RDSO has brought a specification to design PM Alternator with 650 Amp. Hour Battery Charger for LHB Coaches. This is required as the space available is less than 750mm for mounting alternator in the LHB Coach and also to mount the Axle Pulleys. The spec calls for high efficient and high performance PM Alternator with Controller and also a Battery charger unit in the same control panel.
The alternator is having a stator stack with very low loss CRNGO stampings punched with slots for three phase windings. The stator is wound with three phase winding and the leads are taken out to the terminal box of the alternator. The rotor is also built with low loss CRNGO Stampings and having slots to house the Permanent Magnets of high energy NdFeB and the rotor surface is punched to produce Sinusoidal voltage to avoid the harmonic losses in the alternator. The shaft is forged EN24 to give maximum strength and spherical roller bearings are used to take care of railway applications.
The alternator is designed for low MFO and for Maximum speed of 175 KMPH. The weight of the alternator is less than 180 kg compared to the existing 550 Kg of the conventional Inductor Alternator.
These alternators can also be used in the conventional coaches with the ERRUs designed for the purposes and save diesel in the locomotives due to high efficiency and the low weight which reduces the tractive effort of the main locomotive.

The control panel is provided with the control circuit for the control of the PM alternator from Cut in speed to Maximum speed and from minimum load to maximum rated load and maintain the output voltage at 130 V DC +/- 2%.
The control of the PM Alternator is PWM with IGBTs in the main circuit and maintain the power factor more than 0.95 and the efficiency of both the alternator and control panel more than 92%.
The battery charger is also housed in the same control panel and is used from the mains of 415 Volts ac three phase supply in the stations for pre cooling the AC coach before starting the train.

Maximum CURRENT –
Pulleys 5 belts each side – Double ended Drive