Heating control method, heating control device and vehicle for power battery

Abstract

The embodiment of the application discloses a kind of heating control method of power battery, heating control device and vehicle, method is applied to alternating current heating system, system includes power battery, electric capacity, the inductance winding of three-phase motor and three-phase inverter, any one phase inductance winding in three-phase motor as battery connection phase, battery connection phase is connected with power battery by first relay, second relay is arranged between battery connection phase and three-phase inverter;Wherein, method includes: control first relay closure, second relay disconnect, form charge-discharge circuit, charge-discharge circuit includes the inductance winding of three-phase motor, three-phase inverter, power battery and electric capacity;Control charge-discharge circuit forms charge-discharge current, to heat power battery.The application is heated to power battery without additional increase independent heating circuit, to reduce heating cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric vehicles, in particular to a heating control method and device of a power battery and a vehicle. BACKGROUND

[0002] In a low temperature environment, the existing power battery of an electric vehicle generally has problems such as charging difficulty, discharge efficiency reduction and cycle life attenuation, so the power battery needs to be heated before working. The traditional power battery heating scheme mainly relies on external heating elements such as PTC heaters, which requires modification of the three-phase motor connected to the power battery and additional independent heating circuits, resulting in high heating cost. SUMMARY

[0003] The present application provides a heating control method and device of a power battery and a vehicle, which can heat the power battery without additional independent heating circuits, thereby reducing the heating cost.

[0004] The present application provides the following solutions:

[0005] According to a first aspect, a heating control method of a power battery is provided, which is applied to an alternating current heating system, the system including a power battery, a capacitor, an inductive winding of a three-phase motor and a three-phase inverter, any one phase inductive winding of the three-phase motor being a battery connection phase, the battery connection phase being connected to the power battery through a first relay, and a second relay being arranged between the battery connection phase and the three-phase inverter.

[0006] The method includes the following steps:

[0007] controlling the first relay to be closed and the second relay to be opened, so as to form a charging and discharging circuit, the charging and discharging circuit including the inductive winding of the three-phase motor, the three-phase inverter, the power battery and the capacitor;

[0008] controlling the charging and discharging circuit to form a charging and discharging current, so as to heat the power battery.

[0009] As an optional way, the other two phase inductive windings of the three-phase motor except the battery connection phase are capacitor connection phases, the capacitor connection phases are connected to the capacitor through the three-phase inverter, and the step of controlling the charging and discharging circuit to form a charging and discharging current includes the following steps:

[0010] controlling the on-off state of a switching device in the three-phase inverter connected to the capacitor connection phase, so as to increase or decrease the voltage of the capacitor, so that the charging and discharging circuit alternately forms a charging current and a discharging current, the charging current and the discharging current flow through the power battery in opposite directions.

[0011] As an optional mode, the control of the on-off state of the switching device connected by the capacitor connection phase includes:

[0012] Obtaining the target current signal of the power battery;

[0013] Based on the target current signal of the power battery and the current acquisition signal of the two capacitor connection phases, the control signal of the switching device connected by the capacitor connection phase is determined;

[0014] Based on the control signal, the on-off state of the switching device connected by the capacitor connection phase is controlled.

[0015] As an optional mode, the control of the on-off state of the switching device connected by the capacitor connection phase includes:

[0016] Based on the difference between the target current signal and the sum of the two current acquisition signals, proportional integral calculation is performed to obtain the target duty cycle signal;

[0017] The switching device connected by the battery connection phase is controlled to be disconnected, and the control signal of the switching device connected by the capacitor connection phase is determined according to the target duty cycle signal.

[0018] As an optional mode, the obtaining of the target current signal of the power battery includes:

[0019] Based on the pulse heating demand of the power battery, the charge-discharge amplitude and the charge-discharge frequency when the battery connection phase performs sinusoidal alternating charge-discharge are determined;

[0020] According to the charge-discharge amplitude and the charge-discharge frequency, the target current signal of the power battery is determined.

[0021] As an optional mode, before controlling the charge-discharge circuit to form a charge-discharge current to heat the power battery, it further includes:

[0022] Adjust the rotor angle of the three-phase motor to a preset angle, so that the phase currents of the two capacitor connection phases are the same.

[0023] As an optional mode, a third relay is further arranged between the power battery and the capacitor, and the method further includes:

[0024] When the first relay is closed and the second relay is disconnected, the third relay is controlled to be disconnected;

[0025] When the first relay is closed and the second relay is opened, the third relay is controlled to be closed, so that the power battery and the capacitor form a power supply loop.

[0026] As an optional mode, a pre-charging circuit is further arranged between the power battery and the capacitor, the pre-charging circuit comprising a fourth relay and a pre-charging resistor connected in series, and the method further comprises:

[0027] When the first relay is closed and the second relay is opened, the fourth relay is controlled to be opened;

[0028] When the first relay is closed and the second relay is opened, the fourth relay is controlled to be opened;

[0029] According to a second aspect, a heating control device is provided, the device is applied to an alternating current heating system, the system comprising a 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 serving as a battery connection phase, the battery connection phase being connected with the power battery through a first relay, and a second relay being arranged between the battery connection phase and the three-phase inverter;

[0030] The device comprises:

[0031] a path control module configured to control the first relay to be closed and the second relay to be opened, so as to form a charge-discharge loop, the charge-discharge loop comprising the inductive winding of the three-phase motor, the three-phase inverter, the power battery and the capacitor;

[0032] a current control module configured to control the charge-discharge loop to form a charge-discharge current, so as to heat the power battery.

[0033] According to a third aspect, a vehicle is provided, comprising:

[0034] an alternating current heating system, the system comprising a 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 serving as a battery connection phase, the battery connection phase being connected with the power battery through a first relay, and a second relay being arranged between the battery connection phase and the three-phase inverter;

[0035] a controller configured to execute the steps of the method according to the first aspect.

[0036] The scheme provided by the embodiment of the application can form a charging and discharging circuit by the inductive winding of the three-phase motor and the three-phase inverter when the first relay is closed and the second relay is disconnected, the charging and discharging circuit includes the inductive winding of the three-phase motor, the three-phase inverter, the power battery and the capacitor, and the charging and discharging circuit can form a charging and discharging current, so that the power battery and the capacitor can be charged and discharged through the charging and discharging circuit to heat the power battery. It can be understood that the application only needs to add a relay switch to ensure the formation of the charging and discharging circuit between the power battery and the capacitor, so that the alternating current can repeatedly flow between the power battery and the capacitor, and the power battery and the capacitor alternately charge and discharge, and then the power battery itself can be heated by the internal resistance to achieve the purpose of heating the power battery. Compared with the traditional scheme of relying on PTC heater and other external heating elements, the application does not need to make structural changes to the three-phase motor, and does not need to additionally add an independent heating circuit, so the heating cost can be effectively reduced.

[0037] Of course, implementing any product of the application does not necessarily need to achieve all the advantages described above. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments. Obviously, the drawings in the following description only constitute some embodiments of the application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0039] Figure 1 A circuit architecture diagram suitable for the embodiments of the application.

[0040] Figure 2 A flowchart of the heating control method of the power battery provided by the embodiments of the application.

[0041] Figure 3 An electrical connection diagram in the heating mode in the heating control method of the power battery provided by the embodiments of the application.

[0042] Figure 4 A current flow direction diagram of the power battery discharging in the heating control method of the power battery provided by the embodiments of the application.

[0043] Figure 5 A current flow direction diagram of the power battery charging in the heating control method of the power battery provided by the embodiments of the application.

[0044] Figure 6 The control block diagram of the target current signal in the heating control method of the power battery provided in the embodiments of the present application.

[0045] Figure 7 The electrical connection diagram in the power mode in the heating control method of the power battery provided in the embodiments of the present application.

[0046] Figure 8 The example flow chart of the heating mode in the heating control method of the power battery provided in the embodiments of the present application.

[0047] Figure 9 The schematic block diagram of the AC heating system of the power battery provided in the embodiments of the present application. DETAILED DESCRIPTION

[0048] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art belong to the scope of protection of the present application.

[0049] The terms used in the embodiments of the present application are merely for the purpose of describing the specific embodiments, and are not intended to limit the present application. The singular forms “a”, “an” and “the” used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0050] It should be understood that the term “and / or” used herein is merely to describe the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character “ / ” herein generally represents an “or” relationship between the front and rear associated objects.

[0051] Depending on the context, the word “if” as used herein can be interpreted as “when” or “upon” or “in response to determining” or “in response to detecting”. Similarly, depending on the context, the phrase “if it is determined” or “if (a stated condition or event) is detected” can be interpreted as “when it is determined” or “in response to determining” or “when (a stated condition or event) is detected” or “in response to detecting (a stated condition or event)”.

[0052] 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.

[0053] 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 three-phase motor, the power battery, and the capacitor, they proposed incorporating the inductor winding in the three-phase motor as part of the charging and discharging circuit, utilizing the heat generated during the charging and discharging process of alternating current to heat the power battery.

[0054] Therefore, this application provides a heating control method, heating control device, and vehicle for power batteries, which can heat the power batteries without adding an additional independent heating circuit, thereby reducing heating costs.

[0055] refer to Figure 1 , Figure 1 This is a circuit architecture diagram applicable to the embodiments of this application; such as Figure 1 As shown, this circuit architecture is used in control scenarios related to power batteries, and is used to implement the power battery heating control method in this application. 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, 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, and connected to the inductor windings L1, L2, and L3 in the three-phase motor. The circuit can be configured such that any one of the inductor windings L1, L2, and L3 in the three-phase motor can be used as a battery connection phase, connected to the power battery via a first relay, or 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 closed and the second relay is open to form a charging and discharging current, causing Joule heat to be generated inside the power battery to complete the heating. In power mode, the first relay is opened and the second relay is closed to meet the vehicle's power output requirements.

[0056] refer to Figure 2 ,Figure 2 A flowchart of a power battery heating control method provided in an embodiment of this application; see reference. Figure 2 This application provides a heating control method for a power battery. The method is applied to an AC heating system, which 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. The control method may include at least the following steps:

[0057] Step 201: Control the first relay to close and the second relay to open, forming a charging and discharging circuit. The charging and discharging circuit includes the inductor winding of the three-phase motor, the three-phase inverter, the power battery, and the capacitor.

[0058] Step 202: Control the charging and discharging circuit to generate charging and discharging current to heat the power battery.

[0059] The three-phase motor has three inductor windings, as referenced. Figure 3 , Figure 3 The electrical connection diagram in the heating mode of the power battery heating control method provided in the embodiments of this application; as shown. Figure 3 The V-phase inductor winding can be used as a battery connection phase to connect to the power battery, while 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 AC power.

[0060] In some embodiments, the first relay (corresponding to) Figure 1 K3 in the middle is set between the battery connection phase and the positive terminal of the power battery, and the second relay (corresponding to Figure 1 K4 is located between the battery connection phase and the three-phase inverter. The three-phase inverter is connected in parallel with 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 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.

[0061] like Figure 3As shown, the application is based on the original system including a power battery, a capacitor, an inductive winding of a three-phase motor and a three-phase inverter. The application adds a first relay connecting the battery connection phase and the power battery, and a second relay arranged between the battery connection phase and the three-phase inverter. When the first relay is closed and the second relay is opened, the inductive winding of the three-phase motor and the three-phase inverter can form a charging and discharging circuit. The charging and discharging circuit includes the inductive winding of the three-phase motor, the three-phase inverter, the power battery and the capacitor. The charging and discharging circuit can form a charging and discharging current, so that the power battery and the capacitor can be charged and discharged through the charging and discharging circuit to heat the power battery. It can be understood that the application only needs to add a relay switch to ensure the formation of the charging and discharging circuit between the power battery and the capacitor, so that the alternating current can repeatedly flow between the power battery and the capacitor, and the power battery and the capacitor alternately charge and discharge. The power battery can be heated by its own internal resistance to achieve the purpose of heating the power battery. Compared with the traditional scheme relying on external heating elements such as PTC heater, the application does not need to make structural changes to the three-phase motor and does not need to additionally add an independent heating circuit, which can effectively reduce the heating cost.

[0062] In some embodiments, the other two-phase inductive windings of the three-phase motor except the battery connection phase are used as the capacitor connection phase, and the capacitor connection phase is connected with the capacitor through the three-phase inverter. The charging and discharging current formed on the charging and discharging circuit is controlled by controlling the on-off state of the switching device in the three-phase inverter connected with the capacitor connection phase, so that the inductive winding of the three-phase inverter stores and releases energy periodically to increase or decrease the voltage of the capacitor, so that the charging and discharging circuit alternately forms charging current and discharging current, and the directions of the charging current and the discharging current flowing through the power battery are opposite.

[0063] The above process can realize the energy storage and release management of the inductive winding by adjusting the on-off state of the switching device, so as to control the charging and discharging circuit to alternately form charging current and discharging current. It can be understood that when the discharging current of the power battery is needed, the target duty cycle control signal is set to make the inductive winding of the capacitor connection phase enter the energy storage state. At this time, the energy output by the power battery and the magnetic field energy stored by the inductor cooperatively transmit energy to the capacitor through the three-phase inverter, form a Boost circuit, and realize the lifting of the capacitor voltage.

[0064] On the contrary, when the charging current of the power battery is needed, the duty cycle of the control signal is adjusted to make the inductive winding enter the energy release state. At this time, the energy stored by the capacitor and the energy released by the inductor are reversely transmitted to the power battery through the three-phase inverter, form a Buck circuit, and realize the reduction of the capacitor voltage.

[0065] Reference Figure 4and Figure 5 , Figure 4 The current flow diagram of the power battery discharging in the heating control method of the power battery provided by the embodiment of the application, Figure 5 The current flow diagram of the power battery charging in the heating control method of the power battery provided by the embodiment of the application: it can be understood that in the heating control scenario of the application, the Boost circuit is reflected in the process of discharging the power battery to the capacitor. As shown in Figure 4 the power battery discharging stage, the current flows out from the positive electrode of the power battery, flows to the battery connection phase (such as L2) in the three-phase motor through the circuit, and flows through the capacitor connection phase (such as L1 and L3), the on-off state of the switching device in the three-phase inverter connected to the capacitor connection phase is controlled, so that the inductance (L1, L3) of the three-phase motor enters the energy storage state, and the charging and discharging circuit is equivalent to the boost circuit: part of the energy released by the power battery is stored through the inductance, and the other part directly charges the capacitor C1, realizes the voltage rise between the power battery and the capacitor, and completes the energy transfer of the forward current.

[0066] On the contrary, the Buck circuit corresponds to the stage of charging the capacitor to the power battery. As shown in Figure 5 the power battery charging stage, the current flows out from the positive electrode of the capacitor, flows to the capacitor connection phase (such as L1 and L3) after being regulated by the three-phase inverter, and then flows through the battery connection phase (such as L2) to return to the positive electrode of the power battery. At this time, the on-off state of the switching device in the three-phase inverter connected to the capacitor connection phase is controlled, so that the inductance (L1, L3) enters the energy release state, and the charging and discharging circuit is equivalent to the buck circuit: the energy stored by the capacitor and the energy released by the inductance are jointly charged to the power battery, and the energy recovery of the reverse current is realized.

[0067] In some embodiments, the switching device in the three-phase inverter connected to the capacitor connection phase includes an upper bridge arm switch tube and a lower bridge arm switch tube, the upper bridge arm switch tube is connected to the positive electrode of the power battery, and the lower bridge arm switch tube is connected to the negative electrode of the power battery, the on-off state of the switching device connected to the capacitor connection phase is controlled based on the control signal, including: based on the control signal, the upper bridge arm switch tube connected to the capacitor connection phase is switched from the open state to the closed state, and the lower bridge arm switch tube connected to the capacitor connection phase is switched from the closed state to the open state, so that the charging and discharging circuit works as a boost circuit to form a charging current; based on the control signal, the upper bridge arm switch tube connected to the capacitor connection phase is switched from the closed state to the open state, and the lower bridge arm switch tube connected to the capacitor connection phase is switched from the open state to the closed state, so that the charging and discharging circuit works as a buck circuit to form a discharging current.

[0068] In some embodiments, the switching device in the three-phase inverter connected to the capacitor connection phase includes an upper bridge arm switch tube and a lower bridge arm switch tube, the upper bridge arm switch tube is connected to the positive electrode of the power battery, and the lower bridge arm switch tube is connected to the negative electrode of the power battery, the on-off state of the switching device connected to the capacitor connection phase is controlled based on the control signal, including: based on the control signal, the upper bridge arm switch tube connected to the capacitor connection phase is switched from the open state to the closed state, and the lower bridge arm switch tube connected to the capacitor connection phase is switched from the closed state to the open state, so that the charging and discharging circuit works as a boost circuit to form a charging current; based on the control signal, the upper bridge arm switch tube connected to the capacitor connection phase is switched from the closed state to the open state, and the lower bridge arm switch tube connected to the capacitor connection phase is switched from the open state to the closed state, so that the charging and discharging circuit works as a buck circuit to form a discharging current. Figure 1As shown, S1, S2, S3 are the upper bridge arm switch tubes, and S4, S5, S6 are the lower bridge arm switch tubes. The complementary on-off of the upper bridge arm switch tubes and the lower bridge arm switch tubes is used to realize bidirectional energy conversion. When the upper bridge arm switch tube connected to the capacitor phase is closed and the lower bridge arm switch tube is opened, the electric energy of the power battery flows into the capacitor through the inductor winding, and the inductor stores part of the energy in the form of a magnetic field. After superimposing the battery output voltage, the voltage at the capacitor end is raised. At this time, the current flows from the power battery to the capacitor, forming a discharging process for the battery. When the upper bridge arm switch tube is opened and the lower bridge arm switch tube is closed, the high-voltage electric energy stored in the capacitor drives the current to flow in the opposite direction, and the inductor releases the energy stored previously, and the energy of the capacitor is jointly delivered to the power battery. At this time, the circuit is equivalent to a step-down topology, and the capacitor voltage is reduced after being buffered by the inductor energy release, which meets the charging requirements of the power battery, forming a charging process for the battery.

[0069] It can be understood that the alternative switching of the above-mentioned switching states can be realized by the control signal generated according to the target duty cycle signal, which ensures that the upper bridge arm switch tube and the lower bridge arm switch tube are not turned on at the same time in the same period to avoid the risk of short circuit. At the same time, by adjusting the on-time ratio, the energy storage and release period of the inductor is controlled, so that the amplitude and frequency of the charging and discharging current are matched with the heating requirements of the power battery. For example, when the heating power needs to be increased, the on-duty ratio of the upper bridge arm switch tube can be increased to enhance the step-up effect and increase the discharging current amplitude, and the on-duty ratio of the lower bridge arm switch tube is adjusted correspondingly to ensure the reverse balance of the charging current, and then the periodic work of the current on the battery internal resistance is used to realize efficient heating.

[0070] Reference Figure 6 , Figure 6 In the power battery heating control method provided by the embodiments of the present application, a control block diagram of a target current signal is shown as follows: Figure 6 In some embodiments, the control of the on-off state of the switching device connected to the capacitor connection phase of the three-phase inverter includes: obtaining a target current signal of the power battery; determining a control signal of the switching device connected to the capacitor connection phase based on the target current signal of the power battery and current collection signals of two capacitor connection phases; and controlling the on-off state of the switching device connected to the capacitor connection phase based on the control signal.

[0071] The target current signal refers to the set value of the phase current that the battery charging and discharging current needs to reach, and the current collection signal refers to the actual current measurement value of the capacitor connection phase, which is used to feedback the actual current state. By comparing the deviation between the target current signal of the power battery and the current collection signals of the two capacitor connection phases, the on-off state of the switching device in the three-phase inverter can be adjusted to form the charging and discharging current.

[0072] It can be understood that the control signal of the switch device connected by the capacitor connection phase refers to the electrical signal used to regulate the on-off state of the power switch device connected to the capacitor connection phase in the three-phase inverter. Its function is to realize the adjustment of the direction, size and change rate of the capacitor connection phase current by controlling the on-off rhythm of the switch device, so as to complete the heating process by matching the charging and discharging process of the power battery and the capacitor.

[0073] It is worth noting that the control signal determines the current direction and size of the capacitor connection phase by changing the on-off state of the switch device, thereby realizing the alternative switching of the two modes of step-up discharging and step-down charging between the power battery and the capacitor. Specifically, when the power battery needs to discharge to the capacitor, the control signal drives the switch device to be on with a high duty cycle, so that the inductor winding of the capacitor connection phase enters the energy storage state; then the control signal turns to low level, the switch device is turned off, the inductor releases energy and is superimposed with the battery voltage to form a current flowing to the capacitor, which is higher than the battery voltage, to complete the discharging, and the duty cycle of the control signal determines the step-up amplitude. Conversely, when the capacitor needs to charge to the power battery, the control signal drives the switch device to be on with a low duty cycle, and the current released by the capacitor flows through the inductor and stores part of the energy; after the switch device is turned off, the inductor releases energy, which is superimposed with the capacitor current and flows to the power battery at a level lower than the capacitor voltage to complete the charging, and the duty cycle of the control signal determines the step-down amplitude.

[0074] In some embodiments, the target current signal of the power battery is obtained, including: determining the charging and discharging amplitude and the charging and discharging frequency when the battery connection phase is subjected to sinusoidal alternating current charging and discharging based on the pulse heating requirement of the power battery; and determining the target current signal of the power battery according to the charging and discharging amplitude and the charging and discharging frequency.

[0075] Wherein, the pulse heating requirement can contain the difference between the current temperature and the target temperature of the power battery, the maximum allowed heating time and other parameters, the charging and discharging amplitude can correspond to the peak value of the sinusoidal alternating current, and the size is positively correlated with the heating power, the charging and discharging frequency can match the resonance characteristics of the inductor winding of the three-phase motor and the capacitor, and be selected within a predetermined range to avoid high-frequency switching loss or excessive current ripple at low frequency.

[0076] It can be understood that after the charging and discharging amplitude and the charging and discharging frequency are determined, the value of the target current signal can be obtained by the current waveform formula I= A sin(2*π *f* t) where I is the target current signal, is the charging and discharging amplitude, is the alternating current charging and discharging frequency, π is a mathematical constant representing the circumference ratio, and t is a time variable.

[0077] In some embodiments, based on the target current signal of the power battery and the current collection signals of the two capacitor connection phases, the control signal of the switching device connected by the capacitor connection phase is determined, including: based on the difference between the target current signal and the sum of the two current collection signals, a proportional integral calculation is performed to obtain a target duty cycle signal; the switching device in the three-phase inverter connected by the battery connection phase is controlled to be turned off, and the control signal of the switching device in the three-phase inverter connected by the capacitor connection phase is determined according to the target duty cycle signal.

[0078] Wherein, the proportional integral calculation refers to adjusting the difference between the target current signal and the sum of the two current collection signals through the combination of the proportional element and the integral element, which can be realized by a proportional integral controller PID, and the target duty cycle signal can be generated by pulse width modulation technology, which is used to determine the control signal of the switching device in the three-phase inverter connected by the capacitor connection phase, and then the on-off time ratio of the switching device is modulated through the control signal to adjust the phase current of the capacitor connection phase.

[0079] It can be understood that when the difference between the target current signal and the sum of the two current collection signals is converted into the target duty cycle signal through the proportional integral calculation, the switching device in the three-phase inverter connected by the battery connection phase needs to be turned off to avoid interference with the loop formation, and then the control signal can be generated according to the target duty cycle signal, and the switching frequency of the switching device in the three-phase inverter connected by the capacitor connection phase is adjusted based on the control signal, so as to control the phase current of the capacitor connection phase.

[0080] In some embodiments, before controlling the charging and discharging loop to form the charging and discharging current to heat the power battery, it further includes: adjusting the rotor angle of the three-phase motor to a preset angle to make the phase currents of the two capacitor connection phases the same.

[0081] Wherein, the preset angle is 120 degrees, and the angle is set based on the spatial distribution characteristics of the three-phase motor winding: when the rotor angle is positioned at 120 degrees, the coupling degree of the inductance winding of the two capacitor connection phases (such as U phase and W phase) and the rotor magnetic field is consistent, and the equivalent impedance is the same. In this state, when the symmetric control signal is applied through the three-phase inverter, the two capacitor connection phases can form phase currents with equal size and adaptive direction.

[0082] It can be understood that the motor has no torque output, and when the motor is stationary, the energy is only transmitted between the battery and the capacitor. Therefore, when the V-phase terminal of the three-phase motor is connected to the positive pole of the power battery as the battery connection phase, the current of the charging and discharging circuit is equal to the charging and discharging current of the battery. At the same time, the 120-degree pre-positioning can balance the forces generated by the currents of the two capacitor connection phases in the magnetic field, ensuring that the output torque of the three-phase motor is zero, avoiding the rotation of the motor during the heating process, thereby ensuring that the energy is only transmitted between the power battery and the capacitor, and avoiding energy loss caused by the rotation of the motor. This pre-positioning step lays the foundation for subsequent control of the symmetry of the charging and discharging current through the three-phase inverter, ensures stable current waveform during charging and discharging, and improves heating efficiency and control accuracy.

[0083] It is worth noting that when the V-phase terminal of the three-phase motor is connected to the positive pole of the power battery as the battery connection phase, the current of the charging and discharging circuit is equal to the charging and discharging current of the battery, and the energy is only transmitted between the battery and the capacitor.

[0084] Reference Figure 7 , Figure 7 In the power battery heating control method provided by the embodiments of the present application, the electrical connection diagram in the power mode; as Figure 7 The present application further provides that a third relay is further arranged between the power battery and the capacitor, and the method further comprises: controlling the third relay to be opened when the first relay is closed and the second relay is opened; and controlling the third relay to be closed when the first relay is opened and the second relay is closed, so that the power battery and the capacitor form a power supply circuit.

[0085] In some embodiments, a pre-charging circuit is further arranged between the power battery and the capacitor, the pre-charging circuit comprises a fourth relay and a pre-charging resistor connected in series, and the method further comprises: controlling the fourth relay to be opened when the first relay is closed and the second relay is opened; and controlling the fourth relay to be closed when the first relay is opened and the second relay is closed, so that the power battery, the pre-charging resistor and the capacitor form a pre-charging circuit.

[0086] In some embodiments, a pre-charging circuit is further arranged between the power battery and the capacitor, the pre-charging circuit comprises a fourth relay and a pre-charging resistor connected in series, and the method further comprises: controlling the fourth relay to be opened when the first relay is closed and the second relay is opened; and controlling the fourth relay to be closed when the first relay is opened and the second relay is closed, so that the power battery, the pre-charging resistor and the capacitor form a pre-charging circuit.

[0087] The pre-charging circuit refers to a current limiting path formed by the fourth relay and a pre-charging resistor in series, can be realized by combining an electromagnetic relay and a carbon film resistor, and is used for limiting the capacitor charging current when the system starts; the power supply circuit refers to a low-impedance path formed by directly connecting the third relay, can be realized by a high-power contactor, and is used for providing a low-loss current path when the system is stably running; the power mode refers to a state in which the vehicle is running or energy is being output, at this time, the alternating current heating system needs to adjust the circuit topology structure according to the driving demand, and the cooperative control of the third relay and the fourth relay can realize the current grading management of the capacitor charging process.

[0088] It can be understood that when the application is in the heating mode and the power battery is heated, the power mode can be entered to enable the power battery to normally run, 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, the pre-charging resistor limits the initial charging current of the capacitor, and the inrush current impact on the three-phase inverter is avoided, and then when the capacitor voltage reaches a preset threshold, the third relay is closed to bypass the pre-charging circuit, the on-state loss is reduced, and the alternating current heating system can dynamically adjust the switching time of the fourth relay and the third relay according to the real-time power output demand, for example, the pre-charging circuit working time is prolonged in the low power demand, and the power supply circuit is quickly switched to in the high power demand, so as to effectively suppress the impact of current mutation on the circuit elements and improve the circuit reliability.

[0089] Reference Figure 8 , Figure 8 The heating control method of the power battery provided in the embodiment of the application is shown in the example flowchart of the heating mode. Figure 8 As shown in the figure, the application can be in a low temperature condition, the whole vehicle is in a neutral gear, and after the three-phase motor reaches a predetermined position of 120 degrees of rotor angle, it is switched to a pulse heating mode; further, in the pulse heating, the application can run the target current signal control process as shown in Figure 6 , that is, first, the power battery charges the capacitor through Boost voltage rise, at this time, the current is the positive current of the sine current, and the capacitor charges the power battery through control logic Buck voltage drop, at this time, the current is the negative current of the sine current, so that the power battery and the capacitor perform alternating charging and discharging through the charging and discharging circuit, and then the power battery is heated without additional independent heating circuit, thereby reducing the heating cost.

[0090] Reference Figure 9 , Figure 9 The schematic block diagram of the alternating current heating system of the power battery provided in the embodiment of the application is shown in the figure. Figure 9As shown, the application further provides a heating control device 900, the device is applied to an alternating current heating system, the system includes a power battery, a capacitor, an inductive winding of a three-phase motor and a three-phase inverter, any one phase inductive winding of the three-phase motor is 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; wherein the device includes: a channel control module 901 configured to control the first relay to be closed and the second relay to be opened, so as to form a charging and discharging circuit, and the charging and discharging circuit includes the inductive winding of the three-phase motor, the three-phase inverter, the power battery and the capacitor; and a current control module 902 configured to control the charging and discharging circuit to form a charging and discharging current, so as to heat the power battery.

[0091] The alternating current heating system refers to a circuit structure composed of a power battery, a capacitor and a charging and discharging circuit, and can be realized by connecting the power battery with one phase inductive winding of a three-phase motor as a battery connection phase and connecting the capacitor with the remaining two phase inductive windings as capacitor connection phases through a three-phase inverter, and energy flows bidirectionally through the three-phase motor and the three-phase inverter. The three-phase inverter refers to a circuit unit for converting alternating current into direct current, and can be realized by a three-phase full-bridge rectifier circuit or a bridge arm circuit composed of multiple insulated gate bipolar transistors, and the charging and discharging current of the charging and discharging circuit is controlled by controlling the on-off state of the switching devices in the three-phase inverter. The current control module 902 refers to a processor for executing a heating control algorithm, and can be realized by a microcontroller or a digital signal processor.

[0092] In some embodiments, the other two phase inductive windings of the three-phase motor except the battery connection phase are used as capacitor connection phases, and the capacitor connection phases are connected with the capacitor through the three-phase inverter. When the charging and discharging current of the charging and discharging circuit is controlled, the current control module 902 is further configured to control the on-off state of the switching devices in the three-phase inverter connected with the capacitor connection phases, so that the inductive windings of the three-phase inverter store and release energy periodically, so as to increase or decrease the voltage of the capacitor, so that the charging and discharging circuit alternately forms charging current and discharging current, and the directions of the charging current and the discharging current flowing through the power battery are opposite.

[0093] In some embodiments, when the on-off state of the switching devices in the three-phase inverter connected with the capacitor connection phases is controlled, the current control module 902 is further configured to obtain a target current signal of the power battery; determine a control signal of the switching devices connected with the capacitor connection phases based on the target current signal of the power battery and current collection signals of the two capacitor connection phases; and control the on-off state of the switching devices connected with the capacitor connection phases based on the control signal.

[0094] In some embodiments, when determining the control signal of the switching device connected by the capacitor connection phase based on the target current signal of the power battery and the current collection signals of the two capacitor connection phases, the current control module 902 is further configured to: perform proportional integral calculation based on the difference between the target current signal and the sum of the two current collection signals to obtain a target duty cycle signal; control the switching device in the three-phase inverter connected by the battery connection phase to be turned off, and determine the control signal of the switching device in the three-phase inverter connected by the capacitor connection phase according to the target duty cycle signal.

[0095] In some embodiments, when obtaining the target current signal of the power battery, the current control module 902 is further configured to: determine the charge-discharge amplitude and the charge-discharge frequency when the battery connection phase performs sinusoidal alternating charge-discharge based on the pulse heating requirement of the power battery; and determine the target current signal of the power battery according to the charge-discharge amplitude and the charge-discharge frequency.

[0096] In some embodiments, the switching device in the three-phase inverter connected by the capacitor connection phase includes an upper bridge arm switch and a lower bridge arm switch, the upper bridge arm switch is connected to the positive electrode of the power battery, and the lower bridge arm switch is connected to the negative electrode of the power battery, and when controlling the on-off state of the switching device connected by the capacitor connection phase based on the control signal, the current control module 902 is further configured to: based on the control signal, control the upper bridge arm switch connected by the capacitor connection phase to switch from the off state to the closed state, and the lower bridge arm switch connected by the capacitor connection phase to switch from the closed state to the off state, so that the charge-discharge circuit forms a charging current as a boost circuit; based on the control signal, control the upper bridge arm switch connected by the capacitor connection phase to switch from the closed state to the off state, and the lower bridge arm switch connected by the capacitor connection phase to switch from the off state to the closed state, so that the charge-discharge circuit forms a discharging current as a buck circuit.

[0097] In some embodiments, before controlling the charge-discharge circuit to form the charge-discharge current to heat the power battery, the current control module 902 is further configured to: adjust the rotor angle of the three-phase motor to a preset angle so that the phase currents of the two capacitor connection phases are the same.

[0098] In some embodiments, a third relay is further arranged between the power battery and the capacitor, and the path control module 901 is further configured to: control the third relay to be turned off when the first relay is turned on and the second relay is turned off; and control the third relay to be turned on when the first relay is turned off and the second relay is turned on, so that the power battery and the capacitor form a power supply circuit.

[0099] In some embodiments, a pre-charging circuit is further arranged between the power battery and the capacitor, the pre-charging circuit comprising a fourth relay and a pre-charging resistor connected in series, and the path control module 901 is further configured to: control the fourth relay to be open when the first relay is closed and the second relay is open; and control the fourth relay to be closed when the first relay is open and the second relay is closed, so that the power battery, the pre-charging resistor and the capacitor form a pre-charging loop.

[0100] The application further provides a vehicle, which can comprise: an alternating current heating system, the system comprising a power battery, a capacitor, an inductive winding of a three-phase motor and a three-phase inverter, any one phase inductive winding of the three-phase motor being a battery connection phase, the battery connection phase being connected to the power battery through a first relay, and a second relay being arranged between the battery connection phase and the three-phase inverter; and a controller configured to execute the steps of the method of the first aspect, so as to achieve the effect of heating the power battery without additional independent heating circuit, thereby reducing the heating cost.

[0101] In several embodiments provided in the application, it should be understood that the disclosed system, device and method can be implemented by other manners. For example, the device embodiments described above are only schematic, for example, the division of units is only a logical function division, and actual implementation can have another division manner, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units shown or discussed can be indirect coupling or communication connection through some interfaces, devices or units, and can be electrical, mechanical or other forms.

[0102] The units described as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, that is, they can be located in one place, or can be distributed on a plurality of network units. According to actual needs, part or all of the units can be selected to achieve the purpose of the embodiment.

[0103] In addition, each functional unit in each embodiment of the application can be integrated in one processing unit, or each unit can be physically present separately, or two or more units can be integrated in one unit.

[0104] In the above embodiments, all or part of the embodiments can be implemented by software, hardware, firmware or any combination thereof. When implemented by software, all or part of the embodiments can be implemented in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions according to the embodiments of the present application are generated. The computer can be a general purpose computer, a special purpose computer, a computer network, or other programmable apparatus. The computer instructions can be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another computer readable storage medium, for example, the computer instructions can be transmitted from one website, computer, server or data center to another website, computer, server or data center through wired (for example, coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (for example, infrared, wireless, microwave, etc.) manner. The computer readable storage medium can be any available medium readable by a computer or a data storage device such as a server, data center, etc. integrated with one or more available media. The available media can be a magnetic medium (for example, floppy disk, hard disk, magnetic tape), an optical medium (for example, digital video disc (DVD)) or a semiconductor medium (for example, solid state disk (SSD)) and the like.

[0105] The above describes the technical solutions provided by the present application in detail, and the principles and implementation manners of the present application are described by applying specific examples. The above examples are only used to help understand the method and core idea of the present application; at the same time, for those skilled in the art, according to the idea of the present application, the specific implementation manner and application range will be changed. In summary, the content of the specification should not be understood as a limitation of the present application.

Claims

1. A method of heating control of a power battery, characterized in that, The method is applied to an alternating current heating system, the system comprising a power battery, a capacitor, an inductive winding of a three-phase motor and a three-phase inverter, any one phase inductive winding of the three-phase motor being a battery connection phase, the battery connection phase being connected with the power battery through a first relay, a second relay being arranged between the battery connection phase and the three-phase inverter; The method comprises: controlling the first relay to be closed and the second relay to be opened, so that the connection between the battery connection phase and the three-phase inverter is cut off, forming a charging and discharging circuit, the charging and discharging circuit comprising the inductive winding of the three-phase motor, the three-phase inverter, the power battery and the capacitor; controlling the charging and discharging circuit to form a charging and discharging current, so as to heat the power battery; The other two phase inductive windings of the three-phase motor except the battery connection phase are capacitor connection phases, and the capacitor connection phases are connected with the capacitor through the three-phase inverter.

2. The method of claim 1, wherein, The other two phase inductive windings of the three-phase motor except the battery connection phase are capacitor connection phases, and the capacitor connection phases are connected with the capacitor through the three-phase inverter, and the control of the charging and discharging circuit to form a charging and discharging current comprises: controlling the on-off state of the switching device in the three-phase inverter connected with the capacitor connection phase, so as to increase or decrease the voltage of the capacitor, so that the charging and discharging circuit alternately forms a charging current and a discharging current, the directions of the charging current and the discharging current flowing through the power battery are opposite.

3. The method of claim 2, wherein, The control of the on-off state of the switching device in the three-phase inverter connected with the capacitor connection phase comprises: obtaining a target current signal of the power battery; determining a control signal of the switching device connected with the capacitor connection phase based on the target current signal of the power battery and current collection signals of the two capacitor connection phases; controlling the on-off state of the switching device connected with the capacitor connection phase based on the control signal.

4. The method of claim 3, wherein, The determination of the control signal of the switching device connected with the capacitor connection phase based on the target current signal of the power battery and the current collection signals of the two capacitor connection phases comprises: performing proportional integral calculation based on the difference between the target current signal and the sum of the two current collection signals to obtain a target duty cycle signal; controlling the switching device in the three-phase inverter connected with the battery connection phase to be opened, and determining the control signal of the switching device in the three-phase inverter connected with the capacitor connection phase according to the target duty cycle signal.

5. The method of claim 3, wherein, The obtaining of the target current signal of the power battery comprises: determining a charging and discharging amplitude and a charging and discharging frequency when the battery connection phase performs sinusoidal alternating current charging and discharging based on the pulse heating requirement of the power battery; determining the target current signal of the power battery according to the charging and discharging amplitude and the charging and discharging frequency.

6. The method of claim 2, wherein, Before controlling the charging and discharging circuit to form a charging and discharging current, the method further comprises: adjusting the rotor angle of the three-phase motor to a preset angle, so that the phase currents of the two capacitor connection phases are the same.

7. The method according to any one of claims 1 to 6, characterized in that, A third relay is further arranged between the power battery and the capacitor, and the method further comprises: controlling the third relay to be open when the first relay is closed and the second relay is open; controlling the third relay to be closed when the first relay is open and the second relay is closed, so that the power battery and the capacitor form a power supply loop.

8. The method according to any one of claims 1 to 6, characterized in that, A pre-charging circuit is further arranged between the power battery and the capacitor, the pre-charging circuit comprising a fourth relay and a pre-charging resistor connected in series, and the method further comprises: controlling the fourth relay to be open when the first relay is closed and the second relay is open; controlling the fourth relay to be closed when the first relay is open and the second relay is closed, so that the power battery, the pre-charging resistor and the capacitor form a pre-charging loop.

9. A heating control device, characterized by The device is applied to an alternating current heating system, the system comprising a power battery, a capacitor, an inductive winding of a three-phase motor and a three-phase inverter, any one phase inductive winding of the three-phase motor serving as a battery connection phase, the battery connection phase being connected with the power battery through a first relay, and a second relay being arranged between the battery connection phase and the three-phase inverter; The device comprises: a path control module configured to control the first relay to be closed and the second relay to be open, so that the connection between the battery connection phase and the three-phase inverter is cut off, forming a charge-discharge loop, the charge-discharge loop comprising the inductive winding of the three-phase motor, the three-phase inverter, the power battery and the capacitor; a current control module configured to control the charge-discharge loop to form a charge-discharge current to heat the power battery; wherein the other two phase inductive windings of the three-phase motor except the battery connection phase serve as capacitor connection phases, and the capacitor connection phases are connected with the capacitor through the three-phase inverter.

10. A vehicle characterized by comprising: The device comprises: an alternating current heating system, the system comprising a power battery, a capacitor, an inductive winding of a three-phase motor and a three-phase inverter, any one phase inductive winding of the three-phase motor serving as a battery connection phase, the battery connection phase being connected with the power battery through a first relay, and a second relay being arranged between the battery connection phase and the three-phase inverter; a controller configured to execute the steps of the method of any one of claims 1 to 8.

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