Design and implementation of SVPWM switching power amplifiers for active magnetic bearing

The magnetic bearing biased by permanent magnetic body needs bipolar current, so the full-bridge structure is often used in its switching power amplifier. The conventional full-bridge power amplifier has many power-tubes in magnetic bearing system, and this will leads more power-loss and less reliability. In this paper, a 3-leg switching power amplifier circuit is adopted to realize the SVPWM modulator approach using the digital system which includes DSP and FPGA. The test results indicate that this method can reduce the eddy-current-loss remarkably due to the reduction of current ripple relative to the two-level method, and can reduce the switch-loss due to the less number of power-tubes relative to the three-level method with full-bridge power amplifier. In the same time, this method can increase the reliable of system due to the less of the power-tubes.