At present there are many commonly used power electronic devices such as IGBT(here http://www.kynix.com/Search/IGBT.html which one is better), SCR, P - MOSFET, etc.
My question is:
(1) What are the necessary characteristics of the ideal power electronics device which should have? Which of the devices mentioned above is ideal?
(2) What kind of device do we usually choose for the power electronic device with high frequency and small capacity ? Tell me the teason.
(3) What kind of device doese the converter station of dc transmission system usually choose? Also the reason.
Added 4 years, 10 months ago.
1 - There's no such thing as an ideal device, for more than one reason. Ideally you want infinite power gain. That is, the power required to actuate the switch (gate capacitance, base current, etc) is zero while the output power handling (current and voltage) is infinite with zero losses (resistive, capacitive or inductive). They would also be infinitely fast. However, if such a device were to exist, it would be terrible for EMI. In fact, many MOSFET drives have gate resistances explicitly placed to avoid such problems.
2 - Highly variable. Technology changes and the MOSFET vs BJT war has swung back and forth many times since the beginning of time. Let's say with discrete (not die level) devices, I would favour BJTs. Its possible to switch a 2N2222 (small capacity to me) at 1MHz with minimal components (additional R, C and D). A similar MOSFET would require a dedicated gate drive to run that fast.
3 - DC to DC converters are built almost completely with MOSFETs these days. Its just how the losses play out with the devices available on the market. It wasn't too long ago where MC34063As where very common (BJT driver).
Answered 4 years, 10 months ago.
These are excellent questions. Like all good engineering questions, the answer is
"it depends on a lot of details that are not included in your question."
1) One way to think about an ideal power electronic device is that it has two connections where charged particle (typically electrons) flow while being controlled by a third connection. All electronic devices from vacuum tubes to the most modern semiconductors are variants of this basic idea. There is a set of fundamental physical equations that govern the limitations of this type of devices. Electronics is usually not taught by starting with these equations. Instead, students need to learn the more practical aspects. Most engineers learn which devices are good for different applications without ever learning the basic physics that shows the fundamental comparison between all types of devices. This is for a good reason: knowing these equations is interesting, but they rarely have practical use.
The choose a device that is most ideal, a design objective needs to be stated. The device that best demonstrates the physics is the vacuum tube. The device that is best for computing is the MOSFET. If it were possible to make a vacuum tube as small as a MOSFET, the vacuum tube would have much higher performance than a MOSFET. But no one knows how to do that! The physics equations don't tell you that no one knows how to design an extremely small vacuum tube.
2) For high frequency, you need to choose 'how high?' At 110GHz the best device might be Indium Phosphide. At 1MHz it might be Gallium Nitride. At 30 petaHz (X-rays) a vacuum tube is the best. To control a 60Hz motor, a mechanical relay might be a good choice.
The most common switching device is Silicon. The transistor types are chosen based on the needs of the specific circuit. MOSFETs are probably in the most designs. BJT might be in more devices because they are often used in low-cost high-volume products.
3) Utility-scale power typically uses Silicon thyristors, last I checked. The article en.wikipedia.org/wiki/Thyristor is good and answers your question. Newer, better devices might be Silicon Carbide thyristors.
If you want to see modern power devices, here are a few: http://www.genesicsemi.com/images/products_sic/sjt/GA08JT17-247.pdf
They are expensive, though. It would be better to learn on something cheap, because you will blow some up:
Answered 4 years, 10 months ago.