The Technology Research Of Common Mode Voltage Reduction In The SVPWM Drive System

In recent, in the ac variable frequency speed regulation system, because thecontrol of the voltage space vector PWM (SVPWM) control strategy is sim-ple,and it is easy to the realization of digital control of variable frequency speedregulation system, and the SVPWM have adopted a more optimized control strat-egy, namely seem the inverters and ac motor as a whole, according to the threephase motor stator produce trace round rotating magnetic field to control the in-verter work, under this control strategy,not only can improve the utilization rateof dc side voltage, and calculate simplely, reduces the loss of the switching, andthen, reduce the harmonic loss of the motor, reduced torque pulsation, thereforehas been widely used.However, along with the wide application of this control strategy, the problesuch as the surface of the motor bearing place is not smooth, sparking, openwelding and metal surface corrosion,aging. this is because of the control strategy,can produce a maximum amplitude for Vdccommon-mode voltage (dc bus volt-age),cause bearing insulation effect of the lubricant is punctured led on the motorshaft to corresponding shaft voltage and shaft current, lead to premature aging ofthe motor.This paper proposes a new control algorithm strategy, by applying the syn-chronization control inverter SVPWM control strategy of rectifier and inverterside, let the cycle of the rectifier side of the converter and inverter side and cen-ter of synchronization, remove amplitude for±Vdc, plus or minus common-modevoltage±2Vdc/3, then through the new SVPWM control strategy implemented tocommon-mode voltage of the inverter control within the±Vdc/3, prevent prema-ture aging of the motor. The simulation results verify the effectiveness of theproposed design method.