Heating system for battery pack and electric apparatus

Abstract

A heating system for a battery pack and an electric apparatus. The heating system for the battery pack comprises a battery pack, an electric device, and a wire. The battery pack comprises a first battery cell group and a second battery cell group which are connected in series, the wire has a first end and a second end which are opposite, the first end of the wire is connected to a series-connected point between the first battery cell group and the second battery cell group, and the second end of the wire is connected to a neutral point of the electric device.

Description

Battery pack heating system and electrical equipment

[0001] This application claims priority to Chinese patent application No. 2024107060030, filed on May 31, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of battery technology, and more specifically to heating systems and electrical devices for battery packs. Background Technology

[0003] In related technologies, the main heating method for power batteries is external heating, such as PTC (Positive Temperature Coefficient) heating and heat pump heating. External heating involves adding additional heating equipment to heat the battery, which is costly and inefficient.

[0004] In view of the above-mentioned technical problems, this application provides a new heating system and electrical device for a battery pack. Technical issues

[0005] The purpose of this application is to provide a heating system and electrical equipment for battery packs to improve the problems of high cost and low heating efficiency of existing heating methods. Technical solutions

[0006] According to one aspect of this application, a heating system for a battery pack is provided, comprising:

[0007] A battery pack, the battery pack comprising a first cell group and a second cell group connected in series;

[0008] Electrical appliances; and

[0009] A conductor having a first end and a second end opposite to each other, the first end of the conductor being connected to the series connection point between the first battery cell group and the second battery cell group, and the second end of the conductor being connected to the neutral point of the electrical device.

[0010] According to another aspect of this application, a heating system for a battery pack is provided, comprising:

[0011] A battery pack, the battery pack comprising a first cell group and a second cell group connected in series;

[0012] Electrical appliances; and

[0013] A conductor having a first end and a second end opposite to each other, the first end of the conductor being connected to the series connection point between the first battery cell group and the second battery cell group, and the second end of the conductor being connected to the neutral point of the electrical device;

[0014] The connection point between the first cell group and the second cell group is the midpoint of the potential of the battery pack.

[0015] Wherein, when the voltage at the midpoint of the potential is greater than the voltage at the neutral point, the direction of the current in the conductor is a first direction from the battery pack to the electrical device; when the voltage at the midpoint of the potential is less than the voltage at the neutral point, the direction of the current in the conductor is a second direction from the electrical device to the battery pack.

[0016] The current in the conductor includes the drive current for driving the electrical device and the zero-sequence current.

[0017] According to another aspect of this application, an electrical appliance is provided, the electrical appliance including a heating system for the battery pack.

[0018] The battery pack heating system and electrical equipment according to the embodiments of this application connect the series connection point between the battery cells in the battery pack and the neutral point of the electrical equipment through wires. Without the need for additional heating equipment, the battery pack can be heated quickly in a short time, enabling the battery pack to achieve a self-heating effect, increasing the temperature of the battery pack, and ensuring that the vehicle can drive normally in low-temperature environments. Attached Figure Description

[0019] The above and other objects, features, and advantages of this application will become more apparent from the more detailed description of the embodiments of this application in conjunction with the accompanying drawings. The drawings are provided to further illustrate the embodiments of this application and form part of the specification. They are used together with the embodiments of this application to explain this application and do not constitute a limitation thereof. In the drawings, the same reference numerals generally represent the same components or steps.

[0020] Figure 1 is a schematic diagram of the circuit topology of a heating system for a battery pack according to an embodiment of this application.

[0021] Figures 2A and 2B are equivalent schematic diagrams of the circuit topology shown in Figure 1.

[0022] Figure 3A is an equivalent schematic diagram of Figure 2A, showing the direction of current flow when the voltage vector is a non-zero voltage vector.

[0023] Figure 3B is an equivalent schematic diagram of Figure 2B, showing the direction of current flow when the voltage vector is a non-zero voltage vector.

[0024] Figures 4A and 4B are schematic diagrams of the current flow when the voltage vector is zero in the circuit topology diagram of Figure 1.

[0025] Figure 5 is a structural block diagram of an electrical device according to an embodiment of this application.

[0026] In the attached diagram: 100 Heating system of battery pack; 11 Battery pack; 111 First cell group; 112 Second cell group; E1 First electrode; E2 Second electrode; 12 Electrical device; 120 Motor; 121 Coil; 130 Wire; 14 Busbar; 141 Positive busbar; 142 Negative busbar; 15 Controller; 150 Motor controller; 151 Bridge arm assembly; 1511 First bridge group; 1512 Second bridge group; a Series connection point between the first and second cell groups; n Neutral point of electrical device; D1 First direction; D2 Second direction; 200 Electrical equipment.

[0027] Implementation methods of this application

[0028] The following description provides numerous specific details to offer a more thorough understanding of this application. However, it will be apparent to those skilled in the art that this application can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described to avoid confusion with this application.

[0029] It should be understood that this application can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of this application to those skilled in the art. In the drawings, for clarity, the dimensions and relative dimensions of layers and regions may be exaggerated. The same reference numerals denote the same elements throughout.

[0030] It should be understood that when an element or layer is referred to as "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, components, areas, layers, and / or portions, these elements, components, areas, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer, or portion from another element, component, area, layer, or portion. Therefore, without departing from the teachings of this application, the first element, component, area, layer, or portion discussed below may be referred to as a second element, component, area, layer, or portion.

[0031] Spatial relation terms such as “below,” “under,” “below,” “under,” “above,” “above,” etc., are used herein for convenience of description to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms are intended to also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, then the element or feature described as “below,” “under,” or “below” other elements or features will be oriented “above” other elements or features. Therefore, the exemplary terms “below” and “under” can include both above and below orientations. The device may be otherwise oriented (rotated 90 degrees or otherwise) and the spatial descriptive terms used herein will be interpreted accordingly.

[0032] As the power source for electric vehicles, the power battery directly impacts the vehicle's performance. Typically, when the power battery is in a low-temperature environment below -10℃, its charging and discharging performance drops significantly due to the decreased activity of the positive and negative electrode materials and electrolyte, severely affecting the overall driving experience. Therefore, it is necessary to heat the power battery to raise its temperature and ensure the electric vehicle can operate normally in cold conditions.

[0033] In related technologies, the heating methods for power batteries are mainly external heating, such as PTC (Positive Temperature Coefficient) heating and heat pump heating.

[0034] Taking the use of a battery heater to heat the battery pack as an example, the vehicle's high-voltage system needs to provide additional power to the battery heater, as well as water channels, air channels, pipelines, low-voltage systems, etc., which increases the total cost; and because the water channels and pipelines are long, the heat loss is large and the heating time is slow and long.

[0035] To address at least one of the aforementioned problems, this application provides a heating system for a battery pack, comprising: a battery pack including a first cell group and a second cell group connected in series; an electrical device; and a wire having a first end and a second end opposite to each other, the first end of the wire being connected to the series connection point between the first cell group and the second cell group, and the second end of the wire being connected to the neutral point of the electrical device.

[0036] According to the heating system of the battery pack of this application, by connecting the series connection point between the battery cells in the battery pack and the neutral point of the electrical device through wires, the battery pack can be heated rapidly in a short time without the need for additional heating equipment, so that the battery pack can achieve a self-heating effect, increase the temperature of the battery pack, and ensure that the vehicle can drive normally in low-temperature environments.

[0037] To fully understand this application, a detailed structure will be presented in the following description to illustrate the technical solutions proposed in this application. Preferred embodiments of this application are described in detail below; however, in addition to these detailed descriptions, this application may have other implementation methods.

[0038] The heating system 100 of a battery pack according to an embodiment of this application is described below with reference to FIG1. ​​The heating system 100 of the battery pack provided in this embodiment of the application includes: a battery pack 11, the battery pack 11 including a first cell group 111 and a second cell group 112 connected in series; an electrical device 12; and a wire 130 having a first end and a second end opposite to each other, the first end of the wire 130 being connected to the series connection point a between the first cell group 111 and the second cell group 112, and the second end of the wire 130 being connected to the neutral point n of the electrical device 12.

[0039] The neutral point n of electrical device 12 is also called "zero point". Taking electrical device 12 as a motor as an example, it refers to the common point of star connection in a three-phase or multi-phase AC system.

[0040] In this embodiment, the series connection point a between the battery cells in the battery pack 11 and the neutral point n of the electrical device 12 are connected by a wire 130. When the heating system 100 of the battery pack is working, in the first time period, the first battery cell group 111 can discharge to the motor 120 through the wire 130 or the motor 120 can charge the first battery cell group 111 through the wire 130; in the second time period, the second battery cell group 112 can discharge to the motor 120 through the wire 130 or the motor 120 can charge the second battery cell group 112 through the wire 130; the first time period and the second time period do not overlap.

[0041] Specifically, taking the first time period preceding the second time period as an example, firstly, during the first time period, the first battery cell group 111 discharges to the electrical device 12 through the wire 130. The discharge current generates heat on the internal resistance of the first battery cell group 111, thus heating the first battery cell group 111. Alternatively, the electrical device 12 charges the first battery cell group 111 through the wire 130. The charging current generates heat on the internal resistance of the first battery cell group 111, thus heating the first battery cell group 111. Then, during the second time period, the second battery cell group 112 discharges to the electrical device 12 through the wire 130. The discharge current generates heat on the internal resistance of the second battery cell group 112, thus heating the second battery cell group 112. Alternatively, the electrical device 12 charges the second battery cell group 112 through the wire 130. The charging current generates heat on the internal resistance of the second battery cell group 112, thus heating the second battery cell group 112. The above processes are performed alternately, forming an alternating oscillating heating current. Therefore, the battery pack 11 can be heated without the need for additional heating equipment, achieving a self-heating effect and raising its temperature to ensure normal vehicle operation in low-temperature environments. Furthermore, compared to conventional methods of heating the battery pack 11 through external heating equipment, this embodiment uses a heating current to self-heat the battery pack 11, allowing for rapid temperature increases in a short time.

[0042] Based on this, this application provides a low-cost, high-efficiency battery pack heating system 100. According to the battery pack heating system 100 of this application, the series connection point a between the battery cells within the battery pack 11 and the neutral point n of the electrical device 12 are connected via wires 130. The first battery cell group 111 and the second battery cell group 112 are charged or discharged in a first time period and a second time period, so that at any given moment, one battery cell group is charging or discharging. This generates an alternating oscillating heating current, eliminating the need for additional heating equipment and rapidly heating the battery pack 11 in a short time. This enables the battery pack 11 to achieve a self-heating effect, increasing its temperature and ensuring normal vehicle operation in low-temperature environments.

[0043] In related technologies, the series connection point a between the battery cells in the battery pack 11 and the neutral point n of the electrical device 12 are not connected in the vehicle's drive system. This application directly connects the series connection point a between the battery cells in the battery pack 11 and the neutral point n of the electrical device 12 via a wire 130. This not only provides rapid heating of the battery pack 11, but also saves one wire contactor compared to connecting the series connection point a between the battery cells in the battery pack 11 and the neutral point n of the electrical device 12 via a wire contactor. Furthermore, this method saves costs while maintaining the normal function of the electrical device 12.

[0044] In some embodiments, the series connection point a between the first cell group 111 and the second cell group 112 can be the midpoint of the potential of the battery pack 11. The midpoint of the potential refers to the point in the battery pack 11 where the potential (or voltage) is at the middle value.

[0045] In some embodiments, the current in the conductor 130 is alternating current.

[0046] Specifically, in the relevant technology, during the vehicle driving process, the current of the battery pack 11 is continuously output to the load. At low temperatures, the battery pack 11 has a weak continuous discharge capability. Although the discharge current itself will generate heat on the internal resistance of the battery pack 11, the DC discharge capability of the battery pack 11 is weak, that is, the DC discharge current is small. The small current is loaded on the internal resistance of the battery pack 11, and the heat generation rate is low.

[0047] In this embodiment, the current in the conductor 130 is alternating current (AC), that is, the current flowing through the battery pack 11 is AC. This allows the battery pack 11 to still have a strong AC discharge capability at low temperatures. Since the AC discharge current can be very large, the temperature of the battery pack 11 can be raised quickly. Moreover, for the lithium battery pack 11, by making the current flowing through the battery pack 11 AC, lithium deposition in the battery pack 11 can be avoided, thus improving the safety performance of the battery pack 11.

[0048] In some embodiments, the direction of alternating current in conductor 130 is related to the voltage at the midpoint of the potential and the voltage at the neutral point n. Specifically, when the voltage at the midpoint of the potential is greater than the voltage at the neutral point n, the direction of alternating current is a first direction D1 from battery pack 11 to device 12; when the voltage at the midpoint of the potential is less than the voltage at the neutral point n, the direction of alternating current is a second direction D2 from device 12 to battery pack 11.

[0049] Taking a three-phase motor as an example, the voltage of the neutral point n of the three-phase motor fluctuates between Udc, 2 / 3Udc, 1 / 3Udc, and 0 due to driving reasons, while the voltage at the midpoint of the battery pack 11 is usually constant at 1 / 2Udc. When the voltage at the midpoint of the battery pack 11 is greater than the voltage at the neutral point n of the three-phase motor, the current in the conductor 130 flows from the battery pack 11 to the three-phase motor, which can be considered positive. When the voltage at the midpoint of the battery pack 11 is less than the voltage at the neutral point n of the three-phase motor, the current in the conductor 130 flows from the three-phase motor to the battery pack 11, which can be considered negative. The above processes alternate, causing the direction of the current in the conductor 130 to change between positive and negative within a period, that is, alternating current is formed in the conductor 130. The generated alternating current is evenly distributed to the first battery cell group 111 and the second battery cell group 112 during the first and second time periods, that is, alternating current is generated in the first battery cell group 111 and the second battery cell group 112.

[0050] It should be noted that when the battery pack 11 is self-heating, the self-heating current of the battery pack 11 can be controlled or not, and there is no limitation on this.

[0051] In some embodiments, the current in the conductor 130 includes a drive current for driving the electrical device 12. When the battery pack 11 is self-heated using the natural drive current in the conductor 130, the self-heating current of the battery pack 11 is not controlled.

[0052] Specifically, taking a three-phase motor as an example, the current frequency on the phase lines of a three-phase motor satisfies the following conditions:

[0053] f1 = np / 60,

[0054] Where f1 represents the current frequency on the phase line of the three-phase motor, n represents the speed of the three-phase motor, and p represents the number of rotor poles of the three-phase motor.

[0055] Therefore, the frequency of the drive current satisfies the following condition:

[0056] f2 = 3 * np / 60

[0057] Where f2 represents the frequency of the drive current, n represents the speed of the three-phase motor, and p represents the number of rotor poles of the three-phase motor.

[0058] As can be seen from the above formula, under this control condition, the frequency of the self-heating current of the battery pack 11 follows the speed of the three-phase motor. This control method is simple and easy to implement, but its disadvantage is that the frequency and amplitude of the self-heating current of the battery pack 11 are uncontrollable.

[0059] In some embodiments, the current in the conductor 130 includes zero-sequence current.

[0060] Zero-sequence current refers to the current in a three-phase power system where the amplitude and phase difference of the three-phase line currents are all the same. The generation of zero-sequence current requires two conditions: the presence of a zero-sequence voltage and the existence of a zero-sequence current path. Taking a three-phase motor as an example, the zero-sequence voltage is the three-phase voltage in the same direction; the zero-voltage vector is the standard source of the zero-sequence voltage. In this application, the potential midpoint of the battery pack 11 and the neutral point n of the three-phase motor are connected by wire 130, providing a path for the zero-sequence current; therefore, zero-sequence current is generated.

[0061] As described above, when the battery pack 11 is self-heated using the natural drive current in the conductor 130, the self-heating current of the battery pack 11 is uncontrollable. To make the self-heating current of the battery pack 11 controllable, in this embodiment, the zero-sequence current is controlled by the controller 15 (described below) in the control of the electrical device 12. It is known that the zero-sequence current does not generate torque, and therefore will not affect the drive.

[0062] It is worth noting that, under normal circumstances, the frequency of the self-heating current of the battery pack 11 is the same as the frequency of the injected zero-sequence current.

[0063] In some embodiments, the ratio of zero-sequence current to current in the conductor is variable and the ratio ranges from (0, 1).

[0064] In some embodiments, to facilitate control of the zero-sequence current, the heating system 100 of the battery pack may further include a controller 15, which is electrically connected to the electrical device 12 and is used to control the zero-sequence current. For example, the controller 15 may control the magnitude, direction, ratio of the zero-sequence current to the current in the conductor, frequency, etc., without limitation.

[0065] Specifically, the electrical device 12 may include a motor 120, and the controller 15 may include a motor controller 150. The motor controller 150 includes multiple bridge arm assemblies 151. Each bridge arm assembly 151 includes a first bridge group 1511 and a second bridge group 1512 connected in series. The first end of the first bridge group 1511 is connected to the first electrode E1 of the battery pack 11, the second end of the first bridge group 1511 is connected to the first end of the second bridge group 1512, and the second end of the second bridge group 1512 is connected to the second electrode E2 of the battery pack 11. The series connection point a of the first bridge group 1511 and the second bridge group 1512 in each bridge arm assembly 151 is connected to a coil 121 of the motor 120. The motor controller 15 can control the zero-sequence current by controlling the state of the first bridge group 1511 and the second bridge group 1512 within its own bridge arm assembly 151.

[0066] For example, as shown in Figures 4A and 4B, the battery pack 11 is connected to the motor controller 150 via bus 14. The first end of the first bridge group 1511 is connected to the positive terminal of the battery pack 11 via the positive bus 141, and the second end of the second bridge group 1512 is connected to the negative terminal of the battery pack 11 via the negative bus 142. When the motor controller 150 controls the first bridge group 1511 in all its bridge arm assemblies 151 to be on and the second bridge group 1512 to be off, or when the first bridge group 1511 in one of its bridge arms is off and the second bridge group 1512 is on, the voltage vector of the output torque of the motor 120 is a zero voltage vector, and the zero-sequence current is equal to the current in bus 14.

[0067] The zero-voltage vector can include a first zero-voltage vector and a second zero-voltage vector. Taking Figure 4A as the first time period and Figure 4B as the second time period as an example, firstly, during the first time period, the motor controller 150 controls the first bridge group 1511 in all bridge arm assemblies 151 within itself to be turned on and the second bridge group 1512 to be turned off. At this time, the second cell group 112, the wire 130, the motor 120, the first bridge group 1511 in all bridge arm assemblies 151, and the negative busbar 142 form a loop. Current flows from the positive terminal of the second cell group 112 through the loop to the negative terminal of the second cell group 112. The negative terminal, namely the second battery cell group 112, discharges to the motor 120. The discharge current generates heat on the internal resistance of the second battery cell group 112, heating the second battery cell group 112. At this time, since the current in the same direction flows through the three coils 121 of the motor 120, the voltage vector of the output torque of the motor 120 is the first zero voltage vector. Zero-sequence current flows through the conductor 130. The zero-sequence current is equal to the current in the negative bus 142, and the direction of the zero-sequence current is opposite to the direction of the current in the positive bus 141. Then, during the second time period, the motor controller 150 controls the first bridge group 1511 of all the bridge arm assemblies 151 within itself to be turned on and the second bridge group 1512 to be turned off. At this time, the first battery cell group 111, the positive bus 141, the first bridge group 1511 of all the bridge arm assemblies 151, the motor 120 and the wire 130 form a circuit. The current flows from the positive terminal of the first battery cell group 111 to the negative terminal of the first battery cell group 111 through the circuit, that is, the first battery cell group 111 discharges to the motor 120. The discharge current generates heat on the internal resistance of the first battery cell group 111, heating the first battery cell group 111. At this time, since the current in the same direction flows through the three coils 121 of the motor 120, the voltage vector of the output torque of the motor 120 is the first zero voltage vector. Zero-sequence current flows through the wire 130. The zero-sequence current is equal to the current in the positive bus 141, and the direction of the zero-sequence current is opposite to the direction of the current in the negative bus 142. Figures 4A and 4B are interleaved, which creates a reciprocating and interleaved zero-sequence current in the conductor 130. This eliminates the need for additional heating equipment, allowing the battery pack 11 to be heated rapidly in a short time. This enables the battery pack 11 to achieve a self-heating effect, increases the temperature of the battery pack 11, and ensures that the vehicle can drive normally in low-temperature environments.

[0068] Of course, during the first time period mentioned above, after the motor controller 150 controls the first bridge group 1511 of all bridge arm assemblies 151 within itself to be turned on and the second bridge group 1512 to be turned off, the motor 120 can also charge the second battery cell group 112. During this process, the charging current generates heat on the internal resistance of the second battery cell group 112, heating the second battery cell group 112, while zero-sequence current flows through the wire 130. During the second time period mentioned above, after the motor controller 150 controls the first bridge group 1511 of all bridge arm assemblies 151 within itself to be turned on and the second bridge group 1512 to be turned off, the motor 120 can also charge the first battery cell group 111. During this process, the charging current generates heat on the internal resistance of the first battery cell group 111, heating the first battery cell group 111, while zero-sequence current flows through the wire 130. The specific process can be referred to the description above, and will not be repeated here.

[0069] It should be noted that, in addition to controlling the interleaved oscillating zero-sequence current in the conductor 130 through the methods described above, the motor controller 150 can also control the ratio of the zero-sequence current to the total current in the conductor. By increasing the ratio of the zero-sequence current to the total current in the conductor, the heating effect of the zero-sequence current on the battery pack 11 can be improved. However, it is worth noting that since the zero-sequence current does not generate torque, there is a certain upper limit to the zero-sequence current while ensuring the output power of the motor 120. Of course, if the output power of the motor 120 is not required under certain circumstances, the ratio of the zero-sequence current to the total current in the conductor can be increased to a maximum of 100%.

[0070] It should also be noted that, in addition to controlling the generation of zero-sequence current in the conductor 130 by controlling the state of the first bridge group 1511 and the second bridge group 1512 of its own inner bridge arm assembly 151, the motor controller 150 also generates non-zero-sequence current in the conductor 130. The generated non-zero-sequence current can also heat the battery pack 11.

[0071] For example, as shown in Figures 3A and 3B, when the motor controller 15 controls the first bridge group 1511 of one of the bridge arm assemblies 151 to be turned on and the second bridge group 1512 to be turned off, and the first bridge group 1511 of the other bridge arm assemblies 151 to be turned off and the second bridge group 1512 to be turned on, the voltage vector of the motor's output torque is a non-zero voltage vector, and the current in the wires includes non-zero sequence current.

[0072] Taking Figure 3A as the first time period and Figure 3B as the second time period as an example, firstly, in the first time period, the motor controller 150 controls the first bridge group 1511 in the first bridge arm assembly 151 to be turned on and the second bridge group 1512 to be turned off. Similarly, in the second and third bridge arm assemblies 151, the first bridge group 1511 is turned off and the second bridge group 1512 is turned on. At this time, the first battery cell group 111, the positive bus 141, the first bridge group 1511 in all bridge arm assemblies 151, and the motor 1... 20 and wire 130 form a circuit. Current flows from the positive terminal of the first battery cell group 111 to the negative terminal of the first battery cell group 111 through the circuit. That is, the first battery cell group 111 discharges to the motor 120. The discharge current generates heat on the internal resistance of the first battery cell group 111, heating the first battery cell group 111. At this time, since current flows through one of the three coils 121 of the motor 120, the voltage vector of the output torque of the motor 120 is a non-zero voltage vector, and a non-zero sequence current flows through the wire 130. Then, in the second time period, the motor controller 150 still controls the first bridge group 1511 in the first bridge arm assembly 151 to be turned on and the second bridge group 1512 to be turned off. The first bridge group 1511 in the second bridge arm assembly 151 and the third bridge arm assembly 151 are turned off and the second bridge group 1512 is turned on. At this time, the second battery cell group 112, the wire 130, the motor 120, the first bridge group 1511 in all bridge arm assemblies 151 and the negative bus 142 form a loop. The current flows from the positive terminal of the second battery cell group 112 to the negative terminal of the second battery cell group 112 through the loop. That is, the second battery cell group 112 discharges to the motor 120. The discharge current generates heat on the internal resistance of the second battery cell group 112, heating the second battery cell group 112. At this time, since current flows through two of the three coils 121 of the motor 120, the voltage vector of the output torque of the motor 120 is a non-zero voltage vector, and a non-zero sequence current flows through the wire 130. Figures 3A and 3B are interleaved, which creates a non-zero sequence current that oscillates back and forth in the conductor 130. This eliminates the need for additional heating equipment and allows the battery pack 11 to be heated quickly in a short time, enabling the battery pack 11 to achieve a self-heating effect, increasing the temperature of the battery pack 11, and ensuring that the vehicle can drive normally in low-temperature environments.

[0073] Of course, during the first time period mentioned above, the motor 120 can also charge the first battery cell group 111. During this process, the charging current generates heat on the internal resistance of the first battery cell group 111, heating the first battery cell group 111, while a non-zero sequence current flows through the wire 130. During the second time period mentioned above, the motor 120 can also charge the second battery cell group 112. During this process, the charging current generates heat on the internal resistance of the second battery cell group 112, heating the second battery cell group 112, while a non-zero sequence current flows through the wire 130. The specific process can be referred to the description above, and will not be repeated here.

[0074] It is worth noting that the direction of the non-zero sequence current flowing through the conductor 130 in Figure 3A is the same as the magnitude of the non-zero sequence current flowing through the conductor 130 in Figure 3B, but the direction is opposite. Therefore, when the voltage vector of the output torque of the motor 120 is a non-zero voltage vector, the current in the conductor 130 is 0.

[0075] In some embodiments, in the vector control model of motor 120, the three-phase voltage vector of motor 120 can be controlled by motor controller 150 to control the synthetic magnetomotive force of motor 120, thereby realizing the output torque of motor 120.

[0076] A classic voltage vector control technique is SVPWM control. The eight possible combinations of the six switches are ordered in binary, designated U0 to U7 (from 000 to 111, where 000 represents all upper switches off and 111 represents all upper switches on). U0 and U7 are collectively referred to as zero-voltage vectors, while U1 to U6 are collectively referred to as non-zero-voltage vectors. In traditional three-phase three-wire star-connected motor control, the three-phase voltages in the zero-voltage vector have the same direction, failing to generate torque (current) and thus limiting the motor's output capacity. However, to maintain a constant PWM (Pulse Width Modulation) period, when the sum of the durations of two adjacent voltage vectors is less than the PWM period, zero-voltage vectors are used for compensation.

[0077] In this embodiment, when the motor 120 is driven normally, the classic FOC (Field-Oriented Control) and SVPWM (Space Vector Pulse Width Modulation) are used to drive and control the motor 120. At this time, the zero-sequence current in the wire 130 can oscillate and heat the first battery cell group 111 and the second battery cell group 112.

[0078] When the vehicle is driving at low temperatures and the battery needs to be heated, the original FOC algorithm is modified. On the basis of the original given drive current, a zero-sequence current is superimposed, which further increases the current in the wire 130. At the same time, the frequency of the self-heating current of the battery pack 11 is controlled by controlling the frequency of the zero-sequence current. As described above, the frequency of the self-heating current of the battery pack 11 is the same as the frequency of the injected zero-sequence current. The amplitude of the self-heating current of the battery pack 11 can be calibrated by controlling the amplitude of the zero-sequence current.

[0079] To facilitate understanding and further explanation of why the self-heating current of battery pack 11 can be controlled by controlling the zero-sequence current, Figure 1 is transformed according to Thevenin's equivalent theorem, that is, Figure 1 can be equivalent to the sum of Figure 2A and Figure 2B.

[0080] In the six non-zero voltage vectors (U1~U6) that the motor controller 150 controls the output torque of the motor 120 by controlling the states of the first bridge group 1511 and the second bridge group 1512 of its internal bridge arm assembly 151, the circuit state is always such that the total positive current equals the total negative current, as shown in Figures 3A and 3B (taking voltage vector 100 as an example). When the motor 120 is driving normally, the positive and negative currents of the bus 14 are always equal, equivalent to Figures 3A and 3B respectively. In Figure 3A, current 1 in conductor 130 = -current in positive bus 141 (opposite direction); in Figure 3B, current 2 in conductor 130 = -current in negative bus 142 (opposite direction); by Thevenin's equivalent theorem, current in conductor 130 = current 1 in conductor 130 + current 2 in conductor 130 = -(current in positive bus 141 + current in negative bus 142) = 0, that is, the current in conductor 130 is 0. In other words, among the six non-zero voltage vectors that can output torque, the current in wire 130 is 0.

[0081] When the motor controller 150 controls the output torque of the motor 120 to be zero vector (000 and 111) by controlling the state of the first bridge group 1511 and the second bridge group 1512 of its own inner bridge arm assembly 151, the motor 120 cannot output torque. At this time, the current in the conductor 130 is equal to the current in the corresponding bus 14. U0 (000) is shown in Figure 4A, and U7 (111) is shown in Figure 4B. At this time, by controlling the switching of U0 and U7, the direction of the current in the conductor 130 can be controlled to complete the oscillation heating of the battery pack 11.

[0082] According to another aspect of this application, as shown in FIG5, an electrical device 200 is provided, which includes a heating system 100 for a battery pack and a control system 300 for controlling the operation of the heating system 100 for the battery pack.

[0083] The heating system 100 of the battery pack can be implemented as the heating system 100 of the battery pack mentioned above, which can be referred to in the above description and will not be repeated here.

[0084] It should be noted that the electrical equipment 200 mentioned above may include vehicles, ships, aircraft, energy storage equipment, etc., without limitation.

[0085] In summary, the battery pack heating system and electrical equipment according to the embodiments of this application connect the series connection point between the internal battery cells and the neutral point of the electrical device through wires. Without the need for additional heating equipment, the battery pack can be heated rapidly in a short time, enabling the battery pack to achieve a self-heating effect, increasing the temperature of the battery pack, and ensuring that the vehicle can drive normally in low-temperature environments.

[0086] Although exemplary embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above exemplary embodiments are merely illustrative and are not intended to limit the scope of this application. Various changes and modifications can be made therein by those skilled in the art without departing from the scope and spirit of this application. All such changes and modifications are intended to be included within the scope of this application as claimed in the appended claims.

[0087] Similarly, it should be understood that, in order to simplify this application and aid in understanding one or more aspects of the application, various features of this application may sometimes be grouped together in a single embodiment, figure, or description thereof in the description of exemplary embodiments of this application. However, this approach should not be construed as reflecting an intention that the claimed application requires more features than are expressly recited in each claim. Rather, as reflected in the corresponding claims, the point of application is that the corresponding technical problem can be solved with fewer features than all of a single disclosed embodiment. Therefore, the claims following the detailed description are hereby expressly incorporated into that detailed description, wherein each claim itself is a separate embodiment of this application.

[0088] Furthermore, those skilled in the art will understand that although some embodiments described herein include certain features but not others included in other embodiments, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, in the claims, any one of the claimed embodiments can be used in any combination.

[0089] It should be noted that the above embodiments are illustrative of this application and not limiting of it, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses should not be construed as limiting the claims. The use of the words first, second, and third, etc., does not indicate any order. These words can be interpreted as names.

Claims

1. A heating system (100) of a battery pack, wherein, The heating system of the battery pack comprises: a battery pack (11) comprising a first cell group (111) and a second cell group (112) connected in series; an electrical device (12); and a wire (130) having opposite first and second ends, the first end of the wire being connected to a series point (a) between the first cell group and the second cell group, and the second end of the wire being connected to a neutral point (n) of the electrical device.

2. The heating system of the battery pack of claim 1, wherein, The series point between the first cell group and the second cell group is a potential midpoint of the battery pack.

3. The heating system of the battery pack according to claim 2, wherein: when the voltage at the potential midpoint is greater than the voltage at the neutral point, the direction of the current in the wire is a first direction (D1) from the battery pack to the electrical device; when the voltage at the potential midpoint is less than the voltage at the neutral point, the direction of the current in the wire is a second direction (D2) from the electrical device to the battery pack.

4. The heating system of the battery pack according to claim 3, wherein: the current in the wire comprises a driving current for driving the electrical device to operate.

5. The heating system of the battery pack of claim 3 or 4, wherein, the current in the wire comprises a zero sequence current.

6. The heating system of the battery pack of claim 5, wherein, a ratio of the zero sequence current to the total current in the wire is variable, and the ratio ranges from (0, 1].

7. The heating system of the battery pack of claim 5 or 6, wherein, The heating system of the battery pack further comprises: a controller (15) electrically connected to the electrical device for controlling the zero sequence current.

8. The heating system of the battery pack of claim 7, wherein, The electrical device comprises a motor (120), and the controller comprises a motor controller (150).

9. The heating system of the battery pack of claim 8, wherein, The motor controller comprises a plurality of bridge arm assemblies (151), each of the bridge arm assemblies comprising a first bridge group (1511) and a second bridge group (1512) connected in series, a first end of the first bridge group being connected to a first electrode (E1) of the battery pack, a second end of the first bridge group being connected to a first end of the second bridge group, a second end of the second bridge group being connected to a second electrode (E2) of the battery pack, and a series point of the first bridge group and the second bridge group in each of the bridge arm assemblies being connected to a coil of the motor.

10. The heating system of the battery pack of claim 9, wherein, The motor controller controls the zero sequence current by controlling the states of the first bridge group and the second bridge group of the bridge arm assemblies in the motor controller.

11. The heating system of the battery pack of claim 10, wherein, The battery pack is further connected to the motor controller through a bus bar (14); when the motor controller controls the first bridge group to be turned on and the second bridge group to be turned off in the bridge arm assemblies in the motor controller, or controls the first bridge group to be turned off and the second bridge group to be turned on in the bridge arm assemblies in the motor controller, a voltage vector of an output torque of the motor is a zero voltage vector, and the zero sequence current is equal to a current of the bus bar.

12. The heating system of the battery pack of claim 11, wherein, The zero voltage vector comprises a first zero voltage vector and a second zero voltage vector; when the motor controller controls the first bridge group to be turned on and the second bridge group to be turned off in the bridge arm assemblies in the motor controller, the voltage vector of the output torque of the motor is the first zero voltage vector, and the direction of the zero sequence current is opposite to the direction of a current of a positive bus bar (141) in the bus bar. When the motor controller controls the first bridge group in one of the bridge arm assemblies to be on and the second bridge group to be off, and the first bridge group in the rest of the bridge arm assemblies to be off and the second bridge group to be on, the voltage vector of the output torque of the motor is a non-zero voltage vector, and the current in the wire includes a non-zero sequence current.

13. The heating system of the battery pack of any one of claims 9 to 12, wherein, 14. The heating system of the battery pack according to any one of claims 9 to 13, wherein: in a first time period, the motor controller controls the first bridge group in the bridge arm assemblies to be on and the second bridge group to be off, and the first cell group discharges to the motor or the motor charges to the first cell group; in a second time period, the motor controller controls the first bridge group in the bridge arm assemblies to be off and the second bridge group to be on, and the second cell group discharges to the motor or the motor charges to the second cell group; wherein the first time period and the second time period do not overlap. the motor controller controls the first bridge group in one of the bridge arm assemblies to be on and the second bridge group to be off, and the first bridge group in the rest of the bridge arm assemblies to be off and the second bridge group to be on; 15. The heating system of the battery pack of any one of claims 9 to 14, wherein, in a first time period, the first cell group discharges to the motor or the motor charges to the first cell group; in a second time period, the second cell group discharges to the motor or the motor charges to the second cell group; wherein the first time period and the second time period do not overlap. The heating system of the battery pack comprises:

16. A heating system (100) of a battery pack, wherein a battery pack (11) comprising a first cell group (111) and a second cell group (112) connected in series; an electrical device (12); and a wire (130) having opposite first and second ends, the first end of the wire being connected to a series connection point (a) between the first cell group and the second cell group, and the second end of the wire being connected to a neutral point (n) of the electrical device; wherein the series connection point between the first cell group and the second cell group is a potential midpoint of the battery pack; wherein when the voltage at the potential midpoint is greater than the voltage at the neutral point, the direction of the current in the wire is a first direction (D1) from the battery pack to the electrical device, and when the voltage at the potential midpoint is less than the voltage at the neutral point, the direction of the current in the wire is a second direction (D2) from the electrical device to the battery pack; wherein the current in the wire includes a driving current for driving the electrical device to operate and a zero sequence current. The ratio of the zero sequence current to the total current in the wire is variable, and the range of the ratio is (0, 1].

17. The heating system of the battery pack of claim 16, wherein, The heating system of the battery pack further comprises:

18. The heating system of the battery pack of claim 16 or 17, wherein, ​ A controller (15) is electrically connected with the electrical device for controlling the zero sequence current.

19. The heating system of the battery pack of claim 18, wherein, The electrical device includes a motor (120), and the controller includes a motor controller (150).

20. An electrical consumer (200), wherein The electrical device includes the heating system of the battery pack according to any one of claims 1-19.

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