Research On Direct Power Control Of Dual PWM Converter

Dual PWM converter has a good application prospect in fields such as newenergy grid and motor drive, as it has advantages of bidirectional power flow, lowharmonic distortion of AC side current, constant DC side voltage, unity power factor,etc. The control strategies of grid-side PWM rectifier and motor-side PWM inverterare studied respectively in this paper.Based on the theory of instantaneous power, the power mathematical model ofPWM rectifier is established and the power flow character is analyzed in detail. Toimprove both the steady and dynamic performance,18non-fixed sectors are dividedand a scheme named predict direct capacitor power control (P-DCPC) is analyzed anddesigned. Results of simulation prove the validity of this method.As for the direct torque control under (maximum torque per ampere) MTPA ofpermanent magnet synchronous motor (PMSM), based on theory of variable structuresliding mode, a new slide-mode is designed to improve the speed of response andsteady-state performance of torque. To reduce the chattering and maintain therobustness，an improved exponent reaching law was applied to control the torque. Torealize the estimation of load power and DCPC of dual PWM converter, the inverterand the motor are treated as a whole part. To improve both the dynamic performanceand robustness of the dual PWM converter, a new control strategy named directcapacitor power control based on sliding mode variable structure (SMC-DCPC) isproposed.Finally, Comparative experiments are carried out and experimental results showthat dual PWM converter has a better performance and application prospect.