Automated Current Control Method for Flux-Linkage Measurement of Synchronous Reluctance Machines

This article presents a novel approach to the dc standstill measurement of flux linkage and inductance of a synchronous reluctance machine. In the existing standstill test to measure the flux linkage of a machine, a pulsed voltage is applied to the machine in open loop. The flux-linkage characteristics are computed using the measured response. This article discusses the limitations of the voltage pulse-based method, and a current control based method is proposed to overcome these limitations. In the proposed method, a pulsed current in closed loop is applied to the machine at standstill (shaft locked). The major benefit is that the time response of the machine can be modified by properly tuning the controller parameters such that the number of measurement samples available during the transient is improved. Thus, the measurement process can be programmed in a real-time processor to automate the measurement process. The automation leads to bypassing the recording and offline processing of huge datasets. This article also proposes a method to automatically tune the current controllers required in the measurement process. The proposed method is verified by an experiment performed on a 7.5-hp machine.