Optimization current computation of IPMSM drive system for electric vehicles based on the projected dynamic system

For realizing real-time efficiency optimization control of interior permanent-magnet synchronous motor (IPMSM), the optimal currents (OCs) need to be computed real-timely. This paper proposes a method based on the projected dynamic system to find the OCs. Firstly, the efficiency optimization of IPMSM was regarded as a constrained optimization problem. And then, the optimization problem is classified two different cases, that is, the OCs lies either in the interior or on the voltage limit boundary, according to optimization theory the OCs for each case is a solution of a certain nonlinear equations. Finally, a projected dynamic system is used to find the solution of the nonlinear equations. According to the projected theory and the matrix norm theory, the convergence criterion of the projected dynamic system is obtained, and the criterion is very simple. Simulation results show that the method proposed in this paper is effective, and the analysis of the convergence criterion is correct.