JP2013091477A - Vehicle power supply device - Google Patents

Abstract

A vehicle power supply apparatus that appropriately determines deterioration of a switch that switches on / off of power supply from a capacitor to a starter.
A switch voltage acquisition unit (a control unit) for acquiring a voltage value between both ends of a switch at a predetermined time during power supply from a capacitor to a starter, a capacitor voltage detection unit for detecting a capacitor voltage, The falling speed calculating means (control unit 9) for calculating the falling speed of the capacitor voltage detected by the capacitor voltage detecting means 11 during the period including the predetermined time point, the capacitance of the capacitor 1, and the calculated falling speed of the capacitor voltage. Based on the current calculation means (control unit 9) for calculating the current value flowing through the switch, the resistance calculation means (control) for calculating the on-resistance of the switch based on the acquired voltage value at both ends and the calculated current value. Unit 9) and determination means (control unit 9) for determining whether or not the calculated on-resistance exceeds a predetermined value.
[Selection] Figure 1

Description

  The present invention relates to a vehicle power supply device that determines deterioration of a switch that switches on / off of a large current flow.

  The starter provided in the vehicle is used every time the engine is started. However, in particular, in a vehicle having an idle stop function, the starter is frequently used because the engine is started from the idle stop. Therefore, when power is supplied to the starter by the lead storage battery, the deterioration of the lead storage battery proceeds due to repeated charge and discharge.

  Therefore, in the vehicle power supply device described in Patent Document 1, a lead storage battery (main power supply) and a capacitor (power storage unit) are used in combination. In Patent Document 1, power is supplied from a lead storage battery to a starter only at the start of use of the vehicle. While the engine is rotating, the power generated by the generator is stored in the capacitor when the vehicle decelerates. When the vehicle starts the engine from the idle stop, the power stored in the capacitor is supplied to the starter. To do.

JP 2010-63330 A

  However, in the vehicle power supply device described in Patent Document 1, a large current flows through the switch provided between the capacitor and the starter at least every time the engine is started from the idle stop. It is remarkable. If a large current is passed in a state where the switch has deteriorated, the switch may break down and cannot be disconnected from the conducting state, or may not be able to conduct due to poor contact.

  This invention is made in view of such a situation, and it aims at providing the power supply device for vehicles which can determine appropriately deterioration of the switch which switches on / off of the electric power supply from a capacitor to a starter. To do.

  A vehicle power supply apparatus according to the present invention includes a capacitor that stores electric power from a generator provided in the vehicle, and a switch provided between the capacitor and a starter that is supplied with electric power from the capacitor. In the power supply device for a switch, a switch voltage acquisition unit that acquires a voltage value across the switch at a predetermined time point during power supply from the capacitor to the starter, a capacitor voltage detection unit that detects a capacitor voltage of the capacitor, and the predetermined A falling speed calculating means for calculating a falling speed of the capacitor voltage detected by the capacitor voltage detecting means in a period including a time point; a capacitance of the capacitor; and a falling speed of the capacitor voltage calculated by the falling speed calculating means. Current calculating means for calculating a current value flowing through the switch, and the switch Based on the both-ends voltage value acquired by the pressure acquisition means and the current value calculated by the current calculation means, the resistance calculation means for calculating the on-resistance of the switch, and the on-resistance calculated by the resistance calculation means is a predetermined value. And determining means for determining whether or not the number exceeds.

  In the present invention, the on-resistance of the switch is calculated from the voltage value at both ends of the switch and the current value flowing through the switch based on the capacitance of the capacitor and the decreasing speed of the capacitor voltage. Thus, since the deterioration of the switch is determined, it is possible to appropriately determine the deterioration of the switch that switches on / off the power supply from the capacitor to the starter.

  Further, in the vehicle power supply device according to the present invention, the switch voltage acquisition means is configured to acquire voltage values across the switch at a plurality of time points during power supply from the capacitor to the starter, An average calculating means for calculating an average of a plurality of voltage values at both ends detected by the switch voltage acquisition means, and the resistance calculating means uses the average of the voltage values at both ends calculated by the average calculating means, The on-resistance is calculated.

  In the present invention, the average of the voltage values at both ends of the switch at a plurality of time points is calculated, and the calculated average of the voltage values at both ends is used to calculate the on-resistance. Thereby, the on-resistance can be calculated with higher accuracy.

  The vehicle power supply device according to the present invention includes a DC / DC converter connected between the generator and the capacitor and charging the capacitor with a constant current value, and a rising speed of the capacitor voltage during the charging of the capacitor. A rising speed calculating means for calculating; and a capacitance calculating means for calculating a capacitance of the capacitor based on the constant current value and the rising speed of the capacitor voltage measured by the rising speed calculating means. It is characterized by providing.

  In the present invention, a DC / DC converter is used for charging the capacitor, and the rising speed of the charging voltage when the capacitor is charged with a constant current value is calculated, and the capacitance of the capacitor is calculated based on the calculated rising speed. Is calculated. Thereby, even when the capacitance is changed due to the deterioration of the capacitor, the on-resistance of the switch is calculated based on the changed capacitance, so that the on-resistance can be calculated with high accuracy.

  The vehicle power supply apparatus according to the present invention further includes signal output means for outputting a predetermined signal when the determination means determines that the on-resistance calculated by the resistance calculation means exceeds a predetermined value. It is characterized by that.

  In the present invention, when the determination unit determines that the on-resistance exceeds a predetermined value, a predetermined signal is output. Thereby, when the switch is deteriorated, it is possible to notify the user or the related device that the switch is deteriorated.

  ADVANTAGE OF THE INVENTION According to this invention, the vehicle power supply device which can determine appropriately deterioration of the switch which switches on / off of the electric power supply from a capacitor to a starter can be provided.

It is a block diagram which shows the principal part structure of embodiment of the power supply device for vehicles which concerns on this invention. It is a flowchart which shows the example of the process which determines deterioration of a switch. It is a flowchart which shows the example of the process which determines deterioration of a switch. It is a block diagram which shows the principal part structure of embodiment of the power supply device for vehicles which concerns on this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing a main configuration of an embodiment of a vehicle power supply device according to the present invention. Each part shown in FIG. 1 is mounted on a vehicle. FIG. 1 shows a vehicle power supply device 10, a switch 3, a battery 5, a load group 6, a vehicle control unit 8, a starter 21, a generator 22, and an engine 23. The vehicle power supply device 10 includes a capacitor 1, a switch 2, a DC / DC converter 4, and a control unit 9.

  The negative terminal of the capacitor 1 is grounded, and the positive terminal is connected to the positive terminal of the starter 21 through the switch 2. The positive terminal of the capacitor 1 is further connected to one terminal of the DC / DC converter 4, and the other terminal of the DC / DC converter 4 is connected to the positive terminal of the battery 5.

  The positive electrode of the battery 5 is connected to the positive terminal of the starter 21 through the switch 3. The positive electrode of the battery 5 is further connected to the positive electrode terminal of the generator 22 and the positive electrode terminal of each load 61 included in the load group 6. The negative electrode of the battery 5, the negative electrode terminal of the generator 22, and the negative electrode terminal of the load 61 are grounded. The generator 22 and the starter 21 are interlocked with the engine 23.

  The voltmeter 11 detects the charge voltage value (or discharge voltage value) V1 of the capacitor 1. The voltmeter 12 detects the voltage value V2 across the switch 2.

  The controller 9 is supplied with the charging voltage value V1 and the both-ends voltage value V2 from the voltmeter 11 and the voltmeter 12, respectively. The controller 9 is also provided with an ignition key signal, an engine ECU signal, a brake operation signal, and a vehicle speed signal. The ignition key signal indicates ON / OFF of the ignition key. The engine ECU signal indicates the start of the engine and whether or not the engine is rotating. The brake operation signal indicates that the brake is operated by the driver. These signals are given from an ECU (not shown). The vehicle speed signal is given from a sensor (not shown) and indicates a vehicle speed value when the vehicle is running.

  2 and 3 are flowcharts illustrating an example of processing for determining deterioration of the switch 2. The processing of FIGS. 2 and 3 is executed by the control unit 9. The process of FIG. 2 starts from a state where the vehicle is parked and the ignition key is turned off. First, the control unit 9 determines whether or not the start of the engine 23 by the ignition key-on has been started (step S11). That is, it is determined whether or not the value of the ignition key signal is ON and the value of the engine ECU signal is the start of starting the engine 23. If the engine 23 has not started due to the ignition key being turned on (step S11: NO), step S11 is repeated.

  On the other hand, when starting of the engine 23 is started by turning on the ignition key (step S11: YES), the control unit 9 turns on the switch 3 and starts supplying power from the battery 5 to the starter 21 (step S12).

  Subsequently, the control unit 9 determines whether or not the engine 23 has been started (step S13). That is, it is determined whether or not the value of the engine ECU signal indicates that the engine 23 is rotating. If the engine 23 has not been started (step S13: NO), step S13 is repeated. When the start of the engine 23 is completed (step S13: YES), the switch 3 is turned off and the power supply from the battery 5 to the starter 21 is stopped (step S14).

  The regenerative power is supplied from the generator 22 to the DC / DC converter 4 when the driver operates the brake while the vehicle is traveling. The control unit 9 instructs the DC / DC converter 4 to output the power supplied from the generator 22 to the capacitor 1 with the current value I1, resets the time t to 0, and starts timing. (Step S21). Accordingly, the brake is activated while the vehicle is traveling, and the regenerative power generated by the generator 22 can be stored in the capacitor 1.

  Subsequently, the control unit 9 calculates the rate of increase (dV1 / dt1) of the charging voltage value V1 of the capacitor 1 during the period including the predetermined time point t1 (step S22). The predetermined time point t1 is a certain time point in the period in which the DC / DC converter 4 continuously supplies power to the capacitor 1. The rising speed is calculated, for example, by dividing the difference between the charging voltage values V1 at two time points by the time between the two time points.

  Subsequently, the capacitance C of the capacitor 1 is calculated by the following equation (1) (step S23).

C = I1 / (dV1 / dt1) (1)
Where C is the capacitance of the capacitor 1,
I1 is a current value of power supplied from the DC / DC converter 4 to the capacitor 1,
V1 is a charging voltage value of the capacitor 1.

  Subsequently, the control unit 9 determines whether or not V1 exceeds a predetermined value (step S24). The predetermined value is a charging voltage value when the capacitor 1 finishes storing power. When V1 does not exceed the predetermined value (step S24: NO), the process returns to step S22 and is repeated. On the other hand, if V1 exceeds the predetermined value (step S24: YES), it is determined whether or not the ignition key is turned off (step S25). That is, it is determined whether or not the value of the ignition key signal is off.

  The control part 9 complete | finishes a process, when an ignition key is turned off (step S25: YES). On the other hand, when the ignition key is not turned off (step S25: NO), it is determined whether or not the engine 23 is started from the idle stop (step S26). That is, when the value of the ignition key signal continues to be on, it is determined whether or not the value of the engine ECU signal is a value for starting the engine 23. If the engine 23 has not been started (step S26: NO), step S26 is repeated.

  When the engine 23 is started from the idle stop (step S26: YES), the controller 9 turns on the switch 2, starts supplying power from the capacitor 1 to the starter 21, and resets the time t to 0. Then, time measurement is started (step S27).

  Subsequently, the voltage value V2 across the switch 2 at a predetermined time t2 is acquired (step S28). The predetermined time point t2 may be included in a period in which a sudden change in the both-end voltage value V2 due to the inrush current at the start of the starter 21 has converged. Further, at a plurality of time points t2, the both-end voltage value V2 is obtained, an average thereof is obtained, and the average obtained when calculating the on-resistance R described later can be used to improve the accuracy. Subsequently, it is determined whether or not the both-end voltage value V2 exceeds the second predetermined value (step S29). The second predetermined value is determined by estimating a potential difference generated at both ends of the switch 2 when it is estimated that the on-resistance of the switch 2 exceeds the predetermined value.

  When the both-end voltage value V2 exceeds the second predetermined value (step S29: YES), the capacitor 1 in a period including a predetermined time point t2 when it is determined that the both-end voltage value V2 exceeds the second predetermined value. The descending speed (dV1 / dt2) of the discharge voltage value V1 is calculated (step S30). More specifically, for example, the V1 value at each predetermined time point t2 is stored in a storage unit (not shown), and the both-end voltage value V2 determined to exceed the second predetermined value in step S29 is acquired. The descending speed (dV1 / dt2) is calculated from a plurality of discharge voltage values V1 acquired in a period including The descending speed may be an average value of the obtained plurality of discharge voltage values V1.

  Subsequently, the on-resistance R of the switch 2 is calculated by the following equations (2) and (3) (step S31).

I2 = C × (dV1 / dt2) (2)
R = V2 / I2 (3)
However, V1 is the discharge voltage value of the capacitor 1,
(DV1 / dt2) is a rate of decrease in the discharge voltage value of the capacitor 1 during a period including the predetermined time point t2.
C is the capacitance of the capacitor 1,
I2 is a current value flowing through the switch 2 at a predetermined time point t2,
V2 is a voltage across the switch 2 at a predetermined time t2,
R is the on-resistance.

  Subsequently, it is determined whether or not the on-resistance R exceeds a third predetermined value (step S32). If the on-resistance R exceeds the third predetermined value (step S32: YES), a signal indicating that the switch 2 has deteriorated is output to the vehicle control unit 8 (step S33).

  Based on this signal, the vehicle control unit 8 displays, for example, a notification that the switch has deteriorated on a display device provided on an instrument panel (not shown) or turns on an LED (not shown). And so on. For example, the vehicle control unit 8 outputs a signal for prohibiting idle stop to an idle stop ECU (not shown). The vehicle control unit 8 also supplies power to the starter 21 by supplying the battery to the control unit 9 by turning off the switch 2 and turning on the switch 3 when starting the engine 23 from the idle stop. 5 is output.

  When the both-end voltage value V2 does not exceed the second predetermined value (step S29: NO), the on-resistance R calculated at step S31 does not exceed the third predetermined value (step S32: NO), or step S33. After that, the process proceeds to step S34. The controller 9 determines whether or not the engine start from the idle stop has ended (step S34). That is, the value of the engine ECU signal determines whether or not the engine is rotating.

  If the engine has been started (step S34: YES), the process returns to step S21 and the process is repeated. On the other hand, if the engine has not been started (step S34: NO), the process returns to step S28 and the process is repeated.

  FIG. 4 is a block diagram showing a configuration of a main part of the embodiment of the vehicle power supply device according to the present invention. In the configuration of FIG. 4, a vehicle power supply device 10 a is provided instead of the vehicle power supply device 10 of FIG. 1, and a voltmeter 32 is provided instead of the voltmeter 12. The vehicle power supply device 10 a is provided with a control unit 9 a instead of the control unit 9. Others are the same as the structure of FIG. Here, the control unit 9a and the voltmeter 32 will be mainly described.

  The voltmeter 11 measures the charge voltage value (or discharge voltage value) V1 of the capacitor 1, and the voltmeter 32 measures the voltage value V4 of the starter side terminal of the switch 2. The charging voltage value V1 and the voltage value V4 are given to the control unit 9a. The controller 9a is also given an ignition key signal, an engine ECU signal, a brake operation signal, and a vehicle speed signal. The ignition key signal indicates ON / OFF of the ignition key. The engine ECU signal indicates the start of the engine and whether or not the engine is rotating. The brake operation signal indicates that the brake is operated by the driver. These signals are given from an ECU (not shown). The vehicle speed signal is given from a sensor (not shown) and indicates a vehicle speed value when the vehicle is running.

  The process of determining the deterioration of the switch 2 performed by the control unit 9a is almost the same as that in FIGS. More specifically, the difference value between the voltage value V4 and the discharge voltage value V1 is used as the voltage value V2 across the switch 2. For this reason, the control part 9a performs calculation of V2 = (V4-V1).

  As mentioned above, although the form for inventing was demonstrated, this invention is not limited to embodiment described in the form for implementing this invention. Modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Capacitor 2, 3 Switch 4 DC / DC converter 5 Battery 6 Load group 8 Vehicle control part 9, 9a Control part (Switch voltage acquisition means, descent speed calculation means, current calculation means, resistance calculation means, determination means, average calculation means , Rising speed calculation means, capacitance calculation means, signal output means)
11 Voltmeter (Capacitor voltage detection means)
12 Voltmeter 21 Starter 22 Generator 23 Engine 32 Voltmeter 61 Load

Claims (4)

In a vehicle power supply device including a capacitor for storing electric power from a generator provided in a vehicle, and a switch provided between the capacitor and a starter supplied with electric power from the capacitor,
Switch voltage acquisition means for acquiring a voltage value across the switch at a predetermined time during power supply from the capacitor to the starter;
Capacitor voltage detecting means for detecting a capacitor voltage of the capacitor;
A falling speed calculating means for calculating a falling speed of the capacitor voltage detected by the capacitor voltage detecting means in a period including the predetermined time point;
Current calculating means for calculating a current value flowing through the switch based on the capacitance of the capacitor and the falling speed of the capacitor voltage calculated by the falling speed calculating means;
Resistance calculation means for calculating the on-resistance of the switch based on the both-end voltage value acquired by the switch voltage acquisition means and the current value calculated by the current calculation means;
A vehicle power supply apparatus comprising: determination means for determining whether or not the on-resistance calculated by the resistance calculation means exceeds a predetermined value. The switch voltage acquisition means is configured to acquire voltage values across the switch at a plurality of points during power supply from the capacitor to the starter,
Average calculating means for calculating an average of a plurality of voltage values detected by the switch voltage acquisition means;
2. The vehicle power supply according to claim 1, wherein the resistance calculation unit is configured to calculate an on-resistance of the switch using an average of both-end voltage values calculated by the average calculation unit. apparatus. A DC / DC converter connected between the generator and the capacitor and charging the capacitor with a constant current value;
A rising speed calculating means for calculating a rising speed of the capacitor voltage during charging of the capacitor;
The electrostatic capacity calculating means for calculating the electrostatic capacity of the capacitor based on the constant current value and the rising speed of the capacitor voltage measured by the rising speed calculating means. The vehicle power supply device according to 1 or 2.   4. The signal output means according to claim 1, further comprising a signal output means for outputting a predetermined signal when the determination means determines that the on-resistance calculated by the resistance calculation means exceeds a predetermined value. The vehicle power supply device according to claim 1.

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