Schaffler & Associates - Battery Chargers, Converters and Inverters

Schaffler & Associates produce power electronic products for rail applications, manufactured for use in rugged, high-temperature environments. Products are available for both under car mounting or mounting within the switchgear lockers. Schaffler & Associates provide power electronic equipment for new rolling stock and upgrading and retrofitting of electrical equipment on old cars and locomotives.

BATTERY CHARGERS

Schaffler & Associates manufacture chargers for batteries with voltages of 24VDC, 74VDC, 120VDC and 280VDC. The charging current is 50A, 150A, 250A or 500A.

The battery charging algorithm is summarised below. There are three modes of operation during charging which extend the life of batteries.

Constant current charging: during the first period of charging the batteries are charged at a constant current. The battery voltage increases to the gassing voltage and the charger switches to constant voltage.

Constant voltage charging: in the second period of charging the batteries are at a constant voltage - the charging current dropping away exponentially. When the charging current reduces to the trickle charge level, the battery charging mode switches to trickle charge.

Trickle charge: the charging remains in trickle charge until the rate of change of DC link voltage drops below 1% of the nominal voltage per half hour, the batteries are fully charged and charging stops.

DC:DC CONVERTERS

Boost converters: these convert the voltage from 120 VDC to 580 VDC. Boost converters are high-frequency converters used for increasing the DC voltage to 580VDC, which then becomes suitable for driving our range of three-phase inverters. The power range is from 4kW to 8kW.

Buck converters: these convert the voltage from 750VDC to 580VDC. They are ideal for cars supplied with 750VDC where there is significant fluctuation of the power supply (up to 1,100VDC). Our standard range of inverters can be powered from this supply. The power range supplied is up to 60kW.

Variable voltage, variable frequency converter: conversion of variable supply from traction driven alternator 220VAC 25Hz to 380VAC/415VAC three-phase 50Hz/60Hz. This is particularly applicable to locomotive electrical supplies. The converter uses the principle of an active front end IGBT inverter and the power ranges up to 80kW.

DC:AC INVERTERS

DC:AC three-phase inverters: these convert 750VDC, 580VDC, 120VDC and 74VDC to 380VDC/415VDC three-phase 50Hz/60Hz. This product is a combination of the DC:DC converter and three-phase inverter. Its power ranges from 6kW to 60kW.

DC:AC single-phase inverter: these inverters convert 76VDC and 120VDC to 240V one-phase 50Hz/60Hz. These inverters are intended for use for locomotive instrumentation and to power the driver's kettle, microwave oven and toilet hand drier. The power range lies between 2.5kW to 5kW.

FREQUENCY CONVERTERS

Schaffler & Associates also produce single-phase to three-phase frequency converters. The three-phase high frequency converting to a 50Hz/60Hz inverter. The power range is from 1kW to 22kW.