For the refurbishment of 12 Class 900 EMUs operated by Flumitrens of Brazil, Adtranz Switzerland has supplied IGBT choppers with an input voltage of 3 kV DC to replace the JH camshaft equipment controlling four 279 kW traction motors in each motor car. Each four-car Class 900 has two motor cars, with two refurbished sets coupled to form an eight-car Class 9000 trainset.
Controlling the traction motors in both power and braking mode, the chopper provides a starting current of 640A and is based on the recently-developed Integrated Power Module. The IPM is able to block voltages up to 4·5 kV and switch currents up to 1500A at 3·4 kV without a snubber; it comprises IGBT chips, associated freewheeling diode chips, a water-cooled heatsink, plug-in contacts and a gate drive.
The Class 900’s relay-based control has been replaced with a programmable Mitrac system, with distributed modules connected by a multifunctional vehicle bus. The control and input/output modules are equipped with their own power supply units, which obviates the need for a rack or forced cooling.
Refurbishment has also included installing DC/AC inverters to supply auxiliary power and fitting electronic braking. The driver’s cab of each Class 9000 has received a new control desk, air-conditioning and larger windows for improved visibility.
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