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  1. Closed: Re: How to choose right PWM frequency for 3 phase ac motor

    look at the igbt's you will be using - read the data sheet carefully - compute the worst case conduction and switching losses at 20kHz - see how the switching losses go up at the freq goes up,...
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    Closed: Re: 230VAC PWM LED bulb dimmer

    If you ran the 555 off 12V - you could then direct drive a 700/800V mosfet with ease from the 555, - assuming you can common up the gnds on the two ckts, actually the CMOS 555 ( e.g. TLC555 ) ...
  3. Closed: Re: LLC converter vs Dual cascaded Buck….1000V to 48V at 500W output…no isolation ne

    if the layout is symmetric and the fets/diodes the same - the odds are good that they will share to +/- 20% for fixed gate drive...

    how is you 1kv -> 48V coming along ..?
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    Closed: Re: Feedback less PushPull Converter

    the only way to operate under the inference that Vo = D. Vin ( for 1:1:1 turns ratio ) is to use heavy subbers on the mosfets and o/p diodes - this will give you ideal text book waveforms...
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    Closed: Re: 230VAC PWM LED bulb dimmer

    What happens when you include C8...?
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    Closed: Re: 230VAC PWM LED bulb dimmer

    might be a good idea to break one open and draw a schematic of the inside - could be quite helpful...
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    Closed: Re: 230VAC PWM LED bulb dimmer

    What electronics are inside the bulb? - just LED's in series or ...? ?
  8. Closed: Re: LLC converter vs Dual cascaded Buck….1000V to 48V at 500W output…no isolation ne

    So, you want to patent the improved buck converter ? I can't quite see the "inventive step" - legal term - that you have created here ...?

    24V to 12V buck converters ( dual fet ) with...
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    Closed: Re: push pull ac-dc auxiliary winding.

    also note if you are rectifying 230V mains the push pull fets will see > 650Volts - so 800V min required ...
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    Closed: Re: Wht is the purpose of this op amp

    PWM -> DC value converter ... with lower output impedance to drive the secret load ( lower than the 4k7 resistor used on the filter ...)
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    Closed: Re: push pull ac-dc auxiliary winding.

    Auxiliary power supply once the push pull starts - what powers the chip to provide the gate drive at cold start is not shown / not drawn / not provided in the schematic - likely an unfinished ...
  12. Closed: Re: LLC converter vs Dual cascaded Buck….1000V to 48V at 500W output…no isolation ne

    ... and ... does it work in sim ... ?
  13. Closed: Re: LLC converter vs Dual cascaded Buck….1000V to 48V at 500W output…no isolation ne

    2 x 600V diodes with small snubbers across each, 47pF & 470 ohm should make the sim go ...

    - - - Updated - - -

    for 1kV in you probably want to keep the sw freq to 50kHz, or even less, ...
  14. Closed: Re: LLC converter vs Dual cascaded Buck….1000V to 48V at 500W output…no isolation ne

    If you were going to do 2 x buck stages - you would have the same gate drive to each stage, this would give 1kV:220V:48V naturally

    Using SiC you could synch rect both stages ( only 48V ...
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    Closed: Re: AC-DC power supply design

    you run the risk of frying the igbt - try a relay ...

    - - - Updated - - -

    p.s. you only need one triac - the other is redundant - also the thermistor could be 2 x 10W 68E resistors in...
  16. Closed: Re: LLC converter vs Dual cascaded Buck….1000V to 48V at 500W output…no isolation ne

    1000V to 48V, I would do this with 2 x 800V H bridges in series ( we have done up to 4 in series for 3.8kV in, 350Vout 40A )

    I would use a series resonant converter ( not LLC per se ) ...
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    Closed: Re: BJT amplifier design

    are we doing home work for students now ... ?
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    Closed: Re: "Current adds up in phase"

    if you have 2 equal currents 180 deg out of phase in a wire - the net current is zero - if there are in phase then the current is 2x - this is why knowing the phase relationship is...
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    Closed: Re: SMPS for 5000W can be a Full Bridge

    There are a lot of hard switched H bridges up to 3.5kW ( and well above actually ) usually 20kHz for above 3.5kW and up to 50kHz below 3.5kW

    for a compact design - read less heatsink - ...
  20. Closed: Re: Testing Amps on rewound microwave transformer

    ... ... ... .
  21. Closed: Re: convert voltage control to current control

    There is - or should be - no contradiction - you can use a very small amount of current mode control in an half bridge ( but not too much ..! - the rest of the ramp comes from Vin - suitably...
  22. Closed: Re: Testing Amps on rewound microwave transformer

    The current needs to be limited by a suitable load on the output of the Tx - if you apply a too low ohm load you will overload the Tx, this is what fuses and polyfuses & circuit breakers are for ...
  23. Closed: Re: Testing Amps on rewound microwave transformer

    also the pri of a uWave Tx has fewer turns than a conventional Tx - it runs very high peak flux and high peak magnetising current - as a result they hum loudly

    you cannot connect an ammeter...
  24. Closed: Re: Earth leakage Detection "positive" as well as "Negative" >30mA.

    here you go :-157368
  25. [SOLVED]Closed: Re: LoopGain analysis with multiple feedback loop

    @ The Electrician - they are resistors -
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