JP6331268B2 - Vehicle power supply - Google Patents

Description

  The present invention relates to a vehicle power supply apparatus that supplies electric power to in-vehicle electrical equipment mounted on a vehicle.

  Conventionally, when a vehicle engine is started, a large amount of current flows through the cell motor, so that the output voltage of the battery rapidly decreases. At this time, sufficient electric power is not supplied to on-vehicle electrical equipment such as an ECU (Engine Control Unit) connected to the battery, and restart due to reset or delay of control occurs. Thereby, for example, when the in-vehicle electrical equipment is a car navigation device or a car audio device, the screen is restarted, the sound is cut off, and the like, causing the user to feel bothered.

  In particular, in a vehicle having an idling stop function (hereinafter referred to as an idling stop vehicle), since the engine is repeatedly stopped and restarted even during traveling, the above-described on-vehicle equipment is frequently reset. For this reason, in an idling stop vehicle, the power-supply auxiliary | assistance apparatus comprised with a DC / DC converter, a capacitor, a battery, etc. is aimed at the reset prevention of the vehicle-mounted electrical equipment at the time of engine restart.

  For example, in Patent Document 1 below, in an idle stop vehicle in which the engine is stopped when the engine stop condition is satisfied and the starter means is operated when the engine start condition is satisfied to start the engine, the engine start condition is satisfied and the starter means An idle stop vehicle is disclosed in which when a battery output voltage drops below a first set value as a result of operation, a voltage compensation means is operated by a control means to compensate for the battery output voltage.

Japanese Patent No. 3826992

  In recent years, in order to further improve fuel efficiency in an idling stop vehicle, a technique has been developed that extends the engine stop time by stopping the engine not only while the vehicle is stopped but also during deceleration of the vehicle. In such a vehicle, there is a possibility that the engine may be restarted while the vehicle is driven by the operation of the driver, and at the same time as the restart of the engine, ABS (Antilock Bracket System) or ASC (Active Stability Control): a skid prevention mechanism. ) And the like, there is a possibility that the braking force control device of the vehicle operates. When a braking force control device (ABS, ASC, etc.) operates, it is necessary to operate an actuator device related to braking force control in addition to a microcomputer related to braking force control. Such an actuator device generally requires more power than a microcomputer.

  In order to ensure the operation of the braking force control device in a conventional vehicle that performs idling stop only when the vehicle is stopped, it is only necessary to prevent resetting of the microcomputer that performs processing related to the braking force control device. For this reason, in the power auxiliary device according to the conventional technique, only power compensation to maintain the operation of the microcomputer is performed. On the other hand, in order to guarantee the operation of the braking force control device in a vehicle that stops idling while the vehicle is running, in addition to a microcomputer, an actuator device that requires more power than the microcomputer can operate. There is a problem that the capacity of the power auxiliary device according to the prior art is insufficient.

  The present invention has been made in view of the above-described problems of the prior art, and is a vehicle power source that can secure electric power necessary for the operation of the braking force control device in a vehicle that performs idling stop even while the vehicle is running. An object is to provide an apparatus.

In order to solve the above-described problems and achieve the object, a vehicle power supply device according to the invention of claim 1 is a battery in a vehicle including an idling stop system that automatically stops and restarts an engine in accordance with preset conditions. A power supply device for a vehicle that supplies a predetermined amount of electric power from the battery and supplies the electric power to a predetermined in-vehicle electrical device when the engine is restarted, and a temperature in the power auxiliary device. Temperature detecting means for detecting, the predetermined on-vehicle electrical equipment group includes an actuator device of braking control means for controlling the behavior of the vehicle by controlling at least the braking force of each wheel of the vehicle, and the electric power The auxiliary device includes a booster circuit that boosts the power, and a relay connected in parallel with the booster circuit to the battery and the first electrical equipment. And a control circuit for switching the boosted voltage in the booster circuit and the connection state of the relay. The control circuit is equipped with a digital signal processor, and a rush in which a rated output current amount is generated when the actuator device is started up The amount of current that is smaller than the amount of current and can be instantaneously output is set to an amount that can secure the amount of inrush current, and the control circuit is configured such that the temperature of the booster circuit in the power auxiliary device is less than a predetermined temperature. In this case, the boosted voltage is the battery voltage of the battery, and when the temperature of the booster circuit in the power auxiliary device is equal to or higher than a predetermined temperature, the boosted voltage is less than the battery voltage and the predetermined in-vehicle electrical equipment is reset. It is characterized by being higher than the voltage .

According to the present invention, when the engine is restarted, the current boosted by the power assist device is supplied to the actuator device that operates when controlling the braking force of the vehicle. As a result, even when the vehicle is running, even when the engine is restarted from the idling stop, it is possible to always supply power necessary for the operation of the actuator device, and to ensure the operation of the braking force control device.
According to the present invention, since the control circuit is equipped with the digital signal processor, the control cycle of the power auxiliary device can be extremely shortened, and the instantaneous output current amount can be increased without increasing the capacity of the power auxiliary device. Can be increased.
According to the present invention, when the temperature in the power auxiliary device is equal to or higher than the predetermined temperature, the boosted voltage is made lower than in the case where the temperature in the power auxiliary device is lower than the predetermined temperature, so that the engine is frequently restarted. Even when the auxiliary power supply device operates, the temperature rise in the auxiliary power supply device can be suppressed, and the time during which the temperature of the auxiliary power supply device falls within the operating temperature range can be lengthened.
According to the present invention, when the temperature in the power auxiliary device is lower than the predetermined temperature, the boosted voltage is set as the battery voltage of the battery. When the temperature in the power auxiliary device is equal to or higher than the predetermined temperature, the boosted voltage is set as the battery voltage of the battery. Since it is less than and higher than the reset voltage of the predetermined in-vehicle electrical equipment, the time during which the temperature of the auxiliary power supply device is within the operating temperature range is lengthened without causing the reset of the predetermined in-vehicle electrical equipment including the braking force control device. be able to.

1 is an explanatory diagram showing a configuration of a vehicle power supply device 10 according to a first embodiment. FIG. 3 is a block diagram showing a functional configuration of a control circuit 406. FIG. 3 is a flowchart showing a control procedure by a control circuit 406.

  Exemplary embodiments of a vehicle power supply device according to the present invention will be explained below in detail with reference to the accompanying drawings.

(Embodiment)
FIG. 1 is an explanatory diagram illustrating a configuration of a vehicle power supply device 10 according to the embodiment. The vehicle power supply device 10 is a device that supplies power from the battery 20 to the in-vehicle electrical equipment group 30 and is mounted on an idling stop vehicle (hereinafter simply referred to as “vehicle”) in the present embodiment. In this embodiment, in order to further improve the fuel efficiency of the idling stop vehicle, the idling stop is performed not only when the vehicle is stopped but also when the vehicle is traveling (decelerated).

The battery 20 is a 12V battery mounted on the vehicle. More specifically, the battery 20 supplies electric power to an engine starter motor (cell motor) 50 mounted on the vehicle to operate, and supplies electric power to the in-vehicle electrical equipment group 30 other than the cell motor (engine starter motor) 50. Supply.
The cell motor 50 is a motor for starting the engine, and is rotated under the control of the ECU 60 to generate an initial rotation of the engine (not shown). Based on the rotation, the engine starts rotating by its own power by combustion. . More specifically, when the ECU 60 controls the opening and closing of the switch 52, the power supply to the cell motor 50 is turned on and off, and the cell motor 50 rotates and stops.

Here, when the battery 20 supplies power to the cell motor 50, that is, when the engine of the vehicle is started, a large amount of power is instantaneously supplied from the battery 20 to the cell motor 50, and the output voltage of the battery 20 is increased. Is significantly reduced. For this reason, the amount of power supplied to the in-vehicle electrical equipment group 30 other than the cell motor 50 is insufficient, and resetting or operation delay of the in-vehicle electrical equipment group 30 occurs. Since the vehicle equipped with the vehicle power supply device 10 is an idling stop vehicle, the engine is frequently restarted (cell motor 50 is operated) even during traveling.
Therefore, in the present embodiment, a predetermined in-vehicle electrical equipment (first electrical equipment 30A) that is a part of the in-vehicle electrical equipment group 30 is connected to the battery 20 via the DC / DC converter 40 that is a power auxiliary device, A reset or the like does not occur when the engine is started.

  The in-vehicle electrical equipment group 30 is an in-vehicle electrical device (for example, ECU 60, car navigation device, interior light, etc.) mounted on the vehicle. The in-vehicle electrical equipment group is divided into a first electrical equipment 30A including at least an actuator device of a vehicle braking force control device, and a second electrical equipment 30B other than the first electrical equipment 30A. The first electrical equipment 30A is connected to the battery 20 via a DC / DC converter 40, which is a power auxiliary device, and a cell motor (engine starter motor) 50 is activated when the engine is restarted from an idling stop. In the event of a failure, a current boosted by the DC / DC converter (power auxiliary device) 40 is supplied. Further, the second electrical equipment 30B is connected to the battery 20 without going through the power auxiliary device. For this reason, with respect to the second electrical equipment 30B, a reset or the like occurs when the cell motor (engine starter motor) 50 is operating when the engine is restarted.

  The first electrical equipment 30A includes a braking force such as a microcomputer that performs processing related to ABS and ASC, which is a braking force control device that controls the behavior of the vehicle by controlling the braking force of each wheel, and an actuator device that operates during braking force control. Includes electrical equipment required for the operation of the controller. In addition, the first electrical equipment 30A may include an in-vehicle electrical equipment such as a car navigation device that is considered troublesome for the user due to frequent resets.

  The DC / DC converter 40, which is a power auxiliary device, is provided between the battery 20 and the first electrical equipment 30A, and boosts the current supplied from the battery 20 to the first electrical equipment 30A. The DC / DC converter 40 includes a booster circuit 402 that boosts current, a relay 404 connected in parallel with the booster circuit 402 to the battery 20 and the first electrical equipment 30A, and a control circuit 406.

  The booster circuit 402 includes a coil 402A, a diode 402B, a transistor 402C, and a capacitor 402D, and boosts the input current to a desired target voltage (boosted voltage). The boosted voltage is usually equal to or higher than the operating voltage (reset voltage of the first electrical device 30A) necessary for normally operating the first electrical device 30A. Here, the battery voltage of the battery 20 (12V in the present embodiment). However, when the temperature in the booster circuit 402 is high as will be described later, the value is smaller than the battery voltage.

  In the booster circuit 402, a thermistor 402E is provided. The temperature in the booster circuit 402 measured by the thermistor 402E is input to the control circuit 406. In the present embodiment, the temperature in the booster circuit 402 is measured. However, the present invention is not limited to this, and the temperature at other points in the DC / DC converter 40, which is a power auxiliary device, is measured and control described later is performed. You may do it.

  The relay 404 includes a first fixed contact 404A, a second fixed contact 404B, and a movable contact 404C that is switched between the first fixed contact 404A and the second fixed contact 404B to open and close the relay 404. In the relay 404, the first fixed contact 404A is a NC (Normally Close) terminal that is a connection contact that closes the relay 404, and the second fixed contact 404B is a NO (Normally Open) terminal that is a connection contact that opens the relay 404. Then, by switching the connection contact of the movable contact 404C and opening and closing the relay 404, the current path can be switched between the first path and the second path.

  When the movable contact 404C is connected to the first fixed contact 404A and the relay 404 is closed, current is supplied from the battery 20 to the first electrical device 30A via the relay 404 without passing through the booster circuit 402. That is, while the vehicle is running normally and the output voltage of the battery 20 does not decrease, the movable contact 404C is connected to the first fixed contact 404A, and a current is supplied at the same voltage as the output voltage at that time. On the other hand, when the movable contact 404C is connected to the second fixed contact 404B and the relay 404 is opened, current is supplied from the battery 20 to the first electrical device 30A via the booster circuit 402. That is, while the engine of the vehicle is restarted from the idling stop state and the battery voltage decreases, the movable contact 404C is connected to the second fixed contact 404B, and a voltage higher than the decreased output voltage (for example, the battery voltage of the battery 20). ) Is supplied with a boosted current.

  The control circuit 406 performs setting of the boosted voltage in the booster circuit 402, switching of the connection state of the relay 404, and the like. The control circuit 406 includes a DSP (Digital Signal Processor) 4060. This is to increase the processing speed in the control circuit 406 and increase the output of the DC / DC converter 40 instantaneously.

  More specifically, the actuator device included in the first electrical equipment 30 </ b> A obtains power by the motor, but the inrush current until the motor starts rotating and generates counter electromotive force is very large. This inrush current increases in proportion to the capacity of the motor. If the inrush current cannot be sufficiently secured, there may be a delay in starting the motor, which may hinder the operation of the braking force control device.

  On the other hand, when the power auxiliary device such as the DC / DC converter 40 is designed with the inrush current of the motor of the actuator device as the maximum value, the size and weight of the power auxiliary device and the manufacturing cost increase. In particular, when the size of the power assist device is increased, installation becomes difficult in a vehicle having a limited mounting space. That is, in order to achieve both the function and the size required for the power auxiliary device, it is necessary to simultaneously achieve instantaneous high output and miniaturization.

  Here, the occurrence frequency of the inrush current accompanying the operation of the braking force control device (the inrush current accompanying the operation of the actuator device) is low, and the occurrence time is very short and instantaneous. In addition, an element such as a semiconductor included in the booster circuit 402 has a characteristic that an instantaneous energization current is much larger than a steady energization current. That is, in the PWM control in the DC / DC converter 40, the instantaneous output current amount can be increased by setting the feedback control cycle to an extremely short time compared to the prior art. For this reason, in the present embodiment, the DSP 4060 is mounted on the control circuit 406 as a method for shortening the control period of the PWM control in the DC / DC converter 40 for a very short time. Thus, by appropriately combining the control and component selection in the auxiliary power supply device, it is possible to reduce the size of the device body while increasing only the instantaneous output.

  The DC / DC converter 40 of the present embodiment has a rated output current amount that is smaller than the inrush current amount generated when the actuator device of the braking force control device included in the first electrical equipment 30A is activated, and can be output instantaneously. The amount of current is set to an amount that can secure the amount of inrush current generated when the actuator device is started.

FIG. 2 is a block diagram showing a functional configuration of the control circuit 406. The control circuit 406 includes a boost voltage setting unit 406A, a switching control unit 406B, a traveling state acquisition unit 406C, a relay control unit 406D, and a voltage measurement unit 406E.
The boosted voltage setting unit 406A sets a boosted voltage that is a target value for boosting by the DC / DC converter 40. The switching control unit 406B controls the switching timing of the transistor 402C so that the current is boosted to a desired voltage. The traveling state acquisition unit 406C acquires information on the traveling state of the vehicle (traveling speed, engine restart timing after idling stop, etc.) from the ECU 60 or the like.

  In addition, when the temperature in the booster circuit 402 measured by the thermistor 402E is equal to or higher than a predetermined temperature, the booster voltage setting unit 406A lowers the booster voltage than when the temperature in the booster circuit 402 is lower than the predetermined temperature. More specifically, when the temperature in the booster circuit is lower than the predetermined temperature, the boosted voltage is set as the battery voltage of the battery 20, and when the temperature in the booster circuit 402 is higher than the predetermined temperature, the boosted voltage is lower than the battery voltage and 1 higher than the reset voltage of the electrical equipment 30A.

  When the frequency of idling stop increases, the operation interval of the power auxiliary device such as the DC / DC converter 40 becomes very short. When the operation interval is shortened, a sufficient heat dissipation time cannot be secured even if heat is generated in the power auxiliary device, so that the heat amount is accumulated and cannot be within the operating temperature range of the power auxiliary device. Therefore, in the power auxiliary device, when the temperature inside the device becomes high, the drooping control is performed in order to extend the time within the operating temperature range.

  In general drooping control, output current and output voltage are monitored, and control is performed to suppress output (power) within a certain range. However, when the output is changed in accordance with the characteristics of the motor (such as inrush current and steady current), it is difficult to monitor the output and perform the droop control. For example, when the droop control is performed when the output power exceeds a predetermined amount of power, the output is suppressed even when the output instantaneously increases due to the inrush current of the motor, and the necessary power is supplied. I can't.

  Therefore, in this embodiment, the temperature in the booster circuit 402 is monitored, and the steady output (boosted voltage) is lowered only when the operating temperature limit of the booster circuit 402 is approached. Accordingly, in the power auxiliary device (DC / DC converter 40), it is possible to extend the operation time by the drooping control while enabling a large output change due to the inrush current.

  The relay control unit 406D performs control to switch the open / close (connected) state of the relay 404 by switching the connection contact of the movable contact 404C of the relay 404 between the first fixed contact 404A and the second fixed contact 404B. More specifically, relay control unit 406D switches the open / close (connected) state of relay 404 based on the traveling state of the vehicle acquired by traveling state acquisition unit 406C. That is, as described above, while the vehicle is running normally and the output voltage of the battery 20 does not decrease, the movable contact 404C is connected to the first fixed contact 404A and the relay 404 is closed, and the output voltage at that time A current is supplied to the first electrical equipment 30A at the same voltage. On the other hand, while the engine of the vehicle is restarted while idling is stopped and the battery voltage is lowered, the movable contact 404C is connected to the second contact 404B and the relay 404 is opened. The current boosted to the same voltage as the battery voltage is supplied to the first electrical equipment 30A.

  The voltage measuring unit 406E measures a potential difference (voltage) between a point PA located upstream of the booster circuit 402 and a point PB located downstream of the booster circuit 402. More specifically, the voltage measurement unit 406E includes a first potential (hereinafter referred to as a potential α) at an arbitrary point PA on the battery 20 side from the booster circuit 402, and an arbitrary point on the first electrical equipment 30A side from the booster circuit 402. A potential difference from a second potential (hereinafter referred to as potential β) at PB is measured. The potential difference measured by the voltage measuring unit 406E is used for feedback control of the DC / DC converter 40 and the like.

  FIG. 3 is a flowchart showing a control procedure by the control circuit 406. In the flowchart of FIG. 3, the control circuit 406 determines whether or not the temperature in the booster circuit 402 measured by the thermistor 402E is equal to or higher than a predetermined temperature (step S301). The predetermined temperature is, for example, a value with a sufficient margin from the upper limit of the operating temperature range of the booster circuit 402.

  When the temperature in the booster circuit 402 is lower than the predetermined temperature (step S301: No), the boosted voltage is set to the same voltage (12V) as the battery voltage that is the boosted voltage at the normal time (step S302). On the other hand, when the temperature in the booster circuit 402 is equal to or higher than the predetermined temperature (step S301: Yes), the drooping control is performed because the temperature of the booster circuit 402 may be higher than the operating temperature range. That is, the boosted voltage is set to a value lower than the battery voltage (12 V) that is the normal boosted voltage (less than 12 V) and higher than the reset voltage of the first electrical device 30A (step S303). Accordingly, it is possible to secure electric power necessary for the operation of the electrically-operated equipment such as the ECU 60 that is steadily operating in the first electrical equipment 30A while lowering the boosted voltage to suppress the temperature rise in the booster circuit 402. Further, even when an electrical device that instantaneously consumes a large amount of power, such as an actuator device, is operated, the required power can be supplied by setting the control cycle of the DC / DC converter 40 to a very short time. it can.

  Next, the control circuit 406 obtains the traveling state information from the ECU 60, and determines whether or not the engine is restarted, that is, the cell motor 50 is operated (step S304). If the engine is not restarted (step S304: No), the process returns to step S301 and the subsequent processing is continued.

  On the other hand, when the engine is restarted (step S304: Yes), the movable contact 404C of the relay 404 is connected to the second fixed contact 404B, the relay 404 is opened, and the voltage is increased from the battery 20 to the first electrical equipment 30A. The supply current is boosted by supplying the current via the circuit 402 (step S305). Until the restart of the engine is completed (step S306: No), the process returns to step S305 and the pressure increase is continued. Whether or not the engine restart has been completed is determined, for example, based on whether or not the input voltage to the DC / DC converter 40 has become equal to or higher than a predetermined voltage.

  When the restart of the engine is completed (step S306: Yes), the movable contact 404C of the relay 404 is connected to the first fixed contact 404A, the relay 404 is closed, and the booster circuit 402 from the battery 20 to the first electrical equipment 30A. The current is supplied without going through. That is, the boost control is stopped (step S307), and the process according to this flowchart is terminated.

  As described above, the vehicle power supply device 10 according to the embodiment has the power when the cell motor 50 (engine starter motor) is operated with respect to the actuator device that operates during the braking force control of the vehicle that is the first electrical equipment 30A. A current boosted by the DC / DC converter 40 which is an auxiliary device is supplied. As a result, even when the vehicle is traveling normally, even when the engine is restarted from the idling stop, the electric power necessary for the operation of the actuator device can always be supplied, and the operation of the braking force control device such as ABS or ASC can be ensured. it can.

  In addition, since the vehicle power supply device 10 is equipped with the digital signal processor 4060 in the control circuit 406, the control cycle of the DC / DC converter 40 (power auxiliary device) can be extremely shortened, and the capacity of the power auxiliary device can be reduced. The instantaneous output current amount can be increased without increasing.

  Further, vehicle power supply device 10 has a higher temperature in DC / DC converter 40 (in this embodiment, booster circuit 402) than a predetermined temperature when the temperature in DC / DC converter 40 is lower than the predetermined temperature. Since the boosted voltage is lowered, the temperature rise in the DC / DC converter 40 (boost circuit 402) can be suppressed even when the engine is frequently restarted and the DC / DC converter 40 operates. The time for the temperature of the DC converter 40 to fall within the operating temperature range can be lengthened.

  Further, the vehicle power supply device 10 sets the boosted voltage to the same voltage as the battery voltage when the temperature in the DC / DC converter 40 is lower than a predetermined temperature, and when the temperature in the DC / DC converter 40 is equal to or higher than the predetermined temperature. Since the boosted voltage is lower than the battery voltage and higher than the reset voltage of the first electrical device 30A, the time during which the temperature of the DC / DC converter 40 falls within the operating temperature range is increased without causing the reset of the first electrical device 30A. can do.

  DESCRIPTION OF SYMBOLS 10 ... Vehicle power supply device, 20 ... Battery, 30 ... Car-mounted electrical equipment group, 30A ... 1st electrical equipment, 30B ... 2nd electrical equipment, 40 ... DC / DC converter, 50 ... Cell motor, 52 Switch, 402 Boost circuit, 402A Coil, 402B Diode, 402C Transistor, 402D Capacitor, 402E Thermistor, 404, Relay, 404A First fixed contact, 404B ... second fixed contact, 404C ... movable contact, 406 ... control circuit, 406A ... boost voltage setting unit, 406B ... switching control unit, 406C ... running state acquisition unit, 406D ... relay control unit, 406E ... ... Voltage measuring unit, 4060 ... Digital signal processor

Claims (1)

A vehicle power supply device that supplies battery power in a vehicle including an idling stop system that automatically stops and restarts an engine according to a preset condition,
When restarting the engine, a power auxiliary device that boosts the current from the battery and supplies the boosted current to a predetermined in-vehicle electrical device ,
Temperature detecting means for detecting the temperature in the power auxiliary device,
The predetermined in-vehicle electrical equipment group includes an actuator device of a braking control means that controls the behavior of the vehicle by controlling at least the braking force of each wheel of the vehicle,
The power auxiliary device includes a booster circuit for boosting the power, a relay connected in parallel to the booster circuit for the battery and the first electrical equipment, a boosted voltage in the booster circuit, and a connection of the relay A control circuit for switching the state, and the control circuit is equipped with a digital signal processor, the rated output current amount is smaller than the inrush current amount generated at the start of the actuator device, and can be output instantaneously Is set to an amount that can secure the inrush current amount ,
When the temperature of the booster circuit in the power auxiliary device is lower than a predetermined temperature, the control circuit uses the boosted voltage as the battery voltage of the battery, and the temperature of the booster circuit in the power auxiliary device is equal to or higher than the predetermined temperature. The boost voltage is lower than the battery voltage and higher than the reset voltage of the predetermined in-vehicle electrical equipment,
A power supply device for a vehicle.

Images