Speed Ripple Reduction of Direct-Drive PMSM Servo System at Low-Speed Operation Using Virtual Cogging Torque Control Method

In this article, a virtual cogging torque (VCT) control method to reduce the speed ripple of direct-drive permanent magnet synchronous machine servo system under low-speed conditions is proposed. Compared with other factors, at low speeds, main factor that deteriorates drive performance, even induces oscillations. Especially in due volume limitation, designed larger than normal one order remove need brake. Based on model motor, cause and effect are analyzed. Inspired by characteristic torque, VCT proposed investigated significantly speeds. The idea produce proper continuously move corresponding stable equilibrium point rotor smoothly. addition principle method, its analysis implementation studied as well. Simulation experimental results from prototype demonstrate correct valid, it simple effective smooth operations.