DESC:THREE PHASE INDUCTION MOTOR WITH SUPER PREMIUM EFFICIENCY

Field of the invention:

The present invention relates to three phase induction motor and more particularly to three phase induction motor with super premium efficiency.

Background of the invention:

The growing social awareness of recent years in environmental issues such as global warming, have raised interest in technology which increases the efficiency of electrical equipment and reduces energy consumption. Thus from energy conservation point of view, there is a growing need worldwide to replace industrial equipment with high efficiency motors. Governments and companies across the world are actively seeking solutions to a problem that has the potential to profoundly alter the future of our planet.

The ever increasing cost of fuel and electricity adds to the complexity, and directly affects not only industries but entire economies. Renewable energy is only part of the solution. Electric motors are estimated to consume about 65% of the electrical energy consumed by industry. Moreover, energy costs over the typical life cycle of a motor can be as high as fifteen times the original capital cost of the motor. Energy efficient motors thus offer an opportunity to significantly reduce energy costs and their collateral environmental effects. Increasingly, there is a strong economic-and environmental-case for choosing high efficiency motors over conventional ones. Instead of repairing or rewinding a failed motor, organizations may profitably consider replacing them with energy efficient motors or motor driven systems that can bring about significant reduction in energy consumption. So it is mandatory to everyone to use high efficient equipment.

There are existing method to achieve highest energy efficiency (IE4) such as use of Copper (Cu) rotor, permanent magnet motor and synchronous reluctance motor. However, use of Cu rotor leads to increase in manufacturing time and cost. Some are used permanent magnet a rotor for which only DOL (Direct on Line) starting is possible and at low voltage, starting drive is required. Also, there is dependency on other country for its availability. With the use of synchronous reluctance motor, additional devices like invertors and variable frequency drives (VFD) are required. Also, it needs synchronization with other devices. It has low power factor, humming noise etc.

Accordingly, there exists a need to provide a three phase induction motor with super premium efficiency that overcomes drawbacks of the prior art.

Objects of the invention:

The primary object of the present invention is to achieve super premium efficiency of three phase induction motor.

Another object of the present invention is to reduce energy consumption of the three phase induction motor.

Summary of the invention:

Accordingly, the present invention provides a three phase induction motor with super premium efficiency. The induction motor comprises a shaft, an extension key, a driving-end (DE) end shield, a driving-end (DE) bearing, a terminal box, a terminal box cover, an eye bolt, a stator, a rotor, a non-driving end (NDE) bearing, a non-driving end (NDE) end shield and a fan with a fan cover. The stator is arranged in the motor body and the rotor is arranged inside the stator .The shaft arranged at a center of the rotor and the extension key is configured on the shaft. The DE and NDE bearings are fixed on the shaft. The DE end shield is fixed on the DE bearing and the non-driving end (DE) end shield is fixed on the NDE bearing for protection thereof. The terminal box is arranged on the motor body and operatively connected with the stator. The terminal box cover is provided for covering the terminal box. The eye bolt is arranged on the motor body. The fan along with the fan cover is arranged at the NDE end shield for cooling operation.

The three phase induction motor is made up of aluminum die cast rotor and high grade electrical steel for reducing core losses. The stator rotor slot design is modified to reduce core losses. To reduce stator copper losses, reduced number turns per slot and increased copper wire diameter than the existing IE2 motor. Smaller size cooling fan is used to reduce windage losses. Rotor finish OD is grinded to reduce stray load losses.

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 cross sectional longitudinal view of a three phase induction motor, in accordance with the present invention;

Figure 2 shows schematics of stator rotor slots for the three phase induction motor with high efficiency (IE2), in accordance with a prior art; and

Figure 3 shows schematics of stator rotor slots for the three phase induction motor with super premium efficiency (IE4), in accordance with the present invention.

Detailed description of the embodiments:

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 embodiments.

Accordingly, the present invention provides a three phase induction motor and a method to achieve super premium efficiency (IE4) by changing designs of a stator-rotor thereby reduces the energy consumption.

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

Component No Component name
1 Shaft
2 Extension key
3 Driving-end (DE) end shield
4 Driving-end (DE) bearing
5 Terminal box
6 Terminal box cover
7 Eye bolt
8 Motor body
9 Stator
10 Rotor
11 Non-driving end (NDE) bearing
12 Non-driving end (NDE) end shield
13 Fan
14 Fan cover
100 Three phase induction motor

Referring to figure 1, there is shown a cross sectional longitudinal view of a three phase induction motor (100) with super premium efficiency (IE4) (herein after referred as “the induction motor (100)”), in accordance with the present invention.
The induction motor (100) comprises a shaft (1), an extension key (2), a driving-end (DE) end shield (3), a driving-end (DE) bearing (4), a terminal box (5), a terminal box cover (6), an eye bolt (7), a stator (9), a rotor (10), a non-driving end (NDE) bearing (11), a non-driving end (NDE) end shield (12) and a fan (13) with a fan cover (14).

The stator (9) is arranged in the motor body (8). The rotor (10) is arranged inside the stator (9). The shaft (1) is arranged at a center of the rotor (10). The extension key is configured on the shaft (1). The driving-end (DE) bearing and the non-driving end (NDE) bearings are fixed at a driving-end and a non-driving end of the shaft (1), respectively. The driving-end (DE) end shield (3) is fixed on the DE bearing (4) for protection thereof. The non-driving end (DE) end shield (12) is fixed on the NDE bearing (11) for protection thereof. The terminal box (5) is arranged on the motor body (8) and operatively connected with the stator (8). The terminal box cover (6) is provided for covering the terminal box (5). The eye bolt (7) is arranged on the motor body (8). The fan (13) along with the fan cover (14) is arranged at the non-driving end (NDE) end shield (12) for cooling operation.

Again referring to the Figure 1, in an operation, three phase supply is given to the induction motor (100) to produce constant amplitude rotating magnetic field (RMF) which rotates at synchronous speed with respect to the stator (9). As the rotor (10) is stationary, it cuts the rotating magnetic field and as per Faraday's law of electromagnetic induction an electromotive force is generated in the rotor (10) which produces the current. According to Lenz’s Law, the direction of this current is to oppose the vary cause of its production. The vary cause of its production is the difference in its relative speed i.e. the rotating magnetic field and the stationary rotor (10). So the rotor (10) rotates in the same direction as magnetic field and tries to achieve the same speed. As the field rotates at synchronous speed, the rotor (10) rotates at speed less than synchronous speed.

The three phase induction motor (100) is characterized in a way that the induction motor (100) is made up of aluminum die cast rotor and high grade electrical steel for reducing core losses. Further, input Kw is to be reduced by reducing the losses. In an embodiment of the invention, the higher grade steel is M350 steel.

To reduce core losses, the stator lamination diameter is increased than lamination used for IE2 efficiency and modified / changed stator rotor slot design. The stator rotor core length is increased than IE2 motor. To reduce stator copper losses, number of turns of copper wire per slot is reduced and diameter of the copper wire is increased than the existing IE2 motor. Smaller size cooling fan is used to reduce windage losses. Motor Body is designed to give more cooling effect. Rotor finish outer diameter (OD) is grinded to reduce stray load losses. Thus, the losses such as core loss, stator copper loss, rotor copper loss, friction & windage loss and stray load loss are reduced and motor efficiency is increased.

The following table provides comparison of design details of 100 frame 3.7 Kw 2P motor with High Efficiency (IE2) and Super Premium Efficiency (IE4).

Parameter High Efficiency (IE2) Induction Motor (Prior Art) Super Premium Efficiency (IE4) Induction Motor
Stator Lamination Outer Diameter (OD) (mm) 155 165
Stator Lamination Inner Diameter (ID) (mm) 84 90
Rotor Lamination OD (mm) 84 90
Rotor Lamination ID (mm) 37.7 35.7
Stator / Rotor Core Length (mm) 110 150
No. of Turns 64 55
Wire Size 2 x 0.65 mm 0.75 mm & 0.80 mm
Cooling Fan OD (mm) 154 134.5
Core Loss 150.09 138.88
Stator Copper Loss 257.20 135.66
Rotor Loss 168.30 98.73
Friction and Windage Loss 43.51 21.5
Stray Load Loss 95.90 23.8
Total Losses 715 418.57
Efficiency as per IS 12615 85.5 (-2.2) 89.70 (-1.54)
Achieved Efficiency 84.4 89.7
Temperature Rise (?) 70 34.15

Advantages of the invention:

1. Super premium efficiency of the three phase induction motor (100) is achieved using aluminum die cast rotor and high grade electrical steel which further leads to reduce the energy consumption.
2. Rotor is one of the basic part of induction motor which is made of Aluminium Die Cast in which high grade steel is used. Because of High Grade Steel, core losses are less which helps to improve the motor efficiency.
3. It is easy for rotor manufacturing as regular Aluminium Die Cast Process
4. Manufacturing time is less as compared to copper die cast rotor
5. Overall motor cost is less because of use of Aluminium Die Cast Rotor
6. No need of additional devices like Inverter, VFD etc.
7. No synchronization is required.
8. No humming noise.

The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, and to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omissions and substitutions of equivalents are contemplated as circumstances may suggest or render expedient, but such omissions and substitutions are intended to cover the application or implementation without departing from the scope of the claims of the present invention.
,CLAIMS:We claim:

1. A three phase induction motor (100) with super premium efficiency comprising:
a stator (9) arranged in a motor body (8);
a rotor (10) arranged inside the stator (9);
a shaft (1) arranged at a center of the rotor (10);
an extension key (2) configured on the shaft (1);
a driving-end (DE) bearing (4) and a non-driving end (NDE) bearing (11) fixed on the shaft (1),
a driving-end (DE) end shield (3) fixed on the DE bearing (4) for protection thereof;
a non-driving end (NDE) end shield (12) fixed on the NDE bearing (11) for protection thereof;
a terminal box (5) arranged on the motor body (8) and operatively connected with the stator (8), wherein a terminal box cover (6) is provided for covering the terminal box (5);
an eye bolt (7) arranged on the motor body (8); and
a fan (13) along with a fan cover (14) arranged at the non-driving end (NDE) end shield (12) for cooling operation;
wherein, the three phase induction motor (100) is made up of aluminum die cast rotor and high grade electrical steel for reducing core losses, thereby increasing super premium efficiency.

2. The three phase induction motor (100) as claimed in claim 1, wherein a stator lamination diameter and stator rotor core length are increased to increase the efficiency of the three phase induction motor (100) by reducing core losses.

3. The three phase induction motor (100) as claimed in claim 1, wherein the higher grade steel is M350 steel.

4. The three phase induction motor (100) as claimed in claim 1, wherein number of turns of copper wire per slot is reduced and diameter of the copper wire is increased to reduce stator copper losses.

5. The three phase induction motor (100) as claimed in claim 1, wherein smaller size cooling fan (13) is used to reduce windage losses.

6. The three phase induction motor (100) as claimed in claim 1, wherein a rotor finish outer diameter is grinded to reduce stray load losses.

Dated this 30th day of March 2020

Prafulla Wange
(Agent for Applicant)
(IN/PA-2058)