Selective harmonic eliminated and synchronous optimal pulse width modulation for a single-phase PWM rectifier in traction applications

High-power single-phase PWM rectifiers for medium voltage drives operate at low switching frequency to maintain the switching losses of the power semi-conductor devices at an acceptable level. For these applications, selective harmonic eliminated pulse width modulation and synchronous optimal pulse width modulation methods permit a good trade-off between switching losses and harmonic distortion of grid side input currents. The control scheme includes voltage outer-loop and current inner-loop. A fast proportional resonant phase angle estimator is presented. Experimental results obtained from a 50 kVA prototype operated at only 350Hz switching frequency demonstrate the effectiveness of these approaches.