Electric drive unit for trolley bus - has free running diode and nonlinear resistance providing rapid energising path for acceleration during gear changing

摘要

The compact electric drive unit for a trolley bus uses a DC motor with a controlled free-running diode connected in parallel across its field winding and with a starting resistance connected in the armature circuit during start-up. The braking circuit includes the armature, a mechanical switch, a thyristor and a braking resistance. Neither the thyristor or the free-running diode has an extinction circuit, but a second free-running diode and a non-linear resistance are coupled in parallel across the latter. The controlled free-running diode can be extinguished by a short firing of a DC regulator so that the second free-running diode and the non-linear resistance form a rapid energising path for the field winding for rapid acceleration during gear changing. The drive is compact and cheap to mfr.