An improved digital current control of a PM synchronous motor with a simple feedforward disturbance compensation scheme

An improved digital current control technique of a permanent magnet (PM) synchronous motor with a simple feedforward disturbance compensation scheme is presented. Among the various current control schemes for an inverter-fed PM synchronous motor drive, the predictive control is known to give a superior performance. This scheme, however, requires the full knowledge of machine parameters and operating conditions, and cannot give a satisfactory response under the parameter mismatch. To overcome such a limitation, the disturbances caused by the parameter variations are estimated by using a disturbance observer theory and used for the computation of the reference voltages by a feedforward control. Thus, the steady state control performance can be significantly improved with a relatively simple control algorithm, while retaining the good characteristics of the predictive control. The proposed control scheme is implemented on a PM synchronous motor using the software of DSP TMS320C30 and the effectiveness is verified through the comparative simulations and experiments.