CYCLOCONVERTER FOR FREQUENCY CYCLOCONVERTER FOR FREQUENCY CONVERSIONCONVERSION

Presented byPresented by SAMUEL-AGI, SATURDAY SAMUEL-AGI, SATURDAY

06H/0600/EE06H/0600/EEDepartment of Electrical and Electronics Department of Electrical and Electronics Engineering [Telecommunications option] Engineering [Telecommunications option]

Federal Polytechnic Nekede Owerri.Federal Polytechnic Nekede Owerri.Supervised bySupervised by

Engr. R. N. OgbonnaEngr. R. N. Ogbonna

INTRODUCTIONSINTRODUCTIONS

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

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

TYPES OF CYCLOCONVERTERSTYPES OF CYCLOCONVERTERSMatrix cycloconverterMatrix cycloconverterSingle –phase-to –single-phase Single –phase-to –single-phase

cycloconverter.cycloconverter.Single –phase-to-three-phase Single –phase-to-three-phase

cycloconverter.cycloconverter.DC link cycloconverter with parallel-DC link cycloconverter with parallel-

resonant circuit.resonant circuit.Three-phase-to-three-phase Three-phase-to-three-phase

cycloconverter.cycloconverter.

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.

SINGLE-PHASE-TO-SINGLE-PHASESINGLE-PHASE-TO-SINGLE-PHASEThe single-phase-to-single-phase cycloconverter has the The single-phase-to-single-phase cycloconverter has the

positive centre-tap thyristor converter connected in positive centre-tap thyristor converter connected in anti-parallel with a negative converter of a similar type anti-parallel with a negative converter of a similar type so that the voltage and current of either polarity can be so that the voltage and current of either polarity can be controlled in the load.controlled in the load.

SINGLE-PHASE-TO-THREE-PHASE SINGLE-PHASE-TO-THREE-PHASE

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

a single-phase system to a three-phase system a single-phase system to a three-phase system is required .It has two major types viz;is required .It has two major types viz;

Integral pulse modulated (single-phase-to-Integral pulse modulated (single-phase-to-three-phase) cycloconverterthree-phase) cycloconverter

phase-controlled (single-phase-to-three-phase) phase-controlled (single-phase-to-three-phase) cycloconverter.cycloconverter.

THREE-PHASE -TO -THERE –PHASETHREE-PHASE -TO -THERE –PHASE CYCLOCONVERTERCYCLOCONVERTER

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

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

APPLICATIONS OF CYCLCONVERTERSAPPLICATIONS OF CYCLCONVERTERS cycloconverters are used in controlling the cycloconverters are used in controlling the

speed of ac machines such as the speed of ac machines such as the Synchronous motor.Synchronous motor. Cement mill drives. Cement mill drives. Ship propulsion.Ship propulsion. Rolling mill drives. Rolling mill drives. Ore grinding mills.Ore grinding mills. Slip-power recovery Scherbius drives.Slip-power recovery Scherbius drives. Variable-speed,constant-Variable-speed,constant-

frequency{VSCF} power generation for frequency{VSCF} power generation for aircraft 400 Hz power supplies.aircraft 400 Hz power supplies.

RECOMMENDATION RECOMMENDATION I RECOMMEND THAT THE HARMONICS I RECOMMEND THAT THE HARMONICS

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

CONCLUSIONCONCLUSION

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

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

In conclusion, cycloconverters are very In conclusion, cycloconverters are very vital especially to factory machines vital especially to factory machines

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