Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Electric vehicle
Reexamination Certificate
2001-04-13
2003-02-18
Zanelli, Michael J. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Electric vehicle
C180S065100, C180S065800, C307S010600, C320S104000
Reexamination Certificate
active
06522960
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vehicle that utilizes electrical energy of a high voltage power source system, a power source system controller mounted on an apparatus that utilizes the electrical energy of the high voltage power source system, and a method of controlling a power source system. More specifically the invention pertains to a technique that utilizes a converter to convert the electrical energy of a high voltage battery into a low voltage and supply the converted low voltage and accordingly enables application of the electrical energy of a high voltage power source system including the high voltage battery.
2. Description of the Related Art
There are a diversity of recently proposed vehicles that utilize high voltage electrical energy of, for example, high voltage batteries. Typical examples of such vehicles include special vehicles that have a high voltage battery mounted thereon and carry out various works with the electric power of the high voltage battery, electric vehicles that run with the energy of a battery, and hybrid vehicles that have an internal combustion engine and a battery mounted thereon and use the power of the internal combustion engine in combination with the power of the battery. These vehicles generally have two batteries, that is, a high voltage battery that stores high voltage electrical energy used for driving and a low voltage battery that stores low voltage electrical energy used for controlling drives of the vehicle and regulating auxiliary machinery mounted on the vehicle. While the low voltage battery is used only as the auxiliary machinery battery in conventional vehicles driven with only the power of the internal combustion engine, the low voltage battery functions as the power source for controlling a high voltage power source system including the high voltage battery in addition to the function as the auxiliary machinery battery in these recently proposed vehicles. Namely the low voltage battery is of the greater importance with an increase of its loading. In order to ensure supply of electrical energy to the low voltage battery, the prior art electric vehicle has a converter circuit that converts the electrical energy of the high voltage power source system into a low voltage and charges the low voltage battery with the converted low voltage electrical energy.
In spite of such consideration, the voltage drop of the low voltage battery is inevitable, due to the continuously driven, large electric loading like headlights and the natural discharge from the battery in the inactive state over a long term. The proposed safety measures by taking into account the importance of the low voltage battery inhibit the system of the electric vehicle from being activated when the voltage of the low voltage battery is lower than a minimum reference voltage. While the voltage of the low voltage battery is lower than a predetermined level, the voltage of the power line for a controller that takes charge of control operations may fluctuated even with the use of a stabilizing power source unit. The prior art vehicle and the prior art power source controller mounted on an apparatus thus uniformly inhibit its activation when the voltage of the lower voltage battery is lower than the predetermined level.
The method of uniformly inhibiting the activation, however, undesirably lowers the convenience in use of the prior art vehicle and the prior art power source controller mounted on the apparatus. As mentioned above, the loading applied to the low voltage battery has been increasing significantly. A simple increase in storage capacity with the increasing load, however, has limitations, since it undesirably makes the low voltage battery bulky and heavy. The voltage of the low voltage battery that is subject to heavy loading may thus be deviated from a normal range and lowered to or below the minimum reference voltage. The prior art technique inhibits the power supply to the controller that takes charge of control operations relating to drives of the vehicle, thus prohibiting the vehicle from being activated. A simple decrease in minimum reference voltage undesirably lowers the safety factor of the whole system and is thus not adoptable.
The low voltage battery is also generally used as the power source for driving an apparatus that establishes the high voltage power source line, for example, a relay that connects the output of the high voltage battery with the power line of the high voltage power source system. The extreme drop in voltage of the low voltage battery makes the operations of such an apparatus unstable. Under the condition of the lowered voltage of the low voltage power source system, the contact of the relay that switches on and off the high voltage has weak working force. This may result in welding the contact. It is thus impractical to simply decrease the lower limit voltage of the low voltage battery that allows a start of the vehicle or the apparatus.
SUMMARY OF THE INVENTION
The object of the present invention is thus to provide a technique that brings out the best performance of a low voltage battery, while ensuring safety of a whole system. In the case of application to a vehicle, the technique allows a start of the vehicle while guaranteeing the normal operation of the whole system of the vehicle.
At least part of the above and the other related objects is attained by a vehicle that utilizes electrical energy of a high voltage power source system including a high voltage battery. The vehicle includes: a control unit that carries out controls related to driving of the vehicle; a low voltage power source circuit that supplies electrical energy of a low voltage power source system including a low voltage battery to the control unit; a battery voltage measurement unit that measures a voltage level of the low voltage battery; a converter unit that converts the electrical energy of the high voltage power source system into a low voltage and charges the low voltage battery with the converted low voltage electrical energy; and a recovery unit that, when the observed voltage of the low voltage battery is lower than a preset minimum reference voltage at the time of a requirement to start the vehicle, activates the converter unit to recover the voltage of the low voltage battery to the preset minimum reference voltage, prior to a permission to operate the control unit.
In the vehicle of the present invention, in response to a requirement to start the vehicle, the converter unit converts the voltage of the high voltage battery into a low voltage, charges the low voltage battery with the converted low voltage electrical energy, and thereby recovers the voltage of the low voltage battery to the preset minimum reference voltage, prior to a permission to operate the control unit. This arrangement ensures a start of the vehicle even when the voltage of the low voltage battery is in a specific range that is determined to be insufficient for starting the vehicle in the prior art arrangement.
A variety of configurations may be applicable for the connections among the high voltage battery, the converter unit, and the low voltage battery. In one preferable embodiment of the present invention, the vehicle further includes a connection unit that is actuated by part of the control unit with a power supply from the low voltage power source system and connects the high voltage battery with the high voltage power source system including the converter unit. This configuration enables the converter unit to be controlled together with the other devices of the high voltage power source system. In this configuration, one applicable structure may inhibit the operation of the recovery unit when the observed voltage of the low voltage battery is lower than an operation inhibiting reference voltage. Here the operation inhibiting reference voltage corresponds to a lower limit voltage that guarantees the normal operation of the connection unit. This arrangement effectively prevents the process for recovering the vol
Gibson Eric M
Oliff & Berridg,e PLC
Toyota Jidosha & Kabushiki Kaisha
Zanelli Michael J.
LandOfFree
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