CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the U.S. national stage of PCT/JP2019/030116 filed on Aug. 1, 2019, which claims priority of Japanese Patent Application No. JP 2018-145699 filed on Aug. 2, 2018, the contents of which are incorporated herein.

TECHNICAL FIELD

The present disclosure relates to an in-vehicle backup power source control apparatus and an in-vehicle backup power source apparatus.

BACKGROUND

Techniques for backing up an in-vehicle power source unit are known as in-vehicle power source systems. In a system described in JP 2017-70057A, for example, if there is a failure or the like in a vehicle battery that is an in-vehicle power source unit, a voltage adjusted by a voltage boosting circuit based on an output voltage of a capacitor unit that is a power storage unit is output to a load. This realizes backup of the in-vehicle power source unit.

However, in such a system, increases in the cost and size of the power storage unit due to an increase in the capacity of the power storage unit have been a problem.

The present disclosure has been made in order to solve at least one of the above-described issues, and aims to effectively suppress an increase in the capacity of a power storage unit.

SUMMARY

An in-vehicle backup power source control apparatus according to a first aspect of the present disclosure uses, as a backup power source, a power storage unit that is charged by an in-vehicle power source unit, and controls a discharge operation of the power storage unit. The in-vehicle backup power source control apparatus includes a voltage conversion unit that performs a voltage conversion operation for stepping up or down a voltage applied to a first conductive path that is a path through which power is supplied from the power storage unit, and applies an output voltage to a second conductive path that, along with a third conductive path that is connected to a backup target load, constitutes a path for supplying power to the backup target load. A control unit controls the voltage conversion operation such that the output voltage that is applied to the second conductive path by the voltage conversion unit reaches a target voltage. A temperature obtaining unit obtains a temperature of the power storage unit, and when the temperature obtained by the temperature obtaining unit is within a predetermined first temperature range, the control unit sets the target voltage to a first target voltage, and, when the temperature obtained by the temperature obtaining unit is within a predetermined second temperature range that is higher than the first temperature range, the control unit sets the target voltage to a second target voltage that is higher than the first target voltage.

An in-vehicle backup power source control apparatus according to a second aspect of the present disclosure uses, as a backup power source, a power storage unit that is charged by an in-vehicle power source unit, and controls a discharge operation of the power storage unit. The in-vehicle backup power source control apparatus includes a voltage conversion unit that performs a voltage conversion operation for stepping up or down a voltage applied to a first conductive path that is a path through which power is supplied from the power storage unit, and applies an output voltage to a second conductive path that, along with a third conductive path that is connected to a backup target load, constitutes a path for supplying power to the backup target load. A control unit controls the voltage conversion operation such that the output voltage that is applied to the second conductive path by the voltage conversion unit reaches a target voltage. A temperature obtaining unit obtains a temperature of the power storage unit, and the higher the temperature obtained by the temperature obtaining unit is, the higher the target voltage the control unit sets.

An in-vehicle backup power source control apparatus according to a third aspect of the present disclosure uses, as a backup power source, a power storage unit that is charged by an in-vehicle power source unit, and controls a discharge operation of the power storage unit. The in-vehicle backup power source control apparatus includes a voltage conversion unit that performs a voltage conversion operation for stepping up or down a voltage applied to a first conductive path that is a path through which power is supplied from the power storage unit, and applying an output voltage to a second conductive path that, along with a third conductive path that is connected to a backup target load, constitutes a path for supplying power to the backup target load. A control unit controls the voltage conversion operation such that the output voltage that is applied to the second conductive path by the voltage conversion unit reaches a target voltage. A temperature obtaining unit obtains a temperature of the third conductive path, and when the temperature obtained by the temperature obtaining unit is within a predetermined first temperature range, the control unit sets the target voltage to a first target voltage, and, when the temperature obtained by the temperature obtaining unit is within a predetermined second temperature range that is higher than the first temperature range, the control unit sets the target voltage to a second target voltage that is higher than the first target voltage.

An in-vehicle backup power source control apparatus according to a fourth aspect of the present disclosure uses, as a backup power source, a power storage unit that is charged by an in-vehicle power source unit, and controls a discharge operation of the power storage unit. The in-vehicle backup power source control apparatus includes a voltage conversion unit that performs a voltage conversion operation for stepping up or down a voltage applied to a first conductive path that is a path through which power is supplied from the power storage unit, and applying an output voltage to a second conductive path that, along with a third conductive path that is connected to a backup target load, constitutes a path for supplying power to the backup target load. A control unit controls the voltage conversion operation such that the output voltage that is applied to the second conductive path by the voltage conversion unit reaches a target voltage. A temperature obtaining unit obtains a temperature of the third conductive path, and the higher the temperature obtained by the temperature obtaining unit is, the higher the target voltage the control unit sets.

An in-vehicle backup power source apparatus according to a fifth aspect of the present disclosure includes the power storage unit, and the in-vehicle backup power source control apparatus according to any one of the first to fourth aspects.

Advantageous Effects of Disclosure

In the above-described in-vehicle backup power source control apparatus according to the first aspect, the control unit controls the control voltage conversion operation such that the output voltage that is applied to the second conductive path by the voltage conversion unit reaches the target voltage. It is necessary to determine the target voltage at this time in anticipation of power loss due to the resistance of the third conductive path that connects the second conductive path and the backup target load. In particular, when the temperature of the third conductive path is high, the resistance of the third conductive path is high, and thus, it is necessary to determine the target voltage so as to supply power required for driving the backup target load, to the backup target load even when the resistance of the third conductive path is high. On the other hand, when the temperature of the power storage unit is low, the internal resistance of the power storage unit is high. Thus, the power storage unit needs to have a capacity sufficient for generating the target voltage even when the internal resistance is high.

Under the above circumstances, a configuration is adopted in which, when the temperature of the power storage unit is within the predetermined first temperature range, the control unit sets the target voltage to the first target voltage, and when the temperature of the power storage unit is within the predetermined second temperature range that is higher than the first temperature range, the control unit sets the target voltage to the second target voltage that is higher than the first target voltage. In addition, it is envisioned that, when the temperature of the power storage unit is relatively low, the temperature of the third conductive path is also relatively low, and when the temperature of the power storage unit is relatively high, the temperature of the third conductive path is also relatively high.

Therefore, when the temperatures of the power storage unit and the third conductive path are relatively low, the internal resistance of the power storage unit is relatively high, but the target voltage is set to the first target voltage that is relatively low, and thus it is possible to mitigate the burden on the power storage unit while suppressing excessive supply of power to the backup target load. Conversely, when the temperatures of the power storage unit and the third conductive path are relatively high, the resistance of the third conductive path is relatively high, but the internal resistance of the power storage unit is low, and thus, it is possible to supply drive power to the backup target load while suppressing an increase in the capacity of the power storage unit by setting the target voltage to the second target voltage that is relatively high. Therefore, it is possible to effectively suppress an increase in the capacity of the power storage unit.

In the above-described in-vehicle backup power source control apparatus according to the second aspect, the control unit controls the voltage conversion operation such that the output voltage that is applied to the second conductive path by the voltage conversion unit reaches the target voltage. It is necessary to determine the target voltage at this time in anticipation of power loss due to the resistance of the third conductive path that connects the second conductive path and the backup target load. In particular, when the temperature of the third conductive path is high, the resistance of the third conductive path is high, and thus it is necessary to determine the target voltage so as to supply power required for driving the backup target load, to the backup target load even when the resistance of the third conductive path is high. On the other hand, when the temperature of the power storage unit is low, the internal resistance of the power storage unit is high. Thus, the power storage unit needs to have a capacity sufficient for generating the target voltage even when the internal resistance is high.

Under the above circumstances, a configuration is adopted in which the higher the temperature of the power storage unit is, the higher the target voltage the control unit sets. In addition, it is envisioned that, when the temperature of the power storage unit is relatively low, the temperature of the third conductive path is also relatively low, and when the temperature of the power storage unit is relatively high, the temperature of the third conductive path is also relatively high.

Therefore, when the temperatures of the power storage unit and the third conductive path are relatively low, the internal resistance of the power storage unit is relatively high, but the target voltage is set to a relatively low target voltage, and thus it is possible to mitigate the burden on the power storage unit while suppressing excessive supply of power to the backup target load. Conversely, when the temperatures of the power storage unit and the third conductive path are relatively high, the resistance of the third conductive path is relatively high, but the internal resistance of the power storage unit is low, and thus it is possible to supply drive power to the backup target load while suppressing an increase in the capacity of the power storage unit, by setting the target voltage to a relatively high target voltage. Therefore, it is possible to effectively suppress an increase in the capacity of the power storage unit.

In the above-described in-vehicle backup power source control apparatus according to the third aspect, the control unit controls the voltage conversion operation such that the output voltage that is applied to the second conductive path by the voltage conversion unit reaches the target voltage. It is necessary to determine the target voltage at this time in anticipation of power loss due to the resistance of the third conductive path that connects the second conductive path and the backup target load. In particular, when the temperature of the third conductive path is high, the resistance of the third conductive path is high, and thus, it is necessary to determine the target voltage so as to supply power required for driving the backup target load, to the backup target load even when the resistance of the third conductive path is high. On the other hand, when the temperature of the power storage unit is low, the internal resistance of the power storage unit is high. Thus, the power storage unit needs to have a capacity sufficient for generating the target voltage even when the internal resistance is high.

Under the above circumstances, a configuration is adopted in which, when the temperature of the third conductive path is within the predetermined first temperature range, the control unit sets the target voltage to the first target voltage, and when the temperature of the third conductive path is within the predetermined second temperature range that is lower than the first temperature range, the control unit sets the target voltage to the second target voltage that is higher than the first target voltage. In addition, it is envisioned that, when the temperature of the third conductive path is relatively low, the temperature of the power storage unit is also relatively low, and when the temperature of the third conductive path is relatively high, the temperature of the power storage unit is also relatively high.

Therefore, when the temperatures of the power storage unit and the third conductive path are relatively low, the internal resistance of the power storage unit is relatively high, but the target voltage is set to the first target voltage that is relatively low, and thus it is possible to mitigate the burden on the power storage unit while suppressing excessive supply of power to the backup target load. Conversely, when the temperatures of the power storage unit and the third conductive path are relatively high, the resistance of the third conductive path is relatively high, but the internal resistance of the power storage unit is low, and thus, it is possible to supply drive power to the backup target load while suppressing an increase in the capacity of the power storage unit by setting the target voltage to the second target voltage that is relatively high. Therefore, it is possible to effectively suppress an increase in the capacity of the power storage unit.

In the above-described in-vehicle backup power source control apparatus according to the fourth aspect, the control unit controls the control voltage conversion operation such that the output voltage that is applied to the second conductive path by the voltage conversion unit reaches the target voltage. It is necessary to determine the target voltage at this time in anticipation of power loss due to the resistance of the third conductive path that connects the second conductive path and the backup target load. In particular, when the temperature of the third conductive path is high, the resistance of the third conductive path is high, and thus it is necessary to determine the target voltage so as to supply power required for driving the backup target load, to the backup target load even when the resistance of the third conductive path is high. On the other hand, when the temperature of the power storage unit is low, the internal resistance of the power storage unit is high. Thus, the power storage unit needs to have a capacity sufficient for generating the target voltage even when the internal resistance is high.

Under the above circumstances, a configuration is adopted in which, the higher the temperature of the third conductive path is, the higher the target voltage the control unit sets. In addition, it is envisioned that, when the temperature of the third conductive path is relatively low, the temperature of the power storage unit is also relatively low, and when the temperature of the third conductive path is relatively high, the temperature of the power storage unit is also relatively high.

Therefore, when the temperatures of the power storage unit and the third conductive path are relatively low, the internal resistance of the power storage unit is relatively high, but the target voltage is set to a relatively low target voltage, and thus it is possible to mitigate the burden on the power storage unit while suppressing excessive supply of power to the backup target load. Conversely, when the temperatures of the power storage unit and the third conductive path are relatively high, the resistance of the third conductive path is relatively high, but the internal resistance of the power storage unit is low, and thus it is possible to supply drive power to the backup target load while suppressing an increase in the capacity of the power storage unit by setting the target voltage to a relatively high target voltage. Therefore, it is possible to effectively suppress an increase in the capacity of the power storage unit.

According to the above-described in-vehicle backup power source apparatus, it is possible to achieve the same effects as the in-vehicle backup power source control apparatus according to first to fourth aspects.

