Balanced charging and discharging circuit of battery pack

Abstract

The utility model discloses a balanced charging and discharging circuit of a battery pack, which belongs to the technical field of battery charging and comprises a plurality of batteries, a first transformer, a first switch, a second switch, a plurality of first bidirectional switches and a plurality of second bidirectional switches. The positive electrode of the battery pack is connected with the first end of a secondary winding of the first transformer, the second end of the secondary winding of the first transformer is connected with the drain electrode of the second switch, and the source electrode of the second switch is connected with the negative electrode of the battery pack. The positive electrode of each battery is connected with the first end of a primary winding of the first transformer through a first bidirectional switch, the second end of the primary winding of the first transformer is connected with the drain electrode of the first switch, and the negative electrode of each battery is connected with the source electrode of the first switch through a second bidirectional switch. According to the utility model, energy balance between single batteries in the battery pack can be realized.

Description

Technical Field

[0001] The utility model relates to the technical field of battery charging, and in particular to a balanced charging and discharging circuit of a battery pack. Background Art

[0002] With the development of the new energy industry, battery systems have been widely used in the fields of automobiles and energy storage. In order to increase battery capacity, multiple batteries are usually connected in series to form a battery pack. The number of single batteries in the battery pack is increasing. However, due to the differences in the self-discharge rate, internal resistance, temperature and other parameter characteristics between individual batteries during manufacturing and use, it is impossible to maintain consistency, resulting in some single batteries in the battery pack being overcharged and over-discharged during use. The inconsistency between individual batteries is becoming more and more obvious, resulting in a decrease in the overall performance of the battery pack and affecting the service life.

[0003] Therefore, achieving energy balance between individual cells in a battery pack and ensuring consistency between individual cells are important issues that need to be addressed in series battery packs. Utility Model Content

[0004] The utility model aims to provide a balanced charging and discharging circuit for a battery pack.

[0005] In order to achieve the above-mentioned purpose, the technical solution of the utility model is:

[0006] A balanced charge and discharge circuit for a battery pack comprises a plurality of batteries, a first transformer, a first switch, a second switch, a plurality of first bidirectional switches and a plurality of second bidirectional switches, wherein the plurality of batteries are connected in series in the same direction to form a battery pack, the positive electrode of the battery pack is connected to the first end of the secondary winding of the first transformer, the second end of the secondary winding of the first transformer is connected to the drain of the second switch, the source of the second switch is connected to the negative electrode of the battery pack, the positive electrode of each of the batteries is connected to the first end of the primary winding of the first transformer via a first bidirectional switch, the second end of the primary winding of the first transformer is connected to the drain of the first switch, and the negative electrode of each of the batteries is connected to the source of the first switch via a second bidirectional switch.

[0007] In a specific embodiment, the gates of the plurality of first bidirectional switches mentioned above are each connected to a secondary driving module, the secondary driving module includes a photocoupler, a first input end of the photocoupler is connected to a first voltage, a second input end of the photocoupler is connected to a microcontroller signal, a first output end of the photocoupler is connected to a second voltage, and a second output end of the photocoupler is connected to the gate of the first bidirectional switch.

[0008] In a specific embodiment, the gate of the first switch is connected to a primary drive module, and the primary drive module is an isolated drive module.

[0009] In a specific embodiment, the chip model of the primary side driver module is TLP155E.

[0010] In a specific embodiment, the first bidirectional switch includes two switches connected in reverse series.

[0011] In a specific embodiment, the second bidirectional switch includes two switches connected in reverse series.

[0012] In a specific embodiment, the above-mentioned balanced charge and discharge circuit of the battery pack further includes a voltage sampling module, which includes a third switch, a fourteenth resistor and a fifteenth resistor, wherein the first end of the fourteenth resistor is connected to the positive electrode of the battery, the second end of the fourteenth resistor is connected to the drain of the third switch, the source of the third switch is connected to the first end of the fifteenth resistor, and the second end of the fifteenth resistor is connected to the negative electrode of the battery pack.

[0013] In a specific embodiment, the above-mentioned balanced charge and discharge circuit of the battery pack further includes a first resistor, wherein a first end of the first resistor is connected to a source of the first switch, and a second end of the first resistor is connected to a plurality of the second bidirectional switches.

[0014] In a specific embodiment, the above-mentioned balanced charge and discharge circuit of a battery pack further includes a second resistor, a first end of the second resistor is connected to the source of the second switch, and a second end of the second resistor is connected to the negative electrode of the battery pack.

[0015] Beneficial effect: The utility model provides a balanced charge and discharge circuit for a battery pack, which can achieve energy balance between individual batteries in the battery pack during charging and discharging, ensure consistency between individual batteries, and improve the overall performance of the battery pack.

[0016] In order to make the above features and advantages of the utility model more obvious and easy to understand, embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The utility model is a circuit diagram of a balanced charging and discharging circuit of a battery pack.

[0018] Figure 2 for Figure 1 A schematic diagram of a specific embodiment of the invention is shown in FIG.

[0019] Figure 3 is a circuit diagram of the voltage sampling module 61 and the voltage sampling module 62 . DETAILED DESCRIPTION

[0020] In order to make the purpose and technical solution of the embodiment of the utility model clearer, the technical solution of the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings of the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all of the embodiments. Based on the described embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0021] Figure 1 The following is a circuit diagram of a balanced charging and discharging circuit of a battery pack according to the utility model. Figure 1 As shown, multiple batteries B1, B2 to BN are connected in series in the same direction, and the positive electrode of the series connection is the terminal V + , the negative terminal after series connection is terminal V - , the terminal V + The first end of the secondary winding of the transformer T1 is connected to the drain of the switch Q2, and the source of the switch Q2 is connected to the terminal V - The positive electrode of each battery is connected to the first end of the primary winding of the transformer T1 through a bidirectional switch, the second end of the primary winding of the transformer T1 is connected to the drain of the switch Q1, and the negative electrode of each battery is connected to the source of the switch Q1 through a bidirectional switch. The terminal V + With the terminal V - When connected to a charger, the battery pack can be charged; the terminal V + With the terminal V - When a load is connected, power can be supplied to the load.

[0022] More specifically, the positive electrode of the battery B1 is connected to the first end of the primary winding of the transformer T1 through the bidirectional switch 11, the positive electrode of the battery B2 is connected to the first end of the primary winding of the transformer T1 through the bidirectional switch 12, and so on, until the positive electrode of the battery BN is connected to the first end of the primary winding of the transformer T1 through the bidirectional switch 1N. The negative electrode of the battery B1 is connected to the source electrode of the switch Q1 through the bidirectional switch 21, the negative electrode of the battery B2 is connected to the source electrode of the switch Q1 through the bidirectional switch 22, and so on, until the negative electrode of the battery BN is connected to the source electrode of the switch Q1 through the bidirectional switch 2N.

[0023] Further, each bidirectional switch is connected to a secondary drive module, and the secondary drive module drives it to be turned on and off. More specifically, the gate of the bidirectional switch 11 is connected to the output of the secondary drive module 31, and the input connection signal P31 of the secondary drive module 31; the gate of the bidirectional switch 12 is connected to the output of the secondary drive module 32, and the input connection signal P32 of the secondary drive module 32, and so on, until the gate of the bidirectional switch 1N is connected to the output of the secondary drive module 3N, and the input connection signal P3N of the secondary drive module 3N. More specifically, the gate of the bidirectional switch 21 is connected to the output of the secondary drive module 41, and the input connection signal P41 of the secondary drive module 41; the gate of the bidirectional switch 22 is connected to the output of the secondary drive module 42, and the input connection signal P42 of the secondary drive module 42, and so on, until the gate of the bidirectional switch 2N is connected to the output of the secondary drive module 4N, and the input connection signal P4N of the secondary drive module 4N.

[0024] Furthermore, the gate of the switch Q1 is connected to the output of the primary driving module 5 , the input of the primary driving module 5 is connected to the signal P1 , and the gate of the switch Q2 is connected to the signal P2 .

[0025] Optionally, the signal P1, the signal P2, the signal P31, the signal P32, up to the signal P3N, the signal P41, the signal P42, up to the signal P4N are control signals output by a single chip microcomputer.

[0026] Furthermore, the voltage V1 of the positive electrode of battery B1, the voltage V2 of the positive electrode of battery B2, and the voltage V N Input to the microcontroller for control.

[0027] Figure 2 for Figure 1 FIG. 1 is a schematic diagram of a specific embodiment. In this specific embodiment, the number of single batteries in the battery pack is 2. Figure 2 As shown, battery B1 and battery B2 are connected in series in the same direction, and the positive terminal of the series connection is terminal V + , the negative terminal after series connection is terminal V - , the terminal V + The first end of the secondary winding of the transformer T1 is connected to the drain of the switch Q2, and the source of the switch Q2 is connected to the terminal V through the resistor R2. -, the gate of the switch Q2 is connected to the signal P2 through the resistor R4. The positive electrode of the battery B1 is connected to the first end of the primary winding of the transformer T1 through the bidirectional switch 11, the second end of the primary winding of the transformer T1 is connected to the drain of the switch Q1, the source of the switch Q1 is connected to the first end of the resistor R1, and the negative electrode of the battery B1 is connected to the second end of the resistor R1 through the bidirectional switch 21; the positive electrode of the battery B2 is connected to the first end of the primary winding of the transformer T1 through the bidirectional switch 12, and the negative electrode of the battery B2 is connected to the second end of the resistor R1 through the bidirectional switch 22.

[0028] More specifically, the bidirectional switch 11 includes two switches Q11 and Q12 connected in reverse series, the drain of the switch Q11 is connected to the first end of the primary winding of the transformer T1, the source of the switch Q11 is connected to the source of the switch Q12, and the drain of the switch Q12 is connected to the positive electrode of the battery B1; the bidirectional switch 12 includes two switches Q21 and Q22 connected in reverse series, the drain of the switch Q21 is connected to the first end of the primary winding of the transformer T1, the source of the switch Q21 is connected to the source of the switch Q22, and the drain of the switch Q22 is connected to the positive electrode of the battery B2.

[0029] More specifically, the bidirectional switch 21 includes two switches Q13 and Q14 connected in reverse series, the drain of the switch Q13 is connected to the second end of the resistor R1, the source of the switch Q13 is connected to the source of the switch Q14, and the drain of the switch Q14 is connected to the negative electrode of the battery B1; the bidirectional switch 22 includes two switches Q23 and Q24 connected in reverse series, the drain of the switch Q23 is connected to the second end of the resistor R1, the source of the switch Q23 is connected to the source of the switch Q24, and the drain of the switch Q24 is connected to the negative electrode of the battery B2.

[0030] In this specific embodiment, the secondary side driving module 31 includes a photocoupler OP1 and a resistor R10, the first input end of the photocoupler OP1 is connected to the voltage Vcc1, the second input end of the photocoupler OP1 is connected to the signal P31 through the resistor R10, the first output end of the photocoupler OP1 is connected to the voltage Vcc21, the second output end of the photocoupler OP1 is connected to the gates of the switch Q11 and the switch Q12, the first end of the resistor R6 is connected to the source of the switch Q11 and the switch Q12, and the second end of the resistor R6 is connected to the gates of the switch Q11 and the switch Q12.

[0031] In this specific embodiment, the secondary side driving module 41 includes a photocoupler OP2 and a resistor R11, the first input end of the photocoupler OP2 is connected to the voltage Vcc1, the second input end of the photocoupler OP2 is connected to the signal P41 through the resistor R11, the first output end of the photocoupler OP2 is connected to the voltage Vcc22, the second output end of the photocoupler OP2 is connected to the gates of the switch Q13 and the switch Q14, the first end of the resistor R7 is connected to the source of the switch Q13 and the switch Q14, and the second end of the resistor R7 is connected to the gates of the switch Q13 and the switch Q14.

[0032] In this specific embodiment, the secondary side driving module 32 includes a photocoupler OP3 and a resistor R12, the first input end of the photocoupler OP3 is connected to the voltage Vcc1, the second input end of the photocoupler OP3 is connected to the signal P32 through the resistor R12, the first output end of the photocoupler OP3 is connected to the voltage Vcc23, the second output end of the photocoupler OP3 is connected to the gates of the switch Q21 and the switch Q22, the first end of the resistor R8 is connected to the gates of the switch Q21 and the switch Q22, and the second end of the resistor R8 is connected to the gates of the switch Q21 and the switch Q22.

[0033] In this specific embodiment, the secondary side driving module 42 includes a photocoupler OP4 and a resistor R13, the first input end of the photocoupler OP4 is connected to the voltage Vcc1, the second input end of the photocoupler OP4 is connected to the signal P42 through the resistor R13, the first output end of the photocoupler OP4 is connected to the voltage Vcc24, the second output end of the photocoupler OP4 is connected to the gate of the switch Q23 and the switch Q24, the first end of the resistor R9 is connected to the gate of the switch Q23 and the switch Q24, and the second end of the resistor R9 is connected to the gate of the switch Q23 and the switch Q24.

[0034] Further, in this specific embodiment, the primary side driving module 5 is an isolation driving module, and the chip model of the primary side driving module 5 is TLP155E. The first input terminal of the primary side driving module 5 is connected to the voltage Vcc1, the second input terminal of the primary side driving module 5 is connected to the signal P1 through the resistor R5, the first output terminal of the primary side driving module 5 is connected to the voltage Vcc3, the second output terminal of the primary side driving module 5 is connected to the gate of the switch Q1 through the resistor R3, and the third output terminal of the primary side driving module 5 is connected to the second end of the resistor R1.

[0035] More specifically, Figure 2 The function of the bidirectional switch is to achieve bidirectional shutdown.

[0036] Optionally, the model of the single chip microcomputer is stm8s003f3p6 or other models that can realize corresponding functions.

[0037] Furthermore, the balanced charge and discharge circuit of a battery pack of the utility model further includes a voltage sampling module 61 and a voltage sampling module 62, such as Figure 3 As shown, the voltage sampling module 61 includes a resistor R14, a resistor R15 and a switch Q3, the first end of the resistor R14 is connected to the positive electrode of the battery B2, the second end of the resistor R15 is connected to the drain of the switch Q3, the source of the switch Q3 is connected to the first end of the resistor R15, and the second end of the resistor R15 is connected to the terminal V - , the gate of the switch Q3 is connected to the signal P3, and the first end of the resistor R15 outputs the signal AD1.

[0038] The signal P3 is generated by the single chip microcomputer; the signal AD1 represents the voltage across the battery B2 and is output to the single chip microcomputer.

[0039] The voltage sampling module 62 includes a resistor R16, a resistor R17 and a switch Q4. The first end of the resistor R16 is connected to the positive electrode of the battery B1, the second end of the resistor R16 is connected to the drain of the switch Q4, the source of the switch Q4 is connected to the first end of the resistor R17, and the second end of the resistor R17 is connected to the terminal V - , the gate of the switch Q4 is connected to the signal P4, and the first end of the resistor R17 outputs the signal AD2.

[0040] The signal P4 is generated by the microcontroller; the signal AD2 represents the voltage across the battery B1 and the battery B2 connected in series, and is output to the microcontroller. The voltage across the battery B1 can be obtained by subtracting the voltage represented by the signal AD1 from the voltage represented by the signal AD2.

[0041] Optionally, the signal P3 and the signal P4 may be at a high level all the time, and the voltage of each battery in the battery pack is sampled in real time; the signal P3 and the signal P4 may also be at a high level when necessary, and the voltage of each battery in the battery pack is sampled intermittently.

[0042] Optionally, the switch Q1, the switch Q2, the switch Q3, and the switch Q4 are MOSFETs.

[0043] Optionally, the switch Q11, the switch Q21, and even the switch QN1 are MOSFETs; the switch Q12, the switch Q22, and even the switch QN2 are MOSFETs; the switch Q13, the switch Q23, and even the switch QN3 are MOSFETs; and the switch Q14, the switch Q24, and even the switch QN4 are MOSFETs.

[0044] Next, continue to combine Figures 2 to 3 The utility model introduces the working principle of a balanced charging and discharging circuit of a battery pack. + With the terminal V - When the load is connected and the battery pack is discharged, if the voltage sampling module 61 and the voltage sampling module 62 detect that the power of the battery B1 and the battery B2 are unbalanced, for example, the voltage of the battery B2 is higher than the voltage of the battery B1, then the battery B2 needs to be discharged, and the single-chip microcomputer output signal P32 and the signal P42 are low level, the bidirectional switch 12 and the bidirectional switch 22 are turned on, and at the same time, the single-chip microcomputer output signal P1 causes the switch Q1 to be continuously turned on and off. At this time, the body diode of the switch Q2 is turned on, and the power of the battery B2 charges the entire battery pack through the transformer T1, thereby achieving balance between the battery B1 and the battery B2.

[0045] When the terminal V + With the terminal V - When the charger is connected to charge the battery pack, if the voltage sampling module 61 and the voltage sampling module 62 detect that the power of the battery B1 and the battery B2 are unbalanced, for example, the voltage of the battery B2 is higher than the voltage of the battery B1, and the battery B1 needs to be charged more, then the single-chip microcomputer output signal P31 and the signal P41 are low level, the bidirectional switch 11 and the bidirectional switch 21 are turned on, and at the same time, the single-chip microcomputer output signal P2 causes the switch Q2 to be continuously turned on and off. At this time, the body diode of the switch Q1 is turned on, and the external charger charges the battery B1 through the transformer T1, and also charges the entire battery pack, so that the current charging the battery B1 is larger, thereby achieving balance between the battery B1 and the battery B2.

[0046] Although the present invention has been disclosed as above by the embodiments, it is not intended to limit the present invention. Any person with ordinary knowledge in the technical field can make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the scope of the attached patent application.

Claims

1. A balanced charging and discharging circuit for a battery pack, characterized in that: It includes multiple batteries, a first transformer, a first switch, a second switch, multiple first bidirectional switches and multiple second bidirectional switches. Multiple batteries are connected in series in the same direction to form a battery group. The positive electrode of the battery group is connected to the first end of the secondary winding of the first transformer, the second end of the secondary winding of the first transformer is connected to the drain of the second switch, and the source of the second switch is connected to the negative electrode of the battery group. The positive electrode of each battery is connected to the first end of the primary winding of the first transformer through a first bidirectional switch, the second end of the primary winding of the first transformer is connected to the drain of the first switch, and the negative electrode of each battery is connected to the source of the first switch through a second bidirectional switch.

2. A balanced charge and discharge circuit for a battery pack as claimed in claim 1, characterized in that: The gates of the plurality of first bidirectional switches are each connected to a secondary driving module, the secondary driving module comprising a photocoupler, a first input end of the photocoupler being connected to a first voltage, a second input end of the photocoupler being connected to a single-chip computer signal, a first output end of the photocoupler being connected to a second voltage, and a second output end of the photocoupler being connected to the gate of the first bidirectional switch.

3. A balanced charge and discharge circuit for a battery pack as claimed in claim 2, characterized in that: The gate of the first switch is connected to a primary drive module, and the primary drive module is an isolated drive module.

4. A balanced charge and discharge circuit for a battery pack as claimed in claim 3, characterized in that: The chip model of the primary side driver module is TLP155E.

5. A balanced charge and discharge circuit for a battery pack as claimed in claim 1, characterized in that: The first bidirectional switch includes two switches connected in series in opposite directions.

6. A balanced charge and discharge circuit for a battery pack as claimed in claim 5, characterized in that: The second bidirectional switch includes two switches connected in series in opposite directions.

7. A balanced charge and discharge circuit for a battery pack as claimed in any one of claims 1 to 6, characterized in that: It also includes a voltage sampling module, which includes a third switch, a fourteenth resistor and a fifteenth resistor, the first end of the fourteenth resistor is connected to the positive electrode of the battery, the second end of the fourteenth resistor is connected to the drain of the third switch, the source of the third switch is connected to the first end of the fifteenth resistor, and the second end of the fifteenth resistor is connected to the negative electrode of the battery pack.

8. A balanced charge and discharge circuit for a battery pack as claimed in claim 7, characterized in that: It also includes a first resistor, a first end of the first resistor is connected to the source of the first switch, and a second end of the first resistor is connected to the plurality of second bidirectional switches.

9. A balanced charge and discharge circuit for a battery pack as claimed in claim 8, characterized in that: A second resistor is also included, wherein a first end of the second resistor is connected to the source of the second switch, and a second end of the second resistor is connected to the negative electrode of the battery pack.

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