Vehicle power supply system

Abstract

To provide a vehicle power supply system capable of preventing a voltage of a battery for an auxiliary machine from significantly dropping below an operating voltage of the auxiliary machine.SOLUTION: When a battery 13 for an auxiliary machine is being charged and the difference between a voltage value of the battery 13 for an auxiliary machine and a target voltage value of a DCDC converter 17 is equal to or larger than a determination voltage value, a vehicle power supply system 10 determines that the DCDC converter 17 is abnormal, stops the DCDC converter 17, and drives an alternator 15, and when the voltage value of the battery 13 for an auxiliary machine is equal to or less than a predetermined voltage value or when an internal resistance value of the battery 13 for an auxiliary machine is equal to or less than a predetermined resistance value, the vehicle power supply system lowers the determination voltage value.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Some vehicle power supply systems include an alternator that generates electricity by the rotation of an engine and supplies power to auxiliary devices, and a DCDC converter that is connected in parallel with the alternator and converts voltage to supply power from a driving battery to auxiliary devices. The auxiliary devices include an auxiliary load and an auxiliary battery.

[0003] In the above vehicle power supply system, usually, the DCDC converter is driven to supply power from the driving battery to auxiliary devices. When the power consumption of the auxiliary load is greater than or equal to a predetermined power, the engine and the alternator are driven to supplement power to the auxiliary devices.

[0004] For example, Patent Document 1 discloses a technique in which, in the above vehicle power supply system, when an abnormality occurs in the DCDC converter, the DCDC converter is stopped, the alternator is driven, and power is supplied to auxiliary devices.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, as mentioned above, when the DCDC converter is stopped and the alternator is driven, if, for example, the auxiliary battery is degraded or has low remaining capacity, and a large current is generated in a short period of time in an auxiliary load with a heavy load, such as a brake motor or power steering motor, the voltage of the auxiliary battery may drop significantly and fall below the operating voltage of the auxiliary load, which is known as a dead battery.

[0007] Therefore, the present invention aims to provide a vehicle power supply system that can prevent the voltage of the auxiliary battery from dropping significantly and falling below the operating voltage of the auxiliary load when the auxiliary battery is degraded or has low remaining capacity and a short-term large current is generated in the auxiliary load when the DCDC converter is stopped and the alternator is driven. [Means for solving the problem]

[0008] The vehicle power supply system according to the present invention comprises an auxiliary unit, an auxiliary battery that supplies power to the auxiliary unit, an alternator that generates power by the rotation of the engine and supplies power to the auxiliary unit and the auxiliary battery, and a DC-DC converter connected in parallel with the alternator that converts the voltage of the drive battery to supply power to the auxiliary unit and the auxiliary battery. When the auxiliary battery is charging and the difference between the voltage value of the auxiliary battery and the target voltage value of the DC-DC converter is greater than or equal to a determination voltage value, the DC-DC converter is determined to be abnormal and the DC-DC converter is stopped and the alternator is driven. higher In some cases, the determination voltage value is lowered.

[0009] In the vehicle power supply system according to the present invention, if the auxiliary battery is not being charged and the discharge current value of the auxiliary battery is greater than or equal to a determination current value, the DCDC converter is determined to be abnormal and the DCDC converter is stopped, the alternator is driven, and the voltage value of the auxiliary battery is less than or equal to a predetermined voltage value, or the internal resistance value of the auxiliary battery is less than or equal to a predetermined resistance value higher In some cases, it is preferable to lower the judgment current value. [Effects of the Invention]

[0010] According to the vehicle power supply system of the present invention, when the DCDC converter is stopped and the alternator is driven, if the auxiliary battery is deteriorated or has low remaining capacity, and a short-term large current is generated in the auxiliary equipment, it is possible to avoid the auxiliary battery voltage dropping significantly and falling below the operating voltage of the auxiliary equipment. [Brief explanation of the drawing]

[0011] [Figure 1] This block diagram shows an example of a vehicle power supply system. [Figure 2] This is a block diagram showing the configuration of the power supply ECU. [Figure 3] This flowchart illustrates the flow of DCD anomaly detection and control. [Modes for carrying out the invention]

[0012] An example of an embodiment of the present invention will be described in detail below. In the following description, specific shapes, materials, directions, numerical values, etc., are examples to facilitate understanding of the present invention and can be appropriately modified according to the application, purpose, specifications, etc.

[0013] [Vehicle power supply system] The vehicle power supply system 10 will be explained using Figure 1.

[0014] The vehicle power supply system 10 is installed in the vehicle. The vehicle is a Hybrid Electric Vehicle (HEV) that runs on a gasoline engine and an electric motor.

[0015] The vehicle power supply system 10 includes an alternator 15 that generates electricity from the rotation of the engine 14 and supplies power to the auxiliary equipment 11, a DC-DC converter 17 connected in parallel with the alternator 15 that converts the voltage of the drive battery 16 to supply power to the auxiliary equipment 11, and a power supply ECU (Electronic Control Unit) 20 that performs abnormality detection control, which will be described in detail later. The auxiliary equipment 11 includes an auxiliary equipment load 12 and an auxiliary equipment battery 13.

[0016] The vehicle power supply system 10 normally drives the DC-DC converter 17 to supply power from the drive battery 16 to the auxiliary equipment 11, and if the power consumption of the auxiliary equipment load 12 exceeds a predetermined power, it drives the engine 14 and alternator 15 to supplement power to the auxiliary equipment 11.

[0017] According to the vehicle power supply system 10, although details will be described later, when the DCDC converter 17 malfunctions and the DCDC converter 17 is stopped to drive the alternator 15, if the auxiliary battery 13 is deteriorated or has low remaining capacity, and a short-term large current is generated in the auxiliary load 12, it is possible to avoid the voltage of the auxiliary battery 13 dropping significantly and falling below the operating voltage of the auxiliary 11.

[0018] The auxiliary load 12 consists of power-consuming equipment in the vehicle, such as electrical components, control devices that control electrical components, control devices related to driving, and control devices that control autonomous driving, such as brake motors and power steering motors.

[0019] The auxiliary battery 13 supplies power to the auxiliary load 12 and is a battery with a lower voltage and smaller capacity compared to the driving battery 16 described later. For the auxiliary battery 13, a lead battery, a lithium-ion battery, etc. are preferably used. A battery sensor 18 is provided for the auxiliary battery 13. The battery sensor 18 detects the voltage of the auxiliary battery 13, the current on the charging side, or the current on the discharging side.

[0020] The alternator 15 is a generator that generates electricity by the rotation of the engine 14 and supplies power to the auxiliary machine 11. The alternator 15 may be connected to the crankshaft of the engine 14 by a belt. The alternator 15 is connected in parallel with the DCDC converter 17 to the auxiliary machine 11.

[0021] The driving battery 16 supplies power to the motor that drives the vehicle. For the driving battery 16, a lithium-ion battery, etc. are preferably used.

[0022] The DCDC converter 17 steps down the voltage of the DC high-voltage power of the driving battery 16 to the voltage of the DC low-voltage power and supplies it to the auxiliary machine 11. The DCDC converter 17 is connected in parallel with the alternator 15 to the auxiliary machine 11.

[0023] [Power supply ECU] The power supply ECU 20 will be described using FIG. 2.

[0024] Normally, the power supply ECU 20 drives the DCDC converter 17 to supply the power of the driving battery 16 to the auxiliary machine 11. When the power consumption of the auxiliary load 12 is equal to or greater than a predetermined power, the engine 14 and the alternator 15 are driven to supplement the power to the auxiliary machine 11. Further, although details will be described later, the power supply ECU 20 executes DCDC abnormality determination control that stops the DCDC converter 17 and drives the alternator 15 when an abnormality occurs in the DCDC converter 17.

[0025] The power supply ECU20 has a CPU (Central Processing Unit) which is the arithmetic processing unit, and memory units such as RAM (Random Access Memory) and ROM (Read Only Memory). It performs signal processing according to a program pre-stored in ROM while utilizing the temporary storage function of RAM.

[0026] The power supply ECU 20 is connected to the engine 14 and the DCDC converter 17. The power supply ECU 20 stops or starts 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 obtains the voltage, charging current, or discharging current of the auxiliary battery 13 detected by the battery sensor 18.

[0027] The power supply ECU 20 includes, as will be described in detail later, an auxiliary battery voltage drop detection unit 21, an auxiliary battery degradation detection unit 22, an abnormality detection value modification unit 23, a first abnormality detection unit 24, a second abnormality detection unit 25, a DCDC converter stop unit 26, and an alternator drive unit 27. The auxiliary battery voltage drop detection unit 21, the auxiliary battery degradation detection unit 22, the abnormality detection value modification unit 23, the first abnormality detection unit 24, the second abnormality detection unit 25, the DCDC converter stop unit 26, and the alternator drive unit 27 are implemented by the CPU executing a program stored in ROM or RAM.

[0028] The auxiliary battery voltage drop determination unit 21 determines whether the remaining capacity of the auxiliary battery 13 is low. More specifically, the auxiliary battery voltage drop determination unit 21 determines whether the voltage of the auxiliary battery 13 detected by the battery sensor 18 is above a predetermined voltage. The predetermined voltage value is a voltage value that indicates the remaining capacity of the auxiliary battery 13 is low and is stored in the memory unit in advance.

[0029] The auxiliary battery degradation determination unit 22 determines whether the auxiliary battery 13 is degraded. More specifically, the auxiliary battery degradation determination unit 22 detects the internal resistance value of the auxiliary battery 13, and if the internal resistance value is a predetermined resistance value... If it is higherThe system determines that the auxiliary battery 13 is degraded. The predetermined internal resistance value is the resistance value at which the auxiliary battery 13 is determined to be degraded, and is stored in the memory unit beforehand.

[0030] If the auxiliary battery voltage drop determination unit 21 determines that the auxiliary battery 13 has low remaining capacity, or if the auxiliary battery deterioration determination unit 22 determines that the auxiliary battery 13 is deteriorated, the abnormality determination value changing unit 23 sets the determination voltage value lower in the first abnormality determination unit 24 (described later), and sets the determination current value lower in the second abnormality determination unit 25 (described later).

[0031] In this case, when the DCDC converter 17 malfunctions and the DCDC converter 17 is stopped to drive the alternator 15, if the auxiliary battery 13 is deteriorated or has low remaining capacity, and a large current is generated in the auxiliary system load 12, such as a brake motor or power steering motor, for a short period of time, the voltage of the auxiliary battery 13 may drop significantly and fall below the operating voltage of the auxiliary 11, resulting in a so-called battery failure.

[0032] Therefore, the abnormality detection value changing unit 23, when the remaining capacity of the auxiliary battery 13 is low or the auxiliary battery 13 is degraded, tightens the abnormality detection value in the subsequent abnormality detection of the DCDC converter 17, stopping the DCDC converter 17 earlier and driving the alternator 15. This prevents a significant drop in the voltage of the auxiliary battery 13 when a short-term large current is generated in the auxiliary load 12.

[0033] The first abnormality determination unit 24 determines whether the DC-DC converter 17 is abnormal when the auxiliary battery 13 is being charged. More specifically, the first abnormality determination unit 24 determines that the DC-DC converter 17 is abnormal when the auxiliary battery 13 is being charged and the difference between the voltage value of the auxiliary battery 13 and the target voltage value of the power supplied to the auxiliary 11 is greater than or equal to the determination voltage value. The reason for this is that when the DC-DC converter 17 is functioning normally and the auxiliary battery 13 is being charged, the voltage value of the auxiliary battery 13 and the target voltage value of the power supplied to the auxiliary 11 are the same. Here, the target voltage value is the voltage value output by the DC-DC converter 17, which is set based on the requirements of the auxiliary load 12.

[0034] The second abnormality determination unit 25 determines whether the DC-DC converter 17 is abnormal when the auxiliary battery 13 is not being charged. More specifically, the second abnormality determination unit 25 determines that the DC-DC converter 17 is abnormal when the auxiliary battery 13 is not being charged and the discharge current value of the auxiliary battery 13 is greater than or equal to the determination current value. The reason for this is that when the DC-DC converter 17 is functioning normally and the auxiliary battery 13 is not being charged, the power from the drive battery 16 is converted by the DC-DC converter 17 and supplied to the auxiliary 11, so there is no discharge from the auxiliary battery 13 to the auxiliary system load 12.

[0035] The DC-DC converter stop unit 26 stops the DC-DC converter 17 if the first abnormality determination unit 24 or the second abnormality determination unit 25 determines that the DC-DC converter 17 is abnormal.

[0036] If the DCDC converter 17 is stopped in the DCDC converter stop unit 26, the alternator drive unit 27 drives the engine 14 to drive the alternator 15.

[0037] The DC-DC converter stop unit 26 and the alternator drive unit 27 allow the vehicle to continue driving without relying on the remaining power of the auxiliary battery 13, thereby improving reliability during driving. Furthermore, since the auxiliary battery 13 deteriorates faster the greater the power consumption, replacing it with the alternator 15 suppresses the power consumption of the auxiliary battery 13 and thus suppresses its deterioration.

[0038] [Anomaly detection control] Figure 3 illustrates the flow of DCDC anomaly detection and control.

[0039] The DCDC abnormality detection control determines an abnormality in the DCDC converter 17 based on the functions of the power supply ECU 20 described above, following the procedure below. In step S11, the voltage value of the auxiliary battery 13 detected by the battery sensor 18, and the charging current value or the discharging current value are obtained.

[0040] In step S12, the auxiliary battery voltage drop determination unit 21 determines whether the voltage of the auxiliary battery 13 is below a predetermined voltage. If the voltage of the auxiliary battery 13 is below the predetermined voltage, the process proceeds to step S14. If the voltage of the auxiliary battery 13 is greater than the predetermined voltage, the process proceeds to step S13.

[0041] In step S13, the auxiliary battery degradation determination unit 22 determines that the internal resistance value of the auxiliary battery 13 is equal to a predetermined resistance value. higher If this is the case, proceed to step S14. The internal resistance value of the auxiliary battery 13 is a predetermined resistance value. below In that case, proceed to step S21.

[0042] In step S14, the abnormality determination value changing unit 23 lowers the determination voltage value of the first abnormality determination unit 24 in step S22 (described later) and lowers the determination current value of the second abnormality determination unit 25 in step S23 (described later).

[0043] In step S21, it is determined whether the auxiliary battery 13 is being charged. If the auxiliary battery 13 is being charged, the process proceeds to step S22. If the auxiliary battery 13 is not being charged, the process proceeds to step S23.

[0044] In step S22, the first abnormality determination unit 24 determines whether the difference between the voltage value of the auxiliary battery 13 and the target voltage value of the DCDC converter 17 is greater than or equal to the determination voltage value. If the difference between the voltage value of the auxiliary battery 13 and the target voltage value of the DCDC converter 17 is greater than or equal to the determination voltage value, the process proceeds to step S24.

[0045] In step S23, the second abnormality determination unit 25 determines whether the discharge current value of the auxiliary battery 13 is equal to or greater than the determination current value. If the discharge current value of the auxiliary battery 13 is equal to or greater than the determination current value, the process proceeds to step S24.

[0046] In step S24, the DCDC converter stop unit 26 determines that the DCDC converter 17 is abnormal and stops the DCDC converter 17. In step S25, the engine 14 is driven to drive the alternator 15.

[0047] It should be noted that the present invention is not limited to the embodiments and their modifications described above, and various changes and improvements are possible within the scope of the claims of this application. [Explanation of Symbols]

[0048] 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 Auxiliary battery voltage drop detection unit, 22 Auxiliary battery degradation detection unit, 23 Abnormality detection value change unit, 24 First abnormality detection unit, 25 Second abnormality detection unit, 26 DCDC converter stop unit, 27 Alternator drive unit

Claims

1. Auxiliary equipment, An auxiliary battery that supplies power to the aforementioned auxiliary equipment, An alternator that generates electricity by the rotation of the engine and supplies power to the auxiliary equipment and the auxiliary equipment battery, A DC-DC converter connected in parallel with the alternator, which converts voltage to supply power from the drive battery to the auxiliary equipment and the auxiliary equipment battery, Equipped with, If the auxiliary battery is charging and the difference between the voltage of the auxiliary battery and the target voltage of the DC-DC converter is greater than or equal to the determination voltage value, the DC-DC converter is determined to be abnormal, the DC-DC converter is stopped, and the alternator is driven. If the voltage value of the auxiliary battery is below a predetermined voltage value, or if the internal resistance value of the auxiliary battery is higher than a predetermined resistance value, the determination voltage value is lowered. Vehicle power supply system.

2. A vehicle power supply system according to claim 1, If the auxiliary battery is not being charged and the discharge current of the auxiliary battery is greater than or equal to the determination current value, the DC-DC converter is determined to be abnormal, the DC-DC converter is stopped, and the alternator is driven. If the voltage value of the auxiliary battery is less than or equal to the predetermined voltage value, or if the internal resistance value of the auxiliary battery is higher than the predetermined resistance value, the determination current value is lowered. Vehicle power supply system.

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