Abstract: An electric power system for transportation comprises an electric generator started up by an ignition signal, an electricity storage element and a power supply connected to the electric generator, the electricity storage element and the load. The power supply comprises a standby power supply unit, an operating power supply unit and a control unit connected to the electric generator. The control unit is provided with a first state allowing the standby power supply unit and the operating power supply unit to stop operation when the ignition signal is not detected, and a second state starting up the standby power supply unit so as to allow the standby power supply unit to supply electric power to the load and induce the load to emit an on-off signal to the operating power supply unit when the ignition signal is detected.

Abstract: A power architecture for providing voltage modulation power is applied to a power supply including a PFC (Power Factor Correction) unit and a transformer, and the power supply further includes a power level correction unit, wherein the PFC unit decides a voltage modulation power level and converts the input power into a voltage modulation power, and the voltage modulation power is transformed into an output power through the transformer. A power level correction unit acquires a load utilization power signal from the output power and produces a power level correction signal to adjust the voltage modulation power level, which is decided by the PFC unit. Through adjusting the voltage modulation power level of the PFC unit, the PFC unit can produce voltage modulation power with different voltages according to the load variation, so as to reduce the internal loss of the power supply.