JP2014184752A - Power supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply device which is charged with power generated by an on-vehicle generator and has excellent charging efficiency in charging a battery which supplies power to an electric load group.SOLUTION: A lithium storage battery 1 is connected to an electric load 41 and an ISG (Integrated Starter Generator) 3. A lead storage battery 2 is connected to a starter 5. When the ISG 3 generates power and output voltage of the lead storage battery 2 detected by a voltage detector 72 is not less than predetermined voltage, a control section 7 performs control to disconnect the lithium storage battery 1 from the lead storage battery 2 with a switch 6. When the ISG 3 does not generate power and the output voltage of the lithium storage battery 1 is not more than the output voltage of the lead storage battery 2, the control section 7 performs the control to connect the lithium storage battery 1 to the lead storage battery 2 with the switch 6.

Description

  The present invention relates to a power supply apparatus that includes a battery that is charged by electric power generated by an on-vehicle generator and supplies electric power to an electric load group.

  Electric loads installed in vehicles tend to increase year by year. For example, the electric load is increased by adopting an electric brake, an electric power steering device, and the like in order to improve the control performance and efficiency by electrifying equipment that has been operated by hydraulic pressure or engine power. In addition, in order to improve the fuel consumption efficiency in the engine, the electric load tends to increase also by adopting an electric motor that assists the engine output, a starter motor for restarting after idling stop, and the like.

  In response to such an increase in electrical load, in addition to the conventional lead storage battery in a vehicle, a lithium ion storage battery (hereinafter referred to as a lithium storage battery) is provided, and the power generated by the in-vehicle generator is used as a lead storage battery and a lithium storage battery. Power supply devices that are supplied to and charged and discharged have been developed. Lithium storage batteries can be charged and discharged at a higher voltage than lead storage batteries, generally have better charging efficiency than lead storage batteries, and are suitable for improving fuel consumption efficiency.

  For example, a conventional power supply device described in Patent Document 1 is interposed between a lead storage battery connected to an in-vehicle generator, a lithium storage battery connected in parallel to the lead storage battery, and the in-vehicle generator and the lithium storage battery. And a MOS-FET for switching between energization and cutoff, and a relay interposed between the MOS-FET and the lithium storage battery. In this power supply device, the operating states of the MOS-FET and the relay are determined so that the charging rate (hereinafter referred to as SOC: State of Charge) representing the ratio of the current charged amount to the fully charged amount is within an appropriate range for both batteries. .

  Specifically, when the regenerative charging from the in-vehicle generator to the battery, the power supply device increases the chance that the output voltage of the lithium storage battery becomes lower than the output voltage of the lead storage battery, and turns on the MOS-FET and the relay. Control is performed so that charging to the lithium storage battery is promoted. On the other hand, when discharging from the battery, the power supply device increases the chance that the output voltage of the lithium storage battery becomes higher than the output voltage of the lead storage battery, and sets the MOS-FET to the off state and the relay to the on state. Then, control is performed so that power supply from the lithium storage battery to the electric load is promoted.

JP 2011-176958 A

  However, since the power supply device described in Patent Literature 1 sets the charging voltage of the lithium storage battery to be the same as or lower than that of the lead storage battery, the power charged in the lithium storage battery is kept low. For this reason, there is a possibility that the electric power charged in the lithium storage battery is lower than the regenerative electric power of the on-vehicle generator, and there is a problem that the improvement effect of fuel consumption is limited.

  In addition, since the MOS-FET is turned on during regenerative charging, both the lithium storage battery and the lead storage battery are in a charged state, so charging is performed compared to charging a lithium storage battery with good charging efficiency alone. There was a problem that the efficiency was lowered.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a power supply device that is charged with power generated by an on-vehicle generator and has good charging efficiency for a battery that supplies power to an electric load group. To do.

  A power supply device according to the present invention includes an on-vehicle generator that generates power in conjunction with an engine mounted on a vehicle, a first battery that is charged with electric power generated by the on-vehicle generator and supplies electric power to an electric load group, And a second battery that is charged with electric power generated by the in-vehicle generator and supplies electric power to a starter that starts the engine, wherein the first battery is connected to the in-vehicle generator, A switch for connecting and disconnecting one battery and the second battery, a detecting means for detecting output voltages of the first and second batteries, and a detecting means for detecting when the on-vehicle generator is generating power. When the output voltage of the second battery is equal to or higher than a predetermined voltage, the on-vehicle generator generates power while the first battery and the second battery are shut off by the switch. If the output voltage of the first battery detected by the detection means is less than or equal to the output voltage of the second battery, the switch performs control to connect the first battery and the second battery with the switch. Means.

  In the present invention, the on-vehicle generator generates power in conjunction with the engine mounted on the vehicle, and the first battery is charged with the electric power generated by the on-vehicle generator and supplies the electric load group with electric power. The second battery is charged with electric power generated by the on-vehicle generator and supplies electric power to a starter that starts the engine. The first battery is connected to the on-vehicle generator, the first battery and the second battery are connected and disconnected by the switch, and the output voltages of the first and second batteries are detected by the detecting means. When the on-vehicle generator is generating power and the output voltage of the second battery detected by the detection unit is equal to or higher than the predetermined voltage, the control unit cuts off the first battery and the second battery by the switch, When the generator is not generating power and the output voltage of the first battery detected by the detection means is equal to or lower than the output voltage of the second battery, control is performed to connect the first battery and the second battery by the switch. As a result, charging to the first battery that supplies power to the electric load group is performed, so that charging efficiency is improved, and when the output voltage of the first battery decreases, the electric load is applied to both the first battery and the second battery. Power can be supplied to the group.

  The power supply device according to the present invention is characterized in that an upper limit value of a use range related to an output voltage of the first battery is higher than an upper limit value of a use range related to an output voltage of the second battery.

  In the present invention, since the upper limit value of the use range related to the output voltage of the first battery is higher than the upper limit value of the use range related to the output voltage of the second battery, the charging power to the first battery is increased. The charging efficiency can be improved because more power generated by the on-vehicle generator can be used for charging.

  The power supply device according to the present invention includes a second starter that operates when the engine is restarted after idling stop, and the first battery supplies power to the second starter.

  In the present invention, since the electric power is supplied from the first battery to the second starter that operates when the engine is restarted after idling stop, charging / discharging of the first battery is promoted.

  The power supply device according to the present invention includes a motor that supplies power to the output shaft of the engine, and the first battery supplies power to the motor.

  In the present invention, since electric power is supplied from the first battery to the motor that supplies power to the output shaft of the engine, charging and discharging of the first battery is promoted.

  In the power supply device according to the present invention, the first battery is a lithium ion storage battery or a nickel hydride storage battery, and the second battery is a lead storage battery.

  In the present invention, the first battery is a lithium ion storage battery or a nickel hydride storage battery, and the second battery is a lead storage battery. Thereby, charging / discharging of a lithium ion storage battery or a nickel hydride storage battery can be accelerated | stimulated, and charging efficiency can be improved.

  According to the present invention, the on-vehicle generator generates power in conjunction with the engine mounted on the vehicle, and the first battery is charged by the electric power generated by the on-vehicle generator and supplies the electric load group with electric power. The second battery is charged with electric power generated by the on-vehicle generator and supplies electric power to a starter that starts the engine. The first battery is connected to the on-vehicle generator, the first battery and the second battery are connected and disconnected by the switch, and the output voltages of the first and second batteries are detected by the detecting means. When the on-vehicle generator is generating power and the output voltage of the second battery detected by the detection unit is equal to or higher than the predetermined voltage, the control unit cuts off the first battery and the second battery by the switch, When the generator is not generating power and the output voltage of the first battery detected by the detection means is equal to or lower than the output voltage of the second battery, control is performed to connect the first battery and the second battery by the switch. For this reason, since the first battery that supplies power to the electric load group is charged, the charging efficiency is improved, and when the output voltage of the first battery decreases, the electric load is applied to both the first battery and the second battery. Power can be supplied to the group.

It is a block diagram which shows schematic structure of the power supply device which concerns on embodiment of this invention. It is a schematic diagram for demonstrating the target SOC range at the time of use of a lead acid battery. It is a schematic diagram for demonstrating the relationship between the electrical storage amount and output voltage of a lithium storage battery and a lead storage battery. It is a flowchart which shows the process sequence of the switch control of a switch by a control part. It is a block diagram which shows schematic structure of the power supply device which concerns on a modification.

  Hereinafter, the present invention will be described with reference to the drawings illustrating embodiments thereof. FIG. 1 is a block diagram showing a schematic configuration of a power supply device 10 according to an embodiment of the present invention. The power supply device 10 is mounted on a vehicle 100 and includes a lithium storage battery 1, a lead storage battery 2, an integrated starter generator 3 (hereinafter referred to as ISG 3, ISG: Integrated Starter Generator), a switch 6, and a control unit 7. Electric power is supplied to electric loads 41 and 42 (abbreviated as loads 41 and 42 in FIGS. 1 and 5) and a starter 5 such as an electric brake and an electric power steering device.

  The ISG 3 is a motor generator having both functions of an alternator and an engine (not shown) restarter. The ISG 3 is connected to an engine that is a driving power source of the vehicle 100, and generates electric power by rotation of the engine output shaft. The DC power generated and rectified by the function of the generator of the ISG 3 is supplied to the lithium storage battery 1, the lead storage battery 2, and each electric load that are connected in parallel. The ISG 3 performs regenerative control that generates power when the vehicle 100 is decelerating, thereby providing a braking force to the vehicle 100 as a load for the rotation of the engine output shaft, charging each battery with the generated power, Supply power to electrical loads. An alternator may be provided instead of ISG3.

  The ISG 3 also functions as a starter for restarting, and after the engine is idling stopped, the ISG 3 is restarted mainly by receiving power supply from the lithium storage battery 1. For example, the ISG 3 functions as a restart starter by depressing an accelerator pedal after idling stop. In order to prevent the idling stop from becoming an unpleasant phenomenon for the occupant of the vehicle 100, the engine restart by the ISG 3 is required to be immediate and quiet, and includes a drive mechanism for rotating the crankshaft by a belt or the like. The ISG 3 functions as an on-vehicle generator and a second starter in the present invention.

  The starter 5 rotates the crankshaft of an engine (not shown), and starts the engine by igniting fuel with an ignition device. The starter 5 operates mainly by receiving power supply from the lead storage battery 2, but when the SOC of the lead storage battery 2 at the time of engine start is low, the lithium storage battery 1 is connected in parallel to the lead storage battery 2, and the lithium storage battery 1 and lead Power can be supplied from the storage battery 2 to the starter 5 for operation.

  The lithium storage battery 1 is connected to the ISG 3 and the electric load 41, is charged by the ISG 3, and supplies power to the electric load 41 and the ISG 3 (ISG 3 as a restart starter). The lithium storage battery 1 is controlled in a SOC range (hereinafter referred to as a target SOC range) that is a control target during use in which charging / discharging is performed, for example, when the SOC is controlled within a range of 30% to 80%. Battery performance can be prevented from deteriorating and can be used for a long time. Moreover, since the lithium storage battery 1 generally has a better charging efficiency than the lead storage battery 2, by supplying electric power mainly from the lithium storage battery 1 and operating an electric load, the engine load ISG3 (as an alternator) It is considered that the power generation by the ISG 3) is suppressed and the fuel efficiency of the vehicle 100 is improved. Therefore, regarding the arrangement of the electric loads 41 and 42 in the power supply device 10, the load amount by the electric load 41 arranged on the lithium storage battery 1 side with the switch 6 interposed therebetween may be increased. The lithium storage battery 1 functions as the first battery in the present invention.

  The lead storage battery 2 is a storage battery that is widely mounted in the vehicle 100. FIG. 2 is a schematic diagram for explaining the target SOC range when the lead storage battery 2 is used. As shown in FIG. 2, with respect to the lead storage battery 2, the target SOC range in which deterioration of battery performance is suppressed is, for example, a storage amount (SOC conversion) of 88% to 92% and 12.7 V to 12.2 at the output terminal. The range is 8V. The output terminal of the lead storage battery 2 is connected to the starter 5 and is operated by supplying power to the starter 5 when the engine is started. The output terminal of the lead storage battery 2 is connected to the lithium storage battery 1 and the ISG 3 via the switch 6. The lead storage battery 2 is supplied with power from the ISG 3 via the switch 6 and charged. The lead storage battery 2 functions as the second battery in the present invention.

  The switch 6 is a switching element such as a relay or a MOS-FET, for example, and is interposed between the output terminals of the lithium storage battery 1 and the lead storage battery 2. The switch 6 is switched on / off by the controller 7 to connect and disconnect the lithium storage battery 1 and the lead storage battery 2. Further, the switch 6 may be constituted by a DC / DC converter. In this case, voltage adjustment at the time of battery connection is performed by a step-up / step-down function in addition to a connection / cutoff function.

  The control unit 7 includes a CPU (Central Processing Unit) (not shown), a flash memory, a ROM using an EEPROM (Erasable Programmable Read Only Memory), an EEPROM (Electrically EPROM), and a DRAM (Dynamic Random Access Memory). And a RAM using a memory such as SRAM (Static Random Access Memory), and the CPU 6 executes a control program stored in the ROM to control the switch 6 and the like. The CPU temporarily stores data generated during the execution of the control program in the RAM.

  Voltage detectors 71 and 72 and current detectors 73 and 74 are connected to the control unit 7. The voltage detector 71 detects the output voltage value of the lithium storage battery 1, and the voltage detector 72 detects the output voltage value of the lead storage battery 2. The current detector 73 detects the amount of current input / output to / from the lithium storage battery 1, and the current detector 74 detects the amount of current input / output to / from the lead storage battery 2. In the present embodiment, the control unit 7 performs switching control of the switch 6 based on the output voltage values of the lithium storage battery 1 and the lead storage battery 2 detected by the voltage detectors 71 and 72. The switching control may be performed by estimating the charged amount (SOC) of each battery based on the amount. Further, the switching control may be performed by detecting the amount of stored electricity (SOC) by another method. The voltage detectors 71 and 72 function as detection means in the present invention, and the control unit 7 functions as control means in the present invention.

  Next, the operation | movement in the switching control of the switch 6 by the control part 7 is demonstrated. FIG. 3 is a schematic diagram for explaining the relationship between the storage amount of the lithium storage battery 1 and the lead storage battery 2 and the output voltage. In FIG. 3, the solid line indicates the characteristics of the lead storage battery 2, and the thick line indicates the characteristics of the lithium storage battery 1. As described above, the target SOC range of the lead storage battery 2 is, for example, 88% to 92% of the storage amount, and the control unit 7 determines that the storage amount of the lead storage battery 2 falls below the target SOC range when the ISG 3 is generating power. When it is, the lead storage battery 2 is charged. Specifically, the control unit 7 determines whether or not the output voltage value of the lead storage battery 2 detected by the voltage detector 72 is equal to or higher than a predetermined voltage, and if it is equal to or higher than the predetermined voltage, the switch 6 is turned off. If it is less than the predetermined value, the switch 6 is turned on. The predetermined voltage may be 12.7V corresponding to the lower limit value 88% of the target SOC range, or may be a value larger than this and about 12.8V corresponding to the upper limit value 92%. Also, the predetermined voltage may be set to a value larger than 12.8V in consideration of discharge.

  When the storage amount of the lead storage battery 2 is within the target SOC range, the control unit 7 switches the switch 6 to the off state and charges the lithium storage battery 1. As shown by the thick line, the target SOC range of the lithium storage battery 1 is, for example, 30% to 80% of the charged amount, and is controlled to be charged / discharged within the target SOC range. As shown in FIG. 3, the output voltage corresponding to the upper limit value in the target SOC range of the lithium storage battery 1 is set to a higher voltage than the corresponding output voltage of the lead storage battery 2. Charging / discharging of the lithium storage battery 1 is promoted by increasing the load of the electrical load 41 on the lithium storage battery 1 side and the load such as ISG3 as a restart starter compared to the electrical load 42 on the lead storage battery 2 side.

  Further, the control unit 7 compares the output voltage values of the lithium storage battery 1 and the lead storage battery 2 when the ISG 3 is not generating power, and the output voltage value of the lithium storage battery 1 is equal to or less than the output voltage value of the lead storage battery 2. Then, the switch 6 is turned on, and electric power is supplied to the electric loads 41 and 42 by the lithium storage battery 1 and the lead storage battery 2. When the output voltage value of the lithium storage battery 1 is larger than the output voltage value of the lead storage battery 2 when the ISG 3 is not generating power, the control unit 7 turns off the switch 6 so that the lithium storage battery 1 is connected to the electrical load 41 and the like. Electric power is supplied, and the lead storage battery 2 is controlled to supply electric power to the electric load 42.

  Next, a processing procedure for switching control of the switch 6 by the control unit 7 will be described. FIG. 4 is a flowchart showing a processing procedure for switching control of the switch 6 by the control unit 7. The control unit 7 determines whether or not the ISG 3 is regenerating in step S1. It is assumed that the information on whether or not regeneration is already known in the regeneration control process for ISG3. When it determines with regeneration (S1: YES), the control part 7 determines whether the output voltage value of the lead storage battery 2 which the voltage detector 72 detected by step S2 is more than predetermined voltage. When it determines with it being more than a predetermined voltage (S2: YES), the control part 7 switches the switch 6 to an OFF state (step S3), and charges the lithium storage battery 1 (step S4). On the other hand, when it determines with it being below a predetermined voltage (S2: NO), the control part 7 switches the switch 6 to an ON state (step S5), and charges the lithium storage battery 1 and the lead storage battery 2 (step S6). ). After steps S4 and S6, the control unit 7 returns the process to the start.

  Moreover, when it determines with not having regenerated (S1: NO), the control part 7 is the lead storage battery 2 which the voltage detector 72 detected the output voltage value of the lithium storage battery 1 which the voltage detector 71 detected by step S7. It is determined whether or not the output voltage value is larger. When it is determined that the output voltage value of the lithium storage battery 1 is larger than the output voltage value of the lead storage battery 2 (S7: YES), the control unit 7 switches the switch 6 to the off state (step S8) and restarts by step S9. It is determined whether or not the drive of the ISG 3 as a starter has been started. When it is determined that the driving of the ISG 3 is started (S9: YES), the ISG 3 is driven by supplying power from the lithium storage battery 1 to the ISG 3 (step S10). When it is determined that the driving of the ISG 3 as the restart starter is not started (S9: NO), and after the driving of the ISG 3 in step 10, the control unit 7 returns the process to the start.

  When it determines with the output voltage value of the lithium storage battery 1 being below the output voltage value of the lead storage battery 2 (S7: NO), the control part 7 switches the switch 6 to an ON state (step S11), and performs a process after that. Return to start.

  As described above, according to the present embodiment, the ISG 3 generates power in conjunction with the engine mounted on the vehicle 100, and the lithium storage battery 1 is charged with the power generated by the ISG 3, and serves as the electric load 41 and the restart starter. Supply power to ISG3 etc. The lead storage battery 2 is charged by the power generated by the ISG 3 and supplies power to the starter 5 that starts the engine. The lithium storage battery 1 is connected to the ISG 3, the switch 6 connects and disconnects the lithium storage battery 1 and the lead storage battery 2, and the voltage detectors 71 and 72 detect the output voltages of the lithium storage battery 1 and the lead storage battery 2. . When the output voltage of the lead storage battery 2 detected by the voltage detector 72 is equal to or higher than a predetermined voltage when the ISG 3 is generating (regenerating), the control unit 7 switches the lithium storage battery 1 and the lead storage battery 2 with the switch 6. When the output voltage of the lithium storage battery 1 is less than or equal to the output voltage of the lead storage battery 2 when the ISG 3 is not generating power (regeneration), the switch 6 controls the connection of the lithium storage battery 1 and the lead storage battery 2 with the switch 6. Do. As a result, the lithium storage battery 1 that supplies power to the electrical load 41 and the ISG 3 as a restart starter is charged, so that the charging efficiency is improved, and when the output voltage of the lithium storage battery 1 decreases, the lithium storage battery 1 In addition, both the lead storage battery 2 and the lead-acid battery 2 can supply power to the electric load group, and the function safety by the redundant power supply is improved.

  Further, according to the present embodiment, the upper limit value of the use range related to the output voltage corresponding to the target SOC range of the lithium storage battery 1 is higher than the upper limit value of the use range related to the output voltage corresponding to the target SOC range of the lead storage battery 2. Since it is high, the charging power to the lithium storage battery 1 can be increased, and more of the power generated by the ISG 3 can be used for charging, so the charging efficiency is improved.

  Moreover, according to this embodiment, since electric power is supplied from the lithium storage battery 1 to the ISG 3 as a restart starter that operates when restarting after idling stop of the engine, charging / discharging of the lithium storage battery 1 is promoted and charging efficiency is improved. In addition to being improved, fuel consumption can be reduced.

  In the above-described embodiment, the ISG 3 serving as the restart starter is connected to the lithium storage battery 1, but a torque assisting motor that supplies power to the engine output shaft is connected to supply power from the lithium storage battery 1. Good. Also in this case, charging / discharging of the lithium storage battery 1 is promoted, charging efficiency is improved, and fuel consumption can be reduced.

  Although the lithium storage battery 1 is used in the above-described embodiment, a nickel hydride storage battery may be used instead of the lithium storage battery 1. In this case, charging efficiency of the nickel hydride storage battery can be promoted to improve charging efficiency.

(Modification)
FIG. 5 is a block diagram illustrating a schematic configuration of the power supply device 10 according to the modification. The power supply device 10 in the modification is configured by adding switches 81 and 82 to the configuration of the power supply device 10 shown in FIG. The switch 81 is a switching element that connects and disconnects the lithium storage battery 1 and the electrical load 42, and the switch 82 is a switching element that connects and disconnects the lead storage battery 2 and the electrical load 42. In steps S5 and S11 in which the switch 6 is turned on in the flowchart shown in FIG. 4, the switch 81 is turned off and the switch 82 is turned on. In this case, since the operation is the same as that of the first embodiment, the description is omitted for the sake of simplicity.

  In Step S3 and Step S8 in which the switch 6 is turned off in the flowchart shown in FIG. 4, in the modification, the control unit 7 performs control to turn on the switch 81 and turn off the switch 82. Thereby, the electric load 41 is connected to the lithium storage battery 1 side rather than the lead storage battery 2 side across the switch 6. Thereby, the electrical load of the lithium storage battery 1 increases, charging / discharging of the lithium storage battery 1 is accelerated | stimulated, and the further improvement of charging efficiency can be aimed at.

  As mentioned above, although the form for inventing was demonstrated, it should be thought that disclosed embodiment is an illustration and restrictive at no points. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 Lithium storage battery (first battery)
2 Lead acid battery (second battery)
3 ISG (on-vehicle generator, second starter)
41 Electric load (electric load group)
5 Starter 6 Switch 7 Control unit (control means)
71, 72 Voltage detector (detection means)
10 power supply device 100 vehicle

Claims (5)

A vehicle-mounted generator that generates power in conjunction with an engine mounted on the vehicle, a first battery that is charged with power generated by the vehicle-mounted generator and supplies power to an electric load group, and power generated by the vehicle-mounted generator And a second battery for supplying power to a starter for starting the engine,
The first battery is connected to the in-vehicle generator;
A switch for connecting and disconnecting the first battery and the second battery;
Detecting means for detecting output voltages of the first and second batteries;
When the on-vehicle generator is generating power, when the output voltage of the second battery detected by the detecting means is equal to or higher than a predetermined voltage, the switch cuts off the first battery and the second battery. When the on-vehicle generator is not generating power, when the output voltage of the first battery detected by the detection means is equal to or lower than the output voltage of the second battery, the switch causes the first battery and the second battery to And a control means for performing control for connecting the battery.   2. The power supply device according to claim 1, wherein an upper limit value of a use range related to an output voltage of the first battery is higher than an upper limit value of a use range related to an output voltage of the second battery. A second starter that operates upon restart after idling stop of the engine;
The power supply device according to claim 1, wherein the first battery supplies power to the second starter. A motor for supplying power to the output shaft of the engine;
4. The power supply apparatus according to claim 1, wherein the first battery supplies power to the motor. 5. The first battery is a lithium ion storage battery or a nickel hydride storage battery,
The power supply apparatus according to claim 1, wherein the second battery is a lead storage battery.

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