Research Of Battery Internal Resistance Detection System Based On AC Proportion Method

With the wide application of battery as backup power supply in all industries power supply system,the detection technology of battery characteristic parameters arises as the times require and it is necessary to master the status of battery health in time to ensure its reliability and stability in power supply.Due to the close correlation between battery internal resistance and capacity,it becomes to be the key technology of battery detection research to achieve measurement online with higher accuracy at lower cost since it has been widely recognized to judge the performance of a battery by measuring its resistance.Through the analysis of main characteristics of battery,a new AC proportion is proposed in this paper by optimizing the existing battery internal resistance detection method from the principle and technology.Based on AC propotion method,this paper completed the hardware and software design of a low-cost battery internal resistance detection system,which can achieve accurate on-line measurement of battery internal resistance through the measurement experiments.In this paper,starting from the principle of battery internal resistance detection,AC proportional method is proposed on the basis of AC injection method.The calculation process of internal resistance is simplified by adding a reference resistance into the detection circuit,which avoids the errors caused by other parameters such as impedance angle and improves the measurement accuracy in principle.In order to achieve testing battery internal resistance online,we use lock-in amplification technology to realize extracting the weak response signal effectively in the strong noise background to improve the measurement accuracy further,and build the lock-in amplification Model in Simulink.The simulation of online detection environment with complex noise interference verified that the lock-in amplifier module has excellent anti-jamming capability.Finally,combined with the design scheme of battery internal resistance detection system,the hardware circuit and software program of each module are designed on Altium Designer based on ATMEGA48.After debugging and field measurement test,it can be proved that the detection system can achieve on-line measurement of battery internal resistance with high-precision.