Method and system for monitoring electric machine
By detecting the stray magnetic field and electrical model of the motor, and calculating the mechanical output power and power loss in real time, the accuracy and cost of motor efficiency and energy consumption monitoring in the prior art are solved, and efficient monitoring and optimization of motor operation are achieved.
Patent Information
- Application Number
- CN202380040119.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-05-13
- Filing Date
- 2023-05-03
- Publication Date
- 2024-12-24
AI Technical Summary
The prior art is difficult to accurately monitor the actual efficiency and energy consumption of motors in dynamic environments, especially in the case of multiple motors, and it is impossible to calculate the efficiency and losses during operation in real time, resulting in rough and costly efficiency prediction.
By detecting the stray magnetic field of the motor, combining electrical models, calculating the mechanical output power and power loss, calculating the motor's efficiency in real time, and integrating energy consumption under uninterrupted conditions, providing efficiency visualization and optimization suggestions, supporting industrial IoT devices monitoring.
Real-time efficiency monitoring and energy consumption calculations during motor operation are achieved, reducing costs, improving efficiency prediction accuracy, and providing optimization suggestions to improve motor operation efficiency and reduce carbon footprint.
Smart Images
Figure CN119183638A_ABST
Abstract
Description
Technical Field
[0001] The subject matter disclosed herein relates to methods and systems for monitoring electric machines.
[0002] Furthermore, the subject matter disclosed herein relates to a computer program comprising instructions for causing the above-described system to perform the above-described method, and to a computer-readable medium having such a computer program stored thereon. Background Art
[0003] In order to assess the carbon footprint of a motor or generate information about its operating costs, it is inevitable to obtain information about the corresponding electrical energy consumption by acquiring the electrical input power during operation, i.e., taking into account the actual / individual load situation of the motor. IIoT devices for condition monitoring (e.g., soft sensors) usually only provide motor torque and motor speed, which are not sufficient to determine the motor efficiency and thus the motor energy consumption.
[0004] One possible solution to the above problem of taking into account the actual load situation is to use a dynamometer connected to the motor terminals (a very expensive device) and a torque / speed sensing device connected to the shaft during the entire monitoring period, which is prohibited when multiple motors are to be monitored due to the original effort and cost. Retrospective energy consumption calculations (based only on easily available quantities such as recorded torque and speed values) are not possible.
[0005] In the offline case, a specific load profile and specific motor properties have to be assumed, the latter usually only available in fixed / discrete steps (e.g. full load efficiency, half load efficiency, etc.), and the result is a single value kWh amount for a predetermined period of time under relatively rough assumptions. This does not reflect the true state of the motor operation. Summary of the invention
[0006] The subject matter disclosed herein provides a solution to the above-mentioned problem in the form of a method for monitoring an electric machine (e.g., a rotating electric machine), in particular a plurality (two, three, ten, one hundred or even more) of electric machines during operation (in particular during their continuous operation). The method comprises the following steps: detecting a stray magnetic field of the electric machine (each electric machine) in a detector; determining operating point data of the electric machine based on the detected stray magnetic field and an electrical model of the electric machine; determining a mechanical output power p of the electric machine using the electrical model and the operating point data mech (t) and power loss p losses (t); and determine (by continuous, in particular uninterrupted, calculation during the operation of the motor) the efficiency η(t) of the motor from the mechanical output power and the power losses. For example, the formula can be used:
[0007]
[0008] It should be understood that the terms "continuous, uninterrupted" refer to situations where interruption or discontinuity may occur unexpectedly due to some unexpected events (such as fire, power outage, natural disasters, etc.).
[0009] This method allows the efficiency of the motor to be calculated as a function of the load during its operation.
[0010] The term "operation" here means that the motor is used as a field device in a manufacturing plant, automation facility or factory (i.e. where the motor load varies). This means that no additional equipment can be used to monitor each motor. This would introduce additional costs, but most importantly, be very time-consuming. The variation of motor load is a multidimensional problem, and various quantities affect the losses of the motor, such as torque, speed, thermal conditions, etc. This means that the motor is usually operated in a dynamic environment and its actual efficiency deviates far from the efficiency measured in standardized procedures under standardized conditions during motor type testing and far from individual operation under real-world conditions.
[0011] In one embodiment, the power loss p losses (t) Includes but is not limited to ohmic losses of the stator and rotor, core losses, windage and friction losses, and additional losses related to the load.
[0012] In one embodiment, the detector includes a magnetic field detector for receiving a stray magnetic field. The stray magnetic field includes a characteristic frequency. By performing a frequency analysis, the stator frequency (i.e., the current frequency in the stator winding) and the current frequency in the rotor winding can be determined from the stray magnetic field. These two frequencies can be used to determine the speed, slip, and other quantities related to determining the operating point of the motor.
[0013] In one embodiment, the method further comprises calculating the energy consumption of the motor based on the mechanical output power and energy efficiency of the motor during the determined time interval. This can be done by calculating the electrical input power p el (t) and integrate it over a certain time interval to achieve
[0014]
[0015] In one embodiment, the method further comprises: visualizing the energy efficiency of the electric machine as a function of time.
[0016] In one embodiment, the method further includes: if the energy efficiency is below a predetermined threshold, notifying that the threshold is not reached.
[0017] In one embodiment, the method further comprises:
[0018] - using a reference electrical model of the reference motor and the operating point data of the (original) motor to determine the mechanical output power and the power losses of the reference motor,
[0019] - Determine the reference efficiency of the reference motor based on the mechanical output power and power losses,
[0020] - Compare the reference efficiency with the efficiency of the (original) motor.
[0021] In one embodiment, the method further includes recommending (eg, periodically recommending) use of an additional motor that is more efficient if the reference motor is more efficient than the motor.
[0022] In one embodiment, the method includes making recommendations (eg, periodic recommendations) to optimize the efficiency of the motor.
[0023] In one embodiment, the proposal includes a visualization of the carbon footprint of the electric machine, wherein the carbon footprint is calculated based on the efficiency of the electric machine.
[0024] In one embodiment, the recommendations may include recommendations for changes to the operating state of the motor, for example, recommendations may be made to change the voltage / flux (of the motor's inverter), the load (e.g., if the motor is operating under an overload, then reduce the load, or if the motor is operating under a load, then increase the load), etc.
[0025] In one embodiment, the method further comprises calculating a reference energy consumption of the reference motor and an energy consumption of the (original) motor within a predetermined time interval, and comparing the reference energy consumption of the reference motor with the energy consumption of the (original) motor.
[0026] In one embodiment, the method further comprises: receiving mechanical vibrations of the motor, for example in an acceleration detector, and using the detected mechanical vibrations to determine the operating point data. Based on the mechanical vibrations, the speed of the rotor can be directly determined by performing a spectrum analysis. In this case, the method is faster.
[0027] In one embodiment, the detector comprises an acceleration detector.
[0028] In one embodiment, determining the operating point data of the electric machine includes determining the speed and torque of the electric machine.
[0029] In one embodiment, the electrical model is designed as an extended equivalent circuit. In addition to other motor-specific parameters (main inductance X h (main flux), stator leakage inductance X1 and rotor leakage inductance X'2 (leakage flux), rotor resistance R'2 (for rotor winding loss), stator resistance R1 (for stator winding loss), R fe (for core loss), the extended equivalent circuit also includes an additional resistor R responsible for additional lossesadd .
[0030] The losses can be determined by solving the extended equivalent circuit and calculating the power in the corresponding resistors.
[0031] In one embodiment, the method further comprises: determining parameters of the extended equivalent circuit based on / by using the nameplate data.
[0032] The problem is also solved by providing a system having a detector for detecting a stray magnetic field of an electric machine and a computing device adapted to perform the above method.
[0033] In one embodiment, the system is designed as an IIoT-enabled device (IIoT:=Industrial Internet of Things). BRIEF DESCRIPTION OF THE DRAWINGS
[0034] The above and other objects and advantages of the present invention will become apparent in view of the following detailed description of certain aspects, which only indicates several possible ways in which the present invention may be implemented. The present invention is described in conjunction with the accompanying drawings, in which the same reference numerals refer to the same parts throughout the drawings, wherein:
[0035] Figure 1 shows the monitoring of a rotating electrical machine in operation,
[0036] Figure 2 shows the extended circuit of the motor,
[0037] Figure 3 is a flow chart of a method for monitoring energy consumption of an electric machine in operation. DETAILED DESCRIPTION
[0038] Reference signs used in the drawings and claims are for descriptive purposes and shall not be construed as limiting features of the corresponding claims.
[0039] Figure 1 A rotating electrical machine 1 is shown. The electrical machine 1 is connected to an operating voltage and is in operation. The electrical machine 1 is designed as an asynchronous electrical machine, for example an asynchronous machine, and has a rotor 10 rotatable about an axis of rotation 11 and a stator 12 surrounding the rotor 10, wherein a gap 13, which is particularly designed as an air gap, is located between the rotor 10 and the stator 12. The axis of rotation 11 defines an axial direction and a radial direction. The rotor 10 comprises a shaft 100 and a rotor lamination stack 101. The stator 12 comprises a stator lamination stack 120 having a stator winding 121, wherein the stator lamination stack 120 is composed of a plurality of laminated electrical sheets. The stator winding 121 extends axially through the stator lamination stack 120 and forms a winding head 122 at an axial end of the stator lamination stack 120. The shaft 100 of the rotor 10 is supported by a bearing 14. The rotor 10 and the stator 12 are accommodated in a closed electrical machine housing 15.
[0040] Figure 1 Also shown is a system 2 for monitoring a rotating electrical machine 1 during operation of the rotating electrical machine 1 .
[0041] The system 2 includes a sensor device 3 (detector) and a computing system 4, 5, 6, 7. The computing device 4, 5, 6, 7 may generally include hardware and / or software components. For example, it may include a first hardware component 4 and a second hardware component 5, a display device 6, and a cloud computing unit 7.
[0042] The hardware components (computing units) 4, 5; the display device 6 and the cloud computing unit 7 can all be structurally separated from each other. The sensor device 3, the first hardware component 4 and the second hardware component 5 can have a (e.g. bidirectional, preferably wireless) data connection to the cloud (e.g. to the cloud computing unit 7). The second hardware component 5 can, for example, take the form of a mobile device, such as a handheld device, such as a smartphone or a tablet computer. The display device 6 can include, for example, a dashboard. The first computing unit 4 can be arranged in the sensor device 3. The sensor device 3 and / or the first hardware component 4 can be connected to the second hardware component 5 via a (e.g. bidirectional) wireless connection for bidirectional data transmission.
[0043] In one embodiment, system 2 may be an Industrial Internet of Things (IIoT) enabled system.
[0044] The detector 3 is attached to the motor housing 15 and is generally smaller in size than the motor 1 (see Figure 1 ). The motor 1 may be designed as an asynchronous motor with fin-type heat dissipation, and the detector 3 may be attached to the heat dissipation fin of the asynchronous motor.
[0045] The detector 3 is designed to detect stray magnetic fields outside the electric machine 1. To this end, the detector may comprise a magnetic field detector.
[0046] In one embodiment, the detector 3 may be designed to detect mechanical vibrations of the motor 1. To this end, the detector may comprise an acceleration detector (not shown).
[0047] The computing system 4, 5, 6, 7 determines operating point data of the electric machine 1 during its operation. The calculation is based on the detected stray magnetic field and an electrical model 8 of the electric machine 1. The electrical model 8 may be stored on at least one of the computing units 4, 5, 7 of the computing system.
[0048] The operating point data may include, but is not limited to, speed, torque (load), current, loss, etc.
[0049] In one embodiment, at least one of the computing units 4, 5, and 7 of the computing system calculates the stator frequency (i.e., the frequency of the current in the stator winding 121) and the frequency of the current in the rotor winding 101 according to the detected stray magnetic field (including multiple frequencies). These two frequencies are used to calculate the speed, slip rate, etc. of the motor 1.
[0050] In one embodiment, at least one of the computing units 4, 5, 7 of the computing system calculates the rotational speed based on the detected mechanical vibrations of the motor. A frequency analysis is also performed here to "extract" the desired frequency from the spectrum of the mechanical vibrations.
[0051] In one embodiment, at least one of the computing units 4, 5, 7 of the computing system uses the electrical model 8 and the operating point data to calculate the mechanical output power and power loss of the motor 1, and determines the efficiency of the motor 1 based on the mechanical output power and power loss.
[0052] The power loss may be, but is not limited to, at least one of rotor winding loss, stator winding loss, core loss, and additional loss.
[0053] In order to calculate the mechanical output power and power loss, at least one of the calculation units 4, 5, 7 solves the electrical model 8 based on the operating point data (voltage, speed, etc.). The electrical model 8 may include or may be designed as an extended equivalent circuit, which includes the parameters R add To take into account the additional losses (see Figure 2 ).like Figure 2 As shown, by including a resistor R in the circuit 8 add To solve the additional loss.
[0054] Therefore, the extended equivalent circuit 8 is determined by the following motor-specific parameters: main inductance X h (main flux), stator leakage inductance X1 and rotor leakage inductance X'2 (leakage flux), rotor resistance R'2 (for rotor winding loss), stator resistance R1 (for stator winding loss), R fe (for core losses) and R add (for additional losses) (see Figure 2 ). Additional resistance R add Located in the rotor branch of the extended equivalent circuit (at R fe and R'2).
[0055] In one embodiment, the parameters of the extended equivalent circuit 8 are determined by using nameplate information of the motor 1 , such as the number of pole pairs and / or the dimensions of the motor 1 (eg, the height of its shaft 100 ).
[0056] At this point it should be stressed that the detector 3 does not need to be directly connected to any motor sensor inside (or even outside) the motor 1 , for example by wires.
[0057] For example, the electrical model 8 can be downloaded from the cloud, for example from the cloud computing unit 7 or from the cloud database 9 , by means of the second computing unit 5 and transferred to the first computing unit 4 .
[0058] In one embodiment, the electrical model 8 may be used for calculation in the cloud, ie, by the cloud computing unit 7 .
[0059] In one embodiment, at least one of the computing units 4, 5, 7 of the computing system calculates the energy consumption (W) of the motor 1 based on the mechanical output power and energy efficiency of the motor 1 within a determined time interval. el ). This can be done by calculating the electrical input power The electrical input power is then integrated over a predetermined time interval to achieve
[0060]
[0061] In one embodiment, the display device 6 visualizes the energy efficiency of the electric machine 1 as a function of time. The display device 6 may include a web service for remotely displaying the energy efficiency. Figure 1 A display device 6 located in the cloud is shown. However, a person skilled in the art will appreciate that the display device 6 may be part of a computer unit, such as part of the second computer unit 5, part of the cloud computer unit 7 or part of the first computer unit 4. Such visualization of the energy efficiency of the motor 1 during its operation provides a permanent guide for the motor operator, so that she / he can immediately make changes to the operating state of the motor during the operation of the motor (sometimes months or even years) to increase the operating efficiency of the motor, for example, changing the voltage / flux (of the inverter), the load (e.g., reducing the load if the motor is running under overload, or increasing the load if the motor is running under underload), etc., or replacing it with a more efficient motor.
[0062] To facilitate guidance, in one embodiment, at least one of the computing units 4, 5, 7 or the display device 6 of the computing system notifies that a predetermined threshold of energy efficiency has not been reached. The notification can be in the form of a message (e.g., an email), or an auditory or visual signal. Those skilled in the art will appreciate that the form of the notification can be adapted to the needs and / or preferences of the operator. For example, at least one of the computing units 4, 5, 7 can be notified by using the display device 6 for notification.
[0063] In one embodiment, at least one of the computing units 4, 5, 7 of the computing system uses a reference electrical model of some specified reference motors and operating point data of the (original) motor 1 to determine the mechanical output power and power loss of the specified reference motor, determines a reference efficiency of the reference motor based on its mechanical output power and its power loss, and compares the reference efficiency with the efficiency of the (original) motor 1.
[0064] In this way, the efficiency of an electric machine 1 which is currently operated together with some other reference electric machines which are preferably available on the market can be analyzed.
[0065] In order to improve the efficiency of the system in which the motor 1 operates, in one embodiment at least one of the computing units 4, 5, 7 or the display device 6 of the computing system, for example, regularly suggests how to optimize the energy consumption, for example, if the above-mentioned comparison shows that the reference motor is more efficient than the original motor 1, then by adjusting the operating parameters of the motor 1 or by using a reference motor.
[0066] In order to further improve the guidance, in one embodiment, at least one of the computing units 4, 5, 7 of the computing system calculates a reference energy consumption of the reference motor and an energy consumption of the (original) motor 1 within a predetermined time interval, and compares the reference energy consumption of the reference motor with the energy consumption of the (original) motor 1. In this way, only two figures need to be notified to the operator. If the reference motor is more energy-efficient than the original motor 1, a specified notification can be issued, for example, suggesting that the operating state of the original motor 1 should be optimized or that the original motor should be replaced by a more efficient motor.
[0067] Those skilled in the art will appreciate that the above comparison of the original motor 1 with a specified reference motor is also valid in the context of predicting future energy consumption.
[0068] In practice, the determined / collected operating point data of the (original) motor 1 usually contain information about the load (torque) under which the motor 1 has been operating. If the load is not determined, it must be possible to determine the load based on other physical quantities contained in the operating point data of the (original) motor 1. Otherwise, the operating point is not determined. Assuming that the future load of the original motor 1 remains essentially unchanged (i.e. exhibits a comparable load curve), for example, a prediction of the energy consumption of the original machine 1 can be made. In addition, an energy consumption prediction of a reference motor can also be calculated, since its reference electrical model is available. By visualizing this comparison and (continuously) informing the operator of the predicted energy consumption savings, not only guidance can be improved, but also the energy efficiency of the system in which the motor is operating can be increased.
[0069] In other words, by using the torque / speed data of the monitored motor 1, it is possible to derive an indication of the energy efficiency not only of this specific motor, but also of a possible replacement (reference) motor (e.g. an IE4 motor instead of an IE2 motor), by using an electrical model of the replacement motor and pretending to operate it under exactly the same conditions (voltage, frequency, torque) that apply to the original machine 1. This allows for reliable ROI statements, supporting retrofit operations, as well as the European Commission's decarbonization targets.
[0070] Figure 3 An embodiment of the method discussed above is shown. Steps S100 to S140 only involve running the (original) electric machine 1 .
[0071] In one embodiment, in S100 , the time series of the stator (ie, the current frequency in the stator winding 121 ) and the slip frequency of the original running motor 1 are determined based on the detected stray magnetic field.
[0072] In one embodiment, in S101 , an electrical model 8 of the operating motor 1 is provided, for example, downloaded from the cloud, uploaded to the cloud, or determined based on nameplate parameters.
[0073] In one embodiment, in S110 , operating point data for operating the electric machine 1 is determined based on the time series and slip frequency of the stator and based on the electrical model 8 .
[0074] In one embodiment, in S120, the mechanical power p of the original running motor is determined. mech , power loss, and efficiency (as a time series of values).
[0075] In one embodiment, in S130 , the efficiency of the original machine is visualized as a function of time.
[0076] In one embodiment, in S140, by inputting the electrical power p el (Based on mechanical power and efficiency The energy consumption of running the motor 1 is determined by integrating the energy consumption (calculated over time).
[0077] In one embodiment, in S200 , a reference electrical model of a reference machine is provided.
[0078] In one embodiment, in S210 , the mechanical power, power loss and reference efficiency (as a time series of values) of the reference machine are determined based on the reference electrical model and the operating data of the original machine 1 .
[0079] In one embodiment, in S220 , the efficiency of the reference machine is visualized as a function of time.
[0080] In one embodiment, in S221 , the efficiencies of the operating motor 1 and the reference machine are compared and visualized on the same graph at the same time, for example.
[0081] In one embodiment, in S230, by inputting the electrical power p el The energy consumption of the reference machine is determined by integrating over time.
[0082] In one embodiment, in S150 , the energy consumption of the original machine is compared with the energy consumption of the reference machine, and the energy saving potential is visualized.
[0083] Those skilled in the art will appreciate that the above may be applied to the generator mode of the motor.
[0084] The above embodiments of the present disclosure are presented for the purpose of illustration rather than limitation. In particular, the embodiments described with reference to the accompanying drawings are only a few examples of the embodiments described in the introduction. The technical features described with respect to the system can be applied to enhance the method disclosed herein, and vice versa.
Claims
1. A method for monitoring an electric motor (1) during operation of the electric motor, the method comprising: - detecting the stray magnetic field of the electric machine (1) in a detector (3), - based on the detected stray magnetic field and the electrical model (8) of the motor (1), (S110) determining the operating point data of the motor (1), - using the electrical model (8) and the operating point data to determine the mechanical output power and power losses of the electrical machine (1), - (S120) determining the efficiency of the electric machine (1) based on the mechanical output power and based on the power loss.
2. The method according to claim 1, further comprising: - (S140) calculating the energy consumption of the motor (1) based on the energy efficiency of the motor (1) for a determined time interval and the mechanical output power.
3. The method according to claim 1 or 2, further comprising: -(S130) Visualizing the energy efficiency of the electric machine (1) as a function of time.
4. The method according to any one of claims 1 to 3, further comprising: If the energy efficiency is below a certain predetermined threshold, a notification is given that the threshold is not reached.
5. The method according to any one of claims 1 to 4, further comprising: - (S200) determining the mechanical output power and power loss of the reference motor using a reference electrical model (8) of the reference motor and the operating point data of the motor (1), - (S210) determining a reference efficiency of the reference motor according to the mechanical output power and according to the power loss, -(S221) Comparing the reference efficiency with the efficiency of the motor (1).
6. The method according to claim 5, further comprising: If the reference motor (1) is more efficient than the motor (1), it is recommended to use another motor (1) with higher efficiency.
7. The method according to claim 5 or 6, further comprising: - (S230) calculating a reference energy consumption of the reference motor and (S140) an energy consumption of the motor (1) for a predetermined time interval, and (S150) comparing the reference energy consumption of the reference motor with the energy consumption of the motor (1).
8. The method according to any one of claims 1 to 7, further comprising: - receiving mechanical vibrations of the electric machine (1) and using the detected mechanical vibrations to determine the operating point data.
9. The method according to any one of claims 1 to 8, wherein: The electrical model is designed as an extended equivalent circuit (8).
10. The method according to claim 9, further comprising: - Determining the parameters of the extended equivalent circuit (8) based on / by using the nameplate data.
11. A system having a detector (3) for detecting a stray magnetic field of an electrical machine (1) and a computing device (4, 5, 6, 7) adapted to carry out a method according to any one of claims 1 to 10.
12. The system according to claim 11, wherein: The system is designed as an IIoT-enabled device.
13. The system according to claim 11 or 12, wherein: The detector (3) comprises a magnetic field detector and an acceleration detector. The magnetic field detector is configured to receive a stray magnetic field of the motor, and the acceleration detector is configured to receive a mechanical vibration of the motor.
14. A computer program comprising instructions for causing a system according to any one of claims 11 to 13 to perform a method according to any one of claims 1 to 10.
15. A computer readable medium having stored thereon the computer program according to claim 14.