I am designing a 1kHz inverter in a push-pull configuration with KA3525 and IRF540N MOSFETs.
- Input - 12V
- Output - 110Vac - square wave filtered to sine wave
- Power - 15W at 1000Hz
When I fire it up on load I get some noise on the gate pulses.
Also note that the gate pulse is only about 8V peak instead of 12V.
I have a feeling that the gate noise is causing the MOSFET to switch on and off very fast and cause circulating currents and heat up the MOSFETs.
I built this on a perf board to test before going for a proper PCB, but I don't think that should cause any problems at such a low frequency.
I have tried changing the IC but that did not change anything.
Gate resistance is 100 Ohm and gate to source pulldown resistance is 1k.
Any advice is appreciated.
I have tried to keep the layout as clean as possible.
- Ipeak = 1.25A
- Duty = 50%
- I_rms = 1.25/sqrt(2) = 0.88
- R_ds = 52mOhm
- P_loss = 0.04W
- Rthj_A = 62 Deg/W
- T_rise = 2.5 Deg C (The MOSFET is overkill for this application)
- Deadtime is about 40us. These waveforms are at max dutycycle.
I tried using shorter ground paths to eliminate external noise - no change.
No change - (blue is the new setting and yellow is the older setup.)
The negative pulse before was most likely due to improper setting of the base line.
The gate signal starts off clean but soon gets noisy. Check time stamps on the video.