SOC (State of Charge) estimation method for battery pack of ring art mower

Abstract

The invention discloses a SOC (State of Charge) estimation method for a battery pack of a ring art mower. The battery pack of the mower is formed by connecting a plurality of battery monomers in series, the SOC and the health state of each battery monomer obtained by a battery monomer state estimator are used as input, and a fault battery monomer can be found out in time by a fault battery discriminator; the nominal capacity of the battery pack and the model parameters of the battery pack can be accurately corrected according to fault battery monomer information, on one hand, a battery pack SOC feedback value is superposed through the battery pack SOC before feedback, and a battery pack SOC estimation value is generated; on the other hand, the battery pack SOC estimation value is combined with battery pack model parameters to be input into a battery state feedback device to obtain a battery pack SOC feedback value, and the cycle is repeated until discharging of the battery pack is finished, so that the battery pack SOC estimation precision is improved, the battery pack management capacity is further improved, and the battery life is further prolonged.

Description

technical field [0001] The invention relates to the technical field of lawnmower battery pack management, in particular to a method for estimating the state of charge of a Huanyi lawnmower battery pack. Background technique [0002] Compared with oil-powered lawn mowers, electric lawn mowers have become the main direction for the future development of Huanyi lawn mowers due to their advantages such as low noise, less pollution, and convenient use, and have been widely used in cities, especially in public green spaces and Family green space and other occasions. [0003] The battery pack is the main power source of Huanyi electric lawn mower. Whether it can run safely and reliably directly determines the economy and stability of the lawn mower; to accurately obtain the current state of charge (SOC) of the battery pack, That is, the actual power of the battery pack can not only improve the safe and reliable operation of the battery pack, but also improve the life of the batter...

AI Technical Summary

Problems solved by technology

However, due to the influence of battery materials, manufacturing level, and use environment, the battery pack is generally composed of multiple battery cells connected in series, and the SOC and state of health (SOH) of each battery cell in the battery pack are not the same. Inconsistency, leading to premature discharge of the battery cells in the battery pack or damage due to aging, that is, a faulty battery, which seriously affects the accurate acquisition of the SOC of the battery pack

[0004] At present, research and patents on battery SOC estimation at home and abroad are concentrated on battery cells, while the method for battery pack SOC estimation is still immature; the patent (ZL2015104171032) discloses a series battery system modeling method based on a parameter corrector , this method considers the feedback effect of the battery system terminal voltage measurement value on the battery system SOC during the modeling process, but does not consider the impact of the inconsistency of each battery cell on it, resulting in limited accuracy of the SOC obtained from the battery system model; patent ( CN108090319A) discloses a modeling method for a series lithium-ion battery system. In the modeling process, the method considers the influence of the battery cell terminal voltage inconsistency on the SOC of the battery system. Its SOC improvement method is: according to the known lithium-ion battery Cell model, using the working characteristics of the series circuit and the screening method to establish the basic model of the battery system; then detect the terminal voltage of each battery cell, and use it and 1 / N of the output voltage of the basic model as the input of the SOC calibrator of each cell ; Then N monomer SOC compensation values ​​are obtained by N monomer SOC correctors, and the battery system SOC compensation value is obtained by weighting, and then superimposed with the SOC output by the battery system model to obtain the corrected SOC, thereby updating the basic model of the battery system

This method takes into account the impact of battery cell terminal voltage inconsistency on the battery system SOC, and improves the accuracy of battery system SOC estimation to a certain extent, but there are still the following problems: First, it only considers the impact of battery cell terminal voltage inconsistency on the battery system. The influence of SOC deviation does not consider the impact of the battery system capacity change due to the inconsistent terminal voltage of the battery cell, resulting in limited SOC accuracy; the second is that the battery system model output voltage (virtual value) and the measured battery system terminal voltage ( The actual value) constitutes the feedback control function; the third is when calculating the SOC compensation value, the N single SOC correctors get N single SOC compensation values, and the battery system SOC compensation value is obtained by weighting. When the battery system is connected in series When the number of batteries is large, the control difficulty and system instability are increased; the patent (CN2019110348358) discloses a modeling method for a parallel battery system, which takes into account the inconsistency of each branch current of the battery system during the modeling process. The impact of battery system capacity changes, while considering the SOC feedback control effect of the battery system model output voltage (virtual value) and the measured battery system terminal voltage (actual value), improves the battery system SOC accuracy and model accuracy, but still There are the following problems: First, failures caused by the end of discharge or aging of single or multiple battery cells are not considered, especially its impact on the change of the nominal capacity of the battery pack and the specific calculation expressions; Faults caused by the end of discharge or aging of single or multiple battery cells, especially their influence on the change of battery pack model parameters and specific calculation expressions; the third is that the battery cell SOC and SOH, battery pack voltage and current , lawn mower motor operating characteristics, etc. jointly build the battery fault judgment condition, so there is an urgent need for a method for estimating the state of charge of the battery pack of the Huanyi lawn mower to solve the above problems

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