Research on the maximum torque per ampere control of brushless doubly- fed machine servo system

Aiming at the problem of large stator current of brushless doubly-fed motor under no-load and light-load operating conditions, a control method of the maximum torque per ampere (MTPA) was presented. Firstly, the state space model of the brushless doubly-fed machine with the control motor current source and the power motor voltage source as the power supply input is given. Secondly, the MTPA control law is derived by constructing Lagrange auxiliary function and forcing the derivative of stator current of motor to be zero. Thirdly, MTPA control is combined with direct feedback control (DFC) to realize the optimal control of brushless doubly-fed machine (BDFM). Finally, the simulation results show that the proposed MTPA control scheme can significantly reduce the stator current of the BDFM, the control machine (CM) stator current is reduced by 98.3% under no-load conditions, the power machine (PM) stator current is reduced by 66%, the CM stator current is reduced by 57.5% and the PM stator current is reduced by 54% under the loading condition, which significantly reduces the copper consumption of the system and improves the operation efficiency of the machine.