TWI496338B - Method of charging and discharging for second life battery with reuse - Google Patents

Description

Charge and discharge method for replacing battery pack

The invention relates to a charging and discharging method for replacing battery packs, in particular, a health state change of a plurality of battery packs for estimating different health states to determine a charge and discharge ratio of the plurality of battery packs. Estimation method.

The secondary battery is also referred to as a rechargeable battery. Compared with the conventional disposable battery, the secondary battery does not need to be discarded immediately after the power is used, and can be repeatedly used by charging. In addition to prolonging the use time, it can reduce environmental impact, and thus is widely used. Mobile phones, computers and electric vehicles and other electrical appliances.

For the secondary battery, the state of health (SOH) can represent the percentage relationship between the current storage capacity of the secondary battery and the initial storage capacity, and can be used as a standard for measuring whether the secondary battery is suitable for continued use. When the secondary battery is applied to different electrical products, the health status of the secondary battery that must be eliminated for different electrical power requirements is different, for example, when the secondary battery is installed in an electric vehicle with high power demand. The standard of the health status of the secondary battery that must be eliminated may be 80%. However, when the secondary battery is set in an electric vehicle having a low power demand, the standard of the health status of the secondary battery that must be eliminated is Can be reduced to 70% or 60%.

Wherein, when the secondary battery is eliminated due to unsuitability for the first application environment condition, since the secondary battery has a lot of remaining energy, it can be applied again in a suitable occasion. Therefore, the replacement battery can also be called a second life battery (Second life of battery). However, since the health status of each of the replacement batteries is different, the cycle life (Cycle Life, CL) of each of the replacement batteries is also different, and when the plurality of replacement batteries are simultaneously combined for power reuse. If the corresponding charge-discharge ratio of different battery states is not replaced, it may cause the cycle life of some replacement batteries to be exhausted early and completely unusable, resulting in the cycle life of the combined replacement batteries. Can not be exhausted at the same time, thereby reducing the efficiency of power reuse.

The main object of the present invention is to provide a charging and discharging method for replacing battery packs, which is to plan a corresponding charging and discharging ratio for batteries of different health states to improve the efficiency of power reuse.

In order to achieve the foregoing object, the present invention provides a charging and discharging method for replacing a battery pack, which comprises: a measuring step of measuring a health state of one of the plurality of batteries by using a measuring module; a group module is divided into a plurality of intervals in a healthy state range, and each battery is grouped into corresponding intervals according to the health state of each battery to form a plurality of battery packs; a discharge estimating step Performing a discharge estimation equation by a processor, and estimating a minimum health state difference of each of the battery packs according to the output power and a discharge depth of each of the battery packs, and then estimating according to the minimum health state difference amount. a discharge ratio of each of the battery packs; and a charge estimation step, wherein the processor performs a charge estimation equation, and estimates a maximum remaining of each of the battery packs according to the discharge ratio of each of the battery packs and an input power amount The amount of electricity is then estimated based on the maximum remaining amount of electricity.

The charging and discharging method for replacing the battery pack of the present invention, wherein the discharge estimating equation comprises a discharge equation, a discharge depth equation, a cycle life equation, a healthy state equation and a minimum difference equation; the discharge equation is used To estimate the remaining power of each battery pack after outputting the output power for each battery pack having a predetermined amount of power; the discharge depth equation is used to estimate the output power of each battery pack and the current a percentage of the maximum amount of stored electricity as the depth of discharge of each of the battery packs; the cycle life equation estimates a cycle life of each of the battery packs according to the depth of discharge of the battery pack and the state of health; The equation updates the health state of each of the battery packs according to the depth of discharge of the battery pack and the cycle life; the minimum difference amount equation estimates the amount of health state difference of each of the battery packs at different discharge ratios, and The minimum value of the health state difference amount is taken as the minimum health state difference amount.

The charging and discharging method for replacing the battery pack of the present invention, wherein the charging estimating equation comprises a charging equation and a maximum difference amount equation; the charging equation is for estimating each battery pack having a predetermined amount of power, after passing through a battery pack After inputting the input electric quantity per unit time, the remaining electric quantity of each of the battery packs; the maximum difference quantity equation is to estimate the remaining electric quantity of each of the battery packs at different charging ratios, and the maximum value of the remaining electric quantity is taken as the maximum remaining electric quantity.

The charging and discharging method for replacing the battery pack of the present invention, wherein the discharge equation is as follows: Q _{B , i} ^t = Q _{B , i} ^{t -1} - I _{Bd , i} ^t . t _use

Where Q _{B, i} ^t represents the remaining power of the i-th battery pack at time t; Q _{B, i} ^t-1 represents the remaining power of the i-th battery pack at time t-1; I _{Bd, i} ^t represents the i-th The output current of the battery pack at time t; t _use represents the unit time formed by time t-1 to time t. .

The charging and discharging method for replacing the battery pack of the present invention, wherein the discharge depth equation is as follows:

Wherein, DOD _i ^k represents the discharge depth after the i-th battery pack simulates charging and discharging k times; Q _{B, i} ^t represents the remaining power of the i-th battery pack at time t; Q _{SOH, i} represents the ith battery pack The current maximum storage capacity.

The charging and discharging method for replacing the battery pack of the present invention, wherein the cycle life equation is as follows: CL _i ^k = ( a ₁ + b ₁ . DOD _i + c ₁ . SOH _i ^{k -1} + d ₁ . DOD _i ² + e ₁ . DOD _i . SOH _i ^{k -1} + f ₁ . DOD _i ³ + g ₁ . DOD _i ² . SOH _i ^{k -1} + h ₁ . DOD _i ⁴ + i ₁ . DOD _i ³ . SOH _i ^{k -1} )-1

Wherein, Cl _i ^k represents the cycle life after the i-th battery pack simulates charging and discharging k times; SOH _i ^k-1 represents the health state after the i-th battery pack simulates charging and discharging k-1 times; DOD _i represents the first The discharge depth of i battery packs; a ₁ ~i ₁ represents several first calculation coefficients, and a ₁ =-1.149×10 ⁴ ; b ₁ =142.5; c ₁ =190.7;d ₁ =-0.4155;e ₁ = -2.224; f ₁ = 0.002076; g ₁ = 0.001385; h ₁ = - 1.994 × 10 ^-5 ; i ₁ = 3.961 × 10 ^-5 .

The charging and discharging method for replacing the battery pack of the present invention, wherein the health state equation is as follows: SOH _i ^k = a ₂ + b ₂ . DOD _i + c ₂ . CL _i ^k + d ₂ . DOD _i ² + e ₂ . DOD _i . CL _i ^k + f ₂ . DOD _i ³ + g ₂ . DOD _i ² . CL _i ^k + h ₂ . DOD _i ⁴ + i ₂ . DOD _i ³ . CL _i ^k

Wherein, SOH _i ^k represents the health state of the i-th battery pack after k times of charge and discharge; Cl _i ^k represents the cycle life after the i-th battery pack simulates charging and discharging k times; DOD _i represents the i-th battery pack Depth of discharge; a ₂ ~ i ₂ represents a number of second calculated coefficients, and a ₂ = 61.93; b ₂ = -0.2839; c ₂ = 0.004168; d ₂ = 0.01122; e ₂ = 0.000209; f ₂ = -0.0001639; g ₂ = - 4.738 × 10 ^-6 ; h ₂ = 7.885 × 10 ^-7 ; i ₂ = 6.636 × 10 ^-8 .

The charging and discharging method for replacing the battery pack of the present invention, wherein the minimum difference amount equation is as follows:

Where SOH _i ^tf represents the last health state of the i-th battery pack, and SOH _j ^tf represents the last health state of the j-th battery pack.

The charging and discharging method for replacing the battery pack of the present invention, wherein the charging equation is as follows: Q _{B , i} ^t = Q _{B , i} ^{t -1} + I _{Bc , i} ^t . t _use

Where Q _{B, i} ^t represents the remaining power of the i-th battery pack at time t ; Q _{B, i} ^t-1 represents the remaining power of the i-th battery pack at time t-1; I _{Bc, i} ^t represents the i-th The input current of the battery pack at time t; t _use represents the unit time formed by time t-1 to time t.

The charging and discharging method for replacing the battery pack of the present invention, wherein the maximum difference amount equation is as follows:

Where Q _{B, i} ^t represents the remaining power of the i-th battery pack at time t.

1‧‧‧Measurement module

2‧‧‧Group Module

3‧‧‧ Processor

S1‧‧‧Measurement steps

S2‧‧‧ grouping steps

S3‧‧‧Discharge estimation procedure

S4‧‧‧Charging estimation procedure

Fig. 1 is a view showing an apparatus for implementing a charge and discharge method for recycling a battery pack of the present invention.

Fig. 2 is a flow chart showing the charging and discharging method for recycling the battery pack of the present invention.

The above and other objects, features and advantages of the present invention will become more <RTIgt; It refers to the percentage relationship between the current maximum storage capacity of a battery and the initial storage capacity. For example, when the current maximum storage capacity of the battery is only 85% of the initial storage capacity, the health status of the battery is 85%.

The term "cycle life" as used in the present invention refers to the number of times of repeated charge and discharge when a maximum amount of stored electricity drops to a certain percentage of the initial stored amount of electricity after repeated charging and discharging for a battery under certain conditions. That is the cycle life.

The term "Depth of Discharge (DOD)" as used in the present invention refers to the ratio of the amount of electricity discharged by a battery to the maximum amount of stored electricity. For example, when the amount of electricity discharged by the battery is 25% of the maximum amount of stored electricity, the battery is The depth of discharge is 25%.

Please refer to FIG. 1 , which is a preferred embodiment of the charging and discharging method for replacing the battery pack of the present invention. The device comprises a measuring module 1 , a grouping module 2 and a processor 3 . . The cluster module 2 is electrically connected to the measurement module 1 , and the processor 3 is electrically connected to the cluster module 2 .

The measuring module 1 is configured to respectively measure the health status of one of the plurality of batteries, and output a measurement result. The measurement module 1 can be any software or hardware used for battery detection. In the embodiment of the present invention, the battery refers to a replacement battery that is not suitable for the previous application environment condition.

The cluster module 2 is electrically connected to the measurement module 1 to receive the measurement result output by the measurement module 1, and according to the health state presented by the measurement result, the measured number is The cells are grouped to form a plurality of battery packs and output a cluster result. The grouping module 2 can be any software or hardware used for comparison and classification. In the embodiment of the present invention, the battery pack refers to a battery pack composed of the plurality of replacement batteries.

More specifically, the grouping module 2 has a health status range, and the health status range is divided into a plurality of sections. The grouping module 2 groups the batteries into phases according to the health status of each of the batteries. Corresponding intervals to form a number of battery packs and as a result of the clustering. The health status range may be between 0 and 100, and a predetermined scale is used as a basis for dividing the interval. For example, when the preset scale is 10, the health status range may be regarded as a first between 100 and 91. In the interval, the health status range can be regarded as a second interval between 90 and 81. When the health status of the battery is 82%, the battery is grouped into the second interval.

The processor 3 is electrically connected to the grouping module 2 to receive the grouping result output by the grouping module, and performs a discharge estimation equation and a charging estimation according to the grouping result. The operation of the equation is to output a charging ratio and a discharge ratio corresponding to each of the battery packs. The processor 3 can be a computer or any computing processor, and can execute an operation equation or a simulation software to perform related operations and statistics. In this embodiment, the processor 3 is configured. There is a Matlab software computer.

Please refer to FIG. 2 , which is a flow chart of a charging and discharging method for replacing the battery pack of the present invention, comprising: a measuring step S1, a grouping step S2, a discharging step S3, and a charging and distributing step S4. .

In the measuring step S1, the measuring module 1 measures the health state of the plurality of batteries.

More specifically, when the plurality of batteries are to be combined for power supply, the health of each of the batteries must be measured by the measurement module 1, and the batteries of different health states are charged accordingly. The discharge ratio is charged and discharged to improve the power supply efficiency. Accordingly, the measuring step S1 can accurately measure the health status of each of the batteries, thereby enabling the batteries of different health states to perform charging and discharging operations according to corresponding charging and discharging ratios.

The grouping step S2 is divided into a plurality of sections in the health state range by the grouping module 2, and each battery is grouped into corresponding sections according to the health state of each battery to form a plurality of battery packs. .

More specifically, when several batteries are to be combined for power supply, after measuring the health status of each battery, batteries having similar health status must be grouped into the same battery pack. Then, each of the battery packs is charged and discharged at a corresponding charge and discharge ratio to improve the power supply efficiency. In addition, in this embodiment, the plurality of batteries selects a battery having a health status of 61% to 80%, and the battery is reused for a battery that does not meet the health condition, and when the preset scale is 5, the The health status range can be divided into four intervals of 80% to 76%, 75% to 71%, 70% to 66%, and 65% to 61%, and the plurality of batteries can be grouped according to the health status of the plurality of batteries. Four battery packs, and each battery pack is operated at a corresponding charge and discharge ratio Charge and discharge operations to reuse the replacement battery. Accordingly, the grouping step S2 can group a plurality of batteries into a plurality of battery packs according to a state of health, and when the selected plurality of batteries are replaced batteries, the efficiency of reuse of the plurality of battery packs can be improved.

The discharge estimating step S3 is performed by the processor, and estimating the minimum health state difference of each of the battery packs according to the output power and the depth of discharge of each of the battery packs, and then according to the minimum health The amount of state difference is used to estimate the discharge ratio of each of the battery packs.

In a preferred embodiment of the present invention, the discharge estimation equation includes a discharge equation, a discharge depth equation, a cycle life equation, a health state equation, and a minimum difference equation. The discharge equation is used to estimate the remaining power of each battery pack after outputting the output power for each battery pack having a predetermined amount of power. The discharge equation is as follows: Q _{B , i} ^t = Q _{B , i} ^{t -1} - I _{Bd , i} ^t . t _use (1)

Where Q _{B, i} ^t represents the remaining power of the i-th battery pack at time t; Q _{B, i} ^t-1 represents the remaining power of the i-th battery pack at time t-1; I _{Bd, i} ^t represents the i-th The output current of the battery pack at time t; t _use represents the unit time formed by time t-1 to time t.

The discharge depth equation is used to estimate the percentage of the output power of each of the battery packs to the current maximum storage capacity as the discharge depth of each of the battery packs. The depth of discharge equation is as follows:

Wherein, DOD _i ^k represents the discharge depth after the i-th battery pack simulates charging and discharging k times; Q _{SOH, i} represents the current maximum storage capacity of the i-th battery pack.

The cycle life equation estimates the cycle life of each of the battery packs based on the depth of discharge of the battery pack and the health state. The cycle life equation is as follows: CL _i ^k = ( a ₁ + b ₁ . DOD _i + c ₁ . SOH _i ^{k -1} + d ₁ . DOD _i ² + e ₁ . DOD _i .SOH _i ^{k -1} + f ₁ . DOD _i ³ + g ₁ . DOD _i ² . SOH _i ^{k -1} + h ₁ . DOD _i ⁴ + i ₁ . DOD _i ³ . SOH _i ^{k -1} )-1 (3)

Wherein, Cl _i ^k represents the cycle life after the i-th battery pack simulates charging and discharging k times; SOH _i ^k-1 represents the health state after the i-th battery pack simulates charging and discharging k-1 times; a ₁ ~i ₁ represents a plurality of first calculation coefficients, and in the embodiment, the plurality of first calculation coefficients are preferably: a ₁ =-1.149×10 ⁴ ; b ₁ =142.5; c ₁ =190.7; d ₁ = -0.4155; e ₁ = -2.224; f ₁ = 0.002076; g ₁ = 0.001385; h ₁ = - 1.994 × 10 ^-5 ; i ₁ = 3.961 × 10 ^-5 .

The health state equation updates the health status of each of the battery packs according to the depth of discharge of the battery pack and the cycle life. The equation of state of health is expressed as follows: SOH _i ^k = a ₂ + b ₂ . DOD _i + c ₂ . CL _i ^k + d ₂ . DOD _i ² + e ₂ . DOD _i . CL _i ^k + f ₂ . DOD _i ³ + g ₂ . DOD _i ² . CL _i ^k + h ₂ . DOD _i ⁴ + i ₂ . DOD _i ³ . CL _i ^k (4)

Wherein, SOH _i ^k represents the health state of the i-th battery pack after k times of charging and discharging; a ₂ ~ i ₂ represents a plurality of second calculation coefficients, and in the embodiment, the plurality of second calculation coefficients are compared Preferably, a ₂ = 61.93; b ₂ = -0.2839; c ₂ = 0.004168; d ₂ = 0.01122; e ₂ = 0.000209; f ₂ = -0.0001639; g ₂ = - 4.738 × 10 ^-6 ; h ₂ = 7.885 ×10 ^-7 ; i ₂ =6.636×10 ^-8 .

The minimum difference quantity equation estimates the health state difference amount of each of the battery packs at different discharge ratios, and uses the minimum value of the health state difference amount as the minimum health state difference amount. The minimum difference equation is expressed as follows:

Wherein, SOH _i ^tf represents the last health state of the i-th battery pack, and SOH _j ^tf represents the last health state of the j-th battery pack, and the total number of the battery packs is N, i, j are positive integers of 1 to N.

Moreover, the discharge ratio of each of the battery packs is as follows:

Wherein, X _Bd,i represents the discharge ratio of the i-th battery pack, and the discharge ratio is a value greater than 0 to less than 1; P _B ^t represents the total power of the plurality of battery packs at time t (W) ; V _{B, i} ^t represents the voltage value (V) of the i-th battery pack at time t.

More specifically, by the operation of the discharge equation, the relationship between the output power of each battery pack at time t and the remaining power can be known, and the depth of discharge of each battery pack can be estimated through the discharge depth equation, and then The discharge depth is substituted into the cycle life equation and the health state equation for calculation, wherein the cycle life equation and the health state equation can be recursively calculated, and each battery pack is calculated for a certain number of discharges (k times) and different discharges The cycle life and the health state of the ratio, and finally, for each of the battery packs under a certain number of discharges (k times), the minimum error amount equation may accumulate the minimum health state difference amount of each of the battery packs. After determining the minimum health state difference amount, the output power of each battery pack in the discharge equation can be checked according to the calculation result, thereby determining the proportional relationship of the output power between the battery groups, and This proportional relationship is taken as the discharge ratio of each of the battery packs. Here, the number of discharges is set to 4000 times in this embodiment.

Further, in the discharge estimating step S3, the discharge estimating equation can determine the minimum health state difference amount of each of the battery packs, and when each of the battery packs has a minimum health state difference amount, that is, After the battery pack is used for a certain period of time, the remaining cycle life of each of the battery packs will approach the same. Therefore, after calculating the minimum health state difference amount of each of the battery packs, the discharge ratio of each of the battery packs can be determined according to the minimum health state difference amount, and when each of the battery packs discharges according to the discharge ratio, The remaining cycle life of each of the battery packs is gradually approached to be the same, so that the cycle life of the plurality of battery packs can be simultaneously exhausted, so that Improve the efficiency of power reuse.

The charging estimation step S4 is performed by the processor 3 to calculate a charging estimation equation, and estimating the maximum remaining power of each of the battery packs according to the discharge ratio of each of the battery packs and an input power amount, and then according to the maximum remaining power. , estimating the charging ratio of one of the battery packs.

In a preferred embodiment of the invention, the charge estimation equation includes a charging equation and a maximum difference equation. The charging equation is used to estimate the remaining power of each of the battery packs after the input of the input power by one unit of time for each of the battery packs having a predetermined amount of power. The charging equation is as follows: Q _{B , i} ^t = Q _{B , i} ^{t -1} + I _{Bc , i} ^t . t _use (8)

Where Q _{B, i} ^t represents the remaining power of the i-th battery pack at time t; Q _{B, i} ^{t -1} represents the remaining power of the i-th battery pack at time t-1; I _{Bc, i} ^t represents the i-th The input current of the battery pack at time t; t _use represents the unit time formed by time t-1 to time t.

The maximum difference quantity equation estimates the maximum remaining power of each of the battery packs, and the maximum difference amount equation is as follows:

Moreover, the charging ratio of each of the battery packs is as follows:

I _{Bd , i} ^t =( P _B ^t . X _{Bc , i} )/ V _{B , i} ^t (11)

Wherein, X _Bc,i represents the charging ratio of the i-th battery pack, and the charging ratio is a value greater than 0 to less than 1; P _B ^t represents the total power of the plurality of battery packs at time t (W) ; V _{B, i} ^t represents the voltage value (V) of the i-th battery pack at time t.

More specifically, after the discharge ratios of the battery packs are determined by the discharge estimating step S3, the remaining power of each of the battery packs after being discharged can be substituted into the charge. The electric equation is calculated to calculate the relationship between the input power of each battery pack at time t and the remaining power at each different charging ratio, and finally, for each battery pack under a certain number of charging times (k times), The maximum difference amount equation can accumulate the maximum remaining amount of each of the battery packs. After determining the maximum remaining power, the input power of each battery pack in the charging equation can be checked according to the calculation result, thereby determining the proportional relationship of the input power between the battery groups, and using the ratio The relationship is the charging ratio of each of the battery packs, and the number of times of charging is set to 4000 times in this embodiment.

Further, in the charging estimation step S4, the charging estimation equation can determine the maximum remaining power of each of the battery packs, and when each of the battery packs has a maximum remaining power, that is, the battery pack is in a certain state. During the use of time, each of the battery packs has the highest available power. Therefore, after calculating the maximum remaining power of each of the battery packs, the charging ratio of each of the battery packs may be determined according to the maximum remaining power amount, and after each of the battery packs is discharged according to the discharge ratio of the discharge estimating step S3, When charging is performed by the charging ratio, each of the battery packs can have the highest available power, thereby improving the efficiency of power recycling.

In summary, the present invention is directed to batteries of different health states, first estimating the use efficiency of each battery under different discharge ratios, and then finding the discharge ratio of each battery under the optimal use efficiency, and then according to the The discharge ratio is used to estimate the efficiency of each battery under different charging ratios, and then the charging ratio of each battery under the optimal use efficiency is found to improve the efficiency of power recycling.

While the invention has been described in connection with the preferred embodiments described above, it is not intended to limit the scope of the invention. The technical scope of the invention is protected, and therefore the scope of the invention is defined by the scope of the appended claims.

S1‧‧‧Measurement steps

S2‧‧‧ grouping steps

S3‧‧‧Discharge estimation procedure

S4‧‧‧Charging estimation procedure

Claims (10)

A charging and discharging method for replacing a battery pack includes: a measuring step of measuring a health state of one of the plurality of batteries by using a measuring module; and a grouping step of using a cluster module in a health The state range is divided into a plurality of intervals, and each battery is grouped into corresponding intervals according to the health state of each battery to form a plurality of battery packs; and a discharge estimating step is performed by a processor to perform a discharge estimation An equation, and estimating a minimum health state difference amount of each of the battery packs according to the output power and a discharge depth of each of the battery packs, and estimating a discharge ratio of each of the battery packs according to the minimum health state difference amount; and a charging estimation step is performed by the processor, and estimating a maximum remaining power of each of the battery packs according to the discharge ratio and an input power of each battery pack, and estimating the maximum remaining power according to the maximum remaining power. One of the charging ranges of each of the battery packs. The charging and discharging method for replacing a battery pack according to the first application of the patent scope, wherein the discharge estimating equation comprises a discharge equation, a discharge depth equation, a cycle life equation, a health state equation and a minimum difference equation The discharge equation is used to estimate the remaining power of each battery pack after outputting the output power for each battery pack having a predetermined amount of power; the discharge depth equation is used to estimate each battery pack The discharge power is the percentage of the current maximum stored electricity as the discharge depth of each of the battery packs; the cycle life equation estimates the cycle life of each of the battery packs according to the depth of discharge of the battery pack and the health state The health state equation updates the health state of each of the battery packs according to the depth of discharge of the battery pack and the cycle life; the minimum difference amount equation estimates the health state difference of each of the battery packs at different discharge ratios. Quantity, and the minimum value of the difference in health status is used as the minimum health status difference the amount. The charge and discharge method for replacing a battery pack according to the first aspect of the patent application, wherein the charge estimation equation includes a charging equation and a maximum difference equation; the charging equation is used to estimate each of the predetermined power amounts The battery pack, after inputting the input power for one unit time, the remaining power of each battery pack; the maximum difference equation is to estimate the remaining power of each battery pack at different charging ratios, and the maximum value of the remaining power As the maximum remaining power. According to the charging and discharging method of replacing the battery pack according to item 2 of the patent application scope, the discharge equation is as follows: Q _{B , i} ^t = Q _{B, i} ^{t -1} - I _{Bd , i} ^t . t _use where Q _{B, i} ^t represents the remaining power of the i-th battery pack at time t; Q _{B, i} ^{t -1} represents the remaining power of the i-th battery pack at time t-1; I _{Bd, i} ^t represents The output current of the i-th battery pack at time t; t _use represents the unit time formed by time t-1 to time t. According to the charging and discharging method of replacing the battery pack according to the second item of the patent application scope, the discharge depth equation is as follows: Wherein, DOD _i ^k represents the discharge depth after the i-th battery pack simulates charging and discharging k times; Q _{B, i} ^t represents the remaining power of the i-th battery pack at time t; Q _{SOH, i} represents the ith battery pack The current maximum storage capacity. According to the charging and discharging method of replacing the battery pack according to the second item of the patent application scope, the cycle life equation is as follows: CL _i ^k = ( a ₁ + b ₁ . DOD _i + c ₁ . SOH _i ^{k - 1} + d ₁ . DOD _i ² + e ₁ . DOD _i . SOH _i ^{k -1} + f ₁ . DOD _i ³ + g ₁ . DOD _i ² . SOH _i ^{k -1} + h ₁ . DOD _i ⁴ + i ₁ DOD _i ³ . SOH _i ^{k -1} )-1 where Cl _i ^k represents the cycle life after the i-th battery pack simulates charging and discharging k times; SOH _i ^{k -1} represents the i-th battery pack analog charging and discharging Health state after k-1 times; DOD _i represents the discharge depth of the i-th battery pack; a ₁ ~ i ₁ represents several first calculation coefficients, and a ₁ = - 1.149 × 10 ⁴ ; b ₁ = 142.5; ₁ = 190.7; d ₁ = -0.4155; e ₁ = -2.224; f ₁ = 0.002076; g ₁ = 0.001385; h ₁ = - 1.994 × 10 ^-5 ; i ₁ = 3.961 × 10 ^-5 . According to the charging and discharging method of replacing the battery pack according to the second item of the patent application scope, the equation of the health state is as follows: SOH _i ^k = a ₂ + b ₂ . DOD _i + c ₂ . CL _i ^k + d ₂ . DOD _i ² + e ₂ . DOD _i . CL _i ^k + f ₂ . DOD _i ³ + g ₂ . DOD _i ² . CL _i ^k + h ₂ . DOD _i ⁴ + i ₂ . DOD _i ³ . CL _i ^k where SOH _i ^k represents the health state of the i-th battery pack after k times of charge and discharge; Cl _i ^k represents the cycle life after the i-th battery pack simulates charging and discharging k times; DOD _i represents the i-th The depth of discharge of the battery packs; a ₂ ~ i ₂ represents a number of second calculated coefficients, and a ₂ = 61.93; b ₂ = -0.2839; c ₂ = 0.004168; d ₂ = 0.01122; e ₂ = 0.000209; f ₂ = -0.0001639; g ₂ = - 4.738 × 10 ^-6 ; h ₂ = 7.885 × 10 ^-7 ; i ₂ = 6.636 × 10 ^-8 . According to the charging and discharging method of replacing the battery pack according to item 2 of the patent application scope, the minimum difference amount equation is as follows: Where SOH _i ^tf represents the last health state of the i-th battery pack, and SOH _j ^tf represents the last health state of the j-th battery pack. According to the charging and discharging method of replacing the battery pack according to Item 3 of the patent application scope, the charging equation is as follows: Q _{B , i} ^t = Q _{B , i} ^{t -1} + I _{Bc , i} ^t . t _use where Q _{B, i} ^t represents the remaining power of the i-th battery pack at time t; Q _{B, i} ^t-1 represents the remaining power of the i-th battery pack at time t-1; I _{Bc, i} ^t represents The input current of the i-th battery pack at time t; t _use represents the unit time formed by time t-1 to time t. According to the charging and discharging method of replacing the battery pack according to the third item of the patent application scope, the maximum difference amount equation is as follows: Where Q _{B, i} ^t represents the remaining power of the i-th battery pack at time t.