Vehicle control device

Abstract

To provide a control device for a vehicle capable of avoiding a power supply connection state against a driver's intention.SOLUTION: An ECU intermittently operates a DC-DC converter when a predetermined condition that terminals of a 12V battery as a low-voltage battery may be removed is satisfied (step S4). The predetermined conditions include that the automobile is stopped (YES in step S1), that the engine hood is open (YES in step S2), and that the current at the terminals of the 12V battery is less than a predetermined value in step S3 (YES in step PARK).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a vehicle control device. [Background technology]

[0002] Patent Document 1 discloses an electric vehicle that, in order to enable disconnection and confirmation operations to be performed more reliably, turns off the contactor on the high-voltage line when it is determined that the connection between the low-voltage battery and the vehicle has been disconnected, thereby stopping the power supply from the fuel cell and the high-voltage battery. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-259537 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the electric vehicle described in Patent Document 1, it can be difficult to accurately detect whether the low-voltage battery terminals have been disconnected. For example, when power is being supplied from the high-voltage line to the low-voltage line, the supply voltage may become equal to the voltage of the low-voltage battery, causing the current sensor to calculate a low value even though the low-voltage battery terminals are not disconnected. This can result in a false detection that turns off the contactor, preventing power from being supplied from the high-voltage battery to the low-voltage battery or auxiliary equipment, even when the low-voltage battery terminals are connected. On the other hand, if the high-voltage battery contactor is not turned off when the low-voltage battery terminals are disconnected, power is supplied from the high-voltage battery to the auxiliary equipment via the DC-DC converter. In this case, drivers accustomed to engine-powered vehicles may perceive the power connection state as unintended because they expect the vehicle system to be turned off when the low-voltage battery terminals are disconnected.

[0005] An object of the present invention is to provide a vehicle control device that can avoid a power supply connection state that is contrary to the driver's intention. [Means for solving the problem]

[0006] The vehicle control device of the present invention is a vehicle control device that includes a high-voltage battery that generates a predetermined high voltage, a low-voltage battery that generates a predetermined low voltage lower than the high-voltage battery, and a DCDC converter that converts the high voltage supplied from the high-voltage battery to a low voltage and supplies it to the low-voltage battery and auxiliary equipment, and is characterized in that it includes a control unit that controls the DCDC converter, and the control unit operates the DCDC converter intermittently when predetermined conditions are met that indicate that the terminal of the low-voltage battery may be removed. [Effects of the Invention]

[0007] The present invention can provide a vehicle control device that can avoid a power supply connection state that is contrary to the driver's intention. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a vehicle equipped with a vehicle control device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a flowchart showing the flow of operations performed by the control unit of the vehicle control device according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] A vehicle control device according to one embodiment of the present invention includes a high-voltage battery that generates a predetermined high voltage, a low-voltage battery that generates a predetermined low voltage lower than the high-voltage battery, and a DC-DC converter that converts the high voltage supplied from the high-voltage battery to a low voltage and supplies the low-voltage battery and auxiliary equipment with the high-voltage battery. The vehicle control device also includes a control unit that controls the DC-DC converter, and the control unit operates the DC-DC converter intermittently when a predetermined condition is met that indicates that the low-voltage battery terminal may be disconnected. This allows the vehicle control device according to the embodiment of the present invention to avoid a power supply connection state that is contrary to the driver's intention. [Example]

[0010] A vehicle equipped with a vehicle control device according to an embodiment of the present invention will be described below with reference to the drawings.

[0011] As shown in FIG. 1, the vehicle 1 is equipped with a driving motor (referred to as MG in the figure) 4, a high-voltage battery 10 that generates a predetermined high voltage, and a 12V battery 5 as a low-voltage battery that generates a predetermined low voltage lower than that of the high-voltage battery 10.

[0012] The motor 4 is connected to a high-voltage battery 10 via a high-voltage line 2. The motor 4 functions as an electric motor driven by power supplied from the high-voltage battery 10, and also functions as a generator that generates electricity using reverse driving force input from the drive wheels. The power generated by the motor 4 is charged into the high-voltage battery 10. The high-voltage battery 10 is formed, for example, from a lithium-ion battery. The high-voltage battery 10 mainly supplies power to the motor 4.

[0013] The vehicle 1 is equipped with a DC-DC converter 9. The DC-DC converter 9 is connected to a high-voltage battery 10 via a high-voltage line 2. The DC-DC converter 9 converts the high voltage supplied from the high-voltage battery 10 into a low voltage and supplies it to the 12V battery 5 and auxiliary equipment.

[0014] More specifically, the DC-DC converter 9 reduces the voltage of the high-voltage battery 10 to a predetermined low voltage (12 VDC in this embodiment) and supplies power to the 12 V load 7. The DC-DC converter 9 is connected to the 12 V battery 5 and the ECU 8 as a control unit via a low-voltage line 6. The 12 V battery 5 outputs 12 VDC. The ECU 8 and the 12 V load 7 operate on 12 VDC. A current sensor 5A is provided at the output terminal of the 12 V battery 5. The current sensor 5A measures the current flowing through the terminals of the 12 V battery 5.

[0015] In this way, the voltage of the high-voltage battery 10 is converted to a low voltage of 12V by the DC-DC converter 9, and can be used to operate the ECU 8 and the 12V load 7.

[0016] The vehicle 1 is equipped with an inverter 3. The inverter 3 is connected to a high-voltage battery 10 via a high-voltage line 2. The inverter 3 converts the power of the high-voltage battery 10 into AC power and drives a motor 4.

[0017] ECU8 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.

[0018] The ROM of the computer unit stores various constants, various maps, and the like, as well as a program for causing the computer unit to function as the ECU 8. That is, the CPU executes the program stored in the ROM using the RAM as a work area, causing the computer unit to function as the ECU 8 in this embodiment.

[0019] A hood switch 30 and a wheel speed sensor 34 are connected to the ECU 8. Detection signals from the hood switch 30 and the wheel speed sensor 34 are input to the ECU 8. The hood switch 30 has a movable piece (not shown) that detects that an engine hood (not shown) is closed when this movable piece is pressed down. When the engine hood is opened, the movable piece is pushed up by a return spring (not shown). The wheel speed sensor 34 detects the rotational speed of wheels (not shown) (vehicle speed).

[0020] The ECU 8 controls the DC-DC converter 9 and the entire vehicle. The ECU 8 operates the DC-DC converter 9 intermittently when a predetermined condition is met that indicates that the terminals of the 12V battery 5 serving as a low-voltage battery may be disconnected.

[0021] The intermittent operation of the DC-DC converter 9 is preferably performed at a ratio (duty ratio) such that the drive period is longer than the stop period. For example, the DC-DC converter 9 is intermittently operated so that it alternates between 9 seconds of drive and 1 second of stop.

[0022] When the terminals of the 12V battery 5 are disconnected due to the intermittent operation of the DC-DC converter 9, the power supply to the ECU 8 and auxiliary devices is cut off and the vehicle system is turned off while the DC-DC converter 9 is stopped. On the other hand, when the terminals of the 12V battery 5 are not disconnected, the power supply to the ECU 8 and auxiliary devices continues even while the DC-DC converter 9 is stopped, and the vehicle system remains on.

[0023] The predetermined conditions include the vehicle 1 being stopped, the engine hood being open, and the current measured by the current sensor 5A being less than a predetermined value. The ECU 8 determines that the predetermined conditions are met when all three of these conditions are met. Note that the ECU 8 may also determine that the predetermined conditions are met when any one of these three conditions is met.

[0024] Here, in order to disconnect the terminals of the 12V battery 5 for maintenance or the like, the vehicle 1 must be parked and the engine hood must be open. Furthermore, when the terminals of the 12V battery 5 are disconnected, no current flows from the 12V battery 5 to the low-voltage line 6, and therefore the current measured by the current sensor 5A becomes less than a predetermined value. The predetermined conditions under which the terminals of the 12V battery 5 may be disconnected are determined taking these factors into consideration.

[0025] The flow of operations of the ECU 8 will be described with reference to Fig. 2. This operation is repeatedly executed by the ECU 8 at predetermined time intervals.

[0026] The ECU 8 determines whether or not the vehicle is stopped based on the wheel speed detected by the wheel speed sensor 34 (step S1). If the ECU 8 determines that the vehicle is not stopped (NO in step S1), the ECU 8 ends the current operation.

[0027] When the ECU 8 determines that the vehicle is stopped (YES in step S1), it determines (step S2) whether the engine hood (referred to as "hood" in the drawing) is open or not based on the detection result of the hood switch 30. When the ECU 8 determines that the engine hood is not open (NO in step S2), it ends the current operation.

[0028] If the ECU 8 determines that the engine hood is open (YES in step S2), it determines whether or not the current value at the terminals of the 12V battery 5 is 0 A (step S3). If the ECU 8 determines that the current value at the terminals of the 12V battery 5 is not 0 A (NO in step S3), it ends this operation.

[0029] When the ECU 8 determines that the current value at the terminals of the 12V battery 5 is 0 A (YES in step S3), it performs intermittent operation of the DC-DC converter 9 (step S4) and ends the current operation.

[0030] As described above, the vehicle control device of this embodiment includes an ECU 8 that controls the DCDC converter 9, and the ECU 8 operates the DCDC converter 9 intermittently when a predetermined condition is met that indicates that the terminals of the 12V battery 5 serving as a low-voltage battery may be disconnected.

[0031] As a result, in a situation where the removal of the terminals of the 12V battery 5 cannot be accurately detected, if the terminals of the 12V battery 5 are removed, the DCDC converter 9 is driven intermittently, so that the vehicle system can be turned off when the DCDC converter 9 stops, making it behave similarly to an engine vehicle. Furthermore, if the terminals of the 12V battery 5 are not removed, power is supplied to the accessories from the 12V battery 5 even when the DCDC converter 9 stops, and when the DCDC converter 9 is driven, power is supplied to the accessories from the high-voltage battery, so the vehicle system can remain on. As a result, it is possible to avoid a power connection state contrary to the driver's intention.

[0032] In the vehicle control device according to this embodiment, the predetermined conditions include the vehicle 1 being stopped.

[0033] As a result, when the vehicle 1 is stopped, it is determined that the terminals of the 12V battery 5 may be disconnected, and therefore it is possible to avoid a power supply connection state that is contrary to the driver's intention.

[0034] In the vehicle control device according to this embodiment, the predetermined conditions include the engine hood being open.

[0035] As a result, if the engine hood is open, it is determined that the terminals of the 12V battery 5 may be disconnected, and therefore it is possible to avoid a power connection state that is contrary to the driver's intention.

[0036] The vehicle control device according to this embodiment also includes a current sensor 5A that measures the current flowing through the terminals of the 12V battery 5. The predetermined condition includes the current measured by the current sensor 5A being less than a predetermined value.

[0037] As a result, if the current flowing through the terminals of the 12V battery 5 is less than a predetermined value, it is determined that the terminals of the 12V battery 5 may be disconnected, thereby avoiding a power connection state that is contrary to the driver's intention.

[0038] 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]

[0039] 1 vehicle 5 12V battery (low voltage battery) 5A current sensor 7 12V load (auxiliary equipment) 8 ECU (control unit) 9 DC-DC converter 10 High Voltage Battery

Claims

1. a high-voltage battery that generates a predetermined high voltage; a low-voltage battery that generates a predetermined low voltage lower than that of the high-voltage battery; a DC-DC converter that converts a high voltage supplied from the high-voltage battery into a low voltage and supplies the low-voltage battery and an auxiliary device, a control unit for controlling the DC-DC converter; The vehicle control device is characterized in that the control unit causes the DC-DC converter to operate intermittently when a predetermined condition is met that indicates that a terminal of the low-voltage battery may be disconnected.

2. 2. The vehicle control device according to claim 1, wherein the predetermined condition includes the vehicle being stopped.

3. 2. The vehicle control device according to claim 1, wherein the predetermined condition includes an engine hood being open.

4. a current sensor for measuring a current flowing through a terminal of the low-voltage battery; 2. The vehicle control device according to claim 1, wherein the predetermined condition includes a condition that the current measured by the current sensor is less than a predetermined value.

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