CN111352031B - Method for detecting a fault state of an electric machine - Google Patents
Method for detecting a fault state of an electric machine Download PDFInfo
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- CN111352031B CN111352031B CN201911318307.5A CN201911318307A CN111352031B CN 111352031 B CN111352031 B CN 111352031B CN 201911318307 A CN201911318307 A CN 201911318307A CN 111352031 B CN111352031 B CN 111352031B
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- 238000000034 method Methods 0.000 title claims abstract description 39
- 238000004590 computer program Methods 0.000 claims description 6
- 239000004020 conductor Substances 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 230000005284 excitation Effects 0.000 description 4
- 230000015556 catabolic process Effects 0.000 description 3
- 238000006731 degradation reaction Methods 0.000 description 3
- 230000006870 function Effects 0.000 description 3
- 239000004065 semiconductor Substances 0.000 description 3
- 238000004364 calculation method Methods 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000015654 memory Effects 0.000 description 2
- 238000004804 winding Methods 0.000 description 2
- 238000012935 Averaging Methods 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000005669 field effect Effects 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 206010037844 rash Diseases 0.000 description 1
- 230000036962 time dependent Effects 0.000 description 1
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/34—Testing dynamo-electric machines
- G01R31/343—Testing dynamo-electric machines in operation
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/005—Testing of electric installations on transport means
- G01R31/006—Testing of electric installations on transport means on road vehicles, e.g. automobiles or trucks
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Combustion & Propulsion (AREA)
- Protection Of Generators And Motors (AREA)
- Rectifiers (AREA)
- Tests Of Circuit Breakers, Generators, And Electric Motors (AREA)
Abstract
The invention relates to a method for detecting a fault state (100C) of an electric machine (100), comprising a rotor (120), a stator (110) and a rectifier circuit (130) connected to the stator (110), wherein a time profile (200C) of the on-state value (UB+, IB+; U ph、Iph) of the electric machine (100) is detected (310), characterized in that a statistical variable (Q) of the on-state value (UB+, IB+; U ph、Iph) is determined, wherein a fault (F) in the rectifier circuit (130) is deduced when the statistical variable (Q) falls below a threshold value (S).
Description
Technical Field
The invention relates to a method for detecting a fault state of an electric machine, and to a computing unit and a computer program for carrying out the method.
Background
For supplying the grid or the load current loop, different types of generators may be used. For example, multiphase currents can be produced by means of an alternator. For feeding a direct current network from such an alternator, a converter operating as a rectifier can be used in order to convert the multiphase current generated by the alternating current source into direct current. The rectification can be carried out by means of passive (diode) or active (semiconductor switch) rectifying elements. In an active rectifier, in addition to the field regulator, a corresponding drive circuit is also part of the generator regulator. Alternators are often implemented as electric machines that operate as generators to produce electrical energy, or as motors to convert electrical energy into mechanical energy.
Such a generator may be used, for example, in a motor vehicle to supply the on-board electrical system of the motor vehicle. The corresponding electric machine can be operated, for example, as a generator in order to supply the vehicle electrical system or to charge the vehicle battery. For this purpose, the electric machine can be connected to the on-board electrical system or disconnected from the on-board electrical system by means of a so-called final stage (Endstufen) or final-stage circuit.
Disclosure of Invention
According to the invention, a method for detecting a fault state of an electric machine, a computing unit and a computer program for carrying out the method are proposed with the features of the independent claims. Advantageous embodiments are the subject matter of the dependent claims and the following description.
The electric machine can be designed in particular as an electric generator, for example as a claw-pole generator (Klauenpolgenerator) or a salient-pole generator (Schenkelpolgenerator), and/or as an electric machine which can be operated in motor-type and/or generator-type mode. The electric machine has, in particular, a rotor and a stator, and a rectifier circuit connected to the stator for rectifying an alternating voltage applied to the stator. The rectifier circuit may in particular have a bridge circuit formed by passive switching elements, in particular diodes, or by active switching elements, in particular semiconductor switches, for example Metal Oxide Semiconductor Field Effect Transistors (MOSFETs).
The following possibilities are provided by the invention: the different fault states and the intensities of the fault states of the motor are identified in a simple manner. So that in principle it can be classified according to the kind, extent and progress of the fault.
Within the scope of the method, a time profile of the switching value of the electric machine, in particular a time profile of the voltage value or the current value of the direct voltage, in particular of the rectified generator voltage or of the corresponding current, supplied by the electric machine is detected.
After the corresponding switch-on value has been determined, a statistical variable of the switch-on value is determined, wherein a fault in the rectifier circuit is deduced when the statistical variable falls below a threshold value. The use of statistical variables, which are compared with corresponding thresholds, which are preferably determined machine-specific, is particularly advantageous because the use of additional filters or the averaging of the data can in principle be made possible thereby.
Preferably, the quantiles of the on-values (Anschlusswert) are used as statistical variables. The use of a quantile has the advantage: in particular, it is possible to implement the method in fault diagrams represented in voltage or current curves, which are characterized by a particularly strong swing (Ausschlag) with respect to small or large voltage and/or current values. Furthermore, noise superimposed on the voltage signal or the current signal can be eliminated particularly well within the maximum range by means of the fractional number.
As quantiles, the following statistical variables are basically meant, which indicate which fraction of the data determined lies above or below the value defined by the quantiles. Preferably, quantiles in the interval 1% and 10%, preferably 2%, are used. The use of a fractional number which can be specifically adapted to the respective motor and/or to the fault to be detected is advantageous, since the respective fractional number can thus be adapted to the respective fault pattern or to the typical noise characteristics in the voltage and/or current values of the motor. A fraction of 2% thus means, for example, a voltage value in which 2% of the determined voltage value lies below this limit and 98% of the determined voltage value is equal to this limit or lies above this limit.
In a further preferred embodiment of the method, the statistical variable is determined in a time interval of preferably less than or equal to 100ms, more preferably less than or equal to 10 ms. The current method is particularly well suited for: the corresponding fault is also determined with great reliability by means of a small number of voltage or current characteristics, which carry information about the fault structure (fault diagram), in particular in the rectifier circuit of the electric machine. A very small time window of 10ms is therefore usually already sufficient, which, depending on the rotational speed of the motor, may contain a number of corresponding voltage characteristics of approximately 10. Within the interval, a corresponding number 10 or even fewer voltage characteristics are typically sufficient for reliable detection of the corresponding fault by means of the method.
In a further preferred embodiment of the invention, the threshold value is determined in the case of a fault-free motor on the basis of the minimum value of the on-state values. The respective threshold value can be determined, for example, in a fault-free motor, independent of different operating states of the motor, for example, different rotational speeds and load levels of the motor, and stored in the respective control unit. This is advantageous because a corresponding fault can be reliably deduced after a comparison of the threshold value with a corresponding quantile or a corresponding statistical variable.
In a further preferred embodiment of the method, the extent and/or progression of the fault is ascertained by means of the difference between the statistical quantity in the form of a fraction and the threshold value, in particular the increase in resistance between the two switching elements of one of the half-bridges of the rectifier circuit. The comparison of the score with the threshold value can thus be used at present not only for detecting faults, but also for determining the extent and/or progress of the fault taking into account the difference between the statistical quantity, in particular in the form of the score, and the threshold value. The larger the difference between the fractional number and the threshold value, the larger the extent or progression of the fault and thus the greater the resistance of the interruption. The interruption resistance is thus determined accordingly.
In this case, it is also possible to set a corresponding threshold for the difference value, according to which the fault appears to be only slight, medium or correspondingly strong. By means of appropriate thresholds, appropriate measures can preferably be provided, such as for example a fault in the alarm signal, an emergency operation of the motor, etc.
Advantageously, a time profile of the voltage value of the direct voltage applied to the rectifier circuit of the motor is detected. In particular, voltage values can be detected using measurement techniques between the dc voltage terminals of the motor or of the rectifier circuit and are usually detected for proper operation of the motor. It is also possible to detect at least one of the phase voltages and/or phase currents as a switching value in order to check the functionality of the electric machine within the scope of the method.
The invention is particularly advantageously suitable for use in motor vehicles. In this case, the motor vehicle electrical system can be fed and/or the motor vehicle battery can be charged via the electric machine, for example. The on-board motor vehicle electrical system can be connected to the dc voltage terminals of the rectifier circuit. In particular, the time profile of the direct voltage and/or of at least one phase voltage applied between the direct voltage terminals is detected within the scope of the method, and the functional performance (Funktionstuechtigkeit) is determined according to the invention on the basis of this voltage profile.
The method for detecting a fault state can be performed, for example, by a control unit of the motor vehicle. The invention is suitable, for example, in particular for motor vehicles with functions which have higher safety requirements, for example automated or autonomous driving, or for vehicles with long service intervals, for example commercial vehicles.
The inventive computing unit, for example a control unit of a motor vehicle, is provided in particular in terms of programming technology for carrying out the inventive method.
The implementation of the method in the form of a computer program is also advantageous, since this results in particularly low costs, in particular if the implemented controller is also able to be used for other tasks and therefore is already present. Suitable data carriers for providing computer programs are in particular magnetic, optical and electrical memories, such as hard disks, flash memories, EEPROMs, DVDs, etc. The program may also be downloaded via a computer network (internet, intranet, etc.).
Drawings
Other advantages and design aspects of the invention will be apparent from the description and drawings.
The invention is schematically illustrated in the drawings by way of example and is described below with reference to the accompanying drawings:
Fig. 1 shows a schematic illustration of an electric machine with a preferred embodiment of the computing unit according to the invention, which is provided for carrying out a preferred embodiment of the method according to the invention;
Fig. 2 shows a schematic voltage-time diagram of a time-dependent curve of the current values, which can be determined during a preferred embodiment of the method according to the invention;
Fig. 3a, b schematically show the motor in the fault state (a) and the generator voltage in the fault state (b);
fig. 4a, b show the curves of the phase voltages without fault (a) and with fault (b) in one of the rectifier paths; and
Fig. 5 schematically shows a flow chart of a method for identifying faults.
Detailed Description
An electrical machine in the form of a generator is schematically shown in fig. 1 and is denoted by reference numeral 100.
The motor 100 is designed in this example as a three-phase motor, wherein the stator inductances (phases) of the stator 110 are connected in a delta circuit. The rotor 120 has field windings 121 with diodes connected in parallel. A field transistor 122 may also be provided in the field circuit. By switching the excitation transistor 122 on and off, typically by means of PWM operation, a voltage (here a rectified generator voltage) is intermittently applied to the excitation winding 121, whereby an excitation current is generated. The height of the excitation current and thus the height of the generator voltage can be varied in particular by varying the Duty Cycle (Duty Cycle) of the PWM operation, which is also referred to as the drive ratio.
The motor 100 further has a rectifier circuit 130 connected to the stator 110, with three half-bridges for rectifying the three-phase ac voltage applied to the stator 110. Each half-bridge has an intermediate tap between its two rectifier elements, which are configured here as diodes, via which the respective half-bridge is connected to the connection of the stator 110. For commutation or for motor operation of the electric machine, active switching elements (not shown) in the form of transistors may also be provided.
A dc voltage ub+ is provided between the two dc voltage connections 140 of the rectifier circuit 130 as rectified generator voltage. The electric machine 100 can be used, for example, in a motor vehicle for supplying an onboard electric system of the motor vehicle, which is connected to the dc voltage connection 140.
The calculation unit 150 is provided for driving the motor 100. The computing unit 150 may be configured, for example, as a controller of the respective motor vehicle. The calculation unit 150 is arranged to perform an identification of a fault state of the motor. For this purpose, the computing unit 150 is provided in particular in programming technology for executing a preferred embodiment of the method according to the invention.
Fig. 2 schematically shows a time profile 200 of dc voltage ub+ in a fault-free state of motor 100 in a voltage-time diagram.
Fig. 3a schematically shows the motor of fig. 1 in a fault state. In addition, fig. 3b schematically shows a voltage profile of the direct voltage ub+ similar to fig. 2, which can be detected in step 310 in the course of the method in the present fault state.
The motor of fig. 1 in a fault state 100C is schematically shown in fig. 3 a. In this first fault state 100C, there is an interruption in the switching element path of the rectifier circuit 130. In this case, an elevated (optionally endless) resistance R 3 is present between the two switching elements of one of the half-bridges of the rectifier circuit 130. Fig. 3b schematically shows a corresponding curve 200C of the dc voltage ub+ that can be detected in this fault state 100C. Fig. 3b shows a time profile 200C of the dc voltage ub+, which can be detected in step 310 in the course of the method in this fault state 100C. Such failure determination may be performed based on the phase voltage U ph or the phase current I Ph. Fig. 3a shows a voltage or current tap, and fig. 4 a) shows the course of the phase voltage U ph for the reference voltage U Ref in a fault-free state of the motor 100, in particular of the rectifier circuit, and fig. 4 b) shows the course of the phase voltage U ph for the fault state 100C.
Also shown in fig. 4 is the threshold S in a non-faulty motor (see fig. 4 a) and a faulty motor 100, in which a degradation of the conductor element between the two switching elements of the half-bridge of the rectifier circuit 130, for example, occurs, with a consequent increase in the resistance of the resistor R 3. The fraction Q is also shown in the present case as a characteristic feature of fault detection, for example by means of a 2% fraction for a fault-free motor (fig. 4 a) and a fault-free motor (see fig. 4 b).
In the case of a fault-free motor (fig. 4 a), it can be seen that the minimum value of the phase voltage U Ref ends approximately below the zero line and that the quantile of the 2% quantile Q is always above the threshold value of approximately-2.5 volts. With this characterization criterion, it is thus possible to reliably infer a well-functioning motor 100, in particular a fault-free function of the switching elements in the half-bridge and a connection between the half-bridges of the rectifier circuit 130.
In the event of a fault (see fig. 4 b), the minimum swing of the phase voltage U Ph is significantly beyond-10 volts. This characteristic characterizes the increase in resistance in the conductive connection between the corresponding switching elements of the half bridge and in the rectifier circuit 130. In the event of a fault, the respective fraction in the form of a 2% fraction is also significantly shifted downward by a corresponding drop in the minimum value of the phase voltage U Ph, so that in the event of a fault the fraction Q in the form of a 2% fraction always extends below the threshold S defined for the motor without fault. By means of this criterion, a fault can be reliably deduced and a specific allocation of the fault in view of degradation of at least one conductor between two switching elements within the half bridge of the rectifier circuit 130 can also be deduced. Based on the deviation value of the quantile, which is currently in the form of a 2% quantile, from the corresponding threshold value S, the extent and/or progression of the fault or degradation of the conductor element between two switching elements within the half-bridge of the rectifier circuit 130 can also be deduced. The larger the deviation value between the quantile Q and the threshold value S, the larger the range of the fault or the wider the progression. That is, the larger this value, the larger the degraded resistance R 3 allocated to the conductor element between the two switching elements.
Fig. 5 shows a schematic flow chart of the method according to the invention for determining the spring state of an electric machine, in particular the increase in resistance R 3 between the two switching elements of one of the half-bridges of the rectifier circuit 130.
The method begins with an initialization step 300. In step 310, the switching values in the form of the rectifier voltage ub+ or the rectifier current ib+ and/or the phase voltages U Ph and/or I Ph are determined (step 310). In step 320, the corresponding on values ub+, ib+ are determined; the quantile 320 of U Ph、IPh. Preference is given here to quantiles in the range from 1% to 10%, preferably 2%. In step 330, the determined quantile in the interval of preferably 100ms, preferably about 10ms, is compared with a threshold S determined in the fault-free state of the motor 100. If the fraction Q is now less than or equal to the threshold value S, then a corresponding fault (marked by +) of the motor 100 is identified in step 340. If a fault is also identified in step 340, then one or more steps may optionally be imported in step 345. These steps include, inter alia, warning prompts or corresponding emergency running functions of the motor 100 in order to prevent further progress of the fault state. A corresponding warning and/or prompting of the replacement of the motor 100 should be effected as quickly as possible, also in step 345.
The method then ends in step 360. If the fraction Q is now greater than the corresponding threshold value, then in step 350 a fault-free motor 100 (labeled) is detected for the fault to be detected. If the motor 100 is now identified as being fault-free, the method is likewise temporarily ended in step 360. It is possible here again to continue the method at another point in time with step 300.
Claims (11)
1. Method for detecting a fault state (100C) of an electric machine (100) having a rotor (120), a stator (110) and a rectifier circuit (130) connected to the stator (110), wherein a time profile (200C) of a switching value of the electric machine (100) in the form of a rectifier voltage (ub+) or a rectifier current (ib+) and/or a phase voltage (U Ph) and/or a phase current (I Ph) is detected (310), characterized in that a statistical variable (Q) of the switching value is determined (204), wherein a threshold value (S) is determined on the basis of a minimum value of the switching value in a fault-free electric machine (100), and a fault (F) in the rectifier circuit (130) is deduced when the statistical variable (Q) is below the threshold value (S), wherein the statistical variable is a quantile (Q) of the switching value.
2. Method according to claim 1, wherein said quantiles (Q) are in the interval of 1% and 10%.
3. A method according to claim 2, wherein the quantile (Q) is 2%.
4. A method according to any one of claims 1 to 3, wherein said statistical quantity (Q) is determined within a time interval (Δt).
5. Method according to claim 4, wherein said statistical quantity (Q) is determined in a time interval less than or equal to 100 ms.
6. Method according to claim 5, wherein said statistical quantity (Q) is determined in a time interval of less than or equal to 10 ms.
7. A method according to any one of claims 1 to 3, wherein the extent and/or progress of the fault (F) is deduced by means of the difference between the statistical quantity (Q) and the threshold value (S).
8. The method according to claim 7, wherein a resistance increase (R 3) between two switching elements of one of the half-bridges of the rectifier circuit (130) is deduced by means of a difference between the statistical quantity (Q) and the threshold value (S).
9. Computing means (150) arranged by hardware and/or by software for performing the method according to any of the preceding claims.
10. Computer program product which, when implemented on a computing device (150), causes the computing device (150) to perform the method according to any one of claims 1 to 8.
11. A machine-readable storage medium having stored thereon the computer program product according to claim 10.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE102018222575.3 | 2018-12-20 | ||
| DE102018222575.3A DE102018222575A1 (en) | 2018-12-20 | 2018-12-20 | Method for recognizing an error state of an electrical machine |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN111352031A CN111352031A (en) | 2020-06-30 |
| CN111352031B true CN111352031B (en) | 2024-10-29 |
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| CN201911318307.5A Active CN111352031B (en) | 2018-12-20 | 2019-12-19 | Method for detecting a fault state of an electric machine |
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| Country | Link |
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| CN (1) | CN111352031B (en) |
| DE (1) | DE102018222575A1 (en) |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017129285A1 (en) * | 2016-01-27 | 2017-08-03 | Robert Bosch Gmbh | Method for detecting an error in a generator unit |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| GB2122749B (en) * | 1982-06-17 | 1985-07-10 | Standard Telephones Cables Ltd | Electrical condition monitoring of electric motors |
| US5629870A (en) * | 1994-05-31 | 1997-05-13 | Siemens Energy & Automation, Inc. | Method and apparatus for predicting electric induction machine failure during operation |
| DE10347185A1 (en) * | 2003-10-10 | 2005-05-12 | Bosch Gmbh Robert | Generator defect detecting method e.g. for motor vehicle, involves taking up electrical system voltage and evaluating ripples of electrical system voltage in order to determine generator defect |
| JP4433064B2 (en) * | 2008-03-03 | 2010-03-17 | 株式会社デンソー | Anomaly detection device |
| DE102008041043A1 (en) * | 2008-08-06 | 2010-02-11 | Robert Bosch Gmbh | Method for testing armature of electric motor, particularly direct current motor, involves exciting armature in armature position, and determining characterized measuring parameter |
| FR2995083B1 (en) * | 2012-08-30 | 2016-01-29 | Renault Sas | DEVICE FOR DETECTING AND MEASURING ISOLATION FAULT |
| DE102013200637A1 (en) * | 2013-01-17 | 2014-07-31 | Robert Bosch Gmbh | A method of detecting an electrical fault in a generator assembly and means for implementing it |
| DE102014217928A1 (en) * | 2014-09-08 | 2016-03-10 | Robert Bosch Gmbh | Method and apparatus for detecting a DC fault current |
| GB201503930D0 (en) * | 2015-03-09 | 2015-04-22 | Rolls Royce Plc | Fault detection and diagnosis in an induction motor |
| DE102015211933A1 (en) * | 2015-06-26 | 2016-12-29 | Robert Bosch Gmbh | Method for detecting a fault in a generator unit |
| DE102015222773A1 (en) * | 2015-11-18 | 2017-05-18 | Robert Bosch Gmbh | Method for detecting a fault in a generator unit |
| DE102016220235A1 (en) * | 2016-10-17 | 2018-04-19 | Seg Automotive Germany Gmbh | Detecting a fault in a generator unit |
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2018
- 2018-12-20 DE DE102018222575.3A patent/DE102018222575A1/en active Pending
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Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017129285A1 (en) * | 2016-01-27 | 2017-08-03 | Robert Bosch Gmbh | Method for detecting an error in a generator unit |
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| Publication number | Publication date |
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| CN111352031A (en) | 2020-06-30 |
| DE102018222575A1 (en) | 2020-06-25 |
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