全桥隔离DC/DC变换器相移控制归一化及其最小回流功率控制

Normalization of Phase Shift Control and Minimum Reflux Power Control of Full-bridge Isolated DC/DC Converters

全桥隔离DC/DC变换器是未来无工频牵引变压器电力牵引传动系统的一个重要组成部分。重点研究其广泛采用的相移控制方法。首先,提出一种三重相移控制方法,分析该方法与已有相移控制方法的内在联系,统一全桥隔离DC/DC变换器的相移控制方法;其次,为提高系统效率,全面分析变换器中存在的回流功率,并给出最小回流功率控制方法,通过引入一个中间变量,该方法相对于已有控制算法,无需负载侧电流传感器,并有效地降低了控制系统运算复杂度;最后,研制1.5 k W小功率实验平台并进行实验验证,实验结果表明,所提出的最小回流功率控制方法在额定功率附近显著减小了系统回流功率,提高了系统的效率。

A full-bridge isolated DC/DC converter is a key part of transformerless AC traction drive system in railway application. This paper focused on the phase-shift control methods, which are commonly used in full-bridge isolated DC-DC converter. Firstly, a triple-phase-shift control method was proposed, and the internal relationship among phase shift control methods was analyzed. According to the triple-phaseshift control method, all phase shift control methods were unified. Secondly, in order to improve system efficiency, the reactive power was analyzed roundly, and a minimum reflux power control method was shown without the load-side current sensor and the complex operations by defining and using an intermediate variable. Finally, these control methods were verified in a 1.5 k W power experiment platform. Experimental results show that reflux power is reduced effectively by using the minimum reflux power control method, and the system efficiency is improved obviously around the rating output power.