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MAYURBHANJ SCHOOL OF ENGINEERING � LAXMIPOSI ,BARIPADA,757107

Prepared by Mr. Guru pada Mishra(Lect. Electrical Engineering Department)

Subject – Power Electronics & PLC

Chapter – 3 – Understand the Inverters & Cyclo converter

Topic – Cycloconverter

Semester – 5th

Branch – Electronics & Telecommunication

AY-2021-2022, WINTER-2021

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INTRODUCTIONS

A cycloconverter is a frequency changer which converts AC power at one input frequency to output power at a different frequency with a one stage conversion process.

The quality of the output improves if more switching devices (e.g. thyristors) are used.

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TYPES OF CYCLOCONVERTERS

  • Matrix cycloconverter
  • Single –phase-to –single-phase cycloconverter.
  • Single –phase-to-three-phase cycloconverter.
  • DC link cycloconverter with parallel- resonant circuit.
  • Three-phase-to-three-phase cycloconverter.

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MATRIX CYCLOCONVERTER

A Matrix converter consists of a matrix of 9 switches connecting the three input phases to the three output phases .No two switches from the same phase should be ON at the same time, otherwise this will cause a short circuit of the input phases.

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SINGLE-PHASE-TO-SINGLE-PHASE

The single-phase-to-single-phase cycloconverter has the positive centre-tap thyristor converter connected in anti-parallel with a negative converter of a similar type so that the voltage and curre nt of either polarity can be controlled in the load.

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SINGLE-PHASE-TO-THREE-PHASE

The single-phase-to-three-phase cycloconverter is applied where the conversion of power from a single-phase system to a three-phase system

is required .It has two major types viz;

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  • Integral pulse modulated (single-phase-to- three-phase) cycloconverter
  • phase-controlled (single-phase-to-three-phase) cycloconverter.

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THREE-PHASE -TO -THERE –PHASE CYCLOCONVERTER

This type of cycloconverter converts input ac power from three-phase-to-three-phase.

It contains about 18 thyristors [switches]. The circuit comprises of three identical half-wave anti-parallel phase groups. The output voltage contains complex harmonics which may be filtered by the machines effective leakage inductance.

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APPLICATIONS OF CYCLCONVERTERS

cycloconverters are used in controlling the speed of ac machines such as the

  • Synchronous motor.
  • Cement mill drives.
  • Ship propulsion.
  • Rolling mill drives.
  • Ore grinding mills.
  • Slip-power recovery Scherbius drives.
  • Variable-speed,constant- frequency{VSCF} power generation for aircraft 400 Hz power supplies.

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RECOMMENDATION

I RECOMMEND THAT THE HARMONICS PRODUCED BY THE CYCLOCONVERTERS CAN BE COMBATED BY DESIGNING A TYPE OF CYCLOCONVERTER THAT CAN FILTER OUT HARMONICS.THEREFORE,I SUGGEST THAT A POWER-STORING DEVICE SHOULD BE INCORPORATED TO THE CYCLOCONVERTER MACHINE SO THAT THE STORED POWER COULD BE USED W HEN THERE IS POWER FLUCTUATION, FREQUENT INTERRUPTION OR TOTAL POWER FAILURE FOR THE CONSUMPTION BY THE POLYTECHNIC COMMUNITY.

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CONCLUSION

Cyclocnverters are basically used in the industry for ac-to-ac conversion. With

Recent device advances, power forms of cycloconversions are being developed.

In conclusion, cycloconverters are very vital especially to factory machines

that need ac-to-ac conversion where it is best applied.

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