Patent attributes
The invention makes it possible to secure a maximum output within the capacity range of an electrical power source by preventing an output from being cut by a protective function of a converter at the time of a temporary overload. A bidirectional DC-DC converter 4 for stepping up a voltage of DC power supplied from a battery 5 is provided. A stepped-up DC power is converted to an AC power by an inverter 3-2 via a regulator 3-1 and is outputted to the load side. An input voltage V1 of the regulator 3-1 is detected by a voltage detecting portion 15 and is inputted into an output limit determining portion 16. The output limit determining portion 16 determines an output voltage value for starting to limit an inverter output according to a distance from when the input voltage V1 fell below a limit starting voltage value Vlim to a limit voltage value Va. An inverter driving portion 17 limits an output by switching FETs in the inverter 3 in accordance with this output voltage value. When a temporary overload is eliminated, then the output recovers to a maximum value.
