Technical background
Certain monomer falls behind series battery or damage causes whole battery group normally to use because occur, and new used batteries can not be connected to use and be caused very big waste.
In order to reach the equilibrium of battery pack, the following method of existing technical general employing:
1, bypass electric discharge.In charging process, after single battery reaches deboost, open the bypass discharge, reach the purpose that cell voltage no longer rises.This method circuit is simple, but discharge process that can not the balancing battery group;
2, voltage comparison method: use single-chip microcomputer or comparator that the voltage of single battery in the middle of the battery pack is compared mutually, high the carrying out of voltage discharged separately or single low battery of voltage is charged separately.This method implements more complicated, discharge waste battery pack power, and the method that the low battery of voltage is charged separately is difficult to realize in the battery power discharge process;
3, the equalization methods and the circuit of number of patent application 200710025623.4 disclosed battery pack, after its energy process inversion with whole battery group, be lower than the battery charge of average voltage to voltage, in the actual use of battery pack, also there are 3 deficiency: a in this Method and circuits, constantly consume the capacity of whole Battery pack to the battery charge that falls behind, when big or voltage is higher when battery capacity wherein, this circuit will work without cessation, and reach a large amount of battery capacity of process waste of the balance of voltage.B, this circuit adopt rectifies, when loop current is big, will consume bigger power and heating, so this are circuit that the loss battery electric quantity is very big.C, this Method and circuits do not have feedback mechanism, and when wherein a battery capacity was smaller, coil load coupled in the discharge process of whole battery group strengthened, and voltage descends, and can't reach desirable balanced purpose.
Also there is the problem of thermal runaway in actual use in series battery.After battery used a period of time, because the variation of active material, the internal resistance of cell increased, and be uneven, cause battery temperature to rise in the charge or discharge process, electrolyte quickens volatilization, the electrochemical corrosion aggravation causes the out of control of battery pack at last, even causes fire or blast.In the method that solves the battery pack thermal runaway, major part is all used the temperature switch of definite value, when battery pack temperature surpasses the temperature of setting, implements circuit controls.This method can not change with the variations in temperature of environment, and such as under the arctic weather environment, inside battery has generated heat to runaway condition, but because ambient temperature is low, the battery pack rapid heat dissipation can't reach the temperature that temperature switch moves, but battery pack is still damaged because overcharge.In hot environment, battery pack has normal temperature rise may cause the misoperation of temperature switch slightly.
Summary of the invention
The purpose of this invention is to provide a kind of battery set management circuit that the battery pack energy consumption is lower, portfolio effect is good that makes.
Another object of the present invention provides a kind of battery set management circuit that can prevent the battery thermal runaway efficiently and accurately.
Technical scheme of the present invention is such: battery set management circuit, comprise transformer and Switching Power Supply special chip, above-mentioned transformer has plural groups primary coil corresponding respectively with a plurality of cells that are in series, that be in series successively, and every group of number of primary turns is identical, each cell and above-mentioned respectively the group between the primary coil are in parallel by electronic switch respectively, and one of them electronic switch is controlled by the output of above-mentioned Switching Power Supply special chip, and all the other electronic switches are controlled by the synchronous coil of above-mentioned transformer.
Above-mentioned electronic switch is a field effect transistor.
Above-mentioned transformer is a flat surface transformer.
Also comprise the sampling feedback circuit, above-mentioned sampling feedback circuit comprise operational amplifier, above-mentioned transformer secondary coil, with the identical sampling resistor of the corresponding respectively a plurality of resistances that are in series of above-mentioned each cell, the number of turn of above-mentioned secondary coil is identical with the number of turn of above-mentioned primary coil, one the voltage sample output in the above-mentioned sampling resistor and the voltage output end of above-mentioned secondary coil are connected to the input of above-mentioned operational amplifier respectively, and above-mentioned operational amplifier output terminal is connected to the feedback input end of above-mentioned Switching Power Supply special chip.
The temperature control circuit that also comprises control battery set charge/discharge loop break-make, above-mentioned temperature control circuit comprises by second temperature sensing element of first temperature sensing element of sense ambient temperature, sensing battery pack internal temperature and two balance bridges that impedance component constitutes, two node voltage outputs of this balance bridge connect the input of a voltage comparator respectively, and the output of this voltage comparator connects the switch block of a control battery set charge/discharge loop break-make in order to control the break-make of this switch block.
After adopting such scheme, battery set management circuit of the present invention, when the electronic switch conducting of the output that is controlled by the Switching Power Supply special chip, battery pack is to each primary charging coil of series connection, principle according to autotransformer, induced voltage on each primary coil is assembled battery total voltage and removes in the mean value of cell number, meanwhile, all the other electronic switches that are controlled by the synchronous coil of transformer are connected synchronously, and each primary coil is corresponding one by one respectively in parallel with each cell.When the voltage of a certain primary coil during greater than the voltage of the cell in parallel with it, this primary coil is to this cell charging; Otherwise when the voltage of a certain cell during greater than the voltage of the primary coil in parallel with it, this cell is to this primary coil discharge.The loop of other cells too.This is a homeostasis process, as long as have the voltage of a cell to be higher than average voltage in the battery pack, just to corresponding primary coil discharge, obtains charging on the contrary.In the circuit working process, no matter being recharged, the voltage of battery pack rises or externally discharge decline, and each cell all continues to keep average voltage, and battery pack has obtained equilibrium.And among the present invention, feed back to the duty cycle adjustment that the Switching Power Supply special chip carries out output waveform after by the sampling feedback circuit error between the voltage of dividing potential drop on the sampling resistor and transformer secondary output coil being amplified, improve the current load ability of primary coil, keep the steady and balance of each monomer battery voltage.When each cell balance or during near balance, in order to reduce stand-by power consumption, the Switching Power Supply special chip is converted into the PFM control model automatically, enters little power consumption state.Compared with prior art, battery set management circuit of the present invention battery pack is cut down the consumption of energy and portfolio effect good.
And among the present invention, by temperature and the ambient temperature in the temperature control element difference sensing battery pack, by both temperature difference, judge the battery temperature rise, control charging and discharging circuit or prompting early warning can prevent the battery thermal runaway efficiently and accurately.
Embodiment
Battery set management circuit of the present invention, the cell series connection more than two or two can use circuit of the present invention to manage.For convenience of description, the battery of electric bicycle group of the 36V12Ah that is in series with the cell of 3 12V12Ah of present embodiment is that example describes.
As shown in Figure 1, battery set management circuit of the present invention, comprise a transformer, transformer is provided with primary coil N1, N2, N3 and secondary coil N4, N5, the number of turn of primary coil N1, N2, N3 and secondary coil N4 is 6T, primary coil N1, N2, N3 are in series successively, and wherein primary coil N1 is in parallel with cell B1 by switching tube Q2; Primary coil N2 is in parallel with cell B2 by switching tube Q3; Primary coil N3 is in parallel with cell B3 by switching tube Q1.Switching tube Q1 is by the output control break-make of Switching Power Supply special chip IC 1 (PWM or PFM), and Switching Power Supply special chip IC 1 is output as the square wave of EDM Generator of Adjustable Duty Ratio, and concussion frequency 100KHz provides power supply by secondary coil N5 for Switching Power Supply special chip IC 1.Switching tube Q2, Q3 trigger by synchronous coil N6, the N7 of transformer, and the number of turn of coil N6, N7 is 2T synchronously.In the time of switching tube Q1 conducting, the synchronous conducting of switching tube Q2, Q3 is turn-offed too.The extremely low switch mosfet pipe of pressure drop when switching tube Q1, Q2, Q3 all use conducting, when conducting, electric current can two-way flow.
After circuit is connected, the stable 100KHz square wave of Switching Power Supply special chip IC 1 output, pull switch pipe Q1 conducting, suppose that battery voltage is 36V, principle according to autotransformer, induced voltage on primary coil N1, N2, the N3 respectively is 1/3 of an assembled battery total voltage, promptly, the 12V voltage of respectively inducting on primary coil N1, N2, the N3, after switching tube Q2, Q3 synchronous rectification, the switch mosfet tube voltage drop is that 0.01-0.03V ignores, and respectively obtains the charging voltage of 12V on cell B1, B2, the B3.If this moment, the voltage of cell B1 was higher than primary coil N1 voltage, just to primary coil N1 charging, cell B1 voltage descends cell B1; If cell B2 voltage is lower than 12V, primary coil N2 charges to cell B2, and cell B2 voltage rises.This is a homeostasis process, as long as have the voltage of a cell to be higher than average voltage in the battery pack, just to corresponding primary coil discharge, obtains charging on the contrary.In the circuit working process, no matter being recharged, the voltage of battery pack rises or externally discharge decline, and each cell all continues to keep average voltage, and battery pack has obtained equilibrium.When switching tube Q1 closed, above operating state stopped, the action that switching tube Q1 constantly opens repeatedly and closes, and electric charge reaches balance from the battery that high-tension battery continues the inflow low-voltage.
Each switching tube conduction voltage drop is very little in the circuit of the present invention, belongs to little power consumption design.The up-to-date flat surface transformer of transformer adopting, volume is little, and mechanical efficiency can reach more than 95%.
In order to improve the current load ability of transformer coil, keep the steady and balance of each battery cell voltage, the present invention also is provided with the sampling feedback circuit.The sampling feedback circuit comprises sampling resistor R10, R11, the R12 that the secondary coil N4 of operational amplifier IC2, transformer is identical with resistance and be in series, the voltage sample output of sampling resistor R12 and the voltage output end of secondary coil N4 are connected to the input of operational amplifier IC2 respectively, and operational amplifier IC2 output is connected to the feedback input end of Switching Power Supply special chip IC 1 by optocoupler LE.The resistance R 10 of resistances such as the present invention uses, R11, the R12 series connection is sampled to whole battery group, when assembled battery total voltage is 36V, sampled voltage on the sampling resistor R12 is 12V, the voltage that produces with secondary coil N4 compares, the voltage of secondary voltage N4 and primary voltage N1, N2, N3 is identical, when the transformer coil load is big, dividing potential drop on the resistance R 12 is less than the voltage of secondary coil N4, operational amplifier IC2 feeds back to the duty cycle adjustment that Switching Power Supply special chip IC 1 carries out output waveform after this voltage difference is amplified, improve the current load ability of coil, keep the steady and balance of single cell voltage.When each cell balance or during near balance, in order to reduce stand-by power consumption, Switching Power Supply special chip IC 1 is converted into the PFM control model automatically, enters little power consumption state.
Among the present invention, in order to make the use of can connecting of new used batteries, reach bigger balanced balanced current, also the number of turn of secondary coil N4 can be adjusted into than primary coil N1 and many 1T, the voltage of secondary voltage N4 absorbs through the capacitance-resistance of capacitor C 3 and resistance R 9 after through diode Vd4 rectification again, removes to adjust behind the clutter to reach identical with resistance R 12 voltage when the zero load.If cell B3 seriously falls behind in the battery pack, at this moment secondary coil N4 strengthens the charging current of primary coil N3 cell B3, terminal voltage descends, secondary coil N4 voltage and then descends, operational amplifier IC2 feeds back to Switching Power Supply special chip IC 1 through optocoupler LE after voltage error is amplified, and Switching Power Supply special chip IC 1 is adjusted duty ratio, improve the transformer output current, stablize the terminal voltage of primary coil N3.The design suitable transformer, elementary single coil can provide tall and big balanced balanced current in 10A, suppose that wherein a cell capacity is 20% of other cell capacity, battery pack still can charge normal and discharge, and the total capacity of battery is the summation of 3 independent capacity of battery.Reach the purpose that new used batteries can be connected and be used.
For can be effective, prevent the battery thermal runaway exactly, the present invention has also designed the temperature control circuit of control battery set charge/discharge loop break-make, temperature control circuit comprises the thermo-sensitive resistor Rt1 by sense ambient temperature, the thermo-sensitive resistor Rt2 of sensing battery pack internal temperature and resistance R 1, the balance bridge that R2 constitutes, two node voltage outputs of this balance bridge connect the input of voltage comparator ic 3 respectively, the output of voltage comparator ic 3 connects the base stage of switch triode Vt1, be connected with the coil of relay J between the emitter of switch triode Vt1 and the positive source, the normally closed auxiliary contact of relay J is connected in the break-make that is used to control the battery set charge/discharge loop on the battery set charge/discharge loop.The node voltage of the balance bridge that is made of thermo-sensitive resistor Rt1, thermo-sensitive resistor Rt2 and resistance R 1, R2 compares through voltage comparator ic 3, resistance by thermo-sensitive resistor Rt1, Rt2 is set, can be provided with when ambient temperature and battery pack temperature difference are n, voltage comparator ic 3 output switching activity pull switch triode Vt1 realize the control in battery charging and discharging loop.
In the present embodiment, the resistance of thermo-sensitive resistor Rt1 is 600K, 1 ℃ of the every rising of temperature, resistance increases 5K, and the resistance of thermo-sensitive resistor Rt2 is 500K, 1 ℃ of the every rising of temperature, resistance increases 5K, each 500K of the resistance of resistance R 1, R2, and electric bridge is in non-equilibrium state, the 6th pin output low level of voltage comparator ic 3, switch triode Vt1 is in cut-off state.When battery pack temperature exceeds 20 ℃ than ambient temperature, the resistance value ratio thermo-sensitive resistor Rt1 of thermo-sensitive resistor Rt2 increases more than the 100K, the 6 pin output high level of voltage comparator ic 3, switch triode Vt1 conducting, the relay J adhesive, the battery charging and discharging loop disconnects, and the condition that causes battery temperature to raise after the circuitry cuts disappears, battery pack temperature descends, and relay J is closed again.In actual use, battery of electric vehicle generally rises bigger in the charging process temperature, when reaching above-mentioned condition; the battery charging and discharging loop is cut off and connects; charger promptly transfers floating charge state to by constant current or constant voltage charge state, and charging voltage descends, and battery pack is protected.In discharge process, if the excessive battery pack temperature that also may cause of long-time discharging current rises, when reaching above-mentioned condition, circuitry cuts is connected again, and controller enters under-voltage protection, can not continue discharge again, and battery pack is protected.