The active equalization system of dynamical lithium-ion battery packs and equalization methodsTechnical field
The present invention relates to active equalization system and equalization methods, particularly relate to active equalization system and the equalization methods of dynamical lithium-ion battery packs.
Background technology
Dynamical lithium-ion battery packs generally adopts series system to connect, due to each monomer lithium ion battery because manufacturing process causes initial capacity, voltage, internal resistance etc. incomplete same, cause the overcharge and the overdischarge phenomenon that in use cause monomer lithium ion battery, individual monomers lithium ion battery premature aging, inefficacy can be caused, the capacitance decline of dynamical lithium-ion battery packs, short service life time serious.
In discharge process; first the monomer lithium ion battery that electricity is low is discharged in discharge process; in order to protect the dynamical lithium-ion battery packs after series connection; whole dynamical lithium-ion battery packs stops electric discharge; the monomer lithium ion battery that electricity is high still has the electricity do not discharged; cause whole dynamical lithium-ion battery packs service time and capacity actual be determined by minimum that block monomer lithium ion battery of capacity; namely, when this monomer lithium ion battery capacity comes to an end, other monomer lithium ion battery also cannot work on.The charging process of dynamical lithium-ion battery packs is also like this.In charging process; first minimum that block monomer lithium ion battery of capacity can be filled again, and in order to protect dynamical lithium-ion battery packs, whole dynamical lithium-ion battery packs stops charging; make other monomer lithium ion battery of whole dynamical lithium-ion battery packs not be filled electricity, capacitance seriously reduces.As can be seen here, in the course of the work, to dynamical lithium-ion battery packs unbalanced between power lithium-ion battery affect the principal element that dynamical lithium-ion battery packs normally works, and it is very necessary for carrying out Balance route to dynamical lithium-ion battery packs.
Summary of the invention
The present invention overcomes above-mentioned weak point, object is the active equalization system and the equalization methods that provide dynamical lithium-ion battery packs, system architecture is simple, easy to operate, have the advantages that balanced energy transmission is direct, euqalizing current is large, loss power consumption is little, extend the working life of battery pack, adaptability is good, and reliability is high.
The present invention achieves the above object by the following technical programs: the active equalization system of dynamical lithium-ion battery packs, comprising: battery module, matrix control circuit, DC/DC unit, PWM control unit, main control unit, voltage temperature sampling unit; Described battery module is composed in series by several cells, and all cell two ends in battery module are all connected with voltage temperature sampling unit; Described matrix control circuit comprises several gate-controlled switches, in battery module, the gate-controlled switch at cell two ends is connected with DC/DC unit arbitrarily, DC/DC unit is connected with PWM control unit, PWM control unit is connected with main control unit, and main control unit is also connected with matrix control circuit, voltage temperature sampling unit.
Described DC/DC unit comprises: transformer T1, switching tube Q1, switch S a, switching tube Q2, switch Sb; The primary coil of described transformer T1 is connected to switching tube Q1, rectifier diode R1 and the controllable switch S a in parallel with rectifier diode R1; The secondary coil of described transformer T1 is connected to switching tube Q2, rectifier diode R2 and the controllable switch S b in parallel with rectifier diode R2; Positive terminal, the negative pole end of the interior cell arbitrarily of battery module are equipped with gate-controlled switch, and switch S a is connected with the gate-controlled switch of any cell positive terminal, and switching tube Q1 is connected with the gate-controlled switch of any cell negative pole end; Switch Sb is connected with the positive pole of battery module, and switching tube Q2 is connected with the negative pole of battery module, the minus earth of battery module; Main control unit controls the folding of gate-controlled switch, switch S a, switch Sb; Main control unit by PWM control unit control switch pipe Q1, switching tube Q2 open close.
Switch S a in described DC/DC unit, switch Sb, switching tube Q1, switching tube Q2 are field effect transistor or triode or IGBT.
Gate-controlled switch in described matrix majorization unit is field effect transistor, triode, IGBT.
The active equalization method of dynamical lithium-ion battery packs, comprises the following steps:
1) n is saved cell and be composed in series battery module successively, the minus earth of battery module, voltage temperature sampling unit is sampled to the voltage at each cell two ends in battery module, and the voltage of note cell is Ui(i≤n), sampled result is transported to main control unit;
2) main control unit receives sampled result, and obtains the average voltage level U of cell in battery module according to sampled result, according to U△ i=Ui-U, obtains the voltage deviation value U of cell△ i, compare U△ isize obtains voltage deviation maximum U△ imax;
3) main control unit U that step 3) is obtained△ imaxjudge, judge whether to meet presetting balance policy, the cell high to electricity carries out upper limit equilibrium, and the cell that electricity is low carries out lower limit equilibrium; Main control unit carries out battery health assessment to cell in battery module use procedure, judges certain cell capacity deficiency and carries out energy compensating;
4) after equilibrium judgement being carried out to all cells according to step 3), main control unit 3
Judge the cell not needing equilibrium or compensation, then jump back to step 1), voltage temperature sampling unit carries out the sampling of new round voltage temperature;
5) when voltage temperature sampling unit samsara number of samples reaches requirement, after main control unit 3 does not find to need cell that is balanced or that compensate, system enters dormancy.
Described upper limit equilibrium comprises the following steps: main control unit obtains the voltage deviation value U needing the cell carrying out electric quantity balancing△ iafter, in gating matrix control unit, corresponding gate-controlled switch closes, and this cell is connected to DC/DC unit; Main control unit control switch Sa, switching tube Q2 conducting, switch Sb disconnects, and PWM control unit control switch pipe Q1 is operated on off state; This cell is discharged to battery module by DC/DC unit, until the U of this cell△ imeet presetting balance policy.
Described lower limit equilibrium comprises the following steps: main control unit obtains the voltage deviation value U needing the cell carrying out electric quantity balancing△ iafter, in gating matrix control unit, corresponding gate-controlled switch closes, and this cell is connected to DC/DC unit; Main control unit control switch Sb, switching tube Q1 conducting, switch S a disconnects, and PWM control unit control switch pipe Q2 is operated on off state; This cell passes through DC/DC unit to charging battery module, until the U of this cell△ imeet presetting balance policy.
Described energy compensating comprises the following steps: main control unit carries out battery health assessment to cell in battery module use procedure, judges that certain cell capacity is not enough and obtains the voltage deviation value U of this cell△ i; In main control unit gating matrix control unit, corresponding gate-controlled switch closes, and this cell is connected to DC/DC unit; Main control unit control switch Sb, switching tube Q1 conducting, switch S a disconnects, and PWM control unit control switch pipe Q1 is operated on off state; This cell passes through DC/DC unit to charging battery module, until the U of this cell△ imeet presetting compensation policy.
Beneficial effect of the present invention is: by the control to DC/DC unit and matrix control circuit, changes the direction of transformer T1 discharge and recharge, achieve balanced to the upper limit of electric quantity of single batteries in battery module, lower limit is balanced and energy compensating function; Upper limit equilibrium is adapted at implementing in charging process, overcharges to prevent Individual cells monomer; Lower limit equilibrium can be avoided putting; When energy compensating function then ensure that individual monomers battery premature aging, inefficacy, battery module still can normally work.Compared with the prior art, the present invention has the following advantages:
(l) low-loss balancing technique, time balanced, energy loss is very little, and especially when energy compensating, energy transfer efficiency is high, guarantees that battery module keeps capacity, increases the service life;
(2) big current balancing technique, euqalizing current ability reaches more than lOA;
(3) bidirectional equalization technology, can to realize in battery pack arbitrarily between cell and battery module direct bidirectional energy shift, and the switch for controlling does not need high frequency to switch, reliability and stability high;
(4) collecting and distributing type design, simple and practical, easy to connect, extensibility is fabulous.
Accompanying drawing explanation
Fig. 1 is the structural representation of present system;
In figure: 1, battery module; 2, voltage temperature sampling unit; 3, main control unit; 4, matrix control circuit; 5, PWM control unit; 6, DC/DC unit.
Embodiment
Below in conjunction with specific embodiment, the present invention is described further, but protection scope of the present invention is not limited in this:
As shown in Figure 1, the active equalization system of dynamical lithium-ion battery packs, comprising: battery module 1, matrix control circuit 4, DC/DC unit 6, PWM control unit 5, main control unit 3, voltage temperature sampling unit 2; Described battery module 1 is composed in series by n cell, and all cell two ends in battery module 1 are all connected with voltage temperature sampling unit 2; Described matrix control circuit 4 comprises 2n gate-controlled switch, in battery module 1, the gate-controlled switch at cell two ends is connected with DC/DC unit 6 arbitrarily, DC/DC unit 6 is connected with PWM control unit 5, PWM control unit 5 is connected with main control unit 3, and main control unit 3 is also connected with matrix control circuit 4, voltage temperature sampling unit 2.
Described DC/DC unit 6 comprises: transformer T1, switching tube Q1, switch S a, switching tube Q2, switch Sb; The primary coil of described transformer T1 is connected to switching tube Q1, rectifier diode R1 and the controllable switch S a in parallel with rectifier diode R1; The secondary coil of described transformer T1 is connected to switching tube Q2, rectifier diode R2 and the controllable switch S b in parallel with rectifier diode R2; Positive terminal, the negative pole end of the interior cell arbitrarily of battery module 1 are equipped with gate-controlled switch, and switch S a is connected with the gate-controlled switch of any cell positive terminal, and switching tube Q1 is connected with the gate-controlled switch of any cell negative pole end; Switch Sb is connected with the positive pole of battery module 1, and switching tube Q2 is connected with the negative pole of battery module 1, the minus earth of battery module 1; Main control unit 3 controls the folding of gate-controlled switch, switch S a, switch Sb; Main control unit 3 by PWM control unit 5 control switch pipe Q1, switching tube Q2 open close.
The gate-controlled switch that in battery module 1, each cell positive terminal connects is connected with positive bus A, and positive bus A is connected with DC/DC unit 6 breaker in middle Sa; The gate-controlled switch that in battery module 1, each cell negative pole end connects is connected with negative bus B, and negative bus B is connected with DC/DC unit 6 breaker in middle pipe Q1.The positive terminal of battery module 1 is connected with switch Sb, and the negative pole end of battery module 1 is connected with switching tube Q2.
Meanwhile, main control unit 3 is connected with positive bus A, negative bus B, main control unit 3 can gate-controlled switch in gating matrix control circuit 4 and switch S a, switch Sb folding; PWM control unit 5 and switching tube Q1, switching tube Q2 open close, main control unit 3 is worked by PWM control unit 5 control switch pipe Q1, switching tube Q2.
Battery module 1 is in series by n cell, voltage temperature sampling unit 2 is to the voltage sample of each cell, obtain U1, U2 ... Un, the magnitude of voltage collected is transported to main control unit 3 by voltage temperature sampling unit 2, main control unit 3 calculates the average voltage level U of cell, i.e. U=(U1+U2+ ... + Un)/n.Main control unit 3 is according to Ui(i≤n obtained above) and U, calculate the voltage deviation value U of each cell△ i, i.e. U△ i=Ui-U.Presetting balance policy and compensation policy in main control unit 3, set the U of cell△ iand the correlation of the average voltage level U of cell.As the voltage deviation U of cell△ iwhen meeting setting relation with the average voltage U of cell, main control unit 3 takes compulsory exercise, by DC/DC unit 6 equilibrium carried out to corresponding electric quantity of single batteries or carry out energy compensating, make the energy of each cell after isostatic compensation, meet the requirement of setting in main control unit 3 in advance.
In order to carry out active equalization to above-mentioned power lithium-ion battery, the active equalization method of described dynamical lithium-ion battery packs comprises the following steps:
1) n is saved cell and be composed in series battery module 1 successively, the minus earth of battery module 1, in voltage temperature sampling unit 2 pairs of battery modules 1, the voltage at any cell two ends is sampled, and the voltage of note cell is Ui(i≤n), sampled result is transported to main control unit 3;
2) main control unit 3 receives sampled result, and obtains the average voltage level U of cell in battery module 1 according to sampled result, according to U△ i=Ui-U, obtains the voltage deviation value U of cell△ i, compare U△ isize obtains voltage deviation maximum U△ imax;
3) U that obtains of main control unit 3 pairs of step 3)△ imaxjudge, judge whether to meet presetting balance policy, the cell high to electricity carries out upper limit equilibrium, and the cell that electricity is low carries out lower limit equilibrium; Main control unit 3 carries out battery health assessment to cell in battery module 1 use procedure, judges certain cell capacity deficiency and carries out energy compensating;
The upper limit is balanced: main control unit 3 obtains the voltage deviation value U needing the cell carrying out electric quantity balancing△ iafter, in gating matrix control unit 4, corresponding gate-controlled switch closes, and this cell is connected to DC/DC unit 6; Main control unit 3 control switch Sa, switching tube Q2 conducting, switch Sb disconnects, and PWM control unit 5 control switch pipe Q1 is operated on off state; This cell is discharged to battery module 1 by DC/DC unit 6, until the U of this cell△ imeet presetting balance policy;
Lower limit is balanced: main control unit 3 obtains the voltage deviation value U needing the cell carrying out electric quantity balancing△ iafter, in gating matrix control unit 4, corresponding gate-controlled switch closes, and this cell is connected to DC/DC unit 6; Main control unit 3 control switch Sb, switching tube Q1 conducting, switch S a disconnects, and PWM control unit 5 control switch pipe Q2 is operated on off state; This cell is charged to battery module 1 by DC/DC unit 6, until the U of this cell△ imeet presetting balance policy;
Energy compensating: main control unit 3 carries out battery health assessment to cell in battery module 1 use procedure, judges that certain cell capacity is not enough and obtains the voltage deviation value U of this cell△ i; In main control unit 3 gating matrix control unit 4, corresponding gate-controlled switch closes, and this cell is connected to DC/DC unit 6; Main control unit 3 control switch Sb, switching tube Q1 conducting, switch S a disconnects, and PWM control unit 5 control switch pipe Q1 is operated on off state; This cell is charged to battery module 1 by DC/DC unit 6, until the U of this cell△ imeet presetting compensation policy;
4), after carrying out equilibrium judgement according to step 3) to all cells, main control unit 3 judges the cell not needing equilibrium or compensation, then jump back to step 1), and voltage temperature sampling unit 2 carries out the sampling of new round voltage temperature;
5) when voltage temperature sampling unit 2 samsara number of samples reaches requirement, after main control unit 3 does not find to need cell that is balanced or that compensate, system enters resting state.
Sampled result, by sampling to the cell both end voltage in battery module 1, is input in main control unit 3 by the present invention, and main control unit 3 is according to the balance policy Output rusults preset.Main control unit 3 is by the control to DC/DC unit 6 and matrix control circuit 4, change the discharge and recharge direction of transformer T1, upper limit equilibrium is carried out to the cell of high electricity, lower limit equilibrium is carried out to the cell of low electricity, the battery module 1 aligned in use carries out energy compensating.Upper limit equilibrium can prevent cell from overcharging; Lower limit equilibrium can prevent from cell from crossing putting; When energy supplement can ensure that individual monomers battery premature aging lost efficacy, battery module 1 still can normally work.The present invention samples the active equalization mode of the two-way charge and discharge of transformer T1, the upper limit equilibrium to different monomers battery can be realized simultaneously, lower limit is balanced, have loss power consumption little, balanced energy is large, the direct feature of energy trasfer, can also extend the useful life of battery pack, during guarantee individual monomers battery failure, battery module 1 can also normally work.
The know-why being specific embodiments of the invention and using described in above, if the change done according to conception of the present invention, its function produced do not exceed that specification and accompanying drawing contain yet spiritual time, must protection scope of the present invention be belonged to.