JP2002051471A - Power supply system for vehicle, and method for estimating state of charging of the system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply system for vehicle where energy at deceleration of a vehicle, such as an automobile, can be sufficiently accepted as regenerative energy, and to provide a method for estimating the state of charging of the system that allows control of the state of charging with sufficient accuracy. SOLUTION: The power supply system for vehicle is formed, by connecting an aqueous secondary battery group 1 and a nonaqueous secondary battery group 2 with each other in parallel and combining them with a motor generator 3, a shunt 5, and a controller 6. The shunt 5 is for allocating the current which passes through, when the power supply system for vehicle functions to perform charging and discharging to the aqueous secondary battery group 1 and the nonaqueous secondary battery group 2, according to the respective capacity ratios thereof. The controller 6 is to monitor and control the state of charging of the nonaqueous secondary battery group 2 and furthermore to estimate the state of charging of the aqueous secondary battery group 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply system for a traveling vehicle used for an automobile or the like, and a method for estimating a state of charge in the system.

[0002]

2. Description of the Related Art Conventionally, a power supply system (14V system) equipped with a 12V lead storage battery has been used in automobiles. In the 14V system, a current is supplied (discharged) to a starting device (starter motor) for starting an automobile engine from a 12V lead storage battery. After the engine is started, a generator operated by the rotational force of the engine is used. Current is constantly supplied (charged) to the 12V lead storage battery. However, the energy when the vehicle decelerated was consumed as heat. In recent years, instead of 12V lead-acid batteries, 36V
A new power supply system (42V system) equipped with a system lead storage battery has been proposed. In the 42V system, a high-output motor generator can be used as a vehicle starting device for starting an engine of the vehicle, and the motor generator can use the energy that is conventionally consumed as heat during deceleration of the vehicle. It is intended to regenerate (charge) current into a 36V-based lead-acid battery by converting it into electrical energy as regenerative energy, thereby improving energy efficiency and improving fuel efficiency of an automobile.

[0003]

However, the motor generator used in the 42V system has a high output of 3 to 4 kW, and the current value during regeneration is 40 to 80 A (2 to 4 C).
A), but it is difficult for conventional lead-acid batteries to accept such high-current charging. That is, in the lead storage battery, when the charging rate becomes a current value of 1 C or more, the decomposition reaction of water, which is a side reaction at the time of charging, is promoted, and the charging efficiency is reduced, thereby adversely affecting the battery life. Therefore, the state of charge of the lead-acid battery is desirably controlled to 60% to 80%. In order to manage the state of charge of the lead-acid battery, a method of mainly measuring an open circuit voltage has been used. The open circuit voltage of the storage battery has a large error factor such as a long time until it is stabilized, and the management accuracy of the state of charge of the lead storage battery is not sufficient. An object of the present invention is to provide a traveling vehicle power supply system capable of sufficiently accepting energy at the time of deceleration of a traveling vehicle such as an automobile as regenerative energy, and a method for estimating a state of charge with sufficient management accuracy of the state of charge in the system. With the goal.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been made to achieve the above-mentioned object, and a power supply for a traveling vehicle in which an aqueous secondary battery group and a non-aqueous secondary battery group are connected in parallel. In a system, a charge / discharge circuit of the aqueous secondary battery and a charge / discharge circuit of the non-aqueous secondary battery are connected via a flow divider, and the current divider is connected to the aqueous secondary battery. The present invention is characterized in that a current is shunted so as to keep the state of charge of the group and the non-aqueous secondary battery group at the same level. In the power supply system for a traveling vehicle, the shunt is preferably configured to shunt current at a battery capacity ratio of each of the aqueous secondary battery group and the non-aqueous secondary battery group. The secondary battery group desirably includes a controller that controls the state of charge. The aqueous secondary battery group is composed of 18 cells of lead storage batteries connected in series, and the non-aqueous secondary battery group is composed of 10 to 11 cells of lithium secondary batteries connected in series. Preferably, the lead storage battery is a control valve type lead storage battery, and the lithium secondary battery is a lithium ion secondary battery. Further, according to the present invention, an aqueous secondary battery group and a non-aqueous secondary battery group are connected in parallel,
The charge / discharge circuit of the aqueous secondary battery and the charge / discharge circuit of the non-aqueous secondary battery are connected via a shunt,
A method for estimating a state of charge in a power supply system for a traveling vehicle, wherein the current divider shunts current to each of the aqueous secondary battery group and the non-aqueous secondary battery group, wherein the charging of the non-aqueous secondary battery group is performed. It is characterized in that the state of charge is estimated by detecting the state of the aqueous secondary battery. Still further, according to the present invention, an aqueous secondary battery group and a non-aqueous secondary battery group are connected in parallel, a charge / discharge circuit of the aqueous secondary battery, and a charge / discharge circuit of the non-aqueous secondary battery. Are connected via a shunt, and the shunt divides a current to each of the aqueous secondary battery group and the non-aqueous secondary battery group. By detecting the initial state of charge of the aqueous secondary battery group and the non-aqueous secondary battery group, and the rate of change in the state of charge of the non-aqueous secondary battery group, the aqueous secondary battery group It is characterized in that the state of charge is estimated. In the method for estimating a state of charge in each of the power supply systems for a traveling vehicle, the aqueous secondary battery group is composed of 18-cell lead storage batteries connected in series, and the non-aqueous secondary battery group is connected in series. Preferably, the lead storage battery is a control valve type lead storage battery, and the lithium secondary battery is a lithium ion secondary battery.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples, and may be appropriately changed within the scope of the invention. Can be implemented. Here, the aqueous secondary battery group or the non-aqueous secondary battery group refers to an assembled battery in which a plurality of cells of the aqueous secondary battery or the non-aqueous secondary battery are combined. [Description of Aqueous Solution Secondary Battery] As the aqueous solution secondary battery used in the present invention, a so-called lead storage battery, particularly a control valve type lead storage battery can be exemplified. This battery is prepared as follows. Using a positive electrode, a negative electrode, and a glass fiber separator, using lead dioxide for the positive electrode and sea-surface lead for the negative electrode, a laminated electrode group is prepared and inserted into a rectangular battery case.
A lid with an open control valve is attached thereto, dilute sulfuric acid as an electrolyte is injected, and the control valve is attached to seal the battery. The 5-hour capacity of this battery is 18 Ah. [Description of Nonaqueous Secondary Battery] As the nonaqueous secondary battery used in the present invention, a so-called lithium secondary battery, particularly a lithium ion secondary battery, can be used. This battery is prepared as follows. A manganese oxide containing lithium is used for the positive electrode, and a carbon powder, which is an active material, is used for the negative electrode. Using the positive electrode, the negative electrode, and the separator, a wound electrode body is manufactured and inserted into a cylindrical battery can. I do. An electrolytic solution is injected into this, and the container is sealed with a sealing member also serving as a positive electrode terminal. The 5-hour rate capacity of this battery is 3 Ah. [Configuration of Power Supply System for Traveling Vehicle] A power supply system for a traveling vehicle in which an aqueous secondary battery group 1 and a non-aqueous secondary battery group 2 are connected in parallel and a motor generator 3, a shunt 5, and a controller 6 are combined. As shown in FIG. In FIG. 1, a 36V-system control valve-type lead storage battery (36V-18Ah) composed of 18 cells is used for an aqueous secondary battery group 1, and a lithium ion secondary battery ( 3.6
V-3Ah) is used in series with 10 cells, and the battery voltage of the nonaqueous secondary battery group 2 is 36V. The shunt 5
The current flowing at the time of charging and discharging as the power supply system for a traveling vehicle is distributed to the aqueous secondary battery group 1 and the non-aqueous secondary battery group 2 at respective capacity ratios (18 Ah / 3 Ah). 6 is a non-aqueous secondary battery group 2
In addition to monitoring and controlling the state of charge of the battery, the state of charge of the aqueous secondary battery group 1 is estimated. [Operation of Power System for Traveling Vehicle] When the vehicle is started, it is started by the output from the aqueous secondary battery group 1. On the other hand, the regenerative energy generated during braking is partially regenerated (charged) in the aqueous secondary battery group 1 as electric energy, but is regenerated (charged) in the non-aqueous secondary battery group 2 having a higher regenerative capacity. Therefore, the energy efficiency as a power supply system for a traveling vehicle is enhanced. The current flowing during charging / discharging as the power supply system for a traveling vehicle is distributed by the shunt 5 so that the charged state of each of the aqueous secondary battery group 1 and the non-aqueous secondary battery group 2 is maintained at the same level. Therefore, if the charge state of one non-aqueous secondary battery group 2 is detected by the controller 6, it is possible to sufficiently estimate the charge state of the other aqueous secondary battery group 1 which is difficult to manage. Also, if the initial charge states of the aqueous secondary battery group 1 and the non-aqueous secondary battery group 2 are known, the rate of change of the charge state of the non-aqueous secondary battery group 2 can be detected. The state of charge of the aqueous secondary battery group 2 can be estimated.

[0006]

As described above, according to the present invention, by effectively combining the aqueous secondary battery group and the non-aqueous secondary battery group, the energy at the time of braking of a running vehicle such as an automobile is converted into regenerative energy. It can be used well, and by detecting the state of charge of one non-aqueous secondary battery group, the state of charge of the other aqueous secondary battery group can be sufficiently estimated. The target value is extremely large.

[Brief description of the drawings]

FIG. 1 is a block diagram of a power supply system for a traveling vehicle according to the present invention.

[Explanation of symbols]

1: aqueous solution type secondary battery group, 2: non-aqueous type secondary battery group, 3:
Motor generator, 4: Load, 5: Current divider, 6: Controller

Claims (9)

[Claims] 1. A power supply system for a traveling vehicle in which an aqueous secondary battery group and a non-aqueous secondary battery group are connected in parallel, comprising: a charge / discharge circuit for the aqueous secondary battery; The charge / discharge circuit of the secondary battery is connected via a current divider, and the current divider keeps the charge state of each of the aqueous secondary battery group and the non-aqueous secondary battery group at the same level. A power supply system for a traveling vehicle, which shunts the current as described above. 2. The shunt according to claim 1, wherein the shunt shunts the current at a battery capacity ratio of each of the aqueous secondary battery group and the non-aqueous secondary battery group. Power supply system for traveling vehicles. 3. The power supply system for a traveling vehicle according to claim 1, wherein said non-aqueous secondary battery group includes a controller for controlling a state of charge. 4. The aqueous secondary battery group is composed of 18 cells of lead storage batteries connected in series, and the non-aqueous secondary battery group is composed of 10 to 11 cells of lithium secondary batteries connected in series. The power supply system for a traveling vehicle according to claim 1 or 2, wherein the power supply system is configured by a battery. 5. The power supply system for a running vehicle according to claim 4, wherein said lead storage battery is a control valve type lead storage battery, and said lithium secondary battery is a lithium ion secondary battery. 6. An aqueous secondary battery group and a non-aqueous secondary battery group are connected in parallel, and a charge / discharge circuit of the aqueous secondary battery and a charge / discharge circuit of the non-aqueous secondary battery are divided. A charging state estimation method in a power supply system for a traveling vehicle that shunts current to each of the aqueous secondary battery group and the non-aqueous secondary battery group.
A method for estimating a state of charge in a power supply system for a traveling vehicle, comprising: estimating a state of charge of the aqueous secondary battery by detecting a state of charge of the non-aqueous secondary battery group. 7. An aqueous secondary battery group and a non-aqueous secondary battery group are connected in parallel, and a charge / discharge circuit of the aqueous secondary battery and a charge / discharge circuit of the non-aqueous secondary battery are divided. A charging state estimation method in a power supply system for a traveling vehicle that shunts current to each of the aqueous secondary battery group and the non-aqueous secondary battery group.
The initial state of charge of the aqueous secondary battery group and the non-aqueous secondary battery group, and the rate of change of the state of charge of the non-aqueous secondary battery group are detected to detect the state of charge of the aqueous secondary battery group. A method for estimating a state of charge in a power supply system for a traveling vehicle, comprising: 8. The aqueous secondary battery group is composed of 18 cells of lead storage batteries connected in series, and the non-aqueous secondary battery group is composed of 10 to 11 cells of lithium secondary batteries connected in series. 8. The method for estimating a state of charge in a power supply system for a traveling vehicle according to claim 6, wherein the method comprises a battery. 9. A state of charge in a power supply system for a running vehicle according to claim 8, wherein said lead storage battery is a control valve type lead storage battery, and said lithium secondary battery is a lithium ion secondary battery. Estimation method.