CN108565931B - Battery pack voltage equalization circuit based on transformer - Google Patents
Battery pack voltage equalization circuit based on transformer Download PDFInfo
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- CN108565931B CN108565931B CN201810550502.XA CN201810550502A CN108565931B CN 108565931 B CN108565931 B CN 108565931B CN 201810550502 A CN201810550502 A CN 201810550502A CN 108565931 B CN108565931 B CN 108565931B
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- 238000004804 winding Methods 0.000 claims abstract description 140
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- 239000003990 capacitor Substances 0.000 claims description 56
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- 238000007599 discharging Methods 0.000 abstract description 3
- 238000010586 diagram Methods 0.000 description 6
- 230000004907 flux Effects 0.000 description 3
- 230000006698 induction Effects 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000009977 dual effect Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
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- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
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- 238000004134 energy conservation Methods 0.000 description 1
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- 238000001914 filtration Methods 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
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- 229910052742 iron Inorganic materials 0.000 description 1
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0013—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries acting upon several batteries simultaneously or sequentially
- H02J7/0014—Circuits for equalisation of charge between batteries
- H02J7/0019—Circuits for equalisation of charge between batteries using switched or multiplexed charge circuits
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Charge And Discharge Circuits For Batteries Or The Like (AREA)
Abstract
The invention provides a battery pack voltage equalization circuit based on a transformer, which comprises a battery pack and a voltage equalization module; the battery pack comprises a plurality of single batteries connected in series; the voltage equalization module comprises voltage equalization units with the same number as that of the single batteries; each voltage equalization unit comprises a transformer and a switching circuit; the transformer comprises a first primary winding, a second primary winding and a secondary winding; the synonym end of the first primary winding and the synonym end of the second primary winding are alternately conducted to the cathodes of the corresponding single batteries through a switch circuit; the secondary windings of the transformers in the voltage equalization units are connected in parallel. According to the voltage balancing circuit of the battery pack based on the transformer, provided by the invention, voltage balancing is automatically performed in real time according to the voltage difference of each single battery in the charging and discharging processes of the battery pack, so that the single battery with low voltage can be ensured to obtain isolated safe charging of other single batteries with higher voltage, and low-loss high-efficiency voltage balancing is realized.
Description
Technical Field
The invention relates to the technical field of battery circuits, in particular to a battery pack voltage equalization circuit based on a transformer.
Background
Because of limited capacity and voltage, a plurality of single batteries are often connected in series to form a battery pack with relatively high voltage and relatively large capacity for use. During the use of the series battery pack, the battery with small capacity and poor performance can generate an overcharge phenomenon when being charged due to the difference of individual capacities caused by factors such as the manufacturing process of each single battery, and the battery with small capacity and poor performance can generate an overdischarge phenomenon when being discharged; has great potential safety hazard and shortens the service life of the battery pack.
In order to solve the problem caused by the difference between the single cells of the series battery, it is necessary to perform voltage equalization on the single cells of the battery during the use of the battery. In the prior art, each single battery in the battery pack is connected with a resistor in parallel, and balance is realized in a mode that the resistor consumes redundant electric quantity. However, the excessive electric quantity consumed by the resistor can cause the local heating and temperature rise of the battery pack, the heat dissipation requirement on the battery pack is high, and the balanced mode realized through the resistor consumption is the waste of battery electric energy, which is not beneficial to energy conservation and environmental protection.
Disclosure of Invention
In order to solve the defects in the prior art, the invention provides a battery pack voltage balancing circuit based on a transformer, so as to reduce the waste of electric energy in the process of balancing the battery pack voltage.
In order to achieve the above object, the present invention provides a voltage equalization circuit for a battery pack based on a transformer, comprising a battery pack and a voltage equalization module;
the battery pack comprises a plurality of single batteries connected in series;
the voltage equalization module comprises voltage equalization units with the same number as the single batteries; the voltage equalization units are connected with the single batteries in a one-to-one correspondence manner;
each voltage equalization unit comprises a transformer and a switching circuit;
the transformer comprises a first primary winding, a second primary winding and a secondary winding; the number of coil turns of the first primary winding and the second primary winding are the same; the winding directions of the coils of the first primary winding and the second primary winding are opposite;
the homonymous end of the first primary winding and the heteronymous end of the second primary winding are both connected to the positive electrode of the corresponding single battery;
the synonym end of the first primary winding and the synonym end of the second primary winding are alternately conducted to the cathodes of the corresponding single batteries through the switch circuit;
the secondary windings of the transformers in the voltage equalization units are connected in parallel.
Further, the switching circuit comprises a first field effect transistor, a second field effect transistor and a field effect transistor driving circuit; the first field effect tube is connected in series between the synonym end of the first primary winding and the negative electrode of the corresponding single battery; the second field effect tube is connected in series between the homonymous end of the second primary winding and the negative electrode of the corresponding single battery; the field effect transistor driving circuit controls the first field effect transistor and the second field effect transistor to be alternately conducted.
Further, the field effect transistor driving circuit comprises a first voltage dividing resistor, a second voltage dividing resistor, a first current limiting resistor, a second current limiting resistor, a first diode, a second diode, a first capacitor and a second capacitor;
the first voltage dividing resistor and the second voltage dividing resistor are connected in series between the first input power supply and the cathode of the single battery;
one end of the first current limiting resistor is connected to a common end of the first voltage dividing resistor and the second voltage dividing resistor; the other end of the first current-limiting resistor is connected with one end of the first capacitor and the first diode
The anode of the polar tube is connected with the grid electrode of the first field effect tube; the other end of the first capacitor and the negative electrode of the first diode are connected to the same-name end of the first primary winding;
one end of the second current limiting resistor is connected to the common end of the first voltage dividing resistor and the second voltage dividing resistor; the other end of the second current limiting resistor is connected with one end of the second capacitor, the positive electrode of the second diode and the grid electrode of the second field effect transistor; the other end of the second capacitor and the negative electrode of the second diode are connected to the synonym end of the second primary winding.
Further, the first diode and the second diode are both common cathode dual diodes.
Further, the switch circuit further comprises a drive protection switch circuit; the driving protection switch circuit comprises a third field effect transistor, a fourth field effect transistor and a singlechip;
the drain electrode of the third field effect transistor is connected with the grid electrode of the first field effect transistor; the source electrode of the third field effect tube is connected with the cathode of the corresponding single battery;
the drain electrode of the fourth field effect transistor is connected with the grid electrode of the second field effect transistor; the source electrode of the fourth field effect tube is connected with the cathode of the corresponding single battery;
the grid electrode of the third field effect tube and the grid electrode of the fourth field effect tube are connected with the singlechip; the singlechip controls the third field effect transistor and the fourth field effect transistor to be switched on or off.
Further, each voltage equalization unit further comprises a filter circuit; the filter circuit comprises a first filter capacitor, a second filter capacitor, a third filter capacitor, a filter inductor and a third diode; the anode of the third diode is connected with the same-name end of the first primary winding and the different-name end of the second primary winding, and the cathode of the third diode is connected with the anode of the corresponding single battery; the filter inductor is connected with the third diode in parallel, and after the first filter capacitor and the second filter capacitor are connected in parallel, the filter inductor is connected in series between one end of the filter inductor and the cathode of the corresponding single battery; the third filter capacitor is connected in series between the other end of the filter inductor and the negative electrode of the corresponding single battery.
Further, a turns ratio of the secondary winding to the primary winding in each of the transformers is 1 to 5:1.
further, the transformer is a transformer wound by a nanocrystalline annular magnetic core.
According to the voltage balancing circuit of the battery pack based on the transformer, provided by the invention, the two primary windings of the transformer in the voltage balancing unit are alternately conducted to the output ends of the single batteries, so that alternating magnetic flux is produced in the magnetic core of the transformer, induced voltages which are in direct proportion to the voltages of all the single batteries are generated on the secondary windings of the transformer, the secondary windings of all the transformers are connected in parallel, and the single batteries with lower voltages are charged through energy transfer on the secondary windings, so that the single batteries with high voltages can perform isolated lossless charging on the single batteries with low voltages. According to the voltage balancing circuit of the battery pack based on the transformer, provided by the invention, voltage balancing is automatically performed in real time according to the voltage difference of each single battery in the charging and discharging processes of the battery pack, so that the single battery with low voltage can be ensured to obtain isolated safe charging of other single batteries with higher voltage, and low-loss high-efficiency voltage balancing is realized.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the following description will briefly explain the drawings used in the embodiments or the description of the prior art, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a circuit block diagram of a voltage equalizing circuit of a battery pack based on a transformer;
FIG. 2 is a schematic circuit diagram of the voltage equalization unit of FIG. 1;
fig. 3 is a schematic circuit diagram of an embodiment of the present invention.
Reference numerals:
Detailed Description
To make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the present invention will be combined with
The accompanying drawings, which are included to provide a further understanding of the invention, illustrate and together with the description serve to explain the principles of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The terms "first," "second," and the like, as used in embodiments of the present invention, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. "one end," "the other end," and the like, merely indicate that the apparatus or element is oriented or positioned in a relationship based on that shown in the drawings, and do not indicate or imply that the apparatus or element must have a particular orientation, be constructed and operate in a particular orientation. The word "comprising" or "comprises", and the like, is intended to mean that elements or items preceding the word encompass the elements or items listed thereafter and equivalents thereof without precluding other elements or items. "connected" or "connected" and the like are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.
Fig. 1 is a block diagram of a voltage equalizing circuit of a battery pack based on a transformer according to an embodiment of the present invention; referring to fig. 1, the transformer-based battery pack voltage balancing circuit provided by the invention comprises a battery pack 10 and a voltage balancing module.
The battery pack 10 includes a plurality of unit cells 11 connected in series.
The voltage equalization module includes the same number of voltage equalization units 20 as the unit cells 11; the voltage equalization units 20 are connected to the unit cells 11 in a one-to-one correspondence.
Each of the voltage equalization units 20 includes a transformer 21 and a switching circuit 22.
The transformer 21 includes a first primary winding, a second primary winding, and a secondary winding; the number of coil turns of the first primary winding and the second primary winding are the same; the winding directions of the coils of the first primary winding and the second primary winding are opposite.
The homonymous end of the first primary winding and the heteronymous end of the second primary winding are both connected to the positive electrode of the corresponding unit cell 11.
The opposite-name end of the first primary winding and the same-name end of the second primary winding are alternately conducted to the negative electrode of the corresponding single battery 11 through the switch circuit 22.
The secondary windings of the transformers 21 in each of the voltage equalization units 20 are connected in parallel.
In the specific implementation, as shown in fig. 1, the battery pack 10 is formed by connecting N unit cells 11 (C1 to Cn) in series, where N is an integer equal to or greater than 2, and the specific number of unit cells 11 may be set as needed. Wherein the negative electrode of the 1 st single cell 11 is used as the negative electrode of the battery pack 10, and the positive electrode of the N-th single cell 11 is used as the positive electrode of the battery pack 10; the positive electrode of the 1 st single cell 11 is connected with the negative electrode of the 2 nd single cell 11, the positive electrode of the 2 nd single cell 11 is connected with the negative electrode of the 3 rd single cell 11, and so on.
Each of the unit cells 11 is provided with a voltage equalizing unit 20 for equalizing the voltages of the unit cells 11. As shown in fig. 1, the circuit configuration of each voltage equalizing unit 20 is the same, and the voltage equalizing unit 20 includes a transformer 21 and a switching circuit 22; the transformer 21 includes two primary windings and one secondary winding; the number of turns of the coils of the two primary windings is the same and the winding directions are opposite; as shown in fig. 2, the 3 rd pin and the 4 th pin of the transformer 21 are the first primary winding, the 2 nd pin and the 5 th pin of the transformer 21 are the second primary winding, the 1 st pin and the 6 th pin of the transformer 21 are the secondary windings, wherein the 4 th pin, the 2 nd pin and the 1 st pin of the transformer 21 are the homonymous ends of the first primary winding, the second primary winding and the secondary winding respectively, and the 3 rd pin, the 5 th pin and the 6 th pin of the transformer 21 are the heteronymous ends of the first primary winding, the second primary winding and the secondary winding respectively; the homonymous end of the first primary winding and the homonymous end of the second primary winding are both connected to the positive electrode of the corresponding single battery 11, and the homonymous end of the first primary winding and the homonymous end of the second primary winding are alternately conducted to the negative electrode of the corresponding single battery 11 through a switch circuit 22; in the embodiment of the present invention, the corresponding unit cell 11 is the unit cell 11 connected to the voltage balancing unit 20.
Specifically, fig. 2 is a schematic circuit diagram of the voltage equalization unit of the present invention, and fig. 3 is an exemplary schematic circuit diagram when the number of unit cells is two; as shown in fig. 2 and 3, the switching circuit 22 in the embodiment of the present invention includes a first fet Qn1, a second fet Qn2, and a fet driving circuit; which is a kind of
The first field effect tube Qn1 is connected in series between the different-name end of the first primary winding and the negative electrode of the corresponding single battery, and is used for connecting or disconnecting the different-name end of the first primary winding and the negative electrode of the corresponding single battery; the second field effect transistor Qn2 is connected in series between the same-name end of the second primary winding and the negative electrode of the corresponding single battery, and is used for switching on or switching off the connection between the different-name end of the first primary winding and the negative electrode of the corresponding single battery.
The field effect transistor driving circuit is used for driving the first field effect transistor Qn1 and the second field effect transistor Qn2 to be alternately conducted, so that the different-name end of the first primary winding and the same-name end of the second primary winding are alternately conducted to the negative electrode of the corresponding single battery 11; the field effect transistor driving circuit comprises a first voltage dividing resistor Rn1, a second voltage dividing resistor Rn2, a first current limiting resistor Rn3, a second current limiting resistor Rn4, a first diode Yn1, a second diode Yn2, a first capacitor CTn1 and a second capacitor CTn2.
As shown in fig. 2, the first voltage dividing resistor Rn1 and the second voltage dividing resistor Rn2 are connected in series between the first input power supply charge+ and the negative electrode of the unit cell, and the output voltage of the first input power supply charge+ is the same as the output voltage of the corresponding unit cell; the voltage at the common end of the first voltage dividing resistor Rn1 and the second voltage dividing resistor Rn2 is the divided voltage of the second voltage dividing resistor; preferably, the resistance value of the second voltage dividing resistor Rn2 is 15-20 times that of the first voltage dividing resistor Rn1, and in the embodiment of the invention, the resistance value of the first voltage dividing resistor Rn1 is 30kΩ, and the resistance value of the second voltage dividing resistor Rn2 is 510kΩ.
One end of the first current limiting resistor Rn3 is connected to the common end of the first voltage dividing resistor Rn1 and the second voltage dividing resistor Rn 2; the other end of the first current limiting resistor Rn3 is connected with one end of the first capacitor CTn1, the anode of the first diode Yn1 and the grid electrode of the first field effect transistor Qn1, and the connection point is recorded as a first driving voltage output point Vngs1; the other end of the first capacitor CTn1 and the negative electrode of the first diode Yn1 are both connected to the same-name end of the first primary winding, i.e. the first capacitor CTn1 and the first diode Yn1 are connected in parallel.
One end of the second current limiting resistor Rn4 is connected to the common end of the first voltage dividing resistor Rn1 and the second voltage dividing resistor Rn 2; the other end of the second current limiting resistor Rn4 is connected with one end of the second capacitor CTn2, the positive electrode of the second diode Yn2 and the grid electrode of the second field effect transistor Qn2, and the connection point is recorded as a second driving voltage output point Vngs2; the other end of the second capacitor CTn2 and the second diode Yn2
The cathodes are connected to the synonym end of the second primary winding, namely, the second capacitor CTn2 and the second diode Yn2 are connected in parallel; preferably, the first diode Yn1 and the second diode Yn2 are both common-cathode dual diodes.
The first driving voltage output point Vngs1 is connected to the common end of the first voltage dividing resistor Rn1 and the second voltage dividing resistor Rn2 through the first current limiting resistor Rn3, the second driving voltage output point Vngs2 is connected to the common end of the first voltage dividing resistor Rn1 and the second voltage dividing resistor Rn2 through the second current limiting resistor Rn4, the initial voltage of the first driving voltage output point Vngs1 and the second driving voltage output point Vngs2 is the voltage of the common end of the first voltage dividing resistor Rn1 and the second voltage dividing resistor Rn2, the voltage theoretical value of the first driving voltage output point Vngs1 and the second driving voltage output point Vngs2 is the same, when the two are respectively applied to the grid electrode of the first field effect transistor Qn1 and the grid electrode of the second field effect transistor Qn2, in practical application, however, due to errors in parameters of components in the circuit system, for example, errors in actual resistance values of the first current limiting resistor Rn3 and the second current limiting resistor Rn4, errors in conduction threshold voltages of the first field effect transistor Qn1 and the second field effect transistor Qn2 are inevitable, and due to influences of production processes and influences of factors such as various interferences in the circuit, the first field effect transistor Qn1 and the second field effect transistor Qn2 are always conducted first in practical application.
Assuming that the first field effect transistor Qn1 is first turned on, the drain electrode of the first field effect transistor Qn1 is turned on to the cathode of the single battery 11; the second driving voltage output point Vngs2 is connected to the drain electrode of the first field effect transistor Qn1 through the second diode Yn2 in a forward conduction manner, and then follows the first field effect transistor Qn1 to be micro-conducted to the cathode of the single battery 11, so that the voltage of the second driving voltage output point Vngs2 is pulled down to be close to the cathode voltage of the single battery 11, and the second field effect transistor Qn2 is forced to enter a stable cut-off state; after the second field effect transistor Qn2 is turned off, the positive electrode of the single battery 11 is connected to the first driving voltage output point Vngs1 through the second primary winding and then through the first capacitor CTn1 to form positive feedback of the first driving voltage output point Vngs1, because the first capacitor CTn1 is electrified and instant to approximate a short circuit state, which is equivalent to that the positive electrode of the single battery 11 is connected to the first driving voltage output point Vngs1 to provide higher voltage for the first field effect transistor Qn1
The drive voltage and the larger junction capacitance charge current between the gate and source promote the first fet Qn1 to rapidly enter a fully conductive state from the initial micro-conductive state.
After the first field effect transistor Qn1 is completely turned on, the positive electrode of the unit cell 11 continuously charges the first capacitor CTn1 through the second primary winding, and as the voltage at two ends of the first capacitor CTn1 gradually increases, the voltage at the first driving voltage output point Vngs1 gradually decreases because the voltage at two ends of the first capacitor CTn1 and the first driving voltage output point Vngs1 are in a series connection relationship, until the voltage at the first driving voltage output point Vngs1 decreases to be lower than the turn-on threshold voltage of the first field effect transistor Qn1, and the first field effect transistor Qn1 enters the cut-off state. As the first field effect transistor Qn1 enters the off state, the voltage of the second driving voltage output point Vngs2 is restored to the voltage of the common terminal of the first voltage dividing resistor Rn1 and the second voltage dividing resistor Rn 2; the second field effect transistor Qn2 enters a micro-conduction state under the voltage action of a second driving voltage output point Vngs2, and the drain electrode of the second field effect transistor Qn2 is conducted to the cathode of the single battery 11 in a micro-conduction manner from source to source; the first driving voltage output point Vngs1 is connected to the drain electrode of the second field effect transistor Qn2 through the first diode Yn1 in a forward conduction manner, and then follows the second field effect transistor Qn2 to be micro-conducted to the cathode of the single battery 11, so that the voltage of the first driving voltage output point Vngs1 is pulled down to be close to the cathode voltage of the single battery 11, and the first field effect transistor Qn1 is forced to enter a stable cut-off state; after the first field effect transistor Qn1 is turned off, the positive electrode of the single battery 11 is connected to the second driving voltage output point Vngs2 through the first primary winding and then through the second capacitor CTn2, so that positive feedback of the second driving voltage output point Vngs2 is formed, and because the second capacitor CTn2 is in an approximate short circuit state at the moment of being electrified, the positive electrode of the single battery 11 is equivalent to the connection of the positive electrode of the single battery 11 to the second driving voltage output point Vngs2, higher driving voltage and larger junction capacitor charging current between the grid electrode and the source electrode are provided for the second field effect transistor Qn2, and the second field effect transistor Qn2 is promoted to rapidly enter a fully-conducted state from an initial micro-conduction state. Then the second fet Qn2 is turned off again, and the first fet Qn1 is turned on, thus repeating the cycle.
The first fet Qn1 and the second fet Qn2 are alternately turned on in such a manner that the synonym end of the first primary winding and the homonym end of the second primary winding of the transformer 21 are alternately turned on to the negative electrode of the corresponding unit cell 11 through the switching circuit 22.
When the synonym end of the first primary winding is conducted to the negative electrode of the corresponding single battery 11 through the switch circuit 22, the positive electrode of the single battery 11, the first primary winding and the negative electrode of the single battery 11 form a closed loop, and current passes through the first primary winding; when the same-name end of the second primary winding is conducted to the negative electrode of the corresponding single battery 11 through the switch circuit 22, the positive electrode of the single battery 11, the second primary winding and the negative electrode of the single battery 11 form a closed loop, and current passes through the second primary winding; an alternating magnetic flux is thus generated in the core of the transformer 21, and an induced voltage is correspondingly generated on the secondary winding of the transformer 21; the induced voltage on the secondary winding is proportional to the voltage on the primary winding, and because the voltage on the primary winding is the voltage of the single battery 11, the induced voltage on the secondary winding is proportional to the voltage of the single battery 11; in each voltage equalizing unit 20, the secondary winding of the transformer 21 has an induced voltage proportional to the voltage of each unit cell 11, and the larger the voltage of the unit cell 11 is, the larger the induced voltage of the secondary winding of the corresponding transformer 21 is.
Since the transformer 21 in each voltage equalizing unit 20 has the same structure, i.e., the turns ratio of the primary winding and the secondary winding of each transformer 21 is the same, and the winding directions of the corresponding windings are the same, when the voltages of the individual batteries 11 are equal, the induced voltages of the secondary windings of each transformer 21 are also equal, that is, when the secondary windings of each transformer 21 are connected in parallel, there is no voltage difference, so almost no loop current exists, that is, a low power consumption state is achieved.
When the voltage of each single battery 11 deviates to a certain extent, a higher induction voltage is induced on the secondary winding of the corresponding transformer 21 when the voltage of the single battery 11 is higher; when the secondary windings of the transformers 21 are connected in parallel, the secondary winding with high induced voltage transfers energy to the secondary winding with low induced voltage, so that an energy transfer current is generated; along with the increase of the energy on the secondary winding of the corresponding transformer 21 of the single battery 11 with lower voltage, the energy on the secondary winding is transferred to the primary winding of the corresponding transformer 21 again in an induction way, and then the single battery 11 with lower voltage is charged, so that the function of carrying out induction isolation type charging on the single battery 11 with lower voltage by the single battery 11 with higher voltage through the transformer 21 is realized.
The battery pack voltage equalization circuit based on the transformer provided by the embodiment of the invention is balanced by voltage
The two primary windings of the transformers in the unit are alternately conducted to the output ends of the single batteries, so that alternating magnetic flux is produced in the magnetic cores of the transformers, induced voltages which are proportional to the voltages of all the single batteries are generated on the secondary windings of the transformers, the secondary windings of all the transformers are connected in parallel, and the single batteries with lower voltages are charged through energy transfer on the secondary windings, so that the single batteries with high voltages are subjected to isolated lossless charging on the single batteries with low voltages. According to the voltage balancing circuit of the battery pack based on the transformer, provided by the embodiment of the invention, voltage balancing is automatically performed in real time according to the voltage difference of each single battery in the charging and discharging processes of the battery pack, so that the single battery with low voltage can be ensured to obtain isolated safe charging of other single batteries with higher voltage, and low-loss high-efficiency voltage balancing is realized.
Preferably, the switch circuit 22 further comprises a drive protection switch circuit 22; the driving protection switch circuit 22 comprises a third field effect transistor Qn3, a fourth field effect transistor Qn4 and a singlechip.
The drain electrode of the third field effect tube Qn3 is connected with the grid electrode of the first field effect tube Qn 1; the source electrode of the third field effect transistor Qn3 is connected to the negative electrode of the corresponding unit cell 11.
The drain electrode of the fourth field effect tube Qn4 is connected with the grid electrode of the second field effect tube Qn 2; the source electrode of the fourth fet Qn4 is connected to the negative electrode of the corresponding unit cell 11.
The grid electrode of the third field effect tube Qn3 and the grid electrode of the fourth field effect tube Qn4 are connected with the singlechip; the singlechip controls the third field effect transistor Qn3 and the fourth field effect transistor Qn4 to be switched on or off.
In specific implementation, each switch circuit 22 further includes a driving protection switch circuit 22, where the driving protection switch circuit 22 is configured to provide a driving protection closing signal to the first fet Qn1 and the second fet Qn2, so that the first fet Qn1 and the second fet Qn2 are always in a cut-off state; as shown in fig. 2, the driving protection switch circuit 22 includes a third fet Qn3, a fourth fet Qn4, and a single-chip microcomputer; the drain electrode of the third field effect tube Qn3 is connected with the grid electrode of the first field effect tube Qn 1; the source electrode of the third field effect transistor Qn3 is connected with the cathode of the corresponding single battery 11; the drain electrode of the fourth field effect tube Qn4 is connected with the grid electrode of the second field effect tube Qn 2; the source electrode of the fourth field effect tube Qn4 is connected with the cathode of the corresponding single battery 11; gate of third fet Qn3 and fourth fet Qn4
The grid electrodes are connected with the singlechip; the singlechip controls the on or off of the third field effect transistor Qn3 and the fourth field effect transistor Qn 4.
When the voltage equalization function of the battery pack 10 needs to be stopped, the single chip microcomputer outputs voltages higher than voltages required by the conduction of the grid electrode of the third field effect tube Qn3 and the grid electrode of the fourth field effect tube Qn4 to the grid electrode of the third field effect tube Qn3 and the grid electrode of the fourth field effect tube Qn4, so that the grid electrode of the third field effect tube Qn3 and the grid electrode of the fourth field effect tube Qn4 are in a conduction state, the grid electrode of the first field effect tube Qn1 and the grid electrode of the second field effect tube Qn2 are conducted to the negative electrode of the single battery 11, and the first field effect tube Qn1 and the second field effect tube Qn2 are in a cut-off state all the time, so that the voltage equalization function of the battery pack 10 is closed.
Preferably, each of the voltage equalization units 20 further includes a filter circuit; the filter circuit comprises a first filter capacitor Cn1, a second filter capacitor Cn2, a third filter capacitor Cn3, a filter inductor Ln1 and a third diode Dn1; the positive electrode of the third diode Dn1 is connected with the homonymous end of the first primary winding and the heteronymous end of the second primary winding, and the negative electrode of the third diode Dn1 is connected with the positive electrode of the corresponding single battery 11; the filter inductor Ln1 is connected in parallel with the third diode Dn1, and after the first filter capacitor Cn1 and the second filter capacitor Cn are connected in parallel, the filter inductor Ln1 is connected in series between one end of the filter inductor Ln1 and the negative electrode of the corresponding single battery 11; the third filter capacitor Cn3 is connected in series between the other end of the filter inductor Ln1 and the negative electrode of the corresponding unit cell 11.
In specific implementation, as shown in fig. 2, each voltage equalization unit 20 further includes a filter circuit, where the filter circuit includes a first filter capacitor Cn1, a second filter capacitor Cn2, a third filter capacitor Cn3, a filter inductor Ln1, and a third diode Dn1; the positive electrode of the third diode Dn1 is connected with the homonymous end of the first primary winding and the heteronymous end of the second primary winding, and the negative electrode of the third diode Dn1 is connected with the positive electrode of the corresponding single battery 11; the filter inductor Ln1 is connected in parallel with the third diode Dn1, and after the first filter capacitor Cn1 and the second filter capacitor are connected in parallel, the filter inductor Ln1 is connected in series between one end of the filter inductor Ln1 and the cathode of the corresponding single battery 11; the third filter capacitor Cn3 is connected in series between the other end of the filter inductor Ln1 and the negative electrode of the corresponding unit cell 11. Wherein the first filter capacitor Cn1 is used for high frequency filtering; the pi-type filter formed by the second filter capacitor Cn2, the third filter capacitor Cn3 and the filter inductor Ln1 plays a role in stabilizing
The function of the input and output voltage is fixed.
Preferably, the turns ratio of the secondary winding to the primary winding in each of the transformers 21 is 1 to 5:1. in specific implementation, the turns ratio of the secondary winding to the primary winding in each transformer 21 is 1 to 5:1, by setting the number of turns of the secondary winding of the transformer 21 to be more than that of the primary winding, the difference value of the induced voltages on the secondary windings is amplified, so that when the voltage difference of each single battery 11 is smaller, the single battery 11 with high voltage can transfer and charge the single battery 11 with low voltage; meanwhile, the voltage amplification coefficient is not too large, otherwise, on the premise of fixed energy induced by the transformer 21, the higher the transferred voltage is, the higher the voltage-resistant requirement on the device is, the smaller the transferred current is, which is equivalent to the smaller the balance current, and the energy balance of the battery pack 10 is not facilitated. Preferably, the turns ratio of the secondary winding to the primary winding in each of the transformers 21 is 3:1.
preferably, the transformer 21 is a transformer 21 wound by a nanocrystalline toroidal core. In specific implementation, the transformer 21 wound by the high-performance nanocrystalline annular magnetic core has excellent temperature characteristics and extremely high magnetic permeability, reduces low excitation power and copper loss and iron loss, thereby reducing loss in the energy transfer process and improving voltage balance efficiency.
Although terms such as a unit cell, a voltage equalizing unit, a transformer, a primary winding, a secondary winding, a turns ratio, a field effect transistor, a voltage dividing resistor, a current limiting resistor, a filter capacitor, a diode, etc. are more used herein, the possibility of using other terms is not excluded. These terms are used merely for convenience in describing and explaining the nature of the invention; they are to be interpreted as any additional limitation that is not inconsistent with the spirit of the present invention.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.
Claims (6)
1. The utility model provides a group battery voltage equalizer circuit based on transformer which characterized in that: the device comprises a battery pack and a voltage balancing module;
the battery pack comprises a plurality of single batteries connected in series;
the voltage equalization module comprises voltage equalization units with the same number as the single batteries; the voltage equalization units are connected with the single batteries in a one-to-one correspondence manner;
each voltage equalization unit comprises a transformer and a switching circuit;
the transformer comprises a first primary winding, a second primary winding and a secondary winding; the number of coil turns of the first primary winding and the second primary winding are the same; the winding directions of the coils of the first primary winding and the second primary winding are opposite;
the homonymous end of the first primary winding and the heteronymous end of the second primary winding are both connected to the positive electrode of the corresponding single battery;
the synonym end of the first primary winding and the synonym end of the second primary winding are alternately conducted to the cathodes of the corresponding single batteries through the switch circuit;
the secondary windings of the transformers in the voltage equalization units are connected in parallel;
the switching circuit comprises a first field effect transistor, a second field effect transistor and a field effect transistor driving circuit; the first field effect tube is connected in series between the synonym end of the first primary winding and the negative electrode of the corresponding single battery; the second field effect tube is connected in series between the homonymous end of the second primary winding and the negative electrode of the corresponding single battery; the field effect transistor driving circuit controls the first field effect transistor and the second field effect transistor to be alternately conducted;
the field effect transistor driving circuit comprises a first voltage dividing resistor, a second voltage dividing resistor, a first current limiting resistor, a second current limiting resistor, a first diode, a second diode, a first capacitor and a second capacitor;
the first voltage dividing resistor and the second voltage dividing resistor are connected in series between the first input power supply and the cathode of the single battery;
one end of the first current limiting resistor is connected to a common end of the first voltage dividing resistor and the second voltage dividing resistor; the other end of the first current limiting resistor is connected with one end of the first capacitor, the positive electrode of the first diode and the grid electrode of the first field effect tube; the other end of the first capacitor and the negative electrode of the first diode are connected to the same-name end of the first primary winding;
one end of the second current limiting resistor is connected to the common end of the first voltage dividing resistor and the second voltage dividing resistor; the other end of the second current limiting resistor is connected with one end of the second capacitor, the positive electrode of the second diode and the grid electrode of the second field effect transistor; the other end of the second capacitor and the negative electrode of the second diode are connected to the synonym end of the second primary winding.
2. The transformer-based battery voltage equalization circuit of claim 1 wherein: the first diode and the second diode are both common cathode double diodes.
3. The transformer-based battery voltage equalization circuit of claim 2, wherein: the switch circuit also comprises a drive protection switch circuit; the driving protection switch circuit comprises a third field effect transistor, a fourth field effect transistor and a singlechip;
the drain electrode of the third field effect transistor is connected with the grid electrode of the first field effect transistor; the source electrode of the third field effect tube is connected with the cathode of the corresponding single battery;
the drain electrode of the fourth field effect transistor is connected with the grid electrode of the second field effect transistor; the source electrode of the fourth field effect tube is connected with the cathode of the corresponding single battery;
the grid electrode of the third field effect tube and the grid electrode of the fourth field effect tube are connected with the singlechip; the singlechip controls the third field effect transistor and the fourth field effect transistor to be switched on or off.
4. The transformer-based battery voltage equalization circuit of claim 1 wherein: each voltage equalization unit further comprises a filter circuit; the filter circuit comprises a first filter capacitor, a second filter capacitor, a third filter capacitor, a filter inductor and a third diode; the anode of the third diode is connected with the same-name end of the first primary winding and the different-name end of the second primary winding, and the cathode of the third diode is connected with the anode of the corresponding single battery; the filter inductor is connected with the third diode in parallel, and after the first filter capacitor and the second filter capacitor are connected in parallel, the filter inductor is connected in series between one end of the filter inductor and the cathode of the corresponding single battery; the third filter capacitor is connected in series between the other end of the filter inductor and the negative electrode of the corresponding single battery.
5. The transformer-based battery voltage equalization circuit of claim 1 wherein: the turns ratio of the secondary winding to the primary winding in each transformer is 1-5: 1.
6. the transformer-based battery voltage equalization circuit of any of claims 1-5, wherein: the transformer is a transformer wound by a nanocrystalline annular magnetic core.
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| US20220416549A1 (en) * | 2019-03-21 | 2022-12-29 | Hefei Gotion High-Tech Power Energy Co., Ltd. | Active equalization circuit, battery management system, power source system, and electronic device |
| CN114006430B (en) * | 2021-10-26 | 2024-08-06 | 三一锂能有限公司 | Equalization circuit for battery system, battery management system, and working machine |
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| US20040217735A1 (en) * | 2001-05-08 | 2004-11-04 | Ehsan Chitsazan | Interleaved switching lead-acid battery equalizer |
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| KR20070119432A (en) * | 2006-06-15 | 2007-12-20 | 에스케이에너지 주식회사 | Charge equalization apparatus with parallel connection of primary windings of multiple transformers |
| CN101764421A (en) * | 2010-01-15 | 2010-06-30 | 中国科学院电工研究所 | Equalizing equipment for battery units of electric automobile |
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Denomination of invention: A Transformer based Voltage Balancing Circuit for Battery Pack Effective date of registration: 20231222 Granted publication date: 20230523 Pledgee: Bank of China Limited by Share Ltd. Xiamen branch Pledgor: XIAMEN CHIPSUN TECHNOLOGY Co.,Ltd. Registration number: Y2023110000543 |