I have a problem with a self oscillating IRS20957 circuit.
It will not startup and I'm getting an use DC voltage at the output.
The DC voltage is coming from the high-side OCP (from the VDR/VCC voltage) so is seems like that the IRS20957 is not starting up properly.
Unfortunately I'm not allowed to post the schematic here, but I is partly similar to IRS2092 2kW dev board.
(or at least the OCP etc)
At first I tried the values that I calculated for the protection circuits, after that I switched to the 1-2kW IRS2092 version (which is very similar)
The strange thing is that the amplifier was working, but was constantly switching on and off (oscillating frequency was working)
After removing the self reset capacitor the amplifier was staying on, but I got a very strange PWM signal.
When I applied a sine wave the circuit was switching off suddenly.
I already set the dead-time to highest time value (otherwise my amplifier is getting really hot).
The voltage supply is around ±70Vdc (at the moment for testing, will be ±85Vdc), I use four IRFP4227 MOSFETs and FMMT718/716 as a buffer
It will not startup and I'm getting an use DC voltage at the output.
The DC voltage is coming from the high-side OCP (from the VDR/VCC voltage) so is seems like that the IRS20957 is not starting up properly.
Unfortunately I'm not allowed to post the schematic here, but I is partly similar to IRS2092 2kW dev board.
(or at least the OCP etc)
At first I tried the values that I calculated for the protection circuits, after that I switched to the 1-2kW IRS2092 version (which is very similar)
The strange thing is that the amplifier was working, but was constantly switching on and off (oscillating frequency was working)
After removing the self reset capacitor the amplifier was staying on, but I got a very strange PWM signal.
When I applied a sine wave the circuit was switching off suddenly.
I already set the dead-time to highest time value (otherwise my amplifier is getting really hot).
The voltage supply is around ±70Vdc (at the moment for testing, will be ±85Vdc), I use four IRFP4227 MOSFETs and FMMT718/716 as a buffer
