【摘要】 在此以三相Buck整流器级联Buck DC/DC变换器为研究对象,研究了三相输入不平衡时,降低输入电流总谐波失真(THD)的方法。通过推导电流型空间矢量脉宽调制三相Buck整流器开关管导通时间表达式,分析了三相Buck整流器输出功率脉动与输出母线(BUS)电容之间的关系。详细分析了开关管电压应力、电流应力以及LC滤波器的参数,为优化系统设计提供理论依据。级联系统中,前级三相Buck整流器采用电压环控制,后级Buck DC/DC变换器采用电压外环-电流内环双环反馈控制和BUS电容电压前馈控制,电流内环采用比例准谐振控制。最后,通过600 W实验样机对理论分析进行验证。研究结果表明,三相输入电压不平衡时,通过合理设计BUS电容等电路参数,优化系统控制方法,能有效抑制输入电流的THD。更多还原

【Abstract】 Taking three-phase Buck rectifier cascaded with Buck DC/DC converter as research object,the method which can decrease the total harmonic distortion(THD)of input current under three-phase input voltage unbalanced is studied.The expression for on-time of power transistors,using current-mode space vector pulse width modulation,is derived.And then,the relationship between BUS capacitor and output power ripple of three-phase Buck rectifier is analyzed.Moreover,the analysis of voltage and current stress for power transistors and the parameters for LC filter are presented,which provides theoretical guidance in optimizing the system design.The voltage control loop is used in former three-phase Buck rectifier.The latter Buck DC/DC converter used both voltage-current loop and BUS capacitorvoltage feedforward control,in which used the proportional quasi-resonance control.Finally,a 600 W experimental platform is built to verify the theoretical analysis.The research results show that the reasonable parameter design and optimized control method can effectively restrain the increase of input current THD when the three-phase input voltages are unbalanced.更多还原