Power battery heating control method, electric vehicle and medium

Abstract

The present application discloses a power battery heating control method, an electric vehicle and a medium, the method comprising: when an external power supply is connected to a power battery heating system, obtaining the charge and discharge power and heating power of the power battery; obtaining the expected current of the three-phase winding according to the charge and discharge power and the heating power; based on the expected current of the second-phase winding and the third-phase winding in the expected current of the three-phase winding, and the sampled current of the second-phase winding and the third-phase winding, controlling the current in the second-phase winding and the third-phase winding in the three-phase motor, and realizing the effect of power battery charge and discharge current control by using an external power supply and a circuit structure reused during boost charging without leading out the neutral point of the three-phase motor winding, solving the problem of the power battery being unable to self-heat when the power battery is exhausted or the power is low, thereby improving the heating efficiency of the power battery.

Description

Technical Field

[0001] The present invention relates to the field of motor control, and in particular to a power battery heating control method, an electric vehicle, and a computer-readable storage medium. Background Art

[0002] When electric vehicles are exposed to low temperatures, the discharge efficiency of the power battery decreases, reducing the vehicle's range. High-current charging can cause lithium deposition in the power battery, irreversibly damaging it and reducing battery safety. Therefore, in low-temperature environments, the power battery is first heated. A common method involves charging and discharging the battery with the motor windings. In addition to the heat generated by the battery's internal resistance, the motor also generates heat, which is then transferred to the battery via a thermal management system. This improves battery heating efficiency, and thus discharge efficiency.

[0003] However, when the power battery is exhausted or extremely low in power, the above method not only fails to solve the problem of low endurance of electric vehicles, but also further reduces the power consumption and safety of the power battery, reducing the user's car experience. Summary of the Invention

[0004] The main purpose of the present invention is to provide a power battery heating control method, an electric vehicle and a computer-readable storage medium, aiming to solve the technical problem that common battery heating solutions not only cannot solve the problem of low endurance of electric vehicles, but also further reduce the power consumption and safety of power batteries.

[0005] To achieve the above objectives, in a first aspect, a power battery heating control method is provided, which is used in a power battery heating system. The power battery heating system includes a three-phase inverter and a three-phase motor. A connecting line between a first phase winding of the three-phase motor and a first phase bridge arm of the three-phase inverter is led out, and the led-out connecting line is used to connect to an external power supply. The power battery heating method includes the following steps:

[0006] When the external power supply is connected to the power battery heating system, the charging and discharging power and heating power of the power battery are obtained;

[0007] According to the charging and discharging power and the heating power, the desired current of the three-phase winding is obtained;

[0008] Based on the desired currents of the second and third phase windings among the desired currents of the three-phase windings and the sampled currents of the second and third phase windings, the currents in the second and third phase windings of the three-phase motor are controlled.

[0009] Optionally, the step of obtaining the desired current of the three-phase winding according to the charging and discharging power and the heating power includes:

[0010] Obtaining a desired current of a first phase winding among the desired currents of the three-phase windings according to the charge and discharge power;

[0011] Obtaining a desired DC component of the power battery according to a desired current of the first phase winding, a bus voltage, and an external power supply voltage;

[0012] Obtaining a desired AC component of the power battery based on the heating power and the desired DC component of the power battery;

[0013] Obtaining the expected AC component of the bus current according to the expected AC component of the power battery;

[0014] Based on the expected AC component of the bus current and the expected current of the first phase winding, the expected currents of the second phase winding and the third phase winding are obtained.

[0015] Optionally, the step of controlling the currents in the second-phase winding and the third-phase winding in the three-phase motor based on the expected currents of the second-phase winding and the third-phase winding in the expected currents of the three-phase winding and the sampled currents of the second-phase winding and the third-phase winding includes:

[0016] comparing the desired current and the sampled current of the second-phase winding, determining a first duty cycle adjustment value of the power switch element of the second phase in the three-phase inverter based on the comparison result of the desired current and the sampled current of the second-phase winding, and controlling the power switch element of the second phase in the three-phase inverter based on the first duty cycle adjustment value to control the current of the second-phase winding in the three-phase motor;

[0017] Compare the expected current and the sampled current of the third group of windings, determine a second duty cycle adjustment amount of the power switching element of the third phase in the three-phase inverter based on the comparison result of the expected current and the sampled current of the third group of windings, and control the power switching element of the third phase in the three-phase inverter based on the second duty cycle adjustment amount to control the current of the third phase winding in the three-phase motor.

[0018] Optionally, before the step of controlling the currents in the second-phase winding and the third-phase winding in the three-phase motor based on the expected currents of the second-phase winding and the third-phase winding in the expected currents of the three-phase winding and the sampled currents of the second-phase winding and the third-phase winding, the step further includes:

[0019] A first duty cycle feedforward value of the fourth power switch element and a second duty cycle feedforward value of the fifth power switch element in the three-phase inverter are obtained according to the bus voltage and the external power supply voltage.

[0020] Optionally, the step of controlling the currents in the second-phase winding and the third-phase winding in the three-phase motor based on the expected currents of the second-phase winding and the third-phase winding in the expected currents of the three-phase winding and the sampled currents of the second-phase winding and the third-phase winding includes:

[0021] comparing the desired current and the sampled current of the second-phase winding, determining a first duty cycle adjustment base value for the second-phase power switch element in the three-phase inverter based on the comparison result of the desired current and the sampled current of the second-phase winding, and controlling the second-phase power switch element in the three-phase inverter based on the first duty cycle adjustment base value and the first duty cycle feedforward value to control the current of the second-phase winding in the three-phase motor;

[0022] Compare the expected current and the sampled current of the third-phase winding, determine the second duty cycle adjustment base value of the power switching element of the third phase in the three-phase inverter based on the comparison result of the expected current and the sampled current of the third-phase winding, and control the power switching element of the third phase in the three-phase inverter based on the second duty cycle adjustment base value and the second duty cycle feedforward value to control the current of the third-phase winding in the three-phase motor.

[0023] In addition, to achieve the above-mentioned purpose, the present invention also provides an electric vehicle, which includes a power battery heating system, a memory, and a processor. The memory is used to store one or more instructions, and the above-mentioned instructions are executed at least by the processor. The processor is used to implement the power battery heating control method described in the first aspect above.

[0024] In addition, to achieve the above-mentioned purpose, the present invention further provides a computer-readable storage medium, on which is stored an executable program for implementing the power battery control method as described in the first aspect above.

[0025] The present application connects an external power supply to the power battery heating system of an electric vehicle, connects the external power supply to one-phase winding of a three-phase motor in the power battery heating system, and controls the power switching elements of the three-phase inverter through a multiplexed boost circuit structure (i.e., a boost circuit and a buck circuit) formed by connecting the other two-phase windings in parallel, without the need to lead out the neutral point of the three-phase motor winding. This not only solves the high requirements of existing battery heating solutions on power batteries, allowing the power battery to achieve self-heating even when the power is exhausted or extremely low, but also enables bidirectional power flow between the external power supply and the power battery. That is, while improving the battery heating efficiency through the external power supply, it can also realize the charging and discharging of the power battery itself, making it convenient to charge the electric vehicle, reducing the charging time to a certain extent, and improving the user experience of the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the terminal structure of the hardware operating environment involved in the embodiment of the present application;

[0027] Figure 2A schematic diagram of the circuit structure of a power battery heating system provided in an embodiment of the present application;

[0028] Figure 3 A schematic flow chart of a power battery heating control method provided in an embodiment of the present application;

[0029] Figure 4 for Figure 3 Detailed flow chart of step S30;

[0030] Figure 5 This is a waveform diagram in battery heating mode;

[0031] Figure 6 This is a waveform diagram of the battery heating + low current charging mode;

[0032] Figure 7 A schematic diagram of the principle of controlling a three-phase inverter based on the desired current of the V-phase winding and the desired current of the W-phase winding provided in an embodiment of the present application;

[0033] Figure 8 A schematic diagram of another principle of controlling a three-phase inverter based on the desired current of the V-phase winding and the desired current of the W-phase winding provided in an embodiment of the present application.

[0034] Description of Figure Numbers:

[0035] Label name Label name 10 Three-phase inverter D2, D4, D6 Lower bridge diode 20 Three-phase motor <![CDATA[U bat ]]> Power Battery K1 Switching elements C1 First capacitor Lu-Lw Winding C2 Second capacitor Q1-Q6 Power switching elements <![CDATA[U DC ]]> External power supply S1, S3, S5 Upper arm control signal N Neutral point D1, D3, D5 Upper bridge diode PI1-PI2 PI controller S2, S4, S6 Lower arm control signal PWM1-PWM2 PWM controller

[0036] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0037] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0038] Currently, one method for self-heating power batteries is based on the remaining power of the power battery. When the power battery is exhausted or the power is extremely low, self-heating of the power battery cannot be achieved. Another method of using an external power supply for battery self-heating requires that the neutral point of the three-phase motor winding be brought out, but the neutral point of the motor of most electric vehicles is not brought out.

[0039] The main solution provided by the embodiment of the present application is: by utilizing an external power supply to heat the power battery, and by leading out a switching element through one phase winding of the three-phase motor to connect it to the external power supply, a circuit structure control is formed during multiplexing boost charging. This not only solves the high requirements of the existing battery heating solution on the power battery, so that the power battery can achieve improved heating efficiency even when the power is exhausted or extremely low, but also realizes the bidirectional flow of power between the external power supply and the power battery.

[0040] like Figure 1 As shown, Figure 1 It is a schematic diagram of the terminal structure of the hardware operating environment involved in the embodiment of the present application.

[0041] like Figure 1 As shown, the electric vehicle may include: a processor 1001, such as a CPU, a network interface 1004, a user interface 1003, a memory 1005, and a communication bus 1002. The communication bus 1002 is used to realize the connection and communication between these components. The user interface 1003 may include a display screen (Display), an input unit such as a keyboard (Keyboard), and the user interface 1003 may also include a standard wired interface and a wireless interface. The network interface 1004 may optionally include a standard wired interface and a wireless interface (such as a WI-FI interface). The memory 1005 may be a high-speed RAM memory or a stable memory (non-volatile memory), such as a disk memory. The memory 1005 may also be a storage device independent of the aforementioned processor 1001.

[0042] Optionally, the electric vehicle may also include a camera, RF (Radio Frequency) circuit, sensor, audio circuit, WiFi module, etc. Among them, sensors include light sensors, motion sensors and other sensors. Specifically, the light sensor may include an ambient light sensor and a proximity sensor, wherein the ambient light sensor can adjust the brightness of the display screen according to the brightness of the ambient light, and the proximity sensor can turn off the display screen and / or backlight when the mobile terminal is moved to the ear. As a type of motion sensor, the gravity acceleration sensor can detect the magnitude of acceleration in all directions (generally three axes), and can detect the magnitude and direction of gravity when stationary. It can be used for applications that identify the posture of the mobile terminal (such as horizontal and vertical screen switching, related games, magnetometer posture calibration), vibration recognition related functions (such as pedometer, tapping), etc.; of course, the mobile terminal can also be equipped with other sensors such as gyroscopes, barometers, hygrometers, thermometers, infrared sensors, etc., which will not be repeated here.

[0043] Those skilled in the art will understand that Figure 1 The electric vehicle structure shown in the figure does not constitute a limitation to the electric vehicle, and may include more or fewer components than shown in the figure, or combine certain components, or arrange the components differently.

[0044] like Figure 1 As shown, the memory 1005 as a computer storage medium may include an operating system, a network communication module, a user interface module and a computer program.

[0045] exist Figure 1In the terminal shown, the network interface 1004 is mainly used to connect to the backend server and communicate data with the backend server; the user interface 1003 is mainly used to connect to the client (user end) and communicate data with the client; and the processor 1001 can be used to call the computer program stored in the memory 1005 and perform the following steps:

[0046] When the external power supply is connected to the power battery heating system, the charging and discharging power and heating power of the power battery are obtained;

[0047] According to the charging and discharging power and the heating power, the desired current of the three-phase winding is obtained;

[0048] Based on the desired currents of the second and third phase windings among the desired currents of the three-phase windings and the sampled currents of the second and third phase windings, the currents in the second and third phase windings of the three-phase motor are controlled.

[0049] Furthermore, the processor 1001 may call a computer program stored in the memory 1005 and further perform the following steps:

[0050] The step of obtaining the expected current of the three-phase winding according to the charge and discharge power includes: obtaining the expected current of the first phase winding among the expected currents of the three-phase winding according to the charge and discharge power;

[0051] Obtaining a desired DC component of the power battery according to a desired current of the first phase winding, a bus voltage, and an external power supply voltage;

[0052] Obtaining a desired AC component of the power battery based on the heating power and the desired DC component of the power battery;

[0053] Obtaining the expected AC component of the bus current according to the expected AC component of the power battery;

[0054] Based on the expected AC component of the bus current and the expected current of the first phase winding, the expected currents of the second phase winding and the third phase winding are obtained.

[0055] Furthermore, the processor 1001 may call a computer program stored in the memory 1005 and further perform the following steps:

[0056] The step of controlling the currents in the second-phase winding and the third-phase winding of the three-phase motor based on the expected currents of the second-phase winding and the third-phase winding in the expected currents of the three-phase winding and the sampled currents of the second-phase winding and the third-phase winding includes comparing the expected current of the second-phase winding with the sampled current, determining a first duty cycle adjustment amount of a power switching element of a second phase in the three-phase inverter based on the comparison result of the expected current of the second-phase winding and the sampled current, and controlling the power switching element of the second phase in the three-phase inverter based on the first duty cycle adjustment amount to control the current of the second-phase winding of the three-phase motor;

[0057] Compare the expected current and the sampled current of the third group of windings, determine a second duty cycle adjustment amount of the power switching element of the third phase in the three-phase inverter based on the comparison result of the expected current and the sampled current of the third group of windings, and control the power switching element of the third phase in the three-phase inverter based on the second duty cycle adjustment amount to control the current of the third phase winding in the three-phase motor.

[0058] Furthermore, the processor 1001 may call a computer program stored in the memory 1005 and perform the following operations:

[0059] Before the step of controlling the current in the second phase winding and the third phase winding in the three-phase motor based on the expected current of the second phase winding and the third phase winding in the expected current of the three-phase winding, and the sampled current of the second phase winding and the third phase winding: obtain a first duty cycle feedforward value of the fourth power switching element and a second duty cycle feedforward value of the fifth power switching element in the three-phase inverter according to the bus voltage and the external power supply voltage.

[0060] Furthermore, the processor 1001 may call a computer program stored in the memory 1005 and perform the following operations:

[0061] The step of controlling the currents in the second-phase winding and the third-phase winding of the three-phase motor based on the expected currents of the second-phase winding and the third-phase winding in the expected currents of the three-phase winding and the sampled currents of the second-phase winding and the third-phase winding includes: comparing the expected current of the second-phase winding with the sampled current, determining a first duty cycle adjustment base value of a power switch element of a second phase in the three-phase inverter based on the comparison result of the expected current of the second-phase winding and the sampled current, and controlling the power switch element of the second phase in the three-phase inverter based on the first duty cycle adjustment base value and the first duty cycle feedforward value to control the current of the second-phase winding of the three-phase motor;

[0062] Compare the expected current and the sampled current of the third-phase winding, determine the second duty cycle adjustment base value of the power switching element of the third phase in the three-phase inverter based on the comparison result of the expected current and the sampled current of the third-phase winding, and control the power switching element of the third phase in the three-phase inverter based on the second duty cycle adjustment base value and the second duty cycle feedforward value to control the current of the third-phase winding in the three-phase motor.

[0063] Reference Figure 2 , an embodiment of the present application provides a power battery heating system, the system comprising:

[0064] A three-phase inverter 10; a three-phase motor 20, wherein the first phase winding of the three-phase motor 20 is connected to the first phase bridge arm of the three-phase inverter 10, the second phase winding of the three-phase motor 20 is connected to the second phase bridge arm of the three-phase inverter 10, and the third phase winding of the three-phase motor 20 is connected to the third phase bridge arm of the three-phase inverter 10.

[0065] A connection line between the first phase winding of the three-phase motor 20 and the first phase bridge arm of the three-phase inverter 10 is led out, and the led-out connection line is used to connect to an external power supply.

[0066] Optionally, a switch element K1 is provided to control the connection between the external power supply and the power battery heating system. Figure 2 As shown, one end of the switch element K1 is connected to the connection line between the first phase winding of the three-phase motor 20 and the first phase bridge arm of the three-phase inverter 10, and the other end of the switch element K1 is used to connect to the external power supply U DC When the car is connected to a charging station or other external power source, the switch element K1 is closed.

[0067] In the embodiment of the present application, taking the first phase winding of the three-phase motor 20 as the U phase winding Lu, the second phase winding as the V phase winding Lv, and the third phase winding as the W phase winding Lw as an example, when the electric vehicle is connected to the charging pile, the switch element K1 is closed, and the output terminal of the U phase winding Lu of the three-phase motor 20 is connected to the external power supply U DC The positive pole of the power supply, external power supply U DC The negative pole of the power supply is connected to the power battery U via the negative port of the three-phase inverter 10 bat The negative electrode, such as Figure 2 shown.

[0068] It should be noted that, in actual applications, the first phase winding can also be a V-phase winding, the second phase winding and the third phase winding are a W-phase winding and a U-phase winding, or the first phase winding is a W-phase winding, the second phase winding and the third phase winding are a U-phase winding and a V-phase winding. In this embodiment, the first phase is U-phase, the second phase is V-phase, and the third phase is W-phase.

[0069] In addition, the above connection method can also be to connect the output end of the V-phase winding Lv of the three-phase motor 20 to the external power supply U DC The positive pole of the power supply controls the current in the U-phase winding Lu of the three-phase motor 20 and the W-phase winding Lw of the three-phase motor 20, or the output end of the W-phase winding Lw of the three-phase motor 20 is connected to the external power supply U DC The positive pole of the power supply controls the current in the U-phase winding Lu and the V-phase winding Lv of the three-phase motor 20.

[0070] When the external power supply is connected Figure 2 In the power battery heating system shown, by connecting one phase of the three-phase winding to an external power source and controlling the current of the other two phases of the three-phase winding, the self-heating effect of the power battery is controlled. At the same time, bidirectional power flow between the external power source and the power battery can be achieved to achieve the effect of charging or discharging the battery.

[0071] Furthermore, the three-phase inverter 10 includes a first power switching element Q1 , a second power switching element Q2 , a third power switching element Q3 , a fourth power switching element Q4 , a fifth power switching element Q5 and a sixth power switching element Q6 ;

[0072] The first ends of the first power switching element Q1, the third power switching element Q3 and the fifth power switching element Q5 are connected together to form the positive port of the three-phase inverter 10, and the second ends of the second power switching element Q2, the fourth power switching element and the sixth power switching element Q6 are connected together to form the negative port of the three-phase inverter 10. If the power switching element is a transistor as an example, the first end refers to the collector and the second end refers to the emitter.

[0073] The third power switch element Q3, the fourth power switch element Q4 and the second phase winding Lv of the three-phase motor 20 form a boost circuit; the fifth power switch element Q5, the sixth power switch element Q6 and the third phase winding Lw of the three-phase motor 20 form a buck circuit, and the boost circuit and the buck circuit are connected in parallel to form a circuit topology for multiplexing winding boost charging. Through this circuit topology, the heating efficiency and charging and discharging efficiency of the power battery can be improved by using an external power supply without increasing any hardware costs.

[0074] Furthermore, the power battery heating system also includes a power battery U bat , a first capacitor C1 and a second capacitor C2;

[0075] Power Battery U bat The positive electrode is connected to the positive port of the three-phase inverter 10, and the power battery U bat The negative electrode of the three-phase inverter 10 is connected to the negative port, the first capacitor C1 is connected in parallel with the power battery and the three-phase inverter 10, and the second capacitor C2 is connected in parallel with the external power supply U DCIt is connected in parallel with the three-phase motor 20 .

[0076] Among them, the first capacitor C1 is a bus capacitor, which can bat The bus current is filtered and output to the power battery U bat The battery current acts on the internal resistance of the power battery to generate heat loss to the power battery U bat Heating to improve the power battery U bat The discharge efficiency is high, and the second capacitor C2 is a step-down capacitor that plays the role of energy storage and voltage smoothing.

[0077] Figure 2 The direction of the arrow in the middle indicates the positive direction of the current. The three-phase currents of the three-phase motor 20 have the following relationship:

[0078] i u =-(i v +i w )

[0079] Among them, i u It represents the current flowing through the first power switch element, the second power switch element and the first phase winding, and also represents the net outflow current of the external power supply, reflecting the average charging current of the power battery. Because there is internal resistance inside the battery, when the power battery temperature is too low, the internal resistance will increase. If a large current is charged at this time, it will accelerate the degradation of the power battery. Therefore, when charging, i u It should be kept at a smaller value to reduce the consumption of the power battery. v Represents the current flowing through the boost circuit, i w Indicates the current flowing through the step-down circuit.

[0080] From the above formula representing the relationship between the three-phase currents, it can be seen that the current directions of the V-phase and W-phase windings are always opposite, and the amplitudes are close. When battery heating is required, the current amplitudes of the V-phase winding and the W-phase winding, as well as the switching frequency, are controlled so that the charge and discharge currents of the power battery meet the power requirements of battery heating. In addition, the battery can also be charged or discharged.

[0081] exist Figure 2 In the power battery heating system shown, the current of each phase winding and the corresponding working mode are shown in Table 1 below (taking the average current of phase V less than zero as an example):

[0082] Table 1

[0083] Working mode / current <![CDATA[i u ]]> <![CDATA[i v ]]> <![CDATA[i w ]]> Battery heating 0 <![CDATA[-|I peak |]]> <![CDATA[|I peak |]]> Battery heating + low current charging <![CDATA[|I dc |]]> <![CDATA[-|I peak |]]> <![CDATA[|I peak |-|I dc |]]> Battery heating + battery discharge <![CDATA[-|I dc |]]> <![CDATA[-|I peak |]]> <![CDATA[|I peak |+|I dc |]]>

[0084] In the above Table 1, I dc is the U-phase current, which is the current output from the external power supply to the power battery heating system; I peakIndicates the peak current of phase V. The working mode in the table is for one control cycle, for example:

[0085] 1. "Battery heating" mode means that after connecting to an external power source, the battery is only heated within one control cycle without charging or discharging the battery; i u The current value is 0. Substituting 0 into the above three-phase current formula, we can see that i v The current value is -|I peak |, corresponding to i w The current value is |I peak |;

[0086] 2. Mode "Battery heating + low current charging" means that after connecting to an external power supply, the battery heating must be controlled and the battery must be charged within one control cycle. At this time, there is |I dc |, still |I dc |Substitute into the above three-phase current formula, we can see that at this time i v The current value is -|I peak |,i w The current value is |I peak |-|I dc |;

[0087] 3. The "Battery Heating + Battery Discharging" mode means that after connecting to an external power source, the battery heating and battery discharge are controlled within one control cycle. For example, when an electric vehicle needs to feed power to the grid, battery heating and battery discharge are achieved simultaneously.

[0088] In this embodiment, by connecting the first-phase winding of the three-phase motor to an external power supply, the second-phase winding of the three-phase motor and the current in the second-phase winding of the three-phase motor are controlled, thereby avoiding the problem of limited remaining power of the power battery and achieving the effect of controlling the heating efficiency and charging and discharging efficiency of the power battery without increasing any hardware cost.

[0089] Further, refer to Figure 3 , an embodiment of the present application provides a power battery heating control method, which is applied to Figure 2 The power battery heating system shown in the figure. It should be noted in advance that one end of the switch element is set on the connection line between the U-phase winding of the three-phase motor and the U-phase bridge arm of the three-phase inverter, and the other end of the switch element is connected to the external power supply. v <0,i w >0 as an example, the V-phase winding of the three-phase motor and the third and fourth power switching elements form a boost circuit, and the W-phase winding of the three-phase motor and the fifth and sixth power switching elements form a buck circuit. The power battery heating control method includes the following steps:

[0090] Step S10, when the external power supply is connected to the power battery heating system, obtaining the charging and discharging power and heating power of the power battery;

[0091] Optionally, when the power battery heating system is connected to an external power supply, the entire vehicle generates charge and discharge power instructions and heating power instructions for the power battery. The charge and discharge power instructions include the charge and discharge power of the power battery, and the heating power instructions include the heating power of the power battery. The charge and discharge power of the power battery is obtained according to the charge and discharge power instructions, and the heating power of the power battery is obtained according to the heating instructions.

[0092] Step S20, obtaining the desired current of the three-phase winding according to the charging and discharging power and the heating power;

[0093] Optionally, the expected current of the three-phase winding corresponding to the charge / discharge power and the heating power is pre-calibrated, and the correspondence between the calibrated charge / discharge power, the heating power, and the expected current of the three-phase winding is pre-stored in the controller. When the charge / discharge power and the heating power are obtained, the corresponding expected current of the three-phase winding is obtained based on the correspondence between the charge / discharge power, the heating power, and the expected current of the three-phase winding.

[0094] Optionally, the desired currents of the three-phase windings are obtained by calculation by the controller.

[0095] Optionally, the step of obtaining the desired current of the three-phase winding according to the charging and discharging power and the heating power in step S20 includes:

[0096] Step S21, obtaining the expected current of the first phase winding among the expected currents of the three-phase windings according to the charge and discharge power;

[0097] Calculate the expected current i of the first phase winding of a three-phase motor * u , that is, the expected current of the U-phase winding, the specific formula is as follows:

[0098]

[0099] Among them, P ch Represents the charge and discharge power of the power battery, η ch Represents the charge and discharge efficiency of the external power supply, η ch is a known value, i * u Represents the expected current of the U-phase winding, U C2 Represents the external power supply voltage.

[0100] Step S22, obtaining a desired DC component of the power battery according to the desired current of the first phase winding, the bus voltage, and the external power supply voltage;

[0101] Get bus voltage U C1 and external power supply voltage U C2 , use the following formula to calculate the expected DC component i of the power battery * bat- :

[0102]

[0103] Step S23, obtaining a desired AC component of the power battery based on the heating power of the power battery and the desired DC component;

[0104] Then the currently known parameter power battery heating power P h , DC internal resistance R of power battery bat～ , AC internal resistance R of power battery bat- and the expected DC component i of the power battery * bat- Substituting into the following formula, the expected AC component i of the power battery can be calculated * bat～

[0105] P h =(i * bat- ) 2 ·R bat- +(i * bat～ ) 2 ·R bat～

[0106] Step S24: Obtain the expected AC component of the bus current according to the expected AC component of the power battery.

[0107] According to the transfer function relationship between the power battery current and the bus current, and the selection of the appropriate switching frequency f SW , and determine the expected AC component of the bus current using the following formula:

[0108]

[0109] Among them, i * bat～ Represents the expected AC component of the power battery, and obtains i * link～ represents the desired AC component of the bus current, R bat Indicates the internal resistance of the power battery, C1 indicates Figure 2 Wherein, the capacitance of the first capacitor C1 is jω, and jω is the independent variable.

[0110] Step S25, based on the expected AC component i of the bus current * link～ , the expected current i of the first phase winding* u , obtaining desired currents of the second-phase winding and the third-phase winding.

[0111] According to the expected current i of the second phase winding * v and the desired current i of the third phase winding * w The relationship between the two phases is calculated as follows: * v and the desired current i of the third phase winding * w , specifically:

[0112] |i * v -i * w |=k·i * link～

[0113] i * v +i * w =-i * u

[0114] Wherein, k in the above formula represents the fundamental wave conversion coefficient, which can be calculated based on the bus current waveform.

[0115] Step S30 , controlling the currents in the second phase winding and the third phase winding of the three-phase motor based on the expected currents of the second phase winding and the third phase winding in the expected currents of the three-phase winding and the sampled currents of the second phase winding and the third phase winding.

[0116] According to the desired current and sampled current of the V-phase winding and the W-phase winding, the duty cycle adjustment amount of the control signal of the V-phase power switching element and the control signal of the W-phase power switching element are obtained respectively. Based on this duty cycle adjustment amount, the PWM control signal is output to the power switching elements of the boost circuit and the buck circuit via the PWM controller to control the current in the second phase winding and the third phase winding in the three-phase motor.

[0117] In this embodiment, the U-phase winding is connected to a switching element to realize the connection of an external power supply. The PWM control signal controls the power switching element of the V-phase and the power switching element of the W-phase, that is, the switching state of the power switching elements in the boost circuit and the buck circuit is controlled to realize the control of the current in the second-phase winding Lv and the third-phase winding Lw, thereby achieving the effect of controlling the heating efficiency and the charging and discharging efficiency of the power battery.

[0118] It should be noted that Figure 5 and Figure 6 This is a schematic diagram of the waveforms of each phase winding current and battery charge and discharge current in the battery heating mode and battery heating + low current charging mode obtained through simulation experiments.

[0119] The battery heating system operates in the battery heating mode, and the switching frequency f is determined according to the charging and discharging power and heating power of the power battery. SW ≈10kHz, the expected current i of the V-phase winding * v ≈-500A, expected current i of U phase winding * w Taking ≈500A as an example, Figure 5 The waveform corresponding to the battery heating system obtained by simulation in this case is shown. link Indicates the bus current, i bat represents the current of the power battery, I_v represents the V-phase winding current of the three-phase motor, I_w represents the W-phase winding current of the three-phase motor, I_u represents the U-phase winding current of the three-phase motor, I_C1 represents the current at the bus capacitor C1, and g_s4, s5 represent the control signals of the V-phase and W-phase power switching elements in the three-phase inverter.

[0120] The battery heating system operates in the battery heating + low current charging mode, and the switching frequency f is determined according to the charging and discharging power and heating power of the power battery. SW ≈5kHz, the expected current i of the V-phase winding * v ≈-500A, expected current i of U phase winding * w ≈480A as an example, Figure 6 The waveform corresponding to the battery heating system obtained by simulation in this case is shown. link Indicates the bus current, i bat represents the current of the power battery, I_v represents the V-phase winding current of the three-phase motor, I_w represents the W-phase winding current of the three-phase motor, I_u represents the U-phase winding current of the three-phase motor, I_C1 represents the current at the bus capacitor C1, and g_s4, s5 represent the control signals of the V-phase and W-phase power switching elements in the three-phase inverter.

[0121] Combine Figure 5 、 Figure 6 and Figure 2 It can also be concluded that i u 、i v and i w The direction of Figure 5 For example, the current value shown by I_v shows that at this time i v is a negative value, so at this time Figure 2 in i vThe direction is "neutral point N→midpoint V of the second phase bridge arm"; it can be seen from the current value shown by I_w that at this time, i w is positive, so at this time Figure 1 in i w The direction is "midpoint W of the third phase bridge arm → neutral point N"; it can be seen from the current value shown by I_u that there is no i u ,therefore Figure 2 No i u The PWM control signal controls the switching states of the third power switch element, the fourth power switch element, the fifth power switch element, and the sixth power switch element, thereby controlling i v The specific flow direction between the third power switch element and the fourth power switch element and i w The specific flow direction between the fifth power switch element and the sixth power switch element achieves the effect of controlling the battery heating efficiency and charging efficiency.

[0122] In one example, refer to Figure 4 An embodiment of the present application provides a power battery heating control method. Based on the embodiment shown in step S30 above, the step of "controlling the currents in the second-phase winding and the third-phase winding of the three-phase motor based on the expected currents of the second-phase winding and the third-phase winding, and the sampled currents of the second-phase winding and the third-phase winding" includes:

[0123] Step S31, comparing the desired current of the second-phase winding and the sampled current, determining a first duty cycle adjustment value of the power switch element of the second phase in the three-phase inverter based on the comparison result of the desired current and the sampled current of the second-phase winding, and controlling the power switch element of the second phase in the three-phase inverter based on the first duty cycle adjustment value to control the current of the second-phase winding in the three-phase motor;

[0124] Step S32: compare the expected current and the sampled current of the third group of windings, determine the second duty cycle adjustment amount of the power switching element of the third phase in the three-phase inverter based on the comparison result of the expected current and the sampled current of the third group of windings, and control the power switching element of the third phase in the three-phase inverter based on the second duty cycle adjustment amount to control the current of the third phase winding in the three-phase motor.

[0125] according to Figure 7 As can be seen from the control principle diagram, in this embodiment, the desired current i of the V-phase winding is obtained. * v and the sampling current i of the V-phase winding v Then, the desired current i of the V phase winding is * v and sampling current i vAfter comparison, the first PI (Proportional Integral) controller PI1 outputs the duty cycle adjustment value D of the V-phase power switch element according to the comparison result. vΔ The first PWM controller PWM1 adjusts the duty cycle of the V-phase power switch element D vΔ The output is a control signal S3 for controlling the third power switch element Q3 and a control signal S4 for the fourth power switch element Q4 in the three-phase inverter.

[0126] To obtain the desired current i of the W phase winding * w and sampling current i w Then, the desired current i of the W phase winding is * w and sampling current i w The second PI controller PI2 outputs the duty cycle adjustment value D of the W phase power switch element according to the comparison result. wΔ The second PWM controller PWM2 adjusts the duty cycle of the W-phase power switch element D wΔ , outputs a control signal S5 for controlling the fifth power switch element Q5 and a control signal S6 for the sixth power switch element Q6 in the three-phase inverter.

[0127] If the connection to the external power supply is achieved by leading the switching element from the V-phase winding, the PWM controller outputs the upper arm control signal, lower arm control signal of the U-phase power switching element and the upper arm control signal, lower arm control signal of the W-phase power switching element; if the connection to the external power supply is achieved by leading the switching element from the W-phase winding, the PWM controller outputs the upper arm control signal, lower arm control signal of the U-phase power switching element and the upper arm control signal, lower arm control signal of the V-phase power switching element.

[0128] It should be noted that, in this embodiment, the example of parallel control of V phase and W phase is used for illustration. In actual application scenarios, the control order of V phase and W phase is not limited. In addition to parallel control, W phase control can also be performed after V phase control, or V phase control can be performed after W phase control.

[0129] In another example, in order to improve the control response rate of the power battery heating system, before the above step S30, that is, before the step of "controlling the currents in the second-phase winding and the third-phase winding of the three-phase motor based on the expected currents of the second-phase winding and the third-phase winding and the sampled currents of the second-phase winding and the third-phase winding", the battery heating control method further includes:

[0130] Step S33 , obtaining a first duty cycle feedforward value of the fourth power switch element and a second duty cycle feedforward value of the fifth power switch element in the three-phase inverter according to the bus voltage and the external power supply voltage.

[0131] The first duty cycle feedforward value and the second duty cycle feedforward value are calculated as follows:

[0132]

[0133]

[0134] Among them, D v_boost In this embodiment, it is the duty cycle feedforward value of the fourth power switch element of the second phase, that is, the first duty cycle feedforward value, D w_buck In this embodiment, it is the duty cycle feedforward value of the fifth power switch element of the third phase, that is, the second duty cycle feedforward value.

[0135] When the battery heating control method includes step S33, the above step S30, i.e., the step of “controlling the currents in the second-phase winding and the third-phase winding of the three-phase motor based on the expected currents of the second-phase winding and the third-phase winding among the expected currents of the three-phase winding and the sampled currents of the second-phase winding and the third-phase winding” includes:

[0136] Step S34: compare the expected current and the sampled current of the second-phase winding; determine a first duty cycle adjustment base value for the power switching element of the second phase in the three-phase inverter based on the comparison result of the expected current and the sampled current of the second-phase winding; and control the power switching element of the second phase in the three-phase inverter based on the first duty cycle adjustment base value and the first duty cycle feedforward value to control the current of the second-phase winding in the three-phase motor.

[0137] Step S35: Compare the expected current and the sampled current of the third-phase winding; determine a second duty cycle adjustment base value for the power switching element of the third phase in the three-phase inverter based on the comparison result of the expected current and the sampled current of the third-phase winding; control the power switching element of the third phase in the three-phase inverter based on the second duty cycle adjustment base value and the second duty cycle feedforward value to control the current of the third-phase winding in the three-phase motor.

[0138] like Figure 8 As shown, the desired current i in the second phase winding * v and sampling current i v After comparison, the first PI controller PI1 outputs the first duty cycle adjustment basic amount D according to the comparison result. vΔ , the first duty cycle feedforward value D v_boost Added to the first duty cycle adjustment base amount D vΔThe first duty cycle adjustment superposition amount D is obtained. v The first PWM controller PWM1 adjusts the superposition amount D according to the first duty cycle v The control signal S3 and the control signal S4 for controlling the power switching element of the V phase are output.

[0139] The expected current i in the third phase winding * w and sampling current i w After comparison, the second PI controller PI2 outputs the second duty cycle adjustment basic amount D according to the comparison result. wΔ , the second duty cycle feedforward value D w_buck Added to the second duty cycle adjustment base amount D wΔ The second duty cycle adjustment superposition amount D is obtained. w The second PWM controller PWM2 adjusts the superposition amount D according to the second duty cycle w The control signal S5 and the control signal S6 for controlling the power switching element of the W phase are output.

[0140] In addition, an embodiment of the present application also proposes an electric vehicle, which includes a power battery heating system, a memory and a processor. The memory is used to store one or more instructions, and the instructions are executed at least by the processor. The processor is used to implement the above-mentioned power battery heating control method.

[0141] In addition, the present application also proposes a computer-readable storage medium, on which an executable program for implementing the above-mentioned power battery control method is stored.

[0142] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or system comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or system. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or system comprising the element.

[0143] The serial numbers of the above embodiments of the present invention are for description only and do not represent the advantages or disadvantages of the embodiments.

[0144] Through the description of the above embodiments, those skilled in the art can clearly understand that the above embodiment methods can be implemented by means of software plus the necessary general hardware platform, and of course can also be implemented by hardware, but in many cases the former is a better embodiment. Based on this understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes a number of instructions for enabling a terminal device (which can be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in each embodiment of the present invention.

[0145] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A power battery heating control method, characterized in that: Applied to a power battery heating system, the power battery heating system includes a three-phase inverter and a three-phase motor, a connecting line between a first-phase winding of the three-phase motor and a first-phase bridge arm of the three-phase inverter is led out, and the led-out connecting line is used to connect to an external power supply, the three-phase inverter includes a third power switching element, a fourth power switching element, a fifth power switching element, and a sixth power switching element, and the power battery heating control method includes: When the external power supply is connected to the power battery heating system, the charging and discharging power and heating power of the power battery are obtained; Obtaining a desired current of the three-phase winding according to the charging and discharging power and the heating power; Based on the expected currents of the second phase winding and the third phase winding in the expected currents of the three-phase winding and the sampled currents of the second phase winding and the third phase winding, the currents in the second phase winding and the third phase winding of the three-phase motor are controlled, wherein the current directions of the second phase winding and the third phase winding are opposite, and the difference in the current amplitudes of the second phase winding and the third phase winding is less than a preset current amplitude; Among them, the third power switching element, the fourth power switching element and the second phase winding constitute a boost circuit, the fifth power switching element, the sixth power switching element and the third phase winding constitute a buck circuit, and the boost circuit and the buck circuit are connected in parallel to form a circuit topology for multiplexing winding boost charging.

2. The power battery heating control method according to claim 1, characterized in that: The obtaining of the desired current of the three-phase winding according to the charging and discharging power and the heating power includes: Obtaining, according to the charge and discharge power, an expected current of a first phase winding among the expected currents of the three-phase windings; Obtaining a desired DC component of the power battery according to a desired current of the first phase winding, a bus voltage, and an external power supply voltage; Obtaining a desired alternating current component of the power battery based on the heating power and the desired direct current component of the power battery; Obtaining a desired AC component of the bus current according to the desired AC component of the power battery; Expected currents of the second and third phase windings are obtained based on the expected AC component of the bus current and the expected current of the first phase winding.

3. The power battery heating control method according to claim 1, characterized in that: The controlling of the currents in the second-phase winding and the third-phase winding in the three-phase motor based on the expected currents of the second-phase winding and the third-phase winding in the expected currents of the three-phase winding and the sampled currents of the second-phase winding and the third-phase winding includes: comparing the desired current and the sampled current of the second-phase winding, determining a first duty cycle adjustment value of a power switch element of the second phase in the three-phase inverter based on the comparison result of the desired current and the sampled current of the second-phase winding, and controlling the power switch element of the second phase in the three-phase inverter based on the first duty cycle adjustment value to control the current of the second-phase winding in the three-phase motor; Compare the expected current and the sampled current of the third group of windings, determine a second duty cycle adjustment amount of the power switching element of the third phase in the three-phase inverter based on the comparison result of the expected current and the sampled current of the third group of windings, and control the power switching element of the third phase in the three-phase inverter based on the second duty cycle adjustment amount to control the current of the third phase winding in the three-phase motor.

4. The power battery heating control method according to claim 1, characterized in that: Before controlling the currents in the second-phase winding and the third-phase winding in the three-phase motor based on the expected currents of the second-phase winding and the third-phase winding and the sampled currents of the second-phase winding and the third-phase winding, the method further includes: A first duty cycle feedforward value of the fourth power switch element and a second duty cycle feedforward value of the fifth power switch element in the three-phase inverter are obtained according to the bus voltage and the external power supply voltage.

5. The power battery heating control method according to claim 4, characterized in that: The controlling of the currents in the second-phase winding and the third-phase winding in the three-phase motor based on the expected currents of the second-phase winding and the third-phase winding in the expected currents of the three-phase winding and the sampled currents of the second-phase winding and the third-phase winding includes: comparing the desired current and the sampled current of the second-phase winding, determining a first duty cycle adjustment base value for the second-phase power switching element in the three-phase inverter based on the comparison result of the desired current and the sampled current of the second-phase winding, and controlling the second-phase power switching element in the three-phase inverter based on the first duty cycle adjustment base value and the first duty cycle feedforward value to control the current of the second-phase winding in the three-phase motor; Compare the expected current and the sampled current of the third-phase winding, determine a second duty cycle adjustment base value of the power switching element of the third phase in the three-phase inverter based on the comparison result of the expected current and the sampled current of the third-phase winding, and control the power switching element of the third phase in the three-phase inverter based on the second duty cycle adjustment base value and the second duty cycle feedforward value to control the current of the third-phase winding in the three-phase motor.

6. An electric vehicle, characterized in that: The electric vehicle includes a power battery heating system, a memory and a processor, the memory is used to store one or more instructions, the instructions are at least executed by the processor, and the processor is used to implement the power battery heating control method according to any one of claims 1 to 5.

7. A computer-readable storage medium, characterized in that The computer-readable storage medium stores an executable program for implementing the power battery heating control method according to any one of claims 1 to 5.

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