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External control of dc input voltage can be obtained by the use of a______.
Transformer
Chopper
Inverter
Converter
Chopper
A DC-to-DC converter, commonly known as a chopper, is a static power electronics device used to step up or step down a fixed DC input voltage to a variable DC output voltage. It achieves this by rapidly switching a semiconductor device (like a MOSFET or IGBT) on and off, effectively controlling the average output voltage.
A DC-to-DC converter, commonly known as a chopper, is a static power electronics device used to step up or step down a fixed DC input voltage to a variable DC output voltage. It achieves this by rapidly switching a semiconductor device (like a MOSFET or IGBT) on and off, effectively controlling the average output voltage.
VoutтАЛ=kтЛЕVinтАЛ тАФ Average output voltage relationship
k=TonтАЛ+ToffтАЛTonтАЛтАЛ тАФ Duty cycle definition
The chopper operates on the principle of pulse-width modulation (PWM). By varying the duty cycle (k), which is the ratio of the "on" time to the total switching period, the average output voltage (VoutтАЛ) can be regulated independently of the input source (VinтАЛ). The relationship is defined as VoutтАЛ=k├ЧVinтАЛ, where k=TTonтАЛтАЛ.
Choppers perform DC-to-DC conversion, acting as the DC equivalent of an AC transformer.
They are widely used in variable speed drives and power supply units.
Efficiency is very high due to semiconductor switching instead of resistive control.
High efficiency
Compact size and low weight
Fast response time
Generates electromagnetic interference (EMI)
Requires complex control circuitry for high-frequency operation
Electric traction systems
Battery-operated electric vehicles
Regenerative braking systems
A chopper is a high-speed semiconductor switch that turns on/off to modulate the average voltage.
Transformers are AC devices based on electromagnetic induction and cannot work on steady DC.
B is correct тАФ A chopper is a static power electronics circuit used to convert fixed DC input into variable DC output voltage.
Always remember: Transformers operate on the principle of Faraday's Law of Induction, which requires changing magnetic flux, making them unsuitable for steady DC without a conversion stage.