CN108011425B - Active equalization circuit and method for battery pack - Google Patents

Active equalization circuit and method for battery pack Download PDF

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Publication number
CN108011425B
CN108011425B CN201711425404.5A CN201711425404A CN108011425B CN 108011425 B CN108011425 B CN 108011425B CN 201711425404 A CN201711425404 A CN 201711425404A CN 108011425 B CN108011425 B CN 108011425B
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Prior art keywords
battery
battery pack
electric
circuit
battery unit
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CN108011425A (en
Inventor
张超
曹碧颖
李杨
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Shanghai Electric Group Corp
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Shanghai Electric Group Corp
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    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02JCIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0013Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries acting upon several batteries simultaneously or sequentially
    • H02J7/0014Circuits for equalisation of charge between batteries
    • H02J7/0019Circuits for equalisation of charge between batteries using switched or multiplexed charge circuits
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02JCIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0013Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries acting upon several batteries simultaneously or sequentially
    • H02J7/0014Circuits for equalisation of charge between batteries
    • H02J7/0016Circuits for equalisation of charge between batteries using shunting, discharge or bypass circuits
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02JCIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0013Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries acting upon several batteries simultaneously or sequentially
    • H02J7/0014Circuits for equalisation of charge between batteries
    • H02J7/0018Circuits for equalisation of charge between batteries using separate charge circuits
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02JCIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0013Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries acting upon several batteries simultaneously or sequentially
    • H02J7/0022Management of charging with batteries permanently connected to charge circuit
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02JCIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0013Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries acting upon several batteries simultaneously or sequentially
    • H02J7/0026Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries acting upon several batteries simultaneously or sequentially using safety or protection circuits, e.g. overcharge/discharge disconnection

Abstract

The invention provides a battery pack active equalization circuit and a battery pack active equalization method, which belong to the technical field of electrical control, and comprise an inductive equalization circuit and a stable protection circuit: the inductive equalization circuit includes: a plurality of electronic power switches connected in series with each other and connected in parallel to both ends of the battery unit, respectively; a plurality of power inductors, wherein a power inductor is respectively connected in series between each battery unit and the corresponding electronic power switch; the stabilization protection circuit includes: the capacitors are connected in series and are respectively connected in parallel at two ends of the battery unit; the voltage-stabilizing tubes are connected in series and are respectively connected in parallel at two ends of the capacitor. The invention has the beneficial effects that: the active equalization circuit of the battery pack belongs to a bidirectional DC/DC converter type circuit, and solves the problem of low overall efficiency caused by that most of electric quantity in the circuit is only transferred to adjacent electric cores; the problem of in this kind of circuit under the complicated operating mode such as electric core access time inconsistency, local voltage is too high, leads to the integrated circuit board to damage is solved.

Description

Active equalization circuit and method for battery pack
Technical Field
The invention relates to the technical field of electrical control, in particular to a battery pack active equalization circuit and a battery pack active equalization method.
Background
Large-scale energy storage is one of the important solutions for large-scale access of renewable energy sources, and is an important development direction in the next years. The energy storage battery pack is generally formed by combining hundreds of single batteries in series and parallel connection so as to achieve proper voltage level and capacity level. Due to differences in design, environment and performance of the battery, the battery pack has inconsistent electric quantity during recycling.
The development of new energy automobiles becomes a necessary direction for solving energy problems, the problem of inconsistency of electric cores of power batteries in the actual application process can be gradually shown, and if the inconsistency is not treated, the trend of further deterioration can be realized.
The effect of cell inconsistency on power battery packs can cause a number of problems, such as:
1) the capacity and the energy utilization rate are reduced, the charging capacity of the battery pack is limited before the partial batteries which are fully charged before other batteries are charged during charging, and the discharging capacity of the battery pack is limited before the partial batteries which are fully discharged before other batteries are discharged during discharging, so that the total capacity which can be stored and discharged by the battery pack is reduced;
2) the power output capacity of the battery is limited, when batteries with different states of Charge (SOC) are connected in series to form a group, the power input or output capacity of the whole group of batteries can be limited by the batteries with the high SOC due to parameter change in the charging and discharging processes;
3) the difficulty of estimating the state of the battery pack is increased, and the difference of the capacity and the state of charge of the single battery brings great difficulty to the accurate estimation of the state of the series battery pack and the optimal use of energy. If the maximum available capacity and the SOC among the single batteries are inconsistent, the difficulty of estimating the SOC and the Energy State (SOE) of the grouped batteries is obviously increased;
4) the service life of the battery pack is shortened, and practice proves that the service life of the battery pack is often shorter than that of a single battery when the batteries are connected in series for use. One possible reason for the analysis is that the heat dissipation condition in the battery pack cannot be increased compared with the single battery in use, and the degradation speed of the battery is accelerated.
This not only affects the battery life, but also greatly shortens the battery life, and may cause unrecoverable damage such as overcharge or overdischarge of the battery. The battery pack needs to be subjected to balanced management in order to solve the problem of imbalance caused by inconsistent electric quantity of the battery pack.
The battery equalizer is an electric control device which is specially used for a series-connected single battery pack structure, is attached to a battery pack, adopts a circuit of a battery energy equalization topological structure and an equalization control algorithm to control the voltage or SOC value of each single battery, enables each single battery of the battery pack to work in a 'healthy' state, and does not change the circuit structure and the performance of an original battery pack. The balance of the batteries is to change the damage electrical parameters caused by inconsistency among the batteries by a dissipation or conversion method, so as to achieve the purposes of prolonging the endurance time and prolonging the service life of the batteries. The balancing of the batteries is an inevitable requirement for battery management.
The topological structure of the existing battery equalization controller mainly comprises: energy dissipation type, bus type, and DC/DC bidirectional conversion type.
Energy dissipation type: the principle of the energy dissipation type balanced topology circuit is that the redundant electric quantity of a battery with higher electric quantity in a battery pack is dissipated through discharging of a bypass resistor, so that the purpose of improving the electric quantity inconsistency of the battery pack is achieved. For example, the voltage of each battery unit is compared with the average voltage of the battery pack, and when the voltage of the battery unit is greater than the average voltage of the battery pack, the bypass resistor is switched on to discharge, so that the battery units are balanced;
the bus type is characterized in that the battery and the bus are connected together through the balancing sub-circuit, and the battery can transmit the surplus energy of the battery to the energy bus so as to be convenient for other battery monomers to obtain. For example, each battery unit is provided with an equalization subcircuit, the equalization subcircuit comprises an isolation type bidirectional flyback transformer and an electronic switch, two ends of a secondary coil of the isolation type bidirectional flyback transformer are respectively connected with the anode and the cathode of a single battery, and a bus is provided with energy storage equipment to store battery energy.
The DC/DC conversion type and converter type equalizing circuit takes a Buck and Boost topological structure as a basis, energy transfer is realized through an energy storage power inductor, and the inconsistency of the electric quantity of the battery pack is improved. For example, the control circuit comprises n charging control groups, a first energy bidirectional controllable electronic switch and the power inductor are connected in series with the positive and negative electrodes of one battery cell, a second energy bidirectional controllable electronic switch and the power inductor are connected in series with the positive and negative electrodes of another battery cell, the topological structures of the charging control groups are the same, and redundant electric quantity of the battery with higher electric quantity is transferred to the adjacent battery, so that bidirectional flow of energy is realized.
The research on the prior art finds that the following problems exist:
energy dissipation type: the energy dissipation type balancing topology circuit is simple and easy to implement, but consumes the residual electric quantity of the battery pack, reduces the electric quantity of the battery pack, and meanwhile, in order to avoid excessive heat generated during resistor discharging, balancing current must be limited in a small range. These problems limit the development of such equalization topology circuits, but their disadvantages of low equalization efficiency and excessive heat generation determine their limitations;
the bus type circuit structure needs to be provided with energy storage equipment, and is influenced by the volume and the service life of the energy storage equipment, so that the equalizer is inconvenient to use, the service life is influenced, and modularization is inconvenient;
the bidirectional DC/DC converter type circuit transfers redundant electric quantity of a battery with higher electric quantity to an adjacent battery by controlling the balancing module, so as to improve the inconsistency of the electric quantity of a battery pack, but most of the electric quantity transfer of the current control method of the circuit is an adjacent electric core, less part of the electric quantity transfer of the circuit can be transferred to a next adjacent electric core, and the electric quantity transferred to a farther electric core is almost zero, so that the overall balancing speed is slower and the efficiency is not high; meanwhile, under complex working conditions that the access time of the battery core is inconsistent and the like, the local voltage is too high in the circuit, so that the board card is damaged.
Disclosure of Invention
Aiming at the problems in the prior art, the invention relates to a battery pack active equalization circuit and a battery pack active equalization method.
The invention adopts the following technical scheme:
a battery pack active equalization circuit is characterized in that a battery pack is composed of a plurality of battery units, each battery unit is formed by connecting one or more single batteries in series, and the attributes of each battery unit are consistent; the active equalization circuit of the battery pack comprises a power inductive equalization circuit and a stable protection circuit:
the power inductive equalization circuit comprises:
a plurality of electronic power switches connected in series with each other and connected in parallel at both ends of the battery cell, respectively;
a plurality of power inductors, wherein a power inductor is respectively connected in series between each battery unit and the corresponding electronic power switch;
the stabilization protection circuit includes:
the capacitors are connected in series and are respectively connected in parallel at two ends of the battery unit;
and the voltage-stabilizing tubes are mutually connected in series and are respectively connected in parallel at two ends of the capacitor.
Preferably, one end of the power inductor is connected to the positive electrode of the corresponding battery unit, and the other end of the power inductor is connected to the corresponding electronic power switch.
Preferably, the electronic power switch is a MOSFET or an IGBT.
Preferably, when the electronic power switch is the MOSFET, the drain of the MOSFET is connected to the anode of the corresponding battery cell through the corresponding power inductor, the source of the MOSFET is connected to the cathode of the corresponding battery cell, and the gate of the MOSFET is used for receiving a switch control signal;
the switch control signal is used to control the electronic power switch to be turned on and off.
Preferably, the positive electrode of the voltage-stabilizing tube is connected with the negative electrode of the corresponding battery unit, and the negative electrode of the voltage-stabilizing tube is connected with the positive electrode of the corresponding battery unit.
A battery pack active equalization method adopts the battery pack active equalization circuit, and comprises the following steps:
step S1a, selecting a battery unit as a first battery unit and turning on an electronic power switch corresponding to the first battery unit in a first time period, wherein the absolute value of the real-time electric quantity of the first battery unit in the battery pack is the largest, and the real-time electric quantity of the first battery unit is judged to have a preset deviation value compared with the average electric quantity of the battery pack, and the step S2a is turned to when the real-time electric quantity is larger than the average electric quantity;
step S2a, when the real-time electric quantity of an adjacent battery cell of the first battery cell is consistent with the real-time electric quantity of the first battery cell, forming an equalizing battery pack with the adjacent battery cell and the first battery cell having the same real-time electric quantity, and forming a second time period according to the number of the battery cells included in the equalizing battery pack, and simultaneously turning on the electronic power switches corresponding to the battery cells in the equalizing battery pack at the second time period;
step S3a, when the real-time electric quantity of the battery unit is consistent with that of the first battery unit, the step S4a is turned to;
step S4a, forming a plurality of balancing battery packs respectively, each balancing battery pack including the battery cells that are adjacent to each other and have consistent real-time electric quantities, forming a corresponding second time period for each balancing battery pack, and turning on the electronic power switches corresponding to all the battery cells in the balancing battery pack at the same time in the second time period;
step S5a, determining whether the real-time electric quantity of the first battery unit is lower than the average electric quantity:
if yes, all the electronic power switches are closed, and then the electronic power switches are withdrawn;
if not, the process returns to the step S3 a.
Preferably, in the step S1a, the first time period is T1.
Preferably, in step S2a, the second time period is calculated by using the following formula:
T2=T1/n1;
wherein the content of the first and second substances,
t2 is used to represent the second time period;
t1 is used to represent the first time period;
n1 is used to indicate the number of cells in the balancing battery pack.
A battery pack active equalization method adopts the battery pack active equalization circuit, and comprises the following steps:
step S1b, selecting a battery cell as a second battery cell, turning on the electronic power switch corresponding to the battery cell adjacent to the second battery cell in a third time period, determining the real-time electric quantity of the second battery cell when the absolute value of the real-time electric quantity of the second battery cell in the battery pack is minimum and has a preset deviation value compared with the average electric quantity of the battery pack, and turning to step S2b when the real-time electric quantity is smaller than the average electric quantity;
step S2b, when the real-time electric quantity of the battery unit is consistent with the second battery unit, the battery unit with the consistent real-time electric quantity is taken as a battery unit to be judged;
step S3b, determining whether the electronic power switch corresponding to the battery cell adjacent to the battery cell to be determined is already turned on:
if yes, go directly to step S4 b;
if not, turning on the electronic power switch corresponding to the battery unit adjacent to the battery unit to be determined in the third time period, and then turning to step S4 b;
step S4b, determining whether the real-time electric quantity of the second battery unit is higher than the average electric quantity:
if yes, all the electronic power switches are closed, and then the electronic power switches are withdrawn;
if not, the process returns to the step S3 b.
Preferably, in the step S1b, the third time period is T1.
The invention has the beneficial effects that: the invention discloses a battery pack active equalization circuit, which belongs to a bidirectional DC/DC converter type circuit and mainly solves the following two problems:
the problem of low overall efficiency caused by that most of electric quantity in the circuit is only transferred to an adjacent electric core is solved;
the problem of in this kind of circuit under the complicated operating mode such as electric core access time inconsistency, local voltage is too high, leads to the integrated circuit board to damage is solved.
Drawings
FIG. 1 is a schematic diagram of a power inductive equalization circuit of a battery pack active equalization circuit according to a preferred embodiment of the present invention;
fig. 2 is a schematic diagram of a stable protection circuit of an active equalization circuit of a battery pack according to a preferred embodiment of the present invention;
fig. 3 is a flowchart of an active equalization method for a battery pack according to a preferred embodiment of the present invention;
fig. 4 is a second flowchart of the active equalization method for battery pack in a preferred embodiment of the present invention.
Detailed Description
In the following embodiments, the technical features may be combined with each other without conflict.
The following further describes embodiments of the present invention with reference to the drawings:
as shown in fig. 1-2, an active equalization circuit for a battery pack, the battery pack is composed of a plurality of battery units, each battery unit is formed by connecting one or more single batteries in series, and the attributes of each battery unit are consistent; the active equalization circuit of the battery pack comprises a power inductive equalization circuit and a stable protection circuit:
the power inductive equalization circuit comprises:
a plurality of electronic power switches connected in series with each other and connected in parallel to both ends of the battery unit, respectively;
a plurality of power inductors, wherein a power inductor is respectively connected in series between each battery unit and the corresponding electronic power switch;
the stabilization protection circuit includes:
the capacitors are connected in series and are respectively connected in parallel at two ends of the battery unit;
and the voltage stabilizing tubes are connected in series and are respectively connected in parallel at two ends of the capacitor.
Furthermore, one end of the power inductor is connected with the positive electrode of the corresponding battery unit, and the other end of the power inductor is connected with the corresponding electronic power switch.
Further, the electronic power switch is a MOSFET or an IGBT.
Further, when the electronic power switch is an MOSFET, the drain electrode of the MOSFET is connected to the positive electrode of the corresponding battery cell through the corresponding power inductor, the source electrode of the MOSFET is connected to the negative electrode of the corresponding battery cell, and the gate electrode of the MOSFET is used for receiving a switch control signal;
the switch control signal is used to control the electronic power switch to be turned on and off.
Furthermore, the positive pole of the voltage-stabilizing tube is connected with the negative pole of the corresponding battery unit, and the negative pole of the voltage-stabilizing tube is connected with the positive pole of the corresponding battery unit.
In this embodiment, the battery pack active equalization circuit is a high-efficiency and stable power inductance type lithium battery active equalization circuit and a control method thereof, a main loop of the circuit is a mature power inductance type equalization circuit (as shown in fig. 1), but on the basis of the circuit, a stable protection circuit (as shown in fig. 2) which is used in cooperation with the circuit is developed, and the circuit can ensure stable sampling and stable circuit voltage under complex working conditions; meanwhile, in the aspect of circuit control, the patent provides a novel switch gating strategy, and the efficiency of the power inductance type active equalizer is improved.
In fig. 1, bat1-bat24 is a battery cell (i.e. a single battery); L1-L23 are power inductors; K1-K24 are power electronic switches, which may be MOSFETs or IGBTs.
In fig. 2, bat1-bat24 corresponds to the battery cells in fig. 1 one-to-one; C1-C24 are capacitors; D1-D24 is a voltage regulator tube.
The active equalization circuit of the battery pack belongs to a bidirectional DC/DC converter type circuit, and mainly solves the following two problems:
the problem of low overall efficiency caused by that most of electric quantity in the circuit is only transferred to an adjacent electric core is solved;
the problem of in this kind of circuit under the complicated operating mode such as electric core access time inconsistency, local voltage is too high, leads to the integrated circuit board to damage is solved.
As shown in fig. 1-3, in a preferred embodiment of the present invention, a battery active equalization method is adopted, where the battery active equalization circuit is adopted, and the battery active equalization method includes:
step S1a, selecting a battery unit as a first battery unit and switching on an electronic power switch corresponding to the first battery unit in a first time period, wherein the absolute value of the real-time electric quantity of the first battery unit in the battery pack is the largest, and the real-time electric quantity of the first battery unit is judged to have a preset deviation value compared with the average electric quantity of the battery pack, and the step S2a is switched to when the real-time electric quantity is larger than the average electric quantity;
step S2a, when the real-time electric quantity of an adjacent battery unit of the first battery unit is consistent with the real-time electric quantity of the first battery unit, forming a balanced battery pack by the adjacent battery unit and the first battery unit with the same real-time electric quantity, forming a second time period according to the number of the battery units in the balanced battery pack, and simultaneously switching on the electronic power switches corresponding to the battery units in the balanced battery pack by the second time period;
step S3a, when the battery unit is consistent with the real-time electric quantity of the first battery unit, the step S4a is turned to;
step S4a, a plurality of equalizing battery packs are respectively formed, each equalizing battery pack respectively comprises battery units which are adjacent to each other and have consistent real-time electric quantity, a corresponding second time period is formed for each equalizing battery pack, and electronic power switches corresponding to all the battery units in the equalizing battery packs are simultaneously turned on according to the second time period;
step S5a, determining whether the real-time electric quantity of the first battery unit is lower than the average electric quantity:
if yes, all the electronic power switches are closed, and then the operation is quitted;
if not, the process returns to step S3 a.
Further, in step S1a, the first time period is T1.
Further, in step S2a, the second time period is calculated by using the following formula:
T2=T1/n1;
wherein the content of the first and second substances,
t2 is used to indicate a second time period;
t1 is used to indicate a first time period;
n1 is used to indicate the number of cells in the balancing battery pack.
In this embodiment, the stable protection circuit may be in different operating environments when the power inductive equalizer actually operates. If can produce various vibrations on electric automobile, the operating mode that has the hot plug in fixed energy storage, when the interface contact failure who causes equalizer and battery because factors such as vibration or hot plug, the operating condition to this moment of equalizer in fig. 1 carries out the analysis, as follows:
let bat2 electrical core not be switched into circuit for 1ms first. In this 1ms, when the switching tube K on any other electric core is in the on state, energy is accumulated in the power inductor, and then the switching tube is completely turned off, so that the power inductor needs the electric core bat2 to form a loop with the power inductor, and the current in the power inductor is released. At this time, if the battery cell bat2 is disconnected, an instantaneous extremely high voltage is generated at the disconnected position (i.e., across the battery cell bat 2). The voltage can generally break down a sampling channel on the equalizer to release energy, even generate electric sparks, and generate potential safety hazards.
After the stable protection circuit designed in fig. 2 is connected, the working state of the equalizer is analyzed as follows:
also assume bat2 cells are not connected to the circuit for 1 ms. Within the 1ms, the current generated by the power inductor on any other electric core can firstly follow the current through the capacitor C2; when the non-access time of the battery core is too long, the voltage of the voltage regulator tube D2 on the C2 exceeds a certain threshold value, the current path on the power inductor is always ensured, the voltage of the bat2 access point is stabilized in a normal state, the stability of the circuit is ensured, and the problem of poor contact of the battery core possibly caused by vibration, hot plug and the like is solved.
Novel switch gating strategy
For the topology in fig. 1, when the electric quantity of a certain cell is higher than the average electric quantity of other cells by a certain threshold, the corresponding switch tube is started to start equalization. For example, in the prior art, the battery cell bat12 is illustrated, the battery cell bat12 electric quantity is higher than the average battery cell electric quantity by a certain threshold value, the switch K12 is turned on, and the battery cell bat12 electric quantity is stored in the inductor L12 in a current form. When the inductor current increases to a certain threshold value, the switch K12 is turned off, and the electric energy stored in the inductor is transferred to other cells except the cell bat 12. In the process, about 60% of the charge is transferred to the adjacent cells, i.e. bat13 and bat 11; about 30% of the energy is transferred in bat10 and bat14, and the remaining very small fraction of the charge is stored in the remaining cells in a sequentially decreasing manner.
Now, in order to improve the electric energy transfer efficiency of the cell, when the electric quantity is unbalanced (for example, the electric quantity of the cell 12 is also used), the following switching strategy is proposed:
if the electrical quantity of the battery cell 12 is higher than the average battery cell electrical quantity by a certain threshold value:
the switch K12 of the cell with the highest electric quantity is turned on first, and the switching period is T (i.e., the first time period T1).
When the electric quantity of the highest battery cell bat12 is more consistent with the electric quantity of the adjacent battery cell bat11 or bat13 and exceeds the average threshold value, the switches K12 and K11 or K13 are simultaneously turned on, and the switching period is T/2. Now, the example is performed in accordance with K12 with the electric quantity of K11, at this time, battery cell bat12 and battery cell bat11 simultaneously transfer the electric quantities above bat11 and bat12 through L10 and L12, K11 and K12; meanwhile, the switching period is changed into T/2, so that the circuit can be ensured to work on the same stable balanced current.
When the third cell electric quantity is consistent with bat11 and bat12 and is higher than the average value by a certain threshold value: if the battery cell is an adjacent battery cell, namely bat10 or bat14, the three switches are simultaneously turned on, and T/3 is taken periodically; if the cells are not adjacent cells, such as bat5, K5 is simultaneously turned on, the switching period T is turned on, K11 and K12 are turned on, and the switching period T/2 is also turned on.
Continuously judging the electric quantity of the battery cores, and accumulating according to the theory, namely when the electric quantity of the adjacent battery cores is the same and exceeds a threshold value, simultaneously turning on corresponding switches of the battery cores, wherein the period is T divided by the number of the switches; and when the electric quantity of the nonadjacent battery cells is the same and exceeds the threshold value, the corresponding switches of the battery cells are simultaneously switched on, but the switching period of each group is respectively calculated, and a plurality of battery cells in each group are adjacent, and the number is divided by T to be taken as the corresponding switching period.
And when the highest electric quantity of the electric core is not higher than the average electric quantity threshold value of the electric core, balancing the high electric quantity, and closing all the switches K.
As shown in fig. 1-2 and 4, in a preferred embodiment of the present invention, a battery active equalization method is adopted, where the battery active equalization circuit is adopted, and the battery active equalization method includes:
step S1b, selecting a battery unit as a second battery unit and turning on an electronic power switch corresponding to the battery unit adjacent to the second battery unit in a third time period, wherein the absolute value of the real-time electric quantity of the second battery unit in the battery pack is minimum, and has a preset deviation value compared with the average electric quantity of the battery pack, judging the real-time electric quantity of the second battery unit, and turning to step S2b when the real-time electric quantity is smaller than the average electric quantity;
step S2b, when the real-time electric quantity of the battery unit is consistent with the second battery unit, the battery unit with the consistent real-time electric quantity is taken as a battery unit to be judged;
step S3b, determining whether the electronic power switch corresponding to the adjacent battery cell of the battery cells to be determined is already turned on:
if yes, go directly to step S4 b;
if not, turning on the electronic power switch corresponding to the adjacent battery unit of the battery unit to be determined in a third time period, and then turning to step S4 b;
step S4b, determining whether the real-time power of the second battery cell is higher than the average power:
if yes, all the electronic power switches are closed, and then the operation is quitted;
if not, the process returns to step S3 b.
Further, in step S1b, the third time period is T1.
In this embodiment, the stable protection circuit may be in different operating environments when the power inductive equalizer actually operates. If can produce various vibrations on electric automobile, the operating mode that has the hot plug in fixed energy storage, when the interface contact failure who causes equalizer and battery because factors such as vibration or hot plug, the operating condition to this moment of equalizer in fig. 1 carries out the analysis, as follows:
let bat2 electrical core not be switched into circuit for 1ms first. In this 1ms, when the switching tube K on any other electric core is in the on state, energy is accumulated in the power inductor, and then the switching tube is completely turned off, so that the power inductor needs the electric core bat2 to form a loop with the power inductor, and the current in the power inductor is released. At this time, if the battery cell bat2 is disconnected, an instantaneous extremely high voltage is generated at the disconnected position (i.e., across the battery cell bat 2). The voltage can generally break down a sampling channel on the equalizer to release energy, even generate electric sparks, and generate potential safety hazards.
After the stable protection circuit designed in fig. 2 is connected, the working state of the equalizer is analyzed as follows:
also assume bat2 cells are not connected to the circuit for 1 ms. Within the 1ms, the current generated by the power inductor on any other electric core can firstly follow the current through the capacitor C2; when the non-access time of the battery core is too long, the voltage of the voltage regulator tube D2 on the C2 exceeds a certain threshold value, the current path on the power inductor is always ensured, the voltage of the bat2 access point is stabilized in a normal state, the stability of the circuit is ensured, and the problem of poor contact of the battery core possibly caused by vibration, hot plug and the like is solved.
Novel switch gating strategy
For the topology in fig. 1, when the electric quantity of a certain cell is higher than the average electric quantity of other cells by a certain threshold, the corresponding switch tube is started to start equalization. For example, in the prior art, the battery cell bat12 is illustrated, the battery cell bat12 electric quantity is higher than the average battery cell electric quantity by a certain threshold value, the switch K12 is turned on, and the battery cell bat12 electric quantity is stored in the inductor L12 in a current form. When the inductor current increases to a certain threshold value, the switch K12 is turned off, and the electric energy stored in the inductor is transferred to other cells except the cell bat 12. In the process, about 60% of the charge is transferred to the adjacent cells, i.e. bat13 and bat 11; about 30% of the energy is transferred in bat10 and bat14, and the remaining very small fraction of the charge is stored in the remaining cells in a sequentially decreasing manner.
Now, in order to improve the electric energy transfer efficiency of the cell, when the electric quantity is unbalanced (for example, the electric quantity of the cell 12 is also used), the following switching strategy is proposed: if the electric quantity of the battery cell 12 is lower than a certain threshold of the average electric quantity: first, the adjacent switches K11 and K13 of the battery cell with the highest electric quantity are switched on, and the switching period is T.
When the electric quantity of the lowest battery cell bat12 is more consistent with the electric quantity of the adjacent battery cell bat11 or bat13 and is lower than the average threshold value, two switches on the lowest edge of the battery cell with low electric quantity are simultaneously switched on, and the switching period is T. Now, the analysis was performed with bat11 electric quantity consistent with bat12, at which time K10 and K13 were turned on; with a switching period of T.
And continuously judging the electric quantity of the battery cell, and according to the theoretical accumulation, when the battery cell bat1 or bat24 is the lowest, not opening K1 or K24, but only opening the other side.
And when the lowest electric quantity of the electric core is not lower than the average electric quantity threshold value of the electric core, balancing the low electric quantity, and closing all the switches K.
While the specification concludes with claims defining exemplary embodiments of particular structures for practicing the invention, it is believed that other modifications will be made in the spirit of the invention. While the above invention sets forth presently preferred embodiments, these are not intended as limitations.
Various alterations and modifications will no doubt become apparent to those skilled in the art after having read the above description. Therefore, the appended claims should be construed to cover all such variations and modifications as fall within the true spirit and scope of the invention. Any and all equivalent ranges and contents within the scope of the claims should be considered to be within the intent and scope of the present invention.

Claims (7)

1. A battery pack active equalization method is characterized in that a battery pack active equalization circuit is adopted, the battery pack is composed of a plurality of battery units, each battery unit is formed by connecting one or a plurality of single batteries in series, and the attributes of each battery unit are consistent;
the battery pack active equalization circuit comprises a power inductance type equalization circuit and a stable protection circuit;
the power inductive equalization circuit comprises:
a plurality of electronic power switches connected in series with each other and connected in parallel to both ends of the battery cell, respectively;
the stabilization protection circuit includes:
the capacitors are connected in series and are respectively connected in parallel at two ends of the battery unit;
the voltage-stabilizing tubes are connected in series and are respectively connected in parallel at two ends of the capacitor;
the active equalization method of the battery pack comprises the following steps:
step S1a, selecting a battery unit as a first battery unit and turning on an electronic power switch corresponding to the first battery unit in a first time period, wherein the absolute value of the real-time electric quantity of the first battery unit in the battery pack is the largest, and the real-time electric quantity of the first battery unit is judged to have a preset deviation value compared with the average electric quantity of the battery pack, and the step S2a is turned to when the real-time electric quantity is larger than the average electric quantity;
step S2a, when the real-time electric quantity of an adjacent battery cell of the first battery cell is consistent with the real-time electric quantity of the first battery cell, forming an equalizing battery pack with the adjacent battery cell and the first battery cell having the same real-time electric quantity, and forming a second time period according to the number of the battery cells included in the equalizing battery pack, and simultaneously turning on the electronic power switches corresponding to the battery cells in the equalizing battery pack at the second time period;
step S3a, when the real-time electric quantity of the battery unit is consistent with that of the first battery unit, the step S4a is turned to;
step S4a, forming a plurality of balancing battery packs respectively, each balancing battery pack including the battery cells that are adjacent to each other and have consistent real-time electric quantities, forming a corresponding second time period for each balancing battery pack, and turning on the electronic power switches corresponding to all the battery cells in the balancing battery pack at the same time in the second time period;
step S5a, determining whether the real-time electric quantity of the first battery unit is lower than the average electric quantity:
if yes, all the electronic power switches are closed, and then the electronic power switches are withdrawn;
if not, the process returns to the step S3 a.
2. The active battery pack balancing method of claim 1, wherein in step S1a, the first time period is T1.
3. The active equalization method for battery pack according to claim 2, wherein in step S2a, the second time period is calculated by using the following formula:
T2=T1/n1;
wherein the content of the first and second substances,
t2 is used to represent the second time period;
t1 is used to represent the first time period;
n1 is used to indicate the number of cells in the balancing battery pack.
4. The active battery pack balancing method according to claim 1, wherein one end of the power inductor is connected to the positive electrode of the corresponding battery cell, and the other end of the power inductor is connected to the corresponding electronic power switch.
5. The battery pack active balancing method according to claim 1, characterized in that the electronic power switches are MOSFETs or IGBTs.
6. The active equalization method for battery pack according to claim 5, wherein when the electronic power switch is the MOSFET, the drain of the MOSFET is connected to the positive electrode of the corresponding battery cell through the corresponding power inductor, the source of the MOSFET is connected to the negative electrode of the corresponding battery cell, and the gate of the MOSFET is used for receiving a switch control signal;
the switch control signal is used to control the electronic power switch to be turned on and off.
7. The active equalization method for the battery pack according to claim 1, characterized in that the positive electrode of the voltage-stabilizing tube is connected with the negative electrode of the corresponding battery unit, and the negative electrode of the voltage-stabilizing tube is connected with the positive electrode of the corresponding battery unit.
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CN110231577A (en) * 2019-06-14 2019-09-13 安徽锐能科技有限公司 A kind of SOE estimation device for mending electric-type active equalization based on battery
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