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A portable power supply includes an engine-driven generator that generates a first AC power. A rectifier rectifies the first AC power to a first DC power. A DC/DC converter converts a second DC power from a storage unit to a third DC power. A controller selectively enables one or both of the rectifi

A portable power supply includes an engine-driven generator that generates a first AC power. A rectifier rectifies the first AC power to a first DC power. A DC/DC converter converts a second DC power from a storage unit to a third DC power. A controller selectively enables one or both of the rectifier and the DC/DC converter to provide one or both of the first DC power and the third DC power to the input of an inverter. The inverter converts the DC power at its input to a second AC power. Alternatively, the power supply advantageously includes a second generator and a second rectifier. The outputs of the two rectifiers are summed and the sum of the two outputs is provided as an input the inverter to extend the range over which a constant second AC power can be provided.

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1. A power supply comprising an internal combustion engine, a generator driven by the engine to generate a first AC power, a rectifier that rectifies the first AC power to a first DC power, an inverter that receives the first DC power as a first input and that generates a second AC power, an electri

1. A power supply comprising an internal combustion engine, a generator driven by the engine to generate a first AC power, a rectifier that rectifies the first AC power to a first DC power, an inverter that receives the first DC power as a first input and that generates a second AC power, an electrical storage device that stores electrical energy to supply a second DC power, a DC/DC converter that converts the second DC power to a third DC power, the third DC power provided as a second input to the inverter, the inverter also converting the third DC power to the second AC power, and a controller that controls at least the rectifier and the DC/DC converter, the controller selectively enabling one of the rectifier and the DC/DC converter to provide one of the first DC power and the third DC power, respectively, to the inverter, or selectively enabling the rectifier and the DC/DC converter to provide the first and third DC powers to the inverter at the same time, wherein the controller monitors the second AC power, the controller enabling the rectifier and the DC/DC converter to provide the first and third DC powers to the inverter when the second AC power is greater than a preset magnitude.2. The power supply as set forth in claim 1, wherein the controller monitors a current of the second AC power.3. The power supply as set forth in claim 2, wherein the controller additionally monitors an increase rate of the current, the controller enabling the rectifier and the DC/DC converter to provide the first and third DC powers to the inverter when the increase rate of the current is greater than a preset increase rate.4. The power supply as set forth in claim 2, wherein the controller additionally monitors a voltage of the first DC power, the controller enabling the rectifier and the DC/DC converter to provide the first and third DC powers when the current is greater than a preset magnitude and the voltage is less than a preset voltage.5. The power supply as set forth in claim 1, additionally comprising a switch to select either a first control mode or a second control mode, one of the rectifier and the DC/DC converter providing one of the first and third DC powers, respectively, to the inverter when the switch is positioned in the first control mode, and both of the rectifier and the DC/DC converter providing respective DC powers when the switch is positioned in the second control mode.6. The power supply as set forth in claim 5, further comprising a second switch to select either the rectifier or the DC/DC converter under the first control mode.7. The power supply as set forth in claim 6, further comprising a third switch to select either a first engine operating mode or a second engine operating mode, the controller monitoring the second AC power, the controller controlling the engine such that an engine speed changes along with a change of the second AC power when the third switch is positioned in the first engine operating mode, the controller controlling the engine such that the engine speed is generally constant when the third switch is positioned in the second engine operating mode.8. The power supply as set forth in claim 1, additionally comprising a switch to select either a first engine operating mode or second engine operating mode, the controller monitoring the second AC power, the controller controlling the engine such that an engine speed changes along with a change of the second AC power when the switch is positioned in the first engine operating mode, the controller controlling the engine such that the engine speed is generally constant when the switch is positioned in the second engine operating mode.9. The power supply as set forth in claim 8, wherein the controller incorporates at least one control map of engine speed versus current of the second AC power, the controller monitors the current of the second AC power, and the controller controls the engine speed in accordance with a change of the current using said control map.10. The power supply as set forth in claim 1, wherein the generator or the engine incorporates a charge coil that charges the electrical storage device.11. The power supply as set forth in claim 1, wherein the electrical storage device includes a battery.12. The power supply as set forth in claim 1, wherein the electrical storage device includes a double-layered capacitor.13. The power supply as set forth in claim 1, additionally comprising at least a second generator, the generators generating respective first AC powers that are different in magnitude with respect to each other, and additionally comprising at least a second rectifier, each rectifier receiving a respective one of the first AC power and producing a respective rectified DC power at a respective rectifier output, the rectifier outputs being connected in series to provide the first DC power as a sum of the respective rectified DC powers.14. The power supply as set forth in claim 1, additionally comprising a housing at least enclosing the engine and the generator, a temperature sensor detecting a temperature inside of the housing, the controller controlling a speed of the engine based upon an output signal of the temperature sensor, the controller increasing engine speed when the temperature increases.15. A control method for a power supply, comprising monitoring an AC power from an inverter, determining whether the AC power is greater than a preset magnitude, and selectively enabling a rectifier and a DC/DC converter to provide respective DC powers to the inverter when the AC power is greater than the preset magnitude.16. The control method as set forth in claim 15, additionally comprising determining whether a switch is placed in a first position corresponding to a first control mode or in a second position corresponding to a second control mode, enabling one of the rectifier and the DC/DC converter to provide respective DC power to the inverter if the switch is placed in the first position, and enabling the rectifier and the DC/DC converter to provide respective DC powers to the inverter if the switch is placed in the second position.17. The control method as set forth in claim 16, wherein the rectifier rectifies a second AC power generated by a generator driven by an engine, the method further comprising determining whether a second switch is placed in a first position corresponding to a first engine operating mode or the second switch is placed in a second position corresponding to a second engine operating mode, controlling the engine such that an engine speed changes along with a change of the first AC power if the second switch is placed in the first position, and controlling the engine such that the engine speed is generally constant if the second switch is placed in the second position.18. The control method as set forth in claim 15, wherein the rectifier rectifies a second AC power generated by a generator driven by an engine, the method further comprising determining whether a switch is placed in a first position corresponding to a first engine operating mode or the switch is placed in a second position corresponding to a second engine operating mode, controlling the engine such that an engine speed changes along with a change of the first AC power if the switch is placed in the first position, and controlling the engine such that the engine speed is generally fixed if the switch is placed in the second position.19. An engine-driven power supply, the power supply comprising:an engine that operates at a variable engine speed, the engine having a power output; a first generator coupled to the power output of the engine, the first generator generating a first AC voltage having a first magnitude characteristic in response to variations in the engine speed; a second generator coupled to the power output of the engine, the second generator generating a second AC voltage having a second magnitude characteristic in response to variations in the engine speed; a first rectifier having an input that receives the first AC voltage and having an output that provides a first DC voltage; a second rectifier having an input that receives the second AC voltage and having an output that provides a second DC voltage, the output of the second rectifier connected in series with the output of the first rectifier to superimpose the first DC voltage and the second DC voltage to provide a composite DC voltage having a composite magnitude characteristic in response to engine speed; and a DC-to-AC conversion unit having an input that receives the composite DC voltage and having an output that generates an AC output voltage responsive to the magnitude of the composite DC voltage. 20. The power supply as defined in claim 19, further comprising a voltage stabilization circuit that stabilizes at least the first DC voltage such that the composite DC voltage increases only to a selected magnitude as the engine speed increases to a selected engine speed, and such that the composite DC voltage does not increase as the engine speed increases above the selected engine speed.21. The power supply as defined in claim 20, further comprising:a filter circuit coupled to the output of the DC-to-AC conversion unit, the filter circuit reducing harmonic components from the third AC voltage, the filter circuit generating a control voltage responsive to the third AC voltage; and a control circuit coupled to receive the control voltage from the filter circuit, the control circuit controlling the voltage stabilization circuit in response to the control voltage. 22. The power supply as defined in claim 20, wherein:the first AC voltage generated by the first generator is greater than the AC voltage generated by the second generator; and the voltage stabilization circuit stabilizes the first DC voltage provided by the first rectifier. 23. The power supply as defined in claim 19, further comprising a filter circuit coupled to the output of the DC-to-AC conversion unit, the filter circuit reducing harmonic components from the third AC voltage.24. The power supply as set forth in claim 1, additionally comprising a switch operated by an operator to select either a first control mode or a second control mode, one of the rectifier and the DC/DC converter providing one of the first and third DC powers, respectively, to the inverter when the switch is positioned in the first control mode, and both of the rectifier and the DC/DC converter providing respective DC powers when the switch is positioned in the second control mode.25. The power supply as set forth in claim 24, further comprising a second switch operated by an operator to select either the rectifier or the DC/DC converter under the first control mode.26. The power supply as set forth in claim 25, further comprising a third switch operated by an operator to select either a first engine operating mode or a second engine operating mode, the controller monitoring the second AC power, the controller controlling the engine such that an engine speed changes along with a change of the second AC power when the third switch is positioned in the first engine operating mode, the controller controlling the engine such that the engine speed is generally constant when the third switch is positioned in the second engine operating mode.27. The power supply as set forth in claim 1, additionally comprising a switch operated by an operator to select either a first engine operating mode or second engine operating mode, the controller monitoring the second AC power, the controller controlling the engine such that an engine speed changes along with a change of the second AC power when the switch is positioned in the first engine operating mode, the controller controlling the engine such that the engine speed is generally constant when the switch is positioned in the second engine operating mode.