Self-healing fault-tolerant control method for three-phase motor current sensor fault

Abstract

The invention provides a three-phase motor current sensor fault self-healing fault-tolerant control method, and belongs to the field of motor fault-tolerant control. According to the method, when the current sensor has a fault, the error current caused by the fault is accurately identified by collecting the current of each phase and representing the current in a dq coordinate system. Processing the error current by using a wave trap, eliminating an alternating-current component, and ensuring that the d-axis has no error current and the q-axis only has a residual direct-current component; and finally, compensating a q-axis residual direct current component through rotating speed outer ring adjustment to avoid interference to motor operation. According to the method, the fault type or position does not need to be positioned, the self-healing fault-tolerant control is realized, the misdiagnosis risk is reduced, and the control process is simplified. Meanwhile, according to the method, a fault diagnosis stage is omitted, a passive fault-tolerant mode is adopted, and the fault-tolerant control efficiency is effectively improved. Besides, the method is wide in application range and can be popularized to a motor control system of an N * three-phase structure, and a new solution is provided for the field of motor fault-tolerant control.

Description

Technical Field

[0001] The invention relates to the field of motor fault-tolerant control, and in particular to a self-healing fault-tolerant control method for a three-phase motor current sensor fault. Background Art

[0002] As an indispensable key component for the operation of three-phase motors, current sensors monitor the current of each phase of the motor to ensure that the motor can operate stably according to the predetermined control strategy. The current information provided by the current sensor is crucial for achieving precise motor control, which is directly related to the motor's torque output, efficiency, and operating stability.

[0003] However, current sensors may encounter a variety of faults in actual applications, such as disconnection, jamming, offset, and gain change. Once these faults occur, they will directly affect the accuracy of the current signal, which will in turn bring a series of negative effects to the operation of the three-phase motor. Specifically, a current sensor failure may cause a significant increase in the motor torque pulsation, which will not only reduce the motor's operating efficiency, but may also cause mechanical vibration and noise, affecting the motor's service life. At the same time, the fault may also cause an increase in the harmonic components of the current, which will not only interfere with the normal operation of the motor, but may also pollute the power grid and affect the normal operation of other equipment.

[0004] For current sensor faults, most existing fault-tolerant control methods follow the process of first locating the fault and then performing fault-tolerant control. Although this method can achieve fault-tolerant control to a certain extent, it has many shortcomings. First, the fault location process is often complicated and time-consuming, which increases the overall complexity of fault-tolerant control. Secondly, the accuracy of fault location directly determines the effect of fault-tolerant control. Once the positioning is deviated, it may cause misdiagnosis, resulting in the failure of the fault-tolerant control strategy, and may even aggravate the fault of the motor.

[0005] In order to overcome the shortcomings of existing fault-tolerant control methods, reduce control complexity, and avoid the risk of misdiagnosis, the present invention proposes a self-healing fault-tolerant control method for a three-phase motor current sensor fault. Summary of the invention

[0006] The purpose of the present invention is to overcome the above-mentioned defects in the background technology and provide a self-healing fault-tolerant control method for a three-phase motor current sensor fault. The method aims to achieve instant response and effective fault tolerance to current sensor faults through a more intelligent and adaptive control strategy, thereby ensuring that the three-phase motor can still maintain stable operation in the event of a current sensor fault.

[0007] The present invention adopts the following technical solutions to solve the above technical problems:

[0008] A self-healing fault-tolerant control method for a three-phase motor current sensor fault specifically comprises the following steps:

[0009] Step S1: When the current sensor of the three-phase motor fails, collect the current i of each phase n , where i n It is represented by the current i under healthy condition. n.H The error current i caused by the fault n.F sum;

[0010] Step S2: Express the current in the dq coordinate system and identify the d-axis error current i caused by the fault d.F and q-axis error current i q.F ;

[0011] Step S3: using a notch filter to suppress the dq axis error current, eliminating the AC part of the error current, and ensuring that the d axis does not contain the error current and only a DC part remains in the q axis;

[0012] Step S4: Compensate the remaining DC amount in the q-axis through the regulation of the speed outer ring to ensure that this part of the DC amount no longer affects the operation of the motor;

[0013] Step S5: Implementing self-healing fault-tolerant control of the three-phase motor after a current sensor failure, without locating the fault type or fault location.

[0014] Furthermore, in step S1, the current i of each phase is collected n The expression is

[0015] i n =i n.H +i n.F ,n=A,B,C

[0016] Where n is A, B, C phase.

[0017] Furthermore, the current i collected in the healthy state in step S1 is n.H The expression is

[0018]

[0019] Among them, I m is the maximum phase current, ω is the motor angular velocity, and λ is the corresponding angle of A, B, and C.

[0020] Furthermore, in step S1, the error current i caused by the fault is collected n.F The expression is

[0021]

[0022] Among them, k is the gain constant, c is the offset constant; when the sensor works normally, k=0, c=0; when the sensor gain fails, k>0 or k<0, c=0; when the sensor offset fails, k=0, c>0 or c<0; when the sensor is stuck, k=-1, c>0 or c<0; when the sensor is disconnected, k=-1, c=0.

[0023] Furthermore, the dq axis current expression in the dq coordinate system in step S2 is:

[0024]

[0025] During normal operation, i d.F andi q.F All are 0;

[0026] After a current sensor failure occurs, the expression for the error current is:

[0027]

[0028] Among them, A q , B d , B q , C d , C q , D d , D q , E d , E q is a constant, and its specific value is related to the location of the fault.

[0029] Furthermore, the notch filters in step S3 include notch filter 1 and notch filter 2, and their transfer functions are respectively designed as:

[0030] Notch filter 1:

[0031]

[0032] Notch filter 2:

[0033]

[0034] where ω e It is the electrical angular velocity, which is obtained by resolver sampling to ensure that the error current of a specific frequency is effectively suppressed.

[0035] Furthermore, in step S3, after the dq axis error current passes through the trap 1 and the trap 2, the expression becomes:

[0036]

[0037] Compared with the prior art, the present invention adopts the above technical solution and has the following beneficial effects:

[0038] (1) The self-healing fault-tolerant control method for a three-phase motor current sensor fault proposed in the present invention can realize self-fault-tolerant control after various types of current sensor faults (broken wires, stuck, offset, gain), without the need to locate the fault type and fault location. Unlike the traditional process of first diagnosing and then fault-tolerant, this method can realize fault-tolerant control without the need for fault diagnosis, and there is no risk of misdiagnosis.

[0039] (2) Compared with the traditional fault-tolerant scheme, the fault-tolerant method proposed in the present invention omits the fault diagnosis stage and realizes fault-tolerant control of current sensor faults through passive fault-tolerant means, thereby reducing the computational burden and storage burden and effectively reducing the control complexity.

[0040] (3) The fault-tolerant method proposed in the present invention benefits from the omission of the diagnosis process, thus shortening the time from the occurrence of a fault to the execution of fault-tolerant control, thereby realizing fault-tolerant control more quickly.

[0041] (4) The solution proposed in the present invention can be extended to the motor control of N* three-phase structure, and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a block diagram of the adaptive fault-tolerant control of the present invention;

[0043] Figure 2 is the Bode diagram corresponding to the notch filter 1 of the present invention;

[0044] Figure 3 is the Bode diagram corresponding to the notch filter 2 of the present invention;

[0045] Figure 4 The dq axis current waveform of the present invention without fault tolerance;

[0046] Figure 5 dq axis current waveform in the self-fault-tolerant case of the present invention;

[0047] Figure 6 ABC phase current waveforms in the present invention without fault tolerance;

[0048] Figure 7 ABC phase current waveform in the self-fault-tolerant case of the present invention. DETAILED DESCRIPTION

[0049] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings of the specification. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work are within the scope of protection of the present invention.

[0050] A self-healing fault-tolerant control method for a three-phase motor current sensor fault, the control block diagram of which is as follows: Figure 1 As shown, the specific steps include:

[0051] Step S1: When the current sensor of the three-phase motor fails, collect the current i of each phase n , where i n It is represented by the current i under healthy condition. n.H The error current i caused by the fault n.F sum;

[0052] Step S2: Express the current in the dq coordinate system and identify the d-axis error current i caused by the fault d.F and q-axis error current i q.F ;

[0053] Step S3: using a notch filter to suppress the dq axis error current, eliminating the AC part of the error current, and ensuring that the d axis does not contain the error current and only a DC part remains in the q axis;

[0054] Step S4: Compensate the remaining DC amount in the q-axis through the regulation of the speed outer ring to ensure that this part of the DC amount no longer affects the operation of the motor;

[0055] Step S5: Implementing self-healing fault-tolerant control of the three-phase motor after a current sensor failure, without locating the fault type or fault location.

[0056] Furthermore, in step S1, the current i of each phase is collected n The expression is

[0057] i n =i n.H +i n.F ,n=A,B,C

[0058] Where n is A, B, C phase.

[0059] Furthermore, the current i collected in the healthy state in step S1 is n.H The expression is

[0060]

[0061] Among them, I m is the maximum phase current, ω is the motor angular velocity, and λ is the corresponding angle of A, B, and C.

[0062] Furthermore, in step S1, the error current i caused by the fault is collected n.F The expression is

[0063]

[0064] Among them, k is the gain constant, c is the offset constant; when the sensor works normally, k=0, c=0; when the sensor gain fails, k>0 or k<0, c=0; when the sensor offset fails, k=0, c>0 or c<0; when the sensor is stuck, k=-1, c>0 or c<0; when the sensor is disconnected, k=-1, c=0.

[0065] Furthermore, the dq axis current expression in the dq coordinate system in step S2 is:

[0066]

[0067] During normal operation, i d.F andi q.F All are 0;

[0068] After a current sensor failure occurs, the expression for the error current is:

[0069]

[0070] Among them, A q , B d , B q , C d , C q , D d , D q , E d , E q is a constant, and its specific value is related to the location of the fault. It can be seen that since the dq axis current contains pulsations of the fundamental frequency and twice the fundamental frequency, it will cause torque pulsation, and the three-phase current cannot guarantee symmetry and contains a large number of third and second harmonics.

[0071] Furthermore, the notch filters in step S3 include notch filter 1 and notch filter 2, and their transfer functions are respectively designed as:

[0072] Notch filter 1:

[0073]

[0074] Notch filter 2:

[0075]

[0076] where ω e The electrical angular velocity is obtained by resolver sampling to ensure that the error current of a specific frequency is effectively suppressed. The corresponding notch filter Bode diagram is as follows: Figure 2 , Figure 3 shown.

[0077] Furthermore, in step S3, after the dq axis error current passes through the trap 1 and the trap 2, the expression becomes:

[0078]

[0079] Combination Figure 4-Figure 7 It can be seen that the AC part of the error current caused by the sensor failure no longer exists, and the d-axis no longer contains error current, while only part of the DC amount remains in the q-axis. However, due to the regulation of the speed outer loop, this part of the DC amount will also be compensated and will no longer affect the motor operation.

[0080] The present invention can realize self-fault-tolerant control after various types of current sensor faults (broken wires, stuck, offset, gain), without the need to locate the fault type and fault location. Unlike the traditional process of diagnosing first and then fault tolerance, this method can realize fault-tolerant control without fault diagnosis, thus reducing the risk of misdiagnosis. Compared with the traditional fault-tolerant scheme, since the fault diagnosis stage is omitted, the fault-tolerant control of the current sensor fault is realized by passive fault tolerance, thus effectively reducing the control complexity. Thanks to the omission of the diagnosis process, the time from the occurrence of the fault to the execution of the fault-tolerant control can be shortened, and the fault-tolerant control can be realized faster. The proposed scheme can be extended to the motor control of the N* three-phase structure, and has a wide range of applications.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A self-healing fault-tolerant control method for a three-phase motor current sensor fault, characterized in that: The method specifically comprises the following steps: Step S1: When the current sensor of the three-phase motor fails, collect the current i of each phase n , where i n It is represented by the current i under healthy condition. n.H The error current i caused by the fault n.F sum; Step S2: Express the current in the dq coordinate system and identify the d-axis error current i caused by the fault d.F and q-axis error current i q.F ; Step S3: using a notch filter to suppress the dq axis error current, eliminating the AC part of the error current, and ensuring that the d axis does not contain the error current and only a DC part remains in the q axis; Step S4: Compensate the remaining DC amount in the q-axis through the regulation of the speed outer ring to ensure that this part of the DC amount no longer affects the operation of the motor; Step S5: Implementing self-healing fault-tolerant control of the three-phase motor after a current sensor failure, without locating the fault type or fault location.

2. The self-healing fault-tolerant control method for a three-phase motor current sensor fault according to claim 1, characterized in that: In step S1, the current i of each phase is collected. n The expression is i n =i n.H +i n.F ,n=A,B,C Where n is A, B, C phase.

3. The self-healing fault-tolerant control method for a three-phase motor current sensor fault according to claim 1, characterized in that: In step S1, the current i collected in the healthy state is collected. n.H The expression is Among them, I m is the maximum phase current, ω is the motor angular velocity, and λ is the corresponding angle of A, B, and C.

4. The self-healing fault-tolerant control method for a three-phase motor current sensor fault according to claim 1, characterized in that: In step S1, the error current i caused by the fault is collected. n.F The expression is Among them, k is the gain constant, c is the offset constant; when the sensor works normally, k=0, c=0; when the sensor gain fails, k>0 or k<0, c=0; when the sensor offset fails, k=0, c>0 or c<0; when the sensor is stuck, k=-1, c>0 or c<0; when the sensor is disconnected, k=-1, c=0.

5. The self-healing fault-tolerant control method for a three-phase motor current sensor fault according to claim 1, characterized in that: The dq axis current expression in the dq coordinate system in step S2 is: During normal operation, i d.F andi q.F All are 0; After a current sensor failure occurs, the expression for the error current is: Among them, A q , B d , B q , C d , C q , D d , D q , E d , E q is a constant, and its specific value is related to the location of the fault.

6. The self-healing fault-tolerant control method for a three-phase motor current sensor fault according to claim 1, characterized in that: The notch filters in step S3 include notch filter 1 and notch filter 2, and their transfer functions are respectively designed as: Notch filter 1: Notch filter 2: where ω e It is the electrical angular velocity, which is obtained by resolver sampling to ensure that the error current of a specific frequency is effectively suppressed.

7. The self-healing fault-tolerant control method for a three-phase motor current sensor fault according to claim 1, characterized in that: In step S3, after the dq axis error current passes through the trap 1 and the trap 2, the expression becomes:

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