re-enable without jerking. When
the amplifier is disabled, the Normal LED will turn off,
switching of the PWM outputs will stop, and the +Fault
output will go HI. The mosfets in the output bridge are all
off, so the motor can be moved as if it were not connected
to the amplifier.
Note: the back-emf of the motor can cause the diodes that
are part of the mosfets to conduct if the motor voltage
exceeds the power supply. But, for small motions, the
motor will “coast” when the amplifier is disabled.
/ENABLE INPUT ACTIVE LEVEL SELECTION
The default operation for this signal is ground-active. That
is, grounding the input will enable the amplifier, and when
the signal is open ( or greater than +2.5V ), the amplifier
will be disabled. This type of operation is also fail-safe in
that a broken wire will cause the amplifier to disable
( default setting of JP4 on pins 1-2 connects pullup
resistors to +5V ).
For control cards that output +5V ( or open-collector ) to
enable the amplifier, dip switch S1 should be turned ON.
Now, grounding the input will disable ( inhibit ) the amplifier
and +5V ( or open-circuit ) will enable it. But, simply
changing this switch alone has eliminated the fail-safe
feature: a broken wire will produce an open input, and the
amplifier can operate.
FAIL-SAFE OPERATION FOR /ENABLE INPUT
Fail-safe operation means that the amplifier will be
disabled if the wire to the /Enable input is broken ( or the
input is open-circuit ). In order to provide fail-safe operation
with +5V active Enable ( S1 ON ) an internal jumper JP4 is
on the pc board that changes the connection for the “pullup” resistors for the Enable input, as well as the /Pos & /
Neg Enable, /Brake and /Reset inputs.
When this is moved to position 2-3, the input resistors are
connected to ground. Now, if the wire to the /Enable input
is broken, the input will be “pulled-down” to ground,
inhibiting the amplifier.
DIGITAL INPUT PULL-UP/PULL-DOWN RESISTORS
( JUMPER JP4 )
This is a three pin jumper with a shorting plug found just
behind the LED’s on the pc board. The default position is
between pins 1-2, which connects the input resistors for
the enable inputs ( and others, see above ) to +5V. When
the position is changed to pins 2-3, the resistors become
“pull-downs” and the inputs will be grounded with no
signals attached. Used in conjunction with S1, this jumper
can be used for fail-safe operation so that broken wires
shut down the amplifier. The effect on inputs other than the
/Enable input is described below.
/POS & /NEG ENABLE INPUTS
THESE TWO INPUTS ARE ALWAYS GROUND-ACTIVE AND MUST BE
GROUNDED FOR THE AMPLIFIER TO OPERATE.
THE SETTING OF S1 HAS NO EFFECT ON THEIR OPERATION.
These inputs function as direction-sensitive enable/
disables and are normally used with limit switches so that
torque is inhibited when the motor drives into the limit, but
is available to back-out of the limit.
With JP4 in the default position, these inputs are pulled-up
to +5V and are typically grounded through normally closed
limit switches. When the switches open, the inputs pull-up
to +5V and the torque will be inhibited.
If JP4 is in position 2-3, for fail-safe /Enable operation from
cards that output +5V to run the amplifier, then normallyopen limit switches connected to +5V should be used.
When a limit switch is hit, the switch will pull-up to +5V and
torque will be inhibited.
/BRAKE INPUT
This input overrides the signal at the reference inputs and
drives the motor to a stop at a rate determined by the
amplifier current-limits and the value of header part RH14.
If the amplifier is simply disabled, the outputs stop switching and the motor coasts to a stop with no power applied.
Note that if JP4 is in the 2-3 position, that the /Brake input
must be wired to +5V to operate the amplifier ( brake off ).
The brake feature senses the motor back-emf and actively
drives it to zero, which corresponds to zero rpm. When this
feature is active the signals at the reference inputs are
internally disconnected from the PWM stage, and the
output voltage is fed-back through the current limit circuit in
such a way that the output voltage is driven to zero while
maintaining the current-limits set on the component
header.
Header component RH14 controls the gain of the brake
function. It should be chosen based on the application and
will vary according to the amplifier tuning, load inertia, and
motor characteristics. In practice, choose a value that will
drive the amplifier into current-limiting and does not
produce oscillation or noise at a standstill.
/RESET INPUT
Overtemperature and output short circuits are called
latching faults because they cause the amplifier to turn off
and stay off ( like a latching switch that stays where you left
it ).
These faults can be reset by turning the +HV off and back
on, or by grounding the /Reset input when the amplifier is
under power.
If an auto-reset from these conditions is desired, the /
Reset input can be wired to ground. In this case, the
amplifier will “try” to reset every 50mS. after a fault occurs,
and if the cause of the fault has been removed, operation
will resume.
If jumper JP4 has been moved to position 2-3 for fail-safe
operation from HI active /Enable input then the amplifier
will always auto-reset unless the /Reset input is jumpered
193
Models 5121, 5131, 5211, 5221, 5231, 5321
DC Brushless Servo Amplifiers
to +5V.
SETTINGS FOR THE MOTOR
INDUCTANCE COMPENSATION
Armature inductance compensation maximizes the
bandwidth for your motor and supply voltage. Values for
CH18, RH20 from the table ( page 4 ) work well for most
instances. To optimize: first replace CH18 with a jumper
(short), then use a 50Hz, 1V peak-to-peak square wave
input and select RH20 for the best step response ( lowest
risetime with minimal overshoot ). Next install CH18 and
choose the smallest value that does not result in excessive
ringing on the current waveform.
CURRENT LIMITS
The Current Reference signal provides a way to customize
these settings without driving the motor at high current
levels. This signal is the output of the servo preamplifier
stage and current limit section. It has the same scale factor
as the current monitor:
±6V will demand ±Peak current from the amplifier. In terms
of amps/volts the scale factor is Ipeak / 6V. So, for a model
5221 with a peak output current of 20A, the Current Ref
scale factor would be 20A / 6V or 3.33A/V. Using this you
can calculate the effects of header component changes on
the actual current to the motor. In use, a test signal is
inputted to the amplifiers reference inputs, and the
response can be observed at the Current Ref output.
CONTINUOUS CURRENT LIMIT
Select RH16 using manufacturers specification for your
motor. This keeps the motor within its thermal limits. Table
values give basic settings. Note that this limit measures
average current and will not work on symmetrical waveforms such as might occur during system oscillation. Input
a square wave reference signal of ±10V with a very slow (
1/4 Hz ) frequency. This will allow the 2 s. peak time after
polarity reversals, and time for the current to settle to the
continuous value. Calculate the current by multiplying the
observed voltage by the scale factor, and adjust the value
of RH16 for the desired current.
PEAK CURRENT LIMIT
Amplifiers are shipped with no part installed in RH15,
which delivers the amplifiers peak rated current. For lower
settings use values from the table. This setting is of
importance when a motor can be demagnetized by
currents that are within the peak-current capability of the
amplifier. Peak limits “clamp” motor current at the set value
and are not affected by the waveform.
Using the same ±10V square wave, select RH15 for the
desired output current as described above.
PEAK CURRENT TIME-LIMIT
Using the bipolar reference input, the observed peak times
will double, and will typically be 2s. after polarity reversals.
This is the maximum peak time that the amplifier can
deliver, and is 2X the unipolar peak time when driving from
0V input to the maximum of +10 or -10V. For shorter peak
times, test values of RH17 that give the desired result.
Note that peak times are also affected by the DC level of
the current that precedes the peak demand. So, peak
times will be less than 1s if preceded by currents of the
same polarity that are near to the continuos current level.
PHASING THE MOTOR
Power up the amplifier with the reference voltage set to
zero. Apply a small voltage ( about 0.5 to 1V ) between the
reference inputs. This should produce enough torque to
194
spin the motor. Watch what happens, and then reverse the
polarity of the reference. If the motor is phased properly, it
will rotate with little torque to the maximum speed permitted by the power supply. You may be able to slow it with
your hands ( be careful ). Proper phasing will be evident by
smooth rotation in both directions, and smooth torque at
low speeds. For a sensitive test of phasing, input a small (
±0.5 to ±1V ) reference signal at about 1Hz. Hold the motor
shaft and feel the torque in your hand. A properly phased
motor will feel as if someone was twisting the shaft with
their hands, the force will change smoothly as the direction
moves from CW to CCW. If the phasing is wrong the motor
may twist in one direction, but there will be a lag after
changing directions, and it may jump after a pause. Or, it
may not move at all. Of the six combination, the right one
should be quite obvious. As a check when you think that
you have got it right, change the windings: the motor
shouldn’t be good now at all.
If the first try doesn’t work, then there are five other
possible connections of the three motor wires remaining
and one of these must be the right one. Of the six possible
connection combinations, three of these will result in
rotation that is the opposite of the Hall signal rotation
pattern and will not work at all. Of the other three, one will
be the correct connection, one will run the motor at
reduced torque and with uneven low-speed operation, and
the third will not turn the motor at all, but will drive current
through the windings and produce no torque. The chart
below lists all six of the combinations to make it easy to try
them without missing one:
TRY
J1-3
J1-2
J1-1
DIR
#1
U
V
W
#2
V
W
U
CW
#3
W
U
V
#4
#5
#6
U
W
V
W
V
U
V
U
W
CCW
Note that combinations 1-2-3 all represent the same
direction of rotation. The thing that changes is the phasing
of the leads. If you read from left-to-right, beginning with U,
all of the first three are in U-V-W order. For combinations 45-6, note that W and V are reversed. But again, all of these
read in the same order U-W-V, and differ only in phasing. If
you start up your motor and it turns at all, even roughly,
then you probably have the correct direction of rotation and
should now try the other combinations in the same rotation
group. E.g., if you wired it up U-V-W and it ran roughly, then
try #2, or #3. If you get no rotation at all, and turning the
shaft by hand makes it jump backwards, then you’re
probably in the wrong rotation group, and should go to the
opposite group.
Remember that when the drive is operating in torque
mode, that the speed of the motor will only be controlled by
the load, or friction torque so typically small currents will
accelerate an unloaded motor to high speeds.
AMPLIFIER OPERATING MODES
TORQUE MODE OPERATION
Use this mode with microprocessor control cards that take
encoder signals, compute position and velocity, and output
a torque-control command to the amplifier.
Transconductance ( amps output vs. volts at Ref input )
equals Ipeak / 10V.
Models 5121, 5131, 5211, 5221, 5231, 5321
DC Brushless Servo Amplifiers
Settings
Ref Gain pot
Tach Gain pot
Loop Gain pot
Integ Freq pot
Balance pot
input
S2
fully CW
n/a ( no function )
fully CCW
n/a ( no function )
adjust for zero torque at zero
ON (disables integrator)
BRUSH TACHOMETER OPERATION
Disconnect the motor from the load for this
procedure! If tachometer phasing is reversed,
motor may ‘run-away’ at high speed damaging equipment or causing injury!
Begin with these settings:
Ref Gain pot
Tach Gain pot
Loop Gain pot
Integ Freq pot
Balance pot
input
S2
fully CW ( default )
fully CCW ( default )
fully CCW ( default )
fully CCW ( default )
adjust for zero torque at zero
ON (disables integrator)
Select a value for RH6 based on this equation, use a
standard value resistor closest to the solution:
(
RH6 =
pot to reduce the motor speed to the optimal value. The
reason for this is that changes in the Ref Gain pot will not
affect the adjustments of the Loop Gain and Integrator
Frequency pots, or the servo loop dynamics.
HV x Kg
Ke
)( )
RH3
10V
HV = power supply voltage
Kg = tachometer gradient ( usually volts / krpm )
Ke = motor back-emf constant ( volts / krpm )
RH3 = reference input scaling resistor( default = 100K)
10V = maximum reference input voltage ( typical )
DYNAMIC ADJUSTMENTS
“V” OPTION: FREQUENCY TO VOLTAGE TACHOMETER FROM HALL SIGNALS OR QUADRATURE
ENCODER
FUNCTIONAL DIAGRAM (SEE PG. 201)
OPTION BOARD LAYOUT (SEE PG. 201)
HALL TACH OPERATION ( default )
ENCODER TACH OPERATION
* Position of jumper J1-A sets polarity of tach
signal. This may change with selection of Hall or
encoder connections.
All other
jumpers must be set as shown.
“V” OPTION SPECIFICATIONS
ENCODER INPUTS
Encoder type:
2-channel, 90° quadrature,
incremental, digital single-ended outputs ( +5V logic , open-collector, TTL,
cmos, or line-driver.)
Inputs:
Logic threshold voltage 2.5V. RC
filter to 74HC14 Schmitt inverters.
Encoder power:
+5V @ 200mA max. available at J23; +15V @ 10mA available at J2-2 ( Halls use power from same pins ).
Maximum frequency: 600,000 f/v pulses/sec, or 150,000
encoder lines/sec ( each encoder line decodes to 4 f/v pulses )
HALL INPUTS
Connect motor and tachometer. Power-up the amplifier and
rotate the shaft slightly. If the tachometer is phased wrong
the motor will “run-away”. If this occurs, reverse tachometer
connections. When the phasing is correct, the motor will
show some resistance to rotation and will not run away.
Set reference voltage to zero and turn the LOOP GAIN pot
CW until tach oscillation occurs and then back-off until it
goes away, giving 1 or 2 additional turns CCW. Set S2 OFF.
With the INTEG FREQ pot fully CCW apply a step input.
Observe the tach signal and adjust INTEG FREQ in a CW
direction until some overshoot appears after the step.
Adjusting INTEG FREQ pot CW will increase stiffness. At
some point a strong oscillation will occur. Maximum
stiffness occurs just before oscillation, so adjust pot
carefully.
TACH GAIN POT
Always begin with the Tach Gain pot in the fully
CCW ( default ) position. Fully CCW gives maximum feedback, and minimum rpm. Fully CW gives
no feedback, and uncontrolled rpm.
With the Ref Gain pot fully CW, the tach/ref voltage ratio
will be set by the header components as described above.
Turning the Ref Gain pot CCW will reduce motor speed,
and turning the Tach Gain pot CW will increase motor
speed.
Adjusting the Tach Gain pot to change the motor speed will
also change the loop-gain of the servo loop, and thus alter
the bandwidth and risetime of the motor. For this reason,
we prefer to set the value of RH6 so that the motor goes a
bit faster than the ideal, and thereafter use the Ref Gain
Hall type:
Three-channel, digital, +5V or +15V
power, 60° or 120° electrical phase separation.
Inputs:
Logic threshold voltage 2.5V. RC
filter to 74HC14 Schmitt inverters.
Hall power:
+5V @ 200mA max. Available at J23; +15V @ 10mA available at J2-2 ( Encoder uses power from same pins ).
Maximum frequency: 600,000 f/v pulses/sec, or 100,000
Hall cycles/sec ( each Hall cycle decodes to 6 f/v pulses. Motor poles/2 = Hall
cycles per rev )
F/V TACH OUTPUT
±5V typical, ±10V maximum; connects to amplifier at Tach
Gain potentiometer ( see Functional Diagram )
LOW-PASS FILTER
Filter type:
Two-pole active filter. Voltage gain =
1:1. Filter type and frequency variable with component selection on header.
Default values
CH3, CH4 = 0.1µF for Hall tach
mode. For encoder tach mode, remove CH3 & CH4 ( see text for details )
F/V ONE-SHOTS ( MONOSTABLE MULTVIBRATORS )
IC type:
74HCT4538
Pulse width:
700ns minimum with CH1, CH2 =
100pF, 7ms with 1µF. Pulse width ≈ 0.7 X CH1 X 10kΩ ( CH1 and CH2 must
be same )
Default values
CH1, CH2 = 33nF for Hall tach
mode. For encoder tach mode, select values for application ( see text for
details )
ABOUT F/V CONVERSION
F/V, or frequency to voltage conversion is a technique that
takes a digital pulse train of some frequency and converts
it to an analog voltage, with the amplitude of the analog
signal proportional to the frequency of the digital signal.
As implemented in the 5xx1 series amplifiers, the “V”
option is a small pc board that is inside the amplifier case.
195
Models 5121, 5131, 5211, 5221, 5231, 5321
DC Brushless Servo Amplifiers
It uses a digital A/B channel encoder connected to the
Option A & B inputs on J2, or the Hall signals as the digital
signal source, and converts it to a ±10V analog signal that
feeds back to the amplifier through the Tach Gain potentiometer. This is shown as the ETACH signal on the functional diagram.
Where the reference input commanded an analog voltage
from a brush tachometer in an analog velocity loop, it now
commands a frequency from the digital encoder. As
encoders are manufactured with so many lines per
revolution, specifying a line frequency means specifying a
motor rpm, or revs per second.
In operation, the encoder or Hall signals are first decoded.
Each encoder line decodes into four states, and for every
pair of motor poles there is one Hall cycle, and each cycle
has six states. Each time there is a transition from one
state to the next, a monostable multivibrator, or one-shot is
fired and produces a pulse. The width of the pulses
depends on the settings of CH1 and CH2 and is selected
so that the duty-cycle at top speed is about 50%. This
sequence of pulses from the one-shots is then sent
through a low-pass filter where it becomes an analog ±5V
signal. The amplitude of the voltage is proportional to the
frequency of the pulse-train, and the polarity depends on
the direction of rotation of the motor. You can observe this
signal with an oscilloscope at the Tachometer Input pin J36.
HALL TACHOMETER OPERATION
OPTION CARD JUMPER SETTINGS
First remove the cover and check the jumper positions on
the option card. Hall tachometer is the default configuration. If the jumpers are not installed as shown, set them up
now.
J5
CH2
J1 A B
CH1
J7
J6
1
2
3
1
2
3
A
B
C
D
E
F
CD
J2
CH4
J8
CH3
A
B
J3
JUMPER POSITIONS
FOR J1-A
TACHOMETER POLARITY
DEFAULT
J9
1
2
REVERSE
POLARITY
3
The default values for the components are:
CH1, CH2 = 33nF
CH3, CH4 = 0.1µF
These values are for a 4-pole motor turning 10,000 rpm
maximum in Hall tach mode, with a low-pass filter
frequency of 15.9Hz.
POT AND SWITCH SETTINGS
The sections that follow give setup details for the options.
Before proceeding with these instructions, the amplifier
must first be set up and operating correctly in torque mode.
That is, the motor and Halls must be correctly phased,
current limits set, and inductance compensation set up. To
adjust these with the option card installed, first make these
settings:
Ref Gain pot
fully CW
Tach Gain pot
fully CW
Loop Gain pot
fully CCW
Integ Freq pot
n/a ( no function )
Balance pot
adjust for zero torque at zero
input
S2
ON (disables integrator)
The amplifier is now in torque mode, with no velocity
feedback. You can now proceed with the instructions in
previous sections about current-limiting, phasing, and so
forth.
When you have completed torque mode setup, rotate the Tach Gain pot fully CCW.
196
MAXIMUM F/V RATE CHECK
Next, check to see if your maximum motor speed is within
the range of the f/v converter. Enter the number of poles in
the motor, and maximum anticipated rpm into this equation:
Poles X rpm
Fmax =
20
The result should be less than 600,000. This will typically
be much lower than the 600,000 when operating in Hall
mode.
If it is more, then you must reduce the maximum rpm.
ONE-SHOT CAPACITOR SELECTION
Select the values of CH1 & CH2 ( they should always be
the same ) based on this equation:
CH1 = CH2 =
1400
Poles X rpm
( uF )
Use the standard capacitor value that is closest to the
result you get from this calculation. Final speed adjustments will be made using Ref Gain and Tach Gain pots, so
exact capacitor selection is not necessary.
After you have selected CH1 & CH2, install these in the
sockets on the option board. Begin your testing with the
motor disconnected from the load.
TACHOMETER SIGNAL POLARITY
Check the setting of J1-A first. This jumper controls the
polarity of the tachometer signal. This should always be
such that the tach signal is negative feedback. If the
polarity is reversed, the tach signal becomes positive
feedback, and the motor will speed up uncontrollably. The
alternate positions are on pins 1-2, or pins 2-3. With the
amplifier powered-up and enabled, turn the motor shaft
slightly. If the motor ‘runs-away’, change the jumper to the
alternate position. Try again, the motor shaft should now
resist rotation as you turn it. If the jumper has no effect,
check again the position of the Tach Gain pot, and be sure
that it is in the fully CCW position. With feedback enabled
and J1-A set properly you should have a velocity loop
DYNAMIC ADJUSTMENTS
LOOP GAIN
Next, adjust the Loop Gain. Use a function generator and
apply a square-wave to the reference inputs of about ±5V
and 1/2Hz. This will cause the motor to step to 1/2 of the
top speed in both directions. Without the integrator, speed
regulation ( the shape of the flat-top portion of the square
wave ) may be poor, but concentrate instead on the edges
of the waveform. Connect an oscilloscope to the tach
signal at J3-6, and adjust the Loop Gain pot to get a good
quality step-response. If the gain is too high ( pot CW )
there will be overshoot and/or ringing on the edge of the
step. Turn the pot CCW until the step-edge shows a clean
response in the minimum time. Note that the Hall tach
mode will produce a noisy tach signals at low speeds, so
the Loop Gain should be adjusted with the motor turning
more rapidly.
INTEGRATOR
Next, adjust the integrator. Set switch S2 OFF, this will
enable the integrator. Again, using the ±5V, 1/2Hz waveform and monitoring the Tach signal, turn the Integ Freq
pot in a CW direction. The best adjustment for the integrator will be found when there is some overshoot ( 10-20% ),
and settling without undershoot and ringing. If the pot is
turned too far CW, the integrator will produce very strong
oscillation at low frequencies. If this occurs, disable the
amplifier immediately, turn the pot 2-3 turns CCW, and try
Models 5121, 5131, 5211, 5221, 5231, 5321
DC Brushless Servo Amplifiers
again. If you can load the motor while it is turning, then
apply and remove the load and adjust the Integ Freq pot
for the best speed regulation that does not ring or ‘hunt’
when the load is removed and applied.
MOTOR TOP-SPEED
To make adjustments of the top speed. Apply a 10V signal
to the reference inputs. You can measure the top speed by
monitoring any Hall signal and measuring its period. The
jumpers at J3-D, E, or F are good points to probe to see
these signals. The motor speed in rpm will be:
Adjusting the Ref Gain pot CCW will reduce the speed,
and adjusting the Tach Gain pot CW will increase it. The
Ref Gain pot will not affect the dynamic behavior of the
velocity loop. But, large adjustments of the Tach Gain pot
will affect the loop gain and may require re-tuning of the
Loop Gain and Integ Freq pots.
LOW PASS FILTER
The default values for CH3 & CH4 are 0.1µF giving a lowpass filter frequency of 16Hz. We have found this to be a
good starting point for Hall tach operation. The Hall tach
pulse-train will be at a much lower frequency than with an
encoder, and typically Hall tach operation will be for high
speed applications such as spindles or pumps. This can
lead to very rough operation at lower speeds. So, begin
with the default values and then increase or decrease as
needed.
ENCODER TACHOMETER OPERATION
ENCODER CONNECTIONS
Use shielded cable for the encoder signals, if possible.
Grounding the motor case and encoder cable shield will
give maximum noise immunity from the PWM signals in the
motor power cabling. Encoder power is available at J2-3.
The +5V supply has a 200mA rating and will drive “commutating” encoders that output the A/B signals as well as the
Hall signals.
Connect the A and B channel encoder signal to the option
“A” and “B” inputs ( J2-8 & J2-9 ). J2-1 is the ground pin for
encoder signal ground, another ground pin ( J2-7 ) makes
it easy to connect the cable shield to ground.
OPTION CARD JUMPER SETTINGS
This diagram shows the positions of the jumpers and
capacitors on the option card. Note that only the jumpers
on J3 have changed from the default Hall tachometer
settings. J1-B, C, and J1-D remain in their default positions.
J1-A may change position depending on the polarity of the
tach signal required.
POT AND SWITCH SETTINGS
The sections that follow give setup details for the options.
Before proceeding with these instructions, the amplifier
must first be set up and operating correctly in torque mode.
That is, the motor and Halls must be correctly phased,
current limits set, and inductance compensation set up. To
adjust these with the option card installed, first make these
settings:
Ref Gain pot
fully CW
Tach Gain pot
fully CW
Loop Gain pot
fully CCW
Integ Freq pot
n/a ( no function )
Balance pot
adjust for zero torque at zero
input
S2
ON (disables integrator)
The amplifier is now in torque mode, with no velocity
feedback. You can now proceed with the instructions in
previous sections about current-limiting, phasing, and so
forth.
When you have completed torque mode setup, rotate the Tach Gain pot fully CCW.
MAXIMUM F/V RATE CHECK
An f/v pulse train is generated that is 4X the encoder line
frequency ( lines / second ). The maximum f/v clock rate for
the option is 600kHz. First check to make sure that your f/v
pulse-train will be within the options limits.
If the rate is greater than 600kHz, then the maximum
rpm or encoder line count must be reduced to stay
within the option specifications.
ONE-SHOT CAPACITOR SELECTION
If the rate is acceptable, select the f/v capacitors CH1
& CH2 as follows ( Note C = CH1 and CH2, both
should be the same ):
1 × 10e 9
C=
Lines × rpm ( C = pF )
TACHOMETER SIGNAL POLARITY
Check the setting of J1-A first. This jumper controls
the polarity of the tachometer signal. This should
always be such that the tach signal is negative
feedback. If the polarity is reversed, the tach signal
becomes positive feedback, and the motor will speed
up uncontrollably. The alternate positions are on pins
1-2, or pins 2-3. With the amplifier powered-up and
enabled, turn the motor shaft slightly. If the motor
‘runs-away’, change the jumper to the alternate
position. Try again, the motor shaft should now resist
rotation as you turn it. If the jumper has no effect,
check again the position of the Tach Gain pot, and be
sure that it is in the fully CCW position. With feedback
enabled and J1-A set properly you should have a
velocity loop
DYNAMIC ADJUSTMENTS
Begin with the switches and pots set like this:
Ref Gain pot
fully CW
Tach Gain pot fully CCW
Loop Gain pot fully CCW
Integ Freq pot fully CCW
Balance pot
adjust for zero torque at zero
input
S2
ON (disables integrator)
Next, enable the amplifier and turn the motor slightly.
Observe whether or not the motor ‘runs-away’. If it
does, reverse the position of jumper J1-A. The loop
should be stable before you proceed. When this is
complete, input a reference signal of a square-wave
of ±1V at a frequency of 1Hz. This will let you see the
step response of the velocity loop at the Tach input at
J3-6.
LOOP GAIN
Adjust the Loop Gain pot CW until the response to the
step overshoots and then back off for the cleanest
response. This will optimize the loop gain. If you turn
the pot CW too far, you may get oscillation. Again,
turn the pot CCW until this disappears and you get
the cleanest & fastest response without ringing.
INTEGRATOR
Now, set switch S2 OFF, this will enable the integrator.
197
Models 5121, 5131, 5211, 5221, 5231, 5321
DC Brushless Servo Amplifiers
With the motor at a standstill you can turn the shaft by
hand and feel the ‘stiffness’. Rotating the Integ Freq
pot CW will increase the stiffness. Too far and there
will be violent oscillation, so be ready to turn the
power off, or disable the amplifier. At the point of best
stiffness without oscillation, if you input the square
wave you should see some overshoot on the tach
signal that settles without excessive undershoot to the
steady-state value. Changes in load should cause an
increase in current such that the speed remains
constant.
These adjustments are made simpler by using switch
S2 so that you can turn the integrator on and off to
make the loop-gain and stiffness adjustments separately.
MOTOR TOP SPEED
When these adjustments are complete, input a 10V
DC signal, to drive the motor to top speed. Clip the
oscilloscope probe to the jumper at location J2. The
metal part of the jumper should be accessible. Here
you can monitor the train of pulses coming from the
one-shots. The duty cycle of these should be about
50%, typically. The quality of the encoder will determine the consistency of the pulse train. The important
thing is that the pulses never overlap, as this would
cause a sudden change in the tach voltage. Also, if
the pulses overlap, then the tach voltage would
‘saturate’, or remain unchanged as the speed
changes. This would open the velocity loop and the
motor would spin uncontrollably. If you’re getting pulse
overlap at the desired top speed of the motor, the
solution is to change to a smaller value capacitor for
CH1 & CH2 to make a narrower pulse. You will have
to re-adjust either the Tach Gain pot or header
resistor RH6 to re-set the top speed if this is the case.
LOW-PASS FILTER
CH3 and CH4 form a two-pole low-pass filter. The cutoff frequency of the filter is approximately ( assume
CH3 = CH4):
This frequency has a large effect upon the operation of the
velocity loop. As the frequency goes down, low-speed
ripple is less, and the range of operation increases. At the
same time the bandwidth of the velocity loop decreases,
and its response-time increases. As the frequency of the
filter increases, the velocity loop bandwidth increases with
it, but low-speed ripple will be greater. So, in practice the
choice of the filter is made on the basis of each application
and its individual requirements. There will always be a
tradeoff between low-speed velocity ripple and bandwidth.
When choosing a filter frequency for encoder operation, we
generally start with the CH3 & CH4 parts removed. This
approach works well for encoders with 500 lines or greater.
After top speed and velocity-loop adjustments are complete, capacitance can be added as necessary to smooth
out low-speed operation. The option card default components are set for Hall tach operation, and the low-pass filter
frequency is 16Hz. This is usually much too low for
encoder operation. This low frequency is chosen because
the frequency of the Hall signals is so much lower than the
typical encoder frequency that Hall operation is typically
used only for high-speed operation such as spindle drives.
These applications do not typically require fast response
times.
For encoder tach operation we have found that removing
198
CH3 & CH4 works for top speed and dynamic setup. Then,
rotate the motor at your lowest anticipated speed and
check the velocity ripple. If it is objectionable, then add
capacitance at CH3 & CH4 until it affects the overall tuning
and retest at low speed. If you want smoother operation
than you observe, you will have to sacrifice some bandwidth by lowering the filter frequency and re-tuning the
velocity loop with the new values.
U” OPTION: BRUSHLESS TACHOMETER
ADAPTER
FUNCTIONAL DIAGRAM (SEE PG. 201)
OPTION CARD LAYOUT (SEE PG. 201)
CH1 & CH2 control low-pass filter. RH1, 2, & RH3 control
tachometer scaling. J3-A controls tachometer polarity, J3-B
no function
“U” OPTION SPECIFICATIONS
TACHOMETER INPUTS
Type
Scaling
Voltage range
OUTPUT VOLTAGE
BANDWIDTH
3-phase Wye-connected with
grounded center tap
Adjustable with socketed
components
tbd VAC maximum
Analog, ±10V typical with tachometer at maximum
motor rpm
Settable with low-pass filter components
PROTECTION
Amplifier is reset when ETACH signal is >+12V or <12V.
This will cause a 50ms. shutdown, disabling output
stages and effectively limiting motor speed under
closed-loop conditions.
BRUSHLESS TACHOMETER OPERATION
The “U” option is an interface that mounts inside the
amplifier case and is powered from the main board. A
brushless tachometer connects to the J2 connector at the
Option A, B, and C pins ( and ground ). The three AC
waveforms from the tachometer are converted by the
option card into a DC voltage that is proportional to the
motor rpm in magnitude, and to the motor direction in
polarity. Input scaling resistors are chosen so that the
output of the option board is ±10V at the maximum speed
that the motor can achieve with a particular motor and
power supply combination. This signal is fed back to the
amplifier via the tachometer gain potentiometer ( see
ETACH on amplifier functional diagram ). Thus the tachometer input pin ( J3-6 ) can be used to monitor the ETACH
signal, and the Tach Gain pot can be used to adjust the
motor speed. The result is that the motor and amplifier form
a ‘velocity loop’ that controls motor speed in response to a
reference voltage input.
BRUSHLESS TACHOMETER CONNECTIONS
For best results, shielded cable should be used to connect
the tach signals from motor to amplifier. In addition, it is
Models 5121, 5131, 5211, 5221, 5231, 5321
DC Brushless Servo Amplifiers
recommended that the motor frame be grounded to add
shielding between the motor phase windings and the
tachometer. Tachometer signal currents are negligible, so
the choice of cable should be based on adequate mechanical strength, ability to flex, insulation breakdown
appropriate to tach voltages anticipated, and shielding.
POT AND SWITCH SETTINGS
The sections that follow give setup details for the options.
Before proceeding with these instructions, the amplifier
must first be set up and operating correctly in torque mode.
That is, the motor and Halls must be correctly phased,
current limits set, and inductance compensation set up. To
adjust these with the option card installed, first make these
settings:
Ref Gain pot
fully CW
Tach Gain pot
fully CW
Loop Gain pot
fully CCW
Integ Freq pot
n/a ( no function )
Balance pot
adjust for zero torque at zero
input
S2
ON (disables integrator)
The amplifier is now in torque mode, with no velocity
feedback. You can now proceed with the instructions in
previous sections about current-limiting, phasing, and so
forth.
When you have completed torque mode setup, leave
the Tach Gain pot fully CW. Before the velocity loop
can be closed, the tach signal must be tested for
correct phasing!
SCALING FOR MAXIMUM TACHOMETER VOLTAGE
The maximum motor speed will occur under no-load
conditions and will be a function of the motor back-emf and
power supply voltage. Scaling is the process of selecting
resistors so that the peak voltage at the tachometer
switching matrix does not exceed ±10V ( 7VACrms ) under
these conditions. This is important because signals greater
than this may cause the processing circuit to ‘saturate’,
opening the velocity loop and causing the motor to spin
uncontrollably.
You can calculate the values of these resistors by using the
following formulae. Your motor datasheet may define the
tachometer output in either volts ‘peak’ ( VDC ) or in volts
‘rms’ ( VAC ) per thousand revolutions per minute. This is
typically expressed as “V/krpm”. Use the formula that
matches the units in your motor datasheet, and calculate
Vpeak or Vrms based on the power supply voltage, and the
motor back-emf constant:
Vpeak = KgDC
+HV
( KeDC
)
Vpeak = DC peak tach voltage at maximum motor rpm
KgDC = tachometer gradient ( Vpeak/krpm )
KeDC = motor back-emf constant ( Vpeak/krpm )
+HV
Vrms = KgAC
1.4 KeAC
Vrms = AC peak tach voltage at maximum motor rpm
KgAC = tachometer gradient ( Vrms/krpm )
KeAC = motor back-emf constant ( Vrms/krpm )
+HV = Maximum DC power supply voltage
(
)
After you have calculated the maximum DC or AC tach
voltage, now find the values for the scaling resistors. The
“Rx” in the formulae refers to resistors RH1, RH2, and
RH3, which must all be the same value.
Rx =
Vpeak
Vrms
- 5
- 5
Rx =
2
1.4
(Rx = k ohms)
TACHOMETER SIGNAL PHASING
The previous adjustments should have left the amplifier in
torque mode, properly phased, with no tach signal feedback ( Tach Gain pot fully CW ). Apply a small reference
input to rotate the motor at a low speed. Monitor the tach
signal at J3-6. If the tachometer phasing is correct, the
signal will like a DC signal that follows the motor speed
directly. If phasing is not correct, there will be large
dropouts, ripple, or polarity reversals. If this occurs, try the
other five combinations of U-V-W tachometer signals that
are possible. Only one will be correct. When you think that
you have found it, reverse the reference voltage polarity to
rotate the motor in the opposite direction. The tach signal
should change to the opposite polarity in response to the
change in the motor direction.
TACHOMETER SIGNAL POLARITY
The polarity of the ETACH signal must be opposite to the
polarity of the reference signal in order for the loop to be
stable. To check for this without producing uncontrolled
speed, spin the motor under a small reference input in
torque mode, as described previously. Measure the polarity
of the Current Reference signal at J3-9. Next measure the
polarity of the ETACH signal at J3-6. Both must be the
same polarity. If they are opposite polarity, change the
position of jumper J3-A to the alternate position. This will
reverse the polarity of the ETACH signal so that is now
should be the same as the Current Reference signal.
When the tachometer is properly phased, and the
jumper is set for the correct polarity, rotate the Tach
Gain potentiometer fully CCW. This will close the
velocity loop.
DYNAMIC ADJUSTMENTS
Begin with the switches and pots set like this:
Ref Gain pot
fully CW
Tach Gain pot
fully CCW
Loop Gain pot
fully CCW
Integ Freq pot
fully CCW
Balance pot
adjust for zero torque at zero i
nput
S2
ON (disables integrator)
LOOP GAIN
Use a function generator and apply a square-wave to the
reference inputs of about ±5V and 1/2Hz. This will cause
the motor to step to 1/2 of the top speed in both directions.
Without the integrator, speed regulation ( the shape of the
flat-top portion of the square wave ) may be poor, but
concentrate instead on the edges of the waveform.
Connect an oscilloscope to the tach signal at J3-6, and
adjust the Loop Gain pot to get a good quality stepresponse. If the gain is too high ( pot CW ) there will be
overshoot and/or ringing on the edge of the step. Turn the
pot CCW until the step-edge shows a clean response in
the minimum time.
INTEGRATOR
Next, adjust the integrator. Set switch S2 OFF, this will
enable the integrator. Again, using the ±5V, 1/2Hz waveform and monitoring the Tach signal, turn the Integ Freq
pot in a CW direction. The best adjustment for the integrator will be found when there is some overshoot ( 10-20% ),
and settling without undershoot and ringing. If the pot is
turned too far CW, the integrator will produce very strong
oscillation at low frequencies. If this occurs, disable the
amplifier immediately, turn the pot 2-3 turns CCW, and try
again. If you can load the motor while it is turning, then
apply and remove the load and adjust the Integ Freq pot
for the best speed regulation that does not ring or ‘hunt’
when the load is removed and applied.
199
Models 5121, 5131, 5211, 5221, 5231, 5321
DC Brushless Servo Amplifiers
LOW-PASS FILTER
CH3 and CH4 form a two-pole low-pass filter. The cut-off
frequency of the filter is approximately ( assume CH3 =
CH4):
This frequency has a large effect upon the operation of the
velocity loop. The default frequency is 159Hz, a good
starting point for a wide range of applications.
If you application demands a faster velocity loop response,
begin by removing the filter capacitors CH3 & CH4. Then,
tune your velocity loop for the fastest response time that
you can achieve using the Loop Gain and Integ Freq pots.
If you want to smooth the response a bit, you can now add
capacitance at CH3 and CH4 that just begins to affect the
step response, and then back off of the Loop Gain pot for
best results.
Other applications may demand a slower response. In this
case, increase the capacitance until the desired risetime is
achieved.
VELOCITY LOOP TUNING ( BRUSH &
BRUSHLESS TACHOMETER, HALL OR ENCODER
TACHOMETER )
The principles of velocity loop tuning remain the
same even though the source of the tachometer
signal may vary.
1.
2.
3.
4.
FINDING THE BEST VALUES DEPENDS HEAVILY ON
THE APPLICATION, MOTOR AND LOAD INERTIA, AND
QUALITY OF MOTION DESIRED.
A VISUAL GUIDE TO TUNING THE AMPLIFIER
The waveforms for the current monitor in
torque mode operation, and the tachometer for velocity-loop operation are very
similar. Both involve a gain-stage and an
integrator function, and in both cases,
these adjustments are made separately.
Here is a quick overview to support the
explanations in the Applications section.
5.
Use a square-wave test waveform of
±0.5. Set the power supply to the anticipated
operating voltage.
Set dip switch S2 ON. This will disable
the integrator.
Observe the tach signal at J3-6. Adjust
the Loop Gain pot for the best step response
observing the edges of the tachometer
signal.
Set dip switch S2 OFF. This turns the
integrator ON. Adjust the Integ Freq pot in a
CW direction until some overshoot occurs,
but the signal settles cleanly without
undershooting excessively. Too much CW
rotation will produce undershoot and ringing,
or even violent oscillation. If the pot cannot
be adjusted over its range, increase or
decrease CH1 to scale the frequency range
up or down until the pot has a range of
adjustment that produces the best stiffness.
Switch to a sine-wave signal of the same
amplitude. Sweep the frequency over the
range of interest and note the frequency at
which amplitude drops to 0.707 of the
amplitude at 100Hz. This is the ‘bandwidth’
of the velocity loop.
LOAD INDUCTANCE COMPENSATION
Important: always power-down when changing
components in the header socket.
1. Use a square-wave test waveform of ±0.5.
Set the power supply to the anticipated
operating voltage.
2. Replace the compensation capacitor CH18
with a shorting jumper. This turns the
integrator OFF.
3. Observing the signal at the current monitor,
select a value for RH20 that gives a clean
step response.
Observe the edges of the waveform, do not
consider the ‘flat-top’ portion.
4. Install CH18. This turns the integrator ON.
Select the smallest value that does not
result
in excessive ( >10% ) overshoot and/or
oscillation while observing the flat-top
portion of the waveform.
5. Switch to a sine-wave signal of the same
amplitude. Sweep the frequency over the
range of interest and note the frequency at
which amplitude drops to 0.707 of the
amplitude at 100Hz. This is the ‘bandwidth’
of the current loop.
200
INTEGRATOR OFF
OSCILLATION, GAIN TOO HIGH!
GOOD RESPONSE, BEST RISETIME WITHOUT OSCILLATION
GAIN TOO LOW, SLUGGISH RESPONSE
LOOK AT THE EDGES!
INTEGRATOR ON
> 10% OVERSHOOT AND/OR OSCILLATION, CAPACITOR TOO SMALL
GOOD RESPONSE, SAME RISETIME WITH <10% OVERSHOOT
CAPACITOR TOO BIG, SLUGGISH RESPONSE
LOOK AT THE FLAT-TOPS
Models 5121, 5131, 5211, 5221, 5231, 5321
DC Brushless Servo Amplifiers
FUNCTIONAL DIAGRAM (“V”- OPTION)
J1A, J1B, J1C, J1D, J2
PROGRAM STATE DECODER
JUMPER
J3
CONNECTOR
+5V
J2
Chan. B
9
All
OPT C
N.C.
4.7K
& 100pF
OPT B
A
OPT A
C
Chan. A
+5V
100K
33nF
CH1
J9 DEFAULT POSITIONS
B
LOW-PASS FILTER
STATE
8
T-
ENCODER
Q
CH4
Q1
+VDC
3
1
100K
33nF
All
10K & 3.3nF
HALL W
B
-
GND
+5V
A
J9
+5V @ 200mA
+5V
GND
3
1
0.1uF
DECODER
CH2
100K
100K
"OR" GATE
AND
X2.2 DIFF AMP
+
TACH SIGNAL TO AMPLIFIER
TACHOMETER POTENTIOMETER
CH3
D
AMPLIFIER
0.1uF
HALL
HALL V
E
INPUTS
HALL U
F
T+
Q
Q2
J2 DEFAULT POSITION
NOTE: CH1, CH2, CH3, & CH4 SHOWN WITH DEFAULT
VALUES FOR HALL TACH OPERATION
MONITOR F/V PULSE TRAIN HERE
OPTION BOARD LAYOUT (SEE PG. 193)
HALL TACH OPERATION ( default )
J5
CH2
*
J7
J2
123
J5
J1
A B J3
CH1
J6
1
2
3
1
2
3
A
B
C
D
E
F
CD
CH4
J8
ENCODER TACH OPERATION
CH3
A
B
CH2
J1
*A B J3
CH1
1
2
3
1
2
3
J7
J6
J9
J2
123
123
A
B
C
D
E
F
CD
CH4
J8
CH3
A
B
J9
123
* Position of jumper J1-A sets polarity of tach signal. This may change with selection of Hall or encoder connections.
All other jumpers must be set as shown.
FUNCTIONAL DIAGRAM (“U”- OPTION)
CH2
BRUSHLESS TACH
INPUT SCALING RESISTORS
J5
J6
15 NF
Vtach
7 Vrms MAX
OPTION C
RH3
OPTION B
RH2
SWITCHING
OPTION A
RH1
MATRIX
-
10
100K
100K
ETACH
+
9
8
CH1
24.9K
(1.4 X Vtach )
LOW-PASS FILTER
10 NF
GND
7
4.7 K
( 3 PL )
CONNECTOR J2
15 NF
( 3 PL )
HALL U, V, W FROM
MAIN BOARD
OPTION CARD LAYOUT
J2
CH1
CH2
RH1
RH2
RH3
J5
J6
JUMPER POSITIONS
FOR J3
TACHOMETER POLARITY
J1
DEFAULT
J3 A
B
REVERSE
1 2 3 POLARITY
1 2 3
CH1 & CH2 control low-pass filter. RH1, 2, & RH3 control tachometer scaling. J3-A controls tachometer polarity, J3-B no function
201
Models 5121, 5131, 5211, 5221, 5231, 5321
DC Brushless Servo Amplifiers
OUTLINE DIMENSIONS
Dimensions in inches (mm.)
WEIGHT
1.1 lb ( 0.48 kg ) for amplifier. Add 1.0 lb ( 0.46 kg ) for heatsink option
CONNECTORS
), 30A max.
J1: Power & motor
6 position compression-connector ( Phoenix MKDS-5.08 ) AWG 24-12 ( 0.2 to 2.5 mm2
J2: Halls / Options
10-position housing ( Molex 22-01-3107 ) with ten AWG 30-22 contacts ( Molex 08-50-
J3: Signal
16-position housing ( Molex: 22-01-3167 ) with sixteen AWG 30-22 contacts ( Molex 08-
0114 )
50-0114 )
ORDERING GUIDE
Model 5121
Model 5131
Model 5211
Model 5221
Model 5231
Model 5321
20A peak, 10A continuous, +24 to +90 VDC brushless motor amplifier
30A peak, 15A continuous, +24 to +90 VDC brushless motor amplifier
10A peak, 5A continuous, +24 to +180 VDC brushless motor amplifier
20A peak, 10A continuous, +24 to +180 VDC brushless motor amplifier
30A peak, 15A continuous, +24 to +180 VDC brushless motor amplifier
20A peak, 10A continuous, +24 to +225 VDC brushless motor amplifier
Notes:
1. Add “U” to model number to specify brushless tachometer option
2. Add “V” to model number to specify Hall / Encoder tachometer option
3. Add “H” to model number to specify heatsink option.
Examples: 5121U for model 5121 with brushless tach option; 5321VH for 5321 with Hall / Encoder tach
& heatsink.
OTHER DC BRUSHLESS AMPLIFIERS
Model 503
Model 505
Torque-mode brushless amplifier. +18 to +55VDC, 5A continuous, 10A peak.
Same power output as 503. Adds Hall / Encoder tachometer feature for velocity loop
operation.
Model 513R
Resolver interface for trapezoidal-drive motors. Outputs A/B quadrature encoder signals
and analog tachometer signal for velocity loop operation. +24 to +180VDC operation, 13A
continuous, 26A peak.
Model 5421AC and 5321AC
Operation directly from 120VAC or 240VAC mains.
202
Corporate Offices: 20 Dan Road
Canton, MA 02021
Telephone: (781) 828-8090
Fax: (781) 828-6547
E-mail: sales@copleycontrols.com
www.copleycontrols.com
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertising