An Improved Sensorless DTC Scheme for EV Induction Motors

In this paper a sensorless control is proposed to increase the efficiency of a direct torque control (DTC) of an induction motor propelling an electric vehicle (EV). The proposed scheme uses an adaptive flux and speed observer that is based on a full order model of the induction motor. Moreover, it is evaluated on an EV global model taking into account the vehicle dynamics. Simulations have been firstly carried out on a test vehicle propelled by a 37-kW induction motor to evaluate the consistency and the performance of the proposed control approach. The commonly used European drive cycle ECE-15 is adopted for simulation. The obtained results seem to be very promising. Then, the proposed control approach has been experimentally implemented, on a TMS320F240 DSP-based development board, and tested on 1-kW induction motor. Experimental results show that the proposed control scheme is effective in terms of speed and torque performances. Indeed, it allows speed and torque ripple minimization. Moreover, the obtained results show that the proposed sensorless DTC scheme for induction motors is a good candidate for EVs propulsion.

I. Introduction

Recently a lot of effort was focused towards development of high performance EV drives. This is mainly to reduce the environmental pollution due to emissions from the internal combustion engine (ICE) driven vehicles. EVs are already commercially available; however, they have not yet used the most remarkable advantages of electric motors. Indeed, an electric motor offers very fast response and can be controlled in a much better way; therefore, motion control through precise control of the motors has definite advantage over the ICE driven vehicles. Moreover, adhesion characteristics between tire and road surface are greatly affected by the traction motor control. This means that EVs stability and safety can be addressed and then improved by means of motor control.