Abstract:
High frequency switching power supplies have become part of electronic
equipments to provide regulated DC of desired voltages at a lost cost and high
efficiency. These power supplies have several advantages over their counterpart
the linear power supplies. Main advantages are smaller compact size due to
elimination of step down transformer and small filters due to high frequency
operation. These power supplies have high frequency because the regulating
devices in their works as switches ensuring low device loss. Their output voltages
can be controlled for a wide range of input voltage fluctuation by changing the
duty cycle of the switching signals.
Four common types of switch mode converters are used in DC to DC conversion.
They are BUCK, BOOST, BUCK-BOOST and ĈUK converters. Researchers are
trying to modify these DC regulators to regulate AC voltage.
Utility AC voltage fluctuation both momentary and prolonged, affect adversely the
domestic, industrial and commercial customers. A new topology of single phase
Ĉuk AC voltage controller is proposed. The performance of the Ĉuk AC controller
has good power factor and Total Harmonic Distortion (THD) values compared to
the conventional AC-AC voltage controllers. Input AC current chopping by high
frequency Ĉuk conversion for the positive and negative cycle provides low input
current THD within IEEE 519, IEC 61000-3-2 standards and has improved power
factor. The circuit efficiency is also acceptable for certain range of duty cycle.
Positive and negative cycle Ĉuk conversion is performed by a single bi-directional
switch and the output of two conversions is differentially connected to obtain the
controllable step-up/step-down AC output voltage. The proposed circuit is
investigated at low frequency switching so that it can be used in high power
conversion also.
