Method and device for double-precision SOC (state of charge) test of electric vehicle power battery

Abstract

The invention provides a method and a device for double-precision SOC (state of charge) test of an electric vehicle power battery. The method includes: two current hall devices which are different in variation are serially connected and then serially connected with a power battery module and a comprehensive load module to form a loop; and the two current hall devices transmit signals by means of voltage or current respectively, and the outputted signals are subjected to information processing and then transmitted to a battery management module, so that the problem of inaccurate single current hall test caused by wide current variation range of the power battery is solved. The test range can be 1A-1000A, and sampling accuracy can be guaranteed within the test range. In addition, the problem that signals are easy to be interfered is fundamentally solved by transmitting signals by means of CAN communication instead of analog signals (voltage or current).

Description

technical field [0001] The invention relates to the field of power battery testing, in particular to a double-precision SOC testing method for electric vehicle power batteries. Background technique [0002] like figure 1 The principle block diagram of the test system for the existing electric vehicle power battery SOC (ie State Of Charge, in the battery industry, SOC refers to the state of charge, also known as the remaining capacity, indicating the ability of the battery to continue to work), figure 1 The positive pole of the medium power battery 1 is connected in series with the single Hall current sensor 2 and the positive pole of the capacitive comprehensive load 4 (including the capacitor C1 and the motor B1). The negative pole of the power battery 1 is connected in series with the negative pole of the capacitive load part 4, and the single Hall current sensor The DLJC of 2 is also connected to the BMS of the battery management module 3. The problems of this tradition...

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Problems solved by technology

[0003] 1. The signal transmission method adopts analog signal (voltage or current) transmission, which is easy to be interfered;

[0004] 2. The power battery has a wide range of changes, ranging from 1A-1000A, the measurement range is too wide, and the sampling is not accurate

[0005] As far as sampling is inaccurate, specifically, because 500A current is generally used for Hall test, the measurement accuracy is 500A*0.5%=2.5A; the SOC above 100A is acceptable; while the 500A current Hall measurement is not accurate within 50A, This will result in inaccurate SOC measurement

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