Current sampling method and device of three-phase motor driving circuit and steer-by-wire system

Abstract

The invention relates to a current sampling method and device of a three-phase motor driving circuit and a steer-by-wire system. The method comprises the following steps: when any two phases of sampling currents in three phases of sampling currents of a lower bridge arm of the three-phase motor driving circuit are abnormal, respectively acquiring a sampling current of a third phase and an electrical angle of a motor; wherein the three-phase motor driving circuit is connected with the motor and is used for driving the motor to operate; determining a phase current amplitude according to the sampling current of the third phase and the electrical angle of the motor; and determining the feedback current of the first phase and the feedback current of the second phase according to the phase current amplitude and the electrical angle of the motor. According to the invention, the sampling current of the third phase can be used for estimating the abnormal feedback current of the two phases, so that the steering-by-wire system continues to provide assistance.

Description

Technical Field

[0001] The present application relates to the technical field of steer-by-wire systems, and particularly to a method and device for current sampling of a three-phase motor drive circuit and a steer-by-wire system. Background Art

[0002] In a steer-by-wire system (SBW), the mechanical connection between the steering wheel and the steering wheel is cancelled, and the information transmission and control of steering are completely realized by electrical signals. In a steer-by-wire system, the power-assisted steering motor is an actuator of the SBW, which directly affects the steering performance of the SBW and the safety of the driver. In the current closed-loop control scheme of the power-assisted steering motor, the three-phase current of the motor is the most critical parameter, which directly affects the control performance of the power-assisted motor, and further affects the steering performance of the SBW and the safety of the driver.

[0003] In the case where at least one of the three-phase sampled currents is abnormal, generally, the sampling circuit failure is directly reported and the power assistance is cut off at the same time. At this time, the steering system no longer provides power assistance, and the driver can only slowly steer the vehicle to a safe place by hand torque, which directly affects the driver's feel and operability, and the driver experience is very poor. Summary of the Invention

[0004] Based on this, it is necessary to provide a method and device for current sampling of a three-phase motor drive circuit and a steer-by-wire system, which can estimate the feedback currents of the two abnormal phases by using the sampled current of the third phase, so that the steer-by-wire system can continue to provide power assistance.

[0005] In a first aspect, an embodiment of the present application provides a method for current sampling of a three-phase motor drive circuit, the method includes:

[0006] In the three-phase sampled currents of the lower bridge arm of the three-phase motor drive circuit, when any two of the sampled currents are abnormal, the sampled current of the third phase and the electrical angle of the motor are respectively obtained; wherein, the three-phase motor drive circuit is connected to the motor and is used to drive the motor to operate;

[0007] Determine the phase current amplitude according to the sampled current of the third phase and the electrical angle of the motor;

[0008] Determine the feedback current of the first phase and the feedback current of the second phase according to the phase current amplitude and the electrical angle of the motor.

[0009] In one of the embodiments, the determining the phase current amplitude according to the sampled current of the third phase and the electrical angle of the motor includes:

[0010] Obtain the electrical angle of the third phase;

[0011] Determine the angular difference of the third phase according to the electrical angle of the motor and the electrical angle of the third phase;

[0012] Determine the phase current amplitude according to the ratio of the sampled current of the third phase to the cosine value of the angular difference of the third phase.

[0013] In one embodiment, the determining the feedback current of the first phase and the feedback current of the second phase according to the phase current amplitude and the electrical angle of the motor includes:

[0014] Obtain the electrical angle of the first phase and the electrical angle of the second phase respectively;

[0015] Determine the angular difference of the first phase according to the electrical angle of the motor and the electrical angle of the first phase, and determine the angular difference of the second phase according to the electrical angle of the motor and the electrical angle of the second phase;

[0016] Determine the feedback current of the first phase according to the product of the phase current amplitude and the cosine value of the angular difference of the first phase, and determine the feedback current of the second phase according to the product of the phase current amplitude and the cosine value of the angular difference of the second phase.

[0017] In one embodiment, the method further includes:

[0018] Obtain the duty cycle of the driving signal of the upper bridge arm of the third phase;

[0019] The obtaining the sampled current of the third phase includes:

[0020] Obtain the sampled current of the third phase when the duty cycle is less than a preset duty cycle threshold.

[0021] In one embodiment, the three-phase motor drive circuit includes a power supply, three-phase bridge arms, three-phase sampling resistors and a detection circuit. Among them, each upper bridge arm is respectively connected to the positive pole of the power supply and the first end of the lower bridge arm of the corresponding phase, each phase sampling resistor is respectively connected to the negative pole of the power supply and the second end of the lower bridge arm of the corresponding phase, and the detection circuit is respectively connected to both ends of each phase sampling resistor to form a sampling path. The method further includes:

[0022] When the first sampling resistor is short-circuited, determine that the sampled current of the phase corresponding to the first sampling resistor is abnormal; where the first sampling resistor is one of the three-phase sampling resistors;

[0023] When at least one sampling path of the second sampling resistor is open, or both sampling paths of the second sampling resistor are short-circuited, determine that the sampled current of the phase corresponding to the second sampling resistor is abnormal; where the second sampling resistor is one of the three-phase sampling resistors.

[0024] In one embodiment, the method further includes:

[0025] According to the feedback current of the first phase, the feedback current of the second phase, and the sampled current of the third phase, control the working state of the three-phase motor drive circuit to drive the motor to move.

[0026] In a second aspect, an embodiment of the present application provides a current sampling device for a three-phase motor drive circuit, including:

[0027] An acquisition module, configured to respectively acquire the sampled current of the third phase and the electrical angle of the motor when any two of the three sampled currents of the lower bridge arm of the three-phase motor drive circuit are abnormal; wherein, the three-phase motor drive circuit is connected to the motor and is used to drive the motor to operate;

[0028] A determination module, configured to determine the phase current amplitude according to the sampled current of the third phase and the electrical angle of the motor, and determine the feedback current of the first phase and the feedback current of the second phase according to the phase current amplitude and the electrical angle of the motor.

[0029] In a third aspect, an embodiment of the present application provides a steer-by-wire system, the steer-by-wire system includes:

[0030] A motor;

[0031] A three-phase motor drive circuit, connected to the motor and used to drive the motor to move;

[0032] A control circuit, connected to the three-phase motor drive circuit, configured to respectively acquire the sampled current of the third phase and the electrical angle of the motor when any two of the three sampled currents of the lower bridge arm of the three-phase motor drive circuit are abnormal; determine the phase current amplitude according to the sampled current of the third phase and the electrical angle of the motor; determine the feedback current of the first phase and the feedback current of the second phase according to the phase current amplitude and the electrical angle of the motor.

[0033] In a fourth aspect, an embodiment of the present application provides a computer device, including a memory and a processor, the memory stores a computer program, and when the processor executes the computer program, the steps of the above method are implemented.

[0034] In a fifth aspect, an embodiment of the present application provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the above method are implemented.

[0035] The current sampling method, device, and steer-by-wire system of the above three-phase motor drive circuit, in the three-phase sampling currents of the lower bridge arm of the three-phase motor drive circuit, when any two of the three-phase sampling currents are abnormal, respectively obtain the sampling current of the third phase and the electrical angle of the motor, determine the phase current amplitude according to the sampling current of the third phase and the electrical angle of the motor, and determine the feedback current of the first phase and the feedback current of the second phase according to the phase current amplitude and the electrical angle of the motor. Since the currents output by the three lower bridge arms are all related to the electrical angle of the motor, and the current amplitudes output by the two abnormal lower bridge arms are respectively related to the phase current amplitude of the third phase. Therefore, after determining the phase current amplitude through the sampling current of the third phase and the electrical angle of the motor in this application, the feedback currents of the other two phases can be estimated respectively according to the electrical angle and the phase current amplitude of the motor. Subsequently, the motor can be continuously driven to provide assistance according to the feedback currents of the two phases and the sampling current of the third phase, avoiding the driving failure of the motor due to the abnormality of the two-phase sampling currents, resulting in the motor stopping running and losing assistance, and without the need to additionally increase hardware components, the motor drive requirements can be met, reducing the hardware cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application or in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to these drawings.

[0037] Figure 1 Schematic structural diagram of a three-phase motor drive circuit of an embodiment;

[0038] Figure 2 Schematic flowchart of a current sampling method of a three-phase motor drive circuit of an embodiment;

[0039] Figure 3 Schematic flowchart of a current sampling method of a three-phase motor drive circuit of an embodiment;

[0040] Figure 4 Schematic flowchart of a current sampling method of a three-phase motor drive circuit of an embodiment;

[0041] Figure 5 Schematic flowchart of a current sampling method of a three-phase motor drive circuit of an embodiment;

[0042] Figure 6 Schematic structural diagram of a three-phase motor drive circuit of another embodiment;

[0043] Figure 7 Schematic structural diagram of a steer-by-wire system of an embodiment;

[0044] Figure 8 Structural schematic diagram of a three - phase motor drive circuit for another embodiment;

[0045] Figure 9 Structural schematic diagram of a current sampling device of a three - phase motor drive circuit for an embodiment;

[0046] Figure 10 Structural schematic diagram of a computer device for an embodiment. Detailed implementation manners

[0047] For ease of understanding of the present application, the present application will be described more comprehensively below with reference to the relevant drawings. Embodiments of the present application are given in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided so that the disclosure of the present application is more thorough and comprehensive.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used in the description of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0049] It can be understood that the terms "first", "second", etc. used in this application can be used herein to describe various objects, but these objects are not limited by these terms. These terms are only used to distinguish one object from another. For example, without departing from the scope of this application, the first phase can be called the second phase, and similarly, the second phase can be called the first phase. Both the first phase and the second phase are phases, but they are not the same phase.

[0050] It can be understood that "connection" in the following embodiments should be understood as "electrical connection", "communication connection", etc. if there is an electrical signal or data transfer between the connected circuits, modules, units, etc.

[0051] It can be understood that "at least one" means one or more, and "a plurality" means two or more. "At least part of an element" means part or all of the element. When used herein, the singular forms "a", "an", and "the" may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms "include", "comprise", or "have", etc. specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. At the same time, the term "and / or" used in this specification includes any and all combinations of the related listed items.

[0052] The current sampling method of the three-phase motor drive circuit provided by the embodiments of the present application can be applied to, for example, Figure 1 the three-phase motor drive circuit 1 shown in the figure. The three-phase motor drive circuit 1 includes a power supply D, a three-phase bridge arm, and three-phase sampling resistors. Among them, each phase of the upper bridge arm is respectively connected to the positive pole of the power supply D and the first end of the corresponding lower bridge arm, and each phase of the sampling resistor is respectively connected to the negative pole of the power supply D and the second end of the corresponding phase of the lower bridge arm. Among them, the connection points of each phase of the upper bridge arm and the corresponding phase of the lower bridge arm are respectively connected to the motor 2 for driving the motor 2 to operate to provide electric assistance. Exemplarily, each phase of the bridge arm includes two switching tubes, one of the switching tubes serves as the upper bridge arm, and the other serves as the lower bridge arm. Exemplarily, the switching tubes include Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFET / MOS) and Insulated Gate Bipolar Transistors (IGBT).

[0053] For the convenience of description, in the embodiments of the present application, the three-phase bridge arms are respectively denoted as the A-phase bridge arm, the B-phase bridge arm, and the C-phase bridge arm. Among them, the A-phase bridge arm includes switching tubes M1 and M2, the B-phase bridge arm includes switching tubes M3 and M4, and the C-phase bridge arm includes switching tubes M5 and M6. The upper bridge arms of the ABC three-phase bridge arms are respectively switching tubes M1, M3, and M5, and the lower bridge arms of the ABC three-phase bridge arms are respectively switching tubes M2, M4, and M6. Among them, the first poles of switching tube M1, switching tube M3, and switching tube M5 are respectively connected to the positive pole of the power supply D, the second pole of switching tube M1 is connected to the first pole of switching tube M2, the second pole of switching tube M2 is connected to the first end of sampling resistor Ra, the second pole of switching tube M3 is connected to the first pole of switching tube M4, the second pole of switching tube M4 is connected to the first end of sampling resistor Rb, the second pole of switching tube M5 is connected to the second pole of switching tube M6, the second pole of switching tube M6 is connected to the first end of sampling resistor Rc, and the second ends of sampling resistor Ra, sampling resistor Rb, and sampling resistor Rc are respectively connected to the negative pole of the power supply D.

[0054] It can be understood that in the application, the sampling currents (including ia, ib, and ic) of the lower three bridges (including M2, M4, and M6) of the three-phase motor drive circuit 1 are respectively obtained through the three-phase sampling resistors (including Ra, Rb, and Rc) to achieve the current closed-loop control of the motor 2.

[0055] In the related art, when at least one phase of the three-phase sampled current is abnormal, generally, the sampling circuit failure is directly reported and the assistance is cut off at the same time. At this time, the steer-by-wire system no longer provides assistance, and the driver can only slowly steer by hand torque to park the vehicle in a safe area, with little operability and poor driver experience. In response to this, the embodiments of the present application provide a current sampling method, device and steer-by-wire system for a three-phase motor drive circuit 1, which can estimate the feedback currents of the two abnormal phases by using the sampled current of the third phase, so that the steer-by-wire system continues to provide assistance.

[0056] In one embodiment, as Figure 2 shown, a current sampling method for a three-phase motor drive circuit 1 is provided, and this current sampling method is described by applying it to Figure 1 the three-phase motor drive circuit 1 shown. The execution subject of the current sampling method provided in this embodiment can be a terminal, a server, or a system including a terminal and a server, and is implemented through the interaction between the terminal and the server. This embodiment takes the application of this current sampling method to a terminal as an example for illustration, and this current sampling method includes the following steps S202 to step S206.

[0057] S202: When any two of the three-phase sampled currents of the lower bridge arm of the three-phase motor drive circuit are abnormal, respectively obtain the sampled current of the third phase and the electrical angle of the motor.

[0058] In the embodiments of the present application, the sampled current refers to the current output by each phase of the lower bridge arm determined by the sampling resistor. In the application, the three-phase sampled currents can be monitored to determine whether they are abnormal. Exemplarily, when the sampled current cannot be obtained or the sampled current remains fixed for a long time such as 0, it is determined that the sampled current is abnormal. Among them, the electrical angle of the motor 2 refers to the angle of the rotor of the motor 2, and the electrical angle of the motor 2 can be denoted as θ0. Exemplarily, the electrical angle of the motor 2 is obtained through an angle sensor. Another exemplarily, the Hall signal of the motor 2 is obtained through a Hall sensor, and the electrical angle of the motor 2 is obtained according to the Hall signal.

[0059] If the sampled current ia of phase A and the sampled current ib of phase B are abnormal, then obtain the sampled current ic of phase C. If the sampled current ib of phase B and the sampled current ic of phase C are abnormal, then obtain the sampled current ia of phase A. If the sampled current ia of phase A and the sampled current ic of phase C are abnormal, then obtain the sampled current ib of phase B.

[0060] S204: Determine the phase current amplitude according to the sampled current of the third phase and the electrical angle of the motor.

[0061] Among them, the phase current amplitude refers to the amplitude of the sampled current of the third phase, and the phase current amplitude can be denoted as I. The phase current amplitude can be understood as the maximum absolute value that the sampled current of the third phase instantaneously appears within one cycle.

[0062] S206: Determine the feedback current of the first phase and the feedback current of the second phase according to the phase current amplitude and the electrical angle of the motor.

[0063] In the embodiment of the present application, the feedback current refers to the current output by the lower bridge arm of other phases determined according to the sampled current of the third phase. Specifically, the feedback current of the first phase refers to the current output by the lower bridge arm of the first phase determined according to the sampled current of the third phase; the feedback current of the second phase refers to the current output by the lower bridge arm of the second phase determined according to the sampled current of the third phase, and the feedback current of the second phase can be denoted as.

[0064] If the sampled current ia of phase A and the sampled current ib of phase B are abnormal, then determine the feedback current ia' of phase A and the feedback current ib' of phase B according to the sampled current ic of phase C respectively. If the sampled current ib of phase B and the sampled current ic of phase C are abnormal, then determine the feedback current ib' of phase B and the feedback current ic' of phase C according to the sampled current ia of phase A respectively. If the sampled current ia of phase A and the sampled current ic of phase C are abnormal, then determine the feedback current ia' of phase A and the feedback current ic' of phase C according to the sampled current ib of phase B respectively.

[0065] For the above current sampling method of the three-phase motor drive circuit 1, among the three-phase sampled currents of the lower bridge arm of the three-phase motor drive circuit 1, when any two-phase sampled currents are abnormal, respectively obtain the sampled current of the third phase and the electrical angle of the motor 2, determine the phase current amplitude according to the sampled current of the third phase and the electrical angle of the motor 2, and determine the feedback current of the first phase and the feedback current of the second phase according to the phase current amplitude and the electrical angle of the motor 2. Since the currents output by the three-phase lower bridge arms are all related to the electrical angle of the motor 2, and the amplitudes of the currents output by the abnormal two-phase lower bridge arms are respectively related to the phase current amplitude of the third phase. Therefore, after determining the phase current amplitude through the sampled current of the third phase and the electrical angle of the motor 2 in the present application, the feedback currents of the other two phases can be estimated respectively according to the electrical angle of the motor 2 and the phase current amplitude, and then the motor 2 can be continuously driven to provide assistance according to the feedback currents of the two phases and the sampled current of the third phase, avoiding the driving failure of the motor 2 due to the abnormality of the two-phase sampled currents, resulting in the motor 2 stopping running and losing assistance, and without the need to additionally increase hardware components, it can meet the driving requirements of the motor 2 and reduce the hardware cost.

[0066] In one embodiment, as Figure 3 shown, step S204, determining the phase current amplitude according to the sampled current of the third phase and the electrical angle of the motor 2, may include the following steps S302 to step S306.

[0067] S302: Obtain the electrical angle of the third phase.

[0068] In the embodiment of the present application, the electrical angle of the third phase refers to the angle of the third phase in the three-phase windings of the motor 2. The angles of the three-phase windings of the motor 2 are fixed, and the angles of adjacent two-phase windings are 120° or 2π / 3. Or rather, the three-phase currents have symmetry. Taking Figure 1 the shown three-phase motor drive circuit 1 as an example, the electrical angle of phase A can be denoted as θa, the electrical angle of phase B can be denoted as θb, and the electrical angle of phase C can be denoted as θc. Exemplarily, the electrical angle of phase A is 0°, the electrical angle of phase B is 120° or 2π / 3, and the electrical angle of phase C is 240° or 4π / 3.

[0069] If the sampled current ia of phase A and the sampled current ib of phase B are abnormal, then obtain the electrical angle θc of phase C. If the sampled current ib of phase B and the sampled current ic of phase C are abnormal, then obtain the electrical angle θa of phase A. If the sampled current ia of phase A and the sampled current ic of phase C are abnormal, then obtain the electrical angle θb of phase B.

[0070] S304: Determine the angle difference of the third phase according to the electrical angle of the motor and the electrical angle of the third phase.

[0071] In the embodiment of the present application, the angle difference of the third phase is denoted as Δθ. Exemplarily, the angle difference of the third phase is the difference between the electrical angle of the motor 2 and the electrical angle of the third phase. If the sampled current ia of phase A and the sampled current ib of phase B are abnormal, then determine the angle difference Δθc of phase C = θ0 - θc. If the sampled current ib of phase B and the sampled current ic of phase C are abnormal, then determine the angle difference Δθa of phase A = θ0 - θa. If the sampled current ia of phase A and the sampled current ic of phase C are abnormal, then determine the angle difference Δθb of phase B = θ0 - θb.

[0072] S306: Determine the phase current amplitude according to the ratio of the sampled current of the third phase to the cosine value of the angle difference of the third phase.

[0073] Exemplarily, it can be expressed by the formula: in = Icos(Δθn) = Icos(θ0 - θn), where in represents the sampled current of the third phase, θn represents the electrical angle of the third phase, and n represents the third phase. If the sampled current ia of phase A and the sampled current ib of phase B are abnormal, then the phase current amplitude I can be determined according to ic = Icos(θ0 - θc). If the sampled current ib of phase B and the sampled current ic of phase C are abnormal, then the phase current amplitude I can be determined according to ia = Icos(θ0 - θa). If the sampled current ia of phase A and the sampled current ic of phase C are abnormal, then the phase current amplitude I can be determined according to ib = Icos(θ0 - θb).

[0074] The current sampling method of the above three-phase motor drive circuit 1 obtains the electrical angle of the third phase, determines the angle difference of the third phase according to the electrical angle of the motor 2 and the electrical angle of the third phase, and determines the phase current amplitude according to the ratio of the sampled current of the third phase to the cosine value of the angle difference of the third phase. Thus, the feedback current of the first phase and the feedback current of the second phase can be estimated based on the phase current amplitude and the electrical angle of the motor 2, so as to perform closed-loop control on the motor 2 according to the feedback current of the first phase, the feedback current of the second phase, and the sampled current of the third phase, drive the motor 2 to operate normally, and provide electric assistance.

[0075] In one embodiment, as Figure 4 shown, step S206 of determining the feedback current of the first phase and the feedback current of the second phase according to the phase current amplitude and the electrical angle of the motor 2 may include the following steps S402 to S406.

[0076] S402: Obtain the electrical angle of the first phase and the electrical angle of the second phase respectively.

[0077] S404: Determine the angle difference of the first phase according to the electrical angle of the motor and the electrical angle of the first phase, and determine the angle difference of the second phase according to the electrical angle of the motor and the electrical angle of the second phase.

[0078] S406: Determine the feedback current of the first phase according to the product of the phase current amplitude and the cosine value of the angle difference of the first phase, and determine the feedback current of the second phase according to the product of the phase current amplitude and the cosine value of the angle difference of the second phase.

[0079] If the sampled current ia of phase A and the sampled current ib of phase B are abnormal, the electrical angle θa of phase A and the electrical angle θb of phase B are obtained respectively. Then, the angle difference Δθa = θ0 - θa of phase A and the angle difference Δθb = θ0 - θb of phase B are determined respectively. Subsequently, the feedback current ia' of phase A can be determined according to ia' = Icos(θ0 - θa), and the feedback current ib' of phase B can be determined according to ib' = Icos(θ0 - θb).

[0080] Similarly, if the sampled current ib of phase B and the sampled current ic of phase C are abnormal, the electrical angle θb of phase B and the electrical angle θc of phase C are obtained respectively. Then, the angle difference Δθb = θ0 - θb of phase B and the angle difference Δθc = θ0 - θc of phase C are determined respectively. Subsequently, the feedback current ia' of phase B can be determined according to ib' = Icos(θ0 - θb), and the feedback current ic' of phase C can be determined according to ic' = Icos(θ0 - θc).

[0081] Similarly, if the sampled current ia of phase A and the sampled current ic of phase C are abnormal, the electrical angles θa of phase A and θc of phase C are obtained respectively. Then, the angle difference Δθa = θ0 - θa of phase A and the angle difference Δθc = θ0 - θc of phase C are determined respectively. Subsequently, the feedback current ia' of phase A can be determined according to ia' = Icos(θ0 - θa), and the feedback current ic' of phase C can be determined according to ic' = Icos(θ0 - θc).

[0082] The current sampling method of the three-phase motor drive circuit 1 described above obtains the electrical angle of the first phase and the electrical angle of the second phase respectively, determines the angle difference of the first phase according to the electrical angle of the motor 2 and the electrical angle of the first phase, and determines the angle difference of the second phase according to the electrical angle of the motor 2 and the electrical angle of the second phase. Thus, the feedback current of the first phase is determined according to the product of the phase current amplitude and the cosine value of the angle difference of the first phase, and the feedback current of the second phase is determined according to the product of the phase current amplitude and the cosine value of the angle difference of the second phase. Subsequently, the motor 2 can be closed-loop controlled according to the feedback current of the first phase, the feedback current of the second phase, and the sampled current of the third phase, driving the motor 2 to operate normally to provide electric assistance.

[0083] In one embodiment, the current sampling method of the three-phase motor drive circuit 1 may further include: the step of obtaining the duty cycle of the driving signal of the upper bridge arm of the third phase. The driving signal of the upper bridge arm of the third phase refers to the signal output from the end where the upper bridge arm of the third phase is respectively connected to the motor 2 and the lower bridge arm. Based on this, the above step S202, obtaining the sampled current of the third phase, may include: obtaining the sampled current of the third phase when the duty cycle is less than a preset duty cycle threshold. The preset duty cycle threshold is used to measure the accuracy of the sampled current of the third phase, and the preset duty cycle threshold is preset and can be determined through experiments according to the actual application scenario. Exemplarily, the preset duty cycle threshold is less than or equal to 85%.

[0084] It can be understood that if the duty cycle of the driving signal of the upper bridge arm of the third phase is less than the preset duty cycle threshold, it indicates that the accuracy of the sampled current of the third phase obtained is relatively high, that is, the error of the sampled current of the third phase is relatively small. In this case, the sampled current of the third phase can be used to estimate the feedback currents of the first phase and the second phase. If the duty cycle of the driving signal of the upper bridge arm of the third phase is greater than or equal to the preset duty cycle threshold, it indicates that the accuracy of the sampled current of the third phase obtained is relatively low, that is, the error of the sampled current of the third phase is relatively large. In this case, the sampled current of the third phase is regarded as unavailable.

[0085] The current sampling method of the above three-phase motor drive circuit 1 determines the accuracy of the sampling current of the third phase by obtaining the duty cycle of the drive signal of the third-phase upper bridge arm and comparing the duty cycle of the drive signal of the third-phase upper bridge arm with a preset duty cycle threshold. Since the current flowing through the sampling resistor of the third phase is fixed, when the duty cycle of the drive signal of the third-phase upper bridge arm is relatively large, the accuracy of the sampling current of the third phase is not high, the error is large, and even the current cannot be sampled. Therefore, in this application, the sampling current of the third phase is obtained when the duty cycle is less than the preset duty cycle threshold, so as to improve the accuracy of the sampling current of the third phase, and thus improve the accuracy of estimating the feedback current of the first phase and the feedback current of the second phase using the sampling current of the third phase.

[0086] In one embodiment, the current sampling method of the three-phase motor drive circuit 1 may further include: determining that the sampling current of the phase corresponding to the first sampling resistor is abnormal when the first sampling resistor is short-circuited. Wherein, the first sampling resistor is one of the three-phase sampling resistors. Exemplarily, the voltages at both ends of the sampling resistor can be obtained respectively. When the voltages at both ends of the sampling resistor are the same, it can be determined that the sampling resistor is short-circuited. Based on this, when any two-phase sampling resistors are short-circuited, the feedback currents of these two phases can be estimated based on the current sampling method of the three-phase motor drive circuit 1 provided in the embodiments of the present application, and the current closed-loop control of the motor 2 can be maintained, and the motor 2 can be driven to continue running to provide assistance.

[0087] In one embodiment, as Figure 1 shown, the three-phase motor drive circuit 1 further includes a detection circuit 10. The detection circuit 10 is respectively connected to both ends of each phase sampling resistor to form a sampling path, and the detection circuit 10 is used to respectively obtain the voltages at both ends of each phase sampling resistor. Based on this, the sampling current corresponding to each phase can be determined according to the voltage at both ends of each phase sampling resistor obtained by the detection circuit 10 and the resistance value of the sampling resistor. In the algorithm for obtaining the three-phase sampling current, for the three-phase sampling resistor scheme, the current of the low-end resistor with a smaller duty cycle of two phases (the three-phase duty cycles are compared in real time) can be sampled, and then according to Kirchhoff's current law ia + ib + ic = 0, the third-phase current can be inferred, and the three-phase current in the full range of duty cycles (0 - 100%) can be obtained, improving the voltage utilization rate.

[0088] Based on the above, the current sampling method of the three-phase motor drive circuit 1 may further include: determining that the sampling current of the phase corresponding to the second sampling resistor is abnormal when at least one sampling path of the second sampling resistor is open, or when the two sampling paths of the second sampling resistor are short-circuited. Wherein, the second sampling resistor is one of the three-phase sampling resistors. It can be understood that when at least one sampling path of the sampling resistor is open, or when the two sampling paths of the second sampling resistor are short-circuited, the detection circuit 10 cannot successfully obtain the voltage across the sampling resistor, and thus cannot obtain the sampling current of this phase. Therefore, when the sampling paths of the sampling resistors of any two phases are abnormal (open or short-circuited), the feedback currents of these two phases can be estimated based on the current sampling method of the three-phase motor drive circuit 1 provided in the embodiments of the present application, maintaining the current closed-loop control of the motor 2 and driving the motor 2 to continue running to provide assistance.

[0089] In one embodiment, the current sampling method of the three-phase motor drive circuit 1 may further include: controlling the working state of the three-phase motor drive circuit 1 to drive the motor 2 to move according to the feedback current of the first phase, the feedback current of the second phase, and the sampling current of the third phase. Based on this, performing current closed-loop control on the motor 2 according to the feedback current of the first phase, the feedback current of the second phase, and the sampling current of the third phase, and driving the motor 2 to continue running, can continue to provide assistance to the steer-by-wire system, avoiding the driving failure of the motor 2 due to abnormal sampling currents of two phases, resulting in the motor 2 stopping running and losing assistance, and improving the operability and the driver's maneuverability.

[0090] In one embodiment, as Figure 5 shown, a current sampling method of a three-phase motor drive circuit 1 is provided. Taking this method applied to the Figure 1 shown three-phase motor drive circuit 1 as an example, this method includes the following steps S502 to step S516.

[0091] S502: Obtain the duty cycle of the driving signal of the upper bridge arm of the third phase when any two-phase sampling resistors are short-circuited, and / or when the sampling paths of any two-phase sampling resistors are abnormal (open or short-circuited).

[0092] S504: When the duty cycle is less than a preset duty cycle threshold, respectively obtain the sampling current of the third phase and the electrical angle of the motor 2.

[0093] S506: Obtain the electrical angle of the third phase.

[0094] S508: Determine the angle difference of the third phase according to the electrical angle of the motor and the electrical angle of the third phase.

[0095] S510: Determine the phase current amplitude according to the ratio of the sampling current of the third phase to the cosine value of the angle difference of the third phase.

[0096] S512: Obtain the electrical angle of the first phase and the electrical angle of the second phase respectively.

[0097] S514: Determine the angle difference of the first phase according to the electrical angle of the motor and the electrical angle of the first phase, and determine the angle difference of the second phase according to the electrical angle of the motor and the electrical angle of the second phase.

[0098] S516: Determine the feedback current of the first phase according to the product of the phase current amplitude and the cosine value of the angle difference of the first phase, and determine the feedback current of the second phase according to the product of the phase current amplitude and the cosine value of the angle difference of the second phase.

[0099] Exemplarily, if the detection circuit 10 detects that the sampling resistor Ra of phase A is short-circuited and one sampling path of the sampling resistor Rb of phase B is open-circuited, and determines that the sampling current ia of phase A and the sampling current ic of phase B are abnormal. In this case, obtain the electrical angle θ0 of the motor 2, the sampling current ic of phase C, and the electrical angles θa, θb, θc of each phase respectively. For example, θa = 0, θb = 2π / 3, θc = 4π / 3. Then, based on the symmetry of the three-phase current, determine the phase current amplitude I according to the formula ic = Icos(θ0 - 4π / 3). Subsequently, determine the feedback current ia' of phase A according to the formula ia' = Icos(θ0), and determine the feedback current ib' of phase B according to the formula ib' = Icos(θ0 - 2π / 3).

[0100] Another exemplarily, if the detection circuit 10 detects that the sampling current ib of phase B and the sampling current ic of phase C are abnormal. In this case, obtain the electrical angle θ0 of the motor 2, the sampling current ia of phase A, and the electrical angles θa, θb, θc of each phase respectively. For example, θa = 0, θb = 2π / 3, θc = 4π / 3. Then, based on the symmetry of the three-phase current, determine the phase current amplitude I according to the formula ia = Icos(θ0). Subsequently, determine the feedback current ib' of phase B according to the formula ib' = Icos(θ0 - 2π / 3), and determine the feedback current ic' of phase C according to the formula ic' = Icos(θ0 - 4π / 3).

[0101] Yet another exemplarily, if the detection circuit 10 detects that the sampling current ia of phase A and the sampling current ic of phase C are abnormal. In this case, obtain the electrical angle θ0 of the motor 2, the sampling current ib of phase B, and the electrical angles θa, θb, θc of each phase respectively. For example, θa = 0, θb = 2π / 3, θc = 4π / 3. Then, based on the symmetry of the three-phase current, determine the phase current amplitude I according to the formula ib = Icos(θ0 - 2π / 3). Subsequently, determine the feedback current ia' of phase A according to the formula ia' = Icos(θ0), and determine the feedback current ic' of phase C according to the formula ic' = Icos(θ0 - 4π / 3).

[0102] For the current sampling method of the above three-phase motor drive circuit 1, when any two of the three-phase sampling resistors are short-circuited or the corresponding path circuits are short-circuited / opened, the feedback currents of the abnormal two phases can be estimated through the sampling current of the third phase, and the motor 2 can be continuously assisted within a limited assistance range. At the same time of reducing the hardware cost (without adding hardware components), the current sampling function of the steer-by-wire system can meet the requirements of functional safety ASIL D.

[0103] Based on the same inventive concept, the embodiment of the present application also provides a steer-by-wire system for implementing the current sampling method of the above-mentioned three-phase motor drive circuit. The solution for solving the problem provided by the steer-by-wire system is similar to the solution described in the above method. Therefore, the specific limitations in one or more embodiments of the steer-by-wire system provided below can refer to the limitations on the current sampling method of the three-phase motor drive circuit in the foregoing text, and will not be repeated here.

[0104] In one embodiment, as Figure 6 shown, a steer-by-wire system is provided. The steer-by-wire system includes: a motor 2, a three-phase motor drive circuit 1, and a control circuit 3. Among them, the motor 2 is used to provide assistance for the steer-by-wire system, that is, the motor 2 is an assist steering motor. The three-phase motor drive circuit 1 is connected to the motor 2, and the three-phase motor drive circuit 1 is used to drive the motor 2 to move to provide assistance for the steer-by-wire system. The specific structure of the three-phase motor drive circuit 1 can refer to the content of the foregoing related embodiments, and will not be repeated here. The control circuit 3 is connected to the three-phase motor drive circuit 1. Exemplarily, the control circuit 3 is respectively connected to the three-phase bridge arms of the three-phase motor drive circuit 1. Exemplarily, taking Figure 1 the three-phase motor drive circuit 1 shown as an example, the control circuit 3 is respectively connected to the gates of the switching tubes M1~M6. The control circuit 3 is used for: when any two of the three-phase sampling currents in the lower bridge arm of the three-phase motor drive circuit 1 are abnormal, respectively obtaining the sampling current of the third phase and the electrical angle of the motor 2, and determining the phase current amplitude according to the sampling current of the third phase and the electrical angle of the motor 2, and determining the feedback current of the first phase and the feedback current of the second phase according to the phase current amplitude and the electrical angle of the motor 2.

[0105] Exemplarily, as Figure 7As shown in the figure, the steer-by-wire system may further include: an Electronic Control Unit (ECU), an angular displacement sensor, and a road feel simulation motor. The working principle of the steer-by-wire system is as follows: When the driver has a steering requirement, the steering wheel will be rotated. The direct-drive road feel simulation motor under the steering wheel will provide the resistance of steering according to the vehicle condition parameters to simulate the road steering feeling during mechanical steering. At the same time, the ECU control system will collect the information from various sensors of the SBW, analyze and process it, and then transfer it to the logic calculation unit inside the ECU. After calculation by the internal control algorithm, the desired torque will be output to the power steering motor, and the power steering motor will drive the tie rod and the wheels to complete the steer-by-wire operation.

[0106] For the above-mentioned steer-by-wire system, when any two of the three-phase sampling currents in the lower arm of the three-phase motor drive circuit 1 are abnormal through the control circuit 3, the sampling current of the third phase and the electrical angle of the motor 2 are respectively obtained. The phase current amplitude is determined according to the sampling current of the third phase and the electrical angle of the motor 2. The feedback current of the first phase and the feedback current of the second phase are determined according to the phase current amplitude and the electrical angle of the motor 2. Since the currents output by the three-phase lower arm are all related to the electrical angle of the motor 2, and the current amplitudes output by the two abnormal lower arms are respectively related to the phase current amplitude of the third phase. Therefore, after determining the phase current amplitude through the sampling current of the third phase and the electrical angle of the motor 2 in this application, the feedback currents of the other two phases can be estimated respectively according to the electrical angle and the phase current amplitude of the motor 2. Then, the motor 2 can be continuously driven to provide assistance according to the feedback currents of the two phases and the sampling current of the third phase, avoiding the driving failure of the motor 2 due to the abnormality of the two-phase sampling currents, resulting in the motor 2 stopping running and losing assistance, and without the need to additionally increase hardware components, the driving requirements of the motor 2 can be met, reducing the hardware cost.

[0107] In one embodiment, the control circuit 3 is used to: obtain the electrical angle of the third phase, determine the angle difference of the third phase according to the electrical angle of the motor 2 and the electrical angle of the third phase, and determine the phase current amplitude according to the ratio of the sampling current of the third phase to the cosine value of the angle difference of the third phase.

[0108] In one embodiment, the control circuit 3 is used to: respectively obtain the electrical angle of the first phase and the electrical angle of the second phase, determine the angle difference of the first phase according to the electrical angle of the motor 2 and the electrical angle of the first phase, and determine the angle difference of the second phase according to the electrical angle of the motor 2 and the electrical angle of the second phase. Determine the feedback current of the first phase according to the product of the phase current amplitude and the cosine value of the angle difference of the first phase, and determine the feedback current of the second phase according to the product of the phase current amplitude and the cosine value of the angle difference of the second phase.

[0109] In one embodiment, the control circuit 3 is further configured to obtain the duty cycle of the driving signal of the third-phase upper bridge arm, and obtain the sampled current of the third phase when the duty cycle is less than a preset duty cycle threshold.

[0110] In one embodiment, the control circuit 3 is further configured to determine that the sampled current of the phase corresponding to the first sampling resistor is abnormal when the first sampling resistor is short-circuited; wherein, the first sampling resistor is one of the three-phase sampling resistors.

[0111] In one embodiment, the control circuit 3 is further connected to the detection circuit 10 of the three-phase motor drive circuit 1. The control circuit 3 is further configured to determine that the sampled current of the phase corresponding to the second sampling resistor is abnormal when at least one sampling path of the second sampling resistor is open-circuited, or when two sampling paths of the second sampling resistor are short-circuited; wherein, the second sampling resistor is one of the three-phase sampling resistors. Exemplarily, the detection circuit 10 of the three-phase motor drive circuit 1 and the control circuit 3 are integrated in the same device. As Figure 8 shown, the detection circuit 10 and the control circuit 3 are integrated in the same three-phase motor drive chip 4. The three-phase motor drive chip 4 is configured with multiple ports (including GH1~GH3, GL1~GL3, ISN1~ISN3, ISP1~ISP3), and the multiple ports are respectively connected to the gates of the respective switching transistors M1~M6, and both ends of the three-phase sampling resistors Ra, Rb, Rb are respectively connected correspondingly. In this way, the integration degree of the steer-by-wire system is improved.

[0112] In one embodiment, the control circuit 3 is further configured to control the operating state of the three-phase motor drive circuit 1 to drive the motor 2 to move according to the feedback current of the first phase, the feedback current of the second phase, and the sampled current of the third phase.

[0113] Based on the same inventive concept, the embodiment of the present application further provides a current sampling device for the three-phase motor drive circuit 1 for implementing the above method. The solution provided by the current sampling device of the three-phase motor drive circuit 1 for solving the problem is similar to the solution described in the above method. Therefore, the specific limitations in one or more of the following device embodiments can refer to the limitations on the current sampling method of the three-phase motor drive circuit 1 above, and will not be repeated here.

[0114] In one embodiment, as Figure 9As shown, a current sampling device 900 for a three-phase motor drive circuit 1 is provided. This device can be applied to the three-phase motor drive circuit 1 provided in any of the foregoing embodiments. The device includes an acquisition module 901 and a determination module 902. Among them, the acquisition module 901 is configured to respectively acquire the sampling current of the third phase and the electrical angle of the motor 2 when any two of the three-phase sampling currents in the lower bridge arm of the three-phase motor drive circuit 1 are abnormal. Among them, the three-phase motor drive circuit 1 is connected to the motor 2 and is used to drive the motor 2 to operate. The determination module 902 is configured to determine the phase current amplitude according to the sampling current of the third phase and the electrical angle of the motor 2, and determine the feedback current of the first phase and the feedback current of the second phase according to the phase current amplitude and the electrical angle of the motor 2.

[0115] In one embodiment, the acquisition module 901 is configured to acquire the electrical angle of the third phase. The determination module 902 is configured to determine the angle difference of the third phase according to the electrical angle of the motor 2 and the electrical angle of the third phase, and determine the phase current amplitude according to the ratio of the sampling current of the third phase to the cosine value of the angle difference of the third phase.

[0116] In one embodiment, the acquisition module 901 is configured to respectively acquire the electrical angle of the first phase and the electrical angle of the second phase. The determination module 902 is configured to determine the angle difference of the first phase according to the electrical angle of the motor 2 and the electrical angle of the first phase, and determine the angle difference of the second phase according to the electrical angle of the motor 2 and the electrical angle of the second phase. The feedback current of the first phase is determined according to the product of the phase current amplitude and the cosine value of the angle difference of the first phase, and the feedback current of the second phase is determined according to the product of the phase current amplitude and the cosine value of the angle difference of the second phase.

[0117] In one embodiment, the acquisition module 901 is further configured to acquire the duty cycle of the drive signal of the upper bridge arm of the third phase, and acquire the sampling current of the third phase when the duty cycle is less than a preset duty cycle threshold.

[0118] In one embodiment, the determination module 902 is further configured to determine that the sampling current of the phase corresponding to the first sampling resistor is abnormal when the first sampling resistor is short-circuited; where the first sampling resistor is one of the three-phase sampling resistors.

[0119] In one embodiment, the determination module 902 is further configured to determine that the sampling current of the phase corresponding to the second sampling resistor is abnormal when at least one sampling path of the second sampling resistor is open, or when the two sampling paths of the second sampling resistor are short-circuited; where the second sampling resistor is one of the three-phase sampling resistors.

[0120] In one embodiment, the current sampling device 900 of the three-phase motor drive circuit 1 further includes a control module, and the control module is configured to control the operating state of the three-phase motor drive circuit 1 according to the feedback current of the first phase, the feedback current of the second phase, and the sampling current of the third phase to drive the motor 2 to move.

[0121] Each module in the current sampling device 900 of the above three-phase motor drive circuit 1 can be implemented in whole or in part by software, hardware, and their combination. The above-mentioned modules can be embedded in the processor of the computer device in hardware form or be independent of it, or be stored in the memory of the computer device in software form, so that the processor can call and execute the operations corresponding to the above-mentioned modules.

[0122] In one embodiment, a computer device is provided. The computer device can be a server, and its internal structure diagram can be as Figure 10 shown. The computer device includes a processor, a memory, and a network interface connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store data such as sampling current, feedback current, and electrical angle. The network interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, it implements a current sampling method for the three-phase motor drive circuit 1.

[0123] Those skilled in the art can understand that Figure 10 the structure shown in

[0124] is only a block diagram of some structures related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine some components, or have different component arrangements.

[0125] In one embodiment, a computer device is provided, including a memory and a processor. A computer program is stored in the memory, and when the processor executes the computer program, it implements the steps of the current sampling device of the three-phase motor drive circuit 1 provided in any of the foregoing embodiments.

[0126] In one embodiment, a computer program product is provided, including a computer program which, when executed by a processor, implements the steps of the current sampling device of the three-phase motor drive circuit 1 provided in any of the foregoing embodiments.

[0127] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties.

[0128] Those of ordinary skill in the art can understand that all or part of the processes of implementing the methods in the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above methods. Among them, any reference to a memory, database, or other medium used in the embodiments provided in this application can include at least one of non-volatile and volatile memories. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc. The databases involved in the embodiments provided in this application can include at least one of relational databases and non-relational databases. Non-relational databases can include distributed databases based on blockchain, etc., and are not limited thereto. The processors involved in the embodiments provided in this application can be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, data processing logics based on quantum computing, etc., and are not limited thereto.

[0129] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0130] The above-described embodiments merely represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the patent scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the appended claims.

Claims

1. A current sampling method for a three-phase motor drive circuit, characterized in that, The method includes: When any two of the three-phase sampled currents in the lower bridge arm of the three-phase motor drive circuit are abnormal, respectively obtain the sampled current of the third phase and the electrical angle of the motor; wherein, the three-phase motor drive circuit is connected to the motor and is used to drive the motor to operate; Determine the phase current amplitude according to the sampled current of the third phase and the electrical angle of the motor; Determine the feedback current of the first phase and the feedback current of the second phase according to the phase current amplitude and the electrical angle of the motor.

2. The method according to claim 1, characterized in that The determining the phase current amplitude according to the sampled current of the third phase and the electrical angle of the motor includes: Obtain the electrical angle of the third phase; Determine the angle difference of the third phase according to the electrical angle of the motor and the electrical angle of the third phase; Determine the phase current amplitude according to the ratio of the sampled current of the third phase to the cosine value of the angle difference of the third phase.

3. The method according to claim 1, wherein The determining the feedback current of the first phase and the feedback current of the second phase according to the phase current amplitude and the electrical angle of the motor includes: Respectively obtain the electrical angle of the first phase and the electrical angle of the second phase; Determine the angle difference of the first phase according to the electrical angle of the motor and the electrical angle of the first phase, and determine the angle difference of the second phase according to the electrical angle of the motor and the electrical angle of the second phase; Determine the feedback current of the first phase according to the product of the phase current amplitude and the cosine value of the angle difference of the first phase, and determine the feedback current of the second phase according to the product of the phase current amplitude and the cosine value of the angle difference of the second phase.

4. The method according to claim 1, characterized in that The method further includes: Obtain the duty cycle of the drive signal of the upper bridge arm of the third phase; The obtaining the sampled current of the third phase includes: When the duty cycle is less than a preset duty cycle threshold, obtain the sampled current of the third phase.

5. The method according to claim 1, characterized in that, The three-phase motor drive circuit includes a power supply, a three-phase bridge arm, three-phase sampling resistors and a detection circuit. Among them, each upper bridge arm is respectively connected to the positive pole of the power supply and the first end of the corresponding lower bridge arm. Each sampling resistor is respectively connected to the negative pole of the power supply and the second end of the corresponding lower bridge arm. The detection circuit is respectively connected to both ends of each sampling resistor to form a sampling path. The method further includes: When the first sampling resistor is short-circuited, determine that the sampled current of the phase corresponding to the first sampling resistor is abnormal; wherein, the first sampling resistor is one of the three-phase sampling resistors; When at least one sampling path of the second sampling resistor is open, or the two sampling paths of the second sampling resistor are short-circuited, determine that the sampled current of the phase corresponding to the second sampling resistor is abnormal; wherein, the second sampling resistor is one of the three-phase sampling resistors.

6. The method according to claim 1, characterized in that, The method further includes: Control the working state of the three-phase motor drive circuit according to the feedback current of the first phase, the feedback current of the second phase and the sampled current of the third phase to drive the motor to move.

7. A current sampling device for a three-phase motor drive circuit, characterized in that, Includes: An acquisition module, configured to respectively acquire the sampled current of the third phase and the electrical angle of the motor when any two of the three-phase sampled currents of the lower bridge arm of the three-phase motor drive circuit are abnormal; wherein, the three-phase motor drive circuit is connected to the motor and is configured to drive the motor to operate. A determination module, configured to determine the phase current amplitude according to the sampled current of the third phase and the electrical angle of the motor, and determine the feedback current of the first phase and the feedback current of the second phase according to the phase current amplitude and the electrical angle of the motor.

8. A steer-by-wire system, characterized in that, The steer-by-wire system includes: A motor; A three-phase motor drive circuit, connected to the motor and configured to drive the motor to move; A control circuit, connected to the three-phase motor drive circuit, configured to respectively acquire the sampled current of the third phase and the electrical angle of the motor when any two of the three-phase sampled currents of the lower bridge arm of the three-phase motor drive circuit are abnormal; determine the phase current amplitude according to the sampled current of the third phase and the electrical angle of the motor; determine the feedback current of the first phase and the feedback current of the second phase according to the phase current amplitude and the electrical angle of the motor.

9. A computer device, characterized in that, Comprising a memory and a processor, the memory stores a computer program, characterized in that when the processor executes the computer program, the steps of the method according to any one of claims 1 to 6 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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