Online fault diagnosis method for multi-stage rotating rectifier in multi-stage starting and generating system

Abstract

This invention discloses an online fault diagnosis method for a multi-stage rotating rectifier in a multi-stage starting and generating system, belonging to the field of motor fault diagnosis technology. It measures the stator-side current of the exciter, calculates the sum of squares of the stator-side currents based on the measurement results, and simultaneously obtains the rotor position θ of the exciter. r The relative angle θ between the exciter rotor and the magnetic field w The method determines whether the rotating rectifier has failed based on the minimum sum of squares of the exciter stator current within each sampling range. Once a fault is identified and its type determined, the faulty diode is located, either by its position or its number. This method is applicable to rotating rectifier fault diagnosis throughout the entire process of a multi-stage start-up and power generation system. It can determine the fault type and the location of the faulty diode based on online real-time assessment of whether a rotating rectifier has failed. The method is simple to implement, and the algorithm does not require complex switching between the start-up and power generation stages.

Description

Technical Field

[0001] This invention belongs to the field of motor fault diagnosis technology, specifically relating to an online fault diagnosis method for the rotating rectifier of a multi-stage starting and generating system. Background Technology

[0002] To improve aircraft reliability, maintainability, ground support capabilities, and energy efficiency, the concept of More Electric Aircraft (MEA) emerged, and related research and applications have made significant progress in recent decades. MEA refers to aircraft that gradually replaces hydraulic and pneumatic energy in secondary energy systems with electrical energy, thus transforming the aircraft from a secondary energy system to a single energy system.

[0003] Integrated starter / generator is a crucial technology in the field of more-electric aircraft. Integrated starter / generator utilizes the reversibility of electric motors, allowing the onboard main generator to first operate in electric motor mode to start the aircraft engine. Once started, it then switches to generator mode to supply power to onboard electrical equipment. Clearly, in an integrated starter / generator system, since the engine does not require a dedicated starter motor or bleed air extraction, the accessory drive mechanism is greatly simplified, and the corresponding bleed air system is eliminated, significantly improving the aircraft's reliability, maintainability, and efficiency.

[0004] like Figure 1 As shown, a three-stage generator consists of an auxiliary exciter, an exciter, a rotating rectifier, and a main motor. When used as a generator, it offers advantages such as high reliability, low maintenance costs, and simple power generation control technology, thus finding widespread application in aircraft. Research on multi-stage starting and generating systems based on three-stage brushless synchronous generators has also garnered significant attention.

[0005] A multi-stage starting and generating system mainly consists of two operating phases: starting and generating. During the starting phase, the onboard power supply directly provides AC excitation current to the exciter. The induced electromotive force of the exciter rotor's three-phase windings is rectified by a rotating rectifier to provide DC excitation current to the main motor's rotor windings. Once the generator reaches a certain speed, the system enters the generating phase. The magnetic pole pair exciter's stator three-phase windings provide DC excitation current to the exciter stator windings via the generator controller (GCU), and the exciter then provides DC excitation current to the main motor via a rotating rectifier.

[0006] As the above analysis shows, multi-stage start-up and power generation systems employ both AC and DC excitation methods for the exciters at different stages. Furthermore, the exciters require a rotating rectifier to provide excitation current to the main motor; therefore, the health of the rotating rectifier is crucial to the system. Because the rotating rectifier is coaxially mounted with the motor, the significant centrifugal force and thermal stress result in a much higher failure rate than other components. Therefore, to improve the reliability and maintainability of multi-stage start-up and power generation systems, it is necessary to conduct research on fault diagnosis techniques for rotating rectifiers. When the multi-stage start-up and power generation system is in the start-up phase, the aircraft is usually in a ground-based standby state. For safety reasons, regardless of the type of rotating rectifier failure, the aircraft (especially commercial airliners) must be shut down for maintenance at this time. When the system is in the power generation phase, if an open-circuit diode fault occurs in the rotating rectifier, the excitation output capacity of the exciter will decrease slightly. In this case, the multi-stage start-up / generator system can either be shut down or operated at reduced capacity. If a short-circuit diode fault occurs, the exciter rotor current will increase abnormally, and the excitation output capacity will decrease significantly. In this case, the multi-stage start-up / generator system, acting as a generator, must be shut down to prevent the fault from spreading. Therefore, it is necessary to determine the type of diode fault in the rotating rectifier. Furthermore, if a fault is detected in the rotating rectifier, the faulty diode should be located. This not only facilitates rapid repair but also aids in system-level fault analysis and optimization, identifying the root cause or weak point of the fault, enabling system optimization and upgrades, thereby reducing the failure rate and improving reliability.

[0007] Therefore, from the perspective of fault response measures, rapid repair, and system-level fault analysis and optimization, the fault diagnosis method for rotating rectifiers in multi-stage start-up generator systems should be able to distinguish fault types and locate faulty diodes at all stages. Summary of the Invention

[0008] The technical problem to be solved:

[0009] To overcome the shortcomings of existing technologies, this invention provides an online fault diagnosis method for rotating rectifiers in a multi-stage start-up and power generation system. This method can diagnose whether diodes in the rotating rectifier have failed and determine the fault type and location of the faulty diode during the entire operation of the multi-stage start-up and power generation system. The method is simple to implement and does not require complex switching between the start-up and power generation stages.

[0010] The technical solution of this invention is: an online fault diagnosis method for a multi-stage rotating rectifier in a multi-stage starting and generating system, characterized by the following specific steps:

[0011] Step 1: Measure the stator current of the exciter, calculate the sum of squares of the stator currents based on the measurement results, and simultaneously obtain the rotor position θ of the exciter. rThe relative angle θ between the exciter rotor and the magnetic field w ;

[0012] Step 2: Determine whether the rotating rectifier has malfunctioned based on the minimum value of the sum of squares of the exciter stator current within each sampling range;

[0013] Step 3: After determining that the rotating rectifier has failed and the type of failure has been determined in Step 2, locate the faulty diode, that is, determine the location or number of the faulty diode.

[0014] A further technical solution of the present invention is as follows: In step 1, the method for calculating the sum of squares of the exciter stator current is as follows: the stator current of the exciter is collected by a current sensor and denoted as i. eA i eB i eC The formula for calculating the sum of squares of the stator currents of the exciter is as follows:

[0015]

[0016] Among them, the sum of squares of the exciter stator side current i s 2 This refers to the amount of fault information that characterizes the fault state of the rotating rectifier.

[0017] A further technical solution of the present invention is: in step 1, the rotational speed n of the rotating magnetic field generated by the three-phase alternating current of the exciter stator is first determined by... efm With motor speed n r Calculate the relative rotational speed n of the exciter rotor with respect to the magnetic field. w

[0018] n w =n efm -n r

[0019] Then, the relative angle θ between the exciter rotor and the magnetic field, which varies with time, is calculated. w θ w =0~360°, the formula is as follows:

[0020] θ w =∫2πf(n w )dt+θ w0

[0021] When the system starts running, the exciter's initial position is θ. w0 θ w0 = 0~360°; when θ w When =0, the A phase of the exciter stator is aligned with the A phase of the rotor.

[0022] A further technical solution of the present invention is: in step 1, the exciter rotor position θr Can be directly obtained by resolver measurement, θ r = 0 to 360°.

[0023] A further technical solution of the present invention is: when the system is working in the starting stage, the relative angle θ of the exciter rotor with respect to the magnetic field w is denoted as θ; when the system is working in the power generation stage, the position θ of the exciter rotor r is denoted as θ;

[0024] Using the obtained angle θ, when the angle is in different ranges, sample the sum of squares of the exciter stator current, and obtain the minimum value of the sum of squares of the exciter stator current in each range. The sampling ranges respectively defined for the starting stage and the power generation stage are shown in the following table:

[0025]

[0026]

[0027] A further technical solution of the present invention is: the method for judging whether the rectifier fails in step 2 is:

[0028] 2.1 Use a sliding register to compare the minimum value obtained in each sampling range with the minimum value obtained in the previous sampling range, and obtain a ratio, denoted as R;

[0029] 2.2 Compare the ratio R calculated in 2.1 with the set thresholds R1 and R2: if R < R1, the rotating rectifier is working normally; if R1 < R < R2, the rotating rectifier has an open circuit fault; if R2 < R, the rotating rectifier has a short circuit fault.

[0030] A further technical solution of the present invention is: the method for locating the faulty diode in step 3 is:

[0031] 3.1 When it is judged that a fault has occurred, record the θ corresponding to the sampling range at this time, denoted as θ f .

[0032] 3.2 Define the diode numbers of the upper and lower bridge arms of phase a of the rotating rectifier as D1 and D4 respectively, the diode numbers of the upper and lower bridge arms of phase b as D3 and D6, and the diode numbers of the upper and lower bridge arms of phase c as D5 and D2;

[0033] According to the θ f value, judge the number of the faulty diode according to the angle range, as shown in the following table:

[0034] <![CDATA[Startup phase θ f > Open-circuit diode number Short-circuit diode number 35°～45° D1 D4 95°～105° D2 D5 155°～165° D3 D6 215°～225° D4 D1 275°～285° D5 D2 335°～345° D6 D3

[0035]

[0036]

[0037] Beneficial effects

[0038] The beneficial effects of this invention are as follows: when a rotating rectifier is under different fault conditions, the sum of squares of the exciter rotor current and the exciter stator current will differ from those under healthy conditions. This invention starts from the characteristics of the sum of squares of the exciter stator current and diagnoses rotating rectifier faults by judging the correspondence between changes in the sum of squares of the exciter stator current and different states of the rotating rectifier. The proposed method can achieve online diagnosis of whether a rotating rectifier has failed, as well as the determination of the fault type and the location of the faulty diode.

[0039] This invention provides a method for fault diagnosis of rotating rectifiers throughout the entire process of a multi-stage start-up / generation system. It can determine the fault type and location of the faulty diode based on online real-time assessment of whether a rotating rectifier fault has occurred. The method is simple to implement, and the algorithm does not require complex switching between the start-up and generation stages. This proposed method helps improve the overall reliability and maintenance efficiency of multi-stage start-up / generation systems. Specific advantages include:

[0040] 1) Obtaining fault information of the rotating rectifier only requires measuring the stator current of the exciter, which requires less hardware.

[0041] 2) Fault type judgment and fault diode location are based on the sum of squares of the exciter stator current, which eliminates the need to estimate the exciter rotor current and avoids misjudgment caused by inaccurate estimation.

[0042] 3) It only requires sampling data within a fixed range, thus placing lower demands on processor performance. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of a three-stage start-up and power generation system.

[0044] Figure 2 This is a schematic diagram of the equivalent circuit of the rotor section of a multi-stage starter generator.

[0045] Figure 3 This is the conceptual framework of the rotating rectifier fault diagnosis and location method proposed in this invention;

[0046] Figure 4 This is a block diagram of the rotating rectifier fault diagnosis and location method proposed in this invention;

[0047] Figure 5 This refers to the amount of fault information.

[0048] Figure 6 The ratio of fault information at adjacent commutation points;

[0049] Figure 7 This indicates the location of the faulty diode. Detailed Implementation

[0050] The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the invention, and should not be construed as limiting the invention.

[0051] This embodiment presents an online detection and location method for rotating rectifier faults in a multi-stage start-up and power generation system based on the characteristics of current amplitude variation at commutation points. The method obtains the sum of squares of the exciter stator current and the relative angle of the exciter rotor to the magnetic field, as well as the exciter rotor position. The ratio of the sum of squares of the exciter stator current at adjacent commutation points is calculated as fault information. During the start-up phase, the relative angle of the exciter rotor to the magnetic field is used; during the power generation phase, the fault information is sampled based on the exciter rotor position. The fault type of the rotating rectifier is determined by comparing two adjacent fault information values. Finally, the location of the faulty diode in the rotating rectifier is determined using the corresponding sampling range. This method is applicable to rotating rectifier fault diagnosis throughout the entire process of a multi-stage start-up and power generation system. It can determine the fault type and the location of the faulty diode based on online real-time judgment of whether a rotating rectifier fault has occurred. The method is simple to implement, and the algorithm does not require complex switching between the start-up and power generation phases.

[0052] The specific steps are as follows:

[0053] Step 1: Measure the stator current of the exciter, calculate the sum of squares of the stator currents based on the measurement results, and simultaneously obtain the rotor position θ of the exciter. r The relative angle θ between the exciter rotor and the magnetic field w Specifically:

[0054] 1.1 The stator current of the exciter is acquired by a current sensor and denoted as i. eA i eB i eC The sum of squares of the stator currents of the exciter is calculated as shown in the following formula.

[0055]

[0056] Sum of squares of exciter stator current i s 2 This refers to the amount of fault information that characterizes the fault state of the rotating rectifier.

[0057] 1.2 The rotational speed n of the rotating magnetic field generated by the three-phase alternating current of the exciter stator efm With motor speed n r Calculate the relative rotational speed n of the exciter rotor with respect to the magnetic field.w

[0058] n w =n efm -n r

[0059] The relative angle θ of the exciter rotor with respect to the magnetic field changing with time can be obtained by calculation w (range: 0 - 360°).

[0060] θ w =∫2πf(n w )dt + θ w0

[0061] When the system starts to operate, the initial position of the exciter is θ w0 (range: 0 - 360°), when θ w = 0, the stator phase A of the exciter is aligned with the rotor phase A

[0062] The position θ of the exciter rotor r (range: 0 - 360°) can be directly obtained by resolver measurement

[0063] 1.3 When the system is operating in the starting stage, the relative angle θ of the exciter rotor with respect to the magnetic field w is denoted as θ; when the system is operating in the power generation stage, the position θ of the exciter rotor r is denoted as θ

[0064] 1.4 Using the obtained angle θ, sample the sum of squares of the exciter stator current when the angle is in different ranges, and obtain the minimum value of the sum of squares of the exciter stator current in each range. The sampling ranges respectively defined for the starting stage and the power generation stage are shown in the following table

[0065] Start-up phase θ (°) Power generation stage θ (°) 35°～45° 5°～15° 95°～105° 65°～75° 155°～165° 125°～135° 215°～225° 185°～195° 275°～285° 245°～255° 335°～345° 305°～315°

[0066] Step 2: Judge whether the rotating rectifier fails according to the minimum value of the sum of squares of the exciter stator current in each sampling range, specifically

[0067] 2.1 Use a sliding register to compare the minimum value obtained in each sampling range with the minimum value obtained in the previous sampling range, and get the ratio, denoted as R

[0068] 2.2 Compare the ratio R calculated in 2.1 with the set thresholds R1 and R2: If R < R1, the rotating rectifier is working properly; if R1 < R < R2, the rotating rectifier has an open - circuit fault; if R2 < R, the rotating rectifier has a short - circuit fault

[0069] Step 3: After determining the fault in the rotating rectifier and identifying the fault type in Step 2, locate the faulty diode, i.e., determine its position (or number). Details are as follows:

[0070] 3.1 After a fault is detected, record the θ corresponding to the current sampling range, denoted as θ. f .

[0071] 3.2 Define the diodes of the upper and lower arms of phase a of the rotating rectifier as D1 and D4, respectively; the diodes of the upper and lower arms of phase b as D3 and D6, respectively; and the diodes of the upper and lower arms of phase c as D5 and D2, respectively. Based on θ calculated in 3.1... f The location and angle range are used to determine the faulty diode number, as shown in the table below:

[0072] <![CDATA[Startup phase θ f > Open circuit diode number Short-circuit diode number 35°～45° D1 D4 95°～105° D2 D5 155°～165° D3 D6 215°～225° D4 D1 275°～285° D5 D2 335°～345° D6 D3

[0073] <![CDATA[Power generation stage θ f > Open circuit diode number Short-circuit diode number 5°～15° D5 D2 65°～75° D6 D3 125°～135° D1 D4 185°～195° D2 D5 245°～255° D3 D6 305°～315° D4 D1

[0074] In the above steps, if the rotating rectifier is determined to be in a healthy state in step 2, then step 3 will not be performed; if the rotating rectifier is determined to be faulty in step 2, then step 3 will be performed.

[0075] To better understand the above technical solutions, the following will describe the above technical solutions in detail with reference to the accompanying drawings and specific embodiments. The present invention includes, but is not limited to, the following embodiments.

[0076] Figure 3 The diagram illustrates the underlying principles of the rotating rectifier fault diagnosis and location method proposed in this invention. Figure 4 The diagram shown is a block diagram of the rotating rectifier fault diagnosis and location method proposed in this invention.

[0077] The multi-stage starting / generating system used in this embodiment is a three-stage starting / generating system with a three-phase exciter, as shown in the schematic diagram below. Figure 1 As shown, the exciter stator excitation winding is a three-phase winding. During system operation, the motor speed is 400 r / min, the exciter stator excitation frequency is 60 Hz, and the exciter rotor current frequency is 40 Hz. Taking the system in the startup phase and the lower A-phase tube (D4) of the rotating rectifier open circuit as an example, the proposed fault diagnosis and location method is explained. The specific steps included in the embodiment are as follows:

[0078] 1. Obtain the sum of squares of the exciter stator current during motor operation, as follows:

[0079] (1.1) Use a current sensor to monitor the three-phase current i of the exciter stator. eA i eB icC , calculate the fault information amount, that is, the sum of the squares of the stator side currents of the exciter, as shown in the following formula.

[0080]

[0081] The result is as Figure 5 shown;

[0082] (1.2) The rotational speed n of the rotating magnetic field generated by the three-phase alternating current on the stator of the exciter efm and the motor speed n r Calculate the relative rotational speed n of the exciter rotor with respect to the magnetic field w

[0083] n w = n <00000​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​(3.2) In this embodiment, based on the obtained θ f Between 215° and 225°, the faulty diode can be identified as D4 using table (1.2). Figure 7 As shown.

[0092] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A method for on-line diagnosis of a full-stage rotary rectifier fault in a multi-stage start-up power generation system, characterized by The specific steps are as follows: Step 1 : Measure the field exciter stator side current, calculate the stator side current square sum from the measurement, also get the field exciter rotor position θ r Relative angle of the field exciter rotor to the magnetic field θ w ; Step 2: judging whether the rotating rectifier fails according to the minimum value of the square sum of the stator current of the exciter and in each sampling range; Step 3: when the rotating rectifier fails and the fault type is determined in step 2, the fault diode is located, that is, the position or number of the fault diode is determined; When the system is operating in the start-up phase, the relative angle of the exciter rotor with respect to the magnetic field θ w denoted θ ; When the system is operating in the power generation phase, the exciter rotor position θ r denoted θ ; Using the resulting angle θ The stator current square sum of the exciter is sampled when the angle is in different ranges, and the minimum value of the stator current square sum of the exciter in each range is obtained. The sampling ranges for the starting stage and the generating stage are shown in the following table respectively. ； The method for judging whether the rectifier fails in step 2 is: 2.1 The minimum value obtained from each sampling range is compared with the minimum value obtained from the previous sampling range using a sliding register, and the ratio is obtained, denoted as R ; 2.2 Comparing the ratio calculated in 2.1 R with a set threshold value R 1, R 2 the size of: if R R 1, the rotary rectifier is working properly;​ If R 1 R R 2, the rotating rectifier has an open circuit fault; if R 2 R , the rotating rectifier has a short circuit fault.​ 2. The method according to claim 1, wherein the method is characterized by: In step 1, the calculation method of the current square sum of the exciter stator side is as follows: the stator current of the exciter is collected by a current sensor, denoted as i eA , i eB , i eC , the current square sum of the exciter stator side is calculated, and the formula is as follows: Wherein, the exciter stator side current square sum i s 2 That is, the fault information quantity representing the fault state of the rotary rectifier.

3. The method according to claim 2, wherein the method is characterized by: In the step 1, first, the rotational speed of the rotating magnetic field generated by the three-phase AC of the exciter stator n efm With the motor rotational speed n r The relative rotational speed of the exciter rotor with respect to the magnetic field is calculated n w The relative angle of the exciter rotor with respect to the magnetic field is then calculated as a function of time θ w , θ w =0~360°, as follows: When the system is started, the exciter initial position is θ w0 , θ w0 =0-360°; when θ w =0, the exciter stator A phase is aligned with the rotor A phase.

4. The method according to claim 3, wherein the method further comprises: In step 1, the position of the exciter rotor θ r can be measured directly by the resolver, θ r = 0-360°.

5. The method of claim 1, wherein the method further comprises: determining whether the full-range rotary rectifier is in a normal state or a fault state based on the comparison result. The method for locating the fault diode in step 3 is: 3.1 When judging that a fault has occurred, record the sampling range corresponding to this time θ , denoted as θ f ; 3.2 The diode numbers of the upper and lower bridge arms of the rotating rectifier a phase are defined as D1 and D4 respectively, the diode numbers of the upper and lower bridge arms of the b phase are defined as D3 and D6, and the diode numbers of the upper and lower bridge arms of the c phase are defined as D5 and D2; The number of the fault diode is determined according to the angle range of the value calculated in 3.1, as shown in the following table: θ f The number of the fault diode is determined according to the angle range of the value calculated in 3.1, as shown in the following table: 。

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