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Inductor & capacitor design for automatic voltage regulator

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anoop kr

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Hi All
I am designing an Automatic Voltage Regulator(AVR). The Specification of the device is
1). Input Voltage:- 230v AC,50Hz
2). Output Voltage:- 6V-70V DC, 4A
3). Converter:- PWM Using KA3525
4). Output Mosfet Driver:- IR2110
5). Topology Used:- Half Bridge(Using IRF840)

I am so much worried about the lowpass filter design using capacitor and the inductor. I put some values of capacitor and inductor but at that time the mosfets were burned out. I used some softrware for the inductor design but in vain. The Software i used is "MICROMETALS "DESIGN OF INDUCTORS FOR POWER FILTER APPLICATIONS".

I am uploading the circuit diagram also. Somebody please help me:-(
 

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Hi,

your load seems to be an inductive load.
But the output voltage seems to be DC.. or at least carries a lot of DC. Therefore the load current will be dominated by the DC current. This is U_out / R_DC.
R_DC may be very low and thus the current may be very high. Maybe too high.

Klaus
 

Re: Inductor & capacitor design for automatic voltage regulator

yes of course. so how can i calculate the inductor and capacitor values.

- - - Updated - - -

is there any specific formula for calculating the inductor and capacitor values??
 

Hi,

what do you want to achieve?
* reduce EMI?
* generate a clean DC voltage with specified ripple voltage?

For clean DC you need to know: switching frequency, output impedance (or load impedance) at switching frequency, expected ripple voltage.


Klaus
 

Your circuit looks like a parallel resonant converter without the secondary.
Also, i do not see any primary current sensing.

Your circuit also reminds me of a fluorescent ballast driver, but where the fluorescent tube would be, you have an inductor. But then again your controller is fixed frequency , and some variability of switching frequency is best for the above two mentioned converters.
 

i just want to know how to get the exact values of the output inductor(L) and the capacitor(C) for the specified output requirements. Is it possible to replace the output inductor(L) and the capacitor(C) with a fast switching high power diode and a capacitor??. i saw one real circuit like that. Thats why i asked. The inductive load resistance is about 100ohms.
 

ok but your circuit doesnt show a secondary for the half bridge. As it stands you would have an AC current in your "load".
 

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