A Fault Diagnosis Method for Permanent Magnet Synchronous Motor Based on Coding System

Abstract

The present invention discloses a fault diagnosis method for a permanent magnet synchronous motor based on a coding system. The diagnosis method includes three-phase voltage, three-phase current, switching signals of switching tubes, a fault judgment module, a fault type judgment module, and fault type coding. In the motor state, the diagnosis method of the present invention obtains a voltage fault signal through fault judgment on the three-phase voltage, and the switching signals of the switching tubes and the voltage fault signal can be converted into a fault type code I through the fault type judgment module I; in the generator state, on the basis of obtaining the fault type code I by the same motor fault diagnosis method, adding the fault judgment signal of the three-phase current to obtain the fault type code II. The diagnosis method has low cost, is simple and reliable, can achieve full coverage of switching tube faults, and can also be perfectly matched with a fault-tolerant method based on current processing. It can accurately diagnose the current fault situation and obtain the positioning of the switching tube fault at the same time.

Description

Technical Field

[0001] The present invention relates to the technical field of motor drive and control, and specifically to a fault diagnosis method for a permanent magnet synchronous motor based on coding system. Background Art

[0002] In recent years, permanent magnet synchronous motors have received increasing attention due to their advantages such as high efficiency, high torque density, and high power density. When they are applied in the aerospace field, more and more research has been conducted on the integrated starting and generating system of permanent magnet synchronous motors. In the integrated starting and generating system, there are fault conditions in both the motor and generator states. Among them, the open-circuit fault of the switching tube is one of the most common faults. Facing such faults, fault diagnosis is a very important step for maintenance or fault-tolerant control.

[0003] In traditional fault tolerance, when a certain phase fails, this phase is usually directly removed completely and then fault tolerance is carried out, which often results in excessive fault tolerance. A better fault tolerance method can be to implement fault tolerance according to the specific situation of the fault current, which requires that the fault diagnosis should accurately obtain the fault situation of the current. Therefore, a fault diagnosis method for a permanent magnet synchronous motor based on coding system is proposed. Summary of the Invention

[0004] The purpose of the present invention is to provide a fault diagnosis method for a permanent magnet synchronous motor based on coding system. In the motor state, by performing fault judgment on the three-phase voltage to obtain a voltage fault signal, the switching signal of the switching tube and the voltage fault signal can be converted into a fault type code Ⅰ through the fault type judgment module Ⅰ; in the generator state, on the basis of obtaining the fault type code Ⅰ by the same motor fault diagnosis method, adding the fault judgment signal of the three-phase current to obtain a fault type code Ⅱ. The diagnosis method has low cost, is simple and reliable, can achieve full coverage of switching tube faults, and can also be perfectly matched with the fault-tolerant method based on current processing. It can accurately diagnose the current fault situation and also obtain the location of the switching tube fault.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A fault diagnosis method for a permanent magnet synchronous motor based on coding system, the diagnosis method includes three-phase voltage, three-phase current, the switching signal of the switching tube, a fault judgment module, a fault type judgment module, and a fault type code. The three-phase voltage and three-phase current are connected to the fault judgment module, the switching signal of the switching tube and the fault judgment module are connected to the fault type judgment module, and the fault type judgment module is connected to the fault type code.

[0007] Further, the fault judgment module includes a voltage fault judgment module and a current fault judgment module. The voltage fault judgment module is used to judge the faults of the three-phase voltage to obtain a voltage fault signal, and the current fault judgment module is used to judge the faults of the three-phase current to obtain a current fault signal.

[0008] Further, the fault type coding includes fault type coding I and fault type coding II.

[0009] Further, the fault type judgment module includes a fault type judgment module I and a fault type judgment module II. The fault type judgment module I is used to convert the switching signal of the switch tube and the voltage fault signal into the fault type coding I, and the fault type judgment module II is used to convert the fault type coding I and the fault judgment signal of the three-phase current into the fault type coding II.

[0010] Further, the diagnosis method includes the following steps:

[0011] The first step: Set the switch tubes in the open-winding motor model:

[0012] Left (Positive) Inverter Right (Negative) Inverter Upper Switch of Phase A a11 a21 Lower Switch of Phase A a12 a22 Upper Switch of Phase B b11 b21 Lower Switch of Phase B b12 b22 Upper Switch of Phase C c11 c21 Lower Switch of Phase C c12 c22

[0013] Use voltage sensors to measure the voltages of the three phases of motors A, B, and C respectively, and then measure the switching signals of the 6 groups of switch tubes on one side of the inverter in the open-winding model. According to the switching signals and the voltage values, judge whether the values of UA, UB, and UC are within the abnormal range, and obtain a voltage fault signal.

[0014] The second step: After obtaining the fault signal, encode various fault types, and the output signal fault_type is the fault type coding I, to obtain the fault type coding I.

[0015] The coding methods for the faults of phases B and C are the same as that of phase A. In the fault type coding I, C is the first digit, B is the second digit, and A is the third digit. When the fault type coding I is 321, it means that either c11 / c22 is open or both are open, and either c12 / c21 is open or both are open, either b12 / b21 is open or both are open, and either a11 / a22 is open or both are open.

[0016] The third step: For the motor state, each coding of the fault type coding I corresponds to a three-phase current fault condition:

[0017] Fault Type Code I Fault Type of Phase A Current xx0 Phase A Current Normal xx1 First Half Cycle of Phase A Current Missing xx2 Second Half Cycle of Phase A Current Missing xx3 Entire Phase A Current Missing

[0018] Phases B and C are the same as phase A.

[0019] Step 4: For the generator state, when either a11 or a22 is open, the A current is normal; when both a11 and a22 are open, the upper half cycle of the A-phase current is missing. Measure the three-phase current using a current sensor, and combine the fault type code I to perform current fault judgment. Encode according to the fault signal:

[0020] Phase A Code Fault Type 0 Phase A Current Normal 1 First Half Cycle of Phase A Current Missing 2 Second Half Cycle of Phase A Current Missing 3 Entire Phase A Current Missing

[0021] The output signal fault_type_i is the fault type code II. Obtain the fault type code II. The encoding method is the same when faults occur in the B-phase and C-phase. In the fault type code II, C is the first digit, B is the second digit, and A is the third digit:

[0022] Fault Type Code II Fault Type of Phase A Current xx0 Phase A Current Normal xx1 First Half Cycle of Phase A Current Missing xx2 Second Half Cycle of Phase A Current Missing xx3 Entire Phase A Current Missing

[0023] Each encoding of the obtained fault type code II corresponds to a three-phase current fault condition.

[0024] Furthermore, the current fault judgment in the fourth step includes:

[0025] When a fault occurs in the A-phase, assuming the peak value of the A-phase current under normal conditions is Iapp, and the third digit A of the fault type code I is greater than 0, a fault occurrence signal is obtained.

[0026] In the next cycle, detect whether the current is greater than 0.5Iapp or less than -0.5app. When the current is greater than 0.5Iapp, the upper half cycle of the A-phase is missing; when the current is less than -0.5app, the lower half cycle of the A-phase is missing.

[0027] Advantages of the present invention:

[0028] 1. In the motor state, the diagnostic method of the present invention performs fault judgment on the three-phase voltage to obtain a voltage fault signal. Through the fault type judgment module I, the switching signal of the switch tube and the voltage fault signal can be converted into the fault type code I, which can achieve full coverage of switch tube faults;

[0029] 2. In the generator state, on the basis of obtaining the fault type code I by the same motor fault diagnosis method, adding the fault judgment signal of the three-phase current to obtain the fault type code II, the instrument cost used is low, simple and reliable;

[0030] 3. The diagnostic method of the present invention is perfectly coordinated with the fault tolerance method based on current processing, and can accurately diagnose the current fault situation while obtaining the location of the switch tube fault. Description of the Drawings

[0031] The present invention will be further described below with reference to the drawings.

[0032] Figure 1 is the fault diagnosis flow chart of the diagnosis method of the present invention;

[0033] Figure 2 is the fault diagnosis module of the motor and the fault type code Ⅰ;

[0034] Figure 3 is the fault diagnosis module of the generator and the fault type codes Ⅰ and Ⅱ;

[0035] Figure 4 is the open circuit fault set in the motor state;

[0036] Figure 5 is the open circuit fault set in the motor state;

[0037] Figure 6 is the open circuit fault set in the generator state;

[0038] Figure 7 is the open circuit fault set in the generator state;

[0039] Figure 8 is the open circuit fault experiment diagram in the motor state;

[0040] Figure 9 is the open circuit fault experiment diagram in the motor state;

[0041] Figure 10 is the open circuit fault set in the generator state;

[0042] Figure 11 is the open circuit fault experiment diagram in the generator state;

[0043] Figure 12 is the open circuit fault experiment diagram in the generator state. Detailed implementation manners

[0044] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0045] A fault diagnosis method for a permanent magnet synchronous motor based on a coding system, as Figure 1 shown, the diagnosis method includes three-phase voltage, three-phase current, switching signals of switching tubes, a fault judgment module, a fault type judgment module, and a fault type code. The three-phase voltage and the three-phase current are connected to the fault judgment module, the switching signals of the switching tubes and the fault judgment module are connected to the fault type judgment module, and the fault type judgment module is connected to the fault type code.

[0046] The fault judgment module includes a voltage fault judgment module and a current fault judgment module. The voltage fault judgment module is used to judge the faults of the three-phase voltage to obtain a voltage fault signal, and the current fault judgment module is used to judge the faults of the three-phase current to obtain a current fault signal.

[0047] The fault type coding includes fault type coding Ⅰ and fault type coding Ⅱ.

[0048] The fault type judgment module includes fault type judgment module Ⅰ and fault type judgment module Ⅱ. Fault type judgment module Ⅰ is used to convert the switching signal of the switch tube and the voltage fault signal into fault type coding Ⅰ, and fault type judgment module Ⅱ is used to convert fault type coding Ⅰ and the fault judgment signal of the three-phase current into fault type coding Ⅱ.

[0049] The parameters of the permanent magnet synchronous motor are: the number of pole pairs pn = 4, the stator phase resistance Rs = 3Ω, the direct-axis inductance Ld = 33.5mH, the quadrature-axis inductance Lq = 33.5mH, and the permanent magnet flux linkage ψf = 0.125Wb; the simulation conditions are: motor state: the inverter bus voltage is U = 311V, the rated speed is 1000r / min, the step size and the sampling time are the same, Ts = 2μs, and the load torque Tm = 10; generator state: the inverter bus voltage is U = 50V, the rated speed is 1000r / min, the step size and the sampling time are the same, Ts = 2μs, and the load resistance is R = 100Ω.

[0050] Combined with Figures 1 - 7 As shown in

[0051] The first step: Set the switch tubes in the open-winding motor model as shown in the following table:

[0052] Left (Positive) Inverter Right (Negative) Inverter Upper Switch of Phase A a11 a21 Lower Switch of Phase A a12 a22 Upper Switch of Phase B b11 b21 Lower Switch of Phase B b12 b22 Upper Switch of Phase C c11 c21 Lower Switch of Phase C c12 c22

[0053] Use voltage sensors to measure the voltages of the three phases of motors A, B, and C respectively, and then measure the switching signals of the 6 groups of switch tubes on one side of the inverter in the open-winding model. Based on the switching signals and the voltage values, judge whether the values of UA, UB, and UC are within the abnormal range and obtain a voltage fault signal. Taking phase A as an example:

[0054] If either a11 or a22 is open or both are open, when the switching signal of a11 / a22 is 1 for the voltage of phase A, its voltage value cannot reach the normal value UA, and the voltage tends to 0. It is determined that a fault occurs when the voltage value is lower than 0.9UA.

[0055] If either a12 or a21 is open - circuited, or both are open - circuited, when the switching signal of A - phase voltage at a12 / a21 is 1, its voltage value cannot reach the normal value - UA, and the voltage also tends to 0. It is determined that a fault occurs when the voltage value is higher than - 0.9UA.

[0056] Step 2: After obtaining the fault signal, encode various fault types. Taking phase A as an example, it is shown in the following table:

[0057] Phase A Code Fault Type 0 No Fault in Any Switching Tube of Phase A 1 Any One or Both of a11 / a22 Open Circuited 2 Any One or Both of a12 / a21 Open Circuited 3 Faults Corresponding to 1 and 2 Exist Simultaneously

[0058] The output signal fault_type is the fault type code I. Thus, the fault type code I can be obtained. The coding methods for the faults of phase B and phase C are the same as that of phase A. In the fault type code I, C is the first digit, B is the second digit, and A is the third digit. When the fault type code I is 321, the fault type code of phase C represents that either c11 / c22 is open - circuited or both are open - circuited, and either c12 / c21 is open - circuited or both are open - circuited, either b12 / b21 is open - circuited or both are open - circuited, and either a11 / a22 is open - circuited or both are open - circuited.

[0059] Step 3: For the motor state, each code of the fault type code I corresponds to a three - phase current fault condition. Taking phase A as an example:

[0060] Fault Type Code I Fault Type of Phase A Current xx0 Phase A Current Normal xx1 First Half Cycle of Phase A Current Missing xx2 Second Half Cycle of Phase A Current Missing xx3 Entire Phase A Current Missing

[0061] The same applies to phase B and phase C as phase A.

[0062] Step 4: For the generator state, taking phase A as an example, when either a11 / a22 is open - circuited, the current of phase A is normal; only when both a11 / a22 are open - circuited, the first half - cycle of the current of phase A will be missing. At this time, it is necessary to use a current sensor to measure the three - phase current and combine the fault type code I to judge the current fault.

[0063] Taking the fault of phase A as an example, assuming that the peak value of the current of phase A under normal conditions is Iapp. At this time, if the third digit A of the fault type code I is greater than 0, a fault occurrence signal is obtained. In the next cycle after the fault occurs, detect whether the current is greater than 0.5Iapp or less than - 0.5Iapp. If the current is greater than 0.5Iapp, the first half - cycle of phase A is missing; if the current is less than - 0.5Iapp, the second half - cycle of phase A is missing. Similarly, encode according to the fault signal:

[0064]

[0065]

[0066] The output signal fault_type_i is the fault type code II. From this, the fault type code II can be obtained. When faults occur in phases B and C, the coding method is the same. In the fault type code II, C is the first digit, B is the second digit, and A is the third digit. Taking phase A as an example:

[0067] Fault Type Code II Fault Type of Phase A Current xx0 Phase A Current Normal xx1 First Half Cycle of Phase A Current Missing xx2 Second Half Cycle of Phase A Current Missing xx3 Entire Phase A Current Missing

[0068] Each code obtained for the fault type code II corresponds to a three-phase current fault condition.

[0069] During the experiment, in the motor state, open-circuit faults were set to occur simultaneously for a11, b12, c11, and c21 at 0.32 s. As Figure 8 、 Figure 9 shown, the fault type code I is 321. The current loss situation is that the upper half cycle of the current in phase A is missing, the lower half cycle of the current in phase B is missing, and the current in phase C is completely missing. Since there are many simultaneous faults during simulation, the waveforms of the three-phase currents in phases A, B, and C have been distorted significantly, but the missing situation can still be seen to be consistent with the theory. In the generator state, open-circuit faults were set to occur simultaneously for a11, b12, c11, a22, and c22 at 0.32 s. As Figure 10 、 Figure 11 and Figure 12 shown, the fault type code I is 321, and the fault type code II is 001. The current loss situation is that only the upper half cycle of the current in phase A is missing, and there is no current loss in phases B and C.

[0070] In the motor state, by performing fault judgment on the three-phase voltage, a voltage fault signal is obtained. Through the fault type judgment module I, the switching signal of the switch tube and the voltage fault signal can be converted into the fault type code I; in the generator state, on the basis of obtaining the fault type code I by the same motor fault diagnosis method, adding the fault judgment signal of the three-phase current, the fault type code II is obtained. The diagnosis method has low cost, is simple and reliable, can achieve full coverage of switch tube faults, and can also be perfectly matched with the current-based fault tolerance method. It can accurately diagnose the current fault situation and obtain the location of the switch tube fault at the same time.

[0071] In the description of this specification, the description with reference to terms such as "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0072] The foregoing has shown and described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and what is described in the above embodiments and the specification is only to illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements fall within the scope of the present invention claimed.

Claims

1. A fault diagnosis method for a permanent magnet synchronous motor based on a coding system, characterized in that, The described diagnostic method includes three-phase voltage, three-phase current, switching signals of switching tubes, a fault judgment module, a fault type judgment module, and a fault type coding. The three-phase voltage and three-phase current are connected to the fault judgment module. The switching signals of the switching tubes and the fault judgment module are connected to the fault type judgment module. The fault type judgment module is connected to the fault type coding. The fault type coding includes fault type coding I and fault type coding II. The fault type judgment module includes fault type judgment module I and fault type judgment module II. Fault type judgment module I is used to convert the switching signals of the switching tubes and voltage fault signals into fault type coding I. Fault type judgment module II is used to convert fault type coding I and current fault signals into fault type coding II.

2. The fault diagnosis method for a permanent magnet synchronous motor based on a coding system according to claim 1, characterized in that, The fault judgment module includes a voltage fault judgment module and a current fault judgment module. The voltage fault judgment module is used to perform fault judgment on the three-phase voltage to obtain a voltage fault signal. The current fault judgment module is used to perform fault judgment on the three-phase current to obtain a current fault signal.

3. The fault diagnosis method for a permanent magnet synchronous motor based on a coding system according to claim 2, characterized in that, The diagnostic method includes the following steps: Step 1: Set the switching tubes in the open-winding motor model: Use voltage sensors to measure the voltages of the three phases of motors A, B, and C respectively, and then measure the switching signals of 6 groups of switching tubes on one side of the inverter in the open-winding motor model. According to the switching signals and voltage values, determine whether the values of UA, UB, and UC are within the abnormal range, and obtain a voltage fault signal. Step 2: After obtaining the fault signal, encode various fault types. The output signal fault_type is the fault type coding I, and the fault type coding I is obtained. The coding methods for the faults of phases B and C are the same as that of phase A. In the fault type coding I, C is the first digit, B is the second digit, and A is the third digit. When the fault type coding I is 321, it means that either c11 / c22 is open or both are open, and either c12 / c21 is open or both are open, either b12 / b21 is open or both are open, and either a11 / a22 is open or both are open. Step 3: For the motor state, each coding of the fault type coding I corresponds to a three-phase current fault condition: The same applies to phases B and C as to phase A. Step 4: For the generator state, when either a11 / a22 is open, the current of phase A is normal; when both a11 / a22 are open, the upper half cycle of the current of phase A is missing. Use current sensors to measure the three-phase current, combine with the fault type coding I to perform current fault judgment, and encode according to the fault signal: The output signal fault_type_i is the fault type coding II, and the fault type coding II is obtained. The coding methods for phases B and C when faults occur are the same. In the fault type coding II, C is the first digit, B is the second digit, and A is the third digit: Each coding of the obtained fault type coding II corresponds to a three-phase current fault condition; 4. The fault diagnosis method for a permanent magnet synchronous motor based on a coding system according to claim 3, characterized in that, The current fault judgment in the fourth step includes: When a fault occurs in phase A, assuming that the peak value of the current in phase A under normal conditions is I app , and the third digit A of the fault type code I is greater than 0, a fault occurrence signal is obtained; Within the next cycle after occurrence, detect whether the current is greater than 0.5I app or less than -0.5I app If the current is greater than 0.5I app , the first half cycle of phase A is missing; if the current is less than -0.5I app , the second half cycle of phase A is missing.

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