Electricity: battery or capacitor charging or discharging – Battery or cell discharging – With charging
Reexamination Certificate
2000-08-30
2001-03-20
Wong, Peter S. (Department: 2838)
Electricity: battery or capacitor charging or discharging
Battery or cell discharging
With charging
C320S136000
Reexamination Certificate
active
06204636
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a battery control apparatus for controlling a battery mounted in a hybrid vehicle, more particularly to a battery control apparatus for controlling the amount of charging/discharging in accordance with the remaining charge of the battery using a nickel compound.
This application is based on Japanese Patent Application No. Hei 11-246744 (Unpublished), the contents of which are incorporated herein by reference.
2. Description of the Related Art
Conventionally, hybrid vehicles equipped with a motor in addition to an engine as a power source for driving are known. Hybrid vehicles include series hybrid vehicles and parallel hybrid vehicles. In series hybrid vehicles, a motor is driven by the generated output of a generator driven by an engine, and the wheels are driven by the motor. As described above, the engine and the wheels are not mechanically coupled to each other in series hybrid vehicles. Therefore, the engine can be operated at an almost constant RPM reducing fuel consumption and emissions, to provide lower fuel consumption and emissions than can be achieved by conventional engine vehicles.
As opposed to series hybrid vehicles, in parallel hybrid vehicles, a motor coupled to an engine supplements the driving of the driving shaft by the engine, and electric energy obtained by using the motor as a generator is stored in a power storage unit. In addition, the generated electric energy is used for electrical equipment installed in the vehicles. As described above, since the parallel hybrid vehicle can also reduce the drive load of the engine, lower fuel consumption and emissions, compared to conventional engine vehicles, can also be achieved.
The parallel hybrid vehicle includes a type in which the motor which supplements the output of the engine is directly coupled to the output shaft of the engine, and the motor functions as a generator during deceleration and stores the generated electricity in a battery, and a type in which driving force is generated by use of both, or one of, an engine and a motor, and a generator is provided separately.
In such hybrid vehicles, various kinds of controls are performed in such manner that the motor supplements the output of the engine during acceleration, and electricity is stored in the battery by deceleration regeneration during deceleration. This makes it possible to respond to the requirements of the driver while providing electrical energy to the battery (hereinafter referred to as “remaining battery charge” or “state of charge”).
The batteries used in hybrid vehicles often use nickel compounds in their positive electrode. In batteries using a nickel compound, a phenomenon in which an electromotive force value for the remaining battery charges changes due to repeated cycles of charging and discharging occurs. This phenomenon is referred to as a “memory effect” below. The memory effect has the characteristic that it is apt to occur in a battery using a nickel compound when the battery is repeatedly recharged before it has reached a completely discharged state, or repeatedly discharged before it has reached a completely charged state.
The batteries used in hybrid vehicles are controlled so as to be charged and discharged in the middle range of their remaining charge, to provide a long lifetime and high efficiency. For this reason, the batteries never reach the completely discharged state or the completely charged state, and they tend to develop a memory effect.
Since a range of the remaining battery charge available is narrowed by the occurrence of the memory effect, there is the problem that the time during which an operation for continuously supplementing the driving force of the engine and an operation for charging the battery by a deceleration regeneration can be continuously performed is reduced. Moreover, if the charge/discharge is performed only in a middle area of the remaining battery charge in a state in which the memory effect has occurred, the memory effect will further occur, and the range of the remaining battery charge available is reduced, resulting in a vicious cycle.
SUMMARY OF THE INVENTION
The present invention was made in view of the above circumstances, and the object of the present invention is to provide a battery control apparatus for a hybrid vehicle capable of extending the time over which the battery is continuously available, by controlling the amount of charge/discharge depending on a change in the voltage characteristics of the battery.
In the first aspect of the present invention, a battery control apparatus (for example, a battery control apparatus
9
in the embodiment) for a hybrid vehicle with a combustion (an engine
1
) for outputting driving force of the vehicle, an electric motor (a motor
2
) for generating a force for assisting the output from the engine, and a battery (a battery
8
) for supplying power to the motor and for storing energy regenerated by the motor acting as a generator when the assisting force is not required, the battery control apparatus comprising: a remaining battery charge calculator (a remaining battery charge calculating section
91
) for calculating a remaining charge of the battery; a memory effect detector (a memory effect detecting section
93
) for detecting the occurrence of the memory effect in the battery; a use permission zone determining device (a use permission zone determining section
94
) for determining a use permission zone of the remaining charge of the battery in accordance with the occurrence of the memory effect; and a charge/discharge amount controller (a charge/discharge controlling section
92
) for controlling an amount of charge/discharge in the use permission zone of the remaining charge of the battery.
With the above described constitution, when the voltage characteristic of the battery change due to the memory effect, the use permission zone of the remaining battery charge can be enlarged. Accordingly, the effect that the time of continuous availability for use of the battery can be lengthened is obtained. As a result, it is possible to prevent reductions of the time of continuous availability for the driving force supplementation operation for the engine and the charging operation to the battery by deceleration regeneration. Moreover, since enlarging the use permission zone makes it possible to allow the battery to approach to the completely charged state or the completely discharged state, the effect that the memory effect can be reversed is obtained.
A battery control apparatus according to a second aspect of the present invention further comprises a remaining battery charge correcting device (the remaining charge correcting section
91
c
) for detecting a voltage of the battery, comparing the detected voltage with a determination voltage corresponding to the remaining battery charge of a predetermined value, and correcting the remaining charge calculated by the remaining battery charge calculator to the predetermined value based on the comparison result of the detected voltage and the determination voltage, wherein, the use permission zone determining device changes the determination voltage when the remaining battery charge is corrected, in accordance with the occurrence of the memory effect.
With such a constitution, the effect that processing for calculating the remaining battery charge and correcting the remaining battery charge can be performed in the same way regardless of the occurrence of the memory effect, can be obtained.
A battery control apparatus according to a third aspect of the present invention further comprises a remaining battery charge correcting device (the remaining battery charge correcting section
91
c
) for detecting a voltage of the battery, comparing the detected voltage with a determination voltage corresponding to the remaining battery charge of a predetermined value, and correcting the remaining charge calculated by the remaining battery charge calculator to the predetermined value based on the comparison result of the dete
Fujimura Akira
Kawarada Nobuyuki
Kinoshita Naoki
Shibutani Atsushi
Arent Fox Kintner & Plotkin & Kahn, PLLC
Honda Giken Kogyo Kabushiki Kaisha
Toatley Jr. Gregory J
Wong Peter S.
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