JP6187302B2 - Vehicle control device - Google Patents

Description

  The present invention relates to a vehicle control device, and more particularly to a vehicle control device including an internal combustion engine, a rotating electrical machine, and a power storage device capable of charging and discharging driving power of the rotating electrical machine.

  In a secondary battery system mounted on a vehicle such as a hybrid vehicle or an electric vehicle, the state of charge of the battery (hereinafter also referred to as SOC (State Of Charge)) needs to be managed with high accuracy. Therefore, a technique for improving the estimation accuracy of the SOC is required.

  For example, in a power storage system disclosed in Japanese Patent Application Laid-Open No. 2013-158087 (Patent Document 1), a controller calculates an integrated value of a charging current and a discharging current of a battery. In the memory of this controller, first relation data (specifically, an SOC-OCV (Open Circuit Voltage) curve) associated with a state where the integrated value of the discharge current is larger than the integrated value of the charging current, and the charging Second relational data associated with a state where the integrated value of current is larger than the integrated value of discharge current is stored. The controller selects one of the first and second relationship data, and calculates the SOC based on the selected relationship data.

JP2013-158087A

  In the power storage system disclosed in Patent Document 1, since two types of relational data are prepared, the amount of data for estimating the SOC increases. As the amount of data increases, a large-capacity memory and a high-speed CPU (Central Processing Unit) are required, which causes an increase in cost.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a vehicle control device capable of reducing the amount of data for estimating the SOC.

  A control device according to an aspect of the present invention is a vehicle control device including a rotating electrical machine and a power storage device capable of charging and discharging the driving power of the rotating electrical machine. The control device estimates an open voltage of the power storage device, and further estimates a state value from the open voltage based on a change characteristic of the open voltage with respect to a charged state of the power storage device. The change characteristic includes a first curve indicating a characteristic during discharging of the power storage device and a second curve indicating a characteristic during charging of the power storage device. When the charging state belongs to the first region, the control device updates the charging state according to the first curve, while when the charging state belongs to the second region lower than the first region, The state of charge is updated according to a curve that satisfies the following formula (1). In Expression (1), OCV represents an open circuit voltage, DCHG represents an open circuit voltage on the first curve, and CHG represents an open circuit voltage on the second curve.

DCHG <OCV <CHG (1)
According to the above configuration, when the state of charge belongs to the first region, the power storage device is mainly discharged. Therefore, the state of charge is updated according to the first curve indicating the characteristics of the power storage device during discharge. On the other hand, when the state of charge belongs to the second region lower than the first region, charging and discharging of the power storage device are frequently switched, so that the curve satisfying the above formula (1) (that is, the first curve and The charging state is updated according to a curve existing between the second curve and the second curve. In this way, by switching the curve used for estimating the charging state according to the region to which the charging state belongs, only one type of curve needs to be prepared for each region, so the amount of data for estimating the charging state is reduced. can do.

  Preferably, the vehicle is a hybrid vehicle further provided with an internal combustion engine. When the state of charge belongs to the second region, the control device updates the state of charge according to a curve that satisfies the following expressions (2) and (3).

OCV ≧ (CHG + DCHG) / 2− (CHG−DCHG) / 6 (2)
OCV ≦ (CHG + DCHG) / 2 + (CHG−DCHG) / 6 (3)
According to the above configuration, when the state of charge belongs to the second region, charging and discharging of the power storage device are frequently switched. Therefore, a curve satisfying the above equations (2) and (3) (that is, the first The state of charge is updated according to the curve in the vicinity of the average value of the curve and the second curve. Thereby, the estimation accuracy of the state of charge can be improved.

  According to the present invention, the amount of data for estimating the SOC can be reduced.

It is a block diagram which shows roughly the structure of the vehicle which concerns on this Embodiment. It is a figure which shows an example of the SOC-OCV curve in a comparative example. It is a figure which shows an example of the SOC-OCV curve in this Embodiment. FIG. 4 is an enlarged view of an SOC-OCV curve in the HV travel priority area shown in FIG. 3. It is a figure for demonstrating the setting method of the upper limit curve UL and the lower limit curve LL shown in FIG. It is a figure which shows the result of having estimated SOC according to each curve. It is a figure for demonstrating the error of the SOC-OCV curve of a comparative example. It is a figure for demonstrating the error of the SOC-OCV curve of this Embodiment.

  Hereinafter, embodiments of the present invention 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.

  In the present embodiment, a plug-in hybrid vehicle configured to be able to charge a battery mounted on the vehicle from the outside of the vehicle will be described as an example. However, the hybrid vehicle is not limited to a plug-in hybrid vehicle, and may be a normal hybrid vehicle that is not charged from the outside of the vehicle. The “vehicle” may be an electric vehicle.

  FIG. 1 is a block diagram schematically showing the configuration of the vehicle 1 according to the present embodiment. Referring to FIG. 1, vehicle 1 includes an engine 100, a first MG (Motor Generator) 110, a second MG 120, a power split mechanism 130, drive wheels 140, a battery 150, and a PCU (Power Control Unit) 160. And an SMR (System Main Relay) 170 and an ECU (Electronic Control Unit) 300.

  The ECU 300 is a control device that controls the vehicle 1. ECU 300 receives signals from sensors described later and outputs control signals to the components of vehicle 1. The engine 100 is an internal combustion engine such as a gasoline engine or a diesel engine.

  The battery 150 is a power storage device configured to be chargeable / dischargeable. As the battery 150, for example, a secondary battery such as a lithium ion battery or a nickel metal hydride battery, or a capacitor such as an electric double layer capacitor can be employed. A battery sensor 152 is attached to the battery 150.

  The battery sensor 152 comprehensively represents a voltage sensor, a current sensor, and a temperature sensor. The voltage sensor detects a battery voltage VB (more specifically, a CCV (Closed Circuit Voltage)). The current sensor detects a current IB that enters and exits the battery 150. The temperature sensor detects the temperature TB of the battery 150. Each sensor transmits the detected value to ECU 300.

  ECU 300 estimates the SOC of battery 150 based on the detection value of battery sensor 152. Specifically, the SOC can be estimated from the OCV by obtaining in advance the change characteristic of the OCV (open circuit voltage) with respect to the SOC of the battery 150. The OCV is calculated from the voltage VB (CCV) of the battery 150 detected by the voltage sensor. In other words, ECU 300 estimates the OCV of battery 150, and further estimates the SOC from the OCV based on the SOC-OCV curve.

  PCU 160 drives first MG 110 and second MG 120. PCU 160 includes a converter 161 and inverters 162 and 163. Converter 161 boosts the DC voltage supplied from battery 150 based on a control signal from ECU 300. The boosted DC voltage is supplied to inverters 162 and 163. Each of inverters 162 and 163 converts DC power from converter 161 into AC power based on a control signal from ECU 300. The AC power converted by inverters 162 and 163 is supplied to first MG 110 and second MG 120, respectively.

  First MG 110 rotates the crankshaft (not shown) of engine 100 using the AC power converted by inverter 162. Thereby, first MG 110 starts engine 100. Further, the driving force generated by first MG 110 is transmitted to driving wheel 140 through power split mechanism 130. Further, first MG 110 generates power using the power of engine 100 divided by power split mechanism 130. The AC power generated by first MG 110 can be converted to DC power by PCU 160. Thereby, the battery 150 is charged.

  Second MG 120 applies driving force to drive wheels 140 using at least one of the AC power from inverter 163 and the AC power generated by first MG 110. Second MG 120 generates power by regenerative braking. The AC power generated by second MG 120 can be converted to DC power by PCU 160. Thereby, the battery 150 is charged.

  SMR 170 is electrically connected between battery 150 and PCU 160. SMR 170 switches between power supply and interruption between battery 150 and PCU 160 based on a control signal from ECU 300.

  The vehicle 1 is configured to be able to supply power to an external device 500 and an electric device 510 outside the vehicle. External device 500 and electric device 510 are not particularly limited as long as they are devices that operate using electric power from vehicle 1. The vehicle 1 further includes a DC / AC converter 180, an outlet 182, a relay 184, and a connection unit 186 as a configuration for supplying power to the outside of the vehicle.

  DC / AC converter 180 converts DC power from battery 150 or PCU 160 into AC power based on a control signal from ECU 300. The AC power converted by the DC / AC converter 180 is supplied to the outlet 182 and is also supplied to the connection unit 186 via the relay 184. A power plug (not shown) of the electric device 510 is inserted into the outlet 182. Relay 184 is electrically connected between DC / AC converter 180 and connection unit 186. Relay 184 switches between supply and interruption of AC power from DC / AC converter 180 to connection unit 186 based on a control signal from ECU 300.

  The connecting portion 186 is a dedicated connector, for example, and is provided on the outer surface of the vehicle 1. AC power from the vehicle 1 is supplied to the external device 500 via the connection unit 186 and the connection cable 520.

  The vehicle 1 further includes an AC / DC converter 190 and a relay 192 as a configuration for charging the battery 150 from the outside of the vehicle. When charging the battery 150, an AC power source (for example, a commercial power source) is electrically connected to the connection unit 186 instead of the external device 500.

  AC / DC converter 190 converts AC power from connection unit 186 into DC power based on a control signal from ECU 300. Thereby, the battery 150 is charged. Relay 192 is electrically connected between AC / DC converter 190 and battery 150. Relay 192 switches between supply and interruption of DC power from AC / DC converter 190 to battery 150 based on a control signal from ECU 300.

  In the configuration as described above, the traveling performed in a state where the driving of the engine 100 is permitted is also referred to as “HV traveling”. On the other hand, vehicle 1 can run with only the driving force of second MG 120 with engine 100 stopped. The traveling performed with the engine 100 stopped is also referred to as “EV traveling”.

  It is known that when a battery is charged and discharged, polarization occurs in the battery. When the battery is charged, the polarization voltage increases in the positive direction. On the other hand, when the battery is discharged, the polarization voltage increases in the negative direction. When the charging / discharging of the battery is stopped, the polarization voltage generated at that time gradually decreases with time. Thus, the battery has OCV hysteresis characteristics based on the charge / discharge history. Therefore, in order to estimate the SOC with high accuracy, it is important to take this hysteresis characteristic into consideration.

  Therefore, the SOC-OCV curves of the comparative example and the present embodiment are determined in consideration of the OCV hysteresis characteristics of the battery. First, the SOC-OCV curve of the comparative example will be described in detail below. The configuration of the vehicle according to the comparative example is the same as the configuration of vehicle 1 according to the present embodiment, and therefore detailed description will not be repeated.

  In the comparative example, the current integrated value is used to determine whether the polarization voltage of the battery 150 is positive or negative. The current integrated value in the comparative example is from when charge / discharge control is started by turning on the ignition switch 200 (IG-ON) until when charge / discharge control is finished by turning off the ignition switch 200 (IG-OFF). This is a value obtained by integrating the current IB flowing into and out of the battery 150.

  FIG. 2 is a diagram illustrating an example of an SOC-OCV curve in the comparative example. Referring to FIG. 2, the horizontal axis represents SOC and the vertical axis represents OCV. The SOC-OCV curve of the comparative example includes a charge side curve CHG (shown by a solid line) and a discharge side curve DCHG (shown by a broken line).

  The discharge side curve DCHG corresponds to a case where the current integrated value is positive. On the other hand, the charging side curve CHG corresponds to a case where the current integrated value is negative. In other words, the discharge side curve DCHG indicates the characteristics when the battery 150 is discharged, and the charge side curve CHG indicates the characteristics when the battery 150 is charged. As indicated by the broken arrow, when the SOC is estimated from the OCV, the estimated value of the SOC differs depending on which curve is followed. The charge side curve CHG has a lower SOC for the same OCV than the discharge side curve DCHG. The discharge side curve DCHG corresponds to a “first curve”, and the charge side curve CHG corresponds to a “second curve”.

  In the comparative example, either the charge side curve CHG or the discharge side curve DCHG is selected according to the positive or negative of the current integrated value. When the selected curve matches the actual charge / discharge state of the battery, that is, when the charge side curve CHG is selected when the battery is in the charged state, or when the battery is in the discharged state When the side curve DCHG is selected, the estimation accuracy of the SOC can be improved.

  However, the sign of the current integrated value may not match the actual charge / discharge state of the battery 150 at that time. As an example, if power is consumed by an air conditioner or audio immediately before IG-OFF, the battery 150 is in a discharged state during IG-OFF. Therefore, it is desirable to select the discharge side curve DCHG. However, from IG-ON to IG-OFF, for example, when engine 100 is driven to increase the SOC during HV traveling, or when battery 150 is frequently charged by regenerative braking. The current integrated value can be positive. In this case, the charging side curve CHG is selected in the comparative example. Thus, in the comparative example, a curve different from the desired curve can be selected. In that case, the estimation accuracy of the SOC is greatly reduced.

  Further, in the ECU of the comparative example, since two types of curves are stored in the memory, the amount of data for estimating the SOC increases. Therefore, a large-capacity memory and a high-speed CPU are required.

  Next, the SOC-OCV curve in the present embodiment will be described in comparison with a comparative example.

  FIG. 3 is a diagram showing an example of the SOC-OCV curve in the present embodiment. Referring to FIG. 3, the curve of the present embodiment is indicated by a thick solid line. For comparison with the comparative example, the charging side curve CHG is indicated by a thin solid line, and the discharging side curve DCHG is indicated by a broken line. However, the curves of these comparative examples are shown only for comparison, and in the present embodiment, only the curves shown by the thick solid line are stored in the memory of ECU 300.

  The SOC-OCV curve of the present embodiment is divided into four areas according to the SOC. The four regions are a low SOC region, an HV traveling priority region, an EV traveling priority region, and a high SOC region in order of increasing SOC.

  When ECU 300 estimates the SOC from the OCV at a certain moment, ECU 300 determines which region the estimated SOC value belongs to. Thereafter, ECU 300 estimates the SOC at the next moment according to the curve of the region to which the estimated value of SOC belongs, and updates the estimated value.

  The low SOC region is a region where the battery 150 needs to be charged, for example, a region where the SOC is less than 15%. In the low SOC region, the SOC-OCV curve is determined to match the charging side curve CHG. This is because the charge-side curve CHG is estimated to have a lower SOC than the discharge-side curve DCHG with respect to the same OCV, and therefore it is desirable to estimate the SOC with a margin in the low SOC region. Thereby, battery 150 can be prevented from reaching an overdischarged state.

  The HV travel priority area is an area where HV travel is preferentially performed, for example, an area where the SOC is 15% or more and less than 30%. During HV traveling, charging and discharging of the battery 150 are frequently switched. Therefore, in the present embodiment, the SOC-OCV curve in the HV traveling priority region is determined so as to be positioned between the charging side curve CHG and the discharging side curve DCHG. This determination method will be described in detail later.

  The EV traveling priority area is an area where the EV traveling is preferentially performed, for example, an area where the SOC is 30% or more and less than 85%. During EV travel, the battery 150 may be temporarily charged by regenerative braking, but the battery 150 is basically in a discharged state. Therefore, in the present embodiment, the SOC-OCV curve in the EV travel priority area is determined to match the discharge side curve DCHG. In other words, the ECU 300 updates the SOC according to the discharge side curve DCHG when the SOC belongs to the EV travel priority area.

  The high SOC region is a region where the battery 150 needs to be discharged, for example, a region where the SOC is 85% or more. In the high SOC region, the SOC-OCV curve is determined to match the discharge side curve DCHG. This is because the SOC is estimated to be higher for the discharge side curve DCHG than the charge side curve CHG for the same OCV, so it is desirable to estimate the SOC with a margin in the high SOC region. Thereby, battery 150 can be prevented from reaching an overcharged state.

  The method for setting the SOC-OCV curve is not limited to the above method. For example, the SOC-OCV curve in the low SOC region may be determined to coincide with the discharge side curve DCHG. As described above, since the discharge side curve DCHG is estimated to have a higher SOC than the charge side curve CHG with respect to the same OCV, the SOC region that can be discharged from the battery can be widened. Similarly, the SOC-OCV curve in the high SOC region may be determined so as to coincide with the charging side curve CHG. Thereby, the SOC area | region which can be charged to a battery can be expanded.

  FIG. 4 is an enlarged view of the SOC-OCV curve in the HV traveling priority area shown in FIG. Referring to FIG. 4, when the SOC belongs to the HV travel priority region, the SOC-OCV curve is determined so as to be located within a range between charge side curve CHG and discharge side curve DCHG.

  An upper limit curve UL and a lower limit curve LL are set between the charge side curve CHG and the discharge side curve DCHG. The upper limit curve UL is a curve that defines the upper limit value of the OCV for each SOC. The lower limit curve LL is a curve that defines the lower limit value of the OCV for each SOC. In the HV traveling priority region, the SOC-OCV curve is preferably determined so as to be positioned between the upper limit curve UL and the lower limit curve LL.

  FIG. 5 is a diagram for explaining a method of setting the upper limit curve UL and the lower limit curve LL shown in FIG. Referring to FIG. 5, a curve indicating an average OCV between charge side curve CHG and discharge side curve DCHG is represented as average curve AVE (AVE = (CHG + DCHG) / 2). Further, the OCV of the difference between the charging side curve CHG and the discharging side curve DCHG is expressed as a voltage ΔV (ΔV = CHG−DCHG).

  The OCV on the upper limit curve UL is preferably determined to be a value obtained by adding ΔV / 6 to the OCV on the average curve AVE. Similarly, the OCV on the lower limit curve LL is preferably determined to be a value obtained by subtracting ΔV / 6 from the OCV on the average curve AVE. That is, it is preferable that the SOC-OCV curve is determined so as to be located within a central 1/3 range between the charge side curve CHG and the discharge side curve DCHG.

  In other words, the ECU 300 preferably updates the SOC according to a curve that satisfies the following formula (1) when the SOC belongs to the HV travel priority region. However, DCHG indicates OCV on the discharge side curve DCHG, and CHG indicates OCV on the charge side curve CHG.

    DCHG <OCV <CHG (1) It is more preferable to update the SOC in accordance with a curve that satisfies the following formulas (2) and (3). Thereby, the estimation accuracy of SOC can be improved.

OCV ≧ (CHG + DCHG) / 2− (CHG−DCHG) / 6 (2)
OCV ≦ (CHG + DCHG) / 2 + (CHG−DCHG) / 6 (3)
Furthermore, it is more preferable that the SOC-OCV curve is determined so as to coincide with the average curve AVE.

  In the comparative example, it is necessary to prepare two types of curves, a charge side curve CHG and a discharge side curve DCHG. In contrast, according to the present embodiment, only one type of curve is required for each region. Therefore, the data amount for estimating the SOC can be reduced. Further, according to the present embodiment, it is not necessary to calculate an integrated current value in order to select a curve. Therefore, it is not necessary to use a large-capacity memory or a high-speed CPU, and the cost can be reduced.

  Furthermore, according to the present embodiment, for each SOC region, a curve suitable for the state of charge or discharge that battery 150 is likely to take within that region is determined. Therefore, the estimation accuracy of the SOC can be improved as compared with the case where either one of the charge side curve CHG and the discharge side curve DCHG is used.

  The “first region” is preferably an EV travel priority region, and the “second region” is preferably an HV travel priority region. However, since the “first region” only needs to be a region where the frequency of battery discharge is sufficiently higher than the frequency of charging, it is not essential that EV travel is performed in the “first region”. Moreover, the numerical range of each area | region is only what shows an example, and can be changed suitably.

  In the case of an electric vehicle, a region having a relatively high SOC corresponds to a “first region”, and a region having a relatively low SOC corresponds to a “second region”. In a region where the SOC is high, since the vehicle is driven using the discharge power from the battery, it is desirable to use the discharge side curve DCHG. On the other hand, it is also conceivable to use the discharge side curve DCHG for a region where the SOC is low. However, for example, when the charge frequency to the battery by regenerative braking is increased in the low SOC region compared to the high region, the SOC-OCV that satisfies the above formula (1) is used rather than simply using the discharge side curve DCHG. It is desirable to use a curve.

  Further, when the temperature TB of the battery 150 is low, the internal resistance of the battery 150 increases, so that the OCV increases. Therefore, an SOC-OCV curve may be prepared in advance for each temperature TB and stored in the memory of ECU 300. ECU 300 estimates OCV based on the CCV detected by the voltage sensor, and detects temperature TB by the temperature sensor. ECU 300 then selects an SOC-OCV curve corresponding to the detected temperature TB from among the plurality of SOC-OCV curves, and further estimates the SOC from the OCV.

  An example of a measurement result indicating that the SOC estimation accuracy is improved by determining the SOC-OCV curve according to the above average curve and equations (1) and (2) will be described below.

  FIG. 6 is a diagram illustrating a result of estimating the SOC according to each curve. Referring to FIG. 6, when OCV is 3.55 V, the estimated value of SOC according to charging side curve CHG is 20.2%. Similarly, the estimated value of SOC according to the upper limit curve UL is 21.1%. The estimated SOC value according to the lower limit curve LL is 21.8%. The estimated SOC according to the discharge side curve DCHG is 22.7%.

  FIG. 7 is a diagram for explaining an error in the SOC-OCV curve of the comparative example. FIG. 8 is a diagram for explaining an error of the SOC-OCV curve of the present embodiment.

  Referring to FIG. 7, in the comparative example, the estimated value of SOC according to charging side curve CHG is 20.2%. In this case, for example, if charging by regenerative braking is frequently performed and battery 150 is in a charged state, the selected curve matches the state of battery 150, so the SOC error is zero. However, in practice, when EV traveling is mainly performed and battery 150 is in a discharged state, the SOC error is 2.5%. Thus, in the comparative example, the SOC error range (maximum error value−minimum value) is 2.5% depending on whether or not the selected curve matches the actual state of the battery 150 at that time. And get bigger. Since the same applies to the case where the SOC is estimated according to discharge-side curve DCHG, detailed description will not be repeated.

  On the other hand, referring to FIG. 8, in the present embodiment, when the SOC-OCV curve is determined so as to coincide with average curve AVE, the estimated value of SOC is 21.5%. Therefore, if the battery 150 is in a charged state, the SOC error is 1.3% (21.5% -20.2% = 1.3%). On the other hand, if the battery 150 is in a discharged state, the SOC error is 1.2% (22.7% -21.5% = 1.2%). Thus, when the SOC-OCV curve is determined so as to coincide with the average curve AVE, the maximum value of the error is 1.3%, which is smaller than that of the comparative example. The range of error is as small as 0.1% (1.3% -1.2% = 0.1%).

  When the SOC-OCV curve is determined so as to coincide with the upper limit curve UL, the estimated value of SOC is 21.1%. Therefore, if the battery 150 is in a charged state, the SOC error is 0.9% (21.1% -20.2% = 0.9%). On the other hand, if the battery 150 is in a discharged state, the SOC error is 1.6% (22.7% -21.1% = 1.6%). That is, the maximum value of the error is 1.6%, and the error range is 0.7% (1.6% −0.9% = 0.7%).

  Similarly, when the SOC-OCV curve is determined so as to coincide with the lower limit curve LL, the estimated value of SOC is 21.8%. Therefore, if the battery 150 is in a charged state, the SOC error is 1.3% (21.8% -20.2% = 1.6%). On the other hand, if the battery 150 is in the discharged state, the SOC error is 0.9% (22.7% -21.8% = 0.9%). That is, the maximum value of error is 1.6%, and the range of miscalculation is 0.7% (1.6% −0.9% = 0.7%).

  Thus, according to the present embodiment, it can be seen that the maximum value of the SOC error can be reduced as compared with the comparative example. Specifically, in the examples shown in FIGS. 6 to 8, the maximum error value (1.6%) can be reduced to about 60% of the maximum error value (2.5%) in the comparative example (1.6%). /2.5%=64%).

  Further, the degree of deterioration of the battery can be estimated by estimating the SOC. A battery deterioration estimation method using SOC will be briefly described. By dividing the amount of charge that enters and exits the battery during charging / discharging by the SOC change amount ΔSOC, the capacity of the battery at that time is determined (capacity = charge amount / ΔSOC). Further, the capacity maintenance rate is obtained by dividing the capacity at that time by the capacity in the initial state (capacity maintenance ratio = capacity / capacity in the initial state). A value obtained by subtracting the capacity maintenance rate from 100% indicates the battery deterioration rate at that time (capacity maintenance rate + deterioration rate = 100%).

  As an example, a case will be described in which the battery 150 is charged until the SOC reaches 85.0% from the estimated value shown in FIGS. 7 and 8 in each of the comparative example and the present embodiment.

  Referring again to FIG. 7, in the comparative example, when the SOC is estimated according to the charging side curve CHG, the SOC increases by 64.8% (ΔSOC = 85.0% −20.2% = 64.8). %). The error of the estimated value of the SOC with respect to the SOC increase ΔSOC corresponds to a maximum of 3.9% (2.5% / 64.8% = 3.9%). Since the same applies to the case where the SOC is estimated according to discharge-side curve DCHG, detailed description will not be repeated.

  On the other hand, referring to FIG. 8, according to the present embodiment, when the SOC-OCV curve is determined so as to coincide with average curve AVE, the SOC increases by 63.5% (ΔSOC = 85.0% -21.5% = 63.5%). The maximum SOC error (1.3%) corresponds to 2.0% of the SOC increase ΔSOC (1.3% / 63.5% = 2.0%).

  When the SOC-OCV curve is determined so as to coincide with the upper limit curve UL, the SOC increases by 63.9% (ΔSOC = 85.0% -21.1% = 63.9%). The maximum SOC error value (1.6%) corresponds to 2.5% of the SOC increase ΔSOC (1.6% / 63.9% = 2.5%).

  Similarly, when the SOC-OCV curve is determined so as to coincide with the lower limit curve LL, the SOC increases by 63.2% (ΔSOC = 85.0% -21.8% = 63.2%). The maximum SOC error value (1.6%) corresponds to 2.5% of the SOC increase ΔSOC (1.6% / 63.2% = 2.5%).

  As described above, according to the present embodiment, the ratio of the error to the SOC change amount ΔSOC due to charging / discharging can be reduced as compared with the comparative example. Therefore, the estimation accuracy of the deterioration rate of the battery 150 can be improved. Moreover, it becomes possible to manage charging / discharging of the battery with high accuracy.

  Finally, this embodiment will be summarized with reference to FIGS. 1 and 3 again. ECU 300 is a control device for vehicle 1 including second MG 120 and battery 150 capable of charging and discharging the drive power of second MG 120. ECU 300 estimates the OCV of battery 150, and further estimates the SOC from the OCV based on the SOC-OCV curve of battery 150. The SOC-OCV curve includes a discharge-side curve DCHG indicating the characteristics when the battery 150 is discharged, and a charge-side curve CHG used indicating the characteristics when the battery 150 is charged. When the SOC belongs to the EV travel priority area, the ECU 300 updates the SOC according to the discharge-side curve DCHG. On the other hand, when the SOC belongs to the HV travel priority area lower than the EV travel priority area, the ECU 300 The SOC is updated according to a curve satisfying the above. In the formula (1), DCHG indicates OCV on the discharge side curve DCHG, and CHG indicates OCV on the charge side curve CHG.

DCHG <OCV <CHG (1)
Preferably, vehicle 1 is a hybrid vehicle that further includes engine 100. When the SOC belongs to the HV travel priority region, ECU 300 updates the state of charge according to a curve that satisfies the following formulas (2) and (3).

OCV ≧ (CHG + DCHG) / 2− (CHG−DCHG) / 6 (2)
OCV ≦ (CHG + DCHG) / 2 + (CHG−DCHG) / 6 (3)
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.

  1 vehicle, 100 engine, 110 1st MG, 120 2nd MG, 130 power split mechanism, 140 drive wheel, 150 battery, 152 battery sensor, 161 converter, 162, 163 inverter, 180 DC / AC converter, 190 AC / DC conversion , 182 outlet, 184, 192 relay, 186 connection, 200 ignition switch, 300 ECU, 500 external device, 510 electrical device, 520 connection cable.

Claims (2)

A vehicle control device comprising a rotating electrical machine and a power storage device capable of charging and discharging the driving power of the rotating electrical machine,
The control device estimates an open voltage of the power storage device, and further estimates the charge state from the open voltage based on a change characteristic of the open voltage with respect to a charge state of the power storage device,
The change characteristic includes a first curve indicating a characteristic during discharging of the power storage device and a second curve indicating a characteristic during charging of the power storage device,
The controller is
If the state of charge belongs to the first region, update the state of charge according to the first curve,
When the state of charge belongs to a second region lower than the first region, the state of charge is updated according to one type of curve that satisfies the following formula (1) regardless of the state of charge / discharge of the power storage device. And
In the formula (1), OCV is the open circuit voltage, DCHG is the open circuit voltage on the first curve, and CHG is the open circuit voltage on the second curve.
DCHG <OCV <CHG (1) The vehicle is a hybrid vehicle further provided with an internal combustion engine,
2. The vehicle control according to claim 1, wherein when the state of charge belongs to the second region, the control device updates the state of charge according to a curve satisfying the following formulas (2) and (3). apparatus.
OCV ≧ (CHG + DCHG) / 2− (CHG−DCHG) / 6 (2)
OCV ≦ (CHG + DCHG) / 2 + (CHG−DCHG) / 6 (3)

Images