Abstract: In a switched reluctance motor, the projected poles of a rotor have feeble-magnetic portions each having a shape that extends radially inward approximately in the rotational direction from a position relative close to a radially outer end of the projected pole and to an end of the projected pole facing in a counter-rotational direction, that is, a direction opposite to the rotational direction, or a shape that has a side extending radially inward approximately in the rotational direction from a position relatively close to a radially outer end and an counter-rotational direction-facing end of the projected pole and that extends radially inward approximately in the counter-rotational direction. The feeble-magnetic portions are weaker in magnetism than the material of the rotor and reduce the magnetic attraction force occurring at the time of switching of coil energization, thereby reducing noises while ensuring generation of a desired amount of torque.

Abstract: A switched reluctance motor includes a stator having a plurality of pairs of opposing stator pole portions which project inward in the diametrical direction and which extend in the axial direction, a rotor rotatably disposed in the stator and having a plurality of rotor pole portions which project outward in the diametrical direction and which extend in the axial direction and axis portion which is rotatably supported on a housing. A plurality of coils are wound on each of the pair of the stator pole portions and an absorbing mechanism is provided for absorbing radial vibrations of the rotor which are generated by a variation of the magnetic attracting force acting on the rotor pole portions.

Abstract: A system which energizes an SR motor with a three phase sequential and time sharing energization. Coil of respective phase is energized in an interval from an energization ON angle to an energization OFF angle. The OFF angle is advanced in reverse proportion to a speed and a target torque of a rotor of the motor in a high speed range exceeding a threshold Rbase which is an upper limit of a speed range in which a high noises is generated by a tangential oscillation of the rotor. The OFF angle is advanced in proportion to the speed of the rotor and in reverse proportion to the target torque in a low speed range under the threshold Rbase. The advance prevents the generation of noises. The system includes a compensator which corrects an energization level for accommodating an actual acceleration to a target acceleration of the rotor.

Abstract: A switched reluctance motor has a rotor disposed in an annular stator and formed mainly of a stack of iron plates. The rotor has pole protrusions that face the stator. The pole protrusions have weak magnetic portions provided therein. Each weak magnetic portion has a shape elongated from a leading outer point to a tailing inner point, or a shape that has a base side extending a leading outer point to a tailing inner point and that extends from the base side in the rotational direction and in the inward radial direction. The weak magnetic portions are formed of a material that has a weaker magnetism than the materials forming the other portions of the rotor.

Abstract: The generation of oscillations and acoustic noises which result from a rapid change in the magnetic flux upon switching the energization is suppressed, while simultaneously preventing a reduction in the driving efficiency and preventing a resonance from occurring. The current waveform as the current rises or fails is switched in accordance with the rotational speed of the SR motor to minimize a change in the magnetic flux, thus suppressing a reduction in the driving torque. A time interval required for the current to rise or fall is chosen to be greater than one-half the period of the natural frequency of SR motor.

Abstract: Suppression of a peak noise level as may be caused by a resonance when an SR motor is driven is intended. An offset is intentionally provided between a position for a maximum drive efficiency where the energization is to be switched and a position where the energization is actually switched. Such offsets s1, s2, s3, . . . are generated in terms of random numbers, producing a fluctuation in the frequency of the oscillations which result. The fluctuation in the frequency is effective to prevent the occurrence of a resonance. In order to avoid a resulting reduction in the drive efficiency, the magnitude of such offsets are limited to lie within a permissible shift angle, which is in turn determined in terms of the prevailing torque and number of revolutions, by reference to a map.