BMS system SOC calculation method based on metering chip

Abstract

The invention relates to a BMS system SOC calculation method based on a metering chip. The metering chip is connected with an MCU and a voltage reference source chip, and the method comprises the following steps: the MCU sends a metering starting command to the metering chip, and the metering chip calculates the charge and discharge quantity containing a voltage coefficient after receiving the metering starting command; the MCU reads the charge and discharge quantity containing the voltage coefficient in the calculation of the metering chip according to the acquisition time sequence defined by the BMS; generating a single battery electric quantity matrix according to the charging and discharging quantity containing the voltage coefficient; meanwhile, generating a temperature sampling point distribution matrix; amplifying the single battery electric quantity matrix and the temperature sampling point distribution matrix into matrixes with the same rows and columns; and performing Collman filtering on the amplified single battery electric quantity matrix and the amplified temperature sampling point distribution matrix in a one-to-one correspondence manner to obtain the SOC value of the single battery. According to the invention, the independent electric energy metering chip is independently responsible for integral work, so that the computing power of the MCU can be greatly saved.

Description

technical field [0001] The invention relates to the technical field of new energy lithium battery energy storage, in particular to a BMS system SOC calculation method based on a metering chip. Background technique [0002] With the country's policy inclination towards the new energy industry, lithium batteries and BMS systems are widely used in many fields. As a very important function of BMS system, SOC estimation of lithium battery is difficult to calculate accurately. [0003] 1. The ampere-hour integration method commonly used at present, its essence lies in accumulating the collected current signals at short and uniform time intervals. However, the commonly used MCU is limited by hardware conditions, and it is difficult to sample the current value at a higher frequency, which makes the integration effect relatively rough and the error larger. The sampling frequency of current in common BMS systems is usually 10 to 200 Hz. If the sampling frequency is too high, it will...

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Problems solved by technology

And if there are many interruptions in other tasks, it is easy to interrupt the timing, resulting in inaccurate timing, which will directly lead to a large SOC error

Since integral calculation requires extremely precise timing, if the interrupt priority is set higher, it will frequently interrupt other tasks that are running normally, and if the sampling frequency is set higher, normal tasks will not be able to run normally; if it is prioritized If the level setting is slightly lower, it is likely to be frequently interrupted by other tasks, which will affect the accuracy

It can be seen that the sampling frequency in the MCU is inherently limited by the system

[0005] 3. Since the MCU may have different loads at different times, the time of the timer is not equal at high loads and at low loads

The consistency of the timer may be very good in a short period of time, but when it is relaxed to a longer period of time, the timer will have a slight time difference due to the different loads of the MCU, which is reflected in the SOC as the slope of the SOC curve Offset, resulting in a large deviation of the overall SOC value

[0006] 4. Since the MCU is at the core of the entire circuit board, it cannot be effectively isolated from other devices, causing it to be seriously affected by heat and cause temperature drift

[0007] 5. In the process of counting the SOC, the BMS system will also count the total charge and discharge capacity of the system. This process is also completed by the ampere-hour integration, so the large error of the ampere-hour integration not only affects the SOC accuracy, but also affects the entire system. The statistics of charging and discharging capacity of the system also have large errors

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