US Patent 10407050 Auxiliary power supply for hybrid electric vehicle

A vehicle includes a first electric machine configured to generate low-voltage power. The vehicle includes a second electric machine configured to generate high-voltage power. The vehicle includes a power converter configured to convert high-voltage power generated by a second electric machine to low-voltage power. The vehicle includes a controller programmed to, responsive to a low-voltage power demand exceeding a limit of the power converter, operate the first electric machine and the power converter to satisfy the demand, and otherwise, responsive to the power converter being operational, operate only the power converter to satisfy the demand.