CN211731117U

CN211731117U - Balanced circuit for layered equalization of basic chopper circuit

Info

Publication number: CN211731117U
Application number: CN201922140823.5U
Authority: CN
Inventors: 刘红锐; 张开翔; 郭奕旋; 尹荣; 李博
Original assignee: Kunming University of Science and Technology
Current assignee: Kunming University of Science and Technology
Priority date: 2019-12-03
Filing date: 2019-12-03
Publication date: 2020-10-23
Anticipated expiration: 2029-12-03

Abstract

The utility model relates to a balanced equalizer circuit of basic chopper circuit's layering, every 2 on equalizer circuit ith layerⁱA single battery, two Mosfet switches with anti-parallel diodes and an energy storage inductor form an equalizing unit of the ith equalizing circuit, one end of the energy storage inductor and the 2 nd equalizing circuit^i‑1Negative electrode of single battery, No. 2^i‑1The positive electrodes of +1 single batteries are connected, the source electrode of the first Mosfet switch with the anti-parallel diode and the drain electrode of the other Mosfet switch with the anti-parallel diode at the other end of the energy storage inductor are connected, and the drain electrode of the first Mosfet switch with the anti-parallel diode and the drain electrode of the other Mosfet switch with the anti-parallel diode are connectedThe pole of the Mosfet switch is connected with the positive pole of the first single battery, and the source of the Mosfet switch with the antiparallel diode is connected with the No. 2ⁱThe negative electrodes of the single batteries are connected; i1, 2,. m. The utility model discloses can realize quick equilibrium.

Description

Balanced circuit for layered equalization of basic chopper circuit

Technical Field

The utility model relates to a balanced equalizer circuit of basic chopper circuit's layering belongs to power electronic technology and the balanced management technical field of storage battery energy.

Background

With the continuous development of society, various heavy industries are continuously raised, so that the environmental problem is more and more serious. In particular, the continuous exploitation and use of natural resources such as petroleum and coal, etc. cause the greenhouse effect to be intensified. And the resources are all non-renewable energy sources and face the danger of exhaustion. In order to alleviate the problems of energy exhaustion and environmental pollution, countries seek clean energy and renewable energy. The advantages of cleanness, high efficiency, low carbon and environmental protection of the electric automobile are suitable for the concept of saving and protecting the environment of various countries. In the production and manufacturing process of electric vehicles, various vehicle companies, such as tesla, bmi, audi, BYD, and the like, have been actively developing electric vehicles. In the development process of electric vehicles, battery energy storage technology is undoubtedly one of the cores of the whole development of electric vehicles. With the rapid development of batteries and battery management technologies, lithium ion batteries have attracted much attention and favor of the society because of their advantages of high energy density, no pollution, relatively high nominal voltage, and the like.

Due to current technical limitations, the energy of a single lithium ion battery is not sufficient to drive the entire automobile. Therefore, in order to make the electric vehicle possess sufficient power, manufacturers of electric vehicles use a large number of single batteries in series to meet the voltage and current requirements of the electric vehicle. However, due to the production process of lithium ion batteries, different lithium ion batteries have differences in capacity, internal resistance, self-discharge rate, and the like. The influence of certain small-capacity batteries on the series lithium ion batteries in the charging and discharging processes is caused, so that other batteries cannot be deeply utilized, and the service life of the batteries is further shortened. Therefore, it is very important to perform energy balance on the single batteries inside the series battery pack.

Disclosure of Invention

The utility model provides a balanced equalizer circuit of basic chopper circuit's layering to a circuit structure that the inside battery cell of the group battery that realizes establishing ties carries out energy balance is provided for.

The technical scheme of the utility model is that: a balanced circuit of the hierarchical equilibrium of the basic chopper circuit, form m layers of balanced circuits by the battery, energy storage inductance, Mosfet switch with anti-parallel diode;

the battery pack is composed of 2^mSingle battery BT_i1Composed of a first layer 2 of a Mosfet switch with antiparallel diodes^mMosfet switch Q1 with anti-parallel diode_i1A second layer 2^m-1Mosfet switch Q2 with anti-parallel diode_i2… and mth layer 2 Mosfet switch Qm with antiparallel diodes_imThe energy storage inductor is composed of a first layer 2^m-1Energy storage inductor L1_j1A second layer 2^m-2Energy storage inductor L2_j2… and m-th layer 2⁰Energy storage inductor Lm_jmComposition is carried out; wherein i1 is 1,2,3^m ^-0；i2＝1,2,3,...,2^m-1；im＝1,2^m-(m-1)；j1＝1,2,3...,2^m-1；j2＝1,2,3...,2^m-2；jm＝2^m-m；

The ith layer of the equalization circuit is 2ⁱA single battery, two Mosfet switches with anti-parallel diodes and an energy storage inductor form an equalizing unit of the ith equalizing circuit, one end of the energy storage inductor and the 2 nd equalizing circuit^i-1Negative electrode of single battery, No. 2^i-1The positive electrodes of +1 single batteries are connected, the source electrode of a first Mosfet switch with an anti-parallel diode and the drain electrode of the other Mosfet switch with the anti-parallel diode at the other end of the energy storage inductor are connected, the drain electrode of the first Mosfet switch with the anti-parallel diode is connected with the positive electrode of the first single battery, and the source electrode of the other Mosfet switch with the anti-parallel diode is connected with the 2 nd single batteryⁱThe negative electrodes of the single batteries are connected; i1, 2,. m.

The utility model has the advantages that: the utility model discloses can realize quick equilibrium, when being used for the equilibrium process that stews, once complete equilibrium just can make all battery cell's SOC (state of charge also is called the residual capacity, it is the ratio of the residual capacity after the battery used a period of time or shelved for a long time and its complete charge state's capacity, common percentage shows) value unanimous; when the battery pack is used in a charge-discharge balancing process, when the number of the single batteries deviating from the average SOC value exceeds a threshold value, the battery pack performs one-time complete balancing, so that the number of the single batteries deviating from the average SOC value is greatly reduced; when the number of the single batteries deviating from the average SOC value does not exceed the threshold value, the battery units where the single batteries are located are balanced layer by layer, and the single batteries can independently run in the respective battery units, so that the balancing speed is accelerated. The inconsistency among the single batteries can be effectively reduced during charging and discharging. The equalizing circuit can obviously improve the equalizing speed of charging and discharging, and make the SOC values of all the single batteries in the battery pack consistent. The equalizing circuit adopts modular equalization, all the modular equalization modes are the same, the principle is simple, the control is easy, the circuit structure is easy to expand, and the equalizing efficiency is high.

Drawings

FIG. 1 is a schematic diagram of an equalizer circuit for hierarchical equalization of a basic chopper circuit in accordance with the present invention;

FIG. 2 is a schematic diagram of a layer 1 static equilibrium circuit of n single batteries (the principle of other layers is the same);

fig. 3 is a schematic diagram of a charge-discharge balancing circuit when the SOC value of the unit in which the unit cell BTi is located is high among the n unit cells;

FIG. 4 is a schematic diagram of a first layer equalization of a standing equalization circuit for 8 single batteries;

FIG. 5 is a schematic diagram of the second layer equalization of the static equalization circuit for 8 single batteries;

FIG. 6 is a schematic diagram of the third layer of equalization of the static equalization circuit for 8 single batteries;

fig. 7 is a schematic diagram of the first layer of equalization of the charge-discharge equalization circuit for 8 single cells (x < γ);

fig. 8 is a schematic diagram of the second layer equalization of the charge-discharge equalization circuit for 8 cells (x < γ);

in fig. 2-8, the gray portion is off, the black portion is on or active, the dashed line is discharging the high SOC cell and the solid line is charging the low SOC cell.

Detailed Description

Example 1: as shown in fig. 1-8, a hierarchical balanced equalizing circuit of a basic chopper circuit is an m-layer equalizing circuit composed of a battery pack, an energy storage inductor, and a Mosfet switch with anti-parallel diodes;

the battery pack is composed of 2^mSingle battery BT_i1Composed of a first layer 2 of a Mosfet switch with antiparallel diodes^mMosfet switch Q1 with anti-parallel diode_i1A second layer 2^m-1Mosfet switch Q2 with anti-parallel diode_i2… and mth layer 2 Mosfet switch Qm with antiparallel diodes_imThe energy storage inductor is composed of

First layer 2^m-1Energy storage inductor L1_j1A second layer 2^m-2Energy storage inductor L2_j2… and m-th layer 2⁰Energy storage inductor Lm_jmComposition is carried out; wherein i1 is 1,2,3^m-0；i2＝1,2,3,...,2^m-1；im＝1,2^m-(m-1)；j1＝1,2,3...,2^m ^-1；j2＝1,2,3...,2^m-2；jm＝2^m-m(ii) a As shown in the figure, n is 2^m；

Specifically, the method comprises the following steps: every 2 single batteries BT on the first layer of the equalizing circuit_i1、BT_i1+1With two Mosfet switches Q1 with anti-parallel diodes_i1、Q1_i1+1And an energy storage inductor L1_(i1+1)/2An equalizing unit forming the first equalizing circuit, energy storage inductor L1_(i1+1)/2One end of each of which is connected with the single battery BT_i1Is negativePole and battery cell BT_i1+1Is connected with the positive pole of the energy storage inductor L1_(i1+1)/2And the other end of the same is respectively connected with a Mosfet switch Q1 with an anti-parallel diode_i1And Mosfet switch Q1 with anti-parallel diode_i1+1Is connected to the drain of the Mosfet switch Q1 with an anti-parallel diode_i1Drain electrode of and single battery BT_i1With antiparallel diode, Mosfet switch Q1_i1+1Source electrode and single battery BT_i1+1The negative electrodes are connected;

second layer 2 each²Single battery BT_i1、BT_i1+1、BT_i1+2、BT_i1+3Mosfet switch Q2 with two parallel diodes_(i1+1)/2、Q2_(i1+1)/2+1And an energy storage inductor L2_(i1+3)/4An equalizing unit forming the second equalizing circuit, energy storage inductor L2_(i1+3)/4One end of each of which is connected with the single battery BT_i1+1Negative electrode of (1), and single cell BT_i1+2The positive pole of (2), energy storage inductor L2_(i1+3)/4And the other end of the switch is respectively connected with a Mosfet switch Q2 with an anti-parallel diode_(i1+1)/2And another Mosfet switch Q2 with an anti-parallel diode_(i1+1)/2+1Is connected to the drain of the Mosfet switch Q2 with an anti-parallel diode_(i1+1)/2Drain electrode of and single battery BT_i1Another Mosfet switch Q2 with an antiparallel diode_(i1+1)/2+1Source electrode and single battery BT_i1+3Is connected to the negative electrode of (1).

For the same reason, the m-th layer 2^mAnd the single battery, two Mosfet switches with anti-parallel diodes and an energy storage inductor form an equalizing unit of the mth layer of equalizing circuit.

For a battery comprising n cells (fig. 1), the battery starts from layer 1 during the rest phase (fig. 2), if the cells BT_uOr BT_vWhen the SOC value (u is odd number and v is even number) is high, the Mosfet switch Q1 is turned on_uOr Q1_vEnergy storage inductor L1_(u+1)/2Or L1_v/2Energy increase, cell BT_uOr BT_vThe SOC value of (3) decreases. Reopening Mosfet switch Q1_uOr Q1_vEnergy storage inductor L1_(u+1)/2Or L1_v/2Energy transfer to the cell BT_u+1Or BT_v-1Energy storage inductor L1_(u+1)/2Or L1_v/2Energy reduction, cell BT_u+1Or BT_v-1Increases the SOC value (see fig. 2). Similarly, the balance is outward from the innermost layer in sequence, so that the left and the right are 2⁰、2¹、…、2^m-1The SOC values of the single batteries are equal, and the SOC of each single battery is finally consistent (if the second layer is balanced, the balancing unit of the second layer is taken as an execution object, and the left and the right are 2¹The SOC values of the individual cells as a whole are calculated). In the process, the layers from the inside to the outside each have 2^m-1、2^m-2、…、2⁰The balancing units can simultaneously and independently operate, and balancing speed is increased.

The battery pack is characterized in that in the charging and discharging process: when the equalizing circuit performs charge-discharge equalization, if a certain single battery BT_uSOC value of (SOC)_uWhen the difference value delta SOC between the SOC and the average SOCav of the battery pack of the battery unit where the battery unit is located is more than or equal to beta, the SOC value of the single battery is considered to deviate from the average SOC value; wherein Δ SOC is SOCav-SOC_uAnd β represents a threshold value (e.g., 5% to 10%), and SOCav ═ SOC₁+SOC₂+,....+SOC_n) And/n. If the SOC values of a plurality of single batteries deviate from the average SOC value (namely x is more than or equal to gamma; x represents the number of the single batteries with the SOC values deviating from the average SOC value, and gamma represents the threshold value of the deviation number), the single batteries are balanced inwards from the mth layer (the principle is the same as that of static balance, as shown in figure 2), and the number of the single batteries deviating from the average SOC value is rapidly reduced. If the SOC values of only a few cells in the battery pack deviate from the average SOC, the cells are equalized within the equalizing unit to which the cells belong (see fig. 3). E.g. of single cells BT in series-connected batteries_uHas a higher SOC value and a single battery BT_vIf the SOC value is lower, the single battery BT in the equalizing unit is conducted_uThe energy of the energy storage inductor in the equalizing unit is increased by the Mosfet switch of the unit, and the single battery BT_uThe mid SOC value decreases. Disconnecting the battery cell BT_uThe Mosfet switch of the unit turns on the single battery BT_vMosfet switch of the cell, in the equalizing unitEnergy storage inductance energy reduction, single battery BT_vThe mid SOC value increases.

Example 2: with 8 (2)³) A single cell is taken as an example.

In the standing equalization process (as shown in fig. 4-6), assuming that the SOC values of the single batteries BT1, BT3, BT5 and BT8 are higher than the SOC value of another single battery in the first-layer equalization circuit, the specific circuit control method is as follows: when Mosfet switches Q11, Q13, Q15 and Q18 are turned on, energy in BT1, BT3, BT5 and BT8 is transferred to energy storage inductors L11, L12, L13 and L14, and SOC values of BT1, BT3, BT5 and BT8 are reduced. Then, Mosfet switches Q11, Q13, Q15 and Q18 are turned off, Mosfet switches Q12, Q14, Q16 and Q17 are turned on, energy in energy storage inductors L11, L12, L13 and L14 is transferred to BT2, BT4, BT6 and BT7, respectively, and the SOC value is increased. And continuously turning on and off the Mosfet switch until the SOC values of the single batteries in the first layer of battery units are the same, so as to realize the first layer of equalization (as shown in FIG. 4). Similarly, the Mosfet switches of the second layer and the third layer are sequentially turned on and off (for example, the SOC of the whole of BT3 and BT4 is higher than that of BT1 and BT2, the SOC of the whole of BT7 and BT8 is higher than that of BT5 and BT6, and Q22 and Q24 are turned on in a pilot mode) to finally make the SOC values of the single batteries in the battery pack consistent (for example, fig. 5 and 6).

In the charge and discharge balancing process, a threshold value gamma is equal to n/2 equal to 4, if x is larger than or equal to gamma, the same balancing principle as that of standing balancing is firstly adopted in 8-cell balancing, and the number of single cells deviating from the average SOC value is greatly reduced through one-time complete balancing. After the equalization process is completed, if the SOC values of the unit batteries BT1 and BT5 are high and the SOC value of the unit battery BT2 is low (at this time, x is 3 and is smaller than 4, as shown in fig. 7), the Mosfet switches Q11 and Q15 are turned on, and the energy in BT1 and BT5 is transferred to the energy storage inductors L11 and L13, respectively. When the Mosfet switches Q11 and Q15 are turned off, the Mosfet switches Q12 and Q16 are turned on, and the energy in the energy storage inductors L11 and L13 is transferred to the single batteries BT2 and BT 6. The process is carried out with two cells simultaneously; if the SOC values of the single batteries BT1 and BT2 approach the average SOC value, the equalization process of the battery unit is finished. If the SOC values of the unit batteries BT5 and BT6 are far from the average SOC value, the next layer of equalization is continued until the SOC values of the unit batteries approach the average SOC value (as shown in fig. 8).

While the present invention has been described in detail with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, and various changes can be made without departing from the spirit of the present invention within the knowledge of those skilled in the art.

Claims

1. An equalizer circuit for hierarchical equalization of a basic chopper circuit, characterized by: the m-layer equalizing circuit is formed by a battery pack, an energy storage inductor and a Mosfet switch with an anti-parallel diode;

the battery pack is composed of 2^mSingle battery BT_i1Composed of a first layer 2 of a Mosfet switch with antiparallel diodes^mMosfet switch Q1 with anti-parallel diode_i1A second layer 2^m-1Mosfet switch Q2 with anti-parallel diode_i2… and mth layer 2 Mosfet switch Qm with antiparallel diodes_imThe energy storage inductor is composed of a first layer 2^m-1Energy storage inductor L1_j1A second layer 2^m-2Energy storage inductor L2_j2… and m-th layer 2⁰Energy storage inductor Lm_jmComposition is carried out; wherein i1 is 1,2,3^m-0；i2＝1,2,3,...,2^m-1；im＝1,2^m-(m-1)；j1＝1,2,3...,2^m-1；j2＝1,2,3...,2^m-2；jm＝2^m-m；