Battery self-heating device and vehicle

Abstract

The utility model discloses a battery self-heating device and a vehicle, the battery self-heating device comprises a battery pack and at least one bridge arm, the positive electrode of the battery pack is electrically connected to the first confluence end of the at least one bridge arm and the connection point of the at least one bridge arm respectively; the negative electrode of the battery pack is electrically connected to the second confluence end of the at least one bridge arm, and the middle point of the battery pack is electrically connected to the connection point of the at least one bridge arm through the first switch. According to the battery self-heating device and the vehicle provided by the utility model, by setting the electric connection from the midpoint of the battery pack to the bridge arm connection point, only the structure of the battery pack is modified, the structures of the three-phase full-bridge inverter and the three-phase alternating-current motor do not need to be modified, self-heating of the battery pack can be realized, and the service life of the battery pack is prolonged. And complete decoupling of battery self-heating and motor control is realized.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, in particular to a battery self-heating device and a vehicle. Background Art

[0002] Under extremely cold conditions, the high-voltage battery pack of new energy vehicles will significantly reduce its power output capacity while driving and its charging capacity when receiving current, resulting in insufficient vehicle power or long charging time. The vehicle needs to be equipped with a high-speed and efficient battery heating system.

[0003] In order to achieve battery heating, it is usually necessary to modify both the battery and the three-phase AC motor. The large amount of hardware modification will significantly increase the hardware cost, extend the development cycle, and cause the coupling of battery self-heating and motor control. In addition, these modifications may also increase the electromagnetic compatibility (EMC) issues of the vehicle. Utility Model Content

[0004] A series of simplified concepts are introduced in the utility model content section, which will be further described in detail in the detailed implementation section. The utility model content section of the utility model does not mean to attempt to define the key features and essential technical features of the technical solution claimed for protection, nor does it mean to attempt to determine the scope of protection of the technical solution claimed for protection.

[0005] The utility model provides a battery self-heating device, comprising a battery pack and at least one bridge arm, wherein the positive electrode of the battery pack is electrically connected to a first bus terminal of the at least one bridge arm and a connection point of the at least one bridge arm, respectively, the negative electrode of the battery pack is electrically connected to a second bus terminal of the at least one bridge arm, and the midpoint of the battery pack is electrically connected to the connection point of the at least one bridge arm via a first switch.

[0006] Exemplarily, the positive electrode of the battery pack leads to a positive busbar, which is electrically connected to a connection point of the at least one bridge arm, and a center line led from the midpoint of the battery pack merges with the positive busbar and is electrically connected to a connection point of the at least one bridge arm via an inductor.

[0007] Exemplarily, the at least one bridge arm comprises an upper bridge arm switching device and a lower bridge arm switching device connected in series, and the connection point is arranged between the upper bridge arm switching device and the lower bridge arm switching device.

[0008] Exemplarily, the battery pack includes at least two battery groups connected in series, and a midpoint of the battery pack is arranged between any two adjacent battery groups of the at least two battery groups connected in series.

[0009] Exemplarily, the first switch is arranged on the center line, the second switch is arranged on the positive bus, the positive electrode of the battery pack is also led out to a boost bus, the boost bus is electrically connected to the first bus terminal of the at least one bridge arm, and the third switch is arranged on the boost bus, the negative electrode of the battery pack is led out to a negative bus, the negative bus is electrically connected to the second bus terminal of the at least one bridge arm, and the fourth switch is arranged on the negative bus.

[0010] Exemplarily, when the second switch is open and the first switch, the third switch, and the fourth switch are closed, the battery pack self-heats.

[0011] Exemplarily, a pre-charging circuit is further provided on the negative electrode bus, the pre-charging circuit includes a fifth switch and a resistor connected in series, and the pre-charging circuit is connected in parallel with the fourth switch.

[0012] Exemplarily, the battery self-heating device also includes a three-phase full-bridge inverter and a three-phase AC motor, the three-phase full-bridge inverter is connected in parallel with the at least one bridge arm, the three-phase full-bridge inverter includes a three-phase bridge arm, and the three-phase AC motor is electrically connected to each phase bridge arm of the three-phase full-bridge inverter, respectively.

[0013] Exemplarily, the battery self-heating device further includes a first capacitor and a second capacitor, wherein the first capacitor is arranged in parallel with the lower bridge arm switch device of the at least one bridge arm, and the second capacitor is arranged in parallel with the at least one bridge arm.

[0014] The utility model also provides a vehicle, comprising any one of the above battery self-heating devices.

[0015] According to the battery self-heating device and vehicle provided by the utility model, by setting an electrical connection from the midpoint of the battery pack to the bridge arm connection point, only the structure of the battery pack is modified, and there is no need to modify the structure of the three-phase full-bridge inverter and the three-phase AC motor. Self-heating of the battery pack can be achieved, and complete decoupling of battery self-heating and motor control can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The following drawings of the present invention are used as a part of the present invention for understanding the present invention. The drawings show the embodiments of the present invention and their descriptions, and are used to explain the principle of the present invention.

[0017] In the attached figure:

[0018] Figure 1 A schematic diagram of the topological structure of a battery self-heating device according to an embodiment of the utility model;

[0019] Figure 2 A schematic diagram of battery pack heating when the inductor current is positive according to an embodiment of the present utility model;

[0020] Figure 3 A schematic diagram of battery pack heating when the inductor current is negative according to an embodiment of the utility model;

[0021] Figure 4 The figure is a flowchart of the battery self-heating according to an embodiment of the present utility model.

[0022] Reference numerals

[0023] 110, battery pack 120, bridge arm

[0024] 130. Three-phase full-bridge inverter 140. Three-phase AC motor DETAILED DESCRIPTION

[0025] In the following description, a large number of specific details are given to provide a more thorough understanding of the utility model. However, it is obvious to those skilled in the art that the utility model can be implemented without one or more of these details. In other examples, in order to avoid confusion with the utility model, some technical features known in the art are not described.

[0026] In order to fully understand the present invention, a detailed description will be provided in the following description to illustrate the battery self-heating device and vehicle of the present invention. Obviously, the implementation of the present invention is not limited to the specific details familiar to those skilled in the field of battery technology. The preferred embodiments of the present invention are described in detail below, but in addition to these detailed descriptions, the present invention may also have other embodiments.

[0027] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the utility model. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should also be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of the features, wholes, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or combinations thereof.

[0028] Now, exemplary embodiments according to the present utility model will be described in more detail with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in a variety of different forms and should not be interpreted as being limited to the embodiments described herein. It should be understood that these embodiments are provided to make the disclosure of the present utility model thorough and complete, and to fully convey the concepts of these exemplary embodiments to those of ordinary skill in the art. In the accompanying drawings, for the sake of clarity, the thickness of layers and regions is exaggerated, and the same reference numerals are used to represent the same elements, and thus their description will be omitted.

[0029] Currently, most new energy vehicle electric drive assemblies are equipped with a DC boost circuit (BDC) to increase the DC operating voltage at the input bus terminal of the three-phase full-bridge inverter, thereby improving the motor's external characteristics and system efficiency.

[0030] The utility model provides a battery self-heating device, such as Figure 1 As shown, it includes a battery pack 110 and at least one bridge arm 120, the positive electrode of the battery pack is electrically connected to the first bus terminal of the at least one bridge arm and the connection point of the at least one bridge arm, the negative electrode of the battery pack is electrically connected to the second bus terminal of the at least one bridge arm, and the midpoint of the battery pack is electrically connected to the connection point of the at least one bridge arm via a first switch K1.

[0031] Exemplarily, the battery pack 110 includes at least two battery groups connected in series, and the midpoint of the battery pack 110 is arranged between any two adjacent battery groups in the at least two battery groups connected in series. The midpoint of the battery pack is the voltage center point of the battery pack.

[0032] In one embodiment, Figure 1 As shown, the battery pack 110 includes two battery packs (bat1, bat2) connected in series, and the voltages of the battery packs bat1 and bat2 are the same or similar, and the area between the battery packs bat1 and bat2 can be selected as the midpoint of the battery pack 110. When the battery pack 110 includes four battery packs (bat1, bat2, bat3, bat4) connected in series, and the voltages of the four battery packs connected in series are the same or similar, the area between the battery packs bat1 and bat2 or between the battery packs bat3 and bat4 can be selected as the midpoint of the battery pack 110, but in order to balance the voltages on both sides of the midpoint of the battery pack, the area between the battery packs bat2 and bat3 is usually selected as the midpoint of the battery pack 110.

[0033] In one embodiment, the at least one bridge arm 120 includes an upper bridge arm switch device and a lower bridge arm switch device connected in series, and the connection point is set between the upper bridge arm switch device and the lower bridge arm switch device. It should be noted that the number of bridge arms can be set as needed, and this application does not limit this.

[0034] In one embodiment, the positive electrode of the battery pack 110 leads to a boost busbar and a positive busbar, the boost busbar is electrically connected to the first busbar end of the at least one bridge arm 120, and the positive busbar is electrically connected to the connection point of the at least one bridge arm 120. The negative electrode of the battery pack 110 leads to a negative busbar, and the negative busbar is electrically connected to the second busbar end of the at least one bridge arm.

[0035] In one embodiment, the positive bus, negative bus and boost bus are all provided with high-voltage switches. The high-voltage switch may be a relay, a semiconductor device or any other device that performs switch control through photoelectric signals. Specifically, the positive electrode of the battery pack is connected to the connection point of the at least one bridge arm via the second switch K2, that is, the second switch K2 is provided on the positive bus; the positive electrode of the battery pack is connected to the first bus terminal of the at least one bridge arm via the third switch K3, that is, the third switch K3 is provided on the boost bus; the negative electrode of the battery pack is connected to the second bus terminal of the at least one bridge arm via the fourth switch K4, that is, the fourth switch K4 is provided on the negative bus.

[0036] In one embodiment, Figure 1 As shown, the battery self-heating device further includes a three-phase full-bridge inverter 130 and a three-phase AC motor 140. The three-phase full-bridge inverter 130 is connected in parallel with the at least one bridge arm 120. The three-phase full-bridge inverter 130 includes three-phase bridge arms, and the three-phase AC motor 140 is electrically connected to each phase bridge arm of the three-phase full-bridge inverter 130, respectively.

[0037] In one embodiment, Figure 1As shown, when the voltage of the external DC charging pile is lower than the full-charge voltage of its own battery pack, it is necessary to receive the external DC charging pile power through its own DC boost circuit (BDC) and boost the voltage to charge the battery pack. For the BDC working condition, the battery pack leads to three electrical connection lines, namely the positive bus, the negative bus and the boost bus. The boost bus is connected to the first bus terminal of at least one bridge arm 120, and the positive bus and the negative bus are respectively electrically connected to the connection point of at least one bridge arm 120 and the second bus terminal of at least one bridge arm 120. The BCD circuit is usually composed of two identical boost circuits, each of which is provided with an inductor (inductor L1, inductor L2). In addition, the BCD circuit can also be equipped with a current sensor (not shown), and the BDC output end is usually also equipped with a boosted bus capacitor C2 to reduce the switching ripple, which will not be repeated here.

[0038] Exemplarily, the connection point where the midpoint of the battery pack 110 is electrically connected to the at least one bridge arm 120 includes a center line derived from the midpoint of the battery pack 110 and connected to the connection point of the at least one bridge arm 120 via an inductor after merging with the positive busbar. A first switch K1 is provided on the center line derived from the midpoint of the battery pack.

[0039] In one embodiment, a center line is drawn from the midpoint of the battery pack. The center line can be connected in series with a high-voltage switch inside or outside the battery pack, and then connected to the positive busbar, and then drawn out of the battery pack through the positive busbar high-voltage wire harness. Figure 1 In the illustrated embodiment, a center line is drawn from the midpoint of the battery pack 110 , which is connected in series with the first switch K1 , merged with the positive bus bar, and then connected to a connection point of at least one bridge arm 120 via an inductor.

[0040] Exemplarily, when the second switch K2 is opened, and the first switch K1 , the third switch K3 , and the fourth switch K4 are closed, the battery pack is self-heated.

[0041] In one embodiment, Figure 2 As shown, when the control inductor current is positive (flowing to BDC), the current is basically divided equally between the upper and lower bridge arms. Specifically, part of the current flows from the upper bridge arm diode to the third switch K3, and the other part of the current flows from the lower bridge arm diode to the fourth switch K4, and then flows into the battery pack bat1 (also called the positive half pack) and battery pack bat2 (also called the negative half pack) of the battery respectively. The current flows from the battery pack bat1 for charging, and the battery pack bat2 for discharging. From the perspective of energy conservation, the electric power released by the battery pack bat2 is greater than the electric power charged into the battery pack bat1, and the difference is converted into heat dissipated in the entire circuit. At low temperatures, the internal resistance of the battery is large, and most of the heat will be generated in the battery pack, so battery heating is achieved. But Figure 2The state cannot be maintained all the time, because the remaining power (SOC) of battery pack bat2 will continue to decrease while the SOC of battery pack bat1 will continue to increase, resulting in uneven SOC of the battery pack. Therefore, it is necessary to switch to Figure 3 When the inductor current is negative, the battery pack bat2 enters the charging state, while the battery pack bat1 is discharged. Figure 2 and Figure 3 The rapid switching of states can form a back-and-forth charge and discharge current between the battery packs, thereby achieving battery heating. Figure 2 and Figure 3 For simplicity, only the current flow direction of one bridge arm is shown. When two or more bridge arms work simultaneously, each bridge arm has a current as shown in the figure.

[0042] By electrically connecting the midpoint of the battery pack to the connection point of at least one of the bridge arms, the battery self-heating is achieved, which has the following advantages: (1) Only the structure of the battery pack needs to be modified, and the structure of the three-phase full-bridge inverter and the three-phase AC motor does not need to be modified, which reduces the amount of hardware modification, reduces hardware cost, shortens the development cycle, and reduces EMC risk; (2) By reusing BDC for battery self-heating, when the battery pack is self-heated, the inductor current can be accurately closed-loop controlled by BDC to achieve extremely low frequency and arbitrary waveform heating current, thereby improving the battery heating effect; (3) When the battery is self-heated, by controlling the size of the inductor current, the SOC active balancing between multiple battery packs in the battery pack can be achieved. Even when there is no self-heating requirement, this function can be enabled to perform active SOC balancing between battery packs; (4) There is no need to modify the structure of the three-phase full-bridge inverter and the three-phase AC motor, which further achieves complete decoupling of battery self-heating and motor control, that is, the electronically controlled three-phase full-bridge circuit can be used normally to control the motor output torque during self-heating.

[0043] In one embodiment, the working process of the battery self-heating device is as follows: Figure 4 As shown, when the vehicle is charging low voltage electricity, the battery temperature is detected. When the battery temperature is lower than the preset threshold, the battery self-heating pre-charging process is first executed, and then the second switch K2 is disconnected, and the first switch K1, the third switch K3 and the fourth switch K4 are closed to start the reused BDC battery self-heating process. When the battery temperature reaches the preset threshold, the first switch K1 is disconnected, the battery self-heating exit process is executed, and the normal control state is entered.

[0044] Exemplarily, a pre-charging circuit is further provided on the negative busbar, the pre-charging circuit includes a fifth switch K5 and a resistor R1 connected in series, and the pre-charging circuit is connected in parallel with the fourth switch K4. The battery self-heating device also includes a first capacitor C1 and a second capacitor C2, the first capacitor C1 is arranged in parallel with the lower bridge arm switch device of the at least one bridge arm, and the second capacitor C2 is arranged in parallel with the at least one bridge arm.

[0045] In one embodiment, when the battery self-heats, the first capacitor C1 serves as the BDC input capacitor and the second capacitor C2 serves as the BDC output capacitor. The two capacitors operate on different voltage platforms and need to be pre-charged separately. Therefore, the pre-charging circuit needs to be designed on the negative bus of the battery pack to pre-charge the first capacitor C1 and the second capacitor C2 separately.

[0046] In one embodiment, the battery self-heating pre-charging process includes: first, closing the fifth switch K5 on the pre-charging circuit and the third switch K3 on the boost circuit to pre-charge the second capacitor C2; when the second capacitor C2 reaches a preset voltage, closing the first switch K1 on the center line to pre-charge the first capacitor C1; when the first capacitor C1 reaches a preset voltage, closing the fourth switch K4 on the negative main line and disconnecting the fifth switch K5 on the pre-charging circuit.

[0047] In one embodiment, starting the reused BDC battery self-heating includes: selecting the heating current frequency, amplitude and waveform, selecting the bridge arm to be used, such as one or more bridge arms in at least one bridge arm 120, and then turning on the corresponding bridge arm to enter the inductor current closed-loop control state.

[0048] By controlling the inductor current to follow the set waveform, the alternating current of the required frequency, amplitude and waveform can be charged and discharged back and forth between the positive and negative half packs, and the battery can be heated through the thermal effect of the current on the internal resistance of the battery.

[0049] In one embodiment, the inductor current closed-loop control process includes: after entering the inductor current closed-loop control state, the current inductor current value is detected by the current sensor on the inductor loop, and then the inductor current is compared with the instruction, which is defined as follows: Figure 2 The current flowing from the center of the battery to the inductor is positive. When the inductor current is less than the command, the corresponding upper bridge arm switch device duty cycle is reduced, so that the average voltage on the right end of the inductor is reduced, while the voltage on the left end of the inductor is basically 1 / 2*the battery pack voltage remains unchanged. Therefore, after lowering the upper bridge arm duty cycle, the current flowing from the battery into the inductor will increase. When the inductor current is greater than the command value, the corresponding upper bridge arm switch device duty cycle is increased to reduce the current flowing from the battery into the inductor. When the inductor current is controlled to be negative, that is, Figure 3 When the current from the inductor to the battery flows, the same method as above can also be used to control the inductor current.

[0050] By controlling the duty cycle of the switching device on the bridge arm, a charge and discharge current is formed on the inductor and at the center point of the battery pack. This current flows through the internal resistance of the battery pack to heat the battery.

[0051] In one embodiment, after the battery self-heating is completed, after the inductor current, that is, the current on the first switch K1 branch of the center line is basically controlled to 0, the BDC is subjected to the off-wave processing to stop the control of the inductor current, and then the first switch K1 is disconnected. Because the BDC input end is also connected to other high-voltage loads such as the air-conditioning compressor, it is necessary to connect the voltage at the BDC output end back to the BDC input end through the BDC upper bridge, and it is necessary to close the upper bridge IGBT and charge the capacitor C1 to the sum of the voltages of the two half packs. At this time, the BDC has completely entered the short-circuit working condition of normal operation. If the demand is to be in the short-circuit working condition, it can continue to operate in this state. If the BDC is required to enter the direct-through state, after closing the upper bridge IGBT, the second switch K2 on the positive bus is closed first, and then the third switch K3 on the boost bus is disconnected to achieve the direct-through working condition. Since the battery self-heating has been completed at this time, the output power capacity has been basically restored, it can be expected that there may be a BDC boost demand. When it is necessary to enter the boost, it can be entered from the direct-through state. The direct-through to boost part is the content processing and will not be repeated. If the BDC and the three-phase full-bridge inverter are required to enter the off-wave state, that is, there is no need to control the output torque of the motor, then after closing the upper bridge IGBT, the third switch K3 on the boost bus is disconnected, and the three-phase full-bridge inverter is controlled to start the wave and actively discharge through the motor. After the voltage on the capacitors C1 and C2 is released to the required threshold, the BDC and the three-phase full-bridge inverter enter the off-wave state.

[0052] The utility model also provides a vehicle, comprising the battery self-heating device mentioned above.

[0053] According to the battery self-heating device and vehicle provided by the utility model, by setting an electrical connection from the midpoint of the battery pack to the bridge arm connection point, only the structure of the battery pack is modified, and there is no need to modify the structure of the three-phase full-bridge inverter and the three-phase AC motor. Self-heating of the battery pack can be achieved, and complete decoupling of battery self-heating and motor control can be achieved.

[0054] The utility model has been described through the above embodiments, but it should be understood that the above embodiments are only for the purpose of example and description, and are not intended to limit the utility model to the scope of the described embodiments. In addition, it can be understood by those skilled in the art that the utility model is not limited to the above embodiments, and more variations and modifications can be made according to the teachings of the utility model, and these variations and modifications all fall within the scope of protection claimed by the utility model. The protection scope of the utility model is defined by the attached claims and their equivalents.

Claims

1. A battery self-heating device, It is characterized in that It includes a battery pack and at least one bridge arm, wherein the positive electrode of the battery pack is electrically connected to the first bus terminal of the at least one bridge arm and the connection point of the at least one bridge arm, respectively, the negative electrode of the battery pack is electrically connected to the second bus terminal of the at least one bridge arm, and the midpoint of the battery pack is electrically connected to the connection point of the at least one bridge arm via a first switch.

2. The battery self-heating device according to claim 1, It is characterized in that The positive electrode of the battery pack leads to a positive busbar, which is electrically connected to the connection point of the at least one bridge arm. The center line led from the midpoint of the battery pack merges with the positive busbar and is electrically connected to the connection point of the at least one bridge arm via an inductor.

3. The battery self-heating device according to claim 1, It is characterized in that The at least one bridge arm includes an upper bridge arm switching device and a lower bridge arm switching device connected in series, and the connection point is arranged between the upper bridge arm switching device and the lower bridge arm switching device.

4. The battery self-heating device according to claim 1, It is characterized in that The battery pack includes at least two battery groups connected in series, and a midpoint of the battery pack is arranged between any two adjacent battery groups of the at least two battery groups connected in series.

5. The battery self-heating device according to claim 2, It is characterized in that The first switch is arranged on the center line, the second switch is arranged on the positive bus, the positive electrode of the battery pack also leads to a boost bus, the boost bus is electrically connected to the first bus terminal of the at least one bridge arm, and the third switch is arranged on the boost bus, the negative electrode of the battery pack leads to a negative bus, the negative bus is electrically connected to the second bus terminal of the at least one bridge arm, and the fourth switch is arranged on the negative bus.

6. The battery self-heating device according to claim 5, It is characterized in that When the second switch is opened and the first switch, the third switch and the fourth switch are closed, the battery pack self-heats.

7. The battery self-heating device according to claim 5, It is characterized in that The negative busbar is also provided with a pre-charging circuit, which includes a fifth switch and a resistor connected in series, and the pre-charging circuit is connected in parallel with the fourth switch.

8. The battery self-heating device according to claim 1, It is characterized in that It also includes a three-phase full-bridge inverter and a three-phase AC motor. The three-phase full-bridge inverter is connected in parallel with the at least one bridge arm. The three-phase full-bridge inverter includes three-phase bridge arms. The three-phase AC motor is electrically connected to each phase bridge arm of the three-phase full-bridge inverter respectively.

9. The battery self-heating device according to claim 3, It is characterized in that It also includes a first capacitor and a second capacitor, wherein the first capacitor is arranged in parallel with the lower bridge arm switch device of the at least one bridge arm, and the second capacitor is arranged in parallel with the at least one bridge arm.

10. A vehicle, It is characterized in that The invention comprises the battery self-heating device according to any one of claims 1 to 9.

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