This paper presents a novel speed estimation scheme for induction motors (IMs) based on back electromotive-force model reference adaptive system (back-EMF MRAS). The scheme is employed for the purpose of sensorless fault-Tolerant torque-controlled drives used in a limp-home mode operation in electric vehicle (EV) applications. The proposed scheme was experimentally tested on a laboratory dynamometer using a 19-kW IM and a 29-kW controller, which are both currently used in the automotive industry for EV applications. The scheme was also implemented on an electric golf buggy which was equipped with a 5-kW IM. A performance comparison was carried out between the proposed and conventional back-EMF MRAS schemes for starting from standstill, sensitivity to parameter variations and constant speed operation with load variations. Utilizing the golf buggy, the behaviors of the new scheme was separately investigated for vehicle starting from standstill, wide speed range including field weakening region, and hill-starting operations. The proposed scheme is computationally easy to implement, robust against sensitivity to parameters variations, inverter nonlinearity and errors due to digitization in the field weakening region. This scheme is not only consistent for vehicle starting from standstill, it also provides a reliable vehicle-drive in the field weakening region and during vehicle hill-starting. The dynamometer and vehicle test-drive results show the suitability of the proposed scheme for the purpose of EV fault-Tolerant limp-home mode operation.
Bibliographical note© 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.
- Electric vehicles (EVs)
- fault tolerant
- induction motor (IM)
- model reference adaptive system (MRAS)
- torque controlled-drive (TCD)