04-07-2012, 01:27 PM
Implementation of Single-Phase Matrix Converter as a Direct AC-AC Converter with Commutation Strategies
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INTRODUCTION
Many theoretical studies have been investigated on Matrix
Converter (MC) but have found limited practical applications
in power electronics. Nevertheless, MC has been described to
offer an “all silicon” solution for AC-AC conversion,
removing the need for reactive energy storage components
used in conventional rectifier-inverter based system [1] and
hence an attractive alternative converter. The topology was
first proposed by Gyugyi [2] in 1976, arranged such that any
output lines of the converter can be connected to any input
lines. Obviously, published studies have mainly dealt with
three-phase circuit topologies [3, 4, 5]. The single-phase
variant called the the Single-phase Matrix Converter (SPMC)
was first realised by Zuckerberger [6]. Other SPMC topology
had been studied by Hossieni [7] and Abdollah Khoei [8].
Another work was carried out by Saiful [9] proposing the use
of SPWM but has not been experimentally verified. Very few
publications have been found on SPMC but none with
commutation strategies in their implementations.
AC-AC CONVERTER
A classical rectifier-inverter system that could perform
frequency conversion can be depicted as shown in Figure 1,
where the use of storage device for the DC link is necessary
for operation. A direct AC-AC converter on the other hand
converts a fixed frequency fixed voltage input into a variable
frequency variable voltage output without the use of
intermediate storage device. The basic AC-AC energy
conversion described has three possible operations, namely;
a) AC Controller, b) decreased frequency operation and c)
increased frequency operation as illustrated in Fig. 2 to 4
respectively.
HARDWARE DESCRIPTION
A block diagram of the SPMC comprising a phase detector
circuit, control unit, driver circuit and a SPMC circuit are as
shown in Fig. 15. The control unit is used mainly to generate
SPWM gating pulse determined by the XILINX (FPGA) with
the digital implementation
CONCLUSION
In this paper, a direct AC-AC converter using single phase
matrix converter with passive load condition was presented
without the need of intermediate DC link. Results of the
SPMC for both the simulation and experiments illustrates that
it is feasible to realise the converter in the various basic
AC-AC conversion that includes; AC controller, step-up
frequency changer and step-down frequency changer. The
safe-commutation technique implemented has resulted in a
scheme that allows dead time to avoid current spikes of
non-ideal switches and at the same time establishing a current
path that could eliminate switching spikes due to the use of
inductive load. As can be observed in the experimental
results, good agreement was obtained with those predicted in
simulations.