Comparison of driving characteristics in two kind of control schemes for permanent magnet synchronous motor mounted on electric vehicle

This paper shows the considerations of the control characteristics when the surface permanent magnet synchronous motor installed in an electric vehicle is controlled by direct torque control or current control type vector control. Current control type vector control is generally used as a control method of permanent magnet synchronous motor; however, that requires a rotor position detector, the rotating coordinate transformation, and current controller, which needs the gain adjustment. As a result, the controller configuration becomes complicated. In contrast, direct torque control does not require rotor position detector and current controller on the rotating coordinate system. Thus, position sensorless control can be realized more easily. In this research, the controller, which includes a three-phase voltage source inverter and controller board, of an electric vehicle was replaced in order to enable change of the motor control scheme. In addition, simulation verification, comparison of transient characteristics between two control schemes, was conducted. As a simulation result, vehicle speed characteristics of two schemes were almost same. However, the torque and the current of DTC have large ripple than those of vector control. Moreover, some experimental results are shown in this paper.