A fault diagnosis method for a switched reluctance motor converter with current sensor bias

Abstract

This invention discloses a fault diagnosis method for a switched reluctance motor converter biased by current sensors, comprising the following steps: installing current sensors; obtaining the current values ​​measured by three current sensors according to step S1; S3, constructing fault diagnosis variable one; judging the magnitude of the sum and proceeding accordingly; judging; S6, constructing fault diagnosis variable two; when a fault occurs, judging the fault type through the switching transistor signal; judging whether an error is reported, if no error is reported, jumping to S9, if an error is reported, querying the fault code table, and outputting the fault type and fault location, jumping to S10; the system is healthy and no fault has occurred; diagnosis ends. This invention uses the above method, reducing diagnosis time, not coupling with other methods, improving the accuracy of fault diagnosis, and the proposed method is verified by simulation.

Description

Technical Field

[0001] This invention relates to the field of motor system fault diagnosis technology, and in particular to a fault diagnosis method for a switched reluctance motor converter with current sensor bias. Background Technology

[0002] Compared to traditional motors, switched reluctance motors have advantages such as simple structure, high efficiency, flexible control, and low cost. At the same time, switched reluctance motors do not have permanent magnets, so there is no concern about high-temperature demagnetization. This makes switched reluctance motors more competitive in harsh application environments such as electric vehicles, home appliances, aerospace industry, and industrial automation equipment. However, due to the special structure and working principle of switched reluctance motors, the drive system, as the core part of the operation of switched reluctance motors, has increasingly higher requirements for fault diagnosis.

[0003] Traditional current sensor installations only measure the current flowing through the motor windings, without directly measuring the current in each arm of the power converter. A fault in a power device symmetrically positioned on one arm can cause the winding current to exhibit the same abnormal behavior, but the location of the fault cannot be determined. Therefore, researchers have proposed relocating the current sensor. However, the existing installation location can lead to multiphase current coupling, which can cause phase current distortion after a fault occurs. This makes it impossible to accurately calculate the phase current value, resulting in drive system control failure. Summary of the Invention

[0004] The purpose of this invention is to provide a fault diagnosis method for a switched reluctance motor converter with current sensor bias, which solves the problem that existing fault diagnosis methods based on current sensor reconstruction require the addition of new detection devices or are difficult to accurately reconstruct the phase current.

[0005] To achieve the above objectives, the present invention provides a fault diagnosis method for a switched reluctance motor converter with current sensor bias, comprising the following steps:

[0006] S1. Install the current sensor according to the corresponding installation method;

[0007] S2. Obtain the current values ​​measured by the three current sensors according to the current sensor installation method in step S1.

[0008] S3. Construct fault diagnosis variable one;

[0009] S4, Judgment and The size, where, Indicates the first variable for fault diagnosis. for p ( p = A , B ,C ) Phase No. If the phase current values ​​at time 1 are equal, wait for the current to rise at the next time step. If the current rises, it is determined that a diode open circuit fault has occurred, and proceed to step S10. If they are not equal, proceed to step S5.

[0010] S5, Judgment ,in, The winding current fault threshold should be set to 0 if the current switching transistor control signal is off. If it is open, it should be used. If the value 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.

[0011] S6. Construct the second fault diagnosis variable;

[0012] S7. Set two fault modes; when a fault occurs, if the switch signal is 1, it is determined to be an open circuit fault, and if the switch signal is 0, it is determined to be a short circuit fault. Then proceed to step S8.

[0013] S8, Judgment Check if an error occurs. If no error occurs, proceed to step S9. If an error occurs, query the fault code table, output the fault type and fault location, and proceed to step S10.

[0014] S9. Obtain the diagnostic result that the switched reluctance motor drive system is healthy and has no faults.

[0015] S10, Diagnosis complete.

[0016] Preferably, the installation method in S1 is as follows: current sensor one is connected to the upper bridge arm of phase A and phase B, current sensor two is connected to the upper bridge arm of phase C and the lower bridge arm of phase A, and current sensor three is connected to the lower bridge arm of phase B and phase C.

[0017] Preferably, the expressions for the current values ​​measured by the three current sensors in S2 are as follows:

[0018] ;

[0019] in, , , These are the measured values ​​from current sensors one, two, and three, respectively. , , These are the winding currents for phases A, B, and C, respectively.

[0020] Preferably, in a three-phase switched reluctance motor, at most two phases are simultaneously turned on, and the phase current of the non-conducting phase is 0 in a healthy state.

[0021] Preferably, the currents measured in different conduction intervals are as follows:

[0022] AB phase conduction interval:

[0023] ;

[0024] BC phase conduction interval:

[0025] ;

[0026] CA phase conduction interval:

[0027] .

[0028] Preferably, the expression for fault diagnosis variable one in S3 is as follows:

[0029] ;

[0030] in, for p ( p = A , B , C ) Phase No. The phase current value at time t.

[0031] Preferably, the expression for fault diagnosis variable two in S6 is as follows:

[0032] ;

[0033] in, This represents the second variable for fault diagnosis. For the first A current sensor in The current value collected at any given time. For the first A current sensor in The current value collected at any given time.

[0034] Preferably, the two fault modes in S7 are as follows:

[0035] The expression for fault mode one is:

[0036] ;

[0037] The expression for fault mode 2 is:

[0038] .

[0039] Preferably, the fault code table in S8 includes an open circuit fault lookup table and a short circuit fault lookup table.

[0040] Therefore, the present invention employs the above-described fault diagnosis method for a switched reluctance motor converter with current sensor bias, which has the following beneficial effects:

[0041] (1) By using a bias current sensor, each power device in the drive circuit 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 realizing rapid fault diagnosis and location.

[0042] (2) This method does not require any additional hardware and is applicable to various chopper control methods; at the same time, it has strong diagnostic function and can diagnose 10 types of faults of 4 types at the same time; it also has the characteristic of fast diagnosis. After the fault behavior occurs, the faults of the switching tube and the open circuit faults of the diode can be diagnosed and located in as little as 1 or 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 diagnostic speed.

[0043] (3) This method is applicable to three-phase unbalanced half-bridge power converters. By biasing three current sensors at the bridge arm positions of the power converter, it is possible not only to detect the measured bridge arm current, but also to accurately reconstruct the winding current of the three-phase switched reluctance motor. 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 bias 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 reduces the diagnostic time and is not coupled with other phases, thus improving the accuracy of fault diagnosis. The proposed method is verified by simulation.

[0044] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0045] Figure 1 This is a 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.

[0046] Figure 2 This is a diagram showing the placement of the current sensor in the current reconstruction technology of this invention.

[0047] Figure 3 This is a schematic diagram of interval division according to an embodiment of the present invention;

[0048] Figure 4 This is a waveform diagram of the reconstructed steady-state and transient currents according to an embodiment of the present invention;

[0049] Figure 5These are the experimental results of double open-circuit fault diagnosis according to an embodiment of the present invention;

[0050] Figure 6 These are the results of short-circuit fault diagnosis tests according to embodiments of the present invention;

[0051] Figure 7 The results of the fault diagnosis experiment for two simultaneously conducting intervals being opened separately. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0053] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0054] Example

[0055] like Figure 1 As shown, this invention provides a fault diagnosis method for a switched reluctance motor converter with current sensor bias, mainly applied to three-phase unbalanced half-bridge power converters. It can diagnose various faults while reducing fault diagnosis time. The main fault diagnosis types include open-circuit faults of switching transistors, short-circuit faults of switching transistors, open-circuit faults of power diodes, and mixed open-circuit and short-circuit faults of switching transistors. The method includes the following steps:

[0056] S1, according to Figure 2 The structure shown is used to install current sensors. 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. Figure 2 The "D" in the diagram represents a power diode, which is a traditional asymmetric half-bridge power converter used to power the H-bridge.

[0057] S2. Based on the current sensor installation method in step S1, the current values ​​measured by the three current sensors are as follows:

[0058] ;

[0059] in, , , These are the measured values ​​from current sensors one, two, and three, respectively. , , These are the winding currents for phases A, B, and C, respectively.

[0060] A three-phase switched reluctance motor (SRM) can have a maximum of two phases conducting simultaneously, and the phase current of the non-conducting phase should be 0 under healthy conditions. (Refer to...) Figure 3 Based on the motor's operating characteristics and the winding conduction sequence, different overlapping conduction intervals are defined. The currents measured in the different conduction intervals are as follows:

[0061] AB phase conduction interval:

[0062] ;

[0063] BC phase conduction interval:

[0064] ;

[0065] CA phase conduction interval:

[0066] ;

[0067] S3. The expressions for constructing fault diagnosis variables are as follows:

[0068] ;

[0069] in, Indicates the first variable for fault diagnosis. for p ( p = A , B , C ) Phase No. The phase current value at time t. for p ( p = A , B , C ) Phase No. The phase current value at time t.

[0070] S4, Judgment and If the two values ​​are equal, wait for the current to rise in the next moment. If the current rises, it is determined that a diode open circuit fault has occurred, and proceed to step S10. If they are not equal, proceed to step S5.

[0071] S5, Judgment ,in, To determine the winding current fault threshold, if the current switching transistor control signal is off (indicating logic 0), the following should be used: If it is open (representing logic 1), it should be used. If the value 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.

[0072] S6. The expression for the second fault diagnosis variable is constructed as follows:

[0073] ;

[0074] in, This represents the second variable for fault diagnosis. For the first A current sensor in The current value collected at any given time. For the first A current sensor in The current value collected at any given time.

[0075] S7. Set two fault modes, fault mode one is... Fault mode two is .

[0076] When a fault occurs, if the switching transistor signal is 1, an open circuit fault is determined; if the switching transistor signal is 0, a short circuit fault is determined, and step S8 is executed.

[0077] S8, Judgment Check if an error occurs. If no error occurs, proceed to step S9. If an error occurs, query the fault code table and output the fault type and location, then proceed to step S10. The open circuit fault lookup table and short circuit fault lookup table are shown in Tables 1-4, respectively.

[0078] Table 1 Fault Diagnosis and Fault Code Output

[0079] ;

[0080] Table 2 Fault Type Judgment and Control Signals

[0081] ;

[0082] Table 3 Open Circuit Fault Inquiry Table

[0083] ;

[0084] Table 4 Short Circuit Fault Lookup Table

[0085] ;

[0086] S9. Obtain the diagnostic result that the switched reluctance motor drive system is healthy and has no faults.

[0087] S10, Diagnosis complete.

[0088] Figure 4 The results are divided into two parts: the first part shows the current change waveform when the load changes abruptly from 1Nm to 2Nm at 500rpm, and the second part shows the current change waveform when the load changes from 2Nm to 1000rpm at 500rpm. The results show that the reconstruction current error is very small in both transient and steady-state conditions, indicating that the reconstruction method has good robustness.

[0089] Figure 5 The fault was diagnosed using the proposed method when both switching transistors of a single-phase winding experienced open-circuit faults. Figure 6 Both switching transistors of a single-phase winding experienced open-circuit faults, and the faults were diagnosed using the proposed method.

[0090] Figure 7 To investigate a single open-circuit fault occurring in the AB phase conducting interval, experiments show that the fault type and fault location can be diagnosed separately, verifying the decoupling of each phase in the proposed method.

[0091] Therefore, the present invention adopts the above-mentioned fault diagnosis method for a switched reluctance motor converter with current sensor bias, which reduces the diagnosis time, is not coupled with other phases, improves the accuracy of fault diagnosis, and verifies the proposed method through simulation.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions 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 current sensor bias, characterized in that, Includes the following steps: S1. Install the current sensor according to the corresponding installation method; the installation method in S1 is as follows: current sensor one is connected to the upper bridge arm of phase A and phase B, current sensor two is connected to the upper bridge arm of phase C and the lower bridge arm of phase A, and current sensor three is connected to the lower bridge arm of phase B and phase C. S2. Obtain the current values ​​measured by the three current sensors according to the current sensor installation method in step S1. S3. Construct fault diagnosis variable one; The expression for fault diagnosis variable one in S3 is as follows: ； in, for Xiangdi The phase current value at a given time; S4, Judgment and The size, where, Indicates the first variable for fault diagnosis. for Xiangdi If the phase current values ​​at time 1 are equal, wait for the current to rise at the next time step. If the current rises, it is determined that a diode open circuit fault has occurred, and proceed to step S10. If they are not equal, proceed to step S5. S5, Judgment ,in, The winding current fault threshold should be set to 0 if the current switching transistor control signal is off. If it is open, it should be used. If the value 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 second fault diagnosis variable; The expression for fault diagnosis variable two in S6 is as follows: ； in, This represents the second variable for fault diagnosis. For the first A current sensor in The current value collected at any given time. For the first A current sensor in The current value collected at any given time; S7. Set two fault modes; when a fault occurs, if the switch signal is 1, it is determined to be an open circuit fault, and if the switch signal is 0, it is determined to be a short circuit fault. Then proceed to step S8. S8, Judgment Check if an error occurs. If no error occurs, proceed to step S9. If an error occurs, query the fault code table, output the fault type and fault location, and proceed to step S10. S9. Obtain the diagnostic result that the switched reluctance motor drive system is healthy and has no faults. S10, Diagnosis complete.

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

3. The fault diagnosis method for a switched reluctance motor converter with current sensor bias according to claim 2, characterized in that: A three-phase switched reluctance motor can have a maximum of two phases conducting simultaneously, with the non-conducting phase having a phase current of 0 in a healthy state.

4. The fault diagnosis method for a switched reluctance motor converter with current sensor bias according to claim 3, characterized in that, The currents measured in different conduction intervals are as follows: AB phase conduction interval: ； BC phase conduction interval: ； CA phase conduction interval: 。 5. The fault diagnosis method for a switched reluctance motor converter with current sensor bias according to claim 1, characterized in that, The two fault modes in S7 are as follows: The expression for fault mode one is: ； The expression for fault mode 2 is: 。 6. The fault diagnosis method for a switched reluctance motor converter with current sensor bias according to claim 5, characterized in that: The fault code table in S8 includes an open circuit fault lookup table and a short circuit fault lookup table.

Images