The Research And Design On A Charging Management IC Of Traction Battery

Lead acid battery, as a kind of mature power battery, is widely used in the ignition and lighting of the fuel vehicle, the power of the electric vehicle and the standby power of the industrial system. However, the lead-acid battery is facing the dilemma of the rapid decline of battery capacity in actual using, the battery's life is far less than expected. This is often caused by the battery charging mode is not reasonable or quality of the battery charger is not qualified. Therefore, fully consider the battery charging efficiency and prolong the battery life, to design a scientific management mode, complete function and reliable performance of the battery charging battery charging management chip is of practical significance and market value.In this paper, the chemical reaction of charge and discharge of lead-acid battery is introduced. And the lead acid battery life reduction of the two main causes are given: battery water loss(dry-up) and battery thermal runaway. After the analysis of the impact of the battery charging mode on the two main causes, this paper introduces the current common ways of charging management. After comparing the charging efficiency, the battery life and the realization cost, three-stage charge management mode is selected. Then design of the three section of the implementation of the program begin with the basic structure of the battery charger. After fully taking into account the functional requirements of battery charging management, three stage charging management chip is designed.The battery charging management chip designed in this paper not only can achieve the three-stage charging management, but also have the reverse battery protection, anti-aging timing control, charging status indication and cooling fan control function. And this chip can meet the needs of different types of battery and different voltage battery by adjusting the external resistance off-chip. In this paper, the chip is designed by 2um 36V bipolar process, and the design of the key circuits are given, including the bandgap reference circuit, the reverse protection circuit, the three-stage control circuit, the clock circuit and the control circuit. Cadence Spectre software is used to simulate and verify the design of the circuit, the accuracy of bandgap reference is 0.965ppm/?; reverse protection circuit input over-voltage protection, voltage does not exceed 2V; three stage op-amp gain is about 81.55dB; clock cycle is 644uS and the overall simulation results show that the chip can achieve the three section of the battery charge management.