Guys,
Sorry that I have no much time for this forum. Here is my fullbridge. Capable to be supplied +/- 90Vdc. Plenty power output. Yes... you need to tweak by yourself such as dead time by adjust R gate mosfet. And maybe uH inductor to suit your speed. But this topology is working.
.asc file is attached to PDF.
Sorry that I have no much time for this forum. Here is my fullbridge. Capable to be supplied +/- 90Vdc. Plenty power output. Yes... you need to tweak by yourself such as dead time by adjust R gate mosfet. And maybe uH inductor to suit your speed. But this topology is working.
.asc file is attached to PDF.
No current limiting and no way to implement it without changing to a different driver IC scheme or a different supply/ground topology, or adding a few dozen parts either as rail sense or floating sense. Pre-filter feedback, so more useful for LF duty.
TL07x is not the best choice for this application because that kind of chips are OK for their pricing but have a funny -PSRR charactetistic: around crossover frequency (3Mhz) the output exhibits amplification for the voltage difference between the output and negative rail, so any fast spike either as input command or as output load causes HF output bounce. In practice TL07x is OK when the spikes and related inaccuracy do not matter (linear circuits with no spikes, or proper consideration with spikes at the input and/or (100r,1n) to GND at the output to avoid disturbance entering. LM83x and MC3307x is a different kind of audio op-amp in the same price range that does not have the vulnerabilities of TL07x but have other, high input noise current, dictating the use of low value resistors, but this is always less trouble than bounce at the output of an op-amp used as class D modulator.
TL07x is not the best choice for this application because that kind of chips are OK for their pricing but have a funny -PSRR charactetistic: around crossover frequency (3Mhz) the output exhibits amplification for the voltage difference between the output and negative rail, so any fast spike either as input command or as output load causes HF output bounce. In practice TL07x is OK when the spikes and related inaccuracy do not matter (linear circuits with no spikes, or proper consideration with spikes at the input and/or (100r,1n) to GND at the output to avoid disturbance entering. LM83x and MC3307x is a different kind of audio op-amp in the same price range that does not have the vulnerabilities of TL07x but have other, high input noise current, dictating the use of low value resistors, but this is always less trouble than bounce at the output of an op-amp used as class D modulator.
Last edited:
And? Even TPA chips have a basic short circuit detector. Otherwise in case of output short DC protection relay opens but it does not open until output stage is toasted enough to produce DC.
I'm ubiquitous, I'm never leaving or coming back.
Yes, seen the decoupling, some superstition taking place hehe
I'm ubiquitous, I'm never leaving or coming back.
Yes, seen the decoupling, some superstition taking place hehe
Last edited:
Eva,
Thanks for your comments
I fully agree.
For current limiting, as this is just started, not.yet impemented.
TL071 can be swapped with better op amp.
It is still on test. Still problem with mosfet shoot thru on heavy loading. It needs carefuly layout and to stabilize switching behaviour. Your suggestion is welcome
- Calculation I already presented in the other topic.
- Seen too big sparks on your testing videos.
- Shunt is shunted by 2 electrolytic capacitor. This gives unpredictable result for spikes, since sensed voltage depends on ESR and parasitic inductances that depends on layout that is not defined yet.
+ the well known fact that bridge cancels a very high part of rail current at low modulation index.
Again, you are talking about OVER LOAD. Short circuit characteristic is very different. It is momentary and can have very huge energy, instantly. The OCP speed is not fixed but higher current the faster OCP to initiate.
Sparks or not doesn't matter. It is only YOUR personal preference. From my test, it is very simple judgement: no burning mosfet on repeat event event continue shorted. No temperature rise as well to the heatsink which may continue to thermal runaway.
Third is MY SECRET. There are always 4 diodes arround the inductor in my design. Whatever energy generated in the coil, it cannot be more than voltage supply as the diodes act like pipe. Any generated voltage more than voltage supply will be drained by that diodes to supply cap. This is wy my design is very stable. Even you can play connect or disconnect, short, whatever, on and off power without smoke.
I dont know what you mean from last statement.
Last edited:
D
Deleted member 148505
Current sense resistors should be of lower value, it will become hot on full power sinewave tests (and 1/4 of power dissipation of resistors on highly compressed music)
OCP on lowside can be replaced with IR25750L + comparator so that OCP will have no dissipation, can be adjusted without compromise, also cheaper than milliohm current sense resistors.
For highside, a digital isolator can be used, though complexity and cost will increase.
http://www.infineon.com/dgdl/ir25750lpbf.pdf?fileId=5546d462533600a4015355ca1d0e16f7
OCP on lowside can be replaced with IR25750L + comparator so that OCP will have no dissipation, can be adjusted without compromise, also cheaper than milliohm current sense resistors.
For highside, a digital isolator can be used, though complexity and cost will increase.
http://www.infineon.com/dgdl/ir25750lpbf.pdf?fileId=5546d462533600a4015355ca1d0e16f7
Last edited by a moderator: