THE Cyclo-converter using MATLAB

WHAT IS CYCLO CONVERTER?

Cyclo–Converter has been derived from two words
• Cyclo->Frequency
• Converter ->Change of level

Hence, “Cyclo-converter is a device that converts the frequency of an input voltage and converter from one level to another level.”

Types of cyclo-converters:

Cyclo-converters are of many types, but, the main two divisions of cyclo-converters are
• Up-Converter
• Down-Converter

Up Converter:

Up Cyclo-Converter is a system in which the frequency of voltage and current output signals is greater than input signals. (Fin < Fout)

Down Converter:

Down Cyclo-Converter is a system in which the frequency of voltage and current of output signals is less than input signals. (Fin > Fout)

Other Types include;

Cyclo-Inverters:

Conversion of voltage and current first into DC and then back to ac at the desired frequency is called cyclo-inversion, and the equipment used is called cyclo-Inverter.

Phase Control Cyclo-Converters:

They make use of power electronic devices such as power diodes, MOSFETs and SCR’s etc to convert the frequency from one level to another level.
• Circulating Current Type
• Blocking Mode Type
 

Design of “Phase Controlled Down Cyclo-Converter”

1. Apparatus Required
AC Voltage source 60Hz, MOSFETs, Power Diodes, PWM 5V-50% Duty Cycle, RLC Load.
2. Design

BLOCK DIAGRAM:

 

CIRCUIT IN MATLAB SIMULINK:

 

Working:

The conduction of positive and negative cycle occurs through positive and negative converter respectively. The timing of two MOSFETs being on is so adjusted that when one is on, the other is off. One of the two
MOSFETs is on for 0.01 sec making the total period of the converted wave to be of a period of 0.02 sec.

Output:  Waveform plot:

Possible Improvements for practical use:

• A low pass filter can be put on output to gain the exact output of 60 Hz. The RLC filter is not a good choice. Instead, a pi filter should be used.
• The use of SCR’s is more suitable as the LOAD increases.

Post by The Engineer's.