New single-phase power factor correction circuits and design of high efficiency DC/DC converter for distributed power system

Abstract

Over the last decade, there have been a great deal of researchs on the rectification circuit to meet the IEC555-2 requirements. The rectifiers employing the conventional pulse-width-modulated(PWM) converter are mainly investigated. However, operation in continuous mode is accompanied with a current and voltage spike due to a hard switching. This increases switching loss and the level of EMI, thus, operational frequency and power density are limited. Furthermore, there exists an inherent disadvantage like the uncontrollable range when the output voltage is below the peak value of the source voltage. This results in the start-up inrush current as well as over load current. Firstly, to effectively deal with these problems of PWM type converters, a quantum series resonant converter is applied to the push-pull series resonant rectifier(PPSRR), which have the same global characteristics as with conventional boost AC to DC converter and low switching losses. However, there are some inherent disadvantages in quantum resonant converter applied to PPSRR such as the quantized output voltage level, larger current ripple, and uncontrollable ranges. The quantized output voltage level and larger current ripple basically come from the fixed period of the control cycle. As a possible effective way of dealing with these problems, a predictive current control technique is employed, and thus a near optimum control input with respect to current harmonics is obtained. To overcome the another disadvantage like the uncontrollable range when the output voltage is below the peak value of the rectified line voltage in the boost type topologies, the buck operation should be employed for the improved control performance and system design optimization during the start-up transient periods and load fault condition. The buck operation is very useful for safe operation and extending the output voltage range below the peak value of the source voltage. Using this kind of switched operation techn...