A Lead-Acid Battery Charging Management Chip With Temperature Compensation

Environmental issues have been a hot topic in recent years,especially in terms of energy utilization.With the rapid development of the electric vehicle industry,there is an increasing demand for batteries,which leads to the pressure of battery recycling and resource waste.Leadacid batteries will remain the mainstream of the market in the next few years due to their unique advantages of low manufacturing cost and high recycling value.Moreover,the battery damage is caused by the factors such as insufficient battery charging,long-term storage and overcharging,so the market demand for battery charging performance is getting higher and higher,and it is of great significance to study the high-performance battery charging management system.In view of the application requirements of the lead-acid battery charging management system,this paper mainly conducts research work from two aspects of high charging accuracy and temperature compensation,and proposes a lead-acid battery charging management chip with temperature compensation.The system adopts the flyback converter based on the secondary side feedback topology,adjusts the current on the optocoupler by sampling the secondary side voltage,and then feeds back to the switching frequency of the primary side control power tube to achieve constant output.Compared with the primary side feedback structure,the feedback precision is higher and the dynamic response speed is faster.The chip designed in this paper adopts a constant current op amp and a constant voltage op amp.The current on the optocoupler is controlled by sampling the current and voltage at the output port,which is fed back to the primary side to control the switching frequency of the power tube to achieve constant output.Compared with the traditional chip,the circuit structure is simplified.In addition,the MCU is proposed to control the switching of charging state,and a timer is set during charging to prevent the battery from overcharging.To solve the problem that ambient temperature affects battery charging,a peripheral circuit is designed to sample ambient temperature,and the sampled temperature signal is input into the MCU,and the MCU outputs the PWM waveform corresponding to duty cycle.The output voltage is changed by modifying the constant current/constant voltage reference value of the positive phase port of the constant current/constant voltage operation amplifier through the processor,and temperature compensation is realized.The lead-acid battery charge management chip designed in this paper adopts Huahong Honli HHGRACE 0.35μm BCD process,and has been verified by 59V2.8A circuit prototype.The test results show that the maximum static power consumption of the system test board is103 m W within the input range of 85～265V.When the system operates in the constant current mode,the output current is 2.8A,the constant current accuracy is ±1.53%,the linear adjustment rate is ±1.40%,and the load adjustment rate is ±1.21%.When the system operates in the constant voltage mode,the output voltage is 59 V,the constant voltage accuracy is ±1.41%,the linear adjustment rate is ±1.31%,and the load adjustment rate is ±0.90%.It can be seen that the chip designed in this paper has a good application prospect in the lead-acid battery charging management system.