| 摘要 |
1,228,866. Electric motors; inverting. TOKYO SHIBAURA ELECTRIC CO. Ltd. 9 May, 1968 [15 May, 1967], No. 22060/68. Headings H2A and H2F. A brushless D.C. motor has bridge-connected main thyristors 11-16 connected in pairs to motor windings U, V, W so that thyristors 11- 13 control the supply to the winding from the positive supply 41 and thyristors 14-16 the supply from negative supply 42. Main thyristors 11-16 are made to conduct in accordance with rotor position, sensed by sensor 33, under the control of gate control 34 to provide a synchronous torque on rotor 32. Each main thyristor conducts for 120 degrees and is switched off by providing an opposite polarity voltage pulse by connecting voltage source 36 into the circuit and short-circuiting the commutated winding through diode bridge 21-26. In operation, to forcibly quench positive side main thyristors 11-13, switching circuit 37, which includes a transistor or thyristor, is switched on to apply voltage V A to point 43 to turn off the respective main thyristor and thyristor 18 is made conductive to allow the stored energy in the windings to be dissipated through diodes 24-26 and help to turn the thyristor off. In the case of a negative side main thyristor, the thyristor 17 is made to conduct at the same time as circuit 37 by means of pulses from gate control 34. Reactor 35 is included in the supply circuit so that an effective constant current source is obtained. |
