Latency Compensation of SD-ADC for High Performance Motor Control and Diagnosis

High performance motor control and fault diagnosis requires high resolution isolated signal measurement. Sigma-delta ADCs (SD-ADC) are ideal for this purpose but cause remarkable measurement latency which can cause performance degradation and stability issues. In this paper, the effects of current measurement latency caused by sigma delta filter module (SDFM) and corresponding latency compensation are discussed in detail. A Bayesian filter algorithm is proposed to compensate the latency caused by the group delay of SINC filter and increase the phase margin of the system. The proposed algorithm and measurement results are experimentally verified on PMSM drive. It is shown that with proposed solution Sigma-delta ADC can provide much higher resolution than traditional SAR ADCs and also yield superior diagnostics capability and control.