Patent ID: 7432609

Claim:
A method of controlling an electrical system that performs power supply to an electrical load and a battery from a plurality of power energy supply sources including an exhaust gas-driven generator that performs power generation by utilizing exhaust energy of an engine and a generator that performs power generation by utilizing drive forces of the engine, the method comprising the steps of: obtaining information for calculating power costs; calculating, from the obtained information, power costs coinciding with a cost per unit amount of electric power of respective ones of the power energy supply sources and suppliable amounts of power of the respective power energy supply sources; adjusting power flow characteristics of the electrical system by adjusting power supply allocation ratios of the power energy supply sources and a received power allocation ratio of the electrical load or a battery in accordance with the calculated power costs in a direction along which power energy is reduced, wherein for the exhaust gas-driven generator, a generatable amount of power indicating an amount of power generatable by the exhaust gas-driven generator, the amount of power being determined corresponding to an operating point of the engine, is used as the suppliable amount of power; determining an increment amount of fuel for the engine which increment amount is necessary for generation of the suppliable amount of power to be used as the power cost; supplying the increment amount of fuel to the engine additionally when operating the exhaust gas-driven generator; and modifying the operating point of the engine as a result of additionally supplying the increment amount of fuel to the engine.