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Author ：Iflowpower – Portable Power Station Supplier
1 Introduction Modern Communication Equipment and Large Computer Network Systems have high reliability requirements for power systems. At present, most of the traffic storage power supplies and computer use UPS power supplies, all high-power battery servings as the main power system in the mainstream interruption, and the battery pack is the last line of service, which is effective online monitoring, discharge and Capacity test, to understand the performance of the battery pack to the relevant department to provide accurate and reliable data, with special use and significance. In this paper, the DS80C320 single chip is designed as the core, and a multi-function monitoring and maintenance system for the battery pack for constant current discharge and capacity testing of the battery pack is designed in the use of the battery pack.
2 System Work Principles This system is important to have three function modules: online parameter monitoring module, constant current discharge control module and battery remaining capacity * estimation module. Online parameter monitoring module is real-time on the voltage, current, temperature of each battery, online monitoring. The system is sequentially acquired by a light relay switching, and each time the battery (as shown in Figure 1), the double knife relays S1, S2 are inverted to ensure the polarity of the post-level circuit.
The current of the entire battery pack passes through the Hall type current sensor; the measurement of the battery temperature is achieved by resetting the temperature sensor on the surface of the battery, and the battery temperature measured according to the online measured battery temperature. Studies have shown that whether it is constant current discharge, limiting constant current charging or floating state, the low load capacity is the highest. The constant current discharge control module realizes the constant current discharge of the battery pack to meet the daily maintenance of the battery pack.
The principle of this module is to discharge the battery through the microcontroller to control the battery, and the difficulty is how to achieve continuous adjustability of the current. The method used herein is: the resistance of a plurality of fixed resistances such that each circuit (K1 ~ KN) can enable a fixed discharge current; another electrical resistance is used to use the resistance of the first circuit (K1) resistance, using the chopping principle, Get a linear adjustable discharge current (the channel current is slightly larger than the other rectification), by combining the channel current with other rectifices, the discharge current can be achieved, as shown in Figure 2. Figure 1 Online parameter monitoring schematic Figure 2 constant current discharge control principle battery remaining capacity * Estimator By testing internal resistance of the battery, * estimates the remaining capacity of the battery.
Since the capacity of the battery is strong and the battery is strong, in general, the larger the capacity of the battery, the smaller the internal resistance, so the capacity of the battery can be performed on the capacity of the battery by measurement of the internal resistance of the battery. Internal resistance measurement is a more complex process, currently common methods are important density method, open circuit voltage method, communication method and DC discharge method. Density method, open circuit voltage method, communication method, due to incorporated measurement, low measurement accuracy and measurement of static values, is not suitable as a measurement method of battery internal resistance, this system uses DC discharge method to measure the internal resistance of the battery, pass Instantaneous current discharge of the battery, measuring the instant voltage drop on the battery, plotting the discharge curve of the battery, determines the change in the curve, and then combined with the nominal voltage and capacity value input by the user, the state of the battery is obtained.
The actual test confirmed that when the detection current reached a certain value, the load voltage of the battery has a strict linear correspondence between the actual capacity.
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