Direct power control of AC motors.

摘要

In this thesis, the possibilities of direct power control (DPC) of induction motors (IMs) and permanent magnet synchronous motors (PMSMs) fed by a voltage source inverter have been studied. Three different approaches of DPC for IMs and one for PMSMs are proposed and investigated. They are: (a) direct output power and flux control, direct input power and flux control, and direct real power and reactive power control for IMs and (b) direct real and reactive power control for PMSMs. Principles of these approaches have been separately derived and evaluated. The reference values of control variables are discussed, and estimation of the actual values of those variables is provided. Simulation programs were written for the closed-loop speed control systems under various load conditions to verify the proposed methods.Results of this study show that DPC of IMs works well with the output power and flux control, somewhat worse with the input power and flux control, but not so well with the real and reactive power control. It is hoped the investigation will facilitate further studies of DPC of IMs. The best result of this research is the successful direct power control of PMSMs.Keywords: DPC, direct power control, direct power and flux control, induction motor, IM, permanent magnet synchronous motor, PMSM, real power, reactive power, voltage source inverter, hysteresis control.