Abstract: A control system and method for use in controlling a torque-controlled permanent magnet synchronous motor drive. A slew-rate limiter processes an input torque command to produce a modified torque command that is input to the motor drive. A controller is coupled to the slew-rate limiter and the motor drive for dynamically limiting the input torque command applied to the motor drive and its rate of increase. The slew rate limiter processes an applied torque command to output a modified torque command that is applied to the motor drive. Current control error signals are output by the motor drive. The RMS value of the current control error signals is computed. The RMS value is compared to low and high thresholds. If the RMS value is greater than the high threshold, the modified torque command is reduced until the RMS value is less than the high threshold.

Abstract: A surface-mounted permanent magnet synchronous machine drive and a method of controlling the machine drive. Flux weakening and current regulating loops cooperate to provide automatic transition to the flux weakening mode (operation above base speed), regardless of DC bus voltage, load or other operating conditions. The modulation index (d) is used as a condition for automatic start of flux weakening operation is very useful because this point can be easily changed by software when necessary, regardless of the value of DC bus voltage. This feature provides significant performance improvement. No look-up tables are used in the flux weakening loop. The on-set point for flux weakening is automatically adjusted, and may be changed through software. An appropriate d-axis current component is injected over the entire speed range, providing the maximum available torque (which corresponds to the q-axis current component).

Abstract: A surface-mounted permanent magnet synchronous machine drive 10 and a method 30 of controlling the machine drive. Flux weakening and current regulating loops 70, 60 cooperate to provide automatic transition to the flux weakening mode (operation above base speed), regardless of DC bus voltage, load or other operating conditions. This feature provides significant performance improvement. No look-up tables are used in the flux weakening loop. The on-set point for flux weakening is automatically adjusted, and may be changed through software. An appropriate d-axis current component is injected over the entire speed range, providing the maximum available torque (which corresponds to the q-axis current component). The control method works with fixed frequency current compensators.