A battery pack charging and discharging control system and method

Abstract

The present invention relates to a battery pack charge and discharge control system and method, wherein the battery pack charge and discharge control system comprises: a battery charge and discharge sequence rotation topology circuit and a control unit; the battery charge and discharge sequence rotation topology circuit comprises a battery pack connected by N batteries, and a conversion switch connected to the battery pack; the battery charge and discharge sequence rotation topology circuit rotates the connection sequence of the N batteries according to the on and off of the conversion switch; the control unit has a built-in battery charge and discharge sequence rotation strategy, the conversion switch is connected to the control unit, and the control unit controls the on and off of the conversion switch according to the battery charge and discharge sequence rotation strategy. According to the technical solution provided by the present invention, the battery life consistency of the battery pack can be maintained as a whole.

Description

Technical Field

[0001] The present invention relates to the technical field of battery equalization management, and in particular to a battery pack charge and discharge control system and method. Background Art

[0002] Recycling and screening of retired battery packs revealed that the head battery close to the total positive pole of the battery pack and the end battery close to the total negative pole are more likely to become lagging batteries, and their aging speed and failure rate are generally higher than those of the middle batteries far away from the total positive pole and the total negative pole. The reason for this phenomenon is that, on the one hand, the heat dissipation environment of batteries at different positions in the battery pack is different, and on the other hand, the surge current generated at the power-on moment of charging and discharging of the battery pack often first impacts the head and end batteries of the battery pack. The accumulation of multiple surges makes the batteries at the head or end of the battery pack prone to premature aging and shortened lifespan. Summary of the invention

[0003] In order to solve the problem that the batteries at the head and tail of the battery pack are more prone to premature aging and shortened life, the present invention proposes a solution that each time the battery pack is turned on for charging and discharging, the connection order of the batteries is rotated first, so that the number of times each battery becomes the head or tail battery remains uniform.

[0004] The technical solution adopted by the present invention to solve the technical problem is as follows:

[0005] In a first aspect, the present invention provides a battery pack charge and discharge control system for uniformly rotating the connection sequence of battery charge and discharge to maintain the consistency of battery life of the battery pack, comprising: a battery charge and discharge sequence rotation topology circuit and a control unit; the battery charge and discharge sequence rotation topology circuit comprises a battery pack connected by N batteries, and a conversion switch battery connected to the battery pack; the charge and discharge sequence rotation topology circuit rotates the connection sequence of the N batteries according to the on and off of the conversion switch; the control unit has a built-in battery charge and discharge sequence rotation strategy, the conversion switch is connected to the control unit, and the control unit controls the on and off of the conversion switch according to the battery charge and discharge sequence rotation strategy.

[0006] In a second aspect, the present invention provides a battery pack charge and discharge control method, comprising the steps of: S1, constructing a battery charge and discharge sequence rotation topology circuit, in which the connection sequence of batteries in the battery charge and discharge sequence rotation topology circuit can be dynamically rotated; S2, constructing a battery charge and discharge sequence rotation strategy and building it into a control unit, and the control unit can control the connection sequence of batteries during charging and discharging according to the battery charge and discharge sequence rotation strategy; S3, when the battery pack is connected for charging and discharging, the control unit first extracts the battery connection sequence of the last charge and discharge, and then determines the battery connection sequence of the current charge and discharge in combination with the battery charge and discharge sequence rotation strategy, and controls the battery pack to be connected for charging and discharging according to the battery connection sequence of the current charge and discharge.

[0007] The beneficial effects of the present invention are:

[0008] The present invention makes each battery become the first-end or last-end battery evenly by first rotating the connection sequence of the batteries at the start of each charge and discharge, thereby balancing the chances of each battery aging prematurely and shortening its life due to accumulated surge current impacts, thereby maintaining the consistency of the battery life of the battery pack as a whole. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a structural diagram of a battery pack charge and discharge control system.

[0010] Figure 2 It is a structural schematic diagram of a battery charge and discharge sequence rotation topology circuit.

[0011] Figure 3 The connection diagram is a diagram of four batteries being connected as an example, in which the charging and discharging connection sequence is B1-B2-B3-B4.

[0012] Figure 4 The connection diagram is a connection diagram of four batteries, in which the charging and discharging connection sequence is B4~B1~B2~B3.

[0013] Figure 5 The connection diagram is a connection diagram of four batteries, in which the charging and discharging connection sequence is B3-B4-B1-B2.

[0014] Figure 6 The connection diagram is a connection diagram of four batteries, in which the charging and discharging connection sequence is B2~B3~B4~B1.

[0015] Figure 7 It is a flow chart of a battery pack charge and discharge control method. DETAILED DESCRIPTION

[0016] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments:

[0017] At the moment when the battery pack starts charging and discharging, a very short-term surge current appears. The surge current value often exceeds the working current of the battery. When the surge current value exceeds the set threshold, it is often protected by the overcurrent protection of the battery protection board to ensure the safety of the battery. However, due to the electrochemical characteristics of the battery, in some special cases, such as when the battery is over-discharged and then recharged, it is first necessary to use trickle charging for remediation. In this case, the surge current may not be intercepted by the protection board because it is within the working current range of the battery, but it will still cause damage to the battery, especially the head and end batteries of the battery pack are most susceptible to surge impacts. In the prior art, the connection order of the battery pack is fixed, and long-term damage accumulation causes the head and end batteries to become lagging batteries, affecting the overall performance and life of the battery pack.

[0018] Please refer to Figure 1 The present invention provides a battery pack charge and discharge control system, which is used for uniformly rotating the connection sequence of battery charge and discharge to maintain the consistency of battery life of the battery pack, including: a battery charge and discharge sequence rotation topology circuit and a control unit; the battery charge and discharge sequence rotation topology circuit includes a battery pack connected by N batteries, and a conversion switch connected to the battery pack; the battery charge and discharge sequence rotation topology circuit rotates the connection sequence of the N batteries according to the on-off of the conversion switch; the control unit has a built-in battery charge and discharge sequence rotation strategy, the conversion switch is connected to the control unit, and the control unit controls the on-off of the conversion switch according to the battery charge and discharge sequence rotation strategy.

[0019] Specifically, for the sake of connection and use stability, the physical placement of the battery pack remains relatively fixed. To rotate the order of charge and discharge connections, it is necessary to implement it through a rotation topology circuit, that is, through the switching on and off of the switch. The switching on and off of the switch is automatically controlled by the control unit according to the rotation strategy, thereby achieving a combination of the fixed physical position of the battery and the rotation of the charge and discharge connection sequence.

[0020] For further information, please refer to Figure 2 The battery charge and discharge sequence rotation topology circuit includes: the positive and negative poles of N batteries are connected end to end, wherein the negative pole of the last battery is connected to the positive pole of the first battery to form a series ring structure; wherein every two connected batteries are bridged by a bipolar conversion switch, the input end of the bipolar conversion switch is connected to the negative pole between the connected batteries, one of the output ends can be connected to the positive pole between the connected batteries, and the other output end can be connected to the total negative pole of the battery pack; the positive pole of each battery can be connected to the total positive pole of the battery pack through a unipolar conversion switch.

[0021] Specifically, the positive electrode of each battery is B+, and the negative electrode is B-, the total positive electrode of the battery pack is P+, and the total negative electrode is P-. In the prior art, when N batteries are connected, the positive and negative electrodes are connected end to end, and the positive electrode B+ of the first-end battery and the negative electrode B- of the last-end battery are not connected. The positive electrode B+ of the first-end battery is the total positive electrode P+ of the battery pack, and the negative electrode B- of the last-end battery is the total negative electrode P- of the battery pack. The rotation strategy in the present invention requires that each battery can be rotated to become a first-end battery and a last-end battery. Therefore, the connection method is that all batteries can be connected end to end to form a ring, the positive electrode B+ of each battery can be connected to the negative electrode B- of another battery, and the positive electrode B- of each battery can be connected to the positive electrode B+ of another battery, so that each battery can be controlled to become a first-end or last-end battery.

[0022] Furthermore, the battery charging and discharging sequence rotation strategy is specifically as follows: each time the battery pack is connected for charging and discharging, first determine that a battery in the serial ring structure is arranged in the first position, and the batteries connected in sequence are arranged in the second to nth positions according to the preset battery series ranking rule; connect the unipolar conversion switch connected to the positive pole of the first battery to the total positive pole of the battery pack, connect the output end of the bipolar conversion switch connected to the negative pole of the nth battery to the total negative pole of the battery pack, and connect the output end of the bipolar conversion switch connected to the negative pole of the 2nd to n-1st battery to the connected positive pole of the battery, so as to form the battery connection sequence for the current charge and discharge. Among them, the preset battery series ranking rule is: number a battery in the serial ring structure as B1, and the batteries connected in sequence are numbered as B2, ..., Bn-1, Bn; create an N-order circulant matrix Order with B1, B2, ..., Bn-1, Bn as elements:

[0023]

[0024] If the battery pack is connected for charging and discharging for the first time, the order of elements of the first row vector [B1, B2, ..., Bn-1, Bn] of the N-order cyclic array Order is selected as the connection order for the first charge and discharge; for subsequent connections for charging and discharging, the elements of the second to nth row vectors are selected in sequence as the connection order for the second to nth charges and discharges; after the nth row vector is selected as the connection order for charging and discharging, return to the first row vector and start selecting in sequence in a cycle.

[0025] Specifically, the idea of ​​matching the row vector of the N-order cyclic array with the battery connection rotation sequence of the topological circuit is adopted to realize the uniform rotation of the battery connection sequence. The following is an example of 4 battery connections. The specific rotation connection method according to the 4-order cyclic array is as follows: (1) For the first charge and discharge, please refer to Figure 3 , take the first row vector of the 4-order cyclic array as the connection sequence: B1~B2~B3~B4, that is, B1 is the first end battery, B4 is the end battery, B2 and B3 are the connection sequence of the middle batteries; (2) For the second charge and discharge, please refer to Figure 4 , take the second row vector of the 4-order cyclic array as the connection order: B4~B1~B2~B3, that is, take the terminal battery B4 of the last (first) charge and discharge as the first battery, the first battery B1 of the last (first) charge and discharge is connected to the first battery B4 of this (second) charge and discharge to become the middle battery, and the middle battery B3 connected before the terminal battery of the last (first) charge and discharge becomes the terminal battery of this (second) charge and discharge; (3) For the third charge and discharge, please refer to Figure 5, take the third row vector of the 4-order cyclic array as the connection order: B3~B4~B1~B2, that is, take the terminal battery B3 of the last (second) charge and discharge as the first battery, the first battery B4 of the last (second) charge and discharge is connected after the first battery B3 of this (third) charge and discharge to become the middle battery, and the middle battery B2 connected before the terminal battery of the last (second) charge and discharge is the terminal battery of this (third) charge and discharge; (4) The fourth charge and discharge is carried out according to the same rotation rule, please refer to Figure 6 , the connection order of the 4th row vector of the 4th order circulant matrix is: B2~B3~B4~B1; (5) During the fifth charge and discharge, the connection order is returned to the first row vector of the 4th order circulant matrix; the subsequent charge and discharge cycles take the row vector of the 4th order circulant matrix as the battery connection order.

[0026] Furthermore, the conversion switch may be a MOS tube or a relay.

[0027] Specifically, both MOS tubes and relays can be used as conversion switches. Whether to use MOS tubes or relays can be reasonably adopted according to different usage scenarios. Using MOS tubes for switch control has the characteristics of higher response speed, but in some applications with high current, using relays as switches is more stable.

[0028] The present invention also provides a battery pack charge and discharge control method, comprising the steps of: S1, constructing a battery charge and discharge sequence rotation topology circuit, in which the connection sequence of batteries can be dynamically rotated; S2, constructing a battery charge and discharge sequence rotation strategy and building it into a control unit, wherein the control unit can control the connection sequence of batteries during charging and discharging according to the battery charge and discharge sequence rotation strategy; S3, when the battery pack is connected for charging and discharging, the control unit first extracts the battery connection sequence of the last charge and discharge, and then determines the battery connection sequence of the current charge and discharge in combination with the battery charge and discharge sequence rotation strategy, and controls the battery pack to be connected for charging and discharging according to the battery connection sequence of the current charge and discharge.

[0029] Specifically, the topological circuit and the rotation strategy cooperate with each other. The topological circuit is built according to the rotation strategy, and the rotation strategy requires the support of the topological circuit to be implemented.

[0030] Furthermore, the battery charge and discharge sequence rotation topology circuit includes: the positive and negative poles of N batteries are connected end to end, wherein the negative pole of the last battery is connected to the positive pole of the first battery to form a series ring structure; wherein every two connected batteries are bridged by a bipolar conversion switch, wherein the input end of the bipolar conversion switch is connected to the negative pole between the connected batteries, one of the output ends can be connected to the positive pole between the connected batteries, and the other output end can be connected to the total negative pole of the battery pack; the positive pole of each battery can be connected to the total positive pole of the battery pack through a unipolar conversion switch.

[0031] Furthermore, the battery charge and discharge sequence rotation strategy is as follows: each time the battery pack is connected for charge and discharge, first, according to the preset battery series ranking rule, a battery in the series ring structure is determined to be arranged in the first position, and the batteries connected thereafter are arranged in the second to nth positions; the unipolar conversion switch connected to the positive pole of the first battery is connected to the total positive pole of the battery pack, the output end of the bipolar conversion switch connected to the negative pole of the nth battery is connected to the total negative pole of the battery pack, and the output end of the bipolar conversion switch connected to the negative pole of the 2nd to n-1st batteries is connected to the positive pole of the connected batteries, thereby forming the battery connection sequence for the current charge and discharge.

[0032] Furthermore, the preset battery series ranking rule is: a battery in the series ring structure is numbered as B1, and the batteries connected thereafter are numbered B2, ..., Bn-1, Bn in sequence; an N-order circulant matrix Order is created with B1, B2, ..., Bn-1, Bn as elements:

[0033]

[0034] If the battery pack is connected for charging and discharging for the first time, the order of elements of the first row vector [B1, B2, ..., Bn-1, Bn] of the N-order cyclic array Order is selected as the connection order for the first charge and discharge; for subsequent connections for charging and discharging, the elements of the second to nth row vectors are selected in sequence as the connection order for the second to nth charges and discharges; after the nth row vector is selected as the connection order for charging and discharging, return to the first row vector and start selecting in sequence in a cycle.

[0035] It should be noted that in this solution, the number of batteries in the battery pack is not less than 3, and the so-called charging and discharging refers to one charge or discharge, that is, one sequence rotation is performed when charging is connected, and one sequence rotation is performed when discharging is connected, and "charging and discharging" is used for unified description. In this solution, the so-called "battery" includes but is not limited to lithium batteries, lead-acid batteries, nickel-metal hydride batteries and nickel-chromium batteries.

[0036] This solution can be applied to new battery packs to avoid or slow down the inconsistency of battery life, and can also be applied to the cascade utilization of retired batteries. In the cascade utilization, it is necessary to go through a recycling screening process, the model and material of the reorganized batteries need to be from the same batch, and each battery needs to have consistency in performance and capacity.

[0037] For those skilled in the art, various other corresponding changes and deformations can be made according to the technical solutions and concepts described above, and all of these changes and deformations should fall within the protection scope of the claims of the present invention.

[0038] It should be noted that the above-described embodiments are only some embodiments of the present invention, rather than all embodiments. The singular forms "a", "the", "this time", "that", "last time" and "the" used in the embodiments and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

Claims

1. A battery pack charge and discharge control system for uniformly rotating the battery charge and discharge connection sequence to maintain the consistency of battery life of the battery pack, characterized in that: include: Battery charge and discharge sequence rotation topology circuit and control unit; The battery charge and discharge sequence rotation topology circuit includes a battery pack connected by N batteries, and a conversion switch connected to the battery pack; the battery charge and discharge sequence rotation topology circuit rotates the charge and discharge connection sequence of the N batteries according to the on and off of the conversion switch; The control unit has a built-in battery charge and discharge sequence rotation strategy, the conversion switch is connected to the control unit, and the control unit controls the on and off of the conversion switch according to the battery charge and discharge sequence rotation strategy. The connection mode of the N batteries is that all batteries are connected end to end to form a ring, and each battery can be rotated to become a first-end battery or a last-end battery under the control of the battery charge and discharge sequence rotation strategy. The batteries other than the first-end battery and the last-end battery are intermediate batteries. Each time the charge and discharge is turned on, the connection sequence of the batteries is rotated first, so that each battery becomes the first-end battery or the last-end battery evenly, and the life consistency of the N batteries in the battery pack is maintained as a whole; The battery charge and discharge sequence rotation topology circuit comprises: The positive and negative electrodes of N batteries are connected end to end, and the negative electrode of the last battery is connected to the positive electrode of the first battery to form a series ring structure; Every two connected batteries are connected across a bipolar switch, wherein the input end of the bipolar switch is connected to the negative pole between the connected batteries, one of the output ends can be connected to the positive pole between the connected batteries, and the other output end can be connected to the total negative pole of the battery group; The positive terminal of each battery can be connected to the total positive terminal of the battery pack through a single-pole change-over switch; The battery charging and discharging sequence rotation strategy is: Each time the battery pack is connected for charging and discharging, firstly, according to the preset battery series ranking rule, a battery in the series ring structure is determined to be arranged at the first position, and the batteries connected thereafter are arranged at the second to nth positions; Connect the single-pole switch connected to the positive pole of the first battery to the total positive pole of the battery pack. Connect the output end of the bipolar switch connected to the negative pole of the nth battery to the total negative pole of the battery pack. Connect the output end of the bipolar conversion switch connected to the negative electrode of the battery from the 2nd to the n-1th position to the positive electrode of the connected battery, so as to form the battery connection sequence for the current charge and discharge; The preset battery series ranking rule is: A battery in the serial ring structure is numbered B1, and the batteries connected thereto are numbered B2, ..., Bn-1, and Bn in sequence; Create an N-order circulant matrix Order with B1, B2, ..., Bn-1, Bn as elements: If the battery pack is connected for charging and discharging for the first time, the order of elements of the first row vector [B1, B2, ..., Bn-1, Bn] of the N-order cyclic array Order is selected as the first charging and discharging connection order; For subsequent connection charging and discharging, the elements of the 2nd to nth row vectors are selected in sequence as the connection sequence of the 2nd to nth charging and discharging; After selecting the nth row vector as the charging and discharging connection sequence, return to the first row vector and start selecting in sequence in a loop; N is 4, and the specific rotation connection mode of the 4-order cyclic array is as follows: (1) During the first charge and discharge, the first row vector of the 4-order cyclic array is taken as the connection sequence: B1-B2-B3-B4, that is, B1 is the head battery, B4 is the end battery, and B2 and B3 are the middle batteries; (2) During the second charge and discharge, the second row vector of the 4-order cyclic array is taken as the connection sequence: B4-B1-B2-B3, that is, the end battery B4 of the first charge and discharge is taken as the head battery, the head battery B1 of the first charge and discharge is connected after the head battery B4 of the second charge and discharge to become the middle battery, and the middle battery B3 connected before the end battery of the first charge and discharge becomes the end battery of the second charge and discharge; (3) During the third charge and discharge, the first row vector of the 4-order cyclic array is taken as the connection sequence: B4-B1-B2-B3, that is, the end battery B4 of the first charge and discharge is taken as the head battery, the head battery B1 of the first charge and discharge is connected after the head battery B4 of the second charge and discharge to become the middle battery, and the middle battery B3 connected before the end battery of the first charge and discharge becomes the end battery of the second charge and discharge; During discharge, the third row vector of the 4th-order cyclic array is taken as the connection sequence: B3~B4~B1~B2, that is, the terminal battery B3 of the second charge and discharge is taken as the first-end battery, the first-end battery B4 of the second charge and discharge is connected after the first-end battery B3 of the third charge and discharge to become the middle battery, and the middle battery B2 connected before the terminal battery in the second charge and discharge is the terminal battery in the third charge and discharge; (4) During the fourth charge and discharge, according to the same rotation rule, the connection sequence of the fourth row vector of the 4th-order cyclic matrix is ​​taken as: B2~B3~B4~B1; (5) During the fifth charge and discharge, the first row vector of the 4th-order cyclic matrix is ​​returned as the connection sequence; the subsequent charge and discharge cycles take the row vectors of the 4th-order cyclic matrix as the battery connection sequence.

2. The battery pack charge and discharge control system according to claim 1, characterized in that: The conversion switch is a MOS tube.

3. The battery pack charge and discharge control system according to claim 1, characterized in that: The conversion switch is a relay.

4. A battery pack charge and discharge control method, characterized in that: The steps include: S1, constructing a battery charge and discharge sequence rotation topology circuit, wherein the connection sequence of batteries in the battery charge and discharge sequence rotation topology circuit can be dynamically rotated; the battery charge and discharge sequence rotation topology circuit comprises a battery pack connected by N batteries, and a conversion switch connected to the battery pack; the battery charge and discharge sequence rotation topology circuit rotates the charge and discharge connection sequence of the N batteries according to the on and off of the conversion switch; S2, constructing a battery charge and discharge sequence rotation strategy and building it into a control unit, wherein the control unit can control the connection sequence of the batteries during charge and discharge according to the battery charge and discharge sequence rotation strategy; the connection mode of the N batteries is that all the batteries are connected end to end to form a ring, and each battery can be rotated to become a first-end battery or a last-end battery under the control of the battery charge and discharge sequence rotation strategy, and the batteries other than the first-end battery and the last-end battery are intermediate batteries. Each time the charge and discharge is started, the connection sequence of the batteries is rotated first, so that each battery becomes the first-end battery or the last-end battery evenly, and the life consistency of the N batteries in the battery pack is maintained as a whole; S3, when the battery pack is connected for charging and discharging, the control unit first extracts the battery connection sequence of the last charging and discharging, and then determines the battery connection sequence of the current charging and discharging in combination with the battery charging and discharging sequence rotation strategy, and controls the battery pack to be connected for charging and discharging according to the battery connection sequence of the current charging and discharging.

5. The battery pack charge and discharge control method according to claim 4, characterized in that: The battery charge and discharge sequence rotation topology circuit comprises: The positive and negative electrodes of N batteries are connected end to end, and the negative electrode of the last battery is connected to the positive electrode of the first battery to form a series ring structure; Every two connected batteries are connected across a bipolar switch, wherein the input end of the bipolar switch is connected to the negative pole between the connected batteries, one of the output ends can be connected to the positive pole between the connected batteries, and the other output end can be connected to the total negative pole of the battery group; The positive terminal of each battery can be connected to the total positive terminal of the battery pack through a single-pole switch.

6. The battery pack charge and discharge control method according to claim 5, characterized in that: The battery charging and discharging sequence rotation strategy is: Each time the battery pack is connected for charging and discharging, firstly, according to the preset battery series ranking rule, a battery in the series ring structure is determined to be arranged at the first position, and the batteries connected thereafter are arranged at the second to nth positions; Connect the single-pole switch connected to the positive pole of the first battery to the total positive pole of the battery pack. Connect the output end of the bipolar switch connected to the negative pole of the nth battery to the total negative pole of the battery pack. The output end of the bipolar conversion switch connected to the negative pole of the battery from the 2nd to the n-1th position is connected to the positive pole of the connected battery to form the battery connection sequence for the current charge and discharge.

7. The battery pack charge and discharge control method according to claim 6, characterized in that: The preset battery series ranking rule is: A battery in the serial ring structure is numbered B1, and the batteries connected thereto are numbered B2, ..., Bn-1, and Bn in sequence; Create an N-order circulant matrix Order with B1, B2, ..., Bn-1, Bn as elements: If the battery pack is connected for charging and discharging for the first time, the order of elements of the first row vector [B1, B2, ..., Bn-1, Bn] of the N-order cyclic array Order is selected as the first charging and discharging connection order; For subsequent connection charging and discharging, the elements of the 2nd to nth row vectors are selected in sequence as the connection sequence of the 2nd to nth charging and discharging; After the nth row vector is selected as the connection sequence for charging and discharging, the process returns to the first row vector and starts selecting in sequence in a loop.

Images