Power Electronics - MOSFET Power Losses 

sry but this is not for new students in my opinion,

I think their intention is only to consider the case when the current I_DS is positive, for which the intrinsic diode does not conduct.

anjali nosaria nice vedio. #PowerElectronicsAPracticalApproach

Excuse me, but I have the same question. Have you found the answer to yours?

@@mostafasadek2943 Hello, did you find the answer?

@@ADGGMB I believe it's 0.02. 100% corresponds to D=1. Similarly a 2% means D=0.02.

2% duty cycle means D=0.02

I also wanna know

it affects the Ton and Toff calculation, the Cgs and Cds are the capacitance between the gate-source and drain-source, The components and voltage level that you will switch the gate, will interact directy with the capacitance (Cgs) and consequently the time to reach the threshold saturation. In that case, as quick you reach this threshold smaller wil be the energy dissipated.

yes they are, you messed up your math somewhere. Vds x I = 10Amps x 50mOhms = 500mVolts ... so then 500mVolts x 10Amps is 5W @ 100% duty cycle. Like wise with the other equation 10^2 x 50mOhms also equals 5W

Hello, Abed, greetings from Bosnia! Are you trying to make a MOSFET-based dummy DC load? Or what are you trying to acomplish? Please be more specific.

@@edinfific2576 mosfet based dummy load Dc 1500w power . Can test 100v 50amp with out getting the mosfets exploded .

@@abeditani8293 I was going to suggest these 2 projects: www.codrey.com/electronic-circuits/simple-electronic-dc-load/ hackaday.com/2017/02/28/beefy-100-amp-electronic-load-uses-two-mosfets/ but I came across your other comment where you have already made a similar device. All I can suggest to you is to do the following: 1. Use more MOSFETs in parallel (as many as 10-15) 2. Use the thermal paste used for computer CPUs, such as MX-2 3. Place a copper pad under the MOSFETs which would take the heat away significantly faster than the aluminum itself. Basicallly a small square flat block of copper on top of a VERY large aluminum heatsink with many fins 4. Place a few large fans on the heatsink to keep its temperature down under maximum load. Just look at the CPU heatsinks and fans, consider that they take away over 100W of heat, to give you an idea of how much heatsink and fan surface you need for sufficient cooling 5. Consider even water cooling if necessary, either by immersing a portion of the heatsink in a large bucket of water, or by using pipes to run the water through your heatsink. 1500W is a lot of power, almost as much as the water heater which takes an hour and a half to heat up 50 liters of water. 6. Since your dummy load likely doesn't need high speed MOSFETS, all you have to worry about is their voltage, current and power rating, and connecting their gates in parallel shouldn't affect the behavior of the circuit, since they use practically no current at DC or very slow changing drive voltages.

@@edinfific2576 yes . I don't want the mosfet to be high speed but I want it fast respond in the gate Soo it can responded very quickly from the feed back . But I have too much problem to control mosfet in voltage above 60v with 4amp . It just get exploded before even get temperature rise to 60c. I think that I need special specific mosfet for this subject

@@abeditani8293 Devil is in the detsils. I had once tried using a MOSFET on 200+ volts DC from solar panels, and I used a 16V zener diode to protect the gate from surges. The gate was still damaged and I for months I didn't know why. Later I realized that a zener diode of less than 1W power rating has a very poor surge/transient response, and it doesn't conduct quickly enough. Another issue I have discovered accidentally in a darasheet just 2-3 days ago is that a MOSFET's Vds rating is significantly reduced when you apply a reverse bias to the gate. Same thing with your problem: there are some details you have missed in the datasheets or in your circuit. Just like some people have suggested, the power applied to your MOSFET is too high for it and your cooling may also be poor. Without seeing the actual circuit loading it, and knowing the exact MOSFET model, I can't help you much further.

It is because of the energy dissipation area (red triangle), which is like to calculate de triangle area : Area= (base*height)/2. The ID*VDD is the "height" , the Ton is the "base" and the *1/2 is divided by 2.

It is called the mosfet "body diode". By design, all mosfets has a reverse body diode that makes the mosfet drive current in the opposite direction even if the mosfet is OFF.

No, the expression is correct, and you are also correct that the current is less than 10 amps, which is shown in the equation. The RMS current is I*SQRT(Duty Cycle). Since the power loss is calculated by Irms^2*R, Irms^2 = [I*SQRT(Duty Cycle)]^2, which simplifies to I^2*D, so the conduction power loss is I^2*D*Rds,on

What's the current, do you have a heatsink ?

@@Antagon666 5A at 20v . So I have a 100W pure heating up inside the mosfet in the DC region . I need to reach 300W demand of ( 60v at 5A ) My mosfet get dead in 40v 5A even if I have big heathink

Well that's non intended way of using a MOSFET. In order to dissipate 300W of heat, you would need to keep it's package temperature at 25C. And there is no freaking way to cool 300W with the to247 package, because the contact area is simply too small with the heatsink. And the power rating decreases with temperature.. at 100°C, the maximum sustainable power dissipation drops to 100W. It has nothing to do with DC rating of MOSFET, it really is 300W for really short amount of time, until it heats up. So the solution ? 1)Use transistor with a much bigger package size 2) use at least 5 irfp260 in parallel, to spread the power dissipation over a larger area!

@@Antagon666 yes your right . There no way to be exactly to dissipated more than 180w with TO247 package what ever mosfet or IGBT model you use . The area is not enough to transfer this big heating . Can I install like 5 of them all is same one input gate with out problem or corruption with the input mosfet control signal ?

bro??

@@rocksonrong8401 It's a proper stare right in to your soul. I mean the first rule of filmography, don't stare into the camera the whole time, looks really unnatural and unnerving.

www.electronics-lab.com/project/5v-to-12v-step-up-dc-dc-converter/

A voltage regulator needs a voltage higher than the output voltage to work properly. A Lm7812 needs at least 1V higher or 13V input (check datasheet for minimum voltage input).

You can use a circuit booster (based on a circuit voltage doubler DC to DC) where any "clock" can be used (NE555, Schmith Hex trigger, ... ) to raise the voltage at least at the desirable voltage, and then a TL431 (a shunt regulator, instead of a regulator in series ) to get the final voltage. (While a LM7812 takes a toll of 1V, the TL431 may take no voltage at all, since it is in parallel with the load, as a sharply defined voltage Zener diode would do.)