Active Discharging Method of PMSM Using Flux Map-based Torque Control

Abstract

A dc-link voltage control algorithm is developed using the flux-based torque control method and the flux controller. Using negative dq-axes currents, the DC-link voltage can be controlled regardless of the motor operation state. The power flow of the electric-drive vehicle is modeled, and the voltage controller is analyzed. Due to the copper loss of the motor, the nonlinear function, square, is included in the voltage control loop. Using the linear approximation, the control loop is approximated as a linear system. The variable gain, which depends on the current and dc-link voltage, was derived straightforwardly. The compensation gain is proposed to maintain the performance of the voltage controller regardless of the operating point. The performance is experimentally demonstrated under different operation conditions such as 500rev/min and 1000rev/min.