Research on Electric Golf Cart’s Permanent Magnet Brushless D.C. Machine Driving System

　　Research on Electric Golf Cart’s Permanent Magnet Brushless D.C. Machine Driving System
　　Under the background of increasing oil resources shortage, how to reduce traffic dependence on the non-recyclable oil resources and the pressure on the environment, and how to develop electric traffic especially Electric Vehicles (EV) have become major international issues. During this time, from Light Electric Vehicle (LEV) to Compact Electric Vehicle (CEV), China’s electric traffic works out of its own new path.This paper aims at the study on the electric golf cart’s neodymium magnets driving system via specific project against this background, the electric golf cart has some performance indices very closed to compact electric vehicle but it is more lightweight. Researches On the key issues of the development of electric vehicle driving system such as the selection of motors, the construction of driving system, control strategy of driving system, regenerative braking, etc. are applied to practice in the driving system controller.After the comparison of various types of motor, we choose permanent magnet brushless DC motor (BLDCM) as driving motor of the system. And I carry out a detailed analysis and study on the application in driving system about some of the common and specific characteristics of BLDCM. This characteristics include: (1) Sum up the six series of common modulation strategies of BLDCM and finalized a simple H- PWM -L- ON modulation strategy to achieve motor’s speed regulation;
　　(2) Introduce on the three electric braking patterns, analyze low speed regenerative braking theoretically and give the switching mode of the main circuit power semiconductor devices; (3) Study on the commonly used torque control strategy in detail and point out that the torque control strategy has deficiency of highly nonlinear driving response in the region of weak magnetic and leads to "closed-loop failure" when the load torque is unable to reach the given torque corresponding to the position of accelerator pedal, then produce a“the greatest torque control strategy" to http://www.chinamagnets.biz resolve the "closed-loop failure" and achieve good effectiveness in practice.This paper analyze the subsystems’model related with driving system such as vehicular dynamics, BLDC motor, motor control systems and lead-acid battery. In the Saber platform, around the drive system, I build a specific model of main circuit of the voltage source inverter (VSI), convert the running resistance of vehicles to rotation resistance of motor, simplify the lead-acid battery model, and establish the digital PID model in Z domain in order to reflect the implementation of the control strategy in truth. Simulation analysis can find the latent problems of the system before the physical design and simulation results can also be used to guide the design of the actual system.Based on the previous scheme demonstration, theoretical and simulation analysis, I carry out the product design of electric golf cart’s driving system: A controller based on the dsPIC30F4011 including the design of hardware and software’s programming and debugging work, I introduce a series of innovative achievements and products in the hardware design. At last, I verify the final performance of the control system in a series of test.