The Research Of Electric Trucks Dual-mode Controller On Brushless Direct Current Motor

With reduction of petroleum resources and intensification of air pollution, electric vehicles are developed to replace traditional fuel vehicles. The widespread use of electric vehicles is consistent with energy saving ideas and can effectively alleviate environmental problems caused by fuel vehicles. Electric truck controller is developed according to company requirements. Brushless direct current motor has advantages of large torque and high efficiency, and has no brush in comparison with brushed DC motors, which can reduce maintenance costs of the motor. Therefore, brushless DC motor is selected as drive motor of the controller. Dual-mode controller can work both in Hall sensor mode and position sensor damaged even without position sensor in order to avoid vehicle breakdowns because of Hall fault. The hardware and software design of electric tricycle dual-mode controller have been completed based on ds PIC30F4011 chip. The main contents of this paper are as follows.(1) Composition and basic principle of brushless DC motor were elaborated, and a detailed analysis of mathematical model and working process were carried out.(2) Dual-mode controller was developed which can work both in Hall sensor mode and position sensor damaged even without position sensor. In no position sensor mode, rotor position was obtained by terminal voltage method and the motor started through short pulses closed-loop method. Energy feedback was adopted during downhill or braking to improve endurance and reduce vehicle tear of mechanical brake. Multiple current protections were designed to ensure safe and reliable operation of the controller.(3) Hardware circuit of the controller was designed. The circuit was composed of ds PIC30F4011 peripheral circuit, three-phase bridge inverter circuit, drive circuit, power conversion circuit, rotor position detection circuit, current sampling circuit, protection circuit and so on. Cooling device of the controller was improved, thus the installation of cooling block is convenient and reliable.(4) Software design of the controller was completed according to hardware circuit and requirements.Practical loading tests show that the controller operates in good condition, protections work well, and all relative parameters achieve the desired values.