Voltage control method and device for direct-drive permanent magnet synchronous motor

The embodiment of the invention provides a voltage control method and device for a direct-drive permanent magnet synchronous motor. The method comprise the steps of obtaining a voltage space vector and a target phase angle corresponding to the voltage space vector according to a rotor rotation angle and a three-phase current of the motor, obtaining an actual phase angle corresponding to the voltage space vector according to the current stator frequency of the motor, obtaining the target stator frequency of the motor according to the target phase angle and the actual phase angle, and obtainingthe amplitude and phase of the three-phase voltage of the motor according to the target stator frequency. Through the above process, the phase angle of the voltage space vector outputted by a tractioninverter can be adjusted in real time, so that the actual phase angle of the output voltage of the traction inverter always tracks the target phase angle outputted by a control algorithm, the precision of the output voltage o