Current reconstruction method with single DC-link current sensor based on the PWM inverter and AC motor

This paper proposes the new current reconstruction method of three-phase currents in case of using dc-link shunt resistor for three-phase AC motor. When dc-link shunt resistor is used for the acquisition of phase currents, there are the immeasurable regions in the hexagon of Space Vector Pulse Width Modulation(SVPWM). The conventional methods used the shift of the switching patterns of SVPWM to extend the region of the measurable area from the immeasurable area. Thus, these methods cause the audible noise, the current distortion and deteriorate the control performance of the motor drive system. The proposed method uses the current equations of the combined equivalent circuits of the PWM inverter and AC motor according to the switching patterns of the PWM inverter. This method can reconstruct three-phase current without the shift of the switching pattern of SVPWM and producing the audible noise. The effectiveness of the proposed algorithm is verified through computer simulation and the experimental results.