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Electric vehicle current measurement error
- Aug 21, 2018 -

In practical applications of electric vehicle high-power battery packs, Hall sensors are often used to detect the magnitude of the operating current. Due to the defect of the sensor itself or the inaccurate calibration, there will be a certain systematic error in the actual measurement. Such system error can be positive or negative.

If the error of the current sensor is "positive", then the equivalent of "discharge" from the battery increases, and the SoC estimate presents a "negative" error. Although the voltage observation (U) will be corrected in this process, since the equation of state also works at this time, the correction of the measurement equation can offset some of the systematic errors, but it cannot be completely eliminated.

Second, the morphological problem of the error spectrum curve. The EMF-SoC curve of lithium iron phosphate battery is a “monotonically increasing” function curve, and the curve shows “two steep, moderately flat”. The core of the algorithm for SoC estimation using EKF is EMF based on electric vehicle battery. -SoC curve, for the same current system error, there will be a "large intermediate error, small error at both ends". That is, when the depth of discharge is less than 60%, there is a systematic error in the current measurement, and due to the existence of the state equation, the cumulative error of the system will become larger and larger, until the end of the discharge, as the SoC decreases, the EMF curve continues to become Steep, the Kalman gain becomes larger and larger, and the role of the measurement equation becomes more and more obvious, which makes the previous cumulative error gradually eliminated under the action of EKF.

The above is about the electric motor current measurement error knowledge, knowledge is for reference only, I hope to help you.