Vehicular power supply system

Abstract

To provide a vehicular power supply system which includes a battery sensor and can determine abnormality of the battery sensor without requiring changing of hardware.SOLUTION: A vehicular power supply system 10 is provided, converting voltage by a DCDC converter 17 and supplying power to a battery 13 for an auxiliary machine. When a battery sensor 18 detects charging side current of the battery 13 for the auxiliary machine by the time when the DCDC converter 17 starts up after startup of the system, the system determines that a current value of the battery sensor 18 is an abnormal value.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a vehicle power supply system. [Background technology]

[0002] A vehicle power supply system that supplies electric power to the vehicle's auxiliary equipment is known. The vehicle power supply system includes an alternator that generates electric power by rotating an engine and supplies the electric power to the auxiliary equipment, and a DC-DC converter that is connected in parallel with the alternator and converts the voltage of the drive battery to supply the electric power to the auxiliary equipment. The auxiliary equipment includes an auxiliary load and an auxiliary battery.

[0003] Furthermore, there is known anomaly determination device that determines anomaly in a vehicle power supply system. For example, the anomaly determination device disclosed in Patent Document 1 determines anomaly in a power supply circuit of the vehicle power supply system based on the power generation state of a generator and the charge / discharge current of a battery sensor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2001-069681 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the above-mentioned abnormality determination device, when the battery sensor is abnormal, the current value detected by the battery sensor is also abnormal, and it is not possible to determine an abnormality in the power supply circuit of the vehicle power supply system. Therefore, it is desirable to determine an abnormality in the battery sensor in the vehicle power supply system. It is also desirable to determine an abnormality in the battery sensor without changing the hardware of the existing vehicle power supply device.

[0006] SUMMARY OF THE PRESENT DISCLOSURE In view of the above, an object of the present invention is to provide a vehicle power supply system that is capable of determining whether or not an abnormality has occurred in a battery sensor without modifying the hardware. [Means for solving the problem]

[0007] The vehicle power supply system of the present invention is a vehicle power supply system that converts voltage using a DCDC converter and supplies power to an auxiliary battery, and is characterized in that if a battery sensor detects a charging side current of the auxiliary battery between the time the system is started and the time the DCDC converter is started, it is determined that the current value of the battery sensor is an abnormal value. Effect of the Invention

[0008] According to the vehicle power supply system of the present invention, it is possible to determine whether or not there is an abnormality in the battery sensor without modifying the hardware. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing a vehicle power supply system according to an embodiment; [Diagram 2] FIG. 2 is a block diagram showing the configuration of an ECU. [Diagram 3] FIG. 4 is a flow chart showing a flow of abnormality determination control. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] An example of an embodiment of the present invention will be described in detail below. In the following description, specific shapes, materials, directions, values, etc. are merely examples for the purpose of easily understanding the present invention, and can be appropriately changed according to the application, purpose, specifications, etc.

[0011] [Vehicle power supply system] A vehicle power supply system 10 will be described with reference to FIG.

[0012] The vehicle power supply system 10 is mounted on a vehicle. The vehicle is a hybrid electric vehicle (HEV) that runs on a gasoline engine and a motor. The vehicle power supply system 10 can determine an abnormality in the battery sensor 18 without modifying the hardware, as will be described in detail later.

[0013] The vehicle power supply system 10 includes an alternator 15 that generates power by the rotation of an engine 14 and supplies the power to the auxiliary equipment 11, a DC-DC converter 17 that is connected in parallel with the alternator 15 and converts the voltage to supply the power of a drive battery 16 to the auxiliary equipment 11, and a power supply ECU (Electronic Control Unit) 20 that executes battery sensor abnormality determination control, the details of which will be described later. The auxiliary equipment 11 includes an auxiliary equipment load 12 and an auxiliary equipment battery 13.

[0014] The vehicle power supply system 10 normally drives the DCDC converter 17 to supply power from the drive battery 16 to the auxiliary equipment 11, and when the power consumption of the auxiliary load 12 is equal to or greater than a predetermined power, drives the engine 14 and the alternator 15 to supply power to the auxiliary equipment 11.

[0015] The auxiliary load 12 is a device that consumes power, such as an electrical component in the vehicle, a control device that controls the electrical component, a control device related to driving, a control device that controls automatic driving, etc., such as a brake motor, a power steering motor, etc.

[0016] The auxiliary battery 13 supplies power to the auxiliary load 12, and is a battery with a low voltage and a small capacity compared to a drive battery 16 described later. A lead battery, a lithium ion battery, or the like is preferably used as the auxiliary battery 13. A battery sensor 18 is provided in the auxiliary battery 13. The battery sensor 18 detects the voltage, charge current, or discharge current of the auxiliary battery 13.

[0017] The alternator 15 is a generator that generates electricity by the rotation of the engine 14, and supplies electric power to the auxiliary device 11. The alternator 15 may be connected to a crankshaft of the engine 14 by a belt. The alternator 15 is connected in parallel with the DC-DC converter 17 with respect to the auxiliary device 11.

[0018] The drive battery 16 supplies power to a motor that drives the vehicle. As the drive battery 16, a lithium ion battery or the like is preferably used.

[0019] The DCDC converter 17 steps down the voltage of the high-voltage DC power of the drive battery 16 to a low-voltage DC power voltage and supplies it to the auxiliary device 11. The DCDC converter 17 is connected to the auxiliary device 11 in parallel with the alternator 15.

[0020] [Power ECU] The power supply ECU 20 will be described with reference to FIG.

[0021] The power supply ECU 20 determines whether or not there is an abnormality in the battery sensor 18 based on the current value of the auxiliary battery 13 during the period from when the vehicle power supply system 10 starts up (ignition on) until the DCDC converter 17 starts up (ready on). In other words, the power supply ECU 20 can determine whether or not there is an abnormality in the battery sensor 18 without changing the hardware of the vehicle power supply system 10.

[0022] The power supply ECU 20 has a CPU (Central Processing Unit) which is an arithmetic processing unit, and storage units such as a RAM (Random Access Memory) and a ROM (Read Only Memory), and performs signal processing according to a program pre-stored in the ROM while utilizing the temporary storage function of the RAM.

[0023] The power supply ECU 20 is connected to the engine 14 and the DCDC converter 17. The power supply ECU 20 stops or drives the engine 14 or the DCDC converter 17. A battery sensor 18 is connected to the power supply ECU 20. The power supply ECU 20 acquires the voltage, charge-side current, or discharge-side current of the auxiliary battery 13 detected by the battery sensor 18. The power supply ECU 20 acquires the charge-side current of the auxiliary battery 13 as a positive value, and the discharge-side current as a negative value.

[0024] The power supply ECU 20 includes a battery voltage acquisition unit 21, a DCDC converter start confirmation unit 22, a battery current acquisition unit 23, and a battery sensor abnormality determination unit 24, each of which will be described in detail later. The battery voltage acquisition unit 21, the DCDC converter start confirmation unit 22, the battery current acquisition unit 23, and the battery sensor abnormality determination unit 24 are realized by the CPU executing a program stored in the ROM or RAM.

[0025] The battery voltage acquisition unit 21 acquires the voltage value of the auxiliary battery 13 detected by the battery sensor 18 .

[0026] The DCDC converter start confirmation unit 22 confirms whether the DCDC converter 17 is started based on the voltage value of the auxiliary battery 13 acquired by the battery voltage acquisition unit 21.

[0027] More specifically, the DCDC converter start confirmation unit 22 determines that the DCDC converter 17 is started when the voltage value of the auxiliary battery 13 is greater than a predetermined value (for example, 13V). Also, the DCDC converter start confirmation unit 22 determines that the DCDC converter 17 is not started when the voltage value of the auxiliary battery 13 is equal to or less than the predetermined value. Note that the predetermined value is preferably a voltage value slightly lower than the voltage of the auxiliary battery 13 when fully charged.

[0028] The reason for this is that when the DCDC converter 17 is activated, power is supplied to the auxiliary battery 13 by the DCDC converter 17, so that the auxiliary battery 13 is in a charging state and has a voltage higher than that when fully charged. On the other hand, when the DCDC converter 17 is not activated, power is supplied from the auxiliary battery 13 to the auxiliary load 12, so that the auxiliary battery 13 is in a discharging state and has a voltage lower than that when fully charged.

[0029] The battery current acquisition unit 23 acquires the current value of the auxiliary battery 13 detected by the battery sensor 18 .

[0030] When the DCDC converter 17 confirmed by the DCDC converter start confirmation unit 22 has not yet started, the battery sensor abnormality determination unit 24 determines an abnormality in the battery sensor 18 based on the current value of the auxiliary battery 13 acquired by the battery current acquisition unit 23.

[0031] More specifically, when the DCDC converter 17 has not yet started, if the current value of the auxiliary battery 13 is a positive value (charging side), the current value of the battery sensor 18 is abnormal, and it is determined that the battery sensor 18 is abnormal. The reason for this is that when the DCDC converter 17 has not yet started, the auxiliary battery 13 supplies power to the auxiliary load 12, so it is normal for the current value of the auxiliary battery 13 to be a negative value (discharging side).

[0032] [Abnormality Judgment Control] The flow of the battery sensor abnormality determination control will be described with reference to FIG.

[0033] The battery sensor abnormality determination control determines whether or not there is an abnormality in the battery sensor 18 based on each function of the power supply ECU 20 described above according to the following procedure.

[0034] In step S11, the battery voltage acquisition unit 21 acquires the voltage value of the auxiliary battery 13 detected by the battery sensor 18. In addition, the battery current acquisition unit 23 acquires the current value of the auxiliary battery 13 detected by the battery sensor 18.

[0035] In step S12, the DCDC converter start confirmation unit 22 checks whether the voltage value of the auxiliary battery 13 is equal to or lower than a predetermined value. If the voltage value of the auxiliary battery 13 is equal to or lower than the predetermined value, it is determined that the DCDC converter 17 has not yet started, and the process proceeds to step S13. If the voltage value of the auxiliary battery 13 is greater than the predetermined value, it is determined that the DCDC converter 17 has started, and the battery sensor abnormality determination control is terminated.

[0036] In step S13, the battery sensor abnormality determination unit 24 determines whether the current value of the auxiliary battery 13 is a positive value (charging side). If the current value of the auxiliary battery 13 is a positive value (charging side), the process proceeds to step S14. If the current value of the auxiliary battery 13 is a negative value (discharging side), the process proceeds to step S11.

[0037] In step S14, the battery sensor abnormality determination unit 24 determines that the current value of the battery sensor 18 is abnormal because it is a positive value (charging side), whereas it is normal for the auxiliary battery 13 to supply power to the auxiliary load 12 and the current value of the auxiliary battery 13 is a negative value (discharging side).

[0038] It should be noted that the present invention is not limited to the above-described embodiment and its modified examples, and various modifications and improvements are possible within the scope of the matters described in the claims of this application. [Explanation of symbols]

[0039] 10 Vehicle power supply system, 11 Auxiliary equipment, 12 Auxiliary equipment load, 13 Auxiliary equipment battery, 14 Engine, 15 Alternator, 16 Drive battery, 17 DCDC converter, 18 Battery sensor, 20 Power supply ECU, 21 Battery voltage acquisition unit, 22 DCDC converter start confirmation unit, 23 Battery current acquisition unit, 24 Battery sensor abnormality determination unit

Claims

[Claim 1] A vehicle power supply system that converts voltage using a DC-DC converter and supplies power to an auxiliary battery, When a battery sensor detects a charging side current of the auxiliary battery during a period from after the system is started up until the DCDC converter is started up, it is determined that the current value of the battery sensor is an abnormal value. Vehicle power supply system.

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