An Integrated Silicon Carbide (SiC) Based Single Phase Rectifier with Power Factor Correction

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I. INTRODUCTION
Power supplies are one of the most crucial building
blocks of a modern society, converting high-voltage AC
into low-voltage DC for use in electronic circuitry in office
equipment, telecommunication, and consumer electronics.
Over 2.5 billion AC/DC power supplies are currently in use
in the United States alone, about 6 to 10 billion are in use
worldwide, thus improving their efficiency will result in
large energy savings. During the last decade efforts have
been made to improve the efficiency of power supplies and
to reduce their size in order to make them more compact
and portable. There are two main approaches to address this
problem. One way is to improve converter topology while
the other is to improve semiconductor technology.


II ADVANTAGES OF SiC BASED POWER SWITCHES
AND DIODES
The present Si technology is reaching the material’s
theoretical limits. To overcome these limitations, new
semiconductor materials are being researched. SiC
technology is the most mature among the various
semiconductor technologies [2] being researched. Some of
the advantages of SiC power based devices compared to Si
based power devices are as follows:
• SiC power devices have higher breakdown voltages thus
allowing a reduction in the on state resistance Ron.
Lower Ron also means lower conduction losses;
therefore, high overall conversion efficiency is
attainable.
• SiC semiconductor has larger band gap thus it can
operate at high temperatures. Si devices, on the other
hand, can operate at a maximum junction temperature of
only 150°C.
• Forward and reverse bias characteristics of SiC devices
vary only slightly with temperature; therefore, they are
more reliable.



A) SiC SWITCH
Amongst the various SiC based switches that are
being investigated SiC (Junction Field Effect Transistor)
JFET has shown promising results [3]. The Rdson is
around 600 mΩ for a 600V SiC JFET which is much less
than that of Si based power MOSFET’s used in high
voltage applications. A JFET is a normally “ON” switch,
thus to turn the JFET off, the gate voltage must be pulled
negative, below the source. However standard power
MOSFET gate drivers switch from 0V (off) to +Vcc (on).
A parallel resistor and capacitor network is required to
connect a power JFET to a MOSFET driver. This network
translates the gate drive signal to supply a negative gate
voltage to turn the JFET off.