JP2010006335A - Vehicular power supply control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicular power supply control device having improved startability when applying a high voltage load for a starter or the like at a low temperature. <P>SOLUTION: The vehicular power supply control device comprises: a battery for high voltage connected to a high voltage load; a voltage step-down means, in which input is connected to a contact point between the battery for high voltage and high voltage load, and which lowers input voltage to output a low voltage load; a temperature detecting means that detects the temperature of the battery for high voltage; an operation detecting means that detects a starting operation of the high voltage load; an electric storage means that accumulates voltage; and a control means that connects the electric storage means to the contact point and supplies a drive power obtained from the voltage stored in the electric storage means to the high voltage load therefrom, when the operation detecting means has detected a starting operation, and the detected temperature indicated by the temperature detecting means is found lower than the temperature at the time the drive power from the battery for high voltage for the high voltage load is outputted. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vehicle power supply control device, and more specifically, a vehicle power supply control that controls a vehicle power supply that supplies power to a high voltage load driven at a high voltage and a low voltage load driven at a low voltage. Relates to the device.

  In recent years, a lithium battery or the like has been used as a vehicle power source that supplies power to a high voltage load such as a starter for starting an engine and a low voltage load such as an audio device. In general, the output performance of a lithium battery greatly depends on the temperature of the lithium battery itself. For example, when the temperature is low, the internal resistance of the lithium battery increases, and sufficient output power cannot be obtained. For this reason, when the temperature is low, sufficient power is not supplied to the starter, and the starter cannot be driven sufficiently.

To solve the above problem, a technique has been proposed in which the lithium battery is heated to improve the output performance of the lithium battery at a low temperature, and the starter can be sufficiently driven at a low temperature (for example, Patent Document 1). ). Specifically, when the output voltage of the lithium battery is equal to or higher than a predetermined value, power is supplied to the starter to drive the starter. When the output voltage of the lithium battery is lower than the predetermined value, power supply to the starter is prohibited. The lithium battery is warmed by repeating the control of stopping the starter.
JP 2002-195138 A

  Here, in the above prior art, the above control is repeated on the assumption that the output voltage of the lithium battery at a low temperature in a state where the starter is not driven is equal to or higher than a predetermined value. However, when the starter is started, the output voltage of the lithium battery at a low temperature may be lower than a predetermined value. In this case, the conventional technology cannot even drive the starter. As described above, the prior art has a problem that startability of the starter is low at low temperatures.

  SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a vehicle power supply control device that improves the startability of a high voltage load such as a starter at low temperatures.

  The present invention has been made to solve the above problems, and a vehicle power supply control device according to the present invention includes a high voltage battery connected to a high voltage load, a high voltage battery and a high voltage input. Step-down means connected to the connection point of the load to step down the input voltage and output it to the low-voltage load, temperature detection means for detecting the temperature of the high-voltage battery, and operation detection means for detecting the starting operation of the high-voltage load And when the start operation is detected by the operation detecting means, the temperature detected by the temperature detecting means is higher than the temperature at which the driving power for the high voltage load is output from the high voltage battery. If the power is lower, the power storage means is connected to the connection point, and control means for supplying drive power obtained from the voltage stored in the power storage means from the power storage means to the high voltage load is provided.

  The operation detection unit corresponds to, for example, a part of the functions of the engine ECU 18 and the drive control unit in the embodiment described later. The control means corresponds to the battery ECU 113 in an embodiment described later.

  According to the above configuration, the temperature of the high voltage battery is lower than the temperature when the driving power for the high voltage load is output, and the high voltage battery cannot supply the driving power for the high voltage load at a low temperature. Sometimes, drive power is supplied from the power storage means to the high voltage load. For this reason, since the high voltage load can be reliably driven at a low temperature, the startability of the high voltage load at a low temperature can be improved.

  Preferably, the control means may switch the connection of the power storage means from the connection point to the output of the step-down means when the supply of drive power from the power storage means to the high voltage load is completed. Further, in this case, when the supply of drive power from the power storage means to the high voltage load is finished, the control means disconnects the high voltage battery from the connection point and sets the voltage of the storage means to the same voltage as the output voltage of the step-down means. After that, the connection of the power storage means is switched from the connection point to the output of the step-down means, and the high voltage battery is preferably reconnected to the connection point.

  The high-voltage battery may be a lithium battery, the storage means may be a capacitor, and the high-voltage load may be a starter that starts a vehicle engine.

  ADVANTAGE OF THE INVENTION According to this invention, the power supply control apparatus for vehicles which improved the startability of high voltage loads, such as a starter at the time of low temperature, can be provided.

(Embodiment)
With reference to FIG. 1, the structure of the vehicle power supply control device according to the embodiment of the present invention will be described. FIG. 1 is a diagram illustrating a configuration example of a vehicle power supply control device according to an embodiment of the present invention.

  In FIG. 1, a vehicle power supply control device 1 is connected to a variable output alternator 2, a low voltage load 3, and a starter 4. The variable output alternator 2 is a device that generates electric power from the rotational force of an engine (not shown). The low voltage load 3 is an audio device or the like that is driven at a low voltage (for example, 12 V). The starter 4 is a high voltage load that is driven at a high voltage (for example, 42 V), and starts an engine by driving a built-in starter motor.

  The vehicle power supply control device 1 includes a battery pack 11, relays 12 to 15, a DC-DC converter 16, a capacitor 17, and an engine ECU 18. The battery pack 11 includes a high voltage battery 111, a battery temperature sensor 112, and a battery ECU 113. The high voltage battery 111 is, for example, a lithium battery. One end of the high voltage battery 111 is connected to the variable output alternator 2 and the other end is grounded. The high voltage battery 111 is charged with electric power generated by the variable output alternator 2. The relay 12 is ON / OFF controlled by a relay control signal from the terminal a of the battery ECU 113. One end of the relay 12 is connected to one connection end of the high voltage battery 111 and the variable output alternator 2, and the other end is connected to the input of the DC-DC converter 16. The output of the DC-DC converter 16 is connected to one end of the low voltage load 3, and the other end of the low voltage load 3 is grounded. The DC-DC converter 16 is a step-down means for stepping down the input high voltage (for example, 42 V) of the input high voltage battery 111 to a low voltage (for example, 12 V) and outputting it to the low voltage load 3.

  Similar to the relay 12, the relay 13 is ON / OFF controlled by a relay control signal from the terminal a of the battery ECU 113. One end of the relay 13 is connected to the connection point between the input of the DC-DC converter 16 and the other end of the relay 12, and the other end is connected to one end of the relay 15. As with the relay 12, the relay 14 is ON / OFF controlled by a relay control signal from the terminal a of the battery ECU 113. One end of the relay 14 is connected to the output of the DC-DC converter 16, and the other end is connected to a connection point between the other end of the relay 13 and one end of the relay 15. A connection point between the other end of relay 13 and one end of relay 15 is also connected to starter 4 and terminal b of battery ECU 113. Similar to the relay 12, the relay 15 is ON / OFF controlled by a relay control signal from the terminal a of the battery ECU 113. The capacitor 17 is a power storage unit that stores voltage, and is, for example, an ultracapacitor. One end of the capacitor 17 is connected to the other end of the relay 15, and the other end is grounded.

  The engine ECU 18 performs overall control of the engine, such as detection of a starter start operation by the driver and fuel supply to the engine. When the engine ECU 18 detects a starter start operation by the driver, the engine ECU 18 outputs a starter start request signal to the terminal c of the battery ECU 113. The engine ECU 18 outputs a starter drive start signal to the starter 4 when a starter start permission signal is input from the terminal d of the battery ECU 113. When the engine ECU 18 detects a starter drive end operation by the driver, the engine ECU 18 outputs a starter drive end signal to the terminal c of the battery ECU 113 and the starter 4. One end of the battery temperature sensor 112 is connected to the terminal e of the battery ECU 113, and the other end is grounded. The battery temperature sensor 112 detects the temperature of the high-voltage battery 111 and outputs a temperature signal representing the detected temperature to the terminal e of the battery ECU 113.

  Based on the starter start operation and starter drive end operation detected by the engine ECU 18 and the temperature of the high voltage battery 111 detected by the battery temperature sensor 112, the battery ECU 113 turns the relays 12 to 15 on and off, and the starter 4. Control the start of Hereinafter, the control process of the battery ECU 113 will be specifically described with reference to FIG. FIG. 2 is a flowchart showing a flow of control processing of the battery ECU 113. It is assumed that the initial connection state of each relay 12 to 15 is as shown in FIG. FIG. 3 is a diagram illustrating an initial connection state of each of the relays 12 to 15. As shown in FIG. 3, the initial connection state of the relays 12, 14, and 15 is set to the ON state, and the initial connection state of the relay 13 is set to the OFF state. In the initial state, the capacitor 17 is connected to the low voltage side. And

  In FIG. 2, the battery ECU 113 determines whether a starter start is requested (step S10). Specifically, when the driver performs an operation of turning the ignition key to the engine start position, the engine ECU 18 detects this as a starter start operation, and outputs a starter start request signal to the terminal c of the battery ECU 113. When the starter start request signal is input to the terminal c, the battery ECU 113 determines that the starter start is requested.

  When the starter start is requested (Yes in step S10), the battery ECU 113 determines whether or not the temperature of the high voltage battery 111 is lower than a predetermined temperature based on the temperature signal input to the terminal e (step S11). ). The predetermined temperature is the temperature of the high voltage battery 111 when the high voltage battery 111 can output the drive power of the starter 4. This predetermined temperature is set in advance in battery ECU 113, and is set to a different value depending on the type of starter 4 and the type of high-voltage battery 111. If the temperature of the high-voltage battery 111 is lower than the predetermined temperature (Yes in step S11), the control process proceeds to step S12. If the temperature is equal to or higher than the predetermined temperature (No in step S11), the control process proceeds to step S14.

  First, a series of control processes executed when the temperature of the high voltage battery 111 is lower than a predetermined temperature will be described. In step S <b> 12, the battery ECU 113 controls the relays 12 to 15 to connect the capacitor 17 to the high voltage side, and charges the capacitor 17 with the output high voltage of the high voltage battery 111. Specifically, the battery ECU 113 maintains the connection state of the relays 12 and 15 using the relay control signal, switches the connection state of the relay 13 from the OFF state to the ON state, and changes the connection state of the relay 14 from the ON state. Switch to OFF state. The switching order is the order of relay 14 → relay 13. FIG. 4 is a diagram illustrating a connection state of the relays 12 to 15 after the control process in step S12. As shown in FIG. 4, the capacitor 17 is connected to the high voltage battery 111 and the starter 4 by the control process in step S <b> 12, and the output high voltage of the high voltage battery 111 starts to be charged in the capacitor 17.

  Following step S12, the battery ECU 113 determines whether or not the voltage of the capacitor 17 is equal to the output high voltage of the high voltage battery 111 (step S13). Specifically, the battery ECU 113 detects the voltage at the terminal b connected to the capacitor 17 via the relay 15 as the voltage of the capacitor 17. Then, the battery ECU 113 compares the detected voltage with the output high voltage of the high voltage battery 111 set in advance in the battery ECU 113, and performs the determination in step S13. Since the charging time of the capacitor 17 tends to be long at low temperatures, a control process for monitoring the voltage of the capacitor 17 is performed as in step S13.

  When the voltage of the capacitor 17 becomes equal to the output high voltage of the high voltage battery 111 (Yes in step S13), the battery ECU 113 outputs a starter start permission signal from the terminal d to the engine ECU 18 (step S15). When the starter start permission signal is input, the engine ECU 18 outputs a starter drive start signal to the starter 4. When a starter drive start signal is input, the starter 4 drives a built-in starter motor. Here, as shown in FIG. 4, not only the power of the high voltage battery 111 but also the power of the capacitor 17 is supplied to the starter 4. Since the internal resistance of the high voltage battery 111 increases at low temperatures, sufficient power cannot be supplied to the starter 4 at low temperatures. On the other hand, since the internal resistance of the capacitor 17 is substantially close to “0” even at low temperatures, an inrush current (that is, electric power) necessary for driving the starter 4 can be supplied. For this reason, the starter 4 can be reliably driven even at a low temperature.

  Following step S15, the battery ECU 113 determines whether or not the drive of the starter 4 has been completed (step S16). Specifically, when the driver performs an operation of returning the ignition key to the original position, the engine ECU 18 detects this as a starter drive end operation and outputs a starter drive end signal to the terminal c of the battery ECU 113 and the starter 4. . When the starter drive end signal is output from the engine ECU 18, the starter 4 finishes driving, and the battery ECU 113 determines that the starter 4 has finished driving. When the starter 4 has been driven (Yes in step S16), the battery ECU 113 determines whether or not the output high voltage of the high voltage battery 111 is charged in the capacitor 17 (step S17). Specifically, the battery ECU 113 detects the voltage at the terminal b connected to the capacitor 17 via the relay 15 as the voltage of the capacitor 17. Then, the battery ECU 113 compares the detected voltage with the high output voltage of the high voltage battery 111 set in advance, and performs the determination in step S17. Here, since the control process of step S12 is performed, it is determined Yes in step S17, and the control process proceeds to step S18.

  In step S18, the battery ECU 113 controls the relays 12 to 15 and prepares to reconnect the capacitor 17 to the low voltage side (step S18). Specifically, the battery ECU 113 maintains the connection state of the relays 13 to 15 using the relay control signal, and switches the connection state of the relay 12 from the ON state to the OFF state. FIG. 5 is a diagram illustrating a connection state of the relays 12 to 15 after the control process in step S18. As shown in FIG. 5, only the capacitor 17 charged with the output high voltage of the high-voltage battery 111 is connected to the input of the DC-DC converter 16 by the control process in step S18. -Power supply to the DC converter 16 is started.

  Following step S18, the battery ECU 113 determines whether or not the voltage of the capacitor 17 has become equal to the output low voltage of the DC-DC converter 16 (step S19). Specifically, the battery ECU 113 detects the voltage at the terminal b connected to the capacitor 17 via the relay 15 as the voltage of the capacitor 17. Then, the battery ECU 113 compares the detected voltage with the low output voltage of the DC-DC converter 16 set in advance, and performs the determination in step S19. When the voltage of the capacitor 17 becomes equal to the output low voltage of the DC-DC converter 16 (Yes in step S19), the control process proceeds to step S20.

  Through the control processing in steps S18 and S19, the power of the capacitor 17 is changed from the high output voltage of the high voltage battery 111 to the low output voltage of the DC-DC converter 16 until the voltage of the capacitor 17 becomes the low output voltage of the DC-DC converter 16. Thus, the power of the capacitor 17 can be effectively used.

  In step S20, the battery ECU 113 controls the relays 12 to 15 to reconnect the capacitor 17 to the low voltage side. Specifically, the battery ECU 113 uses the relay control signal to switch the connection state of the relays 12 and 14 from the OFF state to the ON state, switches the connection state of the relay 13 from the ON state to the OFF state, and connects the relay 15. Maintain state. The switching order is the order of relay 13 → relay 12 → relay 14. By the control process of step S20, the connection state of each relay 12-15 returns to the initial connection state shown in FIG. After step S20, the control process returns to step S10.

  Next, a series of control processes executed when the temperature of the high voltage battery 111 is equal to or higher than a predetermined temperature will be described. In step S14, the battery ECU 113 controls the relays 12 to 15, connects the high voltage battery 111 to the starter 4, and disconnects the capacitor 17 from the low voltage side. Specifically, the battery ECU 113 outputs a relay control signal, maintains the connection state of the relay 12, switches the connection state of the relay 13 from the OFF state to the ON state, and changes the connection state of the relays 14 and 15 to the ON state. Switch from OFF to OFF state. The switching order is the order of relay 14 → relay 15 → relay 13. FIG. 6 is a diagram illustrating a connection state of the relays 12 to 15 after the control process in step S14. As shown in FIG. 6, only the high-voltage battery 111 is connected to the starter 4 by the control process in step S <b> 14.

  After step S14, the battery ECU 113 performs the control processes of steps S15 and S16 described above. The high-voltage battery 111 here has the output performance necessary to drive the starter 4, so that the starter 4 can be started. When the starter 4 has been driven (Yes in step S16), the battery ECU 113 determines whether or not the output high voltage of the high voltage battery 111 is charged in the capacitor 17 (step S17). Here, since the control process of step S12 is not performed, it is determined No in step S17, and the control process proceeds to step S21.

  In step S21, the battery ECU 113 controls the relays 12 to 15 to reconnect the capacitor 17 to the low voltage side. Specifically, the battery ECU 113 maintains the connection state of the relay 12 using the relay control signal, switches the connection state of the relay 13 from the ON state to the OFF state, and changes the connection state of the relays 14 and 15 from the OFF state. Switch to the ON state. The switching order is the order of relay 13 → relay 15 → relay 14. By the control process of step S21, the connection state of each relay 12-15 returns to the initial connection state shown in FIG. After step S21, the control process returns to step S10.

  As described above, according to the present embodiment, the starter 4 is driven using the capacitor 17 charged with a high voltage at a low temperature. For this reason, since the starter 4 can be reliably driven at low temperatures, the startability of the starter 4 at low temperatures can be improved.

  Further, according to the present embodiment, while the starter 4 is not driven, the capacitor 17 is connected to the low voltage side, and the capacitor 17 is used as a buffer on the low piezoelectric side. For this reason, even if the load value of the low voltage load 3 fluctuates, the output low voltage of the DC-DC converter 16 can be kept constant. The DC-DC converter 16 generally includes an overcurrent protection circuit. For this reason, when the load value of the low voltage load 3 fluctuates and an overcurrent flows through the output of the DC-DC converter 16, the overcurrent protection circuit operates and the output of the DC-DC converter 16 stops. However, in this embodiment, since the overcurrent can be taken out from the capacitor 17, even if an overcurrent flows, the operation of the overcurrent protection circuit can be avoided and the output of the DC-DC converter 16 is prevented from stopping. Can do.

  In the above description, the capacitor 17 is an ultracapacitor, but is not limited thereto. The capacitor 17 may be any capacitor as long as it is resistant to low temperatures, has a sufficient capacity, and has a rated voltage larger than the output high voltage of the high voltage battery 111. Furthermore, although the capacitor 17 is used as the power storage means for storing the voltage, another power storage means having an internal resistance of approximately “0” may be used instead of the capacitor 17.

  Further, in step 13 of FIG. 2 described above, the output high voltage of the high-voltage battery 111 is used as the reference voltage, but the present invention is not limited to this. The determination reference voltage may be equal to or higher than the voltage at which the capacitor 17 can supply the inrush current necessary for driving the starter 4, and may be any voltage as long as it is equal to or higher than this voltage.

  In the above description, the starter 4 is described as an example of the high voltage load. However, the control process of the present embodiment may be applied to a high voltage load other than the starter 4. In this case, the vehicle power supply control device 1 may include a drive control unit (not shown) connected to the battery ECU 113 and the high voltage load instead of the engine ECU 18. The drive control unit outputs a start request signal to the terminal c of the battery ECU 113 when detecting a start operation of the high voltage load by the driver, and outputs a drive start signal when the start permission signal is input from the terminal d of the battery ECU 113. When outputting to the high voltage load and detecting a driving end operation of the high voltage load by the driver, a driving end signal is output to the terminal c of the battery ECU 113. The control process of the battery ECU 113 is different from the control process described in FIG. 2 in that the starter start request signal is replaced with a start request signal, the starter start permission signal is replaced with a start permission signal, and the starter drive end signal is replaced with a drive end signal. The other points are the same as the control process described with reference to FIG.

  The vehicle power supply control device according to the present invention can improve the startability of a high voltage load such as a starter at a low temperature, and is applied to a vehicle such as an automobile.

The figure which shows the structural example of the power supply control device for vehicles which concerns on embodiment of this invention. The flowchart which showed the flow of control processing of battery ECU113 The figure which shows the initial connection state of each relay 12-15 The figure which shows the connection state of each relay 12-15 after the control processing of step S12. The figure which shows the connection state of each relay 12-15 after the control processing of step S18. The figure which shows the connection state of each relay 12-15 after the control processing of step S14.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle power supply control apparatus 2 Variable output alternator 3 Low voltage load 4 Starter 11 Battery pack 12-15 Relay 16 DC-DC converter 17 Capacitor 18 Engine ECU
111 Battery for High Voltage 112 Battery Temperature Sensor 113 Battery ECU

Claims (5)

A high voltage battery connected to a high voltage load;
Step-down means for connecting an input to a connection point between the high-voltage battery and the high-voltage load, stepping down the input voltage and outputting the voltage to a low-voltage load;
Temperature detecting means for detecting the temperature of the high voltage battery;
Operation detecting means for detecting a starting operation of the high voltage load;
Power storage means for storing voltage;
When a start operation is detected by the operation detection means, the temperature detection means detects that the power storage if the temperature detected by the temperature detection means is lower than the temperature at which the driving power for the high voltage load is output from the high voltage battery A vehicle power supply control device comprising: a control means for connecting the means to the connection point and supplying the driving power obtained from the voltage stored in the power storage means from the power storage means to the high voltage load.   2. The vehicle according to claim 1, wherein the control unit switches the connection of the power storage unit from the connection point to the output of the step-down unit when supply of driving power from the power storage unit to the high voltage load is completed. Power control device.   When the supply of drive power from the power storage means to the high voltage load is completed, the control means disconnects the high voltage battery from the connection point, and the voltage of the storage means is the same as the output voltage of the step-down means. 2. The vehicle power supply control device according to claim 1, wherein after the voltage is changed, the connection of the power storage unit is switched from the connection point to the output of the step-down unit, and the high-voltage battery is reconnected to the connection point.   The vehicle power supply control device according to any one of claims 1 to 3, wherein the high-voltage battery is a lithium battery, and the storage means is a capacitor.   The vehicular power supply control device according to any one of claims 1 to 4, wherein the high voltage load is a starter for starting an engine of the vehicle.

Images