DESC:METHOD AND APPARATUS FOR ESTIMATING ENERGY CONSERVATION POTENTIAL IN INDUCTION MOTOR DRIVEN SYSTEMS AND MONITORING OPERATING CONDITION THEREOF

Field of the invention

The present invention relates generally to monitoring of electrical equipment and more particularly, to a method and an apparatus for estimating energy conservation potential in induction motor driven systems and monitoring operating condition thereof.

Background of the invention

Induction motor drives are the most widely used prime movers in the industrial sector accounting for 70% of electricity consumption. Many of the operational motors are operating at low energy efficiency and can be replaced with more efficient motors. The decision for replacement depends on the trade-off between benefits of the energy conservation and the extended life against the capital investment. Motor Current Signature Analysis (MCSA) is a condition monitoring technique used to diagnose and predict faults in induction motors.

There are many prior documents disclosing methods to determine electric motor efficiency. For example, US8010318B2 and US7956637B2 disclose methods to determine electric motor efficiency using the equivalent circuit approach. A publication “Current Signature Analysis for Condition Monitoring of Cage Induction Motors” by William Thomson and Ian Culbert discloses a method of electrical motor current signature analysis (MCSA) for fault detection and condition monitoring of induction motors along with examples thereof. Another publication WO2015047121A1 discloses remote condition monitoring of motor-operated systems using MCSA.

Existing methods measure the instantaneous operating efficiency of an induction motor. However, none of the prior art accounts, with certainty, the potential for energy conservation by replacing or upgrading an induction motor with an efficient motor or drive considering the actual operating load on the new motor. Decision for upgrading or replacing an induction motor drive depends among many things on the availability of a suitable efficient motor meeting the operating requirement of the specific application, energy conservation potential, and financial returns on the investment required. As some of the factors on which this decision has to be made are dynamic and change over time, there is a need for continuously monitoring the induction motors from the perspective of energy efficiency.

Further as there are tens of millions of induction motors in operation, there is a need for effectively communicating the operating condition of the motors with decision makers in the industry.

Accordingly, there is a need for a method and an apparatus for monitoring the operating condition of an induction motor, to estimate energy conservation potential automatically thereof, and to communicate it effectively.

Objects of the invention

An object of the present invention is to continuously monitor operating efficiency, instantaneous and average over time of an induction motor driven system.

Another object of the present invention is to estimate the potential for energy conservation in a motor driven system under same operating conditions after replacing the existing motor with an available more efficient motor or drive-motor system.

Yet another object of the present invention is to alert the user about inefficient motors in operation.

Still another object of the present invention is to calculate the energy conserved and benefits accrued after replacement of the existing motor with an efficient one.

Summary of the invention

Accordingly, the present invention provides an apparatus for estimating energy conservation potential in induction motor driven systems and monitoring operating condition thereof. The motor driven system includes an induction motor, a variable frequency drive and a power supply. The apparatus comprises at least one current sensor, at least one potential transformer, an analog to digital converter, an energy meter, an electronic device, a cloud server and a web application. At least one current sensor is operably connected to the induction motor for generating current signals proportional to the input line currents thereof. At least one potential transformer is operably connected to the induction motor for generating voltage signals proportional to the input line voltages thereof. The voltage signal is acquired directly through AC lines connected to the apparatus in case of low tension motor or through the potential transformers in case of high tension motors. The analog to digital converter converts the analog signals received from the current sensor and the potential transformer into digital data. The energy meter acquires the digital signals form the analog to digital converter for further processing and measuring the operating parameters of the induction motor. The operating parameters of the induction motor measured by the energy meter includes input current, voltage, power, power factor, supply frequency and energy consumed.

The electronic device is operably connected to the analog to digital converter and the energy meter. The electronic device includes a processor, a memory unit, a plurality of indicators and a display. The processor is configured to perform a motor current signature analysis for calculating the operating parameters therein, and the efficiency of the induction motor based on the calculated parameters thereof. The processor calculates the operating slip, rotation speed and the torque of the induction motor based on the data received from the analog to digital converter and the energy meter. The memory unit is configured to store the digital signals therein. The plurality of indicators generates a plurality of alerts in case of the abnormalities of the induction motor respective to the low operating efficiency, overload or under load thereof. The plurality of alerts generated is displayed on the display.

The cloud server includes a program module and a database. The program module is configured to shortlist efficient drives available that meets the operating requirements of a particular motor in operation, and calculates the energy conservation potential per month by using more efficient drive and financial returns on the investment for efficient drive. The database includes simulation information about the operating characteristics of available efficient motors and motor-drive systems and data of financial returns on the investment for efficient drive stored therein. The web application is accessed by a user using login credentials on a portable communication device. The web application includes a user interface that allows the user to enter rated parameters of the induction motor such as nameplate power and nameplate RPM as an input on the web application and accordingly the configuration settings are uploaded on the apparatus from the cloud server.

In another aspect, the present invention provides a method for estimating energy conservation potential in induction motor driven systems and monitoring operating condition thereof.

Brief description of the drawings

The objects and advantages of the present invention will become apparent when the disclosure is read in conjunction with the following figures, wherein
Figure 1 shows a block diagram of an apparatus for estimating energy conservation potential in induction motor driven systems and monitoring operating condition thereof, in accordance with the present invention;

Figure 2 shows a flow diagram of a method for estimating energy conservation potential, in accordance with the present invention; and

Figure 3 shows a flow diagram of a method for estimating energy conserved, in accordance with the present invention.

It should be appreciated by those skilled in the art that any block diagrams herein represent conceptual views of illustrative systems embodying the principles of the present invention. Similarly, it will be appreciated that any flowcharts, flow diagrams, and the like represent various processes which may be substantially represented in computer readable medium and so executed by a computer or processor, whether or not such computer or processor is explicitly shown.

Detailed description of the invention

The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiment.

The embodiments herein provide an apparatus and a method for estimating energy conservation potential in induction motor driven systems and monitoring operating condition thereof. The apparatus of the present invention takes three phase current input from current transformers and voltage signals. The electrical signals are analysed using motor current signature analysis.
The systems and methods described herein are explained using examples with specific details for better understanding. However, the disclosed embodiments can be worked on by a person skilled in the art without the use of these specific details.

Throughout this application, with respect to all reasonable derivatives of such terms, and unless otherwise specified (and/or unless the particular context clearly dictates otherwise), each usage of:
“a” or “an” is meant to read as “at least one.”
“the” is meant to be read as “the at least one.”

References in the specification to “one embodiment” or “an embodiment” mean that a particular feature, structure, characteristic, or function described in connection with the embodiment is included in at least one embodiment. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment.

Hereinafter, embodiments will be described in detail. For clarity of the description, known constructions and functions will be omitted.

Parts of the description may be presented in terms of operations performed by at least one electrical / electronic circuit, a computer system, using terms such as data, state, link, fault, packet, and the like, consistent with the manner commonly employed by those skilled in the art to convey the substance of their work to others skilled in the art. As is well understood by those skilled in the art, these quantities take the form of data stored/transferred in the form of non-transitory, computer-readable electrical, magnetic, or optical signals capable of being stored, transferred, combined, and otherwise manipulated through mechanical and electrical components of the computer system; and the term computer system includes general purpose as well as special purpose data processing machines, switches, and the like, that are standalone, adjunct or embedded. For instance, some embodiments may be implemented by a processing system that executes program instructions so as to cause the processing system to perform operations involved in one or more of the methods described herein. The program instructions may be computer-readable code, such as compiled or non-compiled program logic and/or machine code, stored in a data storage that takes the form of a non-transitory computer-readable medium, such as a magnetic, optical, and/or flash data storage medium. Moreover, such processing system and/or data storage may be implemented using a single computer system or may be distributed across multiple computer systems (e.g., servers) that are communicatively linked through a network to allow the computer systems to operate in a coordinated manner.

The present invention provides an apparatus and a method for estimating energy conservation potential in induction motor driven systems and monitoring operating condition thereof. The apparatus automatically measures the conserved energy and the benefits accrued by the replacement of the existing induction motor with a new efficient motor. The energy conservation potential is estimated by continuously simulating operation of the most efficient available induction motor under same operating conditions and taking the difference between actual input power and power required for the simulated motor.

The present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate the corresponding parts in the various figures. These reference numbers are shown in the bracket in the following description.

Referring to figure 1, an apparatus (100) for estimating energy conservation potential in induction motor driven systems (150) and monitoring operating condition thereof in accordance with the present invention is shown. The motor driven system (150) comprises an induction motor (110), a variable frequency drive (120) (hereinafter, “VFD (120)”) and a power supply (130). The induction motor (110) is powered by the power supply (130). In an embodiment, the power supply (130) is a three phase AC power supply. In another embodiment, the induction motor (110) is powered by the VFD (120). The VFD (120) energizes the induction motor (110) at specific frequency other than the frequency of the power supply (130). The VFD (120) includes a communication module (not shown). However, it is understood here that the induction motor (110) may be directly driven by the power supply (130) without using the VFD (120).

As shown in figure 1, the apparatus (100) comprises at least one current sensor (10), at least one potential transformer (20), an analog to digital converter (30), an energy meter (40), an electronic device (50), a cloud server (60) and a web application (70).

The current sensor (10) is operably connected to the induction motor (110) and generates current signals proportional to the input line currents of the induction motor (110). The potential transformer (20) is operably connected to the induction motor (110) and generates voltage signals proportional to the input line voltages of the induction motor (110). In an embodiment, the voltage signal is either acquired directly through AC lines connected to the apparatus (100) in case of low tension (LT) motor or through the potential transformers (30) in case of high tension (HT) motors. In the context of the present invention, 3 current sensors and 3 potential transformers are required. However, it is understood here that the number of current sensors (10) and potential transformers (20) required may vary in other alternative embodiments of the present invention as per the intended application.

The analog to digital converter (30) converts the analog signals received from the current sensor (10) and the potential transformer (20) into digital data. The energy meter (40) acquires the digital signals form the analog to digital converter (30) for further processing. The energy meter (40) measures the operating parameters of the induction motor (110) including, but are not limiting to, input current, voltage, power, power factor, supply frequency and energy consumed.
The electronic device (50) is operably connected to the analog to digital converter (30) and the energy meter (40). The electronic device (50) includes a processor (42), a memory unit (44), a display/monitor (46) and a plurality of indicators (48). In an embodiment, the processor (42) receives digital data from the analog to digital converter (30) and the energy meter (40) as well as operating parameters directly from the VFD (120). These digital signals are stored in the memory unit (46). Based on the data received from the analog to digital converter (30) and the energy meter (40), the processor (42) calculates the operating slip, rotation speed and the torque of the induction motor (110). In an embodiment, the processor (42) is configured to perform the Motor Current Signature Analysis (MCSA) for calculating the operating parameters therein. The processor (42) further calculates the efficiency of the induction motor (110) based on the calculated parameters thereof. In another embodiment, this data processing takes place on the cloud server (60). The operating data and the calculated efficiency are continuously uploaded to the cloud server (60) through an internet. The electronic device (50) is connected with the internet through WiFi, GSM network, LAN, or Bluetooth. Alternatively, the electronic device (50) can be pre-configured to connect with the internet or a user can enter a network configuration via another device, e.g. mobile phone, over wireless connection like Bluetooth.

The plurality of indicators (48) generates a plurality of alerts in case of the abnormalities of the induction motor (110) respective to the low operating efficiency, overload or under load thereof. The plurality of alerts generated is displayed on the display (46). In an embodiment, the plurality of indicators (48) is light indicators that generate different lights for indicating different operating conditions for example, green light indicates efficient operation, orange light indicates slightly inefficient operation and red light indicates gross inefficiency.

The cloud server (60) includes a program module (52) and a database (54). The program module (52) is configured to shortlist efficient drives available that meets the operating requirements of a particular motor in operation, calculate the energy conservation potential per month by using more efficient drive and financial returns on the investment for efficient drive. The database (54) includes simulation information about the operating characteristics of available efficient motors and motor-drive systems and data of financial returns on the investment for efficient drive stored therein. According to the simulated data, the power requirements and the energy consumed by various efficient motors are estimated for delivering the required output torque and rotational speed. The cloud server (60) also estimates the potential of the energy conservation with various available options. When the existing motor is replaced by the efficient induction motor (110), the operation of the existing motor is simulated on the cloud server (60) and the energy conserved by the replacement is calculated continuously. The cloud server (60) then transfers the estimated information to the processor (42) and to the web application (70).

The web application (70) is accessed by a user using login credentials on a portable communication device (not shown). The web application (70) includes a user interface (62). The user interface (62) allows the user to enter rated parameters of the induction motor (110) like nameplate power and nameplate RPM as an input and accordingly the configuration settings are uploaded on the apparatus (100) from the cloud server (60). The apparatus (100) calculates operating parameters such as slip, rotational speed, operating efficiency, percentage loading, average efficiency over the desired period, energy conservation potential in a motor-driven system, energy conserved by replacing an old motor with a new one of the induction motor (110). The web application (70) allows a plurality of users to review all the information using the portable communication devices. The user entered operating parameter is then communicated by the web application (70) to the cloud server (60) that further transfers the parameters to the processor (42).

Now referring to figures 2-3, in another aspect, the present invention provides a method for estimating energy conservation potential in induction motor driven systems and monitoring operating condition thereof. The method is described hereinafter in conjunction with the apparatus (100) of figure 1.

In a first step, the method involves connecting at least one current sensor (10) to the induction motor (110) for measuring current consumed by it and generating current signals proportional to the input line currents thereof. In the next step, the method involves connecting at least one potential transformer (20) to the induction motor (110) for generating voltage signals proportional to the input line voltages thereof. In an embodiment, the voltage signal is either acquired directly through AC lines connected to the apparatus (100) in case of low tension (LT) motor or through the potential transformers (30) in case of high tension (HT) motors. In the context of the present invention, 3 current sensors and 3 potential transformers are required. However, it is understood here that the number of current sensors (10) and potential transformers (20) required may vary in other alternative embodiments of the present invention as per the intended application. For High Tension motors, at least one potential transformer will be installed to measure the voltage. An auxiliary power supply is provided to the apparatus (100) for operation thereof.

In the next step, the method involves accessing the web application (70) by the user using login credentials on the portable communication device. The portable communication device includes, but is not limited to, smartphone, mobile, cell phone, personal digital assistant (PDA), tablet and like devices known in the art. In the next step, the method involves entering the rated parameters of the induction motor (110) by the user as an input in the web application (70).

In the next step, the method involves sending the rated parameters by the web application (70) to the cloud server (60) and accordingly, the configuration settings are uploaded on the apparatus (100) from the cloud server (60).

In the next step, the method involves sending the parameters by the cloud server (60) to the processor (42) of the electronic device (50). In the next step, the method involves acquiring measurements of the operating parameters by the processor (42) from the energy meter (40). In next step, the method involves sampling of current and voltage waveforms for measurement of operating efficiency through at least one current sensor (10) and at least one potential transformer (20).

In next step, the method involves uploading the sampled data uploaded by the processor (42) to the cloud server (60) for further analysis. In the next step, the method involves calculating operating efficiency of the induction motor (110) using sampled data using the established technique of motor current signature analysis by the program module (52). The program module (52) also shortlists efficient drives available that meets the operating requirements of a particular motor in the operation. The program module (52) then calculates the energy conservation potential per month by using more efficient drive and estimates financial returns on the investment for efficient drive.

In the next step, the method involves communicating to the user about energy conservation potential and financial returns on the investment. In one embodiment, energy conservation potential and financial returns on the investment are communicated to the user through the web application (70). In another embodiment, energy conservation potential and financial returns on the investment are communicated to the user through the plurality of alerts generated by the plurality of indicators (48) on the display (46). In an embodiment, the plurality of indicators (48) is light indicators that generate different lights for indicating different operating conditions for example, green light indicates efficient operation, orange light indicates slightly inefficient operation and red light indicates gross inefficiency.

Advantages of the invention
1. The apparatus (100) and method provide information regarding energy efficiency and potential for energy conservation in the induction motor driven system.
2. The apparatus (100) provides alerts to the user regarding inefficient motors operation.

The foregoing objects of the invention are accomplished and the problems and shortcomings associated with prior art techniques and approaches are overcome by the present invention described in the present embodiment. Detailed descriptions of the preferred embodiment are provided herein; however, it is to be understood that the present invention may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and as a representative basis for teaching one skilled in the art to employ the present invention in virtually any appropriately detailed system, structure, or matter. The embodiments of the invention as described above and the methods disclosed herein will suggest further modification and alterations to those skilled in the art. Such further modifications and alterations may be made without departing from the scope of the invention. ,CLAIMS:We claim:

1. An apparatus (100) for estimating energy conservation potential in induction motor driven systems and monitoring operating condition thereof, the motor driven system having an induction motor (110), a variable frequency drive (120) and a power supply (130), the apparatus (100) comprising:
at least one current sensor (10) operably connected to the induction motor (110) for generating current signals proportional to the input line currents thereof;
at least one potential transformer (20) operably connected to the induction motor (110) for generating voltage signals proportional to the input line voltages thereof;
an analog to digital converter (30) for converting the analog signals received from the current sensor (10) and the potential transformer (20) into digital data;
an energy meter (40) for acquiring the digital signals form the analog to digital converter (30) for further processing and measuring the operating parameters of the induction motor (110);
an electronic device (50) operably connected to the analog to digital converter (30) and the energy meter (40), the electronic device (50) having,
a processor (42) configured to perform a motor current signature analysis for calculating the operating parameters therein, and the efficiency of the induction motor (110) based on the calculated parameters thereof,
a memory unit (46) configured to store the digital signals therein, and
a plurality of indicators (48) for generating a plurality of alerts in case of the abnormalities of the induction motor (110) respective to the low operating efficiency, overload or under load thereof, wherein the plurality of alerts generated is displayed on a display (46);
a cloud server (60) having,
a program module (52) configured to shortlist efficient drives available that meets the operating requirements of a particular motor in operation, and calculates the energy conservation potential per month by using more efficient drive and financial returns on the investment for efficient drive, and
a database having simulation information about the operating characteristics of available efficient motors and motor-drive systems and data of financial returns on the investment for efficient drive stored therein; and
a web application (70) having a user interface (62) that allows a user to enter rated parameters of the induction motor (110) as an input, the web application (70) being accessed by the user using login credentials on a portable communication device.

2. The apparatus (100) as claimed in claim 1, wherein the operating parameters of the induction motor (110) measured by the energy meter (40) includes input current, voltage, power, power factor, supply frequency and energy consumed.

3. The apparatus (100) as claimed in claim 1, wherein the processor (42) calculates the operating slip, rotation speed and the torque of the induction motor (110) based on the data received from the analog to digital converter (30) and the energy meter (40).

4. The apparatus (100) as claimed in claim 1, wherein the voltage signal is acquired directly through AC lines connected to the apparatus (100) in case of low tension motor or through the potential transformers (30) in case of high tension motors.

5. The apparatus (100) as claimed in claim 1, wherein the rated parameters of the induction motor (110) entered by the user include nameplate power and nameplate RPM, and accordingly configuration settings are uploaded on the apparatus (100) from the cloud server (60).

6. A method for estimating energy conservation potential in induction motor driven systems and monitoring operating condition thereof, the method comprising the steps of:
connecting at least one current sensor (10) to an induction motor (110) for measuring current consumed by it and generating current signals proportional to the input line currents thereof;
connecting at least one potential transformer (20) to the induction motor (110) for generating voltage signals proportional to the input line voltages thereof;
accessing a web application (70) by a user using login credentials on a portable communication device;
entering rated parameters of the induction motor (110) by the user as an input in the web application (70), wherein the rated parameters includes nameplate power, nameplate RPM;
sending the rated parameters by the web application (70) to a cloud server (60) and accordingly configuration settings being uploaded on an apparatus (100) from the cloud server (60);
sending the parameters by the cloud server (60) to a processor (42) of an electronic device (50), wherein the processor (42) is configured to perform a motor current signature analysis for calculating the operating parameters therein, and the efficiency of the induction motor (110) based on the calculated parameters thereof;
acquiring measurements of the operating parameters by the processor (42) from an energy meter (40);
sampling of current and voltage waveforms for measurement of operating efficiency through at least one current sensor (10) and at least one potential transformer (20);
uploading the sampled data uploaded by the processor (42) to the cloud server (60) for further analysis;
calculating operating efficiency of the induction motor (110) using sampled data using the established technique of the motor current signature analysis by a program module (52) of the cloud server (60); and
communicating to the user about energy conservation potential and financial returns on the investment.

7. The method as claimed in claim 6, wherein the processor (42) calculates the operating slip, rotation speed and the torque of the induction motor (110) based on the data received from an analog to digital converter (30) and an energy meter (40).

8. The method as claimed in claim 6, wherein the program module (52) shortlists efficient drives available that meets the operating requirements of a particular motor in the operation and then calculates the energy conservation potential per month by using more efficient drive and estimates financial returns on the investment for efficient drive.

9. The method as claimed in claim 6, wherein energy conservation potential and financial returns on the investment are communicated to the user through the web application (70).

10. The method as claimed in claim 6, wherein energy conservation potential and financial returns on the investment are communicated to the user through a plurality of alerts generated by a plurality of indicators (48) on a display (46) of the electronic device (50).