Design of field oriented control using improved flux controller for permanent magnet synchronous motor in traction drive

In traction applications, PMSMs are gaining attention due its reliability and wide constant power speed ranges. The high maintenance cost and complicated control methods are the disadvantages of PMSM. The efficiency of PMSM can be increased to suit the requirements of traction applications by achieving direct control of stator current. However it is quite unattainable due to the strong coupling and non-linear nature of PMSM. To decouple the motor variables, field oriented control technique is commonly used. In this paper, the closed loop control of PMSM using improved flux weakening controller is designed and simulated using Matlab/Simulink. The performance of the motor is tested under running mode operation with load. The simulation results shows good dynamic response of the drive with less ripples for varying speed and load torque. Also, RLC filter is designed to reduce the voltage and current harmonics at motor terminals. The improved flux weakening control method regulates the magnetic flux throughout the entire speed profile. This can be seen from the results that the desired speed is achieved with 2.6% of ripple for mechanical load torque ranging from 200 Nm to 800 Nm whereas the reference speed is maintained at 500 rad/s. Also, it can be seen from the results that the controller adjusts the stator current component automatically without causing spikes during switching and hence the PMSM motor can be driven without setting the direct component of stator current to zero and DC bus voltage is maintained constant at 560 V