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Switching-Mode Regulators

Switching-Mode Regulators. Convert an unregulated DC voltage into a regulated DC voltage. Buck Regulator. Output Voltage is Less Than the Input Voltage. BJT Chopper L-C Filter Load.

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Switching-Mode Regulators

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  1. Switching-Mode Regulators Convert an unregulated DC voltage into a regulated DC voltage ECE 442 Power Electronics

  2. Buck 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 ON Input current flows through L, C, and the Load – rises linearly ECE 442 Power Electronics

  4. Mode 2 Operation – Q1 switched OFF Inductor 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 Regulator ECE 442 Power Electronics

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

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

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

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

  10. Mode 2 Operation – M1 switched OFF Current 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 Regulator ECE 442 Power Electronics

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

  13. Summary for continuous current case • The 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 ON Input current flows through inductor L and Q1 linearly. ECE 442 Power Electronics

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

  17. Waveforms for the Buck-Boost Regulator ECE 442 Power Electronics

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

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

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

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

  22. Equivalent circuit for the converter-generated harmonic currents ECE 442 Power Electronics

  23. Example 5.10 ECE 442 Power Electronics

  24. Buck Chopper for PSpice Simulation ECE 442 Power Electronics

  25. Results from PSpice ECE 442 Power Electronics

  26. Fourier Coefficients of the input current ECE 442 Power Electronics

  27. Example 5.10 in MultiSim7 ECE 442 Power Electronics

  28. ECE 442 Power Electronics

  29. Fourier Coefficients of the Input Current ECE 442 Power Electronics

  30. ECE 442 Power Electronics

  31. ECE 442 Power Electronics

  32. ECE 442 Power Electronics

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