Battery cell balance control circuit, battery management system and vehicle

Abstract

The utility model provides a cell equalization control circuit, a battery management system and a vehicle. The cell equalization control circuit comprises a passive equalization execution sub-circuit, an active equalization switch sub-circuit and a front-end analog chip. The passive equalization execution sub-circuit and the active equalization switch sub-circuit are connected with the battery module and the front-end analog chip, and the active equalization switch sub-circuit and the front-end analog chip are also connected with an external power supply; and after the front-end analog chip detects that the cell voltage of at least one target cell in the battery module is relatively low, the active equalization switch sub-circuit is controlled to be switched on, so that the charging current of an external power supply is led to the battery module, and the target cell is charged after passing through at least part of branch circuits in the passive equalization execution sub-circuit. The active and passive equalization combined control can be realized, the circuit structure is simple, the control cost is lower, the equalization control efficiency is effectively improved, the external power supply also avoids the problem that the unbalance of the battery core is easily aggravated because the front-end analog chip can only take power from the battery core, and the control stability is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of battery management, and in particular to a battery cell balancing control circuit, a battery management system and a vehicle. Background Art

[0002] In large-scale series and parallel applications of batteries, the consistency of battery cells will directly affect the overall application performance and life of the battery module. Therefore, the balanced control of battery cells in the battery module is particularly important.

[0003] In the related technology, two control methods, active balancing and passive balancing, are usually used. However, in both active and passive balancing methods, since the front-end analog chip can only draw power from the battery cell, it is easy to aggravate the imbalance of the battery cell due to inconsistent driving power consumption, resulting in poor stability of the control process. At the same time, it is difficult to achieve a balance between control efficiency and control cost with a simple active balancing method or passive balancing method. Utility Model Content

[0004] The utility model provides a battery cell balancing control circuit, a battery management system and a vehicle, which are used to solve the defects of a traditional balancing control method, that is, poor control process stability and difficulty in balancing control efficiency and control cost.

[0005] On the one hand, the utility model provides a cell balancing control circuit, including: a passive balancing execution subcircuit, an active balancing switch subcircuit and a front-end analog chip;

[0006] The passive balancing execution subcircuit and the active balancing switch subcircuit are both connected to the battery module and the front-end analog chip, and the active balancing switch subcircuit and the front-end analog chip are also both connected to an external power supply;

[0007] After detecting that the cell voltage of at least one target cell in the battery module is low, the front-end analog chip controls the active balancing switch subcircuit to turn on, so as to lead the charging current of the external power supply to the battery module, and charge the target cell after passing through at least part of the branch lines in the passive balancing execution subcircuit.

[0008] According to the cell balancing control circuit provided by the utility model, the active balancing switch subcircuit includes: a first triode, a second triode, a first resistor, a second resistor and a third resistor;

[0009] The first transistor is connected to the first end of the first resistor and the first end of the second resistor respectively, the emitter of the first transistor and the second end of the first resistor are both connected to the isolation transformer sub-circuit, the collector of the first transistor is connected to the battery module, the second end of the second resistor is connected to the collector of the second transistor, the base of the second transistor is connected to the front-end analog chip through the third resistor, and the emitter of the second transistor is grounded.

[0010] According to the battery cell balancing control circuit provided by the utility model, the external power supply is a low-voltage power supply end, and the circuit further includes an isolation transformer subcircuit;

[0011] The active balancing switch sub-circuit and the front-end analog chip are both connected to the isolation transformer sub-circuit, and the isolation transformer sub-circuit is connected to the low-voltage power supply end.

[0012] According to the cell balancing control circuit provided by the utility model, the isolation transformer subcircuit includes: a power management module and a voltage conversion module;

[0013] The power management module is connected to the low-voltage power supply end and the voltage conversion module respectively, and the voltage conversion module is connected to the front-end analog chip and the active balancing switch sub-circuit respectively.

[0014] According to the cell balancing control circuit provided by the utility model, the voltage conversion module includes: a transformer, a first diode, a first capacitor, a second capacitor, a fourth resistor, a fifth resistor and a voltage stabilizing diode;

[0015] The high-voltage side of the transformer is connected to the first diode and the first capacitor respectively, and the first diode and the first capacitor are both connected to the front-end analog chip and the active balancing switch sub-circuit;

[0016] The low-voltage side of the transformer is respectively connected to a series branch consisting of the second capacitor, the fourth resistor and the fifth resistor and the voltage regulator diode, and the series branch and the voltage regulator diode are also connected to the power management module.

[0017] According to the cell balancing control circuit provided by the utility model, the power management module includes: a power management chip, a second diode, a third capacitor, a fourth capacitor, a sixth resistor, a seventh resistor, an eighth resistor and a ninth resistor;

[0018] The first pin and the second pin of the power management chip are connected to the cathode of the second diode through the sixth resistor and the seventh resistor respectively, the cathode of the second diode is also grounded through the third capacitor, the anode of the second diode is connected to the anode of the low-voltage power supply end, the third pin of the power management chip is connected to the cathode of the low-voltage power supply end through the fourth capacitor, the fourth capacitor and the cathode of the low-voltage power supply end are both grounded, and the fourth pin and the fifth pin of the power management chip are connected to the ground through a parallel branch composed of the eighth resistor and the ninth resistor.

[0019] According to the battery cell balancing control circuit provided by the utility model, the circuit also includes an anti-reverse diode, the positive electrode of the anti-reverse diode is connected to the battery module, and the negative electrode of the anti-reverse diode is connected to the connection line between the front-end analog chip and the external power supply.

[0020] According to the battery cell balancing control circuit provided by the utility model, the circuit further includes: a shunt tube and an operational amplifier;

[0021] The shunt tube is connected to the line between the front-end analog chip and the negative electrode of the battery module, the first end of the shunt tube is connected to the in-phase input terminal of the operational amplifier, the second end of the shunt tube is connected to the inverting input terminal of the operational amplifier, and the output terminal of the operational amplifier is connected to the front-end analog chip.

[0022] On the other hand, the utility model further provides a battery management system, comprising any one of the above-mentioned battery cell balancing control circuits.

[0023] On the other hand, the utility model further provides a vehicle, comprising any one of the above-mentioned cell balancing control circuits or the above-mentioned battery management system.

[0024] The battery cell balancing control circuit, battery management system and vehicle provided by the utility model can realize the combined control of active balancing and passive balancing through the cooperation of the passive balancing execution sub-circuit, the active balancing switch sub-circuit and the front-end analog chip. Compared with the simple active balancing control scheme, the circuit structure is simpler and the control cost is lower. Compared with the simple passive balancing control scheme, the control efficiency is effectively improved. At the same time, an external power supply can be used to power the front-end analog chip, avoiding the situation that the front-end analog chip can only draw power from the battery cell, which easily aggravates the problem of battery cell imbalance, and improves the control stability of the battery cell balancing control process. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 This is one of the structural schematic diagrams of the cell balancing control circuit provided by the embodiment of the utility model;

[0027] Figure 2 This is the second structural schematic diagram of the cell balancing control circuit provided by the embodiment of the utility model;

[0028] Figure 3 It is a schematic diagram of the flow of charging current during the charging of some cells in a battery module in an embodiment of the utility model. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the utility model clearer, the technical solution of the utility model will be described clearly and completely in conjunction with the drawings in the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in 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.

[0030] This embodiment relates to the field of battery management, and can be specifically applied to the scenario of balancing control of cells in a battery module. In practical applications, the balancing control of cells mainly adopts two solutions: active balancing and passive balancing.

[0031] Among them, the passive balancing method mainly uses external circuit elements to discharge the battery cells, so that each battery cell in the battery module has the same charging capacity as the weakest battery cell. This control method has a simple circuit structure and is easy to implement, but the larger the battery cell capacity, the slower the balancing, and the control efficiency is difficult to guarantee.

[0032] The active balancing method is to periodically monitor the cell voltage of each cell in the battery module and transfer energy from the higher voltage cell to the lower voltage cell when necessary. This control method has higher balancing efficiency, but the circuit structure is complex and the control cost is high.

[0033] At the same time, no matter which of the above control schemes is adopted, during the control process, the front-end analog chip used for cell voltage collection and control can only draw power from the cell, which can easily aggravate the problem of cell imbalance due to inconsistent driving power consumption, and the control stability is poor.

[0034] Therefore, the traditional balanced control scheme has the problem of difficulty in achieving a balance between control efficiency and control cost, and poor control stability.

[0035] Based on this, this embodiment provides a solution to the above technical problem. Figures 1 to 3 The detailed scheme of the battery cell balancing control circuit, battery management system and vehicle provided by the embodiments of the utility model is described.

[0036] Figure 1 This is one of the structural schematic diagrams of the cell balancing control circuit provided in the embodiment of the utility model.

[0037] like Figure 1 As shown, the cell balancing control circuit provided by the embodiment of the utility model specifically includes: a passive balancing execution subcircuit 110 , an active balancing switch subcircuit 120 and a front-end analog chip 130 .

[0038] The passive balancing execution subcircuit 110 and the active balancing switch subcircuit 120 are both connected to the battery module and the front-end analog chip 130 . The active balancing switch subcircuit 120 and the front-end analog chip 130 are also both connected to an external power supply.

[0039] After detecting that the cell voltage of at least one target cell in the battery module is low, the front-end analog chip 130 controls the active balancing switch subcircuit 120 to turn on, so as to lead the charging current of the external power supply to the battery module, and charge the target cell after passing through at least part of the branch lines in the passive balancing execution subcircuit 110.

[0040] It can be understood that in this embodiment, the front-end analog chip 130 is connected to each battery cell in the battery module through each branch line in the passive balancing execution subcircuit 110, and the front-end analog chip 130 can collect the cell voltage of each battery cell in the battery module. At the same time, the front-end analog chip 130 can control the conduction state of each branch line in the passive balancing execution subcircuit 110 through the internal switching tube, thereby realizing targeted charging of at least one target battery cell in the battery module.

[0041] The front-end analog chip 130 can also control the connection and disconnection between the external power supply and the battery module by controlling the opening and closing of the active balancing switch subcircuit 120, thereby controlling the external power supply to charge the battery module. At the same time, since the front-end analog chip 130 is also directly connected to the external charging source, the external charging source can be used to power the front-end analog chip 130, thereby avoiding the problem of inconsistent driving power consumption and affecting the stability of battery cell balancing control due to relying solely on power from the battery cell.

[0042] The solution provided in this embodiment can realize the combined control of active balancing and passive balancing, so as to take into account both control efficiency and control cost. While using an external power supply to charge the battery module, it can also power the front-end analog chip, thereby improving control stability.

[0043] In one embodiment, see Figure 2 , the active balancing switch sub-circuit 120 includes: a first transistor Q1, a second transistor Q2, a first resistor R1, a second resistor R2 and a third resistor R3;

[0044] The first transistor Q1 is connected to the first end of the first resistor R1 and the first end of the second resistor R2 respectively, the emitter of the first transistor Q1 and the second end of the first resistor R1 are both connected to the isolation transformer sub-circuit, the collector of the first transistor Q1 is connected to the battery module, the second end of the second resistor R2 is connected to the collector of the second transistor Q2, the base of the second transistor Q2 is connected to the front-end analog chip 130 through the third resistor R3, and the emitter of the second transistor Q2 is grounded.

[0045] In one embodiment, see Figure 2 , the external power supply is a low-voltage power supply end, and the above-mentioned battery cell balancing control circuit also includes an isolation transformer subcircuit 140;

[0046] The active balancing switch sub-circuit 120 and the front-end analog chip 130 are both connected to the isolation transformer sub-circuit 140 , and the isolation transformer sub-circuit 140 is connected to the low-voltage power supply terminal.

[0047] In this embodiment, the low-voltage power supply end is specifically a low-voltage power supply on the battery management system side, which can be a 12V or 24V power supply. Specifically, the isolation transformer sub-circuit 140 can be connected to the low-voltage power supply through the main control chip U1 in the battery management system.

[0048] In practical applications, in order to use the low-voltage power supply end to power the front end and the analog chip 130 under normal circumstances, the output voltage of the isolation transformer subcircuit 140 needs to satisfy the following relationship:

[0049] V g =n×V CELLmax

[0050] Where n is the number of cells in the battery module, V CELLmax It is the maximum charging voltage of a single battery cell.

[0051] That is, when the output voltage V gWhen it is equal to the maximum battery pack voltage, the front-end analog chip 130 can be powered by the low-voltage power supply terminal. Otherwise, the front-end analog chip 130 can draw power from the battery cell, thereby realizing a dual power supply design of the front-end analog chip 130 and improving the stability of the balancing control link.

[0052] At the same time, by powering the front-end analog chip 130 through a low-voltage power supply end, a backup can be formed with the original power supply circuit, thereby avoiding the problem that the front-end analog chip 130 cannot report fault data after thermal runaway burns the battery power supply circuit.

[0053] In one embodiment, the isolation transformer sub-circuit 140 includes: a power management module and a voltage conversion module;

[0054] The power management module is connected to the low voltage power supply end and the voltage conversion module respectively, and the voltage conversion module is connected to the front-end analog chip and the active balancing switch sub-circuit respectively.

[0055] Further, see Figure 2 , the voltage conversion module specifically includes: a transformer T1, a first diode D1, a first capacitor C1, a second capacitor C2, a fourth resistor R4, a fifth resistor R5 and a voltage stabilizing diode D2;

[0056] The high voltage side of the transformer T1 is connected to the first diode D1 and the first capacitor C1 respectively, and the first diode D1 and the first capacitor C1 are both connected to the front-end analog chip 130 and the active balancing switch sub-circuit 120;

[0057] The low voltage side of the transformer T1 is respectively connected to a series branch consisting of a second capacitor C2, a fourth resistor R4 and a fifth resistor R5, and a voltage regulator diode D2. The series branch and the voltage regulator diode D2 are also connected to a power management module.

[0058] In one embodiment, see Figure 2 The power management module specifically includes: a power management chip U2, a second diode D3, a third capacitor C3, a fourth capacitor C4, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8 and a ninth resistor R9;

[0059] The first pin (i.e., the ENUVLO pin) and the second pin (i.e., the GND pin) of the power management chip U2 are respectively connected to the cathode of the second diode D3 through the sixth resistor R6 and the seventh resistor R7, the cathode of the second diode D3 is also grounded through the third capacitor C3, the anode of the second diode D3 is connected to the anode of the low-voltage power supply end, the third pin (i.e., the INTvcc pin) of the power management chip U2 is connected to the cathode of the low-voltage power supply end through the fourth capacitor C4, the fourth capacitor C4 and the cathode of the low-voltage power supply end are both grounded, the fourth pin (i.e., the Rref pin) and the fifth pin (i.e., the TC pin) of the power management chip U2 are connected to the ground end through a parallel branch composed of an eighth resistor R8 and a ninth resistor R9.

[0060] In one embodiment, see Figure 1 and Figure 2 The above-mentioned cell balancing control circuit may further include: an anti-reverse diode D4, wherein the positive electrode of the anti-reverse diode D4 is connected to the battery module, and the negative electrode of the anti-reverse diode D4 is connected to the connection line between the front-end analog chip 130 and the external power supply.

[0061] In this embodiment, the anti-reverse diode D4 can prevent the power supply current from being introduced into the battery module when the external power supply is supplying power to the front-end analog chip 130 .

[0062] In one embodiment, see Figure 2 , the above-mentioned cell balancing control circuit may further include: a shunt tube R10 and an operational amplifier U3;

[0063] The shunt tube R10 is connected to the line between the front-end analog chip 130 and the negative electrode of the battery module. The first end of the shunt tube R10 is connected to the non-inverting input terminal of the operational amplifier U3, the second end of the shunt tube R10 is connected to the inverting input terminal of the operational amplifier U3, and the output terminal of the operational amplifier U3 is connected to the front-end analog chip 130.

[0064] The current detection subcircuit composed of the shunt tube R10 and the operational amplifier U3 can monitor the current data in the line during power supply and balancing in real time, thereby providing effective data basis for power management and balancing control process.

[0065] like Figure 2 As shown, the line connecting the VPWER pin of the front-end analog chip 130 and the positive electrode of the battery module is also provided with auxiliary devices such as a resistor R11, a diode D5, a capacitor C5, a capacitor C6 and an inductor L1.

[0066] The CT0 to CTn+1 pins of the front-end analog chip 130 are respectively connected to each branch line in the passive balancing execution sub-circuit 110, and the circuit structure of each branch line is basically the same. Taking the branch line connected to the CTn+1 pin of the front-end analog chip 130 as an example, the branch line includes resistor R12, resistor R13, resistor R14, capacitor C7, capacitor C8 and inductor L2, wherein resistor R12 and resistor R13 are connected to the positive electrode of the battery module through inductor L2, capacitor C7 and capacitor C8 are both grounded, one end of resistor R14 is connected to one side of inductor L2, and the other end of resistor R14 is connected to the switch tube in the front-end analog chip 130, and the current flow direction of the branch line can be controlled by turning on and off the switch tube in the front-end analog chip 130.

[0067] Combine the following Figure 2 The working principle of the cell balancing control circuit provided in this embodiment is described in detail:

[0068] When the active balancing switch sub-circuit 120 needs to be turned on, the GPIO pin of the front-end analog chip 130 will output a high-level signal, and the voltage of the high-level signal is about 5V. The voltage of the high-level signal is greater than the turn-on voltage of the second transistor Q2, 0.7V, so that the second transistor is turned on, and the first resistor R1 and the second resistor R2 are grounded through the collector and emitter of the second transistor. At this time, the voltage difference across the first resistor R1 increases from 0V to greater than 1V, so that the pin voltage difference of the first transistor is less than -1V. At this time, the first transistor is turned on, so that the charging current is injected into the battery module through the emitter and the collector.

[0069] When the active balancing switch sub-circuit 120 needs to be turned off, the GPIO of the front-end analog chip 130 outputs a low-level signal, and the voltage of the low-level signal is approximately 0V. The voltage of the low-level signal is less than the turn-on voltage of the second transistor 0.7V, so that the second transistor is cut off and in a high-impedance state, and the second resistor R2 is equivalent to being suspended. The voltage difference across the first resistor R1 is approximately 0V, so that the pin voltage difference of the first transistor is approximately 0V. At this time, the first transistor is cut off, and the charging current cannot be injected into the battery module through the first transistor.

[0070] Figure 3 The example shows that when there are 5 battery cells in the battery module, when the front-end analog chip 130 detects that the battery voltages of the second battery cell V2 and the fifth battery cell V5 are low, the current flow for charging the second battery cell V2 and the fifth battery cell V5 is realized through some branch lines in the passive balancing execution sub-circuit 110. It is not difficult to see that the flow direction of the charging current can be controlled by controlling the on-off of the relevant switch tubes in the front-end analog chip 130, thereby charging the target battery cells with low voltage.

[0071] It can be understood that this embodiment only takes one battery module as an example to illustrate the cell balancing control process within the battery module. In actual applications, when multiple battery modules are connected in series, the cell balancing control schemes of each battery module are basically the same. A set of cell balancing control circuits provided in this embodiment can be configured for each battery module. The front-end analog chip in each cell balancing control circuit can transmit data with the main control chip in the battery management system through its own isolated communication interface.

[0072] In addition, this embodiment further provides a battery management system, which includes the battery cell balancing control circuit provided by the above embodiments.

[0073] In addition, this embodiment also provides a vehicle, which includes the battery cell balancing control circuit or the above-mentioned battery management system provided by the above-mentioned embodiments.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the utility model, rather than to limit it. Although the utility model has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the utility model.

Claims

1. A cell balancing control circuit, characterized in that: include: Passive equalization execution subcircuit, active equalization switch subcircuit and front-end analog chip; The passive balancing execution subcircuit and the active balancing switch subcircuit are both connected to the battery module and the front-end analog chip, and the active balancing switch subcircuit and the front-end analog chip are also both connected to an external power supply; After detecting that the cell voltage of at least one target cell in the battery module is low, the front-end analog chip controls the active balancing switch subcircuit to turn on, so as to lead the charging current of the external power supply to the battery module, and charge the target cell after passing through at least part of the branch lines in the passive balancing execution subcircuit.

2. The cell balancing control circuit according to claim 1, characterized in that: The active balancing switch subcircuit includes: a first triode, a second triode, a first resistor, a second resistor and a third resistor; The first transistor is connected to the first end of the first resistor and the first end of the second resistor respectively, the emitter of the first transistor and the second end of the first resistor are both connected to the isolation transformer sub-circuit, the collector of the first transistor is connected to the battery module, the second end of the second resistor is connected to the collector of the second transistor, the base of the second transistor is connected to the front-end analog chip through the third resistor, and the emitter of the second transistor is grounded.

3. The cell balancing control circuit according to claim 1, characterized in that: The external power supply is a low-voltage power supply terminal, and the circuit also includes an isolation transformer subcircuit; The active balancing switch sub-circuit and the front-end analog chip are both connected to the isolation transformer sub-circuit, and the isolation transformer sub-circuit is connected to the low-voltage power supply end.

4. The cell balancing control circuit according to claim 3, characterized in that: The isolation transformer subcircuit includes: a power management module and a voltage conversion module; The power management module is connected to the low-voltage power supply end and the voltage conversion module respectively, and the voltage conversion module is connected to the front-end analog chip and the active balancing switch sub-circuit respectively.

5. The cell balancing control circuit according to claim 4, characterized in that: The voltage conversion module includes: a transformer, a first diode, a first capacitor, a second capacitor, a fourth resistor, a fifth resistor and a voltage stabilizing diode; The high-voltage side of the transformer is connected to the first diode and the first capacitor respectively, and the first diode and the first capacitor are both connected to the front-end analog chip and the active balancing switch sub-circuit; The low-voltage side of the transformer is respectively connected to a series branch consisting of the second capacitor, the fourth resistor and the fifth resistor and the voltage regulator diode, and the series branch and the voltage regulator diode are also connected to the power management module.

6. The cell balancing control circuit according to claim 4, characterized in that: The power management module includes: a power management chip, a second diode, a third capacitor, a fourth capacitor, a sixth resistor, a seventh resistor, an eighth resistor and a ninth resistor; The first pin and the second pin of the power management chip are connected to the cathode of the second diode through the sixth resistor and the seventh resistor respectively, the cathode of the second diode is also grounded through the third capacitor, the anode of the second diode is connected to the anode of the low-voltage power supply end, the third pin of the power management chip is connected to the cathode of the low-voltage power supply end through the fourth capacitor, the fourth capacitor and the cathode of the low-voltage power supply end are both grounded, and the fourth pin and the fifth pin of the power management chip are connected to the ground through a parallel branch composed of the eighth resistor and the ninth resistor.

7. The cell balancing control circuit according to claim 1, characterized in that: The circuit also includes an anti-reverse diode, the positive electrode of the anti-reverse diode is connected to the battery module, and the negative electrode of the anti-reverse diode is connected to the connection line between the front-end analog chip and the external power supply.

8. The cell balancing control circuit according to claim 1, characterized in that: The circuit also includes: a shunt tube and an operational amplifier; The shunt tube is connected to the line between the front-end analog chip and the negative electrode of the battery module, the first end of the shunt tube is connected to the in-phase input terminal of the operational amplifier, the second end of the shunt tube is connected to the inverting input terminal of the operational amplifier, and the output terminal of the operational amplifier is connected to the front-end analog chip.

9. A battery management system, characterized in that: The invention comprises a cell balancing control circuit as claimed in any one of claims 1 to 8.

10. A vehicle, characterized in that: It comprises the cell balancing control circuit as claimed in any one of claims 1 to 8 or the battery management system as claimed in claim 9.

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