CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2019-072038 filed on Apr. 4, 2019, the contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a battery control unit and a battery system.

BACKGROUND ART

There is a battery system configured by connecting a plurality of batteries in series as a battery mounted on a vehicle to supply electric power to a drive source or to supply electric power to an auxiliary machine. Deterioration of the plurality of batteries varies due to variations of manufacturing or variations of operating environments and so on. For example, a battery near a heat source is rapidly deteriorated, while a battery far from the heat source is slowly deteriorated.

For this reason, the battery that has deteriorated at the time of charging or discharging reaches a charge/discharge end voltage first. In this case, the charging or discharging may have to be stopped even if there is remaining power in the other batteries, thus capacity of the batteries cannot be entirely consumed.

Therefore, it is considered to equalize charging states of the plurality of batteries (Patent Literature 1). However, if all the batteries are set to the same chargedischarge end voltage, a burden of the battery that has deteriorated may increase, thereby resulting in a larger variation of deterioration.

CITATION LIST

Patent Literature

[Patent Literature 1] WO2010/109956

SUMMARY OF INVENTION

The present invention has been made in view of the above circumstances, and an object thereof is to provide a battery control unit and a battery system which can reduce variations of deterioration of a plurality of batteries.

In order to achieve the above object, a battery control unit and a battery system according to the present invention are characterized by the following [1] to [5].

[1]

A battery control unit includes: a switching unit provided for each of a plurality of batteries arranged in series, and configured to switch between a connected state where the corresponding battery is connected in series with the other battery and a non-connected state where series connection between the corresponding battery and the other battery is disconnected; and a control unit configured to control the switching units corresponding to the battery to switch to the non-connected state when it is determined that the corresponding battery reaches a charge end voltage during charging or a discharge end voltage during discharging. The control unit changes the charge end voltage such that the charge end voltage of the battery, which is deteriorated, is lower than the charge end voltage of the batteries which are not deteriorated or changes the discharge end voltage such that the discharge end voltage of the battery, which is deteriorated, is higher than the discharge end voltage of the batteries which are not deteriorated.

[2]

In the battery control unit according to [1], the control unit changes the charge end voltage or the discharge end voltage such that a range between the charge end voltage and the discharge end voltage of the batteries which are deteriorated is narrower than a range between the charge end voltage and the discharge end voltage of the batteries which are not deteriorated.

[3]

In the battery control unit according to [1] or [2], the control unit changes the charge end voltage or the discharge end voltage in accordance with the number of the batteries which are switched to the non-connected state among the plurality of batteries.

[4]

In the battery control unit according to any one of [1] to [3], the control unit changes both the charge end voltage and the discharge end voltage.

[5]

A battery system includes: a plurality of batteries; and the battery control unit according to any one of [1] to [4].

According to the battery control unit and the battery system having the above configurations [1], [2], and [5], a depth of discharge of the deteriorated battery can be reduced to restrain progress of deterioration, thus the variations of deterioration of the plurality of batteries can be restrained.

According to the battery control unit having the above configuration [3], the depth of discharge of the deteriorated battery can be reduced even without detecting deterioration states of the plurality of batteries.

According to the battery control unit having the above configuration [4], by changing both the charge end voltage and the discharge end voltage, a range of variation of the range between the charge end voltage and the discharge end voltage can be increased, the deterioration of the deteriorated battery can be further restrained, and battery capacity of the batteries which are not deteriorated can be more effectively used.

According to the present invention, a battery control unit and a battery system, which can reduce the depth of discharge of the deteriorated battery to restrain the variation of deterioration of the plurality of batteries, can be provided.

The present invention has been briefly described above. Details of the present invention are further clarified by reading a mode for carrying out the present invention described below (hereinafter, referred to as “embodiment”) with reference to the accompanying drawings.

