The DLRV (Docklands Light Rail Vehicle) consists of two similar cars (Car A and Car B) which are permantly coupled. The cars are mounted onto three bogies; the centre bogie being common to both cars and with the two outside bogies being motored.
The propulsion system has two separately excited traction motors with individual field and armature choppers which are controlled by a hybrid microprocessor/conventional electronics control system. Brake choppers and resistors provide rheostatic braking.
The braking system employed is a fully blended mix of, electric braking (either regenorative or rheostatic as appropriate) and friction braking.
Each traction motor drives its bogies and two axles via a gearbox and have a high starting torque necessary for rapid acceleration with a smooth transition to high speed motoring and an inherent resistance to runaway during wheelslip.
Each armature chopper has two parrallel GTO thyristors with snubbing and smoothing components. Transducers monitor the chopper current and voltage, whilst the armature overload relay and motor contactor provide overload protection.
Each field power supply has two series connected GTO thyristors and a four thyristor reversing bridge with smoothing and snubbing components.
Each brake chopper has a single GTO chopper with associated snubbing components.
The hybrid microprocessor/electronic control system is a closed loop control system with self monitoring, converting the input tractive/brake effort demand signal into field and armature demand signals for the field and armature choppers respectively. The control system also checks that the power circuit is correctly configured and the third rail supply is within the specification.
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