i recently designed a new boost converter 24v to 240v 0.2A
it is working fine on ltspice for the output voltage and current but when testing the input current i found it up to 24Ka!!
it that true?

note : (i will use uc3843 but as its spice model not working with ltspice i used lt1243 they are very similar)

 

That is a substantial startup transient. It may or may not be real. You are still trying for a boost ratio of 10 which as I have explained is not practical. I suggest you consult a textbook on boost converters to understand why this project may be impractical.

 

That is a substantial startup transient. It may or may not be real. You are still trying for a boost ratio of 10 which as I have explained is not practical. I suggest you consult a textbook on boost converters to understand why this project may be impractical.

but there are boost converter in the market do so and even more than ratio of 10 like yh11068a input 12-24v to 400v

 

24kA is the initial charging current for C1. Is C1 really 25Farads?
25uF gives a peak current of 30A.

 

24kA is the initial charging current for C1. Is C1 really 25Farads?
25uF gives a peak current of 30A.

I edited this c to 100uf, now it is about 7A

 

The current still high i expected to draw 3 or 4 A
How to reduce the current and save the output with no change

 

One thing about properly simulating a circuit is to understand the real world parasitic components which are not explicitly included in the model.
Here, I would add a 0.01 to 0.05 ohm series resistor to the supply voltage. 0.001 ohm may be way too low when you factor wiring and connector resistance.

 

C1 would also have parasitic resistance and inductance.

 

but there are boost converter in the market do so and even more than ratio of 10 like yh11068a input 12-24v to 400v

And you are 100% certain, after looking at a schematic diagram of that commercial product, that it is a boost converter with a boost ratio in excess of 10. If that is what you think then a credibility check might be in order.

 

Probably a different type of circuit, such as an inverter of some kind, would be much more efficient and also much simpler to optimize.

 

And you are 100% certain, after looking at a schematic diagram of that commercial product, that it is a boost converter with a boost ratio in excess of 10. If that is what you think then a credibility check might be in order.

ok, if this ratio is very high for single phase boost converter can two phase boost converter gives this ratio and work probably?

calculationS done based on this PDF
https://digitalcommons.calpoly.edu/cgi/viewcontent.cgi?article=1212&context=theses

Except the output and input capacitors not sure yet but it seems the value here is working!

 

I made some changes.
To help the boost ratio I changed L1 into a transformer. L1, L2 note the inductance and K1 statement.
To help the inrush current I changed V1 to have 100uS of ramp up time. This way C1 & C5 charge up slower.
Changed R1, C4.
Not stable yet but just to show what I would have done.

 

Add a "Rser" parameter for inductances and aluminum capacitors. It is easier to do this by selecting them from the LTspice database. Or in any case look in the base what values in this base are similar in value and voltage. For inductance similar in value and required current.

 

Once again I suggest that an inverter configuration would be smaller and more stable and much simpler to design and optimize. There is at least one IC that will provide a regulated higher output with very few added components.

 

Once again I suggest that an inverter configuration would be smaller and more stable and much simpler to design and optimize. There is at least one IC that will provide a regulated higher output with very few added components.

sorry i did not catch your point, is not inverter convert between ac to dc and vice-versa, why use it while i want to boost 24vdc to 240vdc?

 

sorry i did not catch your point, is not inverter convert between ac to dc and vice-versa, why use it while i want to boost 24vdc to 240vdc?

Inverters are routinely used to convert DC to DC, But there is a serious difference in efficiency with some designs. BOOST switching converters have an area of greatest efficiency at much lower ratios. Besides that, boost supplies also rapidly switch the DC, but wind up storing much more power in the magnetic field of the inductor. THAT is why an inverter of the switch-mode type, with transformer action instead, can deliver better efficiency, and also be less complex to optimize in operation.
So if you do a comparison of the different arrangements versus efficiency you will find that the boost scheme is not the best choice at high step-up ratios. A switch-mode inverter will perform more efficiently and also be simpler to optimize.

 

Inverters are routinely used to convert DC to DC, But there is a serious difference in efficiency with some designs. BOOST switching converters have an area of greatest efficiency at much lower ratios. Besides that, boost supplies also rapidly switch the DC, but wind up storing much more power in the magnetic field of the inductor. THAT is why an inverter of the switch-mode type, with transformer action instead, can deliver better efficiency, and also be less complex to optimize in operation.
So if you do a comparison of the different arrangements versus efficiency you will find that the boost scheme is not the best choice at high step-up ratios. A switch-mode inverter will perform more efficiently and also be simpler to optimize.

Do you have example circuit because all i found is just dc to ac inverters

 

Sometimes these are built like this. Note the red circle where the transformer sets on ground not Vin.

 

OK, RS just posted an example that uses a transformer but puts out DC.Transformer step up ratios are more efficient because they depend on turns ratios rather than more energy being stored in an inductor.

 

From post #12 and #18 the schematic are almost the same thing. Turn ratio is an easy boost!