JP2019170010A - Hybrid vehicle - Google Patents

Abstract

To inhibit generation of a memory effect in a nickel hydrogen battery with an SOC that is not a presupposition.SOLUTION: A control device of a hybrid vehicle provided with an internal combustion engine and a nickel hydrogen battery, is configured to generate power by using a motive power output from the internal combustion engine, to charge the nickel hydrogen battery with the generated power, and to stop the charging when an SOC of the nickel hydrogen battery reaches a charge stop SOC during the charge. In the case where the frequency that the SOC of the nickel hydrogen battery falls within a target SOC region (e.g., high-SOC region) is lower than a boundary value, when the charge stop SOC is within the target SOC region and the frequency in the target SOC region is higher than the boundary value, the control device changes the charge stop SOC to an SOC outside the target SOC region (step S34).SELECTED DRAWING: Figure 7

Description

  The present disclosure relates to a hybrid vehicle, and more specifically, to a technique for performing charge control of a nickel metal hydride battery mounted on a hybrid vehicle.

  The hybrid vehicle is configured to be able to travel using both the power output from the internal combustion engine and the power output from the motor that receives the electric power stored in the battery. Even when the hybrid vehicle is stopped (for example, parked), the internal combustion engine may be moved for the purpose of heating the interior of the vehicle or activating a catalyst (for example, an exhaust purification catalyst). Japanese Patent Laying-Open No. 2010-36788 (Patent Document 1) discloses a technique for charging a battery by generating power using power output from an internal combustion engine that is driven during heating in a vehicle interior. Hereinafter, power generation using power output from the internal combustion engine may be referred to as “engine power generation”. Moreover, the electric power generated by the engine power generation may be referred to as “engine generated power”.

JP 2010-36788 A

  A nickel metal hydride battery is known as a battery mounted on a hybrid vehicle. In addition, it is known that a memory effect occurs in a nickel metal hydride battery. The memory effect refers to the discharge voltage of the nickel-metal hydride battery in the initial state (that is, the memory effect) when charging in a state where the power stored in the nickel-metal hydride battery is not completely consumed (so-called supplementary charging) is repeated. This is a phenomenon that is lower than when no occurrence occurs. The memory effect may occur on the charging side of the nickel metal hydride battery, and the charging voltage is higher on the charging side than in the initial state.

  When a nickel metal hydride battery (battery) is charged with engine generated power, a charge stop condition may be determined by SOC (State Of Charge). For example, it is conceivable that charging is performed until the SOC of the nickel metal hydride battery reaches a predetermined SOC (hereinafter referred to as “charging stop SOC”). When the hybrid vehicle is stopped or at low load, the nickel-metal hydride battery consumes little power because the power of the nickel-metal hydride battery is hardly used for running the hybrid vehicle. For this reason, when the hybrid vehicle is stopped or when the load is low, the above-described charging control is executed, and once the nickel metal hydride battery is charged to the charge stop SOC by the engine generated power, the power of the nickel metal hydride battery is thereafter Is consumed mainly by auxiliary loads (lighting device, audio device, etc.), and the nickel hydrogen battery is charged by the generated power by the consumed amount. That is, after the charging is stopped at the charging stop SOC, the charging and discharging of the nickel metal hydride battery is repeated in the vicinity of the charging stop SOC until the hybrid vehicle starts running at a high load. When the charge stop SOC is maintained at the same value, the charge / discharge of the nickel metal hydride battery is repeatedly executed with the same SOC.

  When the charge and discharge of the nickel metal hydride battery is repeatedly performed with the same SOC, the memory effect is likely to occur in the nickel metal hydride battery with the SOC. Hereinafter, the SOC in which the memory effect has occurred may be referred to as “SOCm”. In a nickel metal hydride battery in which a memory effect is generated in SOCm, a graph showing a relationship between SOC and OCV (Open Circuit Voltage) (hereinafter sometimes referred to as “SOC-OCV curve”), an SOC region lower than SOCm The OCV of the SOC region becomes lower than the initial state, and the OCV of the SOC region higher than the SOCm becomes higher than the initial state. When the SOC is estimated from the OCV of the nickel-metal hydride battery using a map showing a predetermined SOC-OCV curve, the memory effect causes a gap between the actual SOC-OCV curve and the SOC-OCV curve shown on the map. In some cases, the SOC estimation accuracy may be reduced.

  In order to improve the estimation accuracy of the SOC, it is assumed that a memory effect is produced in the nickel-metal hydride battery with a predetermined SOC (hereinafter referred to as “correction standard SOC”) (that is, the correction standard SOC matches SOCm). It is also conceivable to correct the map on the basis of the correction reference SOC. However, even if such correction is performed, if a memory effect occurs in the nickel-metal hydride battery with SOCm other than the preconditions, the actual SOC-OCV curve and the SOC-OCV curve indicated by the corrected map There will be a gap between the two. For this reason, the above correction may not be effective depending on the SOCm.

  In addition, when the memory effect occurs in the nickel-metal hydride battery, the OCV in the SOC region higher than the SOCm increases, so that depending on the SOCm, gas may be easily generated in the battery case. For example, when a nickel metal hydride battery is overcharged, a side reaction occurs and oxygen gas is generated from the positive electrode. When gas is generated in the battery case, the battery internal pressure increases, and the SOC region (battery use region) where the battery can be used tends to be narrowed.

  This indication is made in order to solve the above-mentioned subject, and the object is to control that the memory effect of a nickel metal hydride battery occurs in SOC outside a precondition.

  The hybrid vehicle of the present disclosure includes an internal combustion engine, a nickel metal hydride battery, and a control device. The control device generates power using the power output from the internal combustion engine to charge the nickel metal hydride battery, and stops charging when the SOC of the nickel metal hydride battery becomes a charge stop SOC during the charging. Composed. The frequency (hereinafter referred to as “target SOC frequency”) at which the SOC of the nickel metal hydride battery is within a predetermined SOC region (hereinafter referred to as “target SOC region”) is greater than a predetermined value (hereinafter referred to as “boundary value”). When it is low, the charge stop SOC is in the target SOC region, and when the target SOC frequency is higher than the boundary value, the charge stop SOC is changed to an SOC outside the target SOC region by the control device. Composed.

  For example, the frequency for each SOC region is obtained by periodically counting (integrating) the frequency (frequency) for each SOC region. The target SOC frequency can be acquired from, for example, the SOC frequency distribution of a nickel metal hydride battery. In a typical SOC frequency distribution, a plurality of sections (that is, SOC regions) are provided on the horizontal axis according to the SOC size, and an SOC region (SOC numerical range) provided on the horizontal axis on the vertical axis. Shows the frequency of each. Of the plurality of SOC regions provided on the horizontal axis of the SOC frequency distribution, the frequency of the target SOC region corresponds to the target SOC frequency.

  The SOC of the nickel metal hydride battery may be the SOC of one nickel metal hydride battery (unit cell) or the SOC of a battery module including a plurality of nickel metal hydride batteries. The SOC indicates the remaining amount of power storage. For example, the ratio of the current power storage amount to the fully charged power storage amount is expressed as 0 to 100%.

  In the above control device, the nickel-metal hydride battery is charged with the engine power, and if the SOC of the nickel-metal hydride battery becomes the charge stop SOC during the charge, the charge is stopped. For this reason, when the hybrid vehicle is stopped or during low load, the nickel metal hydride battery is repeatedly charged and discharged near the charge stop SOC. When the target SOC frequency is lower than the boundary value, the charge stop SOC is in the target SOC region. Therefore, when charge / discharge of the nickel metal hydride battery is repeatedly executed near the charge stop SOC, the target SOC frequency increases.

  When the target SOC frequency becomes higher than the boundary value, the control device changes the charge stop SOC to an SOC outside the target SOC region. Thereby, charging / discharging of the nickel metal hydride battery is repeatedly executed outside the target SOC region, and the occurrence of the memory effect in the target SOC region is suppressed.

  In the above control device, it is possible to suppress the occurrence of the memory effect in the target SOC region. In other words, it is preferable to set the SOC area where the memory effect is not desired to be generated as the target SOC area. The number of target SOC areas is not limited to one, and may be arbitrary, and a plurality of target SOC areas may be set. Different boundary values may be provided for each target SOC region.

  By suppressing the occurrence of the memory effect in the target SOC region, the possibility that the memory effect occurs in the SOC region outside the target SOC region becomes relatively high. By utilizing this fact, the SOCm can be controlled within the SOC region outside the target SOC region (hereinafter, sometimes referred to as “target SOCm region”). More specifically, when the target SOC frequency becomes higher than the boundary value, the memory effect may be generated in the SOC in the target SOCm region by changing the charge stop SOC to the SOC in the target SOCm region. Increases nature.

  The determination of whether the target SOC frequency of the nickel metal hydride battery is higher or lower than the boundary value may be made in a predetermined cycle, or may be made only when a predetermined memory effect generation condition is satisfied.

  The memory effect generation condition is set so as to be satisfied when the memory effect in the nickel-metal hydride battery is not saturated and the SOC-OCV curve of the nickel-metal hydride battery can change due to the generation of a further memory effect. The above-mentioned memory effect generation condition can be determined by the usage history of the nickel metal hydride battery. The memory effect occurrence condition is, for example, an elapsed time (for example, a usage time of a nickel metal hydride battery) measured by a timer when the integrated travel distance of the hybrid vehicle measured by the odometer is within a predetermined value and / or a timer. It may be established when it is within a predetermined value.

  The hybrid vehicle may include a heating device that heats the inside of the vehicle (for example, the vehicle interior) using the internal combustion engine as a heat source. And while said control apparatus performs heating, it generates electric power using the motive power output from an internal combustion engine during the execution of the heating, charges a nickel metal hydride battery, It may be configured to stop charging when the SOC becomes the charge stop SOC.

  As the target SOC region, an SOC region (hereinafter, may be referred to as a “high SOC region”) defined within a range of SOC 65% to 100% may be employed. When the target SOC frequency is higher than the boundary value, the charge stop SOC may be changed to a lower SOC than the target SOC region (high SOC region) by the control device.

  Note that “determined within the range of SOC 65% to 100%” means that both the upper limit SOC and the lower limit SOC that define the SOC region are within the range of 65% to 100%. That is, the SOC region of 65% or more and 80% or less corresponds to the high SOC region. On the other hand, the SOC region of 30% to 65% does not correspond to the high SOC region.

  According to the above configuration, in a situation where the target SOC frequency is lower than the boundary value, the SOC of the nickel-metal hydride battery is high in engine generated power generated during heating or the like (charging stop SOC included in the range of SOC 65% to 100%) It is possible to improve energy efficiency by charging up to. However, since the nickel-metal hydride battery is charged and discharged in the vicinity of the charge stop SOC when the hybrid vehicle is stopped or when the load is low, the frequency of the high SOC region tends to increase when the charge stop SOC as described above is employed. Therefore, in the hybrid vehicle control apparatus, when the frequency of the high SOC region increases, the charge stop SOC is lowered so that charging is not performed until the SOC is high. By doing so, it is possible to avoid the nickel metal hydride battery from being repeatedly charged and discharged in the high SOC region. And generation | occurrence | production of the memory effect in a high SOC area | region (as a result, the raise of a charging voltage) can be suppressed.

  According to the present disclosure, it is possible to suppress the memory effect of the nickel-metal hydride battery from occurring in SOCs other than the preconditions.

1 is a block diagram schematically showing an overall configuration of a hybrid vehicle according to an embodiment of the present disclosure. It is a figure which shows the structure of one cell contained in the battery shown in FIG. It is a figure which shows an actual SOC-OCV curve when a battery is used by 1st SOC frequency distribution. It is a figure which shows an actual SOC-OCV curve when a battery is used by 2nd SOC frequency distribution. It is the flowchart which showed the processing procedure of SOC frequency distribution preparation performed by the control apparatus of the hybrid vehicle according to embodiment of this indication. It is the flowchart which showed the process sequence of the charge control performed by the control apparatus of the hybrid vehicle according to embodiment of this indication. It is the flowchart which showed the process sequence of the charge stop SOC setting performed by the control apparatus of the hybrid vehicle according to embodiment of this indication. It is a figure which shows the object SOC area | region which concerns on embodiment of this indication. It is a figure which shows an example of SOC frequency distribution of a battery. It is a figure which shows an example of the change of SOC frequency distribution by changing charge stop SOC.

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

  FIG. 1 is a block diagram schematically showing an overall configuration of a vehicle 1 on which a control device according to this embodiment is mounted.

  Referring to FIG. 1, vehicle 1 includes motor generators (hereinafter referred to as “MG (Motor Generator)”) 11, 12, engine 20, drive wheels 30, power split device 31, and drive shaft 32. , Power control unit (hereinafter referred to as “PCU (Power Control Unit)”) 40, system main relay (hereinafter referred to as “SMR (System Main Relay)”) 50, battery system 2, and heating device 3 Is provided.

  The battery system 2 includes a battery 100, a voltage sensor 210, a current sensor 220, a temperature sensor 230, and an electronic control unit (hereinafter referred to as “ECU (Electronic Control Unit)”) 300. The ECU 300 corresponds to an example of a “control device” according to the present disclosure.

  The heating device 3 is configured to heat the interior of the passenger compartment 500 (the space in the vehicle 1 on which an occupant rides) using the engine 20 as a heat source. The heating device 3 includes a heat exchanger 401, a blower device 402, and a switching device 403.

  Vehicle 1 is a hybrid vehicle configured to be able to travel using both the power output from engine 20 and the electric power stored in battery 100.

  The battery 100 is a DC power source configured to be rechargeable. The battery 100 includes an assembled battery including a plurality of secondary batteries. In this embodiment, the assembled battery included in the battery 100 includes a plurality of nickel metal hydride batteries connected in series. A nickel metal hydride battery is a secondary battery having a positive electrode, a negative electrode, and an aqueous electrolyte (for example, an alkaline aqueous solution) in a case. Hereinafter, a secondary battery (in this embodiment, a nickel metal hydride battery) constituting the assembled battery is referred to as a “cell”.

  FIG. 2 is a diagram illustrating a configuration of the cell 101 included in the battery 100. Since the configuration of each cell 101 is common, only one cell 101 is representatively shown in FIG. In FIG. 2, the electrode body 104 is shown through a part of the case 102 of the cell 101.

  Referring to FIG. 2, cell 101 is a square sealed cell including a metal case 102, for example. In the case 102, an electrode body 104 and an electrolytic solution (not shown) constituting a nickel metal hydride battery are accommodated. A gas release valve 103 is provided on the upper portion of the case 102.

  The case 102 is a square case including a case main body and a lid made of metal, and the lid is hermetically sealed by being welded around the opening of the case main body. The gas release valve 103 is opened when the pressure in the case 102 (cell internal pressure) exceeds a predetermined valve opening pressure, and discharges a part of the gas (oxygen gas or the like) in the case 102 to the outside.

  The electrode body 104 includes a positive electrode plate, a negative electrode plate, and an insulating separator. The positive electrode plate and the negative electrode plate are alternately stacked via separators. That is, an insulating separator is sandwiched between the positive electrode plate and the negative electrode plate. The positive electrode plate and the negative electrode plate are electrically connected to a positive electrode terminal and a negative electrode terminal (not shown), respectively.

As the material of the electrode body 104 and the electrolyte solution constituting the nickel metal hydride battery, a material arbitrarily selected from various known materials can be used as the material of the nickel metal hydride battery. In this embodiment, the positive electrode plate includes a positive electrode active material layer containing a solid solution of nickel hydroxide (Ni (OH) ₂ or NiOOH) and a cobalt compound, and an active material support (foamed nickel or the like). An electrode plate is used. The positive electrode plate may be subjected to higher-order Na treatment. An electrode plate containing a hydrogen storage alloy is used for the negative electrode plate. The hydrogen storage alloy is, for example, an alloy of a metal (Ti, Zr, Pd, Mg, etc.) excellent in hydrogen storage capacity and a metal (Fe, Co, Ni, etc.) excellent in hydrogen release capacity. For the separator, a nonwoven fabric made of a synthetic fiber that has been subjected to a hydrophilic treatment is used. An alkaline aqueous solution containing potassium hydroxide (KOH) or sodium hydroxide (NaOH) is used for the electrolytic solution.

  Referring again to FIG. 1, PCU 40 performs bidirectional power conversion between battery 100 and MGs 11 and 12 in accordance with a control signal from ECU 300. The PCU 40 is configured to be able to control the states of the MGs 11 and 12 separately. For example, the PCU 40 can place the MG 12 in a power running state while the MG 11 is in a regenerative (power generation) state. PCU 40 includes, for example, two inverters provided corresponding to MGs 11 and 12 and a converter that boosts a DC voltage supplied to each inverter to an output voltage of battery 100 or higher.

  MGs 11 and 12 are AC rotating electric machines, for example, three-phase AC synchronous motors in which permanent magnets are embedded in a rotor. The MG 11 is mainly used as a generator driven by the engine 20 via the power split device 31. The electric power generated by the MG 11 is supplied to the MG 12 or the battery 100 via the PCU 40.

  The MG 12 mainly operates as an electric motor and drives the drive wheels 30. The MG 12 is driven by receiving at least one of the electric power from the battery 100 and the electric power generated by the MG 11, and the driving force of the MG 12 is transmitted to the drive shaft 32. On the other hand, when the vehicle is braked or when acceleration is reduced on a downward slope, the MG 12 operates as a generator and performs regenerative power generation. The electric power generated by the MG 12 is supplied to the battery 100 via the PCU 40.

  The SMR 50 is electrically connected to a current path connecting the battery 100 and the PCU 40. When SMR 50 is closed in response to a control signal from ECU 300, power can be exchanged between battery 100 and PCU 40.

  The voltage sensor 210 detects the voltage of the battery 100 (inter-terminal voltage). Current sensor 220 detects current IB input / output to / from battery 100. The current IB during charging is represented by a positive number, and the current IB during discharging is represented by a negative number. The temperature sensor 230 detects the temperature of the battery 100. Each sensor outputs the detection result to ECU 300.

  The engine 20 is an internal combustion engine that outputs power by converting combustion energy generated when an air-fuel mixture is burned into kinetic energy of a moving element such as a piston or a rotor. The power split device 31 includes, for example, a planetary gear mechanism having three rotation shafts of a sun gear, a carrier, and a ring gear. Power split device 31 splits the power output from engine 20 into power for driving MG 11 and power for driving drive wheels 30.

  A cooling system (not shown) of the engine 20 is configured such that the engine 20 is cooled by circulating cooling water around the engine 20. The temperature of the cooling water of the engine 20 changes according to the temperature of the engine 20. Water temperature sensor 410 detects the temperature of cooling water of engine 20 (cooling water temperature TW) and outputs the detection result to ECU 300.

  The heat exchanger 401 is attached to the cooling system of the engine 20 and configured to exchange heat between the air input from the switching device 403 and the cooling water of the engine 20. The blower 402 is configured to blow air output from the heat exchanger 401 into the passenger compartment 500. As the blower 402, for example, a fan or a blower can be adopted. The switching device 403 is configured to switch between outside air (air outside the vehicle) and air inside the passenger compartment 500 to be sent to the heat exchanger 401. The outside air temperature sensor 420 detects the outside air temperature (outside air temperature TA1). The vehicle interior sensor 430 detects the temperature in the vehicle interior 500 (indoor temperature TA2). Each sensor outputs the detection result to ECU 300. The blower 402 and the switching device 403 operate according to a control signal from the ECU 300.

  Combustion energy generated in the engine 20 is converted not only into kinetic energy but also into heat energy. The heating device 3 uses the thermal energy to heat the passenger compartment 500. More specifically, when the engine 20 is stopped in a situation where the outside air temperature is low (for example, in winter), the temperature of the engine 20 (and thus the cooling water temperature TW) decreases. In such a case, when there is a heating execution request from the user, the ECU 300 operates the engine 20 to increase the coolant temperature TW to a temperature suitable for heating (for example, 50 ° C. to 60 ° C.). When the engine 20 is moved, the engine 20 becomes hot due to combustion, and the coolant temperature TW rises. At this time, if the MG 11 is driven by the power output from the engine 20 to generate power and the battery 100 is charged using the generated power, the load on the engine 20 increases and the cooling water temperature TW increases. Get faster. As the coolant temperature TW rises to a temperature suitable for heating, the air input from the switching device 403 to the heat exchanger 401 is heated by heat exchange with the coolant of the engine 20. By blowing the air thus warmed into the passenger compartment 500 by the blower 402, the temperature in the passenger compartment 500 can be raised.

  An input device 440 is provided in the passenger compartment 500. The input device 440 is a device that receives an instruction from a user. Input device 440 is operated by a user and outputs a signal corresponding to the user's operation to ECU 300. The communication method between the ECU 300 and the input device 440 may be wired or wireless. The user can operate the input device 440 to request the ECU 300 to perform the heating or set the heating target temperature. The ECU 300 controls the engine 20 and the heating device 3 so that the heating target temperature and the room temperature TA2 coincide with each other based on the coolant temperature TW, the outside air temperature TA1, the room temperature TA2, and the like.

  The ECU 300 includes a CPU (Central Processing Unit) 301, a memory 302, and an input / output buffer (not shown). The memory 302 includes a ROM (Read Only Memory), a RAM (Random Access Memory), and a rewritable nonvolatile memory. Various controls are executed by the CPU 301 executing a program stored in the memory 302 (for example, ROM). ECU 300 controls each device so that vehicle 1 and battery system 2 are in a desired state based on, for example, signals received from each sensor and a map and a program stored in memory 302. ECU 300 executes travel control of vehicle 1 and charge / discharge control of battery 100 by controlling engine 20 and PCU 40, for example. The various controls performed by the ECU 300 are not limited to processing by software, and can be processed by dedicated hardware (electronic circuit).

  ECU 300 includes an odometer (not shown). The accumulated mileage of the vehicle 1 is measured by this odometer. In addition, ECU 300 includes a timer (not shown) that cumulatively counts the elapsed time from when battery 100 is mounted (at the start of use). The usage time of the battery 100 is measured by this timer. Such a timer function can also be realized by software.

  The ECU 300 outputs the acquired information (calculation results and the like by the CPU 301) to the memory 302 (for example, a rewritable nonvolatile memory) and stores it in the memory 302. In addition, the memory 302 stores in advance information used for controlling the vehicle 1 and detecting a battery state.

  Even when the vehicle 1 is stopped (in a state where the vehicle 1 is not traveling), the engine 20 may be moved for the purpose of heating the passenger compartment 500 or activating a catalyst (not shown). In this embodiment, the ECU 300 controls the heating device 3 to heat the vehicle interior 500 while the vehicle 1 is stopped (for example, when a shift lever (not shown) is in the parking range), The battery 100 is charged with the engine generated power during the heating, and the charging is stopped when the SOC of the battery 100 becomes the charge stop SOC during the charging. The engine generated power is, for example, power generated in the MG 11 when the MG 11 is driven by the engine 20.

  The charging control as described above is executed while the traveling of the vehicle 1 is stopped, and once the battery 100 is charged up to the charging stop SOC by the engine generated power, then the power of the battery 100 is mainly used for auxiliary loads (not shown). Lighting device, wiper device, audio device, car navigation system, etc.) or ECU 300, and battery 100 is charged by engine generated power for the consumed amount. That is, after the charging is stopped at the charging stop SOC, the charging and discharging of the battery 100 are repeated near the charging stop SOC until the vehicle 1 starts running. For this reason, when the charge stop SOC is maintained at the same value, charging / discharging of the battery 100 is repeatedly executed with the same SOC. For example, when the vehicle 1 is left for a long time with the shift lever (not shown) of the vehicle 1 in the parking range, charging / discharging of the battery 100 is repeated for a long time with the same SOC. When the charge and discharge of the nickel metal hydride battery is repeatedly performed with the same SOC, the memory effect is likely to occur in the nickel metal hydride battery with the SOC.

  Therefore, in the vehicle 1 according to the present embodiment, when the target SOC frequency is lower than the boundary value, the charge stop SOC is in the target SOC region, and when the target SOC frequency is higher than the boundary value, the ECU 300 Thus, the charge stop SOC is changed to an SOC outside the target SOC region. That is, when the target SOC frequency becomes higher than the boundary value, the charge stop SOC is set to a value before the target SOC frequency becomes higher than the boundary value (that is, when the target SOC frequency is lower than the boundary value). Are set to different values so that the charge stop SOC is not included in the target SOC region. Thereby, charging / discharging of the nickel metal hydride battery in the battery 100 is repeatedly performed outside the target SOC region, and the occurrence of the memory effect in the target SOC region in the nickel hydride battery is suppressed.

  In this embodiment, the target SOC region is a high SOC region (for example, first to third SOC regions to be described later) defined within a range of SOC 65% to 100%. Further, the charge stop SOC when the frequency of the target SOC region is lower than the boundary value is set to 70%, for example. When the frequency of the target SOC region of battery 100 is higher than the boundary value, ECU 300 changes the charge stop SOC to an SOC lower than the target SOC region.

  According to the above configuration, in a situation where the frequency of the high SOC region is lower than the boundary value, the SOC of the nickel metal hydride battery is high (for example, 70%) with the engine generated power generated when heating the vehicle 1 is stopped. It is possible to improve energy efficiency by charging up to. However, since charging / discharging of the battery 100 is performed in the vicinity of the charge stop SOC while the vehicle 1 is stopped traveling, if the charge stop SOC as described above is employed, the frequency of the high SOC region is high while the vehicle 1 is stopped traveling. Become. Therefore, in this embodiment, when the frequency of the high SOC region becomes high, ECU 300 lowers the charge stop SOC so that charging is not performed until the high SOC. By doing so, it is possible to avoid the nickel metal hydride battery from being repeatedly charged and discharged in the high SOC region. And generation | occurrence | production of the memory effect in a high SOC area | region (as a result, the raise of a charging voltage) can be suppressed.

  In this embodiment, ECU 300 is configured to estimate the SOC from the OCV of battery 100 using the SOC estimation information indicating the relationship between the SOC of battery 100 and the OCV. The SOC estimation information is stored in the memory 302, and may be a map, a table, a mathematical expression, or a model. A specific example of the SOC estimation information will be described later (see FIG. 3).

  Since the relationship between the SOC and the OCV in the battery 100 changes due to the memory effect occurring in the nickel metal hydride battery in the battery 100, the SOC estimation information is sequentially corrected. More specifically, when the memory effect is generated with SOCm, the SOC-OCV curve of the nickel-metal hydride battery has an SOCV lower than the SOCm in the SOC region lower than the initial OCV by the amount of memory and higher than the SOCm. The OCV in the SOC area becomes higher than the initial OCV by the amount of memory. The memory amount corresponds to the amount of voltage change due to the memory effect.

  The SOC estimation information is corrected on the precondition that the memory effect occurs in the nickel metal hydride battery in the battery 100 according to the correction reference SOC. In this embodiment, the correction reference SOC is set to 50% or more and less than 65% in consideration of the fact that the battery is generally charged / discharged in the vicinity of 60% SOC while the hybrid vehicle is traveling. Let it be SOC.

  The SOC estimation information is corrected by the following procedure, for example. ECU 300 estimates the amount of memory (the amount of voltage change for each SOC) based on correction reference SOC using the usage time and usage history of battery 100 (information indicating under what conditions battery 100 is used). . The amount of memory tends to increase as the usage time of the battery 100 increases. Also, the amount of memory varies depending on the usage conditions (battery voltage, battery temperature, etc.) of the battery 100. ECU 300 corrects (updates) the SOC estimation information to the contents corresponding to the memory amount estimated as described above.

  A problem when the SOC of the battery 100 is estimated using the SOC estimation information corrected as described above will be described with reference to FIGS. 3 and 4. Hereinafter, an actual SOC-OCV curve (more specifically, an SOC-OCV curve close to a true value precisely measured in an experiment or the like) is referred to as a predetermined SOC-OCV curve (map or the like) used for SOC estimation. In order to distinguish, it may be referred to as “actual SOC-OCV curve”.

  FIG. 3 is a diagram showing an actual SOC-OCV curve when battery 100 is used with the first SOC frequency distribution. The first SOC frequency distribution is an SOC frequency distribution indicated by a line k21. By charging the battery 100 only when the vehicle 1 is traveling without charging the engine 1 while the vehicle 1 is stopped traveling, the SOC frequency distribution of the battery 100 becomes an SOC frequency distribution as indicated by a line k21. became.

  In FIG. 3, a line k11 shows an actual SOC-OCV curve of the battery 100 in the initial state (immediately after the start of use). A line k22 indicates an actual SOC-OCV curve when the battery 100 is used with the SOC frequency distribution indicated by the line k21. The line k12 indicates SOC estimation information that is corrected using the SOC 100% as the correction reference SOC when the battery 100 is used in the SOC frequency distribution indicated by the line k21 (more specifically, a map corrected as shown below) ).

  Referring to FIG. 3, in memory 302, SOC estimation information (initial SOC estimation information) corresponding to the actual SOC-OCV curve indicated by line k11 is obtained and stored in advance by experiments or the like. Therefore, immediately after the start of use of battery 100, ECU 300 estimates the SOC from the OCV of battery 100 using the SOC estimation information. Thereafter, ECU 300 estimates the memory amount based on SOC 60% (correction standard SOC) using the usage time and usage history of battery 100, and corrects the initial SOC estimation information (line k11) based on SOC 60%. . More specifically, the OCV of the SOC region lower than 60% is lower by the memory amount (estimated value) than the initial state (line k11), and the OCV of the SOC region higher than 60% is the initial state (line k11). By performing the correction so as to be higher than the memory amount (estimated value), the SOC estimation information as indicated by the line k12 is obtained. The OCV of the correction reference SOC (SOC 60%) has the same value (both are voltages V1) in the SOC estimation information before correction (line k11) and the SOC estimation information after correction (line k12).

  When the battery 100 is used with the SOC frequency distribution indicated by the line k21, the actual SOC-OCV curve (line k22) substantially matches the corrected SOC estimation information (line k12). In the SOC frequency distribution indicated by the line k21, the frequency is highest at 60%, and the frequency decreases as the distance from 60% increases. When the battery 100 is used with such an SOC frequency distribution, charging and discharging of the battery 100 is repeated at 60% SOC while the vehicle 1 is traveling, and a memory effect is likely to occur in the nickel metal hydride battery in the battery 100 at 60% SOC. . Since the SOC estimation information indicated by the line k12 is corrected on the precondition that the memory effect is generated in the nickel-metal hydride battery in the battery 100 at an SOC of 60% (correction reference SOC), the actual SOC-OCV curve (line k22) And the post-correction SOC estimation information (line k12) substantially coincide with each other.

  FIG. 4 is a diagram showing an actual SOC-OCV curve when battery 100 is used with the second SOC frequency distribution. The second SOC frequency distribution is an SOC frequency distribution indicated by a line k31. In addition to charging while the vehicle 1 is traveling, charging is performed with engine generated power so that the SOC of the battery 100 is 70% (fixed value) while the vehicle 1 is not traveling. The SOC frequency distribution as shown by the line k31 was obtained.

  In FIG. 4, lines k11, k12, and k21 are the same as lines k11, k12, and k21 in FIG. 3, respectively. A line k32 shows an actual SOC-OCV curve when the battery 100 is used with the SOC frequency distribution shown by the line k31.

  Referring to FIG. 4, when battery 100 is used with the SOC frequency distribution indicated by line k31, the actual SOC-OCV curve (line k32) and the corrected SOC estimation information (line k12) deviate. In the SOC frequency distribution indicated by the line k31, the frequency is highest at an SOC higher than 60%. When the battery 100 is used with the SOC frequency distribution indicated by the line k31, a memory effect is likely to occur in the nickel metal hydride battery in the battery 100 at an SOC of 80%. The SOC estimation information indicated by the line k12 is corrected on the precondition that the memory effect is generated in the nickel-metal hydride battery in the battery 100 at SOC 60% (correction reference SOC), so that the actual SOC-OCV curve (line k32) And the corrected SOC estimation information (line k12) deviate. For example, the OCV of SOC 80% is the voltage V3 in the corrected SOC estimation information (line k12), and the voltage V2 is lower than the voltage V3 in the actual SOC-OCV curve (line k32).

  As described above, when a memory effect occurs in the nickel-metal hydride battery with SOCm other than the preconditions, the actual SOC-OCV curve and the SOC estimation information (based on the usage time and usage history of the battery 100) due to the occurrence of the memory effect. Deviation occurs between the map and the map that is successively corrected, and the SOC estimation accuracy is reduced.

  Therefore, in this embodiment, ECU 300 controls the SOCm of the nickel metal hydride battery to suppress the occurrence of the memory effect in the SOC that is not the precondition. More specifically, ECU 300 sets charge stop SOC to target SOCm region (for example, when the frequency at which SOC of battery 100 falls within the target SOC region (for example, SOC 65% to 80%) is higher than the boundary value. The SOCm of the nickel metal hydride battery is controlled within the target SOCm region by changing the SOC to SOC within 60% to 65%.

Hereinafter, the charging control performed by the ECU 300 will be described in detail with reference to FIGS.
FIG. 5 is a flowchart showing a processing procedure for creating the SOC frequency distribution executed by ECU 300. The processing shown in this flowchart is repeatedly executed by being called from the main routine every predetermined time, for example.

  Referring to FIG. 5, ECU 300 obtains the current SOC of battery 100 (step S11). Then, ECU 300 stores the acquired SOC in memory 302. An example of the SOC acquisition method is shown below. However, the SOC acquisition method is not limited to the method shown below, and is arbitrary.

  The ECU 300 detects the detection value of the voltage sensor 210 (voltage VB indicating the current voltage between the terminals of the battery 100), the detection value of the current sensor 220 (current IB indicating the current current of the battery 100), and the detection of the temperature sensor 230. The value (temperature TB indicating the current temperature of the battery 100) is acquired, and the OCV of the battery 100 can be calculated according to the following equation (1).

OCV = VB−IB × R (1)
In Expression (1), R represents the internal resistance of the battery 100. The ECU 300 can obtain the internal resistance of the battery 100 from the temperature TB by referring to, for example, a map stored in the memory 302 in advance (information indicating the relationship between the internal resistance of the battery 100 and the temperature TB).

  ECU 300 can acquire the OCV of battery 100 by the method as described above. Then, ECU 300 can estimate the SOC from the OCV of battery 100 with reference to the SOC estimation information in memory 302. Although details are omitted, the SOC estimation information in the memory 302 is corrected using SOC 60% as the correction reference SOC. The estimation of the memory amount based on the usage time and usage history of the battery 100 and the correction of the SOC estimation information based on the estimated memory amount are called from the main routine and repeatedly executed every predetermined time.

  Next, ECU 300 updates the SOC frequency distribution in memory 302 with the SOC acquired in step S11 (step S12). More specifically, a plurality of sections (that is, SOC regions) are provided on the horizontal axis of the SOC frequency distribution in accordance with the SOC size. In step S12, the frequency of the section (SOC area) corresponding to the SOC size acquired in step S11 is incremented by 1 (counted up). Thereafter, the process is returned to the main routine.

  By repeating the processes of steps S11 to S12, a frequency distribution indicating the occurrence frequency of each section of the SOC of the battery 100 is created. A specific example of the SOC frequency distribution created by the process of FIG. 5 will be described later (see FIG. 9).

  FIG. 6 is a flowchart showing a charging control processing procedure executed by ECU 300. In the process shown in this flowchart, the engine 20 is driven to raise the water temperature of the cooling water temperature TW when the heating device 3 performs heating while the vehicle 1 is stopped traveling, and the SOC of the battery 100 is It is executed when it is lower than a predetermined value (hereinafter referred to as “charging start SOC”). The charge start SOC is a value lower than the charge stop SOC.

  Referring to FIG. 6, ECU 300 performs charging of battery 100 with engine generated power (step S21). More specifically, the MG 11 is driven by driving the MG 11 with the power output from the engine 20 that is being driven, and the battery 100 is charged with the generated power.

  ECU 300 determines whether or not the SOC of battery 100 has reached the charge stop SOC (step S22). More specifically, ECU 300 reads, for example, the current SOC of battery 100 acquired by the process of FIG. 5 (step S11) from memory 302 and compares it with the charge stop SOC. In this embodiment, the initial value of the charge stop SOC is 70%. The charge stop SOC may be changed during charging by the process of FIG. 7 described later.

  The ECU 300 continues charging the battery 100 with engine generated power until it is determined in step S22 that the SOC of the battery 100 has reached the charge stop SOC (steps S21 to S22). That is, while it is determined in step S22 that the SOC of battery 100 has not reached the charge stop SOC (NO in step S22), charging of battery 100 with engine generated power is performed.

  When it is determined in step S22 that the SOC of battery 100 has reached the charge stop SOC (YES in step S22), ECU 300 controls PCU 40 and SMR 50 to stop charging battery 100 with engine generated power. (Step S23). Thereafter, the process is returned to the main routine.

  Even after the charging of the battery 100 is stopped in step S23, the heating by the heating device 3 is continued, and the power of the battery 100 is consumed by the auxiliary load or the ECU 300 during the heating, and the SOC of the battery 100 becomes lower than the charging start SOC. In the case where it is found, the process of FIG.

  FIG. 7 is a flowchart showing a processing procedure for setting the charge stop SOC executed by the ECU 300. The processing shown in this flowchart is repeatedly executed by being called from the main routine every predetermined time, for example.

  Referring to FIG. 7, in step S31, ECU 300 determines whether or not the charging in step S21 of FIG. 6 is being executed.

  In step S32, ECU 300 determines whether or not a predetermined memory effect occurrence condition is satisfied. If the memory effect generation condition is satisfied, it means that the memory effect in the nickel metal hydride battery in the battery 100 is not saturated. In this embodiment, the memory effect generation condition is satisfied when the accumulated travel distance of the vehicle 1 is within a predetermined value and the usage time of the battery 100 is within the predetermined value. However, the present invention is not limited to this, and the memory effect generation condition can be set arbitrarily.

  In step S33, ECU 300 refers to the SOC frequency distribution in memory 302 (the SOC frequency distribution created by the process of FIG. 5) and determines whether the frequency of the target SOC region is equal to or greater than a predetermined boundary value. FIG. 8 is a diagram showing a target SOC region according to this embodiment.

  Referring to FIG. 8, an SOC region of 65% or more and less than 70% (hereinafter referred to as “first SOC region”) and an SOC region of 70% or more and less than 75% (hereinafter referred to as “second SOC region”). The SOC region of 75% or more and less than 80% (hereinafter referred to as “third SOC region”) is set as the target SOC region. Each of the first to third SOC regions corresponds to a high SOC region.

In this embodiment, a plurality of target SOC regions (first to third SOC regions) are set as described above, and different boundary values are provided for each target SOC region. The boundary values of the first SOC region, the second SOC region, and the third SOC region are boundary values X _A , X _B , and X _C , respectively.

  The number of target SOC regions is not limited to three and can be set arbitrarily. In addition, the boundary value of the target SOC region may be a fixed value, or may be variable according to the integrated travel distance of the hybrid vehicle, the usage time (elapsed time from the start of use) of the nickel metal hydride battery, or the like. . In addition, the boundary value of the target SOC region may be set based on the frequency of the SOC region having the highest frequency in the current SOC frequency distribution (hereinafter sometimes referred to as “most frequent SOC region”). For example, the boundary value may be determined as a ratio to the frequency of the most frequent SOC region, such as 60% of the frequency of the most frequent SOC region.

  The first to third SOC areas are set corresponding to the SOC frequency distribution created by the process of FIG. FIG. 9 is a diagram showing an example of the SOC frequency distribution created by the process of FIG.

  Referring to FIG. 9, the processing of steps S <b> 11 to S <b> 12 in FIG. 5 is repeatedly executed, for example, SOC frequency distribution D <b> 1 (hereinafter, also simply referred to as “D1”) is created and stored in memory 302. The SOC frequency distribution in the memory 302 is sequentially updated by the process of FIG. The size of the section of the SOC frequency distribution D1 (the width of each SOC region) is 5%, which corresponds to the width of the first to third SOC regions. The width of each SOC region is not limited to 5% and can be set arbitrarily.

In step S33, ECU 300 determines whether the frequency of any of the first to third SOC regions is equal to or higher than the boundary value. For example, if the current SOC frequency distribution in the memory 302 is D1, the frequency of the 2SOC region in D1 because higher by the difference Δd than the boundary value _{X B} of the 2SOC region of interest SOC region in step S33 It is determined that the frequency is greater than or equal to the boundary value.

  Referring to FIG. 7 again, the memory effect generation condition is satisfied during the charge execution in step S21 of FIG. 6, and the frequency of the target SOC region (the frequency of any of the first to third SOC regions) is equal to or greater than the boundary value. Is determined (YES in all of steps S31 to S33), the ECU 300 changes the charge stop SOC in step S34, and then the process returns to the main routine. On the other hand, if the answer is NO in any of steps S31 to S33, the charge stop SOC is not changed, and the process returns to the main routine.

  In step S34, the charge stop SOC is changed by the ECU 300. For example, when the charge stop SOC is 70% (initial value) and the current SOC frequency distribution in the memory 302 is D1 shown in FIG. 9, the charge stop SOC is changed from 70% to 60%. As a result, the frequency of the second SOC region decreases, and the frequency of the SOC region of 60% or more and less than 65% (hereinafter referred to as “center SOC region”) increases. In this embodiment, the central SOC region corresponds to the target SOCm region.

  FIG. 10 is a diagram illustrating an example of a change in the SOC frequency distribution by changing the charge stop SOC. Referring to FIG. 10, the charge stop SOC is changed from 70% to 60%, and the SOC frequency distribution in the memory 302 is reset (the frequencies of all SOC regions are set to 0). Thereafter, the steps of FIG. 5 are performed. By repeatedly executing the processes of S11 to S12, for example, the SOC frequency distribution D2 is created. In the SOC frequency distribution D1 shown in FIG. 9, when the frequency of the second SOC region decreases by the difference Δd and the frequency of the central SOC region increases by the difference Δd, the SOC frequency distribution D2 is obtained.

  The charge stop SOC is changed from 70% to 60% during the execution of the charge in step S21 of FIG. 6, so that the nickel hydride battery in the battery 100 has a target SOC region (an SOC region of 65% or more and less than 80%). The memory effect is less likely to occur, and the memory effect near SOC 60% is likely to occur. That is, by changing the charge stop SOC as described above, the SOCm can be controlled to around 60%. Thereby, the deviation between the actual SOC-OCV curve of battery 100 and the current SOC estimation information (map that is sequentially corrected) in memory 302 is suppressed, and the SOC of battery 100 can be calculated with high accuracy using the SOC estimation information. It becomes possible to estimate.

  As described above, according to the hybrid vehicle control apparatus (ECU 300) according to the present embodiment, for example, when battery 100 is charged while vehicle 1 is stopped, the target SOC in the nickel metal hydride battery in battery 100 is the target SOC. Generation of a memory effect in a region (for example, a high SOC region) can be suppressed. Further, the ECU 300 performs the processing of FIG. 7, so that the SOCm of the nickel metal hydride battery in the battery 100 is controlled to the target SOCm region, and the memory effect is generated in the SOC outside the preconditions in the nickel metal hydride battery. It will be suppressed.

  In the above embodiment, the high SOC region (first to third SOC regions) is adopted as the target SOC region. Then, ECU 300 makes the charge stop SOC when the frequency of the target SOC region is higher than the boundary value lower than the charge stop SOC (70%) when the frequency of the target SOC region is lower than the boundary value (more specific). (In other words, it is changed to 60%). However, the present invention is not limited to this, and the target SOC region may be an SOC region that is not a high SOC region.

  In addition, in a nickel metal hydride battery in which gas is easily generated in the battery case due to the memory effect generated by a specific SOCm, the specific SOC area may be adopted as the target SOC area. By doing so, an increase in the battery internal pressure is suppressed, and the battery usage range is expanded. Moreover, the life extension of the battery is achieved by suppressing the increase in the battery internal pressure.

  In the above embodiment, the frequency for each SOC region is always detected by the process of FIG. However, the present invention is not limited to this, and the period for detecting the frequency for each SOC region (hereinafter sometimes referred to as “SOC frequency detection period”) can be arbitrarily set. For example, the SOC frequency detection period may be limited to a travel stop period of the vehicle 1 (a period from when travel is stopped to when travel is started again).

  The SOC frequency distribution in the memory 302 may be reset (initialized) at a predetermined timing. As an example of timing for resetting the SOC frequency distribution, timing at which the SOC frequency detection period ends, refresh charge / discharge of the nickel metal hydride battery (refresh charge or refresh discharge for eliminating the memory effect generated in the nickel metal hydride battery) is executed Timing. At the timing when refresh charge / discharge is performed on the nickel metal hydride battery, the SOC frequency distribution may be reset and the charge stop SOC may be returned to the initial value.

  It is not essential to reset the SOC frequency distribution. For example, the frequency of each SOC area in the SOC frequency distribution is continuously counted without resetting the SOC frequency distribution in the memory 302, and the frequency of the SOC frequency distribution increases (or the frequency of the most frequent SOC area increases). The boundary value of the target SOC region may be increased. Further, the boundary value of the target SOC region may be determined as a ratio to the frequency of the most frequent SOC region. Moreover, you may employ | adopt a relative frequency (ratio with respect to the whole frequency) as frequency.

  In the above embodiment, engine power generation is performed when heating is performed while the vehicle 1 is stopped traveling, but engine power generation may be performed while the vehicle 1 is traveling (including during low-load traveling). For example, while heating the vehicle interior 500 by controlling the heating device 3 while the vehicle 1 is traveling, the battery 100 is charged with engine generated power during the heating, and the SOC of the battery 100 is charged during the charging. The charging may be stopped when becomes a charge stop SOC.

  The configuration of the hybrid vehicle is not limited to the configuration shown in FIG. 1 and can be changed as appropriate. In addition, the target for detecting OCV or SOC can be arbitrarily changed as long as the nickel hydrogen battery is included. For example, predetermined cells (one or a plurality of cells 101) included in the battery pack of the battery 100 may be targeted. The voltage sensor 210 may be provided so that the voltage for each cell 101 or the voltage for each of the plurality of cells 101 connected in series is detected. Further, the temperature sensor 230 may be provided so that the temperature of each cell 101 or the temperature of each of the plurality of adjacent cells 101 is detected. Further, the SOC estimation method is arbitrary, and a method using current value integration (Coulomb count) or the like can also be adopted. Further, the nickel metal hydride battery that is subject to charge control is not limited to an assembled battery, and may be a single battery.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

  DESCRIPTION OF SYMBOLS 1 Vehicle, 2 Battery system, 3 Heating apparatus, 11,12 MG, 20 Engine, 30 Drive wheel, 31 Power split device, 32 Drive shaft, 40 PCU, 50 SMR, 100 Battery, 101 cell, 102 Case, 103 Gas discharge Valve, 104 electrode body, 210 voltage sensor, 220 current sensor, 230 temperature sensor, 300 ECU, 301 CPU, 302 memory, 401 heat exchanger, 402 air blower, 403 switching device, 410 water temperature sensor, 420 outside air temperature sensor, 430 Vehicle compartment sensor, 440 input device, 500 vehicle compartment.

Claims (1)

An internal combustion engine;
A nickel metal hydride battery,
A control device that generates power using the power output from the internal combustion engine to charge the nickel metal hydride battery, and stops the charging when the SOC of the nickel metal hydride battery becomes a charge stop SOC during the charging. When,
With
When the frequency at which the SOC of the nickel metal hydride battery is within the predetermined SOC region is lower than a predetermined value, the charge stop SOC is within the predetermined SOC region,
When the frequency is higher than the predetermined value, the control device changes the charging stop SOC to an SOC outside the predetermined SOC range.

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