Control method for circulating current suppression of electric vehicle, motor controller and electric vehicle

Abstract

The invention provides a control method for circulating current suppression of an electric vehicle, a motor controller and the electric vehicle, and is applied to the technical field of electric vehicles. The electric vehicle at least comprises a first motor controller and a second motor controller, the first motor controller comprises a first inverter circuit, the second motor controller comprises a second inverter circuit, the first inverter circuit and the second inverter circuit are connected through a common direct current bus, and the control method is executed by the first motor controller. The control method comprises the following steps: sending a first pulse width modulation (PWM) signal to the first inverter circuit; and in one or more high-level sections of the first PWM signal, a synchronizing signal is sent to a second motor controller, and the synchronizing signal is used for controlling the phase difference between a second PWM signal sent to a second inverter circuit and the first PWM signal to be smaller than or equal to a preset value. In this way, circulation generated in the power assembly is restrained, and the performance of the electric vehicle is stabilized.

Description

Technical Field

[0001] This application relates to the technical field of electric vehicles, and in particular, to a control method for suppressing circulating current in an electric vehicle, a motor controller, and an electric vehicle. Background Art

[0002] With the development of electric vehicle technology, it is crucial to improve the integration level of the powertrain of an electric vehicle. During the process of improving the integration level of the powertrain, some structures in the powertrain (such as the left front motor controller and the right front motor controller) are connected by a common connection line. In the case of multi-structure common connection line connection, circulating current will be generated in the powertrain, affecting the performance of the electric vehicle. Summary of the Invention

[0003] Embodiments of this application provide a control method for suppressing circulating current in an electric vehicle, a motor controller, and an electric vehicle, which suppress the circulating current generated in the powertrain, reduce the losses caused by the circulating current, and stabilize the performance of the electric vehicle.

[0004] In a first aspect, embodiments of this application provide a control method for suppressing circulating current in an electric vehicle. The electric vehicle includes at least a first motor controller and a second motor controller. The first motor controller includes a first inverter circuit, and the second motor controller includes a second inverter circuit. The first inverter circuit and the second inverter circuit are connected by a common DC bus. The control method is executed by the first motor controller. The control method includes: sending a first pulse width modulation (PWM) signal to the first inverter circuit, where the PWM signal is used to control the conduction and cutoff of the switching tubes of the inverter circuit; during one or more high-level segments of the first PWM signal, sending a synchronization signal to the second motor controller, where the synchronization signal is used to control the phase difference between the second PWM signal sent to the second inverter circuit and the first PWM signal to be less than or equal to a preset value.

[0005] Wherein, the preset value is a relatively small value. In embodiments of this application, the specific value of the preset value is not limited and can be 1 / 10 of the period of the first PWM signal or the period of the second PWM signal. When the phase difference between the second PWM signal and the first PWM signal is less than or equal to the preset value, it is considered that the second PWM signal is synchronized with the first PWM signal.

[0006] In this embodiment, by setting a structure in which the first inverter circuit included in the first motor controller and the second inverter circuit included in the second motor controller are connected to a common DC bus, the integration density and volume of the powertrain are improved, the flexibility of the electric vehicle design is enhanced, and the difference between the bus impedance of the first motor controller and the bus impedance of the second motor controller can be controlled within a certain range, suppressing the circulating current generated due to a large impedance difference. Moreover, the first motor controller sends a synchronization signal to the second motor controller during one or more high-level segments of the first PWM signal, and the synchronization signal is used to control the phase difference between the second PWM signal sent to the second inverter circuit and the first PWM signal to be less than or equal to a preset value, achieving consistent switching operation times of the switching tubes of the first inverter circuit and the second inverter circuit, making the output current and voltage of the first inverter circuit and the second inverter circuit time-synchronized, suppressing the bus circulating current generated due to the common bus structure, reducing the heating and loss caused by the bus circulating current, and stabilizing the performance of the electric vehicle.

[0007] In an embodiment of the first aspect, the control method further includes: controlling the period of sending the synchronization signal to be an integer multiple of the period of the first PWM signal or an integer multiple of the period of the second PWM signal.

[0008] In the embodiments of the present application, no specific limitation is imposed on the specific value of the integer multiple. For example, it can be 1, 2, 3, etc. To ensure that the synchronization signal can effectively suppress the circulating current, an upper limit is imposed on the integer multiple. For example, it can be 10, 11, 12, etc.

[0009] In this embodiment, by controlling the period of sending the synchronization signal to be an integer multiple of the period of the first PWM signal or an integer multiple of the period of the second PWM signal, the relationship between the periods of the signals is simple and reliable, which is beneficial to the processing and analysis of the synchronization signal, can reduce the interference between signals, reduce the error accumulation, and improve the stability and reliability of the operation of the electric vehicle.

[0010] In an embodiment of the first aspect, the control method further includes: controlling the period of sending the synchronization signal to increase as the period of the first PWM signal or the second PWM signal increases.

[0011] In this embodiment, by controlling the period of sending the synchronization signal to increase as the period of the first PWM signal or the second PWM signal increases, when it is necessary to adjust the period of the first PWM signal or the second PWM signal, the relationship between the period of the synchronization signal and the period of the first PWM signal or the second PWM signal is still an integer multiple relationship, and the relationship between the periods of the signals is simple and reliable, which is beneficial to maintaining the stability and reliability of the operation of the electric vehicle.

[0012] In an embodiment of the first aspect, the control method further includes: if the second motor controller fails to receive a synchronization signal for a first preset number of consecutive cycles of receiving the synchronization signal or fails to receive a second preset number of synchronization signals within a preset duration, controlling the drive motor corresponding to the first motor controller and the drive motor corresponding to the second motor controller to reduce the torque output.

[0013] In the embodiments of the present application, the specific values of the first preset number, the second preset number, and the preset duration are not limited.

[0014] If the second motor controller fails to receive a synchronization signal for a first preset number of consecutive cycles of receiving the synchronization signal or fails to receive a second preset number of synchronization signals within a preset duration, it is considered that a fault has occurred in the first motor controller or the second motor controller.

[0015] In this embodiment, by automatically detecting that the second motor controller fails to receive a synchronization signal for a first preset number of consecutive cycles of receiving the synchronization signal or fails to receive a second preset number of synchronization signals within a preset duration, the drive motors corresponding to the first motor controller and the second motor controller are timely controlled to reduce the torque output, avoiding the aggravation of the bus circulating current problem and equipment damage.

[0016] In an embodiment of the first aspect, the first motor controller and the second motor controller are also connected through a direct connection signal harness, and the control method further includes: sending a synchronization signal to the second motor controller through the direct connection signal harness.

[0017] In this embodiment, a synchronization signal is sent to the second motor controller through the direct connection signal harness between the first motor controller and the second motor controller. The synchronization signal is a hard-wired signal, with high stability, fast transmission speed, and strong anti-interference ability, which is beneficial to maintaining the stability and reliability of the operation of the electric vehicle.

[0018] In a second aspect, an embodiment of the present application provides a control method for suppressing the circulating current of an electric vehicle. The electric vehicle includes a first motor controller and a second motor controller. The first motor controller includes a first inverter circuit, and the second motor controller includes a second inverter circuit. The first inverter circuit and the second inverter circuit are connected in common to a DC bus. The control method is executed by the second motor controller, and the control method includes: receiving a synchronization signal sent by the first motor controller, and in response to the synchronization signal, sending a second pulse width modulation (PWM) signal to the second inverter circuit, so that the phase difference between the second PWM signal sent to the second inverter circuit and the first PWM signal is less than or equal to a preset value. The PWM signal is used to control the conduction and cutoff of the switching tubes of the inverter circuit.

[0019] In this embodiment, the second motor controller receives the synchronization signal sent by the first motor controller, and in response to the synchronization signal, sends a second pulse width modulation (PWM) signal to the second inverter circuit, so that the phase difference between the second PWM signal sent to the second inverter circuit and the first PWM signal is less than or equal to a preset value. This realizes that the switching action time of the switching tubes of the second inverter circuit is consistent with that of the switching tubes of the second inverter circuit, enables the currents and voltages output by the first inverter circuit and the second inverter circuit to be synchronized in time, suppresses the generation of bus circulating current, reduces the losses caused by the bus circulating current, and improves the anti-interference ability of the electric vehicle powertrain.

[0020] In an embodiment of the second aspect, the control method further includes: if the second motor controller does not receive the synchronization signal for a first preset number of consecutive cycles of receiving the synchronization signal or does not receive a second preset number of synchronization signals within a preset time period, controlling the drive motor corresponding to the first motor controller and the drive motor corresponding to the second motor controller to reduce torque output.

[0021] In this embodiment, by automatically detecting that the second motor controller does not receive the synchronization signal for a first preset number of consecutive cycles of receiving the synchronization signal or does not receive a second preset number of synchronization signals within a preset time period, the drive motor corresponding to the first motor controller and the drive motor corresponding to the second motor controller are timely controlled to reduce torque output, avoiding the aggravation of the bus circulating current problem and equipment damage.

[0022] In an embodiment of the second aspect, the cycle for the second motor controller to receive the synchronization signal is the same as the cycle for the first motor controller to send the synchronization signal.

[0023] In this embodiment, by setting the cycle for the second motor controller to receive the synchronization signal to be the same as the cycle for the first motor controller to send the synchronization signal, the signal processing is simplified, the synchronization signal received in the second motor controller can be monitored, which is beneficial for subsequent signal loss monitoring.

[0024] In a third aspect, an embodiment of the present application provides a first motor controller. The first motor controller includes a first inverter circuit. The first inverter circuit and the second inverter circuit included in the second motor controller are connected in common DC bus. The first motor controller is configured to: send a first pulse width modulation (PWM) signal to the first inverter circuit, and the PWM signal is used to control the conduction and cutoff of the switching tubes of the inverter circuit; during one or more high-level segments of the first PWM signal, send a synchronization signal to the second motor controller, and the synchronization signal is used to control the phase difference between the second PWM signal sent to the second inverter circuit and the first PWM signal to be less than or equal to a preset value.

[0025] Fourth aspect, an embodiment of the present application provides a second motor controller. The second motor controller includes a second inverter circuit. The second inverter circuit and the first inverter circuit included in the first motor controller are connected in a common DC bus. The second motor controller is configured to: receive a synchronization signal sent by the first motor controller, and in response to the synchronization signal, send a second pulse width modulation (PWM) signal to the second inverter circuit, so that the phase difference between the second PWM signal sent to the second inverter circuit and the first PWM signal is less than or equal to a preset value. The PWM signal is used to control the conduction and cutoff of the switching tubes of the inverter circuit.

[0026] Fifth aspect, an embodiment of the present application provides an electric vehicle. The electric vehicle includes at least the first motor controller according to the third aspect and the second motor controller according to the fourth aspect. The first motor controller includes a first inverter circuit, and the second motor controller includes a second inverter circuit. The first inverter circuit and the second inverter circuit are connected in a common DC bus. Among them,

[0027] The first motor controller is configured to:

[0028] send a first pulse width modulation (PWM) signal to the first inverter circuit. The PWM signal is used to control the conduction and cutoff of the switching tubes of the inverter circuit;

[0029] in one or more high-level segments of the first PWM signal, send a synchronization signal to the second motor controller. The synchronization signal is used to control the phase difference between the second PWM signal sent to the second inverter circuit and the first PWM signal to be less than or equal to a preset value;

[0030] The second motor controller is configured to:

[0031] receive the synchronization signal sent by the first motor controller, and in response to the synchronization signal, send a second pulse width modulation (PWM) signal to the second inverter circuit, so that the phase difference between the second PWM signal sent to the second inverter circuit and the first PWM signal is less than or equal to a preset value.

[0032] For the supplements and technical effects of the solutions provided in the above second aspect, third aspect, fourth aspect, and fifth aspect, reference may be made to the corresponding descriptions in the first aspect, and details are not repeated here. Description of the Drawings

[0033] Figure 1 Shows a schematic diagram of an electric vehicle 10 provided by an embodiment of the present application;

[0034] Figure 2 Shows a schematic diagram of a powertrain 13 provided by an embodiment of the present application;

[0035] Figure 3 Shows a schematic diagram of the topology of a powertrain 13 provided by an embodiment of the present application;

[0036] Figure 4 shows a schematic diagram of a signal waveform provided by an embodiment of the present application;

[0037] Figure 5 shows a schematic diagram of an integrated structure of a powertrain 13 provided by an embodiment of the present application. Detailed implementation manners

[0038] The technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings.

[0039] In the embodiments of the present application, prefix words such as "first" and "second" are only used to distinguish different described objects, and have no limiting effect on the position, order, priority, quantity, content, etc. of the described objects. The use of ordinal numbers and other prefix words for distinguishing described objects in the embodiments of the present application does not constitute a limitation on the described objects. For the statements of the described objects, refer to the description in the claims or the context of the embodiments. There should be no redundant limitation due to the use of such prefix words.

[0040] With the development of electric vehicle technology, it is crucial to improve the integration degree of the powertrain of electric vehicles. In the process of improving the integration degree of the powertrain, some structures in the powertrain (such as the left front motor controller and the right front motor controller) are connected by a common connection line. In the case of multi-structure common connection line connection, a circulating current will be generated in the powertrain, affecting the performance of the electric vehicle.

[0041] Among them, the circulating current refers to the current that does not flow along the normal path due to various reasons in the device, forming a closed loop inside the device.

[0042] In one implementation manner, in order to improve the integration degree of the powertrain, in a distributed dual electric drive, the inverter bridges of the dual electric drives share a common DC bus capacitor to smooth the fluctuations of the pulsating voltage and current. However, the scheme of sharing a common DC bus capacitor also has the problem of circulating current.

[0043] In view of this, the embodiments of the present application provide a control method, a motor controller and an electric vehicle for suppressing the circulating current of an electric vehicle, suppressing the circulating current generated in the powertrain, reducing the loss caused by the circulating current, and stabilizing the performance of the electric vehicle.

[0044] See Figure 1 , Figure 1 shows a schematic diagram of an electric vehicle 10 provided by an embodiment of the present application. As Figure 1 shown, the electric vehicle 10 includes wheels 11, a power battery 12 and a powertrain 13. Among them, the powertrain 13 is used to receive power supply from the power battery 12 to drive the wheels 11 or to heat the power battery 12.

[0045] Refer to Figure 2 , Figure 2 which shows a schematic diagram of a powertrain 13 provided by an embodiment of the present application.

[0046] As Figure 2 shown, the powertrain 13 is a distributed dual-motor drive powertrain. The powertrain 13 includes a first drive motor 131 (such as a left front drive motor), a first motor controller 132 of the first drive motor 131, a second drive motor 133 (such as a right front drive motor), and a second motor controller 134 of the second drive motor 133. The first motor controller 132 receives direct current from the power battery 12 and converts the direct current into three-phase alternating current to supply power to the first drive motor 131. The second motor controller 134 receives direct current from the power battery 12 and converts the direct current into three-phase alternating current to supply power to the second drive motor 133. The first drive motor 131 and the wheel 11, and the second drive motor 133 and the wheel 11 are connected by a reducer or a transmission. During the driving process of the electric vehicle 10, the torques of the first drive motor 131 and the second drive motor 133 are transmitted to the wheel 11 to provide power for the electric vehicle 10.

[0047] Refer to Figure 3 , Figure 3 which shows a schematic diagram of a topology structure of a powertrain 13 provided by an embodiment of the present application.

[0048] As Figure 3 shown, the first motor controller 132 includes a first control circuit 1321, a first inverter circuit 1322, and a bus capacitor C. The second motor controller 134 includes a second control circuit 1341, a second inverter circuit 1342, and a bus capacitor C.

[0049] Among them, the first inverter circuit 1321 and the second inverter circuit 1342 share a common DC bus and are connected to the positive and negative poles of the power battery 12. Both ends of the two bus capacitors C are respectively used to connect to the positive pole and the negative pole of the power battery 12. The first inverter circuit 1322 includes a three-phase switch tube bridge arm. Both ends of each switch tube bridge arm are respectively connected to both ends of the bus capacitor C. The midpoint of each switch tube bridge arm is respectively used to connect to a phase winding of the first drive motor 131. The second inverter circuit 1342 includes a three-phase switch tube bridge arm. Both ends of each switch tube bridge arm are respectively connected to both ends of the bus capacitor C. The midpoint of each switch tube bridge arm is respectively used to connect to a phase winding of the second drive motor 133. The rotor position signal output end of the first drive motor 131 is connected to the signal acquisition end of the first control circuit 1321. The rotor position signal output end of the second drive motor 133 is connected to the signal acquisition end of the second control circuit 1341.

[0050] Exemplarily, the first control circuit 1321 and the second control circuit 1342 may include, but are not limited to, 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. The control circuit can control the on or off of the switching tubes in each arm by outputting control signals to each arm of the inverter circuit. Among them, the control signal can be a pulse width modulation (PWM) signal. Exemplarily, the first control circuit 1321 can be connected to the gates of the switching tubes of the three arms in the first inverter circuit 1322 to control the on or off of the switching tubes in the first inverter circuit 1322.

[0051] In some application scenarios, the control circuit can combine the space vector pulse width modulation (SVPWM) technology to generate control signals for each switch of the three arms.

[0052] In this embodiment, through the structure shown as Figure 3 , the integration density of the powertrain is increased, the integration volume is reduced, and the flexibility of the electric vehicle design is improved. Moreover, the common bus design enables the difference between the bus impedance of the first motor controller and the bus impedance of the second motor controller to be controlled within a certain range (for example, 20%), avoiding a series of problems (such as circulating current) caused by a large impedance difference.

[0053] The architecture of the embodiments of the present application has been described above. Next, the control method for suppressing the circulating current provided by the present application will be described in combination with specific embodiments.

[0054] The embodiment of the present application provides a control method for suppressing the circulating current of an electric vehicle, which is executed by the first motor controller 132 and includes the following steps.

[0055] Send a first pulse width modulation (PWM) signal to the first inverter circuit 1322, and the PWM signal is used to control the on and off of the switching tubes of the inverter circuit.

[0056] Specifically, the high level of the PWM signal is used to trigger the conduction of the switching tube in the inverter circuit, and the low level of the PWM signal is used to trigger the turn-off of the switching tube in the inverter circuit. By changing the duty cycle of the PWM signal (i.e., the ratio of the duration of the high-level segment to the entire period), the conduction and turn-off times of the switching tubes in the inverter circuit can be controlled, thereby adjusting parameters such as the voltage, current, and speed of the corresponding drive motor.

[0057] The first PWM signal is generated by the first control circuit and sent to the first inverter circuit. Similarly, the second PWM signal is generated by the second control circuit and sent to the second inverter circuit.

[0058] In one embodiment, in the control circuit, the method for generating a PWM signal includes: determining the voltage reference value to be output according to the operating requirements of the drive motor, such as speed, torque, etc. Then, comparing the carrier signal inside the drive motor with the voltage reference value. When the voltage of the carrier signal is greater than the reference voltage value, the high level of the PWM signal is output; when the voltage of the carrier signal is less than the reference voltage value, the low level of the PWM signal is output to generate the PWM signal (such as the first PWM signal, the second PWM signal).

[0059] In the embodiments of the present application, no limitation is imposed on the specific waveforms of the carrier signal and the PWM signal, which may be triangular waves, sawtooth wave signals, square waves, etc.

[0060] In the control circuit, the PWM signal is periodically generated and sent, and the period of the PWM signal is the same as the period of the carrier signal inside the drive motor. In the embodiments of the present application, no limitation is imposed on the period of the carrier signal inside the drive motor, which can be determined according to the control requirements.

[0061] For ease of understanding, please refer to Figure 4 , Figure 4 which shows a schematic diagram of a signal waveform.

[0062] As Figure 4 shown, the carrier signals inside the first drive motor and the second drive motor are triangular wave signals, and the first PWM signal and the second PWM signal are square wave signals.

[0063] Figure 4 The period between the two dashed lines in

[0064] is one period of the PWM signal, and the periods of the four signals, namely the carrier signal output by the first drive motor, the carrier signal output by the second drive motor, the first PWM signal, and the second PWM signal, are the same. During one or more high-level segments of the first PWM signal, a synchronization signal is sent to the second motor controller 134, and the synchronization signal is used to control the phase difference between the second PWM signal sent to the second inverter circuit and the first PWM signal to be less than or equal to a preset value.

[0065] Among them, the preset value is a relatively small value. In the embodiments of the present application, the specific value of the preset value is not limited and can be 1 / 10 of the period of the first PWM signal or the period of the second PWM signal. When the phase difference between the second PWM signal and the first PWM signal is less than or equal to the preset value, it is considered that the second PWM signal is synchronized with the first PWM signal.

[0066] Among them, the synchronization signal at least includes the relevant information of the first PWM signal, such as the duration of the high-level segment of the first PWM signal, the timestamp for sending the first PWM signal, etc. The synchronization signal jumping from the low level to the high level indicates the start of a synchronization signal, and the synchronization signal jumping from the high level to the low level indicates the end of a synchronization signal. At the same time, the low-level segment is also the interval between two synchronization signals.

[0067] In the embodiments of the present application, the specific waveform of the synchronization signal is not limited, and the waveform of the synchronization signal can be the same as that of the first PWM signal. Similarly, in the embodiments of the present application, the duty cycle of the synchronization signal is not limited, as long as there is an intersection between the high-level segment of the synchronization signal, the high-level segment of the first PWM signal, and the high-level segment of the second PWM signal.

[0068] In one implementation, the sending of the synchronization signal can be triggered by detecting one or more high-level segments of the first PWM signal, or the sending of the synchronization signal can also be monitored and sent at the corresponding moment according to the period of sending the synchronization signal.

[0069] After the second motor controller receives the synchronization signal, in one implementation, the second motor controller adjusts the phase of the second PWM signal sent to the second inverter circuit in response to the received synchronization signal, so that the phase difference between the second PWM signal and the first PWM signal is less than or equal to the preset value.

[0070] Specifically, the second motor controller calculates the target phase information of the second PWM signal according to the synchronization signal; calculates the phase error information of the second PWM signal according to the actual phase information and the target phase information of the second PWM signal; and adjusts the phase of the second PWM signal according to the phase error information. For example, if the actual phase of the second PWM signal is ahead of the target phase, the phase error information indicates that the actual phase of the second PWM signal needs to be adjusted backward; otherwise, the actual phase of the second PWM signal needs to be adjusted forward.

[0071] As Figure 4 shown, in Figure 4 , the synchronization signal is a square wave signal.

[0072] Under the action of the synchronization signal, as Figure 4 shown, the first PWM signal and the second PWM signal are synchronized.

[0073] During one or more high-level segments of the first PWM signal, sending a synchronization signal to the second motor controller means that the synchronization signal can be sent to the second motor controller during each high-level segment of the first PWM signal, or the synchronization signal can be sent to the second motor controller once during multiple high-level segments of the first PWM signal. Figure 4 As shown in the figure, the synchronization signal is sent to the second motor controller during each high-level segment of the first PWM signal, that is, the period of sending the synchronization signal is the same as the period of the first PWM signal.

[0074] In this embodiment, by setting the structure in which the first inverter circuit included in the first motor controller and the second inverter circuit included in the second motor controller are connected to a common DC bus, the integration density and volume of the powertrain are improved, the flexibility of the electric vehicle design is improved, and the difference between the bus impedance of the first motor controller and the bus impedance of the second motor controller can be controlled within a certain range, suppressing the circulating current generated due to the large impedance difference. And the first motor controller sends a synchronization signal to the second motor controller during one or more high-level segments of the first PWM signal, and the synchronization signal is used to control the phase difference between the second PWM signal sent to the second inverter circuit and the first PWM signal to be less than or equal to a preset value, realizing that the switching operation times of the switching tubes of the first inverter circuit and the second inverter circuit are consistent, making the output current and voltage of the first inverter circuit and the second inverter circuit synchronized in time, suppressing the bus circulating current generated due to the common bus structure, reducing the heating and loss caused by the bus circulating current, and stabilizing the performance of the electric vehicle.

[0075] And it is shown by the test of technicians that applying the control method proposed in the embodiment of the present application to an electric vehicle suppresses more than 60% of the circulating current.

[0076] In one embodiment, the period of controlling the sending of the synchronization signal is an integer multiple of the period of the first PWM signal or an integer multiple of the period of the second PWM signal.

[0077] In the embodiment of the present application, the specific value of the integer multiple is not limited, such as 1, 2, 3, etc. In order to ensure that the synchronization signal can effectively suppress the circulating current, the upper limit of the integer multiple is limited, such as 10, 11, 12, etc.

[0078] The period of the first PWM signal is the switching period of the switching tube of the first inverter circuit, the period of the second PWM signal is the switching period of the switching tube of the second inverter circuit, and the period of sending the synchronization signal is an integer multiple of the period of the first PWM signal or an integer multiple of the period of the second PWM signal, that is, the switching tube of the first inverter circuit or the switching tube of the second inverter circuit completes one or more turn-on and turn-off operations, and the synchronization signal completes one cycle of change.

[0079] In this embodiment, by controlling the period of the transmitted synchronization signal to be an integer multiple of the period of the first PWM signal or an integer multiple of the period of the second PWM signal, the relationship between the periods of the signals is simple and reliable, which is beneficial to the processing and analysis of the synchronization signal, can reduce the interference between signals, reduce the error accumulation, and improve the stability and reliability of the operation of the electric vehicle.

[0080] In one embodiment, the period of the transmitted synchronization signal is controlled to increase as the period of the first PWM signal or the second PWM signal increases.

[0081] Wherein, the increased period of the transmitted synchronization signal is an integer multiple of the increased period of the first PWM signal or an integer multiple of the increased period of the second PWM signal.

[0082] In this embodiment, by controlling the period of the transmitted synchronization signal to increase as the period of the first PWM signal or the second PWM signal increases, when it is necessary to adjust the period of the first PWM signal or the second PWM signal, the relationship between the period of the transmitted synchronization signal and the period of the first PWM signal or the second PWM signal is still an integer multiple relationship, and the relationship between the periods of the signals is simple and reliable, which is beneficial to maintaining the stability and reliability of the operation of the electric vehicle.

[0083] In one embodiment, the first motor controller 132 and the second motor controller 134 are also connected through a direct connection signal harness, and the control method specifically includes: sending a synchronization signal to the second motor controller through the direct connection signal harness.

[0084] Wherein, the synchronization signal sent to the second motor controller through the direct connection signal harness is a hard wire signal.

[0085] For ease of understanding, please refer to Figure 5 , Figure 5 which shows a schematic diagram of the integrated structure of a powertrain 13.

[0086] As Figure 5 shown, there is a direct connection signal terminal 1323 and a direct connection signal terminal 1343 on both the first motor controller 132 and the second motor controller 134, and the two direct connection signal terminals are connected through a direct connection signal harness. And there is also a motor controller terminal 1324 and a motor controller terminal 1344 on both the first motor controller 132 and the second motor controller 134, and the first motor controller 132 and the second motor controller 134 are connected to the power battery 12 through the motor controller terminals.

[0087] In this embodiment, a synchronization signal is sent to the second motor controller through a direct connection signal harness between the first motor controller and the second motor controller. The synchronization signal is a hard-wired signal, which has high stability, fast transmission speed, and strong anti-interference ability, and is beneficial to maintaining the stability and reliability of the operation of the electric vehicle.

[0088] In the embodiment of the present application, the reception of the synchronization signal is also monitored.

[0089] In one embodiment, if the second motor controller 134 does not receive the synchronization signal for a first preset number of consecutive cycles of receiving the synchronization signal or does not receive a second preset number of synchronization signals within a preset time period, the drive motor corresponding to the first motor controller and the drive motor corresponding to the second motor controller are controlled to reduce the torque output.

[0090] In the embodiment of the present application, the specific values of the first preset number, the second preset number, and the preset time period are not limited.

[0091] If the second motor controller does not receive the synchronization signal for a first preset number of consecutive cycles of receiving the synchronization signal or does not receive a second preset number of synchronization signals within a preset time period, it is considered that a failure has occurred in the first motor controller or the second motor controller.

[0092] In this embodiment, by automatically detecting that the second motor controller does not receive the synchronization signal for a first preset number of consecutive cycles of receiving the synchronization signal or does not receive a second preset number of synchronization signals within a preset time period, the drive motor corresponding to the first motor controller and the drive motor corresponding to the second motor controller are timely controlled to reduce the torque output, so as to avoid the aggravation of the bus bar circulating current problem and equipment damage.

[0093] The embodiment of the present application also provides a control method for suppressing the circulating current of an electric vehicle, which is executed by the second motor controller 134 and includes the following steps.

[0094] Receive the synchronization signal sent by the first motor controller 132, and in response to the synchronization signal, send a second pulse width modulation (PWM) signal to the second inverter circuit, so that the phase difference between the second PWM signal sent to the second inverter circuit 1342 and the first PWM signal is less than or equal to a preset value. The PWM signal is used to control the on and off of the switching tubes of the inverter circuit.

[0095] The waveform of the second PWM signal sent to the second inverter circuit in response to the synchronization signal is as Figure 4 shown.

[0096] Among them, other descriptions in the embodiment of the present application can refer to the relevant descriptions of the control method executed by the first motor controller, which will not be elaborated here.

[0097] In this embodiment, the second motor controller receives the synchronization signal sent by the first motor controller, and in response to the synchronization signal, sends a second pulse width modulation (PWM) signal to the second inverter circuit, so that the phase difference between the second PWM signal sent to the second inverter circuit and the first PWM signal is less than or equal to a preset value, realizing that the switching action time of the switching tubes of the second inverter circuit is consistent with the switching action time of the switching tubes of the second inverter circuit, making the currents and voltages output by the first inverter circuit and the second inverter circuit synchronized in time, suppressing the generation of bus circulating current, reducing the losses caused by the bus circulating current, and improving the anti-interference ability of the electric vehicle powertrain.

[0098] In one embodiment, the period for the second motor controller 134 to receive the synchronization signal is the same as the period for the first motor controller 132 to send the synchronization signal.

[0099] Wherein, the period for receiving the synchronization signal is an integer multiple of the period of the first PWM signal or an integer multiple of the period of the second PWM signal.

[0100] In this embodiment, by setting the period for the second motor controller to receive the synchronization signal to be the same as the period for the first motor controller to send the synchronization signal, the signal processing is simplified, and it is possible to monitor the synchronization signal received in the second motor controller, which is beneficial for subsequent signal loss monitoring.

[0101] In one embodiment, if the second motor controller 134 does not receive the synchronization signal for a first preset number of consecutive periods of receiving the synchronization signal or does not receive a second preset number of synchronization signals within a preset time duration, the drive motors corresponding to the first motor controller 132 and the second motor controller 134 are controlled to reduce the torque output.

[0102] In this embodiment, by automatically detecting that the second motor controller does not receive the synchronization signal for a first preset number of consecutive periods of receiving the synchronization signal or does not receive a second preset number of synchronization signals within a preset time duration, the drive motors corresponding to the first motor controller and the second motor controller are timely controlled to reduce the torque output, avoiding the aggravation of the bus circulating current problem and equipment damage.

[0103] An embodiment of the present application provides a first motor controller 132, and the first motor controller 132 is used to execute the control method for suppressing the circulating current of the electric vehicle provided in the above embodiment.

[0104] The first motor controller 132 provided in the embodiment of the present application is configured to: send a first pulse width modulation (PWM) signal to the first inverter circuit, and the PWM signal is used to control the conduction and cutoff of the switching tubes of the inverter circuit; during one or more high-level segments of the first PWM signal, send a synchronization signal to the second motor controller, and the synchronization signal is used to control the phase difference between the second PWM signal sent to the second inverter circuit and the first PWM signal to be less than or equal to a preset value.

[0105] The embodiment of the present application provides a second motor controller 134, and the second motor controller 134 is configured to execute the control method for suppressing circulating current in an electric vehicle provided in the above embodiment.

[0106] The second motor controller 134 provided in the embodiment of the present application is configured to: receive the synchronization signal sent by the first motor controller, and in response to the synchronization signal, send a second pulse width modulation (PWM) signal to the second inverter circuit, so that the phase difference between the second PWM signal sent to the second inverter circuit and the first PWM signal is less than or equal to a preset value, and the PWM signal is used to control the conduction and cutoff of the switching tubes of the inverter circuit.

[0107] In another embodiment of the embodiment of the present application, an electric vehicle is further provided. The electric vehicle includes at least a first motor controller and a second motor controller. The first motor controller includes a first inverter circuit, and the second motor controller includes a second inverter circuit. The first inverter circuit and the second inverter circuit are connected in a common DC bus. Among them,

[0108] The first motor controller is configured to:

[0109] send a first pulse width modulation (PWM) signal to the first inverter circuit, and the PWM signal is used to control the conduction and cutoff of the switching tubes of the inverter circuit; during one or more high-level segments of the first PWM signal, send a synchronization signal to the second motor controller, and the synchronization signal is used to control the phase difference between the second PWM signal sent to the second inverter circuit and the first PWM signal to be less than or equal to a preset value;

[0110] The second motor controller is configured to:

[0111] receive the synchronization signal sent by the first motor controller, and in response to the synchronization signal, send a second pulse width modulation (PWM) signal to the second inverter circuit, so that the phase difference between the second PWM signal sent to the second inverter circuit and the first PWM signal is less than or equal to a preset value.

[0112] It can be understood that all relevant contents involved in the above method embodiments can be cited in the embodiments of the first motor controller and the second motor controller, and the embodiment of the electric vehicle. The embodiments of the present application will not be elaborated herein.

[0113] Finally, it should be noted that the above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A control method for suppressing circulating current of an electric vehicle, characterized in that: The electric vehicle at least includes a first motor controller and a second motor controller, the first motor controller includes a first inverter circuit, the second motor controller includes a second inverter circuit, the first inverter circuit and the second inverter circuit are connected to a common DC bus, and the control method is executed by the first motor controller, and the control method includes: Sending a first pulse width modulation (PWM) signal to the first inverter circuit, wherein the PWM signal is used to control the on and off of a switch tube of the inverter circuit; In one or more high level segments of the first PWM signal, a synchronization signal is sent to the second motor controller, and the synchronization signal is used to control the phase difference between the second PWM signal sent to the second inverter circuit and the first PWM signal to be less than or equal to a preset value.

2. The control method according to claim 1, characterized in that: The control method specifically includes: The period of sending the synchronization signal is controlled to be an integer multiple of the period of the first PWM signal or an integer multiple of the period of the second PWM signal.

3. The control method according to claim 1, characterized in that: The control method specifically includes: The period of sending the synchronization signal is controlled to increase as the period of the first PWM signal or the second PWM signal increases.

4. The control method according to claim 1, characterized in that: The control method further comprises: If the second motor controller fails to receive the synchronization signal for a first preset number of consecutive cycles of receiving the synchronization signal or fails to receive a second preset number of the synchronization signal within a preset time period, the drive motor corresponding to the first motor controller and the drive motor corresponding to the second motor controller are controlled to reduce torque output.

5. The control method according to claim 1, characterized in that: The first motor controller and the second motor controller are also connected via a direct signal harness, and the control method specifically includes: A synchronization signal is sent to the second motor controller via the direct signal harness.

6. A control method for suppressing circulating current in an electric vehicle, characterized in that: The electric vehicle includes a first motor controller and a second motor controller, the first motor controller includes a first inverter circuit, the second motor controller includes a second inverter circuit, the first inverter circuit and the second inverter circuit are connected to a common DC bus, and the control method is executed by the second motor controller, and the control method includes: Receive a synchronization signal sent by the first motor controller, and send a second pulse width modulation (PWM) signal to the second inverter circuit in response to the synchronization signal, so that the phase difference between the second PWM signal sent to the second inverter circuit and the first PWM signal is less than or equal to a preset value, and the PWM signal is used to control the on and off of the switch tube of the inverter circuit.

7. The control method according to claim 6, characterized in that: The control method further comprises: If the second motor controller fails to receive the synchronization signal for a first preset number of consecutive cycles of receiving the synchronization signal or fails to receive a second preset number of the synchronization signal within a preset time period, the drive motor corresponding to the first motor controller and the drive motor corresponding to the second motor controller are controlled to reduce torque output.

8. The control method according to claim 6, characterized in that: The period at which the second motor controller receives the synchronization signal is the same as the period at which the first motor controller sends the synchronization signal.

9. A first motor controller, characterized in that: The first motor controller includes a first inverter circuit, the first inverter circuit and a second inverter circuit included in the second motor controller are connected to a common DC bus, and the first motor controller is used for: Sending a first pulse width modulation (PWM) signal to the first inverter circuit, wherein the PWM signal is used to control the on and off of a switch tube of the inverter circuit; In one or more high level segments of the first PWM signal, a synchronization signal is sent to the second motor controller, and the synchronization signal is used to control the phase difference between the second PWM signal sent to the second inverter circuit and the first PWM signal to be less than or equal to a preset value.

10. A second motor controller, characterized in that: The second motor controller includes a second inverter circuit, the second inverter circuit and the first inverter circuit included in the first motor controller are connected to a common DC bus, and the second motor controller is used for: Receive a synchronization signal sent by the first motor controller, and send a second pulse width modulation (PWM) signal to the second inverter circuit in response to the synchronization signal, so that the phase difference between the second PWM signal sent to the second inverter circuit and the first PWM signal is less than or equal to a preset value, and the PWM signal is used to control the on and off of the switch tube of the inverter circuit.

11. An electric vehicle, characterized in that: The electric vehicle at least comprises the first motor controller as claimed in claim 9 and the second motor controller as claimed in claim 10, the first motor controller comprises a first inverter circuit, the second motor controller comprises a second inverter circuit, the first inverter circuit and the second inverter circuit are connected to a common DC bus, wherein: The first motor controller is used for: Sending a first pulse width modulation (PWM) signal to the first inverter circuit, wherein the PWM signal is used to control the on and off of a switch tube of the inverter circuit; In one or more high-level segments of the first PWM signal, a synchronization signal is sent to the second motor controller, wherein the synchronization signal is used to control a phase difference between a second PWM signal sent to the second inverter circuit and the first PWM signal to be less than or equal to a preset value; The second motor controller is used for: Receive a synchronization signal sent by the first motor controller, and send a second pulse width modulation (PWM) signal to the second inverter circuit in response to the synchronization signal, so that the phase difference between the second PWM signal sent to the second inverter circuit and the first PWM signal is less than or equal to a preset value.

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