Fault diagnosis method for switched reluctance motor converter with biased current sensor

Abstract

The invention discloses a fault diagnosis method for a switched reluctance motor converter with a biased current sensor. The fault diagnosis method comprises the following steps: installing the current sensor; obtaining current values measured by the three current sensors according to the step S1; s3, constructing a fault diagnosis variable I; judging the size of the sum, and executing corresponding steps; performing judgment; s6, constructing a fault diagnosis variable 2; when a fault occurs, the type of the fault is judged through a switching tube signal; s9, judging whether an error is reported or not, if no error is reported, skipping to S9, and if an error is reported, querying a fault code table, outputting a fault type and a fault position, and skipping to S10; the system is healthy and has no fault; and finishing the diagnosis. By adopting the method, the diagnosis time is shortened, the method is not coupled with other phases, the accuracy of fault diagnosis is improved, and the proposed method is verified through simulation.

Description

Technical Field

[0001] The present invention relates to the technical field of motor system fault diagnosis, and in particular to a current sensor biased switched reluctance motor converter fault diagnosis method. Background Art

[0002] Compared with traditional motors, switched reluctance motors have the advantages of simple structure, high efficiency, flexible control and low cost. At the same time, switched reluctance motors have no permanent magnets, so there is no worry about high-temperature demagnetization. This makes switched reluctance motors more competitive in harsh application environments such as electric vehicles, home appliances, aviation industry, and industrial automation equipment. However, due to the special structure and working principle of the switched reluctance motor, its drive system, as the core part of the operation of the switched reluctance motor, has increasingly higher requirements for fault diagnosis.

[0003] The traditional installation position of current sensors only measures the current flowing through the motor windings, without directly measuring the bridge arms on the power converter. Failure of power devices at symmetrical positions on the bridge arms will cause the winding current to behave abnormally, but the location of the fault cannot be determined. Therefore, researchers have proposed reselecting the current sensor position. However, the existing installation position will lead to multi-phase current coupling, which will cause phase current distortion after a fault occurs, making it impossible to accurately calculate the phase current value, resulting in failure of drive system control. Summary of the Invention

[0004] The purpose of the present invention is to provide a fault diagnosis method for a switched reluctance motor converter with current sensor bias, which solves the problem that the existing fault diagnosis method with current sensor reconstruction needs to add a new detection device or is difficult to accurately reconstruct the phase current.

[0005] To achieve the above object, the present invention provides a fault diagnosis method for a switched reluctance motor converter with a current sensor bias, comprising the following steps: S1. Install the current sensor according to the corresponding installation method; S2. Obtain the current values ​​measured by the three current sensors according to the current sensor installation method of step S1; S3, construct fault diagnosis variable 1; S4. Judgment and The size of represents fault diagnosis variable 1, for p ( p = A , B , C ) If the two are equal, wait for the current to rise at the next moment. If it rises, it is determined that a diode open circuit fault has occurred and go to step S10. If they are not equal, go to step S5. S5. Judgment ,in, is the winding current fault threshold. If the switch control signal is off at the current moment, If it is on, use If it is greater than the corresponding threshold, it is determined that the drive system has a double short circuit fault or a double open circuit fault, and the process jumps to step S10; S6, construct fault diagnosis variable 2; S7, setting two fault modes; when a fault occurs, if the switch tube signal is 1, it is determined to be an open circuit fault, and if the switch tube signal is 0, it is determined to be a short circuit fault, and executing step S8; S8. Judgment Is there an error? If no error occurs, jump to step S9. If an error occurs, query the fault code table, output the fault type and fault location, and jump to step S10. S9, obtaining a diagnosis result that the switched reluctance motor drive system is healthy and has no faults; S10. Diagnosis ends.

[0006] Preferably, the installation method in S1 is: current sensor 1 is connected to the upper bridge arm of phase A and phase B, current sensor 2 is connected to the upper bridge arm of phase C and the lower bridge arm of phase A, and current sensor 3 is connected to the lower bridge arm of phase B and phase C.

[0007] Preferably, the current values ​​measured by the three current sensors in S2 are expressed as follows: ; in, 、 、 are the measured values ​​of current sensors 1, 2, and 3 respectively. 、 、 They are the A, B, and C phase winding currents respectively.

[0008] Preferably, the three-phase switched reluctance motor has at most two phases conducting at the same time, wherein the phase current of the non-conducting phase is 0 in a healthy state.

[0009] Preferably, the currents measured in different conduction intervals are: AB phase conduction range: ; BC phase conduction range: ; CA phase conduction range: .

[0010] Preferably, the expression of the fault diagnosis variable 1 in S3 is as follows: ; in, for p ( p = A , B , C ) Phase current value at the moment.

[0011] Preferably, the expression of the fault diagnosis variable 2 in S6 is as follows: ; in, represents fault diagnosis variable 2, For the A current sensor in The current value collected at the moment, For the A current sensor in The current value collected at the moment.

[0012] Preferably, the two failure modes in S7 are as follows: The expression of failure mode 1 is: ; The expression of failure mode 2 is: .

[0013] Preferably, the fault code table in S8 includes an open circuit fault query table and a short circuit fault query table.

[0014] Therefore, the present invention adopts the above-mentioned method for fault diagnosis of switched reluctance motor converter with current sensor bias, which has the following beneficial effects: (1) By using the bias current sensor, each bridge arm where the power device of the drive circuit is located can be connected in series in real time. At the same time, a multi-fault diagnosis method combined with the installation method is proposed. By measuring and analyzing the current flow direction online, the health status of the drive system can be judged, thereby achieving rapid fault diagnosis and positioning.

[0015] (2) This method does not require any additional hardware and is applicable to various chopping control methods. It also has strong diagnostic capabilities and can diagnose 10 types of faults of four fault types at the same time. It also has the characteristic of fast diagnosis. After the fault behavior occurs, the switch tube fault and the diode open circuit fault can be diagnosed and located in only 1 and 2 control cycles respectively. At the same time, the fault diagnosis devices of each phase are independent and do not interfere with each other, which greatly improves the diagnostic accuracy and speed.

[0016] (3) This method is applicable to three-phase asymmetric half-bridge power converters. By biasing three current sensors at the bridge arm position of the power converter, not only can the measured bridge arm current be detected, but also the winding current of the three-phase switched reluctance motor can be accurately reconstructed. Without adding any detection device, the internal health status can be diagnosed online. Before and after a fault occurs, the current flow direction will change. The biased current sensor can distinguish this change and analyze the fault location and fault type, thereby realizing the fault diagnosis of the drive system. This diagnostic method shortens the diagnostic time and is not coupled with other phases, which improves the accuracy of fault diagnosis. Simulation is performed to verify the proposed method.

[0017] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of a fault diagnosis method for a switched reluctance motor converter with current sensor bias according to an embodiment of the present invention; Figure 2 A diagram showing the placement of current sensors for the current reconstruction technology according to an embodiment of the present invention; Figure 3 This is a schematic diagram of interval division according to an embodiment of the present invention; Figure 4 This is a waveform diagram of steady-state transient current reconstruction according to an embodiment of the present invention; Figure 5 The double open circuit fault diagnosis experiment results of the embodiment of the present invention; Figure 6 The short-circuit fault diagnosis test results of the embodiment of the present invention; Figure 7 These are the experimental results of open circuit fault diagnosis in two simultaneous conduction intervals. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0020] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0021] Example

[0022] like Figure 1 As shown, the present invention provides a fault diagnosis method for a switched reluctance motor converter with current sensor bias. This method is primarily applied to three-phase asymmetric half-bridge power converters and can diagnose a variety of faults while reducing fault diagnosis time. The main fault types diagnosed include switch open circuit faults, switch short circuit faults, power diode open circuit faults, and a combination of switch open-circuit and switch short-circuit faults. The method includes the following steps: S1. According to Figure 2 The structure shown in the figure is used to install the current sensors. Current sensor 1 is required to connect the upper bridge arm of phase A and phase B, current sensor 2 is required to connect the upper bridge arm of phase C and the lower bridge arm of phase A, and current sensor 3 is required to connect the lower bridge arm of phase B and phase C. Figure 2 D in the figure represents a power diode. It is a traditional asymmetric half-bridge power converter that powers the H-bridge.

[0023] S2. According to the current sensor installation method in step S1, the current values ​​measured by the three current sensors can be obtained as follows: ; in, 、 、 are the measured values ​​of current sensors 1, 2, and 3 respectively. 、 、 They are the A, B, and C phase winding currents respectively.

[0024] A three-phase switched reluctance motor (SRM) has at most two phases conducting at the same time, and the phase current of the non-conducting phase should be 0 in a healthy state. Figure 3, according to the working characteristics of the motor and the conduction sequence of the motor windings, different overlapping conduction intervals are divided. The currents measured in different conduction intervals are: AB phase conduction range: ; BC phase conduction range: ; CA phase conduction range: ; S3. The expression of the fault diagnosis variable is constructed as follows: ; in, represents fault diagnosis variable 1, for p ( p = A , B , C ) The phase current value at the moment, for p ( p = A , B , C ) Phase current value at the moment.

[0025] S4. Judgment and If the two are equal, wait for the next moment for the current to rise. If so, it is determined that a diode open circuit fault has occurred and go to step S10. If they are not equal, go to step S5. S5. Judgment ,in, is the winding current fault threshold. If the switch control signal is off (logic 0) at the current moment, If it is on (indicates logic 1), you should use If it is greater than the corresponding threshold, it is determined that the drive system has a double short circuit fault or a double open circuit fault, and the process jumps to step S10; S6. Construct the expression of fault diagnosis variable 2 as follows: ; in, represents fault diagnosis variable 2, For the A current sensor in The current value collected at the moment, For the A current sensor in The current value collected at the moment.

[0026] S7, set two failure modes, failure mode one is , failure mode 2 is .

[0027] When a fault occurs, if the switch tube signal is 1, it is determined to be an open circuit fault; if the switch tube signal is 0, it is determined to be a short circuit fault, and step S8 is executed; S8. Judgment Is there an error? If no error occurs, jump to step S9. If an error occurs, query the fault code table, output the fault type and fault location, and jump to step S10. The open circuit fault query table and the short circuit fault query table are shown in Table 1-4 respectively: Table 1 Fault judgment and fault code output ;

[0028] Table 2 Fault type judgment and control signal ;

[0029] Table 3 Open circuit fault query table ;

[0030] Table 4 Short circuit fault query table ;

[0031] S9, obtaining a diagnosis result that the switched reluctance motor drive system is healthy and has no faults; S10. Diagnosis ends.

[0032] Figure 4 It is divided into two parts. The first part is 500rpm, the load suddenly changes from 1Nm to 2Nm, the current change waveform and the current change waveform of 2Nm load from 500rpm to 1000rpm. The results show that the reconstructed current error in transient and steady state is very small, which shows that the reconstruction method is very robust.

[0033] Figure 5 The two switching tubes of the single-phase winding both have open circuit faults. According to the proposed method, the fault is diagnosed. Figure 6 Both switching tubes of the single-phase winding have open circuit faults, and the faults are diagnosed according to the proposed method.

[0034] Figure 7 For a single open-circuit fault that occurs in the conduction interval of both AB phases, the experiment shows that the fault type and fault location can be diagnosed separately, verifying the phase decoupling in the proposed method.

[0035] Therefore, the present invention adopts the above-mentioned current sensor biased switched reluctance motor converter fault diagnosis method, which shortens the diagnosis time, is not coupled with other phases, improves the accuracy of fault diagnosis, and performs simulation to verify the proposed method.

[0036] 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 the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A fault diagnosis method for a switched reluctance motor converter with a current sensor bias, characterized in that: The following steps are involved: S1. Install the current sensor according to the corresponding installation method; S2. Obtain the current values ​​measured by the three current sensors according to the current sensor installation method of step S1; S3, construct fault diagnosis variable 1; S4. Judgment and The size of represents fault diagnosis variable 1, for p ( p = A , B , C ) If the two are equal, wait for the current to rise at the next moment. If it rises, it is determined that a diode open circuit fault has occurred and go to step S10. If they are not equal, go to step S5. S5. Judgment ,in, is the winding current fault threshold. If the switch control signal is off at the current moment, If it is on, use If it is greater than the corresponding threshold, it is determined that the drive system has a double short circuit fault or a double open circuit fault, and the process jumps to step S10; S6, construct fault diagnosis variable 2; S7, setting two fault modes; when a fault occurs, if the switch tube signal is 1, it is determined to be an open circuit fault, and if the switch tube signal is 0, it is determined to be a short circuit fault, and executing step S8; S8. Judgment Is there an error? If no error occurs, jump to step S9. If an error occurs, query the fault code table, output the fault type and fault location, and jump to step S10. S9, obtaining a diagnosis result that the switched reluctance motor drive system is healthy and has no faults; S10. Diagnosis ends.

2. The fault diagnosis method for a switched reluctance motor converter with current sensor bias according to claim 1, characterized in that: The installation method in S1 is: current sensor 1 is connected to the upper bridge arm of phase A and phase B, current sensor 2 is connected to the upper bridge arm of phase C and the lower bridge arm of phase A, and current sensor 3 is connected to the lower bridge arm of phase B and phase C.

3. The fault diagnosis method for a switched reluctance motor converter with current sensor bias according to claim 2, characterized in that: The expressions of the current values ​​measured by the three current sensors in S2 are as follows: ； in, 、 、 are the measured values ​​of current sensors 1, 2, and 3 respectively. 、 、 They are the A, B, and C phase winding currents respectively.

4. The fault diagnosis method for a switched reluctance motor converter with current sensor bias according to claim 3, characterized in that: In a three-phase switched reluctance motor, at most two phases are turned on at the same time, and the phase current of the non-conducting phase is 0 in a healthy state.

5. The fault diagnosis method for a switched reluctance motor converter with current sensor bias according to claim 4, characterized in that: The currents measured in different conduction intervals are: AB phase conduction range: ； BC phase conduction range: ； CA phase conduction range: 。 6. The fault diagnosis method for a switched reluctance motor converter with current sensor bias according to claim 5, characterized in that: The expression of the fault diagnosis variable 1 in S3 is as follows: ； in, for p ( p = A , B , C ) Phase current value at the moment.

7. The fault diagnosis method for a switched reluctance motor converter with current sensor bias according to claim 6, characterized in that: The expression of the fault diagnosis variable 2 in S6 is as follows: ； in, represents fault diagnosis variable 2, For the A current sensor in The current value collected at the moment, For the A current sensor in The current value collected at the moment.

8. The fault diagnosis method for a switched reluctance motor converter with current sensor bias according to claim 7, characterized in that: The two failure modes in S7 are as follows: The expression of failure mode 1 is: ； The expression of failure mode 2 is: 。 9. The fault diagnosis method for a switched reluctance motor converter with current sensor bias according to claim 8, characterized in that: The fault code table in S8 includes an open circuit fault query table and a short circuit fault query table.

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