Fault-tolerant control method for nine-phase uniformly distributed motor

Abstract

The fault-tolerant control method of the nine-phase uniformly distributed motor first diagnoses the number, location and type of faults, and then diagnoses the phase angle between the faulty phases. Finally, according to the relationship between the maximum angle of the faulty phase and 120°, it can be divided into three situations: less than, equal to, and greater than for fault tolerance. When the maximum angle between the faulty phases is less than 120°, the fault tolerance is improved. ° When the maximum angle between the fault phases is equal to 120°, the remaining normal six phases can be equivalent to double three phases for fault-tolerant control; when the maximum angle between the fault phases is greater than 120°, the two phases / four phases adjacent to the fault phase are equivalent to a compensation phase, and the two phases with a phase difference of 120° are added, so that the four-phase / six-phase equivalent can be converted into a three-phase fault-tolerant drive system with a phase difference of 120°. The present invention performs fault-tolerant control according to different faults to ensure the normal operation of the system, which can greatly improve the reliability of the system and is very suitable for high-reliability applications such as aerospace.

Description

Technical Field

[0001] The present invention relates to the field of multi-phase motor control, and in particular to a multi-phase motor fault-tolerant control method. Background Art

[0002] In high-reliability applications, such as manned aerospace, redundancy technology is usually used to improve the reliability of the servo system, but it is accompanied by disadvantages such as increased volume / weight, high control complexity, high cost, and reduced power density. In order to improve the reliability of the key component-motor system while improving the system power density, it is crucial to deeply explore the reliability of the motor body and drive controller, and increase the fault tolerance of the drive system. For a multi-phase motor system, each phase is redundantly backed up in function, which makes the multi-phase motor system have greater internal redundancy, so it has greater potential in terms of reliability. However, for nine-phase motors, research on fault-tolerant control is relatively scarce. Summary of the invention

[0003] The technical problem solved by the present invention is to provide a nine-phase motor fault-tolerant control method to improve the fault-tolerant performance of the nine-phase motor and further improve the robustness of the motor.

[0004] The technical solution of the present invention is: a fault-tolerant control method for a nine-phase uniformly distributed motor, the steps are as follows:

[0005] 1) Diagnose the number, location and type of faults. When there are more than one fault, the phase angle between the fault phases needs to be diagnosed;

[0006] 2) When there is only one fault, the principle of conservation of output power or output torque before and after the fault can be used for fault tolerance, that is, the power or torque output by the remaining eight phases is consistent with that before the fault occurs, and then the amplitude and phase of the remaining phases are calculated; the fault-tolerant control method of step 4) can also be used;

[0007] 3) When the number of faults is more than one, according to the relationship between the maximum fault phase angle and 120°, it can be divided into three situations: less than, equal to, and greater than for fault tolerance control;

[0008] 4) When the maximum angle between the faulty phases of the nine-phase motor is less than 120°, two normal phases with a difference of 40° or 80° from the faulty phase can be used for vector synthesis to be equivalent to the compensation phase, or two phases with a difference of 160° from the faulty phase can be used for vector synthesis to be equivalent to the compensation phase, so as to make up for the loss caused by the faulty phase in output power and output torque, ensure the conservation of power or torque before and after the fault, and achieve the purpose of fault-tolerant control;

[0009] 5) When the maximum angle between the faulty phases of the nine-phase motor is equal to 120° and the number of faults does not exceed three, the remaining normal six phases can be equivalent to double three phases for fault-tolerant control;

[0010] 6) When the maximum angle between the faulty phases of a nine-phase motor is greater than 120°, the normal six phases or four phases of the nine phases can be converted into a three-phase drive system, that is, two normal phases adjacent to the faulty phase by 40° and two normal phases adjacent to the faulty phase by 80° are vector-synthesized to be equivalent to the compensation phase of the faulty phase, or two normal phases adjacent to a faulty phase by 40° are vector-synthesized to be equivalent to the compensation phase of the faulty phase, and at the same time, the other two normal phases with a phase angle difference of 120° from the faulty phase are selected to work, thus forming a three-phase drive system with a phase angle difference of 120°, realizing fault-tolerant control and ensuring the normal operation of the system.

[0011] In step 4), two normal phases with a phase difference of 40° or 80° from the fault phase can be used for vector synthesis to be equivalent to the compensation phase, or two phases with a phase difference of 160° from the fault phase can be used for vector synthesis to be equivalent to the compensation phase, so as to make up for the loss caused by the fault phase in output power and output torque, ensure the conservation of power or torque before and after the fault, and achieve the purpose of fault-tolerant control;

[0012] Taking the fault of phase A as an example, the two phases E and F, which have a phase angle difference of 160°, are used to vector synthesize an equivalent compensation phase to replace phase A. The vector synthesis formula is as follows:

[0013]

[0014] make but

[0015]

[0016]

[0017]

[0018] In this way, the E and F phase vectors can be used to synthesize the fault-tolerant control compensation vector equivalent to the A phase.

[0019] Step 5) A method of changing the nine-phase drive system to a six-phase drive system, that is, using a six-phase drive system consisting of two three-phase drive systems with a phase difference of 40°;

[0020] If at least two of the three phases C, F, and I fail, the remaining phases can be used to form a dual three-phase drive system with a phase difference of 40°, that is, the ADG and BEH dual three-phase drive system.

[0021] Step 6) A method of changing the nine-phase drive system to a four-phase or six-phase drive system is to select two phases separated by 120° from the remaining phases and add two phases separated by 40° from the fault phase to form a four-phase drive system; or to select two phases separated by 120° from the remaining phases, add two phases separated by 40° from the fault phase, and add two phases separated by 80° from the fault phase to form a six-phase drive system.

[0022] Taking the failure of phases A, E, and F as an example, phases D and G are selected as two of the three phases, and phases B and I are used to synthesize the third phase, thus forming a four-phase drive system. The formula for synthesizing the third phase from phases B and I is as follows:

[0023]

[0024] Let U B =U I ,but

[0025]

[0026] In this way, the nine-phase drive system can be changed into a four-phase drive system.

[0027] Taking the failure of phases A, E, and F as an example, select phases D and G as two of the three phases, and use the four phases B, I, C, and H to synthesize the third phase, thus forming a six-phase drive system. The formula for synthesizing the third phase from the four phases B, I, C, and H is as follows:

[0028]

[0029] Let U B =U I =U C =U H ,but

[0030]

[0031] In this way, the nine-phase drive system can be changed into a six-phase drive system.

[0032] The advantages of the present invention over the prior art are: the fault-tolerant control method of the nine-phase uniformly distributed motor of the present invention can greatly improve the fault-tolerant performance and reliability of the nine-phase motor system, and provide a new control method for the fault-tolerant control of the nine-phase motor system. The reliability and service life of the nine-phase motor system and the task completion capability of the nine-phase motor system working in harsh environments are improved, the fault-tolerant potential of the nine-phase motor system is fully tapped, and a more solid insurance measure is added to the use of the nine-phase motor system. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a flow chart of the method of the present invention;

[0034] Figure 2 It is a diagram of two-phase vector synthesis fault-tolerant control;

[0035] Figure 3 It is a diagram of fault-tolerant control of dual three-phase drive system;

[0036] Figure 4 It is a diagram of four-phase vector synthesis fault-tolerant control;

[0037] Figure 5 It is a diagram of six-phase vector synthesis fault-tolerant control. DETAILED DESCRIPTION

[0038] The flow chart of the present invention is attached Figure 1 , the specific steps are as follows:

[0039] 1) Diagnose the number, location and type of faults. When there are more than one fault, the phase angle between the fault phases needs to be diagnosed;

[0040] 2) When there is only one fault, the principle of conservation of output power or output torque before and after the fault can be used for fault tolerance, that is, the power or torque output by the remaining eight phases is consistent with that before the fault occurs, and then the amplitude and phase of the remaining phases are calculated; the fault-tolerant control method of step 4) can also be used;

[0041] 3) When the number of faults is more than one, according to the relationship between the maximum fault phase angle and 120°, it can be divided into three situations: less than, equal to, and greater than for fault tolerance control;

[0042] 4) When the maximum angle between the faulty phases of the nine-phase motor is less than 120°, two normal phases with a difference of 40° or 80° from the faulty phase can be used for vector synthesis to be equivalent to the compensation phase, or two phases with a difference of 160° from the faulty phase can be used for vector synthesis to be equivalent to the compensation phase, so as to make up for the loss caused by the faulty phase in output power and output torque, ensure the conservation of power or torque before and after the fault, and achieve the purpose of fault-tolerant control;

[0043] 5) When the maximum angle between the faulty phases of the nine-phase motor is equal to 120° and the number of faults does not exceed three, the remaining normal six phases can be equivalent to double three phases for fault-tolerant control;

[0044] 6) When the maximum angle between the faulty phases of a nine-phase motor is greater than 120°, the normal six phases or four phases of the nine phases can be converted into a three-phase drive system, that is, two normal phases adjacent to the faulty phase by 40° and two normal phases adjacent to the faulty phase by 80° are vector-synthesized to be equivalent to the compensation phase of the faulty phase, or two normal phases adjacent to a faulty phase by 40° are vector-synthesized to be equivalent to the compensation phase of the faulty phase, and at the same time, the other two normal phases with a phase angle difference of 120° from the faulty phase are selected to work, thus forming a three-phase drive system with a phase angle difference of 120°, realizing fault-tolerant control and ensuring the normal operation of the system.

[0045] In step 4), two normal phases with a phase difference of 40° or 80° from the fault phase can be used for vector synthesis to be equivalent to the compensation phase, or two phases with a phase difference of 160° from the fault phase can be used for vector synthesis to be equivalent to the compensation phase, so as to make up for the loss caused by the fault phase in output power and output torque, ensure the conservation of power or torque before and after the fault, and achieve the purpose of fault-tolerant control;

[0046] Take the fault of phase A as an example. Figure 2 As shown, the E phase and F phase, which have a phase angle difference of 160°, are used to vector-synthesize an equivalent compensation phase to replace the A phase. The vector synthesis formula is as follows:

[0047]

[0048] make but

[0049]

[0050]

[0051]

[0052] In this way, the E and F phase vectors can be used to synthesize the fault-tolerant control compensation vector equivalent to the A phase.

[0053] Step 5) A method of changing the nine-phase drive system to a six-phase drive system, that is, using a six-phase drive system consisting of two three-phase drive systems with a phase difference of 40°;

[0054] If at least two of the three phases C, F, and I fail, Figure 3 As shown, the remaining phases can be used to form a dual three-phase drive system with a phase difference of 40°, that is, an ADG and BEH dual three-phase drive system.

[0055] Step 6) A method of changing the nine-phase drive system to a four-phase or six-phase drive system is to select two phases separated by 120° from the remaining phases and add two phases separated by 40° from the fault phase to form a four-phase drive system; or to select two phases separated by 120° from the remaining phases, add two phases separated by 40° from the fault phase, and add two phases separated by 80° from the fault phase to form a six-phase drive system.

[0056] Take the failure of phases A, E, and F as an example. Figure 4 As shown, phases D and G are selected as two of the three phases, and phases B and I are used to synthesize the third phase, thus forming a four-phase drive system. The formula for synthesizing the third phase from phases B and I is as follows:

[0057]

[0058] Let U B =U I ,but

[0059]

[0060] In this way, the nine-phase drive system can be changed into a four-phase drive system.

[0061] Take the failure of phases A, E, and F as an example. Figure 5 As shown, phases D and G are selected as two of the three phases, and the four phases B, I, C, and H are used to synthesize the third phase, thus forming a six-phase drive system. The formula for synthesizing the third phase from the four phases B, I, C, and H is as follows:

[0062]

[0063] Let U B =U I =U C =U H ,but

[0064]

[0065] In this way, the nine-phase drive system can be changed into a six-phase drive system.

[0066] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A fault-tolerant control method for a nine-phase uniformly distributed motor, characterized by the following steps: 1) Diagnose the number, location and type of faults. When there are more than one fault, the phase angle between the fault phases needs to be diagnosed; 2) When there is only one fault, the principle of output power conservation or output torque conservation before and after the fault is adopted for fault tolerance, that is, the power or torque output by the remaining eight phases is consistent with that before the fault occurs, and then the amplitude and phase of the remaining phases are calculated; 3) When the number of faults is more than one, fault tolerance control is performed according to the relationship between the maximum fault phase angle and 120°, which is divided into three situations: less than, equal to, and greater than; 4) When the maximum angle between the faulty phases of the nine-phase motor is less than 120°, two normal phases with a difference of 40° or 80° from the faulty phase are used for vector synthesis to be equivalent to the compensation phase, or two phases with a difference of 160° from the faulty phase are used for vector synthesis to be equivalent to the compensation phase, so as to make up for the loss caused by the faulty phase in output power and output torque, ensure the conservation of power or torque before and after the fault, and achieve the purpose of fault-tolerant control; 5) When the maximum angle between the faulty phases of the nine-phase motor is equal to 120° and the number of faults does not exceed three, the remaining normal six phases are equivalent to double three phases for fault-tolerant control; 6) When the maximum angle between the faulty phases of a nine-phase motor is greater than 120°, the normal six phases or four phases of the nine phases are converted into a three-phase drive system, that is, two normal phases adjacent to the faulty phase by 40° and two normal phases adjacent to the faulty phase by 80° are vector-synthesized to be equivalent to the compensation phase of the faulty phase, or two normal phases adjacent to a faulty phase by 40° are vector-synthesized to be equivalent to the compensation phase of the faulty phase; at the same time, two other normal phases with a phase difference of 120° from the faulty phase are selected to work, thus forming a three-phase drive system with a phase angle difference of 120°, realizing fault-tolerant control and ensuring the normal operation of the system.

2. The fault-tolerant control method of a nine-phase uniformly distributed motor according to claim 1, characterized in that: In step 4), two normal phases with a phase difference of 40° or 80° from the fault phase are used for vector synthesis to be equivalent to the compensation phase, or two phases with a phase difference of 160° from the fault phase are used for vector synthesis to be equivalent to the compensation phase, so as to make up for the loss caused by the fault phase in output power and output torque, ensure the conservation of power or torque before and after the fault, and achieve the purpose of fault-tolerant control; When phase A fails, phase E and phase F, which have a phase angle difference of 160°, are used to synthesize an equivalent compensation phase to replace phase A.

3. The fault-tolerant control method of a nine-phase uniformly distributed motor according to claim 1, characterized in that: Step 5) includes using a six-phase drive system consisting of dual three-phase drive systems with a phase difference of 40°.

4. The fault-tolerant control method of a nine-phase uniformly distributed motor according to claim 1, characterized in that: The step of converting the normal six phases or the selected four phases of the nine phases into a three-phase drive system in step 6) includes selecting two phases separated by 120° from the remaining phases and adding two phases separated by 40° from the fault phase to form a four-phase drive system; or selecting two phases separated by 120° from the remaining phases, adding two phases separated by 40° from the fault phase, and adding two phases separated by 80° from the fault phase to form a six-phase drive system.

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