# Prelab assignment for Exp. 4 ```Prelab Assignment
Experiment 4
ECEN 4517/5517
You will design, construct, test, and demonstrate the cascaded boost converter power stage discussed
in Lecture 8 and illustrated below. You may choose any value for the converter switching frequency.
The converter will interface the 12V battery to a high-voltage (120 – 200 VDC) bus that is the input
of the dc–ac inverter. You should design the best converter system you can for this application, using
the parts in your kit, that results in a good engineering tradeoff between efficiency and maximum
output power.
Converter design. Select initial values for the switching frequency and duty cycles. Compute the
following quantities for two cases: (a) the converter output voltage is 120 V, and (b) the converter
output voltage is 200 V.
•
Duty cycle of each MOSFET
•
The dc output power Pmax that causes the intermediate-voltage filter capacitor C2 RMS
current to be at its maximum rated value (i.e., how much power can you get out of your
converter before the C2 rating is exceeded).
•
MOSFET conduction losses when P = Pmax
Your design should be capable of producing up to the PV panel rated power of 85 W at output
voltages of 120 Vdc and 200 Vdc. Note that producing even more that 85 W is useful since
additional power can be supplied by the battery.
Inductor design. Design the inductors L1 and L2 for your converter design above. For your designs,
specify the core size, the value of the air gap length, the number of turns, and the wire gauge. Keep a
copy of your work for use during the lab experiment.
ECEN 5517 additional prelab assignment: Loss budget. As discussed in class, develop a
preliminary loss budget for your design. You should calculate the conduction loss of every MOSFET
and diode, the switching losses, and the magnetics losses. These calculations should be based on the
available datasheet specifications. Show your work. Provide a list summary of these losses, along
with the total loss and the predicted efficiency. In your final report, you will refine these calculations
based on measured data.
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