Electric vehicle and performance setting method

#The disclosure of Japanese Patent Applications Nos. 2003-041571 filed on Feb. 19, 2003 and 2003-113159 filed on Apr. 17, 2003 including the specification, drawings and abstract are incorporated herein by reference in their entirety.

#1. Field of the Invention

#The invention relates to an electric vehicle and a performance setting method. More particularly, the invention relates to an electric vehicle including a fuel cell and a capacitor which are connected in parallel to a drive circuit of an electric motor that outputs power to an axle shaft. The invention also relates to a method for setting performance of the fuel cell and performance of the capacitor which are to be mounted on the electric vehicle that runs by supplying electric power from the fuel cell and the capacitor to the drive circuit of the electric motor that can output power to the axle shaft without converting a voltage.

#FIG. 1 is a diagram schematically showing a configuration of an electric vehicle according to an embodiment; and

#FIG. 2 is a graph showing an example of a relationship among a maximum output of a fuel cell, a capacitance of a capacitor, dynamic characteristics of the vehicle and a cost in the electric vehicle whose gross weight is 2t.

#Hereafter, an embodiment according to the invention will be described with reference to accompanying drawings. FIG. 1 is a diagram schematically showing a configuration of an electric vehicle 10 according to an embodiment of the invention. As shown in FIG. 1, the electric vehicle 10 according to the embodiment includes a fuel cell 30 which generates electric power using hydrogen gas as fuel gas that is supplied from a hydrogen high-pressure tank 22 and is circulated by a circulating pump 26 and oxygen in the air that is supplied from an air compressor 28 and an accumulator 24 through a switching valve 50; a capacitor 32 which is connected in parallel to the fuel cell 30 through a breaker 56; an inverter 34 which serves as a drive circuit of a drive motor 36 and converts direct current power from the fuel cell 30 and the capacitor 32 to three phase alternating current power; a drive motor 36 which is driven by the three phase alternating current power that is obtained by the inverter 34 and which outputs power to drive wheels 12 through a differential gear 14; and an electronic control unit 70 which controls the entire vehicle. The electric vehicle 10 is configured such that the gross weight is approximately 2t.

#The fuel cell 30 is formed of a fuel cell stack (not shown). The fuel cell stack is formed by stacking unit cells with separators interposed between the unit cells. The unit cell is formed by providing an anode electrode and a cathode electrode so as to sandwich an electrolyte membrane. The separator serves as a partition between the adjacent unit cells. The fuel cell 30 generates electric power by electrochemical reaction of the hydrogen gas supplied to the anode electrode through a gas passage formed in the separator and the air supplied to the cathode electrode. In the fuel cell 30, there is provided a circulation passage (not shown) through which a coolant medium (for example, cooling water) can circulate. Due to circulation of the coolant medium through the circulation passage, the temperature in the fuel cell 30 is maintained at an appropriate temperature (for example, 65° C. to 85° C.). The fuel cell 30 whose maximum output (rated value) is 95 kW and operating voltage is 240 to 400V is mounted on the electric vehicle 10 according to the embodiment.

#The capacitor 32 is configured, for example, as an electric double layer capacitor (EDLC). The capacitor 32 whose working voltage is 240 to 500V and capacitance is 7F is mounted on the electric vehicle 10 according to the embodiment.