H-bridge/buck converter with negative and positive voltage range
I think you missed the point of the diode in Olin's original schematic. It was there to protect the bare MOSFET from the flyback effects of the inductor, and provide a path for the current to flow when the inductor is discharging its stored energy. To do that with an H bridge, you would connect diodes to the supply rails, but that is sometimes handled inside the bridge chip itself. Connecting a diode directly between the H bridge outputs is pointless &mdash; and potentially dangerous, as Andy pointed out.







simulate this circuit &ndash; Schematic created using CircuitLab

If you want to use large polarized capacitors in your filter, you just need to connect their negative terminals to ground. Each one will see only the correct polarity.







simulate this circuit