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;Based on the rotor angle of three-phase motor, 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 for a power battery and a vehicle. BACKGROUND

[0002] In a low temperature environment, the power battery of an existing electric vehicle generally has problems such as charging difficulty, reduced discharging efficiency and cycle life attenuation, so the power battery needs to be heated before it works. 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 costs. SUMMARY

[0003] The present application provides a heating control method and device for 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 for 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:

[0007] controlling the first relay to be closed and the second relay to be opened, thereby forming 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 based on a rotor angle of the three-phase motor, thereby heating 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 respectively a capacitor connection phase, each capacitor connection phase is connected to the capacitor through the three-phase inverter, and the controlling the charging and discharging circuit to form a charging and discharging current based on a rotor angle of the three-phase motor includes:

[0010] Control on / off states of switching devices in the three-phase inverter connected with the capacitor connection phase based on a rotor angle of the three-phase motor, to control the charging and discharging circuit to alternately form charging current and discharging current, the charging current and the discharging current flow through the power battery in opposite directions.

[0011] As an optional way, the control on / off states of the switching devices in the three-phase inverter connected with the capacitor connection phase based on the rotor angle of the three-phase motor comprises:

[0012] Obtain a target direct-axis current of the three-phase motor;

[0013] Determine a target current signal of the capacitor connection phase based on the target direct-axis current and the rotor angle;

[0014] Determine a control signal of the switching device connected with the capacitor connection phase based on the target current signal of the capacitor connection phase and a current acquisition signal of the capacitor connection phase;

[0015] Control on / off states of the switching device connected with the capacitor connection phase based on the control signal.

[0016] As an optional way, the obtaining of the target direct-axis current of the three-phase motor comprises:

[0017] Determine a charging and discharging amplitude and a charging and discharging frequency when the battery connection phase performs sinusoidal alternating charging and discharging based on a pulse heating requirement of the power battery;

[0018] Determine the target direct-axis current of the three-phase motor according to the charging and discharging amplitude and the charging and discharging frequency.

[0019] As an optional way, the determination of the target current signal of the capacitor connection phase based on the target direct-axis current and the rotor angle comprises:

[0020] Obtain a current in a stationary coordinate system through Park inverse transformation based on the target direct-axis current and the rotor angle;

[0021] Obtain the target current signal of the capacitor connection phase through Clark inverse transformation based on the current in the stationary coordinate system.

[0022] As an optional way, the determination of the control signal of the switching device connected with the capacitor connection phase based on the target current signal of the capacitor connection phase and the current acquisition signal of the capacitor connection phase comprises:

[0023] Perform proportional integral calculation based on a difference between the target current signal of the capacitor connection phase and the current acquisition signal, to obtain a target duty cycle signal;

[0024] controlling switching devices in the three-phase inverter connected with the capacitor connection phase to be off, and determining control signals of switching devices in the three-phase inverter connected with the capacitor connection phase according to the target duty cycle signal.

[0025] As an optional mode, before controlling the on-off state of the switching devices in the three-phase inverter connected with the capacitor connection phase based on the rotor angle of the three-phase motor, the method further comprises:

[0026] controlling the quadrature axis current of the three-phase motor to be zero, and adjusting the rotor angle of the three-phase motor to a preset angle range, wherein the angle range is determined based on the pulse heating requirement of the power battery.

[0027] As an optional mode, the power battery and the capacitor are further provided with a pre-charging circuit and a main positive circuit connected in parallel with the pre-charging circuit, the pre-charging circuit comprises a pre-charging relay and a pre-charging resistor, and the main positive circuit comprises a main positive relay, and after controlling the current on the charging and discharging circuit based on the rotor angle of the three-phase motor, the method further comprises:

[0028] controlling the first relay to be off, the second relay to be on, and controlling the on-off state of the pre-charging relay and the main positive relay according to the output power requirement of the power battery.

[0029] According to a second aspect, a heating control device is provided, which 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 on and the second relay to be off to form 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;

[0032] a current control module configured to control the charging and discharging circuit to form a charging and discharging current based on the rotor angle of the three-phase motor to heat the power battery.

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

[0034] An alternating current heating 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 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.

[0035] A controller is configured to execute the steps of the method of the first aspect.

[0036] The scheme provided by the embodiment of the present application is based on the original 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 is a battery connection phase, a first relay connecting the battery connection phase and the power battery is newly added, and a second relay arranged between the battery connection phase and the three-phase inverter is newly added, so that when the first relay is closed and the second relay is opened, the three-phase motor and the three-phase inverter can form a charging and discharging circuit, the charging and discharging circuit comprises the inductive winding of the three-phase motor, the three-phase inverter, the power battery and the capacitor, and then the charging and discharging circuit can form a charging and discharging current by combining the rotor angle of the three-phase motor, 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 present 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 flow repeatedly between the power battery and the capacitor, and based on the charging and discharging current formed on the charging and discharging circuit controlled by the rotor angle of the three-phase motor, the current controllability can be improved, so that the power battery and the capacitor can alternately charge and discharge more accurately and effectively, and then the power battery itself can be heated by using the internal resistance of the power battery to achieve the purpose of heating the power battery. Compared with the traditional scheme relying on PTC heater and other external heating elements, the present application does not need to make structural changes to the three-phase motor, nor does it need to additionally add an independent heating circuit, so the heating effect can be effectively improved and the heating cost can be reduced.

[0037] Of course, any product implementing the present 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 present application or the prior art, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description only constitute some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0039] Figure 1 A circuit architecture diagram applicable to the embodiments of the present application.

[0040] Figure 2A flow chart of the heating control method of the power battery provided in the embodiments of the present application.

[0041] Figure 3 In the heating control method of the power battery provided in the embodiments of the present application, an electrical connection diagram in the heating mode.

[0042] Figure 4 In the heating control method of the power battery provided in the embodiments of the present application, a current flow direction diagram of discharging of the power battery.

[0043] Figure 5 In the heating control method of the power battery provided in the embodiments of the present application, a current flow direction diagram of charging of the power battery.

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

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

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

[0047] Figure 9 A 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 described clearly and completely 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 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 only 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 only to describe the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B 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 to mean "when" or "while" or "in response to determining" or "in response to detecting." Similarly, the phrase "if it is determined" or "if [a stated condition or event] is detected" can be interpreted to mean "upon determining" or "in response to determining" or "upon detecting [the stated condition or event]" or "in response to detecting [the stated condition or event]."

[0052] In the prior art, in a low-temperature environment, the existing power battery of an electric vehicle generally has problems such as charging difficulty, reduced discharging efficiency, and cycle life attenuation, so it is necessary to heat the power battery before the power battery works, and 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 costs.

[0053] To solve the above problems, the present application finds that using existing electrical components of a vehicle for energy conversion can avoid the addition of external heating elements, so by analyzing the energy interaction characteristics between the three-phase motor and the power battery and the capacitor, the inductance winding in the three-phase motor is proposed as part of the charging and discharging circuit, and heat is generated by the charging and discharging process of alternating current, thereby achieving heating of the power battery.

[0054] Therefore, the present application provides a heating control method and device for a power battery and a vehicle, which can heat the power battery without additional independent heating circuits, thereby reducing the heating cost.

[0055] Reference Figure 1 , Figure 1 A circuit architecture diagram suitable for the embodiments of the present application; as Figure 1As shown, the circuit architecture is used for the control scene related to the power battery, and is used to implement the heating control method of the power battery in the present application; wherein the power battery provides power for the entire circuit, K1 is a main positive relay, K2 is a pre-charge relay, K2 is connected with a pre-charge resistor R1 in series, and is used to control the on-off and pre-charge of the circuit; K3 and K4 are respectively a first relay and a second relay, and are used to ensure that the charging and discharging loop is turned on in the heating mode; C1 is a capacitor, which can be a motor controller film capacitor, and can participate in the charging and discharging process; S1 to S6 are switching devices in the three-phase inverter, which can be IGBT switching tubes, and are used to form a three-phase inverter bridge in the three-phase inverter, and are connected with inductance windings L1, L2 and L3 in the three-phase motor; any one phase of the inductance windings L1, L2 and L3 in the three-phase motor can be used as a battery connection phase, and is connected with the power battery through the first relay, and can be used as a capacitor connection phase, and is connected with the capacitor through the second relay; A1 and A2 are current collection elements, and are used to obtain current collection signals of the capacitor connection phase; based on the above circuit architecture, the present application can control the charging and discharging loop to form a charging and discharging current, so as to heat the power battery, for example, in the heating mode, the first relay is controlled to be closed, the second relay is controlled to be opened, the charging and discharging current is formed, the joule heat is generated in the power battery to complete the heating, and in the power mode, the first relay is controlled to be opened, and the second relay is controlled to be closed, so as to meet the power output demand of the vehicle.

[0056] Reference Figure 2 , Figure 2 The flow chart of the heating control method of the power battery provided by the embodiment of the present application; reference Figure 2 The present application provides a heating control method of a power battery, the method is applied to an alternating current heating system, the alternating current heating system includes a power battery, a capacitor, inductance windings of a three-phase motor and a three-phase inverter, any one phase of the inductance windings 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; the control method can at least include the following steps:

[0057] Step 201, control the first relay to be closed and the second relay to be opened, form a charging and discharging loop, and the charging and discharging loop includes the inductance windings of the three-phase motor, the three-phase inverter, the power battery and the capacitor;

[0058] Step 202, control the charging and discharging loop to form a charging and discharging current based on the rotor angle of the three-phase motor, so as to heat the power battery.

[0059] Wherein, the three-phase motor refers to a motor with three inductance windings, reference Figure 3 , Figure 3 The electrical connection diagram in the heating mode in the heating control method of the power battery provided by the embodiment of the present application; as Figure 3The U-phase and W-phase inductor windings can be connected to the capacitor through the three-phase inverter as the capacitor connection phase.

[0060] It can be understood that the three-phase inverter is used to perform current inversion to form a charging and discharging current as an alternating current, and the rotor angle refers to real-time position information of a motor rotor, which can be obtained through a sensor or an observer.

[0061] It is worth noting that the first relay is arranged between the capacitor connection phase and the power battery, and the second relay is arranged between the capacitor connection phase and the three-phase inverter, so that the first relay can be closed and the second relay can be opened in the heating mode, as shown in Figure 1 The first relay and the second relay are relays K3 and K4 used to control the on-off of the charging and discharging circuit, the first relay K3 is arranged between the battery connection phase and the positive electrode of the power battery, and the second relay K4 is arranged between the capacitor connection phase and the three-phase inverter, the three-phase inverter is connected in parallel with the capacitor, the positive electrode of the capacitor is connected to the positive electrode of the power battery through a pre-charging circuit and a main positive circuit connected in parallel with the pre-charging circuit, and the negative electrode is connected to the negative electrode of the power battery, the pre-charging circuit includes a pre-charging relay K2 and a pre-charging resistor R1, and the main positive circuit includes a main positive relay K1; wherein the relays K1 to K4 can be realized by electromagnetic relays or solid-state relays to establish a current path between the power battery and the capacitor.

[0062] As shown in Figure 3As shown, the application is based on the original system including the power battery, the capacitor, the inductive winding of the three-phase motor and the three-phase inverter. The inductive winding of any phase of the three-phase motor is used as the battery connection phase. The first relay connecting the battery connection phase and the power battery is added. The second relay is added between the battery connection phase and the three-phase inverter. When the first relay is closed and the second relay is opened, 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 be controlled by the rotor angle of the three-phase motor to form a charging and discharging current. 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. The alternating current can flow between the power battery and the capacitor. The charging and discharging current formed on the charging and discharging circuit based on the rotor angle of the three-phase motor can improve the controllability of the current. The power battery and the capacitor can alternately charge and discharge more accurately and effectively. The power battery itself can be used to generate heat to heat the power battery. Compared with the traditional scheme relying on the external heating element such as the 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. The heating effect can be improved and the heating cost can be reduced.

[0063] In some embodiments, the other two-phase inductive windings of the three-phase motor except the battery connection phase are respectively used as the capacitor connection phase. Each capacitor connection phase is connected with the capacitor through the three-phase inverter. The charging and discharging circuit is controlled by the rotor angle of the three-phase motor to form a charging and discharging current. The control method includes: based on the rotor angle of the three-phase motor, the on-off state of the switching device in the three-phase inverter connected with the capacitor connection phase is controlled to control the charging and discharging circuit to alternately form the charging current and the discharging current. The directions of the charging current and the discharging current flowing through the power battery are opposite.

[0064] The above process can realize the energy storage and release management of the inductive winding of the three-phase motor by adjusting the on-off state of the switching device to control the charging and discharging circuit to alternately form the charging current and the discharging current. It can be understood that when the discharging current is needed, the inductive winding of the capacitor connection phase is set to enter the energy storage state by the target duty ratio corresponding to the on-off control signal. The magnetic field energy stored in the inductor is used to transfer energy to the capacitor after being regulated by the three-phase inverter. At this time, the current flows out of the power battery to form a boost circuit. When the charging current is needed, the inductive winding is adjusted to enter the energy release state by the target duty ratio corresponding to the on-off control signal. The released energy and the electric energy stored in the capacitor are jointly transmitted to the power battery in the reverse direction through the three-phase inverter to form a buck circuit.

[0065] Reference Figure 4 and 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 present 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 present application: it can be understood that in the heating control scenario of the present application, the Boost circuit is reflected in the process of the power battery discharging to the capacitor. As shown in Figure 4 , in 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), controls the on-off state of the switching device in the three-phase inverter connected to the capacitor connection phase, and makes the inductance (L1, L3) of the three-phase motor enter 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 by 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 the capacitor charging to the power battery. As shown in Figure 5 , in 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, and 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 jointly charge the power battery, and realize the energy recovery of the reverse current.

[0067] It is worth noting that since the rotor angle changes the magnetic coupling state of the inductance windings of each phase of the three-phase motor, and further affects the equivalent impedance and current carrying capacity of the inductance windings of different capacitor connection phases, for example, the change of the rotor angle may cause the inductance value of a capacitor connection phase to increase and the inductance value of another phase to decrease, thereby changing the energy storage / release efficiency of the two. Therefore, in the charging and discharging current switching process, the on-off control of the switching device needs to be performed according to the rotor angle, and the on-off rhythm of the switching device of different capacitor connection phases needs to be adjusted to ensure that the inductance windings can still maintain the stable switching of the direction of the charging current and the discharging current, and further form a periodic alternating sinusoidal current, and generate continuous Joule heat through the energy conversion inside the power battery to realize heating.

[0068] Reference Figure 6 , Figure 6 The control block diagram of the target current signal in the heating control method of the power battery provided by the embodiment of the present application; as shown in Figure 6As shown, in some embodiments, based on the rotor angle of the three-phase motor, the on-off state of the switching device connected to the capacitor connection phase in the three-phase inverter is controlled, including: obtaining a target direct-axis current of the three-phase motor; based on the target direct-axis current and the rotor angle, determining a target current signal of the capacitor connection phase; based on the target current signal of the capacitor connection phase and the current acquisition signal of the capacitor connection phase, determining the control signal of the switching device connected to the capacitor connection phase; based on the control signal, controlling the on-off state of the switching device connected to the capacitor connection phase.

[0069] Wherein, the target direct-axis current refers to the reference current component used to generate the magnetic field in motor control, which can be determined by adjusting the quadrature-axis current to zero and combining the pulse heating demand, the target current signal refers to the phase current set value that the capacitor connection phase needs to reach, and the current acquisition signal refers to the actual current measurement value of the capacitor connection phase, which is used to feedback the actual current state, and the deviation between the phase target current signal and the current acquisition signal is compared for adjustment, and then the on-off state of the switching device in the three-phase inverter can be adjusted to form the charging and discharging current.

[0070] It can be understood that the control signal of the switching device connected to the capacitor connection phase refers to an electrical signal used to regulate the on-off state of the power switching device connected to the capacitor connection phase in the three-phase inverter, which functions to adjust the direction, size and change rate of the current of the capacitor connection phase by controlling the on-off rhythm of the switching device, so as to complete the heating process by cooperating with the charging and discharging process of the power battery and the capacitor.

[0071] 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 switching 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 switching device to turn on with a high duty ratio, so that the inductor winding of the capacitor connection phase enters the energy storage state; then the control signal turns to low level, the switching device is turned off, the inductor releases energy and is superimposed with the battery voltage to form a current flowing to the capacitor higher than the battery voltage, completing the discharging, and at this time, the duty ratio 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 switching device to turn on with a low duty ratio, and the current released by the capacitor flows through the inductor and stores part of the energy; after the switching 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, completing the charging, and at this time, the duty ratio of the control signal determines the step-down amplitude.

[0072] In some embodiments, the target direct-axis current of the three-phase motor is obtained, including: based on the pulse heating demand of the power battery, determining the charging and discharging amplitude and the charging and discharging frequency when the battery connection phase performs sinusoidal alternating current charging and discharging; determining the target direct-axis current of the three-phase motor according to the charging and discharging amplitude and the charging and discharging frequency.

[0073] 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 charge-discharge amplitude can correspond to the peak value of the sinusoidal alternating current, the size of which is positively correlated with the heating power, the charge-discharge frequency can match the resonance characteristics of the inductance winding and the capacitance of the three-phase motor, and is selected within a preset range to avoid high-frequency switching loss or excessive current ripple at low frequency.

[0074] It can be understood that after the charge-discharge amplitude and the charge-discharge frequency are determined, the value of the target direct-axis current can be derived through inverse operation of coordinate transformation. Since the direct-axis current needs to be equivalent to the sinusoidal current of the battery connection phase after Park inverse transformation and Clark inverse transformation, the amplitude of the target direct-axis current has a fixed proportional relationship with the charge-discharge amplitude, and the charge-discharge frequency can be matched by controlling the dynamic change rate of the direct-axis current.

[0075] In some embodiments, based on the target direct-axis current and the rotor angle, the target current signal of the capacitance connection phase is determined, including: based on the target direct-axis current and the rotor angle, the current in the stationary coordinate system is obtained through Park inverse transformation; based on the current in the stationary coordinate system, the target current signal of the capacitance connection phase is obtained through Clark inverse transformation.

[0076] Wherein, the Park inverse transformation refers to converting the current in the rotating coordinate system into the current in the stationary coordinate system, which can be realized by using a coordinate transformation matrix, and is used to combine the target direct-axis current and the rotor angle to generate the current component in the stationary coordinate system. The Clark inverse transformation refers to converting the current in the stationary coordinate system into the phase current, which can be realized by using a three-to-two coordinate transformation matrix, and is used to decompose the stationary coordinate system current into the current target value of the two capacitance connection phases, thereby realizing the control of the phase current.

[0077] It can be understood that after the target direct-axis current and the rotor angle are determined, the direct-axis current is converted into the current component in the stationary coordinate system through the coordinate transformation algorithm, and then the current target value of the two capacitance connection phases is obtained. The deviation between the target value and the actual value of the actual current signal of the capacitance connection phase is input into the proportional integral controller, and the target duty cycle signal for controlling the on-off of the switching devices in the three-phase inverter is calculated. By adjusting the switching frequency and duty cycle of the switching devices in the three-phase inverter, the alternating charge and discharge between the power battery and the capacitor is realized.

[0078] It is worth noting that the Park inverse transformation is to convert the target direct-axis current in the rotating coordinate system (d-q axis) into the two-phase current in the stationary coordinate system (α-β axis) , ), the transformation matrix of which can contain the sine and cosine functions of the rotor angle θ, which associates the direct-axis current with the spatial magnetic field direction of the motor winding through the rotor angle, ensuring that the current vector is always consistent with the magnetic field direction. The subsequent Clark inverse transformation converts the static coordinate system into the phase current in the three-phase coordinate system. Since one phase in the three-phase motor has been connected as the battery connection phase, only the target current values of the other two phases (the capacitor connection phases) need to be calculated. For example, when the battery connection phase is the V phase, the target current signals of the U and W phases can be obtained through transformation, and both satisfy Iu+Iw=-Iv (Iv is the current of the battery connection phase), thereby complying with Kirchhoff's current law. Furthermore, through the above two-stage coordinate transformation, the abstract direct-axis current instruction can be converted into the target current signal of the capacitor connection phase, which can be directly controlled, providing specific basis for subsequent current closed-loop control. 、

[0079] In some embodiments, based on the target current signal of the capacitor connection phase and the current acquisition signal of the capacitor connection phase, the control signal of the switching device connected to the capacitor connection phase is determined, including: based on the difference between the target current signal of the capacitor connection phase and the current acquisition signal, proportional integral calculation is performed to obtain a target duty cycle signal; the switching device in the three-phase inverter connected to the battery connection phase is controlled to be turned off, and the control signal of the switching device in the three-phase inverter connected to the capacitor connection phase is determined according to the target duty cycle signal.

[0080] Among them, the proportional integral calculation refers to the adjustment of the error signal through the combination of the proportional link and the integral link, which can be realized by a proportional integral controller. 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 to 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.

[0081] It can be understood that when the current difference is converted into the target duty cycle signal through proportional integral calculation, the switching device in the three-phase inverter connected to the battery connection phase needs to be turned off to avoid interference with the loop, 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 to the capacitor connection phase is adjusted based on the control signal, so as to control the phase current of the capacitor connection phase.

[0082] In some embodiments, before controlling the on-off state of the switching device in the three-phase inverter connected to the capacitor connection phase based on the rotor angle of the three-phase motor, it further includes: controlling the quadrature-axis current of the three-phase motor to be zero, and adjusting the rotor angle of the three-phase motor to be within a preset angle range, wherein the angle range is determined based on the pulse heating demand of the power battery.

[0083] ​In the process of controlling the three-phase motor, the quadrature-axis current component is set to zero, which can be achieved by adjusting the current closed-loop control parameters of the motor controller, thereby simplifying the current control logic and focusing on the regulation of the direct-axis current.

[0084] It can be understood that when the V-phase terminal of the three-phase motor is connected to the positive electrode of the power battery as the battery connection phase, the current of the charging and discharging circuit is equal to the battery charging and discharging current, and during the charging and discharging process, the motor needs to be stationary, i.e. the motor has no torque output. When the motor is stationary, energy is only transmitted between the battery and the capacitor, and the torque output by the motor is mainly determined by the quadrature-axis current of the Q-axis. Therefore, to ensure that the quadrature-axis current is zero, only the direct-axis current of the D-axis needs to be controlled.

[0085] In some embodiments, corresponding Figure 6 Park / Clark inverse transformation, the specific process of determining the target direct-axis current of the three-phase motor can be as follows:

[0086] According to the formula (1) of Park inverse transformation and the formula (2) of Clark inverse transformation, the relationship between the V-phase current as the battery connection phase and the target direct-axis current and the rotor angle is as follows: When the relationship is as shown in formula 3 and formula 4:

[0087]

[0088]

[0089]

[0090]

[0091] wherein, is the cosine, is the sine, , , are the phase currents of the motor three-phase inductance windings, , are the currents in the stationary two-phase coordinate system, , are the quadrature and direct-axis currents in the rotating coordinate system, is the rotor angle, "°" is the degree symbol, is the radical symbol, is the matrix symbol;

[0092] According to the above formulas 1 to 4, it can be deduced that to control the V-phase sinusoidal alternating charging and discharging as the battery connection phase, the target direct-axis current is as shown in formula 5:

[0093]

[0094] in, For AC charging and discharging amplitude, The frequency of AC charging and discharging is π, which is a mathematical constant representing the mathematical constant pi, and t is a time variable.

[0095] Furthermore, such as Figure 6 As shown, the control process for phase current control in this application can be as follows:

[0096] First, calculate the target direct-axis current using Formula 5. and obtain the rotor angle Then, the target values ​​of the U and W phase currents can be calculated using the Park inverse transform and Clark inverse transform according to formulas 1 to 4, and then... Figure 1 Current sensors A1 and A2 acquire the current acquisition signals of phases U and W. Further, a dual-PID current loop controller can calculate the target duty cycle of the corresponding IGBT switches for U and W, and then update the target duty cycle of the two phases to the control unit to control the circuit. Figure 1 The switching on and off of S1, S3, S4, and S6 is controlled, and the upper and lower bridges of phase V are kept in the off state. That is, S2 and S4 are in the off state throughout the process, so as to ensure that the charging and discharging circuit is open in the heating mode and realize the repeated flow of current between the power battery and the capacitor.

[0097] This application further proposes that, before obtaining the rotor angle of the three-phase motor, if the rotor angle of the three-phase motor is not within a preset angle range, the rotor angle of the three-phase motor shall be adjusted to the angle range, wherein the angle range is determined based on the pulse heating requirements of the three-phase motor.

[0098] Among these, "rotor angle not within the preset angle range" means that the actual mechanical position of the three-phase motor rotor deviates from the preset range. Specifically, an angle sensor or encoder can be used to detect the rotor angle, and the detected value is compared with the preset range boundary value to determine if it is within the range. "Adjusting to the angle range" means changing the rotor's mechanical position by controlling the three-phase motor's drive signal. Specifically, a closed-loop control algorithm can be used to generate the drive signal, causing the rotor to rotate to the target angle range. "Angle range determined based on pulse heating requirements" means dynamically setting the angle range based on the power battery's heating power requirements, the capacitor's charging and discharging capacity, and the three-phase motor's electrical parameters. Specifically, a lookup table method or real-time calculation method can be used to determine the optimal angle range; for example, to ensure that the absolute value of the V-phase current, which is the battery connection phase, is maximized, when... θWhen ∈[90°, 150°] and [270°, 330°], θ-30° ∈[60°, 120°] and [240°, 300°], and sin(θ-30°) takes a value in [sin60°, sin90°] close to the peak value, so the range of θ can be [90°, 150°] and [270°, 330°].

[0099] Reference Figure 7 , Figure 7 In the heating control method of the power battery provided in the embodiment of the present application, the electrical connection diagram in the power mode is as shown in Figure 7 The present application further provides that a pre-charging circuit and a main positive circuit parallel to the pre-charging circuit are further arranged between the power battery and the capacitor, the pre-charging circuit comprises a pre-charging relay and a pre-charging resistor, the main positive circuit comprises a main positive relay, after the current on the charging and discharging circuit is controlled based on the rotor angle of the three-phase motor, the method further comprises: controlling the first relay to be disconnected, the second relay to be closed, and controlling the on-off state of the pre-charging relay and the main positive relay according to the output power demand of the power battery.

[0100] The pre-charging circuit refers to a current limiting path formed by the pre-charging relay and the pre-charging resistor in series, which 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 main positive circuit refers to a low impedance path formed by the main positive relay directly connected, which 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 the state that the vehicle is in driving or energy 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 pre-charging relay and the main positive relay can realize the current grading management of the capacitor charging process.

[0101] It can be understood that when the power battery is heated in the heating mode, the power battery can enter the power mode 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, and the pre-charging resistor limits the initial charging current of the capacitor to avoid the inrush current from impacting the three-phase inverter, and then when the capacitor voltage reaches a preset threshold, the main positive relay is closed to bypass the pre-charging circuit to reduce the on-off loss, so that the alternating current heating system can dynamically adjust the switching time of the pre-charging relay and the main positive relay according to the real-time output power demand, for example, the pre-charging circuit working time is prolonged when the power demand is low, and the main positive circuit is quickly switched when the power demand is high, so as to effectively suppress the impact of current mutation on the circuit elements and improve the circuit reliability.

[0102] Reference Figure 8 , Figure 8 In the heating control method of the power battery provided in the embodiment of the present application, the example flow chart of the heating mode is as shown inFigure 8 As shown, the application can be in the case of low temperature, whole vehicle starting pulse heating; further, the motor controller of the whole vehicle can be used as a heating control device to determine whether the rotor angle of the three-phase motor is within the preset range, if not, the rotor angle of the three-phase motor is controlled to enter the preset range, if yes, it is switched to heating mode, the motor controller can have torque mode, speed mode, pulse heating mode, etc., in pulse heating, the motor controller switches the pulse heating mode, and runs as Figure 6 The target current signal control process, that is, by first Boosting to charge the capacitor with the power battery, the current is the positive current of the sine current at this time, and by controlling the logic Buck to charge the power battery with the capacitor, the current is the negative current of the sine current at this time, so that the power battery and the capacitor are charged and discharged through the charging and discharging circuit, thereby heating the power battery without additional independent heating circuit, thereby reducing the heating cost.

[0103] Reference Figure 9 , Figure 9 The schematic block diagram of the heating control device of the power battery provided by the embodiment of the application is shown in the figure Figure 9 As shown, the application further provides a heating control device 900, 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 as a battery connection phase, the battery connection phase 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 path control module 901 configured to control the first relay to close and the second relay to open, forming 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; a current control module 902 configured to control the charging and discharging circuit to form a charging and discharging current based on the rotor angle of the three-phase motor to heat the power battery.

[0104] Wherein, the alternating current heating system refers to a circuit structure composed of a power battery, a capacitor and a charging and discharging circuit, which 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 realizing bidirectional energy flow 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, which can be realized by a three-phase full-bridge 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, which can be realized by a microcontroller or a digital signal processor.

[0105] In some embodiments, the two-phase inductance windings other than the battery connection phase in the three-phase motor are respectively connected to the capacitor connection phase, each capacitor connection phase is connected to the capacitor through the three-phase inverter, and when the charging and discharging circuit is formed to form a charging current and a discharging current based on the rotor angle of the three-phase motor, the current control module 902 is further configured to: based on the rotor angle of the three-phase motor, control the on-off state of the switching device in the three-phase inverter connected to the capacitor connection phase, to control the charging and discharging circuit to alternately form the charging current and the discharging current, the directions of the charging current and the discharging current flowing through the power battery are opposite.

[0106] In some embodiments, when the on-off state of the switching device in the three-phase inverter connected to the capacitor connection phase is controlled based on the rotor angle of the three-phase motor, the current control module 902 is further configured to: obtain a target direct-axis current of the three-phase motor; based on the target direct-axis current and the rotor angle, determine a target current signal of the capacitor connection phase; based on the target current signal of the capacitor connection phase and the current acquisition signal of the capacitor connection phase, determine the control signal of the switching device connected to the capacitor connection phase; and based on the control signal, control the on-off state of the switching device connected to the capacitor connection phase.

[0107] In some embodiments, when the target direct-axis current of the three-phase motor is obtained, the current control module 902 is further configured to: based on the pulse heating requirement of the power battery, determine the charging and discharging amplitude and the charging and discharging frequency when the battery connection phase is subjected to sinusoidal alternating charging and discharging; and determine the target direct-axis current of the three-phase motor according to the charging and discharging amplitude and the charging and discharging frequency.

[0108] In some embodiments, when the target current signal of the capacitor connection phase is determined based on the target direct-axis current and the rotor angle, the current control module 902 is further configured to: based on the target direct-axis current and the rotor angle, obtain the current in the stationary coordinate system through Park inverse transformation; and based on the current in the stationary coordinate system, obtain the target current signal of the capacitor connection phase through Clark inverse transformation.

[0109] In some embodiments, when the control signal of the switching device connected to the capacitor connection phase is determined based on the target current signal of the capacitor connection phase and the current acquisition signal of the capacitor connection phase, the current control module 902 is further configured to: based on the difference between the target current signal of the capacitor connection phase and the current acquisition signal, perform proportional integral calculation to obtain a target duty cycle signal; control the switching device in the three-phase inverter connected to the battery connection phase to be disconnected, and determine the control signal of the switching device in the three-phase inverter connected to the capacitor connection phase according to the target duty cycle signal.

[0110] In some embodiments, before controlling the on-off state of the switching device in the three-phase inverter to which the capacitor connection phase is connected based on the rotor angle of the three-phase motor, the current control module 902 is further configured to: control the quadrature axis current of the three-phase motor to be zero, and adjust the rotor angle of the three-phase motor to a preset angle range, wherein the angle range is determined based on the pulse heating requirement of the power battery.

[0111] In some embodiments, a pre-charging circuit and a main positive circuit in parallel with the pre-charging circuit are further arranged between the power battery and the capacitor, the pre-charging circuit includes a pre-charging relay and a pre-charging resistor, and the main positive circuit includes a main positive relay, after controlling the current on the charge-discharge circuit based on the rotor angle of the three-phase motor, the path control module 901 is further configured to: control the first relay to be open, the second relay to be closed, and control the on-off state of the pre-charging relay and the main positive relay according to the output power requirement of the power battery.

[0112] The application further provides a vehicle, which can include: 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 with 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 have the effect of the first aspect and any one of the embodiments of the second aspect, that is, to heat the power battery without additional independent heating circuit, thereby reducing the heating cost, and thus the description is omitted here.

[0113] In the several embodiments provided by the present application, it should be understood that the disclosed system, apparatus, and method can be implemented in other manners. For example, the division of the apparatus embodiment is only a logical function division, and there can be another division manner for the actual implementation, for example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections between different units, can be indirect couplings or communication connections through some interfaces, devices, or units, and can be electrical, mechanical, or in other forms.

[0114] The units described as separate components can or can not be physically separate, and the components displayed as units can or can not be physical units, that is, can be located in one place, or can be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purposes of the embodiments.

[0115] In addition, each functional unit in each embodiment of the present application can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit.

[0116] 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 devices. 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. containing one or more available media. The available medium 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.

[0117] The above describes the technical solutions provided by the present application in detail, and the principles and implementation modes 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 mode and application range will be changed. In conclusion, 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 based on a rotor angle of the three-phase motor, so as to heat the power battery; the other two phase inductive windings of the three-phase motor except the battery connection phase are respectively capacitor connection phases, and each capacitor connection phase is 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 respectively capacitor connection phases, and each capacitor connection phase is connected with the capacitor through the three-phase inverter, and the controlling the charging and discharging circuit to form a charging and discharging current based on a rotor angle of the three-phase motor comprises: controlling the on-off state of a switching device in the three-phase inverter connected with the capacitor connection phase based on the rotor angle of the three-phase motor, so as to control the charging and discharging circuit to alternately form a charging current and a discharging current, the charging current and the discharging current flowing through the power battery in opposite directions.

3. The method of claim 2, wherein, The controlling the on-off state of a switching device in the three-phase inverter connected with the capacitor connection phase based on the rotor angle of the three-phase motor comprises: obtaining a target direct-axis current of the three-phase motor; determining a target current signal of the capacitor connection phase based on the target direct-axis current and the rotor angle; determining a control signal of the switching device connected with the capacitor connection phase based on the target current signal of the capacitor connection phase and a current acquisition signal of the capacitor connection phase; 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 obtaining a target direct-axis current of the three-phase motor comprises: determining a charging and discharging amplitude and a charging and discharging frequency when the battery connection phase performs sinusoidal alternating charging and discharging based on a pulse heating requirement of the power battery; determining the target direct-axis current of the three-phase motor according to the charging and discharging amplitude and the charging and discharging frequency.

5. The method of claim 3, wherein, The determining a target current signal of the capacitor connection phase based on the target direct-axis current and the rotor angle comprises: obtaining a current in a stationary coordinate system through Park inverse transformation based on the target direct-axis current and the rotor angle; obtaining the target current signal of the capacitor connection phase through Clark inverse transformation based on the current in the stationary coordinate system.

6. The method of claim 2, wherein, Before the controlling the on-off state of a switching device in the three-phase inverter connected with the capacitor connection phase based on the rotor angle of the three-phase motor, the method further comprises: Control the quadrature axis current of the three-phase motor to be zero, and adjust the rotor angle of the three-phase motor to be within a preset angle range, wherein the angle range is determined based on the pulse heating requirement of the power battery.

7. The method according to any one of claims 1 to 6, characterized in that, 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 main positive loop.

8. The method according to any one of claims 1 to 6, characterized in that, The power battery and the capacitor are further provided with a pre-charging circuit, and 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 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, and the system comprises 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 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. 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, and a charging and discharging loop is formed, the charging and discharging 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 charging and discharging loop to form a charging and discharging current based on the rotor angle of the three-phase motor, so as to heat the power battery; The other two phase inductive windings of the three-phase motor except the battery connection phase are respectively used as capacitor connection phases, and each capacitor connection phase is 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 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; a controller configured to execute the steps of the method according to any one of claims 1 to 8.

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