S.C. Yip

On the use of current sensors for the control of power converters

This paper describes the use of current sensors for the control of power converters. No voltage sensor is required in the whole system. The sensed current and the rate of change of the inductor current in different circuit topologies are used to determine the input and output voltages of the converters, and for current programming and maximum current protection. Apart from reducing the number of sensors, the proposed method provides inherent electrical isolation between the power conversion stage and the controller and lessens noise-coupling problems. The proposed technique is illustrated with a current-programmed DC/DC boost regulator with feedforward and feedback control. The regulators steady state and transient responses under input source and output load disturbances are presented.

Single current sensor control for single-phase active power factor correction

This paper presents the realization of a boost-type active power factor corrector (APFC) using a single current sensor to sense the inductor current for input current shaping and output voltage regulation. Neither input voltage nor output voltage sensing is needed. The sensed inductor current is used for two main functions. The first one is for comparing with a sawtooth signal in order to shape the input current waveform. The second one is for determining the input and output voltages by processing the rate of change of the inductor current when the main switch is in on and off states, respectively. Compared with conventional APFCs, the proposed technique has several advantages. First, no dissipative voltage divider is required. Second, electrical isolation between the power conversion stage and the control stage can be achieved inherently. Finally, no complicated or sophisticated digital sampling and numerical computations are needed. The applicability and accuracy of the proposed technique have been studied experimentally. Steady-state behavior and large-signal response under output load disturbance are also investigated.

A unified control scheme for a bi-directional AC-DC converter with high power quality

This paper presents the modeling, analysis, and design of a thyristor-based AC-DC converter, featuring bidirectional power flow and unity power factor at the AC side in both powering and regenerating modes. The unified controller regulates the voltage at the DC side and operates as a feedback control in the powering mode and a feedforward control in the regenerating mode. Systematic procedures for designing the power conversion stage and the controller are given.

MODELING, ANALYSIS AND DESIGN OF A THYRISTOR-BASED BI-DIRECTIONAL ac–dc CONVERTER

This paper presents the modeling, analysis, and design of a thyristor-based ac–dc converter, featuring bi-directional power flow and unity power factor at the ac side in both powering and regenerating modes. By applying the y-parameter modeling technique and eliminating the effects of the high-frequency poles and zeros, small-signal models of the converter in both modes and a unified controller have been developed. The controller regulates the voltage at the dc side and operates as a feedback controller in the powering mode and a feedforward controller in the regenerating mode. Systematic procedures for determining the circuit component values of the power conversion stage and the controller are presented. The operation is illustrated with the design of a 500-W, 100-V (ac)/200-V (dc) prototype, supplying to a motor-generator set. Experimental results showing operation in the powering mode, regenerating mode, and during mode changeover are included. Circuit operations during the transient of the changeover operation are clearly identified.

A bi-directional induction motor drive with high power quality

This paper presents the modeling, design, and analysis of a thyristor-based, current-controlled bi-directional AC-DC converter. The converter is not only capable of featuring bi-directional power flow, but also offers unity power factor and a near sinusoidal current waveform at the AC side in both powering and regenerating modes. By applying the y-parameter modeling technique, small-signal models of the converter and a unified feedback controller circuit for both modes are derived. Systematic procedures for determining the circuit components in the power conversion stage and the feedback controller are described. The operation is illustrated with the design of a 500 W, 100 V(AC)/200 V(DC) prototype converter, supplying to a voltage fed induction motor drive. Experimental results showing operation in the powering mode, regenerating mode and during mode changeover are given, confirming the feasibility of the proposed design technique and the operation of the converter.