Current Amplifier

[ericgibbs]

No. it's a 12v battery.
I am attaching the block diagram, what i was thinking that i would design my circuit in this manner. but you people are saying that this is not very efficient so i'll change my idea according to yours.

Thanks

So you are considering using a square wave drive to the motor.?

On your diagram for the power amp, if you have a step up transformer, say 12V to 165V, where the 165V has to supply 2.4 Amps, this will mean the power amp will require a current rating of at least 14 Amps, assuming 100% efficiency.

Can you explain exactly what the 165Vac 300Hz motor is going to be used for.?

 

[yasir_ali]

no. this motor requires Sine wave as i told you before too.


I am going to use this motor in my Wood working firm
isn't it possible to drive this motor using these parameters we have?

 

[Hero999]

I think it would be cheaper to just buy a motor with the correct voltage and frequency rating for the mains in your area.

You'll also save money on your electricity bill because converting the mains voltage to the correct voltage for your motor wastes half the energy the motor uses.

Sorry I think you should scrap the whole project but it's your choice of course.

 

[yasir_ali]

@ Hero
ok. i understand that. i'll try to find one that can fit to my requirement. but i still want to try my self so can you just send a block diagram of how can i achieve this. i have a 12v truck size battery i want sine wave at output with 300Hz, 165v and 2.4A. and any one can also send me any block diagram regarding it.


Thanks

 

[Hero999]

Well you've already done the block diagram which seems correct to me. The power amplifier can just be an audio amplifier. The transformer can be a 6V to 120V mains transformer (because the frequency is higher, you can safely over-voltage it) but good luck getting hold of one rated to 400W.

If it's run from a battery, efficiency is even more important.

How much did the motor cost?

I can help you find a 400W 12VDC motor if you like. What's your location?

 

[ericgibbs]

but i still want to try my self so can you just send a block diagram of how can i achieve this. i have a 12v truck size battery i want sine wave at output with 300Hz, 165v and 2.4A. and any one can also send me any block diagram regarding it.
Thanks

hi yasir_ali,
Look at this block diagram, the project is not really feasible.

Powering from a 12V car battery, you require a 500VA 12Vdc to 165Vrms 300Hz sine wave inverter.

 

[yasir_ali]

Thanks Hero And Eric a lot.

@ Hero
i live in Pakistan. and i just found this motor in a junk store.

@Eric

Thanks Eric for your help and the Block diagram. i'll use the same block diagram in my design.

thanks a lot

 

[Hero999]

My advice is sell it on ebay for possibly more than you bought it for in the first place and look for a 400W 12V motor from ebay or another junk store.

 

[yasir_ali]

ok. Hero. But Hero when problems arises you start learning. and believe me a learned a lot just talking on this project. and some other ideas are arising in my mind. But thanks to you guys that you helped me a lot and just the block diagram. i'll try to work on it.

ok tell me last think that in post # 19 Eric said "If the 'η' of the inverter was say, 70% thats approx 35A." how did you calculated this or how did he got to 35A?

Thanks

 

[Hero999]

I'll try to answer that in Eric's absence, no doubt he'll be quick to correct me if I'm wrong.

It's probably and educated guess. The maximum theoretical efficiency of a class AB amplifier is 78.5%, in reality it'll be less, Eric probably it'll be about 70% in practise. I think the efficiency of the whole system will be less than 70% because there will be some losses in the transformer.

Electronic amplifier - Wikipedia, the free encyclopedia