Design Of Battery Voltage Readout Circuit For Power Management System

Today, the design of the power management system has become a key technologyin system of power battery stack, it plays an important role in the function of thewhole battery group. The power management system mainly focuses on the detectionof battery voltage, current, temperature, power and other state information andconverts the changes infomercial input to the control system. The system can receivethe detected data according to the work of the health state of the battery so that thebattery group can be more lasting and efficiently work. This paper first reviews theresearch and development of battery voltage detection system，and analysis the workof the battery cell voltage readout, enumerate several schemes of the commondetection system. The advantages and disadvantages of several schemes werecompared. The battery chip detection scheme is proposed and the design of the batterycell voltage readout system is completed. The system is applied to the battery voltagedetecting chip as a cell voltage extraction module; the module provides voltagedifference for the subsequent detection and control circuit through sample and hold ofthe voltage signal of each cell of the battery pack.The battery voltage monitor designed in this paper mainly includes: high-lowsample and hold circuit, linear regulated supply, bandgap voltage reference. The mainwork is as follows: design the sample and hold circuit which has the function ofeliminating the common mode voltage. The sample and hold circuit can be used tosequentially sample and hold the signals of8batteries, with the input voltage rangefrom0V to5V. The method to improve the SNR of sample and hold circuit is putforward to eliminate the substrate bias effect. The readout system needs a linearregulated power supply for battery voltage which works in the10V to40V inputvoltage. For the transient starting current issue brought by high voltage input voltage,soft start circuit is designed to improve the reliability of the voltage controlled currentsource. The circuit design, layout design and simulation has been completed.