Prevention of battery protection board explosion

　　Hardware composition of battery protection board system: MCU module, detection module, equilibrium module.

　　1. The MCU module of the battery protection board MCU is the core of the system control. The MCU used in this article is the M68HC08 series of GZ16 models. All MCUs in this series use enhanced M68HC08 central processors (CP08). The single -chip machine has the following characteristics:

　　(1) 8MHz internal bus frequency;

　　(2) The built -in Flash memory of 16KB;

　　(3) 2 16 -bit timer interface modules;

　　(4) The clock generator supports 1MHz ~ 8MHz crystal;

　　(5) Enhanced serial communication interface (ESCI) module.

　　2. In the detection module of the battery protective board, the voltage detection, current detection, and temperature detection module will be introduced separately.

　　(1) In this system, the single -chip machine will detect the overall voltage and single -section voltage of the battery pack. There are two methods for detection of the overall voltage of the battery pack:

　　(1) The dedicated voltage detection module is adopted, such as the Hall voltage sensor; The cost of using a dedicated voltage detection module is higher, and a specific power supply is also required. The process is more complicated. Therefore, the pressure of a separate circuit is used for detection. 10 The range of voltage changes in the battery pack of lithium ribs is 28V to 42V. The voltage of 3.9m? Resessive and 300K? Resessive resistance, the range of the collected voltage signal is 2V to 3V, and the corresponding AD conversion results are 409 and*. For the detection of single batteries, flying capacitance technology is mainly used.

　　(2) When the current sampling circuit current sampling, the parameters in the battery management system are an important basis for battery overcurrent protection. The current sampling circuit in this system is shown in Figure 2. When the battery is discharged, the current signal is detected with the Kang Copper wire, and the detected voltage signal is amplified by the differential mold to be amplified to the voltage signal of 0 to 5V to the single -chip microcomputer. If the current of the discharge is too large, the voltage signal detected by the single -chip microcomputer is relatively large, and it will drive the action of the triode to change the MOS pipe grid voltage and turn off the discharge circuit. For example, for the lithium manganate battery of 36V, the protection current is 60A. The resistance of Kang copper wire is about 5MΩ. When the current reaches 60A, the voltage of the copper wire reaches about 300mV. In order to improve the accuracy, the voltage is amplified by the amplifier 10 times to the single -chip microcomputer detection.

　　(3) In the process of temperature detection battery packs In the process of charging and discharge, part of the energy was released in the form of heat. This part of the heat was excluded in time to cause the battery pack to overheat. If the temperature of a single nickel -metal hydride battery exceeds 55 ° C, the battery characteristics will deteriorate, and the battery pack and discharge balance will be broken, which will cause the battery pack to permanently damage or explode. In order to prevent the above situation, real -time monitoring of the temperature of the battery pack and heat dissipation treatment are needed. The thermistor is used as a temperature sensor for temperature sampling. Thermal resistance is a thermal semiconductor resistor, which decreases with the increase in temperature.

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