GB1245687A - Electric motor propulsion system - Google Patents

Abstract

1,245,687. Linear motors. MERLIN GERIN. 4 June, 1969 [14 June, 1968], No. 28146/69. Heading H2A. In a propulsion system for a number of independent vehicles, e.g. trucks of a conveyer, each having an armature 14, Fig. 4, co-operating with the stator 10 of a linear induction motor carrying a polyphase winding, the winding is divided into a number of electrically separate reactors 16, 16<SP>1</SP>, 16<SP>11</SP> which are cyclically connected to the supply 24, e.g. by sets of diodes such as 18, 18<SP>1</SP>, 18<SP>11</SP> so as to produce a travelling field having zones in each of which the field is of varying strength so as to retain an armature 14 within a zone. In this way, an armature tends to travel in the portion of a zone appropriate to the load in its associated truck. If the truck tends to slow down, the armature enters a portion of the zone of greater field strength and vice versa. Collisions are thus avoided. The varying field may be produced by varying the pole pitch of each winding section or varying the supply frequency or voltage. Fig. 5 shows a waveform produced by varying the supply voltage in which each zone comprises three steps. Alternatively, two steps only may be provided or a sawtooth waveform, Fig. 7 (not shown). Control of the rectifiers in Fig. 4 may be governed by selective switching means and a proximity detector for the armatures so that only the winding sections adjacent the armatures are energized.