Electricity: motive power systems – Synchronous motor systems – Hysteresis or reluctance motor systems
Patent
1994-12-19
1996-05-14
Ro, Bentsu
Electricity: motive power systems
Synchronous motor systems
Hysteresis or reluctance motor systems
318254, H02K 3702, H02P 622
Patent
active
055171028
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a fault-tolerant reluctance motor, in which the stator has a different number of poles from the rotor, the stator winding formed by the coils associated with the stator poles is multi-polar, and a control device is provided which switches the individual phases on cyclically through a respective lead angle, the rotor, during normal operation, starting up from an arbitrary position selectively in one or other direction and, on the occurrence of a fault, continuing to run with reduced torque.
Reluctance motors in which a fault in the system, such as the failure of a phase winding, whether as a result of line break, short-circuiting, failure of the switch element or faults in the control system, does not lead to stopping of the motor, are known as fault-tolerant reluctance motors.
According to US-PS 48 96 089, a four-phase motor with eight stator poles and six rotor poles is designed so that on failure of a phase it still continues to run with reduced torque. Because of the missing phase, however, dead zones are created, in which the motor does not start up again in each desired direction of rotation. On the contrary, the rotor first has to be rotated in the opposite direction before it is able to run in the desired direction.
In a fault-tolerant reluctance motor of the kind described in the introduction (US-PS 48 96 088), this disadvantage is eliminated in that the phase windings do not, as is customary, consist of two series-connected and jointly switched pole coils, but of two individually switchable pole coils. When just the one pole coil is switched off on the occurrence of a fault, the other coil remaining in operation is sufficient to avoid a dead zone preventing start-up. This requires, however, twice the circuit complexity in the control device. In addition, it is frequently necessary to take the whole phase winding out of commission when a fault occurs.
The invention is based on the problem of providing a fault-tolerant reluctance motor with which, even when a fault occurs at a random location in the motor, in the control electronics for the commutation or in the sensor arrangement for measuring the rotor position, continued operation of the motor, and in particular start-up of the rotor from any position selectively in one or other direction, is possible.
This problem is solved according to the invention in that the lead angle as well as the pole angle embraced by each stator and rotor pole is at least the same as twice the step angle ##EQU2## in which q is the number of phases and N.sub.r gives the number of rotor poles.
The step angle taken here as the reference dimension describes the angle through which the rotor turns when switching from one phase configuration to the next. The pole angle measurement claimed according to the invention leads to co-ordination of at least two rotor poles with corresponding stator poles in such a way that when these stator poles are energized the rotor experiences torques in the same direction of rotation. If energizing of the one stator pole therefore fails owing to a fault, the other stator pole ensures that the rotor continues to turn with a slightly reduced torque and is even able to start up from any rotor position in the desired direction of rotation. The claimed lead angle, that is, the rotor angle of rotation during which the relevant phase winding is conductive, is of such magnitude that the desired energizing of both stator poles is possible.
Of course, the stator pole angle should not be so large that there is no longer room for the pole coil. With the theoretically smallest number of poles the motor thus has ten stator poles and four rotor poles with five phases. Since the step angle for this construction is 18.degree. however, the stator pole angle is 36.degree.. There is therefore no room left to wind the coil.
The motor that comes closest to satisfying requirements, in which the stator has ten poles, the rotor six poles and the stator winding five phases, is preferred. This produces a step angle of 12.degree. and a stator pol
REFERENCES:
patent: 4434389 (1984-02-01), Langley et al.
patent: 4896088 (1990-01-01), Jahns
patent: 4896089 (1990-01-01), Kliman et al.
patent: 5422525 (1995-06-01), Mansir
Danfoss A/S
Ro Bentsu
LandOfFree
Fault-tolerant reluctance motor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Fault-tolerant reluctance motor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fault-tolerant reluctance motor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1898524