Maximum Torque per Ampere Strategy in IPM Drives for Electric Vehicles

Abstract

Permanent magnet synchronous motors (PMSM) are generally known for their type whose magnets are located on the rotor surface and this motor type, which is called surface mounted permanent magnet synchronous motors (SPM), produces magnet based torque. Based on torque equations, since there is only q-axis current and value of magnetic flux linkage, the d-axis current is kept at 0 and the torque is maximized and controlled, which is called 𝐼 𝑑 = 0 control technique. However, reluctance torque is produced in interior mounted permanent magnet synchronous motors (IPM) due to the inductance difference caused by the saliency in the rotors and by controlling the reluctance torque correctly, the efficiency of motor increases. For this reason, maximum torque per ampere (MTPA) strategy is applied to perform torque control efficiently in IPMs. In this study, the difference between the efficiency values was observed by simulating torque control in IPMs with the MTPA strategy instead of the conventionally used 𝐼 𝑑 = 0 control technique. As a result of the simulations, using the MTPA strategy instead of the conventional vector control technique in the drivers of the IPMs used in electric vehicle applications increases the efficiency of the system and extends drive range capacity by using the battery more efficiently.