Electricity: motive power systems – Synchronous motor systems – Hysteresis or reluctance motor systems
Patent
1991-04-02
1992-08-11
Shoop, Jr., William M.
Electricity: motive power systems
Synchronous motor systems
Hysteresis or reluctance motor systems
318254, H02P 602
Patent
active
051382440
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention is related to a reluctance-type electric motor which is used for the drive source of industrial equipment as a highly efficient D.C. motor having a large output torque and small torque ripple, and which is particularly effective when used as a servo motor.
BACKGROUND OF THE INVENTION
Traditionally, the number of phases cannot be made as large in a reluctance-type motor as in a typical commutator motor. This is because practicability is lost since the cost of the semiconductor circuit of each phase is high.
Accordingly, the stored magnetic energy of each magnetic pole becomes large and it takes time to discharge and store. Thus there is a problem that the torque becomes high but the speed does not.
Further, particularly in a reluctance-type motor having a large output torque, the number of magnetic poles of the armature becomes large and the air-gap of the magnetic path thereof is small, so that the stored magnetic energy is large, whereby the above-mentioned inconvenience is accelerated.
The higher the torque, the more impossible the solution to this problem.
Next, because of the large inductance of armature coils, there is a problem that the rise and fall times of the armature current increase thereby making the ripple of the output torque large.
Moreover, there is a problem that an efficiency is also degraded.
Accordingly, it is the object of this invention to provide a reluctance-type motor which is high-speed, highly efficient, small-sized and inexpensive.
SUMMARY OF THE INVENTION
This invention compress a two-phase reluctance-type motor in which, when the armature coils of each phase are energized with a fixed current, the torque becomes maximum in the vicinity of an electrical angle of 10 to 20 degrees since the salient poles of the rotor start to enter the magnetic poles and thereafter a flat torque is obtained only for a predetermined section. This reluctance-type motor in which the ripple torque has been removed comprises a position detecting unit including position detecting elements for detecting positions of salient poles by which first, second, third and fourth single-phase position detecting signals are obtained in which there are disposed continuous position detecting signals having an electrical angle having a width of 90 degrees that are not superposed in time, semiconductor switching elements connected to both ends of 1st, 1st, 2nd and 2nd armature coils when the armature coils of a 1st and 2nd phase are formed into 1st and 1st armature coils and 2nd and 2nd armature coils, respectively, diodes which are reversely connected to the series connecting body of the respective semiconductor switching elements and the armature coils, energization control circuit which makes the semiconductor switching elements conductive by means of the 1st, 2nd, 3rd and 4th position detecting signals to energize the 1st, 2nd, 1st and 2nd armature coils, thereby generating an output torque in one direction, a d.c. power supply for supplying power to the energization control circuit via one diode forwardly inserted in the positive or negative electrode side of the power supply, means for adjusting the fixing positions of the position detecting elements to initiate the energization of each the armature coil from the vicinity where the torque becomes maximum, a chopper circuit for holding the armature current at a preset value, and an electric circuit which, when the armature coil is controlled for energization by a position detecting signal is de-energized at the end of the position detecting signal, prevents the magnetic energy stored in the armature coil from being fed back to the D.C. power supply via the reversely connected diodes by means of the one diode forwardly inserted in the power supply side, and converts the magnetic energy to the stored magnetic energy of the armature coil to be energized next, thereby making the rise and fall of the armature current rapid.
This invention further comprises a three-phase reluctance-type motor in which when the armature coil
REFERENCES:
patent: 4282464 (1981-08-01), Uzuka
patent: 4670696 (1987-06-01), Byrne et al.
patent: 4698537 (1987-10-01), Byrne et al.
patent: 4739203 (1988-04-01), Miyao et al.
patent: 4739240 (1988-04-01), MacMinn et al.
Cabeca John W.
Kabushikigaisha Sekogiken
Shoop Jr. William M.
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