DE102020215366A1 - Monitoring method and device for an electric propulsion system - Google Patents

Abstract

The invention relates to a monitoring method for an electric drive system (100) with at least one subsystem (10, 20) each with at least one electric submotor (11, 12) designed as a 3-phase motor, characterized bya) monitoring the operation the electrical drive system (100) with a monitoring device (50), with operating data for a positive sequence system, a negative sequence system and a zero sequence system being monitored as symmetrical components of at least one sub-motor (11, 12, 21, 22), andb) with a negative sequence system monitoring means (51) a deviation of at least one parameter of the counter-system from a predetermined condition is detected and c) and in response to the detection of the deviation at least one control signal (S, Su, SI, SN) for the electric drive system (100) is emitted. The invention also relates to a monitoring device.

Description

The present disclosure relates to a monitoring method having the features of claim 1 and a monitoring device having the features of claim 5.

Electrical drive systems, in particular for aircraft, are known in principle.

In this case, for example, electrical drives (electrical propulsion units) in aircraft are arranged in individual subsystems, each of which has an inverter device, a control unit and at least one 3-phase submotor. The partial engines, also referred to as sub-engines, together form the overall engine that drives a propeller of the aircraft engine.

Now, if a failure occurs in one of the subsystems, that subsystem can be shut down, while the remaining subsystems remain in operation to continue driving the propeller.

It is known, for example, to monitor the behavior of the inverter device in order to infer errors in a subsystem.

However, many faults in the electrical part of the subsystems, e.g. in a control unit, cannot be clearly identified. In addition, the regulation of the current and the regulation of the speed in the subsystem affect the effects of faults, which also makes it difficult to detect faults.

Since not all errors in a subsystem are detected, it is also difficult to certify the drives.

The task is therefore to detect faults in a subsystem in a robust manner.

This is made possible by a monitoring method for an electric drive system having the features of claim 1. The electrical drive system has at least one subsystem, each with at least one electrical submotor, which is designed as a 3-phase motor.

First, the operation of the electric drive system is monitored using a monitoring device, with electrical operating data for a positive sequence system, a negative sequence system and a zero sequence system being monitored as symmetrical components of at least one sub-motor. The presentation of the operating data in the form of the symmetrical components is fundamentally known.

A deviation of at least one parameter of the negative system from a predetermined condition is then detected with a negative system monitoring means. The deviation can be defined, for example, by exceeding or falling below threshold values. Calculated deviations, e.g. using time averaging or other filter measures, can also be taken into account.

In response to the detection of the deviation, at least one control signal for the electric drive system is then output.

Robust monitoring can be implemented by using part of the symmetrical components, namely the negative sequence system. The cause of the error can then be determined more precisely and eliminated as part of an inspection.

Such monitoring is easy to implement, with a large number of electrical faults being able to be detected in at least one subsystem during operation. This means that error detection is not limited to a single error source in the sub-system, as would be the case, for example, with the detection of an overvoltage as a result of a short circuit in a winding of the sub-motor.

In one embodiment, the at least one parameter of the negative sequence system can be a voltage value and/or a current value.

Furthermore, a control signal can be determined from current data of the negative sequence system and/or from voltage data of the negative sequence system if a deviation from a predetermined condition is determined for the current data of the negative sequence system and/or for the voltage data of the negative sequence system. In principle, it is sufficient for a single condition for a deviation to be met in order to trigger a control signal. This allows you to react accordingly to an error that has occurred.

The object is also achieved by a monitoring device having the features of claim 5.

• 1 eine schematische Darstellung einer Ausführungsform einer Überwachungsvorrichtung;
• 1A eine schematische Darstellung einer weiteren Ausführungsform einer Überwachungsvorrichtung;
• 2 eine Ausführungsform für eine Überwachung eines Nullsystems eines Teilsystems eines elektrischen Antriebssystems in zwei Teilen (2A, 2B):
• 3 eine Darstellung von Signalverläufen zur Fehlerdetektion.

Exemplary embodiments will now be described with reference to the figures; show

• 1 a schematic representation of an embodiment of a monitoring device;
• 1A a schematic representation of a further embodiment of a monitoring device;
• 2 an embodiment for monitoring a null system of a subsystem of an electric drive system in two parts ( 2A , 2 B ):
• 3 a representation of signal curves for error detection.

In the following, embodiments for a monitoring device and a monitoring method for an electrical drive system 100 are presented, such as those used in an aircraft engine 30 (see FIG 1 ) can be used. However, the embodiments are not limited to this application.

The drive power for the aircraft engine 30 is applied by electric motors 11, 12, 21, 22, which are arranged in subsystems 10, 20 (“lanes” in English). Since the electric motors 11, 12, 21, 22 each provide part of the power, they are referred to here as partial motors 11, 12, 21, 22. The sub-motors 11, 12, 21, 22 and also the sub-systems 10, 20 are shown here as parallel structures, since the failure of a sub-motor 11, 12, 21, 22 and/or a sub-system 10, 20 does not result in no power more is transmitted to the aircraft engine 30.

Rather, the remaining functioning sub-engines 11, 12, 21, 22 and/or sub-systems 10, 20 supply the aircraft engine 30.

However, the parallel and hierarchical representation selected here does not mean that the sub-motors 11, 12, 21, 22 must also be arranged in parallel in the mechanical sense. Rather, for example, the first sub-motor 11 and the second sub-motor 12 can act in series on a drive shaft (see e.g 1A ), The failure of one of the two sub-motors 11, 12 is compensated by the other. This also applies analogously to subsystems 10, 20.

For reasons of clarity, in 1 only two subsystems 10, 20 are shown, with other subsystems can be constructed similarly. The inverter devices 25 that are usually present in the subsystems 10, 20 are also in the 1 not shown.

It is also possible that more than two sub-motors 11, 12, 21, 22 are used in a sub-system 10, 20. It is not mandatory that the same number of sub-motors 11, 12, 21, 22 is used in each sub-system 10, 20 or that the designs or performance of the sub-motors 11, 12, 21, 22 are identical.

The sub-motors 11, 12, 21, 22 are constructed in a basically known manner as 3-phase motors. If, for example, there is a fault in one of these sub-engines 11, 12, 21, 22 or another unit of the sub-system 10, 20, the functioning of the aircraft engine 30 will be impaired, so that control intervention may become necessary.

As explained in more detail below (see 2 and 3 ), uses a monitoring device 50 electrical data from the operation of the subsystems 10, 20, in particular the sub-motors 11, 12, 21, 22 to detect errors in operation.

During operation, the time-dependent voltage and current curves of the 3-phase motors 11, 12, 21, 22 can be described using the system of symmetrical components, which is known per se. The operating characteristics of an electric 3-phase drive can basically be expressed by a positive sequence, a negative sequence and a zero sequence according to the principle of symmetrical components.

The symmetrical components basically assume that only the positive sequence system occurs in error-free operation.

However, due to manufacturing tolerances, e.g. in the individual windings of a sub-motor 11, 12, 21, 22 or in a power section of the inverter device 25, the current behavior is slightly asymmetrical. For this reason, a slight counter-system always occurs in reality. However, a zero system does not exist in error-free operation.

In the event of electrical faults within a subsystem 10, 20, the three phases of the submotors 11, 12, 21, 22 are affected differently.

This leads to a strong increase in the negative phase sequence in the current of a sub-motor 11, 12, 21, 22.

If regulation of the current in a sub-motor 11, 12, 21, 22 can at least partially compensate for the effect of the error, the negative sequence system is still evident in the voltage profile of the sub-motors 11, 12, 21, 22.

As described below, the monitoring device 50 (e.g. a small computer) continuously monitors the current curves, the voltage curves and the speeds n of the sub-motors 11, 12, 21, 22 with a negative-sequence system monitoring means 51 in order to determine at least one parameter of the negative-sequence system.

If at least one parameter of the negative-sequence system deviates from a predetermined condition during operation, the negative-sequence system monitoring means 51 detects an error therein and emits a corresponding control signal S, which can lead, for example, to switching off a sub-motor 11, 12, 21, 22 or a sub-system 10, 20.

1A shows another representation of an embodiment of a monitoring device, which basically on the description of the 1 can be referred to.

Here three sub-motors 11, 12, 21, which are part of an aircraft engine 30, jointly drive a propeller. Each sub-motor 11, 12, 21 receives three-phase current via three-phase lines 27. The three-phase current is generated by inverter devices 25, which in turn receive direct current via direct current lines 26. An inverter device 25 is assigned to each sub-motor 11, 12, 21. An inverter device 25 and a sub-motor 11 each form a sub-system 10, which is represented here by a dashed box.

Thus shows the 1A three subsystems that all act on the shaft of the propeller. If one of the sub-motors 11, 12, 21 has an error, this can - be switched off - as described above. A monitoring device 30 is assigned to each of the subsystems here.

If the sub-motor 11, 12, 21, 22 is designed as a permanent magnet motor (permanently excited synchronous motor) or as a reluctance motor, the current data or voltage data of the negative sequence system can be specially filtered in order to determine an incorrectly measured or incorrectly calculated speed in addition to an electrical error.

In the 2 a signal flow chart is shown for a subsystem 10, 20, which shows the determination of parameters of the negative system and the generation of control signals S resulting therefrom. Here is the 2 divided into two parts. the 2A shows the first part of the signal flow diagram, which follows the second part in the 2 B connects.

Input variables are time-dependent voltage data U_N_1(t), U_N_2(t), U_N_3(t) of a sub-motor 11, 12, 21, 22. Here the voltage values of the three phases _VL1 , _VL2 and _VL3 are processed according to the symmetrical components.

The individual steps in the signal flow plan, which are denoted by Roman numerals, are discussed below. The sequence of digits does not correspond to a chronological sequence; this results from 2 even.

In step I, the phase voltages are determined from the line-to-line voltages. In the subsequent step II, the α and β components of the rotating voltage vector are then determined.

Input variables are also time-dependent current data 11, 12, 13. In step III—analogously to step II—the α and β components of the rotating current vector are determined.

In step IV (in 2 B ) the stress pointer is transformed into the rotating coordinate system. Again analogous to this, in step V the current vector is transformed into the rotating coordinate system.

In step VI (in 2 B ) the positive-sequence system component and the zero-sequence system component are filtered out in the voltage phasor. In step VII, the positive-sequence system component and the zero-sequence system component are filtered in the current vector.

Step VIII then determines the magnitude of the remaining voltage phasor, which corresponds to the negative sequence sequence phasor for the voltage.

In step IX, the magnitude of the remaining current pointer, which corresponds to the negative sequence pointer for the current, is determined.

Finally, in step X, the limit value for the absolute value of the negative phase sequence vector of the voltage is queried.

Finally, in step XI, the limit value for the absolute value of the negative sequence vector of the current is queried.

Other input sizes (in 2A ) are the time-dependent speed n(t) of the partial motor 11, 12, 21, 21 and the number of pole pairs of the partial motor 11, 12, 21, 22, ie a constant.

In step XIII (in 2A ) the electrical frequency is calculated from the input data, in step XII the transformation angle.

In step XIV (in 2 B ) then the negative phase sequence vector of the current is filtered to detect a possibly faulty speed measurement. The filtering here corresponds to an averaging.

Finally, in step XV, the limit value for the filtered negative phase sequence vector of the current is queried to detect an incorrect speed measurement.

If there is a deviation from the previously known condition, for example if a limit value is not reached or exceeded, a control signal S _n , S ₁ is triggered in each case. The control signal S _n is then based on the deviation of the speed-based data, and the control signal S _I is based on the current-based data.

The procedure with the voltage-based data in step I is analogous, so that a comparison with a predetermined condition is also carried out there. A control signal Su is then generated as a function of the comparison.

Each individual control signal S _n , S _U , S _I can be used individually or in combination with others as a control signal S (see 1 ) are used to control the aircraft engine 30.

In 3 the function of an embodiment of the monitoring method is shown as part of a test.

A periodically occurring error is shown in the penultimate line "Error activation" in the form of a square-wave signal.

In the top three lines, the "speed", the "phase of the voltages" and the "phase of the currents" are shown.

The effect of the error can be seen in the bottom line "Negative phase sequence current", although the effect is not so clearly visible due to the scaling. Therefore, in the enlargement displayed at the top right, it becomes clear how the negative sequence system changes due to the error.

Reference List

10

first subsystem

11

first sub engine

12

second sub engine

21

third sub engine

22

fourth sub engine

25

inverter device

26

direct current line

27

Three-phase line, 3-phase system

20

second subsystem

30

Aircraft propulsion (electrical propulsion unit)

50

monitoring device

51

negative sequence monitor means

100

electric drive system

S

control signal in the event of an error

Claims (5)

Monitoring method for an electrical drive system (100) with at least one subsystem (10, 20) each with at least one electrical submotor (11, 12, 21, 22), which is designed as a 3-phase motor, characterized by a) the monitoring of the Operation of the electric drive system (100) with a monitoring device (50), with operating data for a positive sequence system, a negative sequence system and a zero sequence system being monitored as symmetrical components of at least one sub-motor (11, 12, 21, 22), and b) with a negative sequence system monitoring means ( 51) a deviation of at least one parameter of the counter-system from a predetermined condition is detected and c) in response to the detection of the deviation, at least one control signal (S, S _U , S _I , S _N ) for the electric drive system (100) is emitted . monitoring procedures claim 1 , characterized in that the at least one parameter of the negative sequence system is a voltage value (D) and/or a current value (E). monitoring procedures claim 1 or 2 , characterized in that the at least one parameter of the counter-sequence system is linked to time-dependent speed data. Monitoring method according to at least one of the preceding claims, characterized in that a control signal (S _I , S _U , S _n ) is determined from current data of the negative sequence system, from voltage data of the negative sequence system and/or speed data of the negative sequence system if there is a deviation from a predetermined condition for the negative sequence current data, for the negative sequence voltage data and/or for the negative sequence speed data. Monitoring device for an electrical drive system (100) with at least one subsystem (10, 20) each with at least one electrical submotor (11, 12, 21, 22), which is designed as a 3-phase motor, characterized in that the monitoring device ( 50) monitors a positive-sequence system, a negative-sequence system and a zero-sequence system as symmetrical components of the at least one sub-motor (11, 12, 21, 22) during operation and has a negative-sequence system monitoring means (51) with which a deviation of at least one parameter of the negative-sequence system from a predetermined condition is detectable and in response thereto min at least one control signal (S, Su, S _I , S _N ) can be emitted.

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