Patent ID: 8855953

Claim:
An electrical power control device comprising: a direct-current power source; a chopper circuit including a first switching element whose one end is connected with a positive-pole terminal side of the direct-current power source, a second switching element whose one end is connected with a negative-pole terminal side of the direct-current power source, wherein the first switching element and the second switching element are provided between a positive-pole terminal and a negative-pole terminal of the direct-current power source in series with the direct-current power source, and a reactor whose one end is connected with a common connection point located between another end of the first switching element and another end of the second switching element; a load connected between another end of the reactor and the negative-pole terminal of the direct-current power source, wherein the electrical power control device is configured to supply direct-current power of the direct-current power source to the load by controlling the chopper circuit; a detecting section configured to detect an output voltage Vdc of the direct-current power source, a current Idc flowing in the reactor and a switching duty d 1 of the first switching element of the chopper circuit, wherein the switching duty d 1 satisfies a condition of 0≦d 1 ≦1; and a control section configured to calculate a current value d 1 ·Idc flowing in a region producing the output voltage Vdc of the direct-current power source, from the detected output voltage Vdc of the direct-current power source, the switching duty d 1 of the first switching element and the current Idc flowing in the reactor, and to determine an electrical power W by calculating Vdc·d 1 ·Idc from the output voltage Vdc of the direct-current power source and the current value d 1 ·Idc.