一种新的电压型PWM整流器直接功率控制策略

A NEW DIRECT POWER CONTROL STRATEGY OF THREE PHASE BOOST TYPE PWM RECTIFIERS

该文通过电压型PWM整流器的数学模型,分析了现行直接功率控制(DPC)系统的原理及性能。由于DPC系统功率内环采用一个开关表同时控制瞬时有功功率和无功功率,导致暂态过程中功率、直流电压出现了较大的波动;同时,在负载电流扰动时会产生较大的直流动态压降。对此,提出了交替采用有功功率开关表和无功功率开关表的双开关表控制新策略,可提高系统的动、静性能;同时,在负载电流扰动时,通过负载电流反馈控制双开关表转换信号的占空比,可减少直流动态压降或消除稳态直流压降。仿真和实验结果,证实了双开关表控制策略的可行性。

This paper analysies the principle and properties of the direct power control （DPC） system for present three phase boost type PWM rectifiers based on its mathematical model. Switching table in power loop of DPC system controls instantaneous active power and reactive power ,leading to the fluctuation of power and DC voltage in temporary state and DC dynamic voltage drop during load current disturbance. This paper presents a new direct power control strategy based on alternate use of instantaneous active power and reactive power switching tables. Good control properties are achieved by the new control strategy. Meanwhile, DC dynamic voltage drop during load current disturbance is decreased and stable voltage drop is eliminated by the duty cycle of square wave to control double switching table based on load current feedback. The new control strategy is proved feasible by simulink and experiment.