Nonlinear speed control for a PM synchronous motor with a sequential parameter auto-tuning algorithm

A nonlinear speed control for a permanent magnet (PM) synchronous motor with a simple sequential parameter auto-tuning algorithm is presented. The nonlinear control scheme gives an undesirable output performance under the mismatch of the system parameters and load conditions. Recently, to improve the control performance, an adaptive linearisation, a nonlinear sliding mode control and an observer-based technique have been reported. However, these schemes are based on the assumption that a variation of an unknown disturbance is very small during each sampling interval. Even though good performance can be obtained, the performance is no longer satisfactory under specific conditions such as a large inertia variation, a fast speed transient or an increased sampling time. Although various work that effectively estimates only the specific interested parameter of motors can be found in the literature, the simultaneous estimation of principal parameters that give a direct influence on speed dynamics is generally not simple. To overcome this problem, a sequential parameter auto-tuning algorithm at startup is proposed in which dominant motor parameters are estimated in a prescribed sequential routine, one by one. The proposed control scheme is implemented on a PM synchronous motor using DSP TMS320C31 and the effectiveness is verified through simulation and experiment.