Calibration method of common-mode voltage

Abstract

The invention discloses a common-mode voltage calibration method, a circuit for executing the method comprises a voltage sampling circuit which is used for sampling N groups of series-connected to-be-sampled voltages and comprises N + 1 sampling channels, N is a positive integer greater than or equal to 2, and the method comprises the following steps: sampling a group of to-be-sampled voltages by using every two adjacent sampling channels; sequentially measuring each group of to-be-sampled voltage obtained by sampling through each sampling channel to obtain a to-be-sampled voltage measurement value; and by using each group of to-be-sampled voltage measurement values distributed from the low-voltage side to the high-voltage side, carrying out step-by-step calibration on the higher-level to-be-sampled voltage measurement values so as to eliminate voltage measurement errors caused by common-mode voltage changes. The sampling channel group with the minimum gain error is utilized, and the measurement voltage of the sampling channel group closest to the positive electrode of the battery pack is calibrated upwards step by step, so that the influence caused by the gain error is eliminated, the measurement error is reliably reduced, and the judgment accuracy of the state of each single-junction battery of the battery pack is generally improved.

Description

technical field [0001] The invention relates to a calibration method for a measurement circuit, in particular to a calibration method for common mode voltage sampling of a battery pack chip-level measurement circuit. Background technique [0002] With the continuous development of electronic technology, all kinds of miniature electrical appliances are mostly powered by battery packs in their applications. Therefore, such as miniature battery packs, small power banks, etc., which are composed of as few as a few or as many as dozens of single-cell batteries in series, when a single-cell battery fails, it will affect the health of the entire miniature power supply to a certain extent. degree and preset functions. Traditionally, by disassembling the micro power supply, using an electronic multimeter to measure each single battery one by one, recording the voltage and current, and calculating the internal resistance are all done manually. As a result, some designers propose chi...

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Problems solved by technology

by figure 1 As shown, the sampling channel C16 is the highest level in the battery pack, and its operating voltage varies greatly. For example, the highest operating voltage can reach 60V, and the lowest operating voltage can reach 15V. Under different common-mode voltages, the same as the The capacitance value of the sampling capacitor corresponding to the sampling channel C16 will change, resulting in a gain error in the sampling value of the subsequent ADC, which in turn leads to an increase in the error of the entire measurement chip circuit

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