A Method of the SVPWM Pulse Over-modulation Based on Carrier Modulation and Its Implementation

Abstract

In order to expand the operating speed range of wind turbines, reduce losses for the turbine units, and increase power generation, a SVPWM (space vector pulse width modulation) pulse over-modulation method based on carrier modulation is proposed in this paper. The method detects the modulation level of inverter output voltage and the speed of the permanent magnet motor in real time, and corrects the non-linear region of the SVPWM modulation waveform based on its modulation level and speed to ensure the maximum fundamental voltage output. At the same time, judging and calculating the interval and action time of the vector are unnecessary, and the judgment and calculation of the partition are simple. In addition, it is fully compatible with the carrier modulation method of the linear modulation region, and the modulation of intervals can transit smoothly, making it easy for engineering implementation. This method is applied to the operating conditions of permanent magnet wind turbines. The experimental results show that the operating speed range of the optimal power control of the turbines unit has been expanded by about 4%, and its effectiveness and practicality are verified.

Keywords

• carrier-modulation
• svpwm
• permanent magnet generator
• over-modulation
• non-linear modulation