SWITCHED RELUCTANCE MOTOR AND METHOD THEREFORE

Abstract

The invention involves a switched reluctance motor, comprising a stator and a rotor rotatable relative to the stator. The stator comprises several circumferentially arranged coils and stator poles, the stator poles forming the cores of the coils. The rotor comprises several counter poles for interacting with the stator poles for applying a reluctance torque on the rotor. The motor comprises phase inputs for receiving an actuation signal for actuating one or more phase stages. Each stator coil is associated with a phase stage, such that each phase stage comprises at least two coils. Each phase stage comprises a circuit stage including a switching arrangement comprising switches for selectively switching the coils of said phase stage in either one of a parallel, a serial, or a parallel-serial electrical configuration.

Claims

1. Switched reluctance motor, comprising a stator and a rotor, the rotor being rotatable relative to the stator, wherein the stator comprises a plurality of coils and stator poles arranged circumferentially around the rotor, the stator poles forming the cores of the coils, and wherein the rotor comprises a plurality of counter poles for interacting with the stator poles of the stator for applying a reluctance torque on the rotor, wherein the motor comprises one or more phase inputs for receiving an actuation signal for actuating a respective phase stage of one or more phase stages of the motor for powering of the one or more phase stages in accordance with a repetition pattern of a powering sequence, wherein each coil of the plurality of coils of the stator is associated with one said phase stage of the motor such that each phase stage comprises at least two of the coils, and wherein each phase stage comprises a circuit stage including a switching arrangement comprising a plurality of switches for selectively switching the coils associated with said phase stage in either one of a parallel, a serial, or a parallel-serial electrical configuration; wherein the switches include mechanical switches or electro-mechanical switches, and wherein the motor further includes a controller configured for obtaining data indicative of an operational condition of the motor and for operating the switches of each phase stage dependent on the operational condition of the motor, further configured for performing the switching of each phase stage by inactivating during an interruption the powering of the respective phase stage for a plurality of cycles of the repetition pattern of the powering sequence.

2. Switched reluctance motor according to claim 1, wherein in said serial-parallel electrical configuration, the phase stage comprises at least three coils, wherein at least two coils of said phase stage are electrically operated in a serial configuration with respect to each other, and wherein at least two of said coils of said phase stage are electrically operated in a parallel configuration with respect to each other.

3. Switched reluctance motor according to claim 1, wherein the data indicative of the operational condition of the motor is obtained by at least one of a group comprising: a sensor unit providing a sensor signal; said controller or an additional controller unit being arranged for providing said data based on a calculation, wherein the operational condition comprises at least one element of a group comprising: a rotational speed of the rotor, an output power requirement of the motor, sound or sound volume produced by the motor, efficiency of an input power supplied to the motor with respect to the output power delivered by the motor.

4. Switched reluctance motor according to claim 3, wherein the controller is arranged for at least one of: switching the coils of each phase stage such as to operate the phase stage in a serial configuration of the coils when the data indicates the operational condition having a value smaller than a first threshold; or switching the coils of each phase stage such as to operate the phase stage in a parallel configuration of the coils when the data indicates the operational condition having a value larger than a second threshold.

5. Switched reluctance motor according to claim 4, wherein the second threshold is larger than or equal to the first threshold; and wherein the controller is arranged for switching the coils of each phase stage such as to operate the phase stage in a parallel-serial configuration of the coils when the data indicates the operational condition having a value between the first and second threshold, when the second threshold is larger than the first threshold.

6. Switched reluctance motor according to claim 3, wherein the controller is arranged for switching the coils of each phase stage such as to switch from a first of said electrical configurations to a second of said electrical configurations dependent on a direction of change of said operational condition of the motor, wherein on a decrease of the value of the operational condition the switching is performed when the data indicates the operational condition having a value smaller than a third threshold, and on an increase of the value of the operational condition the switching is performed when the data indicates the operational condition having a value larger than a fourth threshold; the fourth threshold being larger than the third threshold.

7. Switched reluctance motor according to claim 1, wherein the controller is configured for switching and interrupting of at least two phase stages during simultaneous interruptions.

8. Switched reluctance motor according to claim 1, wherein the controller is configured for switching and interrupting of at least two phase stages during sequential interruptions.

9. Apparatus comprising a switched reluctance motor in accordance with claim 1, wherein said apparatus is vehicle.

10. Method of operating a switched reluctance motor, the motor comprising a stator and a rotor, the rotor being rotatable relative to the stator, wherein the stator comprises a plurality of coils and stator poles arranged circumferentially around the rotor, the stator poles forming the cores of the coils, and wherein the rotor comprises a plurality of counter poles for interacting with the stator poles of the stator for applying a reluctance torque on the rotor, wherein the motor comprises one or more phase inputs and one or more phase stages, each phase input connected to a respective phase stage, wherein each coil of the plurality of coils of the stator is associated with one said phase stage of the motor such that each phase stage comprises at least two of the coils, the method including: receiving through at least one of said phase inputs an actuation signal for actuating said respective phase stage, and applying the actuation signal to the phase stage such as to actuate the rotor via the stator poles of said phase stage for powering of the one or more phase stages in accordance with a repetition pattern of a powering sequence; operating, during said actuating of the rotor, a switching arrangement of each phase stage comprising a plurality of switches, such as to selectively switch the coils associated with said phase stage in either one of a parallel, a serial, or a parallel-serial electrical configuration, the switches including mechanical switches or electro-mechanical switches; obtaining, by a controller, data indicative of an operational condition of the motor; and operating, by the controller, the switches of each phase stage dependent on the operational condition of the motor, wherein the switching of each phase stage is performed by inactivating during an interruption the powering of the respective phase stage for a plurality of cycles of the repetition pattern of the powering sequence.

11. Method according to claim 10, further including: obtaining, using a sensor unit, a sensor signal indicative of an operational condition of the motor, and providing the sensor signal to a controller; operating, by the controller, the switches of each phase stage dependent on the sensor signal.

12. Method according to claim 11, wherein the operational condition for which the sensor signal is indicative comprises at least one element of a group comprising: a rotational speed of the rotor, an output power requirement of the motor, sound or sound volume produced by the motor, efficiency of an input power supplied to the motor with respect to the output power delivered by the motor.

13. Method according to claim 11, wherein the controller operates the switches such as to: switch the coils of each phase stage such as to operate the phase stage in a serial configuration of the coils when the sensor signal indicates the operational condition having a value smaller than a first threshold; switch the coils of each phase stage such as to operate the phase stage in a parallel configuration of the coils when the sensor signal indicates the operational condition having a value larger than a second threshold; and switch the coils of each phase stage such as to operate the phase stage in a parallel-serial configuration of the coils when the sensor signal indicates the operational condition having a value between the first and second threshold.

14. Method according to claim 10, wherein the switching and interrupting by the controller is performed for at least two phase stages during simultaneous interruptions.

15. Method according to claim 10, wherein the switching and interrupting by the controller is performed for at least two phase stages during simultaneous interruptions.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The invention will further be elucidated by description of some specific embodiments thereof, making reference to the attached drawings. The detailed description provides examples of possible implementations of the invention, but is not to be regarded as describing the only embodiments falling under the scope. The scope of the invention is defined in the claims, and the description is to be regarded as illustrative without being restrictive on the invention. In the drawings:

[0030] FIG. 1 schematically illustrates a switch reluctance motor in accordance with the present invention;

[0031] FIG. 2A and FIG. 2B schematically illustrate the electric configuration of the coils of one phase stage of a switch reluctance motor in accordance with the present invention in different switching states;

[0032] FIG. 3 schematically illustrates a further electric configuration of coils in a phase stage of a switched reluctance motor in accordance with the present invention;

[0033] FIG. 4 schematically illustrates a further electric configuration of the coils of a phase stage of a switched reluctance motor in accordance with the present invention;

[0034] FIG. 5 illustrates the powering diagrams of various phase stages of a switch reluctance motor in accordance with the present invention;

[0035] FIG. 6 illustrates an alternative possible powering diagram of the phase stages of switch reluctance motor in accordance with the present invention;

[0036] FIG. 7 schematically illustrates a further alternative powering diagram of the phase stages of a switch reluctance motor of the present invention;

[0037] FIG. 8 schematically illustrates a further alternative powering diagram of the various phase stages of a switch reluctance motor in accordance with the present invention;

[0038] FIG. 9 is a schematic torque-speed diagram for a switched reluctance motor in accordance with the present invention.

DETAILED DESCRIPTION

[0039] The figures include a large number of reference signs indicating various components, parts and/or aspects of the embodiments that are schematically illustrated. In addition, reference is made to various phase stages by referring to a phase stage number illustrated as a black dot with a number, i.e. phase stages , , , and . These phase stage numbers are not to be mistaken for the reference numerals (which include for example the motor 1, the stator 2 or the rotor 3). Therefore, the notation of the phase stage numbers , , , and is used accordingly in the description to identify the phase stages, whereas the reference numerals to the motor, stator and rotor are provided as regular numbers.

[0040] FIG. 1 schematically illustrates a switched reluctance motor in accordance with the present invention. The switched reluctance motor 1 comprises a stator 2 and a rotor 3. The rotor 3 is rotatable with respect to the stator 2, for example by suspending the rotor 3 using suitable bearings (not shown) with respect to the fixed parts of the motor. The rotatable rotor 3 comprises a central part 15 and a plurality of salient poles 16. The poles 16 are electrically passive in a sense that the poles 16 do not form the cores of (or interact with) coils on the rotor 3. The stator 2 comprises a circumferential part 4 and a plurality of salient poles 6-n, 8-n, 10-n and 12-n (wherein n is indicative of a specific coil in each phase stage, to be explained). Each pole on the stator 2 forms the core of a respective coil of the switched reluctance motor 1. The switched reluctance motor 1 comprises a plurality of coils that are divided into different groups. In the embodiment illustrated in FIG. 1, a total of 16 coils is divided into four groups. These groups are indicated as phase stages. In the embodiment of FIG. 1, a first phase stage comprises the coils 5-1, 5-2, 5-3, and 5-4. In phase stage coil 5-1 is wound enclosing pole 6-1 forming the core thereof. Coil 5-2 comprises pole 6-2 as its core. Coil 5-3 comprises pole 6-3 as its core, and coil 5-4 comprises pole 6-4 as its core. Likewise, the coils of phase stage comprise coils 7-1, 7-2, 7-3 and 7-4 which respectively enclose the poles 8-1, 8-2, 8-3 and 8-4 as their cores. Phase stage comprises coils 9-1, 9-2, 9-3 and 9-4 which are wound such as to enclose respectively the poles 10-1, 10-2, 10-3 and 10-4. Lastly, phase stage comprises coils 11-1, 11-2, 11-3 and 11-4 respectively enclosing poles 12-1, 12-2, 12-3 and 12-4 as their cores.

[0041] Typically in a switched reluctance motor, the number of poles on the stator 2 is different from the number of poles on the rotor 3. In FIG. 1, the stator 2 comprises sixteen poles (6-n, 8-n, 10-n, and 12-n where n=1, 2, 3, 4). The rotor 3 comprises only twelve salient poles 16 circumferentially arranged around the central part 15. In this configuration, only the poles 6-1, 6-2, 6-3 and 6-4 of the first phase stage are nicely aligned with some poles 16 of the rotor 3. The poles of each of the other phase stages , , and are not aligned with any of the salient poles 16 of the rotor 3.

[0042] As will be appreciated, in case the coils of any of the phase stages , , or would be powered by providing an electric current to the respective coils, the rotor poles 16 will experience a force that will pull the rotor towards a position wherein each of the poles of the activated coils is aligned with one of the poles 16 of the rotor 3. In the situation illustrated in FIG. 1, the poles 6-n of phase stage are aligned with some of the poles 16 of the rotor 3. Therefore, activating the coils 5-n of phase stage will not result in a rotation of the rotor 3. However, in case the coils 7-n of phase stage will be powered by means of an electric current, instead of the coils of phase stage , the rotor 3 will rotate until the poles 8-1, 8-2, 8-3 and 8-4 are aligned with some of the poles 16 on the rotor. As will be appreciated, the poles 8-n (n=1, 2, 3, 4) will align with the rotor poles 16 that are most nearby in the situation illustrated in FIG. 1.

[0043] Next, if subsequently the coils 7-n of phase stage are no longer powered, and instead the coils 9-1, 9-2, 9-3 and 9-4 of phase stage are powered with an electric current, the rotor 3 will again experience a torque that will keep the rotor 3 rotating in the clockwise direction. Subsequently, the coils 9-n are no longer powered and the coils 11-1, 11-2, 11-3 and 11-4 of phase stage are powered to keep the rotor 3 rotating. As will be appreciated, by subsequently activating the coils of phase stages , , and , and repeating this activation pattern, the switch reluctance motor 1 can be operated. In FIG. 1, the switch reluctance motor 1 is illustrated comprising a rotor 3 rotating inside a stator 2. As will be appreciated, alternatively, the stator may also be located on the inside and the rotor on the outside (circumferentially around the stator) in a rotatable manner.

[0044] In accordance with the present invention, to operate to coils 5-1, 5-2, 5-3 and 5-4 of the first phase stage , an electric configuration in accordance with a first embodiment of the invention is illustrated in FIGS. 2A and 2B. In FIG. 2A, the configuration is illustrated including switches S1-S6 in a first switching position such as to obtain a parallel electric configuration of the coils 5-n. The configuration illustrated in FIGS. 2A and 2B comprises the coils 5-1, 5-2, 5-3 and 5-4, as well as a plurality of switches S1 20, S2 22, S3 24, S4 26, S5 28 and S6 30. Connection of terminals 31 and 32 allow to connect the phase stage to a power supply. The power supply may be a current source or any other suitable type of power supply that allows to regulate the current provided to the coils 5-n.

[0045] In the situation of FIG. 2A, the switches 20, 22 and 24 (S1, S2 and S3) are in a closed position. The switches 26, 28 and 30 (S4, S5 and S6) respectively connect coils 5-1, 5-2 and 5-3 with connection terminal 32. In this configuration, as follows from FIG. 2A, the coils 5-1, 5-2, 5-3 and 5-4 between the connection terminals 31 and 32 are arranged in an electrically parallel configuration.

[0046] In the situation of FIG. 2B, switches 20, 22 and 24 (S1, S2 and S3) are in an open position, while switches 26, 28 and 30 (S4, S5 and S6) respectively connect coil 5-1 with coil 5-2, coil 5-2 with coil 5-3, and coil 5-3 with coil 5-4. Therefore, in situation illustrated in FIG. 2, the coils are in a serial electric configuration with respect to the connection terminals 31 and 32.

[0047] As will be appreciated, if a current is applied between the connection terminals 31 and 32, in the parallel configuration of FIG. 2A. This current is divided between the coils 5-1, 5-2, 5-3 and 5-4. Therefore, each coil only receives part of the current which is applied between the connection terminals 31 and 32. On the other hand, in the situation of FIG. 2B, where the coils 5-n are in a serial electric configuration with respect to the connection terminals 31 and 32, the full current applied between the connection terminals 31 and 32 is received by each coil 5-1, 5-2, 5-3 and 5-4. The magnetic field generated by each coil is dependent on the electric current flowing through the coil. Therefore, in the parallel situation of FIG. 2A, the magnetic field provided by each of the coils 5-1 through 5-4 is smaller than in the serial electric configuration of FIG. 2B (wherein the electric current is much larger through each coil). However at the same time, at the parallel configuration of FIG. 2A the voltage across each of the coils 5-1, 5-2, 5-3 and 5-4 is much larger than in the situation of FIG. 2B. In the serial configuration of FIG. 2B, the voltage across each of the coils 5-1 through 5-4 is divided over the coils. As a result of these differences, due to the large magnetic field obtainable in the situation of FIG. 2B, in the serial configuration of FIG. 2B the powering of the coils 5-n enable to apply a large substantial torque onto the rotor 3 of FIG. 1. As described before, the maximum torque that can be applied is naturally limited by the available voltage and maximum allowed phase current. At relatively low speeds, the torque is limited by the maximum allowed phase current; at higher speeds, due to the increasing back-emf and decreasing commutation time (as the rotor speed increases), maximum phase current can't be forced in the phase stage anymore. Maximum phase current and thus torque drops gradually as the speed increases. For the serial configuration in FIG. 2B, although the torque that can be applied at low speeds will be higher, the influence of back-emf and decreasing commutation time at higher speeds are more severe than in the parallel configuration of FIG. 2A. Therefore, as also follows for example from curves 80 (for serial) and 84 (for parallel) in FIG. 9, the amount of torque that can be applied at higher speeds will be lower for the serial configuration of FIG. 2A in comparison to the parallel configuration of FIG. 2B, ceterus paribus.

[0048] A further electric configuration of the coils 5-n of the first phase stage is illustrated in FIG. 3. In the configuration of FIG. 3 the switches of S1 through S6, respectively switch 40, 42, 44, 46, 48 and 50 are in a switching arrangement such that the coils 5-1, 5-2, 5-3 and 5-4 are in a electric serial configuration. However, by switching switch 40 (S1) into position ‘1’ while also switching switch (S5) 48 into position ‘1’, a configuration is obtained wherein coils 5-1 and 5-2 are serial with respect to each other while at the same time coils 5-3 and 5-4 are serial with respect to each other, but these pairs of coils (on one hand coils 5-1 and 5-2 and on the other hand coils 5-3 and 5-4) are parallel with respect to each other. Therefore, this switching arrangement wherein switches 40 and 48 (S1 and S5) are in position ‘1’ while all other switches 42, 44, 46 and 50 are in switching position ‘0’, is a hybrid configuration indicative as serial/parallel configuration. Moreover, the full parallel configuration wherein all of the coils 5-1 through 5-4 are parallel with respect to each other is achieved by switching all of the switches 40, 42, 44, 46, 48 and 50 into position ‘1’. The serial configuration is obtained by switching all of the switches 40, 42, 44, 46, 48, and 50 into position ‘0’. As a result, the configuration illustrated in FIG. 3 allows a serial mode, a parallel mode and a serial/parallel mode. In addition to what has been explained above for the serial mode and for the parallel mode, the behavior of the maximum torque that may be applied at a given speed in the serial/parallel mode is somewhere in between the behavior of the maximum torque that can be applied at that given speed in the serial mode and in the parallel mode. This results in a torque-speed curve for serial-parallel configuration such as is exemplarily illustrated by curve 82 in FIG. 9. Therefore the configuration of FIG. 3 provides an advantageous electrical configuration for three different rotation speeds. Low speed (serial, intermediate speed (serial/parallel) and high speed (parallel)). A further alternative electric configuration is illustrated in FIG. 4. In the illustration of FIG. 4 between the connection terminals 64 and 65 coils 5-1 and 5-2 are always serial with respect to each other. At the same time, coils 5-3 and 5-4 are also always serial with respect to each other. However, by selectively switching switch 60 (S1) and switch 62 (S2) in either position ‘0’ or ‘1’, either the serial mode or the serial/parallel mode can be obtained.

[0049] As will be appreciated, the electric configuration of each phase stage , , and may preferably be the same for the switched reluctance motor. Selectively, dependent on the speed of the rotor, the configuration may be switched into a serial mode, a parallel mode, or a serial/parallel mode. Although FIGS. 2A, 2B, 3 and 4 provide the schematic electric configuration for phase stage , the circuitry for the other phase stages , , will be kept the same as that for group . The switches applied for switching the electric configuration could be of any desired type. However, the skilled person will understand that different types of switches each have their own advantages and disadvantages that will render them suitable or unsuitable in certain applications. For example, electro-mechanical switches may be relatively inexpensive, while still fast enough to perform switching in a number of situations. At the same time, such electro-mechanical switches are prone to wear and require maintenance while the switching itself cannot be performed very fast. On the other hand, semiconductor based switches such as transistor type switches allow very fast switching during operation of the respective phase stages , , and , even without having to interrupt activation of the coils. However semiconductor based switches are more expensive than mechanical switches.

[0050] FIG. 5 schematically illustrates a power diagram for powering the coils of each of the phase stages , , and . Horizontally, the diagram indicates the repetition pattern of the powering sequence. During each cycle, the coils of each phase stage , , and will be powered for a brief moment 70, and will not be powered in the meantime during period 71 (as indicated for phase stage ). As follows from FIG. 5, the applied phase current will always be in a same direction through the phase stage when the phase stage is powered during periods 70, and no current is applied during the periods 71 wherein the phase stages are not powered. However, as follows from the diagram of FIG. 5, the powering of each of the phase stages , , , is performed sequentially starting with phase stage , followed by , and . Using semiconductor switches in the configurations illustrated in FIGS. 2A, 2B, 3 and 4, the switching can be performed sufficiently fast such that the powering of the coils does not have to be interrupted. For example, each of the phase stages , , , and can be switched into a different mode (serial, parallel, serial/parallel) during the inactive period 71. Therefore, the switching of the electric configuration into a different mode can be performed during a single cycle, such that all phase stages operate in the same electric configuration in the next cycle.

[0051] If, alternatively, switches are used that do not allow the switching to be performed very fast, for example mechanical switches or electro-mechanical switches, the switching towards a different electrical mode can be performed in a different manner. Various alternative switching methods are illustrated in FIGS. 6, 7 and 8 respectively. In FIG. 6, the powering of the coils in each phase stage , , and must be interrupted for a number of cycles to allow switching of the electric circuitry into the correct mode of operation. This is performed during the interruption indicated by periods 75, 76, 77 and 78 in FIG. 6. After having switched the electric circuitry into the desired configuration, the sequential powering of the different phase stages , , and continues.

[0052] In FIG. 7, each of the phase stages , , and is temporarily inactivated during the switching of this phase stage into the new electric configuration desired. Therefore, the inactive period 75 for switching phase stage is followed by an inactive period 76 for switching , which is followed by an inactive period 77 for and an inactive period 78 for . As a further alternative, as illustrated in FIG. 8, phase stages and are simultaneously switched into a new electric configuration during simultaneous inactive periods 75 and 77, while phase stages and are thereafter switched into the new electric configuration during inactive periods 76 and 78. The skilled person will appreciate that the manner of switching the phase stages , , and is not limited by the specific methods illustrated in FIGS. 5-8, but can be performed in any other desired manner.

[0053] FIG. 9 illustrates a schematic torque-speed representation that may be obtained by a switch reluctance motor in accordance with the present invention. The diagram of FIG. 9 illustrates the torque-speed characteristic 80 obtainable in the serial mode (S). As can be seen, a very high amount of torque (T) can be obtained at low speed, but this amount of torque quickly drops with increasing speed. A further torque-speed characteristic for the serial parallel mode is indicated by 82 (S/P). Here, the maximum amount of torque (T/2) obtainable is less than the torque that is obtainable in the serial mode (note that T/2 is used here as an exemplary value, but is not to be considered as characteristic or typical for a serial-parallel mode as compared to a serial mode in general), but a fair amount of torque can be maintained much longer at higher speeds. The torque-speed characteristic in the parallel mode is indicated with the reference numeral 84. A maximum amount of torque available in this configuration at low speed is only a quarter of that in the serial configuration (T/4) (again also here, note that T/4 is used here as an exemplary value, but is not to be considered as characteristic or typical for a parallel mode as compared to a serial mode in general). However, the amount of torque can be maintained much longer at higher speeds in comparison with the serial configuration and the serial-parallel configuration. Therefore, if switching between the various electric mode serial, serial/parallel and parallel is performed at suitably chosen velocities, the maximum amount of torque obtainable dependent on the velocity of the rotor is indicated by the envelope curve 88. In reality, the amount of torque applied at each speed may be different from that indicated by curve 88. For example, also the efficiency of the switched reluctance motor or the amount of sound produced by the motor at various speeds will be decisive for choosing the correct electric configuration.

[0054] The present invention has been described in terms of some specific embodiments thereof. It will be appreciated that the embodiments shown in the drawings and described herein are intended for illustrated purposes only and are not by any manner or means intended to be restrictive on the invention. It is believed that the operation and construction of the present invention will be apparent from the foregoing description and drawings appended thereto. It will be clear to the skilled person that the invention is not limited to any embodiment herein described and that modifications are possible which should be considered within the scope of the appended claims. Also kinematic inversions are considered inherently disclosed and to be within the scope of the invention. In the claims, any reference signs shall not be construed as limiting the claim. The term ‘comprising’ and ‘including’ when used in this description or the appended claims should not be construed in an exclusive or exhaustive sense but rather in an inclusive sense. Thus the expression ‘comprising’ as used herein does not exclude the presence of other elements or steps in addition to those listed in any claim. Furthermore, the words ‘a’ and ‘an’ shall not be construed as limited to ‘only one’, but instead are used to mean ‘at least one’, and do not exclude a plurality. Features that are not specifically or explicitly described or claimed may be additionally included in the structure of the invention within its scope. Expressions such as: “means for . . . ” should be read as: “component configured for . . . ” or “member constructed to . . . ” and should be construed to include equivalents for the structures disclosed. The use of expressions like: “critical”, “preferred”, “especially preferred” etc. is not intended to limit the invention.

[0055] The invention may be applied in single phase or multiphase switched reluctance motors, and is not limited to any particular number of phase stages. Additions, deletions, and modifications within the purview of the skilled person may generally be made without departing from the spirit and scope of the invention, as is determined by the claims. The invention may be practiced otherwise then as specifically described herein, and is only limited by the appended claims.