Battery self-heating circuit

Abstract

This application relates to a battery self-heating circuit, which includes a battery, a switching circuit, and a three-phase motor, wherein the battery, the switching circuit, and the three-phase motor are connected sequentially. When the battery requires self-heating, a discharge path and a charging path are formed between the battery, the switching circuit, and the three-phase motor. The discharge path allows the battery to discharge to one phase of the three-phase motor; the charging path allows the other two phases of the three-phase motor to charge the battery. During discharge and charging, a polarization reaction occurs inside the battery, generating heat, thereby rapidly increasing the battery temperature. This avoids the problem of incomplete heat utilization that occurs when heating the battery with coolant, thus improving the battery's heating efficiency.

Description

Technical Field

[0001] This application relates to the field of battery management technology, and in particular to a battery self-heating circuit. Background Technology

[0002] With the development of new energy technologies, electric vehicles, including electric cars, electric bicycles, electric motorcycles, and electric toy cars, are widely used. However, when electric vehicles are used in low-temperature environments, the capacity of the batteries will be greatly reduced, thus affecting charging performance and driving range. Therefore, it is necessary to propose technical means to heat the batteries in low-temperature environments.

[0003] Traditional technology uses a whole-vehicle liquid cooling system with an added heating mode. Specifically, the battery is placed in coolant, and heat is generated by controlling the motor to stall, first heating the coolant, and then the coolant heats the battery, thus raising the battery temperature.

[0004] However, while the coolant heats the battery, some of the heat is transferred to other places, so the heat generated by the stalled motor cannot be fully utilized, resulting in low heating efficiency. Summary of the Invention

[0005] Therefore, it is necessary to provide a battery self-heating circuit that can improve battery heating efficiency in response to the above-mentioned technical problems.

[0006] This application provides a battery self-heating circuit. The battery self-heating circuit includes a battery, a switching circuit, and a three-phase motor, wherein the battery, switching circuit, and three-phase motor are connected sequentially. When the battery requires self-heating, a discharge path and a charging path are formed between the battery, switching circuit, and three-phase motor. The discharge path allows the battery to discharge to one phase of the three-phase motor; the charging path allows the other two phases of the three-phase motor to charge the battery.

[0007] In one embodiment, the battery includes two battery packs; a discharge path is formed between the target battery pack, the switching circuit, and the three-phase motor, and a charging path is formed between the two battery packs, the switching circuit, and the three-phase motor, provided that the battery has a self-heating requirement; wherein, the target battery pack is one of the two battery packs, the discharge path is used for the target battery pack to discharge to one phase of the three-phase motor through the discharge path, and the charging path is used for the other two phases of the three-phase motor to charge the two battery packs through the charging path.

[0008] In one embodiment, the two battery packs include a first battery pack and a second battery pack, and the switching circuit is a bridge circuit, which includes a first bridge arm, a second bridge arm, and a third bridge arm; the first bridge arm, the second bridge arm, and the third bridge arm are respectively connected to one phase of a three-phase motor; the first battery pack is connected to the first bridge arm, and the second battery pack is connected to the first bridge arm, the second bridge arm, and the third bridge arm.

[0009] In one embodiment, the connection points between the upper and lower arms of the first bridge arm, the connection points between the upper and lower arms of the second bridge arm, and the connection points between the upper and lower arms of the third bridge arm are each connected to one phase of a three-phase motor; the positive terminal of the first battery pack is connected to the upper arm of the first bridge arm; the positive terminal of the second battery pack is connected to the upper arms of the first, second, and third bridge arms; and the negative terminals of the first and second battery packs are connected to the lower arms of the first, second, and third bridge arms.

[0010] In one embodiment, a DC contactor is provided between the upper arm of the first bridge arm and the upper arm of the second bridge arm.

[0011] In one embodiment, a capacitor is provided between the positive and negative terminals of the battery.

[0012] In one embodiment, the battery self-heating circuit includes multiple switching circuits and multiple three-phase motors corresponding to the multiple switching circuits. The battery is connected to each switching circuit, and each switching circuit is connected to the corresponding three-phase motor.

[0013] In one embodiment, the battery self-heating circuit further includes a control circuit, which is connected to the battery and the switching circuit respectively. The control circuit is used to acquire the temperature data of the battery and determine whether the battery has a self-heating requirement based on the temperature data. The control circuit is also used to acquire the current data of the switching circuit and, when the battery has a self-heating requirement, control the switching element in the switching circuit to form a discharge path and a charging path.

[0014] In one embodiment, the control circuit is also connected to a three-phase motor and is also used to acquire motor parameters; the control circuit is also used to control the switching elements in the switching circuit to form a discharge path and a charging path when the battery has a self-heating requirement.

[0015] In one embodiment, when the battery has a self-heating requirement, the control circuit controls the switching elements in the switching circuit to form a discharge path and a charging path based on a space vector pulse width modulation algorithm.

[0016] The aforementioned battery self-heating circuit includes a battery, a switching circuit, and a three-phase motor, which are connected sequentially. When the battery requires self-heating, a discharge path and a charging path are formed between the battery, the switching circuit, and the three-phase motor. The discharge path allows the battery to discharge to one phase of the three-phase motor, while the charging path allows the other two phases of the three-phase motor to charge the battery. In this way, during the discharge and charging process, a polarization reaction occurs inside the battery, generating heat and thus rapidly raising the battery temperature. This avoids the problem of incomplete heat utilization that exists when heating the battery with coolant, thereby improving the battery's heating efficiency. Attached Figure Description

[0017] Figure 1 This is a structural diagram of a battery self-heating circuit in one embodiment;

[0018] Figure 2 This is a structural diagram of a battery in one embodiment;

[0019] Figure 3 This is a structural diagram of another battery self-heating circuit in one embodiment;

[0020] Figure 4 This is a structural diagram of another battery self-heating circuit in one embodiment;

[0021] Figure 5 This is a structural diagram of another battery self-heating circuit in one embodiment;

[0022] Figure 6 This is a schematic flowchart of a battery self-heating method in one embodiment. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0024] With the development of new energy technologies, electric vehicles, including electric cars, electric bicycles, electric motorcycles, and electric toy cars, are widely used. However, when electric vehicles are used in low-temperature environments, the capacity of the batteries will be greatly reduced, thus affecting charging performance and driving range. Therefore, it is necessary to propose technical methods for heating batteries in low-temperature environments. Currently, there are three methods for heating batteries, but each has its own drawbacks, as detailed below:

[0025] The first method involves heating the battery using external devices. During the charging process, the electric vehicle uses some of its electrical energy to heat the battery. However, this method is only applicable to the charging process when the electric vehicle is parked and cannot solve the problem of heating the battery when the electric vehicle is driving in a low-temperature environment.

[0026] The second method is to add a hot nickel plate or a PTC (Positive Temperature Coefficient) device inside the battery. This method not only greatly increases the cost of the battery, but also reduces the energy density of the battery.

[0027] The third method is whole-vehicle liquid cooling, which adds a heating mode. Specifically, the battery is placed in coolant, and heat is generated by controlling the motor to lock up the rotor. This heat first heats the coolant, which then heats the battery, thus raising its temperature. However, this method requires coolant, increasing the battery size. Furthermore, the motor lockup accelerates the demagnetization of the motor's permanent magnets. Additionally, some heat is transferred to other areas while the coolant is heating the battery, meaning the heat generated by the motor lockup is not fully utilized, resulting in slow battery heating and low heating efficiency. Therefore, it is necessary to propose new technical solutions to these problems.

[0028] In one embodiment, such as Figure 1 The diagram shows a structural diagram of a battery self-heating circuit. This circuit includes a battery 100, a switching circuit 200, and a three-phase motor 300, which are connected sequentially. When the battery 100 requires self-heating, a discharge path and a charging path are formed between the battery 100, the switching circuit 200, and the three-phase motor 300. The discharge path allows the battery 100 to discharge to one phase of the three-phase motor 300; the charging path allows the other two phases of the three-phase motor 300 to charge the battery 100.

[0029] The battery 100 is placed in a battery pack, which contains the battery 100 and a battery management system. The battery management system integrates functions to protect the battery 100, such as overcurrent and overvoltage protection circuits. The switching circuit 200 can be a bridge circuit, which includes multiple bridge arms, each including an upper IGBT (Insulated Gate Bipolar Transistor) bridge arm and a lower IGBT bridge arm. The three-phase motor 300 refers to a three-phase asynchronous motor, a type of induction motor.

[0030] Optionally, the battery self-heating circuit uses a water-cooled housing, which is machined from aluminum alloy. The water-cooling design is tailored to the battery self-heating circuit to ensure that the switching circuit 200 operates within permissible limits. The specific connection methods of the battery 100, switching circuit 200, and three-phase motor 300 in the battery self-heating circuit are as follows:

[0031] The positive and negative terminals of battery 100 are connected to the first and second terminals of switch circuit 200, respectively, and are connected via three different key positions P1 of a 3-pin high-current aviation connector or three different key positions P2 of a 12-pin aviation connector. The third, fourth, and fifth terminals of switch circuit 200 are all connected to three-phase motor 300, and the connection method is also through three different key positions P1 of a 3-pin high-current aviation connector or three different key positions P2 of a 12-pin aviation connector.

[0032] Through the above connection method, the electric vehicle can heat the battery 100 in both normal driving and stationary states. When the temperature of the battery 100 is too low, i.e., when the battery 100 requires self-heating, a discharge path and a charging path can be formed by controlling the high-frequency switching of the IGBTs in multiple bridge arms of the switching circuit 200. In the discharge path, the current flows sequentially from the positive terminal of the battery 100, through the switching circuit 200, to one or two phases of the three-phase motor 300. In the charging path, the current flows sequentially from the remaining two or one phase of the three-phase motor 300, through the switching circuit 200, to the negative terminal of the battery 100. During the alternating process of discharging and charging, the battery 100 generates a large amount of heat, which raises its temperature. Furthermore, the battery 100 exchanges energy with the three-phase motor 300 through the discharge and charging paths, which also provides heat to the battery 100, thereby improving the battery's total driving range and charging / discharging performance.

[0033] In summary, the battery self-heating circuit includes a battery 100, a switching circuit 200, and a three-phase motor 300. The battery 100, switching circuit 200, and three-phase motor 300 are connected sequentially. When the battery 100 requires self-heating, a discharge path and a charging path are formed between the battery 100, switching circuit 200, and three-phase motor 300. The discharge path allows the battery 100 to discharge to one phase of the three-phase motor 300, while the charging path allows the other two phases of the three-phase motor 300 to charge the battery 100. Thus, during the discharge and charging processes, a polarization reaction occurs inside the battery 100, generating heat and rapidly increasing the temperature of the battery 100. This avoids the problem of incomplete heat utilization that occurs when heating the battery 100 with coolant, thereby improving the heating efficiency of the battery 100.

[0034] In one embodiment, such as Figure 2As shown, a structural diagram of a battery is provided. The battery 100 includes two battery packs, DC1 and DC2. The battery 100 has a self-heating requirement. A discharge path is formed between the target battery pack, the switching circuit 200, and the three-phase motor 300. A charging path is formed between the two battery packs DC1 and DC2, the switching circuit 200, and the three-phase motor 300. The target battery pack is one of the two battery packs DC1 and DC2. The discharge path is used for discharging the target battery pack to one phase of the three-phase motor. The charging path is used for charging the other two phases of the three-phase motor to the two battery packs DC1 and DC2.

[0035] Both battery packs, DC1 and DC2, can be composed of multiple batteries connected in series. The positive terminals of DC1 and DC2 are disconnected, while the negative terminals are connected. DC1 and DC2 have equal capacities and the same voltage across their positive and negative terminals. DC1, DC2, and the battery management system constitute a battery pack. The battery management system integrates a battery pack equalization system and energy balancing function to ensure that the voltage and energy of DC1 and DC2 are equal.

[0036] Optionally, the positive terminals of DC1 and DC2 are both connected to the first terminal of the switching circuit 200, the negative terminals of DC1 and DC2 are connected to the second terminal of the switching circuit, and the third, fourth and fifth terminals of the switching circuit 200 are all connected to the three-phase motor 300.

[0037] With the above connection method, when the temperature of battery 100 is too low, a discharge path can be formed between DC1 or DC2, the switching circuit 200, and the three-phase motor 300 by controlling the high-frequency switching of the IGBTs in multiple bridge arms of the switching circuit 200, and a charging path can be formed between DC1 and DC2, the switching circuit 200, and the three-phase motor 300. Specifically, by controlling the high-frequency switching of the IGBTs, DC1 and DC2 can be alternately discharged, and DC1 and DC2 can be charged simultaneously through the charging path. The specific process is as follows:

[0038] The switching circuit 200 controls the on / off state of the IGBT, forming a discharge path between DC1, the switching circuit 200, and the three-phase motor 300, and a charging path between DC1 and DC2, the switching circuit 200, and the three-phase motor 300. The current in the discharge path flows sequentially from the positive terminal of DC1 (DC1+) to one or two phases of the switching circuit 200 and the three-phase motor 300. The current in the charging path flows sequentially from the other two or one phase of the three-phase motor 300 to the switching circuit 200, the negative terminal of DC1, and the negative terminal of DC2 (DC-), thus realizing the discharge of DC1 to charge DC2.

[0039] The switching circuit 200 controls the on / off state of the IGBT, forming a discharge path between DC2, the switching circuit 200, and the three-phase motor 300, and a charging path between DC1 and DC2, the switching circuit 200, and the three-phase motor 300. The current in the discharge path flows sequentially from the positive terminal of DC2 (DC2+) to one or two phases of the switching circuit 200 and the three-phase motor 300. The current in the charging path flows sequentially from the other two or one phase of the three-phase motor 300 to the switching circuit 200, the negative terminal of DC1, and the negative terminal of DC2 (DC-), thus realizing the discharge of DC2 to charge DC1.

[0040] By controlling the high-frequency switching of the switching circuit 200, DC1 and DC2 are alternately discharged, and DC1 and DC2 are simultaneously charged through the charging path, thereby realizing energy exchange between the two battery packs DC1 and DC2 and generating a large amount of heat energy. This not only increases the temperature of battery 100, but also ensures the heat balance between the two battery packs DC1 and DC2.

[0041] In one embodiment, such as Figure 3 As shown, another battery self-heating circuit structure diagram is provided. The two battery packs include a first battery pack DC1 and a second battery pack DC2. The switching circuit 200 is a bridge circuit, which includes a first bridge arm 201, a second bridge arm 202, and a third bridge arm 203. The first bridge arm 201, the second bridge arm 202, and the third bridge arm 203 are respectively connected to one phase of the three-phase motor 300. The first battery pack DC1 is connected to the first bridge arm 201, and the second battery pack DC2 is connected to the first bridge arm 201, the second bridge arm 202, and the third bridge arm 203.

[0042] In one embodiment, the connection point between the upper and lower arms of the first bridge arm 201, the connection point between the upper and lower arms of the second bridge arm 202, and the connection point between the upper and lower arms of the third bridge arm 203 are respectively connected to one phase of the three-phase motor 300; the positive terminal DC1+ of the first battery pack DC1 is connected to the upper arm of the first bridge arm 201; the positive terminal DC2+ of the second battery pack DC2 is connected to the upper arms of the first bridge arm 201, the second bridge arm 202, and the third bridge arm 203; the negative terminal DC1- of the first battery pack DC1 and the negative terminal DC2- of the second battery pack DC2 are connected to the lower arms of the first bridge arm 201, the second bridge arm 202, and the third bridge arm 203.

[0043] In one embodiment, a DC contactor KM is provided between the upper arm of the first bridge arm 201 and the upper arm of the second bridge arm 202.

[0044] In one embodiment, a capacitor is provided between the positive and negative terminals of the battery 100.

[0045] Among them, the upper and lower bridge arms of the first bridge arm 201, the upper and lower bridge arms of the second bridge arm 202, and the upper and lower bridge arms of the third bridge arm 203 are all equipped with power devices. The power devices can be water-cooled silicon carbide modules of model BM840F12B34U2. Water-cooled silicon carbide modules are third-generation power devices with high power density, 1200V withstand voltage and 840A rated current, internal integrated NTC (Negative Temperature Coefficient) temperature detection, silver sintering technology, direct water cooling plate, and can be applied to voltages up to 800V.

[0046] The DC contactor KM can be selected from the DH100A vacuum circuit breaker, which has a withstand voltage rating of 900V, a rated current of 100A, and a short-time withstand current of 1000A. It features small size, high power, and facilitates the improvement of the power density of the switching circuit.

[0047] The capacitor can be a rated voltage of 1000V, 100uf capacitor, used to absorb the spikes caused by chopping during the heating process, and can be called a support capacitor.

[0048] Optionally, two sets of capacitors are provided between the positive and negative terminals of the battery 100, including a first capacitor C1 and a second capacitor C2; the positive terminal DC1+ of the first battery group DC1 is connected to the first end of the first capacitor C1 and the upper bridge arm of the first bridge arm 201; the positive terminal DC2+ of the second battery group DC2 is connected to the first end of the second capacitor C2, the upper bridge arm of the first bridge arm 201, the upper bridge arm of the second bridge arm 202, and the upper bridge arm of the third bridge arm 203; the negative terminal DC1- of the first battery group DC1 and the negative terminal DC2- of the second battery group DC2 are connected to form the negative terminal DC- of the battery 100, and the negative terminal DC- of the battery 100 is connected to the second end of the first capacitor C1, the second end of the second capacitor C2, the lower bridge arm of the first bridge arm 201, the lower bridge arm of the second bridge arm 202, and the lower bridge arm of the third bridge arm 203. The upper arm of the first bridge arm 201 and the upper arm of the second bridge arm 202 are connected to each other, and the upper arm of the second bridge arm 202 and the upper arm of the third bridge arm 203 are connected by a DC contactor; the lower arm of the first bridge arm 201, the lower arm of the second bridge arm 202 and the lower arm of the third bridge arm 203 are connected to each other.

[0049] With the above connection method, when the battery 100 has a self-heating requirement, the DC contactor KM is disconnected, controlling the on / off state of the upper and lower bridge arms in the switching circuit 200, forming a discharge path and a charging path, as shown in the following example:

[0050] The upper arm of the first bridge arm 201, the upper arm of the second bridge arm 202, and the upper arm of the third bridge arm 203 are switched on and off, respectively; the lower arm of the first bridge arm 201, the lower arm of the second bridge arm 202, and the lower arm of the third bridge arm 203 are switched on and off, respectively. The discharge path consists of the second battery pack DC2, the upper arm of the third bridge arm 203, and one phase of the three-phase motor 300 connected to the connection point between the upper and lower arms of the third bridge arm 201. The charging path consists of one phase of the three-phase motor 300 connected to the connection point between the upper and lower arms of the second bridge arm 202, one phase of the three-phase motor 300 connected to the connection point between the upper and lower arms of the first bridge arm 201, the lower arm of the second bridge arm 202, the lower arm of the first bridge arm 201, and the negative terminal DC- of the battery 100. This realizes the process of the second battery pack DC2 discharging to charge DC1.

[0051] The upper arm of the first bridge arm 201, the upper arm of the second bridge arm 202, and the upper arm of the third bridge arm 203 are switched on and off, respectively; the lower arm of the first bridge arm 201, the lower arm of the second bridge arm 202, and the lower arm of the third bridge arm 203 are switched on and off, respectively. The discharge path consists of the first battery pack DC1, the upper arm of the second bridge arm 202, and one phase of the three-phase motor 300 connected to the connection point between the upper and lower arms of the second bridge arm 202. The charging path consists of one phase of the three-phase motor 300 connected to the connection point between the upper and lower arms of the third bridge arm 203, one phase of the three-phase motor 300 connected to the connection point between the upper and lower arms of the first bridge arm 201, the lower arm of the third bridge arm 203, the lower arm of the first bridge arm 201, and the negative terminal DC- of the battery 100. This realizes the process of discharging the first battery pack DC1 to charge DC2.

[0052] By controlling the high-frequency switching of each bridge arm in the switching circuit 200, the first battery pack DC1 and the second battery pack DC2 are alternately discharged, and the first battery pack DC1 and the second battery pack DC2 are simultaneously charged through the charging path, thereby realizing energy exchange between the first battery pack DC1 and the second battery pack DC2 and generating a large amount of heat energy. This not only increases the temperature of the battery 100, but also ensures the thermal balance between the first battery pack DC1 and the second battery pack DC2.

[0053] In one embodiment, such as Figure 4 The diagram shows another type of battery self-heating circuit. The battery self-heating circuit includes multiple switching circuits 200 and multiple three-phase motors 300 corresponding to each switching circuit 200. The battery 100 is connected to each switching circuit 200, and each switching circuit 200 is connected to its corresponding three-phase motor 300.

[0054] Optionally, there are two switch circuits 200 for easy distinction, namely, a first switch circuit 210 and a second switch circuit 220. There are two three-phase motors 300, namely, a first three-phase motor 301 and a second three-phase motor 302. Correspondingly, there are two DC contactors KM, namely, a first DC contactor KM1 and a second DC contactor KM2. Four sets of capacitors are provided between the positive and negative terminals of the battery 100, namely, a first capacitor C1, a second capacitor C2, a third capacitor C3, and a fourth capacitor C4. The first switch circuit 210, the first three-phase motor 301, the first DC contactor KM1, the first capacitor C1, and the second capacitor C2 can be respectively considered as described above. Figure 3 The circuit includes a switching circuit 200, a three-phase motor 300, a DC contactor KM, a first capacitor C1, and a second capacitor C2. Their connections have been described in detail above. The following section will explain the connections between the second switching circuit 220, the second three-phase motor 302, the second DC contactor KM2, the third capacitor C3, and the fourth capacitor C4:

[0055] The second switching circuit 220 is a bridge circuit, which includes a fourth bridge arm 204, a fifth bridge arm 205, and a sixth bridge arm 206. The fourth bridge arm 204, the fifth bridge arm 205, and the sixth bridge arm 206 are respectively connected to one phase of the second three-phase motor 302. The first battery pack DC1 is connected to the fourth bridge arm 201, and the second battery pack DC2 is connected to the fourth bridge arm 204, the fifth bridge arm 205, and the sixth bridge arm 206.

[0056] The connection points between the upper and lower arms of the fourth bridge arm 204, the fifth bridge arm 205, and the sixth bridge arm 206 are respectively connected to one phase of the second three-phase motor 302; the positive terminal DC1+ of the first battery pack DC1 is connected to the first terminal of the third capacitor C3, the upper arm of the fourth bridge arm 204, and the upper arm of the fifth bridge arm 205; the positive terminal DC2+ of the second battery pack DC2 is connected to the first terminal of the fourth capacitor C4, the upper arm of the fourth bridge arm 204, the upper arm of the fifth bridge arm 205, and the upper arm of the sixth bridge arm 206; the first battery pack... The negative terminal DC1- of DC1 and the negative terminal DC2- of the second battery pack DC2 are all connected to the second terminal of the third capacitor C3, the second terminal of the fourth capacitor C4, the lower arm of the fourth bridge arm 204, the lower arm of the fifth bridge arm 205, and the lower arm of the sixth bridge arm 206. That is, the negative terminal DC1- of the first battery pack DC1 and the negative terminal DC2- of the second battery pack DC2 are connected to the negative terminal DC- of the battery 100. The negative terminal DC- of the battery 100 is also connected to the second terminal of the third capacitor C3, the second terminal of the fourth capacitor C4, the lower arm of the fourth bridge arm 204, the lower arm of the fifth bridge arm 205, and the lower arm of the sixth bridge arm 206. Among them, the upper arm of the fourth bridge arm 204 and the upper arm of the fifth bridge arm 205 are connected to each other, and the upper arm of the fifth bridge arm 205 and the upper arm of the sixth bridge arm 206 are connected through the second DC contactor KM2; the lower arm of the fourth bridge arm 204, the lower arm of the fifth bridge arm 205 and the lower arm of the sixth bridge arm 206 are connected to each other.

[0057] With the above connection method, when the battery 100 has a self-heating requirement, the DC contactor KM2 is disconnected, controlling the on / off state of the upper and lower bridge arms in the second switching circuit 220, forming a discharge path and a charging path, as shown in the following example:

[0058] The switching states of the upper arm of the fourth bridge arm 204, the upper arm of the fifth bridge arm 205, and the upper arm of the sixth bridge arm 206 are off, off, and on, respectively; the switching states of the lower arm of the fourth bridge arm 204, the lower arm of the fifth bridge arm 205, and the lower arm of the sixth bridge arm 206 are on, on, and off, respectively. The discharge path is the second battery pack DC2, the upper arm of the sixth bridge arm 206, and one phase of the second three-phase motor 302 connected to the connection point between the upper and lower arms of the sixth bridge arm 206. The charging path is one phase of the second three-phase motor 302 connected to the connection point between the upper and lower arms of the fifth bridge arm 205, one phase of the second three-phase motor 302 connected to the connection point between the upper and lower arms of the fourth bridge arm 204, the lower arm of the fifth bridge arm 205, the lower arm of the fourth bridge arm 204, and the negative terminal DC- of the battery 100. The process of the second battery pack DC2 discharging to charge DC1 was realized.

[0059] The switching states of the upper arm of the fourth bridge arm 204, the upper arm of the fifth bridge arm 205, and the upper arm of the sixth bridge arm 206 are off, on, and off, respectively; the switching states of the lower arm of the fourth bridge arm 204, the lower arm of the fifth bridge arm 205, and the lower arm of the sixth bridge arm 206 are on, off, and on, respectively. The discharge path is the first battery pack DC1, the upper arm of the fifth bridge arm 205, and one phase of the second three-phase motor 302 connected to the connection point between the upper and lower arms of the fifth bridge arm 205. The charging path is one phase of the second three-phase motor 302 connected to the connection point between the upper and lower arms of the sixth bridge arm 206, one phase of the second three-phase motor 302 connected to the connection point between the upper and lower arms of the fourth bridge arm 204, the lower arm of the sixth bridge arm 206, the lower arm of the fourth bridge arm 204, and the negative terminal DC- of the battery 100. The process of discharging DC1 to charge DC2 in the first battery pack was realized.

[0060] When the battery 100 requires self-heating, the first DC contactor KM1 and the second DC contactor KM2 can be simultaneously disconnected, and the first switching circuit 210 and the second switching circuit 220 can simultaneously form a charging path and a discharging path, thereby achieving self-heating of the battery and improving heating efficiency. Alternatively, either the first DC contactor KM1 or the second DC contactor KM2 can be disconnected while the other is closed, and the first switching circuit 210 or the second switching circuit 220 can be correspondingly controlled to form a charging path and a discharging path, thereby achieving self-heating of the battery.

[0061] Furthermore, when battery 100 requires self-heating, disconnecting the first DC contactor KM1 and the second DC contactor KM2 allows one arm of the first switching circuit 210 (first arm 201) and two arms of the second switching circuit 220 (fourth arm 204 and fifth arm 205) to be connected to the positive terminal DC1+ of the first battery pack DC1, and two arms of the first switching circuit 210 (second arm 202 and third arm 203) and one arm of the second switching circuit 220 (sixth arm 206) to be connected to the positive terminal DC2+ of the second battery pack DC2. This ensures uniform heat distribution between the first switching circuit 210 and the second switching circuit 220, and between the first battery pack DC1 and the second battery pack DC2 during battery heating. Moreover, the separate capacitors at both ends of the first DC contactor KM1 and the second DC contactor KM2 effectively prevent surge voltage damage to the first switching circuit 210 and the second switching circuit 220 in case of heating function failure.

[0062] In one embodiment, such as Figure 5As shown, a structural diagram of another battery self-heating circuit is provided. The battery self-heating circuit also includes a control circuit 400, which is connected to the battery 100 and the switching circuit 200 respectively. The control circuit 400 is used to acquire the temperature data of the battery 100 and determine whether the battery 100 has a self-heating requirement based on the temperature data. The control circuit 400 is also used to acquire the current data of the switching circuit 200 and control the switching element in the switching circuit 200 to open and close when the battery has a self-heating requirement, so as to form a discharge path and a charging path.

[0063] In one embodiment, the control circuit 400 is also connected to the three-phase motor 300. The control circuit 400 is also used to acquire motor parameters. The control circuit 400 is also used to control the switching elements in the switching circuit 200 to form a discharge path and a charging path when the battery has a self-heating requirement.

[0064] In one embodiment, the battery self-heating circuit further includes a power supply 500 and a CAN communication device 600. The power supply 500 is connected to the control circuit 400 and is used to provide power to the control circuit 400. The CAN communication device 600 is connected to the control circuit 400 and is used to send commands to the control circuit 400.

[0065] In one embodiment, when the battery 100 has a self-heating requirement, the control circuit 400 controls the switching elements in the switching circuit 200 to form a discharge path and a charging path based on the Space Vector Pulse Width Modulation (SVPWM) algorithm.

[0066] The control circuit 400 controls the three-phase motor 300. The control circuit 400 includes a control board and a drive board, which are connected to each other. The drive board is connected to the switching circuit 200. The control board includes various control strategies and protection thresholds, signal acquisition modules, drive modules, and communication modules. A TMS320F28335 DSP (Digital Signal Processing) chip can be selected. The drive board can use a 5.7kV, 6A single-channel flexible isolated gate driver (model 1ED3461MU12), which features de-protection and protection functions, drive optocouplers, active Miller clamping, adjustable DESAT, and soft-shutdown functions with UL1577 certification, providing reliable protection for the high power density operation of the battery self-heating circuit. The switching elements refer to the power devices and DC contactors KM in the bridge circuit. The power supply 500 provides low-voltage power to the control board, offering a range of 9V to 36V. The control circuit 400 is connected to the power supply 500, the CAN communication device 600, and the three-phase motor 300 through different keys P1 in the 3-core high-current aviation plug-in 3 or different keys P2 in the 12-core aviation plug-in 3.

[0067] Optionally, the battery self-heating circuit includes multiple control circuits 400, which are connected to multiple switching circuits 200 and multiple three-phase motors 300 corresponding to each of the multiple switching circuits 200; the multiple control circuits 400 are also connected to the battery 100.

[0068] For example, there are two control circuits 400. For easy distinction, they are divided into a first control circuit 410 and a second control circuit 420. The first control circuit 410 includes a first control board 411 and a first drive board 412, and the second control circuit 420 includes a second control board 421 and a second drive board 422.

[0069] The first control board 411 is connected to the first drive board 412 and is used to control the output voltage of the first drive board 412 to the gate of the power device in the first switching circuit 210 based on the space vector pulse width modulation algorithm. The first control board 411 is connected to the battery management system in the battery pack and is used to obtain the temperature of the battery 100 through the temperature sensor in the battery management system. The first control board 411 is also connected to the first three-phase motor 301 and is used to obtain the temperature signal and resolver signal of the first three-phase motor 301 through the temperature sensor and the resolver sensor. The first control board 411 is also used to obtain the current signals of the first bridge arm 201, the second bridge arm 202, and the third bridge arm 203 through the first temperature sensor H1, the second temperature sensor H2, and the third temperature sensor H3, respectively. The first control board 411 is also connected to the power supply 500 and the CAN communication device 600.

[0070] The second control board 421 is connected to the second drive board 422 and is used to control the output voltage of the second drive board 422 to the gate of the power device in the second switching circuit 220 based on the space vector pulse width modulation algorithm. The second control board 421 is also connected to the battery management system in the battery pack and is used to acquire temperature data of the battery 100 through the temperature sensor in the battery management system. The second control board 421 is also connected to the second three-phase motor 302 and is used to acquire the temperature signal and resolver signal of the second three-phase motor 302 through the temperature sensor and resolver sensor. The second control board 421 is also used to acquire the current signals of the fourth bridge arm 204, the fifth bridge arm 205, and the sixth bridge arm 206 through the fourth temperature sensor H4, the fifth temperature sensor H5, and the sixth temperature sensor H6, respectively. The second control board 421 is also connected to the power supply 500 and the CAN communication device 600.

[0071] In addition, the first control board 411 and the second control board 421 are also used to implement other functions for the first switching circuit 210 and the second switching circuit 220, such as power device operation feedback, over- and under-voltage protection, temperature detection protection, voltage detection, control of the switching on and off of the DC contactor, forward and reverse control, PWM (Pulse width modulation) signal, and other signals.

[0072] In summary, the most detailed battery self-heating circuit is as follows: Figure 5 As shown, this application integrates battery heating technology with the control circuit of a three-phase motor, achieving spatial integration and effective electrical isolation in the electrical topology. While ensuring safe and reliable operation, it allows the first three-phase motor 301 and the second three-phase motor 302 to simultaneously exchange energy with the battery 100, thereby heating the battery 100. This significantly shortens heating time and improves heating efficiency. Furthermore, the aforementioned battery self-heating circuit can provide heating for the battery 100 throughout the entire lifecycle of the electric vehicle, including during charging and driving, without increasing costs.

[0073] In one embodiment, such as Figure 6 The diagram shows a flowchart of a battery self-heating method. When an electric vehicle equipped with the aforementioned battery self-heating circuit is in motion or stationary state, the battery self-heats as follows:

[0074] In step S1, the first control board 411 and the second control board 421 acquire the temperature data of the battery 100 in real time and determine whether the temperature data is lower than a preset temperature threshold. If yes, proceed to step S2; otherwise, continue with step S1.

[0075] Step S2: Enter the battery self-heating mode, that is, the first control board 411 and the second control board 421 respectively control the first DC contactor KM1 and the second DC contactor KM2 to disconnect, and respectively control the first drive board 412 and the second drive board 422 to provide voltage to the gate of the power device based on the SVPWM algorithm, thereby changing the switching state of the power device.

[0076] In step S3, the first control board 411 and the second control board 421 acquire, in real time, the temperature signals and resolver signals of the first three-phase motor 301 and the second three-phase motor 302, as well as the current signals of the first switching circuit 210 and the second switching circuit 220. The first switching circuit 210 and the second switching circuit 220 are controlled according to constraints, i.e., the output voltages of the first drive board 412 and the second drive board 422 are adjusted respectively. These constraints include torque constraints, voltage constraints, and current constraints. When the resolver signal is less than a preset resolver threshold, it indicates that the torque constraint is met; when the current signal meets the current threshold, it indicates that the voltage and current constraints are met.

[0077] In step S4, the first control board 411 and the second control board 421 control the first drive board 412 and the second drive board 422 respectively based on the SVPWM algorithm, so that the power devices are switched on and off at high frequency, thereby realizing the energy exchange between the first battery pack DC1 and the second battery pack DC2 and the first three-phase motor 301 and the second three-phase motor 302, which heats the battery 100. The first battery pack DC1 and the second battery pack DC2 charge and discharge through the discharge path and the charging path, so that the polarization reaction is generated inside the first battery pack DC1 and the second battery pack DC2, generating heat to heat the battery 100.

[0078] In step S5, the first control board 411 and the second control board 421 continue to acquire the temperature data of the battery 100 in real time and determine whether the temperature data is lower than the preset temperature threshold. If yes, then step S2 is executed; otherwise, the heating step is terminated to ensure that the battery 100 operates under optimal range and charge / discharge performance.

[0079] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0080] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

[0081] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0082] Furthermore, in this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, for example, two, three, etc., unless otherwise explicitly specified.

[0083] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

Claims

1. A battery self-heating circuit, characterized in that, The battery self-heating circuit includes a battery, a switching circuit, and a three-phase motor. The battery comprises two battery packs: a first battery pack and a second battery pack. The positive terminals of the first and second battery packs are disconnected, while their negative terminals are connected. The switching circuit is a bridge circuit, comprising a first arm, a second arm, and a third arm. Each of the first, second, and third arms is connected to one phase of the three-phase motor. The first battery pack is connected to the first arm, and the second battery pack is connected to all three arms. When the battery has a self-heating requirement, a discharge path is formed between the target battery pack, the switching circuit, and the three-phase motor, and a charging path is formed between the first battery pack, the second battery pack, the switching circuit, and the three-phase motor. The target battery pack is one of the first battery pack and the second battery pack; the discharge path is used for the first battery pack and the second battery pack to alternately discharge to one phase of the three-phase motor through the discharge path; the charging path is used for the other two phases of the three-phase motor to charge the first battery pack and the second battery pack through the charging path.

2. The battery self-heating circuit according to claim 1, characterized in that, The connection point between the upper and lower bridge arms of the first bridge arm, the connection point between the upper and lower bridge arms of the second bridge arm, and the connection point between the upper and lower bridge arms of the third bridge arm are respectively connected to one phase of the three-phase motor. The positive terminal of the first battery pack is connected to the upper arm of the first bridge arm; the positive terminal of the second battery pack is connected to the upper arm of the first bridge arm, the upper arm of the second bridge arm, and the upper arm of the third bridge arm; the negative terminals of the first battery pack and the second battery pack are connected to the lower arm of the first bridge arm, the lower arm of the second bridge arm, and the lower arm of the third bridge arm.

3. The battery self-heating circuit according to claim 2, characterized in that, A DC contactor is provided between the upper arm of the first bridge arm and the upper arm of the second bridge arm.

4. The battery self-heating circuit according to any one of claims 1 to 3, characterized in that, A capacitor is provided between the positive and negative terminals of the battery.

5. The battery self-heating circuit according to any one of claims 1 to 3, characterized in that, The battery self-heating circuit includes multiple switching circuits and multiple three-phase motors corresponding to each of the multiple switching circuits. The battery is connected to each of the switching circuits, and each of the switching circuits is connected to the corresponding three-phase motor.

6. The battery self-heating circuit according to any one of claims 1 to 3, characterized in that, The battery self-heating circuit also includes a control circuit, which is connected to the battery and the switch circuit respectively. The control circuit is used to acquire the temperature data of the battery and determine whether the battery has a self-heating requirement based on the temperature data. The control circuit is also used to acquire the current data of the switching circuit, and when the battery has a self-heating requirement, control the switching element in the switching circuit to form the discharge path and the charging path.

7. The battery self-heating circuit according to claim 6, characterized in that, The control circuit is also connected to the three-phase motor. The control circuit is also used to acquire motor parameters; The control circuit is also used to control the switching elements in the switching circuit to form the discharge path and the charging path when the battery has a self-heating requirement.

8. The battery self-heating circuit according to claim 7, characterized in that, When the battery has a self-heating requirement, the control circuit controls the switching elements in the switching circuit to form the discharge path and the charging path based on the space vector pulse width modulation algorithm.

9. The battery self-heating circuit according to claim 7, characterized in that, The control circuit is specifically used to control the on / off state of the switching element in the switching circuit when the battery has a self-heating requirement, so that the discharge path is formed between the first battery pack, the switching circuit and the three-phase motor, and the charging path is formed between the first battery pack, the second battery pack, the switching circuit and the three-phase motor. The current in the discharge path flows sequentially through the positive terminal of the first battery pack, the switching circuit, and one phase of the three-phase motor; the current in the charging path flows sequentially through the other two phases of the three-phase motor, the switching circuit, the negative terminal of the first battery pack, and the negative terminal of the second battery pack, so as to enable the first battery pack to discharge and charge the second battery pack.

10. The battery self-heating circuit according to claim 7, characterized in that, The control circuit is specifically used to control the on / off state of the switching element in the switching circuit when the battery has a self-heating requirement, so that the discharge path is formed between the second battery pack, the switching circuit and the three-phase motor, and the charging path is formed between the first battery pack, the second battery pack, the switching circuit and the three-phase motor. The current in the discharge path flows sequentially through the positive terminal of the second battery pack, the switching circuit, and one phase of the three-phase motor; the current in the charging path flows sequentially through the other two phases of the three-phase motor, the switching circuit, the negative terminal of the first battery pack, and the negative terminal of the second battery pack, so as to enable the second battery pack to discharge and charge the first battery pack.

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