Hybrid vehicles

Abstract

To suppress degradation of emission.SOLUTION: A hybrid vehicle comprises: an engine for travel in which an electric heating catalyst is attached to an exhaust system; a motor for travel; a battery which has a plurality of battery cells that are serially connected and can supply / receive the power to / from the motor; a power supply part which can supply the power from the battery to the electric heating catalyst; and a control device which controls the engine and motor so as to travel with the travel request power by switching between the CD mode and the CS mode. The control device operates the power supply part when the mode is in the CD mode, the electric heating catalyst is inactive and polarization of at least one of the plurality of battery cells is predicted.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to hybrid vehicles. [Background technology]

[0002] Conventionally, this type of hybrid vehicle has been proposed to include a driving engine with an electrically heated catalyst attached to the exhaust system, a driving motor, a battery capable of exchanging power with the motor, and a power adjustment unit that adjusts the power supplied from the battery to the electrically heated catalyst, and to run by switching between a CD (Charge Depleting) mode and a CS (Charge Sustaining) mode (see, for example, Patent Document 1). In this hybrid vehicle, when catalyst warm-up is incomplete and the vehicle is in CD mode, the power adjustment unit is controlled to not supply power to the electrically heated catalyst until the battery's SOC drops to a predetermined SOC, and when the SOC drops to the predetermined SOC, the power adjustment unit is controlled to supply power to the electrically heated catalyst. When catalyst warm-up is incomplete and the vehicle is in CS mode, the power adjustment unit is controlled to supply power to the electrically heated catalyst. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-85108 Summary of the Invention [Problem to be solved by the invention]

[0004] In the hybrid vehicle described above, if the SOC is greater than the predetermined SOC in CD mode and the engine is stopped and high battery output continues, a sudden voltage drop due to polarization may occur in at least one battery cell in the battery, resulting in a drop in battery output. If the engine attempts to compensate for the drop in driving power due to the drop in battery output with power from the engine, this could result in a deterioration in emissions due to the electrically heated catalyst being inactive.

[0005] The hybrid vehicle of the present disclosure has a primary objective of suppressing deterioration of emissions. [Means for solving the problem]

[0006] The hybrid vehicle of the present disclosure employs the following measures to achieve the above-mentioned main object.

[0007] [1] The hybrid vehicle disclosed herein is an engine for driving in which an electrically heated catalyst is attached to an exhaust system; A driving motor; a battery having a plurality of battery cells connected in series and capable of exchanging power with the motor; a power supply unit capable of supplying power from the battery to the electrically heated catalyst; a control device that controls the engine and the motor by switching between a CD (Charge Depleting) mode and a CS (Charge Sustaining) mode so that the vehicle travels at a required power level; A hybrid vehicle comprising: the control device activates the power supply unit when the vehicle is in the CD mode, the electrically heated catalyst is inactive, and polarization of at least one of the plurality of battery cells is predicted. The gist of this is as follows.

[0008] In the hybrid vehicle disclosed herein, when the electrically heated catalyst is inactive in CD mode and polarization of at least one battery cell is predicted, the power supply unit is activated. This prevents the electrically heated catalyst from being inactive when a drop in battery output occurs in CD mode due to a sudden drop in voltage caused by polarization of at least one battery cell. As a result, when a drop in battery output occurs in CD mode due to a sudden drop in voltage caused by polarization of at least one battery cell, and driving power is attempted to be supplemented by engine power, a situation in which emissions deteriorate due to an inactive electrically heated catalyst can be prevented.

[0009] [2] In the hybrid vehicle of the present disclosure (the hybrid vehicle described in [1] above), the control device may determine that polarization of at least one of the plurality of battery cells is predicted when the CD mode is selected and the electrically heated catalyst is inactive, and the required running power is greater than the sum of polarization prediction indices related to the prediction of polarization of each of the plurality of battery cells, or when the voltage of at least one of the battery cells is less than a threshold voltage that is higher than the inflection point voltage when the voltage drops.

[0010] [3] In this case (the hybrid vehicle described in [2] above), the polarization prediction index of the battery cell may be the maximum allowable output of the battery cell that can maintain the voltage of the battery cell within a range equal to or greater than the threshold voltage.

[0011] [4] In the hybrid vehicle of the present disclosure (the hybrid vehicle described in [1] or [2] above), the power supply unit may be capable of adjusting the power supplied from the battery to the electrically heated catalyst, and the control device may, when operating the power supply unit, control the power supply unit so that the value obtained by subtracting the required driving power and the power supplied to the electrically heated catalyst from the sum of polarization sign indicators related to signs of polarization of each of the plurality of battery cells is equal to or greater than 0. In this way, it is possible to suppress (delay) a sudden voltage drop due to polarization in at least one of the plurality of battery cells.

[0012] [5] In this case (the hybrid vehicle described in [4] above), the polarization predictor index of the battery cell may be the maximum allowable output of the battery cell that can maintain the voltage of the battery cell within a range equal to or greater than the inflection point voltage when the voltage drops. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram of a hybrid vehicle 20. [Figure 2] 10 is a flowchart illustrating an example of a catalyst heating routine. [Figure 3] 3 is an explanatory diagram showing a schematic relationship between the driving duration of the hybrid vehicle 20 and the voltage Vc[i] of the battery cell 50[i]. FIG. [Figure 4] 10 is a flowchart illustrating an example of a catalyst heating routine. DETAILED DESCRIPTION OF THE INVENTION

[0014] Next, embodiments of the present disclosure will be described using examples. [Example]

[0015] 1 is a schematic diagram of a hybrid vehicle 20 according to an embodiment of the present disclosure. As shown in the figure, the hybrid vehicle 20 includes an engine 22, a planetary gear 30, motors MG1 and MG2, inverters 41 and 42, a battery 50, a charger 60, and a hybrid electronic control unit (hereinafter referred to as "HVECU") 70.

[0016] The engine 22 is configured as an internal combustion engine that outputs power using fuel such as gasoline or diesel. A crankshaft 23 of the engine 22 is connected to a carrier of a planetary gear 30. The operation of the engine 22 is controlled by an engine electronic control unit (hereinafter referred to as "engine ECU") 28.

[0017] Exhaust gas from the engine 22 is discharged into the outside air via a purification device 25. The purification device 25 is equipped with an electrically heated catalyst (EHC) 26, which has a catalyst 26a and a heater 26b. The catalyst 26a purifies harmful components in the exhaust gas, such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx). The heater 26b is configured as a heat-generating member that generates heat when current is applied, and supports the catalyst 26a. The heater 26b is also connected to a power line 54 via a power supply circuit 27. The power supply circuit 27 is configured to adjust the power supplied from the battery 50 (power line 54) to the electrically heated catalyst 26 (heater 26b), and is controlled by the engine ECU 28.

[0018] The engine ECU 28 includes a microcomputer having a CPU, ROM, RAM, flash memory, input / output ports, and communication ports. The engine ECU 28 receives inputs such as the crank angle θcr of the engine 22 from the crank sensor 23a, the coolant temperature Tw of the engine 22 from the water temperature sensor, the intake air amount Qa of the engine 22 from the air flow meter, and the temperature Tc of the catalyst 26a from the temperature sensor 26c. The engine ECU 28 outputs control signals to the throttle valve, fuel injection valves, spark plugs, and the like. The engine ECU 28 calculates the engine speed Ne of the engine 22 based on the crank angle θcr, and calculates the load factor KL of the engine 22 (the ratio of the volume of air actually taken in during one cycle to the stroke volume per cycle of the engine 22) based on the intake air amount Qa and the engine speed Ne. The engine ECU 28 communicates with the HVECU 70.

[0019] Planetary gear 30 is configured as a single-pinion type planetary gear mechanism. The sun gear of planetary gear 30 is connected to the rotor of motor MG1, the ring gear is connected to drive shaft 37, and the carrier is connected to crankshaft 23 of engine 22. Drive shaft 37 is connected to drive wheels 39a, 39b via differential gear 38.

[0020] The motors MG1 and MG2 are configured as, for example, synchronous generator motors. The rotor of the motor MG1 is connected to the sun gear of the planetary gear 30, and the rotor of the motor MG2 is connected to the drive shaft 37. The inverters 41 and 42 are used to drive the motors MG1 and MG2, and are connected to a battery 50 via a power line 54. The motors MG1 and MG2 are rotationally driven by a motor electronic control unit (hereinafter referred to as "motor ECU") 40 controlling the switching of multiple switching elements of the inverters 41 and 42.

[0021] The motor ECU 40 includes a microcomputer having a CPU, ROM, RAM, flash memory, input / output ports, and communication ports. The motor ECU 40 receives inputs such as rotational positions θm1 and θm2 of the rotors of the motors MG1 and MG2 from rotational position sensors 43 and 44. The motor ECU 40 outputs control signals to inverters 41 and 42. The motor ECU 40 calculates rotational speeds Nm1 and Nm2 of the motors MG1 and MG2 based on the rotational positions θm1 and θm2. The motor ECU 40 communicates with the HVECU 70.

[0022] The battery 50 comprises n (n≧2) battery cells 50[1] to 50[n] connected in series. The battery cells 50[1] to 50[n] are each configured as a lithium-ion secondary battery. In this embodiment, the battery cells 50[1] to 50[n] have the same specifications (same rated voltage, etc.). The battery 50 is connected to inverters 41 and 42 via a power line 54. The battery 50 is managed by a battery electronic control unit (hereinafter referred to as "battery ECU") 52.

[0023] The battery ECU 52 includes a microcomputer having a CPU, ROM, RAM, flash memory, input / output ports, and communication ports. The battery ECU 52 receives inputs such as the voltage Vb of the battery 50 from the voltage sensor 51v, the voltages Vc[1] to Vc[n] of the battery cells 50[1] to 50[n] from the voltage sensors 51v[1] to 51v[n], the current Ib of the battery 50 (the discharge side is a positive value) from the current sensor 51i, and the temperature Tb of the battery 50 from the temperature sensor 51t. The battery ECU 52 calculates the state of charge (SOC) of the battery 50 based on the integrated value of the current Ib, and calculates input / output limits Win and Wout, which are the allowable input / output power of the battery 50, based on the state of charge (SOC), the voltages Vc[1] to Vc[n], and the temperature Tb. The battery ECU 52 communicates with the HVECU 70.

[0024] The charger 60 is connected to the power line 54. The charger 60 is configured to be able to charge the battery 50 using power from the external power source when the power plug 62 is connected to an external power source such as a household power source or a commercial power source, and is controlled by the HVECU 70.

[0025] The HVECU 70 is equipped with a microcomputer having a CPU, ROM, RAM, flash memory, input / output ports, and communication ports. The HVECU 70 receives inputs such as a start signal from a start switch 80, a shift position SP indicating the operating position of a shift lever 81 from a shift position sensor 82, an accelerator opening Acc indicating the depression amount of an accelerator pedal 83 from an accelerator pedal sensor 84, a brake pedal position BP indicating the depression amount of a brake pedal 85 from a brake pedal sensor 86, and a vehicle speed V from a vehicle speed sensor 87. The HVECU 70 outputs a control signal to the charger 60. The HVECU 70 communicates with the engine ECU 28, the motor ECU 40, and the battery ECU 52.

[0026] In the hybrid vehicle 20 of the embodiment, when the power plug 62 is connected to an external power source while the hybrid vehicle 20 is parked at a charging point such as a home or a charging station with the system stopped, the charger 60 is controlled so that the battery 50 is charged using power from the external power source. Then, when the system is started after charging the battery 50, the hybrid vehicle 20 runs in a CD mode (Charge Depleting) before the power storage percentage SOC of the battery 50 falls below the threshold value Shv, and after the power storage percentage SOC falls below the threshold value Shv, the hybrid vehicle 20 runs in a CS (Charge Sustaining) mode until the system is stopped.

[0027] The CD mode is a mode in which electric driving (EV driving) is prioritized over hybrid driving (HV driving) so as to reduce the power storage ratio SOC of the battery 50, and the CS mode is a mode in which EV driving and HV driving are used in combination so as to maintain the power storage ratio SOC of the battery 50 within a control range including a target ratio SOC* (for example, a threshold value Shv). The EV driving is driving that involves stopping the engine 22, and the HV driving is driving that involves operating the engine 22.

[0028] During HV running, the HVECU 70 sets a running torque requirement Tus required for running (required of the drive shaft 37) based on the accelerator opening Acc and the vehicle speed V, and calculates a running power requirement Pus by multiplying the set running torque requirement Tus by the rotation speed Nd of the drive shaft 37 (rotation speed Nm2 of the motor MG2). Next, the vehicle power requirement Pe* required for the vehicle (required of the engine 22) is set by subtracting the charging / discharging power requirement Pb* (the discharging side is a positive value) of the battery 50 from the running power requirement Pus. For example, the output limit Wout is used as the charging / discharging power Pb* in the CD mode, and a power set to reduce the difference between the power storage rate SOC and the target rate SOC* is used in the CS mode. The engine ECU 28 then sets a target rotation speed Ne* and a target torque Te* for the engine 22 and torque commands Tm1* and Tm2* for the motors MG1 and MG2 so that the engine 22 outputs a required vehicle power Pe* and a required running torque Tus (required running power Pus) is output to the drive shaft 37 within the input / output limits Win and Wout of the battery 50. The engine ECU 28 also transmits the target rotation speed Ne* and the target torque Te* to the engine ECU 28 and the torque commands Tm1* and Tm2* to the motor ECU 40. The engine ECU 28 performs operation control of the engine 22 (specifically, intake air amount control, fuel injection control, ignition control, etc.) so that the engine 22 is operated based on the target rotation speed Ne* and the target torque Te*. The motor ECU 40 performs drive control of the motors MG1 and MG2 (specifically, switching control of multiple switching elements of the inverters 41 and 42) so that the motors MG1 and MG2 are driven by the torque commands Tm1* and Tm2*. In HV driving, when a stop condition for the engine 22 is met, the engine 22 is stopped and the vehicle transitions to EV driving. The stop condition is set so that it is more likely to be met (making it easier to transition to EV driving) in CD mode than in CS mode.

[0029] In EV driving, the HVECU 70 sets the required driving torque Tus and required driving power Pus in the same way as in HV driving, sets the torque command Tm1* of the motor MG1 to a value of 0, and sets the torque command Tm2* of the motor MG2 so that the required driving torque Tus (required driving power Pus) is output to the drive shaft 37 within the input / output limits Win, Wout of the battery 50. The torque commands Tm1* and Tm2* are then sent to the motor ECU 40. The drive control of the motors MG1 and MG2 by the motor ECU 40 has been described above. In EV driving, when the start condition for the engine 22 is met, the engine 22 is started and the vehicle transitions to HV driving. The start condition is set so that it is less likely to be met in CD mode than in CS mode (making it more difficult to transition to HV driving).

[0030] Next, the operation of the hybrid vehicle 20 of this embodiment, particularly the heating process of the electrically heated catalyst 26 (catalyst 26a) of the purification device 25 in the CD mode, will be described. Figure 2 is a flowchart showing an example of a catalyst heating routine executed by the engine ECU 28. This routine is repeatedly executed in the CD mode.

[0031] 2 is executed, the engine ECU 28 first receives data such as the temperature Tc of the catalyst 26a, the voltage Vc[i] of the battery cell 50[i] (i: 1 to n), the current Ib of the battery 50, and the required running power Pus (step S100). Here, the temperature Tc of the catalyst 26a is input as a value detected by the temperature sensor 26c. Note that the temperature Tc of the catalyst 26a may be input as a value estimated based on the rotation speed Ne, load factor KL, and coolant temperature Tw of the engine 22. The voltage Vc[i] of the battery cell 50[i] is input as a value detected by a voltage sensor 51v[i] from the battery ECU 52 via the HVECU 70 through communication. The current Ib of the battery 50 is input as a value detected by a current sensor 51i from the battery ECU 52 via the HVECU 70 through communication. The required driving power Pus is calculated by multiplying the required driving torque Tus, which is based on the accelerator opening Acc from the accelerator pedal sensor 84 and the vehicle speed V from the vehicle speed sensor 87, by the rotation speed Nd of the drive shaft 37 (the rotation speed Nm2 of the motor MG2), and is further input via communication from the HVECU 70.

[0032] Next, it is determined whether the catalyst 26a is active or inactive based on the temperature Tc of the catalyst 26a (step S110). This determination is made, for example, by comparing the temperature Tc of the catalyst 26a with the activation temperature Tcref. If it is determined that the catalyst 26a is active, the power supply circuit 27 is stopped (step S170), and this routine ends. Note that stopping the power supply circuit 27 includes not only stopping from operation, but also continuing to stop.

[0033] When it is determined in step S110 that the catalyst 26a is inactive, the polarization sign index TWoutip[i] and the polarization prediction index TWoutth[i] of the battery cell 50[i] are calculated (steps S120, S130). Here, the polarization sign index TWoutip[i] of the battery cell 50[i] is an index related to a sign of polarization of the battery cell 50[i]. The polarization prediction index TWoutth[i] of the battery cell 50[i] is an index related to a prediction of polarization of the battery cell 50[i].

[0034] FIG. 3 is an explanatory diagram showing a relationship between the operation duration of the hybrid vehicle 20 and the voltage Vc[i] of the battery cell 50[i]. FIG. 3 shows a case where the current Ib of the battery 50 is constant in CD mode. In the diagram, "Vcip[i]" and "Vcth[i]" represent the inflection point voltage when the voltage of the battery cell 50[i] drops, and a threshold voltage that is somewhat higher than that. In the embodiment, the battery cells 50[i] have the same specifications, so the inflection point voltage Vcip[i] and the threshold voltage Vcth[i] are the same values ​​regardless of the battery cell 50[i]. As shown in the diagram, the voltage Vc[i] of the battery cell 50[i] decreases as the operation duration of the hybrid vehicle 20 (the duration of CD mode) increases. At this time, the larger the current Ib of the battery 50, the more rapidly the voltage Vc[i] of the battery cell 50[i] decreases. Furthermore, when the voltage Vc[i] of the battery cell 50[i] is less than the inflection point voltage Vcip[i], the amount of drop per unit time of the voltage Vc[i] of the battery cell 50[i] for the current Ib of the same battery 50 is greater than when the voltage Vc[i] of the battery cell 50[i] is equal to or greater than the inflection point voltage Vcip[i]. The sudden drop in the voltage Vc[i] of the battery cell 50[i] is thought to be due to polarization of the battery cell 50[i].

[0035] Based on these characteristics of the battery 50, a polarization sign index TWoutip[i] and a polarization prediction index TWoutth[i] of the battery cell 50[i] are defined. The polarization sign index TWoutip[i] of the battery cell 50[i] is defined as the maximum allowable output of the battery cell 50[i] that can maintain the voltage Vc[i] of the battery cell 50[i] within a range equal to or greater than the inflection point voltage Vcip[i]. The polarization prediction index TWoutth[i] of the battery cell 50[i] is defined as the maximum allowable output of the battery cell 50[i] that can maintain the voltage Vc[i] of the battery cell 50[i] within a range equal to or greater than the threshold voltage Vcth[i].

[0036] In the embodiment, the polarization predictor index TWoutip[i] of the battery cell 50[i] is calculated according to equation (1) using the voltage Vc[i] and internal resistance Rc[i] of the battery cell 50[i], the current Ib of the battery 50, and the inflection point voltage Vcip[i]. The polarization predictor index TWoutth[i] of the battery cell 50[i] is calculated according to equation (2) using the voltage Vc[i] and internal resistance Rc[i] of the battery cell 50[i], the current Ib of the battery 50, and the threshold voltage Vcth[i]. In the embodiment, the battery cells 50[i] have the same specifications, so the same value is used for the internal resistance Rc[i] of the battery cell 50[i] regardless of the battery cell 50[i]. In equations (1) and (2), "Vc[i]+Ib×Rc[i]" means the open-circuit voltage Vcoc[i] of the battery cell 50[i], and the value in {} means the maximum allowable current Imax[i] of the battery cell 50[i]. Because the threshold voltage Vcth[i] is higher than the inflection point voltage Vcip[i], the polarization prediction index TWoutth[i] is smaller than the polarization sign index Twoutip[i].

[0037] TWoutip[i]=Vcip[i]×[(Vc[i]+Ib×Rc[i]-Vcip[i]) / Rc[i]] (1) TWoutth[i]=Vcth[i]×[(Vc[i]+Ib×Rc[i]-Vcth[i]) / Rc[i]] (2)

[0038] Next, the sum (ΣTWoutth[i]) of the polarization prediction indices TWoutth[i] of the battery cells 50[i] is compared with the required running power Pus (step S140). This process is to determine whether polarization is predicted in at least one of the battery cells 50[i]. If the sum (ΣTWoutth[i]) of the polarization prediction indices TWoutth[i] of the battery cells 50[i] is equal to or greater than the required running power Pus, it is determined that polarization is not predicted in any of the battery cells 50[i], the power supply circuit 27 is stopped (step S170), and this routine ends.

[0039] If the sum (ΣTWoutth[i]) of the polarization prediction indices TWoutth[i] of the battery cells 50[i] is less than the required running power Pus in step S140, it is determined that polarization is predicted in at least one of the battery cells 50[i], and the power supply circuit 27 is activated (step S150). In this embodiment, the power supply circuit 27 is controlled so that a predetermined amount of power is supplied to the electrically heated catalyst 26 (heater 26b). The activation of the power supply circuit 27 heats the catalyst 26a.

[0040] Next, it is determined whether the catalyst 26a is active or inactive (step S160). If it is determined that the catalyst 26a is inactive, the routine returns to step S150. The processes of steps S150 to S160 are repeated until the catalyst 26a becomes active. If it is determined in step S160 that the catalyst 26a is active, the power supply circuit 27 is stopped (step S170), and this routine ends. The threshold voltage Vcth[i] of the battery cell 50[i] described above is set so that the catalyst 26a becomes active by heating before the voltage Vc[i] of the battery cell 50[i] reaches the inflection point voltage Vcip[i]. This control allows the catalyst 26a to be activated in CD mode before a drop in output from the battery 50 occurs due to a sudden drop in voltage caused by polarization of at least one of the battery cells 50[i]. This prevents a situation in which, in CD mode, a drop in output from the battery 50 occurs due to a sudden drop in voltage caused by polarization of at least one of the battery cells 50[i], and when an attempt is made to supplement the driving power Pus with the power of the engine 22, the catalyst 26a is inactive, resulting in a deterioration in emissions.

[0041] In the hybrid vehicle 20 of the embodiment described above, when the vehicle is in CD mode, the catalyst 26a is inactive, and polarization is predicted in at least one of the battery cells 50[1] to 50[n], the power supply circuit 27 is operated to supply power to the electrically heated catalyst 26 (heater 26b) and heat and activate the catalyst 26a. This prevents a situation in which, in CD mode, a drop in output from the battery 50 occurs due to a sudden drop in voltage caused by polarization in at least one of the battery cells 50[1] to 50[n], and the driving power Pus is supplemented by power from the engine 22, resulting in a deterioration in emissions due to an inactive catalyst 26a.

[0042] In the embodiment, the engine ECU 28 executes the catalyst heating routine of Fig. 2. However, instead of this, the engine ECU 28 may execute the catalyst heating routine of Fig. 4. The routine of Fig. 4 differs from the routine of Fig. 2 in that the processing of step S150 is replaced by the processing of steps S152, S152. Therefore, the processing of the routine of Fig. 4 that is the same as the routine of Fig. 2 is assigned the same step number, and detailed description thereof will be omitted.

[0043] 4, if the sum (ΣTWoutth[i]) of the polarization prediction indicators TWoutth[i] of the battery cells 50[i] is less than the required running power Pus in step S140, it is determined that polarization is predicted in at least one of the battery cells 50[i], a target power Phc to be supplied to the electrically heated catalyst 26 (heater 26b) is set (step S152), and the power supply circuit 27 is controlled so that the set target power Phc is supplied to the electrically heated catalyst 26 (heater 26b) (step S154). Here, the target power Phc is set so that the value obtained by subtracting the required running power Pus and the target power Phc from the sum (ΣTWoutip[i]) of the polarization sign indicators TWoutip[i] of the battery cells 50[i] is equal to or greater than 0, that is, within a range equal to or less than the value obtained by subtracting the required running power Pus from the sum (ΣTWoutip[i]) of the polarization sign indicators TWoutip[i] of the battery cells 50[i]. This makes it possible to suppress (delay) a sudden voltage drop due to polarization in at least one of the battery cells 50[i].

[0044] 2 and 4, it is determined that polarization is predicted in at least one of the battery cells 50[i] when the sum of the polarization prediction indicators TWoutth[i] of the battery cells 50[i] is less than the required running power Pus. However, instead of this, it may be determined that polarization is predicted in at least one of the battery cells 50[i] when the voltage Vc[i] of at least one battery cell 50[i] is less than the threshold voltage Vcth[i].

[0045] 2 and 4, a constant value is used for the threshold voltage Vcth[i] of the battery cell 50[i], regardless of the current Ib (average current) of the battery 50. However, a value that increases as the current Ib (average current) of the battery 50 increases may be used. This is because the larger the current Ib (average current) of the battery 50, the shorter the time it takes for the voltage Vc[i] of the battery cell 50[i] to reach the inflection point voltage Vcip[i] after reaching the threshold voltage Vcth[i].

[0046] In the embodiment, the hybrid vehicle 20 includes the engine ECU 28, the motor ECU 40, the battery ECU 52, and the HVECU 70. However, at least two of these may be integrated into one unit.

[0047] In the embodiment, the hybrid vehicle 20 is configured to include an engine 22 and a motor MG1 connected via a planetary gear 30 to a drive shaft 37 connected to drive wheels 39a and 39b, a motor MG2 connected to the drive shaft 37, and a battery 50 capable of exchanging power with the motors MG1 and MG2. However, the present invention is not limited to this configuration, and any hybrid vehicle configuration may be used as long as it includes a running engine with an electrically heated catalyst attached to the exhaust system, a running motor, and a battery having a plurality of battery cells connected in series and capable of exchanging power with the motor. For example, the hybrid vehicle may be configured to include a motor connected via a transmission to a drive shaft connected to the drive wheels, an engine connected to the motor via a clutch, and a battery capable of exchanging power with the motor.

[0048] The correspondence between the main elements of the embodiment and the main elements of the invention described in the "Means for Solving the Problem" section will be explained below. In the embodiment, the engine 22 corresponds to the "engine," the motor MG2 corresponds to the "motor," the battery 50 corresponds to the "battery," the power supply circuit 27 corresponds to the "power supply unit," and the engine ECU 28, the motor ECU 40, and the hybrid ECU 70 correspond to the "controller."

[0049] The correspondence between the main elements of the Examples and the main elements of the invention described in the "Means for Solving the Problem" section does not limit the elements of the invention described in the "Means for Solving the Problem" section, since the Examples are examples for specifically explaining the mode for implementing the invention described in the "Means for Solving the Problem" section. In other words, the interpretation of the invention described in the "Means for Solving the Problem" section should be based on the description in that section, and the Examples are merely specific examples of the invention described in the "Means for Solving the Problem" section.

[0050] The above describes the form for implementing the present disclosure using examples, but the present disclosure is not limited to these examples in any way, and it goes without saying that the present disclosure can be implemented in various forms within the scope that does not deviate from the gist of the present disclosure. [Industrial Applicability]

[0051] The present disclosure is applicable to the hybrid vehicle manufacturing industry and the like. [Explanation of symbols]

[0052] 20 Hybrid vehicle, 22 Engine, 23 Crankshaft, 23a Crank sensor, 25 Purification device, 26 Electrically heated catalyst, 26a Catalyst, 26b Heater, 26c Temperature sensor, 27 Power supply circuit, 28 Engine ECU, 30 Planetary gear, 37 Drive shaft, 38 Differential gear, 39a, 39b Drive wheels, 40 Motor ECU, 41, 42 Inverter, 43, 44 Rotational position sensor, 50 Battery, 51i Current sensor, 51v, 51v[1] to 51v[n] Voltage sensor, 51t Temperature sensor, 52 Battery ECU, 54 Power line, 60 Charger, 62 Power plug, 70 HVECU, 80 Start switch, 81 Shift lever, 82 Shift position sensor, 83 Accelerator pedal, 84 Accelerator pedal sensor, 85 Brake pedal, 86 Brake pedal sensor, 87 vehicle speed sensor.

Claims

1. an engine for driving in which an electrically heated catalyst is attached to an exhaust system; A driving motor; a battery having a plurality of battery cells connected in series and capable of exchanging power with the motor; a power supply unit capable of supplying power from the battery to the electrically heated catalyst; a control device that controls the engine and the motor by switching between a CD (Charge Depleting) mode and a CS (Charge Sustaining) mode so that the vehicle travels at a required power level; A hybrid vehicle comprising: the control device activates the power supply unit when the CD mode is in effect, the electrically heated catalyst is inactive, and polarization of at least one of the plurality of battery cells is predicted; the control device determines that polarization of at least one of the plurality of battery cells is predicted when the vehicle is in the CD mode, the electrically heated catalyst is inactive, and the required running power is greater than the sum of polarization prediction indexes related to the prediction of polarization of each of the plurality of battery cells, or when the voltage of at least one of the battery cells is less than a threshold voltage that is higher than an inflection point voltage when a voltage drop occurs. Hybrid car.

2. The hybrid vehicle according to claim 1, the polarization prediction index of the battery cell is a maximum allowable output of the battery cell that can maintain a voltage of the battery cell within a range equal to or greater than the threshold voltage; Hybrid car.

3. The hybrid vehicle according to claim 1, the power supply unit is capable of adjusting the power supplied from the battery to the electrically heated catalyst; When activating the power supply unit, the control device controls the power supply unit so that a value obtained by subtracting the required driving power and the supply power supplied to the electrically heated catalyst from a sum of polarization sign indicators related to signs of polarization of each of the plurality of battery cells is equal to or greater than 0. Hybrid car.

4. 4. The hybrid vehicle according to claim 3, the polarization predictor index of the battery cell is a maximum allowable output of the battery cell that can maintain the voltage of the battery cell within a range equal to or higher than an inflection point voltage when the voltage drops; Hybrid car.

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