Charging control method, device, medium and vehicle of vehicle charging system

Abstract

The present invention relates to the field of vehicle charging technology, and specifically provides a charging control method, device, medium and vehicle of a vehicle charging system, aiming to solve the problem of how to effectively reduce the iron loss of the motor in the power control unit PEU and improve the charging efficiency of electric vehicles when the voltage level of the power battery and the charging facility do not match. The vehicle charging system of the present invention includes a voltage conversion device formed by the electric drive system of the reused vehicle. The charging control method can first convert the output voltage of the external charging facility through the voltage conversion device when the voltage level does not match, and then charge the power battery. At the same time, during the charging process, one or more phases of the inverter are selectively controlled according to the charging current input to the charging port to convert the output voltage of the external charging facility, so that the DC component flowing through the stator winding in the voltage conversion device is maintained within a preset range, reducing the iron loss of the motor, thereby improving the charging efficiency and charging power.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle charging, and specifically provides a charging control method, device, medium and vehicle of a vehicle charging system. Background Art

[0002] With the rapid development of electric vehicle technology, the voltage level of the medium and high voltage system of electric vehicles is also increasing, such as from 400V to 800V. However, the charging facilities cannot be upgraded and renovated in time due to factors such as cost, resulting in the charging facilities being unable to adapt to the rapid changes in the voltage level of the medium and high voltage system of electric vehicles. In order to solve this problem, a patent application with publication number CN112600411A discloses a voltage conversion device, which reuses the inverter and motor winding in the power control unit PEU in the electric vehicle to achieve a boost function from a second DC voltage such as 400V to a first DC voltage such as 800V, and can convert the lower voltage provided by the charging facility into a higher voltage to charge the power battery, thereby taking into account the charging facilities of different voltage levels on the market.

[0003] See attached Figure 1 , Figure 1 The main structure of a vehicle charging system constructed by using the above voltage conversion device is shown as an example. Figure 1 As shown in the figure, the vehicle charging system mainly connects the charging port of the charging facility to the neutral point of the three-phase stator winding. When the charging current flows through the three-phase stator winding at the same time, the mutual inductance voltage generated between the three-phase stator winding cancels each other out. Although this will reduce the ripple current of the charging current on the input side of the power battery, it will not reduce the ripple current in each phase of the stator winding. A larger ripple current will increase the iron loss of the motor, thereby reducing the charging efficiency of the electric vehicle. See the attached Figure 2 , Figure 2 The main structure of another vehicle charging system constructed by using the above voltage conversion device is shown as an example. Figure 2 As shown, the vehicle charging system mainly connects the charging port of the charging facility with a single-phase stator winding. Although this structure can use the mutual inductance voltage generated between the three-phase stator windings to suppress the ripple current in each phase of the stator winding, during the charging process, the charging current output by the charging facility first enters a single-phase stator winding (extraction phase winding) and then is diverted to the other two-phase stator windings through this phase stator winding. Since the current flowing through the extraction phase winding is relatively large, the extraction phase winding will generate a large amount of heat, thereby increasing copper loss, and also reducing the charging efficiency and charging power.

[0004] It can be seen that when the voltage level of the power battery and the charging facility does not match, how to effectively reduce the iron loss and copper loss generated by the motor in the power control unit PEU and improve the charging efficiency of electric vehicles is a problem that needs to be solved urgently.

[0005] Accordingly, the art requires a new vehicle charging solution to solve the above problems. Summary of the invention

[0006] In order to overcome the above-mentioned defects, the present invention is proposed to provide a charging control method, device, medium and vehicle for a vehicle charging system that solves or at least partially solves the above-mentioned technical problems.

[0007] In a first aspect, the present invention provides a charging control method for a vehicle charging system, wherein the vehicle comprises a power battery and an electric drive system, wherein the electric drive system comprises an inverter and a motor, wherein the DC side of the inverter is connected to the power battery, and the AC side of the inverter is connected to the stator winding of the motor, wherein the charging system comprises a charging port and a voltage conversion device, wherein the voltage conversion device comprises the inverter, the stator winding, a first positive terminal, a second positive terminal and a negative terminal, wherein the first positive terminal and the negative terminal are respectively connected to the positive and negative electrodes of the DC side, and the second positive terminal is connected to the center tap of the stator winding, wherein the charging control method comprises:

[0008] When the output voltage level of the external charging facility connected to the charging port does not match the charging voltage level of the power battery, control the power battery, the voltage conversion device and the charging port to form a charging loop and control the external charging facility to charge the power battery through the charging loop in a constant voltage charging mode;

[0009] During the charging process, one or more phases of the inverter are selectively controlled to convert the output voltage of the external charging facility according to the charging current input to the charging port, so that the DC component flowing through the stator winding in the voltage conversion device is maintained within a preset range, thereby reducing the iron loss of the motor.

[0010] In a technical solution of the charging control method of the vehicle charging system, when the multi-phase bridge arm is controlled to perform voltage conversion on the output voltage of the external charging facility, the method further includes:

[0011] The multi-phase bridge arms are interleavedly controlled so as to reduce the ripple current generated by the stator winding in the voltage conversion device through the mutual inductance voltage formed by the multi-phase bridge arms during the interleaved control, thereby reducing the iron loss of the motor.

[0012] In a technical solution of the charging control method of the above-mentioned vehicle charging system, the step of "interleaving control of the multi-phase bridge arms" specifically includes:

[0013] If the number of the multi-phase bridge arms is two, the multi-phase bridge arms are staggered controlled by adopting a 180° staggered control method;

[0014] If the number of the multi-phase bridge arms is three, the multi-phase bridge arms are interlaced controlled by adopting a 120° interlaced control method.

[0015] In a technical solution of the charging control method of the above-mentioned vehicle charging system, the step of "selectively controlling one or more phases of the inverter to convert the output voltage of the external charging facility according to the charging current input to the charging port" specifically includes:

[0016] If I r th1 , then controlling a phase bridge arm to perform voltage conversion on the output voltage;

[0017] If I th1 ≤I r ≤I th2 , then control the two-phase bridge arm to perform voltage conversion on the output voltage;

[0018] If I r >I th2 , then controlling the three-phase bridge arm to perform voltage conversion on the output voltage;

[0019] Among them, I th1 and I th2 Respectively represent the preset first current threshold and the second current threshold.

[0020] In a second aspect, a charging control device of a vehicle charging system is provided, wherein the vehicle comprises a power battery and an electric drive system, wherein the electric drive system comprises an inverter and a motor, wherein a DC side of the inverter is connected to the power battery, and an AC side of the inverter is connected to a stator winding of the motor, wherein the charging system comprises a charging port and a voltage conversion device, wherein the voltage conversion device comprises the inverter, the stator winding, a first positive terminal, a second positive terminal and a negative terminal, wherein the first positive terminal and the negative terminal are respectively connected to a positive pole and a negative pole of the DC side, and the second positive terminal is connected to a center tap of the stator winding, wherein the charging control device comprises:

[0021] a first charging control module, configured to control the power battery, the voltage conversion device and the charging port to form a charging loop and control the external charging facility to charge the power battery through the charging loop in a constant voltage charging mode when the output voltage level of the external charging facility connected to the charging port does not match the charging voltage level of the power battery;

[0022] ​The second charging control module is configured to selectively control one or more phases of the inverter to perform voltage conversion on the output voltage of the external charging facility according to the charging current input to the charging port during the charging process, so that the DC component flowing through the stator winding in the voltage conversion device is maintained within a preset range, thereby reducing the iron loss of the motor.

[0023] In a technical solution of the charging control device of the above-mentioned vehicle charging system, the second charging control module includes an interleaving control submodule, and the interleaving control submodule is configured to perform interleaving control on the multi-phase bridge arm when controlling the multi-phase bridge arm to perform voltage conversion on the output voltage of the external charging facility, so as to reduce the ripple current generated by the stator winding in the voltage conversion device through the mutual inductance voltage formed by the multi-phase bridge arm during interleaving control, thereby reducing the iron loss of the motor.

[0024] In a technical solution of the charging control device of the above vehicle charging system, the interleaving control submodule includes a first interleaving control unit and a second interleaving control unit;

[0025] The first interleaving control unit is configured to interleave the multi-phase bridge arms using a 180° interleaving control method when the number of the multi-phase bridge arms is two;

[0026] The second interleaving control unit is configured to perform interleaving control on the multi-phase bridge arms by adopting a 120° interleaving control method when the number of the multi-phase bridge arms is three.

[0027] In a technical solution of the charging control device of the above vehicle charging system, the first charging control module includes a first bridge arm control submodule, a second bridge arm control submodule and a third bridge arm control submodule;

[0028] The first bridge arm control submodule is configured to r th1 When controlling a phase bridge arm to perform voltage conversion on the output voltage;

[0029] The second bridge arm control submodule is configured to th1 ≤I r ≤I th2 Controlling the two-phase bridge arms to perform voltage conversion on the output voltage;

[0030] The third bridge arm control submodule is configured to r >I th2 Controlling the three-phase bridge arm to perform voltage conversion on the output voltage;

[0031] Among them, I th1 and I th2 Respectively represent the preset first current threshold and the second current threshold.​

[0032] In a third aspect, a control device is provided, which includes a processor and a storage device, wherein the storage device is suitable for storing multiple program codes, and the program codes are suitable for being loaded and run by the processor to execute the charging control method for the vehicle charging system described in any one of the technical solutions of the charging control method for the above-mentioned vehicle charging system.

[0033] In a fourth aspect, a computer-readable storage medium is provided, which stores a plurality of program codes, wherein the program codes are suitable for being loaded and run by a processor to execute the vehicle charging system charging control method described in any one of the technical solutions of the vehicle charging system charging control method.

[0034] In a fifth aspect, a vehicle is provided, comprising a power battery and an electric drive system, wherein the electric drive system comprises an inverter and a motor, wherein the DC side of the inverter is connected to the power battery, and the AC side of the inverter is connected to the stator winding of the motor, and the vehicle also comprises a charging control device for a vehicle charging system described in any one of the technical solutions of the charging control device for the above-mentioned vehicle charging system or a control device described in the technical solution of the above-mentioned control device.

[0035] Solution 1. A charging control method for a vehicle charging system, wherein the vehicle comprises a power battery and an electric drive system, wherein the electric drive system comprises an inverter and a motor, wherein the DC side of the inverter is connected to the power battery, and the AC side of the inverter is connected to the stator winding of the motor, wherein the charging system comprises a charging port and a voltage conversion device, wherein the voltage conversion device comprises the inverter, the stator winding, a first positive terminal, a second positive terminal and a negative terminal, wherein the first positive terminal and the negative terminal are respectively connected to the positive and negative poles of the DC side, and the second positive terminal is connected to the center tap of the stator winding.

[0036] Characterized in that the charging control method comprises:

[0037] When the output voltage level of the external charging facility connected to the charging port does not match the charging voltage level of the power battery, control the power battery, the voltage conversion device and the charging port to form a charging loop and control the external charging facility to charge the power battery through the charging loop in a constant voltage charging mode;

[0038] During the charging process, one or more phases of the inverter are selectively controlled to convert the output voltage of the external charging facility according to the charging current input to the charging port, so that the DC component flowing through the stator winding in the voltage conversion device is maintained within a preset range, thereby reducing the iron loss of the motor.

[0039] Solution 2. The charging control method of the vehicle charging system according to Solution 1 is characterized in that when controlling the multi-phase bridge arm to perform voltage conversion on the output voltage of the external charging facility, the method further comprises:

[0040] The multi-phase bridge arms are interleavedly controlled so as to reduce the ripple current generated by the stator winding in the voltage conversion device through the mutual inductance voltage formed by the multi-phase bridge arms during the interleaved control, thereby reducing the iron loss of the motor.

[0041] Solution 3. The charging control method of the vehicle charging system according to Solution 2 is characterized in that the step of "interleaving the multi-phase bridge arms" specifically includes:

[0042] If the number of the multi-phase bridge arms is two, the multi-phase bridge arms are staggered controlled by adopting a 180° staggered control method;

[0043] If the number of the multi-phase bridge arms is three, the multi-phase bridge arms are interlaced controlled by adopting a 120° interlaced control method.

[0044] Solution 4. The charging control method of the vehicle charging system according to Solution 1 is characterized in that the step of "selectively controlling one or more phases of the inverter to convert the output voltage of the external charging facility according to the charging current input to the charging port" specifically includes:

[0045] If I r th1 , then controlling a phase bridge arm to perform voltage conversion on the output voltage;

[0046] If I th1 ≤I r ≤I th2 , then control the two-phase bridge arm to perform voltage conversion on the output voltage;

[0047] If I r >I th2 , then controlling the three-phase bridge arm to perform voltage conversion on the output voltage;

[0048] Among them, I th1 and I th2 Respectively represent the preset first current threshold and the second current threshold.

[0049] ​Solution 5. A charging control device for a vehicle charging system, the vehicle comprising a power battery and an electric drive system, the electric drive system comprising an inverter and a motor, the DC side of the inverter being connected to the power battery, the AC side of the inverter being connected to the stator winding of the motor, the charging system comprising a charging port and a voltage conversion device, the voltage conversion device comprising the inverter, the stator winding, a first positive terminal, a second positive terminal and a negative terminal, the first positive terminal and the negative terminal being connected to the positive and negative poles of the DC side, respectively, the second positive terminal being connected to the center tap of the stator winding,

[0050] Characterized in that the charging control device comprises:

[0051] a first charging control module, configured to control the power battery, the voltage conversion device and the charging port to form a charging loop and control the external charging facility to charge the power battery through the charging loop in a constant voltage charging mode when the output voltage level of the external charging facility connected to the charging port does not match the charging voltage level of the power battery;

[0052] The second charging control module is configured to selectively control one or more phases of the inverter to perform voltage conversion on the output voltage of the external charging facility according to the charging current input to the charging port during the charging process, so that the DC component flowing through the stator winding in the voltage conversion device is maintained within a preset range, thereby reducing the iron loss of the motor.

[0053] Solution 6. The charging control device of the vehicle charging system according to Solution 5 is characterized in that the second charging control module includes an interleaving control submodule, and the interleaving control submodule is configured to perform interleaving control on the multi-phase bridge arm when controlling the multi-phase bridge arm to perform voltage conversion on the output voltage of the external charging facility, so as to reduce the ripple current generated by the stator winding in the voltage conversion device through the mutual inductance voltage formed by the multi-phase bridge arm during interleaving control, thereby reducing the iron loss of the motor.

[0054] Solution 7. The charging control device of the vehicle charging system according to Solution 6 is characterized in that the interleaving control submodule includes a first interleaving control unit and a second interleaving control unit;

[0055] The first interleaving control unit is configured to interleave the multi-phase bridge arms using a 180° interleaving control method when the number of the multi-phase bridge arms is two;

[0056] The second interleaving control unit is configured to perform interleaving control on the multi-phase bridge arms by adopting a 120° interleaving control method when the number of the multi-phase bridge arms is three.

[0057] Solution 8. The charging control device of the vehicle charging system according to Solution 5 is characterized in that the first charging control module includes a first bridge arm control submodule, a second bridge arm control submodule and a third bridge arm control submodule;

[0058] The first bridge arm control submodule is configured to r th1 When controlling a phase bridge arm to perform voltage conversion on the output voltage;

[0059] The second bridge arm control submodule is configured to th1 ≤I r ≤I th2 Controlling the two-phase bridge arms to perform voltage conversion on the output voltage;

[0060] The third bridge arm control submodule is configured to r >I th2 Controlling the three-phase bridge arm to perform voltage conversion on the output voltage;

[0061] Among them, I th1 and I th2 Respectively represent the preset first current threshold and the second current threshold.

[0062] Scheme 9. A control device, comprising a processor and a storage device, wherein the storage device is suitable for storing multiple program codes, and is characterized in that the program codes are suitable for being loaded and run by the processor to execute the charging control method of the vehicle charging system described in any one of Schemes 1 to 4.

[0063] Solution 10. A computer-readable storage medium storing a plurality of program codes, wherein the program codes are suitable for being loaded and run by a processor to execute the charging control method of a vehicle charging system according to any one of Solutions 1 to 4.

[0064] Scheme 11. A vehicle comprising a power battery and an electric drive system, wherein the electric drive system comprises an inverter and a motor, wherein the DC side of the inverter is connected to the power battery, and the AC side of the inverter is connected to the stator winding of the motor, and wherein the vehicle further comprises a charging control device for the vehicle charging system described in any one of Schemes 5 to 8 or the control device described in Scheme 9.

[0065] The above one or more technical solutions of the present invention have at least one or more of the following beneficial effects:

[0066] ​In the technical solution for implementing the present invention, the vehicle charging system may include a charging port and a voltage conversion device. The voltage conversion device may reuse the vehicle's electric drive system, which may include an inverter and a motor, the DC side of the inverter being connected to a power battery, and the AC side of the inverter being connected to a stator winding of the motor. The voltage conversion device may include the above-mentioned inverter and the above-mentioned stator winding, and may also include a first positive terminal, a second positive terminal, and a negative terminal, wherein the first positive terminal and the negative terminal are respectively connected to the positive and negative poles of the DC side of the inverter, and the second positive terminal is connected to the center tap of the stator winding. The first positive terminal, the second positive terminal, and the negative terminal constitute the external power input side of the voltage conversion device, and the DC side of the inverter constitutes the external power output side of the voltage conversion device. When the output voltage level of the external power supply (such as an external charging facility) connected to the external power input side matches the supply voltage level (such as the charging voltage level of the power battery) of the load (such as a power battery) connected to the external power output side, the output electric energy of the external power supply can be directly transmitted to the load; when the output voltage level of the external power supply does not match the supply voltage level of the load, the output electric energy of the external power supply can be voltage-converted, and then the electric energy after voltage conversion can be transmitted to the load.

[0067] According to the charging control method of an embodiment of the present invention, when the output voltage level of the external charging facility connected to the charging port in the above-mentioned vehicle charging system does not match the charging voltage level of the power battery, the power battery, the voltage conversion device and the charging port can be controlled to form a charging circuit and the external charging facility can be controlled to charge the power battery through the charging circuit in a constant voltage charging mode (control the external charging facility to output a constant voltage to the vehicle charging system). At the same time, during the charging process, one or more phases of the inverter are selectively controlled according to the charging current input to the charging port to perform voltage conversion on the output voltage of the external charging facility, so that the DC component flowing through the stator winding in the voltage conversion device is maintained within a preset range, thereby reducing the iron loss of the motor and improving the charging efficiency of the power battery.

[0068] Specifically, during the charging process, the battery power of the power battery changes from low power to high power until it is fully charged. When the external charging facility is controlled to charge the power battery in a constant voltage charging mode, as the battery power of the power battery continues to increase, the charging current input to the charging port will continue to decrease (the charging power is constantly changing). If the number of bridge arms of the inverter that converts the output voltage of the external charging facility remains unchanged during the entire charging process, since the charging current input to the charging port will continue to decrease, the DC component flowing through the stator winding connected to the corresponding bridge arm will also continue to decrease. After analyzing the magnetic induction intensity, DC bias, magnetic permeability and iron loss of the asynchronous motor, the inventor determined that: for the asynchronous motor, if the DC component in the stator winding is smaller, the motor iron loss is greater, and the motor iron loss can be reduced by increasing the DC component in the stator winding (see below for the specific analysis process). The charging control method according to an embodiment of the present invention utilizes the above-mentioned principle that the iron loss of the motor can be reduced by increasing the DC component in the stator winding. When the electric drive system of the reused vehicle charges the power battery, the DC component flowing through the stator winding in the voltage conversion device is controlled to be maintained within a preset range, so that the magnetic permeability is maintained within a lower range, and the iron loss of the motor is also maintained within a lower range, thereby improving the charging efficiency of the power battery.

[0069] Among them, by analyzing the magnetic induction intensity, DC bias, magnetic permeability and iron loss of the asynchronous motor, it is determined that "the smaller the DC component in the stator winding, the more the motor iron loss, and the motor iron loss can be reduced by increasing the DC component in the stator winding". The analysis process includes:

[0070] (1) According to the iron loss calculation formula (P T represents iron loss, k represents loss coefficient, f represents switching frequency of inverter, m and n are preset constants, B ac represents the magnetic induction intensity, V represents the core volume, N L represents the number of turns of the stator winding, ΔI represents the current change, μ represents the magnetic permeability, and MPL represents the magnetic path length) can determine that the larger the magnetic permeability μ, the greater the iron loss P T The larger the magnetic permeability μ, the smaller the iron loss P T The smaller.

[0071] (2) See Appendix Figure 3 , Figure 3 The relationship curves of the magnetic permeability and magnetic induction intensity of the asynchronous motor and the magnetic field intensity are shown as examples, wherein the horizontal axis H (A / m) represents the magnetic field intensity, the vertical axis B (T) represents the magnetic induction intensity, and the vertical axis u (mH / m) represents the magnetic permeability. Figure 3As shown, the magnetic permeability u will have a large difference with the increase of the magnetic field strength H, especially after exceeding a certain magnetic field strength H, the magnetic permeability u will decrease with the increase of the magnetic field strength H.

[0072] (3) See Appendix Figure 4 , Figure 4 The relationship curves of magnetic field intensity, magnetic induction intensity and DC bias when the asynchronous motor works in DC induction mode are shown as an example, where I DC Indicates DC bias, B dc Indicated by the DC bias I DC The magnetic induction intensity generated, H represents the magnetic field intensity. A person skilled in the art can determine that: the DC bias I DC The larger the value, the greater the magnetic field strength it generates, which in turn makes the magnetic induction intensity B dc The bigger.

[0073] Based on the above analysis, it can be seen that by increasing the DC bias I DC The magnetic field strength H can be increased, and after the magnetic field strength H reaches a certain value, the magnetic permeability u will decrease with the increase of the magnetic field strength H, and then the iron loss P can be reduced after the magnetic permeability u decreases. T ; Accordingly, reduce the DC bias I DC The magnetic field strength H can also be reduced. After the magnetic field strength H reaches a certain value, the magnetic permeability u will increase as the magnetic field strength H decreases, thereby increasing the iron loss P. T Therefore, it can be determined that "the smaller the DC component in the stator winding, the greater the motor iron loss, and the motor iron loss can be reduced by increasing the DC component in the stator winding."

[0074] Furthermore, in the technical solution for implementing the present invention, when controlling the multi-phase bridge arm to perform voltage conversion on the output voltage of the external charging facility, the multi-phase bridge arm can be interleavedly controlled to reduce the ripple current generated by the stator winding in the voltage conversion device through the mutual inductance voltage formed by the multi-phase bridge arm during the interleaved control, thereby reducing the iron loss of the motor.

[0075] In the process of staggered control of multi-phase bridge arms, if the upper bridge arm or the lower bridge arm of the two-phase bridge arm is in the on state, the charging current flowing through the stator winding connected to the two-phase bridge arm is on an upward trend. If one of the phase bridge arms is controlled to be turned off at this time, the charging current flowing through the stator winding connected to this phase bridge arm will be on a downward trend. As the charging current in one phase stator winding increases and the charging current in the other phase stator winding decreases, the mutual inductance voltage generated between the two phase stator windings will increase, thereby increasing the winding voltage of the two phase stator windings. Since the charging power will not change suddenly at this moment, the current growth at this moment can be suppressed by increasing the winding voltage under the premise of unchanged power, thereby reducing the ripple current, thereby reducing the iron loss of the motor and improving the charging efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] The disclosure of the present invention will become more easily understood with reference to the accompanying drawings. It is easy for those skilled in the art to understand that these drawings are only for illustrative purposes and are not intended to limit the scope of protection of the present invention. Among them:

[0077] Figure 1 It is a schematic diagram of the main structural block diagram of a vehicle charging system;

[0078] Figure 2 It is a schematic diagram of the main structural block diagram of another vehicle charging system;

[0079] Figure 3 It is a schematic diagram of the relationship curves between the magnetic permeability and magnetic induction intensity of the asynchronous motor and the magnetic field intensity;

[0080] Figure 4 It is a diagram showing the relationship between the magnetic field intensity, magnetic induction intensity and DC bias when the asynchronous motor works in DC induction mode;

[0081] Figure 5 According to one embodiment of the present invention, Figure 1 A schematic diagram of the flow path of the charging current when the vehicle charging system charges the power battery;

[0082] Figure 6 is a flow chart of main steps of a charging control method for a vehicle charging system according to an embodiment of the present invention;

[0083] Figure 7 It is the electrical schematic diagram of the inductance of the three-phase stator winding of an asynchronous motor;

[0084] Figure 8 is a schematic diagram of control signals of a three-phase bridge arm in a 120° staggered control mode according to an embodiment of the present invention;

[0085] Fig. 9is a schematic diagram of control signals of a three-phase bridge arm in a 180° staggered control mode according to an embodiment of the present invention;

[0086] Fig.10 It is a schematic diagram of the main structure block diagram of a charging control device of a vehicle charging system according to an embodiment of the present invention.

[0087] Reference numerals list :

[0088] 1: power battery; 2: voltage conversion device; 3: charging port; 21: first positive terminal; 22: second positive terminal; 23: negative terminal. DETAILED DESCRIPTION

[0089] Some embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0090] In the description of the present invention, "module" and "processor" may include hardware, software or a combination of the two. A module may include hardware circuits, various suitable sensors, communication ports, and memories, and may also include software parts, such as program codes, or a combination of software and hardware. The processor may be a central processing unit, a microprocessor, a digital signal processor, or any other suitable processor. The processor has data and / or signal processing functions. The processor may be implemented in software, hardware, or a combination of the two. Non-temporary computer-readable storage media include any suitable media that can store program codes, such as magnetic disks, hard disks, optical disks, flash memory, read-only memory, random access memory, etc.

[0091] Here we first explain some terms involved in the present invention.

[0092] The power electronic device may be a fully controlled power semiconductor device, such as a metal oxide semiconductor field effect transistor (MOSFET), an insulated gate bipolar transistor (IGBT) or an integrated gate commutated thyristor (IGCT). At the same time, these fully controlled power semiconductor devices are all three-terminal devices, such as a MOSFET including a source, a drain and a gate, an IGBT including a collector, an emitter and a gate, and an IGCT including a collector, an emitter and a gate. Among them, the source, the drain, the collector and the emitter are the main electrodes, and the gate and the gate are the control electrodes. In order to clearly describe the main electrodes of the power electronic device, the main electrode in the power input direction of the power electronic device is described as the first main electrode (such as the drain of the MOSFET and the collector of the IGBT) in the present invention, and the main electrode in the power output direction is described as the second main electrode (such as the source of the MOSFET and the emitter of the IGBT).

[0093] Below we first combine the attached Figure 5 The vehicle charging system in the embodiment of the present invention is described, and then the charging control method of the vehicle charging system in the embodiment of the present invention is specifically described.

[0094] In an embodiment of the present invention, the vehicle charging system can reuse the vehicle's electric drive system. Among them, the vehicle's electric drive system may include an inverter and a motor, the DC side of the inverter is connected to the power battery, and the AC side of the inverter is connected to the stator winding of the motor. The inverter can convert the DC power output by the power battery into AC power, and then make the motor operate under the control of the AC power to provide power to drive the vehicle. The vehicle charging system may include a charging port and a voltage conversion device, and the voltage conversion device may include an inverter, a stator winding, a first positive terminal, a second positive terminal and a negative terminal, the first positive terminal and the negative terminal are respectively connected to the positive and negative poles of the DC side, and the second positive terminal is connected to the center tap of the stator winding.

[0095] See attached Figure 5 The vehicle charging system may include a power battery 1, a voltage conversion device 2 and a charging port 3. The voltage conversion device 2 may include the inverter in the aforementioned electric drive system and the stator winding of the motor. The three-phase stator winding of the motor is connected in a Y-type connection to form a center tap. In addition, the voltage conversion device 2 may also include a first positive terminal 21, a second positive terminal 22 and a negative terminal 23. The first positive terminal 21 and the negative terminal 23 are respectively connected to the positive and negative poles of the DC side, and the second positive terminal 22 is connected to the center tap of the stator winding.

[0096] 1. Inverter

[0097] The inverter may be a three-phase full-bridge inverter, which includes three-phase bridge arms, each phase bridge arm includes an upper bridge arm and a lower bridge arm. The upper bridge arm and the lower bridge arm of the first phase bridge arm include power electronic devices Q1 and Q2, respectively, the upper bridge arm and the lower bridge arm of the second phase bridge arm include power electronic devices Q3 and Q4, respectively, and the upper bridge arm and the lower bridge arm of the third phase bridge arm include power electronic devices Q5 and Q6, respectively. The three-phase bridge arms are respectively connected to the three-phase stator winding L, and the three-phase stator winding L is connected in a Y-type connection to form a center tap.

[0098] 2. First positive terminal 21, second positive terminal 22 and negative terminal 23

[0099] The first positive terminal 21 of the voltage conversion device 2 is connected to the positive pole of the DC side in the inverter, the second positive terminal 22 is connected to the center tap of the three-phase stator winding L, and the negative terminal 23 is connected to the negative pole of the DC side in the inverter. The first positive terminal 21, the second positive terminal 22 and the negative terminal 23 constitute the external power input side of the voltage conversion device 2, and the DC side in the inverter constitutes the external power output side of the voltage conversion device 2. When the output voltage level of the external power supply connected to the external power input side matches the supply voltage level of the load connected to the external power output side, such as when the two are equal, the first positive terminal 21 and the negative terminal 23 can be controlled to be connected to the external power supply by closing the switch K1 and the switch K3, so that the DC power output by the external power supply can be directly input to the load for power supply through the first positive terminal 21 and the negative terminal 23, as well as the positive and negative poles of the DC side in the inverter. When the output voltage level of the external power supply does not match the supply voltage level of the load, the second positive terminal 22 and the negative terminal 23 can be controlled to connect to the external power supply by closing the switch K2 and the switch K3, and the inverter can be controlled to perform voltage conversion on the DC power input from the second positive terminal 22 and the negative terminal 23, and then the DC power after voltage conversion is input to the load through the positive and negative poles of the DC side of the inverter for power supply. For example: if the output voltage level of the external power supply is lower than the supply voltage level of the load, the inverter can be controlled to perform voltage boost conversion on the DC power. Figure 1 Cport in is the interface capacitance.

[0100] In this embodiment of the invention, the load connected to the output side of the external power supply may be a power battery of the vehicle, and the external power supply connected to the input side of the external power supply may be an external charging facility capable of charging the power battery. When the output voltage level of the external charging facility matches the charging voltage level of the power battery, the first positive terminal 21 and the negative terminal 23 are controlled to be connected to the external charging facility, and when the output voltage level of the external charging facility does not match the charging voltage level of the power battery, the second positive terminal 22 and the negative terminal 23 are controlled to be connected to the external charging facility. Further, when the highest output voltage level of the external charging facility is less than the highest charging voltage level of the power battery, the power battery 1, the voltage conversion device 2 and the charging port 3 can be controlled to form a charging loop by closing the switch K2 and the switch K3, and at the same time, all the upper bridge arms of the inverter in the voltage conversion device 2 are controlled to maintain the on state (that is, the power electronic devices Q1, Q3 and Q5 are controlled to maintain the on state), and all the lower bridge arms are controlled to maintain the off state (that is, the power electronic devices Q2, Q4 and Q6 are controlled to maintain the off state) to boost the electric energy input by the external charging facility through the charging port 3. The charging current inputted from the charging port 3 is inputted into the center tap of the stator winding through the second positive terminal 22, and then divided into three currents and inputted into each phase of the stator winding, and then inputted into the power battery 1 through the power electronic device in the upper bridge arm connected to each phase of the stator winding. Among them, one current is inputted into the A phase stator winding and then inputted into the power battery 1 through the power electronic device Q1, one current is inputted into the B phase stator winding and then inputted into the power battery 1 through the power electronic device Q3, and one current is inputted into the C phase stator winding and then inputted into the power battery 1 through the power electronic device Q5. In addition, in this embodiment, the voltage conversion device disclosed in the patent application with publication number CN112600411A can be used, and the specific structure and working principle of the voltage conversion device will not be described in detail here.

[0101] The above has completed the introduction of the vehicle charging system. Now, the charging control method of the vehicle charging system will be described.

[0102] See attached Figure 6 , Figure 6 FIG. 1 is a flow chart of the main steps of a charging control method for a vehicle charging system according to an embodiment of the present invention. The vehicle charging system may be the vehicle charging system described in the above embodiment. Figure 6 As shown, the charging control method of the vehicle charging system in the embodiment of the present invention mainly includes the following steps S101 to S103.

[0103] Step S101: When the output voltage level of the external charging facility connected to the charging port does not match the charging voltage level of the power battery, the power battery, the voltage conversion device and the charging port are controlled to form a charging loop.

[0104] Continue to refer to the attached Figure 5 When the output voltage level of the external charging facility connected to the charging port 3 does not match the charging voltage level of the power battery 1, the power battery 1, the voltage conversion device 2 and the charging port 3 can be controlled by closing the switch K2 and the switch K3 to form a charging circuit, so that the voltage conversion device 2 can perform voltage conversion on the electric energy input by the external charging facility through the charging port 3, so that the charging voltage matches the charging voltage level of the power battery 1.

[0105] Step S102: Control the external charging facility to charge the power battery via the charging circuit in a constant voltage charging mode.

[0106] The constant voltage charging mode refers to a mode in which an external charging facility is controlled to continuously output a certain voltage value to the vehicle charging system.

[0107] Step S103: During the charging process, one or more phases of the inverter are selectively controlled to convert the output voltage of the external charging facility according to the charging current input to the charging port, so that the DC component flowing through the stator winding in the voltage conversion device is maintained within a preset range, thereby reducing the iron loss of the motor.

[0108] During the charging process, the battery power of the power battery changes from low power to high power until it is fully charged. When the external charging facility is controlled to charge the power battery in a constant voltage charging mode, as the battery power of the power battery continues to increase, the charging current input to the charging port will continue to decrease. If the number of bridge arms of the inverter that performs voltage conversion on the output voltage of the external charging facility remains unchanged during the entire charging process, since the charging current input to the charging port will continue to decrease, the DC component flowing through the stator winding connected to the corresponding bridge arm will also continue to decrease. According to the analysis of the magnetic induction intensity, DC bias, magnetic permeability and iron loss of the asynchronous motor in the aforementioned invention content section, it can be seen that: if the DC component in the stator winding is smaller, the motor iron loss is greater, and the motor iron loss can be reduced by increasing the DC component in the stator winding. Based on the implementation described in the above steps S101 to S103, the principle that over-increasing the DC component in the stator winding can reduce the iron loss of the motor is utilized. When the electric drive system of the reused vehicle charges the power battery, the DC component flowing through the stator winding in the voltage conversion device is controlled to be maintained within a preset range, so that the magnetic permeability is maintained within a lower range, and the iron loss of the motor is also maintained within a lower range, thereby improving the charging efficiency of the power battery.

[0109] In addition, when the charging current of the charging port is large, the output voltage of the external charging facility can be transformed by simultaneously inputting the charging current into multiple-phase bridge arms, thereby avoiding the problem of using one-phase bridge arm causing a large current flowing through the stator winding connected to this phase bridge arm, thereby causing this phase stator winding to produce a large copper loss. When the charging current of the charging port is small, even if the charging current is fully input into one-phase bridge arm to transform the output voltage of the external charging facility, since the charging current is relatively small at this time, it will not cause the stator winding connected to this phase bridge arm to produce a large copper loss, thereby further improving the charging efficiency.

[0110] The above step S103 is further explained below.

[0111] In one implementation of the above step S103, when controlling the multi-phase bridge arm to perform voltage conversion on the output voltage of the external charging facility, the multi-phase bridge arm may be controlled by the following steps:

[0112] The multi-phase bridge arms are interleavedly controlled so as to reduce the ripple current generated by the stator winding in the voltage conversion device through the mutual inductance voltage formed by the multi-phase bridge arms during the interleaved control, thereby reducing the iron loss of the motor.

[0113] See attached Figure 7 , Figure 7 is the inductance electrical schematic diagram of the three-phase stator winding of an asynchronous motor, where A, B and C represent Figure 5 The A-phase stator winding, B-phase stator winding and C-phase stator winding in the vehicle charging system shown in FIG. Figure 7 As shown, the inductance of the A-phase stator winding includes the self-inductance L a , and the mutual inductance L formed by the B-phase stator winding ab , and the mutual inductance L formed by the C-phase stator winding ac ; The inductance of the B-phase stator winding includes the self-inductance L b , and the mutual inductance L formed by the A-phase stator winding ab , and the mutual inductance L formed by the C-phase stator winding bc ; The inductance of the C-phase stator winding includes the self-inductance L c , and the mutual inductance L formed by the B-phase stator winding bc , and the mutual inductance L formed by the A-phase stator winding ac .

[0114] The winding voltages of the A-phase stator winding, the B-phase stator winding, and the C-phase stator winding are expressed as follows (1):

[0115]

[0116] The meaning of each parameter in formula (1) is: V a 、V b and V cRespectively represent the winding voltages of the A-phase stator winding, the B-phase stator winding, and the C-phase stator winding, i a 、i b and i c Respectively represent the winding currents of the A-phase stator winding, the B-phase stator winding and the C-phase stator winding, and They represent the change rates of the winding currents of the A-phase stator winding, the B-phase stator winding, and the C-phase stator winding, respectively. Mutual inductance L ab The mutual inductance voltage, Mutual inductance L ac The mutual inductance voltage, Indicates L ac The mutual inductance voltage.

[0117] Taking the A-phase stator winding and the B-phase stator winding as an example, when i a rise i b decline When the mutual inductance voltage Greater than zero, V a increases, while V a Increase will inhibit i a Increases, thereby reducing the ripple current in the A-phase stator winding.

[0118] In one embodiment, when the three-phase bridge arms need to be interleaved, a 120° interleaved control method may be used to interleave the multi-phase bridge arms.

[0119] See attached Figure 8 , Figure 8 The control signals of the three-phase bridge arm when the 120° staggered control mode is adopted are shown as an example, wherein PWMA, PWMB and PWMC represent the control signals of the A-phase bridge arm, the B-phase bridge arm and the C-phase bridge arm respectively. The A-phase bridge arm, the B-phase bridge arm and the C-phase bridge arm are respectively connected to the attached Figure 5 The first phase bridge arm, the second phase bridge arm and the third phase bridge arm in the circuit correspond to each other. At this time, the winding voltages of the A-phase stator winding, the B-phase stator winding and the C-phase stator winding are shown in formula (1).

[0120] Continue to refer to the attached Figure 5Taking the A-phase bridge arm and the B-phase bridge arm as an example, when the level signals in PWMA and PWMB are both high-level signals for controlling the conduction of the lower bridge arms of the A-phase bridge arm and the B-phase bridge arm at a certain moment, the charging current output by the charging port 3 will enter the A-phase stator winding and the B-phase stator winding respectively through the second positive terminal 22. In one current flow path, the charging current flows through the A-phase stator winding, the power electronic device Q2 and the negative terminal 23 in sequence and flows back to the charging port 3. In another current flow path, the charging current flows through the B-phase stator winding, the power electronic device Q4 and the negative terminal 23 in sequence and flows back to the charging port 3. In the above process, the A-phase stator winding and the B-phase stator winding will store electrical energy. Assume that, at the next moment, the level signal in PWMA is still a high-level signal for controlling the conduction of the lower bridge arm of the A-phase bridge arm, but the level signal in PWMB becomes a low-level signal for controlling the shutdown of the lower bridge arm of the B-phase bridge arm. At this time, the charging current in the A-phase stator winding flows through the power electronic device Q2 and the charging current in the A-phase stator winding shows an upward trend, while the charging current in the B-phase stator winding flows into the power battery 1 through the diode reversely connected in parallel with the power electronic device Q3 and shows a downward trend.

[0121] According to the above embodiments, “when i a rise i b decline When the mutual inductance voltage Greater than zero, V a increases, while V a Increase will inhibit i a Therefore, during the period when the level signals in PWMA and PWMB are high level signals and low level signals respectively, the mutual inductance voltage generated by the A-phase stator winding and the B-phase stator winding increases, which can suppress the ripple current in the A-phase stator winding and the B-phase stator winding.

[0122] In one embodiment, when staggered control is required for two-phase bridge arms, a 180° staggered control method may be used to staggered control the multi-phase bridge arms.

[0123] See attached Fig. 9 , Fig. 9 The control signals of the two-phase bridge arms when the 180° staggered control mode is adopted are exemplarily shown, wherein PWMA, PWMB and PWMC represent the control signals of the A-phase bridge arm, the B-phase bridge arm and the C-phase bridge arm respectively.

[0124] Take the example of shutting off the A-phase bridge arm and performing staggered control on the B-phase bridge arm and the C-phase bridge arm. At this time, the winding voltages of the A-phase stator winding, the B-phase stator winding and the C-phase stator winding are as shown in the following formula (2):

[0125]

[0126] The principle of suppressing the ripple current in the stator winding by the 180° staggered control method is similar to the principle of suppressing the ripple current in the stator winding by the 120° staggered control method mentioned above, and will not be repeated here.

[0127] Furthermore, in another embodiment of the above step S103, the output voltage of the external charging facility can be converted by selectively controlling one or more phases of the inverter according to the charging current input to the charging port through the following steps:

[0128] If I r th1 , then control one phase bridge arm to convert the output voltage; if I th1 ≤I r ≤I th2 , then the two-phase bridge arm is controlled to convert the output voltage; if I r >I th2 , then the three-phase bridge arm is controlled to perform voltage conversion on the output voltage; where I th1 and I th2 Respectively represent the preset first current threshold and the second current threshold.

[0129] Through the above method, the output voltage of the multi-phase bridge arm to the external charging facility can be transformed when the charging current is large, and the output voltage of the single-phase bridge arm to the external charging facility can be transformed when the charging current is small, so that the magnitude of the charging current is positively correlated with the number of bridge arm controls, thereby ensuring that the DC component in each phase stator winding is maintained within a range that can make the magnetic permeability lower, thereby reducing the iron loss of the motor. For example, the A-phase bridge arm and the B-phase bridge arm can be staggered and the C-phase bridge arm can be turned off, so that the DC components in the A-phase stator winding and the B-phase stator winding are maintained within a range that can make the magnetic permeability lower.

[0130] It should be pointed out that although the various steps in the above embodiments are described in a specific order, those skilled in the art can understand that in order to achieve the effects of the present invention, different steps do not have to be performed in such an order. They can be performed simultaneously (in parallel) or in other orders. These changes are within the scope of protection of the present invention.

[0131] Furthermore, the present invention also provides a charging control device for a vehicle charging system.

[0132] See attached Fig.10 , Fig.10 ​It is a main structural block diagram of a charging control device of a vehicle charging system according to an embodiment of the present invention. In this embodiment, the vehicle charging system is the same as the vehicle charging system in the aforementioned method embodiment. For example, the vehicle may include a power battery and an electric drive system, the electric drive system may include an inverter and a motor, the DC side of the inverter is connected to the power battery, the AC side of the inverter is connected to the stator winding of the motor, the charging system may include a charging port and a voltage conversion device, the voltage conversion device may include an inverter, a stator winding, a first positive terminal, a second positive terminal and a negative terminal, the first positive terminal and the negative terminal are respectively connected to the positive and negative poles of the DC side, and the second positive terminal is connected to the center tap of the stator winding. For other technical details, please refer to the aforementioned method embodiment, which will not be repeated here.

[0133] like Fig.10 As shown, the charging control device of the vehicle charging system in the embodiment of the present invention mainly includes a first charging control module and a second charging control module. The first charging control module can be configured to control the power battery, the voltage conversion device and the charging port to form a charging circuit and control the external charging facility to charge the power battery through the charging circuit in a constant voltage charging mode when the output voltage level of the external charging facility connected to the charging port does not match the charging voltage level of the power battery. The second charging control module can be configured to selectively control one or more phases of the inverter to perform voltage conversion on the output voltage of the external charging facility according to the charging current input to the charging port during the charging process, so that the DC component flowing through the stator winding in the voltage conversion device is maintained within a preset range, thereby reducing the iron loss of the motor.

[0134] In one embodiment, the second charging control module may include an interleaving control submodule. In this embodiment, the interleaving control submodule may be configured to interleave the multiphase bridge arms when controlling the multiphase bridge arms to perform voltage conversion on the output voltage of the external charging facility, so as to reduce the ripple current generated by the stator winding in the voltage conversion device through the mutual inductance voltage formed by the multiphase bridge arms during the interleaving control, thereby reducing the iron loss of the motor.

[0135] In one embodiment, the interleaving control submodule may include a first interleaving control unit and a second interleaving control unit. In this embodiment, the first interleaving control unit may be configured to interleave the multi-phase bridge arms using a 180° interleaving control method when the number of the multi-phase bridge arms is two; the second interleaving control unit may be configured to interleave the multi-phase bridge arms using a 120° interleaving control method when the number of the multi-phase bridge arms is three.

[0136] In one embodiment, the first charging control module may include a first bridge arm control submodule, a second bridge arm control submodule and a third bridge arm control submodule. In this embodiment, the first bridge arm control submodule may be configured tor th1 The second bridge arm control submodule can be configured to control one phase bridge arm to perform voltage conversion on the output voltage at the same time; the second bridge arm control submodule can be configured to control one phase bridge arm to perform voltage conversion on the output voltage at the same time; th1 ≤I r ≤I th2 The third bridge arm control submodule can be configured to control the two-phase bridge arm to convert the output voltage at the same time; r >I th2 When the three-phase bridge arm is controlled, the output voltage is converted; where I th1 and I th2 Respectively represent the preset first current threshold and the second current threshold.

[0137] The charging control device of the vehicle charging system is used to execute Figure 6 The embodiment of the charging control method for the vehicle charging system shown in the figure has similar technical principles, technical problems solved and technical effects produced. Those skilled in the art can clearly understand that for the convenience and conciseness of description, the specific working process and related instructions of the charging control device of the vehicle charging system can refer to the contents described in the embodiment of the charging control method for the vehicle charging system, which will not be repeated here.

[0138] It is understood by those skilled in the art that the present invention implements all or part of the processes in the method of the above embodiment, and can also be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable storage medium may include: any entity or device, medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory, random access memory, electric carrier signal, telecommunication signal and software distribution medium that can carry the computer program code. It should be noted that the content contained in the computer-readable storage medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable storage media do not include electric carrier signals and telecommunication signals.

[0139] ​Furthermore, the present invention also provides a control device. In one embodiment of a control device according to the present invention, the control device includes a processor and a storage device, the storage device can be configured to store a program for executing the charging control method of the vehicle charging system of the above method embodiment, and the processor can be configured to execute the program in the storage device, which includes but is not limited to the program for executing the charging control method of the vehicle charging system of the above method embodiment. For ease of explanation, only the parts related to the embodiment of the present invention are shown. For specific technical details not disclosed, please refer to the method part of the embodiment of the present invention. The control device can be a control device device formed by various electronic devices.

[0140] Furthermore, the present invention also provides a computer-readable storage medium. In a computer-readable storage medium embodiment according to the present invention, the computer-readable storage medium may be configured to store a program for executing the charging control method of the vehicle charging system of the above-mentioned method embodiment, and the program may be loaded and run by the processor to implement the charging control method of the above-mentioned vehicle charging system. For ease of explanation, only the parts related to the embodiment of the present invention are shown. For specific technical details not disclosed, please refer to the method part of the embodiment of the present invention. The computer-readable storage medium may be a storage device formed by various electronic devices. Optionally, the computer-readable storage medium in the embodiment of the present invention is a non-temporary computer-readable storage medium.

[0141] Furthermore, the present invention also provides a vehicle. In a vehicle embodiment according to the present invention, the vehicle may include a power battery and an electric drive system, the electric drive system may include an inverter and a motor, the DC side of the inverter is connected to the power battery, and the AC side of the inverter is connected to the stator winding of the motor. In addition, the vehicle may also include the charging control device of the vehicle charging system described in the aforementioned device embodiment or the control device described in the aforementioned device embodiment. For ease of explanation, only the parts related to the embodiments of the present invention are shown. For specific technical details not disclosed, please refer to the device part of the embodiments of the present invention.

[0142] Further, it should be understood that since the setting of each module is only for illustrating the functional units of the device of the present invention, the physical devices corresponding to these modules may be the processor itself, or a part of the software in the processor, a part of the hardware, or a part of the combination of software and hardware. Therefore, the number of each module in the figure is only schematic.

[0143] Those skilled in the art will appreciate that the modules in the device can be adaptively split or merged. Such splitting or merging of specific modules will not cause the technical solution to deviate from the principle of the present invention, and therefore, the technical solutions after splitting or merging will fall within the protection scope of the present invention.

[0144] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A charging control method for a vehicle charging system, wherein the vehicle comprises a power battery and an electric drive system, wherein the electric drive system comprises an inverter and a motor, wherein a DC side of the inverter is connected to the power battery, and an AC side of the inverter is connected to a stator winding of the motor, wherein the charging system comprises a charging port and a voltage conversion device, wherein the voltage conversion device comprises the inverter, the stator winding, a first positive terminal, a second positive terminal and a negative terminal, wherein the first positive terminal and the negative terminal are respectively connected to a positive pole and a negative pole of the DC side, and the second positive terminal is connected to a center tap of the stator winding, It is characterized in that The charging control method comprises: When the output voltage level of the external charging facility connected to the charging port does not match the charging voltage level of the power battery, control the power battery, the voltage conversion device and the charging port to form a charging loop and control the external charging facility to charge the power battery through the charging loop in a constant voltage charging mode; During the charging process, one or more phases of the inverter are selectively controlled to convert the output voltage of the external charging facility according to the charging current input to the charging port, so that the DC component flowing through the stator winding in the voltage conversion device is maintained within a preset range, thereby reducing the iron loss of the motor.

2. The charging control method of the vehicle charging system according to claim 1, characterized in that: When controlling the multi-phase bridge arm to perform voltage conversion on the output voltage of the external charging facility, the method further includes: The multi-phase bridge arms are interleavedly controlled so as to reduce the ripple current generated by the stator winding in the voltage conversion device through the mutual inductance voltage formed by the multi-phase bridge arms during the interleaved control, thereby reducing the iron loss of the motor.

3. The charging control method of the vehicle charging system according to claim 2, characterized in that: The step of "interleaving control of the multi-phase bridge arms" specifically includes: If the number of the multi-phase bridge arms is two, the multi-phase bridge arms are staggered controlled by adopting a 180° staggered control method; If the number of the multi-phase bridge arms is three, the multi-phase bridge arms are interlaced controlled by adopting a 120° interlaced control method.

4. The charging control method of the vehicle charging system according to claim 1, characterized in that: The step of "selectively controlling one or more phases of the inverter to convert the output voltage of the external charging facility according to the charging current input to the charging port" specifically includes: If I r th1 , then controlling a phase bridge arm to perform voltage conversion on the output voltage;​ If I th1 ≤I r ≤I th2 , then control the two-phase bridge arm to perform voltage conversion on the output voltage; If I r >I th2 , then control the three-phase bridge arm to perform voltage conversion on the output voltage; Among them, I th1 and I th2 Respectively represent the preset first current threshold and the second current threshold.

5. A charging control device for a vehicle charging system, the vehicle comprising a power battery and an electric drive system, the electric drive system comprising an inverter and a motor, the DC side of the inverter being connected to the power battery, the AC side of the inverter being connected to the stator winding of the motor, the charging system comprising a charging port and a voltage conversion device, the voltage conversion device comprising the inverter, the stator winding, a first positive terminal, a second positive terminal and a negative terminal, the first positive terminal and the negative terminal being connected to the positive and negative poles of the DC side, respectively, the second positive terminal being connected to the center tap of the stator winding, It is characterized in that The charging control device comprises: a first charging control module, configured to control the power battery, the voltage conversion device and the charging port to form a charging loop and control the external charging facility to charge the power battery through the charging loop in a constant voltage charging mode when the output voltage level of the external charging facility connected to the charging port does not match the charging voltage level of the power battery; The second charging control module is configured to selectively control one or more phases of the inverter to perform voltage conversion on the output voltage of the external charging facility according to the charging current input to the charging port during the charging process, so that the DC component flowing through the stator winding in the voltage conversion device is maintained within a preset range, thereby reducing the iron loss of the motor.

6. The charging control device of the vehicle charging system according to claim 5, characterized in that: The second charging control module includes an interleaving control submodule, which is configured to perform interleaving control on the multi-phase bridge arm when controlling the multi-phase bridge arm to perform voltage conversion on the output voltage of the external charging facility, so as to reduce the ripple current generated by the stator winding in the voltage conversion device through the mutual inductance voltage formed by the multi-phase bridge arm during interleaving control, thereby reducing the iron loss of the motor.

7. The charging control device of the vehicle charging system according to claim 6, characterized in that: The interleaving control submodule includes a first interleaving control unit and a second interleaving control unit; The first interleaving control unit is configured to interleave the multi-phase bridge arms using a 180° interleaving control method when the number of the multi-phase bridge arms is two; The second interleaving control unit is configured to perform interleaving control on the multi-phase bridge arms by adopting a 120° interleaving control method when the number of the multi-phase bridge arms is three.

8. The charging control device of the vehicle charging system according to claim 5, characterized in that: The first charging control module includes a first bridge arm control submodule, a second bridge arm control submodule and a third bridge arm control submodule; The first bridge arm control submodule is configured to r th1 When controlling a phase bridge arm to perform voltage conversion on the output voltage;​ The second bridge arm control submodule is configured to th1 ≤I r ≤I th2 Controlling the two-phase bridge arms to perform voltage conversion on the output voltage; The third bridge arm control submodule is configured to r >I th2 Controlling the three-phase bridge arm to perform voltage conversion on the output voltage; Among them, I th1 and I th2 Respectively represent the preset first current threshold and the second current threshold.

9. A control device, comprising a processor and a storage device, wherein the storage device is suitable for storing a plurality of program codes, characterized in that: The program code is suitable for being loaded and run by the processor to execute the charging control method of the vehicle charging system according to any one of claims 1 to 4.

10. A computer-readable storage medium storing a plurality of program codes, characterized in that: The program code is suitable for being loaded and run by a processor to execute the charging control method of the vehicle charging system according to any one of claims 1 to 4.

11. A vehicle, comprising a power battery and an electric drive system, wherein the electric drive system comprises an inverter and a motor, wherein the DC side of the inverter is connected to the power battery, and the AC side of the inverter is connected to the stator winding of the motor, wherein: The vehicle further includes the charging control device of the vehicle charging system according to any one of claims 5 to 8 or the control device according to claim 9.

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