much different than it is for silicon IGBTs (3 kHz)。 A tradeoff analysis could carried out, but
the targeted benefits will be small and would not likely swing any conclusions reached in this
project。 In addition the trade off study should be carried out for the correct voltage, which will
likely be much higher than the 690 V specified for the baseline turbine。 Designing a high current,
high frequency medium-voltage inductor is a significant design exercise there are no such
products in the market to the author's knowledge。 It is the understanding of the author that
further work of this nature is being done in another NREL concept study in parallel to this
project。
5。 6 promising New Wind Turbine Configurations Using SIC
This project has led to the conclusion that SIC devices will not be exploited to greatest advantage
if they are just used as one-for-one replacements of existing silicon devices in power
electronics rated at 690 V。 However, SIC devices have unique characteristics that can be
exploited to great advantage if the overall configuration is allowed to change。 An existing
baseline wind turbine should not dictate how the SIC devices are used, but rather the unique
characteristics of SIC devices should dictate how the system is configured。 The pertinent SIC
characteristics for wind turbines are high voltage and temperature capability。 Several new
approaches capitalizing on the high-voltage capability are described in this section。 They are not
exhaustive, but rather illustrate some of the new possibilities with SIC devices。 How to capitalize
on the high temperature capability is covered later。
5。6。1 Medium Voltage With Standard Transformer
In this alternative, the baseline converter show in Figure 1 would be made entirely of SIC
MOSFETs (or SIC BJTs) and SIC PN junction diodes (or Schottkys) capable of operating at
2300 VAC and 4, 160 VA。 C, which requires devices that can withstand 5, 500 V and 10, 000 V,
respectively。 The generator feeding this converter in addition to the filter inductor, would also
be rated nominally at 2, 300 VAC or 4, 160 VAC。 The converter would be connected to the grid
through a standard 60 HZ transformer。 The 1。 5 MW of power from the baseline turbine can be
handled by a single inverter bridge that carries only 208 amps and is about one-sixth the size of
that required with silicon IGBTs rated for operation at 690 V rms。 This relatively simple
topology cannot be developed with standard silicon IGBTs and is therefore uniquely enabled by
SIC。
Given DARPA and Navy work now being carried out along with other Peregrine work, the
necessary inverter bridge could be designed and tested during the next two to five years。 It is
impossible to be precise about the reduction in losses due to lack of real test data for high-
forward conduction losses with higher voltage and significant reduction in switching losses。
5。 6。 2 Medium Voltage With High Frequency Transformer
Figure 2 shows in block form the next interesting configuration which contains a high frequency
transformer。 This is a well-know approach to reducing the size of transformers, and is currently
being pursued by the Navy using SIC。 The general strategy is to create smooth DC with a
Rectifier, and then feed the transformer with a high frequency train of square AC pulses created
by an H-bridge。 The width of the pulses can be varied using standard PWM techniques to
regulate the voltage on the output side of the transformer。 The high frequency output is again
rectified into smooth DC, which is inverted using PWM techniques and filtered。 The frequency 碳化硅电器元件的应用英文文献和中文翻译(5):http://www.youerw.com/fanyi/lunwen_98498.html