A cycloconverter is a device that converts AC power at one frequency to a different output frequency in a single stage. There are several types of cycloconverters including matrix, single-phase to single-phase, single-phase to three-phase, and three-phase to three-phase. Cycloconverters are used to control the speed of AC machines in applications like cement mill drives, ship propulsion, rolling mills, and variable speed power generation. The document recommends incorporating a power-storing device to help filter harmonics produced by cycloconverters and provide backup power during interruptions.

1. CYCLOCONVERTER FOR FREQUENCYCYCLOCONVERTER FOR FREQUENCY
CONVERSIONCONVERSION
Presented byPresented by
SAMUEL-AGI, SATURDAYSAMUEL-AGI, SATURDAY
06H/0600/EE06H/0600/EE
Department of Electrical and ElectronicsDepartment 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

2. INTRODUCTIONSINTRODUCTIONS
A cycloconverter is a frequency changerA cycloconverter is a frequency changer
which converts AC power at one inputwhich converts AC power at one input
frequency to output power at a differentfrequency to output power at a different
frequency with a one stage conversionfrequency with a one stage conversion
process.process.
The quality of the output improves if moreThe quality of the output improves if more
switching devices (e.g. thyristors) areswitching devices (e.g. thyristors) are
used.used.

3. TYPES OF CYCLOCONVERTERSTYPES OF CYCLOCONVERTERS
Matrix cycloconverterMatrix cycloconverter
Single –phase-to –single-phaseSingle –phase-to –single-phase
cycloconverter.cycloconverter.
Single –phase-to-three-phaseSingle –phase-to-three-phase
cycloconverter.cycloconverter.
DC link cycloconverter with parallel-DC link cycloconverter with parallel-
resonant circuit.resonant circuit.
Three-phase-to-three-phaseThree-phase-to-three-phase
cycloconverter.cycloconverter.

4. 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.

5. SINGLE-PHASE-TO-SINGLE-PHASESINGLE-PHASE-TO-SINGLE-PHASE
The single-phase-to-single-phase cycloconverter has theThe single-phase-to-single-phase cycloconverter has the
positive centre-tap thyristor converter connected inpositive centre-tap thyristor converter connected in
anti-parallel with a negative converter of a similar typeanti-parallel with a negative converter of a similar type
so that the voltage and current of either polarity can beso that the voltage and current of either polarity can be
controlled in the load.controlled in the load.

6. SINGLE-PHASE-TO-THREE-PHASESINGLE-PHASE-TO-THREE-PHASE
The single-phase-to-three-phase cycloconverterThe single-phase-to-three-phase cycloconverter
is applied where the conversion of power fromis applied where the conversion of power from
a single-phase system to a three-phase systema 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.

7. THREE-PHASE -TO -THERE –PHASETHREE-PHASE -TO -THERE –PHASE
CYCLOCONVERTERCYCLOCONVERTER
This type of cycloconverter converts input ac powerThis 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 circuitIt contains about 18 thyristors [switches]. The circuit
comprises of three identical half-wave anti-parallelcomprises of three identical half-wave anti-parallel
phase groups. The output voltage contains complexphase groups. The output voltage contains complex
harmonics which may be filtered by the machinesharmonics which may be filtered by the machines
effective leakage inductance.effective leakage inductance.

8. APPLICATIONS OF CYCLCONVERTERSAPPLICATIONS OF CYCLCONVERTERS
cycloconverters are used in controlling thecycloconverters are used in controlling the
speed of ac machines such as thespeed 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 forfrequency{VSCF} power generation for
aircraft 400 Hz power supplies.aircraft 400 Hz power supplies.

9. RECOMMENDATIONRECOMMENDATION
I RECOMMEND THAT THE HARMONICSI RECOMMEND THAT THE HARMONICS
PRODUCED BY THE CYCLOCONVERTERSPRODUCED BY THE CYCLOCONVERTERS
CAN BE COMBATED BY DESIGNING A TYPECAN BE COMBATED BY DESIGNING A TYPE
OF CYCLOCONVERTER THAT CAN FILTEROF CYCLOCONVERTER THAT CAN FILTER
OUT HARMONICS.THEREFORE,I SUGGESTOUT HARMONICS.THEREFORE,I SUGGEST
THAT A POWER-STORING DEVICE SHOULDTHAT A POWER-STORING DEVICE SHOULD
BE INCORPORATED TO THEBE INCORPORATED TO THE
CYCLOCONVERTER MACHINE SO THAT THECYCLOCONVERTER MACHINE SO THAT THE
STORED POWER COULD BE USED WHENSTORED POWER COULD BE USED WHEN
THERE IS POWER FLUCTUATION, FREQUENTTHERE IS POWER FLUCTUATION, FREQUENT
INTERRUPTION OR TOTAL POWER FAILUREINTERRUPTION OR TOTAL POWER FAILURE
FOR THE CONSUMPTION BY THEFOR THE CONSUMPTION BY THE
POLYTECHNIC COMMUNITY.POLYTECHNIC COMMUNITY.

10. CONCLUSIONCONCLUSION
Cyclocnverters are basically used in theCyclocnverters are basically used in the
industry for ac-to-ac conversion. Withindustry for ac-to-ac conversion. With
Recent device advances, power forms ofRecent device advances, power forms of
cycloconversions are being developed.cycloconversions are being developed.
In conclusion, cycloconverters are veryIn conclusion, cycloconverters are very
vital especially to factory machinesvital especially to factory machines
that need ac-to-ac conversion where it isthat need ac-to-ac conversion where it is
best applied.best applied.