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. ln 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 1 83 932 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 1800 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.

Altematively, 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 flue 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 runing 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.