600/800W 220~230v AC Inverter SMPS from 12v DC

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Hi Adeel
In what kind of circuit it should give you that current ? a switch mode circuit ? what frequency ? and what arrangement ? if you don't mention those parameters , how we can help you ? where is your schematic ? how you expect that we help you with these low informations ?
Best Wishes
Goldsmith
 


thanks for your response. please consider my thread "DC-DC boost converter problem". & let me know for further info .

waiting for response.

thanks in advance
 

thanks for your response. please consider my thread "DC-DC boost converter problem". & let me know for further info .

waiting for response.

thanks in advance
Click to expand...
I fear
Can you add it's address here , please ? because i can't remember that . and now i'm a bit more busy , hence i don't have any time to search and find your thread .
All the best
Goldsmith
 

Dear Goldsmith

here it is. waiting for your response.

thanks
Adeel
 

Hi again
Well , now how can i help you ? how you have designed your inductors ? how you have selected cores ? how about capacitor ? all of these parameters are important for judgement about a boost converter .
If you tell me a bit more explanations about your exact , problem , i can help you more .
Best Wishes
Goldsmith
 

i am using the cores whose snaps are attached in my previous post (yellow/white & green/blue). i have selected it randomly. i started winding the core with 18 AWG wire until my LCR meter gives 300uH.
Capacitor used is 47uF 400V polar.
My problem is that i theoretically should get the peak inductor current of at least 6.5A but in practice i am getting only about 3.5A. Either there is some parasitic resistance or additional inductance that is limiting the current. i am doubtful about the inductance because it seems to be increased during circuit operation. how could verify it if my doubt is correct or otherwise?

please advice

thanks in advance
 

i have selected it randomly
Click to expand...

Hi Adeel
A designer won't select a core randomly . it is not named design !
Would you like that i tell you how to select a core ? ( according to the frequency and power and color ? )
meter gives 300uH.
Capacitor used is 47uF 400V polar.
Click to expand...
How you have calculated those numbers ? again randomly ?

Can you show me your calculations , please ?

All the best
Goldsmith
 

yes please tell me how to select the best core for a particular application. also tell me what is wrong with these cores.

i have measured them & their value is unchanged.

I=V/R*[1-exp(-r*t/L)]
I=12/0.5*[1-exp(-0.5*190u/300u)]
where 0.5 is Rds(on) of IRF740
 

Hi again
For core selection and Magnetic element design , take a look below , please :
https://www.edaboard.com/threads/229615/

Now i have to go , because i'm terribly busy . so , tomorrow i'll have more time to help you more .

Until tomorrow , have a nice time !
Goldsmith
 

Dear Goldsmith,

i have gone through the thread and i found it very useful but is there any procedure to find out the power and frequency of a randomly selected core through some experiments. also consider this **broken link removed**. what kind of transformer it is? what is its core material? what kind of primary winding and wire gauge it has to support a huge current of greater than 40A? Can you provide me the more detailed technical specs of this transformer so that i can made it by myself? please advice

thanks in advance

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Dear Goldsmith,

i have gone through the thread and i found it very useful but is there any procedure to find out the power and frequency of a randomly selected core through some experiments. also consider this **broken link removed**. what kind of transformer it is? what is its core material? what kind of primary winding and wire gauge it has to support a huge current of greater than 40A? Can you provide me the more detailed technical specs of this transformer so that i can made it by myself? please advice

thanks in advance
 

Hi again
As it appears you didn't read , that link carefully . because at end pages of that thread i have added some tables which can handle your aim . why you didn't read that thread carefully ?
Best Wishes
Goldsmith
 

Due to some official and personal work pressure I could not give full concentration in my Inverter making task. It is advancing in very slow motion...
Recently I bought two MOSFET driver IC IRF2110, four IRF3205 and some diodes (1N4007). But for such high frequency operation (50kHz) this diode is not suitable. To complete converter I need to buy some Schottky diode. Now, I've the following question in my mind need comments from you -
1. Do I need Freewheeling diode for MOSFET bridge configuration?
2. If yes, can I use normal diode (1N4007) as freewheeling diode?
3. Which value of recovery time should I use for 50kHz operation? Also refer some part number for this.
4. What will be output waveform after rectification?
5. How can I design filter for this sample case? If I get some idea about filter I'll try to manage required ferrite core when I'll go to market for Schottky diode.
 

1. Do I need Freewheeling diode for MOSFET bridge configuration?
Click to expand...
Most of the switching mosfets have internally anti parallel diodes . ( unless some types of them )

2. If yes, can I use normal diode (1N4007) as freewheeling diode?
Click to expand...
Of course not ! do you know about Trr ? you'd better to take a look at concept of Trr .
4. What will be output waveform after rectification?
Click to expand...
What ? what kind of rectifier ? which section of your circuit ?
5. How can I design filter for this sample case? If I get some idea about filter I'll try to manage required ferrite core when I'll go to market for Schottky diode.
Click to expand...
FIlter of what section ? first section or 2nd section ? ( both are 2nd order LC filters ) but latest stage , needs more attention .
Good luck
Goldsmith
 

As IRF3205 has anti parallel diode, I do not need anymore diode for freewheeling purposes. Diode having Trr lower is better. Could you suggest some part number which I can use?

For now, I wanted to design filter for the first stage i.e, converter stage. 400-450v 50kHz square wave will be rectified with a bridge rectifier.
 

Hi Sam
. Could you suggest some part number which I can use?
Click to expand...
Yes , of course . if you need diodes , you should mention your power rating ( that diode should be able to handle ) but , these are some usual good points ! ( from low power up to high power ) . 1n4148/
FR104 /UF4007 /SB1020 op to 10100/ MUR1560 /DSSk48 / MUR1060CT or ... etc
For now, I wanted to design filter for the first stage i.e, converter stage. 400-450v 50kHz square wave will be rectified with a bridge rectifier.
Click to expand...
Humm i think you're referring to the DC voltage increasing stage , well , are you familiar with formulas of an H bridge filter design ? if no , i can give you two formula , one for , out put capacitor and the other one is for inductor .
All the best
Goldsmith
 

Thanks Goldsmith,
For 50kHz 400v with 350-400w output, 1A-2A current ratting of Schottky diode should be okay.
i can give you two formula , one for , out put capacitor and the other one is for inductor .
Click to expand...
Yes, please give me the formula.
 

If you haven't already, going through this design may help clear some of your doubts:
**broken link removed**
 

Yes, please give me the formula.
Click to expand...
L=0.5vo*t/Ion

C=(80*10^-6 )*di/Vr
By the way , i agree with Tahmid , you'd better to take a look at his literature .
Good luck
GOldsmith
 

Converter spec -
According to the formula given in the ST doc shared by Tahmid [ Lmin=(Vin*N2/N1-Vout)*ton/dI ]
Ripple current, dI=15% of Iout=0.15A
So, L=(12*33-325)*9us/0.15=4.26mH

I cannot understand this formula - L=0.5vo*t/Ion
So, cannot verify the result. Could you please check and explain this simple formula and help me to verify the result?

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For capacitance measurement the formula is C=1/8(dI/dVo)*Ts
Switching time, Ts=20us for 50kHz frequency (not sure whether it is right or wrong)
dVo=0.1%of Vo=325*0.001=0.325v

So, C=1/8(0.15/.325)*20=1.15uF
Is it okay?
 
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Hi Sam
To prevent such high values , you can increase frequency of operation of this stage up to 200KHZ , as well ! ( because a 630V or 400 V capacitor , with low ESR and low ESL with value of 1uf seems a bit expensive and large )
Good luck
Goldsmith

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Switching time, Ts=20us for 50kHz frequency (not sure whether it is right or wrong)
Click to expand...
BTW : why you have doubt about it ? TS means switching frequency . so 1/50*10^3 =20usec .
so it's true .
 

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