Auxiliary power supply

Abstract

The present invention provides an auxiliary power supply device that can reduce the potential difference between the power supply unit and the power supply unit that charges the device. [Solution] The auxiliary power supply unit 10 includes a power supply unit 20 that receives power from the power supply unit 12, a first charging path 22 connectable to the power supply unit 20, a second charging path 24 connectable to the power supply unit 20 and having a higher resistance than the first charging path 22, and a switch unit that can switch between the connection of the first charging path 22 and the power supply unit 20 and the connection of the second charging path 24 and the power supply unit 20. The switch unit switches from the connection of the first charging path 22 to the connection of the second charging path 24 when the potential difference between the power supply unit 12 and the power supply unit 20 is above a predetermined threshold.

Description

Technical Field

[0001] The present invention relates to an auxiliary power supply device mounted on a vehicle and capable of being charged.

Background Art

[0002] In Patent Document 1, a wireless charging device includes a wireless transmission circuit that transmits an electromagnetic signal and a communication control circuit. The communication control circuit wirelessly communicates with the device to be charged and adjusts the transmission power of the wireless transmission circuit so that the output current matches the charging current of the battery in the device to be charged.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the technology disclosed in Patent Document 1, control is performed to make the output current of the wireless charging device match the charging current of the battery. In charging the auxiliary power supply device of a vehicle, there is a limit to reducing the potential of the power supply side, and when the potential difference between the auxiliary power supply device and the power supply side becomes large, there is a risk that a large current will flow through the auxiliary power supply device.

[0005] An object of the present invention is to provide an auxiliary power supply device capable of reducing the potential difference between a power supply unit and a power supply unit to be charged.

Means for Solving the Problems

[0006] To solve the above problems, an auxiliary power supply device according to one aspect of the present invention comprises a power supply unit that receives power from a power supply unit, a first charging path connectable to the power supply unit, a second charging path connectable to the power supply unit and having a higher resistance than the first charging path, and a switch unit that can switch between the connection between the first charging path and the power supply unit and the connection between the second charging path and the power supply unit. The switch unit switches from the connection of the first charging path to the connection of the second charging path when the potential difference between the power supply unit and the power supply unit is greater than or equal to a predetermined threshold. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an auxiliary power supply device that can reduce the potential difference between the power supply unit and the power supply unit that charges the device. [Brief explanation of the drawing]

[0008] [Figure 1] This diagram shows the configuration of the auxiliary power supply unit of the first embodiment. [Figure 2] This diagram shows the configuration of the auxiliary power supply unit in the second embodiment. [Modes for carrying out the invention]

[0009] Figure 1 shows the configuration of the auxiliary power supply unit 10 of the first embodiment. The auxiliary power supply unit 10 is mounted on the vehicle and is provided separately from the main power supply for driving. The auxiliary power supply unit 10 may be composed of, for example, a lithium-ion battery. The auxiliary power supply unit 10 is provided as an integrated power pack. The vehicle equipped with the auxiliary power supply unit 10 may have an autonomous driving control function that enables autonomous driving.

[0010] The power supply unit 12 supplies power to the auxiliary power supply unit 10 when the vehicle is running. The power supply unit 12 is, for example, a step-down converter and is further connected upstream to the high-voltage power supply unit.

[0011] The auxiliary power supply unit 10 includes a power supply unit 20, a first charging path 22, a second charging path 24, a third charging path 26, a first switch unit 28, a second switch unit 30, a third switch unit 32, a first resistor unit 34, a second resistor unit 36, and a switch control unit (not shown).

[0012] The power supply unit 20 is composed of multiple cells and can be charged by receiving power from the power supply unit 12. The power supply unit 20 is at a first potential V1, which is detected by a potential detection sensor (not shown).

[0013] The first charging path 22, the second charging path 24, and the third charging path 26 can be connected to the power supply unit 12 and the power supply unit 20, respectively. The second charging path 24 is provided with a first resistor 34, which is not provided in the first charging path 22. Therefore, the second charging path 24 has a higher resistance value than the first charging path 22.

[0014] The third charging path 26 is provided with a first resistor 34 and a second resistor 36. Therefore, the third charging path 26 has a higher resistance value than the first charging path 22 and the second charging path 24. The first charging path 22 is at the second potential V2, and the second charging path 24 is at the third potential V3, which are detected by potential detection sensors (not shown). Each potential detection sensor sends the detection result to the control unit. The second potential V2 may be the potential of the power supply unit 12.

[0015] The first switch unit 28 is located in the first charging path 22 and switches the power supply unit 12 and the power supply unit 20 to a connected or disconnected state by switching it on or off. The second switch unit 30 is located in the second charging path 24 and switches the power supply unit 12 and the power supply unit 20 to a connected or disconnected state by switching it on or off.

[0016] The third switch unit 32 is located in the third charging path 26 and switches the power supply unit 12 and the power supply unit 20 to a connected or disconnected state by turning it on or off. The first switch unit 28, the second switch unit 30, and the third switch unit 32 are turned on or off by the control unit.

[0017] Any one of the first switch unit 28, the second switch unit 30, and the third switch unit 32 is turned on, and the other two are turned off. As a result, only any one of the first charging path 22, the second charging path 24, and the third charging path 26 connects the power supply unit 12 and the power source unit 20. The first switch unit 28, the second switch unit 30, and the third switch unit 32 may be collectively referred to as a switch unit.

[0018] The control unit calculates the potential difference between the power supply unit 12 and the power source unit 20, that is, the difference between the second potential V2 and the first potential V1. If the potential difference (V2 - V1) between the power supply unit 12 and the power source unit 20 is greater than or equal to the first threshold value, the control unit determines to use the third charging path 26, turns off the first switch unit 28 and the second switch unit 30, and turns on the third switch unit 32.

[0019] If the potential difference (V2 - V1) between the power supply unit 12 and the power source unit 20 is less than the first threshold value and greater than or equal to the second threshold value, the control unit determines to use the second charging path 24, turns off the first switch unit 28 and the third switch unit 32, and turns on the second switch unit 30. The second threshold value is smaller than the first threshold value. The first threshold value and the second threshold value are set by experiments or the like, but are preset based on the magnitudes of the first resistor unit 34 and the second resistor unit 36.

[0020] If the potential difference (V2 - V1) between the power supply unit 12 and the power source unit 20 is less than the second threshold value, the control unit determines to use the first charging path 22, turns off the second switch unit 30 and the third switch unit 32, and turns on the first switch unit 28. Thus, the auxiliary power supply device 10 has a plurality of charging paths with different resistance values and is switchable.

[0021] As the charging rate of the power source unit 20 decreases, the first potential V1 of the power source unit 20 decreases. There is a limit to the voltage drop in the power supply unit 12, and there is a limit to the minimum value of the second potential V2. If the potential difference between the power supply unit 12 and the power source unit 20 is excessively large, there is a risk that a large current will flow through the power source unit 20.

[0022] Therefore, when the potential difference between the power supply unit 12 and the power source unit 20 is greater than or equal to a predetermined second threshold value, the switch unit switches the connection from the first charging path 22 to the second charging path 24, and when the potential difference is greater than or equal to a predetermined first threshold value, the switch unit switches the connection from the first charging path 22 or the second charging path 24 to the third charging path 26. Thereby, by using the second charging path 24 and the third charging path 26, the potential difference between the power supply unit 12 and the power source unit 20 can be reduced, and the current value flowing through the power source unit 20 can be suppressed.

[0023] FIG. 2 is a diagram showing the configuration of the auxiliary power supply device 100 according to the second embodiment. The auxiliary power supply device 100 is different from the auxiliary power supply device 10 shown in FIG. 1 in that it includes a variable resistor unit 134. The auxiliary power supply device 100 includes a power source unit 20, a first charging path 122, a second charging path 124, a first switch unit 128, a second switch unit 130, a variable resistor unit 134, and a control unit.

[0024] The first charging path 122 and the second charging path 124 can each connect the power supply unit 12 and the power source unit 20. A variable resistor unit 134 is provided in the second charging path 124. Therefore, the second charging path 124 has a larger resistance value than the first charging path 122.

[0025] The first switch unit 128 is provided in the first charging path 122 and switches, by being turned on / off, between a state where the power supply unit 12 and the power source unit 20 are connected and a state where the connection is released. The second switch unit 130 is provided in the second charging path 124 and switches, by being turned on / off, between a state where the power supply unit 12 and the power source unit 20 are connected and a state where the connection is released.

[0026] Either the first switch unit 128 or the second switch unit 130 is turned on, and the other is turned off. Only one of the first charging path 122 and the second charging path 124 connects the power supply unit 12 and the power source unit 20.

[0027] The control unit decides to use the second charging path 124 if the potential difference (V2-V1) between the power supply unit 12 and the power supply unit 20 is greater than or equal to a predetermined threshold, and turns off the first switch unit 128 and turns on the second switch unit 130.

[0028] The control unit changes the resistance value of the variable resistor 134 according to the magnitude of the potential difference (V2-V1) between the power supply unit 12 and the power supply unit 20. The control unit increases the resistance value of the variable resistor 134 as the potential difference (V2-V1) between the power supply unit 12 and the power supply unit 20 increases. The variable resistor 134 allows the charging voltage (V2-V3) of the power supply unit 20 to be changed linearly.

[0029] The present disclosure has been explained above based on the examples described. The present disclosure is not limited to the examples described above, and various modifications such as design changes can be made based on the knowledge of those skilled in the art. [Explanation of Symbols]

[0030] 10 Auxiliary power supply unit, 12 Power supply unit, 20 Power supply unit, 22 First charging path, 24 Second charging path, 26 Third charging path, 28 First switch unit, 30 Second switch unit, 32 Third switch unit, 34 First resistor unit, 36 Second resistor unit.

Claims

[Claim 1] The power supply unit receives power from the power supply unit, A first charging path connectable to the power supply unit, A second charging path, which is connectable to the power supply unit and has a greater resistance than the first charging path, The device includes a switch that can switch between the connection of the first charging path and the power supply unit, and the connection of the second charging path and the power supply unit. The auxiliary power supply device is characterized in that the switch unit switches from the connection of the first charging path to the connection of the second charging path when the potential difference between the power supply unit and the power supply unit is greater than or equal to a predetermined threshold.

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