Badly in need of help on output inductor design for ZXCD1000 based 500 watts amp

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Evan Shultz said:
They could be referring to the inherent crossover distortion advantage that BD modulation has over AD??
It's a 2 channel triangle carrier based amplifier in bridge configuation, could it do BD modulation?

IMHO, BD could only be done digitally, since it need to detect the signature of signal value and do different processing for + and - . It's fairly easy with numbers, but hardly could accurate with continuous signals.
 
Razor_Edge said:

Right now the Mosfets used are IRF530 and IRF9530 with 10 volts zener. Also, planning to move on to IRF740 for higher powers >500 watts @ 70~90 volts.

Even IRF640/9640 (200V 18A/11A) couldn't handle enough current for 500W, 740 series is too small.

What about your practical results about IRF530/9530?

In my simulation, the two devices have poor Ciss and Crss matching. IRF530 runs much quicker than IRF9530, cause significant degeneration on shoot-though and dead time performance.
 
Good morning with a big big blow....

What about your practical results about IRF530/9530?
In my simulation, the two devices have poor Ciss and Crss matching. IRF530 runs much quicker than IRF9530, cause significant degeneration on shoot-though and dead time performance.

Thanks kenshin for rendering me the simulation results.

Though what you said is correct. Today (about 3 hours back) I tested the setup with 70 volts rails.
Ashtonishingly, the output Mosfet's were really cool for the whole testing duration. But the output filter capacitor (1uf/160 volts) blew up, messing up the whole place... :bawling:

Earlier I had used two 470nf/63 volts caps in parallel. Once they gave up at 35 volts I changed it to 1uf/160 volts. It worked perfectly fine until today when I increased the rail voltage to 70 volts

Can somebody please comment on this. I am sure DIYer's are much more experienced then me...

Today I felt the need of doing simulation before trying out anything. The problem is... I dont know how to do simulation... :apathic: I thought my paper calculations and experience is good enough. :xeye:

Which simulation tool are you using Kenshin..? Please suggest me a roadmap in this direction.


Forgot to mention... that the output filter caps get very hot even at 50 volts but had been working fine for 2 hours last night.
 
hkaplan131 said:
Checkout the Coopper Bussman (Coiltronics) DR and HC series. You might have to parallel a couple coils to get to your inudctance.

http://www.cooperet.com/products/products.cfm?page=high_current_inductors

I am using a DR127-8R2 8.2 uH which handles 12 amps.

What FETs will you use for the 500 watt amp? My rough calulation shows you must be using a 4 ohm speaker to get 150 watts from 35 Volts.

To get to 500 watts you will need a 65 Volt supply. Do you have a FET 16 Amps at 65 Volts?


You are right, I used a 4 ohm speaker with a current of about 4.8 amps... only problem I faced was that it (I dont know how and why) blew up the output filter capacitor (non electrolytic cap). I had to change to 1uf/160 volts (electrolytic) to make it work on that voltage.

I am planning to use paralleled IRF640 and IRF9640 (2 pairs on each leg).

Does somebody know anything better??
 
I am planning to use paralleled IRF640 and IRF9640 (2 pairs on each leg).

Yeh, Dual IRF640 or better :)

Exactly what kind of cap are you using? ESR should be minimal.


Improving layout, turn your mosfets around so the heatsink can act as a shield from EMI to the other mosfet. Heatsinks in between, mosfets on the outside.

Minimizing loops current loops where it counts is important, all effort should be made to ensure critical loops are minimal, some tripath app notes explain this well.

The only simulator worth learning is called LTspice/SwitcherCad from Linear Technologies. It's free.
 
:wave:

classd4sure said:


Yeh, Dual IRF640 or better :)

Exactly what kind of cap are you using? ESR should be minimal.


Thanks a ton for suggestion Chris...

I used locally available caps... just found out, that they are not capable to work even for 100 volts... Bogus voltage ratings... :boggled:

The only simulator worth learning is called LTspice/SwitcherCad from Linear Technologies. It's free.

I would surely check it out... Can you please also tell me how far could they be used in designs. I mean what all sections can be best covered (input, output, output filter section..?) :scratch:
 
Enough that it's worth learning. In that respect it's the same as any other spice simulator. Not perfect. Learning average modelling will bring you even further, I haven't even begun with that yet. Limited info on it, usually just in the form of slides and lecture notes, would be best to have the course I'm sure, or at least a good book. You can play with output stages and feedback networks etc. Steep learning curve, wouldnt' bother if this is a one time thing for you but if you're seriously interested in playing with this stuff more, it's a huge help once you can get around in it. Don't plan on having it mastered after a month of looking at it for an hour every other day. Go through any included tutorials.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.