Page 35 - PEN Ebook May 2021
P. 35
Design Design
Figure 2: CL filter Waveform.
Figure 1: DC-DC Converter with CL and LC Filter.
bers are not required in case of CL filter for the DC output current and this all happens because
rectification of the diodes. The waveform of the of the higher peak of the current in a triangular
current in the H-bridge is triangular because of waveform. For instance, the losses have been
the discontinuous rectifier current. Higher cur- calculated on the basis of the 1200V on the IGBT
rent peaks are responsible for making triangular technology that is switching at 10kHz. If the
waveform inefficient. There is a 120A current snubber rectifier is not designed properly then
charge at 400 DC out and 500 DC in, as shown the partial offset can be detected in the IGBT
in figure 2. Using an LC output filter results in a losses.
continuous current which produces square waves
with low current peaks in the H-bridge. Another
advantage related to the use of LC filter is the DESIGN OF RECTIFIER SNUBBER
high efficiency [1]. The waveform of the LC filter CIRCUIT Figure 3: LC filter Waveform.
is shown in figure 3. With a huge number of losses dissipating the ADVANTAGES OF SIC SCHOTTKY ▶ Small amount of charge at the capacitance of
rectifier snubber starts to become problematic DIODE the junction, but it is not greater than the Qrr
[1]. It is important that the Qrr in the diodes is Some of the significant advantages that are as- at the normal Si PN junction.
H-BRIDGE LOSSES absorbed by the snubber circuit and should be sociated with the SiC devices are:
The switching losses are most prominent when dissipated in the resistor and, because of this ▶ Easy and ready availability at the standard
turning off the switching devices [1]. 50% of the whole process, the efficiency gets reduced, and ▶ A tendency of lowering the loss of switching. package of the industry.
IGBT losses at higher value occurs in comparison the need of large components is increased [1]. At
to the triangular waveform at the same level of this point there’s no other help but a SiC diode. ▶ Reverse recovery charge is not present.
34 MAY 2021 | www.powerelectronicsnews.com MAY 2021 | www.powerelectronicsnews.com 35
