JP2012061917A - Power supply control device of vehicle - Google Patents

Abstract

A power supply control device for a vehicle capable of appropriately suppressing a change in characteristics of an auxiliary machine when starting an internal combustion engine.
A power supply control device for a vehicle is applied to a vehicle having an internal combustion engine, a motor for starting the internal combustion engine using electric power of a battery, and an auxiliary machine having a characteristic that an operation state changes depending on a voltage. Auxiliary battery that outputs a power supply voltage lower than the battery and drives the auxiliary machine, a voltage converter that is connected to the battery and the auxiliary battery and performs voltage conversion, and the auxiliary machine operates when the internal combustion engine is started Voltage target lower limit value setting means for changing a lower limit value set for the voltage target value of the voltage converter according to whether or not the voltage target value is set. Thereby, the characteristic change of the auxiliary machine at the time of starting of an internal combustion engine can be suppressed appropriately.
[Selection] Figure 5

Description

  The present invention relates to a power supply control device mounted on a hybrid vehicle or the like.

  This type of technique is described in Patent Document 1, for example. In Patent Document 1, when the high-voltage side battery output decreases and the engine cannot be started, the voltage command of the DC / DC converter is set lower than the output voltage of the auxiliary battery and lower than the operating voltage of the ECU. That the voltage command of the DC / DC converter is set to be equal to or higher than the output power of the auxiliary battery after the completion of the engine start. In this way, power consumption in the DC / DC converter is suppressed while preventing malfunction of the ECU.

JP 2008-74195 A

  However, in the technique described in Patent Document 1 described above, when an auxiliary machine having a characteristic that changes an operating state depending on a supplied voltage (hereinafter, referred to as a “voltage characteristic” as appropriate) is used. There was a possibility that the operation of the auxiliary machine would fluctuate due to the machine voltage change. For example, when the auxiliary machine has an air conditioner and the air conditioner is operating, the air volume may fluctuate. Also, for example, if the accessory has a light and the light is operating, the light may blink. Hereinafter, the change in the characteristics of the auxiliary machine due to the change in the auxiliary machine voltage is referred to as “characteristic change” as appropriate. When such a characteristic change occurs, there is a possibility that a sense of incongruity may be caused to the passengers or other vehicles.

  The present invention has been made to solve the above-described problems, and provides a vehicle power supply control device capable of appropriately suppressing changes in the characteristics of an auxiliary device when starting an internal combustion engine. Objective.

  In one aspect of the present invention, a power supply control device for a vehicle includes an internal combustion engine, a motor that starts the internal combustion engine using battery power, and an auxiliary machine that has a characteristic that an operating state changes depending on a voltage. An auxiliary battery that is applied to a vehicle and outputs a power supply voltage lower than that of the battery and drives the auxiliary machine, a voltage converter that is connected to the battery and the auxiliary battery and performs voltage conversion, and the internal combustion engine And a voltage target lower limit value setting means for changing a lower limit value set for the voltage target value of the voltage converter according to whether or not the auxiliary machine is operating when the engine is started.

  The vehicle power supply control device is preferably applied to a vehicle that starts an internal combustion engine by driving a motor with electric power of a battery (main battery). For example, a vehicle power supply control device is applied to a hybrid vehicle. The auxiliary battery outputs a power supply voltage lower than that of the battery and drives the auxiliary machine having voltage characteristics. The voltage converter is connected to the battery and the auxiliary battery, and performs voltage conversion. For example, the voltage converter is a DC / DC converter. The voltage target lower limit value setting means changes a lower limit value set for the voltage target value of the voltage converter, depending on whether or not an auxiliary machine having voltage characteristics is operating when the internal combustion engine is started. This lower limit value is a control value used to limit the voltage of the voltage converter so as not to fall below the lower limit value.

  According to the above-described vehicle power supply control device, it is possible to appropriately suppress changes in the characteristics of the auxiliary machinery at the start of the internal combustion engine. Specifically, it is possible to appropriately suppress the characteristic change of the auxiliary machine that can occur when the target voltage of the voltage converter is lowered at the time of starting. As a result, it is possible to appropriately suppress a sense of discomfort that may occur in passengers and other vehicles.

  Preferably, in the above-described vehicle power supply control device, the voltage target lower limit value setting means increases the lower limit value when the auxiliary machine is operating compared to when the auxiliary machine is not operating. can do.

  In one aspect of the above vehicle power control device, the auxiliary machine has a light, and the voltage target lower limit setting means has a low illuminance in the surrounding environment when the light is operating. The difference between the lower limit value and the current voltage in the voltage converter is made smaller than when the illuminance is high.

  In this aspect, the voltage target lower limit value setting means is configured such that when the light is operating and the ambient environment illuminance (environmental illuminance) is low, the voltage target lower limit value in the voltage converter and the voltage converter Reduce the difference from the current voltage. That is, the voltage target lower limit setting means increases the lower limit as the environmental illuminance is lower. Thereby, the uncomfortable feeling by the light brightness change which may arise when environmental illuminance is low can be suppressed appropriately. Further, in this aspect, when the environmental illuminance is high, the lower limit value tends to be smaller than when the environmental illuminance is low, so that the starting power can be reduced.

  In another aspect of the power control apparatus for a vehicle described above, the auxiliary machine has an air conditioner, and the voltage target lower limit value setting unit is operated when the air conditioner is operating and the vehicle speed is low. The difference between the lower limit value and the current voltage in the voltage converter is made smaller than when the vehicle speed is high.

  In this aspect, the voltage target lower limit setting means calculates a difference between the lower limit value of the voltage target value of the voltage converter and the current voltage of the voltage converter when the vehicle speed is low when the air conditioner is operating. Make it smaller. That is, the voltage target lower limit setting means increases the lower limit as the vehicle speed is lower. Thereby, the uncomfortable feeling by the air-conditioner air volume change which may occur when the vehicle speed is low can be appropriately suppressed. Further, in this aspect, when the vehicle speed is high, the lower limit value tends to be smaller than when the vehicle speed is low, so that the starting power can be reduced.

  Preferably, the voltage target lower limit value setting means sets the lower limit value so that a characteristic change of the auxiliary machine is not more than a predetermined value when the auxiliary machine is operating. For example, the “predetermined value” is set to a value of characteristic change that makes a person feel uncomfortable. As a result, it is possible to appropriately suppress the change in the characteristics of the auxiliary device that occurs at the time of starting within a range that does not give a sense of incongruity to humans.

The schematic block diagram of the hybrid vehicle in this embodiment is shown. An example of the characteristic variation of an auxiliary machine is shown. The figure for demonstrating the control in 1st Embodiment is shown. An example in which the DC / DC voltage change amount is obtained in consideration of the air conditioner air volume level will be described. The control flow in 1st Embodiment is shown. The figure for demonstrating the calculation method of auxiliary machine power consumption is shown. In 2nd Embodiment, the figure for demonstrating the reason for performing control according to environmental illumination intensity is shown. The figure for demonstrating the control in 2nd Embodiment is shown. In 3rd Embodiment, the figure for demonstrating the reason for performing control according to a vehicle speed is shown. The figure for demonstrating the control in 3rd Embodiment is shown.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

<First Embodiment>
First, a first embodiment in the present invention will be described.

(Device configuration)
FIG. 1 is a schematic configuration diagram of a hybrid vehicle 100 equipped with a vehicle power supply control device according to the first embodiment. Note that broken line arrows in FIG. 1 indicate signal input / output.

  Hybrid vehicle 100 mainly includes engine (internal combustion engine) 1, axle 2, drive wheels 3, first motor generator MG 1, second motor generator MG 2, power split mechanism 4, inverter 5, and the like. The main battery 6, the DC / DC converter 7, the auxiliary battery 8, the auxiliary machine 9, and an ECU (Electronic Control Unit) 20 are provided.

  The axle 2 is a part of a power transmission system that transmits the power of the engine 1 and the second motor generator MG2 to the wheels 3. The wheels 3 are wheels of the hybrid vehicle 100, and only the left and right front wheels are particularly shown in FIG. The engine 1 is composed of a gasoline engine, for example, and functions as a power source that outputs the main propulsive force of the hybrid vehicle 100. The engine 1 is controlled variously by the ECU 20.

  The first motor generator MG1 is configured to function mainly as a generator for charging the main battery 6 or a generator for supplying power to the second motor generator MG2, and the output of the engine 1 To generate electricity. The second motor generator MG2 is mainly configured to function as an electric motor that assists (assists) the output of the engine 1. For example, the second motor generator MG2 operates to start the engine 1 using the electric power from the main battery 6.

  Further, the second motor generator MG2 generates a braking force by functioning as a regenerative brake at the time of engine braking or braking by a foot brake. These motor generators MG1 and MG2 are configured as, for example, synchronous motor generators, and include a rotor having a plurality of permanent magnets on the outer peripheral surface and a stator wound with a three-phase coil that forms a rotating magnetic field. Hereinafter, the first motor generator MG1 and the second motor generator MG2 are referred to as “motor generator MG” as appropriate.

  Power split device 4 corresponds to a planetary gear (planetary gear mechanism) configured with a sun gear, a ring gear, and the like, and is configured to be able to distribute the output of engine 1 to first motor generator MG1 and axle 2. ing.

  Inverter 5 is a DC / AC converter that controls input / output of power between main battery 6 and first motor generator MG1 and / or second motor generator MG2. For example, the inverter 5 converts the AC power generated by the first motor generator MG1 into DC power and supplies it to the main battery 6, and converts the DC power extracted from the main battery 6 into AC power for the second. To the motor generator MG2.

  The main battery 6 is configured to be capable of functioning as a power source for driving the first motor generator MG1 and / or the second motor generator MG2, and the first motor generator MG1 and / or the second motor generator MG2. It is a storage battery configured to be able to charge electric power generated by motor generator MG2.

  The DC / DC converter 7 corresponds to an example of a voltage converter in the present invention, and steps down the power of the main battery 6 and supplies it to the auxiliary battery 8, the auxiliary machine 9, and the ECU 20. Specifically, the DC / DC converter 7 steps down the DC voltage supplied from the main battery 6 in accordance with the control signal S7 supplied from the ECU 20 and supplies the reduced DC voltage to the auxiliary battery 8 and the auxiliary machine 9. And supplied to the ECU 20.

  The auxiliary battery 8 is a battery that supplies electric power to the auxiliary machine 9 and the ECU 20, and outputs a power supply voltage lower than that of the main battery 6. The auxiliary battery 8 is charged by a direct current voltage from the DC / DC converter 7.

  In other words, the auxiliary machine 9 is an “auxiliary machine load” and is driven by electric power supplied from the auxiliary battery 8 through the DC / DC converter 7. For example, the auxiliary machine 9 includes an air conditioner (air conditioner), a light (lighting device), an ignition device, an electric pump, a power window, an audio, and the like.

  The ECU 20 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like (not shown), and performs various controls on each component in the hybrid vehicle 100. Specifically, the ECU 20 includes the engine 1, the first motor generator MG1, the second motor generator MG2, the inverter 5, the main battery 6, the DC / DC converter 7, the auxiliary battery 8, and the auxiliary machine 9. These components are controlled by exchanging signals S1 to S3 and S5 to S9. The ECU 20 includes, for example, a hybrid ECU, an engine ECU, and a motor ECU. Although details will be described later, the ECU 20 functions as voltage target lower limit setting means in the present invention.

(Control method)
Next, the control performed by the ECU 20 in the first embodiment will be specifically described.

  As described above, there is a technique for reducing the power consumption of the auxiliary machine by limiting the voltage command of the DC / DC converter 7 at the time of starting the engine. However, in this technique, the auxiliary machine 9 has a voltage (in other words, an electric load). More specifically, if the operation state changes depending on the terminal voltage of the auxiliary machine 9), the operation of the auxiliary machine 9 may fluctuate due to the change of the auxiliary machine voltage. That is, when the engine is started, there is a possibility that the auxiliary machine 9 having the voltage characteristic may change in characteristic due to the auxiliary machine voltage change. More specifically, in this technique, when the target value of the voltage in the DC / DC converter 7 is reduced during engine start-up, even if the voltage is within the operating voltage range of the ECU 20, it has a voltage characteristic. In the machine 9, there is a possibility that the characteristic change occurs only during starting.

  For example, when the auxiliary machine 9 has an air conditioner and the air conditioner is in operation, as shown in FIG. 2, the air conditioner is caused by fluctuations in the voltage supplied to the air conditioner (terminal voltage of the auxiliary machine 9). The airflow tends to fluctuate. The air conditioner corresponds to an air conditioner blower, and the air conditioner air volume corresponds to the air volume of the air conditioner blower. On the other hand, if the accessory 9 has a light and the light is operating, the light may blink due to a change in the accessory voltage. When such a characteristic change of the auxiliary machine 9 occurs, there is a possibility that a sense of incongruity may be caused to the passengers or other vehicles. For example, in the intermittent start of the engine 1, it can be said that such a problem tends to appear remarkably because the vehicle is running and the start frequency is high.

  Therefore, in the first embodiment, the ECU 20 sets the lower limit value set for the voltage target value of the DC / DC converter 7 according to whether or not the auxiliary machine 9 having voltage characteristics is operating at the time of engine start. To change. The lower limit value is a control value used to limit the voltage of the DC / DC converter 7 (hereinafter referred to as “DC / DC voltage” as appropriate) so as not to fall below the lower limit value. Hereinafter, the lower limit value is referred to as “starting DC / DC voltage target lower limit value”, and the symbol “VDC_crk” is used as appropriate. Specifically, the ECU 20 increases the starting DC / DC voltage target lower limit value when the auxiliary machine 9 having voltage characteristics is operating, compared to when the auxiliary machine 9 is not operating. Further, the ECU 20 sets the DC / DC voltage target at start-up so that the characteristic change of the auxiliary machine 9 is not more than a predetermined value (hereinafter referred to as “characteristic change predetermined value”) when the auxiliary machine 9 is operating. Set the lower limit.

  Specifically, assuming that there are a plurality of auxiliary machines 9 having voltage characteristics, the ECU 20 first changes the characteristic changes of the auxiliary machines 9 that are turned on among the plurality of auxiliary machines 9. A voltage change amount in the DC / DC converter 7 that is equal to or less than a predetermined value (hereinafter, referred to as “DC / DC voltage change amount” as appropriate) is obtained. In this case, the ECU 20 uses the characteristic change predetermined value determined for each auxiliary machine 9, and the characteristic change is less than the characteristic change predetermined value for each of the auxiliary machines 9 that are turned on among the plurality of auxiliary machines 9. A DC / DC voltage change amount such that

  Then, the ECU 20 obtains a minimum voltage change amount among the obtained plurality of DC / DC voltage change amounts, and sets the minimum DC / DC voltage change amount as an upper limit (hereinafter referred to as a change width) of the DC / DC voltage. It is called “change width upper limit”, and the sign of “ΔVDCmax” is used as appropriate.) That is, the ECU 20 sets the DC / DC voltage change amount obtained from the auxiliary machine 9 having the largest characteristic change with respect to the DC / DC voltage change among the auxiliary machines 9 turned on as the upper limit of the DC / DC voltage change width. Set. This is because the change in the DC / DC voltage is limited by the upper limit of the change width, thereby limiting the change in the characteristics of all the auxiliary machines 9 that are turned on to a value equal to or less than the predetermined value for changing the characteristic.

  Thereafter, the ECU 20 obtains a voltage obtained by subtracting the upper limit of the change width from the current DC / DC voltage (hereinafter referred to as “current DC / DC voltage”, and appropriately uses the sign of “VDC_now”). Set to the target voltage lower limit. That is, the ECU 20 guards the starting DC / DC voltage target lower limit value by “VDC_now−ΔVDCmax”. In this case, the ECU 20 determines that the voltage obtained by subtracting the upper limit of the change width from the current DC / DC voltage is called a DC / DC voltage necessary for operating the ECU 20 (hereinafter referred to as “ECU operating voltage”, and a sign of “VDC_low” as appropriate. Is less than the current DC / DC voltage, the ECU operating voltage is set to the starting DC / DC voltage target lower limit value. This is to ensure the operation of the ECU 20 by preventing the DC / DC voltage at the time of engine start from dropping below the ECU operating voltage.

  Thereafter, the ECU 20 controls the voltage conversion in the DC / DC converter 7 using the voltage equal to or higher than the starting DC / DC voltage target lower limit set as described above as a target value, and starts the engine 1. Take control. Thereby, it becomes possible to appropriately suppress the characteristic change of the auxiliary machine 9 when the engine is started.

  Here, a specific example of control in the first embodiment will be described with reference to FIG. FIG. 3 shows the DC / DC voltage on the horizontal axis, and the accessory characteristics (corresponding to the operating state of the accessory 9) on the vertical axis. Specifically, the operation state of the ECU 20, the air conditioner air volume, and the light luminance are shown in order from the top. Here, an air conditioner and a light are illustrated as the auxiliary machine 9, a change in air-conditioner air volume is used as a change in air conditioner characteristics, and a change in light luminance is used as a change in light characteristics.

  When the air conditioner is turned on, the ECU 20 uses the characteristic change predetermined value (hereinafter referred to as “air flow change predetermined value”) determined for the change in the air conditioner air volume, and the change in the air conditioner air volume changes the air volume. A DC / DC voltage change amount (hereinafter, a sign of “ΔVDC_A” is appropriately used) that is equal to or less than a predetermined value is obtained. Specifically, the ECU 20 uses the graph 51 indicating the relationship between the DC / DC voltage and the air flow rate of the air conditioner as a reference, based on the current DC / DC voltage VDC_now, to determine the DC / DC voltage change amount corresponding to the predetermined air flow rate change value. ΔVDC_A is obtained. The graph 51 showing the relationship between the DC / DC voltage and the air flow rate of the air conditioner is obtained in advance through experiments or simulations and stored in a memory or the like. The ECU 20 obtains the DC / DC voltage change amount ΔVDC_A using the graph 51 stored in the memory.

  On the other hand, when the light is on, the ECU 20 uses the characteristic change predetermined value (hereinafter referred to as “brightness change predetermined value”) determined with respect to the change in the light luminance to change the light luminance. Is a DC / DC voltage change amount (hereinafter, a sign of “ΔVDC_B” is used as appropriate) such that the luminance change is not more than a predetermined value. Specifically, the ECU 20 uses the graph 52 indicating the relationship between the DC / DC voltage and the light luminance, based on the current DC / DC voltage VDC_now, and the DC / DC voltage variation corresponding to the predetermined luminance variation value. ΔVDC_B is obtained. Note that the graph 52 indicating the relationship between the DC / DC voltage and the light luminance is obtained in advance through experiments or simulations and stored in a memory or the like. ECU20 calculates | requires DC / DC voltage variation | change_quantity (DELTA) VDC_A using the graph 52 memorize | stored in the said memory.

  In the example shown in FIG. 3, since ΔVDC_B is the smallest among the DC / DC voltage change amounts ΔVDC_A and ΔVDC_B, the ECU 20 sets the DC / DC voltage change amount ΔVDC_B to the change width upper limit ΔVDCmax. Since the voltage obtained by subtracting the change width upper limit ΔVDCmax (ΔVDC_B) from the current DC / DC voltage VDC_now is greater than the ECU operating voltage VDC_low, the ECU 20 subtracts the voltage obtained by subtracting the change width upper limit ΔVDCmax from the current DC / DC voltage VDC_now. Set to the DC / DC voltage target lower limit at start-up.

  When determining the DC / DC voltage change amount at which the characteristic change of the auxiliary machine 9 is equal to or less than the characteristic change predetermined value, the relationship between the DC / DC voltage change and the characteristic change in each auxiliary machine 9 (for example, graphs 51 and 52) ) May be considered. Depending on the accessory 9, the relationship between the DC / DC voltage change and the characteristic change is not fixed, and the relationship may change depending on some parameters. In other words, the DC / DC voltage change amount that causes the characteristic change to be equal to or less than the characteristic change predetermined value may change depending on some parameter. Therefore, the ECU 20 selects, for example, the relationship between the DC / DC voltage change and the characteristic change according to such a parameter, and the DC / DC voltage change at which the characteristic change is equal to or smaller than the characteristic change predetermined value based on the selected relationship. The amount can be determined.

  FIG. 4 is a diagram illustrating an example of obtaining the DC / DC voltage change amount ΔVDC_A in consideration of the air conditioner air volume level. FIG. 4 shows the DC / DC voltage on the horizontal axis and the air-conditioner air volume on the vertical axis.

  As shown in FIG. 4, it can be seen that the relationship between the DC / DC voltage and the air conditioner air volume changes according to the air conditioner air volume level (HI, M, LO). For example, when the air conditioner air volume level is “HI”, the relationship between the DC / DC voltage and the air conditioner air volume is as shown by the graph 61, and when the air conditioner air volume level is “M”, the graph 62 shows the relationship. When the air conditioner air flow level is “LO”, the relationship between the DC / DC voltage and the air conditioner air flow as shown in the graph 63 is obtained. That is, the higher the air conditioner air flow level, the greater the amount of change in the air conditioner air flow with respect to the change in the DC / DC voltage.

  Therefore, the ECU 20 decreases the DC / DC voltage change amount ΔVDC_A as the air conditioner airflow level is higher. For example, the ECU 20 obtains the DC / DC voltage change amount ΔVDC_Aa from the graph 61 when the air conditioner air flow level is “HI”, and the DC / DC voltage change from the graph 62 when the air conditioner air flow level is “M”. The amount ΔVDC_Ab is obtained, and when the air conditioner air flow level is “LO”, the DC / DC voltage change amount ΔVDC_Ac is obtained from the graph 63 (ΔVDC_Aa <ΔVDC_Ab <ΔVDC_Ac).

  For example, the relationship between the DC / DC voltage corresponding to the air conditioner air volume level and the air conditioner air volume as shown in graphs 61 to 63 is obtained in advance through experiments or simulations and stored in a memory or the like. And ECU20 calculates | requires DC / DC voltage variation | change_quantity (DELTA) VDC_A using the relationship memorize | stored in the said memory.

  The “characteristic change predetermined value” used to limit the characteristic change of the auxiliary machine 9 is basically set in advance in consideration of human sensation. For example, the characteristic change predetermined value is set to a value corresponding to the characteristic change of the auxiliary machine 9 that makes a person feel uncomfortable. If the auxiliary machine 9 is an air conditioner, a value corresponding to a change in the air conditioner air volume that makes the person feel uncomfortable is set to a predetermined value, and if the auxiliary machine 9 is a light, the light brightness that makes the person feel uncomfortable A value corresponding to the change is set to a luminance change predetermined value.

(Control flow)
Next, a control flow in the first embodiment will be described with reference to FIG. The control flow is repeatedly executed by the ECU 20. This process is executed, for example, when the engine 1 is started.

  In step S101, the ECU 20 determines whether or not the auxiliary machine 9 having voltage characteristics is turned on. In this case, the ECU 20 performs the determination according to a command signal supplied to the auxiliary machine 9 or a signal supplied from the auxiliary machine 9. If the auxiliary machine 9 is on (step S101; Yes), the process proceeds to step S102. If the auxiliary machine 9 is not on (step S101; No), the process proceeds to step S104.

  In step S102, the ECU 20 sets a change width upper limit based on the DC / DC voltage change amount of the auxiliary machine 9 that is turned on. Specifically, the ECU 20 uses the characteristic change predetermined value determined for each auxiliary machine 9, and for each of the auxiliary machines 9 that are turned on among the plurality of auxiliary machines 9 having voltage characteristics, A DC / DC voltage change amount at which the change is less than a predetermined value of each characteristic change is obtained. Then, the ECU 20 sets the minimum voltage change amount among the obtained plurality of DC / DC voltage change amounts as the change width upper limit in the DC / DC voltage. This process is expressed as “ΔVDCmax = min (ΔVDC_A, ΔVDC_B,...)”. After step S102 ends, the process proceeds to step S103.

  In step S103, the ECU 20 sets the starting DC / DC voltage target lower limit value based on the change width upper limit. Specifically, the ECU 20 guards the starting DC / DC voltage target lower limit value with a voltage obtained by subtracting the change width upper limit from the current DC / DC voltage. In this case, the ECU 20 sets the larger one of the voltage obtained by subtracting the change width upper limit from the current DC / DC voltage and the ECU operating voltage as the DC / DC voltage target lower limit value at the time of starting. This process is expressed as “VDC_crk ← max (VDC_low, VDC_now−ΔVDCmax)”. After step S103 ends, the process proceeds to step S105.

  On the other hand, in step S104, the ECU 20 sets the starting DC / DC voltage target lower limit value to the ECU operating voltage because the auxiliary machine 9 having voltage characteristics is not turned on. This process is expressed as “VDC_crk ← VDC_low”. Then, the process proceeds to step S105.

  In step S105, the ECU 20 acquires the current consumption of the auxiliary machine 9 (auxiliary machine current consumption). For example, the ECU 20 acquires the auxiliary machine current consumption from a current sensor that detects the current of the auxiliary machine 9. Then, the process proceeds to step S106.

  In step S106, the ECU 20 calculates the power consumption (auxiliary power consumption) of the auxiliary machine 9 when starting the engine. Specifically, the ECU 20 calculates the auxiliary machine power consumption based on the auxiliary machine current consumption acquired in step S105 and the starting DC / DC voltage target lower limit value set in step S103 or step S104. Then, the process proceeds to step S107.

  Here, with reference to FIG. 6, an example of a method of calculating auxiliary machine power consumption will be described. FIG. 6 shows the DC / DC voltage on the horizontal axis and the auxiliary machine power consumption on the vertical axis. The ECU 20 uses the map defined by the DC / DC voltage, the auxiliary machine power consumption, and the auxiliary machine current consumption as shown in FIG. 6, and uses the current auxiliary machine current consumption and the starting DC / DC voltage target lower limit value VDC_crk. Is calculated (see arrow 70 for example). The map is defined such that the auxiliary machine power consumption increases as the auxiliary machine current consumption increases. The map is set in advance based on a predetermined experiment, a predetermined arithmetic expression, or the like.

  Returning to FIG. 5, the processing after step S107 will be described. In step S107, the ECU 20 determines that the battery output of the main battery 7 is the power required for starting the engine 1 (hereinafter referred to as “engine starting power”), and the auxiliary machine power consumption calculated in step S106. It is determined whether the power is equal to or less than the power obtained by adding. When the battery output is equal to or lower than the power obtained by adding the engine starting power and the auxiliary machine power consumption (step S107; Yes), the process proceeds to step S108.

  In step S108, the ECU 20 starts the engine 1 by driving the motor generator MG using the electric power of the main battery 7 and calls the target voltage of the DC / DC converter 7 (hereinafter referred to as “DC / DC target voltage”). Is set to a voltage corresponding to the starting DC / DC voltage target lower limit value set in step S103 or step S104 (VDC ← VDC_crk). Then, the process proceeds to step S109.

  In step S109, the ECU 20 determines whether or not the engine 1 is in a complete explosion state based on the engine speed or the like. When the engine 1 is in a complete explosion state (step S109; Yes), the process proceeds to step S110. On the other hand, when the engine 1 is not in a complete explosion state (step S109; No), the process returns to step S109.

  On the other hand, when the battery output is larger than the power obtained by adding the engine starting power and the auxiliary machine power consumption (step S107; No), the process proceeds to step S110. In this case, the engine 1 is not started in order to suppress the occurrence of a start-up shock or the like in the engine 1.

  In step S110, the ECU 20 sets the DC / DC target voltage to a voltage used during normal traveling. Then, the process ends.

  According to 1st Embodiment described above, the characteristic change of the auxiliary machine 9 at the time of engine starting can be suppressed appropriately. Therefore, it is possible to appropriately suppress a sense of incongruity that may occur in a passenger or another vehicle.

Second Embodiment
Next, a second embodiment will be described. As described above, the DC / DC voltage change amount is obtained such that the characteristic change of the auxiliary machine 9 is equal to or less than the characteristic change predetermined value (see FIG. 3 and the like). In the second embodiment, this “characteristic change predetermined value” is obtained. It differs from the first embodiment in that the “value” is changed. Specifically, in the second embodiment, the characteristic change predetermined value is changed based on a factor that changes the characteristic change of the auxiliary machine 9 that is felt as human sensation. Changing the characteristic change predetermined value in this way corresponds to changing the DC / DC voltage change amount of the auxiliary machine 9 based on a factor that changes the characteristic change felt as human sensation. This corresponds to changing the DC / DC voltage target lower limit value at the start.

  Specifically, in the second embodiment, the auxiliary machine 9 has at least a light, and when the light is operating, the illuminance of the surrounding environment in the hybrid vehicle 100 (hereinafter, referred to as “environmental illuminance” as appropriate). ) Is low, the characteristic change predetermined value (that is, the luminance change predetermined value) used for the light is made smaller than when the ambient illuminance is high. In other words, the lower the ambient illuminance, the smaller the DC / DC voltage change amount for the light. In this case, if the DC / DC voltage change amount is decreased, the upper limit of the change range tends to be reduced. Therefore, the finally set starting DC / DC voltage target lower limit value tends to increase as the ambient illuminance decreases. .

  Basically, the control according to the second embodiment is also applied to the hybrid vehicle 100 shown in FIG. That is, the control according to the second embodiment is also executed by the ECU 20. Also, the configuration and control not specifically described here are the same as those in the first embodiment.

  With reference to FIG. 7, the reason why the control according to the environmental illuminance is performed as described above will be specifically described. In FIG. 7, the horizontal axis shows the amount of change in the brightness of the light at the time of starting the engine (which is caused by the change in the voltage of the light), and the vertical axis shows the sensory effect (in other words, the sensory effect on the change in the light brightness). Impact). FIG. 7 illustrates the relationship between the amount of change in light luminance and the sensory effect for two cases, when the ambient illuminance is low (dark) and when the ambient illuminance is high (bright). As the environmental illuminance, a detection value of an environmental illuminometer configured to detect the environmental illuminance is used. This environmental illuminance meter is mounted on the hybrid vehicle 100.

  As shown in FIG. 7, it can be seen that the sensory influence on the change in light luminance changes depending on the ambient illuminance. That is, it can be seen that the change in the light luminance with respect to the voltage change changes that the human being feels as a sensuality depending on the ambient illumination outside the hybrid vehicle 100. Specifically, it can be seen that the lower the ambient illuminance, the greater the sensory effect due to the change in light luminance. Therefore, it can be said that the lower the ambient illuminance, the more easily the change in the light luminance gives the driver and other vehicles a sense of incongruity.

  Therefore, in the second embodiment, in order to suppress the change in the sensory influence on the light luminance change caused by the environmental illuminance, when the light is on, the ECU 20 decreases the luminance change predetermined value as the environmental illuminance decreases. Make it smaller. In other words, the ECU 20 decreases the DC / DC voltage change amount for the light, which is used to obtain the upper limit of the change width, as the ambient illuminance is lower. That is, the ECU 20 decreases the difference (corresponding to the change width upper limit) between the starting DC / DC voltage target lower limit value and the current DC / DC voltage as the ambient illuminance is lower. The ECU 20 acquires the environmental illuminance detected by the environmental illuminance meter and performs the above-described processing based on the acquired environmental illuminance.

  A specific example of control in the second embodiment will be described with reference to FIG. FIG. 8A shows the DC / DC voltage on the horizontal axis and the light luminance on the vertical axis. FIG. 8A illustrates an example in which the luminance change predetermined value indicated by reference numeral 81 is used when the environmental illuminance is low, and the luminance change predetermined value indicated by reference numeral 82 is used when the environmental illuminance is high. The predetermined luminance change value 81 used when the environmental illuminance is low is smaller than the predetermined luminance change value 82 used when the environmental illuminance is high. In addition, by performing an experiment or the like in advance, a predetermined luminance change value to be used according to the ambient illuminance is obtained. Then, the relationship between the environmental illuminance thus obtained and the luminance change predetermined value to be used is stored in a memory or the like, and the ECU 20 corresponds to the environmental illuminance detected by the environmental illuminometer based on the relationship stored in the memory. Set the brightness change to a predetermined value.

  In the example shown in FIG. 8A, the ECU 20 obtains the DC / DC voltage change amount ΔVDC_B1 corresponding to the luminance change predetermined value 81 from the graph 80 when the environmental illuminance is low, and when the environmental illuminance is high, A DC / DC voltage change amount ΔVDC_B2 corresponding to the luminance change predetermined value 82 is obtained from the graph 80. The DC / DC voltage change amount ΔVDC_B1 used when the environmental illuminance is low is smaller than the DC / DC voltage change amount ΔVDC_B2 used when the environmental illuminance is high. After obtaining the DC / DC voltage change amount ΔVDC_B in this way, the ECU 20 sets the upper limit of the change range based on the DC / DC voltage change amount by the same method as in the first embodiment, and the change range. A DC / DC voltage target lower limit value at start is set based on the upper limit.

  Here, it is not limited to obtaining the DC / DC voltage change amount from the luminance change predetermined value changed according to the environmental illuminance as described above, and the DC / DC voltage change amount changed according to the environmental illuminance is calculated. It is also possible to directly obtain the DC / DC voltage change amount from the ambient illuminance. An example of this is shown in FIG. In FIG. 8B, the horizontal axis indicates the ambient illuminance, and the vertical axis indicates the DC / DC voltage change amount for the light. From this, it can be seen that the lower the environmental illuminance, the more the DC / DC voltage change amount having a smaller value is obtained. The relationship between the ambient illuminance and the DC / DC voltage change amount as shown in FIG. 8B is obtained in advance through experiments and stored in a memory or the like. The ECU 20 obtains a DC / DC voltage change amount corresponding to the environmental illuminance detected by the environmental illuminometer based on the relationship stored in the memory.

  According to the second embodiment described above, it is possible to appropriately suppress the change in the sensory influence on the light luminance change caused by the environmental illuminance. Specifically, it is possible to appropriately suppress a sense of discomfort due to a change in light luminance that may occur when the ambient illuminance is low.

  Further, according to the second embodiment, when the environmental illuminance is high, the luminance change predetermined value is increased and the DC / DC voltage change amount for the light tends to be larger than when the environmental illuminance is low. is there. Therefore, it can be said that when the environmental illuminance is high, the finally set starting DC / DC voltage target lower limit tends to be small. Therefore, according to the second embodiment, it is possible to efficiently reduce the starting power when the environmental illuminance is high.

<Third Embodiment>
Next, a third embodiment will be described. The third embodiment is the same as the second embodiment in that the characteristic change predetermined value is changed based on a factor that changes the characteristic change of the auxiliary machine 9 that is felt as a human sensation. However, in the second embodiment, the characteristic change predetermined value (brightness change predetermined value) used for the light is changed according to the ambient illuminance, but in the third embodiment, the air conditioner is changed according to the vehicle speed of the hybrid vehicle 100. The characteristic change predetermined value to be used (air flow change predetermined value) is changed. Specifically, in the third embodiment, when the air conditioner is operating, when the vehicle speed is low, the air flow change predetermined value used for the air conditioner is made smaller than when the vehicle speed is high. In other words, the lower the vehicle speed, the smaller the DC / DC voltage change amount for the air conditioner. In this case, if the DC / DC voltage change amount is reduced, the upper limit of the change width tends to be reduced, so that the finally set starting DC / DC voltage target lower limit value tends to increase as the vehicle speed decreases.

  Basically, the control according to the third embodiment is also applied to the hybrid vehicle 100 shown in FIG. That is, the control according to the third embodiment is also executed by the ECU 20. Also, the configuration and control not specifically described here are the same as those in the first embodiment.

  The reason why the control according to the vehicle speed is performed as described above will be specifically described with reference to FIG. In FIG. 9, the horizontal axis shows the amount of change in the air-conditioner air volume at engine startup (which is caused by the voltage fluctuation of the air-conditioner), and the vertical axis shows the sensory effect (in other words, the sensory effect on the air-conditioner air volume change). ). FIG. 9 exemplifies the relationship between the air-conditioner air volume change amount and the sensory effect in two cases of low vehicle speed and high vehicle speed.

  As shown in FIG. 9, it can be seen that the sensory influence on the air-conditioner air volume change varies depending on the vehicle speed. That is, it can be seen that the change in the air volume of the air conditioner with respect to the voltage fluctuation changes depending on the vehicle speed. Specifically, it can be seen that the lower the vehicle speed, the greater the sensory effect due to the change in air-conditioner air volume. Therefore, it can be said that the lower the vehicle speed, the more easily the air conditioner air volume change gives the passenger a sense of incongruity. This is because the change in air-conditioning air volume affects the human body as noise, but the traveling noise is relatively small at low vehicle speeds, so the noise due to the air-conditioning air volume change is not lost by the traveling noise. Conversely, the higher the vehicle speed, the smaller the sensory effect due to the change in the air-conditioner air volume. This is because the traveling noise becomes large at high vehicle speeds, and the noise due to the change in the air volume of the air conditioner is lost by the traveling noise.

  From the above, in the third embodiment, in order to suppress the change in the sensory influence on the air conditioner air volume change caused by the vehicle speed, the ECU 20 reduces the air volume change predetermined value as the vehicle speed decreases when the air conditioner is on. The air flow change predetermined value is increased as the vehicle speed increases. In other words, the ECU 20 decreases the DC / DC voltage change amount for the air conditioner used for obtaining the upper limit of the change width as the vehicle speed is lower and increases as the vehicle speed is higher. That is, the ECU 20 decreases the difference between the DC / DC voltage target lower limit value at the start and the current DC / DC voltage (corresponding to the upper limit of the change range) as the vehicle speed decreases, and the DC / DC at the start increases as the vehicle speed increases. Increase the difference between the target voltage lower limit and the current DC / DC voltage. In addition, ECU20 acquires the vehicle speed which the vehicle speed sensor detected, and performs the above-mentioned process based on the acquired vehicle speed.

  A specific example of control in the third embodiment will be described with reference to FIG. In FIG. 10A, the horizontal axis represents the DC / DC voltage, and the vertical axis represents the air conditioner air volume. FIG. 10A shows an example in which the predetermined airflow change value indicated by reference numeral 91 is used when the vehicle speed is low, and the predetermined airflow change value indicated by reference numeral 92 is used when the vehicle speed is high. The predetermined airflow change value 91 used when the vehicle speed is low is smaller than the predetermined airflow change value 92 used when the vehicle speed is high. It should be noted that by performing an experiment or the like in advance, an airflow change predetermined value to be used according to the vehicle speed is obtained. Then, the relationship between the vehicle speed thus obtained and the predetermined airflow change predetermined value to be used is stored in a memory or the like, and the ECU 20 changes the airflow corresponding to the vehicle speed detected by the vehicle speed sensor based on the relationship stored in the memory. Set to a predetermined value.

  In the example shown in FIG. 10A, when the vehicle speed is low, the ECU 20 obtains the DC / DC voltage change amount ΔVDC_A1 corresponding to the predetermined airflow change value 91 from the graph 90, and when the vehicle speed is high, the graph 90 Further, a DC / DC voltage change amount ΔVDC_A2 corresponding to the air flow change predetermined value 92 is obtained. The DC / DC voltage change amount ΔVDC_A1 used when the vehicle speed is low is smaller than the DC / DC voltage change amount ΔVDC_A2 used when the vehicle speed is high. After obtaining the DC / DC voltage change amount ΔVDC_A in this way, the ECU 20 sets the upper limit of the change width based on the DC / DC voltage change amount by the same method as in the first embodiment, and the change width. A DC / DC voltage target lower limit value at start is set based on the upper limit.

  Here, the present invention is not limited to obtaining the DC / DC voltage change amount from the predetermined value of the change in air volume that is changed according to the vehicle speed as described above, and the DC / DC voltage change amount that is changed according to the vehicle speed is used. The DC / DC voltage change amount may be obtained directly from the vehicle speed. An example of this is shown in FIG. In FIG. 10B, the horizontal axis represents the vehicle speed, and the vertical axis represents the DC / DC voltage change amount for the air conditioner. From this, it can be seen that the lower the vehicle speed, the smaller the DC / DC voltage change amount is obtained, and the higher the vehicle speed, the greater the DC / DC voltage change amount. The relationship between the vehicle speed and the DC / DC voltage change amount as shown in FIG. 10B is obtained by conducting an experiment in advance and stored in a memory or the like. ECU20 calculates | requires the DC / DC voltage variation | change_quantity corresponding to the vehicle speed which the vehicle speed sensor detected based on the relationship memorize | stored in the said memory.

  According to 3rd Embodiment described above, the change of the sensory influence with respect to the air-conditioner air volume change resulting from a vehicle speed can be suppressed appropriately. Specifically, it is possible to appropriately suppress the uncomfortable feeling caused by the change in the air volume of the air conditioner that can occur when the vehicle speed is low.

  Further, according to the third embodiment, when the vehicle speed is high, the air volume change predetermined value is increased and the DC / DC voltage change amount for the air conditioner tends to be increased as compared with the case where the vehicle speed is low. Therefore, it can be said that when the vehicle speed is high, the finally set starting DC / DC voltage target lower limit tends to be small. Therefore, according to the third embodiment, it is possible to efficiently reduce the starting power when the vehicle speed is high.

In addition, you may implement combining 2nd Embodiment mentioned above and 3rd Embodiment. Specifically, as shown in the second embodiment, the predetermined luminance change value may be changed according to the ambient illuminance, and the predetermined air flow change value may be changed according to the vehicle speed. In other words, the DC / DC voltage change amount used for the light may be changed according to the ambient illuminance, and the DC / DC voltage change amount used for the air conditioner may be changed according to the vehicle speed. By doing so, it is possible to appropriately set the DC / DC voltage target lower limit value at the start in consideration of the environmental illuminance and the vehicle speed. Therefore, it is possible to more effectively suppress the occurrence of a sense of incongruity due to the characteristic change, and it is possible to efficiently reduce the starting power.
[Modification]
The present invention is not limited to application to a hybrid vehicle, and can be applied to various vehicles configured to start an engine by driving a motor with battery power.

  Further, the embodiments are not limited to the above-described embodiments, and can be appropriately changed without departing from the spirit or concept of the invention that can be read from the claims and the entire specification.

1 Engine 4 Power split mechanism 5 Inverter 6 Main battery 7 DC / DC converter 8 Auxiliary battery 9 Auxiliary machine 20 ECU
MG1 first motor generator MG2 second motor generator 100 hybrid vehicle

Claims (5)

Applied to a vehicle having an internal combustion engine, a motor for starting the internal combustion engine using electric power of a battery, and an auxiliary machine having a characteristic that an operation state changes depending on a voltage;
An auxiliary battery that outputs a power supply voltage lower than the battery and drives the auxiliary machine;
A voltage converter connected to the battery and the auxiliary battery and performing voltage conversion;
Voltage target lower limit value setting means for changing a lower limit value to be set for the voltage target value of the voltage converter according to whether or not the auxiliary machine is operating at the time of starting the internal combustion engine. A power supply control device for a vehicle.   2. The vehicle power supply control device according to claim 1, wherein the voltage target lower limit value setting means increases the lower limit value when the auxiliary machine is operating as compared with a case where the auxiliary machine is not operating. . The auxiliary machine has a light,
The voltage target lower limit setting means is configured such that when the light is operating, the lower limit value and the current voltage in the voltage converter are compared with the case where the illuminance of the surrounding environment is low and the illuminance is high. The power supply control device for a vehicle according to claim 1 or 2, wherein the difference is reduced. The auxiliary machine has an air conditioner,
The voltage target lower limit value setting means calculates a difference between the lower limit value and the current voltage in the voltage converter when the air conditioner is operating, when the vehicle speed is low, and when the vehicle speed is high. The power supply control device for a vehicle according to any one of claims 1 to 3, wherein the power supply control device is reduced.   5. The voltage target lower limit value setting unit sets the lower limit value so that a characteristic change of the auxiliary machine is equal to or less than a predetermined value when the auxiliary machine is operating. The vehicle power supply control device according to item.

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