An improved two-phase PWM strategy for inverters in electric vehicle

An improved pulse-width modulation (PWM) strategy with two-phase modulation is proposed for inverters in electric vehicle. By properly selecting the clamping phase in each PWM cycle, no switching occurs when the corresponding phase current is around its peak value, thus the switching loss will be significantly reduced. Meanwhile, the peak-to-peak value of the common-mode voltage (CMV), which leads to the premature deterioration of motor bearings, is reduced to 1/3 of the traditional three-phase PWM method in each sector. Furthermore, the harmonic distortion characteristic is also improved comparing with other PWM techniques for CMV reduction. Just a little software is needed for implementing the proposed strategy and the method can be widely applied. Experimental results are presented to fully support the above-mentioned claims.