Automotive Dual-voltage System Of The Permanent Magnet Generator

In recent years, with the increase of vehicle load, the require of generator output power increase too, which led to issues such as tension in the engine room, supply current excessive. Therefore, there were two trends in the development of vehicle electrical system: First, the use of greater power mass ratio generator; second is to improve the voltage of vehicle electrical system.This paper presents a dual-voltage (42V, 14V) hybrid power supply system of permanent magnet generator. Permanent magnet generator has high power mass ratio, high efficiency, in the same output power, the permanent magnet generator can reduce the size of 30%～50% compare to excited generator. Hybrid power supply system is able to meet the requirement of high-power load, and can be used as the transition to 42V as well as to maximize the use of permanent magnet generator capacity.Aiming at characteristic that the output voltage of permanent magnet generator changes with the speed and load, to achieve constant output control; the compatibility problem between 42V and 14V in hybrid power supply system, which are studied in this paper. The constant pressure control system developed contains that the control module: a single-chip microcomputer as the core, controllable rectifier module, phase detection module, SCR driver module, DC/DC module, feedback circuit module. In order to make the good static and dynamic performance, the automatic control technology of modern systems and advanced control algorithms are used in this study. Especially for the transient disturbance of load factor in dual-voltage system, incremental PID control algorithm is adopted to optimize the control process, the speed of dynamic response relying on powerful single-chip computing speed is increased. The two output voltage of the system can be controlled stably and quickly both in steady state and dynamic state.In this study, the data is collected through the data acquisition card when the system is in the course of mutation load transient process, the varying voltage waveform is displayed on PC in real-time by labview software, which provide a great deal of convenience for optimizing the control process.Plentiful test and research on the dual-voltage output control system shows that: if advanced control technology and control algorithms are used in the hybrid power supply system of permanent magnet generator, good results can be received.The steady state voltage regulation is less than 1%; the transient voltage regulation is 2.738%～11.319%; the stabilization time is 165ms～331ms.Visibly, the steady state voltage regulation,the transient voltage regulation,the stabilization time and other major performance indicators of dual-voltage hybrid power supply system in permanent magnet generator are essential to meet the vehicle electrical system. The control system is worth a certain reference value for its simple structure and lower price.