Battery heating system and electric vehicle

Abstract

A battery heating system (10) and an electric vehicle (1000). The system (10) is a power battery pack comprising a first battery pack (1) and a second battery pack (2) connected in series, and a center line is drawn at the series connection point (A) between the first battery pack (1) and the second battery pack (2). The power battery pack, n buck-boost inverters (3) each comprising an inverter bridge and an inductor, wherein the n inverter bridges are connected in parallel to form a first bus terminal (B) and a second bus terminal (C), and the first bus terminal (B) and the second bus terminal (C) are connected corresponding to the positive and negative electrodes of the power battery pack. One end of the inductor is connected to the midpoint of the corresponding inverter bridge, and the other end of the inductor is connected to the center line, where n is an integer greater than 1. The n buck-boost inverters (3), and a controller (100) connected to the control end of the inverter bridge and configured to perform phase-shift control on the n buck-boost inverters (3) to achieve simultaneous self-heating of the first battery pack (1) and the second battery pack (2).

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This disclosure claims priority to Chinese Patent Application No. 202210472874.1, filed on April 29, 2022, and entitled "BATTERY HEATING SYSTEM AND ELECTRIC VEHICLE," which is incorporated herein by reference in its entirety.

[0002] The present disclosure relates to the technical field of vehicles, and in particular to battery heating systems and electric vehicles. [Background technology]

[0003] A prior art battery internal heating solution is shown in Figure 1. The battery pack includes batteries B1 and B2 and an inductor L as an energy storage element. In one cycle, battery B1 charges inductor L, then inductor L charges battery B2, battery B2 then charges inductor L, and finally inductor L charges battery B1. During the charging and discharging process, the battery's internal resistance generates heat, resulting in battery self-heating. However, during the charging and discharging process, the terminal voltage of the battery pack fluctuates greatly, affecting the stability of powering the load and causing a significant voltage impact on the charging device during charging and self-heating. Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a battery heating system and an electric vehicle that can efficiently heat a power battery pack at low cost, maintain a stable battery pack voltage, ensure high quality when powering a load, and prevent voltage impact on a charging device during charging and self-heating. [Means for solving the problem]

[0005] In a first aspect, one embodiment of the present disclosure provides a battery heating system, including: a power battery pack including a first battery assembly and a second battery assembly, the first battery assembly and the second battery assembly being connected in series with a center line leading to a series connection point between the first battery assembly and the second battery assembly; n buck-boost inverters, each including an inverter bridge and an inductor, the n inverter bridges being connected in parallel to form a first bus terminal and a second bus terminal, the first bus terminal being connected to a positive electrode of the power battery pack, the second bus terminal being connected to a negative electrode of the power battery pack, one terminal of the inductor being connected to a midpoint of the inverter bridge, and the other terminal of the inductor being connected to the center line, where n is an integer greater than 1; and a controller connected to control terminals of the inverter bridges and configured to perform out-of-phase control on the n buck-boost inverters to achieve simultaneous self-heating of the first battery assembly and the second battery assembly.

[0006] In addition, the battery heating system in the embodiment of the present disclosure further has the following additional technical features.

[0007] According to one embodiment of the present disclosure, the inverter bridge includes an upper bridge arm switch tube and a lower bridge arm switch tube. One terminal of the upper bridge arm switch tube is connected to one terminal of the lower bridge arm switch tube, with the connection point being the midpoint of the inverter bridge. The other terminal of the upper bridge arm switch tube is connected to a first bus terminal, and the other terminal of the lower bridge arm switch tube is connected to a second bus terminal. The controller controls a number of upper bridge arm switch tubes and b number of lower bridge arm switch tubes to be turned on simultaneously, where a and b are both positive integers less than n, and a+b=n.

[0008] According to one embodiment of the present disclosure, the absolute value of ab is less than or equal to 1.

[0009] According to one embodiment of the present disclosure, the controller is specifically configured to control the turn-on angle of each upper bridge arm switch tube to be out of phase by 2*Π / n, and to control the upper bridge arm switch tube and the lower bridge arm switch tube in the same inverter bridge to be turned on complementarily in each on / off cycle, where Π represents one-half of the on / off cycle.

[0010] According to one embodiment of the present disclosure, the first bus terminal is connected to the positive electrode of the first battery assembly, and the second bus terminal is connected to the negative electrode of the second battery assembly. When n is 3, the three buck-boost inverters are designated as a first buck-boost inverter, a second buck-boost inverter, and a third buck-boost inverter, respectively. The first buck-boost inverter includes a first switch tube, a fourth switch tube, and a third inductor. The second buck-boost inverter includes a second switch tube, a fifth switch tube, and a second inductor. The third buck-boost inverter includes a third switch tube, a sixth switch tube, and a first inductor. The first switch tube, the second switch tube, and the third switch tube are all upper bridge arm switch tubes. The fourth switch tube, the fifth switch tube, and the sixth switch tube are all lower bridge arm switch tubes. In each on / off period, the controller controls the first switch tube, the third switch tube, and the fifth switch tube to be turned on and the second switch tube, the fourth switch tube, and the sixth switch tube to be turned off in a first timing sequence, where the time length of the first timing sequence is Π / 3; and controls the first switch tube, the fifth switch tube, and the sixth switch tube to be turned on and the second switch tube, the third switch tube, and the fourth switch tube to be turned off in a second timing sequence, where the second timing sequence is the same as the first timing sequence. a third timing sequence, the first switch tube, the second switch tube, and the sixth switch tube being turned on, and a third timing sequence, the fourth switch tube, and the fifth switch tube being turned off, wherein the third timing sequence is adjacent to the second timing sequence, the time length of the third timing sequence is Π / 3; and a fourth timing sequence, the first switch tube, the third switch tube, and the sixth switch tube being turned on, and a fourth timing sequence, the ...and the fifth switch tube to be turned off, where the fourth timing sequence is adjacent to the third timing sequence and the time length of the fourth timing sequence is Π / 3; in the fifth timing sequence, the second switch tube, the third switch tube, and the fourth switch tube are turned on and the first switch tube, the fifth switch tube, and the sixth switch tube are turned off, where the fifth timing sequence is adjacent to the fourth timing sequence and the time length of the fifth timing sequence is Π / 3; and in the sixth timing sequence, the third switch tube, the fourth switch tube, and the fifth switch tube are turned on and the first switch tube, the second switch tube, and the sixth switch tube are turned off, where the sixth timing sequence is adjacent to the fifth timing sequence and the time length of the sixth timing sequence is Π / 3.

[0011] According to one embodiment of the present disclosure, the controller is further specifically configured to control the net on-time of each switch tube to be equal to the net off-time.

[0012] According to one embodiment of the present disclosure, the system further includes a switch assembly connected between the centerline and the other terminal of all of the inductors and configured to control connection and disconnection of the centerline to and from the inductors.

[0013] According to one embodiment of the present disclosure, the system further includes a heat transport assembly disposed between the inductor and the power battery pack and configured to transfer heat generated by the inductor to the power battery pack.

[0014] According to one embodiment of the present disclosure, the heat transport assembly includes a heat pump loop, which includes a heat transport medium and a heat pump, and the heat pump is configured to transfer absorbed heat generated by the inductor to the power battery pack when the heat transport medium flows through the power battery pack by controlling the heat transport medium to flow through the heat pump loop.

[0015] According to one embodiment of the present disclosure, the direction and magnitude of current flow in the n inductors included in the n buck-boost inverters are the same.

[0016] In a second aspect, the present disclosure provides an electric vehicle including the battery heating system described above.

[0017] In a battery heating system and electric vehicle according to an embodiment of the present disclosure, a power battery pack including a first battery assembly and a second battery assembly is arranged, and n buck-boost inverters, each including an inverter bridge and an inductor, are arranged. A center line is drawn to the series connection point between the first battery assembly and the second battery assembly. One terminal of the inductor is connected to the midpoint of the corresponding inverter bridge, and the other terminal of the inductor is connected to the center line. A controller performs phase-shift control on the inverter bridge to achieve simultaneous self-heating of the first battery assembly and the second battery assembly, maintain a stable battery pack voltage, ensure high quality when powering the load, and prevent voltage impact on the charging device during charging and self-heating. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a circuit diagram of a battery heating system according to the prior art. [Figure 2] 1 is a schematic structural diagram of a battery heating system according to an embodiment of the present disclosure. [Figure 3] FIG. 1 is a circuit diagram of an example battery heating system according to the present disclosure. [Figure 4]FIG. 10 is a circuit diagram of another example of a battery heating system according to the present disclosure. [Figure 5] 5 is a schematic diagram illustrating the operation of the example battery heating system shown in FIG. 4 according to the present disclosure. [Figure 6] 5 is another schematic diagram illustrating the operation of the example battery heating system shown in FIG. 4 according to the present disclosure. [Figure 7] FIG. 2 is a schematic structural diagram of a battery heating system according to another embodiment of the present disclosure. [Figure 8] FIG. 10 is a circuit diagram of a further example of a battery heating system according to the present disclosure. [Figure 9] 1 is a block diagram illustrating the structure of an electric vehicle according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0019] The battery heating system and electric vehicle according to the embodiments of the present disclosure will be described with reference to the accompanying drawings, in which the same or similar elements or elements having the same or similar functions are designated with the same or similar reference numerals throughout the description. The embodiments described with reference to the accompanying drawings are illustrative and should not be understood as limitations on the present disclosure.

[0020] The present disclosure provides a battery heating system and an electric vehicle.

[0021] FIG. 2 is a schematic structural diagram of a battery heating system according to an embodiment of the present disclosure.

[0022] 2, the battery heating system 10 includes a power battery pack, n buck-boost inverters 3, and a controller 100. The power battery pack includes a first battery assembly 1 and a second battery assembly 2.

[0023] Specifically, a first battery assembly 1 and a second battery assembly 2 are connected in series, with a center line extending to a series connection point A between the first battery assembly 1 and the second battery assembly 2. Each buck-boost inverter 3 includes an inverter bridge and an inductor. n inverter bridges are connected in parallel to form a first bus terminal B and a second bus terminal C, with the first bus terminal B connected to the positive pole of the power battery pack and the second bus terminal C connected to the negative pole of the power battery pack. One terminal of the inductor is connected to the midpoint of the corresponding inverter bridge, and the other terminal of the inductor is connected to the center line. n is an integer greater than 1. A controller 100 is connected to the control terminals of the inverter bridges and configured to perform phase-shift control on the n buck-boost inverters 3 to achieve simultaneous self-heating of the first battery assembly 1 and the second battery assembly 2.

[0024] Unlike the first battery assembly and the second battery assembly in the prior art shown in FIG. 1, in which the self-heating current flows alternately, in this embodiment, during the self-heating process, the current flows through the first battery assembly 1 and the second battery assembly 2 simultaneously, thereby realizing simultaneous self-heating of the first battery assembly and the second battery assembly.

[0025] The period of the drive signal output by the controller 100 to each bridge arm switch tube in each buck-boost inverter is T, and the phase of each drive signal differs sequentially by T / n*k, thereby realizing phase shift control, where k is the number of bridge arm switch tubes in each buck-boost inverter.

[0026] The embodiment shown in Figure 2 is a specific embodiment in which the first bus terminal B is connected to the positive electrode of the first battery assembly 1 and the second bus terminal C is connected to the negative electrode of the second battery assembly 2. The first battery assembly 1 and the second battery assembly 2 can be separate battery packs or the same battery pack. Of course, each battery pack can be obtained by connecting multiple battery cores in series or parallel, and the number of battery cores connected in series or parallel can be the same or different. The current flow direction and magnitude in the n inductors included in the n buck-boost inverters are the same.

[0027] The inverter bridge includes an upper bridge arm switch tube and a lower bridge arm switch tube. One terminal of the upper bridge arm switch tube is connected to one terminal of the lower bridge arm switch tube, with the connection point being the midpoint of the inverter bridge. The other terminal of the upper bridge arm switch tube is connected to a first bus terminal B, and the other terminal of the lower bridge arm switch tube is connected to a second bus terminal C. The controller controls a upper bridge arm switch tubes and b lower bridge arm switch tubes to be turned on simultaneously, where a and b are both positive integers less than n, and a+b=n.

[0028] During the charging and discharging process of the battery pack, the internal resistance of the battery pack consumes energy when current flows, and the consumed energy can be used to heat the battery pack. Therefore, the controller 100 controls the on / off of the upper bridge arm switch tubes and the lower bridge arm switch tubes in the n inverter bridges, and performs phase-shift control to alternately enable the first battery assembly 1 to charge the second battery assembly 2 and enable the second battery assembly 2 to charge the first battery assembly 1. Therefore, current flows simultaneously through the first battery assembly 1 and the second battery assembly 2, with the current flow directions opposite to each other, thereby achieving simultaneous self-heating of the first battery assembly 1 and the second battery assembly 2 and improving heating efficiency. Simultaneous self-heating stabilizes the total voltage during the heating process, ensuring high quality when powering the load and preventing voltage impact on the charging device during charging and self-heating.

[0029] In particular, the controller 100 is connected to the control terminals of the upper and lower bridge arm switch tubes, respectively, and is specifically configured to control the on angles of the upper and lower bridge arm switch tubes in each inverter bridge to be phase-shifted by 2*Π / n, and to control the upper and lower bridge arm switch tubes in the same inverter bridge to be complementarily turned on in each on / off cycle, where Π represents half the on / off cycle. In each on / off cycle, the on time (duty ratio) of each bridge arm varies from 0 to 1. Specifically, if the upper and lower switch tubes in the same bridge arm are complementary, the on time can be adjusted arbitrarily according to the desired waveform output in actual use.

[0030] The controller 100 is further configured to control the net on-time of each switch tube to be equal to the net off-time, i.e., after multiple on / off cycles for a certain period, the total on-time and off-time of each switch tube should be equal, so that the amount of electricity discharged by the first battery assembly 1 is the same as the amount of electricity discharged by the second battery assembly 2, and the first battery assembly 1 is charged with the same amount of electricity as that charged into the second battery assembly 2, ensuring equalization of the power of the first battery assembly 1 and the second battery assembly 2.

[0031] It should be understood that in actual use, the dead time needs to be taken into consideration, and the control mode by the controller 100 can be adaptively adjusted according to the dead time.

[0032] In one example of the present disclosure, when n is 2, the circuit diagram of the battery heating system 10 is as shown in Figure 3. The battery heating system 10 according to an embodiment of the present disclosure will be described in detail with reference to the example shown in Figure 3.

[0033] In this example, the duty ratio of each bridge arm is fixed (e.g., 0.5), the first bus terminal B is connected to the positive pole of the first battery assembly 1, and the second bus terminal C is connected to the negative pole of the second battery assembly 2. When n is 2, the two buck-boost inverters 3 are designated as the first buck-boost inverter 3 and the second buck-boost inverter 3, respectively. The first buck-boost inverter 3 includes a first switch tube T1, a fourth switch tube T4, and a third inductor Lw. The second buck-boost inverter 3 includes a second switch tube T2, a fifth switch tube T5, and a second inductor Lv. The first switch tube T1 and the second switch tube T2 are both upper bridge arm switch tubes. The fourth switch tube T4 and the fifth switch tube T5 are both lower bridge arm switch tubes. In each on / off cycle, the controller 100: In a first timing sequence, the first switch tube T1 and the fifth switch tube T5 are controlled to be turned on, and the second switch tube T2 and the fourth switch tube T4 are controlled to be turned off, where the time length of the first timing sequence is Π / 2.

[0034] At this stage, the first battery assembly 1 discharges to the third inductor Lw through the first switch tube T1 for energy storage, and the discharge current i 11 is i, where i is the current flowing through the single-phase bridge arm, and the current flow direction is defined as the positive direction. The second inductor Lv discharges the energy stored therein to the second battery assembly 2 through the fifth switch tube T5 to charge the second battery assembly 2, where the charging current i of the second battery assembly 2 is 12 is -i.

[0035] The controller 100 is configured to control the second switch tube T2 and the fourth switch tube T4 to be turned on and the first switch tube T1 and the fifth switch tube T5 to be turned off in a second timing sequence, where the second timing sequence is adjacent to the first timing sequence, and the time length of the second timing sequence is Π / 2.

[0036] At this stage, the first battery assembly 1 discharges to the second inductor Lv through the second switch tube T2 for energy storage, where the discharge current i 21 The third inductor Lw discharges the energy stored therein to the second battery assembly 2 through the fourth switch tube T4 to charge the second battery assembly 2, where the charging current i 22 is -i.

[0037] Therefore, in stages 0 to Π, the first battery assembly 1 continuously discharges current, and the second battery assembly 2 continuously charges.

[0038] The controller 100 is configured to control the first switch tube T1 and the fifth switch tube T5 to be turned on and the second switch tube T2 and the fourth switch tube T4 to be turned off in a third timing sequence, the third timing sequence being adjacent to the second timing sequence, and the time length of the third timing sequence is Π / 2.

[0039] At this stage, the third inductor Lw discharges the energy stored therein through the first switch tube T1 to charge the first battery assembly 1, where the charging current i 31 The second battery assembly 2 discharges to the second inductor Lv through the fifth switch tube T5 for energy storage, where the discharge current i 32 is i.

[0040] The controller 100 controls the second switch tube T2 and the fourth switch tube T4 to be turned on and the first switch tube T1 and the fifth switch tube T5 to be turned off in a fourth timing sequence, where the fourth timing sequence is adjacent to the third timing sequence, and the time length of the fourth timing sequence is Π / 2.

[0041] At this stage, the second inductor Lw discharges the energy stored therein through the second switch tube T2 to charge the first battery assembly 1, where the charging current i 41 The second battery assembly 2 discharges to the third inductor Lw through the fourth switch tube T4 for energy storage, where the discharge current i 42 is i.

[0042] Therefore, in stages Π to 2Π, the second battery assembly 2 continuously discharges current and the first battery assembly 1 continuously charges.

[0043] In the above stage, the first battery assembly 1 and the second battery assembly 2 have currents that are completely out of phase with each other by 180 degrees, so these currents flow in opposite directions and cancel each other out. When the first battery assembly 1 is discharged, the second battery assembly 2 is charged, and the voltage changes of the two cancel each other out, so the terminal voltage of the power battery pack remains stable.

[0044] In another example of the present disclosure, when n is 3, the circuit diagram of the battery heating system 10 is as shown in Figure 4. The battery heating system 10 according to an embodiment of the present disclosure will be described in detail with reference to the example shown in Figure 4.

[0045] In this example, the duty ratio of each bridge arm is fixed (e.g., 0.5), the first bus terminal B is connected to the positive pole of the first battery assembly 1, and the second bus terminal C is connected to the negative pole of the second battery assembly 2. When n is 3, the three buck-boost inverters 3 are designated as the first buck-boost inverter 3, the second buck-boost inverter 3, and the third buck-boost inverter 3, respectively. The first buck-boost inverter 3 includes a first switch tube T1, a fourth switch tube T4, and a third inductor Lw. The second buck-boost inverter 3 includes a second switch tube T2, a fifth switch tube T5, and a second inductor Lv. The third buck-boost inverter 3 includes a third switch tube T3, a sixth switch tube T6, and a first inductor Lu. The first switch tube T1, the second switch tube T2, and the third switch tube T3 are all upper bridge arm switch tubes. The fourth switch tube T4, the fifth switch tube T5, and the sixth switch tube T6 are all lower bridge arm switch tubes. The specific control mode of the controller 100 for the first switch tube T1, the second switch tube T2, the third switch tube T3, the fourth switch tube T4, the fifth switch tube T5, and the sixth switch tube T6 is shown in FIG. 5. In each on / off cycle, the controller 100: In a first timing sequence, the first switch tube T1, the third switch tube T3, and the fifth switch tube T5 are turned on, and the second switch tube T2, the fourth switch tube T4, and the sixth switch tube T6 are turned off, and the time length of the first timing sequence is Π / 3.

[0046] At this stage, the first battery assembly 1 discharges to the first inductor Lu and the third inductor Lw through the first switch tube T1 and the third switch tube T3 for energy storage, and the discharge current i of the first battery assembly 1 11is 2*i, where i is the current flowing through the single-phase bridge arm, and the current flow direction is defined as the positive direction. The second inductor Lv discharges the energy stored therein to the second battery assembly 2 through the fifth switch tube T5 to charge the second battery assembly 2, where the charging current i of the second battery assembly 2 is 12 is -i.

[0047] The controller 100 is configured to control the first switch tube T1, the fifth switch tube T5, and the sixth switch tube T6 to be turned on and the second switch tube T2, the third switch tube T3, and the fourth switch tube T4 to be turned off in a second timing sequence, the second timing sequence being adjacent to the first timing sequence, and the time length of the second timing sequence being Π / 3.

[0048] At this stage, the first battery assembly 1 continuously discharges into the third inductor Lw through the first switch tube T1 for energy storage, where the discharge current i 21 The first inductor Lu and the second inductor Lv discharge the energy stored therein to the second battery assembly 2 through the fifth switch tube T5 and the sixth switch tube T6 to charge the second battery assembly 2, where the charging current i 22 is -2*i.

[0049] The controller 100 is configured to control the first switch tube T1, the second switch tube T2, and the sixth switch tube T6 to be turned on and the third switch tube T3, the fourth switch tube T4, and the fifth switch tube T5 to be turned off in a third timing sequence, where the third timing sequence is adjacent to the second timing sequence, and the time length of the third timing sequence is Π / 3.

[0050] At this stage, the first battery assembly 1 discharges to the second inductor Lv and the third inductor Lw through the first switch tube T1 and the second switch tube T2 for energy storage, where the discharge current i 31 The first inductor Lu discharges the energy stored therein to charge the second battery assembly 2, where the charging current i 32 is -i.

[0051] Therefore, in stages 0 to Π, the first battery assembly 1 continuously discharges current and the second battery assembly 2 continuously charges.

[0052] The controller 100 is configured to control the second switch tube T2, the fourth switch tube T4, and the sixth switch tube T6 to be turned on and the first switch tube T1, the third switch tube T3, and the fifth switch tube T5 to be turned off in a fourth timing sequence, where the fourth timing sequence is adjacent to the third timing sequence, and the time length of the fourth timing sequence is Π / 3.

[0053] At this stage, the second inductor Lw discharges the energy stored therein through the second switch tube T2 to charge the first battery assembly 1, where the charging current i 41 The second battery assembly 2 discharges to the first inductor Lu and the third inductor Lw through the fourth switch tube T4 and the sixth switch tube T6 for energy storage, where the discharge current i of the second battery assembly 2 is 42 is 2*i.

[0054] The controller 100 is configured to control the second switch tube T2, the third switch tube T3, and the fourth switch tube T4 to be turned on and the first switch tube T1, the fifth switch tube T5, and the sixth switch tube T6 to be turned off in a fifth timing sequence, where the fifth timing sequence is adjacent to the fourth timing sequence, and the time length of the fifth timing sequence is Π / 3.

[0055] At this stage, the first inductor Lu and the second inductor Lv discharge the energy stored therein through the second switch tube T2 and the third switch tube T3 to charge the first battery assembly 1, where the charging current i 51 The second battery assembly 2 discharges to the third inductor Lw through the fourth switch tube T4 for energy storage, where the discharge current i 52 is i.

[0056] The controller 100 is configured to control the third switch tube T3, the fourth switch tube T4, and the fifth switch tube T5 to be turned on and the first switch tube T1, the second switch tube T2, and the sixth switch tube T6 to be turned off in a sixth timing sequence, where the sixth timing sequence is adjacent to the fifth timing sequence, and the time length of the sixth timing sequence is Π / 3.

[0057] At this stage, the first inductor Lu discharges the energy stored therein through the third switch tube T3 to charge the first battery assembly 1, where the charging current i 61 The second battery assembly 2 discharges to the second inductor Lv and the third inductor Lw through the fourth switch tube T4 and the fifth switch tube T5 for energy storage, where the discharge current i 62 is 2*i.

[0058] Therefore, in stages Π to 2Π, the second battery assembly 2 continuously discharges current and the first battery assembly 1 continuously charges.

[0059] In the above steps, the current i1 of the first battery assembly 1 and the current i2 of the second battery assembly 2 are as shown in Figure 6. Since both the first battery assembly 1 and the second battery assembly 2 have currents that are completely out of phase with each other by 180 degrees, it can be seen that the currents flow in opposite directions and cancel each other out. When the first battery assembly 1 is discharged, the second battery assembly 2 is charged, and the voltage changes of both cancel each other out, so the terminal voltage of the power battery pack remains stable.

[0060] In the above embodiments, the operation process and beneficial effects of the self-heating system are respectively described using an example where n is 2 and an example where n is 3. Those skilled in the art will understand that n may be other integer values ​​greater than 1, for example, n=4, 5, or 6.

[0061] To further improve the stability of the terminal voltage of the power battery pack, the absolute value of ab may be set to |ab|≦1. That is, the difference between a and b is within 1. In particular, when n is an even number, a=b. In this case, the charging current and discharging current of the first battery assembly and the second battery assembly become equal, and the changes in the terminal voltages of the two battery assemblies completely cancel each other out, making the terminal voltage of the power battery pack most stable.

[0062] In one embodiment of the present disclosure, as shown in FIG. 7, the system further includes a switch assembly 5 connected between the centerline and the other terminal of all of the inductors and configured to control the connection and disconnection of the centerline to and from the inductors.

[0063] In particular, by using a switch assembly 5 connected between the center line and the other terminal of each inductor, the topology of the circuit can be controlled to realize various functions according to actual needs. Specifically, when self-heating is required, the switch assembly 5 is controlled to be turned on, thereby connecting the n buck-boost inverters 3 to the center line, and is controlled by the controller 100 to realize self-heating. When self-heating is not required, for example, when the vehicle is being driven to run, charged, or powered on, the switch assembly 5 is controlled to be turned off, thereby disconnecting the n buck-boost inverters 3 from the center line.

[0064] For example, as shown in FIG. 8, the switch assembly 5 may include a function switch 51, where one terminal of the function switch 51 is connected to the center line and the other terminal of the switch assembly 5 is connected to the other terminal of all the inductors, respectively.

[0065] In one embodiment of the present disclosure, the battery heating system 10 is used in an electric vehicle. The electric vehicle includes a motor and a motor controller. The inverter bridge in the motor controller is reused as an inverter bridge, and the motor windings in the motor are reused as inductors. Here, when n is 2, any two-phase inverter bridge in the motor controller 100 of the electric vehicle is reused as two inverter bridges in the multiple buck-boost inverters 3, and any two-phase motor windings in the electric vehicle are reused as two inductors in the multiple buck-boost inverters 3. Alternatively, when n is 3, any three-phase inverter bridge in the motor controller 100 of the electric vehicle is reused as three inverter bridges in the multiple buck-boost inverters 3, and the three-phase motor windings of the electric vehicle are reused as three inductors in the multiple buck-boost inverters 3.

[0066] Thus, vehicle costs are further reduced and vehicle component reuse rates are increased.

[0067] In one embodiment of the present disclosure, the battery heating system 10 further includes a heat transport assembly disposed between the inductor and the power battery pack and configured to transfer heat generated by the inductor to the power battery pack.

[0068] In particular, during the charging and discharging process of the battery pack, the internal resistance of the battery pack and the windings of the circuit both consume energy, causing energy waste and circuit failure. For example, if the temperature of the windings becomes too high, the permanent magnet motor may be demagnetized. Therefore, a heat transport assembly may be further disposed in the electromagnetic heating system to transfer the heat generated by the inductor to the power battery pack, thereby accelerating the heating rate of the battery pack on the one hand and cooling the inductor on the other hand.

[0069] For example, the heat transport assembly may include a heat pump loop including a heat transport medium and a heat pump configured to transfer absorbed heat generated by the inductor to the power battery pack when the heat transport medium flows through the power battery pack by controlling the heat transport medium to flow through the heat pump loop.

[0070] In summary, a battery heating system according to an embodiment of the present disclosure includes a power battery pack including a first battery assembly and a second battery assembly, and n buck-boost inverters, each including an inverter bridge and an inductor. A center line is drawn to the series connection point between the first battery assembly and the second battery assembly. One terminal of the inductor is connected to the midpoint of the corresponding inverter bridge, and the other terminal of the inductor is connected to the center line. A controller controls the inverter bridges in a phase-shifted manner to alternately enable the first battery assembly to charge the second battery assembly and the second battery assembly to charge the first battery assembly. This enables simultaneous self-heating of the first and second battery assemblies, reducing the self-heating cost of the power battery pack and enabling simultaneous self-heating of the first and second battery assemblies, thereby improving heating efficiency. The buck-boost inverters can also be obtained by reusing components from electric vehicles, further reducing vehicle costs. By disposing the heat transport assembly, the heat generated during the operation of the inductor is transferred to the power battery pack, further increasing the heating rate and preventing adverse effects on the vehicle caused by the battery heating system.

[0071] The present disclosure further provides an electric vehicle.

[0072] FIG. 9 is a block diagram illustrating the structure of an electric vehicle according to one embodiment of the present disclosure.

[0073] As shown in FIG. 9, an electric vehicle 1000 includes a battery heating system 10.

[0074] In an electric vehicle according to an embodiment of the present disclosure, a battery heating system includes a power battery pack including a first battery assembly and a second battery assembly, and n buck-boost inverters, each including an inverter bridge and an inductor. A center line is drawn to the series connection point between the first battery assembly and the second battery assembly. One terminal of the inductor is connected to the midpoint of the corresponding inverter bridge, and the other terminal of the inductor is connected to the center line. A controller controls the inverter bridges in a phase-shifted manner to alternately enable the first battery assembly to charge the second battery assembly and the second battery assembly to charge the first battery assembly. This enables simultaneous self-heating of the first and second battery assemblies, reducing the self-heating cost of the power battery pack and enabling simultaneous self-heating of the first and second battery assemblies, thereby improving heating efficiency. The buck-boost inverters can also be obtained by reusing components from electric vehicles, further reducing vehicle costs. By disposing the heat transport assembly, the heat generated during the operation of the inductor is transferred to the power battery pack, further increasing the heating rate and preventing adverse effects on the vehicle caused by the battery heating system.

[0075] In the description herein, reference to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples" means that the specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present disclosure. As used herein, illustrative references to such terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more of the embodiments or examples.

[0076] While embodiments of the present disclosure have been shown and described, it is understood that the foregoing embodiments are illustrative and should not be understood as limitations on the present disclosure. Alterations, modifications, substitutions, or variations may be made to the foregoing embodiments by those skilled in the art without departing from the scope of the present disclosure.

Claims

1. a power battery pack including a first battery assembly and a second battery assembly, the first battery assembly and the second battery assembly being connected in series, with a center line drawn to a series connection point between the first battery assembly and the second battery assembly; n buck-boost inverters, each comprising an inverter bridge and an inductor, the n inverter bridges connected in parallel to form a first bus terminal and a second bus terminal, the first bus terminal connected to a positive pole of the power battery pack, the second bus terminal connected to a negative pole of the power battery pack, one terminal of the inductor connected to a midpoint of the inverter bridge, and the other terminal of the inductor connected to the center line, where n is an integer greater than 1; a controller connected to a control terminal of the inverter bridge and configured to perform out-of-phase control on the n buck-boost inverters to achieve simultaneous self-heating of the first battery assembly and the second battery assembly; Equipped with the inverter bridge comprises an upper bridge arm switch tube and a lower bridge arm switch tube, one terminal of the upper bridge arm switch tube is connected to one terminal of the lower bridge arm switch tube, the connection point being the midpoint of the inverter bridge, the other terminal of the upper bridge arm switch tube is connected to the first bus terminal, and the other terminal of the lower bridge arm switch tube is connected to the second bus terminal; the first bus terminal is connected to a positive electrode of the first battery assembly, and the second bus terminal is connected to a negative electrode of the second battery assembly; when n is 3, the three buck-boost inverters are designated as a first buck-boost inverter, a second buck-boost inverter, and a third buck-boost inverter, respectively; the first buck-boost inverter comprises a first switch tube, a fourth switch tube, and a third inductor; the second buck-boost inverter comprises a second switch tube, a fifth switch tube, and a second inductor; the third buck-boost inverter comprises a third switch tube, a sixth switch tube, and a first inductor; the first switch tube, the second switch tube, and the third switch tube are all upper bridge arm switch tubes, and the fourth switch tube, the fifth switch tube, and the sixth switch tube are all lower bridge arm switch tubes; and in each on / off cycle, the controller: Controlling the first, third, and fifth switch tubes to be turned on and the second, fourth, and sixth switch tubes to be turned off in a first timing sequence, wherein a time length of the first timing sequence is Π / 3; Controlling the first, fifth, and sixth switch tubes to be turned on and the second, third, and fourth switch tubes to be turned off in a second timing sequence, wherein the second timing sequence is adjacent to the first timing sequence and the time length of the second timing sequence is Π / 3; Controlling the first, second, and sixth switch tubes to be turned on and the third, fourth, and fifth switch tubes to be turned off in a third timing sequence, wherein the third timing sequence is adjacent to the second timing sequence and the time length of the third timing sequence is Π / 3; Controlling the second, fourth, and sixth switch tubes to be turned on and the first, third, and fifth switch tubes to be turned off in a fourth timing sequence, wherein the fourth timing sequence is adjacent to the third timing sequence and the time length of the fourth timing sequence is Π / 3; Controlling the second, third, and fourth switch tubes to be turned on and the first, fifth, and sixth switch tubes to be turned off in a fifth timing sequence, wherein the fifth timing sequence is adjacent to the fourth timing sequence and the time length of the fifth timing sequence is Π / 3; controlling the third switch tube, the fourth switch tube, and the fifth switch tube to be turned on and the first switch tube, the second switch tube, and the sixth switch tube to be turned off in a sixth timing sequence, wherein the sixth timing sequence is adjacent to the fifth timing sequence, and the time length of the sixth timing sequence is Π / 3; configured to: where Π represents half of the on / off period.

2. The battery heating system described in claim 1, wherein the controller controls a upper bridge arm switch tubes and b lower bridge arm switch tubes to be turned on simultaneously, where a and b are both positive integers smaller than n and a + b = n.

3. The battery heating system of claim 2 , wherein the absolute value of a−b is 1 or less.

4. 4. The battery heating system of claim 3, wherein the controller is configured to control the on angles of each upper bridge arm switch tube to be out of phase by 2*Π / n, and to control the upper bridge arm switch tube and the lower bridge arm switch tube in the same inverter bridge to be complementarily turned on in each on / off period.

5. The controller The battery heating system of claim 1 , further configured to control a net on-time of each switch tube to be equal to a net off-time.

6. 6. The battery heating system of claim 1, further comprising a switch assembly connected between the center wire and the other terminals of all the inductors and configured to control connection and disconnection of the center wire to and from the inductors.

7. 6. The battery heating system of claim 1, further comprising a heat transport assembly disposed between the inductor and the power battery pack and configured to transfer heat generated by the inductor to the power battery pack.

8. The heat transport assembly comprises:

8. The battery heating system of claim 7, comprising a heat pump loop, the heat pump loop comprising a heat transport medium and a heat pump, the heat pump being configured to transfer the heat absorbed by the inductor to the power battery pack when the heat transport medium flows through the power battery pack by controlling the heat transport medium to flow through the heat pump loop.

9. The battery heating system according to claim 1 , wherein the n inductors included in the n buck-boost inverters have the same current flow direction and magnitude.

10. An electric vehicle comprising the battery heating system according to any one of claims 1 to 5.

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