An electrical system architecture for a mobile, electric hybrid machine includes a first bus configured to receive electric power at a first, selectively adjustable voltage from an electrical power source. A second bus is configured to receive electric power at a second voltage that is lower than the first voltage. A controller is configured to determine a desired magnitude of the second voltage for the second bus, produce a signal indicative of a magnitude of the first, selectively adjustable voltage that is a multiple of the desired magnitude of the second voltage, and adjust the magnitude of the first voltage in the first bus to the multiple of the desired magnitude of the second voltage. A fixed-ratio power converter is configured to convert the power at the first voltage in the first bus to the power at the second voltage in the second bus.