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, entitled "BATTERY HEATING SYSTEM AND ELECTRIC VEHICLE", which is hereby incorporated by reference in its entirety.

[0002] This disclosure relates to the technical field of vehicles, and more particularly, to a battery heating system and an electric vehicle.

Background Art

[0003] The internal heating solution of a battery in the prior art is shown in FIG. 1. The battery pack includes batteries B1 and B2 and an inductor L as an energy storage element. In one cycle, after battery B1 charges inductor L, inductor L charges battery B2, then battery B2 charges inductor L, and finally inductor L charges battery B1. During the charge - discharge process, heat is generated by the internal resistance of the battery, thereby realizing self - heating of the battery. However, during the charge - discharge process, the terminal voltage of the battery pack fluctuates greatly, affecting the stability when powering a load and causing a large voltage impact on the charging device in the charging and self - heating states.

Summary of the Invention

Problems to be Solved by the Invention

[0004] This disclosure provides a battery heating system and an electric vehicle. According to this disclosure, the power battery pack can be heated efficiently at low cost, maintain a stable battery pack voltage, ensure high quality when powering a load, and prevent voltage impact on the charging device in the charging and self - heating states.

Means for Solving the Problems

[0005] In a first aspect, an embodiment of the present disclosure provides a battery heating system. The system is a power battery pack including a first battery assembly and a second battery assembly, wherein the first battery assembly and the second battery assembly are connected in series, and a center line is drawn at the series connection point of the first battery assembly and the second battery assembly; a power battery pack, n buck-boost inverters each including an inverter bridge and an inductor, wherein the n inverter bridges are connected in parallel to form a first bus terminal and a second bus terminal, the first bus terminal is connected to the positive electrode of the power battery pack, the second bus terminal is connected to the negative electrode of the power battery pack, one terminal of the inductor is connected to the midpoint of the inverter bridge, and the other terminal of the inductor is connected to the center line, where n is an integer greater than 1; n buck-boost inverters; and a controller connected to the control terminals of the inverter bridges, configured to perform phase-shift 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 according to the embodiment of the present disclosure further has the following additional technical features.

[0007] According to an 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, and the connection point is 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 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 both a and b are positive integers smaller than n, and a + b = n.

[0008] According to an embodiment of the present disclosure, the absolute value of a - b is 1 or less.

[0009] According to an embodiment of the present disclosure, the controller is specifically configured to control the angle of turning on each upper bridge arm switch tube to be phase-shifted by 2*Π / n, and in each on / off cycle, control the upper bridge arm switch tube and the lower bridge arm switch tube in the same inverter bridge to be turned on complementarily, 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 respectively designated as the first buck-boost inverter, the second buck-boost inverter, and the third buck-boost inverter. 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 cycle, the controller controls the second switch tube, the fourth switch tube, and the sixth switch tube to be turned off and the first switch tube, the third switch tube, and the fifth switch tube to be turned on in the first timing sequence, where the length of the time of the first timing sequence is Π / 3, and controls the second switch tube, the third switch tube, and the fourth switch tube to be turned off and the first switch tube, the fifth switch tube, and the sixth switch tube to be turned on in the second timing sequence, where the second timing sequence is adjacent to the first timing sequence and the length of the time of the second timing sequence is Π / 3, and controls the third switch tube, the fourth switch tube, and the fifth switch tube to be turned off and the first switch tube, the second switch tube, and the sixth switch tube to be turned on in the third timing sequence, where the third timing sequence is adjacent to the second timing sequence and the length of the time of the third timing sequence is Π / 3, and controls the first switch tube, the third switch tube, and the second switch tube, the fourth switch tube, and the sixth switch tube to be turned on in the fourth timing sequence.and controlling the fifth switch tube to be turned off, where the fourth timing sequence is adjacent to the third timing sequence and the length of the time of the fourth timing sequence is Π / 3; and in the fifth timing sequence, controlling the first switch tube, the fifth switch tube, and the sixth switch tube to be turned off so that the second switch tube, the third switch tube, and the fourth switch tube are turned on, where the fifth timing sequence is adjacent to the fourth timing sequence and the length of the time of the fifth timing sequence is Π / 3; and in the sixth timing sequence, controlling the first switch tube, the second switch tube, and the sixth switch tube to be turned off so that the third switch tube, the fourth switch tube, and the fifth switch tube are turned on, where the sixth timing sequence is adjacent to the fifth timing sequence and the length of the time of the sixth timing sequence is Π / 3, and is specifically configured to perform the above operations.

[0011] According to an 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 an embodiment of the present disclosure, the system further includes a switch assembly connected between the center line and the other terminal of all inductors and configured to control the connection and disconnection of the center line to the inductor.

[0013] According to an 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 the 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. The heat pump loop includes a heat transport medium and a heat pump. The heat pump is configured to control the heat transport medium to flow within the heat pump loop so that the heat transport medium transfers the absorbed heat generated by the inductor to the power battery pack when flowing through the power battery pack.

[0015] According to one embodiment of the present disclosure, the flow direction and magnitude of the current on 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 the battery heating system and the electric vehicle according to the embodiments 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 at 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. The 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 feeding power to the load, and prevent the voltage impact on the charging device in the charging and self-heating states.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

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Figure 9

DETAILED DESCRIPTION OF THE INVENTION

[0019] The battery heating system and the electric vehicle according to the embodiments of the present disclosure will be described with reference to the accompanying drawings, and elements having the same or similar elements or the same or similar functions are denoted by the same or similar reference numerals throughout the description. The embodiments described with reference to the accompanying drawings are illustrative and should not be construed 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] As shown in FIG. 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] In particular, the first battery assembly 1 and the second battery assembly 2 are connected in series, and a center line is drawn at the series connection point A of 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. The first bus terminal B is connected to the positive electrode of the power battery pack, and the second bus terminal C is connected to the negative electrode 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. The controller 100 is connected to the control terminals of the inverter bridges and is 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] Different from the first battery assembly and the second battery assembly in the prior art shown in FIG. 1, in which self-heating currents flow alternately, in this embodiment, during the self-heating process, current flows through the first battery assembly 1 and the second battery assembly 2 simultaneously to achieve 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 phases of the drive signals are different from each other in sequence by T / n*k, whereby phase-shift control is achieved, where k is the number of bridge arm switch tubes in each buck-boost inverter.

[0026] The embodiment shown in FIG. 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 a plurality of battery cores in series or in parallel, and the number of battery cores connected in series or in parallel may be the same or different. The flow directions and magnitudes of the currents on 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, and the connection point is the midpoint of the inverter bridge. The other terminal of the upper bridge arm switch tube is connected to the first bus terminal B, and the other terminal of the lower bridge arm switch tube is connected to the 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 both a and b are positive integers smaller than n, and a + b = n.

[0028] During the charge and discharge process of the battery pack, due to the internal resistance of the battery pack, when current flows, energy is consumed, and the consumed energy can be used to heat the battery pack. Therefore, the controller 100 is arranged to alternately control the on / off of the upper bridge arm switch tubes and the lower bridge arm switch tubes in the n inverter bridges, perform phase shift control, 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 through the first battery assembly 1 and the second battery assembly 2 simultaneously, and the flow directions of these currents are opposite to each other, thereby realizing the simultaneous self-heating of the first battery assembly 1 and the second battery assembly 2 and improving the heating efficiency. Due to the simultaneous self-heating, the total voltage during the heating process is stabilized, ensuring high quality when feeding power to the load and preventing the voltage from affecting the charging device in the charging and self-heating states.

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

[0030] The controller 100 is further configured to control the net on-time of each switching tube to be equal to the net off-time. That is, after a plurality of on / off operations in a certain period, the total on-time and off-time of each switching tube should be equal, so that the amount of electricity released by the first battery assembly 1 is the same as the amount of electricity released by the second battery assembly 2, and the first battery assembly 1 is charged by the same amount of electricity as the electricity charged to the second battery assembly 2, ensuring the equalization of the power of the first battery assembly 1 and the second battery assembly 2.

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

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

[0033] In this example, the duty ratio of each bridge arm is fixed (for example, 0.5), 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. When n is 2, the two buck-boost inverters 3 are respectively designated as the first buck-boost inverter 3 and the second buck-boost inverter 3. The first buck-boost inverter 3 includes the first switching tube T1, the fourth switching tube T4, and the third inductor Lw. The second buck-boost inverter 3 includes the second switching tube T2, the fifth switching tube T5, and the second inductor Lv. Both the first switching tube T1 and the second switching tube T2 are upper bridge arm switching tubes. Both the fourth switching tube T4 and the fifth switching tube T5 are lower bridge arm switching tubes. In each on / off cycle, the controller 100 Specifically configured to control the second switch tube T2 and the fourth switch tube T4 to be turned off so that the first switch tube T1 and the fifth switch tube T5 are turned on in the first timing sequence, where the length of the time 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 of the first battery assembly 1 11 is i, where i is the current flowing through the single-phase bridge arm, and the direction of the current flow 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 12 is -i.

[0035] The controller 100 is configured to control the first switch tube T1 and the fifth switch tube T5 to be turned off so that the second switch tube T2 and the fourth switch tube T4 are turned on in the second timing sequence, where the second timing sequence is adjacent to the first timing sequence, and the length of the time 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 of the first battery assembly 1 21 is i. 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 of the second battery assembly 2 22 is -i.

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

[0038] The controller 100 is configured to control the second switch tube T2 and the fourth switch tube T4 to be turned off and the first switch tube T1 and the fifth switch tube T5 to be turned on in the third timing sequence, where the third timing sequence is adjacent to the second timing sequence, and the length of the time 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 of the first battery assembly 1 is -i. The second battery assembly 2 discharges through the fifth switch tube T5 to the second inductor Lv for energy storage, where the discharge current i 32 of the second battery assembly 2 is i.

[0040] The controller 100 controls the first switch tube T1 and the fifth switch tube T5 to be turned off and the second switch tube T2 and the fourth switch tube T4 to be turned on in the fourth timing sequence, where the fourth timing sequence is adjacent to the third timing sequence, and the length of the time 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 of the first battery assembly 1 is -i. The second battery assembly 2 discharges through the fourth switch tube T4 to the third inductor Lw for energy storage, where the discharge current i 42 of the second battery assembly 2 is i.

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

[0043] In the above stage, both the first battery assembly 1 and the second battery assembly 2 have currents with completely different phases of 180 degrees. Therefore, these currents flow in opposite directions and cancel each other out. When the first battery assembly 1 discharges, the second battery assembly 2 is charged, and since the voltage changes of both cancel each other out, 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 FIG. 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 FIG. 4.

[0045] In this example, the duty ratio of each bridge arm is fixed (for example, 0.5), 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. When n is 3, the three buck-boost inverters 3 are respectively designated as the first buck-boost inverter 3, the second buck-boost inverter 3, and the third buck-boost inverter 3. The first buck-boost inverter 3 includes the first switch tube T1, the fourth switch tube T4, and the third inductor Lw. The second buck-boost inverter 3 includes the second switch tube T2, the fifth switch tube T5, and the second inductor Lv. The third buck-boost inverter 3 includes the third switch tube T3, the sixth switch tube T6, and the 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 modes of 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 by the controller 100 are shown in FIG. 5. In each on / off cycle, the controller 100 is specifically configured to control the second switch tube T2, the fourth switch tube T4, and the sixth switch tube T6 to be turned off so that the first switch tube T1, the third switch tube T3, and the fifth switch tube T5 are turned on in the first timing sequence, where the length of the time of the first timing sequence is Π / 3. In the first timing sequence, it is specifically configured to control the second switch tube T2, the fourth switch tube T4, and the sixth switch tube T6 to be turned off so that the first switch tube T1, the third switch tube T3, and the fifth switch tube T5 are turned on, where the length of the time 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 12 is -i.

[0047] In the second timing sequence, 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 off so that the first switch tube T1, the fifth switch tube T5, and the sixth switch tube T6 are turned on. The second timing sequence is adjacent to the first timing sequence, and the length of the time of the second timing sequence is Π / 3.

[0048] At this stage, the first battery assembly 1 continuously discharges to the third inductor Lw through the first switch tube T1 for energy storage, where the discharge current i of the first battery assembly 1 21 is i. 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 of the second battery assembly 2 22 is -2*i.

[0049] In the third timing sequence, 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 off so that the first switch tube T1, the second switch tube T2, and the sixth switch tube T6 are turned on. Here, the third timing sequence is adjacent to the second timing sequence, and the length of the time 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 of the first battery assembly 1 31 is 2*i. The first inductor Lu discharges the energy stored therein to charge the second battery assembly 2, where the charging current i of the second battery assembly 2 32 is -i.

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

[0052] The controller 100 is configured to control the first switch tube T1, the third switch tube T3, and the fifth switch tube T5 to be turned off so that the second switch tube T2, the fourth switch tube T4, and the sixth switch tube T6 are turned on in the fourth timing sequence, where the fourth timing sequence is adjacent to the third timing sequence and the length of the time 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 of the first battery assembly 1 41 is -i. 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 42 is 2*i.

[0054] In the fifth timing sequence, 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 off so that the second switch tube T2, the third switch tube T3, and the fourth switch tube T4 are turned on. Here, the fifth timing sequence is adjacent to the fourth timing sequence, and the length of the time of the fifth timing sequence is Π / 3.

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

[0056] In the sixth timing sequence, 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 off so that the third switch tube T3, the fourth switch tube T4, and the fifth switch tube T5 are turned on. Here, the sixth timing sequence is adjacent to the fifth timing sequence, and the length of the time of the sixth timing sequence is Π / 3.

[0057] At this stage, the first inductor Lu releases the energy stored therein through the third switch tube T3 to charge the first battery assembly 1. Here, the charging current i of the first battery assembly 1 61 is -i. 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. Here, the discharging current i of the second battery assembly 2 62 is 2*i.

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

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

[0060] In the above embodiment, the operation process and beneficial effects of the self-heating system are described using the example where n = 2 and the example where n = 3, respectively. 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 a - b may be set such that |a - b| ≦ 1. That is, the difference between a and b is within 1. In particular, when n is an even number, a = b. At this time, the charging current and the discharging current of the first battery assembly and the second battery assembly are equal, and the changes in the terminal voltages of both completely cancel each other out, so the terminal voltage of the power battery pack is the 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 center line and the other terminal of all the inductors and configured to control the connection and disconnection of the center line to the inductors.

[0063] In particular, by using the switch assembly 5 connected between the center line and the other terminals of all the inductors, the circuit topology is controlled, and various functions can be realized according to actual requirements. Specifically, when self-heating is required, the switch assembly 5 is controlled to be turned on, whereby the n buck-boost inverters 3 are connected to the center line and controlled by the controller 100 to realize self-heating. For example, when the vehicle is driven, charged, or powered on for running and self-heating is not required, the switch assembly 5 is controlled to be turned off, so that the n buck-boost inverters 3 are disconnected 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 respectively connected to the other terminals of all the inductors.

[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 winding in the motor is reused as an inductor. 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 plurality of buck-boost inverters 3, and any two-phase motor winding of the electric vehicle is reused as two inductors in the plurality of buck-boost inverters 3, or when n is 3, the three-phase inverter bridge in the motor controller 100 of the electric vehicle is reused as three inverter bridges in the plurality of buck-boost inverters 3, and the three-phase motor winding of the electric vehicle is reused as three inductors in the plurality of buck-boost inverters 3.

[0066] Therefore, the vehicle cost is further reduced, and the reuse rate of vehicle components is improved.

[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 the heat generated by the inductor to the power battery pack.

[0068] In particular, during the charging and discharging process of the battery pack, both the internal resistance of the battery pack and the windings of the circuit consume energy, causing energy waste and circuit failures. For example, if the temperature of the windings is too high, the permanent magnet motor may be demagnetized. Therefore, by further arranging the heat transport assembly in the electromagnetic heating system so that the heat generated by the inductor is transferred to the power battery pack, on the one hand, the heating rate of the battery pack can be accelerated, and on the other hand, the inductor can be cooled.

[0069] For example, the heat transport assembly may include a heat pump loop. The heat pump loop includes a heat transport medium and a heat pump. The heat pump is configured to control the heat transport medium to flow in the heat pump loop so that the heat transport medium transfers the absorbed heat generated by the inductor to the power battery pack when flowing through the power battery pack.

[0070] In summary, in the battery heating system according to the 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 from 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. The controller performs phase shift control on the inverter bridge to alternately enable the first battery assembly to charge the second battery assembly and enable the second battery assembly to charge the first battery assembly. Thereby, simultaneous self-heating of the first battery assembly and the second battery assembly is realized, the self-heating cost of the power battery pack is reduced, simultaneous self-heating of the first battery assembly and the second battery assembly is enabled, and the heating efficiency is improved. Further, the buck-boost inverter is obtained by reusing components of the electric vehicle, and the vehicle cost can be further reduced. By arranging the heat transfer assembly, the heat generated during the operation of the inductor is transmitted 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 showing the structure of an electric vehicle according to an embodiment of the present disclosure.

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

[0074] According to an electric vehicle according to an embodiment of the present disclosure, in a battery heating system, 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 at the series connection point of 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. The controller performs phase shift control on the inverter bridge to enable the first battery assembly to charge the second battery assembly and to enable the second battery assembly to charge the first battery assembly alternately. Thereby, simultaneous self-heating of the first battery assembly and the second battery assembly is realized, the self-heating cost of the power battery pack is reduced, simultaneous self-heating of the first battery assembly and the second battery assembly is enabled, and the heating efficiency is improved. Further, the buck-boost inverter is obtained by reusing components of the electric vehicle, and the vehicle cost can be further reduced. By arranging a heat transfer assembly, the heat generated during the operation of the inductor is transmitted 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 of this specification, the description of terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the exemplary descriptions of the foregoing terms do not necessarily refer to the same embodiment or example. Further, the specific features, structures, materials, or characteristics described may be combined in any suitable form in any one or more of the embodiments or examples.

[0076] Although embodiments of the present disclosure have been shown and described, it will be understood that the foregoing embodiments are exemplary and should not be construed as limitations on the present disclosure. Without departing from the scope of the present disclosure, changes, modifications, substitutions, or variations to the foregoing embodiments may be made by those skilled in the art.

Claims

1. A power battery pack comprising a first battery assembly and a second battery assembly, wherein the first battery assembly and the second battery assembly are connected in series, and a center line is drawn at the series connection point of the first battery assembly and the second battery assembly; a power battery pack, n buck-boost inverters each comprising an inverter bridge and an inductor, wherein the n inverter bridges are connected in parallel to form a first bus terminal and a second bus terminal, the first bus terminal is connected to the positive electrode of the power battery pack, the second bus terminal is connected to the negative electrode of the power battery pack, one terminal of the inductor is connected to the midpoint of the inverter bridge, and the other terminal of the inductor is connected to the center line, where n is an integer greater than 1; n buck-boost inverters, A controller connected to the control terminals of the inverter bridges, configured to perform phase-shift control on the n buck-boost inverters to achieve simultaneous self-heating of the first battery assembly and the second battery assembly A battery heating system comprising.

2. The inverter bridge is Comprising 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, and the connection point is 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 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 both a and b are positive integers smaller than n, and a + b = n; the battery heating system according to claim 1.

3. The absolute value of a - b is 1 or less; the battery heating system according to claim 2.

4. The controller is configured to control the angle at which each upper bridge arm switch tube is turned on to be phase-shifted by 2*Π / n, and in each on / off cycle, the upper bridge arm switch tube and the lower bridge arm switch tube in the same inverter bridge are controlled to be turned on complementarily, where Π represents half of the on / off cycle, the battery heating system according to claim 3.

5. The first bus terminal is connected to the positive electrode of the first battery assembly, 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 respectively designated as the first buck-boost inverter, the second buck-boost inverter, and the third buck-boost inverter, 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 cycle, the controller In the first timing sequence, control 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, where the length of the time of the first timing sequence is Π / 3, control In the second timing sequence, control 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, where the second timing sequence is adjacent to the first timing sequence, and the length of the time of the second timing sequence is Π / 3, control In the third timing sequence, control is performed such that the third switch tube, the fourth switch tube, and the fifth switch tube are turned off so that the first switch tube, the second switch tube, and the sixth switch tube are turned on, where the third timing sequence is adjacent to the second timing sequence and the length of time of the third timing sequence is Π / 3, and In the fourth timing sequence, control is performed such that the first switch tube, the third switch tube, and the fifth switch tube are turned off so that the second switch tube, the fourth switch tube, and the sixth switch tube are turned on, where the fourth timing sequence is adjacent to the third timing sequence and the length of time of the fourth timing sequence is Π / 3, and In the fifth timing sequence, control is performed such that the first switch tube, the fifth switch tube, and the sixth switch tube are turned off so that the second switch tube, the third switch tube, and the fourth switch tube are turned on, where the fifth timing sequence is adjacent to the fourth timing sequence and the length of time of the fifth timing sequence is Π / 3, and In the sixth timing sequence, control is performed such that the first switch tube, the second switch tube, and the sixth switch tube are turned off so that the third switch tube, the fourth switch tube, and the fifth switch tube are turned on, where the sixth timing sequence is adjacent to the fifth timing sequence and the length of time of the sixth timing sequence is Π / 3, and The battery heating system according to claim 4, configured to perform the above.

6. The controller is Further configured to control the net on-time of each switch tube to be equal to the net off-time, the battery heating system according to claim 4 or 5.

7. A battery heating system according to any one of claims 1 to 6, further comprising a switch assembly connected between the center line and the other terminals of all the inductors and configured to control connection and disconnection of the center line to the inductors.

8. A battery heating system according to any one of claims 1 to 7, 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.

9. The heat transport assembly comprises a heat pump loop, the heat pump loop comprises a heat transport medium and a heat pump, and the heat pump is configured to control the heat transport medium to flow in the heat pump loop so that the heat transport medium transfers the absorbed heat generated by the inductor to the power battery pack when flowing through the power battery pack. The battery heating system according to claim 8.

10. The flow direction and magnitude of the current on the n inductors provided in the n buck-boost inverters are the same. The battery heating system according to any one of claims 1 to 9.

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

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