AN ELECTRIC MOTOR

Abstract: An electric motor with solely one direction of rotation and electronic speed control, includes two mutually rotatable parts with ferromagnetic cores (1, 2) separated by an air gap (6). The state core (1) is provided with a peripherally extending ring of magnet pole groups each including at least one pair of salient magnet poles (3, 4), the one being ferromagnetic (4) and the other permanently magnetic (3). All magnet pole groups are connected magnetically to a common magnetizing winding (5), which magnetizes all magnet pole groups simultaneously in a manner such that the ferromagnetic pole and the permantely magnetic pole of each group is magnetized in the same direction. The rotor core (2) is provided with a peripherally extending ring of salient ferromagnetic reluctance poles (7) with twice the pole pitch of the stator. Each reluctance pole has a width which over a part of the pole corresponds to a stator pole pitch which over the remaining part of the reluctance pole is smaller, so that each reluctance pole (7) presents a part (7B) which projects in a predetermined peripheral direction common to all reluctance poles.

Description: An electric motor The present invention relates to an electric motor which is of the kind defined in the preamble of Claim 1 and which can be supplied with current and its speed con¬ trolled by a simple electronic circuit and which has a single, pre-determined direction of rotation. The inven¬ tion also relates to an appropriate electronic supply and control arrangement for use with such a motor. There are several very wide areas of use in which elec¬ tric motors need rotate only in one direction. Such areas include the drive motors of fans, pumps, centri¬ fuges, compressors and different domestic electrical appliances, and also many other usages. It would be highly beneficial in the case of many of these electric motor drives to be able to vary the speed of the motor in a controllable manner and/or to be able to achieve higher speeds than those available with the use of commutator-equipped universal motors or induction motors supplied directly from the mains. This requires, however, a motor with which the supply of current is controlled electronically, hereinafter refer- red to as an electronic motor. With a few exceptions, present day electronic motors are intended to include electronically reversible rotation, which as before mentioned is not required in several, very wide areas in which such motors are used, and consequently electronic motors have not been used in many extensive fields of use, for reasons of economy. The major part of the costs of present day electronic motors, for instance, induc¬ tion motors to which current is supplied via frequency converters, lies in the supply electronics. The main components of the frequency converter, e.g. the power transistors, are responsible for a highly significant part of these costs. Figure 1 of the accompanying draw¬ ings illustrates a conventional and quite common embodi¬ ment of the inverter part of a frequency converter intended for controlling electronically the supply of electric current to an induction motor having, for instance, a power range of 0.5-2.5 kW. This inverter contains no less than six MOSFET-type transistors with associated drive circuits, and twelve rapid diods. Consequently, in order to reduce radically the costs of an electric motor that has electronically controlled power supply facilities, it is necessary to lower radi¬ cally the cost of the supply electronics. In other words, it is necessary to use much simpler electronics containing fewer components. Accordingly, an object of this invention is to provide an electric motor which will enable the supply of power thereto to be controlled electronically with the aid of much simpler supply electronics containing far less components than present day known electronic motors. This object is achieved with an electronic motor con¬ structed in accordance with the present invention and having the essential characteristic features set forth in Claim 1. Advantageous further developments and embodiments of the inventive motor have the characteris¬ tic features set forth in Claims 2-12. Distinct from the majority of present day known electronic motors, the inventive electronic motor is not constructed for elec¬ tronic reversible rotation, but will only rotate in one pre-determined direction. This pre-determined direction can only be changed by mechanical modification of the motor. As before mentioned, this will have no importance in the large majority of fields in which, such motc£8 are used. Claim 13 defines the characteristic features of an electronic supply circuit intended for a motor construc¬ ted in accordance with the invention. The invention will now be described in more detail with reference to the accompanying drawings, in which Figure 1 illustrates the aforedescribed construction of the inverter used in a frequency converter of the type generally used in present day electronic motors; Figure 2 is a schematic and principle end view of an exemplifying first embodiment of an electric motor constructed in accordance with the invention; Figure 3 is a spread sheet which illustrates schemati¬ cally the configuration and arrangement of the stator poles and the rotor poles of the motor illustrated in Figure 2; Figure 4 is a view similar to Figure 3, illustrating an alternative rotor pole embodiment, which enables the rotational direction of the motor to be reversed with the aid of a simple, mechanical switching facility; Figure 5 is a schematic and principle side view, partly in axial section, of an exemplifying second embodiment of a motor constructed in accordance with the invention; Figure 6 is a sectional view of the motor according to Figure 5, taken along the line VI-VI in Figure 5; Figure 7 is a schematic spread view illustrating the configuration of the rotor used with the motor illustra¬ ted in Figures 5 and 6; Figure 8 is a schematic, principle side view, partly in axial section, of an exemplifying third embodiment of a motor constructed in accordance with the invention; Figure 9 is a sectional view of the motor shown in Figure 8, taken along the line IX-IX in Figure 8; Figure 10 is a diagram suitable for use when accounting for the torque development of a motor according to the invention; and Figure 11 illustrates an advantageous electronic supply circuit for use with a motor constructed in accordance with the present invention. The inventive motor operates in accordance with the reluctance principle, wherein the ferromagnetic core on one of the two parts of the motor which rotate relative to one another is provided with both ferromagnetic and permanent-magnetic poles, which are magnetized with the aid of a magnetizing winding, whereas the ferromagnetic core of the other part of said motor is provided with salient, ferromagnetic reluctance poles. Figures 2 and 3 illustrate schematically a first exemplifying embodiment of an inventive motor, compri¬ sing a stator 1 having a ferromagnetic core, and a rotor 2 having a ferromagnetic core and an intermediate, cylindrical air gap 6. The stator 1 includes an even number of magnetic pole groups, in the illustrated embodiment four groups, each of which has a salient permanent-magnetic pole 3 and a salient ferromagnetic pole 4. The permanent-magnetic polarity of the poles 3 is indicated in the drawings with the aid of arrows extending in the direction of the magnetic flux which the permanent magnets endeavour to drive. Each of the magnet pole groups comprising a permanently magnetic pole 3 and a ferromagnetic pole 4 is enclosed by part of a magnetizing winding 5, such that the permanently magnetic pole 3 and the ferromagnetic pole 4 of each magnet pole group is magnetized in mutually the same direction by the winding 5. The permanently magnetic poles 3 have mutually opposite polarities in mutually adjacent magnet pole groups, and mutually adjacent magnet pole groups are magnetized by the winding 5 in mutually opposite directions. An advantage is afforded when the winding 5 is arranged so that the magnetization generated thereby will oppose the polarity of the per¬ manently magnetic poles 3. Figure 3 illustrates schematically the configuration of the stator poles and the rotor poles, and also shows the pole arrangement in a spread-out view. It will be seen from Figure 3 that the permanently magnetic stator poles 3 and the ferromagnetic stator poles 4 are arranged with a constant pole pitch and with a slight interspace therebetween. Each pole may advantageously have a width in the peripheral direction corresponding to substan¬ tially two thirds of the pole pitch. The ferromagnetic core of the rotor 2 is configured with the same number of salient, ferromagnetic reluctance poles 7 as there are magnetic pole groups on the stator i.e. in the illustrated embodiment four such reluctance poles. It will also be seen from Figure 3 that the pole pitch of these reluctance poles 7 is twice that of the stator poles 3, 4. Each reluctance pole 7 has along approximately half of its axial length essentially the same peripheral width as a stator pole 3, 4, and over the remainder of its axial length a width which cor¬ responds essentially to one half of a rotor pole pitch. Thus, each rotor pole 7 can be considered to comprise a main pole 7A of uniform width and a nose 7B which pro¬ jects from the main pole. The noses 7B of all rotor poles project from respective main poles 7A in mutually the same peripheral direction. When no current flows through the magnetizing winding 5, the rotor 2 has stable equilibrium states, in the illustrated embodiment four such states, in which the rotor poles 7 are positioned such as to fully cover the permanently magnetic stator poles 3. In these operatio¬ nal states of the rotor, each pole nose 7B extends peripherally forwards to the nearest located ferromag¬ netic stator pole. This position or state is hereinafter referred to as the start position. Figure 3 shows the stator poles and the rotor poles in one such mutual position. When the rotor is in its start position and current is supplied to the magnetizing winding 5 in the direction marked in Figure 2, the rotor pole noses 7B are drawn in a direction towards adjacent ferromagnetic stator poles 4, while, at the same time, the holding force of the permanently magnetic stator poles 3 is weakened or possibly reduced down to zero. As a result, first the rotor pole noses 7B and then the main parts 7A of the rotor poles will be drawn in beneath the ferromagnetic stator poles 4. The mutual position between rotor and stator obtained in this way is refer¬ red to in the following as the indrawn position. It will be seen that when the magnetizing current ceases to flow, when, or immediately prior to, reaching the indrawn position, the rotor will continue to rotate in a direction towards the next following start posi¬ tion, and that when the magnetizing current again begins to flow through the winding 5, when, or immediately prior to, reaching the next following start position, the rotor will continue to rotate. It will be understood from this that the current in the magnetizing winding 5 on the stator can be controlled with the aid of a single electronic switch, for example a transistor, and with the aid of a device which functions to detect the mutual rotational position between rotor and stator and to switch the switch on and off in response to the position detected. When no current flows through the magnetizing winding 5, the rotor 2 is also able to adopt unstable equilibrium positions, in the illustrated embodiment four such posi¬ tions, in which the rotor poles partially overlap the ferromagnetic stator poles 4. The motor, however, can also be started from such an unstable equilibrium posi¬ tion, since the supply of current to the winding 5 will result in the rotor 2 being drawn beyond the point of said unstable equilibrium position to an indrawn posi¬ tion. When braking the motor electrically, i.e. generator operation, the winding 5 is supplied with current within the angular intervals occurrent when the rotor rotates from an indrawn position to a start position. No current is supplied during generator operation through the angular intervals in which current is supplied to the winding 5 during motor operation, and vice versa. It will be understood that the exemplifying embodiment of the inventive motor illustrated in Figure 2, 3 can be varied in several respects. For instance, the number of stator pole groups 3, 4 and the number of rotor poles 7 coacting therewith can have any desired even number .whatsoever. Furthermore, each stator pole group may :comprise several pairs of permanently magnetic poles 3 and ferromagnetic poles 4, wherein the poles 3 have mutually the same permanent-magnetic polarity within each pole group and all of both the ferromagnetic and permanently magnetic poles within one and the same pole group are magnetized in one and the same direction by the magnetizing winding 5. The number of rotor poles 7 in this case will naturally equal the total number of pairs of permanently magnetic and ferromagnetic stator poles, since the rotor pole pitch is twice as large as the stator pole pitch. It will also be understood that the stator and rotor can change places in a motor constructed in accordance with the invention, so as to obtain a motor equipped with an external rotor. It will also be understood that, in principle, there is nothing to prevent the magetizing winding and the pole groups, consisting of permanently magnetic and ferromagnetic poles, from being arranged on the rotating part of the motor, while providing the reluctance poles on the stationary part thereof. This latter configuration, however, will naturally require the provision of slip-rings and brushes or like devices, for supplying current to the magnetizing winding. It will be seen from the aforegoing that an inventive motor constructed in accordance with the Figure 2, 3 illustration, will only rotate in one direction, this direction being determined by the direction in which the noses 7B extend peripherally from the main part 7A of the rotor poles 7. An inventive motor constructed in accordance with the principles illustrated in Figures 2 and 3 and operating in the aforedescribed manner can be modified in a rela- tively simple fashion, such as to enable the rotational direction of the motor to be reversed, with the aid of a relatively simple mechanical adjustment. To this end, the rotor poles 7 are configured in the manner illustra¬ ted schematically in Figure 4. In this case, the rotor poles 7 have an axial length which exceeds the active axial length of the stator poles 3, 4, this active axial length being referenced b in Figure 4. Furthermore, each rotor pole 7 is provided with two outwardly projecting noses 7B and 7C of the aforedescribed kind, said noses being located on respective ends of the rotor pole 7 and directed in mutually opposite peripheral directions. The rotor is displaceable axially in relation to the stator, so as to enable to the rotor to be moved between two different working positions. In one of these working positions the rotor pole noses 7B are located within the active area of the stator poles 3, 4, and hence the motor will rotate in the direction determined by the noses 7B, whereas in the other of said working positions the noses 7C are located within the active area of the stator poles 3, 4 and the motor will thus rotate in the opposite direction, determined by the pole noses 7C. A motor of this construction can be used conceivably in those instances when the rotational direction of the motor need not be changed too often. Other embodiments of the invention are also conceivable, such as the embodiment illustrated in Figures 5, 6 and 7 for instance. In the case of this embodiment, both the stator 1 and the rotor 2 are provided with two axially spaced pole rings. Each of the stator pole rings SI and S2 consists of an equal number of permanently magnetic poles 3 and ferromagnetic poles 4, which are disposed alternately in the principle manner illustrated in Figure 3. All of the permanently magnetic poles 3 located within one and the same pole ring SI and S2 respectively have mutually the same permanent magnetic polarity in relation to the air gap but opposite pola¬ rity in relation to the permanently magnetic poles in the other pole ring. Thus, the two stator pole rings SI and S2 are mutually the same, with the exception of the direction of the polarity of the permanently magnetic poles 3. The two rotor pole rings Rl and R2 are mutually identical and constructed in principle in the manner illustrated in Figure 3. Each rotor pole ring Rl will thus include the same number of ferromagnetic reluctance poles 7 as the number of ferromagnetic poles 4 found in each stator pole ring SI, each such rotor pole 7 being configured with a peripherally extending nose 7B which extends in the same direction for all rotor poles 7 in both rotor pole rings Rl and R2. The salient rotor poles 7 can be formed by corresponding recesses 8 in the peripheral surface of the cylindrical rotor core 2. The stator pole rings SI, S2 are joined together by means of a ferromagnetic yoke, such as to enable mag¬ netic flux to pass between the rings SI, S2 in an axial direction. The rotor pole rings Rl, R2 are also con¬ nected together in a similar manner, by means of a ferromagnetic yoke, which conducts magnetic flux axially between the rotor pole rings Rl, R2. In the case of this embodiment, the magnetizing winding or stator winding 5, consists of one single circular coil winding, arranged on the stator core 1 between the two stator pole rings SI, S2. Conveniently, the direc¬ tion of current flow in the winding 5 will be such as to counteract the field generated by the permanently mag¬ netic poles 3 in the two stator pole rings SI, S2. It will be understood that the mutual positions of the stator pole rings SI, S2 and the rotor pole rings Rl, R2 are such that both of the rotor pole rings Rl, R2 will simultaneously adopt a start position in relation to respective stator pole rings SI, S2. It will also be understood that the rotor pole rings of a motor constructed in accordance with Figures 5-7 may include any number of poles whatsoever. Furthermore, it will be understood that the embodiment according to Figures 5-7 may be provided with a conical air gap instead of a cylindrical air gap. It is also possible to construct an inventive motor with a planar air gap. One such embodiment is illustrated schematically in Figures 8 and 9. This embodiment can be obtained, in principle, from the embodiment illustrated and described in Figures 5-7, solely by changing the geometry of the stator core and the rotor core. In the case of the embodiment illustrated in Figures 8 and 9, the stator core 1 has an annular configuration with a U-shaped radially and inwardly open cross-sec¬ tion, wherein the two legs of the U-shaped cross-section carry the two annular stator pole rings SI and S2 which are planar in this case. Each of the stator pole rings SI and S2 consists of an equal number of permanently magnetic poles 3 and ferromagnetic poles 4, arranged alternately to one another. The permanently magnetic poles 3 in the two stator pole rings SI, S2 have, in this case, polarities which are directed in mutually the same axial direction. In the case of this embodiment, each stator pole ring SI, S2 includes three permanent magnetic poles 3 and three ferromagnetic poles 4. ! The rotor 2 mounted on the motor shaft 9, which may be a stably journalled tubular shaft for instance, is located between the two planar, annular stator pole rings SI, S2 and may have the form of a ferromagnetic ring the sur- faces of which facing towards the stator pole rings SI, S2 are configured with rotor poles in accordance with the aforedescribed principle. In the case of this em¬ bodiment, the rotor 2, however, may simply consist of radially projecting ferromagnetic arms, the number of which corresponds to the number of ferromagnetic poles 4 in the stator pole rings SI, S2 and each of which forms a respective rotor pole 7 with the nose 7B extending in one peripheral direction, as will best be seen from Figure 9. In the case of this embodiment, the magnetizing, or stator winding 5 consists of a single, circular coil winding which is arranged within the U-shaped cross- section of the annular stator core 1, in the manner illustrated schematically in the drawing. The embodiment of the invention illustrated in Figures 8 and 9 can be used advantageously for driving centri¬ fuges, agitators, mixers, bobbins for spinning heads, and like machines. It will be seen that when the current flows through the motor winding of the motor according to Figures 5-9, the motor is also magnetized axially. If, as a result here- of, the magnetic leakage field is so powerful as to have a disturbing effect on the ambient surroundings of the motor, the leakage field can be considerably reduced, by configuring the motor with two stators and two rotors of mutually the same type, but with windings whose axial magnetic fields will counteract one another. This enables both of the windings to be supplied from a common electronic supply circuit. The magnetic noise which always occurs when the magnetic forces acting between stator and rotor vary with time and in space, such as in the case of a motor constructed in accordance with the invention, can be reduced in a manner known from other electromachines, by slanting the limiting lines of the rotor poles and/or by making the pole pitch of the motor poles slightly uneven. It will be understood from the aforegoing that a motor constructed in accordance with the invention is provided with one single winding in which current need only flow in one direction. Consequently, the supply of current to an inventive motor can be effected with the aid of a single switch device controlled in response to the angular position of the rotor relative to the stator. When the magnetomotive force of the stator winding decreases, the magnetic field energy in the motor will also decrease. The field energy thus released should preferably thus be returned to the supply source, or alternatively converted to heat in a resistor. Figure 11 illustrates a particularly advantageous embodiment of an electric circuit intended for supplying current to an inventive motor from a d.c. source U D , which may be a galvanic battery, or a capacitor bank connected to a mains-supplied rectifier bridge, for instance. In order to enable magnetic field energy to be fed back to the voltage source U_, the inventive motor is provided, in addition to the aforesaid magnetizing or working winding, referenced Wl in Figure 11, with a return winding W2, which is wound as a secondary winding of the working winding Wl. Thus, the return winding W2 is arranged in the motor physically parallel with the working winding Wl and has the same number of turns as said working winding, although in certain instances the return winding W2 may have a significantly smaller conductor area. Alternatively, the two windings Wl and W2 may also be wound in a bifilar fashion. In this case, voltages of equally high values will be induced in the two windings Wl and Wl when the magnetic field through the windings changes. The supply circuit includes an electronic switching device SW, for instance a transistor, which is control¬ led in response to the angular position of the rotor relative to the stator and which is connected in series with the working winding Wl of the motor, between the two poles of the voltage source U D . The supply circuit also includes a diode D, which is connected in series with the return winding W2, between the two poles of the voltage source U n , in a manner such that the ends of similar polarity of the two windings Wl, W2 with respect to the voltages induced in said windings are each con¬ nected to a respective pole of the voltage source U_., said ends being marked with dots in Figure 11, and such that the current flow direction of the diode D is op¬ posite to the current flow direction of the switching device SW. Furthermore, the supply circuit includes a capacitor C which is connected between the other ends of the two windings Wl and W2. The voltage across the capacitor C is essentially equal to the voltage of the voltage source U D , irrespective of the voltage induced in the windings Wl and W2. When the transistor SW is made conductive,. current begins to flow through the working winding Wl. When the transistor SW begins to become non-conductive, the voltage across the transistor increases to about 2 U n , prior to the diode D taking over the current I 1 flowing through the winding Wl. Subsequent to these events taking place, the return winding W2 also begins to conduct current I_. The manner in which the current flow is divided between the windings Wl and W2 has no sig¬ nificance with respect to the magnetic circuit of the motor. Consequently, an increase in I„ will result immediately in a decrease in I- . In other words, current is conducted in the return winding W2 instead of the working winding Wl. Because of the incomplete magnetic coupling between the windings Wl and W2, only an insig¬ nificant part of the recycled energy will be taken up in the capacitor C. The larger part of the field energy released is fed back to the voltage source U_, through the diode D. If the transistor SW is made conductive prior to decay of the current I_ in the return winding W2, the residual current is taken over by the working winding Wl, in a course of events similar to that described above. The relationship between the total current conducted by the motor winding I = I. + I 2 and the air-gap torque T of the motor can be expressed as T = T pM ( _) + I . k(α) where T pM (α) is the air gap torque with no current through the stator winding as a result of the perma¬ nently magnetic poles of the stator; is the angular position of the rotor relative to the stator, k(α) is a torque factor. The torque factor k(α) is a periodic function of the angular position of the rotor relative to the stator. Figure 10 illustrates the typical variation of the torque factor k(α) as a function of the angular position of the rotor in electric degrees, when a not- insignificant total current in the preferred direction is assumed to be present in the motor winding. The simplest possible form of current supply to an inventive motor is obtained when the motor winding is supplied with rectangular current pulses, i.e. the current has either a specific constant value or is zero. It can be shown mathematically, however, that the mean value of the air gap torque of the motor can be maxi¬ mized irrespective of the magnitude of the losses in the motor winding, when the total motor current is varied in the same manner as the positive part of the function k(α). This applies to motor operation. In the case of generator operation, the current passing through the motor winding shall have the same shape as the negative part of the function k(α), although with reversed sign. The gain achieved in motor torque when modulating the amplitude of the current within a current conducting interval, compared with maintaining the current ampli¬ tude constant, within said current interval, may be as high as 6% in the form of improved machine performance, in a typical case. At the same time, however, the peak current values also increases, and therewith the current load on the switching device used (SW in Figure 11) by a factor of ^2 — 1.41. A suitable compromise may be to increase the peak value of the current by about 25% in comparison with a purely rectangular current pulse of constant amplitude, which would result in a torque increase of about 5%. It should be observed in this context, however, that modulation of current strength within the current conducting interval in accordance with the aforegoing requires the device used to detect the angular position of the rotor relative to the stator to have a correspondingly larger angular resolution.

Claims: CLAIMS 1. An electric motor comprising a first part and a second part which are rotatable relative to one another and each of which has a ferromagnetic core and which are separated by an air gap lying between said cores, characterized in that the ferromagnetic core of said first part (1) has provided on the surface thereof which faces the air gap (6) a plurality of magnet pole groups which are disposed sequentially and peripherally in the direction of mutual rotation of said parts; in that each of said magnet pole groups includes at least one pair of salient magnetic poles (3, 4) which are arranged periph- erally in mutually spaced relationship in said rota¬ tional direction, of which magnet poles one is ferro¬ magnetic (4) and the other permanently magnetic (3) and which are coupled magnetically to a magnetizing winding (5) for simultaneous magnetization of both the ferro- magnetic and the permanently magnetic poles (3, 4) in mutually the same direction relative to the air gap, the pole pitch being constant within each magnet pole group and between mutually adjacent magnet pole groups; in that the ferromagnetic core of the other part (2) is provided on the surface thereof which faces said air gap (6) and opposite the magnet pole groups (3, 4) on the ferromagnetic core of the first part (1) is provided with a ring of salient ferromagnetic reluctance poles (7) which extend peripherally in said rotational direc- tion and which have a mutual pole pitch corresponding to twice the pole pitch of the magnetic poles (3, 4) on the ferromagnetic core of the first part (1); in that each of said reluctance poles (7) has a width in said peri¬ pheral direction which over a part of the reluctance pole corresponds essentially to a pole pitch of the magnet poles (3, 4) on the ferromagnetic core of the first part (1) and which over the remaining part of the pole (7) is smaller and corresponds essentially to the peripheral width of the magnetic poles (3, 4) on the ferromagnetic core of the first part (1) , in a manner such that each reluctance pole (7) presents a part (7B) which projects in a pre-determined peripheral' direction common to all reluctance poles (7) . 2. A motor according to Claim 1, characterized in that the direction of magnetization achieved by the magne¬ tizing winding (5) is opposite to the permanent magnetic polarity of the permanently magnetic poles (3) . 3. A motor according to Claim 1 or 2, characterized in that the ferromagnetic and permanently magnetic poles (3, 4) on the ferromagnetic core of the first part (1) have a width in the peripheral direction which corres¬ ponds essentially to two thirds of the pole pitch of said magnet poles. 4. A motor according to any of Claims 1-3, characterized in that the peripherally projecting part (7B) of each reluctance pole (7) has in a direction perpendicular to said mutual rotational direction an extension which corresponds to substantially half the total extension of the reluctance pole (7) in said perpendicular direction. 5. A motor according to any one of Claims 1-4, charac- terized in that said first part (1) is stationary and said second part (2) is rotatable. 6. A motor according to any one of Claims 1-5, charac- terized in that the air gap (6) is cylindrical; in that the ferromagnetic core of said first part (1) has an even number of magnetic pole groups (3, 4) of the afore¬ said kind disposed in a peripheral ring; and in that the permanently magnetic poles (3) have oppositely directed permanent magnetic polarities in mutually adjacent magnet pole groups and in that different magnetic pole groups (3,4) are embraced by different parts of the mag¬ netizing winding (5) in a manner such that mutually adjacent magnet pole groups (3, 4) are magnetized in mutually opposite directions by the magnetizing winding (5). 7. A motor according to Claim 6, characterized in that each magnet pole group (3, 4) on the first part (1) includes several, peripherally and sequentially located pairs of ferromagnetic poles (4) and a permanently magnetic pole (3); and in that all permanently magnetic poles (3) in one and the same pole group (3, 4) have the same permanent magnetic polarity. 8. A motor according to any one of Claims 1-5, charac¬ terized in that the air gap is cylindrical; in that the ferromagnetic core of the first part (1) has provided on the surface thereof facing the air gap two axially spaced and peripherally extending rings (SI, S2) of magnet pole groups (3, 4) of the aforesaid kind, in that the permanently magnetic poles (3) in the two rings (SI, S2) have oppositely directed permanent magnet polarities relative to the air gap; in that the magnetizing winding (5) comprises a coil winding which extends coaxially in relation to the air gap and which is located between said magnet pole rings (SI, S2); and in that the ferromagnetic core of the second part (2) has provided on the surface thereof facing said air gap two peripher- ally extending rings (Rl, R2) of reluctance poles (7) of the aforesaid kind located opposite the magnet pole rings (SI, S2) on the ferromagnetic core of said first part (1). 9. A motor according to any one of Claims 6-8, charac¬ terized in that each reluctance pole (7) has an axial extension which is greater than the axial extension of the magnet poles (3, 4) on the first part (1) and is configured with two parts (7B, 7C) which project peri¬ pherally in opposite directions and each of which is located on a respective axial end of the reluctance pole (7); in that the first part (1) and the second part (2) of the motor can be displaced axially in relation to one another to alternatively a first working position in which the reluctance pole parts (7B) projecting in one peripheral direction are located opposite the magnet poles (3, 4) on the first part (1), or to a second working position in which the reluctance pole parts (7C) projecting in the opposite peripheral direction are located opposite the magnet poles (3, 4) on the first part (1). 10. A motor according to any one of Claims 1-5, charac- terized in that the ferromagnetic cores of the first part (1) and the second part (2) are separated by two, annular, planar and axially spaced air gaps which are conσentrical with the mutual rotational axis of said parts and between which the ferromagnetic core of the second part (2) is located; in that said ferromagnetic core of said second part (2) is configured with a pla¬ nar, annular ring of reluctance poles (7) of the afore¬ said kind which face towards each of the two air gaps, whereas the ferromagnetic core of the first part (l) has an annular configuration with a substantially U-shaped and radially inwards open cross-section, the two legs of which U-shaped cross-section are located on opposite sides of the ferromagnetic core of the second part (2) on the opposite side of said air gaps and are each provided with a respective planar, annular ring (SI, S2) of magnet pole groups (3, 4) of said kind; in that all permanent magnet poles (3) have mutually the same axially directed permanent magnetic polarity; and in that the magnetizing winding (5) consists of a coil winding arranged concentrically in relation to the common rotational axis, inwardly of the yoke part of the U-shaped cross-section of the ferromagnetic core of said first part (1) . 11. A motor according to any one of Claims 1-10, charac¬ terized in that the motor includes a further winding (W2) which is arranged in the same manner as the mag¬ netizing winding (Wl, Fig. 11) and has the same number of winding turns as said magnetizing winding, so that equally large voltages are induced in the magnetizing winding (Wl) and the further winding (W2) in response to changes in the magnetic flux through the windings. 12. A motor according to Claim 11, characterized in that the magnetizing winding (Wl) and the further winding (W2) have a bifilar winding configuration. 13. A device for supplying a motor according to Claim 11, characterized in that the device includes a direct voltage source (U-) , a switch device (SW) which is controlled in response to the mutual angle of rotation between the two parts of said motor and which is con¬ nected in series with the magnetizing winding (Wl) of the motor between the two poles of the voltage source ( u n) ' a di o l e ( D ) connected in series with the further winding (W2) of the motor, between the poles of the voltage source (U D ) in a manner such that with respect tσ the voltages induced in the windings the magnetizing winding (Wl) and the further winding (W2) have like- polar ends connected to respective poles of the voltage source (U_) and the current direction in the diode (D) is opposite to the current direction of the switching device (SW); and further includes a capacitor (C) con¬ nected between the other ends of the two windings (Wl, W2).

Inventors: TOEROEK VILMOS, TOEROEK, VILMOS
Applicants: TOEROEK VILMOS, TOEROEK, VILMOS
Application year: 1989
Main classification: H02K19
IPC codes: H02K19, H02K21, H02K29