JP2018050381A - Vehicle power supply - Google Patents

Abstract

An object of the present invention is to provide a vehicle power supply device capable of suppressing a situation in which a specific load cannot be driven due to a shortage of power of a first power supply unit by suppressing an influence on a second power supply unit. In a power supply device for a vehicle, a voltage conversion section includes a first conductive path that is a power supply path from a first power supply section and at least a power supply path to a starter (specific load). A voltage converter that is electrically connected to the second conductive path 82 that is a power supply path from the second power supply unit 92 and converts at least the voltage applied to the second conductive path 82 and applies it to the first conductive path 81 Perform the operation. The control unit 2 sets the voltage applied to the second conductive path 82 to a value lower than the output voltage of the first power supply unit 91 at the time of full charge at least during a period in which the starter 95 is driven, and the specific load operates. The voltage conversion unit 3 performs a voltage conversion operation of converting the voltage to a predetermined target voltage value higher than the minimum operation voltage to be applied and applying the voltage to the first conductive path 81. [Selection diagram] Fig. 1

Description

  The present invention relates to a vehicle power supply device.

  In recent years, a technique for converting kinetic energy during braking into regenerative power has been adopted in order to improve the fuel efficiency of vehicles. In vehicles equipped with this kind of technology, in order to store the generated power, the power supply system is configured with an auxiliary storage battery in addition to the conventional lead storage battery, and the generator, lead storage battery, auxiliary storage battery Are related to each other and controlled.

  As an example of such a power supply system, a technique such as Patent Document 1 has been proposed. The on-vehicle power supply device disclosed in Patent Document 1 uses a DC / DC converter to convert the electric power discharged from the second storage battery when the second storage battery is charged by regenerative power generation. It operates to boost the pressure and supply it to the lead storage battery side.

JP 2011-126431 A

  By the way, in a power supply system for a vehicle, when driving a specific load that requires a large current such as a starter, the specific load may not be driven normally with electric power of only a lead storage battery. For example, when the performance of a lead storage battery is reduced due to deterioration, a temperature drop, or the like, a situation may occur in which sufficient power for driving a specific load cannot be secured with only the lead storage battery. In such a case, it is conceivable to compensate for the shortage of power by supplying power from the auxiliary storage battery. However, simply supplying power from the auxiliary storage battery significantly increases the burden on the auxiliary storage battery when driving a specific load. For this reason, the auxiliary storage battery must be enlarged in view of this point. In addition, if the shortage of power when driving a specific load is simply compensated by the power from the auxiliary storage battery, the power supply from the auxiliary storage battery (for example, the power supply to other loads connected to the auxiliary storage battery) may become unstable. There is.

  The present invention has been made based on the above-described circumstances, and can prevent a situation in which a specific load cannot be driven due to power shortage of the first power supply unit by suppressing the influence on the second power supply unit. Is intended to provide.

The vehicle power supply device of the present invention includes:
Electrically connected to a first conductive path that is a power supply path from the first power supply unit and a second conductive path that is a power supply path from the second power supply unit and that is at least a power supply path for a specific load; A voltage converter that converts a voltage applied to the first conductive path and performs a voltage conversion operation applied to the second conductive path;
At least during the period when the specific load is driven, the voltage applied to the first conductive path is lower than the output voltage when the second power supply unit is fully charged, and the minimum operation in which the specific load operates. A control unit that causes the voltage conversion unit to perform a voltage conversion operation that converts the voltage into a predetermined target voltage value that is higher than the voltage and applies the voltage to the second conductive path;
Have

  In the vehicle power supply device, the control unit drives the voltage conversion unit, converts the voltage applied to the first conductive path to a predetermined target voltage value at least during the period when the specific load is driven, and converts the voltage to the second conductive path. The voltage conversion operation to be applied is performed by the voltage conversion unit. That is, during the period for driving the specific load, the power for driving the specific load can be supplemented using the power supplied from the first power supply unit via the first conductive path. It becomes easy to avoid the situation where the specific load cannot be driven due to the shortage. Further, the target voltage value in the power conversion operation performed during the period for driving the specific load is a value lower than the output voltage at the time of full charge of the second power supply unit and higher than the minimum operating voltage at which the specific load operates. Since it is a value, the specific load can be operated in a form in which the power supplied from the first power supply unit is suppressed.

1 is a circuit diagram schematically illustrating a vehicle power supply system including a vehicle power supply device according to a first embodiment. 3 is a flowchart illustrating the flow of voltage conversion control performed by the vehicle power supply device according to the first embodiment. (A) is a graph illustrating the change over time of the starter current in the vehicle power supply system of FIG. 1, (B) is a graph illustrating the change over time of the output voltage of the second power supply unit, ( C) is a graph illustrating the change over time of the output voltage of the first power supply unit. 6 is a flowchart illustrating the flow of voltage conversion control performed by the vehicle power supply device according to the second embodiment. 10 is a flowchart illustrating the flow of voltage conversion control performed by the vehicle power supply device according to the third embodiment.

The desirable form of invention is illustrated below.
The control unit functions to cause the voltage conversion unit to perform a voltage conversion operation that converts the voltage applied to the first conductive path to a target voltage value and applies the voltage to the second conductive path every time the specific load is driven. May be.

  Since this vehicle power supply device can supplement the drive power of the specific load with the power of the first power supply unit every time the specific load is driven, the situation where the specific load cannot be driven due to the power shortage of the second power supply unit. It becomes easier to avoid.

  The vehicle power supply device may include a temperature detection unit that detects the temperature of the second power supply unit. The control unit converts the voltage applied to the first conductive path to the target voltage value during the period when the specific load is driven and applies the voltage to the second conductive path when the temperature detected by the temperature detection unit is equal to or lower than a predetermined temperature threshold. The voltage conversion operation to be performed may be performed by the voltage conversion unit.

  In this vehicle power supply device, when the temperature of the second power supply unit is relatively low, that is, when the performance of the second power supply unit is lowered, the driving power of the specific load can be supplemented by the power of the first power supply unit. it can. In other words, since the power of the first power supply unit is used when an environment in which the specific load cannot easily be driven due to the power shortage of the second power supply unit is generated, the frequency of use of the first power supply unit is suppressed and efficient. Can assist.

  The vehicle power supply device may include a deterioration determination unit that determines whether or not the second power supply unit is in a predetermined deterioration state. When the deterioration determining unit determines that the second power supply unit is in the deteriorated state, the control unit converts the voltage applied to the first conductive path to the target voltage value during the period when the specific load is driven, You may function so that the voltage conversion operation | movement applied to a path may be performed by a voltage conversion part.

  This vehicle power supply device supplements the drive power of the specific load with the power of the first power supply unit when the deterioration determination unit determines that the deterioration state is present, that is, when the performance of the second power supply unit is degraded. Can do. That is, when the possibility that the specific load cannot be driven due to the power shortage of the second power supply unit is increased, the power of the first power supply unit is used. be able to.

<Example 1>
Embodiment 1 of the present invention will be described below.
A vehicle power supply device 1 (hereinafter also referred to as a power supply device 1) shown in FIG. 1 is configured as a power supply device used in an in-vehicle power supply system 100 (hereinafter also referred to as a power supply system 100). The power supply system 100 mainly includes a first power supply unit 91, a generator 93, a second power supply unit 92, the power supply device 1 and the like, and includes a first conductive path 81 and a second conductive path 82 which are configured as a wiring unit. The system is configured to be electrically connected, and is configured as a system that supplies power from these to the load 94 on the first power supply unit 91 side, the starter 95, the other load 96 on the second power supply unit 92 side, and the like. ing.

  The first power supply unit 91 is configured by power storage means such as a lithium ion battery or an electric double layer capacitor, for example, and is configured to output a voltage of 48 V, for example, from the high potential side terminal. The first power supply unit 91 has a high potential side terminal connected to the first conductive path 81, and the conductive path 7 </ b> A on the input side of the generator 93, the load 94, and the power supply device 1 through the first conductive path 81. Is electrically connected.

  The 2nd power supply part 92 is comprised by electrical storage means, such as a lead storage battery, an electric double layer capacitor, etc., for example, and makes the structure from which the voltage of 12V is output from a high potential side terminal. The second power supply unit 92 has a high potential side terminal connected to the second conductive path 82, and is connected to the starter 95, the load 96, and the conductive path 7 B on the output side of the power supply device 1 via the second conductive path 82. Electrically connected.

  The generator 93 is configured as a known alternator, for example. A power generation instruction for instructing power generation is input to the generator 93 from a control device (not shown). When the power generation instruction is input, the generator 93 converts the kinetic energy of the vehicle into alternating regenerative power. The generator 93 rectifies the AC regenerative power into the DC regenerative power, and uses the DC voltage related to the rectified DC regenerative power as the output voltage via the first conductive path 81 and the power supply unit 1. Apply to. The generator 93 does not generate power when no power generation instruction is input.

  The starter 95 corresponds to an example of a specific load, and is configured as a known starter for a vehicle. It is configured as a known vehicle starter that performs an operation of increasing the rotational speed until the vehicle engine is properly started, and includes a motor as a drive source. The motor of the starter 95 is mainly operated by electric power supplied from the second power supply unit 92.

  The power supply device 1 includes a voltage conversion unit 3 that converts and outputs an input voltage applied to the input side conductive path 7A, and a control unit 2 that controls the voltage conversion unit 3 with a PWM signal, and includes the input side conductive path 7A. DC voltage (input voltage) applied to is converted in a step-down manner, and an output voltage obtained by stepping down the input voltage is output to the output side conductive path 7B.

  The input side conductive path 7A is configured as, for example, a primary side (high voltage side) power supply line to which a relatively high voltage is applied. The input side conductive path 7A is electrically connected to the high potential side terminal of the first power supply unit 91 via the first conductive path 81, and a predetermined DC voltage (for example, 48V) is applied from the first power supply unit 91. Make a configuration.

  The output side conductive path 7B is configured as a secondary (low voltage side) power supply line to which a relatively low voltage is applied. The output side conductive path 7 </ b> B is electrically connected to the high potential side terminal of the second power supply unit 92 through the second conductive path 82, and a DC voltage smaller than the output voltage of the first power supply unit 91 from the second power supply unit 92. (For example, 12V) is applied.

  Between the input-side conductive path 7A and the output-side conductive path 7B, a voltage converter 3 that functions as a synchronous rectification step-down converter is provided. The voltage conversion unit 3 is a power supply path from the first power supply unit 91, a power supply path from the second power supply unit 92, and a power supply path to at least the starter 95 (specific load). A voltage conversion operation can be performed in which a voltage applied to the first conductive path 81 is converted to a voltage applied to the second conductive path 82 by being electrically connected to the second conductive path 82.

  The voltage conversion unit 3 includes a high-side switching element 4, a low-side switching element 6, and an inductor 12. The switching element 4 is configured as an N-channel MOSFET, and the input side conductive path 7 </ b> A is connected to the drain of the switching element 4. The drain of the switching element 6 on the low side and one end of the inductor 12 are connected to the source of the switching element 4. The switching element 6 has a drain connected to a connection point between the switching element 4 and the inductor 12 and a source grounded. The other end of the inductor 12 is connected to the output side conductive path 7B. Further, an input capacitor 8 is connected to the input side conductive path 7A, an output capacitor 10 is connected to the output side conductive path 7B, and the other end of each is grounded.

  The voltage conversion unit 3 is controlled by the control unit 2 and is input via the conductive path 7A on the input side when the voltage conversion operation start condition is satisfied during normal control other than when the control unit performs specific control described later. The applied voltage of the first conductive path 81 (voltage applied by the output voltage of the generator 93 and the first power supply unit 91) is stepped down to the first target voltage, and the reduced voltage is applied to the second conductive path 82. Output as. On the other hand, when the control unit 2 performs specific control, which will be described later, the voltage conversion unit 3 uses the output voltage of the first power supply unit 91 as an input voltage and the voltage of the second conductive path 82 is lower than the first target voltage. The voltage conversion operation is performed so that the target voltage is 2.

  The detection unit 20 includes a current detection unit 22 that detects an output current and a voltage detection unit 24 that detects an output voltage. The detection unit 20 detects a value reflecting the output current and the output voltage in the output-side conductive path 7B, and outputs the detected values. To do. The current detection unit 22 may be configured to output a voltage value corresponding to a current (output current) flowing through the output-side conductive path 7B as a detection value. For example, the current detection unit 22 includes a resistor and a differential amplifier that are interposed in the output-side conductive path 7B, and the voltage across the resistor is input to the differential amplifier, and resistance is generated by the current flowing through the output-side conductive path 7B. The amount of voltage drop generated in the device is amplified by a differential amplifier and output as a detection value. The voltage detector 24 outputs, for example, a value reflecting the voltage (output voltage) of the output side conductive path 7B (for example, the voltage of the output side conductive path 7B itself, or a divided value). Thus, the detection value (analog voltage value) generated by the current detection unit 22 and the voltage detection unit 24 is input to the control unit 2 and converted into a digital value.

  The temperature detection unit 60 is configured using, for example, a thermistor, detects the temperature of the second power supply unit 92, and outputs temperature information indicating the detected temperature to the control unit 2. For example, the temperature detection unit 60 is arranged so as to be in contact with or close to the surface portion of the second power supply unit 92, and outputs temperature information indicating the temperature of the arrangement position to the control unit 2. In this configuration, the temperature detection unit 60 may be omitted.

  The control unit 2 includes a control circuit such as a microcomputer, and a drive circuit that provides a complementary PWM signal (drive signal) to the switching elements 4 and 6 based on the PWM signal generated by the control circuit. Eggplant. The control circuit includes a CPU, a ROM, a RAM, a nonvolatile memory, and the like, and performs various calculations and processes.

  Next, voltage conversion control performed by the power supply device 1 will be described. For example, the control unit 2 of the power supply device 1 functions to repeatedly execute the voltage conversion control shown in FIG. 2. Specifically, the control unit 2 of FIG. The control in FIG. 2 is repeatedly executed so as to execute the control in FIG. 2 again.

  After starting the voltage conversion control of FIG. 2, the control unit 2 first performs the process of step S1 to determine whether or not the ignition switch is in an on state. In this configuration, when an ignition switch (not shown) provided in the vehicle is switched from the off state to the on state, the ignition switch is turned on from a device (such as an external ECU) provided outside the power supply device 1. An ignition-on signal (hereinafter also referred to as an IG-on signal) is input to the control unit 2 and the IG-on signal is continuously input while the ignition switch is on. On the other hand, when the ignition switch is turned off, an ignition off signal (hereinafter also referred to as an IG off signal) indicating that the ignition switch is turned off is input to the control unit 2 and the ignition switch is turned off. During this time, the IG off signal continues to be input. In step S1, the control unit 2 determines whether or not the IG ON signal is input to the control unit 2, and when determining that the IG ON signal is input (Yes in step S1), the specific control in step S2 I do. On the other hand, when it determines with the control part 2 not having input the IG ON signal in step S1 (in the case of No in step S1), the voltage conversion control shown in FIG. 2 is complete | finished. After completion, the control in FIG. 2 is executed again at short time intervals.

  When performing the specific control in step S2, the control unit 2 converts the input voltage applied to the first conductive path 81 into a predetermined target voltage value (second target voltage value Vt2) and supplies the second conductive path 82 to the second conductive path 82. The voltage converter 3 is caused to perform a step-down operation so as to be applied. The second target voltage value Vt2 is a value smaller than the first target voltage value Vt1 set in the normal control described later. Specifically, the second target voltage value Vt2 is larger than the output voltage when the second power supply unit 92 is fully charged. It is a low value and a value higher than the minimum operating voltage at which the starter 95 (specific load) operates. For example, in a configuration in which the output voltage when the second power supply unit 92 is fully charged is 12V and the starter 95 operates at 8V, the control unit 2 sets the second target voltage value Vt2 from the operable voltage of the starter 95. Is set to a slightly higher value (for example, a predetermined value greater than 8V and less than 9V).

  After executing the specific control in Step S2, the control unit 2 determines whether or not the starter 95 has been started in Step S3. If it is determined that the starter 95 has ended (Yes in Step S3), the control unit 2 performs Step S4. Perform general control. On the other hand, when it is determined in step S3 that the starter 95 has not been started (No in step S3), the control unit 2 returns to step S2 and continues the specific control. As described above, the control unit 2 performs the specific control until the starter 95 is started (specifically, a specific condition indicating the start of the starter 95 is satisfied). In this configuration, for example, a certain period of time after the IG on signal is input is the “specific condition indicating the start end of the starter 95”. In this case, the “IG on signal is input in step S3. If it is determined that a fixed time has passed, the process proceeds to step S4.

  Note that the present invention is not limited to this example. For example, when the control unit 2 is configured to obtain a signal indicating the start end of the starter 95 from an external device that controls the operation of the starter 95, the starter 95 is started from the external device. The acquisition of the signal indicating the end may be the “specific condition indicating the start end of the starter 95”. In this case, if it is determined in step S3 that “a signal indicating the start completion of the starter 95 has been acquired from the external device”, the process proceeds to step S4.

  As described above, in the power supply device 1 of this configuration, the voltage applied to the first conductive path 81 is supplied to the second power supply unit 92 at least during the period when the starter 95 (specific load) is driven by the control of the control unit 2. A second target voltage value Vt2 (predetermined value) that is lower than the output voltage at full charge (for example, 12V) and higher than the lowest operating voltage (for example, 8V) at which the starter 95 (specific load) operates. The voltage conversion section 3 is caused to perform a voltage conversion operation that is applied to the second conductive path 82.

  After starting the general control in step S4, the control unit 2 converts the voltage applied to the first conductive path 81 to the first target voltage value Vt1 when the predetermined voltage conversion condition is satisfied, and performs the second conduction. The voltage conversion operation to be applied to the path 82 is performed by the voltage conversion unit 3. The first target voltage value Vt1 is a value higher than the second target voltage value Vt2, and is set to a value slightly higher than the output voltage of the second power supply unit 92, for example.

Here, an operation during a period in which the general control is performed will be described.
In the power supply device 1 of this configuration, the electric power generated and rectified by the generator 93 (alternator) in conjunction with an engine (not shown) is charged in the first power supply unit 91 and the conductive path 7A on the input side of the power supply device 1 is used. Given to. The power supply device 1 charges the second power supply unit 92 by stepping down the electric power supplied from the generator 93 and the first power supply unit 91 and outputs it to the second conductive path 82, and also starts the starter 95 and other loads. Power is supplied to various in-vehicle electronic devices.

  An ECU (not shown) provided in the vehicle is provided with vehicle travel information such as vehicle speed information, accelerator pedal opening information, or brake pedal depression amount information from the outside. A power generation control unit for controlling the power generation amount of the generator 93 according to the traveling state is attached. Based on the given travel information, the ECU controls the power generation amount of the generator 93 by the power generation control unit, and causes the generator 93 to generate regenerative power during braking of the vehicle.

  The output voltage applied to the first conductive path 81 by the generator 93 is higher than the output voltage of the first power supply unit 91. For this reason, when the generator 93 is generating electric power, the output voltage of the generator 93 is applied to the input conductive path 7A of the power supply device 1 via the first conductive path 81, and the generator 93 is generating power. When there is not, the output voltage of the first power supply unit 91 is applied to the conductive path 7A on the input side of the power supply device 1 through the first conductive path 81.

  During the general control executed in step S4, the output voltage applied to the second conductive path 82 when the voltage conversion unit 3 is performing the voltage conversion operation (step-down operation) is based on the output voltage of the second power supply unit 92. A high first target voltage value Vt1 is set. Therefore, when the voltage conversion unit 3 is performing a voltage conversion operation (step-down operation) during general control, the output voltage of the power supply device 1 is applied to the load 96 and the like, and when the power supply device 1 is stopped, The output voltage of the second power supply unit 92 is applied to the load 96 and the like.

  After starting the general control in step S4, the control unit 2 continues the general control until the ignition switch is switched to an off state (specifically, until an IG off signal is input to the control unit 2). When the IG OFF signal is input to the control unit 2, the control in FIG.

  As described above, in the power supply device 1 of this configuration, the voltage applied to the first conductive path 81 is supplied to the second power supply unit at least during the period when the starter 95 (specific load) is driven by the specific control of the control unit 2. A second target voltage value (second target voltage value Vt2) converted to a predetermined target voltage value (second target voltage value Vt2) that is lower than the output voltage at the time of full charge of 92 and higher than the lowest operating voltage at which the starter 95 operates. The voltage conversion operation to be applied to the conductive path 82 is performed by the voltage conversion unit 3.

  And the control part 2 performs such specific control whenever the starter 95 which is specific load drives. That is, the control unit 2 converts the voltage applied to the first conductive path 81 into a target voltage value (second target voltage) and applies it to the second conductive path 82 every time the starter 95 is driven. For example, the voltage conversion unit 3 performs the operation until the starter 95 is driven.

Hereinafter, the effect of this configuration will be exemplified.
In the vehicular power supply device 1 with this configuration, the voltage applied to the first conductive path 81 is set to a predetermined target voltage during a period in which the control unit 2 drives the voltage conversion unit 3 and at least the starter 95 that is a specific load is driven. The voltage conversion unit 3 is caused to perform a voltage conversion operation that converts the value into a value and applies it to the second conductive path 82. That is, since the power for driving the starter 95 can be supplemented by using the power supplied from the first power supply unit 91 via the first conductive path 81 during the period for driving the starter 95, the second power supply unit It becomes easy to avoid a situation in which the starter 95 cannot be driven due to the lack of power of 92.

  As shown in FIG. 3A, when the starter 95 is driven, the starter current flowing through the starter 95 is greatly increased. Accordingly, as shown in FIG. 3B, the voltage of the second power supply unit 92 (FIG. 3B). In this example, there is a concern that the lead-acid battery voltage) is greatly reduced. In this case, if the low temperature state or the deterioration state of the second power supply unit 92 overlaps, the starter 95 may not be driven due to insufficient power of the second power supply unit 92. On the other hand, in this configuration, the voltage conversion unit 3 is operated during this period (particularly, the period specified as “power supply from DCDC” in FIG. 3B), and the power supplied from the first power supply unit 91. Since the electric power for driving the starter 95 can be supplemented using the above, the above-described problem can be avoided.

  In addition, the target voltage value (second target voltage value Vt2) in the power conversion operation performed during the period for driving the starter 95 is lower than the output voltage when the second power supply unit 92 is fully charged, and the starter 95 95 is a value higher than the minimum operating voltage at which it operates, so that the starter 95 can be operated in a form in which the power supplied from the first power supply unit 91 is suppressed. In particular, when compared with the case where the first target voltage value Vt1 higher than the output voltage of the second power supply unit 92 is output as in the general control, the starter is driven (in particular, “power supply to DCDC” in FIG. 3). It is possible to suppress a decrease in the output voltage (the auxiliary battery voltage in FIG. 3C) of the first power supply unit 91 during the specified period.

  In the vehicular power supply device 1 of this configuration, the control unit 2 converts the voltage applied to the first conductive path 81 into a target voltage value each time the starter 95 that is a specific load is driven, and converts the voltage to the target voltage value. The voltage conversion unit 3 is caused to perform a voltage conversion operation to be applied to. The vehicle power supply device 1 can supplement the drive power of the starter 95 with the power of the first power supply unit 91 each time the starter 95 that is a specific load is driven. It becomes easier to avoid the situation in which 95 cannot be driven.

<Example 2>
Next, Example 2 will be described. The second embodiment is different from the first embodiment in that the control of FIG. 4 is executed instead of the control of FIG. 2, and the other points are the same as the first embodiment. Since the circuit configuration shown in FIG. 1 is the same as that of the first embodiment, reference is made to FIG. 1 in the following description.

  The power supply device 1 according to the second embodiment has the same circuit configuration as that in FIG. 1 and performs voltage conversion control according to the flow in FIG. For example, the control unit 2 of the power supply device 1 according to the second embodiment functions to repeatedly execute the voltage conversion control illustrated in FIG. 4. Specifically, after the control illustrated in FIG. 4 ends (end), The control of FIG. 4 is repeatedly executed so that the control of FIG. 4 is executed again at short time intervals. In the control of FIG. 4, step S21 is the same as step S1 of FIG. 2, and steps S23 to S26 are the same as steps S2 to S5 of FIG. Therefore, specific description of these steps is omitted.

  In step S21, the control unit 2 determines whether or not the IG ON signal is input to the control unit 2, and determines that the IG ON signal is input (in the case of Yes in step S21), the second in step S22. It is determined whether or not the temperature of the power supply unit 92 is equal to or lower than a threshold temperature. In step S22, the control unit 2 determines whether or not the temperature of the second power supply unit 92 detected by the temperature detection unit 60 is equal to or lower than the threshold temperature. If the temperature is equal to or lower than the threshold temperature, specific control is performed in step S23. If the temperature exceeds the threshold temperature, the process proceeds to step S25 to perform general control.

  As described above, the power supply device 1 having this configuration includes the temperature detection unit 60 that detects the temperature of the second power supply unit 92, and the control unit 2 has a temperature detected by the temperature detection unit 60 that is equal to or lower than a predetermined temperature threshold. In this case, the voltage conversion for converting the voltage applied to the first conductive path 81 into the target voltage value (second target voltage value Vt2) and applying the voltage to the second conductive path 82 during the period when the starter 95 (specific load) is driven. It functions to cause the voltage conversion unit 3 to perform the operation.

  When the temperature of the second power supply unit 92 is relatively low, that is, when the performance of the second power supply unit 92 is degraded, the power supply device 1 of this configuration uses the drive power of the starter 95 (specific load) as the first power supply. It can be supplemented by the power of the unit 91. That is, since the power of the first power supply unit 91 is used in an environment in which the starter 95 cannot easily be driven due to insufficient power of the second power supply unit 92, the frequency of use of the first power supply unit 91 is suppressed. And can assist efficiently.

<Example 3>
Next, Example 3 will be described. The third embodiment is the same as the first embodiment except that the control of FIG. 5 is executed instead of the control of FIG. Since the circuit configuration shown in FIG. 1 is the same as that of the first embodiment, reference is made to FIG. 1 in the following description.

  The power supply device 1 according to the third embodiment has the same circuit configuration as that in FIG. 1 and performs voltage conversion control according to the flow in FIG. For example, the control unit 2 of the power supply device 1 according to the third embodiment functions to repeatedly execute the voltage conversion control illustrated in FIG. 5. Specifically, after the control illustrated in FIG. 5 ends (end), The control of FIG. 5 is repeatedly executed so that the control of FIG. 5 is executed again at short time intervals. In the control of FIG. 5, step S31 is the same as step S1 of FIG. 2, and steps S33 to S36 are the same as steps S2 to S5 of FIG. Therefore, specific description of these steps is omitted.

  In step S31, the control unit 2 determines whether or not the IG ON signal is input to the control unit 2, and if it is determined that the IG on signal is input (Yes in step S31), the control unit 2 It is determined whether or not the power supply unit 92 is in a predetermined deterioration state. In step S32, it is determined whether or not the second power supply unit 92 is in a predetermined deterioration state by a predetermined deterioration detection method. Various determination methods known in the art can be used to determine whether or not the first power supply unit 91 is in a deteriorated state. For example, JP 2011-17546 A, JP 2007-30649 A, and 2007 JP The methods described in JP-A-3030650 and JP-A-2008-235155 can be used. Of course, other known methods may be used.

  If the control unit 2 determines in step S32 that the second power supply unit 92 is in a predetermined deterioration state, the control unit 2 performs specific control in step S33. If it is determined that the second power supply unit 92 is not in the predetermined deterioration state, the control unit 2 proceeds to step S35. Perform general control.

  In the power supply device 1 of this configuration, the control unit 2 functions as a deterioration determination unit, and determines whether or not the second power supply unit 92 is in a predetermined deterioration state by a predetermined deterioration detection method. When the control unit 2 determines that the second power supply unit 92 is in a deteriorated state, the control unit 2 sets the voltage applied to the first conductive path 81 during the period when the starter 95 (specific load) is driven to the target voltage value (second To the target voltage value Vt2), and the voltage conversion unit 3 performs a voltage conversion operation to be applied to the second conductive path 82.

  When the vehicle power supply device 1 is determined to be in a deteriorated state by the deterioration determination unit, that is, when the performance of the second power supply unit 92 is degraded, the drive power of the starter 95 (specific load) is supplied to the first power supply. It can be supplemented by the power of the unit 91. That is, since the power of the first power supply unit 91 is used when the possibility that the starter 95 cannot be driven due to insufficient power of the second power supply unit 92 is increased, the frequency of use of the first power supply unit 91 is suppressed and efficient. Can assist.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.

  In the above-described embodiment, the example in which the above-described specific control is performed when the starter 95 is driven in response to the ON operation of the ignition switch has been described. However, the above-described specific control is performed when the starter 95 is driven in response to the return from the idle stop state. It may be.

  In the above-described embodiment, the step-down DCDC converter is exemplified as the voltage conversion unit 3, but a step-up DCDC converter or a step-up / step-down DCDC converter may be used.

  In the embodiment described above, a single-phase DCDC converter is exemplified as the voltage conversion unit 3, but a multiphase DCDC converter may be used.

  In the embodiment described above, a synchronous rectification type DCDC converter is exemplified as the voltage conversion unit 3, but a diode type DCDC converter in which some switching elements are replaced with diodes may be used.

  In the above-described embodiment, the specific control is executed using the ignition switch ON operation as a trigger. However, for example, the specific control may be executed using a starter operation start signal received from the outside as a trigger.

  In the above-described embodiments, the starter has been exemplified as the specific load. However, other known loads may be used as long as the vehicle load requires a large current during driving. Also, the loads 94 and 96 can be various known vehicle loads.

  In the above-described embodiment, an example of measuring the degree of deterioration has been shown. However, in any of the above-described embodiment or any example in which the above-described embodiment is changed, the method described in Japanese Patent No. 5242997 and JP-A-2009-226996 is described. The control unit 2 may measure the SOH (State Of Health) of the second power supply unit 92 by various known methods, and use this SOH as the degree of deterioration. Then, it may be determined that the second power supply unit 92 is in a degraded state when the SOH of the second power supply unit 92 becomes equal to or less than a predetermined threshold.

DESCRIPTION OF SYMBOLS 1 ... Vehicle power supply device 2 ... Control part (deterioration determination part)
DESCRIPTION OF SYMBOLS 3 ... Voltage conversion part 60 ... Temperature detection part 81 ... 1st conductive path 82 ... 2nd conductive path 91 ... 1st power supply part 92 ... 2nd power supply part 95 ... Starter (specific load)

Claims (4)

Electrically connected to a first conductive path that is a power supply path from the first power supply unit and a second conductive path that is a power supply path from the second power supply unit and that is at least a power supply path for a specific load; A voltage converter that converts a voltage applied to the first conductive path and performs a voltage conversion operation applied to the second conductive path;
At least during the period when the specific load is driven, the voltage applied to the first conductive path is lower than the output voltage when the second power supply unit is fully charged, and the minimum operation in which the specific load operates. A control unit that causes the voltage conversion unit to perform a voltage conversion operation that converts the voltage into a predetermined target voltage value that is higher than the voltage and applies the voltage to the second conductive path;
A power supply device for a vehicle.   The controller converts a voltage applied to the first conductive path into the target voltage value and applies the voltage to the second conductive path every time the specific load is driven. The vehicular power supply device according to claim 1 to be performed. A temperature detection unit for detecting the temperature of the second power supply unit;
When the temperature detected by the temperature detection unit is equal to or lower than a predetermined temperature threshold, the control unit converts the voltage applied to the first conductive path during the period when the specific load is driven into the target voltage value, and The power supply device for vehicles according to claim 1 which makes said voltage conversion part perform voltage conversion operation applied to the 2nd electric conduction path. A deterioration determination unit that determines whether or not the second power supply unit is in a predetermined deterioration state;
When the deterioration determining unit determines that the second power supply unit is in a deteriorated state, the control unit sets the voltage applied to the first conductive path during the period during which the specific load is driven to the target voltage value. The power supply device for vehicles according to claim 1 or 3 which makes said voltage conversion part perform voltage conversion operation which converts and applies to said 2nd electric conduction path.

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