An automated reconfigurable FPGA-based magnetic characterization of switched reluctance machines

The flux-linkage profile of a switched reluctance machine (SRM) is an important parameter in the verification of the design and performance of the drive. Due to the double salient structure of the SRM, the profile is a function of both rotor position and excitation current. In addition, the effects of eddy current losses and resistance changes make the measurement of SRM magnetic characteristics challenging. This paper describes an automated method to measure the magnetic characteristics of SRM drives using reconfigurable FPGA hardware programmed graphically with National Instruments LabVIEW. The FPGA-based measurement system provides advantages for the measurement and control of electric machines due to the timing, triggering, and custom logic capabilities of the reconfigurable chipset. A measurement methodology based on 60 Hz sinusoidal excitation using a variable AC power supply is developed which provides an alternative to time domain integration approaches for magnetic characterization. An automated software environment provides the ability to accurately measure voltage and current waveforms, perform sensor calibration, acquire rotor angular position, and eliminate error from thermal and eddy currents effects. The measured flux-linkage profile is correlated with finite element analysis results for validation of the proposed method.