Alternating current heating system for power battery and vehicle

Abstract

The embodiment of the application discloses an alternating current heating system of a power battery and a vehicle, the system comprises the power battery, a capacitor, an inductive winding of a three-phase motor and a three-phase inverter, any phase inductive winding of the three-phase motor is used as a battery connection phase, the battery connection phase is connected with the power battery through a first relay, and a second relay is arranged between the battery connection phase and the three-phase inverter; when the first relay is closed and the second relay is disconnected, the inductive winding of the three-phase motor, the power battery, the capacitor and the three-phase inverter form a charging and discharging circuit, and a charging and discharging current of the charging and discharging circuit is used to heat the power battery. The power battery is heated without additionally increasing an independent heating circuit, so that the heating cost is reduced.

Description

Technical Field

[0001] This application relates to the field of electric vehicle technology, and in particular to an AC heating system for a power battery and a vehicle. Background Technology

[0002] In low-temperature environments, existing electric vehicle power batteries generally suffer from problems such as difficulty in charging, reduced discharge efficiency, and decreased cycle life. Therefore, it is necessary to heat the power battery before it is put into operation. However, traditional power battery heating solutions mainly rely on external heating elements such as PTC heaters, which require modifications to the three-phase motor connected to the power battery and the addition of an independent heating circuit, resulting in high heating costs. Utility Model Content

[0003] This application provides an AC heating system for a power battery and a vehicle, which heats the power battery without adding an additional independent heating circuit, thereby reducing heating costs.

[0004] This application provides the following solution:

[0005] According to the first aspect, an AC heating system for a power battery includes a power battery, a capacitor, an inductor winding of a three-phase motor, and a three-phase inverter. Any one phase of the inductor winding of the three-phase motor serves as the battery connection phase. The battery connection phase is connected to the power battery through a first relay, and a second relay is provided between the battery connection phase and the three-phase inverter.

[0006] When the first relay is closed and the second relay is open, the inductor winding of the three-phase motor, the power battery, the capacitor, and the three-phase inverter form a charging and discharging circuit, and the charging and discharging current of the charging and discharging circuit is used to heat the power battery.

[0007] As an alternative, the first input port of the three-phase inverter is connected to the first terminal of the power battery and the first terminal of the capacitor; the second input port of the three-phase inverter is connected to the second terminal of the power battery and the second terminal of the capacitor.

[0008] The three-phase output ports of the three-phase inverter are respectively connected to the three-phase inductor windings of the three-phase motor. Any one of the three-phase inductor windings serves as the battery connection phase and is connected to one of the phase output ports of the three-phase inverter through the second relay.

[0009] As an alternative, when the first relay is closed and the second relay is open, the switching devices in the three-phase inverter connected to the battery connection are disconnected.

[0010] In the three-phase motor, the other two inductor windings besides the battery-connected phase serve as capacitor-connected phases, and the switching devices in the three-phase inverter connected to the capacitor-connected phases switch between on and off states.

[0011] As an optional feature, the AC heating system further includes: a controller;

[0012] The controller is used to output a status control signal to the three-phase inverter.

[0013] As an optional approach, a current sensor is provided between the capacitor connection phase and the three-phase inverter;

[0014] The current sensor is used to acquire the current acquisition signal of the capacitor-connected phase and output the current acquisition signal to the controller.

[0015] As an optional approach, a third relay is provided between the first terminal of the power battery and the first terminal of the capacitor;

[0016] When the first relay is closed and the second relay is open, the third relay is open;

[0017] When the first relay is open and the second relay is closed, the third relay is closed, and the power battery and the capacitor form a power supply circuit.

[0018] As an alternative, a pre-charging circuit is provided between the first end of the power battery and the first end of the capacitor, the pre-charging circuit including a fourth relay and a pre-charging resistor connected in series;

[0019] When the first relay is closed and the second relay is open, the fourth relay is open;

[0020] When the first relay is open and the second relay is closed, the fourth relay is closed, and the power battery, the pre-charge resistor, and the capacitor form a pre-charge circuit.

[0021] As an alternative, the switching devices of each phase in the three-phase inverter include an upper bridge arm switch and a lower bridge arm switch. The upper bridge arm switch is connected to the first input port, the lower bridge arm switch is connected to the second input port, and an output port is formed between the upper bridge arm switch and the lower bridge arm switch.

[0022] As an alternative, when the first relay is closed and the second relay is open, both the upper bridge arm switch and the lower bridge arm switch connected to the battery connection phase are open; the other two inductor windings of the three-phase motor, excluding the battery connection phase, are respectively used as capacitor connection phases, and when either the upper bridge arm switch or the lower bridge arm switch connected to the capacitor connection phase is closed, the other switch is open.

[0023] According to a second aspect, a vehicle is provided, including an AC heating system for a power battery as described in the first aspect above.

[0024] The solution provided in this application, based on the existing system including a power battery, capacitor, inductor windings of a three-phase motor, and a three-phase inverter, uses any one phase of the inductor winding of the three-phase motor as the battery connection phase, adds a first relay connecting the battery connection phase and the power battery, and adds a second relay between the battery connection phase and the three-phase inverter. When the first relay is closed and the second relay is open, the inductor windings of the three-phase motor and the three-phase inverter can form a charging and discharging circuit between the power battery and the capacitor, allowing the power battery and the capacitor to perform AC charging and discharging through the charging and discharging circuit. It can be understood that this application can ensure the formation of a charging and discharging circuit between the power battery and the capacitor simply by adding a relay switch, allowing AC current to flow repeatedly between the power battery and the capacitor, and the power battery and the capacitor to charge and discharge alternately. In this way, the internal resistance of the power battery itself can be used to generate heat, thereby achieving the purpose of heating the power battery. Compared with the traditional solution that relies on external heating elements such as PTC heaters, this application does not require structural modifications to the three-phase motor, nor does it require the addition of an independent heating circuit, which can effectively reduce heating costs.

[0025] Of course, any product implementing this application does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 A circuit architecture diagram of an AC heating system for a power battery provided in an embodiment of this application;

[0028] Figure 2 Electrical connection diagram in heating mode of the AC heating system of the power battery provided in the embodiments of this application;

[0029] Figure 3 A diagram showing the current flow direction of the power battery discharge in the AC heating system of the power battery provided in the embodiments of this application;

[0030] Figure 4 A diagram showing the current flow direction during charging of a power battery in an AC heating system provided in an embodiment of this application.

[0031] Figure 5 Electrical connection diagram in power mode of the AC heating system of the power battery provided in the embodiments of this application. Detailed Implementation

[0032] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0033] The terminology used in the embodiments of this utility model is for the purpose of describing particular embodiments only and is not intended to be limiting of the utility model. The singular forms "a," "the," and "the" as used in the embodiments of this utility model and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0034] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0035] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0036] In existing technologies, under low-temperature conditions, the power batteries of current electric vehicles generally suffer from problems such as difficulty in charging, reduced discharge efficiency, and decreased cycle life. Therefore, it is necessary to heat the power battery before it works. However, traditional power battery heating solutions mainly rely on external heating elements such as PTC heaters, which require modifications to the three-phase motor connected to the power battery and the addition of an independent heating circuit, resulting in high heating costs.

[0037] To address the aforementioned issues, the inventors of this application discovered that energy conversion using existing electrical components in vehicles can avoid the need for external heating elements. Therefore, by analyzing the energy interaction characteristics between the inductor windings of a three-phase motor and the power battery and capacitor, they proposed incorporating the inductor windings of the three-phase motor as part of a charging and discharging circuit, utilizing the heat generated during the charging and discharging process of alternating current to heat the power battery.

[0038] Therefore, this application provides an AC heating system for a power battery and a vehicle for heating the power battery without adding an additional independent heating circuit, thereby reducing heating costs.

[0039] refer to Figure 1 , Figure 1 This is a circuit architecture diagram of an AC heating system for a power battery provided in an embodiment of this application. This application provides an AC heating system for a power battery, including a power battery, a capacitor, an inductor winding of a three-phase motor, and a three-phase inverter. Any one phase of the inductor winding of the three-phase motor serves as the battery connection phase. The battery connection phase is connected to the power battery through a first relay, and a second relay is provided between the battery connection phase and the three-phase inverter.

[0040] Among them, such as Figure 1 As shown, the power battery provides electrical energy to the entire circuit. K1 is the third relay, K2 is the fourth relay, and K2 is connected in series with the pre-charge resistor R1 to control the circuit's on / off state and pre-charge. K3 and K4 are the first and second relays, respectively, used to ensure the charging and discharging circuit is open in heating mode. C1 is a capacitor, which can be a thin-film capacitor for the motor controller and participate in the charging and discharging process. S1 to S6 are switching devices in the three-phase inverter, which can be IGBT switches, used to form the three-phase inverter bridge in the three-phase inverter, connected to the inductor windings L1, L2, and L3 of the three-phase motor. The inductor windings L1, L2, and L3 of the three-phase motor... Any one phase can be used as a battery connection phase, connected to the power battery via a first relay, and can also be used as a capacitor connection phase, connected to the capacitor via a second relay. A1 and A2 are current acquisition elements used to acquire the current acquisition signal of the capacitor connection phase. Based on the above circuit architecture, this application can control the charging and discharging circuit to form a charging and discharging current to heat the power battery. For example, in heating mode, the first relay is controlled to close and the second relay is controlled to open, forming a charging and discharging current, so that Joule heat is generated inside the power battery to complete the heating. In power mode, the first relay is controlled to open and the second relay is controlled to close to meet the vehicle's power output requirements.

[0041] refer to Figure 2 , Figure 2 An electrical connection diagram in heating mode for a power battery heating control system provided in this application embodiment; as shown. Figure 2As shown, the three-phase motor has three inductor windings. The V-phase inductor winding can be used as a battery connection phase to connect to the power battery. The U-phase and W-phase inductor windings can be used as capacitor connection phases to connect to the capacitor through the three-phase inverter. The three-phase inverter is used to perform current inversion to form a charging and discharging current as alternating current.

[0042] In some embodiments, the first relay (corresponding to) Figure 1 K3) is installed between the battery connection phase and the positive terminal of the power battery, and the second relay (corresponding to Figure 1 K4 is positioned between the battery connection phase and the three-phase inverter. The first input port of the three-phase inverter is connected to the first terminal of the power battery and the first terminal of the capacitor. The second input port of the three-phase inverter is connected to the second terminal of the power battery and the second terminal of the capacitor. The three-phase output ports of the three-phase inverter are respectively connected to the three-phase inductor windings of the three-phase motor. Any one of the three-phase inductor windings serves as the battery connection phase and is connected to one of the output ports of the three-phase inverter through the second relay.

[0043] It is understandable that the first terminal of the power battery is the positive terminal of the power battery, and the second terminal of the power battery is the negative terminal of the power battery. The first terminal of the capacitor is the positive terminal of the capacitor, and the second terminal of the capacitor is the negative terminal of the capacitor. The positive terminal of the capacitor is connected to the positive terminal of the power battery through a pre-charging circuit (including the fourth relay K2 and the pre-charging resistor R1) and a parallel power supply circuit (including the third relay K1). The negative terminal of the capacitor is directly connected to the negative terminal of the power battery. Relays K1 to K4 can be electromagnetic or solid-state relays, used to control the on / off of the current path between the power battery and the capacitor.

[0044] like Figure 2 As shown, this application, based on the existing system including a power battery, capacitor, inductor windings of a three-phase motor, and a three-phase inverter, uses any one phase of the inductor winding of the three-phase motor as the battery connection phase, adds a first relay connecting the battery connection phase and the power battery, and adds a second relay between the battery connection phase and the three-phase inverter. When the first relay is closed and the second relay is open, the inductor windings of the three-phase motor and the three-phase inverter can form a charging and discharging circuit between the power battery and the capacitor, allowing the power battery and the capacitor to perform AC charging and discharging through the charging and discharging circuit. It can be understood that this application can ensure the formation of a charging and discharging circuit between the power battery and the capacitor simply by adding a relay switch, allowing AC current to flow repeatedly between the power battery and the capacitor, and the power battery and the capacitor to charge and discharge alternately. In this way, the internal resistance of the power battery itself can be used to generate heat, thereby achieving the purpose of heating the power battery. Compared with the traditional solution that relies on external heating elements such as PTC heaters, this application does not require structural modifications to the three-phase motor, nor does it require the addition of an independent heating circuit, which can effectively reduce heating costs.

[0045] In some embodiments, when the first relay is closed and the second relay is open, the switching devices in the three-phase inverter connected to the battery connection phase are disconnected; the other two inductor windings in the three-phase motor, excluding the battery connection phase, are respectively used as capacitor connection phases, and the switching devices in the three-phase inverter connected to the capacitor connection phase switch between on and off states.

[0046] It is understood that the system of this application can realize the energy storage and release of the inductor winding in the three-phase inverter by switching the on and off states of the switching devices, so that the charging and discharging circuits can alternately form charging current and discharging current. It is understood that when it is necessary to form the discharging current of the power battery, the inductor winding in the three-phase inverter can form a Boost circuit to raise the capacitor voltage; conversely, when it is necessary to form the charging current of the power battery, the inductor winding in the three-phase inverter can form a Buck circuit to lower the capacitor voltage.

[0047] refer to Figure 3 and Figure 4 , Figure 3 The current flow diagram of the power battery discharge in the AC heating system of the power battery provided in the embodiments of this application is shown. Figure 4 In the AC heating system for a power battery provided in this application embodiment, the current flow diagram for power battery charging is as follows: It can be understood that in the heating scenario of this application, the Boost circuit is manifested in the process of the power battery discharging into the capacitor. For example... Figure 3 As shown, during the power battery discharge phase, current flows out from the positive terminal of the power battery, through the circuit to the battery connection phase (such as L2) in the three-phase motor, and through the capacitor connection phase (such as L1 and L3). The switching devices in the three-phase inverter connected to the capacitor connection phase switch the on and off states, so that the inductor windings (L1, L3) of the three-phase motor enter the energy storage state. The charging and discharging circuit is equivalent to a boost circuit, realizing the voltage rise between the power battery and the capacitor, and completing the energy transfer of the forward current.

[0048] Conversely, the Buck step-down circuit corresponds to the stage where the capacitor charges the power battery. For example... Figure 4 As shown, during the charging phase of the power battery, current flows out from the positive terminal of the capacitor, is regulated by the three-phase inverter, flows to the capacitor connection phases (such as L1 and L3), and then flows through the battery connection phases (such as L2) back to the positive terminal of the power battery. At this time, the switching devices in the three-phase inverter connected to the capacitor connection phase switch between on and off states, causing the inductors (L1, L3) to enter the energy release state. The charging and discharging circuit is equivalent to a buck converter circuit: the energy stored in the capacitor and the energy released by the inductor together charge the power battery, realizing energy recovery from the reverse current.

[0049] In some embodiments, the AC heating system further includes: a controller; the controller being configured to output a status control signal to a three-phase inverter.

[0050] It is understandable that the controller may include a proportional-integral controller (PID) to output a state control signal using pulse width modulation (PWM) technology. The state control signal is an electrical signal used to regulate the on / off state of the power switching devices connected to the capacitor in the three-phase inverter. When the power battery needs to discharge to the capacitor, the state control signal is used to determine the voltage rise of the capacitor; when the capacitor needs to charge the power battery, the state control signal is used to determine the voltage drop of the capacitor.

[0051] In some embodiments, a current sensor is provided between the capacitor-connected phase and the three-phase inverter; the current sensor is used to acquire the current acquisition signal of the capacitor-connected phase and output the current acquisition signal to the controller.

[0052] It is understandable that the current acquisition signal refers to the actual current measurement value of the capacitor-connected phase, which is used to feed back the actual current status to the controller so that the controller responds to the current acquisition signal and outputs a status control signal to the three-phase inverter.

[0053] In some embodiments, the switching devices of each phase in the three-phase inverter include an upper bridge arm switch and a lower bridge arm switch. The upper bridge arm switch is connected to a first input port, and the lower bridge arm switch is connected to a second input port. An output port is formed between the upper bridge arm switch and the lower bridge arm switch. Further, when the first relay is closed and the second relay is open, both the upper bridge arm switch and the lower bridge arm switch connected to the battery connection phase are disconnected. The inductor windings of the other two phases of the three-phase motor, excluding the battery connection phase, are respectively used as capacitor connection phases. When either the upper bridge arm switch or the lower bridge arm switch connected to the capacitor connection phase is closed, the other switch is open.

[0054] Specifically, the upper and lower bridge arm switches are not turned on simultaneously within the same cycle to avoid short-circuit risks. When the upper bridge arm switch connected by the capacitor switches from the open to the closed state, and the lower bridge arm switch connected by the capacitor switches from the closed to the open state, the charging and discharging circuit can act as a boost circuit to generate charging current. When the upper bridge arm switch connected by the capacitor switches from the closed to the open state, and the lower bridge arm switch connected by the capacitor switches from the open to the closed state, the charging and discharging circuit can act as a buck circuit to generate discharging current.

[0055] It is understandable that, such as Figure 1As shown, S1, S2, and S3 are the upper bridge arm switches, and S4, S5, and S6 are the lower bridge arm switches. The complementary switching of the upper and lower bridge arm switches is used to achieve bidirectional energy conversion. When the upper bridge arm switch of the capacitor-connected phase is closed and the lower bridge arm switch is open, the power battery's electrical energy flows into the capacitor through the inductor winding. At this time, the inductor stores some energy in the form of a magnetic field. After being superimposed on the battery's output voltage, the voltage at the capacitor terminals increases. At this time, the current flows from the power battery to the capacitor, forming a discharge process for the battery. When the upper bridge arm switch is open and the lower bridge arm switch is closed, the high-voltage electrical energy stored in the capacitor drives the current to flow in the opposite direction. The inductor winding releases the previously stored energy, which, together with the capacitor's energy, is delivered to the power battery. At this time, the circuit is equivalent to a step-down topology. The capacitor voltage is reduced after being buffered by the inductor's energy release, adapting to the charging needs of the power battery, forming the battery charging process.

[0056] In some embodiments, the rotor angle of the three-phase motor is set to a preset angle, and the phase currents of the two capacitor-connected phases are the same. The preset angle can be 120 degrees, which is set based on the spatial distribution characteristics of the inductor windings of the three-phase motor. When the rotor angle is set to 120 degrees, the three-phase motor has no torque output. The V-phase inductor winding of the three-phase motor is connected to the positive terminal of the power battery as a battery connection phase. The inductor windings of the two capacitor-connected phases (such as the U-phase and W-phase) have the same coupling degree with the rotor magnetic field and the same equivalent impedance. The two capacitor-connected phases can form phase currents of equal magnitude and matching direction, thereby ensuring that energy is transferred only between the power battery and the capacitor, avoiding energy loss caused by motor rotation.

[0057] refer to Figure 5 , Figure 5 An electrical connection diagram in power mode for the AC heating system of a power battery provided in the embodiments of this application; as shown. Figure 5 This application further proposes that a third relay is provided between the first terminal of the power battery and the first terminal of the capacitor; when the first relay is closed and the second relay is open, the third relay is open; when the first relay is open and the second relay is closed, the third relay is closed, and the power battery and the capacitor form a power supply circuit.

[0058] In some embodiments, a pre-charging circuit is provided between the first end of the power battery and the first end of the capacitor. The pre-charging circuit includes a fourth relay and a pre-charging resistor connected in series. When the first relay is closed and the second relay is open, the fourth relay is open. When the first relay is open and the second relay is closed, the fourth relay is closed, and the power battery, the pre-charging resistor, and the capacitor form a pre-charging circuit.

[0059] The power supply circuit and the pre-charging circuit are connected in parallel. The pre-charging circuit is a current limiting path formed by the fourth relay and the pre-charging resistor in series. It can be implemented by combining an electromagnetic relay and a carbon film resistor to limit the capacitor charging current when the system starts. The power supply circuit is a low-impedance path formed by the direct connection of the third relay. It can be implemented by a high-power contactor to provide a low-loss current path when the system is running stably. The power mode refers to the vehicle being in driving or energy output mode. At this time, the AC heating system needs to adjust the circuit topology according to the driving requirements. The switching of the on and off states of the third and fourth relays can realize the hierarchical management of the current during the capacitor charging process.

[0060] It is understood that after the power battery is heated in the heating mode, the application can enter the power mode to enable the power battery to operate normally. In this state, the first relay can be disconnected to cut off the charging and discharging circuit, and the second relay can be closed to activate the capacitor connection phase. At this time, the pre-charging circuit is preferentially turned on, and the pre-charging resistor limits the initial charging current of the capacitor to avoid the surge current impacting the three-phase inverter. Then, when the capacitor voltage reaches the preset threshold, the third relay is closed to bypass the pre-charging circuit, reducing conduction losses. This allows the AC heating system to dynamically adjust the switching timing of the fourth and third relays according to the real-time power output demand. For example, the working time of the pre-charging circuit can be extended when the power demand is low, and the power supply circuit can be quickly switched when the power demand is high, effectively suppressing the impact of current surges on circuit components and improving circuit reliability.

[0061] In some embodiments, the implementation process of the AC heating system based on the power battery can be as follows: During pulse heating, the switching devices in the three-phase inverter connected by the capacitors in this application switch between on and off states. First, a Boost circuit is formed to charge the capacitors from the power battery. At this time, the current is a positive current of a sinusoidal current. Then, a Buck circuit is formed to charge the power battery from the capacitors. At this time, the current is a negative current of a sinusoidal current. This allows the power battery and the capacitor to perform AC charging and discharging through the charging and discharging circuit, thereby heating the power battery without adding an additional independent heating circuit, thus reducing heating costs.

[0062] This application further proposes a vehicle that may include: an AC heating system for the power battery of the first aspect described above, which heats the power battery without adding an additional independent heating circuit, thereby reducing heating costs, as described in any of the embodiments of the first aspect.

[0063] In the embodiments provided in this application, it should be understood that the disclosed system can be implemented in other ways. For example, the system embodiments described above are merely illustrative. For instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces or units, and may be electrical, mechanical, or other forms.

[0064] The technical solutions provided in this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the system and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. An AC heating system for a power cell, characterized by The system includes a power battery, a capacitor, an inductor winding of a three-phase motor, and a three-phase inverter. Any one phase of the inductor winding of the three-phase motor serves as the battery connection phase. The battery connection phase is connected to the power battery via a first relay, and a second relay is provided between the battery connection phase and the three-phase inverter. When the first relay is closed and the second relay is open, the inductor winding of the three-phase motor, the power battery, the capacitor, and the three-phase inverter form a charging and discharging circuit, and the charging and discharging current of the charging and discharging circuit is used to heat the power battery.

2. The system of claim 1, wherein, The first input port of the three-phase inverter is connected to the first terminal of the power battery and the first terminal of the capacitor; the second input port of the three-phase inverter is connected to the second terminal of the power battery and the second terminal of the capacitor. The three-phase output ports of the three-phase inverter are respectively connected to the three-phase inductor windings of the three-phase motor. Any one of the three-phase inductor windings serves as the battery connection phase and is connected to one of the phase output ports of the three-phase inverter through the second relay.

3. The system of claim 1, wherein, When the first relay is closed and the second relay is open, the switching devices in the three-phase inverter connected to the battery connection are disconnected; In the three-phase motor, the other two inductor windings besides the battery-connected phase serve as capacitor-connected phases, and the switching devices in the three-phase inverter connected to the capacitor-connected phases switch between on and off states.

4. The system of claim 3, wherein, The AC heating system also includes: a controller; The controller is used to output a status control signal to the three-phase inverter.

5. The system of claim 4, wherein, A current sensor is provided between the capacitor connection phase and the three-phase inverter; The current sensor is used to acquire the current acquisition signal of the capacitor-connected phase and output the current acquisition signal to the controller.

6. The system of claim 2, wherein, A third relay is provided between the first end of the power battery and the first end of the capacitor; When the first relay is closed and the second relay is open, the third relay is open; When the first relay is open and the second relay is closed, the third relay is closed, and the power battery and the capacitor form a power supply circuit.

7. The system of claim 2, wherein, A pre-charging circuit is provided between the first end of the power battery and the first end of the capacitor. The pre-charging circuit includes a fourth relay and a pre-charging resistor connected in series. When the first relay is closed and the second relay is open, the fourth relay is open; When the first relay is open and the second relay is closed, the fourth relay is closed, and the power battery, the pre-charge resistor, and the capacitor form a pre-charge circuit.

8. The system of claim 2, wherein, Each phase of the three-phase inverter includes an upper bridge arm switch and a lower bridge arm switch. The upper bridge arm switch is connected to the first input port, and the lower bridge arm switch is connected to the second input port. An output port is formed between the upper bridge arm switch and the lower bridge arm switch.

9. The system of claim 8, wherein, When the first relay is closed and the second relay is open, both the upper bridge arm switch and the lower bridge arm switch connected to the battery connection phase are open; the other two inductor windings of the three-phase motor, excluding the battery connection phase, are respectively used as capacitor connection phases. When either the upper bridge arm switch or the lower bridge arm switch connected to the capacitor connection phase is closed, the other switch is open.

10. A vehicle characterized by comprising: The AC heating system of the power battery as described in any one of claims 1 to 9.

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