An Equilibrium Control Method Based on the gm(1,n) Gray Forecasting Model

Abstract

The invention discloses a GM (1, N) grey forecasting model-based balancing control method. A microcontroller acquires battery monomer voltage in a standing state by utilizing an analog-digital conversion module; the microcontroller judges whether the voltage difference between the average voltage of the acquired monomer voltage and the lowest monomer voltage is greater than the balancing threshold value of the battery, if yes, starting a balancing circuit, otherwise, stopping the balancing circuit; then judging whether the balancing times k of a battery monomer i is greater than the balancing data of the newest set time of the battery monomer I, wherein the balancing data of the newest set time concretely comprises the battery monomer voltage U<i,k-5>- U<i,k-1>, and balancing time te<i,k-5>- te<i,k-1>, wherein k is more than 5; processing the data obtained in the step IV to obtain kst balancing time, starting balancing for balancing time, and standing for ts<i,k> after the balancing is over, thus the balancing control of the time is over, and turning to step 1 for the balancing control next time. According to the GM (1, N) grey forecasting model-based balancing control method, the inconsistency among battery monomers can be effectively improved, and the balancing efficiency can be increased.

Description

technical field [0001] The invention relates to an equilibrium control method based on a GM (1, N) gray prediction model. Background technique [0002] Energy crisis and environmental pollution are two major problems facing the world today. Electric vehicles are widely welcomed by people for their energy saving and environmental protection, and have become the inevitable trend of future automobile development. Lithium-ion batteries are widely used as power sources in electric vehicles and hybrid electric vehicles because of their high energy density, low discharge rate and no memory effect. However, due to the technical constraints of battery manufacturing technology and power management system, a large number of monomers and multi-stage series-parallel connections are required to provide sufficient supply voltage and driving power during the use of power batteries. However, when this type of battery is used in series, it is easy to cause overcharge and overdischarge of so...

AI Technical Summary

Problems solved by technology

[0008] 1) The open circuit voltage of lithium-ion batteries is relatively flat when the SOC is between 30% and 70%. Even if the SOC differs greatly, the corresponding voltage difference is very small. The current is very small, which may even cause the power electronic devices to fail to conduct normally;

[0009] 2) Due to the conduction voltage drop of power electronic devices, it is difficult to achieve zero voltage difference balance between battery cells

But, the main problem that this invention exists is: because belong to Cell to Cell type balance circuit, even if using Boost step-up conversion, the balance current that improves is limited, can't meet the balance demand of electric vehicle large-capacity power battery far away; Boost conversion itself also has energy waste

However, due to the non-linear characteristics of the battery and the existence of ohmic internal resistance, when the battery cell is charged, the battery cell will have an instantaneous boost, which may even be higher than the voltage of other battery cells. The voltage of the battery cell will drop instantly, and the battery voltage has a recovery process, so for the voltage-based equalization control strategy, it is difficult to judge when the battery pack reaches equilibrium

If the time of each equalization is too short, it will cause the switch to switch frequently and increase the total equalization time; if the time of each equalization is too long, it will lead to over-equalization and waste energy

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