Title of Invention

BRUSHLESS OUTER ROTOR PERMANENT MAGNET D.C. ELECTRIC MOTOR

Abstract

Brushless Outer Rotor Permanent Magnet D.C. Electric Motor comprising of Outer rotor with metal ring on which 24 strong permanently magnetized magnets in 12 pairs of North and South Pole charge are fixed on rotor ring; right side end shield and left side end shield are machined to join with rotor ring; Stator with shaft provided with center hole through which connection wires pass from stator winding to shaft; smaller end of shaft matches with size of right side end-shield bearing and other matches with left side end-shield bearing; both bearings are fixed at center of both sides of end shields respectively; Stamping core fitted on plate having 72 slots on which three hall-effect sensors fitted; Three-phase coil winding placed in stamping slots which are 120°E out of phase from each other at symmetrical displacement producing continuous torque; Connection wires from hall-effect sensors to logic controller for controlling reversal of polarity.

Full Text

FORM-2 THE PATENTS ACT, 1970 (39 of 1970) COMPLETE SPECIFICATION (See section 10; rule 13) "BRUSHLESS OUTER ROTOR PERMANENT MAGNET D.C. ELECTRIC MOTOR" SAVALIA RAVJIBHAI MADHABHAI An Indian National having his address at C/o. Savalia Research Centre, Opp. 137, Last Bus Stop, Near Kamdar Kalyan Kendra, New Bapunagar, Ahmedabad - 380 024. Gujarat State, India. The following specification particularly describes the nature of this invention and the manner in which it is to be performed: - GRANTED 19-10-2006 This invention particularly relates to a brushless outer rotor permanent magnet D.C. motor with high efficiency and high torque that saves power. Every man living on earth is almost dependent on external energy source. High growth rate of population and per head more requirement of power multiplies huge requirement of energy. Electricity is one of the main energy sources, which is mostly used because of its convenience. The major problems associated with this energy are: 1. It is costly. 2. It has shortage. 3. The method of generating electricity is highly polluting. This is responsible to create Green House Effect, which is one of the causes of Global Warming. The above said problems instigate us to save power. Saving of electricity usage will reduce the need to generate more electricity, which ultimately result in lesser pollution and benefit economically. Most of the electrical equipments use Induction motor to convert electrical power into required form and magnitude of mechanical power. These motors have inner rotor and outer stator. There are many disadvantages associated with the same: 1. Available induction motors run at very high speed, while most of the applications associated with these motors require only a speed ratio of 1 to 5. As a result of the high speed, the Components at contact between these two become extremely hot which decrease their life and this calls for frequent replacement of these components. 2. Most of the conventional Induction motors are low efficient because required magnetic field to run motor in rotation is generated by using electric power. These motors require large amount of copper wire for coil winding and stamping mass as electro magnetic core to generate magnetic field. Copper wire in coil winds and core material losses some electric power as entropy thus reducing overall efficiency of the motor. 3. Significant amount of electric power is lost as Entropy as mentioned above. (The energy that does not convert in to mechanical form and wasted to thermal form is entropy.) Entropy is also a one of the major causes for global worming. 4. The conventional motors require extra electric power like electro magnet to get strong magnetic field thus adding into usage of electric power. 5. The efficiency of this motor is very poor as the utilization of mechanical energy is very less compared to its generation. 6. Low efficient induction motor heats up very high. So, coil windings gets short circuit and it burns out. Rewinding of coil adds up major cost in maintenance. 7. Being low efficient, the motor becomes very hot. So lubricatives in bearing burns out and that cause bearing's life failure. One of the major problems with induction motor is to replace ball bearing frequently thus adding into maintenance cost. 8. Most of the conventional motors do not provide high torque that is required in many applications to get started. 9. This conventional induction motor require large amount of copper wire for coil winding and stamping mass as electro magnetic core to generate magnetic field which makes it heavy in weight and huge in size. Objects of the invention: The object of this invention is to provide a Brushless Outer Rotor Permanent Magnet Direct Current Electric Motor with the use of very strong permanent magnets to get strong magnetic field to achieve high efficiency. The further object of this invention is to provide a Brushless Outer Rotor Permanent Magnet Direct Current Electric Motor that allows obtaining controllable speed. The further object of this invention is to provide a Brushless Outer Rotor Permanent Magnet Direct Current Electric Motor that saves electricity in significant amount, as extra electric power required by electro magnet is not required by strong permanent magnets. The further object of this invention is to provide a Brushless Outer Rotor Permanent Magnet Direct Current Electric Motor that uses controller circuit to perform commutation instead brushes, slip rings or any mechanical commutator for efficient functioning. The further object of this invention is to provide a Brushless Outer Rotor Permanent Magnet Direct Current Electric Motor, which does not heat up so frequent replacement of related parts, is not required involving less maintenance cost. The further object of this invention is to provide a Brushless Outer Rotor Permanent Magnet Direct Current Electric Motor that is compact in size and light in weight as mass of copper used is significantly less. The further object of this invention is to provide a Brushless Outer Rotor Permanent Magnet Direct Current Electric Motor in which outer rotor has large diameter that works as cooling system. The further object of this invention is to provide a Brushless Outer Rotor Permanent Magnet Direct Current Electric Motor in which shelf life of coil winding is long. The further object of this invention is to provide a Brushless Outer Rotor Permanent Magnet Direct Current Electric Motor that provides high torque that is required in many applications to get started. Description of the Invention: The proposed motor has rotor on outer side and stator coil windings are in center of motor. The proposed motor has following basic components: 1. Rotor that contains: - Magnet ring, Bearings and End shields. 2. Stator that contains: - Stamping coil, Cast lron(C.I.) plates, Shaft, Connection wires. 3. Logic Controller 4. Hall Effect sensors The proposed motor is made in three phases coil winding. The proposed motor runs on three-phase D.C. power. If it requires running on grid A.C. power, A.C. power should be converted into D.C. power first. The invention will now be described in more details with reference to the accompanying drawings. Fig. 1 shows the cross sectional elevation of the Brushless Outer Rotor Permanent Magnet Direct Current Electric Motor which is further referred to as B.L.P.M.D.C. Electric Motor. Fig-2 shows Hall Effect Sensor position on stamping teeth. Fig. 3 shows wave pattern of the proposed motor. Fig. 4 shows commutation sequence. Referring to Fig. 1 and 2, rotor is made of metal ring (1). Strong permanently magnetized magnets (2) are fixed by adhesive on inner surface of rotor ring (1). 24 Magnets (2) are in 12 pairs of North Pole charge and South Pole charge. Right side end shield (3) and left side end shield (11) are machined as per required size to join with rotor ring (1) machined. Right side end shield (3) is machined in "V" shape groove (13) for V-belt drive. Shaft (9) is machined as per requirement. Center hole (8) is provided through which connection wires (7) pass from stator winding (4) to outer side of shaft (9). Shaft (9) is firmly fixed in center hole (8) of plate (6). Smaller end of shaft (9) is according to the size of right side end-shield bearing (12) and the other end of shaft (9) is according to left side end-shield bearing (10). Right side end-shield bearing (12) and left right side end-shield bearing (10) are fixed at center of right side end shield (3) and left side end shield (11) respectively. Stamping core (5) is tight fitted on outer surface of plate (6). Stamping core (5) has 72 slots on outer surface of stamping slot (14). Three-phase coil winding (4) is placed in stamping slots (14) at 120°E from each other at symmetrical displacement and turns of coil winding (4) are selected as per requirement. One end of connection wires (7) is connected with coil winding (4) and other end of connection wires (7) is coming out from center hole (8) of shaft (9). Three hall-effect sensors (15) are fitted on outer surface of teeth of stamping core (5). Connection wires (7) from hall-effect sensors (15) are also coming out from center hole (8) of shaft. Outer end of connection wires (7) are connected to logic controller (17). Motor shaft (9) is fitted on stand (16). The proposed motor has mainly following sections:- Stator that comprises of shaft (9), Plate (6), stamping core (5), coil winding (4), hall effect sensors (15), connection wires (7) and logic controller (17). All these components are stable. These components do not move or rotate. Rotor includes rotor steel ring (1), magnets (2), right side end-shield (3), left side end-shield (11), right side end-shield bearing (12) and left side end- shield bearing (10). These components rotate while power supply is given to the motor. In most of the conventional induction motors, the rotor is kept in center of the motor and stator on the outer side of the motor, rotor parts are not visible, only rotating shaft coming from end shield is visible. Whereas in the proposed motor, rotor is on outer side that is visible. Stator kept inside the motor is not visible. This arrangement makes • Magnets (2) keep strongly fix with inner surface of outer ring (1) due to strong centrifugal force during rotational state. • Outer rotor to work as cooling system. Most conventional Induction motor are low efficient because required magnetic field to run motor in rotational is generated by electric power. This conventional induction motor require large amount of copper wire for coil winding and stamping mass as electro magnetic core to generate magnetic field. Copper wire in coil winds and core material losses some electric power as entropy, resulting into dissipating of heat. This wasted power can be not converted in to mechanical energy thus reduces efficiency of conventional induction motor. In proposed motor, very strong 24 permanent magnets (2) are used to get strong magnetic field. These magnets (2) are permanently magnetic charged so it does not require extra electric power like electro magnet that saves significant amount of electric power. Moreover, strong magnetic field generated by permanent magnets (2) minimizes stamping core and copper wire for coil winding (4). This helps to • Minimize power loss as entropy, that also saves electric power, • Light in weight and compact in size. Thus, the proposed motor saves power at multi stages making it efficient and economical. Working of Invention: A brushless motor, as its name suggests, is a motor without brushes, slip rings or any mechanical commutator, that is required in conventional D.C. motors. In the proposed motor, the polarity of the current that passes through coil winding (4) is reversed every time when a magnet pole passes by in order to ensure that the torque is unidirectional. In the conventional D.C. motor, commutator and brushes reverse current polarity. In the proposed motor, 24 strong magnets (2), which are permanently magnetic, charged so it does not require extra electric power to generate magnetic field. In proposed motor, the polarity reversal is performed electronic commutation by logic controller (17 Fig. 2), which is programmed to perform switching in synchronism with the magnet position on the rotor. The phase current in the proposed motor switches polarity in synchronism with the passage of alternate N and S magnet poles. The motor is said to operate with square wave excitation as shown in fig. 3. The back EMF (electro motive force) in this case is usually arranged to be trapezoidal and the terms square wave and trapezoidal are used interchangeably to refer to the motor. As shown figure 3, the three phases have been labeled A, B and C respectively. In the figure 3, the back EMF shapes (18), i.e., the back EMF divided by speed, are trapezoids having 2/3 duty cycle. That is, for each 180°E the back EMF shape (18) is constant over 120°E. The current (19) associated with each back EMF is composed of rectangular pulses having a 2/3 duty cycle, where the nonzero portions of the pulses are aligned with the flat areas of the respective back EMF shapes (18 Fig. 3) and the polarity of the current (19) matched that of the back EMF (18). Following figure 3, the constant torque produced is shown at the bottom of the figure 3. Over each 60°E segment, positive current flows in one phase, negative current flows in another, and no current flows in the third phase. The letters below the constant torque line signify the two phases carrying current, with the over bar denoting negative current flow or flow out of a phase. Every 60°E, where the back EMF (18) in a phase makes a transition at Tl, T2, T3, T4, T5 & T6 in three phase as sequence (fig. 3 & fig. 4), the current in one phase remains unchanged, while the current in another goes to zero, and the current in the third becomes nonzero. Over 360°E, there are six transitions or commutations before the sequence repeats. As a result, this motor drive is often called a six steps drive. For exact rotor magnet position information there are three Hall effect sensors (15 Fig. 1) used. These sensors (15) provide feedback to the logic controller (17 Fig. 2) for controlling the sequence. Every 60°E rotation one magnet in sequence 'N' or'S' pole passes by sensors (15 Fig. 1) that generate logic signals and it feedback to the logic controller (17) for commutation. 'N' & 'S' pole are in sequence passes by hall sensors (15), that is main mechanism to reverse current polarity in coil winding (4 Fig. 1) of three phase. Hall effect sensors (15) sense polarity of each phase and send signals to logic controller (17). The processor of logic controller (17) calculates and at exact magnet position it reverses current polarity of coil of relevant phase to maintain constant torque (figure 3 Bottom line). Reversal in current polarity is caused by reverse magnet polarity passing by hall effect sensors (15) (Refer Fig. 1). One duty cycle of 360°E (Figure 3 & Figure 4) 1. Every 60°E transition point for commutation to change the current polarity in one phase out of three (fig. 3 & fig. 4) 2. Every 120°E current reverse in one phase out of three in sequence (fig. 3 & fig. 4) 3. Every 60°E one phase remain with no current (fig. 3 & fig. 4) 4. Every 120°E one phase keep positive current out of three phase (fig. 3 & fig. 4) 5. Every 120°E one phase keep negative current (fig. 3 & fig. 4) 6. Every one rotation (Cycle) there are six time commutation in three phase and there are two time commutation in every phase in every duty cycle (fig. 3 & fig. 4) In this way, motor rotate at constant torque. R.P.M. is determined by back EMF, which is dependent on flux density and number of turns of coil winding (4). The turns of coil winding (4) are fixed as per requirement. Certain arrangement such as variable pot etc. can be provided on the outer side of logic controller (17) if required, to control R.P.M.

Documents:

881-mum-2004-abstract(19-10-2006).doc

881-mum-2004-abstract(19-10-2006).pdf

881-mum-2004-cancelled pages(19-10-2006).pdf

881-mum-2004-claims(granted)-(19-10-2006).doc

881-mum-2004-claims(granted)-(19-10-2006).pdf

881-mum-2004-correspondnce(19-10-2006).pdf

881-mum-2004-correspondnce(ipo)-(12-4-2007).pdf

881-mum-2004-drawing(19-10-2006).pdf

881-mum-2004-form 1(13-8-2004).pdf

881-mum-2004-form 1(19-10-2006).pdf

881-mum-2004-form 1(29-6-2006).pdf

881-mum-2004-form 18(29-6-2006).pdf

881-mum-2004-form 2(granted)-(19-10-2006).doc

881-mum-2004-form 2(granted)-(19-10-2006).pdf

881-mum-2004-form 26(13-8-2004).pdf

881-mum-2004-form 3(29-6-2006).pdf

881-mum-2004-form 5(26-6-2006).pdf

881-mum-2004-form 9(26-4-2005).pdf

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