Integration of non-linear H∞ and sliding mode control techniques for motion control of a permanent magnet synchronous motor

A new method using non-linear H_∞ and sliding mode control (SMC) is presented for a permanent magnet synchronous motor (PMSM) position control system. It is a high-performance controller in the presence of motor parameters variations and unknown load torque disturbances. In the proposed technique, the load torque is considered as an external disturbance and non-linear H_∞ is utilised to minimise its influence on the rotor position. Although H_∞ is to some extend robust against motor parameter variations, parameter variations may affect the performance of H_∞ controller, so SMC is used to reject these variations. Integration of these two methods offers an efficient robust position controller for PMSM. Position control of PMSM using the proposed method is compared with those obtained by other methods. Merits of the approach through simulations are verified by the experimental results.