how much power can i get fro IRFZ44?

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N-Channel

N-Channel

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Joined 2003
MOSFET P diss

If you know the Rds (on) of the 'Z44, and the voltage you're working with (in this case, a nominal 12-14V), then you can get a pretty good idea.

If, say, the 'Z44's Rds (on) is 0.026 ohms (just a guess- check the datasheets), and at 12V, you're drawing 20A, then the power dissipated by the MOSFETs will be I^2 x R.

For this example, take 20A, square it, and multiply the product by the R ds (on) of the MOSFET. 20 x 20 x .026 = 10.4W Dissipated, per MOSFET.

If you're going for power supply efficiency, try paralleling the MOSFETs, and the power dissipated by them will be cut in half.
 
EnvisionAudio

EnvisionAudio

Member
Joined 2002
Only in best case circumstances. In the real world, you must derate the component according to environmental and electrical effects. You have junction temperature, thermal resistance and intertia and the SOA of the FET. All of these (and many more) must be considered when designing maximum current capability. Is this going in an automobile? Isn't the heatsink going to be hot in the warmer months? Another derating.

In my experience, 12 IRFZ44N (6 per phase) will handle ~60A continuous in the configuration you state with a switching frequency of 50kHz and "normal" vehicle electrical anamolies (load dumps, etc).
 
Eva

Eva

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Joined 2003
Analyzing only conduction losses in switching circuits is like telling only half the story

There are also switching losses, and sometimes there are also additional losses due to avalanche effect caused by unclamped transformer leakage inductance

Switching losses are strongly dependent on gate drive and rise/fall times, the faster the switching the lower the losses but the higher the EMI radiation and the higher the likelihood to excite RF resonances between PCB tracks and components further increasing EMI

In other words, the power output obtainable from a set of MOSFETs is also dependent on transformer design, layout and gate drive

Are you going to use regulated or unregulated output topology? The analysys is quite different
 
A

Astro Power

Member
Joined 2004
ok........ i will photograph the car amplifier powersupply....

my next question is........

i learn yesterday how to to twist around transformer... of car amplifier...


13.8V = 4 turns.... if i want in the out 45V i will calculate like that:

45\13.8=3.2

3.2x4= 12.8 so i will need to turn 13 turns to get 45V

(of course i need to turn double to get 45V +\-)

now i want to know how amper will out the wire that i twist around with him the transformer....

because i want 45V +\- with 20A.

soo how much diameter the wire(s) need to be?

thanks tamir
 
G

gearheaddruid

Member
Joined 2004
Power from mosfets.

Astro, is that the power supply from a Pyramid? Looks like you have plenty of room for a big supply. Look up in the trading post area for my listing of LITZ wire. There is an explination of why you should use it. It will be much easier to wind the transformer. Your secondary winding should be at least #12 wire if you are using it as a sub woofer amp. I would recommend #10. The primary is going to require a lot of conductor. I would say, double up the big Litz wire (105 strands of #30) for each leg of the primary.

When you start to drive the amp bridged, I would heatsink the drivers that are hanging on the perfboard. They are going to get hot!

What part of Israel do you live in? My wife has family in Kfar Saba. Regards, Steve
 
A

Astro Power

Member
Joined 2004
yes ! it is old 2000W pyramid powersupply.... it is look to you a good supply ?

because i want to build a stronger power supply..

and i live in binyamina...it is beside hadera.

and Kfar Saba it is 30 min of drive....from where i live... :)

i find a software:
http://www.hw.cz/software/transforn_calculate/transformer01.exe
it is look like to you reliable ?

thanks tamir



this amplifier work in my car .........already 3 weeks.....

and after 30 min of high volume it is start to make noise...
and if i turn of to cool........it is fix.......

so u thinks it is because the driver transistors??
thay need to be in heatsink?
 
kinser

kinser

Member
Joined 2004
Astro Power,
Its me Kinser,
Sorry for going off topic
I live in Raanana which is close to kfar saba and i would like to know where you buy transformers, becuase im stuck at a dead end! :bawling:
and I have ICQ if you didnt see my reply to "subwoofer amp"
ICQ number: 248-686-489

Kinser
 
G

gearheaddruid

Member
Joined 2004
Haifa toroids.

Hi sss, I would be careful with the toroid you have, it looks like a common mode choke from a mains supply. I think it has a distributed gap in it and may not work well for the power transformer in a smps. It would be great as an output choke after the rectifiers!;) One source of cores that I have used for lower power (<250 watts) is an old flyback core from a big color t.v. Remove the plastic gap spacers so the core halves are touching and wind away. It's cheap and dirty, usually found for free. Another source: old industrial smps made by TDK. with some work you can dismantle the power transformer on these. You will need two identical supplies as one half of the core is usually gapped and you need two ungapped halves. If you are lucky, there will also be some Litz wire on the core you can reuse. Some older t.v. sets and computer monitors had Litz wire on the horizontal width adjustment coil. Regards, Steve
 
Eva

Eva

Member
Joined 2003
Common mode filter cores are *never* gapped *nor* made from iron-powder materials. They are made from standard medium-permeability power ferrites, from high-permeability signal ferrites, or from specific RF-damping low-permeability ferrites depending on RF attenuation requirements and price constraints

Differential mode filters are actually the ones subject to DC currents and are made usually with gapped cores or iron-powder materials
 
G

gearheaddruid

Member
Joined 2004
Core material.

Eva, appreciate the feedback, My experience has been that common mode chokes are more designed to suppress rf ranges and do not work well as an inductor for pp smps. I stand corrected about the distributed gap. I bow to your knowledge. What you wrote makes sense to me as a common mode choke would not need to store energy and would not worry about saturation.

Do not know if you got my other notice Eva, "A woman who speaks smps....) I'm in love!:cloud9:
 
A

Astro Power

Member
Joined 2004
this is the transformer that i will us in my new power supply.

13V+13V~200A in primary 2622W

38V+38V~60A in secondary.

http://www.mamsh.com/1t.jpg
http://www.mamsh.com/2t.jpg

the core is 70X110..... (it is written on the core)

it will be for my car amplifier.

http://www.mamsh.com/111.JPG

i will add output transistors to get a 1600WRMS (brigde) to 1 ohm.


1.but my question is... how much transistors of irfz44 i need to put to my PWM to get the "2622W" of power supply.

2.my next question is... how much output transistors i need to put on any chennel to get 800WRMS - 0.5Ohm. of
2sc5200 and 2sa1943.

(remember it is 1600WRMS on 1 ohm in bridge.)

please do not suggest me other kinds of transistors (pwm\amp).


for more info:
http://www.mamsh.com/info.JPG

thanks allot
tamir
 
Eva

Eva

Member
Joined 2003
This core is not made of ferrite, its an iron-alloy laminate core and it's not suitable for high frequency operation [the core itself will overheat badly as frequency is increased]

Have you characterized your old ferrite cores? This is the very first step to decide the operating frequency and the number of turns
 
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