The worst and most difficult is when you have to handle with projects in which you must create something that you have not found in schematics. Things goes far worst when nobody else have. I created a very simple tube-IC preamp , which i plug in a final stage NAD amplifier and test it in comparison with a McLaren with a Dynaudio set. Although i had 1000 times more distortion in 1khz the votes of professionalists (including maclaren owner where 4 of 4 for tube-NAD).It took me about 3 months. Then i designed a predesigned mosfet amplifier with National LME49830TB. It was relative easy. Since then I try for 8 months to design a full bridge SPM and i'm stuck. There are major problems. In fact i maybe miss some theory. Can't find out how can you keep voltage constant and clear from ripples in high energy variations. I need +-70Volts/12Amps output from 220AC mains. There are many SPMs in the internet for 50-100Euro but i doubt if they'll work. If anyone knows, i need a 800W quasi resonant full bridge 100Mhz(at least) PS. Tried schematics with LTC3722-2. (simulations seems wrong). Any suggestions? Any idea? Any experience?
100 Mhz ? - what high power FET could handle that high frequency? Why is that necessary?
800W + Full-bridge - for that power half-bridge shouldn't be better?
At 100kHz you can easily handle 800W with small cores (ETD44), and common FETs or IGBTs, and with quasi-resoant it should be low-noise, with minimal filtering
800W + Full-bridge - for that power half-bridge shouldn't be better?
At 100kHz you can easily handle 800W with small cores (ETD44), and common FETs or IGBTs, and with quasi-resoant it should be low-noise, with minimal filtering
Thank you for your response. why 100Mhz? This is because the EM noise from cores will definitelly exist. The audio spectrum is till 20khz. Lets suppose that we hear just in 15Khz. In 15Khz-20kHz the ringind from EM nose will be of 3-4th order low, so the frequency - noise response will be better in the final product. Why full bridge? This is because the half bridge MOSFETS will consume much more energy and probably they will need a fan cooling. My target is to put a large cooling core but no fan at all. Also, the full bridge topology can be used in higher power demand SPMs. The cores will not be a problem. FAIRCHILD has some ultra fast high energy mosfets. Any schematics idea?
I have a phase shift modulated bridge design using the 74C14 (CD40106) and discrete parts. I share it with anyone interested, but the LTspice file is the way I do so because I often draw my diagrams unusually tight and hard for a lot of other people to follow. it has a lower clock frequency, but you might try speeding up the MOSFET turn-on times. Reducing the level shifter pull-up resistor is one way to do so. i have attached it if you are interested.
It didn't occur to me that the CD4000 library ought to be included with the phase shift bridge circuit, in the folder. A great tip for LTspice fans like me is to add the CD4000 library to the main components library so that the CD40106 or any other common CMOS device can be selected from the drop down menu in the tool bar. I am re-uploading the phase shift bridge power supply folder with the CD4000 library file included.
Hmm, I wonder why. One ameliorating factor for mine should be that the switching frequency i use is pretty low, and I often add some extra bypass capacitance on each MOSFET totem pole.
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As I said it's in the secondary. When diode turns off, current goes negative through it for some time (how far depends on type and recovery charge) and then diode recovers. The latter happens really fast.
The resonant circuit containing Ls and Cs is excited and rings quite badly. The reason is purposely increased Ls - to store enough energy for ZVS condition. You may start filter with capacitor instead of inductor but then it's another story.
Schottky helps somewhat but it has substantial capacitance.
BAA
Guys, since you both seem so experienced with switching power supplies, i would like to ask you some more questions. Consider a Full bridge circuit with driver the LTC3722, it is a synchronus dual mode full bridge phase modulated IC. To eliminate the EMI and need of driving transformer i would like to use the FAN7393 High voltage hi-low side mosfet driver IC. The bridge IC's will be FQPF10N60C and the output IC's for synchronization will be FQB55N10 or FDD86102 (for mosfets there are lot of Spice models in fairchild site). I wonder how can i lead the input pusles to the primary windong of transformer, in a pseudo sinusoidal waveform instead of pulse waveform. If you have any idea or any negative comment, please inform me. Also i would like to know if anyone has any idea on this...
Lets say that our system runs in 100W with a small pulse duration. Suddenly the system swallows a 500Wpeak with a reasonable duration. From my knowlege this will result in a significant voltage variation and a serius change in the system transfer function. Is it possible to have an output capacitor steady charged and with a winding on the ouput supply line to measure the current peak and turn on the charged capacitor to give time to the circuit to change its pulse duration smoothly? Is it a stupid technique?
Any comment is acceptable.
Guys, since you both seem so experienced with switching power supplies, i would like to ask you some more questions. Consider a Full bridge circuit with driver the LTC3722, it is a synchronus dual mode full bridge phase modulated IC. To eliminate the EMI and need of driving transformer i would like to use the FAN7393 High voltage hi-low side mosfet driver IC. The bridge IC's will be FQPF10N60C and the output IC's for synchronization will be FQB55N10 or FDD86102 (for mosfets there are lot of Spice models in fairchild site). I wonder how can i lead the input pusles to the primary windong of transformer, in a pseudo sinusoidal waveform instead of pulse waveform. If you have any idea or any negative comment, please inform me. Also i would like to know if anyone has any idea on this...
Lets say that our system runs in 100W with a small pulse duration. Suddenly the system swallows a 500Wpeak with a reasonable duration. From my knowlege this will result in a significant voltage variation and a serius change in the system transfer function. Is it possible to have an output capacitor steady charged and with a winding on the ouput supply line to measure the current peak and turn on the charged capacitor to give time to the circuit to change its pulse duration smoothly? Is it a stupid technique?
Any comment is acceptable.
I experimented with synchronous rectification in the past, but didn't go very far with it.
That idea of storing separate reserve power in a capacitor seems good. I think it could be done by just making the output filter capacitor that size. I like your openness to ideas.
I experimented with synchronous rectification in the past, but didn't go very far with it.
That idea of storing separate reserve power in a capacitor seems good. I think it could be done by just making the output filter capacitor that size. I like your openness to ideas.
You are probably wright. By just replace the output filter capacitor in other energy size you can have the demanding energy, but i don't know if the pulse modulator will be in place to expand it's pulse width in proper time without noise generation. (In any case i start to consider myself as a just talker). So, i'll start a design and send you for comments. Then you may help from your experience.
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