JP2012065488A - Vehicle power supply system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress power consumption of a low-voltage battery and extend a range of emergency retreating travel at an occurrence of a failure in a DC/DC converter in a vehicle power supply system.SOLUTION: An onboard electrical load (7) that is indispensable for running a vehicle is directly connected to a low-voltage battery (4). onboard electrical loads (8 and 9) that are not indispensable for running a vehicle are connected to the low-voltage battery (4) via power supply blocking means (10 and 11). A control means (12) is provided that makes the power supply blocking means (10 and 11) block power supply to the onboard electrical loads (8 and 9) that are not indispensable for running a vehicle, when a failure detecting means (13) detects a failure in a DC/DC converter (5).

Description

  The present invention relates to a power supply system for a vehicle, and in particular, two batteries, a high voltage battery that supplies power to a drive system and a low voltage battery that supplies power to a control system and an auxiliary machine, and the voltage of the high voltage battery. The present invention relates to a vehicle power supply system including a DC / DC converter that steps down and charges a low-voltage battery.

Generally, electric vehicles such as electric vehicles and hybrid vehicles equipped with a motor for traveling are used as a high voltage battery for driving the motor and a low voltage battery (gasoline vehicle for driving the electrical equipment and auxiliary equipment). As well as a 12V system lead storage battery, etc., and a DC / DC converter that steps down the voltage of the high voltage battery and charges the low voltage battery.
Moreover, in such a vehicle, the information of each component, such as a motor for driving, an engine, and a battery, is managed, and is provided with a control means (integrated ECU) that performs integrated control, or the control means of any component includes A function to perform the above-described integrated control is often provided.

JP-A-7-107620 JP 2002-200908 A JP 2005-229706 A

The abnormality monitoring device for a DC / DC converter for an electric vehicle according to Patent Document 1 includes a protection function against an internal failure such as an overcurrent, an overvoltage, a short circuit, or a disconnection in the DC / DC converter, and the output voltage of the DC / DC converter is When a decrease and / or an abnormal increase is detected, an abnormal alarm is issued.
The power distribution device for a vehicle according to Patent Document 2 supplies power to an important in-vehicle electric load even when power supply to the entire in-vehicle electric load is impossible, and suppresses a decrease in vehicle running function to a minimum. .
The vehicle control device according to Patent Document 3 performs traveling in a normal state as much as possible even if an abnormality occurs in the power conversion mechanism (DC / DC converter).

However, conventionally, in the above-mentioned Patent Document 1, when an abnormality occurs in the DC / DC converter, the power supply from the DC / DC converter to the 12V auxiliary machine, which is an in-vehicle electric load, or the charging of the 12V battery is performed. As a result, the voltage of the 12V battery is lowered by driving the 12V auxiliary machine. For this reason, in the case of an electric vehicle or a hybrid vehicle, the electric load of a 12V auxiliary machine is larger than that of a gasoline vehicle, and a vacuum pump or the like that generates a negative brake pressure is also a 12V auxiliary machine. For this reason, it greatly affects the running performance of the vehicle.
In order to solve such a problem, as described in Patent Document 2 above, it is possible to cut off the power supply to the in-vehicle electric load with low importance and to perform priority power supply to the in-vehicle electric load with high importance. Various means have been proposed, such as a method of providing a power supply control device that performs the above, and control for limiting the driving of an in-vehicle electric load as described in Patent Document 3 above.
However, in the above-mentioned Patent Document 2, it is necessary to newly add a 12V power supply system power supply control device, resulting in an increase in cost, and the configuration of an electric vehicle such as an electric vehicle and a hybrid vehicle, and DC / No abnormality of the DC converter is assumed.
Moreover, in the above-mentioned patent document 3, the vehicle-mounted electric load (for example, the audio equipment etc. which operate | moves mechanically by a driver | operator's switch operation etc.) which is out of the control object of the control means (integrated ECU) which performs drive restriction of a vehicle-mounted electric load The control means cannot be used in common with the parts used in the existing gasoline vehicle when the effect is not obtained, and all on-vehicle electric loads are controlled by the control means. However, there is a disadvantage that the cost increases.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a power supply system for a vehicle that can reduce the power consumption of a low-voltage battery and extend the distance that can be evacuated.

  The present invention provides a motor for driving wheels, a high voltage battery for supplying electric power to the motor, a low voltage battery for supplying electric power to an in-vehicle electric load, and a DC / DC for stepping down the voltage of the high voltage battery. In a vehicle power supply system in which a DC converter is provided and the low voltage battery is charged by a voltage stepped down by the DC / DC converter, an in-vehicle electric load indispensable for vehicle travel is directly connected to the low voltage battery for vehicle travel. A non-essential in-vehicle electric load is connected to the low-voltage battery through a power-off means for cutting off the power supply to the in-vehicle electric load, and provided with an abnormality detection means for detecting an abnormality in the DC / DC converter. When an abnormality of the DC / DC converter is detected by the detecting means, it is indispensable for the vehicle traveling by the power shut-off means. Characterized in that a control means for interrupting the power supply to the vehicle electrical loads are.

  The vehicle power supply system of the present invention continues to supply power to an in-vehicle electric load that is indispensable for traveling when an abnormality occurs in the DC / DC converter, while supplying power to an in-vehicle electric load that is not indispensable for traveling. Since it stops, the power consumption of the low-voltage battery can be suppressed, and the distance that can be evacuated can be extended.

FIG. 1 is a configuration diagram of a vehicle power supply system. (Example) FIG. 2 is a flowchart of power control of the vehicle. (Example)

  The present invention aims to reduce the power consumption of the low-voltage battery and extend the distance that can be evacuated. When an abnormality occurs in the DC / DC converter, while continuing to supply power to the in-vehicle electric load that is indispensable for traveling, This is achieved by stopping the power supply to the in-vehicle electric load that is not essential for traveling.

1 and 2 show an embodiment of the present invention.
In FIG. 1, reference numeral 1 denotes a power supply system mounted on an electric vehicle such as an electric vehicle or a hybrid vehicle.
The power supply system 1 includes a traveling motor 2 that drives wheels, a high-voltage battery 3 that supplies electric power to the motor 2, and a low-voltage battery 4 that supplies electric power to on-vehicle electric loads 7, 8, and 9 described later. (12V lead acid battery or the like) and a DC / DC converter 5 that steps down the voltage of the high voltage battery 3 are provided, and the low voltage battery 4 is charged by the voltage stepped down by the DC / DC converter 5.
The high voltage battery 3 is connected to a DC / DC converter 5 and an inverter 6. The motor 2 is driven and controlled by an inverter 6. The voltage of the high voltage battery 3 is stepped down by the DC / DC converter 5 and supplied to the low voltage battery 4 and vehicle electric loads 7, 8, and 9 described later.

In the power supply system 1, a first in-vehicle electric load (12V auxiliary machine) 7 as an in-vehicle electric load indispensable for vehicle travel is directly connected to the low-voltage battery 4, but is not indispensable for vehicle travel. The second in-vehicle electric load (12V system auxiliary machine) 8 and the third in-vehicle electric load (12V system auxiliary machine) 9 which are electric loads are connected via the first power supply cutoff means 10 and the second power supply cutoff means 11. Connected to the low voltage battery 4.
The first on-vehicle electric load 7 is a 12V auxiliary machine that is indispensable for traveling in the vehicle, and is directly connected to the low-voltage battery 4 and the DC / DC converter 5.
The second in-vehicle electric load 8 is a 12V auxiliary machine having a lower priority than the first in-vehicle electric load 7 in traveling the vehicle, and the low-voltage battery 4 is connected via the first power shut-off means 10. And a DC / DC converter 5.
The third in-vehicle electric load 9 is a 12V auxiliary machine having a lower priority than the second in-vehicle electric load 8 when traveling on the vehicle, and the low-voltage battery 4 is connected via the second power shut-off means 11. And a DC / DC converter 5.
The first power cut-off means 10 and the second power cut-off means 11 cut off the power supply to the second in-vehicle electric load 8 and the third in-vehicle electric load 9, and include a DC / DC converter 5 and an inverter. 6 and the like, the control means (integrated ECU) 12 for integrated control of various components is communicated, and the operation of the control means 12 is controlled.
The first power shut-off means 10 and the second power shut-off means 11 are intended to shut off the power supply in an emergency. Therefore, the first power shut-off means 10 and the second power shut-off means 11 are electrically connected in a normal state and electrically only when energized. The use of a contact relay or the like having a mechanism to be disconnected is preferable from the viewpoint of efficiency and reliability.
In the power supply system 1, the DC / DC converter 5 includes an abnormality detection unit 13 so as to detect an abnormality in the DC / DC converter 5.
The control means 12 is in communication with a first power cutoff means 10, a second power cutoff means 11, and an abnormality detection means 13.

Then, when the abnormality detection unit 13 detects the abnormality of the DC / DC converter 5, the control unit 12 operates the first power cutoff unit 10 and the second power cutoff unit 11 to operate the second on-vehicle electric load. 8. Shut off the power supply to the third in-vehicle electric load 9.
As a result, when an abnormality occurs in the DC / DC converter 5, the power supply to the first in-vehicle electric load 7 of the 12V system auxiliary equipment indispensable for traveling is continued, while the 12V system auxiliary equipment not essential for traveling is continued. Since power supply to the second in-vehicle electric load 8 and the third in-vehicle electric load 9 is stopped, the power consumption of the low-voltage battery 4 can be suppressed, and the retreatable distance can be extended.
Further, the control means 12 for controlling the second in-vehicle electric load 8 and the third in-vehicle electric load 9 of the 12V auxiliary machine stops the second in-vehicle electric load 8 and the third in-vehicle electric load 9 of the 12V auxiliary machine. The control means 12 uses the first power cutoff means 10 and the second power cutoff means 11 to stop the power supply to the second in-vehicle electric load 8 and the third in-vehicle electric load 9 of the 12V auxiliary machine. It is possible to make common parts such as the second onboard electric load 8 and the third onboard electric load 9 and the control means 12 of the existing gasoline vehicle and the 12V system auxiliary machine.

Further, the control means 12 includes voltage detection means 14 for detecting the power supply voltage value of the low voltage battery 4, and the second in-vehicle electric load 8 and the third in-vehicle electric load 9 which are in-vehicle electric loads that are not essential for vehicle travel. Further, it is divided into at least two according to the priority, and the one with the higher priority is a plurality of first power shut-off means 10, which are a plurality of power shut-off means according to the voltage value detected by the voltage detecting means 14. The power supply to the second in-vehicle electric load 8 and the third in-vehicle electric load 9 is interrupted by the second power interruption means 11. The voltage detection means 14 is connected to the DC / DC converter 5 and the low voltage battery 4.
Thereby, when the voltage of the low voltage battery 4 decreases, the power supply to the second in-vehicle electric load 8 and the third in-vehicle electric load 9 of the 12V auxiliary machine is performed according to the priority according to the degree of the voltage decrease. Since the vehicle stops, it is possible to perform evacuation according to the situation.

Next, power control according to this embodiment will be described based on the flowchart of FIG.
As shown in FIG. 2, when the program of the control means 12 is started (step A01), it is determined whether or not there is an abnormality in the DC / DC converter 5 (step A02).
If this step A02 is NO, it is determined whether or not the voltage of the low voltage battery 4 <the first determination value A (step A03). The first determination value A is a threshold value for determining the voltage drop state of the low voltage battery 4.
When step A03 is YES or when step A02 is YES, the second power shut-off means 11 is activated (ON) (step A04), and the voltage of the low voltage battery 4 <second determination. It is determined whether or not the value is B (step A05). The second determination value B is a threshold value for determining the voltage drop state of the low voltage battery 4. Here, the magnitude relationship between the first determination value A and the second determination value B is A> B.
If step A05 is YES, the first power shut-off means 10 is activated (turned on) (step A06), and the program is returned (step A07).
On the other hand, when the step A03 is NO, the second power shut-off means 11 and the first power shut-off means 10 are not operated, and the program is returned (step A07). If step A05 is NO, the first power shut-off means 10 is not activated and the program is returned (step A07).

  That is, in this embodiment, in the power supply system 1 equipped with 12V auxiliary equipment for electric vehicles and hybrid vehicles, an abnormality is detected when an abnormality occurs in the 12V system including the low voltage battery 4 and the DC / DC converter 5. A function capable of cutting off the power supply to the second in-vehicle electric load 8 and the third in-vehicle electric load 9 of the 12V auxiliary machine that is not indispensable for performing the evacuation traveling of the vehicle by a signal from the control means 12 at a low cost. Can be implemented.

  The vehicle power supply system according to the present invention can be applied to various vehicles.

DESCRIPTION OF SYMBOLS 1 Power supply system of vehicle 2 Motor 3 High voltage battery 4 Low voltage battery 5 DC / DC converter 6 Inverter 7 1st vehicle electric load (vehicle electric load indispensable for vehicle travel)
8 Second in-vehicle electrical load (in-vehicle electrical load not essential for vehicle travel)
9 Third in-vehicle electrical load (in-vehicle electrical load not essential for vehicle travel)
10 First power cut-off means 11 Second power cut-off means 12 Control means (integrated ECU)
13 Abnormality detection means 14 Voltage detection means

Claims (2)

  A motor for driving the wheel is provided, a high voltage battery for supplying electric power to the motor is provided, a low voltage battery for supplying electric power to the in-vehicle electric load is provided, and a DC / DC converter for stepping down the voltage of the high voltage battery is provided. In the vehicle power supply system that charges the low-voltage battery with the voltage stepped down by the DC / DC converter, an in-vehicle electric load that is indispensable for vehicle travel is directly connected to the low-voltage battery and is not indispensable for vehicle travel. The electrical load is connected to the low voltage battery via a power shut-off means for shutting off the power supply to the in-vehicle electrical load, and provided with an abnormality detecting means for detecting an abnormality of the DC / DC converter. On-vehicle electricity that is not indispensable for the vehicle travel by the power shut-off means when an abnormality of the DC / DC converter is detected Vehicle power supply system, characterized in that a control means for interrupting the power supply to the load.   The control means includes a voltage detection means for detecting a power supply voltage value of the low-voltage battery, further divides the in-vehicle electric load that is not indispensable for vehicle travel into at least two according to priority, and has a high priority. According to the voltage value detected by the voltage detection means, the power supply system for the vehicle is characterized in that the power supply to the in-vehicle electric load that is not indispensable for traveling of the vehicle is cut off by the plurality of power cut-off means.

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