Study On An Electrical Drive Installation

This work presents research results on an electrical drive installation powered by battery. In usual installation, high current output do great harm to battery and shorter it's service life. Safely charging is also important to prolong battery. To solve these problems, this dissertation bring out a new scheme that a DC-DC converter is added in the middle of battery and motor. By this method, the battery can work with low current output, however large torque also can be acquired by motor. Moreover, redundant energy can be charged to battery safely and in time. For this purpose, the research consist of three sections: Control methodology of the 3-phase brushless DC motor, Analysis and selection of DC-DC topology and Charge and discharge control for battery.With the research on the control methodology of the BLDCM, the equivalent formula of BLDCM was acquired. Then the principle of electrical commutator in BLDCM was detailed discussed. The commutation method of sensorless BLDCM was also discussed.In the dissertation, the DC-DC topology was analyzed. Buck and Boost topology were brought forward as the converter topology. Then the synchronous Buck topology was discussed in detail. Three operating mode of this topology was brought out. They were Buck current continuous mode, Boost current continuous mode and hybrid mode. It is found that the Synchronous Buck topology was a suitable topology for unifying the charge and discharge circuits.Management of charging and discharging of valve regulated lead acid battery (VRLA) is one of the most important functions of the equipment. With the research on the VRLA battery's electrical chemistry theory and the main factor influencing the VRLA battery service life, the scheme of charging and discharging was proposed. In detail, the scheme involves discharging with limiting voltage fluctuation, charging battery in time, maintaining good service state to increasing lifetime. Then, the variety kinds of working mode were detailed proposed based on the scheme.Based the studies aforesaid, an electrical drive installation was developed and a prototype was acquired. The installation realizes a high current and large torque outputs, and satisfied battery management which is in a constant voltage-limit current mode. Proved by circuit and vehicle application experiments, the prototype was well fulfilled the purpose. The design method and control strategy was valued for future work.