Direct Power Control Strategy of PWM Rectifier Based on Improved Virtual Flux-Linkage Observer

In order to achieve the low cost and high performance control of three-phase pwm rectifier,a direct power control (dpc) strategy based on a new-style virtual flux-linkage observer is proposed. the model of three-phase pwm rectifier and the principle of virtual flux-linkage vector control are introduced firstly. then,in order to avoid the effect of integral initial value and cumulative deviation,three first-order low-pass filters are cascaded to replace the pure integral link; an improved virtual flux-linkage observer of three-phase power grid is presented. from the observed virtual flux-linkage,the voltage and instantaneous power of three-phase power grid are online estimated. on this basis,the power grid voltage sensorless direct power control system of three-phase pwm rectifier is designed. simulation results have shown that,both in the rectifying state and in the inverting state,the power grid side current and the dc side voltage of three-phase pwm rectifier all can be effectively controlled; the high power factor operation of three-phase pwm rectifier is realized. © 2017 wenshao bu and leilei xu.