Unity power factor operation and output controller design of quantum boost series resonant rectifier (QBSRR)

Abstract

There have been a great deal of recent researches on the rectification circuit due to the increasing demand for the high power quality in the AC line. Among them, the boosting feature of the pulse-width-modulated (PWM) hard-switched converters are mainly used. However, this type of circuit has the limited switching frequency due to the high switching losses in the devices. Therefore, soft-switched resonant type circuit is more desirable in view of the high power density since it eliminates the switching losses to a great extent such that the switching frequency can be increased. Among of the reported resonant circuits, one interesting topic is a quantum series resonant converter (QSRC) which can provide the zero current switching conditions, ease of control, and linear characteristics like the conventional PWM converters. Based on this type of converter, a new AC-to-DC conversion circuit named as a quantum boost series resonant rectifier (QBSRR) is proposed in this dissertation to obtain the high power factor. In general, due to the voltage step-down characteristics, the AC-to-DC rectifier using the series resonant circuit has the problem when the output voltage falls below the line voltage. As a possible way of dealing with this problem, the proposed rectifier employs the additional switch and hence it has the boosting feature. Furthermore, since a QBSRR has the half-bridge topology, a wide range of output voltage are available, i.e. above half the input peak voltage. In addition to the suggestion of a new rectification circuit, the another purpose of this paper is to construct the accurate closed-loop model for the controlled system which gives the intuition of the closed-loop system dynamics. Since the rectifier employs the rectified sinusoidal waveshape as the input source voltage, the 120Hz ripple component is appeared in the output voltage. In order to obtain the stable output voltage regardless of this 120Hz ripple component, the digital PI-controller ...