1 Switching-Mode RegulatorsConvert an unregulated DC voltage into a regulated DC voltage ECE 442 Power Electronics

2 Output Voltage is Less Than the Input VoltageBuck Regulator Output Voltage is Less Than the Input Voltage BJT Chopper L-C Filter Load Control Voltage Freewheeling Diode ECE 442 Power Electronics

3 Mode 1 Operation – Q1 switched ONInput current flows through L, C, and the Load – rises linearly ECE 442 Power Electronics

4 Mode 2 Operation – Q1 switched OFFInductor current continues to flow through L, C, the Load, and Dm, falling linearly until Q1 is turned ON again. ECE 442 Power Electronics

5 Waveforms for the Buck RegulatorECE 442 Power Electronics

6 Summary for the Buck RegulatorThe peak-to-peak ripple current is The peak-to-peak ripple voltage is ECE 442 Power Electronics

7 Summary for continuous current caseThe critical value of the inductor is The critical value of the capacitor is ECE 442 Power Electronics

8 Output Voltage is Greater Than the Input VoltageBoost Regulator Output Voltage is Greater Than the Input Voltage ECE 442 Power Electronics

9 Mode 1 Operation – M1 switched ONInput current flows through L and M1 (linearly) ECE 442 Power Electronics

10 Mode 2 Operation – M1 switched OFFCurrent that flowed through the transistor now flows through L, C, the Load, and diode Dm until transistor M1 is turned ON again. ECE 442 Power Electronics

11 Waveforms for the Boost RegulatorECE 442 Power Electronics

12 Summary for the Boost RegulatorThe peak-to-peak ripple current is The peak-to-peak ripple voltage is ECE 442 Power Electronics

13 Summary for continuous current caseThe critical value of the inductor is The critical value of the capacitor is ECE 442 Power Electronics

14 Buck-Boost Regulator The output voltage could be less than or greater than the input voltage The polarity of the output voltage is opposite to the polarity of the input voltage Vs – Inverting Regulator ECE 442 Power Electronics

15 Mode 1 Operation – Q1 turned ONInput current flows through inductor L and Q1 linearly. ECE 442 Power Electronics

16 Mode 2 Operation – Q1 switched OFFCurrent flowing through L now flows through L, C, Dm and the Load. ECE 442 Power Electronics

17 Waveforms for the Buck-Boost RegulatorECE 442 Power Electronics

18 Summary for the Buck-Boost RegulatorThe peak-to-peak ripple current is The peak-to-peak ripple voltage is ECE 442 Power Electronics

19 Summary for continuous current caseThe critical value of the inductor is The critical value of the capacitor is ECE 442 Power Electronics

20 Converter with a highly inductive LoadInput Current is “pulse” shaped ECE 442 Power Electronics

21 Connect an input filterFilter out the converter-generated harmonics from the supply line. ECE 442 Power Electronics

22 Equivalent circuit for the converter-generated harmonic currentsECE 442 Power Electronics

23 Example 5.10 ECE 442 Power Electronics

24 Buck Chopper for PSpice SimulationECE 442 Power Electronics

25 Results from PSpice ECE 442 Power Electronics

26 Fourier Coefficients of the input currentECE 442 Power Electronics

27 Example 5.10 in MultiSim ECE 442 Power Electronics

28 ECE 442 Power Electronics

29 Fourier Coefficients of the Input CurrentECE 442 Power Electronics

30 ECE 442 Power Electronics

31 ECE 442 Power Electronics

32 ECE 442 Power Electronics