Optimization-Based Auto-Tuning of PI Current and Speed Controller Gains for PMSM Drives Using Measured Responses

How well a PMSM drive behaves rests largely on how its proportional–integral gains are chosen. This paper sets those gains automatically, for both the current and the speed regulator, by driving down a scalar score computed from the responses produced by the drive itself. The initial gains are set from known nominal motor parameters, and the final gains are then determined solely from the measured responses so that the method does not require an accurate system model and is insensitive to errors in the initial parameters. The score weighs a normalized tracking error against a normalized overshoot so that quickness is bought without losing damping. Ordering protects the cascade: the current regulator is settled while the shaft is at rest, and the speed regulator follows. Simulation and experimental results produced using a DSP-based drive, using both a 100 W and a 50 kW PMSM, confirm improved performance under both underdamped and overdamped initial gains with low computational burden.