TW200701609A - High-efficiency single-stage bidirectional converter with multi-input power sources - Google Patents

Abstract

The aim of this invention focuses on the development of a high-efficiency single-stage bidirectional converter with multi-input power sources. Owing to future power systems with various power sources and clean energies without energy storage capability, batteries are usually taken as auxiliary powers when clean energies are applied to distributed generation systems. By this way, it needs multiple or multistage power converters in order to achieve the objective of united power supply. However, excess circuit elements and multistage power conversion will result in degenerate conversion efficiency. In this invention, it takes a three-winding coupled inductor as the main component of energy transmission, and utilizes only two power semiconductor switches to accomplish the multi-input mechanism. According to the scheduled switching conditions, this circuit could be operated at discharge, charge and standalone states to simplify traditional multiple boost converters in the grid connection scheme. Moreover, the coupled inductor as the principal part of this circuit has high-voltage gain property, and this invention adequately utilizes the winding voltage in the high-voltage side to further increase the corresponding voltage gain superior to that one in the conventional coupled-inductor strategy. This property is helpful to solve the power conversion problem induced by clean energies with inherent low-voltage characteristics. In addition, all switches and diodes have favorable voltage-clamped results so that the voltage spikes induced by the leakage-inductor energy can be alleviated effectively, and there are no high reverse-recovery currents within diodes because the leakage inductor has the limited capability of current speedy changes. Furthermore, this strategy possesses a low-voltage-type charge circuit without increasing additional circuit elements to avoid the power losses induced by the multistage conversion in the traditional auxiliary power systems, and utilizes the synchronous rectifier technique to further decrease the conduction losses. Consequently, the circuit topology in this invention can achieve the ultimate goal of high-efficiency single-stage bidirectional power conversion with multi-input power sources because the devices with low conduction losses can be adopted in the low-voltage side with high current, and there is no high voltage spikes and stresses in the high-voltage side with low current.