High bandwidth phase voltage and phase current control loop of a permanent magnet synchronous motor based on delta sigma bitstreams

Abstract

Delta Sigma (ΔΣ) analog digital converters are usually comprised of an analog modulator and a digital low pass filter. These converters are used for phase voltage and phase current measurement in control loops. A new approach, the delta sigma signal processing (DSSP), directly processes the high frequent ΔΣ-bitstream. Due to the high frequent sampling rate of the DSSP, sampling effects can be neglected and a high closed loop bandwidth is achieved. In order to fully utilize the advantages of this concept, a high bandwidth three phase hysteresis modulator for power electronics is presented. Since the hysteresis modulator is based on DSSP, the ΔΣ-bitstreams of phase voltage and current measurement can be directly processed. The performance of this feedback is evaluated with regard to the compensation of inverter nonlinearities, average switching frequencies and the dynamic behavior of the control loops.