Correct Answer - Option 1 : AC regulation
Choppers can provide regeneration, fast response, smooth control but do not provide AC regulation.
Concept:
A chopper is a static device which is used to obtain a variable dc voltage from a constant dc voltage source. Also known as a dc-to-dc converter.
They can step up the DC voltage or step down the DC voltage levels.
Types of Choppers:
- Type A Chopper or First-Quadrant Chopper
- Type B Chopper or Second-Quadrant Chopper
- Type C Chopper or Two-quadrant type-A Chopper
- Type D Chopper or Two-quadrant type-B Chopper
- Type E Chopper or fourth-quadrant Chopper
Note:
Power electronic circuits can be classified as follows.
1. Diode rectifiers:
- A diode rectifier circuit converts AC input voltage into a fixed DC voltage.
- The input voltage may be single phase or three phase.
- They find use in electric traction, battery charging, electroplating, electrochemical processing, power supplies, welding and UPS systems.
2. AC to DC converters (Phase controlled rectifiers):
- These convert AC voltage to variable DC output voltage.
- They may be fed from single phase or three phase.
- These are used in dc drives, metallurgical and chemical industries, excitation systems for synchronous machines.
3. DC to DC converters (DC Choppers):
- A dc chopper converts DC input voltage to a controllable DC output voltage.
- For lower power circuits, thyristors are replaced by power transistors.
- Choppers find wide applications in dc drives, subway cars, trolley trucks, battery driven vehicles, etc.
4. DC to AC converters (Inverters):
- An inverter converts fixed DC voltage to a variable AC voltage. The output may be a variable voltage and variable frequency.
- In inverter circuits, we would like the inverter output to be sinusoidal with magnitude and frequency controllable. In order to produce a sinusoidal output voltage waveform at a desired frequency, a sinusoidal control signal at the desired frequency is compared with a triangular waveform.
- These find wide use in induction motor and synchronous motor drives, induction heating, UPS, HVDC transmission etc.
5. AC to AC converters: These convert fixed AC input voltage into variable AC output voltage. These are two types as given below.
i. AC voltage controllers:
- These converter circuits convert fixed AC voltage directly to a variable AC voltage at the same frequency.
- These are widely used for lighting control, speed control of fans, pumps, etc.
ii. Cycloconverters:
- These circuits convert input power at one frequency to output power at a different frequency through a one stage conversion.
- These are primarily used for slow speed large ac drives like rotary kiln etc.
6. Static switches:
- The power semiconductor devices can operate as static switches or contactors.
- Depending upon the input supply, the static switches are called ac static switches or dc static switches.
