How to test an IGBT with a multimeter presented by Katie Nyberg for Galco TV. Buy the items featured in this video at 800-337-1720 or visit: http://www.galco. Bjt; mosfet; igbt; scr; smd code; packages; apps mosfet. 2n5484 2sk2040 apt1004r2gn buz905d hat1044m irf9611 irfs541. The IGBT is a cross between the bipolar and MOSFET transistor s (s ee figure 1). The IGBT has the output switching and conduction characteristics of a bipolar transistor but is voltage -controlled like a.
The MOSFET or IGBT question is a recurring one. We all have faced this question once. Knowing which type of FET to go for. And the question is still going-on. You can look for the web, and you find an IGBT manufacturer’s e-book about how IGBT’s are such a good solutions for so many applications. But you may also find an e-book teaching you about MOSFETs, their superiority, and how you could use them in almost all of your designs. If this book happens to be written by a famous MOSFET manufacturer, it’s a total coincidence of course…
When an FET is conducting, this channel resistance is commonly known as R DS(ON) and is at its minimum resistive value when V GS = 0. Thus a high R DS(ON) value results in a low I DSS and vice versa. So a JFET can be biased to operate as a constant current source device at any current value below its saturation current, I DSS when V GS equals. Might be surprising, but FET technology was invented in 1930, some 20 years before the bipolar transistor. The first signal level FET transistors were built in the late 1950’s while power MOSFETs have been available from the mid 70’s. Today, millions of MOSFET transistors are integrated in modern.
It reminds me of Transphorm’s former CEO presentation during a Keynote at APEC. He showed us a slide (actually one that I made back when I was at Yole Développement), that he twisted to mock how SiC, GaN and Super Junction MOSFET actors view the same situation.
A great way to teach how marketing and vision alter a message supposed to be objective at first (and why consulting companies like Point The Gap have clear view :-) ).
Figure 1: Transphorm’s CEO presented these picture during APEC keynote sessions: The truth about marketing your products.
So, I’m not here to reveal you a hidden truth for generations (of IGBTs). There is no hidden truth.
It’s what « they » said… All the people you met and asked the question. But each time you read a new article on the subject, it becomes blurry. Let’s make things a little bit clearer for everyone.
There are a few cases where the MOSFET or IGBT question is non-applicable:
- All applications requiring 1700V or higher breakdown voltage for the switches
- Rail traction, Wind turbines, Grid T&D, Central inverters for utility scale PV, high power motor drives…
- This breakdown voltage requirement comes mostly from the DC-bus voltage. This bus in motor drive or generator as an example, is the one that conveys rectified DC power to the DC/AC conversion part. This bus, loaded with capacitors to stabilize and filter current, may have a design at 1000V+. This make you have to use 1700V devices or more.
- All applications at very low voltage:
- Apart from flash light triggering in cameras (300V IGBTs). You will always go for a MOSFET. From 5V to 400V. Period. It’s smaller, faster, better and sometimes stronger.
- This includes a load of consumer applications, embedded power conversion to power-up all sorts of functions inside all the electronics you have at home or carry everywhere.
So where does the question applies? For all the stuff between 400V and 1700V.
You can have:
- Consumer applications: like AC/DC adapters for laptops, tablets and electronics
- Renewable energy with PV inverter for residential, but also micro-inverters.
- All the industries using the medium and small range of motor drives (conveyors and/or belts)
- All small/medium power UPS, in data centers, SMEs, industries…
- And so many other applications…
MOSFETs are good because they are fast. Their switching frequency can go up to several 100MHz. And it’s their main advantage. You also have to think about and Include Super Junction MOSFET in the story. We will write an article about the history of Super Junction MOSFET. But remember that SJ MOSFET have even better characteristics compared to MOSFET. They are also more expensive.
On the other hand, IGBTs can handle more power, meaning that at a comparable voltage, they outperform MOSFETs in current handling capability.
Igbt Fet 차이점
This is the main idea and it comes from losses. All transistor have losses. If we highly simplify the problem, you end-up with two type of losses: Conduction losses and switching losses, respectively happening during conduction mode, or at switching on/off or off/on (you could guess that, right?).
So what happens is that:
- IGBT have lower conduction losses but higher switching losses compared to the best Super Junction MOSFETs
- MOSFETs in general and especially Super Junction MOSFETs, have low conduction losses (the famous RdsON they advertise everywhere) but have higher conduction losses compared to IGBT
And this is the key thing you have to keep in mind.
Next generation compound semiconductor devices are not in the party yet. They are too expensive for you, and you better let another niche applications and adventurous company put Wide band gap semiconductor on the market. But you better watch and try the devices, validate them and get ready to launch.
Igbt Fet 損失
Though the choice is still blurry for now: GaN FeT should be used for voltages up to 1200V. SiC is giving it’s best at high and very high voltage: 1700V but, based on R&D, it’s outstanding at voltages up to 10kV.
It’s still an unclear boundary. So far, GaN is available at 600V only (1200V are samples).
SiC begins to be used, for very specific applications.
MOSFETs and IGBTs are now becoming a commodity: More and more Chinese companies are able to manufacture IGBTs. Only early generation and simple device designs are available from them, but that’s a sign. On the other side, Infineon recently announced that they are moving some MOSFETs (40V OptiMOS) to their Dresden 12in. (300mm) wafer fab. It’s becoming common and cheap to have Power MOSFETs and IGBTs.
But the market of GaN and SiC is not at it’s breakeven point. Investment is what make manufacturers survive, not sales. This makes us tell it’s early.
But mainly frequency. They are still king on their own voltage (low for MOSFET, and high for IGBT). but between 400V and 1700V, you have to choose. Look at the losses, the on and off time, the frequency of your applications, but also now you are looking at the footprint (MOSFET generally have small packages).
Keeping in mind these points:
- IGBT have lower conduction losses but higher switching losses compared to the best Super Junction MOSFETs
- MOSFETs in general and especially Super Junction MOSFETs, have low conduction losses (the famous RdsON they advertise everywhere) but have higher conduction losses compared to IGBT.
MOSFET Vs IGBT
In today’s world there are wide varieties of solid-state, switch-mode, power-supply transistors to perform switching operations in power-electronic systems. All these have their own specifications in terms of current, voltage, switching speed, load, driver circuitry and temperature. Each one has its limitations and advantages as well, but its usage depends on the requirements of the application.
In most of the switching applications Metal-Oxide Semiconductor Filed Effect Transistor (MOSFET) and Insulated Gate Bipolar Transistors (IGBTs) are predominant than the other switching devices due to their superior characteristics. These applications include Uninterruptable Power Supplies (UPS), Solar Inverters and Converters, various motor driver systems, Pulse Width Modulation (PWM) technique based applications, Switch Mode Power Supplies (SMPS), etc.
Let us see the prominent differences that make these switching devices suitable for appropriate applications. In this regard, the description of the following two switching devices is pertinent.
High-Voltage Power MOSFET
Power MOSFET
MOSFET is a most commonly used switching device, which is voltage-controlled power device unlike the BJT, which is a current controlled device. MOSFET is a low-current, low-voltage and high-frequency switching device. It consists of three terminals: gate, drain and source. It comes with two different modes: enhancement and depletion modes and the MOSFETs can be P-channel or N-channel MOSFETs. MOSFETs vary depending on the voltage level of the gate terminal.
In a depletion mode, maximum conductance takes place between the source and the drain if there is no voltage at the gate terminal, whereas a positive or negative voltage at the gate decreases the conductivity. In an enhancement mode, the MOSFET doesn’t conduct if there is no voltage at the gate terminal, and if the voltage is more, conduction takes place.
If the positive voltage is more than the threshold level applied between the gate and the source, then it creates a conduction layer by accumulating electrons. This layer is formed between the oxide layer and the P-substrate layer by pushing away the holes from the P-substrate and attracting the electrons in the N-layer. With the increase in the gate to source voltage, the size of this conduction layer increases resulting in the flow of more current from the source to the drain. In this way, MOSFET comes into conduction mode by the application of voltage across the gate and source.
MOSFET can be turned off by decreasing the gate to source voltage to below the threshold level of it. Sometimes a BJT current is required to trigger it though the MOSFET is a voltage controlled switch. It also has a body-drain diode useful in dealing with freewheeling current applications. Because its on-state resistance is low, on-state losses are also lower. MOSFETs can operate at high frequencies and low voltages and are perfectly suitable for faster switching operations with low-voltage drops. But these are restricted to be used at higher operating voltages in the range of around 500V.
IGBT (Insulated Gate Bipolar Transistor)
IGBT is designed by combining the features of both MOSFET and BJT in monolithic form. As the BJTs have high current handling capacity and MOSFET control is easy, IGBTs are preferred for medium to high-power applications. It is a minority charge carrier device and has high input impedance.
Igbt Vs Mosfet
It has three terminals: Emitter, Collector and Gate. The Gate is a control terminal, whereas the collector and emitter terminals are associated for conduction path. IGBT is a four-layer structure P-N-P-N same as that of thyristors. The below figure shows different layers of IGBT, wherein the flow of electrons through the drift region and the channel draw more holes into the drift region towards the emitter. Because the current flow is composed of the holes and electrons, the current is of bipolar nature.
Igbt Vs Mosfet Inverter
IGBT Structure
Similar to the MOSFET, when the positive gate bias is applied, it allows the inversion of P-base region under the gate and creates N-channel. During this state, the resistance of n- layer is reduced rapidly when the positive holes are injected from the p+ layer to the n- layer. This makes the IGBT to handle more currents than the MOSFET due to lower conduction losses. For turning it off – the negative bias at the gate or lowering the gate voltage to a threshold level makes it off due to no injection of holes to the N region.
Difference between Insulated Gate Bipolar Transistor (IGBTs) and High-Voltage Power MOSFETs
Igbt Vs Fet
- MOSFET is a majority carrier device wherein the conduction is by electrons’ flow, whereas IGBT is a current flow comprising both electrons and holes. As discussed above, the injection of minority carriers (holes) to the drift region significantly reduces on-stage voltage due to conduction modulation. This is the advantage of low on-state voltage drop compared to MOSFET which is a smaller chip size and less expensive device.
- IGBT is made up of emitter, collector and gate terminals, whereas MOSFET consists of source, drain and gate terminals.
- IGBT usage is predominated for higher voltage applications as it is unipolar and requires additional freewheeling diode for the reverse flow of current. Because of this additional diode across the IGBT – it gives very high performance compared to the MOSFET.
- MOSFET and IGBT structures look very similar except for the P-substrate below the N substrate. Due to this extra layer, the conductivity is increased by the injection of holes that also reduces the on-state voltage as discussed above.
- MOSFET is rated at a voltage of about 600 volts, whereas IGBT is rated at a voltage of about1400V range. Therefore, at high voltages current becomes low eventually resulting in low switching losses.
- IGBT is preferred for low frequency (Less than 20 KHz), high voltage (more than 1000V), small or narrow load or line variations; low duty cycle, high operating temperature; and, more than 5kw output power rating applications; whereas MOSFET is preferred for wide load or line variations, low voltage (Less than 250V), large duty cycles and high frequency (more than 200KHz) applications.
- IGBT typical applications include Uninterruptable Power supplies (UPS), low-power lighting, motor control and welding applications, Switch Mode Power Supplies (SMPS), battery charging, etc., but compared to MOSFET, IGBT is predominated in several applications.
Difference between IGBT and MOSFET
In the above diagram, you can observe some comparisons of IGBT and MOSFET based on their model with ratings. Therefore, for choosing switching devices, especially IGBT and MOSFET devices there are larger parameters to be considered for the corresponding applications in power electronic field. For any application-based projects on these devices, you can contact us by commenting below.
Photo Credits:
- Power MOSFET by nlvocables
- MOSFET Structure by circuitstoday
- Insulated Gate Bipolar Transistor by cloudfront
- IGBT Structure by lchu
- Difference between IGBT and MOSFET by powersystemsdesign