Three-phase power conversion using soft-switching PWM techniques

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Virginia Tech


This dissertation addresses several key issues related to high-frequency soft-switching PWM three-phase power converters. These are:

  1. Analysis, synthesis, and design of three-phase soft-switching PWM power converter topologies
  2. Design of input EMI filters for three-phase converters
  3. Design of microprocessor controllers for three-phase converters.

An analysis of existing soft-switching PWM techniques is performed, and two generalized soft-switching PWM converter circuit representations are derived.

Based on these representations and common topological properties of three-phase and dc-dc PWM converters, two new procedures for synthesis of three-phase soft-switching PWM converters are derived. The two procedures are used to synthesize five new three-phase soft-switching PWM converter topologies suitable for wide range of applications.

A digital signal processor-based controller implementation example is presented. It demonstrates the feasibility of producing versatile, high performance, reliable, low-cost digital controllers for soft-switching PWM three-phase power converters operating at high switching frequencies.

A new approach to the design of input filters for ac power electronic circuits is presented here. This approach is based on the application of a vast body of knowledge about passive L-C filters that has existed for many years, but has not been used in power electronics. New passive and active filter pole damping schemes are applied to high-order elliptic filters, resulting in significant filter size reduction compared to the standard filter designs.