JP5964215B2 - Charge / discharge control circuit, power supply device for vehicle, and failure determination method - Google Patents

Description

  The present invention relates to a charge / discharge control circuit for controlling charge / discharge of a capacitor and a battery, a vehicle power supply device, and a failure determination method.

  Some vehicles, such as automobiles, are equipped with an idle stop function that stops idle operation of an engine when traveling is stopped at an intersection or the like.

  An example of a system that realizes such an idle stop function is an energy recovery type idle stop system. The system includes a vehicle power supply device including a capacitor such as an electric double layer capacitor, a battery, and a charge / discharge control circuit that controls charge / discharge of the capacitor and the battery.

  In this system, the capacitor is charged using the electric power generated by the generator when the vehicle is running or when the brake is depressed. When a predetermined restart condition such as when the driver steps on the accelerator during idle stop is satisfied, the starter is operated using the power of the capacitor instead of the power of the battery, thereby restarting the engine. . In such a system, since the voltage of the battery does not decrease when the engine is restarted, it is not necessary to provide a booster circuit between the battery and the electrical component load.

  As an apparatus similar to this idle stop system, the apparatus described in Patent Document 1 is also known.

JP 2011-190735 A

  By the way, in the idle stop system, there is a possibility that a short circuit failure occurs in which both terminals of the capacitor are connected to the ground. If the idle stop is performed in a state where the capacitor is short-circuited, the engine cannot be restarted because power cannot be supplied from the capacitor to the starter even if the restart condition is subsequently satisfied. For this reason, it is necessary to determine whether or not there is a short circuit failure of the capacitor, and to perform control so that, for example, an idle stop is not performed when a short circuit failure occurs. When a short circuit failure occurs, the capacitor voltage approaches the ground voltage.

  However, simply determining that a short-circuit failure has occurred when the capacitor voltage is close to the ground voltage, the capacitor voltage is close to the ground voltage even when the capacitor is not charged, such as immediately after the vehicle is assembled. Even if the connection is normal, there is a possibility that a failure is determined. That is, there is a problem that the presence or absence of a short circuit failure of the capacitor cannot be accurately determined.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a charge / discharge control circuit, a vehicle power supply device, and a failure determination method that can accurately determine whether or not a short circuit failure has occurred in a capacitor.

A charge / discharge control circuit according to one embodiment of the present invention includes:
A charge / discharge control circuit that has a first terminal to which a capacitor and a starter are connected, a second terminal to which a chargeable / dischargeable battery and a power generation unit are connected, and controls charge / discharge of the capacitor and the battery. ,
The starter starts the engine using the electric power supplied from the first terminal,
The power generation unit generates power by rotation of the engine, and outputs power corresponding to the generated power to the second terminal,
Switching between a discharging state in which the capacitor voltage at the first terminal is boosted or lowered and output to the second terminal and a charging state in which the battery voltage at the second terminal is boosted or lowered and output to the first terminal are switched. Possible power circuit,
A detection unit for detecting the capacitor voltage and the battery voltage;
A control unit that switches the power supply circuit to the charged state when the charging mode is entered, starts charging the capacitor, and controls the power supply circuit so that the capacitor voltage approaches a target voltage; and
The controller is
(A) the capacitor voltage is equal to or lower than a first specified voltage;
(B) A specified time or more has elapsed from the start of charging of the capacitor, and
(C) When the battery voltage is equal to or higher than a second specified voltage higher than the first specified voltage, it is determined that a short circuit failure of the capacitor has occurred.

In the charge / discharge control circuit,
When the capacitor is not short-circuited and the battery voltage is equal to or higher than the second specified voltage, the capacitor voltage exceeds the first specified voltage after the specified time from the start of charging. The specified time, the first specified voltage, and the second specified voltage may be set.

A power supply device for a vehicle according to an aspect of the present invention includes:
A capacitor;
A chargeable / dischargeable battery;
A charge / discharge control circuit which has a first terminal to which the capacitor is connected and a second terminal to which the battery is connected, and which controls charge / discharge of the capacitor and the battery;
A starter for starting the engine using the electric power supplied from the first terminal;
A power generation unit that generates electric power by rotating the engine and outputs electric power corresponding to the generated electric power to the second terminal,
The charge / discharge control circuit includes:
Switching between a discharging state in which the capacitor voltage at the first terminal is boosted or lowered and output to the second terminal and a charging state in which the battery voltage at the second terminal is boosted or lowered and output to the first terminal are switched. Possible power circuit,
A detection unit for detecting the capacitor voltage and the battery voltage;
A control unit that controls the power supply circuit so that the capacitor voltage approaches a target voltage by switching the power supply circuit to the charging state when charging mode is started and charging of the capacitor is started;
The controller is
(A) the capacitor voltage is equal to or lower than a first specified voltage;
(B) A specified time or more has elapsed from the start of charging of the capacitor, and
(C) When the battery voltage is equal to or higher than a second specified voltage higher than the first specified voltage, it is determined that a short circuit failure of the capacitor has occurred.

A failure determination method according to an aspect of the present invention includes:
A charge / discharge control circuit that has a first terminal to which a capacitor and a starter are connected, a second terminal to which a chargeable / dischargeable battery and a power generation unit are connected, and controls charge / discharge of the capacitor and the battery. The starter starts the engine using the power supplied from the first terminal, and the power generation unit generates power by rotation of the engine, and supplies the power corresponding to the generated power to the second terminal. A discharging state in which the capacitor voltage of the first terminal is boosted or stepped down and output to the second terminal; and a charging state in which the battery voltage of the second terminal is stepped up or stepped down and output to the first terminal; , A detection unit that detects the capacitor voltage and the battery voltage, and when in a charging mode, the power supply circuit is switched to the charging state, In failure determination method in a charging and discharging control circuit comprising the capacitor voltage to start electric and a control unit for controlling the power supply circuit so as to approach the target voltage, and
(A) the capacitor voltage is equal to or lower than a first specified voltage;
(B) A specified time or more has elapsed from the start of charging of the capacitor, and
(C) When the battery voltage is equal to or higher than a second specified voltage higher than the first specified voltage, it is determined that a short circuit failure of the capacitor has occurred.

  According to the present invention, (A) the capacitor voltage is less than or equal to the first specified voltage, (B) more than a specified time has elapsed since the start of charging the capacitor, and (C) the battery voltage is higher than the first specified voltage. When the voltage is equal to or higher than the second specified voltage, it is determined that the capacitor is short-circuited.

  Therefore, when the capacitor is not short-circuited and the battery voltage is equal to or higher than the second specified voltage, the capacitor voltage is set to exceed the first specified voltage after a specified time from the start of charging the capacitor. Thus, when the capacitor is not short-circuited and is not charged immediately after the start of charging, the conditions (A) and (B) are not satisfied, so that a short-circuit failure can be prevented from being erroneously determined.

  Furthermore, since the condition (C) is not satisfied when the battery voltage is less than the second specified voltage and the capacitor cannot be sufficiently charged, it is possible to prevent erroneous determination of a short circuit failure.

  Accordingly, it is possible to accurately determine the presence or absence of a capacitor short-circuit failure. In addition, it is possible to determine the presence or absence of a short fault by calculation by the control unit without adding a special circuit to the existing circuit.

It is a block diagram which shows the structure of the vehicle power supply device which concerns on one Embodiment of this invention.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. This embodiment does not limit the present invention.

  FIG. 1 is a block diagram showing a configuration of a vehicle power supply device 100 according to an embodiment of the present invention. This vehicle power supply device 100 is used in an energy recovery type idle stop system mounted on a vehicle such as an automobile.

  As shown in FIG. 1, the vehicle power supply device 100 includes a charge / discharge control circuit 10, a capacitor C, a chargeable / dischargeable battery B, a starter 20, and a power generation unit (ACG) 30.

  The charge / discharge control circuit 10 includes a first terminal T1 to which one end of the capacitor C and the starter 20 is connected, and a second terminal T2 to which one end of the battery B, the power generation unit 30, and the electrical component load 300 is connected. The charging / discharging of the capacitor C and the battery B is controlled.

The capacitor C is, for example, an electric double layer capacitor and has a capacity capable of starting the engine 200. Capacitor C has a faster charging and discharging reaction than battery B, and can be charged and discharged with a large current.
The battery B is a secondary battery such as a lead battery, for example.

  The starter 20 includes an electric motor, and starts the engine 200 using electric power supplied from the first terminal T1 of the charge / discharge control circuit 10. When a predetermined restart condition is satisfied such as when the driver steps on the accelerator during the idle stop, the starter 20 restarts the engine 200 using the electric power of the capacitor C.

  The power generation unit 30 generates power by rotation of the engine 200 when the vehicle is running or when a brake is depressed, and outputs DC power corresponding to the generated AC power to the second terminal T2 of the charge / discharge control circuit 10. To do. Specifically, the power generation unit 30 converts the generated AC power into DC power and outputs the DC power.

  The electrical component load 300 is various loads such as an audio device and a navigation device provided in the vehicle, for example.

  The other ends of the capacitor C, the starter 20, the battery B, the power generation unit 30, and the electrical component load 300 are grounded.

  The charge / discharge control circuit 10 will be described in more detail. The charge / discharge control circuit 10 includes a bidirectional step-up / down power supply (power supply circuit) 11, a detection unit 12, and a control unit 13.

  The bidirectional buck-boost power supply 11 boosts or steps down the capacitor voltage Vc at the first terminal T1 and outputs it to the second terminal T2, and boosts or steps down the battery voltage Vb at the second terminal T2. The state of charge output at T1 can be switched.

  The detection unit 12 detects the capacitor voltage Vc at the first terminal T1 and the battery voltage Vb at the second terminal T2.

  The control unit 13 is composed of a digital circuit such as a CPU, and controls the bidirectional step-up / down power supply 11 based on an external signal. When the control unit 13 enters the charging mode, that is, when a charging instruction is input from the outside or when it is determined that charging should be performed based on a signal from the outside, the bidirectional step-up / down power supply 11 is charged. To start charging of the capacitor C and control the bidirectional buck-boost power supply 11 so that the capacitor voltage Vc approaches the target voltage Vi. The target voltage Vi may be directly input to the control unit 13 from the outside, or may be set by the control unit 13 based on a signal from the outside.

  Note that the control unit 13 also performs other control related to charging / discharging of the capacitor C and the battery B according to various external signals, but is directly related to the determination of the presence or absence of the short-circuit failure of the capacitor C in the present embodiment. The explanation is omitted.

  The control unit 13 determines whether or not there is a short circuit failure of the capacitor C. When a short circuit failure of the capacitor C occurs, the first terminal T1 and the ground are electrically short-circuited.

  Specifically, the control unit 13 determines that (A) the capacitor voltage Vc is equal to or lower than the first specified voltage, (B) a specified time or more has elapsed from the start of charging of the capacitor C, and (C) the battery voltage Vb is When the voltage is equal to or higher than the second specified voltage higher than the first specified voltage, that is, when the three conditions (A) to (C) are satisfied, it is determined that the short-circuit failure of the capacitor C has occurred.

  The specified time, the first specified voltage, and the second specified voltage are set in advance as described below and stored in advance in a storage unit (not shown) in the control unit 13.

  When the capacitor C is not short-circuited and the battery voltage Vb is equal to or higher than the second specified voltage, the capacitor voltage Vc is set after a specified time from the start of charging regardless of the value at the start of charging of the capacitor voltage Vc. The specified time, the first specified voltage, and the second specified voltage are set such that exceeds the first specified voltage.

  Accordingly, when the capacitor C is not short-circuited and is not charged at the start of charging, the conditions (A) and (B) are not satisfied, and therefore it is possible to prevent the short-circuit failure from being erroneously determined. That is, even when the capacitor C is not charged, such as immediately after the vehicle is assembled, it is possible to prevent erroneous determination of a short circuit failure.

  Furthermore, since the condition (C) is not satisfied when the battery voltage Vb is less than the second specified voltage and the capacitor C cannot be charged sufficiently, it is possible to prevent erroneous determination of a short circuit failure. That is, even if the capacitor C is not short-circuited and the battery voltage Vb is merely less than the second specified voltage and the conditions (A) and (B) are satisfied, the short-circuit failure is not erroneously determined.

  On the other hand, when the capacitor C is short-circuited, the capacitor voltage Vc is almost zero below the first specified voltage even after a specified time has elapsed since the start of charging of the capacitor C. Can be determined.

Thus, according to the present embodiment, it is possible to accurately determine whether or not the capacitor C has a short circuit failure.
In addition, it is possible to determine the presence or absence of a short fault by calculation by the control unit 13 without adding a special circuit to the existing circuit. For example, the failure determination of this embodiment can be realized only by changing the control program of the control unit 13.

  Therefore, an ECU (engine control unit) (not shown) provided in the vehicle uses the determination result to control each part of the vehicle so that, for example, an idle stop is not performed when the capacitor C is short-circuited. can do. Thereby, the state where engine 200 cannot be restarted after an idle stop can be avoided.

  As mentioned above, although embodiment of this invention was explained in full detail, a concrete structure is not limited to the said embodiment, It can implement in various deformation | transformation in the range which does not deviate from the summary of this invention.

10 Charge / Discharge Control Circuit 11 Bidirectional Buck-Boost Power Supply (Power Supply Circuit)
DESCRIPTION OF SYMBOLS 12 Detection part 13 Control part C Capacitor B Battery 20 Starter 30 Electric power generation part 100 Power supply device for vehicles

Claims (3)

A charge / discharge control circuit that has a first terminal to which a capacitor and a starter are connected, a second terminal to which a chargeable / dischargeable battery and a power generation unit are connected, and controls charge / discharge of the capacitor and the battery. ,
The starter starts an engine using electric power supplied from the capacitor via the first terminal,
The power generation unit generates power by rotation of the engine, and outputs power corresponding to the generated power to the second terminal,
Switching between a discharging state in which the capacitor voltage at the first terminal is boosted or lowered and output to the second terminal and a charging state in which the battery voltage at the second terminal is boosted or lowered and output to the first terminal are switched. Possible power circuit,
A detection unit for detecting the capacitor voltage and the battery voltage;
A control unit that switches the power supply circuit to the charged state when the charging mode is entered, starts charging the capacitor, and controls the power supply circuit so that the capacitor voltage approaches a target voltage; and
The controller is
(A) the capacitor voltage is equal to or lower than a first specified voltage;
(B) A specified time or more has elapsed from the start of charging of the capacitor, and
(C) When the battery voltage is equal to or higher than a second specified voltage higher than the first specified voltage, it is determined that a short circuit failure of the capacitor has occurred ;
The specified time, the first specified voltage, and the second specified voltage are from the start of charging when the capacitor is not short-circuited and the battery voltage is equal to or higher than the second specified voltage. The charge / discharge control circuit according to claim 1, wherein the capacitor voltage is set to exceed the first specified voltage after the specified time . A capacitor;
A chargeable / dischargeable battery;
A charge / discharge control circuit which has a first terminal to which the capacitor is connected and a second terminal to which the battery is connected, and which controls charge / discharge of the capacitor and the battery;
A starter for starting an engine using electric power supplied from the capacitor via the first terminal;
A power generation unit that generates electric power by rotating the engine and outputs electric power corresponding to the generated electric power to the second terminal,
The charge / discharge control circuit includes:
Switching between a discharging state in which the capacitor voltage at the first terminal is boosted or lowered and output to the second terminal and a charging state in which the battery voltage at the second terminal is boosted or lowered and output to the first terminal are switched. Possible power circuit,
A detection unit for detecting the capacitor voltage and the battery voltage;
A control unit that controls the power supply circuit so that the capacitor voltage approaches a target voltage by switching the power supply circuit to the charging state when charging mode is started and charging of the capacitor is started;
The controller is
(A) the capacitor voltage is equal to or lower than a first specified voltage;
(B) A specified time or more has elapsed from the start of charging of the capacitor, and
(C) When the battery voltage is equal to or higher than a second specified voltage higher than the first specified voltage, it is determined that a short circuit failure of the capacitor has occurred ;
The specified time, the first specified voltage, and the second specified voltage are from the start of charging when the capacitor is not short-circuited and the battery voltage is equal to or higher than the second specified voltage. The vehicle power supply device , wherein the capacitor voltage is set to exceed the first specified voltage after the specified time . A charge / discharge control circuit that has a first terminal to which a capacitor and a starter are connected, a second terminal to which a chargeable / dischargeable battery and a power generation unit are connected, and controls charge / discharge of the capacitor and the battery. The starter starts the engine using the electric power supplied from the capacitor via the first terminal , and the power generation unit generates electric power by rotating the engine and generates electric power according to the generated electric power. A discharge state in which the voltage is output to the second terminal, the capacitor voltage of the first terminal is boosted or stepped down and output to the second terminal, and the battery voltage of the second terminal is boosted or stepped down to the first terminal. A power supply circuit capable of switching between a charge state to be output, a detection unit for detecting the capacitor voltage and the battery voltage, and the power supply circuit is switched to the charge state when in a charge mode. Te, in failure determination method in a charging and discharging control circuit and a control unit for the capacitor voltage begins to charge the capacitor to control the power supply circuit so as to approach the target voltage,
(A) the capacitor voltage is equal to or lower than a first specified voltage;
(B) A specified time or more has elapsed from the start of charging of the capacitor, and
(C) When the battery voltage is equal to or higher than a second specified voltage higher than the first specified voltage, it is determined that a short circuit failure of the capacitor has occurred ;
The specified time, the first specified voltage, and the second specified voltage are from the start of charging when the capacitor is not short-circuited and the battery voltage is equal to or higher than the second specified voltage. The failure determination method , wherein the capacitor voltage is set to exceed the first specified voltage after the specified time .

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