Project 1

1. Cuk converter

Given, 

Vin = 300-600V

Vout = -450V

power= 5Kw

Input voltage considered is 500V

Fs =100KHz

1) Duty cycle 

Vo/Vin = -D / (1-D)

D = 0.47

2) Inductor design,

iL1 = P/Vin = 10A, iL2 = P /V0 = 11.11A

R = vo^2 / P = 40.5 ohm

For 10% ripple,

DeltaiL1 = 1A, DeltaiL2 = 1.1A

L1 = (vinD)/ (fs*DeltaiL1) = 2.35mH, L2 = 2.14mH

C1 = V0*D / R*fs*deltaVc1 = 0.549uF

Cout = (1-D) / 8*L2*fs^2*DeltaV0/V0 = 0.309uF

Cuk converter Schematic

The input and output voltages, duty ratio, current through inductors 1 and 2, voltage across the capacitors are shown in the above waveforms. The output of the Cuk converter for the input voltage of 500V is -450V. 

2. Sepic Converter

Schematic

Design,

Vin= 400V, Vout = 450V, P = 6000W

Duty cycle,

Vo/Vin = D/ (1-D)

D= 0.53

R = Vo^2/P =  33.75 ohm

fs =100KHz

Inductor design,

L1 = (vin *D/fs*deltaIL1) = 1.41mH

L2 =  (vin *D/fs*deltaIL2) = 1.593mH

C1 = V0*D / R*fs*deltaVc1 = 0.14uF

Cout = D / R*fs*deltaV0/V0) = 0.157uF

The input and output voltages, duty ratio, current through inductors 1 and 2, voltage across the capacitors are shown in the above waveforms. The input voltage is 400V and the output voltage is 450V. The output voltage across the Sepic converter is positive.

3. Boost Converter

Schematic

Design,

Vin = 300, vout= 450V, P= 2000W, fs =100KHz

R = Vout^/P = 101.25 ohm

Duty cycle,

Vo/Vin = -D/ (1-D) = 0.6

L = (Vout*(1-D) /fs* deltaIL) = 1.62mH

C = D / (r *fs* deltaV0/V0i)= 5.925uF

The Mosfet and diode, voltage and current, Input voltage and current, Output voltage and current waveforms are shown in the above waveforms

The input voltage to the converter is 300V and the output voltage from the converter is 450 V. The voltage is boosted up with a negative polarity in the buck boost converter.