JP4572774B2 - Vehicle power supply - Google Patents

Description

  The present invention relates to a vehicle power supply device, and more particularly to a vehicle power supply device mounted on an idle stop vehicle that temporarily automatically stops an engine when the vehicle is stopped due to a signal or the like.

  In recent years, for the purpose of reducing fuel consumption and emission, idle stop vehicles have been put into practical use in which the engine is automatically stopped temporarily when the vehicle is stopped, such as when waiting for a signal. In this type of vehicle, based on predetermined idle determination information such as vehicle speed and accelerator opening, the engine is automatically stopped when the vehicle is estimated to be stopped, and then an engine start condition that represents the driver's intention to start When is established, the engine is automatically started by a starter to prepare for starting.

  Here, since the starter for starting the engine generally consumes a considerable amount of electric power, especially in urban areas where the vehicle is frequently stopped and started, consumption of the battery serving as a power source increases as the engine starts more frequently. .

  If the battery voltage temporarily decreases significantly during engine cranking due to battery consumption, the battery voltage to the electrical load that drives the battery as a power source decreases. For example, the illumination of the instruments in the vehicle temporarily becomes dark, and the quality of the vehicle is greatly impaired. Further, in a car audio or car navigation system, there is a possibility that a sound interruption or the like may occur due to a reset of a built-in CPU (Central Processing Unit).

  In order to solve such various problems of the electric load, for example, Japanese Patent Application Laid-Open No. 2002-38984 discloses that the battery voltage is supplied to the electric load when the battery voltage is reduced when the engine is restarted after the idle stop. An idle stop vehicle comprising voltage compensation means for compensating is disclosed.

According to this, when the engine is automatically stopped by the idle stop and then the engine is restarted by the starter, when the battery voltage falls below the set value, the voltage compensation means is activated and the battery voltage is applied to the electric load. Compensate for supply. More specifically, the voltage compensation means includes a voltage compensation circuit including a booster circuit and a voltage compensation controller that controls the voltage compensation circuit. In this configuration, the voltage compensation controller controls the voltage compensation circuit so that the voltage applied to the electric load exceeds the minimum operating voltage of the electric load when the battery voltage drops below the set value. Accordingly, the voltage compensation circuit boosts the battery voltage as the input voltage and supplies the boosted output voltage to the electric load.
JP 2002-38984 A JP 2004-229477 A

  However, in the idle stop vehicle according to Patent Document 1, when a failure of a circuit element such as a switch included in the voltage compensation circuit or a failure of the voltage compensation controller occurs, the boost operation cannot be performed normally, and the voltage The output voltage of the compensation circuit will drop at once. As a result, the voltage compensation means cannot compensate the supply of the load driving voltage for driving the electric load, and the driving state of the electric load becomes unstable.

  However, since the conventional idle stop vehicle does not have a means for diagnosing the failure of the voltage compensation means prior to restarting the engine, the failure of the voltage compensation means can be performed by actually restarting the engine. This is the first time it is detected.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a vehicle power supply device that can reliably drive an electric load.

  According to the present invention, a vehicle power supply device includes a power supply that supplies a power supply voltage to an engine starting motor, and a load drive voltage that is supplied with the power supply voltage from the power supply and drives an electric load from the received power supply voltage. And a voltage supply circuit that supplies the generated load drive voltage to the electric load, and supplies a boosted voltage obtained by boosting the power supply voltage as the load drive voltage when the power supply voltage is within a predetermined range. A control circuit for controlling the circuit, and an engine automatic stop control circuit for automatically controlling engine stop and engine restart by the engine start motor according to the state of the vehicle. The control circuit includes an operation confirmation unit that confirms whether or not the voltage boosting operation in the voltage supply circuit can be normally executed. The engine automatic stop control circuit executes automatic control for restarting the engine in response to determining that the boosting operation can be normally performed.

  Preferably, the engine automatic stop control circuit prohibits automatic control for stopping and restarting the engine when it is determined that the boosting operation cannot be normally performed.

  According to the above vehicle power supply device, since the engine is automatically started in response to the confirmation of the normality of the voltage supply circuit, the drive of the electric load can be reliably maintained even when the engine is restarted. it can.

  Preferably, the voltage supply circuit includes step-down means for generating a load drive voltage obtained by stepping down the power supply voltage by a predetermined voltage. The control circuit causes the voltage supply circuit to perform a boost operation so as to compensate for the predetermined voltage. The operation confirmation unit determines that the boosting operation can be normally performed based on the voltage difference between the power supply voltage and the load drive voltage being equal to or less than a predetermined value.

  According to the vehicle power supply device described above, whether or not the boosting operation can be normally performed is determined by causing the included booster circuit to perform the same operation as the actual boosting operation. Can be accurately confirmed, and the reliability of the vehicle power supply device can be improved.

  Preferably, the step-down means sets the predetermined voltage so that the generated load drive voltage does not fall below the lower limit of the operating voltage of the electric load.

  According to the above-described vehicle power supply device, the electric load can be stably driven even while the operation of the voltage supply circuit is being confirmed.

  Preferably, the step-down means is connected between a first voltage detection circuit for detecting a power supply voltage and a second voltage detection circuit for detecting a load drive voltage, and in response to an instruction from the operation confirmation means, A load driving voltage is generated by reducing the voltage by a predetermined voltage.

  According to the above-described vehicle power supply device, the operation confirmation unit can cause the booster circuit to perform the same operation as the actual boosting operation.

  Preferably, the voltage step-down means includes a diode element included in the voltage supply circuit and having an anode connected to the first voltage detection circuit side and a cathode connected to the second voltage detection circuit side. The diode element generates a load drive voltage obtained by stepping down the power supply voltage by a forward voltage in response to an instruction from the operation confirmation unit.

  According to the above-described vehicle power supply device, it is not necessary to add a new device for confirming the operation. Therefore, the operation of the voltage supply circuit can be confirmed with a simple and low-cost device configuration. In addition, since the forward voltage of the diode element is sufficiently small with respect to the power supply voltage, the electric load can be driven stably even while the operation check means is being executed.

  Preferably, the step-down means includes a field effect transistor connected in series between the output terminal of the voltage supply circuit and the second voltage detection circuit. The field effect transistor operates in a linear region in response to the gate potential indicated by the operation confirmation means.

  According to the above-described vehicle power supply device, the power supply voltage can be easily lowered by operating the field effect transistor in the linear region.

  Preferably, the field effect transistor constitutes a switch element connected in series between the output terminal of the voltage supply circuit and a predetermined electrical load selected in advance. The control circuit makes the switch element nonconductive in response to the power supply voltage falling below a predetermined range, and cuts off the supply of the load drive voltage to the predetermined electric load.

  According to the above-described vehicle power supply device, the operation of the voltage supply circuit can be confirmed with a simple and low-cost device configuration by using the switching element provided for ensuring the operation of the idle stop vehicle as the step-down means. it can.

  Preferably, the operation confirmation unit confirms whether or not the voltage boosting operation in the voltage supply circuit can be normally executed in response to the engine being stopped.

  Preferably, the operation confirming unit confirms whether or not the boosting operation in the voltage supply circuit can be normally executed in response to the engine stop condition being satisfied.

  Preferably, the operation confirming unit confirms whether or not the voltage boosting operation in the voltage supply circuit can be normally performed at predetermined time intervals.

  According to the above vehicle power supply device, the operation of the voltage supply device can be confirmed prior to the timing of restarting the engine after the idle stop.

  According to the present invention, since the engine is automatically started in response to the confirmation of the normality of the drive voltage supply device, the electric load can be reliably maintained even when the engine is restarted.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.

[Embodiment 1]
1 is a schematic block diagram of a vehicle power supply device mounted on an automobile according to Embodiment 1 of the present invention.

  Referring to FIG. 1, a vehicle power supply device 100 includes a DC power supply B, a drive voltage supply device 10, an alternator 20, a starter 30, an electric load 40, an idle stop ECU 50, and an EFI (Electronic Fuel Injection). A control unit 60 and an LED (Light-Emitting Diode) 70 are provided.

  The drive voltage supply device 10, the alternator 20, the starter 30 and the EFI control unit 60 are connected to the power supply line 9 of the DC power supply B. The electrical load 40 is connected to the drive voltage supply device 10.

  The DC power source B is made of, for example, a lead battery. Drive voltage supply device 10 receives power supply voltage VB from power supply line 9 of DC power supply B, and generates load drive voltage VDL based on the received power supply voltage VB. Then, the generated load drive voltage VDL is supplied to the electric load 40. That is, in FIG. 1, the power supply voltage VB corresponds to the input voltage VIN of the drive voltage supply device 10, and the load drive voltage VDL corresponds to the output voltage VOUT of the drive voltage supply device 10.

  Alternator 20 receives power supply voltage VB from DC power supply B, and supplies the received power supply voltage VB to a built-in rotor to generate a magnetic field. The alternator 20 receives power from an engine (not shown), rotates the rotor with the received power, and induces AC power in a stator provided around the rotor. Further, the alternator 20 rectifies the induced AC power by the built-in diode and converts it into DC power, and supplies the converted DC power to the DC power source B to charge the DC power source B.

  Starter 30 receives power supply voltage VB from DC power supply B, and is driven by the received power supply voltage VB. Starter 30 then starts the engine in accordance with control from idle stop ECU 50.

The EFI control unit 60 controls fuel supply to the engine.
The electrical load 40 includes an audio / navigation 44 and a meter 46, both connected to the output of the drive voltage supply device 10.

  The audio / navigation 44 receives the load drive voltage VDL from the drive voltage supply device 10 and is driven by the received load drive voltage VDL. Thus, the driver can enjoy music and execute the navigation system.

The meter 46 is driven by receiving the load drive voltage VDL from the drive voltage supply device 10.
When it is determined that the engine stop condition is satisfied, the idle stop ECU 50 generates a signal EST for controlling the stop of the engine, and outputs the generated signal EST to the EFI control unit 60. Further, the idle stop ECU 50 generates a stop signal STOP indicating that the engine has stopped, and outputs the generated stop signal STOP to the drive voltage supply device 10.

  When drive voltage supply device 10 receives stop signal STOP from idle stop ECU 50, drive voltage supply device 10 performs an operation check as to whether or not the boosting operation is normally performed according to a method described later. At this time, if it is determined that the boosting operation is abnormal, the drive voltage supply device 10 generates a warning signal WARN for notifying the driver of the abnormality of the boosting operation, and sends the generated warning signal WARN to the idle stop ECU 50. Output. The idle stop ECU 50 turns on the LED 70 in response to the warning signal WARN. The notification to the driver may be performed by other methods.

  When it is determined that the engine restart condition is satisfied after the engine is stopped, the idle stop ECU 50 generates a signal STAR for controlling the restart of the engine, and outputs the generated signal STAR to the starter 30. To do. Thereby, the starter 30 restarts the engine.

  The engine stop condition of the idle stop vehicle is, for example, that the remaining capacity of the DC power supply B is a predetermined value or more, that there is a vehicle speed history indicating that the vehicle has traveled a certain distance, and that the vehicle travels uphill. If it is, it is to confirm that the climb is a climb within a predetermined angle. The engine restart condition after the idle stop is, for example, confirming that the brake pedal is turned off and that the accelerator is turned on. However, the engine stop condition and the engine restart condition are not limited to the above-described conditions, and known conditions may be added as needed.

  In this way, the drive voltage supply device 10 receives the power supply voltage VB from the DC power supply B electrically connected to the alternator 20 that is a generator and the starter 30 that is a large power load.

  FIG. 2 is a block diagram for explaining the configuration of the drive voltage supply apparatus 10 in FIG.

  Referring to FIG. 2, drive voltage supply apparatus 10 includes a booster circuit 110, switch drive circuits 12 and 14, voltage detection circuits 16 and 18, and control circuit 120.

  Boost circuit 110 includes capacitors C1 and C2, a coil L1, MOS transistors Q1 and Q2, and diodes D1 and D2.

  Capacitor C1 is connected between power supply line 9 of DC power supply B and the ground line. One end of the coil L1 is connected to the power supply line 9, and the other end is connected to an intermediate point between the MOS transistor Q1 and the MOS transistor Q2, that is, between the drain of the MOS transistor Q1 and the source of the MOS transistor Q2. The source of the MOS transistor Q1 is connected to the ground line, and the collector of the MOS transistor Q2 is connected to the power supply line 9. Also, diodes D1 and D2 that flow current from the source side to the drain side are connected between the drain and source of the MOS transistors Q1 and Q2. MOS transistors Q1 and Q2 constitute a switching element according to the present invention. The switch element may be composed of a field effect transistor or a junction transistor other than the MOS transistor.

  The booster circuit 110 boosts the power supply voltage VB (corresponding to the input voltage VIN) supplied from the DC power supply B via the capacitor C1, and supplies the boosted output voltage VOUT to the electric load 40 (not shown).

  More specifically, the capacitor C1 smoothes the power supply voltage VB supplied from the DC power supply B, and applies the smoothed power supply voltage VB to the intermediate point between the MOS transistor Q1 and the MOS transistor Q2 via the coil L1. Supply.

  MOS transistors Q1 and Q2 have switch drive circuits 12 and 14 connected to their gates, respectively. Switch drive circuits 12 and 14 receive signals PWM1 and PWM2 for controlling switching of MOS transistors Q1 and Q2 from control circuit 120, respectively. The switch drive circuits 12 and 14 control the gate potentials of the corresponding transistors so that the MOS transistors Q1 and Q2 are turned on / off according to the signals PWM1 and PWM2, respectively. As a result, the input voltage VIN is boosted according to the period during which the MOS transistor Q1 is turned on by the signal PWM1 and supplied to the capacitor C2.

  The capacitor C2 smoothes the boosted input voltage VIN and supplies the smoothed input voltage VIN to the electric load 40 as the output voltage VOUT.

  The voltage detection circuit 16 detects the input voltage VIN (corresponding to the input voltage of the booster circuit 110) of the drive voltage supply device 10, and outputs the detected input voltage VIN to the control circuit 120. The voltage detection circuit 18 detects the output voltage VOUT of the drive voltage supply device 10 (corresponding to the output voltage of the booster circuit 110), and outputs the detected output voltage VOUT to the control circuit 120.

  Control circuit 120 receives input voltage VIN from voltage detection circuit 16 and receives output voltage VOUT from voltage detection circuit 18. Based on the input voltage VIN and the output voltage VOUT, the control circuit 120 generates signals PWM1 and PWM2 for switching control of the MOS transistors Q1 and Q2 by a method to be described later, and outputs them to the switch drive circuits 12 and 14, respectively. To do.

  Furthermore, the control circuit 120 receives a stop signal STOP indicating that the engine has stopped from the idle stop ECU 50. Then, in response to the stop signal STOP, the control circuit 120 confirms the normality of the boosting operation in the boosting circuit 110 by a method described later. At this time, if it is determined that the boosting operation is abnormal, the control circuit 120 generates a warning signal WARN and outputs it to the idle stop ECU 50.

FIG. 3 is a functional block diagram of the control circuit 120 in FIG.
Referring to FIG. 3, control circuit 120 includes a switching control unit 122 and an operation confirmation unit 124.

  The switching control unit 122 generates signals PWM1 and PWM2 based on the input voltage VIN and the output voltage VOUT, and outputs them to the switch drive circuits 12 and 14, respectively.

  More specifically, the switching control unit 122 turns on the MOS transistor Q2 based on the magnitude relationship between the power supply voltage VB as the input voltage VIN and the voltages VIN1 and VIN2 set in advance based on the load drive voltage VDL. Duty D_ON_2 is calculated. Voltage VIN2 is set to about power supply voltage VB (for example, 12V) of DC power supply B during normal operation. Voltage VIN1 is set to a level (for example, 6 to 7V) that is lower than a limit value (hereinafter also referred to as an operating voltage lower limit value, for example, 8V) of load drive voltage VDL that ensures normal operation of electric load 40.

  For example, when the input voltage VIN exceeds the voltage VIN2, the switching control unit 122 sets the target value of the output voltage VOUT, that is, the voltage command value Vdc_com of the booster circuit 110 to the same voltage as the input voltage VIN. Then, the switching control unit 122 calculates the on-duty D_ON_2 of the MOS transistor Q2 based on the input voltage VIN and the voltage command value Vdc_com according to Expression (1).

D_ON_2 = VIN / Vdc_com (1)
At this time, since the voltage command value Vdc_com is equal to the input voltage VIN, the on-duty D_ON_2 is 100%. Further, the ON duty D_ON_1 (= 1−D_ON_2) of the MOS transistor Q1 is 0%. Therefore, the switching control unit 122 generates the signals PWM1 and PWM2 for keeping the MOS transistor Q2 on and the MOS transistor Q1 off, and the generated signals PWM1 and PWM2 to the switch drive circuits 12 and 14, respectively. Output. As a result, the booster circuit 110 outputs the input voltage VIN as it is as the output voltage VOUT without performing the boosting operation.

  On the other hand, when the input voltage VIN is within the range from the voltage VIN1 to the voltage VIN2, the switching control unit 122 sets the voltage command value Vdc_com to the constant voltage Vc. The constant voltage Vc at this time is set to about the power supply voltage VB (for example, 12 V) of the DC power supply B during normal operation. Then, the switching control unit 122 calculates the on-duty D_ON_2 of the MOS transistor Q2 according to the equation (1), and calculates a duty ratio that is a ratio of this to the on-duty D_ON_1 of the MOS transistor Q2. Then, the switching control unit 122 generates signals PWM1 and PWM2 for turning on / off the MOS transistors Q1 and Q2 based on the calculated duty ratio, and the generated signals PWM1 and PWM2 are used as the switch drive circuits 12 and 14. To each output.

  Further, when the switching control unit 122 receives the output voltage VOUT from the voltage detection circuit 18, the switching control unit 122 calculates a deviation Vdc_com-VOUT between the voltage command value Vdc_com and the output voltage VOUT so that the calculated deviation Vdc_com-VOUT becomes zero. Calculate the duty ratio. Thus, the switching control unit 122 performs feedback control using the input voltage VIN and the output voltage VOUT.

  When the input voltage VIN is lower than the voltage VIN1, the switching control unit 122 sets the voltage command value Vdc_com to the same voltage as the input voltage VIN. Then, the switching control unit 122 generates signals PWM1 and PWM2 for continuously turning on the MOS transistor Q2 and continuing to turn off the MOS transistor Q1, and the generated signals PWM1 and PWM2 to the switch drive circuits 12 and 14, respectively. Output. As a result, the booster circuit 110 outputs the input voltage VIN as it is as the output voltage VOUT without performing the boosting operation.

  FIG. 4 is a diagram for schematically explaining input / output characteristics of the drive voltage supply device 10 during normal operation.

  During normal operation, the drive voltage supply device 10 receives the power supply voltage VB from the DC power supply B as the input voltage VIN and generates the load drive voltage VDL based on the received input voltage VIN, as described above. The load driving voltage VDL thus supplied is supplied to the electric load 40 as the output voltage VOUT.

  At this time, when the power supply voltage VB as the input voltage VIN decreases from the voltage VIN2 to the voltage VIN1, the booster circuit 110 boosts the decreased power supply voltage VB to generate a constant voltage Vc as the output voltage VOUT.

  That is, the booster circuit 110 outputs the input voltage VIN as it is as the output voltage VOUT when the power supply voltage VB as the input voltage VIN is in the range of 0V to the voltage VIN1 and is equal to or higher than the voltage VIN2, and the input voltage VIN is When the voltage is in the range of VIN1 to VIN2, the input voltage VIN is boosted, and the boosted output voltage Vc is output. Thus, even when the power supply voltage VB drops from 12 V to 6 V, for example, when the engine is restarted, the output voltage VOUT boosted to the constant voltage Vc is supplied to the electric load 40. The driving of the load driving voltage VDL is compensated and the driving can be continued.

  However, when the boosting operation of the booster circuit 110 is not normally performed due to the failure of at least one of the booster circuit 110, the switch drive circuits 12, 14 and the voltage detection circuits 16, 18, the engine is restarted. Thus, even if the power supply voltage VB is significantly reduced, the drive voltage supply device 10 cannot compensate for the supply of the load drive voltage VDL. Therefore, it becomes difficult for the electric load 40 to continue to be driven normally.

  For example, in the audio / navigation 44, sound interruption occurs when the built-in CPU is reset. Moreover, in the meter 46, the illumination of a display part will become dark temporarily.

  Therefore, as a means for avoiding such a problem of the electric load 40, the vehicle power supply device 100 according to the present invention performs the boosting operation of the drive voltage supply device 10 prior to the timing of restarting the engine after the idle stop. An operation confirmation means for confirming normality is provided. Then, vehicle power supply device 100 continues the idle stop control in response to the normality of the boosting operation being confirmed by the operation confirming means. According to this, even if the engine is restarted, the driving of the electric load 40 is reliably maintained.

  Specifically, referring to control circuit 120 in FIG. 3, operation confirming unit 124 performs operation confirmation of the boost operation when receiving stop signal STOP from idle stop ECU 50 in response to the engine being stopped. A signal OP is generated, and the generated signal OP is output to the switching control unit 122.

  When the switching control unit 122 receives the signal OP from the operation confirmation unit 124, the switching control unit 122 causes the booster circuit 110 to perform a boosting operation according to the following procedure.

  Specifically, first, the switching control unit 122 generates the signals PWM1 and PWM2 for turning off the MOS transistors Q1 and Q2, and outputs the generated signals PWM1 and PWM2 to the switch drive circuits 12 and 14. . Accordingly, in the power supply line 9, since the forward current flows through the diode D2 in response to the MOS transistor Q2 being turned off, the forward voltage of the diode D2 is between the input voltage VIN and the output voltage VOUT. A drop corresponding to the voltage corresponding to Vf occurs. That is, the diode D2 constitutes a “step-down unit” according to the present invention, and the output voltage VOUT is set to a voltage lower than the input voltage VIN by the forward voltage Vf of the diode D2. The voltage detection circuits 16 and 18 detect the input voltage VIN and the output voltage VOUT at this time and output them to the switching control unit 122, respectively.

  Since the forward voltage Vf of the diode D2 is normally about 0.6V, the output voltage VOUT by the step-down means is about 12−0.6 = 11.4V. Since this voltage level sufficiently exceeds the operating voltage lower limit value (for example, 8 V) of the electric load 40 described above, the driving of the electric load 40 is not affected. Therefore, according to the present invention, it is possible to reliably drive the electric load 40 even by executing the operation confirmation means.

  Next, when the switching control unit 122 receives the input voltage VIN and the output voltage VOUT from the voltage detection circuits 16 and 18, the switching control unit 122 generates signals PWM1 and PWM2 for compensating for the voltage drop described above. Specifically, the switching control unit 122 sets the voltage command value Vdc_com to the same voltage as the input voltage VIN, and a deviation Vdc_com−VOUT between the set voltage command value Vdc_com (that is, the input voltage VIN) and the output voltage VOUT. The duty ratio is calculated so that (= VIN−VOUT) becomes zero. The switching control unit 122 generates the signals PWM1 and PWM2 based on the calculated duty ratio, and outputs the generated signals PWM1 and PWM2 to the switch drive circuits 12 and 14, respectively.

  As described above, the switching control unit 122 performs feedback control based on the input voltage VIN and the output voltage VOUT, so that the booster circuit 10 performs boosting operation by switching the MOS transistors Q1 and Q2. At this time, the input voltage VIN and the output voltage VOUT are detected by the voltage detection circuits 16 and 18 and transferred to the operation check unit 124.

  Finally, when the operation check unit 124 receives the input voltage VIN and the output voltage VOUT from the voltage detection circuits 16 and 18, it determines whether or not the boosting operation is normally performed based on the voltage difference VIN−VOUT between the two. to decide. If the voltage difference VIN−VOUT is equal to or lower than the predetermined voltage V_std, the operation check unit 124 determines that the boosting operation is normally performed. On the other hand, when the voltage difference VIN−VOUT exceeds the predetermined voltage V_std, the operation check unit 124 determines that the boosting operation is abnormal.

  The predetermined voltage V_std is set to a voltage sufficiently lower than the forward voltage Vf so that the voltage drop corresponding to the forward voltage Vf of the diode D2 is compensated by the boosting operation.

  When it is determined that the boosting operation is abnormal, the operation confirmation unit 124 generates a warning signal WARN and outputs the generated warning signal WARN to the idle stop ECU 50. The idle stop ECU 50 turns on the LED 70 (not shown) in response to the warning signal WARN. Further, the idle stop ECU 50 prohibits subsequent idle stop control.

  In this case, when the driver knows that the drive voltage supply device 10 has failed from the lighting of the LED 70, the driver manually restarts the engine by operating the ignition key to the engine start position where the starter is energized again. In the subsequent operation of the vehicle, the engine is not stopped even if the engine stop condition is satisfied by waiting for a signal or the like, so that the power supply voltage VB does not decrease due to the power consumption of the starter. For this reason, the driver can drive and transport the vehicle in which an abnormality has occurred to a repair shop or the like.

  As described above, the operation confirmation means according to the present invention confirms normal operation using the same path as the drive voltage supply device 10 actually performs the boost operation, and thus correctly determines whether the boost operation is normal / abnormal. Can be judged. Furthermore, since it is not necessary to add a new device for operation confirmation, the operation confirmation of the drive voltage supply device 10 can be performed accurately with a simple and low-cost device configuration.

  Further, since the voltage drop Vf by the step-down means is sufficiently small with respect to the power supply voltage VB, even if the step-up operation for confirming the operation is performed, the load drive voltage VDL does not vary greatly. As a result, the electric load 40 can maintain stable driving even during the execution of the operation confirmation unit.

  FIG. 5 is a flowchart for explaining the operation confirmation means executed by the drive voltage supply apparatus 10 in FIG.

  Referring to FIG. 5, when the engine is first stopped in response to the establishment of the engine stop condition, idle stop ECU 50 generates stop signal STOP, and uses the generated stop signal STOP as an inside of drive voltage supply device 10. To the control circuit 120 (step S01).

  When the operation check unit 124 of the control circuit 120 receives the stop signal STOP from the idle stop ECU 50, the operation check unit 124 generates a signal OP for executing the operation check of the boost operation, and outputs the generated signal OP to the switching control unit 122. To do. When receiving the signal OP from the operation check unit 124, the switching control unit 122 generates signals PWM1 and PWM2 for turning off the MOS transistors Q1 and Q2, and the generated signals PWM1 and PWM2 are used as the switch drive circuit 12, 14 (step S02). Thereby, in the power supply line 9, a voltage drop corresponding to the forward voltage Vf of the diode D2 occurs between the input voltage VIN and the output voltage VOUT.

  The switching control unit 122 detects the input voltage VIN and the output voltage VOUT through the voltage detection circuits 16 and 18 (step S03). The switching control unit 122 performs feedback control based on the input voltage VIN and the output voltage VOUT so that the voltage drop is compensated. As a result, the booster circuit 10 performs the boosting operation with the MOS transistors Q1 and Q2 being switched and controlled (step S04).

  When the operation check unit 124 receives the input voltage VIN and the output voltage VOUT from the voltage detection circuits 16 and 18, the operation check unit 124 determines whether or not the voltage difference VIN−VOUT between them is equal to or less than a predetermined voltage V_std (step S05).

  If it is determined in step S05 that the voltage difference VIN−VOUT is equal to or lower than the predetermined voltage V_std, the operation check unit 124 determines that the boosting operation is normally performed (step S06). In response to this, the idle stop ECU 50 determines that the drive voltage supply device 10 can compensate for the supply of the load drive voltage VDL, and continues the idle stop control (step S07). Therefore, the engine is automatically restarted under the control of the idle stop ECU 50 (step S08).

  On the other hand, when it is determined in step S05 that the voltage difference VIN−VOUT exceeds the predetermined voltage V_std, the operation confirmation unit 124 determines that the boosting operation is abnormal and generates a warning signal WARN, and the generated warning signal WARN is output to the idle stop ECU 50. The idle stop ECU 50 turns on the LED 70 in response to the warning signal WARN. Further, the idle stop ECU 50 prohibits the subsequent idle stop control (step S10). Thereby, the restart of the engine is executed by the operation of the driver's ignition key (step S11).

  In the present embodiment, the operation confirmation unit 124 is configured to execute the operation confirmation of the boost operation in response to the input of the stop signal STOP indicating that the engine has been stopped from the idle stop ECU 50. However, the present invention is not limited to this, and the idle stop ECU 50 may be configured to execute an operation confirmation of the boosting operation in response to the signal EST generated when the engine stop condition is satisfied. In this case, when receiving the warning signal WARN from the operation confirmation unit 124, the idle stop ECU 50 does not automatically stop the engine and prohibits the subsequent idle stop control.

[Example of change]
As described above, the vehicle power supply device 100 according to the present invention reliably drives the electric load even after the engine is restarted by checking the operation of the drive voltage supply device 10 prior to the timing of restarting the engine. Makes it possible to continue.

  Here, in addition to setting the timing for confirming the operation of the drive voltage supply device 10 as the timing at which the engine is stopped, as shown in the following modification example, the timing for performing the operation check can also be set at predetermined intervals. Similar effects can be obtained.

  FIG. 6 is a functional block diagram of a control circuit 120A mounted on the vehicle power supply device according to the modification of the first embodiment of the present invention. The vehicle power supply device according to this modification is obtained by changing the control circuit 120 of FIG. 3 to the control circuit 120A of FIG. 6 with respect to the vehicle power supply device 100 of FIG.

  Referring to FIG. 6, control circuit 120A includes a switching control unit 122, an operation confirmation unit 124A, and a timer 126.

  The switching control unit 122 is the same as the switching control unit 122 in FIG. 3, generates signals PWM1 and PWM2 based on the input voltage VIN and the output voltage VOUT, and outputs them to the switch drive circuits 12 and 14, respectively.

  The timer 126 starts a time measuring operation in response to an instruction from an ECU (not shown). When the timer value reaches a predetermined period set in advance, the timer 126 outputs a signal instructing this to the operation confirming unit 124A and the timer value. Is reset and starts timing again. The timer 126 repeats a series of operations, and outputs a signal to the operation confirmation unit 124A every predetermined period.

  When the operation confirmation unit 124A receives a signal from the timer 126 every predetermined period, the operation confirmation unit 124A generates a signal OP for performing the operation confirmation of the boosting operation, and outputs the generated signal OP to the switching control unit 122.

  When the switching control unit 122 receives the signal OP from the operation confirmation unit 124A, the switching control unit 122 causes a voltage drop between the input voltage VIN and the output voltage VOUT according to the above-described procedure, and compensates the voltage drop in the booster circuit 110. Boost operation is performed.

  Based on the voltage difference between the input voltage VIN and the output voltage VOUT at this time, the operation check unit 124A determines whether or not the boosting operation of the drive voltage supply device 10 is normal. Then, when it is determined that the step-up operation is abnormal, the operation confirmation unit 124A generates a warning signal WARN and outputs it to the idle stop ECU 50. In response to the warning signal WARN, the idle stop ECU 50 prohibits the subsequent idle stop control.

  As described above, according to the first embodiment of the present invention, since the engine is automatically started in response to the confirmation of the normality of the drive voltage supply device, the electric load can be driven even when the engine is restarted. Can be reliably maintained.

  Further, the normal / abnormality of the boosting operation is determined by making the internal boosting circuit perform the same operation as the actual boosting operation, so that the normality of the drive voltage supply device can be confirmed accurately, High reliability can be achieved.

  Furthermore, the load drive voltage does not fluctuate greatly during execution of the operation check of the drive voltage supply device, and is maintained at a voltage sufficiently higher than the operating voltage lower limit value, so that the electric load can be driven stably. Can do.

[Embodiment 2]
FIG. 7 is a block diagram for illustrating a configuration of drive voltage supply apparatus 10B according to the second embodiment of the present invention.

  Referring to FIG. 7, drive voltage supply apparatus 10 </ b> B is different from drive voltage supply apparatus 10 of FIG. , Which is also referred to as a supply node N3), and a voltage detection circuit 18B for detecting the output voltage VOUT1 output via the MOS transistor Q3 is different. Therefore, the detailed description about the part which overlaps with FIG. 2 is not repeated.

  MOS transistor Q3 is connected in series between output node N2 of booster circuit 110 and supply node N3. MOS transistor Q3 receives signal Vg from control circuit 120B at its gate, and is turned on / off according to the potential of received signal Vg. That is, when the MOS transistor Q3 is turned on according to the high-potential signal Vg, the output node N2 of the booster circuit 110 and the supply node N3 are electrically connected, so that the audio / navigation 44 has an output voltage. VOUT is supplied. On the other hand, when the MOS transistor Q3 is turned off in response to the low potential signal Vg, the output node N2 and the supply node N3 of the booster circuit 110 are electrically separated, so that the output voltage VOUT to the audio / navigation 44 is reduced. Supply is cut off.

  As described above, the MOS transistor Q3 constitutes a switching element and has a function of supplying / cutting off the output voltage VOUT to the audio / navigation 44 under the control of the control circuit 120B. The control of the MOS transistor Q3 is performed from the viewpoint of ensuring the operation of the idle stop vehicle as described below.

  In detail, the electric load 40 is distinguished into what is necessary for operation of an idle stop vehicle and what is not necessarily required for operation of a vehicle. In the example of FIG. 7, the meter 46 corresponds to the former, and the audio / navigation 44 corresponds to the latter. Here, when the drive voltage supply device 10 is configured to uniformly supply the output voltage VOUT to these electric loads 40, when the power supply voltage Vb is significantly reduced and falls below the operating voltage lower limit value, such as when the engine is restarted. , All of the electric load 40 is reset, and there is a risk that the operation of the vehicle will be affected.

  Therefore, a priority order based on the contribution to the operation of the vehicle is given to each of the electric loads 40, and when the power supply voltage VB decreases, the supply of the output voltage VOUT to the electric load with a low priority is cut off. . According to this, even if the power supply voltage VB greatly decreases when the engine is restarted after the idle stop, the operation of the vehicle is ensured.

  Furthermore, according to the present invention, the MOS transistor Q3 functions as a “step-down means” when checking the operation of the drive voltage supply device 10B.

  Specifically, MOS transistor Q3 receives signal OP1 from control circuit 120B at its gate when the operation check means is executed. The MOS transistor Q3 is operated in a linear region where the drain current increases with the drain-source voltage in accordance with the gate potential indicated by the signal OP1. During operation in this linear region, the MOS transistor Q3 is connected in series between the output node N2 of the booster circuit 110 and the supply node N3, and can be represented by a resistance that can be varied by the gate potential indicated by the signal OP1. . Therefore, the output voltage VOUT1 appearing at the supply node N3 is lowered from the output voltage VOUT by a voltage that is uniquely determined by the gate potential and the load driving current.

  Voltage detection circuit 18B detects output voltage VOUT1 appearing at supply node N3, and outputs the detected output voltage VOUT1 to control circuit 120B. When control circuit 120B receives input voltage VIN and output voltage VOUT1 from voltage detection circuits 16 and 18B, control circuit 120B causes boosting circuit 110 to perform a boosting operation so as to compensate for the voltage drop.

FIG. 8 is a functional block diagram of the control circuit 120B in FIG.
Referring to FIG. 8, control circuit 120B includes a switching control unit 122B and an operation confirmation unit 124B.

  The switching control unit 122B calculates a duty ratio based on the input voltage VIN and the output voltage VOUT according to the method described above, and outputs signals PWM1 and PWM2 for turning on / off the MOS transistors Q1 and Q2 with the calculated duty ratio. And output to the switch drive circuits 12 and 14, respectively. Thereby, the booster circuit 110 boosts the input voltage VIN to the constant voltage Vc and outputs the boosted output voltage VOUT when the input voltage VIN is in the range of the preset voltages VIN1 to VIN2.

  Further, when the input voltage VIN is equal to or lower than a predetermined voltage, the switching control unit 122B generates a signal Vg for turning off the MOS transistor Q3, and outputs the generated signal Vg to the gate of the MOS transistor Q3. As a result, the supply of the output voltage VOUT to the audio / navigation 44 is cut off.

  When the operation check unit 124B receives a stop signal STOP from the idle stop ECU 50 in response to the engine being stopped, the operation check unit 124B generates a signal OP1 for executing the operation check of the boosting operation, and uses the generated signal OP1 as a MOS transistor. Output to Q3.

  When the MOS transistor Q3 receives the signal OP1 from the operation check unit 124B, the MOS transistor Q3 causes the booster circuit 110 to perform a boosting operation according to the following procedure.

  Specifically, first, the MOS transistor Q3 operates in a linear region according to the gate potential indicated by the signal OP1, and causes a voltage drop between the output node N2 and the supply node N3 of the booster circuit 110. That is, the MOS transistor Q3 constitutes the “step-down unit” according to the present embodiment, and outputs the output voltage VOUT1 obtained by dropping the output voltage VOUT by a voltage determined by the gate potential and the load driving current. The voltage detection circuits 12 and 14B detect the input voltage VIN and the output voltage VOUT1 and output them to the switching control unit 122B.

  Since the drain-source voltage in the linear region of the MOS transistor Q3 is sufficiently low, the load driving voltage VDL of the audio / navigation 44 is sufficiently higher than the lower limit of the operating voltage even if a voltage drop occurs, which has an influence on driving. It does not occur.

  Next, when the switching control unit 122B receives the input voltage VIN and the output voltage VOUT1 from the voltage detection circuits 12 and 14B, the switching control unit 122B generates signals PWM1 and PWM2 for compensating for the voltage drop of the output voltage VOUT1. Specifically, the switching control unit 122B sets the voltage command value Vdc_com to the same voltage as the input voltage VIN, and the deviation Vdc_com−VOUT1 between the set voltage command value Vdc_com (that is, the input voltage VIN) and the output voltage VOUT1. The duty ratio is calculated so that (= VIN−VOUT1) becomes zero. Switching control unit 122B generates signals PWM1 and PWM2 based on the calculated duty ratio, and outputs the generated signals PWM1 and PWM2 to switch drive circuits 12 and 14, respectively.

  As described above, the switching control unit 122B performs feedback control based on the input voltage VIN and the output voltage VOUT1, so that the booster circuit 10 performs switching operation by switching the MOS transistors Q1 and Q2. At this time, the input voltage VIN and the output voltage VOUT1 are detected by the voltage detection circuits 16 and 18B, respectively, and transferred to the operation check unit 124B.

  Finally, when the operation check unit 124B receives the input voltage VIN and the output voltage VOUT1 from the voltage detection circuits 16 and 18B, the operation check unit 124B determines whether or not the boosting operation is normally performed based on the voltage difference VIN−VOUT1 between the two. to decide. The operation confirmation unit 124B determines that the boosting operation is normally performed when the voltage difference VIN−VOUT1 is equal to or lower than a predetermined voltage. On the other hand, when the voltage difference VIN−VOUT1 exceeds the predetermined voltage V_std1, the operation confirmation unit 124B determines that the boosting operation is abnormal.

  Note that the predetermined voltage V_std1 is equal to the drain-source voltage so that the voltage drop corresponding to the drain-source voltage when the MOS transistor Q3 is operated in the linear region is compensated by the boosting operation. In contrast, a sufficiently low voltage is set.

  When it is determined that the boosting operation is abnormal, the operation confirmation unit 124B generates a warning signal WARN and outputs the generated warning signal WARN to the idle stop ECU 50. As in the first embodiment, the idle stop ECU 50 turns on the LED 70 (not shown) in response to the warning signal WARN. Further, the idle stop ECU 50 prohibits subsequent idle stop control. In this case, the engine is restarted when the driver operates the ignition key again.

  FIG. 9 is a flowchart for explaining the operation confirmation means executed in the drive voltage supply apparatus according to Embodiment 2 of the present invention.

  Referring to FIG. 9, first, idle stop ECU 50 executes control for automatically stopping the engine in response to the engine stop condition being satisfied. When engine stop is detected (step S20), the idle stop ECU 50 generates a signal STOP and outputs the generated signal STOP to the operation check unit 124B.

  Next, when the operation confirmation unit 124B receives the signal STOP from the idle ECU 50, the operation confirmation unit 124B executes an operation confirmation unit. Specifically, the operation check unit 124B generates a signal OP1 for operating the MOS transistor Q3 in the linear region, and outputs the generated signal OP1 to the gate of the MOS transistor Q3 (step S21). Since the MOS transistor Q3 operates in a linear region according to the gate potential indicated by the signal OP1, the voltage between the output node N2 of the booster circuit 110 and the supply node N3 corresponds to the drain-source voltage of the MOS transistor Q3. A voltage drop occurs by the voltage to be applied. The input voltage VIN and the output voltage VOUT1 are respectively detected by the voltage detection circuit and transferred to the switching control unit 122B (step S22).

  When the switching control unit 122B receives the input voltage VIN and the output voltage VOUT, the switching control unit 122B performs feedback control so as to compensate for the voltage drop of the output voltage VOUT1 with respect to the input voltage VIN. As a result, the booster circuit 10 performs a boosting operation by switching the MOS transistors Q1 and Q2 (step S23).

  When the operation check unit 124B receives the input voltage VIN and the output voltage VOUT1 from the voltage detection circuits 16 and 18B, the operation check unit 124B determines whether or not the voltage difference VIN−VOUT1 is equal to or less than a predetermined voltage V_std1 (step S24).

  If it is determined in step S24 that the voltage difference VIN-VOUT1 is equal to or less than the predetermined voltage V_std1, the operation check unit 124B determines that the boosting operation is normally performed (step S25). In response to this, the idle stop ECU 50 determines that the drive voltage supply device 10 can compensate for the supply of the load drive voltage VDL, and continues the idle stop control (step S26). Therefore, the engine is automatically restarted under the control of the idle stop ECU 50 (step S27).

  On the other hand, when it is determined in step S24 that the voltage difference VIN−VOUT1 exceeds the predetermined voltage V_std1, the operation check unit 124B determines that the boosting operation is abnormal and generates a warning signal WARN, and the generated warning signal WARN is output to the idle stop ECU 50. The idle stop ECU 50 turns on the LED 70 in response to the warning signal WARN. Further, the idle stop ECU 50 prohibits the subsequent idle stop control (step S29). Thereby, the restart of the engine is executed by the operation of the driver's ignition key (step S30).

  In the present embodiment, the voltage drop means is constituted by the MOS transistor Q3 arranged between the output node N2 and the supply node N3 of the booster circuit 110. However, the present invention is not limited to this, and the voltage drop means is supplied from the source of the MOS transistor Q2. The same effect can be obtained by configuring the semiconductor switch element on the output side.

  As described above, according to the second embodiment of the present invention, since the engine is automatically started in response to the confirmation of the normality of the drive voltage supply device, the electric load can be driven even when the engine is restarted. Can be reliably maintained.

  In addition, since an existing switch element is used as a step-down means and a step-up operation is performed using an actual step-up circuit, a simple and low-cost device configuration without adding a new device as an operation confirmation means Thus, the normality of the drive voltage supply device can be confirmed accurately.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 is a schematic block diagram of a vehicle power supply device mounted on an automobile according to Embodiment 1 of the present invention. It is a block diagram for demonstrating the structure of the drive voltage supply apparatus in FIG. FIG. 3 is a functional block diagram of a control circuit in FIG. 2. It is a figure for demonstrating roughly the input-output characteristic at the time of normal operation | movement of a drive voltage supply apparatus. It is a flowchart for demonstrating the operation confirmation means performed with the drive voltage supply apparatus in FIG. It is a functional block diagram of the control circuit mounted in the vehicle power supply device by the modification of Embodiment 1 of this invention. It is a block diagram for demonstrating the structure of the drive voltage supply apparatus by Embodiment 2 of this invention. It is a functional block diagram of the control circuit in FIG. It is a flowchart for demonstrating the operation confirmation means performed with the drive voltage supply apparatus by Embodiment 2 of this invention.

Explanation of symbols

  9 power line, 10 drive voltage supply device, 12, 14 switch drive circuit, 16, 18, 18B voltage detection circuit, 20 alternator, 30 starter, 40 electrical load, 44 audio / navigation, 46 meter, 50 idle stop ECU, 60 EFI, 70 LED, 100 vehicle power supply device, 110 booster circuit, 120, 120A, 120B control circuit, 122, 122B switching control unit, 124, 124A, 124B operation confirmation unit, 126 timer, B DC power supply, L1 coil, C1 , C2 capacitors, Q1-Q3 MOS transistors, D1, D2 diodes.

Claims (11)

A power supply for supplying a power supply voltage to the engine starting motor;
A voltage supply circuit that receives supply of the power supply voltage from the power supply, generates a load drive voltage for driving an electric load from the received power supply voltage, and supplies the generated load drive voltage to the electric load;
A control circuit that controls the voltage supply circuit to supply a boosted voltage obtained by boosting the power supply voltage as the load drive voltage when the power supply voltage is in a predetermined range;
An engine automatic stop control circuit that automatically controls stop of the engine and restart of the engine by the engine start motor according to the state of the vehicle,
Wherein the control circuit, by executing the step-up operation to the voltage supply circuit includes an operation confirmation means prior KiNoboru pressure operation to confirm whether it can successfully executed,
The engine automatic stop control circuit is a vehicular power supply device that executes automatic control for restarting the engine when it is determined that the boosting operation can be normally executed. 2. The vehicle power supply according to claim 1, wherein the engine automatic stop control circuit prohibits subsequent automatic control of stop and restart of the engine when it is determined that the boosting operation cannot be normally performed. 3. apparatus. The voltage supply circuit includes step-down means for generating the load drive voltage obtained by stepping down the power supply voltage by a predetermined voltage,
The control circuit causes the voltage supply circuit to perform a boost operation so as to compensate the predetermined voltage,
The vehicle according to claim 2, wherein the operation confirmation unit determines that the boosting operation can be normally performed based on a voltage difference between the power supply voltage and the load drive voltage being equal to or less than a predetermined value. Power supply.   The vehicular power supply device according to claim 3, wherein the step-down means sets the predetermined voltage so that the generated load drive voltage does not fall below a lower limit of an operating voltage of the electric load.   The step-down means is connected between a first voltage detection circuit for detecting the power supply voltage and a second voltage detection circuit for detecting the load drive voltage, and in response to an instruction from the operation confirmation means, The vehicle power supply device according to claim 4, wherein the load drive voltage is generated by stepping down the power supply voltage by the predetermined voltage. The step-down means includes a diode element included in the voltage supply circuit and having an anode connected to the first voltage detection circuit side and a cathode connected to the second voltage detection circuit side,
The vehicle power supply device according to claim 5, wherein the diode element generates the load drive voltage obtained by stepping down the power supply voltage by a forward voltage in response to an instruction from the operation confirmation unit. The step-down means includes a field effect transistor connected in series between the output terminal of the voltage supply circuit and the second voltage detection circuit,
The vehicle power supply device according to claim 5, wherein the field effect transistor operates in a linear region in response to a gate potential indicated by the operation confirmation unit. The field effect transistor comprises a switch element connected in series between an output terminal of the voltage supply circuit and a predetermined electrical load selected in advance.
8. The control circuit according to claim 7, wherein the control circuit makes the switch element non-conductive and cuts off the supply of the load driving voltage to the predetermined electric load in response to the power supply voltage falling below the predetermined range. Vehicle power supply.   The vehicle power supply device according to claim 2, wherein the operation confirming unit confirms whether or not a boosting operation in the voltage supply circuit can be normally executed in response to the engine being stopped.   The vehicle power supply according to claim 2, wherein the operation confirming unit confirms whether or not the voltage boosting operation in the voltage supply circuit can be normally executed in response to the engine stop condition being satisfied. apparatus.   The vehicle power supply device according to claim 2, wherein the operation confirmation unit confirms whether or not a boosting operation in the voltage supply circuit can be normally performed at predetermined time intervals.

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