A battery pack voltage automatic balancing system

Abstract

The present invention allows different batches of battery packs to be mixed and used through the power replenishment function between household energy storage battery packs, without being affected by the difference in power, thereby avoiding a reduction in the use time of household energy storage batteries; the battery is replenished by the charger, and at the end of charging and discharging, and during the charging balance period, when certain conditions are met, such as excessive pressure difference or abnormal voltage, the balancing strategy will be activated, and the charger will adjust the current to achieve battery power balance. The balancing will automatically stop when the stop conditions are met, such as when the voltage returns to normal or the pressure difference is reduced to a certain range. In addition, if the total voltage of the household energy storage battery pack is too high, the voltage is too high, the balancing time is too long, or the charging and discharging relays or chargers fail, the balancing will also stop to ensure the safety and stability of the battery system; at the same time, the analysis and correction module is set to analyze and correct the faults encountered during the balancing process.

Description

Technical Field

[0001] The present invention relates to the field of household battery energy storage; in particular, to an automatic voltage balancing system between battery packs Background Art

[0002] Home energy storage refers to a technology that stores energy for home use. With the increasing attention and demand for renewable energy, home energy storage systems have become a popular choice. During the use of batteries, home energy storage stores electrical energy so that it can be supplied to the home when needed. Such a system usually includes an energy storage device, an inverter, and an energy management controller. Energy storage devices generally use battery technology, such as lithium-ion batteries or lead-acid batteries. Due to the different production batches, different usage times, different charging times, and different power consumption when different power units in the home use batteries, the capacity consistency between the battery packs is often different, resulting in the need for voltage and capacity balancing between the battery packs. At present, the means of voltage balancing between the battery packs of the home energy storage system is often to discharge the battery pack with a larger capacity, which results in energy waste, and it is impossible to determine whether the voltage difference is due to the failure of the battery pack itself or the failure of the measuring device. Summary of the invention

[0003] 1. Technical issues to be resolved

[0004] In order to solve the above technical problems, the present invention provides a battery pack voltage automatic balancing system

[0005] (II) Technical solution

[0006] A battery pack voltage automatic balancing system; including battery pack balancing in the charging stage and battery pack balancing in the discharging stage; the battery pack balancing in the charging stage includes a charging terminal voltage automatic balancing system.

[0007] Further; at the end of charging, the open circuit voltage method is used to calculate the voltage value of each battery pack; when the following conditions are met, the corresponding battery pack is controlled to start battery pack balancing; the charger starts balancing for 5 minutes, stops for 3 minutes, and then re-detects whether the battery pack balancing start condition is met;

[0008] 1: Determine that the system is at the end of charging. When the charging cell has a level 1 overvoltage fault, that is, ≥3.40V, it is considered to be at the end of charging.

[0009] 2. The highest single cell voltage Vx in the pack is less than 3.6V, the charger communication is normal, and the charge and discharge relay is turned on;

[0010] 3. When the system is determined to be in a balanced state, the voltage between each battery pack is measured and the voltage difference between each battery pack is calculated. When Umax-Umin≧1.2V, the switch K1+ of the slave control circuit of the corresponding battery pack is turned on to balance the battery pack. The balancing current is 10A.

[0011] 4: When 0.5V≤Umax-Umin<1.2V; the charger starts 5A current balancing.

[0012] Furthermore, the balancing is stopped when any of the following conditions is met.

[0013] 1: The voltage released by the charging monomer overvoltage threshold level 1 is ≤3.28V.

[0014] 2: Umax-Umin<0.5V.

[0015] 3. Battery pack balancing is turned on for 5 minutes.

[0016] Furthermore; when the battery pack system is at the end of discharge and all the following conditions are met, the corresponding battery pack is controlled to start battery pack balancing, the charger is turned on for 5 minutes, and then stopped for 3 minutes before re-detecting whether the battery pack balancing start conditions are met.

[0017] 1: The system is at the end of discharge and the discharge monomer is undervoltage level 1 fault, the voltage is ≤3.05V.

[0018] 2: The charger communication is normal and the charge and discharge relay is open.

[0019] 3. When it is determined that the system is in the end-of-discharge equilibrium state, the voltage between each battery pack is measured and the voltage difference between each battery pack is calculated. When 1.2V>Umax-Umin≥0.5V, the charger starts 5A current balancing; Umax-Umin≥1.2V, the charger starts 10A current balancing.

[0020] Furthermore, the condition for stopping balancing at the end of discharge is to stop balancing when any of the following conditions is met.

[0021] 1: Discharge monomer undervoltage threshold level 1 release voltage value ≥ 3.15V.

[0022] 2: Umax-Umin<0.5V.

[0023] Stop conditions for the inter-pack balancing strategy: If any of the following conditions is met, the corresponding battery pack will be controlled to start and stop balancing (disconnect the slave control LSD1+), and the battery pack balancing start time will be reset to zero. After a delay of 3 minutes, the battery pack balancing start conditions will be re-judged;

[0024] 1: The total cumulative pressure of the battery pack Ux = the maximum total pressure Umax

[0025] 2. The highest single cell voltage in the package Vx ≥ 3.6V.

[0026] 3. Battery pack balancing is turned on for 5 minutes.

[0027] 4: Charge and discharge relay failure.

[0028] 5. Charger communication failure.

[0029] Furthermore, the automatic balancing system also includes an analysis and correction module, which includes:

[0030] The monitoring module is used to monitor the voltage value, current value, battery temperature, and other electrical parameters of the electrical components of the battery pack at each time point during operation;

[0031] A storage module, used for storing the collected information;

[0032] Analysis and calculation module, used to calculate the real-time battery voltage, current change value, and other related parameters of electrical components;

[0033] Risk calculation module: used to calculate the risk level value, output the risk level, and prompt for early warning;

[0034] Display module, used to display real-time information and risk warning information;

[0035] The fault analysis module analyzes the fault type and prompts the fault type.

[0036] The equilibrium strategy correction module is used to correct the equilibrium strategy.

[0037] The voltage value and current value at each time point during the monitoring operation process include: monitoring the voltage value U at the nth time n , I n， The voltage value U at the n+1th time point n+1 , I n+1 , voltage real-time change value U 变 , real-time current change value I 变 , voltage / current change rate V u , V i ;

[0038] U 变 = U n+1 -U n , I 变 = I n+1 -I n ;

[0039] V u = U 变 / t, V i = I变 / t;

[0040] Perform risk grading on the real-time voltage change value U_change. The U_change risk grading is as follows: First risk level: U 变 < x1; Second risk level: x2 > U 变 > x1, Third risk level: x3 > U 变 > x2, Fourth risk level: x4 > U 变 > x3, Fifth risk level: x5 > U 变 > x4;

[0041] Perform risk grading on the voltage change rate V u . The V u risk grading is as follows: First risk level: V u < y1; Second risk level: y2 > V u > y1, Third risk level: y3 > V u > y2, Fourth risk level: y4 > V u > y3, Fifth risk level: y5 > V u > y4; where the risk levels range from one to five, with one being the lowest and five being the highest;

[0042] The monitoring transmits real-time voltage and current data to the controller. The analysis and calculation module obtains the risk level information and transmits it to the display module to prompt an early warning.

[0043] A fault analysis module for analyzing the type of fault generated.

[0044] The balancing strategy correction module includes: Before implementing balancing, record the information of the battery at that time, including the magnitudes of current, temperature, and voltage parameters. After recording the current change rate A_after, temperature change rate T_after, and voltage change rate V u after balancing, set the threshold intervals for current, temperature, and voltage.

[0045] If after balancing, the current change rate A_after, temperature change rate T_after, and voltage change rate V u after are all within the threshold intervals, no fault signal is generated; if the current change rate A_after, temperature change rate T_after, and voltage change rate V u after are all outside the threshold intervals, a fault signal is generated; if the current change rate A_after, temperature change rate T_after, and voltage change rate V u after any one or two are outside the threshold intervals, perform fault analysis on the parameter(s) outside the threshold interval.

[0046] For example, if after balancing, the current change rate and temperature change rate are within the threshold intervals, while the voltage change rate is outside the threshold interval, perform fault analysis on the voltage.

[0047] After balancing, the voltage change rate of each battery pack is V u1 、V u2 、V u3 …V un， Average voltage change rate V u all;

[0048] If the voltage change rate difference ratio (V u均 -V un ) / V u均 ) is less than M, n is an integer, and n>1, then no fault signal is triggered; if the voltage change rate difference ratio ((V u均 -V un ) / V u均 )>M, a fault signal is generated.

[0049] If a fault signal is generated, troubleshooting and analysis are performed based on the fault signal;

[0050] If the fault signal is not generated, the voltage change rate difference V u均－ V un Modify the equilibrium strategy.

[0051] The modified balancing strategy is used for the next balancing. The balancing strategy is modified in the following way: according to the voltage change rate difference V u均－ V un , execute equilibrium strategy correction.

[0052] Preset equalization time, if V u均 -V un =0, then the balancing is performed according to the predetermined balancing switch time;

[0053] If V u均 -V un >0 or V u均 -V un <0, then based on the predetermined balancing switch time, the balancing switch time is preset to be extended or shortened.

[0054] The fault analysis module also includes modules for analyzing electrical parameters of other electrical components.

[0055] The analysis and correction module is a further optimization of the balancing strategy and can run independently of the balancing module.

[0056] (III) Beneficial effects

[0057] The present invention allows different batches of battery packs to be mixed and used through the power replenishment function between household energy storage battery packs, without being affected by the difference in power, thereby avoiding a reduction in the use time of household energy storage batteries; the battery is replenished by the charger, and at the end of charging and discharging, and during the charging balance period, when certain conditions are met, such as excessive pressure difference or abnormal voltage, the balancing strategy will be activated, and the charger will adjust the current to achieve battery power balance. The balancing will automatically stop when the stop conditions are met, such as when the voltage returns to normal or the pressure difference is reduced to a certain range. In addition, if the total voltage of the household energy storage battery pack is too high, the voltage is too high, the balancing time is too long, or the charging and discharging relays or chargers fail, the balancing will also stop to ensure the safety and stability of the battery system; at the same time, the analysis and correction module is set to analyze and correct the faults encountered during the balancing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Attached Figure 1 This is the circuit diagram of the voltage automatic balancing system;

[0059] Attached Figure 2 This is a schematic diagram of the charger module;

[0060] Attached Figure 3 This is a schematic diagram of the slave control module;

[0061] Figure 4 This is a relay schematic. DETAILED DESCRIPTION

[0062] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0063] A battery pack voltage automatic balancing system; including battery pack balancing in the charging stage and battery pack balancing in the discharging stage; the battery pack balancing in the charging stage includes a charging terminal voltage automatic balancing system.

[0064] Further; at the end of charging, the open circuit voltage method is used to calculate the voltage value of each battery pack; when the following conditions are met, the corresponding battery pack is controlled to start battery pack balancing; the charger starts balancing for 5 minutes, stops for 3 minutes, and then re-detects whether the battery pack balancing start condition is met;

[0065] 1: Determine that the system is at the end of charging. When the charging cell has a level 1 overvoltage fault, that is, ≥3.40V, it is considered to be at the end of charging.

[0066] 2. The highest single cell voltage Vx in the pack is less than 3.6V, the charger communication is normal, and the charge and discharge relay is turned on;

[0067] 3. When the system is determined to be in a balanced state, the voltage between each battery pack is measured and the voltage difference between each battery pack is calculated. When Umax-Umin≥1.2V, the switch K1+ of the slave control circuit of the corresponding battery pack is turned on to balance the battery pack. The balancing current is 10A.

[0068] 4: When 0.5V≤Umax-Umin<1.2V; the charger starts 5A current balancing.

[0069] Furthermore, the balancing is stopped when any of the following conditions is met.

[0070] 1: Charging monomer overvoltage threshold level 1 release ≤ 3.28V.

[0071] 2: Umax-Umin<0.5V.

[0072] 3. Battery pack balancing is turned on for 5 minutes.

[0073] Furthermore; when the battery pack system is at the end of discharge and all the following conditions are met, the corresponding battery pack is controlled to start battery pack balancing, the charger is turned on for 5 minutes, and then stopped for 3 minutes before re-detecting whether the battery pack balancing start conditions are met.

[0074] 1: The system is at the end of discharge and the discharge monomer is undervoltage level 1 fault, the voltage is ≤3.05V.

[0075] 2: The charger communication is normal and the charge and discharge relay is open.

[0076] 3. When it is determined that the system is in the end-of-discharge equilibrium state, the voltage between each battery pack is measured and the voltage difference between each battery pack is calculated. When 1.2V>Umax-Umin≥0.5V, the charger starts 5A current balancing; Umax-Umin≥1.2V, the charger starts 10A current balancing.

[0077] Furthermore, the condition for stopping balancing at the end of discharge is to stop balancing when any of the following conditions is met.

[0078] 1: Discharge monomer undervoltage threshold level 1 release voltage value ≥ 3.15V.

[0079] 2. Umax-Umin<0.5V (voltage difference between packages).

[0080] Stop conditions for the inter-pack balancing strategy: If any of the following conditions is met, the corresponding battery pack will be controlled to start and stop balancing (disconnect the slave control LSD1+), and the battery pack balancing start time will be reset to zero. After a delay of 3 minutes, the battery pack balancing start conditions will be re-judged;

[0081] 1: The total cumulative pressure of the battery pack Ux = the maximum total pressure Umax

[0082] 2. The highest single cell voltage in the package Vx ≥ 3.6V.

[0083] 3. Battery pack balancing is turned on for 5 minutes.

[0084] 4: Charge and discharge relay failure.

[0085] 5. Charger communication failure.

Claims

1. An automatic voltage balancing system between battery packs; including battery pack balancing in the charging stage and battery pack balancing in the discharging stage; the battery pack balancing in the charging stage includes an automatic voltage balancing system at the charging end; the battery pack balancing in the discharging stage includes an automatic voltage balancing system at the discharging end; the voltage value of each battery pack is calculated by the open circuit voltage method at the charging end; When the following conditions are met, the corresponding battery pack is controlled to start battery pack balancing; the charger starts balancing for 5 minutes, stops for 3 minutes, and then re-checks whether the battery pack balancing start conditions are met; 1: Determine that the system is at the end of charging. When the charging cell has a level 1 overvoltage fault, i.e. ≥3.40V, it is identified as the end of charging.

2. The highest single cell voltage Vx in the pack is less than 3.6V, the charger communication is normal, and the charge and discharge relay is turned on; 3. When the system is determined to be in a balanced state, the voltage between each battery pack is measured and the voltage difference between each battery pack is calculated. When Umax-Umin≥1.2V, the switch of the slave control circuit of the corresponding battery pack is turned on to balance the battery pack. The balancing current is 10A. 4: When 0.5V≤Umax-Umin<1.2V; the charger turns on 5A current balancing; The charging end stops balancing when any of the following conditions is met: 1: The voltage released by the charging monomer overvoltage threshold level 1 is ≤3.28V; 2. Umax-Umin<0.5V; 3. Battery pack balancing is turned on for 5 minutes; The automatic balancing system also includes an analysis and correction module, including: The monitoring module is used to monitor the voltage value, current value, battery temperature, and other electrical parameters of the electrical components of the battery pack at each time point during operation; A storage module, used for storing the collected information; Analysis and calculation module, used to calculate the real-time battery voltage, current change value, and other related parameters of electrical components; Risk calculation module: used to calculate the risk level value, output the risk level, and prompt for early warning; Display module, used to display real-time information and risk warning information; Fault analysis module, analyzes fault type and prompts fault type; Balance strategy correction module, used to correct the balance strategy; The voltage value and current value at each time point during the monitoring operation process include: monitoring the voltage value U at the nth time n , I n， The voltage value U at the n+1th time point n+1 , I n+1 , voltage real-time change value U 变 , real-time current change value I 变 , voltage / current change rate V u , V i ; IN 变 = U n+1 -IN n , and 变 = I n+1 - And n ; V u = U 变 / t, V i = I 变 / t, Perform risk grading on the real-time voltage change value U_change. The risk grading of U_change is as follows: First risk level: U 变 < x1; Second risk level: x2 > U 变 > x1, Third risk level: x3 > U 变 > x2, Fourth risk level: x4 > U 变 > x3, Fifth risk level: x5 > U 变 > x4; Perform risk grading on the voltage change rate V u The risk grading of V u is as follows: The first risk level: V u < y1; The second risk level: y2 > V u > y1, The third risk level: y3 > V u > y2, The fourth risk level: y4 > V u > y3, The fifth risk level: y5 > V u > y4; Among them, the risk levels from one to five increase from low to high; The fault analysis module is used to analyze the type of fault that occurs; the balancing strategy correction module includes: before implementing balancing, recording the battery information at that time, including the current, temperature, and voltage parameters; recording the current change rate A, temperature change rate T, and voltage change rate Vu after balancing, and setting the current, temperature, and voltage threshold intervals; if the current change rate A, temperature change rate T, and voltage change rate Vu after balancing are u If the current change rate is A, the temperature change rate is T, and the voltage change rate is V u If the current change rate is A, the temperature change rate is T, and the voltage change rate is V u If any one or two of them are outside the threshold range, a fault analysis is performed on the parameter outside the threshold range; if the current change rate and temperature change rate after balancing are within the threshold range, and the voltage change rate is outside the threshold range, a fault analysis is performed on the voltage; after balancing, the voltage change rate V u1 、V u2 、V u3 …V un， Average voltage change rate V u均 ; If the voltage change rate difference ratio ((V u均 -V un ) / V u均 ) is less than M, n is an integer, and n>1, then no fault signal is triggered; if the voltage change rate difference ratio ((V u均 -V un ) / V u均 )>M, a fault signal is generated; if a fault signal is generated, troubleshooting and analysis are performed based on the fault signal; if a fault signal is not generated, the voltage change rate difference V u均－ V un The balancing strategy is modified; the modified balancing strategy is used for the next balancing, and the balancing strategy is modified in the following way: according to the voltage change rate difference V u均－ V un , execute equilibrium strategy correction; preset equilibrium time, if V u均 -V un =0, then the balancing is performed according to the predetermined balancing switching time; if V u均 -V un >0 or V u均 -V un <0, then based on the predetermined balancing switch time, the balancing switch time is preset to be extended or shortened.

2. The battery pack voltage automatic balancing system according to claim 1, characterized in that: When the battery pack system is at the end of discharge and all the following conditions are met, the corresponding battery pack is controlled to start battery pack balancing. The charger starts balancing for 5 minutes, and then stops for 3 minutes before re-testing whether the battery pack balancing start conditions are met: 1: The system is at the end of discharge and the discharge monomer is undervoltage level 1 fault, the voltage is ≤3.05V; 2. The charger communication is normal and the charge and discharge relay is turned on; 3. When it is determined that the system is in the end-of-discharge equilibrium state, the voltage between each battery pack is measured and the voltage difference between each battery pack is calculated. When 1.2V>Umax-Umin≥0.5V, the charger starts 5A current balancing; Umax-Umin≥1.2V, the charger starts 10A current balancing.

3. The battery pack voltage automatic balancing system according to claim 2, characterized in that: Conditions for stopping balancing at the end of discharge: balancing stops when any of the following conditions are met: 1: Discharge monomer undervoltage threshold level 1 release voltage value ≥ 3.15V; 2: Umax-Umin<0.5V.

4. The automatic voltage balancing system between battery packs according to claim 3, characterized in that: Stop conditions for the inter-pack balancing strategy: If any of the following conditions is met, the corresponding battery pack will be controlled to start and stop balancing, the slave control LSD1+ will be disconnected, and the battery pack balancing start time will be reset to zero. After a delay of 3 minutes, the battery pack balancing start conditions will be re-judged; 1: The total cumulative pressure of the battery pack Ux = the maximum total pressure Umax; 2. The highest single cell voltage in the package Vx ≥ 3.6V; 3. Battery pack balancing is turned on for 5 minutes; 4. Charge and discharge relay failure; 5. Charger communication failure.

5. The automatic voltage balancing system between battery packs according to claim 4, characterized in that: The monitoring transmits real-time voltage and current data to the controller, and the analysis and calculation module obtains the risk level information, which is then transmitted to the display module and prompted with an early warning.

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