An automated rotor time-constant measurement system for indirect field-oriented drives

An automated scheme to measure the open-circuit rotor time constant and set the slip gain of a field-oriented controller is presented. The test utilizes the pulse-width-modulated inverter of the drive itself and is conducted at zero speed so that the result can be used for automated calibration of the slip gain in the controller of an indirect field-oriented drive system. The accuracy of the test is verified by a simple measurement that checks for the existence of a linear relation between the input torque command and output torque at steady state