Current beat suppression of non-electrolytic capacitor variable frequency driver based on multi-rotating PI

In a variable frequency drive system without electrolytic capacitor, the bus voltage fluctuates periodically due to the decrease of the bus capacitance. The current beat frequency phenomenon generally occurs when the frequency of the output voltage of the inverter is similar to the fluctuation frequency of the bus voltage. A multi-rotation PI harmonic suppression method is proposed to suppress the current beat frequency of non-electrolytic capacitor variable frequency driver. This method takes dq coordinate system as reference, uses the characteristics of fundamental current in dq coordinate system, builds a current closed loop under rotating coordinate system respectively, extracts the main harmonic current, and represses harmonic current through multi-rotating PI method, so that the harmonic in winding current can be suppressed, thus suppressing the motor beat frequency phenomenon. Through simulation and theoretical deduction, this method can obtain better beat suppression effect in non-electrolytic capacitor variable frequency driver, and the control structure is simpler, the parameter tuning and engineering implementation are easier.