GB1282644A - Direct-current electric motor - Google Patents

Abstract

1282644 Electric motors PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd 29 Oct 1969 [1 Nov 1968] 53005/69 Heading H2A A P.M. rotor D.C. motor having stator windings energized in dependence on rotor position includes at least two stator windings and two Hall plates exposed to the rotor field, the Hall voltages being supplied to control transistors whose emitter electrodes are fed from a common source of substantially constant current. The motor shown has four windings 1-4 and two Hall plates 9, 10, the latter being connected to the bases of amplifying transistors 16, 17 and 26, 27, connected to control transistors 18, 19 and 28, 29 which in turn control switching transistors 21, 23 and 22, 24 connected to the windings. The common source of constant current comprising transistor 31 ensures that only one of the control transistors conducts at any given time and hence only one winding is energized at any given time. In a modification, Figs. 4, 6 (not shown), having three windings (1, 2, 3), each winding is connected in one diagonal of a respective bridge-type transistorized double change-over switch controlled by a Hall plate (e.g. 9). The windings each carry current in opposite directions at different times and two windings are energized at any given time. The control transistors (e.g. 18) for each winding are respectively connected together with the corresponding transistors in the circuits of the other windings to a common source of constant current (e.g. transistor 31). There are thus three transistorized change-over switches and four sources of constant current, one for each group of control transistors in corresponding arms of the bridge type change-over switches.