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Efficiency Improvement of a PWM Rectifier Using Soft Switching and Redesign of the Modified Converter

Haghi, Rasool | 2011

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 41760 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Zolghadri, Mohammad Reza
  7. Abstract:
  8. In this project, the Line-Modulated Fixed Off-Time method is used as the current control strategy for a Power Factor Corrector (PFC) pre-regulator. A zero voltage switching PWM (ZVS-PWM) auxiliary circuit is configured to perform ZVS in the switches. To reduce conduction losses, the rectifier circuit and the PFC are combined to create bridgeless PFC and a new zero-voltage-switching is introduced for reduse switching loss. Soft commutation of the main switch with zero voltage is achieved without additional current stress. When main switch is turned off ,the voltage across the switch rises very slowly. when the current of the switch decays to zero the voltage across the switch is very low.A new procedure for design the auxiliary circuit is introduced. To verify the feasibility of the proposed converter a prototype, is realized, with same specifications as used in the design example. A 250W, with an input ac voltage of 90-265 Vrms, have been designed and implemented to verify the system performance. This converter has higher efficiency than the conventional PWM hard-switching counterpart because of soft switching and lower conduction loss in the power flow path during rectification. a prototype switching at 100 kHz, efficiency is improved by about 2.7% with respect to hard-switching counterpart. is desired to reduce the volume and weight of a converter by increasing the switching frequency. In this project reduce the volume and weight of a converter by increasing the switching frequency is described.

  9. Keywords:
  10. Soft-Switching ; Pulse Width Modulation (PWM) ; Power Factor Correction ; Bridgeless Structure ; Line Modulated Fixed Off Time (LM-FOT)

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