I am using an H-bridge for output to a UV lamp. Attached is the circuit for the H-bridge, 555 timer to produce signal for switching, optocouplers to isolate the gate drivers and keep all four MOSFETs turning on and off at the same time, and the low side gate drivers with their relative ground tied to the respective MOSFET's source.
I am using two power supplies, one for the timer and drivers at +15V and the other is at the terminal BUCK-OUT. To ensure I had the timer and other chips working I set the BUCK-OUT terminal to 0V, the gates of each MOSFET were turning on and off at the right times and quickly. I first started applying about +30V to BUCK-OUT, this made the signal to the gate worse, not as clean, and brought the duty cycle further away from 50%, but by adjusting the potentiometers I was able to get the signals back to a near 50% duty.
The problem is that this is going to be a constant current output, the voltage will be changing constantly. Open circuit voltage will be a max of around 600V-800V and the on state will be 80V-140V. I have tested the circuit with and without a load, both show the same outcome, so the thing messing up the signal is the voltage across GND and BUCK-OUT.
Please let me know what you think could be the problem, or if you need any other information about this circuit.
I am using two power supplies, one for the timer and drivers at +15V and the other is at the terminal BUCK-OUT. To ensure I had the timer and other chips working I set the BUCK-OUT terminal to 0V, the gates of each MOSFET were turning on and off at the right times and quickly. I first started applying about +30V to BUCK-OUT, this made the signal to the gate worse, not as clean, and brought the duty cycle further away from 50%, but by adjusting the potentiometers I was able to get the signals back to a near 50% duty.
The problem is that this is going to be a constant current output, the voltage will be changing constantly. Open circuit voltage will be a max of around 600V-800V and the on state will be 80V-140V. I have tested the circuit with and without a load, both show the same outcome, so the thing messing up the signal is the voltage across GND and BUCK-OUT.
Please let me know what you think could be the problem, or if you need any other information about this circuit.
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