Harmonic injection based adaptive control of IPM motor drive for reduced motor current harmonics

This paper presents a robust nonlinear controller for interior permanent magnet synchronous motors (IPMSM) based on maximum torque per ampere (MTPA). Harmonic reduction is achieved through strategic harmonic injection into the command voltages. Third harmonic injection also permits increased utilization (transfer ratio) of supply potential which facilitates a greater speed operating range. Stability of the control law state variables is demonstrated through Lyapunov stability criterion. Global asymptotic stability is assured through the application of criterion supported by Barbalat´s lemma. Control expressions are derived using adaptive back-stepping technique, with estimation of dynamic load and mechanical coefficient ensuring optimal performance under dynamic operating conditions. The proposed system has been implemented in a co-simulation environment, with control system and machine model implemented in Matlab/Simulink and PSIM, respectively. The complete drive system is implemented using the DS1104 DSP board for a 3.7kW laboratory motor. Both experimental and simulation results have demonstrated excellent drive performance, harmonic distortion reduction and an increase in the linear modulation range.