The Design Of Digital Active Power Factor Corrector In Integrated Bldc Control System

The traditio nal brushless DC motor (BLDCM) driving control system willcause the grid harmonic pollution, even affecting other electrica l equip ment towork properly in the same grid, thus this paper designs a BLDCM driving controlsystem with power factor correction function.Single switc h BOOST-TYPE power factor correction (PFC) is introduced toeliminate power grid harmo nic pollution in fan motors contro l system, however,the current zero-crossing distortion affects PFC performance. To solve thisproblem, a new current zero-crossing distortion suppression method and itsconcrete imp leme ntatio n are proposed in this paper. Digital contro l is adoptedand duty ratio feed-forward compensatio n is introduced to reduce the disturbanceof inp ut voltage and output volta ge on the inductor current, forcing the inputcurrent fo llows the input volta ge changes; the input impedance is ana lyzed toshow that duty ratio feed-forward compensatio n can inhib it the current phaseadvance; A current samp ling method is proposed to get the average current bysampling twice per PWM period. Simulation and experime nt results indicate theproposed method can inhib it current phase advance, achieve unity power factorcorrection and verify the validity of the proposed method.A three-phase six switching APFC techno logy is used for high-powerBLDCM drive syste m. This paper first derives the mathe matical model o f thethree-phase VSR in the three-phase stationary coordinate system and thetwo-phase rotating coordinate system. Then according to dq coordinate systemmathe matical model, the current decoupling control strategy is proposed which isbased on volta ge feed-forward. Simulation results demonstrate that the use ofthis kind of algorithm can cause three-phase input current to reach a higherpower factor, and effective ly reduce the inp ut current distortion. As for theproblem o f excessive sensor, the paper also proposes a virtual flux-orientedvector control method. With this k ind of contro l method the gird vo ltage sensorsare eliminated, and simulation results show that the virtual flux oriented controlmethod can achie ve almost the same control effect as traditiona l volta gefeed-forward current decoupling control method.