Category: ELECTRICAL MACHINES

Static Scherbius Scheme

Static Scherbius Scheme: Static Scherbius Scheme – A basic scheme of a Scherbius static-converter cascade, that is employed for recovery of slip power in electrical form itself, is given in Fig. 11.42. For achieving both subsynchronous and supersynchronous speed control, converters C1 and C2 must be fully-controlled thyristor bridges, one functioning at slip frequency as […]

AC Motor Control

AC Motor Control: AC Motor Control – The only way to control the speed of a synchronous motor is to control the input frequency and voltage such as to keep V/f constant. The induction motor, on the other hand, can be controlled by the following means: 1. Stator Voltage Control This is applicable for small […]

DC Motor Control through Choppers

DC Motor Control through Choppers: DC Motor Control through Choppers – For controlling a dc motor operated from dc supply, the dc voltage level must be controlled. Examples can be cited of subway drives, trolley buses or battery-operated vehicles. Conventional methods of converting a fixed-voltage dc source to a variable-voltage dc source are: Resistance Control […]

Three Phase Converters

Three Phase Converters: Large-kW motors are fed from 3-phase supply through three Phase Converters. In a Three Phase Converters, the ripple frequency of the motor terminal voltage is higher than that in the single-phase converter, as a result the filtering requirements for smoothing out the motor current are less and the current is mostly continuous. […]

DC Motor Control through Converters

DC Motor Control through Converters: DC motor control is conveniently and efficiently achieved by phase-controlled converters wherein the ac input voltage is converted to a controlled dc output. The commutation process, the transfer of current from one thyristor to the other, in these converters is the inexpensive natural or line commutation. As, an incoming thyristor is […]

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