Choppers are _______ converters.
DC to DC
Choppers: DC to DC Converters
In power electronics, a chopper is a static device that converts fixed DC input voltage into a variable DC output voltage directly. This process is essentially a DC-to-DC voltage transformation. Because of their ability to control DC power, choppers are widely used in various applications, particularly in electric vehicles, regulated power supplies, and DC motor drives.
Chopper Functionality
The primary function of a chopper is to act as a DC equivalent of an AC transformer, allowing for the stepping up or stepping down of DC voltage levels. However, unlike a transformer which works with AC, a chopper operates by rapidly switching a DC input voltage on and off at a high frequency. This rapid switching creates a pulsed DC output, and by varying the duty cycle (the ratio of ON time to the total switching period), the average output DC voltage can be controlled.
- DC to DC Conversion: Choppers are specifically designed to take a DC input and produce a DC output. This distinguishes them from other power converters like rectifiers (AC to DC), inverters (DC to AC), or AC voltage controllers (AC to AC).
- Voltage Regulation: They provide a controlled DC output voltage from an uncontrolled DC input voltage. This control can be used to either reduce (step-down chopper) or increase (step-up chopper) the voltage.
- Efficiency: Since choppers use switching elements (like MOSFETs, IGBTs) that operate in either fully ON or fully OFF states, power losses are minimized, making them highly efficient power converters.
Types of Choppers
Choppers can be broadly classified based on their output voltage relation to the input voltage:
- Step-Down Chopper (Buck Converter): This type of chopper produces an average output voltage less than the input DC voltage. It's used when a lower, regulated DC voltage is required from a higher DC source.
- Step-Up Chopper (Boost Converter): Conversely, a step-up chopper produces an average output voltage greater than the input DC voltage. This is useful in applications where a higher DC voltage is needed from a lower DC source.
Given that choppers convert DC voltage from one level to another DC voltage level, they are fundamentally DC to DC converters.
Important Questions from Choppers
A step-up chopper is supplied through a source of 200 V and operated at a duty cycle of 50%. Find the average output voltage of the chopper.
A chopper is a -
Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R
Assertion A: Chopper converts fixed d.c. input voltage to a controllable d.c. output voltage. The Chopper circuit require forced or load commutation to turn off the thyristors.
Reason R: The Chopper circuits are dependent upon the type of commutation and also on the direction of power flow.
In the light of the above statements, choose the most appropriate answer from the options given below
A load commutated chopper fed d.c. drive uses 100 V d.c. supply. The maximum chopper frequency is 5 kHz. The value of maximum load current is 100 A. The commutating capacitance will be :
In a lossless buck converter, an average power of 20 W to a load with a regulated 12 V output, while operating at a duty cycle of 0.8 with continuous inductor current. Following data is given :
(a) The average value of input voltage is given by 15 V
(b) The average value of input voltage is 16 V
(c) The average value of input current is 4/3 A
(d) The average value of input current is 3/4 AWhich is correct out of the following ?
