WO2019111145A1

WO2019111145A1 - Electronically controlled high efficiency induction motor

Info

Publication number: WO2019111145A1
Application number: PCT/IB2018/059612
Authority: WO
Inventors: Kunjimon THEKKE PEEDIKAYIL
Original assignee: Thekke Peedikayil Kunjimon
Priority date: 2017-12-06
Filing date: 2018-12-04
Publication date: 2019-06-13

Abstract

The present invention provides electronically controlled high efficiency induction motor having low power consumption due to additional winding provided over the normal winding in the stator (1) that develops back emf, by which part of the power requirement is met and an electronic module through which electric power is supplied to the motor. The electronic module is having a micro controller (6) that controls the voltage frequency and the capacitance of the motor from lower to higher limit; a variable frequency drive (7) that stabilize the frequency at a constant limit; relay switch(8) that helps for switching (on/off) the motor and selects the capacitor, from the capacitor bank (13) based on the load of the motor, measured by the Current Transformer coils (10) that transmit to the microcontroller; step down transformer (11) that provides low voltage for the working of the electronic module and integrated Circuit (12).

Description

ELECTRONICALLY CONTROLLED HIGH EFFICIENCY INDUCTION

MOTOR

FIELD OF INVENTION

The present invention relates to a“Electronically controlled high efficiency induction motor” more specifically an induction motor which is provided with an electronic module which has less power consumption compared to the conventional induction motor having the same capacity. It is meant for single phase motor with capacity of 1 to 10 hp.

BACKGROUND OF THE INVENTION

The world is moving towards a sustainable energy, with an emphasis on energy efficiency and energy conservation. Energy has always been a vital resource in the development of any nation. We can no longer support infinitely with the available source of energy as it is getting depleted day by day. Hence all-out effort has to be made to find out renewal source of energy at the same time has to conserve whatever energy is available. Here comes the relevance of the high efficiency induction motors, the most commonly used motors in many applications from industry, agriculture etc. These are also called as Asynchronous Motors, because an induction motor always runs at a speed lower than synchronous speed. Synchronous speed means the speed of the rotating magnetic field in the stator.

There are basically 2 types of induction motor depending upon the type of input supply - (i) Single phase induction motor and (ii) Three phase induction motor out which the present invention is limited to single phase motor. Or they can be divided according to type of rotor - (i) Squirrel cage motor and (ii) Slip ring motor or wound type and our invention is related to squirrel cage motor.

Before going into details of the instant invention an effort is made to go into the working principle of an induction motor. Here the stator winding is fed with an AC supply.

* Alternating flux is produced around the stator winding due to AC supply. This alternating flux revolves with synchronous speed. The revolving flux is called as "Rotating Magnetic Field" (RMF). a The relative speed between stator RMF and rotor conductors causes an induced emf in the rotor conductors, according to the Faraday's law of electromagnetic induction. The rotor conductors are short circuited, and hence rotor current is produced due to induced emf. That is why such motors are called as induction motors. This action is same as that occurs in transformers, hence induction motors can be called as rotating transformers. Now, induced current in rotor will also produce alternating flux around it. This rotor flux lags behind the stator flux. The direction of induced rotor current, according to Leriz s law, is such that it will tend to oppose the cause of its production.

* As the cause of production of rotor current is the relative velocity between rotating stator flux and the rotor, the rotor will tty to catch up with the stator RMF. Thus the rotor rotates in the same direction as that of stator flux to minimize the relative velocity. However, the rotor never succeeds in catching up the synchronous speed. This is the basic working principle of induction motor of either type, single phase or

On a perusal of the prior art patents application/ granted patents and literature, it can be seen that the“Electronically controlled high efficiency induction motor according to our invention is completely different when it comes to consumption of electricity as well the load it can take compared to the prior art induction motors.

In this connection reference is made to some of the prior art Patents/ Patent application in the field of attention.

US6566778B1 discloses Cage-type induction motor for high rotational speeds comprising a rotor 10 has a structure with a rotor core 12 and rotor conductors 14, the rotor core 12 is made of a weakly magnetic substance with a high permeability and a relatively low electrical conductivity, and the rotor conductors 14 are composed of a conducting material with a low permeability and a relatively high electrical conductivity. Also, the rotor core 12 and the rotor conductors 14 are formed into a single body that has an entire-surface with a smooth cylindrical shape. Furthermore, a stator 20 is composed of a plurality of stator sheets 22 laminated in the axial direction and a stator winding 24. Each stator sheet is formed with a closed circular inner ring portion 22 a and an outer ring portion 22 b, with slots 23 that penetrate the sheets between the ring portions, and the stator winding is housed in the slots. US6700270B2 discloses a synchronous induction motor realizing a great reluctance torque by concentrating a magnetomotive force generated by a rotor provided with a permanent magnet having a two-pole structure, and having a high efficiency. The synchronous induction motor has a stator provided with a stator winding, a rotor rotating within the stator, a cage-type secondary electric conductor provided in a peripheral portion of a rotor yoke portion constituting the rotor, and a permanent magnet inserted into the rotor yoke portion and having a two-pole structure, and the magnetomotive force generated by one pole of the rotor is set to a value equal to or less than 10% of a peak value in a predetermined range near an electrical angle of 0 degrees or 180 degrees. US6331760B1 teaches an improved induction motor having at least one capacitive element electrically connected in parallel with and tapped to each phase of a delta- or wye- wound stator winding such that the capacitive elements are alternately charged or discharged during operation, thereby storing energy from and releasing energy to the windings. This alternate energy storage and release assists in controlling the level of magnetic core saturation and increasing motor efficiency under all operating conditions due to reduced hysteresis and eddy current losses. Motor starting or inrush current is also substantially reduced using this arrangement. In one embodiment, variable capacitors and switch elements are used to provide the ability to dynamically“tune” the motor winding for optimal efficiency. US20l20l2674lAldiscloses a low-inductance, high-efficiency induction machine and method of making same. The electric drive system includes an induction machine and a power converter electrically coupled to the induction machine to drive the induction machine. The power converter comprising a plurality of silicon carbide (SiC) switching devices. The electric drive system further includes a controller that is electrically coupled to the power converter and that is programmed to transmit switching signals to the plurality of SiC switching devices at a given switching frequency such that a peak-to-peak current ripple is less than approximately five percent.

US5500581A relates to a high-efficiency power supply control apparatus for variable- speed induction motor. The apparatus for controlling the supply of power to a variable- speed induction motor converts an AC power source voltage to a motor supply voltage at a designated frequency, with the amplitude of the motor supply voltage being controlled in accordance with the motor load such that the degree of slip conforms to a predetermined optimum slip charactistic, whereby high efficiency and stability are maintained over a wide range of load values. The motor supply voltage amplitude is detected to provide an indication of the motor load, an optimum value of an operating parameter of the motor which varies in accordance with degree of slip is derived based on the designated frequency and the detected voltage amplitude, using a predetermined function corresponding to that frequency, and the motor supply voltage amplitude is controlled such as to reduce an amount of difference between the optimum value of the operating parameter and a detected value of that parameter. US6327524B1 discloses a device for high efficiency motor control includes an induction motor and a controller. The induction motor generates a motor torque and has a given rotor resistance and magnetizing inductance at a specific temperature. The controller is coupled to and controls the induction motor. The controller includes control logic operative to maximize the motor torque using a flux current and a torque current. The controller determines the flux current and torque current based upon a requested torque, a requested speed, the magnetizing inductance, the temperature and the rotor resistance.

US4971522A relates a control system for an AC motor driven cyclic load, such as a beam pumping unit, includes a flywheel, transducer, tachometer, outside set point source, controller, and variable frequency power supply. The flywheel is rotatably connected between the motor and the cyclic load for receiving and storing rotational kinetic energy from the motor and the load during portions of a cycle of the cyclic load when there is excess energy and returning the stored rotational kinetic energy to drive the cyclic load during portions of a cycle when there is an energy demand by the cyclic load. The transducer generates a transducer signal which is a function of the cycle speed. The tachometer means generates a tachometer signal which is a function of the speed of rotation of the motor's rotor. The outside set point source generates an outside set point signal representative of a desired set point cycle speed of the cyclic load. The controller receives the transducer signal, the tachometer signal and the outside set point signal and generates a control signal representative of the adjustment to the power supply frequency of the motor needed to achieve the set point cycle speed. The variable frequency power supply receives the control signal and adjusts the frequency of the power supplied to the motor accordingly. US3987324A discloses high efficiency induction motor with multi-cage rotor. Fractional horsepower induction motors having a fixed number of poles (and, accordingly, a single no load synchronous speed) that are particularly adapted for multi-speed operation when driving a fan load by changing the field strength of the main winding. Induction motors of N fundamental poles have squirrel cage rotor having a plurality of interrelated conductor bars and end rings that are arranged so that multiple sets of the rotor bars establish a predetermined number of separately identifiable cage sets such that the fundamental pole structure of the stator field is coupled with the rotor and such that the third harmonic of the stator field is not coupled with the rotor. The rotor slot number and total number of separately identifiable cage sets are selected so that a cage set pattern is provided that has two-thirds of a fundamental pole pitch. In addition, the number of rotor cage end rings at one end times the number of rotor cage end rings at the other end is greater than or equal to the number of different cage types.

US3781616A relates to a control system for dynamically reenergizing a rotating induction motor. A pair of inverters supply power to the windings of the induction motor through an inductive reactor. A tachometer senses the rotational speed of the rotor of the induction motor and applies a signal to a programmed logic circuit for pulse width modulating the power of the inverters over a constant torque range and for step wave shaping the power of the inverters over a constant horsepower range. In the event of an interruption of power, the reapplied power to the induction motor is reduced and the frequency of the reapplied power is readjusted at or near the actual synchronous speed of the induction motor so that little, if any, current surges occur upon reenergizing of the induction motor.

US5294876A relates to a control system for an AC induction motor, comprising a stator, a rotor, at least two stator windings and rotor windings. The control system comprises a first vector rotator for rotating control signals with a first angle (a) for providing output signals connected to frequency inverters for providing drive signals to each stator winding of the motor, said first angle (a) being the time integral of a rotation frequency (w). Moreover, the control system comprises a second vector rotator for counterrotating measured drive voltages and/or currents with a second angle (-a) which is the inverse of said first angle (a). The rotation frequency (w) is controlled in dependence of said counterrotated measured voltages and/or currents essentially for maintaining the amplitude of said magnetizing currents (Im) of each stator winding constant which is a necessary condition for obtaining Natural Field Orientation.

US4806838A relates to an A.C. induction motor energy conserving power control method and apparatus. Electric power consumed by an a.c. induction motor is measured and sensed changes in power factor are used to modulate the combined magnetic flux produced in the motor field by two sets of RUN windings. A main RUN winding set, which normally couples fully with the a.c. power, is engineered to have sufficient ampere- turns to produce just enough magnetic flux to operate the motor with a light load and maintain a moderately high power factor. Motor driven load increases are determined by sensing a corresponding increase in the power factor of the main RUN winding set, whereupon power flow to a secondary RUN winding is proportionately increased. Considerable energy savings occurs when the motor drives a fluctuating load due to reduced magnetic field excitation under all but full load conditions, with the result that energy ordinarily wasted by eddy currents, copper losses, and poor power factor operation is considerably lessened. Other possible losses due to harmonic distortion of the a.c. power waveform brought about by the phase-delayed thyristor control of the second run winding power are mostly swamped out and masked by the parallel, always-on major power draw by the main run winding. A motor speed-sensitive switch or relay may divert current around the thyristor and fully excite the second run winding during motor start-up, thereby producing full available motor torque during start-up while negating any electrical stress on the control thyristor.

Hence, in spite of the availability of a variety of induction motor according to prior art, having varying degrees of efficiency, it can be seen that the novel features of our invention which makes the induction motor according to the instant invention is unique having low power consumption which is unparalleled, mainly due to different type of winding of the stator coupled with an electronic module provided therein. Hence the present inventionstands apart from the prior art system, due to its overall efficiency with respect to power consumption.

SUMMARY

The present invention provides an electronically controlled high efficiency induction motor. One of the main features of the state of the art induction motor is the method of winding the armature of the stator coil which generates back emf and an electronic module connected to motor through which electric power is supplied to the motor. Another feature of the electronic module is its capacity to select the capacitor, from the capacitor bank having capacitors of varying capacitance based on the quantum of load the motor is subjected to, which is reflected in terms of amperage and measured by the CT coils of the electronic module and the relay switch provided therein.

Coming to the winding of the stator, there is provided an additional winding over the normal winding, which develops what is known as back emf (BEMF), by which part of the power requirement is met without drawing power from the electric main line. This is how the induction motor of the present design is more power efficient than the prior art induction motor.

According to the invention the electronically controlled high efficiency induction motor is comprising of a stator for generating a rotating magnetic field; a rotor disposed to rotate relative to the stator and an electronic modulecoupled withthe winding of the stator. Here the stator generates a rotating magnetic field; andthe rotor is disposed to rotate relative to the stator. The stator (1) is having conventional main winding producing rotating magnetic Field and another additional winding for producing the back EMF which in turn is fed back to the main winding through the electronic module.

According to one aspect of the invention the electronic module attached to the induction motor enables the selection of the capacitor, by means of relay switch (8), connected to the motor at a given point of time while running the motor based on the torque/load taken by the motor which is measured by the CT coil provided in the electronic module in terms of amperage of the motor and thus stabilize the running of the motor.

According to another aspect of the invention, once the motor is switched on, in the electronic module, the connection is made to capacitor C3 by means of relayl (RL1), the motor starts rotating, as the load increases, relay 2 (RL2) activates capacitor C4, as the load still increases, Relay 3( RL3)activatesthe capacitor C5 and later Relay 4 (RL4) activates capacitor C6.

The electronic module is havingi) a micro controller (6) that controls the voltage frequency and the capacitance of the motor from lower to higher limit, ii) a variable frequency drive (7) that stabilize the frequency at a constant limit; iii) relay switch(8) that helps for switching (on/off) the motor and also controls the capacitor; iv) display (9) that displays the voltage, current and power consumption of the motor; v) current transformer coil (CT- coil) (10) that sense the output current and transmit to the microcontroller; vi) step transformer (11) that provides low voltage for the working of the electronic module; vii) Integrated Circuit (12) that receives the output of the micro controller and converts the output signal into analog signal and given to the input of the relay switch(8) and capacitor bank (13) that stabilize the motor input and the power factor (pf) while the motor is running on load.

According to yet another aspect of the invention, during the rotation in every segment of one full rotation, produces the back emf and simultaneously said back emf produced during the rotation of the specific segment is used in rotating the rotor in the succeeding segment and this cycle is repeated in all the segment and as such alternate segment produces the back emf which in turn is used in the rotation during the next segment.

According to another aspect of the invention, the CT Coil provided in the electronic module measures the current consumption and passes to pre programed microcontroller (6), which in turn actuates the relay (9), so as to select and connect the specific capacitor from the capacitor bank (13) having different rating to suit the torque requirement.

BRIEF DESCRIPTION OF THE DRAWING

These and other features, aspects and advantages of the present invention will become better understood when the detailed description is read with reference to the accompanying drawings.

Fig.1. View of the induction motors showing stator

Fig.2Another view of the induction motorshowing rotor

Fig.3 Induction coil showing the winding of the stator.

Fig.4 Shows the shortening of the induction coil between S2, H2 and J2 as shown in Fig.4

Fig.5 Shows the shortening of the inducti on coil between SS1, FIH1 and JJ 1

shown in Fig.5.

Fig.6depicts how back emf is developed during the single rotation of the rotor

Fig.7 Shows electronic circuitry of the Electronic module attached to the induction motor. Wherein 1- Stator; 2-Rotor ; 3- Frame/yoke; 4- Shafts and bearing; 5- Fan; 6- Micro controller; 7- Variable frequency drive; 8- Relay; 9- Display; 10- Current Transformer coil; 11- Step downtransformer; l2-Integrated Circuit; and 13- Capacitor bank.

DETAILED DESCRIPTION OF THE INVENTION

An electronically controlled high efficiency induction motor according to the inventionis a self-contained system wherein the electric power required for running the motor is partly being generated by the motor itself due to the unique method of winding of the stator. Similarly, the electronic module attached to the induction motor enables the selection of the capacitors, by means of relay switch, connected to the motor at a given point of time while running the motor based on the torque/ load taken by the motor which is measured by the CT coil provided in the electronic module in terms of amperage of the motor.

Now the invention is being explained in detail. Like all the conventional induction motor and has basically two parts - Stator and Rotor. The Fig.1 and Fig.2 shows rotor and displays a stator of motor respectively. The stator of an AC induction motor's magnetic structure, which does not rotate. It usually contains the primary winding. The stator is made up of laminations with a large hole in the center in which the rotor can turn. The stack of lamination is secured by end screws. There are slots in the stator in which the windings for the coils are inserted. The Stator is made up of a number of stampings with slots to carry windings. The windings are geometrically spaced 120 degrees apart. The stator (1) rabbets and bore are machined carefully to ensure uniformity of air gap.

The stator (1) is installed with specially tailor- made stator winding, to meet our requirement of the high efficiency induction motor as shown in Fig 1 and Fig.2.It carries two windings one is main winding for producing rotating magnetic Field and another one is for producing the back EMF.This back EMF is given to the electronic module. The electronic module controls the output of the motor and this voltage is given back to the stator winding. The winding is wound for a definite number of poles and the exact number of pole being determined by the requirement of speed. The greater the number of pole, lesser the speed and vice versa as per the general concept. Synchronize Speed directly proportional to frequency and inversely proportional to number of pols. Ns = l20f/P wherein Ns is the synchronous speed and f is the frequency P is equal to number of poles. The rotor (2) used here is squirrel cage type. In squirrel cage type rotor, copper bars or Aluminium bars are placed parallel or approximately parallel to the shaft and close to the rotor surface. The conductors are not insulated from the core, since the rotor currents naturally flow the path of least resistance. At both ends of the rotor, the rotor conductors are short-circuited by the continuous end rings of similar materials to that of the rotor conductors. The rotor conductors and their end rings form a complete closed circuit itself. Carbon brushes are also provided like any conventional induction motor. The frame / yoke (3) is made of close grained alloy cast iron or Aluminium alloy.

Shafts and bearing (4) used here are like any other conventional induction motor. Ball bearing of suitable size is used to reduce rotational friction and support radial and axial loads. Fan (5) is provided to help for adequate circulation of air to cool the windings and it is securely keyed into the rotor shaft.The bearing is housed in the end plates and they are fixed to the frame/ yoke.

According to our invention, the rotor used is the conventional one. But there is design modification with respect stator winding. The specialty of the winding design in the stator is the additional overlapping parallel winding over the normal winding, which develops what is known as back emf (BEMF). Referring to the Figure.3 which depicts the windings of the stator, the details of windings is as under.

Jl and J2 refers to two end of the first motor winding coil over which an additional winding is made to produce back emf, the ends of the additional coil is indicated by JJ1 and JJ2.

Similarly, Hl and H2 refers to two end of the motor winding coil over which an additional winding is made to produce back emf, the ends of the additional coil is HH1 and HH2.

In the same way,Sl and S2 refers to two end of the motor coil over which an additional winding is made to produce back emf, the ends of the additional coil is SS1 and SS2.

The winding connection inside the Motor is as under according to the present invention.

Jl is connected to Motor

Hl is connected to motor

Sl is connected to Motor Shorting is done between S2,H2 and J2 as shown in Fig.4

Shorting is done between SS1, HH1 and JJ1 as shown in Fig.5

The Fig.4and Fig.5 show the shorting for connecting the winding prior to connecting the board. The other end of the main winding which is not shorted as well that of the additional windings which is also not shorted are connected to the electronic module.

Electronic moduleis one of the most important part of the motor which does the control functionality of the motor. The main components of the electronic module are as under:

Micro controller (6) controls the voltage frequency and the capacitance of the motor from lower to higher limit.

Variable Frequency Drive (7)varies and stabilize the frequency at a constant limit. It is controlled by the micro controller.

Relayswitch (8) provided in the electronic module helps for switching (ON/OFF) the motor and also controls the capacitor. Display (9) provided therein shows the voltage, current while running the motor and power used in the circuit.

Current Transformer Coil (CT coil) (10) of the electronic module controls the output current and stabilize the current.

A stepdown transformer (11) is provided to give low voltage for the working of the electronic module.

An IC (12) is provided therein to which the output of the micro controller is given (eg IC TLO 2001). It converts the output signal into analog signal and it is given to the input of the relay.

8-capacitor bank (l3)stabilize the motor input and the power factor (PF) of the line. While the motor is running on the load, based on load the electronic module selects the required capacitance from the capacitor bank.

Stator winding connection with the electronic module is as under: Power input is first given to the Electronic module

1. The entry of the Electricity input (phase) is to the capacitor bank of the board.

2. From capacitor bank the connection goes to Sl and SS2 of the Motor.

3. The entry of the Electricity input (Neutral) goes to the board as well as to H1-HH2 of the motor

4. The Control relay of the board is connected to Jl- JJ2

How the induction motor works according to the instantinvention is briefly explained below.

It works similar to any other induction motor, but is more energy efficient. As a general rule, conversion of electrical power into mechanical power take place in the rotating part of electric motor.

In DC motor, the electrical power is conducted directly to the armature (rotating part) through brushes and commutator. In this sense a dc motor can be called as a conduction motor. However, in AC motor the, rotor does not receive electric power by conduction but by induction in exactly the same way as the secondary of 2 winding transformer receives its secondary power from the primary. That is why such motor are known as induction motor. In fact an induction motor can be treated as rotating transformer.

One of the main feature of the induction motor is the method of winding the armature of the stator coil, which generates back emf and an electronics module connected to motor through which electric power is supplied to the motor.Another feature of the electronics module is its capacity to select the capacitor, from the capacitor bank having capacitors of varying capacitance based on the quantum of load the motor is subjected to, which is reflected in terms of amperage and measure by the CT coil of the electronics module and the relay switch provided therein. An electronically controlled high efficiency induction motor according to the invention is a self-contained system wherein the electric power required for running the motor is partly being generated by the motor itself due to the unique method of winding of the stator. Similarly, the electronic module attached to the induction motor enable the selection of the capacitor, by means of relay switch, connected to the motor at a given point of time while mnning the motor based on the torque/load taken by the motor which is measured by the CT coil provided in the electronic module in terms of amperage of the motor.

Once we switch on the motor, in the electronic module, the connection is made to capacitor C3 by means of relayl (RL1) and the motor starts rotating. As the load increases, the relay 2 (RL2) will activate capacitor C4. As the load still increases, Relay 3(RL3) will activate capacitor C5 and later Relay 4 (RL4) will activate capacitor C6.

Assume hypothetically that one rotation is divided into 4 equal segments/ sectors as shown in the Figure 6 which represents one full rotation of the motor. In the first segment connection is in between SS2 and Sl while the rotor startsmoving. It draws power from the main and simultaneously produces back emf shown as BEMF in the figure 6 which is used in rotating the rotor in the second segment and as such no power is consumed from the main during the rotation in the second segment. Similarly, while the rotor moves in the third segment, the connection is made between Jl and JJ2. Here it draws current from the main line and at the same time produces back emfshown as BEMF in the figure 6, which is used to move the rotor in the fourth segment. Hence here also power is not required for the movement of the rotor in the fourth segment and similar cycle is repeated throughout the running of the motor. Due to this phenomenon of back emf there is lot of saving in the power consumption.

As mentioned earlier the electronic module helps in selecting the capacitor while running the motor based on load.

To start with, based on the current consumption measured by the CT Coil provided in the electronic module, is passed on to microcontroller (6) which is programed so as to activate the relay based on the load, which in turn actuates the relay so as to select and connect the specific capacitor to suit the torque requirement from a plurality of capacitors having different rating provided therein. For Example, for 1 hp motor the capacitor chosen is 5 to 20pf.

The electronic module displays, current and voltage. It is provided with over load protection, short circuit protection as well as over heat tripping arrangement. Example

The following example shows how the induction motor according to the present invention is superior to that of the conventional induction motor. For the purpose ofcomparison, we have given different loads to the motor viz. lkg, 5kg, 8kg. Example-l (on No load)

Test was carried out to find the power consumption of the ordinary Induction motor as well as that of high efficiency induction motor according to the instant invention. The comparative test results are given in the following Table- 1.

Table- 1

From the above example it can be seen that at no load the amount of power saved is 768.67 wats, which shows how efficient is the induction motor according to the instant invention.

Example 2 (with a load of lkg)

Test was carried out by giving a load by fixing a flywheel having the weight of 1 kg on the shaft motor to find the power consumption of the ordinary Induction motor as well as the induction motor according to the invention.

The comparative test results are given in the following Table-2.

Table-2

From the above example it can be seen that onload the amount of power saved is 79l.2lwats, which shows how efficient is the induction motor according to the instant invention.

Example 3 (with a load of 5 kg) Test was carried out by giving a load by fixing a flywheel having the weight of 5 kg on the shaft motor to find the power consumption of the ordinary Induction motor as well as the induction motor according to the invention.

The comparative test results are given in the following Table-3.

Table-3

From the above example it can be seen that on load the amount of power saved is 904.33wats, which shows how efficient is the induction motor according to the instant invention.

Example 4 (with a load of 8 kg)

Test was carried out by giving a load by fixing a flywheel having the weight of 8 kg on the shaft motor to find the power consumption of the ordinary Induction motor as well as the induction motor according to the invention.

The comparative test results are given in the following Table-4.

Table-4

From the above example it can be seen that on load the amount of power saved is 919.65 wats, which shows how efficient is the induction motor according to the instant invention.

The novel features of the invention have been brought out by explaining some of the preferred embodiments under the invention, enabling those in the art to understand and visualize the present invention. It is also to be understood that the invention is not limited in its application to the details set forth in the above description or as illustrated in the drawings. Although the invention has been described in considerable detail with reference to certain preferred embodiments thereof, various modifications can be made without departing from the spirit and scope of the invention as described herein above and the appended claims.

Claims

I Claim:

1. An electronically controlled high efficiency induction motor comprising a stator for generating a rotating magnetic field; and a rotor disposed to rotate relative to the stator and the winding of the stator coupled with an electronic modulecharacterized in that, a) the stator (1) is provided with conventional main winding producing rotating magnetic Field and another additional winding for producing the back EMF which in turn is fed back to the main winding through the electronic module; and b) the electronic module is provided with i) a micro controller (6) that controls the voltage frequency and selects the capacitance of the motor from lower to higher limit, ii) a variable frequency drive (7) that stabilize the frequency at a constant limit; iii) relay switch (8) that helps for switching (on/off) the motor and also controls the capacitor; iv) display (9) that displays the voltage, current and power consumption of the motor; v) current transformer coil (CT-coil) (10) that sense the output current and transmit to the microcontroller; vi) step downtransformer (11) that provides low voltage for the working of the electronic module; vii) Integrated Circuit (12) that receives the output of the micro controller and converts the output signal into analog signal and give to the input of the relay switch (8) and capacitor bank (13) that stabilize the motor input and the power factor (pf) while the motor is running on load.

2. The electronically controlled high efficiency induction motor as claimed in claim

1, wherein the additional overlapping parallel winding over the normal winding provided in the stator develops what is known as back emf (BEMF).

3. The electronically controlled high efficiency induction motor as claimed in claim 1, wherein

a) in the main winding one end of the each coil (Jl, Ell, and S l) is connected to Motor through the electronic module and the other end (J2,H2 and S2) is short circuited and

b) in the additional one end of each of the coil (JJ2, HFI2,and SS2) is connected to Motor through the electronic module and the other end (JJT,HHl and SS1) is short circuited.

4. The electronically controlled high efficiency induction motor as claimed in claim 1, wherein in the stator winding connection with the electronic module : a) power input is first given to the Electronic module through the capacitor bank; b) from capacitor bank the connection goes to one end of the coil (Sl) of the main winding and one end of the coil (SS2) of the additional winding; c) the entry of the Electricity input (Neutral) goes to the electronic module as well as to one end of the coil (Hl) of the main winding and one end of the coil (HH2) of the additional winding; and d) the Control relay (8 ) of the board is connected to one end of the coil (Jl) of the main winding and one end of the coil (JJ2) of the additional winding.

5. The electronically controlled high efficiency induction motor as claimed in claim 1, wherein variable frequency drive (7) controls the out put of the motor and this voltage is given back to the stator winding of the motor and the winding is wound for a definite number of poles and the exact number of pole being determined by the requirement of speed.

6. The electronically controlled high efficiency induction motor as claimed in claim 1, wherein the electronic module attached to the induction motor enable the selection of the capacitor, by means of relay switch (8), connected to the motor at a given point of time while running the motor based on the torque/load taken by the motor which is measured by the CT coil provided in the electronic module in terms of amperage of the motor and thus stabilize the running of the motor.

7. The electronically controlled high efficiency induction motor as claimed in claim 1, wherein, once the motor is switched on, in the electronic module, the connection is made to capacitor C3 by means of relayl (RL1), the motor starts rotating, as the load increases, relay 2 (RL2) activates capacitor C4, as theload still increases, Relay 3 (RL3)activatesthe capacitor C5 and later Relay 4 (RL4) activates capacitor C6.

8. The electronically controlled high efficiency induction motor as claimed in claim 1, wherein, during the rotation in every segment, back emfis produced and simultaneously said back emf produced during the rotation of the specific segment is used in rotating the rotor in the succeeding segment and this cycle is repeated in all the segment and as such alternate segment produces the back emf which in turn is used in the rotation during the next segment.

9. The electronically controlled high efficiency induction motor as claimed in claim 1, wherein, the CT Coil provided in the electronic module measures the current consumption and passes topre programed microcontroller (6), which in turn actuates the relay switch (8), so as to select and connect the specific capacitor from the capacitor bank (l3)having different rating to suit the torque requirement.

10. The electronically controlled high efficiency induction motor as claimed in claim 1, wherein over load protection, short circuit protection as well as over heat tripping arrangement is provided in the electronic module.