chopper transformer

chopper transformer

1. 1 Introduction A chopper is a static device that converts fixed dc input voltage to a variable dc output voltage directly

2. prefrence of chopper transformer To increase the power available from the present transformer without reducing its life. B) To enable a load of different impedance to be supplied by the same rectifier transformer within total kilowatt limitations. 2

3. Types of chopper There are two types of choppers AC DC 3

4. AC link chopper In AC link chopper,first DC is converted to AC with the help of an inverter. After that AC is stepped- up or stepped –down. Then converted bak to DC by a diode rectifier. 4

5. Disadvantages Expensive Bulky Less efficent 5

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7. DC Chopper A DC chopper is a static device that converts fixed dc input voltage to a variable dc output voltage. This kind of choppers are more efficient as they involve one stage conversion 7

8. Principle of Chopper Operation A chopper can be said as a high speed on/off semiconductor switch. It connects source to load and disconnects the load from source at high-speed. 8

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10. (a) Based on the output voltage of the output the choppers are classified as Step-Down Chopper In this case the average output voltage is less than the input voltage. It is  also known as step down converter. Step-Up Chopper Here the average output voltage is more than the input voltage. It is also known as step up converter. Step-Up/Down Chopper This type of converter produces an output voltage that is either lower or higher than the input voltage 10

11. (c) Depending upon the power loss  the choppers are classified into two categories Hard switched Converter Here the power loss is high during the switching (ON to OFF and OFF to ON) as a result of the non zero voltage and current on the power switches.   Soft switched or resonant converters In this type of choppers, the power loss is low at the time of switching as a result of zero voltage and/or zero current on the switches. 11

12. Applications of Choppers They are used for DC motor control (battery-supplied vehicles), solar energy conversion and wind energy conversion. Used in electric cars, airplanes and spaceships, where onboard-regulated DC power supplies are required. As power supplies in computers, commercial electronics, electronic instruments. 12

13. Refrences http://www.circuitstoday.com/choppers-an-introduction http://www.completepowerelectronics.com/converters/chopper 13