Circuits and methods for measuring cell voltages in battery packs

Abstract

A circuit used to measure cell voltages in a battery pack can include a cell voltage level shifter, a sense block, and a compensation current generator. The cell voltage level shifter selects a cell and shifts the terminal voltages of the selected cell from a first voltage level to a second voltage level. The sense block monitors the current consumed by the level shifter, and generates a signal indicative of the consumed current. The compensation current generator generates compensation currents to compensate the current consumed by the level shifter. Therefore, unbalance of the cell capacities caused by the current consumed by the level shifter can be reduced or eliminated, and thus the overall capacity of the battery pack can be improved.

Description

technical field [0001] The invention relates to a voltage measurement technology, in particular to a circuit and a method for measuring the voltage of a unit battery in a battery pack. Background technique [0002] Batteries are used in various applications such as electric or hybrid electric vehicles. The usable voltage of a single cell in a battery may be around 2 to 4V, but some systems, such as electric vehicles or hybrid electric vehicles, may require higher voltages, such as 40V. Multiple unit batteries can be connected in series to drive electric vehicles or hybrid electric vehicles. [0003] In the battery management system, the state of the unit battery, such as the voltage of the unit battery, can be detected and measured by a measurement module, such as an analog-to-digital converter (ADC, Analog-to-Digital Converter). The ADC can be constructed from devices that operate at lower voltages. A voltage conversion circuit can be coupled between the unit cells and t...

AI Technical Summary

Problems solved by technology

Similarly, when the cell voltage conversion circuit 120 measures other cells, such as cells 111 and 113-115, current is also consumed

Therefore, the capacities of the cells 111-115 are unbalanced, and the cell 115 at the bottom of the battery pack 110 may have the least capacity relative to the other cells 111-114, thereby affecting the usable capacity of the battery pack 110.

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