JP6079725B2 - Vehicle power supply control device - Google Patents

Description

  The technology disclosed herein relates to a vehicle power supply control device.

  In recent years, from the viewpoint of improving the fuel efficiency of a vehicle, an increasing number of vehicles adopt a so-called deceleration regeneration system that reduces the burden on the engine by generating power intensively when the vehicle is decelerated.

  In vehicles that employ a deceleration regeneration system, in order to charge a large amount of power generated during deceleration in a short time, apart from the lead battery (first power storage device) that has been widely used, In many cases, a lithium ion battery or an electric double layer capacitor (second power storage device) capable of rapid charge / discharge is mounted (see, for example, Patent Document 1). By mounting two types of power storage devices having different characteristics, it is possible to secure a sufficiently large charge capacity while recovering the electric power generated during deceleration without waste.

  In Patent Document 1, an electrical load is connected to the first power storage device, a generator is connected to the second power storage device, and a voltage converter and a bypass relay are connected between the first power storage device and the second power storage device. When the configuration provided in parallel is adopted and the state in which the output current of the voltage converter exceeds the predetermined value continues for a predetermined time or more in the interruption state of the bypass relay, the potential difference between the first power storage device and the second power storage device is a predetermined value. There is further disclosed a technique for switching the bypass relay from the cut-off state to the connected state when it is contracted to the following.

JP 2013-119331 A

  A bypass relay having a mechanical contact is desired to reduce the number of on / off times in consideration of its durability. In order to reduce the number of times the bypass relay is turned on / off, the delay control as described in Patent Document 1 is performed when the bypass relay is switched from the cut-off state to the connected state when the output current of the voltage converter exceeds a threshold value. It is effective to introduce. This is because if the load is reduced during the delay time and the output current of the voltage converter becomes less than the threshold value, it is not necessary to switch the bypass relay from the disconnected state to the connected state. However, during this delay control, it is necessary to supply the required current from the voltage converter to the electric load, and quick switching is required for switching the bypass relay.

  The technology disclosed herein enables a high-current output of a voltage converter to be maintained in a vehicle power supply control device equipped with two types of power storage devices, and achieves quick switching of a bypass relay after a delay. Objective.

  The technique disclosed here continues by preliminarily reducing the potential difference between the first power storage device and the second power storage device by actively discharging the second power storage device in the connection preparation mode with delay control. In the connection execution mode, the bypass relay is quickly switched from the cutoff state to the connected state.

  More specifically, the technology disclosed herein enables a generator that is driven by an engine to generate electricity, a first power storage device connected to an electrical load, and charge / discharge faster than the first power storage device. A second power storage device that is directly charged by the generator, a voltage converter that steps down the voltage of the second power storage device and supplies the second power storage device to the first power storage device and the electrical load, a generator, the second power storage device, and the first This is a technique for a vehicle power supply control device including a bypass relay that switches connection and disconnection between a power storage device and an electric load, and a control unit that controls operations of a generator, a voltage converter, and the bypass relay. The control unit executes the connection execution mode control after executing the connection preparation mode control for a certain period of time when the output current of the voltage converter becomes equal to or greater than the threshold value due to the electric load in the cutoff state of the bypass relay. Configured. In the connection preparation mode, the control unit discharges the second power storage device to the set potential difference with respect to the first power storage device, and waits for a predetermined time while adjusting the power generation of the generator so as to maintain the set potential difference. Perform delay control. Further, in the connection execution mode, the control unit adjusts the power generation of the generator so as to reduce the potential difference between the first power storage device and the second power storage device to a predetermined value or less, and then switches the bypass relay from the cutoff state to the connected state. To control.

  According to this configuration, by setting the delay time before switching, it is possible to reduce the switching frequency of the bypass relay to the line, and it is possible to suppress a decrease in durability of the contact type relay and to restart power generation during delay control By maintaining the voltage, a high current output can be maintained even during delay control.

  The control unit maintains the potential difference between the first power storage device and the second power storage device in the connection preparation mode with the first potential difference, and controls the potential difference between the first power storage device and the second power storage device in the connection execution mode. Control may be performed so that the bypass relay is switched from the disconnected state to the connected state after being reduced to a smaller second potential difference.

  According to this configuration, it is possible to quickly switch to the bypass relay side line after the delay while maintaining a high current output from the voltage converter during the delay control.

  Further, the control unit may set the target voltage of the second power storage device in the connection preparation mode to be higher than the target voltage of the second power storage device in the connection execution mode.

  According to this configuration, during delay control, the target voltage of the second power storage device is increased to facilitate the maintenance of the high current output of the voltage converter, and at the time of switching to the bypass relay side, the second power storage device By lowering the target voltage, it is possible to prevent the voltage of the first power storage device from exceeding the upper limit due to a high voltage acting on the first power storage device during switching.

  Further, the control unit may set the target voltage of the first power storage device in the connection preparation mode to be higher than the target voltage of the first power storage device in the connection execution mode.

  According to this configuration, during delay control, the second power storage device can be discharged quickly by increasing the target voltage of the first power storage device, and the target voltage of the first power storage device can be set when switching to the bypass relay side. By lowering, it is possible to prevent the voltage of the first power storage device from exceeding the upper limit due to the potential difference at the time of switching.

  In addition, the control unit may control to end the delay control and immediately shift to the connection execution mode when the voltage of the first power storage device becomes a predetermined value or less in the connection preparation mode.

  According to this configuration, it is possible to prevent the first power storage device from deteriorating due to the voltage drop of the first power storage device due to excessive delay.

  Further, the control unit may perform control so as to end the delay control and immediately shift to the connection execution mode when the temperature of the voltage converter becomes a predetermined value or more in the connection preparation mode.

  According to this configuration, it is possible to prevent thermal damage to the voltage converter due to excessive delay.

  According to the technology disclosed herein, in the delay control of the bypass relay in the vehicle power supply control device equipped with two types of power storage devices, the voltage converter can maintain a high current output and the bypass after delay Fast switching of relays can be achieved.

It is a circuit diagram which shows the electric constitution of the power supply control device for vehicles. It is a block diagram which shows the connection of a control system. It is a flowchart which shows the procedure of the control performed at the time of switching from the interruption | blocking state of a bypass relay to a connection state. It is a time chart for demonstrating operation | movement of each part at the time of switching from the interruption | blocking state of a bypass relay to a connection state.

  Hereinafter, exemplary embodiments will be described in detail with reference to the drawings.

(1) Overall Configuration of Vehicle FIG. 1 is a circuit diagram showing an electrical configuration of a vehicle power supply control device. The vehicle shown in FIG. 1 has an alternator 1 that generates power by generating power from a diesel engine (not shown) provided in an engine room (hereinafter also referred to simply as an engine), and is electrically connected to the alternator 1. The battery 2 and the capacitor 3 that store the generated power, the DC / DC converter 4 that steps down the power generated by the alternator 1, the electric load 5 that includes various electrical components that consume power, and the engine that is driven when the engine is started. And a starter 6 for cranking the engine. The alternator 1 corresponds to a “generator” in the claims, the battery 2 corresponds to a “first power storage device” in the claims, and the capacitor 3 corresponds to a “second power storage device” in the claims. The DC / DC converter 4 corresponds to a “voltage converter” in the claims.

  The alternator 1 generates power by rotating a rotor that rotates in conjunction with the output shaft of an engine in a magnetic field. The alternator 1 has a range of up to 25 V depending on the increase or decrease of the current applied to the field coil that generates the magnetic field. It is possible to adjust the generated power. The alternator 1 also includes a rectifier (not shown) that converts the generated AC power into DC power. That is, the electric power generated by the alternator 1 is converted into direct current by this rectifier and then transmitted to each part.

  The battery 2 is a lead battery having a nominal voltage of 12 V, which is a common power storage device for vehicles. Since such a battery 2 stores electrical energy by a chemical reaction, it is not suitable for rapid charge / discharge, but has a characteristic that it can store a relatively large amount of power because it easily secures a charge capacity. There is.

  The capacitor 3 has a large capacity by connecting a plurality of electric double layer capacitors (EDLC), and can be charged up to 25V. Unlike the battery 2, the capacitor 3 stores electricity by physical adsorption of electrolyte ions, and therefore has a characteristic that it can be charged / discharged relatively quickly and has low internal resistance.

  The DC / DC converter 4 is of a switching type in which a voltage is changed by ON / OFF (switching operation) of a built-in switching element. In the present embodiment, the DC / DC converter 4 is configured to switch the voltage of power supplied from the alternator 1 or the capacitor 3 side to the electric load 5 or the battery 2 side (that is, from the left side to the right side in the figure) by a switching operation. It has a function to step down the voltage, but other functions such as a function to allow power supply in the opposite direction (that is, from the right side to the left side in the figure) and to increase the voltage are provided. Not done.

  The alternator 1 and the capacitor 3 are connected to each other via a first power supply line 7. A second line 8 branches from the first line 7, and a DC / DC converter 4 is interposed in the middle of the second line 8. A third line 9 branches from the second line 8, and the battery 2 and the second line 8 are connected to each other via the third line 9. A fourth line 10 branches from the third line 9, and the starter 6 and the battery 2 are connected to each other via the fourth line 10.

  A capacitor cutoff relay 12 for interrupting the connection between the alternator 1 and the capacitor 3 is provided at a portion between the branch point of the first line 7 and the second line 8 and the capacitor 3. The capacitor cut-off relay 12 can be switched between an on state (closed: connected state) that permits power supply from the alternator 1 to the capacitor 3 and an off state (open: cut-off state) that cuts off the power supply.

  Further, a bypass line 11 branches from the first line 7 in parallel with the second line 8, and the bypass line 11 is connected to a middle portion of the second line 8 located on the output side of the DC / DC converter 4. Has been. That is, the bypass line 11 connects the alternator 1 and the electric load 5 without using the DC / DC converter 4 and connects the battery 2 and the capacitor 3 without using the DC / DC converter 4. In order to intermittently connect these connections, the bypass line 11 is provided with a bypass relay 13. The bypass relay 13 switches between an on state (closed: connected state) that permits power feeding through the bypass line 11 (bypassing the DC / DC converter 4) and an off state (open: blocked state) that blocks the power feeding. It is possible.

  The electric load 5 includes an air conditioner 22, an audio 23, and the like in addition to an electric power steering mechanism (hereinafter abbreviated as EPAS) 21 that assists a steering operation by a driver with a driving force of an electric motor or the like. Yes. The electric loads such as the EPAS 21, the air conditioner 22, and the audio 23 are supplied to the first line via the second line 8 provided with the DC / DC converter 4 or the bypass line 11 provided with no DC / DC converter 4. 7 is connected.

  Further, the electrical load 5 of the present embodiment includes a glow plug 26 in addition to the electrical load such as the EPAS 21. The glow plug 26 is a heater for warming the combustion chamber of the engine by energization heating when the engine (diesel engine in the present embodiment) is cold started. The glow plug 26 is connected to the battery 2 in parallel with the starter 6. However, the PTC heater 25 is a heater for heating the room by energization heating, and operates stably even at a maximum of 25 V. Therefore, the DC / DC Arranged on the alternator 1 and the capacitor 3 side with respect to the converter 4.

  In addition to the above, in the present embodiment, a charging line 14 that connects the battery 2 and the capacitor 3 is provided. The charging line 14 is interposed between a point on the third line 9 and a point closer to the capacitor 3 than the capacitor cutoff relay 12 in the first line 7. A charging FET 15, which is a semiconductor switch for intermittently connecting the battery 2 and the capacitor 3, is provided on the charging line 14 in series with the resistor 16. The charging FET 15 can be switched between an on state (closed: connected state) that permits power supply from the battery 2 to the capacitor 3 through the charging line 14 and an off state (open: blocked state) that blocks the power supply. Yes. Further, a waste power FET 17 for reducing the voltage of the capacitor 3 is provided between a connection point between the charge FET 15 and the resistor 16 and the ground.

(2) Control System FIG. 2 is a block diagram showing connection of the control system. As shown in the figure, the alternator 1, the DC / DC converter 4, the starter 6, the capacitor cutoff relay 12, the bypass relay 13, the charging FET 15, the waste electric FET 17, the electric load 5 (EPAS 21, air conditioner 22, audio 23,... ) And the like are connected to the controller 30 via various signal lines, and are controlled based on a command from the controller 30. The controller 30 is a microcomputer including a conventionally known CPU, ROM, RAM, and the like, and corresponds to a “control unit” in the claims.

  The controller 30 is connected to various sensors provided in the vehicle via signal lines. Specifically, the vehicle of the present embodiment is provided with a voltage sensor SN1, an operation state detection means SN2, an ignition switch sensor SN3, and other switch detection means SN4, and information detected by these sensors is a controller. 30 are sequentially input.

  The voltage sensor SN1 is a sensor that detects the voltage of the capacitor 3 (capacitor voltage) as shown in FIG.

  The driving state detection means SN2 is a generic term for sensors that detect physical quantities related to the state of the vehicle or engine. For example, a vehicle speed sensor that detects the traveling speed of the vehicle, an engine rotation speed sensor that detects the rotation speed of the engine, and an accelerator pedal. And an accelerator / brake sensor for detecting an operation amount or an operation force of the brake pedal. Based on the input information from the driving state detection means SN2, the controller 30 can obtain information such as whether the vehicle is decelerating or accelerating and the degree of deceleration / acceleration.

  The ignition switch sensor SN3 is a sensor that detects an operation state of an ignition switch (not shown) that is operated by a driver when the engine is started or stopped.

  The other switch detection means SN4 is a generic term for sensors that detect operation states of switches other than the ignition switch, and includes, for example, sensors that detect operation states of operation switches such as an air conditioner and an audio.

  Based on input information from each of the sensors SN1 to SN4, the controller 30 generates power generated by the alternator 1, a step-down operation by the DC / DC converter 4, driving / stopping the electric load 5 and the starter 6, and relays 12 and 13 The on / off operation, the on / off operation of the FETs 15 and 17, and the like are controlled. Hereinafter, a specific example of the control operation by the controller 30 will be described in detail.

(3) Control operation The vehicle power supply control device according to the present embodiment can execute so-called deceleration regeneration control in which power generation is concentrated when the vehicle is decelerated. For this reason, each part of a power supply is controlled as follows by the controller 30 during driving | running | working of a vehicle.

  At the time of deceleration of the vehicle, power generation by the alternator 1 is actively performed, and generated power of 25 V at maximum is generated. The electric power generated by the alternator 1 is stepped down to 12V by the DC / DC converter 4 and then supplied to the electric load 5. Further, surplus power exceeding the power consumption in the electric load 5 is supplied to the capacitor 3 and charged. Since the capacitor 3 can be rapidly charged as already described, surplus power is efficiently recovered by the capacitor 3. However, when the capacitor 3 is already in a fully charged state (25 V), the capacitor 3 cannot be charged any more, so surplus power is sent to charge the battery 2.

  On the other hand, in a driving scene other than when the vehicle is decelerating, power generation by the alternator 1 is suppressed as much as possible in order to reduce the resistance applied from the alternator 1 to the engine. For example, when power generation by the alternator 1 is not performed, power consumption in the electric load 5 is mainly provided by charging power of the capacitor 3. In other words, the maximum 25 V power charged in the capacitor 3 is stepped down to 12 V by the DC / DC converter 4 and then supplied to the electric load 5. However, when the capacitor voltage is not sufficiently high, or when the power consumption at the electric load 5 is relatively large, the power consumption at the electric load 5 cannot be covered only by the charging power of the capacitor 3. Therefore, in such a case, the power generation by the alternator 1 is performed to the minimum necessary, and the power generated by the alternator 1 is used, and the power discharged from the battery 2 is also used as necessary. . By such control, the charging power of the capacitor 3 while the vehicle is traveling is always kept above a certain level. In the present embodiment, charging / discharging of the capacitor 3 is controlled so that the capacitor voltage falls within the range of 12 to 25V.

  As described above, in this embodiment, power is supplied mainly from the alternator 1 to the electric load 5 through the DC / DC converter 4 when the vehicle is decelerated, and from the capacitor 3 through the DC / DC converter 4 except when the vehicle is decelerated. Electric power is supplied to the load 5. For this reason, during traveling of the vehicle, in principle, power feeding through the bypass line 11 is not performed, and the capacitor 3 is not disconnected from the first line 7. For this reason, the bypass relay 13 is always maintained in the cutoff state, and the capacitor cutoff relay 12 is always maintained in the connected state.

  However, if the time during which the output current of the DC / DC converter 4 exceeds a predetermined value becomes longer due to a change in the state of the electric load 5, heating of the DC / DC converter 4 becomes a problem. Therefore, in the case of such an overload, it is necessary to switch the power supply line from the second line 8 of the DC / DC converter 4 to the bypass line 11 by switching the bypass relay 13 from the disconnected state to the connected state. . However, the bypass line 11 cannot be switched to the connected state in a state where the potential difference between the battery 2 and the capacitor 3 is large. Therefore, in the present embodiment, the following control is performed when switching from the second line 8 to the bypass line 11.

  FIG. 3 is a flowchart illustrating a control procedure performed when the bypass relay 13 is switched from the cutoff state to the connected state.

  In step S1, the controller 30 reads the voltage of the capacitor 3, that is, the capacitor voltage Vcap, reads the voltage of the battery 2, that is, the battery voltage Vbat, reads the vehicle load state, and the output current Iout of the DC / DC converter 4. And reading of the generated current Ialt of the alternator 1 are executed.

  In step S2, the controller 30 determines whether or not the overcurrent state in which the output current Iout of the DC / DC converter 4 is equal to or greater than the threshold value I0 has continued for several seconds (for example, 5 seconds). Here, the threshold value I0 is, for example, 75A. If NO, the process returns to step S1, and if YES, the process proceeds to step S3.

  In step S3, the controller 30 resets and starts an internal timer.

  In step S4, the controller 30 sets the capacitor target voltage Vcap1 to a voltage higher by α1 than the battery target voltage Vbat1. Here, α1 is a value close to the lowest potential difference at which the DC / DC converter 4 can maintain a high current output, for example, 3V.

  In step S5, the controller 30 controls the power generation of the alternator 1 so that the voltage of the capacitor 3 maintains the capacitor target voltage Vcap1.

  In step S6, the controller 30 determines whether several tens of seconds (for example, 30 seconds) have elapsed since the start of the timer in step S3. If NO, the process proceeds to step S7. If YES, the process proceeds to step S9.

  In step S7, the controller 30 determines whether the output current Iout of the DC / DC converter 4 is equal to or greater than a predetermined value I1 (> I0) or whether the battery voltage Vbat is equal to or less than a predetermined value Vbat3 (<Vbat2: described later). If NO, the process proceeds to step S8, and if YES, the process proceeds to step S9. Note that the controller 30 may determine in step S7 whether the temperature of the DC / DC converter 4 is equal to or higher than a predetermined value. If NO, the controller 30 may proceed to step S8, and if YES, the controller 30 may proceed to step S9.

  In step S8, the controller 30 determines whether or not the overcurrent state in which the output current Iout of the DC / DC converter 4 is equal to or greater than the threshold value I0 is continued. If YES, the process returns to step S5. If NO, the process is terminated without bringing the bypass relay 13 into a connected state. Here, the fact that the bypass relay 13 is not connected means that the number of on / off operations of the bypass relay 13 can be reduced.

  In step S9, the controller 30 sets the capacitor target voltage Vcap2 to a voltage higher by α2 (<α1) than the battery target voltage Vbat2 (<Vbat1). Here, α2 is 1V, for example.

  In step S10, the controller 30 controls the power generation of the alternator 1 so that the voltage of the capacitor 3 maintains the capacitor target voltage Vcap2.

  The controller 30 ends the process after switching the bypass relay 13 from the disconnected state to the connected state in step S11.

  FIG. 4 is a time chart for explaining the operation of each part when the bypass relay 13 is switched from the cutoff state to the connected state. The controller 30 executes connection preparation mode control for 30 seconds from time t0 to time t2, and controls connection execution mode from time t2 to time t3.

  When the overcurrent state in which the output current of the DC / DC converter 4 is 75 A or more continues for 5 seconds, a connection request for the bypass relay 13 is issued at time t0. From this time t0, the time measurement for 30 seconds by the timer starts. On the other hand, the controller 30 increases the target voltage of the battery 2 at time t0 and sets the target voltage of the capacitor 3 to a voltage higher by 3V than the battery target voltage. Along with this, the voltage of the battery 2 increases and the voltage of the capacitor 3 decreases due to the discharge through the DC / DC converter 4.

  When the voltage of the capacitor 3 reaches a capacitor target voltage that is 3V higher than the battery target voltage at time t1, the controller 30 covers the current consumption while maintaining the potential difference (= 3V) between the battery 2 and the capacitor 3. The power generation of the alternator 1 is adjusted.

  When 30 seconds elapse from time t0 and time t2 is reached, the controller 30 lowers the target voltage of the battery 2 and sets the target voltage of the capacitor 3 to a voltage higher by 1V than the battery target voltage. Along with this, the output current of the DC / DC converter 4 is also lowered by greatly reducing the generated current of the alternator 1, and as a result, the battery 2 is taken out and the voltage of the battery 2 is lowered. It descends due to the discharge through the DC / DC converter 4.

  At time t3, the potential difference between the battery 2 and the capacitor 3 is 1V, and the bypass relay 13 is switched from the cut-off state to the connected state. At the same time, the operation of the DC / DC converter 4 is applied only to the temperature sensor (not shown). And the output current becomes very small. After the bypass relay 13 is in the connected state, the potential difference between the battery 2 and the capacitor 3 becomes 0 V, and the potential becomes the same as the normal generated voltage of the alternator 1.

(4) Operation As described above, in this embodiment, the alternator 1 that is driven by the engine to generate electric power, the battery 2 connected to the electric load 5, and the alternator that can be charged and discharged more rapidly than the battery 2 are used. The capacitor 3 that is directly charged by 1, the DC / DC converter 4 that steps down the voltage of the capacitor 3 and supplies it to the battery 2 and the electric load 5, and the connection between the alternator 1 and capacitor 3, the battery 2, and the electric load 5, In a vehicular power supply control device including a bypass relay 13 that switches off, a controller 30 that controls the operation of the alternator 1, the DC / DC converter 4, and the bypass relay 13, the controller 30 is in a cut-off state of the bypass relay 13. The output current Iout of the DC / DC converter 4 is changed to the threshold value I0 by the electric load 5. In this case, the connection execution mode control is executed after the connection preparation mode control is executed for a certain period of time. In the connection preparation mode, the controller 30 discharges the capacitor 3 to the set potential difference α1 with respect to the battery 2, and adjusts the power generation of the alternator 1 so as to maintain the set potential difference α1 and waits for a predetermined time to elapse. Is executed (steps S3 to S8). In the connection execution mode, the controller 30 adjusts the power generation of the alternator 1 so as to reduce the potential difference between the battery 2 and the capacitor 3 to a predetermined value α2 or less, and switches the bypass relay 13 from the cutoff state to the connected state. Control (steps S9 to S11).

  According to this configuration, by setting the delay time before switching, it is possible to reduce the switching frequency of the bypass relay 13 to the line, so that it is possible to suppress a decrease in durability of the contact relay, and the alternator 1 during delay control. The high current output can be maintained even during the delay control by restarting the power generation and maintaining the voltage.

  Further, the controller 30 maintains the potential difference between the battery 2 and the capacitor 3 at the first potential difference α1 in the connection preparation mode (step S5), and the potential difference between the battery 2 and the capacitor 3 is smaller than the first potential difference α1 in the connection execution mode. After the voltage is reduced to the second potential difference α2, the bypass relay 13 is controlled to be switched from the disconnected state to the connected state (steps S10 and S11).

  According to this configuration, a high-current output from the DC / DC converter 4 can be maintained during the delay control, and the switching to the line on the bypass relay 13 side after the delay can be quickly performed.

  Further, the controller 30 sets the target voltage Vcap1 of the capacitor 3 in the connection preparation mode to be higher than the target voltage Vcap2 of the capacitor 3 in the connection execution mode (steps S4 and S9).

  According to this configuration, during delay control, the target voltage Vcap1 of the capacitor 3 is increased so that the high current output of the DC / DC converter 4 can be easily maintained, and at the time of switching to the bypass relay 13 side, By lowering the target voltage Vcap2, it is possible to prevent the high voltage from acting on the battery 2 at the time of switching and the voltage of the battery 2 from exceeding the upper limit value.

  Further, the controller 30 sets the target voltage Vbat1 of the battery 2 in the connection preparation mode to be higher than the target voltage Vbat2 of the battery 2 in the connection execution mode (steps S4 and S9).

  According to this configuration, the capacitor 3 can be discharged quickly by increasing the target voltage Vbat1 of the battery 2 during the delay control, and the target voltage Vbat2 of the battery 2 is decreased when switching to the bypass relay 13 side. The voltage of the battery 2 can be prevented from exceeding the upper limit due to the potential difference between the battery 2 and the capacitor 3 at the time of switching.

  In addition, when the voltage of the battery 2 becomes equal to or lower than the predetermined value Vbat3 in the connection preparation mode, the controller 30 controls to end the delay control and immediately shift to the connection execution mode (step S7).

  According to this configuration, it is possible to prevent the deterioration of the battery 2 due to the voltage drop of the battery 2 due to excessive delay.

  Further, the controller 30 controls to end the delay control and immediately shift to the connection execution mode when the temperature of the DC / DC converter 4 exceeds a predetermined value in the connection preparation mode.

  According to this configuration, it is possible to prevent thermal damage to the DC / DC converter 4 due to excessive delay.

(5) Modified Example In the above embodiment, the capacitor 3 composed of a plurality of electric double layer capacitors (EDLC) is used as the power storage device (second power storage device referred to in the claims) that can be charged and discharged more rapidly than the battery 2. However, it is also possible to use a power storage device other than the capacitor 3 as the second power storage device. One example is a lithium ion capacitor. Unlike the electric double layer capacitor, the lithium ion capacitor further improves the energy density by using a carbon-based material capable of electrochemically occluding lithium ions as the negative electrode. It is also called a hybrid capacitor because the charge / discharge principle is different (a chemical reaction is used in combination).

  In the above embodiment, the case where the technology disclosed herein is applied to a vehicle equipped with a diesel engine has been described as an example. However, the technology disclosed herein is an engine other than a diesel engine (for example, a gasoline engine). Naturally, it can also be applied to a vehicle equipped with a).

  Further, in the above embodiment, the alternator 1 is used as a generator that generates power by obtaining power from the engine. However, not only power generation but also engine torque assist (operation for adding torque to the engine output shaft) can be performed. A possible electric motor (motor generator) may be used as a generator. That is, the technique disclosed here can be applied not only to a conventional vehicle in which only the engine is a power source, but also to a hybrid vehicle using both an engine and an electric motor.

  As described above, the technology disclosed herein is useful as a vehicle power supply control device.

1 Alternator (generator)
2 Battery (first power storage device)
3 Capacitor (second power storage device)
4 DC / DC converter (voltage converter)
5 Electric load 6 Starter 7 First line 8 Second line 9 Third line 10 Fourth line 11 Bypass line 12 Capacitor cutoff relay 13 Bypass relay 14 Charging line 15 Charging FET
16 Resistance 17 Waste FET
30 controller (control unit)
SN1 Voltage sensor SN3 Ignition switch sensor

Claims (6)

A generator driven by an engine to generate electricity;
A first power storage device connected to the electrical load;
A second power storage device that can be charged and discharged more rapidly than the first power storage device and is directly charged by the generator;
A voltage converter that steps down the voltage of the second power storage device and supplies the voltage to the first power storage device and the electrical load;
A bypass relay that switches connection and disconnection between the generator, the second power storage device, the first power storage device, and the electric load;
A vehicle power supply control device comprising a controller that controls operations of the generator, the voltage converter, and the bypass relay,
When the output current of the voltage converter becomes equal to or greater than a threshold value due to the electrical load in the shut-off state of the bypass relay, the control unit performs control of the connection execution mode after executing the control of the connection preparation mode for a certain period of time. Is configured to run
In the connection preparation mode, the control unit discharges the second power storage device to the set potential difference with respect to the first power storage device, and adjusts the power generation of the generator to maintain the set potential difference. Execute delay control to wait for the passage of time,
In the connection execution mode, the control unit adjusts the power generation of the generator so as to reduce the potential difference between the first power storage device and the second power storage device to a predetermined value or less, and then switches the bypass relay from the cutoff state. A power supply control device for a vehicle, wherein control is performed so as to switch to a connected state. In the vehicle power supply control device according to claim 1,
The control unit maintains a potential difference between the first power storage device and the second power storage device at a first potential difference in the connection preparation mode, and between the first power storage device and the second power storage device in the connection execution mode. A power supply control device for a vehicle, wherein after the potential difference is reduced to a second potential difference smaller than the first potential difference, the bypass relay is controlled to be switched from a cutoff state to a connected state. In the vehicle power supply control device according to claim 2,
The control unit sets the target voltage of the second power storage device in the connection preparation mode to be higher than the target voltage of the second power storage device in the connection execution mode. In the vehicle power supply control device according to claim 2 or 3,
The control unit sets the target voltage of the first power storage device in the connection preparation mode to be higher than the target voltage of the first power storage device in the connection execution mode. In the vehicle power supply control device according to claim 2,
The control unit controls to end the delay control and immediately shift to the connection execution mode when the voltage of the first power storage device becomes a predetermined value or less in the connection preparation mode. A vehicle power supply control device. In the vehicle power supply control device according to claim 2,
The control unit performs control so that when the temperature of the voltage converter becomes equal to or higher than a predetermined value in the connection preparation mode, the delay control is terminated and the mode is immediately shifted to the connection execution mode. A vehicle power supply control device.

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