JP2007137093A - Power supply system for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shut off a step-down converter acting abnormally by securing supply of a stand-by current of an electric load when the step-down converter for supplying power is failed. <P>SOLUTION: This system comprises a step-down converter 13 interposed in a circuit between an electric load and a battery 11 to converting a voltage to an output voltage lower than an input voltage, protective opening/closing means interposed between the step-down converter and the battery, circuit opening/closing means connected in parallel with the step-down converter, converter abnormality monitoring means for monitoring abnormal actions of the step-down converter, sleep detection means for detecting a stand-by status that an electric volume supplied to the electric load from the battery is lower than a starting status, and control means 18. When the step-down converter detects the stand-by status at the normal time, the control means brings the circuit opening/closing means into a non-conductive status, and brings the circuit opening/closing means when the converter detects the starting status. Meanwhile, when abnormality of the step-down converter is detected, the protective opening/closing means is brought into a non-conductive status, and the circuit opening/closing means is brought into a conductive status. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vehicle power supply system, and more particularly, in a vehicle power supply system that distributes power from an in-vehicle battery to various electric loads, a step-down converter that ensures standby current even when the step-down converter is abnormal and operates abnormally. By cutting off from the circuit, a function for protecting other circuits from abnormal heat generation and noise is added.

Conventionally, since various electric loads (ECU: Electronic Control Unit, actuator, etc.) are operated using electric power charged in a battery in an automobile, it is important to suppress battery power consumption as much as possible.
When the vehicle is in an operating state, the load current is large, and when the electric load is in a standby state, the load current (that is, the standby current) is small, so the power consumption of the electric load varies greatly between the operating state and the standby state of the electric load. . When the battery is designed to improve conversion efficiency when the electrical load is in the operating state, if the same amount of power is supplied as in the operating state when the electrical load is in the standby state, a lot of unnecessary dark current flows and is consumed. The power may increase and battery conversion efficiency may deteriorate. In view of this, it has been considered to reduce power consumption by reducing the power supplied to some of the electric loads in a state where the ignition key is turned off or in a standby state.

  For example, Japanese Unexamined Patent Application Publication No. 2004-201389 (Patent Document 1) describes a power supply system in which a high voltage battery such as 36 to 42 V is used as a power source, and a high voltage load and a low voltage load are connected to the power source. . Patent Document 1 discloses a power supply circuit in which power is supplied to a low-voltage load via a main DC-DC converter or a sub DC-DC converter that steps down to a relatively low voltage (hereinafter referred to as a step-down converter). Yes. When the electric load is in a standby state, the power conversion efficiency can be increased by reducing the power supply voltage to, for example, 12 to 14 V using a step-down converter.

  However, the invention of Patent Document 1 is intended for a power supply system using a high-voltage battery as a power source, and is not currently intended for a general-purpose 12V power supply system. Also, a step-down converter that supplies power to the electrical load when the electrical load is in a standby state may not output a predetermined voltage due to a failure such as a short circuit between the input and output or a short circuit between the input or output and the ground point. is there. Driving the step-down converter in such a state generates heat and noise, and affects circuits other than the step-down converter. Conversely, battery power consumption may be raised. In addition, there is a possibility that the power supply from the step-down converter to the low voltage load may be interrupted, which may cause a reset of the contents of the memory in the ECU.

JP 2004-201389 A

  The present invention has been made in view of the above circumstances, and ensures standby current supply even when a predetermined voltage is not output due to a failure of the step-down converter, and disconnects the step-down converter from the circuit to prevent abnormal heat generation and noise. It is an object to provide a highly reliable vehicle power supply system that protects other circuits from the influence.

In order to solve the above problems, the present invention provides a vehicle power supply system that supplies electric power from a battery to an electric load.
A step-down converter for converting to an output voltage lower than an input voltage by interposing in a circuit between the electric load and the battery;
Protective opening and closing means interposed between the step-down converter and the battery;
Circuit switching means connected in parallel to the step-down converter;
Control means for the protective opening and closing means and circuit opening and closing means;
Converter abnormality monitoring means for monitoring abnormal operation of the step-down converter;
Sleep detection means for detecting a standby state in which the amount of power supplied from the battery to the electric load is reduced compared to the startup state after a predetermined time has elapsed after turning off the ignition key;
When the converter abnormality monitoring unit detects no abnormality and the sleep detection unit detects a standby state, the control unit sets the circuit opening / closing unit to a non-conduction state, and the sleep detection unit When detecting, the circuit opening / closing means is turned on, while when the converter abnormality monitoring means detects an abnormality, the protective opening / closing means is turned off and the circuit opening / closing means is controlled to be turned on. A vehicle power supply system is provided.

According to the above configuration, when an abnormality occurs in the step-down converter, the converter abnormality monitoring means detects the abnormality of the step-down converter, a signal is sent from the converter abnormality monitoring means to the control means, and the control means turns off the protective opening / closing means. The circuit opening / closing means is turned on while being turned on.
By shutting down the step-down converter in which an abnormality has occurred from the vehicle power supply system, it is possible to protect other circuits from abnormal heat generation and noise and prevent damage from spreading. In addition, when the electric load is in a standby state, power cannot be supplied to the electric load if the step-down converter is shut off, but power can be supplied from the battery to the electric load by setting the circuit opening / closing means in a conductive state. By supplying power from the battery to the electrical load, the power conversion efficiency in the standby state of the electrical load is deteriorated, but the standby current required even when the electrical load is in the standby state can be secured. When the electric load is in an operating state, even if an abnormality occurs in the step-down converter, the circuit switching means is already in a conductive state, so that power is continuously supplied from the battery.

  A rectifier connected in series on the secondary side of the step-down converter so that the direction of the electric load from the step-down converter is the forward direction, and the control means is both opened and closed when switching between the protective opening and closing means and the circuit opening and closing means It is preferable that a time difference is given to the opening / closing switching timing so as to form a predetermined length of time during which the means is in a conductive state.

  According to the above-described configuration, when switching between the protective opening / closing means and the circuit opening / closing means, both opening / closing means are both in a conductive state and both opening / closing means are not in a non-conductive state for a predetermined length of time. Therefore, power supply to the electric load can be performed without interruption. Further, since the rectifier is connected so that the direction of the electric load is forward from the step-down converter, it is possible to prevent a current from flowing from the electric load side to the step-down converter side due to a voltage difference between the battery and the step-down converter.

Further, the present invention provides a vehicle power supply system that supplies electric power from a battery to a plurality of electric loads.
A step-down converter for converting to an output voltage lower than an input voltage by interposing in a circuit between the electric load and the battery;
A rectifier connected in series from the step-down converter to the secondary side of the step-down converter so that the direction of the electric load is a forward direction;
Power storage means for storing the secondary voltage of the step-down converter between the rectifier and the secondary side of the step-down converter;
Circuit switching means connected in parallel to the step-down converter;
Control means for the circuit opening and closing means;
Converter abnormality monitoring means for monitoring abnormal operation of the step-down converter;
Sleep detection means for detecting a standby state in which the amount of power supplied from the battery to the electric load is reduced compared to the startup state after a predetermined time has elapsed after turning off the ignition key;
When the converter abnormality monitoring unit detects no abnormality and the sleep detection unit detects a standby state, the control unit sets the circuit opening / closing unit to a non-conduction state, and the sleep detection unit A vehicle power supply system characterized in that when detecting, the circuit opening / closing means is turned on, and when the converter abnormality monitoring means detects an abnormality, the circuit opening / closing means is turned on. providing.

  According to the above configuration, even when the step-down converter does not operate and power is not supplied, the converter abnormality monitoring unit detects an abnormality of the step-down converter, and the control unit sets the circuit opening / closing unit to a conductive state. Electric power can be supplied to each electric load. Even if power is supplied to the electrical load by the step-down converter, even if an abnormality occurs in the step-down converter and the power supply is interrupted, the power supply from the power storage means is performed. Can be prevented.

The converter abnormality monitoring means is preferably voltage monitoring means for measuring a secondary side voltage of the step-down converter and detecting abnormality of the step-down converter when an abnormal voltage is generated.
According to the above configuration, abnormality monitoring can be performed by measuring a voltage generated when an abnormality such as an input / output short circuit of the step-down converter, a short circuit between the input or the output and the ground point occurs.

The converter abnormality monitoring means is preferably current monitoring means for measuring a primary side and / or secondary side current of the step-down converter and detecting an abnormality of the step-down converter when an abnormal current is generated.
According to the above configuration, the abnormality monitoring can be performed by measuring the current generated when an abnormality such as an input / output short circuit of the step-down converter, a short circuit between the input or the output and the ground point occurs.

As described above, according to the present invention, when the step-down converter is abnormal, the converter abnormality monitoring means detects the abnormality, and the protective switching circuit is turned off to disconnect the step-down converter from the vehicle power supply system. It is possible to protect other circuits from abnormal heat generation and noise and prevent damage from spreading. Furthermore, since a large current is prevented from flowing from the battery due to an abnormality in the step-down converter, it is possible to prevent the battery from going up due to a failure of the step-down converter. In addition, when the electric load is in a standby state, even if an abnormality occurs in the step-down converter and the step-down converter is shut off, the circuit switching means is turned on to supply power from the battery to the electric load. A current can be secured.
Furthermore, even when power is being supplied to the electric load by the step-down converter, even if an abnormality occurs in the step-down converter and the power supply is interrupted, the electric power is supplied from the power storage means by providing the power storage means. The interruption of the power supply can be prevented.

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a vehicle power supply system 10 according to the first embodiment, in which a junction box 12 is connected to a 12V battery 11 via a wire W1, and each wire W2 is connected to a circuit branched by the junction box 12. ECUs 20 to 23 and actuators 24 and 25 are connected to each other.

In the junction box 12, a step-down converter 13 composed of a DC-DC converter, a protective relay 14 constituting protective opening / closing means interposed between the step-down converter 13 and the battery 11, and the step-down converter 13 are connected in parallel. The semiconductor relay 15 constituting the circuit switching means, the voltage sensor 16 and the current sensor 17 constituting the converter abnormality monitoring means for monitoring the abnormal operation of the step-down converter 13, the control means 18, and the step-down converter 13 are arranged in the order of the electric load. A rectifier 19 connected in series is provided on the secondary side of the step-down converter 13 so as to have a direction.
The step-down converter 13 is interposed in a circuit between the electric load and the battery 11 and converts it into an output voltage lower than the input voltage. In this embodiment, 12V is converted to 6V.
The voltage sensor 16 provided as converter abnormality monitoring means for monitoring abnormal operation of the step-down converter 13 constitutes voltage monitoring means for measuring the secondary side voltage of the step-down converter 13 and detecting abnormality of the converter 13 when an abnormal voltage is generated. The current sensor 17 constitutes current monitoring means for measuring the primary current of the step-down converter 13 and detecting an abnormality of the step-down converter when an abnormal current is generated.

  The control means 18 makes the semiconductor relay 15 non-conductive when the electric load is in a standby state, and makes the semiconductor relay 15 conductive when the electric load is in an operating state. Further, the control means 18 makes the protective relay 14 non-conductive and makes the semiconductor relay 15 conductive when the voltage sensor 16 and / or the current sensor 17 detects an abnormality.

The protective relay 14 is connected in series with the step-down converter 13, and the protective relay 14 and the step-down converter 13 constitute a parallel connection circuit with the semiconductor relay 15. One of the parallel connection circuits is connected to the battery 11 and the other is connected to the ECUs 20 to 22. A current sensor 17 is connected between the battery 11 and the parallel connection circuit. Further, the output voltage of the step-down converter 13 is monitored by the voltage sensor 16.
The current sensor 17, the protective relay 14, the semiconductor relay 15, and the step-down converter 13 are connected to the control means 18.

Next, the operation of the vehicle power supply system configured as described above will be described.
FIG. 2 is a time chart showing the operation of the vehicle power supply system 10 when the electric load shifts from the operating state to the standby state. When the electric load shifts from the operating state to the standby state, the current value input from the current sensor 17 to the control means 18 is below the threshold value, so the control means 18 puts the semiconductor relay 15 in a non-conducting state. For this reason, electric power is supplied to the electric load by the voltage of the step-down converter 13. The protective relay 14 is in a conductive state as long as there is no abnormality in the step-down converter 13.

Further, the switching between the step-down converter 13 and the semiconductor relay 15 by the control means 18 is set so that one ON operation is advanced by a predetermined time T1 from the other OFF operation so that there is no timing when both of them are simultaneously OFF. Yes. By setting in this way, when the step-down converter 13 and the semiconductor relay 15 are switched, the step-down converter 13 and the semiconductor relay 15 are both in a conductive state, so that power supply to the electric load can be performed without interruption. . Further, since the rectifier 19 is connected from the step-down converter 13 so that the direction of the electric load is a forward direction, a current flows from the electric load side to the step-down converter 13 side due to a voltage difference between the battery 11 and the step-down converter 13. Can be prevented.
On the other hand, when the electric load shifts from the standby state to the operating state, the current value input from the current sensor 17 to the control unit 18 exceeds a preset threshold value, and thus the control unit 18 brings the semiconductor relay 15 into a conductive state. With this operation, electric power is supplied from the battery 11 to the electric load.

The operation when abnormality occurs in the step-down converter 13 will be described below.
FIG. 3A is a time chart showing the operation of the vehicle power supply system 10 when a short circuit accident occurs at the input / output terminals of the step-down converter 13 when power is supplied to the electric load by the step-down converter 13. .
When the electrical load is in a standby state, the current value measured by the current sensor 17 is smaller than a predetermined threshold value, so that the semiconductor relay 15 is in a non-conduction state. Therefore, the electric power from the step-down converter 13 is supplied to the electric load.

  Here, when a short circuit accident of the input / output terminal of the step-down converter 13 occurs, the output voltage of the step-down converter 13 monitored by the voltage sensor 16 exceeds the predetermined threshold Vth as shown in FIG. Is done. At this time, the control means 18 brings the protective relay 14 into a non-conductive state and brings the semiconductor relay 15 into a conductive state.

  In this way, by shutting down the step-down converter 13, it is possible to protect other circuits from abnormal heat generation and noise, and to prevent damage expansion. Further, by making the semiconductor relay 15 conductive, it is possible to supply electric power from the battery 11 to the electric load even when the step-down converter 13 is cut off, and to ensure the standby current required even when the electric load is in the standby state. can do.

  Note that the predetermined threshold Vth for determining that the output voltage of the step-down converter 13 is abnormal is determined by the output specification of the step-down converter 13. For example, the rated output value can be set to + 10% or more. The value width can be arbitrarily set as long as the value is larger than the normal output range.

FIG. 3B shows a time chart when the terminal of the step-down converter 13 is short-circuited to the ground when power is supplied to the electric load by the battery 11.
When the electric load is in an operating state, the current value measured by the current sensor 17 is larger than a predetermined threshold value, so that the semiconductor relay 15 is in a conductive state. Therefore, the electric power from the battery 11 is supplied to the electric load.
Here, when the input terminal of the step-down converter 13 is short-circuited to the ground, the current value measured by the current sensor 17 exceeds the overcurrent threshold Ith as shown in FIG. At this time, the control means 18 makes the protective relay 14 non-conductive. By shutting down the step-down converter 13, it is possible to protect other circuits from abnormal heat generation and noise and to prevent damage from spreading.

A predetermined overcurrent threshold Ith for determining that the output current of step-down converter 13 is abnormal is determined by the output specification of step-down converter 13. For example, the current value flowing at the rated output can be set to + 10% or more. The value width can be arbitrarily set as long as the value is larger than the normal output range.
Further, in the time chart of FIG. 3B, the abnormal operation when the terminal of the step-down converter 13 is short-circuited to the ground is detected using the current sensor 17, but it may be detected using the voltage sensor 16. The predetermined threshold Vth for determining that the output voltage of the step-down converter 13 is abnormal is determined by the output specification of the step-down converter 13. For example, the voltage value at the rated output can be set to -10% or more. The value width can be arbitrarily set as long as it is smaller than the normal output range.

  Although the current sensor 17 is provided on the primary side of the step-down converter 13 in the above example, it may be provided on the secondary side, or may be provided on both the primary side and the secondary side. Even if it is provided on the secondary side, an abnormality of the step-down converter 13 can be detected by measuring the current value. Further, by providing both the primary side and the secondary side, it is possible to perform abnormality detection with higher reliability.

FIG. 4 shows a second embodiment.
The difference from the first embodiment is that a capacitor 51 constituting a storage means for accumulating the secondary voltage of the step-down converter is connected between the step-down converter 13 and the rectifier 19 between the rectifier and the secondary side of the step-down converter. The protection relay 14 is deleted.

When the electrical load changes from the operating state to the standby state, the current value input from the current sensor 17 to the control means 18 is below the threshold value, so that the control means 18 detects the semiconductor relay after the time T1 elapses after the current value falls below the threshold value. 15 is changed from the conductive state to the non-conductive state. In the standby state, electric power is supplied to the electric load by the voltage of the step-down converter 13.
Here, FIG. 5A shows a time chart in the case where power is not supplied from the step-down converter 13 due to a failure of the step-down converter 13 when the electric load changes from the operating state to the standby state.
Even after the current value input from the current sensor 17 to the control means 18 falls below the threshold value and the electric load is in the standby state, the voltage value detected by the voltage sensor 16 is smaller than the threshold value because power is not supplied from the step-down converter 13. At this time, the control means 18 does not turn off the semiconductor relay 15 even after the time T1 after the current value falls below the threshold value, and keeps the conductive state. For this reason, the power supply to the electric load is performed without interruption by the battery 11.

FIG. 5B shows a time chart when power is not supplied due to an abnormality in the step-down converter 13 when power is supplied to the electric load by the step-down converter 13.
When the voltage sensor 16 detects that the power from the step-down converter 13 has suddenly decreased, the control means 18 brings the semiconductor relay 15 into a conducting state. However, a time lag occurs between the time when the voltage sensor 16 detects that the power from the step-down converter 13 is not supplied and the time when the semiconductor relay 15 is turned on. During this time, power is not supplied from the battery 11 or the step-down converter 13 to the electric load, but power can be supplied by the capacitor 51.

  The abnormal operation of the vehicular power supply system 10 can be notified to a higher-level information processing apparatus via an in-vehicle LAN or the like. The user can be notified by a warning sound or warning display.

  In the above embodiment, the operating state and the standby state of the electric load are determined based on the detected current value by connecting the current sensor 17, but a signal indicating the operating state and the standby state is input to the control means 18 from the outside. May be. In this case, the current sensor 17 can be deleted.

FIG. 6 shows a third embodiment.
The third embodiment is an embodiment in which the configurations of the first embodiment and the second embodiment are combined. The difference from the first embodiment is that the secondary of the step-down converter is between the rectifier and the secondary side of the step-down converter. The capacitor 51 which comprises the electrical storage means to accumulate | store a voltage is connected between the step-down converter 13 and the rectifier 19.

When the step-down converter 13 cannot supply power, the current sensor 17 or the voltage sensor 16 detects an abnormality of the step-down converter 13, and the control means 18 turns off the protective relay 14 and turns on the circuit opening / closing means. .
Further, when power is supplied to the electric load by the step-down converter 13, even if the power supply from the step-down converter 13 is interrupted, power is supplied from the capacitor 51.

It is a block diagram of the power supply system for vehicles of a 1st embodiment of the present invention. It is a time chart which shows operation | movement of the power supply system for vehicles. (A) is a time chart for explaining the operation when a short circuit accident of the input / output terminal of the step-down converter occurs, and (B) is a time chart for explaining the operation when the terminal of the step-down converter is grounded. It is a block diagram of the power supply system for vehicles of a 2nd embodiment of the present invention. (A) is a time chart for explaining the operation when power is not supplied from the step-down converter during switching, and (B) is a time chart for explaining the operation when power is not supplied during operation of the step-down converter. It is a block diagram of the power supply system for vehicles of a 3rd embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Vehicle power supply system 11 Battery 12, 30, 40 Junction box 13 Buck converter 14 Protection relay 15 Semiconductor relay 16 Voltage sensor 17 Current sensor 18 Control means 19 Rectifier 20-23 ECU
24, 25 Actuator 51 Capacitor

Claims (5)

In a vehicle power supply system that supplies electric power from a battery to an electric load,
A step-down converter for converting to an output voltage lower than an input voltage by interposing in a circuit between the electric load and the battery;
Protective opening and closing means interposed between the step-down converter and the battery;
Circuit switching means connected in parallel to the step-down converter;
Control means for the protective opening and closing means and circuit opening and closing means;
Converter abnormality monitoring means for monitoring abnormal operation of the step-down converter;
Sleep detection means for detecting a standby state in which the amount of power supplied from the battery to the electric load is reduced compared to the startup state after a predetermined time has elapsed after turning off the ignition key;
When the converter abnormality monitoring unit detects no abnormality and the sleep detection unit detects a standby state, the control unit sets the circuit opening / closing unit to a non-conduction state, and the sleep detection unit When detecting, the circuit opening / closing means is turned on, while when the converter abnormality monitoring means detects an abnormality, the protective opening / closing means is turned off and the circuit opening / closing means is controlled to be turned on. A power supply system for a vehicle. A rectifier connected in series on the secondary side of the step-down converter so that the direction of the electric load from the step-down converter is a forward direction;
2. The switching means sets a time difference in opening / closing switching timing so as to form a predetermined length of time during which the opening / closing means is in a conductive state when switching between opening / closing of the protective opening / closing means and circuit opening / closing means. The vehicle power supply system described in 1. In a vehicle power supply system that supplies electric power from a battery to a plurality of electric loads,
A step-down converter for converting to an output voltage lower than an input voltage by interposing in a circuit between the electric load and the battery;
A rectifier connected in series from the step-down converter to the secondary side of the step-down converter so that the direction of the electric load is a forward direction;
Power storage means for storing the secondary voltage of the step-down converter between the rectifier and the secondary side of the step-down converter;
Circuit switching means connected in parallel to the step-down converter;
Control means for the circuit opening and closing means;
Converter abnormality monitoring means for monitoring abnormal operation of the step-down converter;
Sleep detection means for detecting a standby state in which the amount of power supplied from the battery to the electric load is reduced compared to the startup state after a predetermined time has elapsed after turning off the ignition key;
When the converter abnormality monitoring unit detects no abnormality and the sleep detection unit detects a standby state, the control unit sets the circuit opening / closing unit to a non-conduction state, and the sleep detection unit The vehicle power supply system is characterized in that when detecting, the circuit opening / closing means is in a conducting state, and when the converter abnormality monitoring means detects an abnormality, the circuit opening / closing means is in a conducting state.   The power supply for vehicles according to any one of claims 1 to 3, wherein the converter abnormality monitoring means has voltage monitoring means for measuring a secondary side voltage of the step-down converter and detecting abnormality of the converter when an abnormal voltage is generated. system.   5. The converter abnormality monitoring unit according to claim 1, further comprising a current monitoring unit that measures a primary side and / or secondary side current of the step-down converter and detects an abnormality of the converter when an abnormal current occurs. The vehicle power supply system described in 1.

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