A powertrain, charging control method and electric vehicle

Abstract

The present application provides a powertrain, a charging control method and an electric vehicle, wherein the powertrain is arranged between a DC power supply and a power battery, and includes a motor controller and a motor, wherein the motor controller includes three bridge arms and a controller, wherein the first end of the DC power supply is coupled to one end of each of the three bridge arms and the first end of the power battery, and the second end of the power battery is coupled to the other end of each bridge arm; the midpoint of each bridge arm is coupled to one end of the motor winding corresponding to each bridge arm; the other end of each of the three motor windings is coupled to the second end of the DC power supply, and the three bridge arms include a first bridge arm and a second bridge arm; the first bridge arm is turned on or off according to a first PWM signal, and the second bridge arm is turned on or off according to a second PWM signal; the first PWM signal is interlaced with the second PWM signal. The implementation of the present application can ensure that the heating of the magnetic steel in the motor is within a safe range, and reduce the ripple of the output current of the powertrain.

Description

Technical Field

[0001] The present application relates to the field of new energy vehicle technology, and in particular to a powertrain, a charging control method, and an electric vehicle. Background Art

[0002] The output voltage of some charging piles currently on the market is 220V to 500V. In order to solve the problem of slow charging speed of electric vehicles, the voltage of the power batteries equipped on electric vehicles is relatively high, such as 600V to 800V. When the voltage of the power battery on the electric vehicle is 600V, the charging pile that can only output 220V to 500V cannot charge the electric vehicle. Therefore, in order to adapt to some charging piles in the existing market, the bridge arm and motor winding used to drive the motor in the electric vehicle can be reused to boost the voltage output by the charging pile, and the boosted voltage can be provided to the power battery. Then, how to specifically control the conduction or shutdown of the bridge arm is the current key research issue. Summary of the invention

[0003] The present application provides a powertrain, a charging control method and an electric vehicle, which can ensure that the heating of the magnetic steel in the motor is within a safe range and reduce the ripple of the output current of the powertrain.

[0004] In the first aspect, an embodiment of the present application provides a powertrain, which is arranged between a DC power supply and a power battery, and includes a motor controller (MCU) and a motor, wherein the MCU includes three bridge arms and a controller, and the motor includes three motor windings corresponding to the three bridge arms. In a specific implementation, the first end of the DC power supply is coupled to one end of each of the three bridge arms and the first end of the power battery, and the second end of the power battery is coupled to the other end of each bridge arm; the midpoint of each bridge arm is coupled to one end of the motor winding corresponding to each bridge arm; and the other end of each of the three motor windings is coupled to the second end of the DC power supply. Furthermore, the three bridge arms include a first bridge arm and a second bridge arm; the first bridge arm can be turned on or off according to a first pulse width modulation (PWM) signal sent by the controller, and the second bridge arm can be turned on or off according to a second PWM signal sent by the controller; the first PWM signal and the second PWM signal are interlaced, that is, the rising edge of the second PWM signal lags behind the rising edge of the first PWM signal by a first preset time; or, the falling edge of the second PWM signal lags behind the falling edge of the first PWM signal by a second preset time. The embodiment of the present application balances the heat generated by the motor magnet and the ripple of the output current of the powertrain by controlling the interlacing of the first PWM signal and the second PWM signal, thereby ensuring that the heat generated by the magnet in the motor is within a safe range and reducing the ripple of the output current of the powertrain.

[0005] In combination with the first aspect, in a first possible implementation, the three bridge arms further include a third bridge arm, which can be turned on or off according to a third PWM signal. The rising edge of the third PWM signal lags behind the rising edge of the second PWM signal by a third preset time; or the falling edge of the third PWM signal lags behind the falling edge of the second PWM signal by a fourth preset time. The embodiment of the present application specifically implements three-phase interleaving, that is, none of the three bridge arms are turned on or off at the same time. The embodiment of the present application can also ensure that the heating of the magnetic steel in the motor is within a safe range and reduce the ripple of the output current of the powertrain.

[0006] In combination with the first possible implementation of the first aspect, in a second possible implementation, the cycle time of the first PWM signal is T; wherein the first preset time and the third preset time are T / 3; or, the second preset time and the fourth preset time are T / 3. The three-phase staggered 120° control method adopted in the embodiment of the present application is more in line with the control habits of the motor, and can also ensure that the heating of the magnetic steel in the motor is within a safe range and reduce the ripple of the output current of the powertrain.

[0007] In combination with the first aspect, in a third possible implementation, the three bridge arms further include a third bridge arm, and the third bridge arm can be turned on or off according to a third PWM signal. The rising edge of the third PWM signal appears simultaneously with the rising edge of the first PWM signal; and the falling edge of the third PWM signal appears simultaneously with the falling edge of the first PWM signal.

[0008] In combination with the third possible implementation of the first aspect, in a fourth possible implementation, the cycle time of the first PWM signal is T; wherein the first preset time is T / 2; or the second preset time is T / 2.

[0009] In combination with any one of the possible implementations of the first aspect, in a fifth possible implementation, the first PWM signal, the second PWM signal, and the third PWM signal have equal cycle times and the same duty cycles.

[0010] In combination with the first aspect or any one of the possible implementations of the first aspect, in a sixth possible implementation, the power assembly further includes a first switch and a second switch, wherein one end of the first switch is coupled to a midpoint of any one of the three bridge arms.

[0011] The other end of each of the three motor windings is coupled to the second end of the DC power supply, which is specifically implemented as follows: the other end of each of the three motor windings is coupled to one end of the second switching switch, and the other end of the second switching switch and the other end of the first switching switch are coupled to the second end of the DC power supply.

[0012] In combination with the sixth possible implementation of the first aspect, in a seventh possible implementation, when the difference between the voltage of the power battery and the voltage of the DC power supply is less than a first preset threshold, the first switching switch is turned off and the second switching switch is turned on.

[0013] In combination with the sixth possible implementation method of the first aspect, in an eighth possible implementation method, when the difference between the power battery voltage and the DC power supply voltage is greater than or equal to the first preset threshold, the first switching switch is turned on and the second switching switch is turned off.

[0014] The first bridge arm is used to be turned on or off according to a first pulse width modulation (PWM) signal, and the second bridge arm is used to be turned on or off according to a second PWM signal, which is specifically implemented as follows:

[0015] The other two bridge arms among the above three bridge arms except any bridge arm coupled to the first switch are used to be turned on or off according to the fourth PWM signal and the fifth PWM signal respectively.

[0016] In combination with the sixth possible implementation of the first aspect, in a ninth possible implementation, the powertrain further includes an inductor. The other end of the second switch and the other end of the first switch are coupled to the second end of the DC power supply, which is specifically implemented as follows: the other end of the second switch and the other end of the first switch are coupled to one end of the inductor, and the other end of the inductor is coupled to the second end of the DC power supply.

[0017] In the second aspect, an embodiment of the present application provides a charging control method, which is used in a powertrain, which includes a motor controller Unit (MCU) and a motor; wherein the MCU includes three bridge arms and a controller, and the motor includes three motor windings corresponding to the three bridge arms. In a specific implementation, the first end of the DC power supply is coupled to one end of each of the three bridge arms and the first end of the power battery, and the second end of the power battery is coupled to the other end of each bridge arm; the midpoint of each bridge arm is coupled to one end of the motor winding corresponding to each bridge arm; the other end of each of the three motor windings is coupled to the second end of the DC power supply. Furthermore, the three bridge arms include a first bridge arm and a second bridge arm;

[0018] The charging control method is specifically implemented as follows: the controller sends a first pulse width modulation (PWM) signal to the first bridge arm and sends a second PWM signal to the second bridge arm; the first PWM signal and the second PWM signal are staggered, that is, the rising edge of the second PWM signal lags behind the rising edge of the first PWM signal by a first preset time; or, the falling edge of the second PWM signal lags behind the falling edge of the first PWM signal by a second preset time.

[0019] In combination with the second aspect, in a first possible implementation, the three bridge arms further include a third bridge arm, and the charging control method further includes: the controller sends a third PWM signal to the third bridge arm. The rising edge of the third PWM signal lags behind the rising edge of the second PWM signal by a third preset time; or the falling edge of the third PWM signal lags behind the falling edge of the second PWM signal by a fourth preset time.

[0020] In combination with the first possible implementation method of the second aspect, in a second possible implementation method, the cycle time of the above-mentioned first PWM signal is T; wherein the first preset time and the third preset time are T / 3; or, the second preset time and the fourth preset time are T / 3.

[0021] In combination with the second aspect, in a third possible implementation, the three bridge arms further include a third bridge arm, and the charging control method further includes: the controller sends a third PWM signal to the third bridge arm. The rising edge of the third PWM signal appears at the same time as the rising edge of the first PWM signal; and the falling edge of the third PWM signal appears at the same time as the falling edge of the first PWM signal.

[0022] In combination with the third possible implementation of the second aspect, in a fourth possible implementation, the cycle time of the first PWM signal is T; wherein the first preset time is T / 2; or the second preset time is T / 2.

[0023] In combination with any one of the possible implementations of the second aspect, in a fifth possible implementation, the cycle times of the first PWM signal, the second PWM signal, and the third PWM signal are equal, and their duty cycles are the same.

[0024] In combination with the second aspect or any one of the above possible implementations of the second aspect, in a sixth possible implementation, the power assembly further includes a first switching switch and a second switching switch.

[0025] The charging control method further includes:

[0026] When the difference between the voltage of the power battery and the voltage of the DC power supply is less than the first preset threshold, the controller controls the first switch to be turned off, and controls the second switch to be turned on. One end of the first switch is coupled to the midpoint of any bridge arm of the three bridge arms, and the other end of the first switch is coupled to the second end of the DC power supply. One end of the second switch is coupled to the other end of each motor winding of the three motor windings, and the other end of the second switch is coupled to the second end of the DC power supply.

[0027] In combination with the sixth possible implementation of the second aspect, in an eighth possible implementation, when the difference between the power battery voltage and the DC power supply voltage is greater than or equal to the first preset threshold, the controller controls the first switch to be turned on and the second switch to be turned off. In addition, the controller further sends a fourth PWM signal and a fifth PWM signal to the other two bridge arms of the three bridge arms except any bridge arm coupled to the first switch, respectively.

[0028] In a third aspect, an embodiment of the present application provides an electric vehicle, comprising a power battery and a powertrain in combination with the first aspect or in combination with any one of the above possible implementations of the first aspect.

[0029] It should be understood that the implementation and beneficial effects of the above-mentioned aspects of the present application can be referenced to each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A schematic diagram of a structure of a powertrain provided in an embodiment of the present application;

[0031] Figure 2 A schematic diagram of a charging scenario of an electric vehicle provided in an embodiment of the present application;

[0032] Figure 3 A schematic diagram of a structure of a powertrain provided in an embodiment of the present application;

[0033] Figure 4 A waveform diagram provided for an embodiment of the present application;

[0034] Figure 5 Another waveform diagram provided for an embodiment of the present application;

[0035] Figure 6 Another waveform diagram provided for an embodiment of the present application;

[0036] Fig. 7A and Figure 7B A current ripple schematic diagram provided in an embodiment of the present application;

[0037] Figure 8 Another waveform diagram provided for an embodiment of the present application;

[0038] Fig. 9 Another structural schematic diagram of a powertrain provided in an embodiment of the present application;

[0039] Fig.10 Another structural schematic diagram of a powertrain provided in an embodiment of the present application;

[0040] FIG. 11A to FIG. 11F A schematic diagram of a circuit state of a powertrain provided in an embodiment of the present application;

[0041] FIG. 12A to FIG. 12B A schematic diagram of another circuit state of a powertrain provided in an embodiment of the present application;

[0042] FIG. 13A to FIG. 13B A schematic diagram of another circuit state of a powertrain provided in an embodiment of the present application;

[0043] FIG. 14A to FIG. 14B Another circuit state schematic diagram of a powertrain provided in an embodiment of the present application. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0045] The implementation of the technical solution of the present application is further described in detail below in conjunction with the accompanying drawings.

[0046] See also Figure 1 , Figure 1 A schematic diagram of the structure of a powertrain provided in an embodiment of the present application. Figure 1 As shown, the powertrain 10 includes a motor controller Unit (MCU) 101 and a motor 102 .

[0047] The MCU 101 includes three bridge arms and a controller, wherein the controller can send pulse width modulation (PWM) signals to the three bridge arms, and the three bridge arms can be turned on or off respectively according to the PWM signals received by each.

[0048] Exemplarily, the controller can be specifically implemented as a central processing unit (CPU), other general-purpose processors, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.

[0049] In some feasible implementations, the three bridge arms and the controller are welded on the same printed circuit board (PCB) or on different PCBs. The PCB can be specifically placed inside a hardware box, which is located on top of the motor.

[0050] The powertrain 10 can be integrated into a whole and placed in an electric vehicle, so that Figure 2 The schematic diagram of the charging scenario of an electric vehicle is shown in FIG. Figure 2 As shown, the electric vehicle 20 includes a power battery 203 and Figure 1 The powertrain 10 is shown in FIG.

[0051] The power battery 203 is connected to the DC power supply through the power assembly 10. Figure 2 In the example, the DC power source is used as the charging pile 21. In some other feasible implementations, the DC power source can be specifically implemented as another electric vehicle (not shown in the figure).

[0052] The specific structure of the powertrain provided in the embodiment of the present application is described below with reference to the accompanying drawings.

[0053] In some possible implementations, see Figure 3 , Figure 3 A schematic diagram of the structure of a powertrain provided in an embodiment of the present application. Figure 3 As shown, the power assembly 10A is disposed between the DC power supply 301 and the power battery 303 , and the power assembly 10A includes an MCU and a motor M3 .

[0054] Among them, the MCU includes three bridge arms and a controller (not shown in the figure), and the three bridge arms include a first bridge arm, a second bridge arm and a third bridge arm. It should be noted that each bridge arm may include two switch units connected in series, and the switch unit may include at least one switch connected in series or in parallel. In specific practice, the switch unit may select multiple switches in series or in parallel according to the voltage and current in the power supply module. Among them, the switch can be specifically implemented as an insulated gate bipolar transistor (IGBT) and its anti-parallel diode, or a metal oxide semiconductor field effect transistor (MOSFET), etc. In general, the embodiments of the present application do not limit the type of switches and the number of switches in the switch unit.

[0055] For example, the switch included in the bridge arm is specifically implemented as an IGBT and its anti-parallel diode. Figure 3 As shown, the first bridge arm includes a switch tube Q 31 And the switch tube Q 31 The series switch tube Q 32 The second bridge arm includes the switch tube Q 33 And the switch tube Q 33 The series switch tube Q 34 The third bridge arm includes the switch tube Q 35 And the switch tube Q 35 The series switch tube Q 36 .

[0056] It should be explained that the first bridge arm, the second bridge arm and the third bridge arm can be interchanged. For example, the first bridge arm includes a switch tube Q 33 And the switch tube Q33 The series switch tube Q 34 The second bridge arm includes the switch tube Q 35 And the switch tube Q 35 The series switch tube Q 36 The third bridge arm includes the switch tube Q 31 And the switch tube Q 31 The series switch tube Q 32 .

[0057] In a specific implementation, the first end of the DC power supply 301 is coupled to one end of each bridge arm and the first end of the power battery 303. Figure 3 The first end of the DC power supply 301 shown in the figure is the positive terminal, the second end of the DC power supply 301 is the negative terminal, the first end of the power battery 303 is the positive terminal, and the second end of the power battery 303 is the negative terminal.

[0058] Then the positive terminal of the DC power supply 301 is coupled to the switch tube Q 31 The collector of the switch tube Q 33 The collector of the switch tube Q 35 The collector of the power battery 303 and the positive terminal of the power battery 303. The negative terminal of the power battery 303 is coupled to the switch tube Q 32 The emitter of the switch tube Q 34 The emitter and switch tube Q 36 of the emitter.

[0059] It should be noted that the "coupling" described in this application refers to direct or indirect connection. For example, the coupling between A and B can be either a direct connection between A and B or an indirect connection between A and B through one or more other electrical components. For example, A can be directly connected to C, and C can be directly connected to B, so that A and B are connected through C. For example, the DC power supply 301 can be connected to the switch tube Q through a switch. 31 The collector of the switch tube Q 33 The collector of the switch tube Q 35 The collector and the positive terminal of the power battery 303.

[0060] The midpoint of each bridge arm is coupled to one end of the motor winding corresponding to each bridge arm, and the midpoint of each bridge arm is the series coupling point between two series switch units. 31 The emitter and switch tube Q 32 The collector coupling of the motor winding N U3 One end of the switch tube Q 33 The emitter and switch tube Q 34 The collector coupling of the motor winding N V3 One end of the switch tube Q 35 The emitter and switch tube Q36 The collector coupling of the motor winding N W3 one end.

[0061] Motor winding N U3 The other end of the motor winding N V3 The other end of the motor winding N W3 The other end is coupled to the negative end of the DC power supply 301.

[0062] Optionally, in some feasible implementations, the first end of the DC power supply may be a negative terminal, the second end of the DC power supply may be a positive terminal, the first end of the power battery may be a negative terminal, and the second end of the power battery may be a positive terminal (not shown in the figure). Then the positive terminal of the DC power supply is coupled to the other end of each motor winding, and the negative terminal of the DC power supply is coupled to the other end of each bridge arm.

[0063] The following is an exemplary description of how to specifically control the powertrain provided by the present application in conjunction with the accompanying drawings.

[0064] In some possible implementations, see Figure 4 , Figure 4 A waveform diagram provided in an embodiment of the present application. Figure 4 As shown, the controller can switch Q 31 Send PWM1 signal and switch Q 33 Send PWM2 signal. At this time, the rising edge of PWM1 signal is, for example, at t 41 At the moment, the rising edge of the PWM2 signal is, for example, at t 42 At this moment, the interlacing of PWM1 signal and PWM2 signal is specifically manifested as: 42 Time lag t 41 Moment first preset time.

[0065] The first preset time is preset, and the length of the first preset time is related to the ripple of the output current of the powertrain and the heat generated by the magnetic steel in the motor. The setting of the first preset time can be adjusted according to specific practical applications, that is, the embodiment of the present application does not limit the length of the first preset time.

[0066] Of course, the staggering of the PWM1 signal and the PWM2 signal can also be that the falling edge of the PWM1 signal is staggered with the falling edge of the PWM2 signal. For example, the falling edge of the PWM2 signal lags behind the falling edge of the PWM1 signal by a second preset time. Similarly, the second preset time is pre-set, and the length of the second preset time is related to the ripple size of the output current of the powertrain and the heat generated by the magnetic steel in the motor. The setting of the second preset time can also be adjusted according to specific practical applications, that is, the embodiment of the present application does not limit the length of the second preset time.

[0067] It should be noted that, in specific practical applications, the rising edge or falling edge of the PWM1 signal and the PWM2 signal can be set, that is, the first preset time or the second preset time can be pre-set to achieve the interleaving of the PWM1 signal and the PWM2 signal. Alternatively, the rising edge and the falling edge of the PWM1 signal and the PWM2 signal can be set at the same time, that is, the first preset time and the second preset time can be pre-set to achieve the interleaving of the PWM1 signal and the PWM2 signal.

[0068] For example, Figure 4 The controller sends the switch Q 35 For example, when sending a PWM3 signal, the rising edge of the PWM3 signal is at t 41 Moment, that is, the rising edge of the PWM3 signal and the rising edge of the PWM1 signal appear at the same time.

[0069] It can be understood that the signals sent by the controller to the two switch units in the same switch bridge arm are complementary. 32 The signal sent is complementary to the PWM1 signal and is sent to the switch tube Q 34 The signal sent is complementary to the PWM2 signal and is sent to the switch tube Q 36 The signal sent is complementary to the PWM3 signal. At this time, in the embodiment of the present application, the control switch tube Q 31 The PWM1 signal can be called the first PWM signal, which controls the switch tube Q 33 The PWM2 signal can be called a second PWM signal.

[0070] Relative to the switch tube Q 31 And the switch tube Q 33 At the same time, the motor winding N U3 and motor winding N V3 In parallel, the inductance in the powertrain is reduced, resulting in an increase in the ripple of the output current of the powertrain. In the embodiment of the present application, the controller controls the first bridge arm (i.e., the switch tube Q 31 ) and controls the first PWM signal of the second bridge arm (i.e., the switch tube Q 33 ) are interlaced, so that the switch tube Q 33 Lagging behind the switch tube Q 31 Conducting, the motor winding N in the powertrain U3 and motor winding N V3 The parallel connection time becomes shorter, and even the motor winding N U3 and motor winding N V3 It is not necessary to connect them in parallel. At this time, the inductance in the powertrain is greater than the switch tube Q 31 And the switch tube Q 33At the same time, the inductance that is turned on is large, and the ripple of the output current of the powertrain is small.

[0071] In general, the embodiments of the present application strike a balance between the amount of heat generated by the motor magnets and the amount of ripple in the output current of the powertrain, which can ensure that the heat generated by the motor magnets is within a safe range and reduce the ripple in the output current of the powertrain.

[0072] Optionally, in some possible implementations, see Figure 5 , Figure 5 Another waveform diagram provided in the embodiment of the present application. Figure 5 As shown, the controller can switch Q 31 Send PWM1' signal to switch tube Q 33 Send PWM2' signal and switch Q 35 Send PWM3' signal. At this time, the rising edge of PWM1' signal is, for example, at t 51 At the moment, the rising edge of the PWM2′ signal is, for example, at t 52 At the moment, the rising edge of the PWM3′ signal is, for example, at t 53 time.

[0073] Then the PWM1′ signal, PWM2′ signal and PWM3′ signal are interlaced with each other as follows: 52 Time lag t 51 The first preset time, t 53 Time lag t 52 The third preset time is also preset. The length of the third preset time is also related to the ripple size of the output current of the powertrain and the heat generated by the magnetic steel in the motor. The setting of the third preset time can be adjusted according to specific practical applications, that is, the embodiment of the present application does not limit the length of the third preset time.

[0074] Of course, the interlacing of PWM1′ signal, PWM2 signal and PWM3′ signal can also be specifically manifested as: the falling edge of PWM2′ signal lags behind the falling edge of PWM1′ signal by a second preset time, and the falling edge of PWM3′ signal lags behind the falling edge of PWM2′ signal by a fourth preset time. Similarly, the fourth preset time is pre-set, and the fourth preset time is related to the ripple size of the output current of the powertrain and the heat generated by the magnetic steel in the motor. The setting of the fourth preset time can also be adjusted according to specific practical applications, that is, the embodiment of the present application does not limit the length of the fourth preset time.

[0075] It should be noted that, in specific practical applications, the rising edge or falling edge of the PWM1′ signal, PWM2′ signal and PWM3′ signal can be set, that is, the first preset time and the third preset time are pre-set to achieve the interleaving of the PWM1′ signal, PWM2′ signal and PWM3′ signal. Alternatively, the second preset time and the fourth preset time are pre-set to achieve the interleaving of the PWM1′ signal, PWM2′ signal and PWM3′ signal. Alternatively, the rising edge and the falling edge of the PWM1′ signal, PWM2′ signal and PWM3′ signal can be set at the same time, that is, the first preset time, the second preset time, the third preset time and the fourth preset time are pre-set to achieve the interleaving of the PWM1′ signal, PWM2′ signal and PWM3′ signal.

[0076] The waveform diagram shown in the embodiment of the present application specifically implements three-phase interleaving, that is, the switch tubes in the three bridge arms are not turned on at the same time, for example, the switch tube Q 33 Lagging behind the switch tube Q 31 Turn on, switch tube Q 35 Lagging behind the switch tube Q 33 Relative use Figure 4 The waveform diagram shown in the figure is used to control the three bridge arms. The inductance of the powertrain controlled by the embodiment of the present application is larger, and the ripple of the output current of the powertrain is smaller, but the heat generated by the magnetic steel of the motor is also greater. In general, the embodiment of the present application can also ensure that the heat generated by the magnetic steel in the motor is within a safe range and reduce the ripple of the output current of the powertrain.

[0077] Optionally, in some possible implementations, see Figure 6 , Figure 6 Another waveform diagram provided in the embodiment of the present application. Figure 6 As shown, the controller can switch Q 31 Send PWM1" signal to switch tube Q 33 Send PWM2" signal and switch Q 35 Send PWM3″ signal. At this time, the rising edge of PWM1″ signal is, for example, at t 61 At this moment, the corresponding falling edge is at t 62 Moment; the rising edge of the PWM2" signal is, for example, at t 63 At this moment, the corresponding falling edge is at t 64 Moment; the rising edge of the PWM3 "signal is, for example, at t 65 At this moment, the corresponding falling edge is at t 66 The next rising edge of the PWM1″ signal is at t 67 At this moment, the cycle time of the PWM1″ signal is t 67 Time and t 61The time difference between the instants (e.g. T).

[0078] Among them, the PWM1″ signal, PWM2″ signal and PWM3″ signal are interlaced with each other as follows: 63 Time lag t 61 The first preset time, t 65 Time lag t 63 The third preset time. Figure 5 In the waveform diagram shown in FIG. 1 , in the embodiment of the present application, the first preset time is equal to the third preset time, and both are T / 3. At this time, the three phases of the three bridge arms are staggered by 120°.

[0079] Of course, the interleaving of the PWM1″ signal, the PWM2″ signal and the PWM3″ signal can also be specifically expressed as: the falling edge of the PWM2″ signal lags behind the falling edge of the PWM1″ signal by a second preset time, and the falling edge of the PWM3″ signal lags behind the falling edge of the PWM2″ signal by a fourth preset time. At this time, the second preset time is equal to the fourth preset time, and both are T / 3.

[0080] The waveform diagram shown in the embodiment of the present application specifically implements the three-phase staggered 120°, that is, the switch tubes in the three bridge arms are not turned on at the same time, for example, the switch tube Q 33 On-state ratio switch tube Q 31 Turn-on hysteresis T / 3, switch tube Q 35 On-state ratio switch tube Q 33 The conduction is also delayed by T / 3. Figure 5 The waveform diagram shown in FIG. 1 is used to control the three bridge arms. The three-phase staggered 120° control method adopted in the embodiment of the present application is more in line with the control habits of the motor, and the embodiment of the present application can also be implemented as follows: Figure 5 The technical effect described.

[0081] At this time, the ripple diagram of the output current of the powertrain can be seen in Fig. 7A .like Fig. 7A As shown, the motor winding N U3 The current is I U3 , motor winding N V3 The current is I V3 , motor winding N W3 The current is I W3 Among them, when the three phases of the three bridge arms are staggered by 120°, the current I U3 ,I V3 and I W3 Also staggered 120°, then at any t 71 At this moment, the output current I O is the current I U3 ,IV3 and I W3 For example, if the ripple amplitude of the current on each motor winding is 65A, the output current I of the powertrain is O The ripple amplitude can be 20A. It can be understood that Fig. 7A From the ripple diagram shown in FIG. 1 , it can be seen that the ripple currents of the three motor windings are staggered, and the peak values ​​of the ripples of the motor windings can be staggered. For example, the motor winding N U3 When the ripple current is large, the motor winding N V3 The ripple current of the motor winding N W3 The ripple current is smaller, so that the ripple of the output current of the powertrain is smaller than the current ripple on any motor winding.

[0082] Assuming that the signals of the three bridge arms are synchronized, the current I U3 ,I V3 and I W3 Also synchronously, the peak values ​​of the ripples of the motor windings appear at the same time, so the ripple amplitude of the output current of the powertrain is 3×65=195 A. At this time, the ripple of the output current of the powertrain is large.

[0083] In order to illustrate the influence of the three-phase staggered control method at different angles on the ripple size of the output current of the powertrain, the present application also provides Figure 7B The ripple diagram shown in Figure 7B The current ripple diagram shown in FIG. 1 is that the controller uses a three-phase staggered 60° control method to control the three bridge arms, that is, the first preset time is equal to the third preset time, and is T / 6. At this time, if Figure 7B As shown, the motor winding N U3 The current is I U3 ', motor winding N V3 The current is I V3 ', motor winding N W3 The current is I W3 ′. Then at any t 81 At this moment, the output current I O ′ is the current I U3 ′、I V3 ' and I W3 For example, if the ripple amplitude of the current on each motor winding is 65A, the output current I O The ripple amplitude of ' can be 95A.

[0084] Optionally, in some feasible implementations, the cycle times of PWM1″ signal, PWM2″ signal and PWM3″ signal are equal, that is, they are all T. Moreover, the duty cycles of PWM1″ signal, PWM2″ signal and PWM3″ signal are the same. In implementing the embodiments of the present application, the controller can use one operating frequency to generate control signals for the three bridge arms, without switching different frequencies to generate signals with different cycle times, thus facilitating control.

[0085] Optionally, in some possible implementations, see Figure 8 , Figure 8 Another waveform diagram provided in the embodiment of the present application. Figure 8 As shown, the controller can switch Q 31 Send PWM1″′ signal to switch tube Q 33 Send PWM2″′ signal and switch Q 35 Send PWM3″′ signal. At this time, the rising edge of PWM1″′ signal is, for example, at t 81 At this moment, the corresponding falling edge is at t 82 PWM2 "' the rising edge of the signal is, for example, at t 81 At this moment, the corresponding falling edge is at t 82 That is, the rising edge of the PWM1″′ signal appears at the same time as the rising edge of the PWM2″′ signal, and the falling edge of the PWM1″′ signal appears at the same time as the falling edge of the PWM2″′ signal. At this time, the cycle time of the PWM1″′ signal is t 82 Time and t 81 The time difference between the instants (e.g. T).

[0086] The rising edge of the PWM2″′ signal is, for example, at t 83 At this moment, the corresponding falling edge is at t 84 moment. It can be seen that t 83 Time lag t 81 At the first preset time, the first preset time is T / 2. At this time, two of the three bridge arms are staggered by 180°.

[0087] The waveform diagram shown in the embodiment of the present application specifically implements the two-phase staggered 180°, that is, the switch tubes in the two bridge arms are not turned on at the same time, for example, the switch tube Q 31 With the switch tube Q 33 At the same time, the switch tube Q 35 On-state ratio switch tube Q 31 And the switch tube Q 33 The turn-on time lags by T / 2. The inventor of the present application found in the research and time process that the controller adopts Figure 8 The waveform diagram shown in the figure controls the three bridge arms, and the heat generated by the motor magnetic steel is relatively small.

[0088] In summary, each switch tube in the three bridge arms (for example, switch tube Q 31 , switch tube Q 33 And the switch tube Q 35 ) is turned on when it receives a high level and turned off when it receives a low level, so each switch tube can be turned on according to Figure 4 , Figure 5 or Figure 6 The waveform diagram shown is turned on or off, so that the power assembly forms different circuit states, thereby boosting the voltage of the DC power supply 301 and providing the boosted voltage to the power battery 303.

[0089] It should be noted that the controller uses Figures 4 to 6 Any waveform diagram shown in the figure to control the switch tubes in the three bridge arms should be understood as a schematic diagram. The controller can also use other waveform diagrams as long as the rising edges or falling edges of the switch tubes in any two of the three bridge arms are staggered.

[0090] Optionally, in some possible implementations, see Fig. 9 , Fig. 9 This is another schematic diagram of the structure of the powertrain provided in the embodiment of the present application. Fig. 9 As shown, the power assembly 10B is arranged between the DC power supply 901 and the power battery 903, and the power assembly 10B includes three bridge arms, a motor M9, a first switch K 91 and the second switch K 92 .

[0091] Take the switch included in the bridge arm as an IGBT and its anti-parallel diode as an example. Fig. 9 As shown, the first bridge arm includes a switch tube Q 91 And the switch tube Q 91 The series switch tube Q 92 The second bridge arm includes the switch tube Q 93 And the switch tube Q 93 The series switch tube Q 94 The third bridge arm includes the switch tube Q 95 And the switch tube Q 95 The series switch tube Q 96 .

[0092] It should be explained that the first bridge arm, the second bridge arm and the third bridge arm can be interchanged. For example, the first bridge arm includes a switch tube Q 93 And the switch tube Q 93 The series switch tube Q 94 The second bridge arm includes the switch tube Q 95 And the switch tube Q95 The series switch tube Q 96 The third bridge arm includes the switch tube Q 91 And the switch tube Q 91 The series switch tube Q 92 .

[0093] First switch K 91 and the second switch K 92 It can be specifically implemented as a contactor, relay, IGBT or MOSFET, etc.

[0094] The first end of the DC power supply 901 is coupled to one end of each bridge arm and the first end of the power battery 903. Fig. 9 The first end of the DC power supply 901 shown in the figure is the positive terminal, the second end of the DC power supply 901 is the negative terminal, the first end of the power battery 903 is the positive terminal, and the second end of the power battery 903 is the negative terminal.

[0095] Then the positive terminal of the DC power supply 901 is coupled to the switch tube Q 91 The collector of the switch tube Q 93 The collector of the switch tube Q 95 The collector of the power battery 903 and the positive terminal of the power battery 903. The negative terminal of the power battery 903 is coupled to the switch tube Q 92 The emitter of the switch tube Q 94 The emitter and switch tube Q 96 of the emitter.

[0096] The midpoint of each bridge arm is coupled to one end of the motor winding corresponding to each bridge arm, and the midpoint of each bridge arm is the series coupling point between two series switch units. 91 The emitter and switch tube Q 92 The collector coupling of the motor winding N U9 One end of the switch tube Q 93 The emitter and switch tube Q 94 The collector coupling of the motor winding N V9 One end of the switch tube Q 95 The emitter and switch tube Q 96 The collector coupling of the motor winding N W9 one end.

[0097] First switch K 91 One end of the bridge is coupled to the midpoint of any one of the three bridge arms. Fig. 9 The first switch K 91 One end of the coupling switch tube Q 91 The emitter and switch tube Q 92 Optionally, the first switch K 91One end can be coupled to the switch tube Q 93 The emitter and switch tube Q 94 Alternatively, the first switch K 91 One end can be coupled to the switch tube Q 95 The emitter and switch tube Q 96 The collector.

[0098] Motor winding N U9 The other end of the motor winding N V9 The other end of the motor winding N W9 Coupling the second switch K 92 One end of the second switch K 92 The other end is connected to the first switch K 91 The other end is coupled to the negative end of the DC power supply 901.

[0099] Optionally, in some feasible implementations, the powertrain further includes an inductor (not shown in the figure). The specific connection method of the inductor can be that one end of the inductor is coupled to the second switch K 92 The other end and the first switch K 91 The other end of the inductor is coupled to the second end of the DC power supply 901.

[0100] Optionally, in some possible implementations, see Fig.10 , Fig.10 This is another schematic diagram of the structure of the powertrain provided in the embodiment of the present application. Fig.10 As shown, the power assembly 10C is disposed between the DC power supply 1001 and the power battery 1003. The internal structure of the power assembly 10C can be referred to Fig. 9 The powertrain 10B shown in FIG. 91 The emitter and switch tube Q 92 The collector coupling of the motor winding N U9 One end of the switch tube Q 93 The emitter and switch tube Q 94 The collector coupling of the motor winding N V9 One end of the switch tube Q 95 The emitter and switch tube Q 96 The collector coupling of the motor winding N W9 One end of the motor winding N U9 The other end of the motor winding N V9 The other end of the motor winding N W9 Coupling the second switch K 92 One end of the first switch K 91 One end of the coupling switch tube Q 91 The emitter and switch tube Q 92 The collector.

[0101] Different from Fig. 9 The powertrain 10B and the powertrain 10C shown in FIG. 1 are different in the way in which the DC power supply 1001 is coupled to the outside. Fig.10 In the embodiment, the first end of the DC power source 1001 is the negative terminal, the second end of the DC power source 1001 is the positive terminal, the first end of the power battery 1003 is the negative terminal, and the second end of the power battery 1003 is the positive terminal.

[0102] Then the positive terminal of the DC power supply 1001 is coupled to the second switch K 92 The other end is connected to the first switch K 91 The other end of the DC power supply 1001 is coupled to the negative terminal of the switch tube Q 92 The collector of the switch tube Q 94 The collector of the switch tube Q 96 The collector of the power battery 1003 and the negative terminal of the power battery 1003. The positive terminal of the power battery 1003 is coupled to the switch tube Q 91 The collector of the switch tube Q 93 The collector and switch tube Q 95 The collector.

[0103] The following is a detailed Fig. 9 Taking the powertrain 10B shown in FIG. 1 as an example, the circuit state of the powertrain is exemplarily described.

[0104] Exemplarily, the controller controls the second switch K 92 is turned on, and the controller follows Figure 6 The waveform shown in FIG. 1 is sent to each bridge arm as an example, that is, the controller can send a signal to the switch tube Q 31 Send PWM1" signal to switch tube Q 33 Send PWM2" signal and switch Q 35 Send PWM3" signal.

[0105] Then, at t 61 Time to t 62 The time period between the moments, the switch tube Q 91 Turn on, switch tube Q 93 And the switch tube Q 95 The second switch K is turned off. 92 At this time, the powertrain 10B forms Fig.11A The circuit state shown in FIG. 1 is that the DC power supply 901 passes through the switch tube Q 91 To the motor winding N U9 to charge.

[0106] In t 62 Time to t 63The time period between the moments, the switch tube Q 91 , switch tube Q 93 And the switch tube Q 95 The second switch K is turned off. 92 At this time, the powertrain 10B forms Fig. 11B In the circuit state shown in FIG. 1 , a DC power supply 901 and a motor winding N U9 The voltage across the power battery 903 is the voltage of the DC power supply 901 and the voltage of the motor winding N U9 The sum of the voltages of the DC power supply 901 is achieved by boosting the voltage of the DC power supply 901 and providing the boosted voltage to the power battery 903.

[0107] In t 63 Time to t 64 The time period between the moments, the switch tube Q 93 Turn on, switch tube Q 91 And the switch tube Q 95 The second switch K is turned off. 92 At this time, the powertrain 10B forms Fig. 11C The circuit state shown in FIG. 1 is that the DC power supply 901 passes through the switch tube Q 93 To the motor winding N V9 to charge.

[0108] In t 64 Time to t 65 The time period between the moments, the switch tube Q 91 , switch tube Q 93 And the switch tube Q 95 The second switch K is turned off. 92 At this time, the powertrain 10B forms Fig.11D In the circuit state shown in FIG. 1 , a DC power supply 901 and a motor winding N V9 The voltage across the power battery 903 is the voltage of the DC power supply 901 and the voltage of the motor winding N V9 The sum of the voltages of the DC power supply 901 is achieved by boosting the voltage of the DC power supply 901 and providing the boosted voltage to the power battery 903.

[0109] In t 65 Time to t 66 The time period between the moments, the switch tube Q 95 Turn on, switch tube Q 91 And the switch tube Q 93 The second switch K is turned off. 92 At this time, the powertrain 10B forms Fig.11E In the circuit state shown in FIG. 1 , the DC power supply 901 is supplied to the motor winding N through the switch tube Q95. W9to charge.

[0110] In t 66 Time to t 69 The time period between the moments, the switch tube Q 91 , switch tube Q 93 And the switch tube Q 95 The second switch K is turned off. 92 At this time, the powertrain 10B forms Fig.11F In the circuit state shown in FIG. 1 , a DC power supply 901 and a motor winding N W9 The voltage across the power battery 903 is the voltage of the DC power supply 901 and the voltage of the motor winding N W9 The sum of the voltages of the DC power supply 901 is achieved by boosting the voltage of the DC power supply 901 and providing the boosted voltage to the power battery 903.

[0111] In summary, FIG. 11A to FIG. 11F All are switched on in the second switch K 92 The first switch K is turned on. 91 When turned off, the powertrain 10B can form a circuit state.

[0112] In some feasible implementations, the difference between the voltage of the power battery 903 and the voltage of the DC power supply 901 is less than a first preset threshold, and the first switch K 91 Turn off, the second switch K 92 The first preset threshold is an empirical value, such as 100V or 150V.

[0113] For example, before sending PWM signals to each switch tube, the controller detects the voltage of the DC power supply 901 and the voltage of the power battery 903. For example, if the controller detects that the voltage of the DC power supply 901 is 500V, the voltage of the power battery 903 is 600V, and the first preset threshold is 150V, the controller controls the first switch K 91 Turn off, the second switch K 92 For another example, after the controller sends PWM signals to each switch tube, the power battery 903 is in a charging state, and the controller still monitors the voltage of the power battery 903 in real time during the charging process. For example, before the voltage of the power battery 903 is charged from 600V to 950V, the difference between the voltage of the power battery 903 and the voltage of the DC power supply 901 is less than the first preset threshold, and the controller keeps controlling the first switch K 91 Turn off, the second switch K 92 Conductivity.

[0114] When the voltage of the power battery 903 is greater than or equal to 950V, the controller controls the first switch K 91The second switch K is turned on. 92 Shut down.

[0115] Optionally, in some feasible implementations, the difference between the voltage of the power battery 903 and the voltage of the DC power supply 901 is greater than or equal to the first preset threshold, and the first switch K 91 The second switch K is turned on. 92 At this time, the controller can turn on the switch tube Q 93 Send the fourth PWM signal and 95 Send the fifth PWM signal. And the switch tube Q 91 It is understood that the controller can provide the switch tube Q 91 Send low level to make the switch Q 91 Or, the controller does not control the switch tube Q 91 , switch tube Q 91 The default state is off.

[0116] It should be noted that the fourth PWM signal and the fifth PWM signal may be synchronous signals, and the rising edges or falling edges of the two may be staggered, etc. The embodiment of the present application does not limit the fourth PWM signal and the fifth PWM signal.

[0117] At this time, the powertrain 10B can have multiple circuit states. For example, the switch tube Q 93 Turn on, switch tube Q 95 The first switch K is turned off and 91 At this time, the powertrain 10B can form Fig. 12A The circuit state shown in FIG. 1 is that the DC power supply 901 passes through the switch tube Q 93 To the motor winding N V9 and motor winding N U9 to charge.

[0118] Switching tube Q 93 And the switch tube Q 95 The first switch K is turned off and 91 At this time, the powertrain 10B can form Fig. 12B The circuit state shown in FIG. 1 includes a DC power supply 901 and a motor winding N. V9 and motor winding N U9 The voltage across the power battery 903 is equal to the voltage of the DC power supply 901 and the motor winding N U9 and motor winding N U9 The sum of the voltages of the DC power supply 901 is achieved by boosting the voltage of the DC power supply 901 and providing the boosted voltage to the power battery 903.

[0119] For example, the switch tube Q95 Turn on, switch tube Q 93 The first switch K is turned off and 91 At this time, the powertrain 10B can form Fig.13A The circuit state shown in FIG. 1 is that the DC power supply 901 passes through the switch tube Q 95 To the motor winding N W9 and motor winding N U9 to charge.

[0120] Switching tube Q 93 And the switch tube Q 95 The first switch K is turned off and 91 At this time, the powertrain 10B can form Fig. 13B The circuit state shown in FIG. 1 includes a DC power supply 901 and a motor winding N. W9 and motor winding N U9 The voltage across the power battery 903 is equal to the voltage of the DC power supply 901 and the motor winding N U9 and motor winding N W9 The sum of the voltages of the DC power supply 901 is achieved by boosting the voltage of the DC power supply 901 and providing the boosted voltage to the power battery 903.

[0121] For example, the switch tube Q 93 And the switch tube Q 95 The first switch K 91 At this time, the powertrain 10B can form Fig.14A The circuit state shown in FIG. 1 is that the DC power supply 901 passes through the switch tube Q 93 To the motor winding N V9 And the motor winding N U9 The DC power supply 901 is also charged through the switch tube Q 95 To the motor winding N W9 And the motor winding N U9 to charge.

[0122] Switching tube Q 93 And the switch tube Q 95 The first switch K is turned off and 91 At this time, the powertrain 10B can form Fig. 14B The circuit state shown in FIG. 1 includes a DC power supply 901 and a motor winding N. U9 And the motor winding N V9 discharge to the outside together, and the DC power supply 901 and the motor winding N U9 And the motor winding N W9 discharge to the outside together. At this time, the motor winding N V9 and motor winding N W9The voltage at both ends of the parallel connection, the motor winding N U9 The sum of the voltages at both ends and the voltage at both ends of the DC power supply 901 is the voltage at both ends of the power battery 903 .

[0123] It should be noted that the above terms “first” and “second” are only used for descriptive purposes and should not be understood as indicating or implying relative importance.

[0124] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A powertrain, characterized in that: The powertrain is arranged between the DC power supply and the power battery, and includes a motor controller (Motor Controller Unit, MCU) and a motor; wherein the MCU includes three bridge arms and a controller, and the motor includes three motor windings corresponding to the three bridge arms; The first end of the DC power supply is coupled to one end of each of the three bridge arms and the first end of the power battery, and the second end of the power battery is coupled to the other end of each bridge arm; the midpoint of each bridge arm is coupled to one end of the motor winding corresponding to each bridge arm; the other end of each of the three motor windings is coupled to the second end of the DC power supply; The three bridge arms include a first bridge arm and a second bridge arm; the first bridge arm is used to be turned on or off according to a first pulse width modulation (PWM) signal sent by the controller, and the second bridge arm is used to be turned on or off according to a second PWM signal sent by the controller; wherein the rising edge of the second PWM signal lags behind the rising edge of the first PWM signal by a first preset time; or, the falling edge of the second PWM signal lags behind the falling edge of the first PWM signal by a second preset time; Wherein, the power assembly further includes a first switching switch and a second switching switch; one end of the first switching switch is coupled to the midpoint of any bridge arm among the three bridge arms; The other end of each of the three motor windings is coupled to the second end of the DC power supply, specifically comprising: The other end of each of the three motor windings is coupled to one end of the second switch, and the other end of the second switch and the other end of the first switch are coupled to the second end of the DC power supply.

2. The powertrain according to claim 1, characterized in that: The three bridge arms further include a third bridge arm, and the third bridge arm is used to be turned on or off according to a third PWM signal; The rising edge of the third PWM signal lags behind the rising edge of the second PWM signal by a third preset time; or the falling edge of the third PWM signal lags behind the falling edge of the second PWM signal by a fourth preset time.

3. The powertrain according to claim 2, characterized in that: The cycle time of the first PWM signal is T; wherein the first preset time and the third preset time are T / 3; or, the second preset time and the fourth preset time are T / 3.

4. The powertrain according to claim 1, characterized in that: The three bridge arms further include a third bridge arm, and the third bridge arm is used to be turned on or off according to a third PWM signal; The rising edge of the third PWM signal appears simultaneously with the rising edge of the first PWM signal; and the falling edge of the third PWM signal appears simultaneously with the falling edge of the first PWM signal.

5. The powertrain according to claim 4, characterized in that: The cycle time of the first PWM signal is T, and the first preset time is T / 2; or the second preset time is T / 2.

6. The powertrain according to any one of claims 2 to 5, characterized in that: The first PWM signal, the second PWM signal and the third PWM signal have the same cycle time and the same duty cycle.

7. The powertrain according to claim 1, characterized in that: When the difference between the voltage of the power battery and the voltage of the DC power supply is less than a first preset threshold, the first switch is turned off and the second switch is turned on.

8. The powertrain according to claim 7, characterized in that: When the difference between the power battery voltage and the DC power supply voltage is greater than or equal to a first preset threshold, the first switch is turned on and the second switch is turned off; The first bridge arm is used to be turned on or off according to a first pulse width modulation (PWM) signal, and the second bridge arm is used to be turned on or off according to a second PWM signal, specifically including: The other two bridge arms among the three bridge arms except the any one bridge arm are used to be turned on or off according to the fourth PWM signal and the fifth PWM signal respectively.

9. The powertrain according to claim 7, characterized in that: The powertrain also includes an inductor; The other end of the second switch is coupled to the other end of the first switch, and the second end of the DC power supply is coupled to the other end of the first switch, and specifically includes: The other end of the second switch and the other end of the first switch are coupled to one end of the inductor, and the other end of the inductor is coupled to the second end of the DC power supply.

10. A charging control method, characterized in that: The charging control method is used for a powertrain, which includes a motor controller (Motor Controller Unit, MCU) and a motor; wherein the MCU includes three bridge arms and a controller, and the motor includes three motor windings corresponding to the three bridge arms; The first end of the DC power supply is coupled to one end of each of the three bridge arms and the first end of the power battery, and the second end of the power battery is coupled to the other end of each of the bridge arms; the midpoint of each of the bridge arms is coupled to one end of the motor winding corresponding to each of the bridge arms; the other end of each of the three motor windings is coupled to the second end of the DC power supply; the three bridge arms include a first bridge arm and a second bridge arm; The charging control method comprises: The controller sends a first pulse width modulation (PWM) signal to the first bridge arm, and sends a second PWM signal to the second bridge arm, wherein a rising edge of the second PWM signal lags behind a rising edge of the first PWM signal by a first preset time; or a falling edge of the second PWM signal lags behind a falling edge of the first PWM signal by a second preset time; Wherein, the power assembly further includes a first switching switch and a second switching switch; one end of the first switching switch is coupled to the midpoint of any bridge arm among the three bridge arms; The other end of each of the three motor windings is coupled to the second end of the DC power supply, specifically comprising: The other end of each of the three motor windings is coupled to one end of the second switch, and the other end of the second switch and the other end of the first switch are coupled to the second end of the DC power supply; The charging control method further includes: when the difference between the voltage of the power battery and the voltage of the DC power supply is less than a first preset threshold, the first switching switch is turned off and the second switching switch is turned on.

11. The charging control method according to claim 10, characterized in that: The three bridge arms also include a third bridge arm; The charging control method further includes: The controller sends a third PWM signal to the third bridge arm; wherein a rising edge of the third PWM signal lags behind a rising edge of the second PWM signal by a third preset time; or a falling edge of the third PWM signal lags behind a falling edge of the second PWM signal by a fourth preset time.

12. The charging control method according to claim 11, characterized in that: The cycle time of the first PWM signal is T; wherein the first preset time and the third preset time are T / 3; or, the second preset time and the fourth preset time are T / 3.

13. The charging control method according to claim 10, characterized in that: The three bridge arms also include a third bridge arm; The charging control method further includes: The controller sends a third PWM signal to the third bridge arm; wherein a rising edge of the third PWM signal appears simultaneously with a rising edge of the first PWM signal; and a falling edge of the third PWM signal appears simultaneously with a falling edge of the first PWM signal.

14. The charging control method according to claim 13, characterized in that: The cycle time of the first PWM signal is T, and the first preset time is T / 2; or the second preset time is T / 2.

15. The charging control method according to any one of claims 10 to 14, characterized in that: The charging control method further includes: When the difference between the power battery voltage and the DC power supply voltage is greater than or equal to a first preset threshold, the first switch is turned on and the second switch is turned off; The other two bridge arms among the three bridge arms except the any one bridge arm are turned on or off according to the fourth PWM signal and the fifth PWM signal respectively.

16. An electric vehicle, characterized in that: The electric vehicle comprises a power battery and a powertrain as described in any one of claims 1 to 9.

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