Flux weakening control method and device for permanent magnet direct-current motor

The invention relates to a flux weakening control method and device for a permanent magnet direct-current motor. The flux weakening control method comprises steps as follows: calculating an error of a voltage mode according to a voltage value output by a current loop controller in a dq rotating coordinate system and a limit value of the voltage mode; calculating a compensation angle according to the error of the voltage mode and an electrical angular velocity of a rotor; obtaining an MTPA (maximum torque per ampere) angle according to a current reference vector; adding the compensation angle to the MTPA angle to generate a flux weakened phase angle; calculating a current reference value in the dq rotating coordinate system according to the flux weakened phase angle and the current reference vector and transmitting the current reference value in the dq rotating coordinate system into the current loop controller. With the implementation of the technical scheme, few algorithm links are needed, the debugging proc