JP2010241396A - Power supply system for hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure output power from a power storage device when a hybrid vehicle is in a mode where vehicle drive power is generated by preferentially using the power of the power storage device. <P>SOLUTION: In the hybrid vehicle, CD (Charge Depleting) mode where the power of the power storage device is preferentially used for traveling, or CS (Charge Sustaining) mode where an SOC (State of Charge) of the power storage device is controlled within a predetermined control range by internal charging using output of an internal combustion engine, is selected according to a vehicle state. A forcible charging period of the power storage device is provided independently of SOC management when the mode shifts from the CS mode to the CD mode by satisfaction of a predetermined condition, there by increasing discharge power of the power storage device as soon as CD mode transfer is set. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a power supply system for a hybrid vehicle, and more particularly to charge / discharge control of a power storage device mounted on the hybrid vehicle.

  As one aspect of a hybrid vehicle, a vehicle configuration that can generate vehicle drive power by both an electric motor that receives supply of drive power from a power storage device represented by a secondary battery and an internal combustion engine that generates output by fuel combustion is known. It has been. In the hybrid vehicle, it is necessary to set the output distribution between the internal combustion engine and the electric motor in the entire hybrid vehicle so that the power storage device is not overcharged or overdischarged. In general, the chargeable / dischargeable power of the power storage device is set based on the SOC (State of Charge) indicating the remaining capacity of the power storage device, the battery temperature, etc., and within the range of the chargeable / dischargeable power, The output sharing is set so as to be charged and discharged.

  Regarding such driving force distribution, Japanese Patent Laid-Open No. 2006-42497 (Patent Document 1) describes not only the overall SOC, which is an average SOC of the entire power storage device (secondary battery) based on current integration and the like, It is described that the driving force distribution control is optimized in consideration of the fact that the output characteristics vary depending on the distribution state of the ion concentration inside the secondary battery. Specifically, even if the overall SOC is the same level, if the local SOC based on the estimation of the ion concentration distribution inside the secondary battery is lower than the overall SOC, the motor output power upper limit value is lower than normal. It is described as a value.

JP 2006-42497 A

  As described in Patent Document 1, when a secondary battery applied as a power storage device continues to discharge for a long period of time, an uneven distribution of ion concentration occurs in the secondary battery, resulting in an output from the secondary battery. The possible power tends to decrease.

  On the other hand, in a hybrid vehicle that can generate charging power of the power storage device while traveling using the output of the internal combustion engine, the traveling mode (CD ( 2. Description of the Related Art There is known a configuration capable of traveling by selecting a charge depleting (CS) mode and a traveling mode (CS (Charge Sustaining) mode) for traveling while maintaining the remaining capacity of the power storage device within a predetermined control range.

  In such a hybrid vehicle, when the CD mode is selected, the vehicle basically travels using only the electric power of the power storage device, so that the output power from the electric motor can be secured particularly immediately after switching to the CD mode. In addition, it is necessary to consider so that the dischargeable power from the power storage device does not decrease. Also in the CS mode, it is preferable to execute charge / discharge control that can secure the dischargeable power from the power storage device according to the vehicle state.

  The present invention has been made to solve such problems, and an object of the present invention is to provide a hybrid having a traveling mode in which vehicle driving power is generated by preferentially using the power of the power storage device. In the vehicle, charge / discharge control of the power storage device is appropriately performed in accordance with the selection of the travel mode so that the outputable power from the power storage device is ensured.

  A power supply system for a hybrid vehicle according to the present invention is a power supply system for a hybrid vehicle in which an internal combustion engine and an electric motor are mounted as a power source, and a power storage device configured to be able to input and output electric power to the electric motor, and an output of the internal combustion engine A power generation unit for generating charging power of the power storage device, a charge / discharge control unit configured to estimate a remaining capacity of the power storage device based on a state detection value of the power storage device, a traveling mode selection unit, and a hybrid And a control unit. The travel mode selection unit uses a first travel mode in which the internal combustion engine and the electric motor are used to travel while maintaining the remaining capacity of the power storage device within a predetermined control range, and the electric motor mainly uses the electric power of the power storage device. It is configured to select one of the second traveling mode using the internal combustion engine and the electric motor to travel. The hybrid control unit is configured to control the internal combustion engine and the electric motor based on a selection result by the traveling mode selection unit. The hybrid control unit is configured to instruct execution of internal charging for return charging for returning the dischargeable power of the power storage device upon transition from the first travel mode to the second travel mode. The

  According to the hybrid vehicle power supply system described above, the return charge is performed at the time of transition from the first travel mode (CS mode) to the second travel mode (CD mode). The CD mode in which the vehicle travels mainly by the electric motor output can be started in a state of being reliably recovered. As a result, in the CD mode, the vehicle driving power that can be handled by the electric power from the power storage device can be expanded while protecting the power storage device.

  More preferably, the hybrid control unit instructs execution of internal charging for return charging regardless of the estimated value of the remaining capacity.

  In this way, it is possible to provide an opportunity for return charging to secure the dischargeable power (Wout) of the power storage device separately from the management of the remaining capacity (SOC) of the power storage device.

  Preferably, the hybrid vehicle further includes a navigation device configured to be able to acquire own vehicle position information of the vehicle and at least one of road map information and external information from outside the vehicle. The travel mode selection unit is configured to select one of the first and second travel modes based on the relationship between the vehicle position information and at least one information. The hybrid control unit, when selecting the first travel mode, for return charging when a predetermined switching precondition set to be satisfied before the switching condition to the second travel mode is satisfied. Instructs execution of internal charging.

  In this way, in the hybrid vehicle that selects the CS mode and the CD mode based on the information from the navigation device, an opportunity for return charging can be provided with certainty before shifting to the CD mode. For example, when performing a travel mode selection for using up the power of the power storage device by the time of arrival at the home, or a travel mode selection directed to travel that avoids exhaust gas output (passage of the internal combustion engine) during city traffic Control can be applied.

  More preferably, at the time of transition from the first travel mode to the second travel mode, the hybrid control unit further determines whether or not return charging is necessary according to the state of the power storage device.

  In this way, when the dischargeable power (Wout) of the power storage device is not lowered, there is no need for an unnecessary return charging, and therefore a reduction in fuel consumption in the CD mode can be prevented.

  Preferably, the hybrid control unit further performs internal charging for return charging when the vehicle state satisfies a predetermined condition regardless of the estimated value of the remaining capacity when the second traveling mode is selected. Instruct. More preferably, when the internal combustion engine is started by a request different from the return charge when the second travel mode is selected, the hybrid control unit determines that the total required power for traveling of the hybrid vehicle is equal to that of the internal combustion engine. When the output is lower than the maximum output value, execution of internal charging is instructed by increasing the output of the internal combustion engine.

  In this way, when the first traveling mode (CS mode) is selected, the output of the internal combustion engine started by other factors is raised without newly requesting the start of the internal combustion engine for return charging. Thus, it is possible to ensure the output of the internal combustion engine for return charging. As a result, it is possible to provide an opportunity for return charging of the power storage device without unnecessarily increasing the operation opportunity of the internal combustion engine during the selection of the CS mode.

  More preferably, the hybrid control unit is configured to start or increase the output of the internal combustion engine if the brake pedal changes from the on state to the off state while the internal combustion engine is stopped when the second travel mode is selected. Instructing execution of internal charging for return charging.

  If it does in this way, when starting from the stop state of a vehicle, it will be predicted that the acceleration demand from a user will occur, and it can secure surely the electric power which can be discharged from the power storage device at the time of the acceleration demand concerned. As a result, driving comfort can be improved.

  More preferably, the hybrid control unit further determines whether or not return charging is necessary according to the state of the power storage device when the second travel mode is selected.

  In this way, when the dischargeable power (Wout) of the power storage device is not lowered, there is no need for an unnecessary return charging, and therefore a reduction in fuel consumption in the CD mode can be prevented.

  Preferably, the power supply system for the hybrid vehicle further includes a charger configured to charge the power storage device with a power supply external to the vehicle.

  In this way, in the hybrid vehicle in which the driving mode is more flexibly selected between the CD mode and the CS mode and the power storage device can be externally charged, by appropriately performing charge / discharge control of the power storage device, Can be secured.

  According to the present invention, in a hybrid vehicle having a travel mode that generates vehicle drive power by preferentially using the power of the power storage device, charge / discharge control of the power storage device is appropriately performed in accordance with the selection of the travel mode. As a result, it is possible to secure power that can be output from the power storage device.

It is a functional block diagram explaining the structure of the hybrid vehicle carrying the power supply system by embodiment of this invention. FIG. 2 is a block diagram illustrating travel control related to travel mode selection in the hybrid vehicle illustrated in FIG. 1. It is a conceptual diagram which shows the relationship between driving mode selection and SOC transition of an electrical storage apparatus. It is a conceptual diagram explaining the example in which driving modes are selected according to the own vehicle position of a hybrid vehicle. It is a 1st conceptual diagram explaining the example of switching from CS mode to CD mode. It is a 2nd conceptual diagram explaining the example of a switch from CS mode to CD mode. It is a wave form diagram which shows the relationship between charging / discharging operation | movement of a secondary battery, and transition of an output power upper limit. It is a flowchart which shows the process sequence of the vehicle control for providing the opportunity of a return charge during CS mode selection. It is a 1st flowchart which shows the process sequence of the vehicle control for providing the opportunity of a return charge during CD mode selection. It is a conceptual diagram explaining transition of the output power accompanying the return charge according to the flowchart of FIG. It is a 2nd flowchart which shows the process sequence of the vehicle control for providing the opportunity of return charge during CD mode selection.

  Embodiments of the present invention will be described below in detail with reference to the drawings. In the following, the same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated.

  FIG. 1 is a functional block diagram illustrating a configuration of a hybrid vehicle equipped with a power supply system according to an embodiment of the present invention.

  Referring to FIG. 1, hybrid vehicle 100 includes an engine 202, a power split mechanism 204, motor generators 206 and 210, a transmission gear 208, a drive shaft 212, and wheels 214. Hybrid vehicle 100 also includes power storage device 216, power converters 218 and 220, fuel tank 222, charger 224, ECU (Electronic Control Unit) 250, fuel supply port 260, charging connector 270, And a navigation device 300.

  Power split device 204 is coupled to engine 202, motor generator 206, and transmission gear 208 to distribute power among them. For example, a planetary gear having three rotation shafts of a sun gear, a planetary carrier, and a ring gear can be used as the power split mechanism 204, and these three rotation shafts are connected to the rotation shafts of the engine 202, the motor generator 206, and the transmission gear 208, respectively. Is done.

  Kinetic energy generated by the engine 202 is distributed to the motor generator 206 and the transmission gear 208 by the power split mechanism 204. That is, engine 202 is incorporated in hybrid vehicle 100 as a power source for driving motor generator 206 while driving transmission gear 208 that transmits power to drive shaft 212. The motor generator 206 is incorporated in the hybrid vehicle 100 so as to operate as a generator driven by the engine 202 and to operate as an electric motor that can start the engine 202. Motor generator 210 is incorporated in hybrid vehicle 100 as a power source for driving transmission gear 208 that transmits power to drive shaft 212.

  The power storage device 216 is a rechargeable DC power source, and is configured by a secondary battery such as nickel hydride or lithium ion, for example. The power storage device 216 supplies power to the power converters 218 and 220. Power storage device 216 is charged by receiving power from power converters 218 and / or 220 when motor generators 206 and / or 210 generate power.

  Furthermore, the power storage device 216 receives external power from the charging facility when the charging connector 270 is connected to a charging facility (not shown) outside the vehicle represented by a charging stand via the charging cable 280. Charging is performed by receiving electric power from a charger 224 that converts the electric power into the charging power of the power storage device 216.

  Output voltage VB, input / output current IB, and temperature TB of power storage device 216 are detected by a sensor (not shown), and the detected values are sent to ECU 250. In addition, the power storage device 216 is not limited to a secondary battery, and may be configured by an electric double layer capacitor or the like.

  Based on signal PWM 1 from ECU 250, power converter 218 converts the power generated by motor generator 206 into DC power and outputs it to power storage device 216. Power converter 220 converts DC power supplied from power storage device 216 into AC power based on signal PWM 2 from ECU 250 and outputs the AC power to motor generator 210. Power converter 218 converts DC power supplied from power storage device 216 into AC power and outputs it to motor generator 206 based on signal PWM 1 when engine 202 is started. In addition, power converter 220 converts the power generated by motor generator 210 into DC power based on signal PWM 2 and outputs it to power storage device 216 when the vehicle is braked or when acceleration is reduced on a downward slope.

  Motor generators 206 and 210 are AC motors, for example, three-phase AC synchronous motors in which a permanent magnet is embedded in a rotor. Motor generator 206 converts the kinetic energy generated by engine 202 into electrical energy and outputs it to power converter 218. Motor generator 206 generates driving power by the three-phase AC power received from power converter 218 and starts engine 202.

  Motor generator 210 generates vehicle driving torque by the three-phase AC power received from power converter 220. Motor generator 210 also converts mechanical energy stored in the vehicle as kinetic energy or positional energy into electrical energy and outputs it to power converter 220 when braking the vehicle or reducing acceleration on a downward slope.

  Engine 202 converts thermal energy generated by fuel combustion into kinetic energy of a moving element such as a piston or a rotor, and outputs the converted kinetic energy to power split mechanism 204. For example, if the motion element is a piston and the motion is a reciprocating motion, the reciprocating motion is converted into a rotational motion via a so-called crank mechanism, and the kinetic energy of the piston is transmitted to the power split mechanism 204. The fuel for the engine 202 is preferably a hydrocarbon fuel such as gasoline, light oil, ethanol, liquid hydrogen, natural gas, or a liquid or gaseous hydrogen fuel.

  The fuel tank 222 stores the fuel supplied from the fuel supply port 260 and supplies the stored fuel to the engine 202. The remaining fuel amount FL in the fuel tank 222 is detected by a sensor (not shown), and the detected value is output to the ECU 250.

  Based on signal PWM 3 from ECU 250, charger 224 converts electric power from an external power source supplied to charging connector 270 into charging power for power storage device 216 and outputs the power to power storage device 216.

  ECU 250 performs arithmetic processing based on a signal transmitted from each sensor, a map stored in a ROM (Read Only Memory) 252 and a program, and controls devices so that hybrid vehicle 100 is in a desired driving state. To do. Alternatively, at least a part of the ECU 250 may be configured to execute predetermined numerical / logical operation processing by hardware such as an electronic circuit.

  Specifically, ECU 250 generates signals PWM1 and PWM2 for driving power converters 218 and 220, respectively, and outputs the generated signals PWM1 and PWM2 to power converters 218 and 220, respectively. When ECU 250 receives signal REQ requesting charging of power storage device 216 by charger 224, ECU 250 generates signal PWM 3 for driving charger 224, and outputs the generated signal PWM 3 to charger 224.

  The configuration for external charging of hybrid vehicle 100 is not limited to the example shown in FIG. 1, and power from a charging facility (not shown) can be converted into charging power for power storage device 216 during parking. Any configuration can be applied. For example, the arrangement of the charger 224 dedicated to external charging may be omitted, and power from the external power source supplied to the charging connector 270 may be converted into charging power for the power storage device 216 by the power converters 218 and 220.

  Alternatively, without using the charging cable 280, a charging facility (not shown) and the hybrid vehicle 100 are electromagnetically coupled in a non-contact manner to supply power, specifically, a primary coil is provided on the external power supply side. While being provided, external charging may be performed by a configuration in which a secondary coil is provided on the vehicle side (charging connector 270) and electric power is supplied using mutual inductance between the primary coil and the secondary coil.

  Further, ECU 250 selects a travel mode of hybrid vehicle 100 as part of travel control. Specifically, the engine 202 is stopped and the EV mode (electricity drive) using only the motor generator 210 is mainly applied, whereby the CD mode in which the electric power of the power storage device 216 is preferentially used, and the engine 202 One of the CS modes in which the remaining capacity (SOC) of the power storage device 216 is maintained in a certain range by the operated HV traveling (hybrid traveling) is selected.

  Further, ECU 250 travels using electric power based on the remaining fuel amount FL of fuel tank 222 and the detected values of voltage VB and current IB of power storage device 216, or further based on other information not shown. It is also possible to generate and manage information on fuel consumption and information on fuel consumption and display them on a display unit (not shown). In addition, between the ECU 250 and the navigation device 300, information INF related to the selection of the travel mode is transmitted and received.

  FIG. 2 is a block diagram illustrating travel control related to travel mode selection in the hybrid vehicle shown in FIG. For each functional block shown in FIG. 2, a circuit (hardware) having a function corresponding to the block may be configured in the ECU 250, or the ECU 250 executes software processing according to a preset program. May be realized.

  Referring to FIG. 2, ECU 250 includes a travel mode selection unit 251, a hybrid control unit 252, a battery control unit 254, and an engine control unit 256.

  Traveling mode selection unit 251 selects one of the CD mode and the CS mode according to the vehicle state of hybrid vehicle 100. When the mode selection switch 145 is installed in the hybrid vehicle 100, the traveling mode selection unit 251 may forcibly select one of the CD mode and the CS mode in accordance with a user input to the mode selection switch 145. . The input to the mode selection switch 145 is performed in such a manner that any one of the travel modes is forcibly designated or prohibited.

  FIG. 3 is a conceptual diagram showing the relationship between the selection of the travel mode and the transition of the remaining capacity (SOC) of power storage device 216.

  In FIG. 3, the CD mode is selected in the period from departure (travel distance L = 0) to L = L1, the period L = L2 to L3, and the period L = L4 to L5, and L = L1 to L2 An example in which the CS mode is selected is shown in the period of L = L3 to L4 and the period of L> L5.

  As shown in FIG. 3, during selection of the CD mode, hybrid control unit 252 (FIG. 2) basically stops engine 202 and ensures vehicle drive power only by the output of motor generator 210. Thus, the engine 202 and the motor generators 206 and 210 are controlled. In other words, in the CD mode, internal charging of power storage device 216 is restricted, and basically, power generation operation by motor generator 206 by the output of engine 202 is not performed. As a result, the SOC of power storage device 216 decreases as the vehicle travels.

  In contrast, during the CS mode selection, internal charging by motor generator 206 is controlled such that SOC of power storage device 216 is maintained within a predetermined control range. That is, when the SOC falls outside the predetermined control range, the engine 202 also starts to operate in response to the start of internal charging by the motor generator 206. A part of the driving power generated by the operation of engine 202 may be used for running hybrid vehicle 100.

  On the other hand, when the SOC rises out of the predetermined control range, vehicle traveling that actively uses the electric power of power storage device 216 is directed. As a result, the SOC during the CS mode changes so as to be maintained within a predetermined control range.

  Referring to FIG. 2 again, battery control unit 254 calculates the SOC of power storage device 216 based on output voltage VB, input / output current IB, and temperature TB of power storage device 216, and also charges / discharges power storage device 216. An output power upper limit value Wout and an input power upper limit value Win that indicate possible power are set. For example, the SOC can be calculated based on the input / output current IB (charge / discharge current). Alternatively, the SOC may be obtained by further reflecting the output voltage VB and the temperature TB. Output power upper limit value Wout and input power upper limit value Win can be set mainly based on the SOC and temperature of power storage device 216 according to a predetermined relational expression, a map, or the like.

  The engine control unit 256 performs throttle control of the engine 202, detects the engine speed Ne of the engine 202, and transmits it to the hybrid control unit 252.

  The hybrid control unit 252 calculates the total required power for the entire vehicle based on the output signal Acc of the accelerator position sensor 142 and the vehicle speed V detected by the vehicle speed sensor 144. This total required power may also include power (engine output) required for generating charging power for power storage device 216 by motor generator 206.

  Hybrid control unit 252 manages engine 202 so that charging / discharging power of power storage device 216 falls within the range of output power upper limit value Wout to input power upper limit value Win according to the calculated total required power. The output power sharing between the motor generators 210 is determined, and the required rotation speed and the required power (torque) are further set for each of the engine 202 and the motor generators 206 and 210 according to the sharing result.

  The above-mentioned traveling mode is reflected in this output power sharing. For example, when the CD mode is selected, if the total required power is equal to or less than the output power upper limit value Wout of power storage device 216, hybrid control unit 252 causes motor generator 210 to output torque so that total required power is output by motor generator 210. While setting the command, the engine 202 is instructed to stop.

  On the other hand, when the total required power is larger than the output power upper limit value Wout, the hybrid control unit 252 determines the output power sharing so that the engine 202 can obtain an output. As described above, the CD mode is intended to improve the fuel consumption rate by maintaining the engine 202 in a stopped state. However, when a driving force request such as sudden acceleration is given from the user, the engine 202 Is started. Alternatively, the hybrid control unit 252 operates the engine 202 even when an engine start request that is not related to a driving force request such as a catalyst warm-up or an air conditioning request is issued.

  On the other hand, when the CS mode is selected, the hybrid control unit 252 determines the output power sharing so that the overall fuel efficiency is optimized.

  The hybrid control unit 252 transmits the required rotation speed and the required power to the engine control unit 256, and causes the engine control unit 256 to perform throttle control of the engine 202. Furthermore, hybrid control unit 252 generates control commands (signals PWM1 and PWM2 in FIG. 1) for power converters 218 and 220 that control motor generators 206 and 210 so that the output power of motor generator 210 follows the above sharing. .

  The navigation device 300 includes a navigation control unit 310, a GPS antenna 320, a beacon receiving unit 330, a gyro sensor 340, a display unit 350, an interface unit 360, and a storage unit 370.

  The navigation control unit 310 is typically configured by an electronic control unit (ECU) similar to the ECU 250, and performs route guidance for setting a travel route to the destination. Typically, the navigation control unit 310 obtains information on the destination set by the user from the display unit 350 including a touch display. It should be noted that, through the present embodiment, any known method can be applied as a method for searching for a travel route to a once set destination, and therefore detailed description will not be given.

  Further, the navigation control unit 310 reads road map information (data) recorded on a recording medium 355 such as a CD (Compact Disk) and a DVD (Digital Versatile Disk) via the interface unit 360. The road map data preferably includes information on charging facilities (charging stations) for externally charging the hybrid vehicle 100, for example, information indicating its position and charging capability (particularly charging speed). Storage unit 370 is an HDD (Hard Disk Drive), for example, and can store road map data in a nonvolatile manner. Note that the storage unit 370 may not be provided.

  Further, the navigation control unit 310 receives external information received from the beacon receiving unit 330 from the beacons installed on the road. For example, traffic information, required time, construction information, speed / lane regulation information, parking lot position / empty vehicle information, etc. can be acquired by external information from beacons, and access to a predetermined area where exhaust gas output is regulated Can also be recognized. Alternatively, information indicating a predetermined area may be stored in advance on the road map data.

  The navigation control unit 310 uses the GPS antenna 320 and the gyro sensor 340 or further uses the output (V) of the vehicle speed sensor 144 to grasp the vehicle position information, that is, the current position and the traveling direction of the vehicle. That is, "the vehicle position information" can be acquired by the GPS antenna 320, the gyro sensor 340, the vehicle speed sensor 144, or a part thereof.

  Then, the navigation control unit 310 displays the grasped vehicle position on the display unit 350 so as to overlap the road map data. Further, when the destination is set by the user, the navigation control unit 310 searches for a travel route from the current position to the destination and performs route guidance using the display unit 350. As is well known, as part of route guidance, voice guidance may be performed based on the relationship between the vehicle position and the searched travel route.

  Hereinafter, an example in which the travel mode is selected according to the own vehicle position of the hybrid vehicle 100 based on the output of the navigation device 300 (corresponding to the information INF in FIG. 1) will be described with reference to FIGS. To do. Note that the selection of the driving mode by the driving mode selection unit 251 is not limited to the following example, and information other than the vehicle position, for example, depending on the SOC of the power storage device 216 or a plurality of information Depending on the combination, the selection of the CS mode and the CD mode may be performed.

  Referring to FIG. 4, hybrid vehicle 100 includes a passage of specific travel areas 505 and 510 in travel route 500. For example, the traveling areas 505 and 510 correspond to urban areas, and the area outside the traveling areas 505 and 510 corresponds to suburbs.

  The traveling areas 505 and 510 may be areas where traveling by an engine with exhaust gas output is prohibited or charged due to environmental measures or the like. The travel areas 505 and 510 may be defined on the road map information (data), and detect the approach / entry / leaving to the travel areas 505 and 510 based on external information (beacons, etc.) from the outside of the vehicle. Also good. Moreover, about the mode which suppresses the output of the exhaust gas at the time of driving | running | working in an urban area, you may make it selectable by a user.

  The hybrid vehicle 100 travels with the output of exhaust gas suppressed by selecting the CD mode in the travel areas 505 and 510, while the CS mode is selected and travels outside the travel areas 505 and 510.

  Referring to FIG. 5, the driving mode is switched from the CS mode to the CD mode in response to entering the driving area 505 at the point where the driving distance L of the hybrid vehicle 100 becomes L2. As described above, in the CD mode, since the vehicle travels using the electric power of power storage device 216 with engine 202 stopped, the SOC gradually decreases. As indicated by a dotted line in FIG. 5, when the SOC decreases to the control lower limit SOCl during the CD mode selection, the travel mode is automatically switched to the CS mode to prevent overdischarge of the power storage device 216. May be switched automatically. If it does in this way, internal charge accompanying starting of engine 202 can be performed, and SOC can be recovered.

  Alternatively, referring to FIG. 4 again, when the travel route 500 has a charging point 530 such as a home equipped with a charging facility for external charging as the destination, the arrival time at the charging point 530 (travel distance) It is also possible to select the CD mode and the CS mode according to the travel distance to the charging point 530 so that the electric power of the power storage device 216 is used up for L = Lm).

  In this case, as shown in FIG. 6, based on the SOC of power storage device 216, travelable distance Lrs based only on the power of power storage device 216 is estimated and travel distance L = L4 (where Lm−L4 = The CD mode can be selected from the time when Lrs) is reached.

  In this way, since SOC = SOCl (management lower limit value) can be obtained upon arrival at the charging point 530, the fuel consumption of the hybrid vehicle 100 can be improved by effectively using the power of the power storage device 216.

  As described above, in the hybrid vehicle according to the present embodiment, when the CD mode is selected, vehicle driving power (running power) is basically secured only by the output power from power storage device 216. It is preferable that dischargeable power is secured.

  On the other hand, when the secondary battery constituting the power storage device 216 is continuously discharged, the output power may be reduced due to the bias of the ion concentration distribution inside the secondary battery. It has been discovered by the inventors that the phenomenon is particularly prominent in lithium ion secondary batteries.

  FIG. 7 is a waveform diagram showing the relationship between the charging / discharging operation of the secondary battery and the transition of the output power upper limit value.

  With reference to FIG. 7, the ion concentration gradient inside the secondary battery gradually changes as the discharge with IB> 0 continues. As a result, a phenomenon occurs in which the output power of the secondary battery decreases in addition to the decrease in the stored power (SOC) due to the continued discharge. The battery control unit 254 is configured to reflect the above phenomenon so as to lower the output power upper limit value Wout during continuous discharge. Note that the reduction in output power due to the above-described deviation in ion concentration gradient can also occur from the viewpoint of SOC management even when discharge stop or charge request is not required.

  When such a phenomenon occurs, it is possible to eliminate the bias of the ion concentration gradient by giving a reverse potential to the inside of the secondary battery by stopping the discharge and providing a charging period. Thereby, it is possible to recover the output power (output power upper limit Wout) of the secondary battery. At this time, unlike the relatively long-term charging for recovering the SOC, the output power of the secondary battery can be recovered by providing the charging period itself for a short period.

  Therefore, in the following, charging of power storage device 216 for a certain period for recovering dischargeable power (output power upper limit value Wout) by continuous discharging operation for a certain period will also be referred to as “recovery charging”. This return charge is not requested directly based on the SOC value, but is separate from the charge request generated from the aspect of SOC management.

  The hybrid vehicle power supply system according to the present embodiment is characterized in that an opportunity for return charging as shown in FIG. 7 is appropriately provided in association with selection of the driving mode.

  FIG. 8 shows a vehicle control processing procedure for providing an opportunity for return charging during CS mode selection in the hybrid vehicle power supply system according to the present embodiment. Control processing according to the flowchart shown in FIG. 8 is executed by ECU 250 at predetermined intervals.

  Referring to FIG. 8, ECU 250 determines in step S100 whether or not the traveling mode is the CS mode. When the driving mode is the CS mode (YES in S100), the following processing in steps S110 to S160 is performed. Execute.

  In step S110, ECU 250 determines whether the switching condition from the CS mode to the CD mode is satisfied based on the own vehicle position information in accordance with the travel mode selection described in FIGS. When the switching condition is not satisfied (NO determination in S110), ECU 50 proceeds to step S120 to determine whether a switching preliminary condition from the CS mode to the CD mode is satisfied.

  The switching preliminary condition in step S120 is a condition set in advance so as to be satisfied before the switching condition is satisfied in step S110. For example, when it is determined that the switching condition in S110 is satisfied when entering the traveling area 505, 510 (FIG. 4), the remaining distance until entering the traveling area 505, 510 is equal to or less than a predetermined value. It can be determined that the switching preliminary condition in step S120 is satisfied.

  Alternatively, in FIG. 6, when the remaining travel distance to the destination charging point 530 (FIG. 4) is shorter than the travelable distance Lrs using only the power of the power storage device 216, the switching condition in step S <b> 110 is established. On the other hand, when the remaining travel distance falls below the determination value set longer than Lrs, it can be determined that the switching preliminary condition in step S120 is satisfied.

  When the switching precondition is satisfied (YES in S120), ECU 250 generates a charge request for power storage device 216 by engine 202 in step S140, and maintains the CS mode in step S150. The charging request in step S140 is not charging for recovering the SOC, as described with reference to FIG. 7, but secures a charging period for the power storage device 216 for a certain period of time (typically, pulse charging of several seconds is considered). Is to do.

  Prior to execution of step S140, ECU 250 may further determine whether or not power storage device 216 is in a state requiring return charging in step S130. The determination in step S130 can be executed based on the state of the power storage device 216, such as the state of charge / discharge of the power storage device 216 up to the present time, the transition of the output power upper limit value Wout reflecting this, or the temperature TB of the power storage device 216. .

  For example, predetermined predetermined conditions such as when the output power upper limit Wout is below a predetermined value, when the power storage device 216 continues to be charged for a predetermined time, or when the battery temperature is low are satisfied. When step S130 is determined as YES and return charging is executed, if none of the predetermined conditions is satisfied, step S130 may be determined as NO and step S140 may be skipped.

  In this way, when the power storage device 216 is in a state that does not require return charging, it is not necessary to start the engine 202, so that unnecessary reduction in fuel consumption can be prevented.

  On the other hand, when YES is determined in step S110, ECU 250 proceeds to step S160 and switches the traveling mode to the CD mode. By providing the opportunity for return charging when switching from the CS mode to the CD mode by the processing of S120 to S140 at the time of NO determination of S110 as described above, the power storage device 216 can be operated immediately after switching to the CD mode. Sufficient output power can be secured.

  As a result, the CD mode can be started in a state where the dischargeable power (output power upper limit value Wout) of the power storage device 216 is reliably recovered. As a result, in the CD mode, the vehicle driving power that can be dealt with can be increased while maintaining the stop of the engine 202 while protecting the power storage device 216.

  When selecting the travel mode based on the SOC, the same processing procedure as described above can be realized by setting the SOC determination value step by step in the switching condition (S110) and the switching preliminary condition (S120). . Further, when selecting a travel mode in which it is difficult to foresee the establishment of the switching condition, a return charge is requested when the switch condition is satisfied (S130, S140), and the travel mode is changed after the completion of the return charge. As a processing procedure for actually switching to the CD mode, as in FIG. 8, an opportunity for return charging can be provided when switching from the CS mode to the CD mode.

  Next, return charging during CD mode selection in the power supply system of the hybrid vehicle according to the present embodiment will be described with reference to FIGS. The control processing according to the flowcharts shown in FIGS. 9 and 11 is executed by the ECU 250 at predetermined intervals.

  As described above, in the CD mode, the engine 202 is basically stopped. Therefore, it is not preferable to newly provide an operation opportunity of the engine 202 for return charging. For this reason, it is necessary to perform return charging so as not to increase the operation opportunity of the engine 202 unnecessarily.

  Referring to FIG. 9, ECU 250 determines in step S200 whether or not the running mode is the CD mode, and when in the CD mode (when YES is determined in S200), the following processing in steps S210 to S240 is performed. Execute.

  In step S220, the ECU 250 determines whether the engine 202 has already been started or a factor different from the return charge, such as a driving force request from the user or a catalyst warm-up request or a vehicle interior request different from the driving force request. It is determined whether a start request is issued to the engine 202 due to a heating request or the like.

  When engine 202 is starting or when there is a request to start engine 202 (YES in S210), ECU 250 causes total required power pp of the entire vehicle to be greater than engine maximum output power pemax in step S230. Is also determined whether it is too small. When pp <pemax (YES in S230), ECU 250 advances the process to step S240 to increase the output power of engine 202 from the originally required value. And then. With this increased power, engine output for performing return charging of the power storage device 216 is secured.

  The engine output for return charging in step S240 is ensured as shown in FIG.

  Referring to FIG. 10, it is assumed that engine 202 has already been started at a time prior to time ta and step S220 of FIG. 9 has been determined to be YES. In this situation, when the total required power pp is lower than the maximum output power pemax of the engine 202, as shown by the dotted line in FIG. 10, the output for return charging with respect to the original total required power value (pp = p1). The total required power pp is set so that the power Δp is added.

  This additional amount Δp of the total required power is reflected in the output required power of the engine 202. A charging current IB = −I1 for return charging can be generated by power generation of the motor generator 206 by Δp.

  When pp> pemax is satisfied by the user's accelerator pedal operation from time ta, the engine 202 cannot cover all of the total required power pp. Therefore, in order to secure vehicle driving power, power is output from the power storage device 216. (IB> 0).

  According to the present embodiment, it is easy to ensure the output power (Wout) of power storage device 216 after time tb by return charging before time ta. Thereby, as understood from the comparison between the dotted line (with return charging) and the solid line (without return charging) in FIG. 10, it becomes easier to secure the output power from the power storage device 216. As a result, it is possible to sufficiently respond to the user's driving power request (acceleration request), so that driving comfort can be improved.

  Referring to FIG. 9 again, whether or not power storage device 216 is in a state requiring return charge by executing step S210 similar to step S130 in FIG. 8 together with the control of return charge in steps S220 to S240. You may further determine whether.

  In this way, when the power storage device 216 is in a state that does not require return charging (NO in S210), it is unnecessary even if the engine 202 is being started or requested to start due to a factor other than return charging. Return charging can be disabled. As a result, it is possible to prevent the output of the engine 202 from being increased unnecessarily, so that fuel efficiency can be improved.

  Alternatively, when the CD mode is selected, as shown in FIG. 11, it is possible to predict the occurrence of an acceleration request from the user and execute return charging in advance.

  FIG. 11 shows a control processing procedure for securing an opportunity for return charging as required when the vehicle starts from a stop state in which the engine 202 is stopped.

  Referring to FIG. 11, ECU 250 determines in step S200 whether or not the running mode is the CD mode, and executes the processing of the subsequent steps when in the CD mode (when YES is determined in S200).

  In step S250, ECU 250 determines whether or not the vehicle is stopped. When the vehicle is stopped (YES in S250), the brake pedal (not shown) is changed from the on state to the off state in step S260. It is determined whether or not. In step S260, it can be detected that the brake pedal that has been depressed is released according to a comparison with the brake pedal depression force in the previous control cycle.

  Then, when YES is determined in S260, ECU 250 advances the process to step S270 to start engine 202 that has been stopped, or increases the output by Δp if engine 202 is in operation. The device 216 is recharged. If it does in this way, the output electric power (Wout) of the electrical storage apparatus 216 can be ensured in preparation for the subsequent depression of the accelerator pedal from the moment when the brake pedal is released when the vehicle starts from the stop. In other words, driving comfort can be improved by preventing a shortage of output power from the power storage device 216 corresponding to the acceleration request due to depression of the accelerator pedal.

  When any of steps S250 and S260 is NO, the vehicle state is not predicted to cause an acceleration request by the user immediately as described above. Therefore, step S270 is skipped and return charging is not executed. It is said.

  Alternatively, prior to steps SS250 and S260, step S210 similar to FIG. 9 may be further executed to further determine whether or not power storage device 216 is in a state that requires a return charge.

  In this way, when the power storage device 216 is in a state that does not require return charging (when NO is determined in S210), an unnecessary return is required even in a vehicle state in which an acceleration request from the user is predicted to be generated immediately thereafter. Charging can be disabled. As a result, it is possible to prevent the engine 202 from being started unnecessarily for the purpose of return charging, so that fuel consumption can be improved.

  As described above, according to the present embodiment, in the hybrid vehicle configured to perform the driving mode selection including the CS mode and the CD mode, the SOC management is performed at the time of transition from the CS mode to the CD mode. By executing the return charging independently, the CD mode in which the vehicle travels mainly by the motor output can be started in a state where the dischargeable power (Wout) of the power storage device 216 is reliably recovered. In addition, even when traveling in the CD mode, it is possible to appropriately provide a return charging opportunity without unnecessarily increasing the operation opportunity of the engine 202.

  As a result, in hybrid vehicle 100, the vehicle drive power that can be handled by the electric power from power storage device 216 can be increased while protecting power storage device 216 during traveling in the CD mode.

  In the present embodiment, for hybrid vehicle 100 (FIG. 1), a configuration that can be charged by a charging facility outside the vehicle is illustrated, but application of the present invention is not limited to the hybrid vehicle having such a configuration. . That is, in hybrid vehicle 100, the configuration for external charging represented by charger 224 (FIG. 1) is not essential, and the driving mode is selected between the CS mode and the CD mode. In the case of a hybrid vehicle having a transition to, the fact that the present invention can be applied even if the power storage device 216 is not configured to be externally charged will be described in a confirming manner.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. 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.

  The present invention can be applied to a hybrid vehicle that selects a traveling mode between a CD mode and a CS mode.

  100 hybrid vehicle, 142 accelerator position sensor, 144 vehicle speed sensor, 145 mode selection switch, 202 engine, 204 power split mechanism, 206, 210 motor generator, 208 transmission gear, 212 engine, 214 wheel, 216 power storage device, 218, 220 power Converter, 222 Fuel tank, 224 Charger, 251 Driving mode selection unit, 252 Hybrid control unit, 254 Battery control unit, 256 Engine control unit, 260 Fuel supply port, 270 Charging connector, 280 Charging cable, 300 Navigation device, 310 Navigation control unit, 320 antenna, 330 beacon receiving unit, 340 gyro sensor, 350 display unit, 355 recording medium, 360 interface unit, 370 storage unit, 50 Traveling path, 505, 510 Traveling area, 530 Charging point, FL Fuel remaining amount, IB input / output current (power storage device), INS information (traveling mode selection), L traveling distance, Lrs Travelable distance (EV), Ne engine rotation Number, pemax engine output maximum power, pp total required power, PWM1, PWM2, PWM3 signal, SOCI SOC management lower limit value, TB temperature (power storage device), V vehicle speed, VB output voltage (power storage device), Win input power upper limit value, Wout Output power upper limit, Δp Additional output power (return charge).

Claims (9)

A power supply system for a hybrid vehicle equipped with an internal combustion engine and an electric motor as a power source,
A power storage device configured to be able to input and output power to the motor;
A power generation unit for generating charging power of the power storage device by an output of the internal combustion engine;
A charge / discharge control unit configured to estimate a remaining capacity of the power storage device based on a state detection value of the power storage device;
A first traveling mode in which the internal combustion engine and the electric motor are used so as to travel while maintaining the remaining capacity of the power storage device within a predetermined control range, and traveling mainly by the motor using the power of the power storage device. A travel mode selection unit configured to select one of the internal combustion engine and the second travel mode using the electric motor;
A hybrid control unit configured to control the internal combustion engine and the electric motor based on a selection result by the travel mode selection unit;
The hybrid control unit instructs the execution of the internal charging for return charging for returning the dischargeable power of the power storage device upon transition from the first driving mode to the second driving mode. A hybrid vehicle power system.   The hybrid vehicle power supply system according to claim 1, wherein the hybrid control unit instructs execution of the internal charging for the return charging regardless of the estimated value of the remaining capacity. The hybrid vehicle further includes a navigation device configured to be able to acquire own vehicle position information of the hybrid vehicle and at least one of road map information and external information from outside the vehicle,
The travel mode selection unit is configured to select one of the first and second travel modes based on the relationship between the vehicle position information and the at least one information,
The hybrid control unit, when the first traveling mode is selected, returns when the predetermined switching preliminary condition set to be satisfied before the switching condition to the second traveling mode is satisfied. The power supply system for a hybrid vehicle according to claim 1, wherein execution of the internal charging is instructed for charging.   The hybrid control unit further determines whether or not the return charging is necessary in accordance with a state of the power storage device at the time of transition from the first travel mode to the second travel mode. The power supply system of the hybrid vehicle of Claim 1.   The hybrid control unit further performs the internal charging for the return charging when the vehicle condition satisfies a predetermined condition regardless of the estimated value of the remaining capacity when the second traveling mode is selected. The power supply system for a hybrid vehicle according to claim 1, wherein execution is instructed.   When the internal combustion engine is started by a request different from the return charge when the second travel mode is selected, the hybrid control unit determines that the total required power for travel of the hybrid vehicle is the internal combustion engine 6. The power supply system for a hybrid vehicle according to claim 5, wherein when the engine output is lower than a maximum output value of the engine, execution of the internal charging is instructed by increasing the output of the internal combustion engine from the output according to the request.   The hybrid control unit, when the second traveling mode is selected, when the brake pedal transitions from an on state to an off state in a stopped state where the internal combustion engine is stopped, by the start of the internal combustion engine or an increase in output, The power supply system for a hybrid vehicle according to claim 5, wherein execution of the internal charging for the return charging is instructed.   The hybrid according to any one of claims 5 to 7, wherein the hybrid control unit further determines whether or not the return charging is necessary according to a state of the power storage device when the second traveling mode is selected. Vehicle power system.   The power supply system for a hybrid vehicle according to any one of claims 1 to 8, further comprising a charger configured to charge the power storage device with a power supply external to the vehicle.

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