A minimum voltage vector error modulation assisted by a current reference modification for the PMSM drive

Although the minimum voltage vector (VV) error (MVE) is an efficient VV modulation scheme for reducing the driver switching loss, the applied MVE vector is not the exact reference for the voltage control. There is an essential error between the reference VV and the applied VV, even this error has been minimized. In this paper, this issue is investigated as a nonlinear uncertainty in the machine's current control loop and cannot be solved by a regular disturbance resistance method. This paper proposes a current reference modification method. The electrical current error induced by the MVE can be predicted, and then this error prediction can be applied to adjust the current reference. With this reference modification (RM), the final electrical current output is with an error to the modified reference, but closer to the original electrical current reference. This method is called RM_MVE in this paper. Experimental comparisons between the regular MVE and RM_MVE methods are conducted on a 4.7 kW PMSM platform. Experimental results demonstrate: Phase current THD decreased from 21.96 % (MVE) to 6.56 % (RM_MVE) at 500 r/min. Motor efficiency increased from 78.75 % to 81.25 % at 500 r/min, and total system efficiency rose by 2.44 %. These enhancements confirm the effectiveness of RM in suppressing modulation nonlinearity without compromising inverter efficiency.