Battery pack prevents feedback current impact circuit, battery pack and electric vehicle

Abstract

The utility model discloses a kind of battery pack prevents the circuit of feedback current impact, battery pack and electric vehicle, comprising: temperature detection module, battery connection point, load connection point, first loop module and second loop module;Temperature detection module is used to detect the temperature of battery;First loop module and second loop module are connected in parallel between battery connection point and load connection point;First loop module is configured to be in the temperature of battery greater than or equal to first preset temperature, controlled conduction battery connection point and load connection point between passage;Second loop module is configured to be in the temperature of battery less than first preset temperature, controlled conduction battery connection point and load connection point between passage, and block feedback current between battery connection point and load connection point, can avoid the damage of feedback current generated in low temperature environment to battery, it is favorable to improve the service life of battery.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and in particular to a circuit for preventing feedback current surges in a battery pack, a battery pack, and an electric vehicle. Background Technology

[0002] Currently, most battery cells on the market are not allowed to be charged below 0°C. This is because under low temperature conditions, lithium ions are prone to lithium plating on the surface of the negative electrode, which not only causes irreversible capacity decay, but may also form lithium dendrites, piercing the separator and causing internal short circuits, seriously threatening the safety and lifespan of the battery.

[0003] In the field of power systems such as electric vehicles, highly coordinated communication protocols (such as CAN bus) and thermal management strategies are typically used between the vehicle and the battery pack to achieve precise temperature monitoring and charge / discharge control, thereby effectively avoiding the risks of low-temperature charging and feedback current. However, in the electric two-wheeler market, due to the large number of vehicle brands and models, battery packs are often used as general or aftermarket components, lacking effective control mechanisms for the batteries. This poses a risk that feedback current can flow directly into the cells below 0°C, inducing side reactions such as lithium plating, resulting in shortened cell life or even battery failure. Utility Model Content

[0004] This invention provides a circuit, a battery pack, and an electric vehicle for preventing feedback current surges in a battery pack. This avoids damage to the battery caused by feedback current generated in the vehicle at low temperatures, and helps to improve the battery's lifespan.

[0005] In a first aspect, this utility model provides a circuit for preventing feedback current surges in a battery pack, comprising: a temperature detection module, a battery connection point, a load connection point, a first circuit module, and a second circuit module;

[0006] The temperature detection module is used to detect the temperature of the battery;

[0007] The first circuit module and the second circuit module are connected in parallel between the battery connection point and the load connection point;

[0008] The first circuit module is configured to controllably open the path between the battery connection point and the load connection point when the battery temperature is greater than or equal to a first preset temperature.

[0009] The second circuit module is configured to controllably open the path between the battery connection point and the load connection point and block the feedback current between the battery connection point and the load connection point when the battery temperature is lower than a first preset temperature.

[0010] Optionally, the first circuit module includes a first switching unit and a unidirectional conduction blocking unit;

[0011] The first switching unit and the unidirectional conduction blocking unit are connected in series and connected between the battery connection point and the load connection point.

[0012] Optionally, the first switching unit includes a first switching transistor, and the unidirectional conduction blocking unit includes a diode;

[0013] When the battery connection point is connected to the positive terminal of the battery, the anode of the diode is connected to the battery connection point, and the cathode of the diode is connected to the load connection point.

[0014] Optionally, when the battery connection point is connected to the negative terminal of the battery, the cathode of the diode is connected to the battery connection point, and the anode of the diode is connected to the load connection point.

[0015] Optionally, the second circuit module includes a pre-charge branch and a main power branch;

[0016] The precharge branch and the main power branch are connected in parallel between the battery connection point and the load connection point;

[0017] The pre-charge branch is configured to be turned on during the system startup phase to pre-charge the load-side capacitor.

[0018] The main power branch is configured to be turned on after precharging is completed, wherein the precharging branch and the main power branch are not turned on simultaneously.

[0019] Optionally, the main power branch includes a second switching unit connected between the battery connection point and the load connection point.

[0020] Optionally, the pre-charge branch includes: a third switching unit and a pre-charge resistor; the third switching unit and the pre-charge resistor are connected in series and connected between the battery connection point and the load connection point.

[0021] Optionally, the second switching unit includes a second switching transistor, and the third switching unit includes a third switching transistor.

[0022] Secondly, embodiments of the present invention provide a battery pack, including a circuit for preventing feedback current surges in any embodiment of the present invention.

[0023] Thirdly, this utility model provides an electric vehicle, including a battery pack according to any embodiment of this utility model.

[0024] The circuit for preventing feedback current surges provided in this embodiment of the invention connects a first circuit module and a second circuit module in parallel between the battery connection point and the load connection point. By combining the relationship between the battery temperature and a first preset temperature, the circuit dynamically selects to activate either the first circuit module or the second circuit module. In the safe temperature range, the first circuit module is used for normal charging and discharging, while in the unsafe temperature range, the second circuit module is used to maintain a unidirectional discharge path and simultaneously block the feedback current from the load side. This avoids damage to the battery caused by the feedback current generated when the vehicle is braking or going downhill in low-temperature environments, which helps to improve the battery's service life. Attached Figure Description

[0025] Figure 1 A circuit diagram for preventing feedback current surges in a battery pack, provided as an embodiment of this utility model;

[0026] Figure 2 A circuit diagram illustrating another battery pack designed to prevent feedback current surges, provided as an embodiment of this utility model.

[0027] Figure 3 This is a circuit diagram illustrating another battery pack designed to prevent feedback current surges, provided as an embodiment of the present invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0029] Figure 1 A circuit diagram for preventing feedback current surges in a battery pack, as provided in this embodiment of the present invention, is shown below. Figure 1The system includes a temperature detection module, a battery connection point 1, a load connection point 2, a first circuit module 120, and a second circuit module 110. The battery connection point 1 is connected to the positive terminal of the battery pack, and the load connection point 2 is connected to the positive input terminal of the motor controller (i.e., the load). If the system adopts a negative control architecture, then the battery connection point 1 is connected to the negative terminal of the battery pack, and the load connection point 2 is connected to the negative input terminal of the motor controller (i.e., the load). For example, in this embodiment, a negative control architecture is used. The first circuit module 120 and the second circuit module 110 are connected in parallel between the battery connection point 1 and the load connection point 2; the first circuit module 120 and the second circuit module 110 form two selectable current paths. The temperature detection module can be an NTC thermistor or other temperature sensor, installed on the surface of the battery cell or inside the module of the battery pack, for real-time detection of the battery temperature and outputting the temperature signal to a control unit, such as the MCU of an electric vehicle or a separately configured protection IC.

[0030] For example, the operation of the circuit preventing feedback current surge in this embodiment of the present invention is as follows: Based on the relationship between the battery temperature and a first preset temperature, the first circuit module 120 or the second circuit module 110 is dynamically selected to be turned on. When the battery temperature is greater than or equal to the first preset temperature, the battery is within a safe temperature range, allowing normal charging and discharging. In this case, the first circuit module 120 is turned on, and the second circuit module 110 is turned off. When the battery temperature is lower than the first preset temperature, the battery enters a low-temperature protection mode. At this time, the current injected into the battery is cut off, the first circuit module 120 is turned off, and the second circuit module 110 is turned on. The second circuit module 110 maintains a unidirectional discharge path while blocking feedback current from the load side. It should be noted that the first preset temperature can be set according to the lowest safe temperature during battery charging. For example, in this embodiment of the present invention, the first preset temperature can be 0°C.

[0031] The circuit for preventing feedback current surges provided in this embodiment of the invention connects a first circuit module 120 and a second circuit module 110 in parallel between the battery connection point 1 and the load connection point 2. Based on the relationship between the battery temperature and a first preset temperature, the circuit dynamically selects to activate either the first circuit module 120 or the second circuit module 110. In the safe temperature range, the first circuit module 120 is used for normal charging and discharging, while in the unsafe temperature range, the second circuit module 110 is used to maintain a unidirectional discharge path and simultaneously block the feedback current from the load side. This avoids damage to the battery caused by the feedback current generated when the vehicle is braking or going downhill in low-temperature environments, and helps to improve the battery's service life.

[0032] Figure 2A circuit diagram illustrating another method for preventing feedback current surges in a battery pack, as provided in this embodiment of the invention, is shown below. Figure 2 The first circuit module 120 includes a first switching unit 121 and a unidirectional conduction blocking unit 122. The first switching unit 121 and the unidirectional conduction blocking unit 122 are connected in series and are connected between the battery connection point 1 and the load connection point 2. The first switching unit 121 and the unidirectional conduction blocking unit 122 form a current path in series. The first switching unit 121 can controllably turn on or off the current path under the action of a control signal. The unidirectional conduction blocking unit 122 is configured to only allow current to flow from the battery side to the load side, i.e., the discharge direction, and automatically cuts off when a reverse voltage is detected, thereby effectively blocking the current fed back from the load side to the battery side. Through the series structure of the first switching unit 121 and the unidirectional conduction blocking unit 122, the first circuit module 120 can discharge normally in the conducting state, and the unidirectional conduction blocking unit 122 is used to prevent abnormal feedback current from impacting the battery.

[0033] Optionally, the first switching unit 121 includes a first switching transistor Q1, and the unidirectional conduction blocking unit 122 includes a diode D1. In this embodiment, a negative electrode control architecture is used as an example. Battery connection point 1 is connected to the negative terminal of the battery, and load connection point 2 is connected to the negative input terminal of the motor controller (i.e., the load). During charging, current flows into the battery. The feedback current to the negative terminal of the battery is from battery connection point 1 to load connection point 2. The cathode of diode D1 is connected to battery connection point 1, and the anode of diode D1 is connected to load connection point 2. When a reverse voltage exists, i.e., when there is feedback current from battery connection point 1 to load connection point 2, diode D1 is naturally cut off, thereby achieving the unidirectional conduction function.

[0034] Figure 3 A circuit diagram illustrating another method for preventing feedback current surges in a battery pack, as provided in this embodiment of the invention, is shown below. Figure 3 In this embodiment of the invention, a positive control architecture is used as an example. Battery connection point 1 is connected to the positive terminal of the battery, and load connection point 2 is connected to the positive input terminal of the motor controller (i.e., the load). The direction of the feedback current to the positive terminal of the battery is from load connection point 2 to battery connection point 1. The anode of diode D1 is connected to battery connection point 1, and the cathode of diode D1 is connected to load connection point 2. When there is a reverse voltage, that is, when there is a feedback current from load connection point 2 to battery connection point 1, diode D1 is naturally cut off, thereby realizing the unidirectional conduction function.

[0035] See also Figure 2 and Figure 3 The second circuit module 110 includes a pre-charge branch 111 and a main power branch 112;

[0036] The pre-charge branch 111 and the main power branch 112 are connected in parallel between the battery connection point 1 and the load connection point 2;

[0037] The precharge branch 111 is configured to be turned on during the system startup phase to precharge the load-side capacitor;

[0038] The main power branch 112 is configured to be turned on after precharging is completed, wherein the precharging branch 111 and the main power branch 112 are not turned on at the same time.

[0039] Specifically, the second circuit module 110 includes a pre-charge branch 111 and a main power branch 112 connected in parallel. When the battery temperature is greater than or equal to a first preset temperature, the battery is considered to be within a safe temperature range, allowing normal charging and discharging. Therefore, during the vehicle startup phase, the pre-charge branch 111 is first activated to pre-charge the load-side capacitor, preventing current surges. After the load-side capacitor voltage stabilizes, the low-impedance main power branch 112 is then switched on to support high-current discharge. When the battery temperature is lower than the first preset temperature, the battery is considered to be within a safe temperature range, allowing normal charging and discharging. Therefore, during the vehicle startup phase, the pre-charge branch 111 is first activated to pre-charge the load-side capacitor, preventing current surges. After the load-side capacitor voltage stabilizes, the first circuit module 120 is then switched on, effectively blocking feedback current. During normal vehicle operation, if the battery temperature drops below the first preset temperature, the first circuit module 120 can be turned on, and the main power branch 112 can be switched off, thereby enabling switching and effective blocking of feedback current during operation.

[0040] Optionally, the main power branch 112 includes a second switching unit connected between the battery connection point 1 and the load connection point 2. The pre-charge branch 111 includes a third switching unit and a pre-charge resistor; the third switching unit and the pre-charge resistor are connected in series and connected between the battery connection point 1 and the load connection point 2. The second and third switching units are used to implement the function of turning on or off. For example, the second switching unit includes a second switching transistor Q2, and the third switching unit includes a third switching transistor Q3. The second switching transistor Q2 and the third switching transistor Q3 can be MOSFET switching transistors.

[0041] Specifically, the pre-charge branch 111 includes a third switch Q3 connected in series and a pre-charge resistor R, while the main power branch 112 includes a second switch Q2. The second switch Q2 and the third switch Q3 can be interlocked, meaning they cannot be turned on simultaneously. When the vehicle is powered on and started, if the battery temperature is greater than or equal to a first preset temperature, the third switch Q3 is turned on first, and the second switch Q2 is turned off, allowing current to slowly charge the load-side capacitor through the pre-charge resistor R in a unidirectional manner, avoiding current surges. After the load-side capacitor voltage stabilizes, the third switch Q3 is turned off, and the second switch Q2 is turned on again, switching to the low-impedance main power branch 112 to support high-current discharge. When the vehicle is powered on and started, if the battery temperature is less than the first preset temperature, the third switch Q3 is turned on first to complete pre-charging. After the first switch Q1 is turned on, the third switch Q3 is turned off, effectively blocking the feedback current under low-temperature conditions. During normal vehicle operation, if the battery temperature drops below the first preset temperature, the first switch tube can be turned on and the second switch tube Q2 can be turned off, thereby enabling switching during operation and effectively blocking the feedback current.

[0042] In this embodiment of the invention, each switching transistor can be a MOSFET. The selection of each switching transistor only needs to meet the overcurrent and withstand voltage requirements of the entire device, and is not specifically limited here. The connection direction of diode D1 must match the direction of the feedback current. The control unit that controls the conduction or cutoff of each switching transistor can be integrated into the battery management system (BMS), for example, driven and controlled by an analog front-end chip (AFE). It does not need to communicate with the vehicle and can complete the control only by relying on battery temperature and voltage signals, which is suitable for the two-wheeled or three-wheeled vehicle market where protocols are not uniform.

[0043] This utility model embodiment also provides a battery pack, which includes a battery module and a battery management system integrated in the battery module. The battery management system includes a circuit in any embodiment to prevent feedback current surges. Therefore, it has the same beneficial effects, and will not be repeated here. The above-mentioned battery pack can be widely used in scenarios lacking unified communication protocols and vehicle-wide collaborative control capabilities, such as electric two-wheelers, electric scooters, and low-speed electric vehicles.

[0044] This utility model embodiment also provides an electric vehicle equipped with the battery pack of this utility model embodiment. The electric vehicle can be an electric bicycle, electric motorcycle, electric moped, electric scooter, or other low-speed electric vehicle. During vehicle operation, when the user brakes, coasts, or goes downhill, the motor may enter a generating state and output feedback current. The electric vehicle of this utility model embodiment can isolate the feedback current at low temperatures, improving battery safety and battery life.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A circuit for preventing feedback current surges in a battery pack, characterized in that, include: Temperature detection module, battery connection point, load connection point, first circuit module and second circuit module; The temperature detection module is used to detect the temperature of the battery; The first circuit module and the second circuit module are connected in parallel between the battery connection point and the load connection point; The first circuit module is configured to controllably open the path between the battery connection point and the load connection point when the battery temperature is greater than or equal to a first preset temperature. The second circuit module is configured to controllably open the path between the battery connection point and the load connection point and block the feedback current between the battery connection point and the load connection point when the battery temperature is lower than a first preset temperature.

2. The circuit for preventing feedback current surges in the battery pack according to claim 1, characterized in that, The first circuit module includes a first switching unit and a unidirectional conduction blocking unit; The first switching unit and the unidirectional conduction blocking unit are connected in series and connected between the battery connection point and the load connection point.

3. The circuit for preventing feedback current surges in the battery pack according to claim 2, characterized in that, The first switching unit includes a first switching transistor, and the unidirectional conduction blocking unit includes a diode; When the battery connection point is connected to the positive terminal of the battery, the anode of the diode is connected to the battery connection point, and the cathode of the diode is connected to the load connection point.

4. The circuit for preventing feedback current surges in the battery pack according to claim 3, characterized in that, When the battery connection point is connected to the negative terminal of the battery, the cathode of the diode is connected to the battery connection point, and the anode of the diode is connected to the load connection point.

5. The circuit for preventing feedback current surges in a battery pack according to claim 1, characterized in that, The second circuit module includes a pre-charge branch and a main power branch; The precharge branch and the main power branch are connected in parallel between the battery connection point and the load connection point; The pre-charge branch is configured to be turned on during the system startup phase to pre-charge the load-side capacitor. The main power branch is configured to be turned on after precharging is completed, wherein the precharging branch and the main power branch are not turned on simultaneously.

6. The circuit for preventing feedback current surges in a battery pack according to claim 5, characterized in that, The main power branch includes a second switching unit connected between the battery connection point and the load connection point.

7. The circuit for preventing feedback current surges in a battery pack according to claim 6, characterized in that, The pre-charge branch includes a third switching unit and a pre-charge resistor; the third switching unit and the pre-charge resistor are connected in series and are connected between the battery connection point and the load connection point.

8. The circuit for preventing feedback current surges in a battery pack according to claim 7, characterized in that, The second switching unit includes a second switching transistor, and the third switching unit includes a third switching transistor.

9. A battery pack, characterized in that, The circuit for preventing feedback current surges in the battery pack as described in any one of claims 1-8.

10. An electric vehicle, characterized in that, Includes the battery pack as described in claim 9.

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