In recent years, electric vehicles using an electric motor as a drive source as well as so-called hybrid electric vehicles using a combination of an electric motor and another type of drive source such as an internal combustion engine or a fuel cell have been practically available. This kind of vehicle is provided with a power storage unit for supplying electricity, i.e., energy to the electric motor. A repetitively chargeable secondary battery, a capacitor or the like is arranged as the power storage unit.
A nickel cadmium battery, a nickel hydrogen battery or a lithium ion battery is used as the secondary battery. The secondary battery includes, e.g., a battery module having layered battery cells. The battery module is mounted on the vehicle together with a power storage casing accommodating it. The battery module supplies a DC power. Since the secondary battery mounted on the vehicle is required to provide a high voltage and a high output, it is formed of about thirty battery modules connected in series. Each battery cell is formed of about six cells connected in series and each having an output of about 1.2 V. This battery module achieves a high input/output voltage.
The motor providing a drive power of the vehicle is driven by an AC power. DC electricity provided from the power storage unit is converted into AC electricity, which is fed to the motor. The power supply device may be connected to control units and/or auxiliary devices such as an audio unit in addition to the inverter for driving the motor. These units and devices are driven with a low voltage. Therefore, the power supply device may be provided with a converter for stepping down the voltage of the power storage unit.
Japanese Patent Laying-Open No. 2004-114821 has disclosed a power supply package having power supply parts of a 42-V system and power supply parts of a 14-V system that are arranged and integrated in a package casing to be arranged in an engine room of a vehicle. In this power supply package, all power supply interconnections for mutual connection between power supply parts or for external connection thereof are formed of bus bars, and the bus bars of the power supply parts can be connected together only by sliding these parts in the attaching direction. According to the disclosure, this power supply package can provide a wiring-less structure, and can facilitate mounting and wiring operations. Also, according to the disclosure, the power supply package includes an inverter, a DC/DC converter, a 36-V battery, a 12-V battery and others that are arranged in the package casing, and are accommodated in the engine room of the vehicle together with the package casing.
Japanese Patent Laying-Open No. 2004-106807 has disclosed a hybrid vehicle having a high-potential battery supplying an electric power to a drive motor driving a vehicle as well as a low-potential battery supplying an electric power to auxiliary devices of the vehicle. The high-potential battery is formed of a plurality of divided battery units, and the divided battery units of the high-potential battery as well as the low-potential battery are arranged behind a rearmost seat of the vehicle, and are located in spaced two positions that neighbor to sidewalls of a vehicle body, respectively. According to the disclosure, this hybrid vehicle can achieve a good balance in vehicle weight, a flat baggage compartment and a trunk-through structure.
Japanese Patent Laying-Open No. 2005-297860 has disclosed a power supply device for a vehicle and particularly for a hybrid vehicle that uses in combination a high-voltage battery and an auxiliary battery (i.e., battery for auxiliary devices) arranged in the rear of the vehicle. In this power supply device, a fusible link box is arranged near the auxiliary battery of 12 V, and a power line that is an output line of a DC/DC converter performing voltage conversion between the high-voltage battery and the auxiliary battery is not returned to an engine room but is connected to the fusible link box. According to the disclosure, wiring paths of electric power lines can be easily ensured in this power supply device for the vehicle.
Japanese Patent Laying-Open No, 2005-178732 has disclosed a cooling device of a high-voltage electric device for a vehicle motor. In this device, a battery, an inverter, a DC-DC converter and a fan are arranged concentratedly under a rear seat, a cooling air inlet is arranged under one side, in a vehicle width direction, of the rear seat and a cooling air outlet is arranged under the other side. According to the disclosure, this device can efficiently cool high-voltage electric units without causing lowering of utility and the like.
Japanese Patent Laying-Open No. 9-149552 has disclosed a power supply device that includes a main battery having a voltage of 300 V, a voltage converter converting the voltage of the main battery into 12 V and a voltage converter converting the voltage of the main battery into 24 V.
Japanese Patent Laying-Open No. 9-200902 has disclosed a power supply device for an electric vehicle that includes a main power supply feeding a electric power to a drive motor controlled by a drive motor control device, and a plurality of sub-power supplies that are employed for supplying powers to electric loads of various rated voltages different from that of the drive motor, and are formed of voltage converters for converting the voltage of the main power supply into voltages corresponding to the various rated voltages of the plurality of sub-power supplies, respectively.
The voltages taken out from the power supply device are, e.g., about 12 V and 30 V, respectively. In recent years, a power supply for a voltage(s) different from these voltages has been required in some cases. In some cases, the voltage of about 12 V cannot provide a sufficient drive power, e.g., to an electric power steering device that is driven by an electric motor, and the voltage of about 300 V is excessively high for it. Accordingly, it has been studied to use electricity, e.g., of about 40 V as the power supply for driving the electric power steering. As described above, another kind of voltage is required in addition to the voltages supplied from the conventional power supply in some cases.
The power supply package disclosed in the above Japanese Patent Laying-Open No. 2004-114821 includes the 36-V battery and 12-V battery. These batteries arranged for the high and low voltage systems, respectively, increase the sizes of the power supply device. In the Japanese Patent Laying-Open No. 9-149552 or 9-200902, the main battery is connected to a plurality of voltage converters for supplying the electricity of a plurality of voltages, but the structures and arrangement of the various devices or units are not disclosed.