Control method of electric power in vehicle

Abstract

To provide a control method of electric power in a vehicle which can suppress deterioration of utilization efficiency of the electric power of the whole vehicle at the time of charging a main power storage part of the vehicle.SOLUTION: A control method of electric power in a vehicle is given in which CPU of ECU 22 raises, before charging a main battery 16 mounted on a vehicle 10 from an external power source 30, charging rate of an auxiliary battery 20 electrically connected through a circuit with a DC / DC converter 28 that can convert a first DC voltage outputted from the main battery 16 into a second DC voltage whose voltage is different from the first DC voltage, and the auxiliary battery 20 supplies, when the main battery 16 is charged from the external power source 30, an auxiliary machine 18 mounted on the vehicle 10 with electric power.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for controlling power in a vehicle. [Background technology]

[0002] Patent Document 1 below discloses an invention related to an on-board charger. In this on-board charger, when the main battery (main power storage unit) is electrically disconnected from an external power source and the voltage of the auxiliary battery is equal to or greater than a threshold value, the controller puts the DC / DC converter in an inactive state, preventing the auxiliary battery from being charged. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-35067 Summary of the Invention [Problem to be solved by the invention]

[0004] When charging the main battery with an external power source, if the auxiliary battery runs out of power, it is necessary to supply power to the auxiliary devices mounted on the vehicle via a DC / DC converter. However, because the voltage of the main battery is higher than that of the auxiliary battery, supplying power from the main battery to the auxiliary devices via a DC / DC converter reduces the conversion efficiency of the DC / DC converter, which is undesirable from the perspective of the overall power utilization efficiency of the vehicle.

[0005] In consideration of the above circumstances, an object of the present invention is to provide a method for controlling power in a vehicle that can suppress deterioration in the efficiency of power use in the entire vehicle when a main power storage unit of the vehicle is being charged. [Means for solving the problem]

[0006] A first aspect of the method for controlling power in a vehicle includes, before charging a main power storage unit mounted on the vehicle with an external power source, increasing the charging rate of an auxiliary power storage unit electrically connected via a circuit to a DC voltage converter capable of converting a first DC voltage output from the main power storage unit into a second DC voltage different from the first DC voltage, and when charging the main power storage unit with the external power source, supplying power to the auxiliary equipment mounted on the vehicle from the auxiliary power storage unit.

[0007] According to the first aspect of the method for controlling power in a vehicle, before charging a main power storage unit mounted on the vehicle with an external power source, the charging rate of an auxiliary power storage unit electrically connected via a circuit to a DC voltage converter capable of converting a first DC voltage output from the main power storage unit into a second DC voltage different from the first DC voltage is increased.

[0008] Therefore, power is stored in the auxiliary power storage unit before the main power storage unit mounted on the vehicle is charged by an external power supply.

[0009] Incidentally, when the main power storage unit is charged by an external power supply, if the auxiliary equipment power storage unit has insufficient power, it is necessary to supply power from the main power storage unit to the auxiliary equipment mounted on the vehicle via the DC voltage converter. However, if the voltage of the main power storage unit is higher than the voltage of the auxiliary equipment power storage unit, the conversion efficiency of the DC voltage converter deteriorates when power is supplied from the main power storage unit to the auxiliary equipment via the DC voltage converter, which is not preferable from the viewpoint of efficiency of power use of the entire vehicle.

[0010] In this aspect, the auxiliary power storage unit is in a charged state before the main power storage unit is charged by the external power source, and when the main power storage unit is being charged by the external power source, the auxiliary power storage unit can supply power to the auxiliary units mounted on the vehicle without relying on power from the main power storage unit. In other words, in this aspect, when the main power storage unit is being charged by the external power source, it is not necessary to supply power from the main power storage unit to the auxiliary units via the DC voltage converter.

[0011] A second aspect of the power control method in a vehicle is the method of the first aspect, wherein when the charging rate is equal to or higher than a first threshold when the main storage unit is being charged, a first state is set in which the first output voltage of the auxiliary storage unit is higher than the second output voltage of the DC voltage conversion unit until the charging rate reaches a second threshold that is lower than the first threshold, and when the charging rate is equal to or lower than the second threshold when the main storage unit is being charged, a second state is set in which the second output voltage is higher than the first output voltage.

[0012] According to the method for controlling power in a vehicle according to the second aspect, when the charging rate of the auxiliary power storage unit is equal to or higher than a first threshold value during charging of the main power storage unit, a first state is established in which the first output voltage of the auxiliary power storage unit is higher than the second output voltage of the DC voltage converter until the charging rate of the auxiliary power storage unit reaches a second threshold value that is lower than the first threshold value. Therefore, in the first state, power is supplied from the auxiliary power storage unit to the auxiliary units mounted on the vehicle.

[0013] On the other hand, when the main power storage unit is being charged, if the charging rate of the auxiliary power storage unit is equal to or lower than the second threshold value, a second state is entered in which the second output voltage of the DC voltage converter is higher than the first output voltage of the auxiliary power storage unit. Therefore, in the second state, power is supplied from the main power storage unit via the DC voltage converter to the auxiliary units mounted on the vehicle.

[0014] A third aspect of the method for controlling power in a vehicle is the method for controlling power in a vehicle according to the second aspect, wherein in the second state, the second output voltage is set to a value lower than the normal output voltage of the DC voltage conversion unit, and power is supplied from the DC voltage conversion unit to the auxiliary storage unit and the auxiliary.

[0015] According to the third aspect of the invention, in a vehicle power control method, in a second state in which the second output voltage of the DC voltage converter is higher than the first output voltage of the auxiliary equipment power storage unit, the second output voltage is set to a value lower than a normal output voltage of the DC voltage converter. At this time, power is supplied from the main power storage unit via the DC voltage converter to the auxiliary equipment mounted on the vehicle in a state in which the second output voltage of the DC voltage converter is lower than the normal output voltage.

[0016] Although it is possible to supply power to various auxiliary devices from the main power storage unit by lowering the output voltage of the DC voltage conversion unit, a decrease in the output voltage of the DC voltage conversion unit will result in a deterioration in the conversion efficiency of the DC voltage conversion unit.

[0017] Here, in this aspect, power is supplied from the DC voltage conversion unit not only to the auxiliary equipment but also to the auxiliary equipment storage unit, so the current output from the DC voltage conversion unit can be increased, and as a result, deterioration in the conversion efficiency of the DC voltage conversion unit can be suppressed.

[0018] A fourth aspect of the method for controlling power in a vehicle is the method for controlling power in a vehicle according to the first aspect, in which a start time for charging the main storage unit from the external power source is set by input from an operation unit mounted on the vehicle, and power is supplied from the DC voltage conversion unit to the auxiliary storage unit while the vehicle is traveling before the start time until the auxiliary storage unit is fully charged.

[0019] According to a fourth aspect of the electric power control method for a vehicle, a start time for charging the main power storage unit from an external power supply is set by input from an operation unit mounted on the vehicle, and while the vehicle is traveling before the start time, electric power is supplied from the DC voltage conversion unit to the auxiliary power storage unit until the auxiliary power storage unit is fully charged.

[0020] Therefore, in this aspect, when the main power storage unit is charged by an external power supply, it is possible to increase the reliability with which electric power is stored in the auxiliary power storage unit. [Effects of the Invention]

[0021] As described above, the method for controlling power in a vehicle according to the present invention has the excellent effect of being able to suppress deterioration in the efficiency of power use in the entire vehicle when the main power storage unit of the vehicle is being charged. [Brief explanation of the drawings]

[0022] [Figure 1]1 is a block diagram showing a hardware configuration of a power control system according to an embodiment of the present invention. [Figure 2] 2 is a block diagram showing the hardware configuration of a main ECU that constitutes part of the power control system according to the present embodiment. FIG. [Figure 3] 4 is a flowchart showing a control flow by a main ECU that constitutes a part of the power control system according to the present embodiment. [Figure 4] 3 is a diagram showing the relationship between the output voltage of the DC / DC converter and the charging rate of the auxiliary battery in the power control system according to the present embodiment. FIG. [Figure 5] 2 is a diagram schematically showing the relationship between a DC / DC converter and an auxiliary battery in the power control system according to the present embodiment. FIG. [Figure 6] 4 is a diagram showing the relationship between the conversion efficiency of a DC / DC converter and the output current of the DC / DC converter in the power control system according to the present embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0023] An example of a method for controlling power in a vehicle will be described below using Figures 1 to 6, taking as a specific example a power supply system 12 mounted on a "vehicle 10." As shown in Figure 1, the power supply system 12 includes a power supply unit 14, a "main battery 16" as a main power storage unit, "auxiliary equipment 18," an "auxiliary equipment battery 20" as a power storage unit for the auxiliary equipment, a main ECU (Electronic Control Unit) 22, and an "operation unit 24" including a touch panel.

[0024] The power supply unit 14 includes a charger 26 and a DC / DC converter 28 as a DC voltage conversion unit. The charger 26 converts AC voltage output from an external power source 30, such as a charging stand, into DC voltage, and supplies power from the external power source 30 to the main battery 16, thereby enabling charging of the main battery 16.

[0025] DC / DC converter 28 is a power supply device capable of converting a DC voltage into a voltage appropriate for the device, and is capable of converting a first DC voltage output from main battery 16 into a second DC voltage lower than the first DC voltage. Note that the second DC voltage output from DC / DC converter 28 is set to, for example, approximately 12 V to 15 V, which is sufficient to supply power to auxiliary equipment 18 and auxiliary battery 20.

[0026] The main battery 16 is a high-voltage battery capable of supplying power to a drive motor (not shown) via an inverter (not shown) mounted on the vehicle 10, and its rated voltage is set to, for example, approximately 200 [V] to 400 [V].

[0027] Examples of the auxiliary device 18 include a navigation system and lights mounted on the vehicle 10. The auxiliary device 18 is supplied with power from a DC / DC converter 28 and an auxiliary battery 20.

[0028] The auxiliary battery 20 may be, for example, a lead storage battery, and its output voltage is set to approximately 12 V to 15 V. The auxiliary battery 20 is capable of supplying power to the accessories 18 and being charged with power from the main battery 16 via a DC / DC converter 28 under the control of the main ECU 22, as will be described later.

[0029] As shown in FIG. 5, the auxiliary device 18, the auxiliary battery 20, and the DC / DC converter 28 are electrically connected via a common "circuit 32."

[0030] 2, the main ECU 22 includes a CPU (Central Processing Unit) 22A, which is an example of a processor, a ROM (Read Only Memory) 22B, a RAM (Random Access Memory) 22C, a communication I / F (Interface) 22E, and an input / output I / F 22F. The CPU 22A, the ROM 22B, the RAM 22C, the communication I / F 22E, and the input / output I / F 22F are connected to each other via a bus 22G so as to be able to communicate with each other.

[0031] The CPU 22A is a central processing unit and is capable of executing various programs related to various types of control. Specifically, the CPU 22A reads programs from the ROM 22B and executes the programs using the RAM 22C as a work area. The CPU 22A reads and executes the execution programs stored in the ROM 22B, thereby enabling the main ECU 22 to perform various functions, as will be described later. The ROM 22B is also capable of storing various data acquired by various sensors, as will be described later.

[0032] The communication I / F 22E is an interface used for communication between the main ECU 22 and a sub-ECU (not shown), and is capable of communicating with the sub-ECU via a CAN (Controller Area Network) or the like. Note that other communication standards that can be adopted for communication by the communication I / F 22E include, for example, Ethernet (registered trademark).

[0033] The input / output I / F 22F is an interface through which the main ECU 22 communicates with various devices mounted on the vehicle 10, such as the main battery 16, current sensors and voltage sensors provided in the main battery 16, the auxiliary battery 20, current sensors and voltage sensors provided in the auxiliary battery 20, the operation unit 24, the DC / DC converter 28, current sensors and voltage sensors provided in the DC / DC converter 28, and the charger 26. These devices may be directly connected to the bus 22G, or may be able to communicate with the main ECU 22 via another ECU to which they are connected. The main ECU 22 configured as described above has the following functions.

[0034] Specifically, the main ECU 22 acquires the start time of charging the main battery 16 using the external power supply 30, which is set based on an operation input to the operation unit 24, and supplies power to the auxiliary battery 20 while the vehicle 10 is running, so that the auxiliary battery 20 is fully charged by the start time. Power is supplied to the auxiliary battery 20 from the main battery 16 via a DC / DC converter 28.

[0035] The main ECU 22 is also capable of estimating the state of charge of the auxiliary battery 20 based on the detection results of various sensors provided for the auxiliary battery 20. As shown in Fig. 4, when the state of charge of the auxiliary battery 20 is equal to or higher than a first threshold value P1 [%] during charging of the main battery 16, the main ECU 22 controls the main battery 16 to enter a first state S1 in which the first output voltage V1 of the auxiliary battery 20 is greater than the second output voltage V2 of the DC / DC converter 28 until the state of charge reaches a second threshold value P2 [%]. In other words, in the first state S1, the main ECU 22 controls various devices so that power is supplied from the auxiliary battery 20 to the auxiliary device 18.

[0036] On the other hand, when charging the main battery 16, when the charging rate of the auxiliary battery 20 is equal to or lower than the second threshold P2, or when the charging rate of the auxiliary battery 20 is higher than the second threshold P2 and lower than the first threshold P1 and this charging rate is on an upward trend, the main ECU 22 controls the DC / DC converter 28 to enter a second state S2 in which the second output voltage V2 is greater than the first output voltage V1 of the auxiliary battery 20.

[0037] In addition, in the second state S2, the main ECU 22 sets the second output voltage V2 of the DC / DC converter 28 to a value lower than the normal output voltage of the DC / DC converter 28, and controls various devices so that power is supplied from the main battery 16 to the auxiliary equipment 18 and the auxiliary battery 20 via the DC / DC converter 28.

[0038] At this time, as shown in FIG. 6, main ECU 22 feedback controls the output voltage of DC / DC converter 28 so that DC / DC converter 28 operates in a region where the output current of DC / DC converter 28 is C [A] or more, where the conversion efficiency of DC / DC converter 28 is good.

[0039] (Actions and Effects of This Embodiment) Next, the operation and effects of this embodiment will be described.

[0040] The power control method for the vehicle according to this embodiment will be described below by taking as an example the control flow by the main ECU 22, mainly using the flowchart shown in Figure 3. This control flow is started when the CPU 22A of the main ECU 22 receives a predetermined instruction signal at predetermined time intervals.

[0041] When this control flow starts, in step S100, the CPU 22A acquires the start time of charging the main battery 16 using the external power supply 30 based on an operation input to the operation unit 24, and the process proceeds to step S101.

[0042] In step S101, the CPU 22A controls the DC / DC converter 28 to supply power to the auxiliary battery 20 while the vehicle 10 is running, etc., to charge the auxiliary battery 20 for a predetermined time, and then proceeds to step S102.

[0043] In step S102, the CPU 22A determines whether the auxiliary battery 20 is fully charged based on data acquired from various sensors. If the auxiliary battery 20 is fully charged (step S102: YES), the CPU 22A proceeds to step S103, and if the auxiliary battery 20 is not fully charged (step S102: NO), the CPU 22A returns to step S101.

[0044] In step S103, the CPU 22A determines whether the main battery 16 is in a chargeable state. Specifically, the CPU 22A determines whether the current time is the start time for charging the main battery 16 and whether the charger 26 is connected to the external power supply 30. If the main battery 16 is in a chargeable state (step S103: YES), the CPU 22A proceeds to step S104, and if the main battery 16 is not in a chargeable state (step S103: NO), the CPU 22A repeats step S103.

[0045] In step S104, the CPU 22A controls the auxiliary battery 20 and the DC / DC converter 28 so that the first output voltage V1 of the auxiliary battery 20 is greater than the second output voltage V2 of the DC / DC converter 28, and charges the main battery 16 for a predetermined time, and then proceeds to step S105.

[0046] In step S105, the CPU 22A determines whether the main battery 16 is fully charged based on data acquired from various sensors. If the main battery 16 is fully charged (step S105: YES), the CPU 22A ends this control flow. On the other hand, if the main battery 16 is not fully charged (step S105: NO), the CPU 22A proceeds to step S106.

[0047] In step S106, the CPU 22A estimates the state of charge of the auxiliary battery 20 based on data acquired from various sensors. If the CPU 22A determines that the state of charge of the auxiliary battery 20 has reached the second threshold value P2 (step S106: YES), the CPU 22A proceeds to step S107, and if the CPU 22A determines that the state of charge of the auxiliary battery 20 has not reached the second threshold value P2 (step S106: NO), the CPU 22A returns to step S105.

[0048] In step S107, the CPU 22A controls the auxiliary battery 20 and the DC / DC converter 28 so that the second output voltage V2 of the DC / DC converter 28 is greater than the first output voltage V1 of the auxiliary battery 20, and supplies power to the auxiliary device 18 and charges the auxiliary battery 20 for a predetermined time, and then proceeds to step S108.

[0049] In step S108, the CPU 22A estimates the state of charge of the auxiliary battery 20 based on data acquired from various sensors. If the CPU 22A determines that the state of charge of the auxiliary battery 20 is equal to or greater than the first threshold value P1 (step S108: YES), the process returns to step S104, and if the CPU 22A determines that the state of charge of the auxiliary battery 20 has not reached the first threshold value P1 (step S108: NO), the process returns to step S105.

[0050] In this manner, in this embodiment, before the main battery 16 mounted on the vehicle 10 is charged by the external power source 30, the charging rate of the auxiliary battery 20, which is electrically connected via the DC / DC converter 28 and circuit 32, which can convert the first DC voltage output from the main battery 16 into a second DC voltage different from the first DC voltage, is increased.

[0051] Therefore, power is stored in the auxiliary battery 20 before the main battery 16 mounted on the vehicle 10 is charged by the external power source 30.

[0052] Incidentally, when charging the main battery 16 from the external power source 30, if the power of the auxiliary battery 20 is insufficient, it is necessary to supply power from the main battery 16 to the auxiliary equipment 18 mounted on the vehicle 10 via the DC / DC converter 28. However, if the voltage of the main battery 16 is higher than the voltage of the auxiliary battery 20, when power is supplied from the main battery 16 to the auxiliary equipment 18 via the DC / DC converter 28, the conversion efficiency of the DC / DC converter 28 deteriorates, which is undesirable from the viewpoint of the efficiency of power utilization of the entire vehicle 10.

[0053] In this embodiment, the auxiliary battery 20 is in a charged state before the main battery 16 is charged by the external power source 30, and when the main battery 16 is being charged by the external power source 30, the auxiliary battery 20 can supply power to the accessories 18 mounted on the vehicle 10 without relying on power from the main battery 16. In other words, in this embodiment, when the main battery 16 is being charged by the external power source 30, there is no need to supply power from the main battery 16 to the accessories 18 via the DC / DC converter 28.

[0054] Furthermore, in this embodiment, when the charging rate of the auxiliary power storage unit is equal to or higher than the first threshold value during charging of the main battery 16, the system enters a first state S1 in which the first output voltage V1 of the auxiliary battery 20 is higher than the second output voltage V2 of the DC / DC converter 28 until the charging rate of the auxiliary battery 20 reaches a second threshold value P2 that is lower than the first threshold value P1. Therefore, in the first state S1, power is supplied from the auxiliary battery 20 to the auxiliary device 18 mounted on the vehicle 10.

[0055] On the other hand, when the charging rate of the auxiliary battery 20 is equal to or lower than the second threshold value P2 while the main battery 16 is being charged, a second state S2 is entered in which the second output voltage V2 of the DC / DC converter 28 is greater than the first output voltage of the auxiliary battery 20. Therefore, in the second state S2, power is supplied from the main battery 16 via the DC / DC converter 28 to the auxiliary device 18 mounted on the vehicle 10.

[0056] Furthermore, in this embodiment, in the second state S2, the second output voltage V2 of the DC / DC converter 28 is set to a value lower than the normal output voltage of the DC / DC converter 28. At this time, with the second output voltage V2 of the DC / DC converter 28 lower than the normal output voltage, power is supplied from the main battery 16 to the auxiliary equipment 18 mounted on the vehicle 10 via the DC / DC converter 28.

[0057] Although it is possible to supply power from the main battery 16 to various accessories 18 by lowering the output voltage of the DC / DC converter 28, a reduction in the output voltage of the DC / DC converter 28 will result in a deterioration in the conversion efficiency of the DC / DC converter 28.

[0058] In this embodiment, power is supplied from DC / DC converter 28 not only to auxiliary device 18 but also to auxiliary battery 20, so that the current output from DC / DC converter 28 can be increased as shown in FIG. 6, and as a result, deterioration in the conversion efficiency of DC / DC converter 28 can be suppressed.

[0059] Additionally, in this embodiment, the start time for charging the main battery 16 from the external power source 30 is set by input from the operation unit 24 mounted on the vehicle 10. Then, while the vehicle 10 is running before the start time, power is supplied from the DC / DC converter 28 to the auxiliary battery 20 until the auxiliary battery 20 is fully charged.

[0060] Therefore, in this embodiment, when the main battery 16 is being charged by the external power supply 30, the reliability that electric power is stored in the auxiliary battery 20 can be increased.

[0061] As described above, the method for controlling power in a vehicle according to this embodiment has the excellent effect of suppressing deterioration in the efficiency of power use of the entire vehicle 10 when charging the main battery 16 of the vehicle 10. [Explanation of symbols]

[0062] 10 vehicles 16 Main battery (main power storage unit) 18 Auxiliary Machinery 20 Auxiliary battery (auxiliary power storage unit) 24 Control section 28 DC / DC converter (DC voltage conversion section) 30 External power supply 32 circuits

Claims

1. before charging a main power storage unit mounted on a vehicle with an external power supply, increasing a charging rate of an auxiliary power storage unit electrically connected via a circuit to a DC voltage converter capable of converting a first DC voltage output from the main power storage unit into a second DC voltage different from the first DC voltage; When the main power storage unit is charged by the external power supply, the auxiliary power storage unit supplies electric power to an auxiliary unit mounted on the vehicle. A method for controlling power in a vehicle.

2. a first state in which, when the charging rate is equal to or higher than a first threshold value during charging of the main power storage unit, a first output voltage of the auxiliary power storage unit is higher than a second output voltage of the DC voltage conversion unit until the charging rate reaches a second threshold value that is lower than the first threshold value; a second state in which the second output voltage is higher than the first output voltage when the charging rate is equal to or lower than the second threshold value during charging of the main power storage unit; The method for controlling power in a vehicle according to claim 1 .

3. In the second state, the second output voltage is set to a value lower than the output voltage of the DC voltage converter in a normal state, and electric power is supplied from the DC voltage converter to the auxiliary equipment power storage unit and the auxiliary equipment. The method for controlling electric power in a vehicle according to claim 2.

4. setting a start time for charging the main power storage unit from the external power supply by inputting an operation unit mounted on the vehicle; supplying electric power from the DC voltage converter to the auxiliary power storage unit while the vehicle is traveling before the start time until the auxiliary power storage unit is fully charged; The method for controlling power in a vehicle according to claim 1 .

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