The Research And Design Of Battery Quick Charging System Based On The PWM Rectifier

As a kind of energy storage devices, storage battery has the advantages of voltage stability, power supply reliability and convenient movement. It has been widely used in electric power industry, aviation, ships, electric vehicle, coal mines, uninterruptible power supply and all kinds of electronic products, etc., especially for the electric cars that as the new type object of energy conservation and environmental protection, which need high power battery for its power, however, how to charge the battery quickly, safely, efficiently and pollution free has been the bottleneck of battery application. In this paper, Sail 6-QW-110 electric vehicles starting battery was selected as the target object, the research and design of battery quick charging system that based on PWM voltage source rectifier has been discussed.Firstly, the present research situation of battery quick charging method in domestic and foreign has been carried on the investigation, and emphatically analyzes the impedance characteristics of the battery charge and discharge, charge and discharge characteristics, the mathematical model of lead acid battery was established, and a simulation was carried out, the factors affecting its fast charging are analyzed at the same time. Because the charging time of current charging method is longer, based on rapid charging principle, a new type of charging method that referred to as three phase depolarization pulse fsat charging method was put forward. It includes three stages,1 CA depolarization pulse fast charging stage,0.8CA depolarization pulse fast charging stage and 0.5CA depolarization pulse fast charging stage. In view of the current charging circuit may produce pollution for power grid, circuit of battery quick charging system that based on PWM voltage source rectifier has been proposed. Three phase half bridge PWM voltage type rectifier is selected as the AC-DC main circuit, and the working principles of PWM rectifier is analyzed, in addition, low frequency and high frequency mathematical model of three phase voltage source PWM rectifier are established respectively under the three phase static coordinate system, two phase static coordinate system and two phase rotating coordinate system. SVPWM control algorithm and current inner loop and voltage outer loop of the direct current double closed loop control strategy are adopted to get constant dc power supply in the control system of PWM rectifier. The system not only achieve fast charging, but also has realized the the net side current is sinusoidal, unit power factor and bi-directional energy flow operation.Secondly, in order to satisfy different quick charge battery charging device, in the circuit joined the bi-directional DC-DC converter. The appropriate charge and discharge current, voltage are set up according to the charge and discharge characteristics of different battery. Aiming at the strategy adopt in this system, bi-directional DC-DC converter uses the current closed loop PWM control strategy.Finally, the simulation model of battery quick charging system based on voltage type PWM rectifier and the overall charging device were built in Matlab. The calculation method of each parameter and the impact caused by parameter setting were introduced in detail.