Electric driving device

摘要

1,141,414. Electric motors. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. 11 Sept., 1967 [14 Sept., 1966], No. 41330/67. Heading H2A. [Also in Division G1] The current through the stator windings of a commutatorless electric motor is switched by electronic switches controlled on starting by an auxiliary photo-electric arrangement including a light source which is extinguished when the induced e.m.f. in the stator windings reaches a predetermined value which is sufficient to directly control the electronic switches. The motor has a polarized rotor and a stator having at least two stator windings and operates from a D.C. source. As shown, stator windings 1, 2 are supplied from D.C. source 4 through transistor switches 5, 6 which are rendered conducting alternately by the e.m.f. induced in the non- energized stator winding. On starting when no induced e.m.f. is present screen 12, rotating with the permanent magnet rotor, allows light sensitive resistors 9, 10 to be illuminated alternately from lamp 8 to operate switches 5, 6. When the rotor is running the induced e.m.f. charges capacitor 30 through diode 29 until it counteracts the forward bias on transistor 25 and renders it non-conducting to switch off lamp 8. Alternatively the lamp is connected in series with the stator windings so that after the motor has started the voltage drop across the lamp reduces to less than its operating voltage and it is extinguished. A motor having three stator windings connected 120 degrees elect. apart and using phototransistors to control the electronic switches is also described, Fig. 2 (not shown).