currently, i have 4x470uf capacitors on the +60v rail, and 4x470uf on the negative rail. as you say, perhaps this is too much?
seeing as it is important that i finally add these inductors on the rectifier stage, i have lots of 22uh 25a toroid inductors, maybe these could be effective?
if so, i will try again with feedback, but with an inductor between the capacitors and diode on each rail side
when i had that feedback issue, i did notice really loud buzzing from the transformer when the current would peak an waveform was messy.
seeing as it is important that i finally add these inductors on the rectifier stage, i have lots of 22uh 25a toroid inductors, maybe these could be effective?
if so, i will try again with feedback, but with an inductor between the capacitors and diode on each rail side
when i had that feedback issue, i did notice really loud buzzing from the transformer when the current would peak an waveform was messy.
No ,i think such capacity should be ok for such load as yours ,especially if there's no feedback .Had problem with feedback with adjustable flyback converter ,for 11Ampere max output ,to reduce ripple ,used 2x3300 uf .That made feedback to oscillate a bit ,had to do more tricks to stabilise ,but problem with constant current mode remains . Current limiting is working ,but transformer gives additional 1khz sound ,This psu i have at work ,so don't care much about that .But if i need to charge Li-on cell with bms integrated ,i have current and voltage kick ,when connecting battery , and that turns on battery protection. Then i have to increase voltage slowly with load connected ,to prevent battery not charging .
If you really would like to implement output voltage regulation ,i will try to explain how that works and whats needs to be changed .
The big inductor at output is not for ripple reduction ,but for voltage reduction ,energy absorbtion and returning it to load . Try to google " forward converter current doubler" . To have +-60V output after inductor , you need to have more than twice voltage from transformer secondary , lets say 2x150V . As example ,atx psu have such inductor ,and transformer outputs are 2x29V for +12v rail . Part of energy is absorbed by inductor, and returned to output when there's a deadtime period ,when no primary mosfets conducting .Output current doubles .This is the same stepdown buck dc/dc converter ,just without mosfet switch, pulses already coming from transformer .Inductance is critical ,and load current dependent .Have recently modded one psu , original toroid inductor heated at half load current ,a few watts of loss ,ant that was not wire hot ,the core itself . Good result were reached only when tested EI core from old flyback psu , massive , and with 1mm air gap (a few layers of insulation tape helped ), and with 2,5mm2 wire wounded .Tried also small good toroid ,with high current rating ,similar inductance ,no go .Also one benefit ,what current doubler does - reduce diode loss . When you have let's say 10 Ampere output as you have now ,no inductor, all 10ampere goes through diodes ,one by one .With transformer voltage higher twice and inductor present after diodes ,current is 5A , because inductor current rises slow .Lower power loss on diodes .
Output capacitors and inductor will cause additional delay in output response ,and then feedback oscillates . For 494 ic there's resistor in series with capacitor ,between pins 3 and 2 as i remember ,to slow down feedback , but depending on load , inductance ,output capacitors , needs testing of values . Also , if additional filter is added ,feedback must be connected before that filter . Or feedback resistor split into two resistors in series , and midpoint connected through 1-10uf to first output capacitor , end resistor to output after all filters . That trick allows feedback to sense voltage after all filters ,compensate voltage drop on inductors DC resistance ,but slowly .Better slowly ,than oscillate .Some of these things can be seen in simulation ,but harder to notice . Feedback oscillation shows as not constant pulse length , and that variation is slower than pulse length itself ,this is what we hear as buzzing .
If you really would like to implement output voltage regulation ,i will try to explain how that works and whats needs to be changed .
The big inductor at output is not for ripple reduction ,but for voltage reduction ,energy absorbtion and returning it to load . Try to google " forward converter current doubler" . To have +-60V output after inductor , you need to have more than twice voltage from transformer secondary , lets say 2x150V . As example ,atx psu have such inductor ,and transformer outputs are 2x29V for +12v rail . Part of energy is absorbed by inductor, and returned to output when there's a deadtime period ,when no primary mosfets conducting .Output current doubles .This is the same stepdown buck dc/dc converter ,just without mosfet switch, pulses already coming from transformer .Inductance is critical ,and load current dependent .Have recently modded one psu , original toroid inductor heated at half load current ,a few watts of loss ,ant that was not wire hot ,the core itself . Good result were reached only when tested EI core from old flyback psu , massive , and with 1mm air gap (a few layers of insulation tape helped ), and with 2,5mm2 wire wounded .Tried also small good toroid ,with high current rating ,similar inductance ,no go .Also one benefit ,what current doubler does - reduce diode loss . When you have let's say 10 Ampere output as you have now ,no inductor, all 10ampere goes through diodes ,one by one .With transformer voltage higher twice and inductor present after diodes ,current is 5A , because inductor current rises slow .Lower power loss on diodes .
Output capacitors and inductor will cause additional delay in output response ,and then feedback oscillates . For 494 ic there's resistor in series with capacitor ,between pins 3 and 2 as i remember ,to slow down feedback , but depending on load , inductance ,output capacitors , needs testing of values . Also , if additional filter is added ,feedback must be connected before that filter . Or feedback resistor split into two resistors in series , and midpoint connected through 1-10uf to first output capacitor , end resistor to output after all filters . That trick allows feedback to sense voltage after all filters ,compensate voltage drop on inductors DC resistance ,but slowly .Better slowly ,than oscillate .Some of these things can be seen in simulation ,but harder to notice . Feedback oscillation shows as not constant pulse length , and that variation is slower than pulse length itself ,this is what we hear as buzzing .
