I have a 230VAC inverter that runs off 12V (battery). But it seems to cause a lot of noise.
The noise is causing problems with my MCU and other circuits. It seems the problem is measurable in the +12V supply.
I'm measuring the +12V bus, which is connected to battery positive, and with the probe ground connected to the negative bus, which is connected to battery negative terminal, via 30mm2 cables of ~1m length.
Measuring directly at the positive terminal gives the same result. Except when the probe ground is connected to battery negative. (This leads me to suspect the problem might be with the inverter input)
However, when probe ground is connected to battery negative terminal, the noise disappears. The scope looks the same when the inverter is turned off.
Attempts to reduce noise
I've tried to use an extension cord to move it ~4 meters away: no effect
Turning off lights: no effect
Holding the inverter in my hand: no effect
Connecting oscilloscope probe to battery negative terminal: causes noise to disappear
Connecting a wire from negative battery terminal to oscilloscope ground: no effect
- Inverter pulls 0.6A
- Scope ground is connected to negative bus, which is connected to battery negative terminal
- No natural earth is connected. "Earth" is connected to negative bus, which is connected to vehicle chassis (motorhome installation with external mains cable intake, mains cable lacks earth wire).
- Battery bank is LiFePO4
- No VAC output is connected
- Oscilloscope and computer is powered from mains cable during testing
- No other appliances are connected except for a 12V LED strip (no driver).
What is the cause of this noise?
Do I need a beefy input capacitor? The inverter already has some beefy input capacitors, but maybe they're not enough?
What else might resolve the problem?