FIELD OF THE INVENTION:

The present invention relates to high efficiency and energy conserving systems resembling Permanent Magnet Vector Motors and methods for energy conversion.

DESCRIPTION OF THE PRIOR ART:

The patent application with publication number WO 2009/068888 titled, 'Control Of Electrical Machines' claims an electrical machine system for converting electrical energy into mechanical energy or mechanical energy into electrical energy, the machine comprising of a stator and a rotor, the stator having one or more electrical windings wherein at least one electrical parameter of the windings have a cyclic variation related to rotor position; at least one control device for controlling supply of electrical current to or from the or each said electrical winding, and at least one rotor position sensor means for detecting at least one electrical signal related to the cyclic variation of at least one electrical parameter of the or each said electrical winding wherein at least one said rotor position sensor means comprises the steps of measuring the said electrical signal at least once during any part of an electrical cycle, conversion of the at least one measured electrical signal to a ratiometric quantity representative of an estimate of the rotor position and using the said ratiometric quantity in a calculation to maintain the current passing through the or each said electrical winding in synchronism with rotor rotation.

The patent US 7714529 titled, 'Permanent magnet synchronous motor and controller therefor' claims a permanent magnet synchronous motor having a stator and a rotor, the stator having windings and the rotor comprising a plurality of permanent magnets, and a controller, the controller comprising: two magnetic field sensors, each having a linear response to sensed magnetic field strength, the sensors being spaced by an angle A electrical degrees relative to the rotor, where angle A is greater than 0 degrees and less than 180 degrees or greater than 180 degrees and less than 360 degrees, for sensing the position of the rotor by sensing a magnetic field representative of the fields of the magnets of the rotor; normalizing means for producing first and second signals representing normalized orthogonal components of the outputs of the sensors; and energizing means for producing, from the said orthogonal components, sinusoidal currents for energizing the windings of the stator to drive the rotor, the energizing means including a transformer that transforms the normalized first and second signals into 3-phase synchronous sinusoidal waveforms; wherein the normalizing means produces the first and second signals with a uniform amplitude.

The current invention overcomes the need for rotor position sensor, as the rotor used comprises of a combination of a cage rotor and permanent magnet synchronous rotor. The cage rotor gives starting and accelerating torque to allow the rotor to reach near-synchronous speed and due to synchronising torque developed by permanent magnets rotor pull in to synchronism. While operating at synchronous speed, as the magnetic field is rotating at the same speed as the rotor, the cage rotor has no further effect on the operation of the synchronous motor in steady state operation. During further operation, synchronism is achieved by presence of permanent magnet synchronous rotor.

BACKGROUND OF THE INVENTION:

The fundamental principle of working of electric motors is conversion of electrical energy into mechanical energy by electromagnetic means. This mechanical energy is used for driving pump, fan or blower, compressor, any mechanical system converting rotation to other useful form like conveyor, hoist, crane etc. Electric motors are used at home as well as in industry. It is estimated that motors use about 70% of the total electrical power in industry.

The basic types of electric motors are DC (Direct current) motors and AC (Alternating Current) motors depending on the type of voltage supply they are driven by i.e. constant voltage supply and alternating voltage supply respectively. Apart from source of power they can be classified according to their construction, application or type of motion they give.

The parts of an electric motor are- 'rotor' which is the moving part, 'stator' which is the static part, 'poles' either salient or shaded on which magnetic fields are produced, 'commutator' is a device to reverse the flow of electric current, brushes, axles and coils. Most DC motors require brushes to connect the rotor winding and hence are have low longevity as the brushes wear out. There is excessive maintenance needed combined with high costs and brush wear increases in low pressure environment hence cannot be used say in aircrafts.

AC motors are of two main types induction and synchronous motors. In the first current induced in rotor and air gap rotating field due to current flowing in stator winding produce torque, and in the second magnetic field on the rotor produced by DC current delivered through slip rings or by a permanent magnet and current flowing in stator winding produce torque.

In induction motors rotating magnetic field rotating at synchronous rpm is produced by current flowing in stator winding. Synchronous RPM can be worked out by following formula.

Ns = 120 x f/ p

Where Ns = synchronous speed in rpm

f = frequency of supply in Hz

p = nos. of poles of winding

Speed of induction motor is always less than synchronous rpm as current induced in rotor is proportional to difference between synchronous rpm and actual rotor rpm i.e. slip rpm. Induction motor cannot develop any torque at synchronous rpm as current induced in rotor will be zero. As slip rpm increases, more current induced in rotor and hence increase in torque developed.

In synchronous motors torque is developed only when stator field rotating at synchronous rpm and actual rotor rpm are equal. Thus rotor of synchronous motor always rotates at synchronous rpm. The speed does not change with change in load and supply voltage within allowable limits. Synchronous motors are specifically designed to maintain constant speed with the rotor synchronous to the rotating field. The speed is a fixed multiplication factor of the power supply frequency. The speed does not change with change in load and supply voltage. The speed of available motors can be controlled using close loop control system which controls the speed by regulating power delivered to the motor and it comprises of controller, driver and shaft encoder which gives feedback to the controller. But this adds additional cost and do not ensure perfect constant speed. The power factor of an AC electric power system is defined as the ratio of the real power to the apparent power flowing in the circuit, and is a dimensionless number between 0 and 1. Real power is the capacity of the circuit for performing work and apparent power is the product of the current and voltage of the circuit. Maximum demand is product of voltage and maximum current drawn from the supply system. Poor power factors results in increased current drawn from the supply system for given real power and hence increase in maximum demand. Many electricity companies charge fixed cost based on maximum demand in addition to energy consumed. Thus poor power factor increases energy cost. A high power factor is generally desirable in a transmission system to reduce transmission losses and improve voltage regulation at the load. It is often desirable to adjust the power factor of a system to near 1.0. External capacitors and control equipments are required to improve power factor of induction motors.

The efficiency of a motor can be defined as "the ratio of a motor's power output to total power input." Factors that influence motor efficiency are losses taking place in different parts of motor. Different losses are stator copper losses, stator iron losses, rotor copper losses, friction and windage losses and stray load losses. Efficiency of motor can be improved by reducing above losses. It may require to use better or more active material like copper and stamping steel to reduce above losses and hence to improve efficiency. A higher frame size may be used to counter copper and iron losses by accommodating required active materials to increase efficiency.

Different losses taking place in motor are converted in to heat, which raises temperature of various components. These components are required to be cooled and keep its temperature within allowable limits. Thermal considerations are one of the major limitations to the output obtainable from electrical machines. Cooling air flow is required for removal of generated heat, eliminating hot spots and maximizing the motor's useful life. In standard motors heat generated is conducted to body which is cooled by air blown over the body. Heat conduction to body is poor due to contact resistance between stamping and body. It is desirable to develop advanced thermal design and cooling circuits for electric motors. In induction motors as load increases its rpm reduces so that more current is induced in rotor and hence more torque to meet load demand. In some application where it is required to minimize such speed changes, adjustable speed drives are often required to control the speed thus adding to the cost.

Motors available in the market have poor efficiencies and power factors, resulting in more energy consumption and more energy cost. External capacitors and control equipments are required to improve power factor of induction motors. Adjustable speed drives are often required to control the speed thus adding to the cost.

Permanent magnet motors normally face magnetic locking or 'cogging problem', which refers to rotation occurring in jerks or increments rather than smooth motion. When an armature coil enters the magnetic field produced by the field coils it tends to speed up, and slow down when leaving it. This effect becomes apparent at low speeds. The techniques normally used are; skewing of stator stack, skewing of the magnetic poles, making number of rotor slots prime visa-vis the number of stator slots etc. However, these techniques increase manufacturing cost and have other problems such as stator skewing would lead to reduction of effective slot area and increased stator resistance.

A neodymium magnet (also known as NdFeB or Neo magnet) is a permanent magnet made from an alloy of neodymium, iron, and boron and is the most widely-used type of rare-earth magnet. NdFeB has high coercive force, high energy and high performance : cost ratio.

A Permanent Magnet Synchronous Motor (PMSM) is a 'self-excited' synchronous motor that uses permanent magnets to provide magnetic fluxes, needed to produce torque. PMSMs are generally more compact and are more energy efficient than other motors PMSMs are very popular in a wide array of applications. They don't have a commutator like a DC motor hence are more reliable, they achieve higher efficiency than AC induction motor as they generate magnetic flux with rotor magnets. Therefore, PMSM are used in high-end white goods like refrigerators, washing machines, dishwashers, etc. and in other appliances that require high reliability and efficiency. But the rotor rpm have to be synchronized with the stator current in order to produce the required torque and not to lose synchronization. For this purpose a rotor position sensor is required. The need of a rotor position sensor increases the cost and reduces the reliability. Therefore, it is necessary to develop new control strategies for PMSMs to avoid the use of the rotor position sensor.

OBJECT OF THE INVENTION:

The object of the invention is to make high efficiency and energy conserving systems and methods for energy conversion.

Another object of the invention is to make a system having characteristics including but not limited to; high efficiency, high power factor, low energy cost, a constant rpm for given supply frequency, more compact that is to have a lower frame size and low rotor inertia that is fast response to frequency change.

SUMMARY OF THE INVENTION:

The present invention in a preferred embodiment provides a system for energy conversion with high efficiency, wherein the said system comprises of,

a) a stator comprising of at least one cooling air passage for facilitating heat transfer and at least one winding slot to accommodate a winding with a full pitched coil; b) a rotor comprising of,

- a central rotor shaft,

- at least one slot along the periphery of the rotor for squirrel cage such that the angle between slots is non-uniform in at least one arrangement;

- at least one slot to accommodate at least one magnet; and

c) a 'forced air cooling fan' which forces air through stamping air passages.

In another embodiment of the present invention, a method for energy conversion with high efficiency is used, wherein the method comprising the steps of,

a) arranging a stator (1), a stator winding (2), a rotor (3), a cage (4), a permanent magnets (5), a 'forced air cooling fan' (6), a front end shield with bearing (7) and a rear end shield with bearing (8), the said arrangement being in accordance with the exemplary arrangement as shown in Figure 1 ; b) connecting electric supply to terminals of 'forced air cooling fan' that enables cooling air passage through air passages of stator stampings which shall enable cooling of Stator (1) and stator winding (2);

c) passing electric supply to terminals of Stator winding (2) which will enable creation of rotating magnetic field thereby inducing voltage and electric current in rotor cage (4), which in turn generates starting and accelerating torque, and rotor (3) tends to accelerate near synchronous speed;

d) creating unequal predefined angles between rotor slots which enables prevention of stalling and cogging during accelerating period and also in achieving more space at pole centre and sinusoidally reducing space towards pole ends; and

e) generating running torque due to magnetic field due to permanent magnets (5) and current flowing in stator winding (2).

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:

Figure 1 illustrates an example of a vertical cross-section of the system with stator winding, rotor cage, cooling fan, permanent magnet and rotor.

Figure 2 illustrates an example of a radial cross-section of the stator stamping of the system showing air passages and stator slots.

Figure 3 illustrates an example of a radial cross-section of the rotor stamping of the system showing rotor slot and slot for permanent magnet.

Figure 4 illustrates an example of a radial cross-section of the stator stamping of the system as extended to a permanent magnet submersible motor showing stator slots.

Figure 5 illustrates an example of a radial cross-section of the rotor stamping of the system as extended to a permanent magnet submersible motor showing rotor slot and slot for permanent magnet.

Figure 6 illustrates an example of a radial cross-section of the Stator stamping of the system as extended to a permanent magnet torque motor showing stator slots. Figure 6(A) illustrates an example of a radial cross-section of the rotor stamping of the system as extended to a permanent magnet torque motor showing rotor and permanent magnet slots.

Figure 7 illustrates an example of the outer body, of the system and Figure 7(A) shows the rear side view of the same outer body wherein a fan could be seen mounted at one end of the system.

Figure 8 illustrates an indicative graph of comparative percentage efficiency between standard motor and permanent magnet vector motor over increasing percentage loads.

Figure 9 illustrates an indicative graph of comparative percentage power factor between standard motor and permanent magnet vector motor over increasing percentage loads.

DETAIL DESCRITION OF THE INVENTION:

The present invention in a preferred embodiment provides a system for energy conversion with high efficiency, wherein the said system comprises of,

a) a stator comprising at least one cooling air passage for facilitating heat transfer and at least one winding slot to accommodate a winding with a full pitched coil; b) a rotor comprising of,

- a central rotor shaft;

- at least one slot along the periphery of the rotor for squirrel cage such that the angle between slots is non-uniform in at least one arrangement;

- at least one slot to accommodate at least one magnet; and

c) a 'forced air cooling fan' which forces air through stamping air passages.

In an embodiment of the invention, the system is used as an electric motor to convert electrical energy into mechanical energy. When used as an electric motor, an example of a method of using the system is firstly, coupling the motor to a load using direct coupling, pulley or any other standard arrangements. Then, the winding terminals of the motor are to be connected to suitable supply voltage system and the cooling fan motor terminal is to be connected to suitable supply. The cooling fan motor is to be started first and then the motor is to be started using proper switchgears. The motor will accelerate to synchronous speed as determined by supply voltage frequency, permissible variations in supply voltage and load will not affect speed of the motor and it can be run continuously within permissible loading condition. The system used as a motor may not require rotor position sensors or AC drive for starting and normal operation but for application requiring speed control, AC drive can be used.

In an embodiment of the invention, the system comprises of a rotor constituted by one or more permanent magnets, a stator with wire windings which serves as an electromagnet when current is passed through it, the current may be but is not limited to alternating current. Rotating magnetic field created by current flowing in stator winding induces current in rotor cage which generates starting torque and accelerating torque for accelerating the rotor near to synchronous speed. Synchronising torque generated by flux due to permanent magnet and current flowing in stator winding pulls rotor in to synchronous speed and at synchronous speed there is no current in cage and hence no rotor copper losses, thus giving higher efficiency. 'Copper loss' is a term which is normally used to refer to the energy which is dissipated by the resistance in the wire used to wind a coil in an electrical device such as a transformer, motor or generator. Copper losses occur in electrical devices because of the flow of electrical currents through conductors. Copper losses increase as the value of electrical current passing through the conductors increases. An increase in the electrical resistance of conductors also causes the copper losses to increase. The unequal predefined angles between rotor slots help in preventing stalling and cogging during accelerating period. Moreover flux from permanent magnets passes through space between rotor slots and unequal predefined angle between rotor slots help in achieving more space at pole centre and sinusoidally reducing space towards pole ends.

In an embodiment of the invention, the system can be used as a motor with a 'power factor' nearing 1, and without the use of any external controlling or monitoring or regulating or inspecting or checking equipment or device or tool or machine or mechanism or apparatus or gadget or appliance or contraption including but not limited to external capacitors. Stator winding and size of the permanent magnet are designed so that motor power factor is near to 1. Improvement in power factor reduces current flowing in stator winding which reduces stator copper losses, because of which efficiency increases. The term 'power factor' for the purpose of this invention is the ratio of actual power (watts) to apparent power (volt-amperes). The power factor is 1 when current and voltage are in phase.

In an embodiment of the invention, the system facilitates energy conservation, and may reduce energy related expenses and cost.

In an embodiment of the invention, the system works in synchronism or in tandem with supply frequency and maintains constant or stable speed irrespective of variations or changes in load and supply voltage.

In an embodiment of the invention, the system may or may not require additional equipment or device or tool or machine or mechanism or apparatus or gadget or appliance or contraption like but not limited to close loop speed control system which controls the speed by regulating power delivered to the motor and it comprises of controller, driver and shaft encoder which gives feedback to the controller.

In an embodiment of the invention, the system does not require a rotor position sensor or an AC drive for starting and running operation and it can be started using a suitable AC supply system. A rotor position sensor is a device used to synchronize the rotor with permanent magnets, to stator currents in order to produce the required torque. The current invention overcomes the need for rotor position sensor, as the rotor uses a combination of a cage rotor and permanent magnet synchronous rotor. The cage rotor contains longitudinal conductive bars made of suitable material such as but not limited to aluminum or copper; set into grooves and connected together at both ends by shorting rings forming a cage-like shape. The cage rotor gives starting and accelerating torque to allow the rotor to reach near-synchronous speed and due to synchronising torque developed by permanent magnets, rotor pulls in to synchronism. While operating at synchronous speed, as the magnetic field is rotating at the same speed as the rotor, the cage rotor has no further effect on the operation of the synchronous motor in steady state operation. During further operation, synchronism is achieved by presence of permanent magnet synchronous rotor. In an embodiment of the invention, the system overcomes the requirement of having a higher frame size which is otherwise required by other motors; to improve the efficiency by reducing copper or iron losses.

In an embodiment of the invention, the system is made such that the stator stampings are designed with attributes including but not limited to cooling air passages and laminated body construction with a proper balance between slot area and teeth area thus improving motor life and performance. Copper losses can be reduced by increasing stator slot area to accommodate more copper but increasing stator slot area reduces stator teeth area and increases flux densities in stator teeth and stator yoke which results in increased magnetization current and iron losses. The specific design of the stator stamping of the current invention increases efficiency of the system and the output.

In an embodiment of the invention, the system in accordance with other embodiments and figures, is made such that the number of stator slots is an integer greater than two, which helps in achieving nearly sinusoidal distribution of air gap flux due to current flowing in stator winding, the angles between stator slots are equal, and the stator winding is designed with full pitched coil in place of chorded coils used in standard motors. This improves winding factor and waveform of voltage induced in stator winding due to permanent magnet flux.

In an embodiment of the invention, the system is made with a specially designed rotor with a central shaft, a stamping with attributes including but not limited to a cage slot size, shape and pitch; and V-shaped slots with size and pitch to accommodate magnets ; the angle between rotor slots is non uniform and a proper balance is maintained between cage slots and permanent magnet slots, as allotting less area for permanent magnet slots will result in less flux from magnet and poor performance during synchronous operation, whereas allotting more area for permanent magnet slots will result in poor performance during starting and accelerating. As illustrated in previous embodiments, this distribution of rotor slots help in achieving nearly sinusoidal distribution of flux due to balance of squirrel cage and permanent magnets positioned in rotor stamping, eliminates cogging problem and improves starting torque as compared to uniform distribution followed in standard motors. The stator and rotor stamping designs mentioned in various embodiments of the invention influence the attributes such as but not limited to permanent magnet size, air gap flux distribution, winding copper and iron losses and overall motor performance and efficiency. Stamping includes a variety of sheet-metal forming manufacturing processes and is used to refer to various press forming operations including coining, embossing, blanking and pressing.

In an embodiment of the invention, the system is designed with forced cooling to ensure proper cooling at low speed operation, which can be obtained using AC drive. Cooling air flow enables removal of stator generated heat, eliminates hot spots and maximizes the motor's longevity or durability.

In an embodiment of the invention, the system has 'forced air cooling fan' mounted at non driving side of the motor, which forces air through stamping air passages.

In an embodiment of the invention, the system has a rotor with a low moment of inertia known as 'rotor inertia' and hence gives quick response to any controlled or uncontrolled change in frequency of supply.

In an embodiment of the invention, the system can be coupled to load using direct coupling, pulley or any other standard arrangements.

In an embodiment of the invention, a method for energy conversion with high efficiency is used, wherein the method comprising the steps of,

a) arranging a stator (1), a stator winding (2), a rotor (3), a cage (4), a permanent magnets (5), a 'forced air cooling fan' (6), a front end shield with bearing (7) and a rear end shield with bearing (8), the said arrangement being in accordance with the exemplary arrangement as shown in Figure 1 ;

b) connecting electric supply to terminals of 'forced air cooling fan' that enables cooling air passage through air passages of stator stampings which shall enable cooling of stator (1) and stator winding (2);

c) passing electric supply to terminals of stator winding (2) which will enable creation of rotating magnetic field thereby inducing voltage and electric current in rotor cage (4), which in turn generates starting and accelerating torque, and rotor (3) tends to accelerate near synchronous speed;

d) creating unequal predefined angles between rotor slots which enables prevention of stalling and cogging during accelerating period and also in achieving more space at pole centre and sinusoidally reducing space towards pole ends; and

e) generating running torque due to magnetic field due to permanent magnets (5) and current flowing in stator winding (2).

In an embodiment of the invention, a method for energy conversion with high efficiency is used, wherein the method comprising the steps of,

a) arranging a stator (1), a stator winding (2), a rotor (3), a cage (4), a permanent magnets (5), a 'forced air cooling fan' (6), a front end shield with bearing (7) and a rear end shield with bearing (8), the said arrangement being in accordance with the exemplary arrangement as shown in Figure 1 ;

b) connecting electric supply to terminals of 'forced air cooling fan' that enables cooling air passage through air passages of stator stampings which shall enable cooling of stator (1) and stator winding (2);

c) passing electric supply to terminals of stator winding (2) which will enable creation of rotating magnetic field thereby inducing voltage and electric current in rotor cage (4), which in turn generates starting and accelerating torque, and rotor (3) tends to accelerate near synchronous speed;

d) creating unequal predefined angles between rotor slots which enables prevention of stalling and cogging during accelerating period and also in achieving more space at pole centre and sinusoidally reducing space towards pole ends;

e) generating running torque due to magnetic field due to permanent magnets (5) and current flowing in stator winding (2), whereby rotor will tend to attain synchronous speed;

f) attaining synchronous speed by rotor whereby there shall be no torque developed by rotor cage; and

g) developing torque and rotating the rotor at synchronous speed by flux from permanent magnets (5) and current flowing in stator winding (2) irrespective of voltage and load variation within allowable limits; and h) using the torque and rotation of the rotor in the form of mechanical energy.

The magnet used in various embodiments of the invention may include but is not limited to temporary magnets, permanent magnet, rare earth based magnets, horseshoe magnet, bar magnet, ball-ended magnet, circular magnet, isolating magnets, injection moulded magnet, flexible magnet, neodymium-iron-boron ( dFeB) based magnet, samarium-cobalt based magnet, alnico based magnet, ceramic based magnet or ferrite based magnet, Praseodymium based magnet, Neodymium based magnet, Samarium based magnet, Gadolinium based magnet, Dysprosium based magnet, Samarium- Cobalt based magnet, Neodymium-iron-boron based magnet or their derivatives or alloys or any combination thereof.

In an embodiment of the invention, the machine is suitable to be used with Pulse-width modulation AC drive owing to the winding insulation system used.

In an example in accordance to the invention, having rating of 5.5 KW, 415V, 50 Hz, 4 Pole, with a 100% load, 93% efficiency can be achieved with a current of 8.6 Amp, power factor of 0.962 and RPM of 1500.

In an example in accordance to the invention, having rating of 5.5 KW, 415V, 50 Hz, 4 Pole, with a 75% load, 93% efficiency can be achieved with a current of 6.4 Amp, power factor of 0.958 and RPM of 1500.

In an example in accordance to the invention, having rating of 5.5 KW, 415V, 50 Hz, 4 Pole, with a 50% load, 92.2% efficiency can be achieved with a current of 4.4 Amp, power factor of 0.95 and RPM of 1500.

In an example in accordance to the invention, for 4- pole design motor with 28 rotor slots and 36 stator slots; the angles between stator slots are equal and measure 10°; the non-uniform angles between rotor slots are such that: angles between slot 1 and 2 is 13.1 °, between slot 2 and 3 is 14.3°, between slot 3 and 4 is 14.8°, between slot 4 and 5 is 14.3°, between slots 5 and 6 is 13.1 ° and between slots 6 and 7 is 10.2° and this sequence is repeated over all four sets of 7 rotor slots. This distribution of rotor slots improves starting torque as compared to uniform distribution followed in standard motors.

In an embodiment of the invention, the system can be used with a suitable AC drive as servo motor. A servomotor or a servo is an electromechanical device, with a positional feedback control, in which an electrical input allows the rotor to be positioned accurately.

In accordance with a test conducted for the present invention, the system with specifications- above 5.5 KW, 4 pole, 415V, 50 Hz using TDE MACNO, Italy make AC drive Model OPD-15 and using pulse command for position control gave motor performance with high efficiency.

In accordance with a 'No load test' conducted for the present invention, the system with specifications- above 5.5 KW, 4 pole, 415V, 50 Hz was fed through utility supply and run uncoupled and it was observed that the machine started satisfactorily and accelerated to synchronous speed. The readings taken were: Voltage- 415 V, Current- 2.7 A, Power Input- 190.82 W, Frequency- 49.8 Hz, Speed- 1494 RPM.

In accordance with a 'Locked rotor test' conducted for the present invention, the system with specifications- above 5.5 KW, 4 pole, 415V, 50 Hz was fed to reduced voltage supply through auto transformer with the shaft of the machine locked. The readings noted were: Voltage- 82.93 V, Current- 11.34 A, Power Input- 1094.4 W, Torque- 0.46 Kg-m.

In accordance with a ' Temperature Rise Test' conducted for the present invention, the system with specifications- above 5.5 KW, 4 pole, 415V, 50 Hz was run at rated loading condition till winding temperature stabilized. Temperature rise as measured by resistance method was 41.4 deg. Cent, above ambient temperature of 38 deg. Cent. Temperature rise allowed as per IS 325 for Class-B insulated motor is 80 deg. Cent, above ambient temperature of 40 deg. Cent.

In an embodiment of the invention, the system can be used as drive motor for applications or instruments such as but not limited to, injection molding machines, blow molding machines, textile machines, printing machines, machine tools, packaging machineries, winders and unwinders, testing machines, press feeders, rotary cutters, traverses, planners, handling system, fly sheer, lift and crane, computer numerical control machines, pump, ball mill, rolling mill, conveyor, centrifuge, paper mill machines, pharmaceuticals machines, fans, oven, blender, can opener, refrigerator, mixer, tape player, clocks, washer, dryer, electric screwdriver, vacuum cleaner, electric saw, electric drill, furnace blower, hair dryer, electric razor, electric toothbrush, power windows, windshield wipers, cars, CD player, computers, computer based machines, toys, pumps, lifts, electric trains, turbines, drills, conveyer belts, airplanes, robotics and other applications or functions where standard motors are used and combinations thereof.

In an embodiment of the invention, system and methods of the current invention can be extended to a submersible pump-motor used in wells, bore wells, to achieve better efficiency, constant speed, better output and sizeable saving in energy cost and energy conservation.

In an example in accordance to the invention, the submersible motor has a 2-pole design, a cylindrical shape, circular stator stamping, C-shaped slots for permanent magnet in rotor stamping.

In an embodiment of the invention, system and methods of the current invention can be extended to a torque motor which is a multi-pole motor, to increase efficiency, eliminate speed reducing gearbox and its maintenance and related downtime.

In an example in accordance to the invention, has a 12-pole design and "V" shaped slots to accommodate magnets in the rotor.

In an embodiment of the invention, the term 'forced air cooling fan' apparatus that creates a current of air or any other gas for the purpose of cooling or ventilation

For the purpose of the drawings and figures, N may stand for north pole region of a magnet and S may stand for south pole region of a magnet

Figure 1 illustrates an example of a vertical cross-section of the system with a stator (1), stator winding (2), rotor (3), cage (4), permanent magnet (5), cooling fan (6), front end shield with bearing (7) and rear end shield with bearing (8). An example of radial cross-section of the stator stamping of the system is illustrated in Figure 2 which shows the air passages (9) through which heat generated by stator copper and iron losses is forced out by the forced cooling and stator slots (10) which house the full pitched coil stator windings.

An example of radial cross-section of the rotor is illustrated in Figure 3 which shows unequally spaced rotor slots (11) and a slot (12) of one of the permanent magnets (5). Further, the Figure through the said example also indicates polarities of permanent magnets.

Figure 4 illustrates an example of a radial cross-section of the stator stamping of the system as extended to a permanent magnet submersible motor showing stator slots (10). As submersible motors are used in bore wells the cooling media is water and hence the stamping differs from Figure 2 by absence of air passages.

An example of the radial cross-section of the rotor stamping of the system as extended to a permanent magnet submersible motor is illustrated in figure 5 which shows a slot (12) for permanent magnets (5) and slots for squirrel cage (13). Further, the Figure through the said example also indicates polarities of permanent magnets.

Figure 6 illustrates an example of a radial cross-section of the stator stamping and Figure 6(a) illustrates an example of a radial cross-section of the rotor stamping of the system as extended to a permanent magnet torque motor showing slot(12) for permanent magnet(5) and a slots for squirrel cage and stator slots (10).

Figure 7 illustrates an example of the outer body, of the system and Figure 7(A) shows the rear view of the same outer body wherein a fan could be seen mounted at one end of the system.

Figure 8 illustrates an indicative graph of comparative percentage efficiency between standard motor and permanent magnet vector motor over increasing percentage loads. The percentage efficiency of the current invention is higher than that of standard motor over different percentage loads owing to the factors mentioned in the various embodiments above. This leads to saving energy and the highlighted area in the graph depicts the amount of energy saved.

Figure 9 illustrates an indicative graph of comparative percentage power factor between standard motor and permanent magnet vector motor over increasing percentage loads. The percentage power factor of the current invention is much higher than that of standard motor over different percentage loads. The power factor of the current invention is high owing to specific design of stator and rotor stampings. As the power factor is high, the current drawn from the system for the same real power would be less as compared to standard motor because power factor is the ratio of real power and apparent power and apparent power is the product of voltage and current. As the current drawn from the system is less the maximum demand would be less as it is the product of voltage and maximum current from the supply system. This saving in maximum demand is highlighted in Figure 9. This leads to decrease in energy cost.

In an embodiment of the invention, the components of the present invention may be connected or arranged by using any suitable method and may include without limitation use of one or more of welding; adhesives; riveting; fastening devices such as but not limited to screw, nut, bolt, hook, clamp, clip, buckle, nail, pin, ring or any combination thereof.

It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being "directly connected or coupled" to another element, there are no intervening elements present. Furthermore, "connected" or "coupled" as used herein may include wirelessly connected or coupled or through one or more fastening devices or by any other process or device.

While the present invention is susceptible of embodiment in various forms, there is shown in the drawings and will hereinafter be described a presently preferred embodiment with the understanding that the present disclosure is to be considered an exemplification of the invention and is not intended to limit the invention to the specific embodiments illustrated. The use of "including", "comprising" or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude or rule out the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

The aim of this specification is to describe the invention without limiting the invention to any one embodiment or specific collection of features. A person skilled in the relevant art may realize the variations from the specific embodiments that will nonetheless fall within the scope of the invention, and such variations are deemed to be within the scope of the current invention. It may be appreciated that various other modifications and changes may be made to the embodiment described without departing from the spirit and scope of the invention.