Yes, it is worth exploring.
As far as I understand, the OP claims to have dissipated 800W with two transistors. It requires a heatsink with about 0.5 K/W at 25 °C ambient temperature. That's no impossible with strong blowers, but sounds questionable for the shown heat sink. In any case, a well considered design would use more transistors in parallel to the benefit of a longer lifetime.how does one keep a Tc = 25C while dissipating 625 watt, with real world case-to-heatsink plus heatsink-to- ambient thermal resistances.
625W is in datasheet mentione Absolute Maximum Power dissipationPlease show me the calculations:
how does one keep a Tc = 25C while dissipating 625 watt, with real world case-to-heatsink plus heatsink-to- ambient thermal resistances.
As far as I understand, the OP claims to have dissipated 800W with two transistors. It requires a heatsink with about 0.5 K/W at 25 °C ambient temperature. That's no impossible with strong blowers, but sounds questionable for the shown heat sink. In any case, a well considered design would use more transistors in parallel to the benefit of a longer lifetime.
I know it's possible, but doubting that the heat sink sketched in post #6 is sufficient. Also suggested to operate the transistors at lower junction temperature.If is used wind tunnel (composed of co-located coolers) or use expensive heatsing as Fischer LA 14 Hollow-fin cooling aggregates is possible realize thermal resistance Rth 0.13 - 0.07 K/W.
Heat sing in post 6 is SK 100 150mm from Fischer, Rth=1.2K/W, if is this heatsing used as one side wind tunnel ceiling AL sheet and apply wind 6m/s have Rth =0.25 K/W.I know it's possible, but doubting that the heat sink sketched in post #6 is sufficient. Also suggested to operate the transistors at lower junction temperature.
In case of doubt, perform a system simulation of analog + digital control loop.
When we are dealing with large currents and loads.I'm not familiar with FET's but I know they can work with 200V of Vds and 100A..
Did you measure the Rth value? What's the fan sound level?Heat sing in post 6 is SK 100 150mm from Fischer, Rth=1.2K/W, if is this heatsing used as one side wind tunnel ceiling AL sheet and apply wind 6m/s have Rth =0.25 K/W.
Make behavioral models for digital controller elements, e.g. time discrete sampling, dead time, PI controller.For simulation I use MULTISIM and I do not know how to simulate digital control.
When we are dealing with large currents and loads.
You need to be aware, 1mili Ohm , for example in connector or in wire, PCB is in power dissipation 10W for 100A
On picture you have 35m Ohm shunt for 100A it is 350W power disipation only on shunt
Similar to that with transistor legs (pin) and soldering to PCB.
The load for such large currents can be dealt with as a "blacksmith's work" or you have to go through the massive parallelization, for example 8MODTET and 8 current shunt then it will be 12,5 A on MOSFET.
Parameters | IRFP260N | FDA50N50 |
Vdss | 200V | 500V |
Rds | 40mOhm | 90mOhm |
Avalanche Current | 50A | 48A |
Operating.temp | 175C | 150C |
Max power disipation | 300W | 625W |
Thermal Resistance J-C | 0,5 C/W | 0,2 C/W |
Csii | 4100pF | 5000pF |
Price in China 5pcs | 3$ | 5$ |
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