Analysis of single phase rectifier circuits

Author: Lazar, James Frederick

Year: 1997

Degree: Dissertation (Ph.D.)

Advisors: Cuk, Slobodan; Middlebrook, Robert David

Committee Member: Unknown, Unknown

Option: Electrical Engineering

DOI: 10.7907/ZWBE-EV76

Abstract

The preponderant application of rectifier circuits is the powering of dc loads from the ac utility line. Ordinary rectifier circuits present a nonlinear load impedance to the utility line, thereby generating harmonic currents, and contributing to the harmonic current problem. There are many active and passive rectifier circuits offering reduced harmonic currents, and in this work a methodology is developed by which these circuits may be analyzed and compared.

Rectifier circuits can be classified as either active or passive. A passive rectifier circuit contains passive components (inductors, capacitors, saturable reactors, etc.), and passive switches (rectifier diodes) only. Active rectifier circuits use at least one controllable active switch (power transistor), in addition to passive switches and passive components. The performance characteristics of these circuits can be assessed with respect to a fictional device called the ideal rectifier. This assessment allows direct comparison of various approaches, passive or active, using the ideal rectifier as the common reference. Rectifier circuit performance may also be compared against specified requirements.

The next topic considered is the analysis of active rectifier circuits employing a pwm (pulse width modulation) converter as a means to control power flow within the rectifier circuit. The pwm converter is modeled using the pwm switch method. A large-signal nonlinear pwm switch model is used for modeling large-signal rectifier circuit behavior, and models are developed for operation in either the continuous or discontinuous conduction mode. Similarly, a small-signal model is developed for small-signal considerations. In addition, for pwm converters operating in the continuous conduction mode, the effect of lossy resistive elements inside the converter are accounted for in the pwm switch model, and this modeling technique is shown to give results identical to those obtained via the state-space averaging method.

The methods developed are then applied to the analysis of the boost rectifier operating in the discontinuous conduction mode. Three control schemes are compared, each offering a different compromise between circuit complexity and performance. Finally, a design example is given, and experimental results are provided.

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