并联全桥LLC谐振变换器直流母线电压控制方法

DC Bus Voltage Control Method for Paralleled Full-bridge LLC Resonant Converter

为了解决并联全桥LLC谐振型DC-DC变换器直流母线电压控制问题,提出了一种基于半桥/全桥结构切换的控制策略。在轻载的工况下通过改变开关管驱动信号,将全桥LLC转化为半桥LLC,解决了在光伏储能微电网中直流母线电压无法精确控制的问题。同时利用电压死区控制器和电流死区控制器,达到直流母线电压控制和两路并联均流的效果。为了验证方法的正确性和有效性,利用7 k W样机进行了实验验证。结果显示,该方法有效降低了电压纹波,缩短了负荷投切时的电压调节时间,并实现了两路并联均流。

To solve the DC bus voltage control problem of paralleled full-bridge LLC resonant converter,a controlscheme based on the switching between a half-bridge LLC and a full-bridge LLC is proposed. Under light load condi-tions,the full-bridge LLC is transformed into the half-bridge LLC through changing the drive signals of switches,whichregulates the DC bus voltage accurately in a photovoltaic/energy storage system. Meanwhile,through utilizing the volt-age dead-band controller and current dead-band controller,the DC bus voltage is regulated and the currents are sharedbetween two LLC resonant converters. To verify the proposed method,tests were carried out using a 7 kW prototype.The results show that the proposed method can reduce the voltage ripple and the regulation time of voltage during loaddisturbance,and realize current sharing between two paralleled LLC resonant converters.