Battery protection circuit, battery system and control method thereof

Abstract

The present disclosure relates to a battery protection circuit, a battery system and a control method thereof, comprising: a plurality of first switching devices connected with a series battery pack; a first connection end of each first switching device is connected between the positive electrode of each cell and a resistance structure; a second connection end is connected between the negative electrode of each cell and the resistance structure; a balance discharge circuit is coupled between the two ends of each cell after being connected in series with the resistance structure, and whether to perform balance discharge on the coupled cell is determined according to the collected voltage of the coupled cell. The control signal of the control end of each first switching device is the voltage drop signal of part or all of the resistors in the resistance structure during balance discharge, which is used to drive the first switching device to be in a conducting state or to keep the first switching device in a cut-off state, and the first switching device in the conducting state forms an additional balance discharge path independent of the above balance discharge circuit. It can protect the cell and has the ability to enhance the discharge current.

Description

Technical Field

[0001] This disclosure relates to the field of battery management technology, and in particular to a battery protection circuit, a battery system and a control method thereof. Background Technology

[0002] Battery packs achieve higher output voltages by connecting multiple cells in series. As battery packs are increasingly used in various fields such as consumer electronics, transportation (e.g., electric bicycles, electric motorcycles, electric cars, or cars partially powered by electricity), and energy storage systems (e.g., grid-scale energy storage systems, backup power for communication base stations, and battery energy storage systems for portable medical devices), the requirements for battery pack charge / discharge performance and lifespan are also gradually increasing.

[0003] In realizing the concept disclosed herein, the inventors discovered at least the following technical problems in the related technology: In some scenarios, due to capacity mismatch and different aging levels between individual cells, the voltage difference between cells increases with prolonged use. This voltage difference leads to a decrease in the effective battery capacity. For example, during charging, the cell with the highest voltage triggers the overvoltage protection first, preventing the entire string of cells from charging and other cells from fully charging. During discharging, the cell with the lowest voltage triggers the overvoltage protection first, preventing the entire string of cells from discharging. In the worst-case scenario, the voltage difference between cells is so large that one cell in the battery pack has a voltage close to the overvoltage protection for discharging, while another cell has a voltage close to the overvoltage protection for charging. Such a battery pack cannot be effectively charged or discharged and must be scrapped prematurely. Furthermore, for some battery protection circuit structures, the current balancing discharge current is limited by the value of the protection resistor set in the circuit and the current carrying capacity of the built-in balancing discharge switch, resulting in limited balancing discharge protection capabilities during charging and discharging. Summary of the Invention

[0004] To solve the above-mentioned technical problems, or at least partially solve them, embodiments of this disclosure provide a battery protection circuit, a battery system, and a control method thereof.

[0005] In a first aspect, embodiments of the present disclosure provide a battery protection circuit, the battery protection circuit comprising: a plurality of first switching devices and a balancing discharge circuit;

[0006] The aforementioned plurality of first switching devices are used to connect to a series-connected battery pack; wherein a resistor structure is provided on the transmission line of at least one of the positive or negative terminals of each of the plurality of cells included in the series-connected battery pack, the resistor structure including one resistor or multiple resistors connected in series; a first connection terminal of each first switching device is used to connect between the positive terminal of each cell and the resistor structure; a second connection terminal of each first switching device is used to connect between the negative terminal of each cell and the resistor structure.

[0007] The above-mentioned balanced discharge circuit is used to connect in series with the above-mentioned resistor structure and then coupled to both ends of each cell. It determines whether to perform balanced discharge on the coupled cell based on the sampled voltage of the coupled cell.

[0008] The control signal at the control terminal of each first switching device is the voltage drop signal of part or all of the resistance in the above-mentioned resistor structure during balanced discharge. The voltage drop signal is used to drive the first switching device to be in the on state or to keep the first switching device in the off state. The first switching device in the on state forms an additional balanced discharge path independent of the above-mentioned balanced discharge circuit.

[0009] In some embodiments, the above-mentioned balanced discharge circuit is located inside the chip body and has a cell voltage detection function; the port of the above-mentioned balanced discharge circuit coupled to each cell has at least two port attributes at the same time: a power equalization discharge port attribute and a cell equalization voltage detection port attribute.

[0010] The aforementioned multiple first switching devices are located outside the aforementioned chip body;

[0011] The control terminal of each first switching device satisfies one of the following conditions:

[0012] The control terminal of the first switching device is currently coupled to the internal series circuit of the resistor structure in the corresponding battery cell; or,

[0013] The control terminal of the first switching device is currently coupled to the connection line between the resistor structure in the corresponding cell and the aforementioned balanced discharge circuit.

[0014] In some embodiments, for each first switching device, when the corresponding voltage drop signal is higher than the current first switching device's turn-on voltage threshold, the current first switching device is driven to turn on; when the corresponding voltage drop signal is less than the current first switching device's turn-on voltage threshold, the current first switching device remains off.

[0015] When at least one target cell is in a balanced discharge state, the first switching device connected to the target cell has one of the following states:

[0016] When the discharge current of the target battery cell is higher than a set value, the first switching device connected to it is in the first conducting state; or...

[0017] The discharge current of the target battery cell is less than the set value, and the first switching device connected to the target battery cell is in the second off state.

[0018] The first switching device mentioned above is one of the following two types: upper resistor driven type and lower resistor driven type;

[0019] For the first switching device driven by the upper resistor, the control signal of its control terminal comes from the first resistor structure on the transmission line of the positive electrode of the battery cell. The first resistor structure is located between the positive electrode of the battery cell and the balance discharge circuit.

[0020] For the first switching device driven by the lower resistor, the control signal at its control terminal comes from the second resistor structure on the transmission line of the negative electrode of the battery cell. The second resistor structure is located between the negative electrode of the battery cell and the balance discharge circuit.

[0021] In some embodiments, a first connection terminal of each first switching device is used to connect between the positive terminal of each battery cell and the resistive structure, and a second connection terminal of each first switching device is used to connect between the negative terminal of each battery cell and the resistive structure, including:

[0022] For each first switching device, one of the following situations exists:

[0023] The first and second connection terminals of the current first switching device are directly connected to the positive and negative terminals of the corresponding battery cells, respectively, forming a parallel connection between the current first switching device and the two ends of each battery cell; or,

[0024] An intermediate element is provided between the first connection terminal of the first switching device and the positive terminal of the corresponding battery cell, and the second connection terminal of the first switching device is directly connected to the negative terminal of the corresponding battery cell; or,

[0025] Currently, the first connection terminal of the first switching device is directly connected to the positive terminal of the corresponding battery cell, and an intermediate element is provided between the second connection terminal of the first switching device and the connection line of the corresponding battery cell; or,

[0026] An intermediate element is provided between the first connection terminal of the first switching device and the line connecting the positive terminal of the corresponding battery cell, and an intermediate element is provided between the second connection terminal of the first switching device and the line connecting the negative terminal of the corresponding battery cell.

[0027] The aforementioned first switching device driven by an upper resistor has at least one of the following structures:

[0028] A PMOS transistor, wherein the gate of the PMOS transistor is the control terminal, and the source and drain of the PMOS transistor are the conduction connection terminals; or,

[0029] The combination structure of PMOS transistor and first series resistor, wherein the first series resistor is connected in series with at least one of the source or drain of PMOS transistor;

[0030] A PNP bipolar transistor, wherein the base of the aforementioned PNP bipolar transistor is the control terminal, and the emitter and collector of the aforementioned PNP bipolar transistor are the conduction terminals; or...

[0031] The combination structure of a PNP bipolar transistor and a second series resistor, wherein the second series resistor is connected in series with at least one of the emitter or collector of the PNP bipolar transistor;

[0032] The aforementioned first switching device driven by a downstream resistor has at least one of the following structures:

[0033] An NMOS transistor, wherein the gate of the NMOS transistor is the control terminal, and the source and drain of the NMOS transistor are the conduction connection terminals; or,

[0034] The combination structure of NMOS transistor and third series resistor, wherein the third series resistor is connected in series with at least one of the source or drain of NMOS transistor;

[0035] An NPN bipolar transistor, wherein the base of the aforementioned NPN bipolar transistor is the control terminal, and the emitter and collector of the aforementioned NPN bipolar transistor are the conduction terminals; or,

[0036] The combination structure of an NPN bipolar transistor and a fourth series resistor, wherein the fourth series resistor is connected in series with at least one of the emitter or collector of the NPN bipolar transistor.

[0037] In some embodiments, the battery protection circuit further includes a resistor structure located on the transmission line of at least one of the positive or negative terminals of each of the plurality of cells in the series battery pack, and disposed outside the chip body.

[0038] In some embodiments, determining whether to perform a balancing discharge on the coupled cell based on the sampled voltage of the coupled cell includes: performing a balancing discharge on the coupled cell when the sampled voltage of the coupled cell is higher than the sampled voltage of other cells and the voltage difference exceeds the balance range.

[0039] The above-mentioned balanced discharge circuit includes:

[0040] Multiple second switching devices, each of which is connected in series with the resistive structure in each cell and then coupled to both ends of each cell;

[0041] A control circuit is coupled to both ends of each of the above-mentioned second switching devices and is used to acquire the voltage of the cell coupled to the disconnected second switching device when the second switching device is disconnected, and to determine whether to control at least one second switching device to conduct in order to perform balanced discharge on the coupled cell based on the acquired cell voltage.

[0042] The control circuit described above is used to control the second switching device coupled to the target cell to be turned on. When the voltage drop signal drives the first switching device to be in the on state, the target cell is balanced discharged based on the balanced discharge circuit and the additional balanced discharge path. When the voltage drop signal drives the first switching device to remain in the off state, the target cell is balanced discharged based on the balanced discharge circuit.

[0043] The target cell is one or more cells in the series battery pack whose voltage value is higher than that of other cells and whose voltage difference exceeds the balance range; or, the target cell is one or more cells in the series battery pack whose voltage is greater than the balance discharge threshold voltage, and at least one cell in the series battery pack has a voltage lower than the balance discharge threshold voltage.

[0044] In some embodiments, the plurality of second switching devices are connected in series, one end of the plurality of second switching devices connected in series is used to be coupled to the first end of the series battery pack and grounded, and the other end of the plurality of second switching devices connected in series is used to be coupled to the second end of the series battery pack.

[0045] The end of each second switching device that is furthest from ground is used to be coupled to the aforementioned resistor structure. In two adjacent second switching devices, the upper-level second switching device is connected in series with the resistor structure coupled to the upper-level second switching device and the resistor structure coupled to the lower-level second switching device, and then coupled to the two ends of the battery cell corresponding to the upper-level second switching device. Furthermore, when the control circuit acquires the voltage of at least one battery cell, the control circuit controls all of the aforementioned multiple second switching devices to be turned off.

[0046] In some embodiments, the control circuit includes:

[0047] At least two acquisition circuits or at least two comparison circuits, each of the acquisition circuits or each of the comparison circuits being coupled to both ends of one of the plurality of second switching devices, each of the acquisition circuits being used to acquire the voltage of the cell coupled to the second switching device when the second switching device is turned off, and each of the comparison circuits being used to acquire the voltage of the cell coupled to the second switching device when the second switching device is turned off, and to compare the voltage of the cell with a set value and output a comparison result;

[0048] The control logic is configured to output at least two first control signals, each of which characterizes whether it is necessary to disconnect the corresponding second switching device to acquire the voltage of the cell coupled to the corresponding second switching device; and the control logic is coupled to the output terminals of the at least two acquisition circuits or the at least two comparison circuits, and is configured to output at least two second control signals based on the output results of the at least two acquisition circuits or the at least two comparison circuits, each of which characterizes whether the voltage of the cell coupled to the corresponding second switching device is greater than the balance discharge threshold voltage;

[0049] A logic operation circuit is used to perform logical operations on at least one first control signal and at least one second control signal to output at least one control signal, each of the above control signals being used to control a corresponding second switching device to be turned off or on.

[0050] In some embodiments, each of the above-mentioned acquisition circuits or each of the above-mentioned comparison circuits also receives the first control signal, which is used to control whether the corresponding acquisition circuit or comparison circuit operates.

[0051] Wherein: when the first control signal is a first logic level, the corresponding first control signal is used to indicate that the corresponding second switching device needs to be disconnected in order to collect the voltage of the cell coupled to the corresponding second switching device. In addition, the corresponding first control signal is also used to control the corresponding acquisition circuit or comparison circuit to work.

[0052] When the first control signal is at the second logic level, the corresponding first control signal is used to indicate that it is not necessary to disconnect the corresponding switching device to collect the voltage of the cell coupled to the corresponding switching device. Furthermore, the corresponding first control signal is also used to control the corresponding acquisition circuit or comparison circuit to stop working.

[0053] The control circuit described above also includes a first inverter, wherein the lowest-level second switching device is grounded and is an NMOS transistor, the control terminal of which is coupled to the input terminal of the first inverter, the output terminal of the first inverter is used to receive the control signal sent by the control circuit, the highest-level switching device is a PMOS transistor, and the second switching device located at the non-end position of the series of multiple second switching devices is one of the following: an NMOS transistor, a PMOS transistor, or a combination of an NMOS transistor and a PMOS transistor.

[0054] In a second aspect, embodiments of this disclosure provide a battery system, including: a series-connected battery pack; and a battery protection circuit provided in the first aspect embodiment.

[0055] Thirdly, embodiments of this disclosure provide a battery protection control method, applied to the battery protection circuit provided in the first aspect embodiment or the battery system provided in the second aspect embodiment, the method comprising:

[0056] Voltage is collected for each cell in a series-connected battery pack.

[0057] The control of the balancing discharge circuit is determined based on the collected voltage of each cell to perform balancing discharge on the target cell. During the balancing discharge process, the voltage drop signal of part or all of the resistance in the resistor structure corresponding to the target cell during balancing discharge is used as the control signal of the first switching device to drive the first switching device to be in the conducting state or to keep the first switching device in the cut-off state. The first switching device in the conducting state forms an additional balancing discharge path independent of the above-mentioned balancing discharge circuit, so that the target cell can be balancing discharged together based on the discharge path corresponding to the above-mentioned balancing discharge circuit and the above-mentioned additional balancing discharge path.

[0058] The target cell is one or more cells in the series battery pack whose voltage is higher than that of other cells and whose voltage difference exceeds the balance range; or, the target cell is one or more cells in the series battery pack whose voltage is greater than the balance discharge threshold voltage, and at least one cell in the series battery pack has a voltage lower than the balance discharge threshold voltage.

[0059] The technical solutions provided in the embodiments of this disclosure have at least some or all of the following advantages:

[0060] By setting multiple first switching devices and a balancing discharge circuit, the balancing discharge circuit can collect voltage data from the coupled cells and perform balancing discharge control when an imbalance is detected between the cells during the charging or discharging phase. During the balancing discharge of one or more cells based on a resistive structure, the voltage drop signal of part or all of the resistance in the resistive structure during balancing discharge is used as a control signal. In some scenarios, the voltage drop signal drives the first switching devices to be in the conducting state. The first switching devices in the conducting state form an additional balancing discharge path independent of the aforementioned balancing discharge circuit. This additional balancing discharge path is independent of the discharge path corresponding to the balancing discharge circuit. The multiple discharge paths also effectively enhance the balancing discharge current. When the discharge current is large, it can be discharged quickly through multiple discharge paths, thus protecting the series battery pack. This effectively solves the problem in related technologies where the balancing discharge current is limited by the value of the protection resistor set in the circuit and the current carrying capacity of the built-in balancing discharge switch. Attached Figure Description

[0061] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure.

[0062] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0063] Figure 1 A schematic diagram of the structure of a battery protection circuit according to an embodiment of the present disclosure is shown.

[0064] Figure 2 A schematic diagram of the structure of a battery protection circuit according to another embodiment of the present disclosure is shown.

[0065] Figure 3 A schematic diagram of the structure of a battery protection circuit according to yet another embodiment of the present disclosure is shown.

[0066] Figure 4 A schematic diagram of the structure of a balanced discharge circuit according to an embodiment of the present disclosure is shown. Detailed Implementation

[0067] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0068] The first exemplary embodiment of this disclosure provides a battery protection circuit.

[0069] Figure 1 A schematic diagram of the structure of a battery protection circuit according to an embodiment of the present disclosure is shown.

[0070] Reference Figure 1 As shown, the battery protection circuit provided in this embodiment includes: a plurality of first switching devices 110 and a balanced discharge circuit 120.

[0071] The aforementioned plurality of first switching devices 110 are used for connection to a series-connected battery pack. For example, in Figure 1 The diagram uses a dashed rectangle to outline a series-connected battery pack, which includes multiple cells connected in series, designated as cell 1 to cell n. Figure 1The cells are respectively represented as BATTERY CELL(1), BATTERY CELL(2), ..., BATTERY CELL(n), where n ≥ 2 and is a positive integer. In the above-mentioned series-connected battery pack, at least one of the positive or negative terminals of each cell has a resistor structure on its transmission line. This resistor structure includes one or more resistors connected in series. For example, refer to... Figure 1 As shown, a resistor structure R(1) is provided on the transmission line of the positive terminal of cell 1; a resistor structure R(2) is provided on the transmission line of the positive terminal of cell 2, and the above-mentioned resistor structure R(1) is provided on the transmission line of the negative terminal of cell 2; ...; a resistor structure R(n) is provided on the transmission line of the positive terminal of cell n, and a resistor structure R(n-1) is provided on the transmission line of the negative terminal of cell n. Each resistor structure includes one resistor or multiple resistors connected in series, for example in... Figure 1 In the example, the resistor structure R(n-1) includes two resistors connected in series, while resistor structures R(1) and R(n) each contain one resistor.

[0072] The first connection terminal up of each first switching device 110 is used to connect between the positive terminal of each battery cell and the resistive structure; the second connection terminal dn of each first switching device is used to connect between the negative terminal of each battery cell and the resistive structure. For example, for battery cells 1 to n, the corresponding first switching devices are represented as SW1 to SWn, respectively. (Refer to...) Figure 1 As shown, the first connection terminal up of the first switching device SW1 is used to connect between the positive terminal of the corresponding cell 1 and the resistor structure R(1), and the second connection terminal dn of SW1 is used to connect between the negative terminal of the cell 1 and the resistor structure R(1). The first connection terminal up of the first switching device SW2 is used to connect between the positive terminal of the corresponding cell 2 and the resistor structure R(2), and the second connection terminal dn of SW2 is used to connect between the negative terminal of the cell 2 and the resistor structure R(1). Similarly, the first connection terminal up of the first switching device SWn is used to connect between the positive terminal of cell n and the resistor structure R(n), and the second connection terminal dn of SWn is used to connect between the negative terminal of cell n and the resistor structure R(n-1).

[0073] The aforementioned balanced discharge circuit 120 is used to connect in series with the aforementioned resistor structure R(1) to R(n) and then coupled to both ends of each cell. It determines whether to perform balanced discharge on the coupled cells based on the collected voltage of the coupled cells 1 to n.

[0074] The control signal of the control terminal ctr of each first switching device is the voltage drop signal of part or all of the resistance in the corresponding resistor structure during balanced discharge. The voltage drop signal is used to drive the first switching device to be in the on state or to keep the first switching device in the off state. The first switching device in the on state forms an additional balanced discharge path independent of the above-mentioned balanced discharge circuit.

[0075] Reference Figure 1 As shown, the control terminal ctr of each first switching device satisfies one of the following conditions:

[0076] The control terminal of the first switching device is currently coupled to the internal series circuit of the resistor structure in the corresponding battery cell; or,

[0077] The control terminal of the first switching device is currently coupled to the connection line between the resistor structure in the corresponding cell and the aforementioned balanced discharge circuit.

[0078] In one example scenario, refer to Figure 1 As shown, the control terminal ctr of the first switching device SWn-1 is coupled to the corresponding battery cell (specifically, battery cell n-1). Figure 1 (Not shown in the diagram) The internal series circuit of the resistor structure R(n-1) is connected to the control terminal ctr of SWn-1, which is coupled between the series circuit of the two resistors in the resistor structure R(n-1).

[0079] In another example, refer to Figure 1 As shown, the control terminal ctr of the first switching device SWn is coupled to the connection line between the resistor structure R(n-1) in the corresponding cell (specifically cell n) and the above-mentioned balanced discharge circuit 120.

[0080] In some embodiments, the first switching device is one of the following two types: SW_UP (upper resistor driven type) and SW_DN (lower resistor driven type).

[0081] For the first switching device of the resistor-driven SW_UP, the control signal of its control terminal comes from the first resistor structure on the transmission line of the positive electrode of the battery cell. The first resistor structure is located between the positive electrode of the battery cell and the balance discharge circuit.

[0082] For example, refer to Figure 1As shown, SW1 and SWn-1 are examples of first switching devices driven by an upper resistor. The control signal of the control terminal ctr of the first switching device SW1 comes from the first resistor structure R(1) between the positive terminal of cell 1 and the balance discharge circuit. For example, the control signal is the voltage drop signal corresponding to the first resistor structure R(1). The control signal of the control terminal ctr of the first switching device SWn-1 comes from the first resistor structure R(n-1) between the positive terminal of cell n-1 and the balance discharge circuit. For example, the control signal is the voltage drop signal corresponding to the left resistor of the two resistors connected in series in the first resistor structure R(n-1).

[0083] For the first switching device of the resistor-driven SW_DN, the control signal of its control terminal comes from the second resistor structure on the transmission line of the cell negative electrode. The second resistor structure is located between the cell negative electrode and the balance discharge circuit.

[0084] For example, refer to Figure 1 As shown, SW2 and SWn serve as examples of the first switching devices driven by a downstream resistor. The control signal of the control terminal ctr of the first switching device SW2 comes from the second resistor structure R(1) between the negative terminal of cell 1 and the balance discharge circuit (although R(1) is the same resistor structure, its specific location differs for different cells, thus corresponding to the first resistor structure and the second resistor structure respectively; similarly, it will not be explained further). For example, the control signal is the voltage drop signal corresponding to the second resistor structure R(1). The control signal of the control terminal ctr of the first switching device SWn comes from the second resistor structure R(n-1) between the negative terminal of cell n and the balance discharge circuit. For example, the control signal is the voltage drop signal corresponding to the two resistors connected in series in the second resistor structure R(n-1).

[0085] In the above embodiments, one method involves the first switching device being coupled to an internal series line between multiple resistors connected in series in the resistor structure; in this case, a portion of the voltage drop across the multiple series resistors serves as the driving force. Another method involves the first switching device being coupled to a connection line between the ends of the multiple series resistors in the resistor structure and the balanced discharge circuit 120; in this case, the entire voltage drop across one or more series resistors in the resistor structure serves as the driving force.

[0086] The above structural setup achieves at least some or all of the following effects:

[0087] Voltage stress dispersion: Since a single resistor is prone to breakdown or leakage when subjected to high voltage, it is connected in series so that each resistor shares the voltage.

[0088] More uniform heat dissipation: Due to the localized heat concentration of high-power resistors, thermal runaway can occur (the temperature coefficient affects the resistance value). By connecting multiple resistors in series, the temperature rise of individual components is reduced, the lifespan is extended, and resistance drift caused by heat concentration is avoided.

[0089] A specific proportion of voltage is extracted from the total voltage drop to trigger the switch, enabling gradient and fine-tuning of voltage drive settings.

[0090] It should be noted that the type of each first switching device can be one of the two types mentioned above, and there is no restriction on whether the types of the two first switching devices corresponding to adjacent cells are the same or different.

[0091] The aforementioned resistor-driven first switching device has at least one of the following structures:

[0092] A PMOS transistor, wherein the gate of the PMOS transistor is the control terminal, and the source and drain of the PMOS transistor are the conduction connection terminals; or,

[0093] The combination structure of PMOS transistor and first series resistor, wherein the first series resistor is connected in series with at least one of the source or drain of PMOS transistor;

[0094] A PNP bipolar transistor, wherein the base of the aforementioned PNP bipolar transistor is the control terminal, and the emitter and collector of the aforementioned PNP bipolar transistor are the conduction terminals; or...

[0095] The combination structure of a PNP bipolar transistor and a second series resistor, wherein the second series resistor is connected in series with at least one of the emitter or collector of the PNP bipolar transistor;

[0096] The aforementioned first switching device driven by a downstream resistor has at least one of the following structures:

[0097] An NMOS transistor, wherein the gate of the NMOS transistor is the control terminal, and the source and drain of the NMOS transistor are the conduction connection terminals; or,

[0098] The combination structure of NMOS transistor and third series resistor, wherein the third series resistor is connected in series with at least one of the source or drain of NMOS transistor;

[0099] An NPN bipolar transistor, wherein the base of the aforementioned NPN bipolar transistor is the control terminal, and the emitter and collector of the aforementioned NPN bipolar transistor are the conduction terminals; or,

[0100] The combination structure of an NPN bipolar transistor and a fourth series resistor, wherein the fourth series resistor is connected in series with at least one of the emitter or collector of the NPN bipolar transistor.

[0101] In some embodiments, by setting a combination structure corresponding to transistors and series resistors (e.g., first series resistors to fourth series resistors), the controllability of current enhancement can be improved based on the setting of series resistors, thereby achieving more refined regulation, while enhancing the balanced discharge current.

[0102] In some embodiments, in the above-described balancing discharge circuit 120, determining whether to perform balancing discharge on the coupled cell based on the sampled voltage of the coupled cell includes: performing balancing discharge on the coupled cell when the sampled voltage of the coupled cell is higher than the sampled voltage of other cells and the voltage difference exceeds the balancing range.

[0103] In the above embodiments, for each first switching device, when the corresponding voltage drop signal is higher than the current first switching device's turn-on voltage threshold, the current first switching device is driven to turn on; when the corresponding voltage drop signal is less than the current first switching device's turn-on voltage threshold, the current first switching device remains off.

[0104] When at least one target cell is in a balanced discharge state, the first switching device connected to the target cell has one of the following states:

[0105] When the discharge current of the target battery cell is higher than a set value, the first switching device connected to it is in the first conducting state; or...

[0106] The discharge current of the target battery cell is less than the set value, and the first switching device connected to the target battery cell is in the second off state.

[0107] It is understandable that for the same target cell in a balanced discharge state, the state of the first switching device may vary at different times, sometimes being in the on state (first state) and sometimes in the off state (second state). Furthermore, for the same target cell in a balanced discharge state, the voltage drop signal generated by the discharge current may also drive the corresponding first switching device to remain in the on state.

[0108] In a series-connected battery pack where the voltages of multiple cells are unbalanced, the voltage difference between the cells in the pack can be reduced and the imbalance eliminated by appropriately discharging the cells with higher voltages. Furthermore, this process does not prevent any single cell in the series-connected battery pack from charging or discharging.

[0109] Since the placement of the first switching device and the resistance values ​​of one or more resistors connected in series in the resistor structure can be optimized through simulation during circuit design, in most scenarios, the voltage drop signal of the corresponding resistor structure can drive the first switching device to conduct when the balance discharge circuit is turned on to balance discharge the relatively high voltage cells. This adds an extra balance discharge path, enhances the balance discharge current, achieves rapid discharge, and protects the series battery pack.

[0110] In the aforementioned battery protection circuit, by setting multiple first switching devices and a balancing discharge circuit, the balancing discharge circuit can collect voltage data from the coupled cells and perform balancing discharge control when an imbalance between cells is detected during the charging or discharging phase. During the balancing discharge process of one or more cells based on a resistive structure, the voltage drop signal of part or all of the resistance in the resistive structure during balancing discharge is used as a control signal. In some scenarios (e.g., during certain phases of battery protection circuit use, when the discharge current flowing into the balancing discharge circuit from a target cell is large, the voltage drop signal corresponding to the resistive structure is higher than the turn-on voltage threshold of the first switching device, driving the first switching device to be in a conducting state; or, during various phases of battery protection circuit use...), the balancing discharge circuit can... In a target battery cell, the voltage drop signal corresponding to the resistive structure is always greater than the threshold voltage of the first switching device, and it can always be in the conducting state under the driving action of the voltage drop signal. The voltage drop signal is used to drive the first switching device to be in the conducting state. The first switching device in the conducting state forms an additional balanced discharge path independent of the above-mentioned balanced discharge circuit. This additional balanced discharge path is independent of the discharge path corresponding to the balanced discharge circuit. Multiple discharge paths also effectively enhance the balanced discharge current. When the discharge current is large, it can be discharged quickly through multiple discharge paths, thus protecting the series-connected battery cell. This effectively solves the problem in related technologies where the balanced discharge current is limited by the value of the protection resistor set in the circuit and the current carrying capacity of the built-in balanced discharge switch. In addition, as the battery pack is used, when the overall cell voltage drops to a correspondingly small discharge current, during the balanced discharge process, the same first switching device may be in the conducting state initially under the driving action of the voltage drop signal, but later the voltage drop signal is insufficient to drive the first switching device to conduct. That is, there is the aforementioned voltage drop signal that keeps the first switching device in the off state. In this scenario, because the discharge current is small, the corresponding battery cell protection can be achieved only through the discharge path corresponding to the balanced discharge circuit. Overall, it can achieve the following functions: overcharge protection, overcurrent / short circuit protection, and over-discharge protection.

[0111] In some embodiments, refer to Figure 1As shown, the vertical dashed line represents the boundary between the inside and outside of the chip body; the aforementioned balanced discharge circuit 120 is located inside the chip body, while the aforementioned plurality of first switching devices 110 are located outside the chip body.

[0112] The balanced discharge circuit 120 has a cell voltage detection function; the port of the balanced discharge circuit coupled to each cell has at least two port attributes: a balanced discharge port attribute and a cell balanced voltage detection port attribute.

[0113] By incorporating cell voltage detection into the balanced discharge circuit, the equalization discharge port and the equalization voltage detection port in the balanced discharge circuit are combined into one, which can effectively save circuit pins and achieve efficient utilization of circuit area.

[0114] In some embodiments, refer to Figure 1 As shown, the resistor structure is also located outside the chip body. For example, the resistor structure is coupled to the chip body as part of the peripheral circuit, which facilitates heat dissipation outside the chip body and avoids adverse effects on the chip body during the balanced discharge process.

[0115] In some application scenarios, the above-mentioned balanced discharge circuit 120 can also have more port attributes. For example, in addition to having the two attributes mentioned above, it can also have at least one of the following two attributes: cell charging overvoltage protection threshold detection port attribute and cell discharging overvoltage protection threshold detection port attribute.

[0116] In some embodiments, a first connection terminal of each first switching device is used to connect between the positive terminal of each battery cell and the resistive structure, and a second connection terminal of each first switching device is used to connect between the negative terminal of each battery cell and the resistive structure, including:

[0117] For each first switching device, one of the following situations exists:

[0118] The first and second connection terminals of the current first switching device are directly connected to the positive and negative terminals of the corresponding battery cells, respectively, forming a parallel connection between the current first switching device and the two ends of each battery cell; for example... Figure 1 The indicated situation; or,

[0119] An intermediate element is provided between the first connection terminal of the first switching device and the positive terminal of the corresponding battery cell, and the second connection terminal of the first switching device is directly connected to the negative terminal of the corresponding battery cell; or,

[0120] Currently, the first connection terminal of the first switching device is directly connected to the positive terminal of the corresponding battery cell, and an intermediate element is provided between the second connection terminal of the first switching device and the connection line of the corresponding battery cell; or,

[0121] An intermediate element is provided between the first connection terminal of the first switching device and the line connecting the positive terminal of the corresponding battery cell, and an intermediate element is provided between the second connection terminal of the first switching device and the line connecting the negative terminal of the corresponding battery cell.

[0122] Figure 2 A schematic diagram of the structure of a battery protection circuit according to another embodiment of the present disclosure is shown.

[0123] Reference Figure 2 As shown, in some other embodiments, in addition to including multiple first switching devices 110 and a balanced discharge circuit 120, the battery protection circuit may also include multiple capacitors C(1), C(2)...C(n-1), C(n), one end of each capacitor is coupled to a resistor structure and the other end is grounded.

[0124] For example, in the example structure, one end of the capacitor is coupled between a resistor structure on the transmission line of the corresponding cell's positive terminal and a balanced discharge circuit.

[0125] For example, one end of C(1) is coupled to one end of R(1), and the other end is grounded; one end of C(2) is coupled to one end of R(2), and the other end is grounded; one end of C(n-1) is coupled to one end of R(n-1), and the other end is grounded; one end of C(n) is coupled to one end of R(n), and the other end is grounded.

[0126] Figure 3 A schematic diagram of the structure of a battery protection circuit according to yet another embodiment of the present disclosure is shown.

[0127] Reference Figure 3 As shown, the above-mentioned balanced discharge circuit 120 includes: a plurality of second switching devices 121 and a control circuit.

[0128] In the plurality of second switching devices 121, each second switching device is used to be connected in series with the resistive structure in each cell and then coupled to both ends of each cell. For example, refer to Figure 3 As shown, the second switching devices coupled to cells 1 to n are illustrated: MN(1), MP(2), MP(3), ..., MP(n).

[0129] The control circuit is coupled to both ends of each of the above-mentioned second switching devices 121, and is used to collect the voltage of the cell coupled to the disconnected second switching device when the second switching device is disconnected, and determine whether to control at least one second switching device to conduct in order to perform balanced discharge on the coupled cell based on the collected cell voltage.

[0130] The control circuit is used to control the second switching device 121 coupled to the target cell to be turned on. When the voltage drop signal drives the first switching device 110 to be in the on state, the target cell is balanced discharged based on the balanced discharge circuit and the additional balanced discharge path. When the voltage drop signal drives the first switching device to remain in the off state, the target cell is balanced discharged based on the balanced discharge circuit.

[0131] The target cell is one or more cells in the series battery pack whose voltage value is higher than that of other cells and whose voltage difference exceeds the balance range; or, the target cell is one or more cells in the series battery pack whose voltage is greater than the balance discharge threshold voltage, and at least one cell in the series battery pack has a voltage lower than the balance discharge threshold voltage.

[0132] The voltage of multiple battery cells is in a balanced state, which corresponds to the following situation: when the voltage difference between multiple battery cells is within the balance range (the specific value range can be set according to actual needs), it can be regarded as the voltage of multiple battery cells being in a balanced state; this includes the cases where the voltage difference is equal to zero and non-zero.

[0133] For example, refer to Figure 3 As shown, during the charging or discharging process of cells 1 to n, the voltages of cells 1 to n, obtained by the control circuit, are V1 to Vn, respectively. Cell n's voltage Vn is higher than the voltages of the other cells, and the voltage difference exceeds the equilibrium range. Therefore, cell n is the target cell, and the control circuit controls the second switching device MP(n) coupled to cell n to conduct. (Refer to...) Figure 3 As indicated by the dashed single arrow corresponding to serial number ①, the discharge path originates from the positive terminal of cell n, passes sequentially through resistor structures R(n), MP(n), and R(n-1), and then returns to the negative terminal of cell n, forming a balanced discharge path for cell n. Simultaneously, since the control signal for the first switching device SWn is the voltage drop signal of R(n-1), when this voltage drop signal exceeds the turn-on threshold of SWn, it can drive the first switching device SWn to conduct, for example, referring to... Figure 3 As shown by the dashed double arrow corresponding to serial number ②, the discharge path originates from the positive terminal of cell n, passes through the first switching device SWn, and returns to the negative terminal of cell n, forming another additional balanced discharge path for cell n. This additional balanced discharge path is independent of the discharge path corresponding to the balanced discharge circuit. The multiple discharge paths effectively enhance the balanced discharge current, enabling rapid discharge when the discharge current is large, thus protecting the series-connected battery pack. This effectively solves the problem in related technologies where the balanced discharge current is limited by the value of the protective resistor set in the circuit and the current carrying capacity of the built-in balanced discharge switch.

[0134] Furthermore, as the overall cell voltage drops to a relatively small level during battery pack use, the same first switching device (e.g., the first switching device SWn in the example above) may be in a conducting state initially driven by the voltage drop signal, but later the voltage drop signal may be insufficient to drive the first switching device to conduct. In other words, the voltage drop signal may cause the first switching device to remain in a cut-off state. In this scenario, since the discharge current is small, the corresponding cell protection can be achieved through the discharge path corresponding to the balanced discharge circuit.

[0135] In some embodiments, the plurality of second switching devices are connected in series, one end of the plurality of second switching devices connected in series is used to be coupled to the first end of the series battery pack and grounded, and the other end of the plurality of second switching devices connected in series is used to be coupled to the second end of the series battery pack.

[0136] The end of each second switching device that is furthest from ground is used to be coupled to the aforementioned resistor structure. In two adjacent second switching devices, the upper-level second switching device is connected in series with the resistor structure coupled to the upper-level second switching device and the resistor structure coupled to the lower-level second switching device, and then coupled to the two ends of the battery cell corresponding to the upper-level second switching device. Furthermore, when the control circuit acquires the voltage of at least one battery cell, the control circuit controls all of the aforementioned multiple second switching devices to be turned off.

[0137] In some embodiments, the control circuit includes: at least two acquisition circuits or at least two comparison circuits, control logic, and logic operation circuit.

[0138] Each of the above-mentioned acquisition circuits or each of the above-mentioned comparison circuits is coupled to both ends of one of the above-mentioned plurality of second switching devices. Each of the above-mentioned acquisition circuits is used to acquire the voltage of the cell coupled to the second switching device when the second switching device is turned off. Each of the above-mentioned comparison circuits is used to acquire the voltage of the cell coupled to the second switching device when the second switching device is turned off, and compare the voltage of the cell with a set value and output the comparison result.

[0139] The control logic is configured to output at least two first control signals, each of which characterizes whether it is necessary to disconnect the corresponding second switching device to acquire the voltage of the cell coupled to the corresponding second switching device; and the control logic is coupled to the output terminals of the at least two acquisition circuits or the at least two comparison circuits, and is configured to output at least two second control signals based on the output results of the at least two acquisition circuits or the at least two comparison circuits, each of which characterizes whether the voltage of the cell coupled to the corresponding second switching device is greater than the balance discharge threshold voltage.

[0140] A logic operation circuit is used to perform logical operations on at least one first control signal and at least one second control signal to output at least one control signal, each of which controls a corresponding second switching device to be turned off or on. The logic operation circuit may include a first OR gate OR1 and at least two second OR gates such as OR21, OR22...OR2n.

[0141] Since the control circuit, such as the acquisition circuit or the comparison circuit, is coupled to both ends of each second switching device, and at least two second switching devices, such as MN(1), MP(2)...MP(n), are connected in series, the closing of the second switching device will affect the voltage detection result of the battery cell. Therefore, in order to ensure the accuracy of the voltage detection result of the battery cell, the second switching device needs to be disconnected when performing voltage detection.

[0142] Multiple second switching devices have the following characteristics:

[0143] The first scenario involves at least two switching devices not connected in series. The upper-level second switching device, such as MP(2), is connected in series with the resistor structure R(2) coupled to the upper-level second switching device, but not with the resistor structure R(1) coupled to the lower-level second switching device, such as MN(1). For example, R1 is connected in series with MN1 and can be coupled between the two ends of the cell (1); R2 is connected in series with MP2 and can be coupled between the two ends of the cell (2). Since R1 is not connected in series with R2 and MP2, when collecting the voltage of the cell, only the second switching device corresponding to the cell whose voltage needs to be collected needs to be disconnected.

[0144] The second scenario involves at least two switching devices connected in series. The upper-level second switching device, such as MP(2), is coupled to a resistor structure, such as R(2), and the lower-level second switching device, such as MN(1), is coupled to a resistor structure, such as R(1), in series. For example, MP2 (upper-level) is connected in series with R2 (upper-level) and R1 (lower-level) and can be coupled between the two ends of the cell (2). Since the closing of other second switching devices will also affect the detection result of the cell that needs to be detected, all second switching devices will be turned off as long as one cell needs to be detected.

[0145] In some embodiments, when the cell voltage of the target cell is higher than the balance discharge threshold voltage, the second switching device corresponding to the target cell needs to be turned on to perform balance discharge; however, when the voltage of all cells is higher than the balance threshold voltage, all cells may no longer perform balance discharge, and all second switching devices are turned off.

[0146] In some embodiments, each of the above-mentioned acquisition circuits or each of the above-mentioned comparison circuits further receives the above-mentioned first control signal, which is used to control whether the corresponding acquisition circuit or comparison circuit operates.

[0147] Wherein: when the first control signal is at the first logic level, the corresponding first control signal is used to indicate that the corresponding second switching device needs to be disconnected in order to acquire the voltage of the cell coupled to the corresponding second switching device, and the corresponding first control signal is also used to control the corresponding acquisition circuit or comparison circuit to work.

[0148] When the first control signal is at the second logic level, the corresponding first control signal is used to indicate that it is not necessary to disconnect the corresponding switching device to acquire the voltage of the cell coupled to the corresponding switching device. Furthermore, the corresponding first control signal is also used to control the corresponding acquisition circuit or comparison circuit to stop working.

[0149] For example, refer to Figure 3 As shown, the acquisition circuit or comparison circuit can be coupled one-to-one with the second switching device. The control logic is used to output at least two first control signals CELL_SCAN(n), which characterize whether the corresponding second switching device needs to be disconnected to acquire the voltage of the cell coupled to the corresponding second switching device; and the control logic is coupled to the output terminals of at least two acquisition circuits or at least two comparison circuits, and is used to output at least two second control signals BAL_DET(n) according to the output results of at least two acquisition circuits or at least two comparison circuits, which characterize whether the voltage of the cell coupled to the corresponding second switching device is greater than the balance discharge threshold voltage.

[0150] Each acquisition circuit or each comparator circuit may also receive a first control signal CELL_SCAN(n), which is used to control whether the corresponding acquisition circuit or comparator circuit operates. Specifically: the first control signal CELL_SCAN(n) is a first logic level, such as a logic high level, indicating that the corresponding second switching device needs to be disconnected to acquire the voltage of the cell coupled to the corresponding second switching device, and the first logic level can also control the corresponding acquisition circuit or comparator circuit to operate; the first control signal CELL_SCAN(n) is a second logic level, such as a logic low level, indicating that the corresponding second switching device does not need to be disconnected to acquire the voltage of the cell coupled to the corresponding second switching device, and the second logic level can also control the corresponding acquisition circuit or comparator circuit to stop operating.

[0151] The acquisition circuit acquires the voltage of the cell coupled to the switching device when the switching device is open. Then, the control logic compares the cell voltage acquired by the acquisition circuit with a set value and outputs at least two second control signals BAL_DET(n). The comparison circuit acquires the voltage of the cell coupled to the switching device when the switching device is open, compares the cell voltage with a set value, and outputs the comparison result. The control logic outputs at least two second control signals BAL_DET(n) based on the output results of at least two comparison circuits.

[0152] In some embodiments, the comparison circuit may include a comparator, the first output of which is coupled to one end of a switching device, the second input of which is coupled to the other end of a switching device, and the third output of which can receive a first control signal CELL_SCAN(n). The comparator is used to compare the difference between the voltages input to the first and second inputs with a preset value stored internally, and output the comparison result to the control circuit through the output.

[0153] When the second control signal BAL_DET(n) is at a logic low level, it indicates that the voltage of the cell coupled to the corresponding second switching device is greater than the balance discharge threshold voltage. When the second control signal BAL_DET(n) is at a logic high level, it indicates that the voltage of the cell coupled to the corresponding second switching device is not greater than the balance discharge threshold voltage. Furthermore, when the cell voltage is greater than the balance discharge threshold and cell voltage acquisition is not required, the corresponding second switching device can be turned on for balance discharge (all second switching devices can be turned off when all cell voltages are greater than the balance discharge threshold). When the cell voltage is less than the balance discharge threshold or cell voltage acquisition is required, the corresponding second switching device is turned off.

[0154] The control circuit described above also includes a first inverter, wherein the lowest-level second switching device is grounded and is an NMOS transistor, the control terminal of which is coupled to the input terminal of the first inverter, the output terminal of the first inverter is used to receive the control signal sent by the control circuit, the highest-level switching device is a PMOS transistor, and the second switching device located at the non-end position of the series of multiple second switching devices is one of the following: an NMOS transistor, a PMOS transistor, or a combination of an NMOS transistor and a PMOS transistor.

[0155] The logic operation circuit may include, for example, a first OR gate OR1 and at least two second OR gates such as OR21, OR22, ..., OR(2n). The logic operation circuit can be used to perform logical operations on at least one first control signal (such as at least one of CELL_SCAN(1), CELL_SCAN(2), ..., CELL_SCAN(n)) and at least one second control signal (such as at least one of BAL_DET(1), BAL_DET(2), ..., BAL_DET(n)) to output at least one control signal (such as at least one of BAL_CTRL(1), ..., BAL_CTRL(n)). Each control signal (such as one of BAL_CTRL(1), ..., BAL_CTRL(n)) is used to control the corresponding second switching device to be turned off or on.

[0156] The first OR gate OR1 may include at least two input terminals, which respectively receive at least two first control signals CELL_SCAN(n). The output terminal of the first OR gate OR1 is used to output a third control signal CELL_SCAN, which is used to indicate whether all second switching devices are turned off. The first input terminal of each second OR gate, such as OR21, OR22...OR(2n), is used to receive the first control signal CELL_SCAN(n) corresponding to the second switching device. The second input terminal of each second OR gate is used to receive the third control signal CELL_SCAN. The output terminal of each second OR gate is used to output a control signal BAL_CTRL(n) and is coupled to the control terminal of at least two second switching devices.

[0157] Figure 4 A schematic diagram of the structure of a balanced discharge circuit according to an embodiment of the present disclosure is shown.

[0158] Reference Figure 4 As shown, the second OR gate also includes a third input terminal, which is used to receive a fourth control signal STOP_BAL. The fourth control signal is used to characterize whether all cells coupled to the second switching devices need to undergo balancing discharge. When all cells coupled to the second switching devices need to undergo balancing discharge, the fourth control signal is at a logic high level. When at least one cell coupled to a switching device does not need to undergo balancing discharge, the fourth control signal is at a logic low level. The control circuit also includes a third OR gate OR3 and a second inverter INV2. The third OR gate includes at least two input terminals, which respectively receive at least two second control signals BAL_DET(n). The output terminal of the third OR gate is coupled to the input terminal of the second inverter INV2, and the output terminal of the second inverter is used to output the fourth control signal.

[0159] Therefore, the function of the third OR gate and the second inverter is: if the voltage of all cells is higher than the balance threshold voltage, then all cells can stop balancing discharge, and at this time all the second switching devices are turned off.

[0160] In some embodiments, some components of the battery protection circuit can be integrated within the chip body, while others are disposed outside the chip body as peripheral circuits. For example, the balanced discharge circuit is disposed within the chip body; the plurality of first switching devices are disposed outside the chip body; and the resistor structure is disposed outside the chip body.

[0161] In some embodiments, the battery protection circuit further includes the aforementioned resistor structure; the resistor structure is located on the transmission line of at least one of the positive or negative terminals of each of the plurality of cells included in the series battery pack, and is disposed outside the chip body. For example, the aforementioned resistor structure and the aforementioned first switching device constitute a peripheral circuit.

[0162] The aforementioned battery protection chip incorporates multiple first switching devices and a balancing discharge circuit. The balancing discharge circuit can acquire voltage data from the coupled cells and control balancing discharge when an imbalance is detected between cells during charging or discharging. During the balancing discharge of one or more cells based on a resistive structure, the voltage drop signal of part or all of the resistance in the resistive structure during balancing discharge is used as a control signal. In some scenarios (e.g., during certain phases of battery protection circuit use, when the discharge current flowing into the balancing discharge circuit from a target cell is large, the voltage drop signal corresponding to the resistive structure exceeds the turn-on voltage threshold of the first switching device, driving the first switching device to be in a conducting state; or, during various phases of battery protection circuit use, when a certain...), the voltage drop signal is higher than the turn-on voltage threshold of the first switching device, driving the first switching device to be in a conducting state. The voltage drop signal corresponding to the resistive structure in each target cell is always greater than the threshold voltage of the first switching device, and can always be in the conducting state under the driving action of the voltage drop signal. The voltage drop signal is used to drive the first switching device to be in the conducting state. The first switching device in the conducting state forms an additional balanced discharge path independent of the above-mentioned balanced discharge circuit. This additional balanced discharge path is independent of the discharge path corresponding to the balanced discharge circuit. The multiple discharge paths also effectively enhance the balanced discharge current. When the discharge current is large, it can be discharged quickly through multiple discharge paths, thus protecting the series-connected cells. This effectively solves the problem in related technologies that the balanced discharge current is limited by the value of the protection resistor set in the circuit and the current carrying capacity of the built-in balanced discharge switch.

[0163] Furthermore, as the overall cell voltage drops to a relatively small level during battery pack use, the same first switching device may initially be in a conducting state driven by the voltage drop signal, but later the voltage drop signal may be insufficient to drive the first switching device to conduct. In other words, the aforementioned voltage drop signal causes the first switching device to remain in a cut-off state. In this scenario, since the discharge current is small, the corresponding cell protection can be achieved simply through the discharge path corresponding to the balanced discharge circuit.

[0164] A second exemplary embodiment of this disclosure provides a battery system.

[0165] The battery system of this embodiment includes: a series-connected battery pack; and a battery protection circuit provided in the first embodiment.

[0166] The battery system can be implemented based on hardware circuits, or a combination of hardware circuits and control programs.

[0167] A third exemplary embodiment of this disclosure provides a battery protection control method, applied to the battery protection circuit provided in the first embodiment or the battery system provided in the second embodiment, the method comprising:

[0168] Voltage is collected for each cell in a series-connected battery pack.

[0169] The decision to activate the balancing discharge circuit based on the collected voltage of each cell is made to perform balancing discharge on the target cell. During the balancing discharge process, the voltage drop signal of part or all of the resistance in the resistor structure corresponding to the target cell during balancing discharge is used as the control signal of the first switching device to drive the first switching device to be in the on state or to keep the first switching device in the off state. The first switching device in the on state forms an additional balancing discharge path independent of the above-mentioned balancing discharge circuit, so that the target cell can be balancing discharged together based on the discharge path corresponding to the above-mentioned balancing discharge circuit and the above-mentioned additional balancing discharge path.

[0170] The target cell is one or more cells in the series battery pack whose voltage is higher than that of other cells and whose voltage difference exceeds the balance range; or, the target cell is one or more cells in the series battery pack whose voltage is greater than the balance discharge threshold voltage, and at least one cell in the series battery pack has a voltage lower than the balance discharge threshold voltage.

[0171] By collecting voltage data from each cell in a series-connected battery pack and determining the voltage balance of each cell, a balancing discharge circuit is controlled to discharge the target cell with the higher voltage. Simultaneously, the first switching device in the circuit uses the voltage drop signal generated by the resistor structure corresponding to the target cell as a control signal. When the balancing discharge current is large, the voltage drop signal is sufficient to drive the first switching device to conduct, thus forming an additional balancing discharge path independent of the aforementioned balancing discharge circuit. This allows for balancing discharge of the target cell using both the discharge path of the balancing discharge circuit and the additional balancing discharge path, effectively protecting the series-connected battery pack and enhancing the discharge current. This effectively solves the problem in related technologies where the balancing discharge current is limited by the value of the protective resistor in the circuit and the current carrying capacity of the built-in balancing discharge switch.

[0172] Furthermore, as the overall cell voltage drops to a relatively small level during battery pack use, the same first switching device (e.g., the first switching device SWn in the example above) may be in a conducting state initially driven by the voltage drop signal, but later the voltage drop signal may be insufficient to drive the first switching device to conduct. In other words, the voltage drop signal may cause the first switching device to remain in a cut-off state. In this scenario, since the discharge current is small, the corresponding cell protection can be achieved through the discharge path corresponding to the balanced discharge circuit.

[0173] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0174] In this disclosure, terms such as “connection,” “linked,” “connected,” “coupled,” and “coupled” that indicate electrical connection, unless otherwise specified, refer to direct or indirect electrical connections. A direct electrical connection refers to a direct connection between two or more objects without any intervening objects, while an indirect electrical connection refers to a connection between two or more objects with one or more intervening objects (such as electrical components or units like resistors, capacitors, inductors, switches, and filters).

[0175] The above description is merely a specific embodiment of this disclosure, enabling those skilled in the art to understand or implement it. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A battery protection circuit, characterized in that, include: A plurality of first switching devices are provided for connection to a series-connected battery pack; wherein a resistor structure is provided on the transmission line of at least one of the positive or negative terminals of each of the plurality of cells in the series-connected battery pack, the resistor structure comprising one resistor or a plurality of resistors connected in series; a first connection terminal of each first switching device is used to connect between the positive terminal of each cell and the resistor structure; a second connection terminal of each first switching device is used to connect between the negative terminal of each cell and the resistor structure. A balanced discharge circuit is used to connect in series with the resistor structure and then coupled to both ends of each cell to determine whether to perform balanced discharge on the coupled cell based on the sampled voltage of the coupled cell. The control signal at the control terminal of each first switching device is the voltage drop signal of part or all of the resistance in the resistor structure during balanced discharge. The voltage drop signal is used to drive the first switching device to be in the on state or to keep the first switching device in the off state. The first switching device in the on state forms an additional balanced discharge path independent of the balanced discharge circuit. For each first switching device, when the corresponding voltage drop signal is higher than the current first switching device's turn-on voltage threshold, the current first switching device is driven to turn on; when the corresponding voltage drop signal is lower than the current first switching device's turn-on voltage threshold, the current first switching device remains off. When at least one target cell is in a balanced discharge state, the first switching device connected to the target cell has one of the following states: When the discharge current corresponding to the target battery cell is higher than a set value, the corresponding first switching device is in a first conducting state; or... The discharge current of the target battery cell is less than a set value, and the first switching device connected to the target battery cell is in the second state of being off. The first switching device is one of the following two types: upper resistor driven type and lower resistor driven type; For the first switching device driven by the upper resistor, the control signal of its control terminal comes from the first resistor structure on the transmission line of the positive electrode of the battery cell, and the first resistor structure is located between the positive electrode of the battery cell and the balance discharge circuit. For the first switching device driven by the lower resistor, the control signal at its control terminal comes from the second resistor structure on the transmission line of the negative electrode of the battery cell. The second resistor structure is located between the negative electrode of the battery cell and the balance discharge circuit. The first connection terminal of each first switching device is used to connect between the positive terminal of each battery cell and the resistive structure, and the second connection terminal of each first switching device is used to connect between the negative terminal of each battery cell and the resistive structure, including: For each first switching device, one of the following situations exists: The first and second connection terminals of the current first switching device are directly connected to the positive and negative terminals of the corresponding battery cells, respectively, forming a parallel connection between the current first switching device and the two ends of each battery cell; or, An intermediate element is provided between the first connection terminal of the first switching device and the positive terminal of the corresponding battery cell, and the second connection terminal of the first switching device is directly connected to the negative terminal of the corresponding battery cell; or, Currently, the first connection terminal of the first switching device is directly connected to the positive terminal of the corresponding battery cell, and an intermediate element is provided between the second connection terminal of the first switching device and the connection line of the corresponding battery cell; or, An intermediate element is provided between the first connection terminal of the first switching device and the line connecting the positive terminal of the corresponding battery cell, and an intermediate element is provided between the second connection terminal of the first switching device and the line connecting the negative terminal of the corresponding battery cell.

2. The battery protection circuit according to claim 1, characterized in that, The balanced discharge circuit is located inside the chip body and has a cell voltage detection function; the port of the balanced discharge circuit coupled to each cell has at least two port attributes: a power equalization discharge port attribute and a cell equalization voltage detection port attribute. The plurality of first switching devices are located outside the chip body; The control terminal of each first switching device satisfies one of the following conditions: The control terminal of the first switching device is currently coupled to the internal series circuit of the resistor structure in the corresponding battery cell; or, The control terminal of the first switching device is currently coupled to the connection line between the resistor structure in the corresponding cell and the balanced discharge circuit.

3. The battery protection circuit according to claim 1, characterized in that, The first switching device driven by the upper resistor has at least one of the following structures: A PMOS transistor, wherein the gate of the PMOS transistor is the control terminal, and the source and drain of the PMOS transistor are the conduction connection terminals; or, The combination structure of a PMOS transistor and a first series resistor, wherein the first series resistor is connected in series with at least one of the source or drain of the PMOS transistor; A PNP bipolar transistor, wherein the base of the PNP bipolar transistor is the control terminal, and the emitter and collector of the PNP bipolar transistor are the conduction terminals; or, The combination structure of a PNP bipolar transistor and a second series resistor, wherein the second series resistor is connected in series with at least one of the emitter or collector of the PNP bipolar transistor; The first switching device driven by the downstream resistor has at least one of the following structures: An NMOS transistor, wherein the gate of the NMOS transistor is the control terminal, and the source and drain of the NMOS transistor are the conduction connection terminals; or, The combination structure of an NMOS transistor and a third series resistor, wherein the third series resistor is connected in series with at least one of the source or drain of the NMOS transistor; An NPN bipolar transistor, wherein the base of the NPN bipolar transistor is the control terminal, and the emitter and collector of the NPN bipolar transistor are the conduction terminals; or, The combination structure of an NPN bipolar transistor and a fourth series resistor, wherein the fourth series resistor is connected in series with at least one of the emitter or collector of the NPN bipolar transistor.

4. The battery protection circuit according to any one of claims 1-3, characterized in that, Also includes: A resistor structure is located on the transmission line of at least one of the positive or negative terminals of each of the multiple cells included in the series battery pack, and is disposed outside the chip body; Determine whether to perform balancing discharge on the coupled cell based on the sampled voltage of the coupled cell, including: performing balancing discharge on the coupled cell when the sampled voltage of the coupled cell is higher than the sampled voltage of other cells and the voltage difference exceeds the balance range. The balanced discharge circuit includes: Multiple second switching devices, each of which is connected in series with the resistive structure in each cell and then coupled to both ends of each cell; A control circuit is coupled to both ends of each of the second switching devices and is used to acquire the voltage of the cell coupled to the disconnected second switching device when the second switching device is disconnected, and to determine whether to control at least one second switching device to conduct in order to perform balanced discharge on the coupled cell based on the acquired cell voltage. The control circuit is used to control the second switching device coupled to the target cell to be turned on. When the voltage drop signal drives the first switching device to be in the on state, the target cell is balanced discharged based on the balanced discharge circuit and the additional balanced discharge path. When the voltage drop signal drives the first switching device to remain in the off state, the target cell is balanced discharged based on the balanced discharge circuit. The target cell is one or more cells in the series battery pack whose voltage value is higher than that of other cells and whose voltage difference exceeds the balance range; or, the target cell is one or more cells in the series battery pack whose voltage is greater than the balance discharge threshold voltage, and at least one cell in the series battery pack has a voltage lower than the balance discharge threshold voltage.

5. The battery protection circuit according to claim 4, characterized in that, The plurality of second switching devices are connected in series, one end of which is used to couple to the first end of the series battery pack and ground, and the other end of which is used to couple to the second end of the series battery pack. The end of each second switching device away from ground is used to be coupled to the resistor structure. In two adjacent second switching devices, the resistor structure coupled to the upper-level second switching device and the resistor structure coupled to the lower-level second switching device are connected in series and then coupled to the two ends of the cell corresponding to the upper-level second switching device. Furthermore, when the control circuit acquires the voltage of at least one cell, the control circuit controls all of the plurality of second switching devices to be turned off.

6. The battery protection circuit according to claim 5, characterized in that, The control circuit includes: At least two acquisition circuits or at least two comparison circuits are provided, each of the acquisition circuits or each of the comparison circuits being coupled to both ends of one of the plurality of second switching devices. Each acquisition circuit is used to acquire the voltage of the cell coupled to the second switching device when the second switching device is turned off, and each comparison circuit is used to acquire the voltage of the cell coupled to the second switching device when the second switching device is turned off, and compare the voltage of the cell with a set value and output a comparison result. The control logic is configured to output at least two first control signals, each first control signal being configured to characterize whether it is necessary to disconnect the corresponding second switching device to acquire the voltage of the cell coupled to the corresponding second switching device; and the control logic is coupled to the output terminals of the at least two acquisition circuits or the at least two comparison circuits, and is configured to output at least two second control signals based on the output results of the at least two acquisition circuits or the at least two comparison circuits, each second control signal being configured to characterize whether the voltage of the cell coupled to the corresponding second switching device is greater than the balance discharge threshold voltage; A logic operation circuit is used to perform logical operations on at least one first control signal and at least one second control signal to output at least one control signal, each of the control signals being used to control a corresponding second switching device to be turned off or on.

7. The battery protection circuit according to claim 6, characterized in that, Each of the acquisition circuits or each of the comparison circuits also receives the first control signal, which is used to control whether the corresponding acquisition circuit or comparison circuit operates. Wherein: when the first control signal is at the first logic level, the corresponding first control signal is used to indicate that the corresponding second switching device needs to be disconnected in order to acquire the voltage of the cell coupled to the corresponding second switching device, and the corresponding first control signal is also used to control the corresponding acquisition circuit or comparison circuit to work. When the first control signal is at the second logic level, the corresponding first control signal is used to indicate that it is not necessary to disconnect the corresponding switching device to collect the voltage of the cell coupled to the corresponding switching device. Furthermore, the corresponding first control signal is also used to control the corresponding acquisition circuit or comparison circuit to stop working. The control circuit further includes a first inverter, wherein the lowest-level second switching device is grounded and is an NMOS transistor, the control terminal of which is coupled to the input terminal of the first inverter, the output terminal of the first inverter is used to receive the control signal sent by the control circuit, the highest-level switching device is a PMOS transistor, and the second switching devices located at the non-end positions of the multiple series-connected second switching devices are one of the following: NMOS transistor, PMOS transistor, or a combination of NMOS transistor and PMOS transistor.

8. A battery system, characterized in that, include: Series battery pack; The battery protection circuit according to any one of claims 1-7.

9. A battery protection control method, characterized in that, The method, applied to the battery protection circuit of any one of claims 1-7 or the battery system of claim 8, comprises: Voltage is collected for each cell in a series-connected battery pack. The decision to activate the balancing discharge circuit based on the collected voltage of each cell is made to perform balancing discharge on the target cell. During the balancing discharge process, the voltage drop signal of part or all of the resistance in the resistor structure corresponding to the target cell during balancing discharge is used as the control signal of the first switching device to drive the first switching device to be in the on state or to keep the first switching device in the off state. The first switching device in the on state forms an additional balancing discharge path independent of the balancing discharge circuit, so that the target cell can be balancing discharged together based on the discharge path corresponding to the balancing discharge circuit and the additional balancing discharge path. Wherein, the target cell is one or more cells in the series battery pack whose voltage value is higher than that of other cells and whose voltage difference exceeds the balance range; or, the target cell is one or more cells in the series battery pack whose voltage is greater than the balance discharge threshold voltage, and at least one cell in the series battery pack has a voltage lower than the balance discharge threshold voltage.

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