Electricity: motive power systems – Switched reluctance motor commutation control
Reexamination Certificate
2000-10-06
2001-12-25
Ip, Paul (Department: 2837)
Electricity: motive power systems
Switched reluctance motor commutation control
C318S132000, C318S434000, C318S696000, C318S685000
Reexamination Certificate
active
06333610
ABSTRACT:
FIELD OF AND BACKGROUND OF THE INVENTION
The invention concerns a speed control device for an electronically commutated multiphase electric motor. These types of speed control devices are used in combination with permanently excited electronically commutated multiphase electric motors in motor vehicles, particularly for fan drives or pump drives with a relatively small starting load moment.
U.S. Pat. No. 5,563,481 discloses a speed control device for electronically commutated multiphase electric motors with adjustable speeds, in which the pulse width of the supply voltage is modulated by means of a high frequency, inaudible 20 kHz pulse. U.S. Pat. No. 5,589,745 discloses a second speed control device which provides pulse width modulation of the supply voltage by means of a drive circuit with pulse groups that can be adjusted with respect to amplitude and/or duration. However, these known speed control devices require complex hardware and/or expensive software.
British Laid-Open Publication GB-OS 1 563 015 (which corresponds to German Laid Open Publication 26 39 055 B2), U.S. Pat. Nos. 4,283,664, and 3,769,555 disclose speed control devices for electronically commutated electric motors having motor phases that can be powered unidirectionally and unpulsed during definable time blocks by phase shifters from a constant voltage supply, depending on rotor position sensor signals, thereby creating torque.
For the device of GB-OS 1 563 015, various speeds can be achieved by the assignment of definite pulse patterns to defined speeds. U.S. Pat. No. 4,283,664 provides for setting various speeds by adjustment of the constant voltage supply source. U.S. Pat. No. 3,769,555 permits the setting of various speeds by means of a pulse generator that adjusts pulse width and pulse frequency.
OBJECTS OF THE INVENTION
According to one object of the present invention, it is sought to provide a variable-speed drive with speeds that can be set as desired, which device can be made at a significantly lower hardware and software expense, while still completely satisfying the required operating conditions.
SUMMARY OF THE INVENTION
According to one formulation, the present invention is directed to a speed control device that requires less expensive components by applying a unidirectional, unpulsed supply to each of the motor phases, via only one simple, in particular transistorized, phase shifter. Preferably, the phase shifter is connected directly with its neutral side to one terminal of the constant voltage supply. By alternating switching between two (or more) time block pulse patterns, which are assigned respectively to different motor speeds, intermediate speeds can easily be achieved by switching between different time blocks at a switching frequency, that is below audible frequencies. This switching frequency is determined according to the length of the time block and/or the moment of switching. Moreover, this switching frequency is dependent only on the mechanical time constants of the drive system, with a view to ensuring a non-jerking rotational speed setting. The switching losses can thereby be significantly reduced relative to prior art speed control devices employing high frequency pulse width modulation.
REFERENCES:
patent: 3769555 (1973-10-01), Dolbachian et al.
patent: 4093905 (1978-06-01), von Braun
patent: 4283664 (1981-08-01), Ebert
patent: 4888533 (1989-12-01), Gotoh et al.
patent: 5783891 (1998-07-01), Auinger et al.
patent: 5886486 (1999-03-01), Jeong et al.
patent: 6201322 (2001-03-01), Heine et al.
patent: 24 03 432 A (1975-07-01), None
patent: 26 39 055 B2 (1977-03-01), None
patent: 196 30 036 A (1998-01-01), None
patent: 1 563 015 (1980-03-01), None
Meschik Martin
Schermann Markus
Ip Paul
Siemens Aktiengesellschaft
Sughrue & Mion, PLLC
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