Battery charging system

Abstract

To provide a charging system of a battery capable of shortening a time until a charging state of each battery reaches a predetermined charging state when charging a plurality of batteries.SOLUTION: And a control device 5 configured to charge the first battery 3 with a low voltage suitable for the first battery 3 until a charge amount of the first battery 3 becomes equal to or greater than a first predetermined value, and to disconnect the first battery 3 and charge the second battery 4 with a high voltage suitable for the second battery 4 when the charge amount of the first battery 3 becomes equal to or greater than the first predetermined value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a battery charging system. [Background technology]

[0002] Patent document 1 describes a system equipped with two types of batteries with different characteristics, in which the first battery and the second battery are connected in parallel and charged using constant current and constant voltage charging, and when a drop in charging current is detected, the connection to the first battery is cut off, allowing charging current to flow to the second battery.

[0003] It is desirable to charge at a higher voltage because the higher the voltage, the shorter the charging time. However, if the voltage is too high, the battery may be damaged. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2016 / 035280 Summary of the Invention [Problem to be solved by the invention]

[0005] In the charging method described in Patent Document 1, two batteries are charged simultaneously, and when charging of one battery is completed, that battery is disconnected and only the other battery is charged (hereinafter referred to as "individual charging"). As a result, until charging of the battery with the lower upper limit voltage is completed, the charging voltage is set to match that of the battery with the lower upper limit voltage, which is not efficient from the perspective of charging the battery with the higher upper limit voltage.

[0006] Therefore, an object of the present invention is to provide a battery charging system that can shorten the time required to bring each battery to a predetermined charge state when charging multiple batteries. [Means for solving the problem]

[0007] In order to solve the above problem, the present invention provides a vehicle battery charging system comprising a first battery, a second battery having an upper limit voltage higher than that of the first battery, and a generator that supplies power to the first battery and the second battery, and is equipped with a control device that charges the first battery at a low voltage suitable for the first battery until the charge amount of the first battery reaches or exceeds a first predetermined value, and when the charge amount of the first battery reaches or exceeds the first predetermined value, disconnects the first battery and charges the second battery at a high voltage suitable for the second battery. [Effects of the Invention]

[0008] Thus, according to the present invention, when charging a plurality of batteries, it is possible to reduce the time required to bring each battery to a predetermined charge state. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a block diagram of a vehicle equipped with a battery charging system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a flowchart showing the procedure of the charging control process of the battery charging system according to one embodiment of the present invention. [Figure 3] FIG. 3 is a time chart showing changes in the charge amount of the battery due to the charge control process of the battery charging system according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] A battery charging system according to one embodiment of the present invention is a vehicle battery charging system including a first battery, a second battery having a higher upper limit voltage than the first battery, and a generator that supplies power to the first battery and the second battery, and is configured to include a control device that charges the first battery at a low voltage suitable for the first battery until the charge amount of the first battery reaches or exceeds a first predetermined value, and that disconnects the first battery and charges the second battery at a high voltage suitable for the second battery when the charge amount of the first battery reaches or exceeds the first predetermined value.

[0011] As a result, the battery charging system according to one embodiment of the present invention can reduce the time required to bring each battery to a predetermined charge state when charging a plurality of batteries. [Example]

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A battery charging system according to an embodiment of the present invention will be described in detail below with reference to the drawings.

[0013] In FIG. 1, a vehicle 1 equipped with a battery charging system according to a first embodiment of the present invention includes a generator 2, a first battery 3, a second battery 4, and a control device 5.

[0014] The generator 2 generates electric power using, for example, the driving force of an engine (not shown). The generator 2 supplies the generated electric power to the first battery 3 and the second battery 4.

[0015] The first battery 3 is a battery with a low upper limit voltage and is configured, for example, as a lead storage battery.

[0016] A first switch 31 is connected between the first battery 3 and the generator 2 to electrically disconnect or connect the generator 2 and the first battery 3.

[0017] A first current sensor 32 that detects the current flowing through the first battery 3 is connected between the first battery 3 and the ground terminal. The control device 5 can calculate the charge amount of the first battery 3 based on the current value detected by the first current sensor 32.

[0018] The second battery 4 has a higher upper limit voltage than the first battery 3. The second battery 4 is, for example, a lithium ion battery.

[0019] A second switch 41 is connected between the second battery 4 and the generator 2 to electrically disconnect or connect the generator 2 and the second battery 4.

[0020] A second current sensor 42 that detects the current flowing through the second battery 4 is connected between the second battery 4 and the ground terminal. The control device 5 can calculate the charge amount of the second battery 4 based on the current value detected by the second current sensor 42.

[0021] The control device 5 is composed of a computer unit equipped with a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), flash memory for storing backup data, etc., input ports, and output ports.

[0022] The ROM of this computer unit stores a program for causing the computer unit to function as the control device 5, along with various constants and maps.

[0023] That is, the CPU executes the program stored in the ROM using the RAM as a work area, and this computer unit functions as the control device 5 in this embodiment.

[0024] To the input port of the control device 5, various sensors including the first current sensor 32 and the second current sensor 42 described above are connected.

[0025] On the other hand, various controlled objects including the generator 2, the first switch 31, and the second switch 41 described above are connected to the output port of the control device 5.

[0026] The control device 5 can charge the first battery 3 and the second battery 4 simultaneously with the electric power generated by the generator 2.

[0027] When simultaneously charging the first battery 3 and the second battery 4, the control device 5 first connects the first switch 31 to the connected state to connect the first battery 3 to the generator 2, and charges the first battery 3 at a low voltage suitable for the first battery 3, which has a low upper limit voltage. At this time, the control device 5 may also connect the second switch 41 to the connected state to connect the second battery 4 to the generator 2, and charge the second battery 4 simultaneously with the first battery 3.

[0028] When the charge amount of the first battery 3 reaches or exceeds a first predetermined value, the control device 5 disconnects the first switch 31 to separate the first battery 3 from the generator 2, and connects the second switch 41 to the generator 2 to charge the second battery 4 with a high voltage suitable for the second battery 4, which has a high upper limit voltage. The charge amount is expressed as a percentage, with a fully charged battery being 100%.

[0029] The first predetermined value is, for example, the charge amount of each battery at which idling stop, which automatically stops the engine of the vehicle 1, is permitted.

[0030] This reduces the time it takes for the charge amounts of both the first battery 3 and the second battery 4 to reach or exceed the first predetermined value. If the first predetermined value is the charge amount at which idling stop is permitted, the frequency of idling stop can be increased, improving fuel efficiency.

[0031] When the charge amount of the second battery 4 becomes equal to or greater than a second predetermined value, the control device 5 connects the first battery 3 to the generator 2 by connecting the first switch 31, and simultaneously charges the first battery 3 and the second battery 4 at a low voltage suitable for the first battery 3, which has a low upper limit voltage.

[0032] The second predetermined value is, for example, the charge amount of each battery at which no-power-generation control is permitted, in which power generation by the generator 2 is stopped and the power required for the vehicle 1 is supplied from two or one batteries.

[0033] This reduces the time it takes for the charge amounts of both the first battery 3 and the second battery 4 to reach or exceed the second predetermined value. When the second predetermined value is the charge amount at which non-power generation control is permitted, the frequency of non-power generation control can be increased, improving fuel efficiency.

[0034] Although the battery power lost due to the non-power generation control must be restored, overall fuel efficiency can be improved by generating power without using fuel through regeneration or by generating power when the vehicle 1's engine, etc., is efficient.

[0035] When the charge amount of the first battery 3 becomes equal to or greater than the third predetermined value, the control device 5 simultaneously charges the first battery 3 and the second battery 4 at a low voltage suitable for the first battery 3, which has a low upper limit voltage.

[0036] The third predetermined value is, for example, the charge amount of each battery at which suppressed power generation control is permitted, in which the power generation voltage is matched to the battery voltage to prevent charging or discharging of the battery, and only power is generated to supply to the electrical loads of the vehicle 1. The suppressed power generation control can reduce the fuel used to charge the battery. Note that since the first battery 3 and the second battery 4 have different voltages, during suppressed power generation control, one battery is disconnected and the power generation voltage is matched to the voltage of the other battery.

[0037] When charging of the first battery 3 is completed, the control device 5 disconnects the first switch 31 to the disconnected state, thereby separating the first battery 3 from the generator 2, and charges only the second battery 4 with a high voltage suitable for the second battery 4 until charging of the second battery 4 is completed.

[0038] In this embodiment, since non-power generation control has a greater fuel reduction effect than suppressed power generation control, the second predetermined value is set to the charge amount at which non-power generation control is permitted so that non-power generation control is permitted earlier, but this is not limited to this, and the settings of the first to third predetermined values ​​are merely examples.

[0039] Since idling stop has the greatest fuel saving effect, when the electrical load is large, suppressed power generation control may be permitted first to prevent the battery charge from decreasing, and since idling stop is performed when the vehicle is stopped, no power generation control may be permitted first in the high vehicle speed range.

[0040] The charging control process performed by the battery charging system according to this embodiment configured as described above will be described with reference to Fig. 2. The charging control process described below is started when it is determined that charging of the first battery 3 and the second battery 4 is required.

[0041] In step S1, the control device 5 determines whether the charge amount of the first battery 3 is equal to or greater than a first predetermined value.

[0042] If it is determined that the charge amount of the first battery 3 is equal to or greater than the first predetermined value, the control device 5 executes the process of step S3. If it is determined that the charge amount of the first battery 3 is not equal to or greater than the first predetermined value, the control device 5 executes the process of step S2.

[0043] In step S2, the control device 5 charges the first battery 3 at a low voltage suitable for the first battery 3. After executing the process of step S2, the control device 5 executes the process of step S1.

[0044] In step S3, the control device 5 determines whether the charge amount of the second battery 4 is equal to or greater than a second predetermined value.

[0045] If it is determined that the charge amount of the second battery 4 is equal to or greater than the second predetermined value, the control device 5 executes the process of step S5. If it is determined that the charge amount of the second battery 4 is not equal to or greater than the second predetermined value, the control device 5 executes the process of step S4.

[0046] In step S4, the control device 5 disconnects the first battery 3 and charges the second battery 4 with a high voltage suitable for the second battery 4. After executing the process of step S4, the control device 5 executes the process of step S3.

[0047] In step S5, the control device 5 determines whether the charge amount of the first battery 3 is equal to or greater than a third predetermined value.

[0048] If it is determined that the charge amount of the first battery 3 is equal to or greater than the third predetermined value, the control device 5 executes the process of step S7. If it is determined that the charge amount of the first battery 3 is not equal to or greater than the third predetermined value, the control device 5 executes the process of step S6.

[0049] In step S6, the control device 5 charges the first battery 3 and the second battery 4 at a low voltage suitable for the first battery 3. After executing the process of step S6, the control device 5 executes the process of step S5.

[0050] In step S7, the control device 5 determines whether or not charging of the first battery 3 has been completed.

[0051] If it is determined that charging of the first battery 3 is complete, the control device 5 executes the process of step S9. If it is determined that charging of the first battery 3 is not complete, the control device 5 executes the process of step S8.

[0052] In step S8, the control device 5 charges the first battery 3 and the second battery 4 at a low voltage suitable for the first battery 3. After executing the process of step S8, the control device 5 executes the process of step S7.

[0053] In step S9, the control device 5 disconnects the first battery 3 and charges the second battery 4 with a high voltage suitable for the second battery 4 until charging of the second battery 4 is completed. After executing the process of step S9, the control device 5 ends the charge control process.

[0054] The operation of such a charge control process will be described with reference to Fig. 3. In Fig. 3, the line indicated by A shows the change in the charge amount of the first battery 3 according to this embodiment, the line indicated by B shows the change in the charge amount of the second battery 4 according to this embodiment, the line indicated by C shows the change in the charge amount of the first battery 3 due to individual charging, and the line indicated by D shows the change in the charge amount of the second battery 4 due to individual charging.

[0055] In both this embodiment and the individual charging, the first battery 3 and the second battery 4 are charged at a low voltage suitable for the first battery 3 when charging starts.

[0056] At time t1, when the charge amount of the first battery 3 reaches or exceeds a first predetermined value, in individual charging, charging continues as is, but in this embodiment, the first battery 3 is disconnected and the second battery 4 is charged with a high voltage suitable for the second battery 4.

[0057] In this embodiment, at time t2, the charge amount of the second battery 4 also becomes equal to or greater than the first predetermined value, and if the first predetermined value is the charge amount at which idling stop is permitted, idling stop is permitted at time t2.

[0058] At time t3, in this embodiment, the charge amount of the second battery 4 becomes equal to or greater than the second predetermined value, and the first battery 3 and the second battery 4 are charged at a low voltage suitable for the first battery 3.

[0059] At time t4, in this embodiment, if the charge amount of the first battery 3 also becomes equal to or greater than the second predetermined value, and the second predetermined value is the charge amount at which non-power generation control is permitted, non-power generation control is permitted at time t4.

[0060] At time t5, in individual charging, the charge amount of the second battery 4 also becomes equal to or greater than the first predetermined value, and if the first predetermined value is the charge amount at which idling stop is permitted, idling stop is permitted at time t5.

[0061] At time t6, in individual charging, the charge amount of the second battery 4 also becomes equal to or greater than the second predetermined value, and if the second predetermined value is the charge amount at which non-power generation control is permitted, non-power generation control is permitted at time t6.

[0062] At time t7, in this embodiment, charging of the first battery 3 is completed, the first battery 3 is disconnected, and the second battery 4 is charged with a high voltage suitable for the second battery 4.

[0063] In this way, in this embodiment, the time until idling stop is permitted is shortened from time t5 due to individual charging to time t2.

[0064] Furthermore, in this embodiment, the time until non-power generation control is permitted is also shortened from time t6 in the case of individual charging to time t4.

[0065] Thus, in this embodiment, the control device 5 charges the first battery 3 at a low voltage suitable for the first battery 3 until the charge amount of the first battery 3 reaches or exceeds a first predetermined value, and when the charge amount of the first battery 3 reaches or exceeds the first predetermined value, the control device 5 disconnects the first battery 3 and charges the second battery 4 at a high voltage suitable for the second battery 4.

[0066] As a result, when the charge amount of the first battery 3 reaches or exceeds the first predetermined value, the first battery 3 is disconnected and the second battery 4 is charged at a high voltage suitable for the second battery 4, thereby shortening the time it takes for the charge amount of each battery to reach or exceed the first predetermined value.

[0067] In addition, when the charge amount of the first battery 3 becomes equal to or greater than a first predetermined value and the second battery 4 is being charged at a high voltage suitable for the second battery 4, if the charge amount of the second battery 4 becomes equal to or greater than a second predetermined value, the control device 5 charges the first battery 3 and the second battery 4 at a low voltage suitable for the first battery 3.

[0068] As a result, when the charge amount of the second battery 4 reaches or exceeds the second predetermined value, the first battery 3 and the second battery 4 are charged at a low voltage suitable for the first battery 3, thereby shortening the time it takes for the charge amount of each battery to reach or exceed the second predetermined value.

[0069] In addition, when the charge amount of the second battery 4 becomes equal to or greater than a second predetermined value and the first battery 3 and the second battery 4 are being charged at a low voltage suitable for the first battery 3, if charging of the first battery 3 is completed, the control device 5 disconnects the first battery 3 and charges the second battery 4 at a high voltage suitable for the second battery 4.

[0070] As a result, when charging of the first battery 3 is completed, the first battery 3 is disconnected and the second battery 4 is charged at a high voltage suitable for the second battery 4, thereby shortening the time required to fully charge each battery.

[0071] The first predetermined value is the charge amount of the battery at which idling stop of the vehicle 1 is permitted.

[0072] This reduces the time until idling stop is permitted, allowing idling stop to be performed more frequently and improving fuel economy.

[0073] The second predetermined value is the charge amount of the battery at which non-power generation control is permitted. This reduces the time until non-power generation control is permitted, making it possible to increase the frequency of non-power generation control and improve fuel efficiency.

[0074] In this embodiment, an example has been described in which the control device 5 performs various judgments and calculations based on various sensor information, but this is not limited to this. The vehicle 1 may be provided with a communication unit capable of communicating with an external device such as an external server, and various judgments and calculations may be performed by the external device based on the detection information of the various sensors transmitted from the communication unit. The judgment results and calculation results may be received by the communication unit, and various controls may be performed using the received judgment results and calculation results.

[0075] While an embodiment of the present invention has been disclosed, it will be apparent to one skilled in the art that modifications may be made thereto without departing from the scope of the present invention, and it is intended that all such modifications and equivalents be included in the following claims. [Explanation of symbols]

[0076] 1 vehicle 2. Generator 3. First Battery 4 Second Battery 5. Control device 31 First Switch 32 First current sensor 41 Second Switch 42 Second current sensor

Claims

1. A charging system for a vehicle battery, comprising: a first battery; a second battery having an upper limit voltage higher than that of the first battery; and a generator that supplies electric power to the first battery and the second battery, A battery charging system including a control device that charges the first battery at a low voltage suitable for the first battery until the charge amount of the first battery reaches or exceeds a first predetermined value, and that disconnects the first battery and charges the second battery at a high voltage suitable for the second battery when the charge amount of the first battery reaches or exceeds the first predetermined value.

2. 2. The battery charging system of claim 1, wherein when the charge amount of the first battery becomes equal to or greater than a first predetermined value and the second battery is being charged at a high voltage suitable for the second battery, if the charge amount of the second battery becomes equal to or greater than a second predetermined value, the control device charges the first battery and the second battery at a low voltage suitable for the first battery.

3. 3. The battery charging system of claim 2, wherein when the charge amount of the second battery becomes equal to or greater than a second predetermined value and the first battery and the second battery are being charged at a low voltage suitable for the first battery, the control device disconnects the first battery and charges the second battery at a high voltage suitable for the second battery when charging of the first battery is completed.

4. 4. The battery charging system according to claim 1, wherein the first predetermined value is a charge amount of the battery at which idling stop of the vehicle is permitted.

5. 4. The battery charging system according to claim 2, wherein the second predetermined value is a battery charge amount at which no-power-generation control is permitted, in which power generation by the generator is stopped and the power required for the vehicle is supplied from two or one batteries.

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