A Low Cost Induction Motor Controller for Light Electric Vehicles in Local Areas

Abstract

This paper is concerned with design considerations and tradeoffs involved in the power electronics development for light electric vehicles. A review of propulsion system design, power conversion structure and control is presented. A three-phase squirrel-cage induction motor is used as propulsion system for an electric scooter. The motor is controlled at different operating conditions by means of a simple scalar control using a low cost controller board developed for light electric vehicles used in local areas. Experimental results show that the proposed digital controller is able to follow the reference speed with a suitable dynamics for the electric scooter. I. INTRODUCTION Nowadays, environmental quality of cities is an emerging issue. The ever increasing traffic volume has produced high levels of carbon dioxide emissions from the conventional gasoline and diesel-fueled vehicles, which will contribute to a substantial increase of pollution in the major cities all over the world, causing heavy consequences to the communities (1� 4). It has been recognized that electric vehicles are the only viable solution in order to reduced air pollution, in particular, in large urban areas. However, electrical vehicles have serious disadvantages because of the limitation on cruising range imposed by weight, capacity of the batteries and long recharging time. Electric scooters are a step towards the solution for the environmental problems and traffic congestion created by cars. Moreover, electric scooters are competitive when devoted to urban mobility where it is not necessary an extended driving range. Therefore, the research and development of electric scooters in order to reduce air pollution and environmental damage becomes relevant. In addition, if those disadvantages can be overcome, motorcycles customers will be motivated to purchase electric motorcycles in the near future. Therefore, our objective in this paper is to establish an appropriate platform for the study of electric motorcycles, and then to design a low cost controller for the achievements of the desired control objectives. In this context the induction motor offers weight and efficiency advantages over the more conventional DC motors, besides its traditional advantages of robustness, low cost and well established manufacturing techniques. This work presents the design of a propulsion system for a prototype of a low cost electric scooter. The propulsion system consists of a three-phase induction motor driving the road wheels using a differential. The main benefits of these vehicles include: zero emissions, reduced noise pollution, significant reduction in maintenance and more comfortable ride from greatly reduced vibration. In this project, the viability and affordability of the electric scooter has been studied.