Electrical angle-detecting apparatus and driving system of synch

Details Electrical angle-detecting apparatus and driving system of synch Electrical angle-detecting apparatus and driving system of synch

1994-10-24

1997-03-04

Ro, Bentsu

Electricity: motive power systems

Synchronous motor systems

Armature winding circuits

318254, H02P 616

Patent

active

056083009

ABSTRACT:
The present invention provides a system for detecting a rotational orientation or electrical angle of a rotor without any specific sensor so as to efficiently control a synchronous motor even while the rotor is at a stop or rotates at a relatively low speed. An electrical angle of a rotor (50) is determined according to a previously stored relationship between inductances of different interphases and electrical angles. At a first step, an electrical angle .phi. is calculated either in a range of 0 through .pi. or in a range of .pi. through 2.pi. by approximation. At a second step, a range where the electrical angle .phi. belongs to is specified by taking advantage of asymmetrical property of a maximum current in response to a voltage applied to each interphase. An equivocal electrical angle .theta. is then determined in a range of 0 through 2.pi.. In order to control the driving current of a three-phase synchronous motor (40) at better efficiency, a preferable system of the invention determines the electrical angle according to the above method while the rotor (50) is under inactivating condition or rotates at a speed of less than a predetermined rotating speed, and detects the electrical angle with a reverse electromotive voltage while the rotor (50) rotates at a speed of not less than the predetermined rotating speed.

REFERENCES:
patent: 5028852 (1991-07-01), Dunfield
patent: 5117165 (1992-05-01), Cassat et al.
patent: 5280222 (1994-01-01), von der Heide et al.

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