1 / 38

Chapter 10 Switching DC Power Supplies

Chapter 10 Switching DC Power Supplies. One of the most important applications of power electronics. Linear Power Supplies. Very poor efficiency and large weight and size. Switching DC Power Supply: Block Diagram. High efficiency and small weight and size.

calista-osborne
Download Presentation

Chapter 10 Switching DC Power Supplies

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 10 Switching DC Power Supplies • One of the most important applications of power electronics Chapter 10 Switching DC Power Supplies

  2. Linear Power Supplies • Very poor efficiency and large weight and size Chapter 10 Switching DC Power Supplies

  3. Switching DC Power Supply: Block Diagram • High efficiency and small weight and size Chapter 10 Switching DC Power Supplies

  4. Switching DC Power Supply: Multiple Outputs • In most applications, several dc voltages are required, possibly electrically isolated from each other Chapter 10 Switching DC Power Supplies

  5. Transformer Analysis • Needed to discuss high-frequency isolated supplies Chapter 10 Switching DC Power Supplies

  6. PWM to Regulate Output • Basic principle is the same as discussed in Chapter 8 Chapter 10 Switching DC Power Supplies

  7. Flyback Converter • Derived from buck-boost; very power at small power (> 50 W ) power levels Chapter 10 Switching DC Power Supplies

  8. Flyback Converter • Switch on and off states (assuming incomplete core demagnetization) Chapter 10 Switching DC Power Supplies

  9. Flyback Converter • Switching waveforms (assuming incomplete core demagnetization) Chapter 10 Switching DC Power Supplies

  10. Other Flyback Converter Topologies • Not commonly used Chapter 10 Switching DC Power Supplies

  11. Forward Converter • Derived from Buck; idealized to assume that the transformer is ideal (not possible in practice) Chapter 10 Switching DC Power Supplies

  12. Forward Converter: in Practice • Switching waveforms (assuming incomplete core demagnetization) Chapter 10 Switching DC Power Supplies

  13. Forward Converter: Other Possible Topologies • Two-switch Forward converter is very commonly used Chapter 10 Switching DC Power Supplies

  14. Push-Pull Inverter • Leakage inductances become a problem Chapter 10 Switching DC Power Supplies

  15. Half-Bridge Converter • Derived from Buck Chapter 10 Switching DC Power Supplies

  16. Full-Bridge Converter • Used at higher power levels (> 0.5 kW ) Chapter 10 Switching DC Power Supplies

  17. Current-Source Converter • More rugged (no shoot-through) but both switches must not be open simultaneously Chapter 10 Switching DC Power Supplies

  18. Ferrite Core Material • Several materials to choose from based on applications Chapter 10 Switching DC Power Supplies

  19. Core Utilization in Various Converter Topologies • At high switching frequencies, core losses limit excursion of flux density Chapter 10 Switching DC Power Supplies

  20. Control to Regulate Voltage Output • Linearized representation of the feedback control system Chapter 10 Switching DC Power Supplies

  21. Forward Converter: An Example • The switch and the diode are assumed to be ideal Chapter 10 Switching DC Power Supplies

  22. Forward Converter:Transfer Function Plots • Example considered earlier Chapter 10 Switching DC Power Supplies

  23. Flyback Converter:Transfer Function Plots • An example Chapter 10 Switching DC Power Supplies

  24. Linearizing the PWM Block • The transfer function is essentially a constant with zero phase shift Chapter 10 Switching DC Power Supplies

  25. Gain of the PWM IC • It is slope of the characteristic Chapter 10 Switching DC Power Supplies

  26. Typical Gain and Phase Plots of the Open-Loop Transfer Function • Definitions of the crossover frequency, phase and gain margins Chapter 10 Switching DC Power Supplies

  27. A General Amplifier for Error Compensation • Can be implemented using a single op-amp Chapter 10 Switching DC Power Supplies

  28. Type-2 Error Amplifier • Shows phase boost at the crossover frequency Chapter 10 Switching DC Power Supplies

  29. Voltage Feed-Forward • Makes converter immune from input voltage variations Chapter 10 Switching DC Power Supplies

  30. Voltage versus Current Mode Control • Regulating the output voltage is the objective in both modes of control Chapter 10 Switching DC Power Supplies

  31. Various Types of Current Mode Control • Constant frequency, peak-current mode control is used most frequently Chapter 10 Switching DC Power Supplies

  32. Peak Current Mode Control • Slope compensation is needed Chapter 10 Switching DC Power Supplies

  33. A Typical PWM Control IC • Many safety control functions are built in Chapter 10 Switching DC Power Supplies

  34. Current Limiting • Two options are shown Chapter 10 Switching DC Power Supplies

  35. Implementing Electrical Isolation in the Feedback Loop • Two ways are shown Chapter 10 Switching DC Power Supplies

  36. Implementing Electrical Isolation in the Feedback Loop • A dedicated IC for this application is available Chapter 10 Switching DC Power Supplies

  37. Input Filter • Needed to comply with the EMI and harmonic limits Chapter 10 Switching DC Power Supplies

  38. ESR of the Output Capacitor • ESR often dictates the peak-peak voltage ripple Chapter 10 Switching DC Power Supplies

More Related