Flying capacitive series battery pack voltage detection device and control method

Abstract

The invention provides a novel battery voltage detection device and a control method. A sampling resistor can be canceled in a battery voltage detection circuit with a triode switch, so that battery voltage measuring accuracy is improved. Two ends of a flying capacitor serve as input voltage, a single-end operational amplifier is used, battery voltage can be monitored by the aid of the low-cost amplifier, and a complicated differential amplifier is omitted. The battery voltage detection circuit is used for monitoring voltage of a plurality of serial batteries and has the advantages of rapidness in detection and high detection accuracy, a battery pack selects each battery through the triode switch, so that the battery voltage is further reduced through direction correction, voltage detection ranges are further narrowed, voltage detection accuracy is improved, and the voltage of each battery is calculated.

Description

technical field [0001] The invention relates to the management of lithium batteries connected in series, in particular to a battery voltage detection circuit using a multi-way selector switch. Background technique [0002] The voltage of a single lithium-ion power battery is generally relatively low, and it is usually used in series in an electric vehicle. The 2V-4.2V voltage range of lithium-ion batteries accounts for more than 95% of the battery capacity. Therefore, in order to accurately measure the battery capacity, the measurement error of the battery voltage needs to reach about 1mV. There are many voltage measurement circuits for single-cell lithium-ion batteries in 4.2V Measuring only the range error of 2V can meet the requirements. However, since the individual lithium-ion batteries are used in series, the simple resistance voltage division method to measure the battery voltage will result in lower measurement accuracy for the battery pack with higher voltag...

AI Technical Summary

Problems solved by technology

The 2V-4.2V voltage range of lithium-ion batteries accounts for more than 95% of the battery capacity. Therefore, in order to accurately measure the battery capacity, the measurement error of the battery voltage needs to reach about 1mV. There are many voltage measurement circuits for single-cell lithium-ion batteries in 4.2V Measuring only the range error of 2V can meet the requirements. However, since each single lithium-ion battery is used in series, the simple resistance voltage division method to measure the battery voltage will lead to the lower measurement accuracy of the battery pack with higher voltage.

[0003] Inaccurate voltage measurement weakens the equalization effect of the power lithium-ion battery pack, and the insufficient accuracy of the maximum charging limit voltage will greatly reduce the service life of the battery, so accurate measurement of the voltage of the power lithium-ion battery is very important for the battery management system

[0004] The traditional battery pack measurement method uses the resistance voltage division method. The resistance voltage division method will cause the battery to consume power when it is not in use, and the lower the battery voltage, the lower the measurement accuracy will be.

Images