A HIGH PERFORMANCE ELECTRIC MOTOR

Abstract: The object of the present invention is to obtain a high performance and low-cost electric motor that simplifies the transfer of the mechanical motion created by the motor to the driven load, requiring none or some mechanical transfer means such as belt/pulley arrangement or a gear box, on applications especially requiring varying torque and speed operations, requiring wide torque-speed range; requiring high torque value at low speeds. In the motor subject to the present invention, which has a structure with external rotor, the stator and rotor are formed by the packaging of magnetic lamination segments that are cut in 180 DEG or smaller angles in order to complete 360 DEG . The rotor yoke (2) of said motor on the inner surface of which a series of permanent magnets (3) are placed with no spaced apart intervals and said permanent magnets (3) are connected with the motor shaft (7) by the rotor body (1) and rotor hub which are made of non-polymeric or non-magnetic metal suitable for injection casting, or directly with the load shaft.

Description: A HIGH PERFORMANCE ELECTRIC MOTOR The present invention is related to a high performance electric motor with intelligent motion properties. Electric motors convert electrical energy into mechanical energy and transfer the motion to the load through their shafts. During this transfer, a high level of performance, is described as low noise level, low torque vibration, low speed oscillation; high power/weight ratio, high torque/current ratio, high efficiency, high motion controllability and high sensing capacity. The control mechanisms and sensors, required for the realization of motion profiles desired for the loads, have to be accurate and expensive in proportion with the complexity of motion. However, motor's character; may eliminate the necessity of expensive control mechanism and sensor. This aspect in motors is known as high sensing capacity. In the patent application No. EP 0629 735 A and in the U.S. patents No.s US 5.266. 855 and US 4.853.571 motors developed to receive high torque at low speeds are disclosed. In referred motors the stator and rotor yokes are formed as annular helical yokes edgewise wound from strips of magnetic material. This way of winding helical yokes causes slot opening to be large, that in turn may lead to the loss of torque and noisy operation. In the said motors and in the motor described in the patent application No. GB 2 183 932 A the magnet placed inside the rotor are spaced apart and each magnet comprises a pole. In the said motor the stator windings are wound on each teeth. The object of the present invention is to obtain a high performance and low-cost electric motor that simplifies the transfer of the mechanical motion created by the motor to the driven load, requiring none or some mechanical transfer means such as belt/pulley orrangement or a gear box, on applications especially requiring varying torque and speed operations, requiring wide torque-speed range; requiring high torque value at low speeds. A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawing in which: Figure 1 is the general view of the motor Figure 2 is the AA cross-section of Fig.l. Figure 3 is the view of stator lamination Figure 4 is the view of skewed stator laminations Figure 5 is the view of a segment of stator lamination Figure 6 is the view of a segment of rotor lamination. Figure 7 is the part of rotor circle arc. In the motor subject to the present invention, the stator and rotor are formed by the packaging of magnetic lamination segments (Figures 5 and 7). The said stator segments (Fig.5) and rotor segments (Fig.7) are cut in 180° or smaller angles in order to complete 360°. Providing the joining edges are be in the middle of the teeth. In this case, the flux loss at joining edges will be minimum and hence the torque loss will be minimised. Said stator and rotor segments, (Fig.5 and 7) cut in 180° or smaller angles, have holes which are (9,10,11) required for packaging. Each lamination layer of the said stator yoke (5) and rotor yoke (2) are stacked on top of each other axially in such a manner that the joining edges of the said stator and rotor segments (Figures 5 and 7) are not lined and the said holes (9,10,11) are on the same line. Such arranged segments are placed in a suitable mould and the holes (9,10,11) are filled with a non-polymeric or non-magnetic metal suitable for injection moulding by pressure die casting method in order to form the rotor and stator yokes (2 and 5)and to join the segments. Alternatively, the segments may be riveted to form stator and rotor yokes and to join segments, through the said holes (9,10,11). The holes (9) on the pole piece are discarded when considered unnecessary, depending on the motor diameter. The motor subject to the present invention has been designed by two different approaches. The waveform of the induced voltage in the stator winding is trapezoidal in the first approach, is sinusoidal in the second approach. There are various designs to obtain the induced voltage in the form of sinusoidal wave. One of them is to skew the package of the stator laminations. Segment-cutting method does not involve any dimensional restrictions and the slot (8) opening can be made at any value. The above mentioned motor has an outer rotor and a series of permanent magnets (3) placed with no spaced apart intervals on the inner surface of the rotor yoke (2). These permanent magnets (3) are magnetized by a proper magnetizing fixture, to form as many poles as required by the application. In this case, one or more poles are obtained on one magnet segment. This method provides convenience in production. The permanent magnets (3) used at the rotor of the motor are magnetized radically or in parallel to provide proper polarisation. The way of magnetisation and polarization determines the number of the poles, phase winding type and number of slot, of the motor. The rotor yoke (2) of said motor and said permanent magnets (3) are connected with the motor shaft (7) by the rotor body (1) and rotor hub which are made of non -polymeric or non-magnetic metal suitable for injection casting, or directly with the load shaft. Above said motor allows a connection with the load shaft without requiring a motor shaft, due to its structural and dynamic properties. Thus cost saving is achieved by the elimination of motor shaft. For example, in certain applications that require such mechanical transfer elements as belt-pulley or switch gear box, the necessity of employing speed-reducing or motion- transferring elements is eliminated by re arranging the placement, using the motor of the present invention. Said stator is connected to the motor shaft (7) or load shaft concentrically by a non polymeric or non magnetic metal (6) suitable for injection casting. The length of the rotor yoke (2) is equal to the length of stator yokes or longer by an appropriate proportion. There are slots (8) on said stator for one or more phase AC windings (4) to be placed in. The number of slots (8) per phase and pole can be equal to 1(=1), more than one (>1) or less than one (<1). In case it is equal to 1, concentric winding and in other cases, fractional-pitch winding is used. It is possible to wind stator windings either directly on each teeth or by skipping two or more slot pitches. In order to monitor the voltage at the winding induced the permanent magnets (3) at the said rotor the position of the rotor is detected and the said stator windings (4) are fed by an inverter from the direct current supply. The position of the rotor is detected by optic sensors or by magnetic sensors that are placed in the air gap, with electrical angles suitable to the stator surface. This information obtained by the sensors are evaluated at the electronic control unit and the rotational direction, speed and torque of the motor is controlled by turning on and off the power electronic switches on the inverter. Said motor has been designed according to two different approaches. In the First approach the waveform of the voltage induced at the stator winding (4) is trapezoidal and in the second approach it is sinusoidal. In the first approach the noise level and torque vibration of the motors are reduced to a low level by using the electronic control method. In some applications such as servo systems there is need for low noiselevel and torque vibration. In this case, a motor wherein the waveform of the voltage induced at the stator winding (4) is sinusoidal, may be used. The purpose of this application is to be able to control the motor having a sinusoidal electro motor force (EMF) waveform, by means of low-cost rotor position sensors. In order to obtain the induced voltage in a trapezoidal waveform, radial magnetization with no angles and concentrical winding are employed. Whereas to obtain induced voltage in a sinusoidal waveform, there are various motor design options. These are: • Skewing stator laminations. • Polorization of permanent magnets (3) at the rotor by magnatizing, to skew them in the proper angle. • Determining the number of stator slots (8) per phase and pole, fractionally. • Forming a sinusoidal air gap flux by parallel magnetizing the permanent magnets (3) at the rotor or by using different types of magnets in the permanent magnet group forming one pole. The common object of these design options is to obtain the magnetic flux formed at the air gap in the form of a sinusoidal wave. The electronic control unit realizes mechanical motion control by utilizing different algorithms, depending on the waveform of the voltage induced at the said stator winding (4). In line with application demands, the stator windings (4) for both types of motor are made as tap-winding or non-tap winding depending on the required speed range. At low speed, the tap winding is totally used whereas at high speed only the necessary amount is used. The electronic control unit developed in line with the requirements of the application determines the part of the winding to be used, by running digital algorithm. As an alternative, required speed levels are reached by using a non-tap stator winding instead of tap-windings, by changing the algorithm. The referred motor is fed by an inverter consisting of power electronic switches, equal in number to the number of phases for a half-wave feeding, and twice the number of phases for a full-wave feeding. In the said inverter, a diode may be connected to each power electronic switch inversely parallel or in case the said switches are chosen as MOS gated switches, their own parasitical diode of the switch itself may be used. A digital controller is used for the application of algorithms determined for the control of the said motor speed and torque. Alternatively, in order to reduce the cost of the controller, programmable logic elements may also be used for the application of algorithms in order to process the signals from the position sensor. Said motor provides controlled both clock and counter clock wise, 100% mechanical motion continuously. In said motor, motor position is sensed by simple sensors and any desired mechanical motion is transferred to the load. It is possible for the said motor to provide the desired mechanical motion with a good performance by small changes made at its control circuit, at a 110 V, 220 V and any other voltage value without making any changes in the motor geometry. The motor can also be run at 110V, 220V by arranging the control circuit properly. The said motor runs with a noise level of approximately 35 dB at low speed and under 100 Watt load; and with approximately 60dB noise level at speeds between 1500 rpm and 2000 rpm under approximately 600 watt load. Said motor without requiring isolation provides the proper mechanical motor in application that need to be worked with low noise level and low vibration.

Claims: CLAIMS 1. An electric motor wherein its stator consists of two or more phase windings; rotor length is equal to or longer that the stator length simplifying the transfer of mechanical motion to the driven load; which does not require or reduces the requirement of mechanical transfer elements such as belt-pulley or gearbox having an outer motor; characterized in that, the permanent magnets are placed on the inner surface of rotor yoke without any space in between and each lamination of the rotor and stator yokes are formed by stacking segments axially one on the other. 2. An electric motor as claimed in claim 1, characterized in that the segments required to form the said rotor and stator are cut in 180° or smaller angles so that they complete 360°, segments are cut such that their joining edges are brought in the middle of teeth, holes exist on segments for packaging, each lamination plate of said rotor and stator yokes is stacked axially on top of the other such that the said rotor and stator segments do not overlap and said holes overlap on the same vertical alignment, segments are placed in a mould, said holes are filled with a non-polymeric or non-magnetic metal suitable for injection casting by pressure diecasting to form rotor and stator yokes and to connect segment. 3. An electric motor as claimed in claim 1 , characterized in that the segments are riveted through the said holes to form the said rotor and stator yokes and to join the segments. 4. An electric motor as claimed in claims 1 to 3; characterized in that the permanent magnets form one and more poles radially and in parallel in one segment, and are placed inside the rotor without any space in between. 5. An electric motor as claimed in claims 1 to 4, characterized in that the said rotor yoke and the said permanent magnets are connected directly to the load shaft by means of the rotor body and hub formed by a non polymeric and nonmagnetic metal suitable for injection casting. 5 6. An electric motor as claimed in claims 1 to 5, characterized in that the two or more phase stator windings of the said motor, are wound by arcing two or more slot pitches. 10 7. An electric motor as claimed in claims 1 to 6, characterized in that the concentric type of winding and radial magnetisation with no angles are applied in order to obtain a trapezoidal waveform for the voltage induced at the stator winding of the said motor. 15 8. An electric motor as claimed in claims 1 to 6; characterized in that the stator lamination package is skewed, so that joining edges of said segments do not line and said holes overlap in a skewed way with the said skew angle to obtain the induced voltage at the stator in sinusoidal form. 20 9. An electric motor as claimed in claims 1 to 6, characterized in that polarization of permanent magnets is skewed at an appropriate angle in order to obtain the voltage induced at the stator winding in the form of a sinusoidal wave. o 5 10. An electric motor as claimed in claims 1 to 6, characterized in that in the said motor, the stator slot number per phase and per pole is determined in fractions, in order to obtain the voltage induced at the stator winding in the form of a sinusoidal wave. 0 1 1. An electric motor as claimed in claims 1 to 6, characterized in that in the said motor, said permanent magnets at the said rotor are magnetized in parallel in order to obtain the voltage induced at the stator winding in the form of a sinusoidal wave. 12. An electric motor as claimed in to claims 1 to 6, characterized in that in the said motor, sinusoidal air gap flux is formed by using different types of permanent magnets in the permanent magnet group forming one pole in order to obtain the voltage induced at the stator winding in the form of a sinusoidal wave. 13. An electric motor as claimed in claims 1 to 12; characterized in that the electric motor, running in one or more speeds has tapped or non-tapped windings. 14. An electric motor according to claims 1 to 12, characterized in that, the number of the stator windings used for applications requiring tap-winding may be reduced to non-tap winding by changing the digital algorithm. 15. An electric motor as claimed in claims 1 to 14, characterized in that said motor is fed by an inverter consisting of power electronic switches equal in number to the number of phases for a half- wave feeding and twice the number of phases for a full wave feeding and in the said inverter, a diode- element being connected inversely parallel to each power electronic switches, or in case the chosen power electronic switches are MOS-gated, their own parasitical diodes are used; and programmable logic elements and digital controller are used in the application of the algorithms determined for the control of speed and torque in order to process the signals produced by the position sensor. 16. An electric motor as claimed in claims 1 to 15, characterized in that rotor position in said motor is determined by the electronic drive of the motor by using simple sensors its speed and torque as a function of the rotor angle, in order to provide any of mechanical motion at the load applied by the motor. 1 7. An electric motor as claimed in claims 1 to 16, characterized in that it does not require any isolation for the applications that require operation at low noise level and low vibration due to its operating properties of working at low speeds at 100 watts, with a noise level of approximately 35 dB and at speeds of 1500 to 2000 rpm, at 600 watts with a noise level of approximately 60 dB. 18. An electric motor as claimed in Claims 1 to 17, characterized in that it provides any desired mechanical motion with a high performance at 110 Volts, 220 Volts and any other mains voltage value by making small changes in the electronic drive of the motor without making any modifications in the motor geometry. 19. An electric motor as claimed in claims 1 to 17 characterized in that said motor is operated at two different voltage values, such as 110 volts and 220 volts, by selecting with a control switch.

Inventors: ALBAS GUENSU, DIRIL ORHAN, SOENMEZOEZ FEHMI, TEZDUYAR LATIF, ALBAS, GUENSU, DIRIL, ORHAN, SOENMEZOEZ, FEHMI, TEZDUYAR, LATIF
Applicants: ALBAS GUENSU, ARCELIK AS, DIRIL ORHAN, SOENMEZOEZ FEHMI, TEZDUYAR LATIF, ALBAS, GUENSU, ARCELIK A.S., DIRIL, ORHAN, SOENMEZOEZ, FEHMI, TEZDUYAR, LATIF
Application year: 1997
Main classification: H02N
IPC codes: H02K1, H02K3, H02K21, H02K29