01-06-2012, 01:27 PM
Modern trends of electric drives in electric traction systems
Modern trends of electric drives.doc (Size: 153.5 KB / Downloads: 173)
Abstract :
Electric traction makes things easier and safer. They bring down the distance and time and break the barriers of time and space. Electric traction is very economical, easy and safe. They can largely opt for vehicles, elevators etc. Electric traction vehicles include general-purpose electrical locomotives, electro-motor trains for city and intercity, shunting locomotives, industrial locomotives, mine locomotives, dc operated tramcars, low floor tramcars with asynchronous induction drives etc. These vehicles use wide range of traction equipment like dc traction motors, induction traction motors, locomotive transformers, main drive rectifiers.
Introduction :
Traction motors can use both ac/dc currents with suitable control electronics. They are operating in high voltage current. They can widely used for vehicles, elevators, locomotives etc. Electric traction makes things easier and safer. They bring down the distance and time and break the barriers of time and space. Electric traction is very economical, easy and safe. They can largely opt for vehicles, elevators etc. Electric traction vehicles include general-purpose electrical locomotives, electro-motor trains for city and intercity, shunting locomotives, industrial locomotives, mine locomotives, dc operated tramcars, low floor tramcars with asynchronous induction drives etc. These vehicles use wide range of traction equipment like dc traction motors, induction traction motors, locomotive transformers.
Classification:
Electrification systems are classified by three main parameters:
Voltage
The common voltages are simple multiples of each other:
1200 V DC = 2 x 600 V DC ,1500 V DC = 2 x 750 V DC
3000 V DC = 2 x 1500 V DC
Current
This can be direct current (DC) or alternating current (AC). For AC systems, the frequency (hertz) is also given. In general, it is assumed that AC systems are single-phase, but if they are not (e.g. three-phase), then this should also be stated.
Contact System
This refers to the means by which traction current is collected by the traction unit. There are two main types: (Conductor Rail and Overhead Line).
Electric traction drives :
The DC Traction Motor: How it Drives the Axle:
The traditional DC (Direct Current) electric motor driving a train or locomotive is a simple machine consisting of a case containing a fixed electrical part, the stator (called the stator because it is static and comprising what is called the field coils) and a moving electrical part, the rotor (because it rotates) or armature as it is often called. As the rotor turns, it turns a pinion which drives a gearwheel. The gearwheel is shrunk onto the axle and thus drives the wheels as shown in the diagram below. The motion of the motor is created by the interaction of the magnetism caused by the currents flowing the the stator and the rotor. This interaction causes the rotor to turn and provide the drive.
Conclusion :
Using these electric drives we can get better performance and by applying these electronic control methods we can easily control our electric traction motors.