JP7750197B2 - Hybrid vehicles - Google Patents

Description

This disclosure relates to hybrid vehicles.

Conventionally, this type of hybrid vehicle has been proposed as comprising a driving engine with an electrically heated catalyst attached to the exhaust system, a driving motor, a battery that can exchange power with the motor, and a power adjustment unit that adjusts the power supplied from the battery to the electrically heated catalyst, and running by switching between CD (Charge Depleting) mode and 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.

JP 2019-85108 A

In the hybrid vehicle described above, if the engine is stopped and high battery output continues while the SOC is greater than the predetermined SOC in CD mode, 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's power is then used to compensate for the drop in driving power caused by the drop in battery output, this could result in a deterioration in emissions due to the electrically heated catalyst being inactive.

The primary purpose of the hybrid vehicle disclosed herein is to suppress the deterioration of emissions.

The hybrid vehicle disclosed herein employs the following measures to achieve the above-mentioned primary objective.

[1] The hybrid vehicle of the present disclosure 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 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 gist of this is as follows.

In the hybrid vehicle disclosed herein, when the electrically heated catalyst is inactive in CD mode and polarization of at least one of the multiple battery cells 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 of the multiple battery cells. As a result, it is possible to prevent a situation in which a drop in battery output occurs in CD mode due to a sudden drop in voltage caused by polarization of at least one of the multiple battery cells and emissions deteriorate when driving power is supplemented by engine power due to an inactive electrically heated catalyst.

[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 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 indices related to the polarization prediction 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.

[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.

[4] In a hybrid vehicle of the present disclosure (a 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 when operating the power supply unit, the control device may 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.

[5] In this case (the hybrid vehicle described in [4] above), the polarization predictor indicator 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.

FIG. 2 is a schematic diagram of a hybrid vehicle 20. 10 is a flowchart illustrating an example of a catalyst heating routine. 10 is an explanatory diagram showing a schematic relationship between the operation duration of a hybrid vehicle 20 and the voltage Vc[i] of a battery cell 50[i]. FIG. 10 is a flowchart illustrating an example of a catalyst heating routine.

Next, we will explain the form for implementing this disclosure using examples.

Figure 1 is a schematic diagram of a hybrid vehicle 20 according to one embodiment of the present disclosure. As shown, the hybrid vehicle 20 of the embodiment 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.

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

Exhaust 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, such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx). The heater 26b is configured as a heat-generating element that generates heat when electricity 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.

The engine ECU 28 includes a microcomputer with 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 volume 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 valve, spark plug, and other components. The engine ECU 28 calculates the engine 22 rotation speed Ne based on the crank angle θcr, and calculates the engine 22 load factor KL (the ratio of the volume of air actually taken in per cycle to the stroke volume per cycle of the engine 22) based on the intake air volume Qa and the engine 22 rotation speed Ne. The engine ECU 28 communicates with the HV ECU 70.

Planetary gear 30 is configured as a single-pinion 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.

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

The motor ECU 40 is equipped with a microcomputer having a CPU, ROM, RAM, flash memory, input/output ports, and communication ports. The motor ECU 40 receives inputs such as the rotational positions θm1 and θm2 of the rotors of 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 the rotational speeds Nm1 and Nm2 of motors MG1 and MG2 based on the rotational positions θm1 and θm2. The motor ECU 40 communicates with the HVECU 70.

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

The battery ECU 52 is equipped with a microcomputer having a CPU, ROM, RAM, flash memory, input/output ports, and communication ports. The battery ECU 52 receives inputs such as the battery 50 voltage Vb 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 battery 50 current Ib (the discharge side is a positive value) from the current sensor 51i, and the battery 50 temperature Tb from the temperature sensor 51t. The battery ECU 52 calculates the battery 50's power storage percentage SOC based on the integrated value of the current Ib, and calculates the input/output limits Win and Wout, which are the allowable input/output power of the battery 50, based on the power storage percentage SOC, the voltages Vc[1] to Vc[n], and the temperature Tb. The battery ECU 52 communicates with the HVECU 70.

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

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 the start switch 80, a shift position SP indicating the operating position of the shift lever 81 from the shift position sensor 82, an accelerator opening Acc indicating the amount of depression of the accelerator pedal 83 from the accelerator pedal sensor 84, a brake pedal position BP indicating the amount of depression of the brake pedal 85 from the brake pedal sensor 86, and a vehicle speed V from the vehicle speed sensor 87. The HVECU 70 outputs a control signal to the charger 60. The HVECU 70 communicates with the engine ECU 28, motor ECU 40, and battery ECU 52.

In the hybrid vehicle 20 of this embodiment, when the power plug 62 is connected to an external power source while the system is stopped and the vehicle is parked at a charging point such as at home or a charging station, 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 CD mode (Charge Depleting) until the battery 50's power storage percentage SOC falls below the threshold value Shv, and after the power storage percentage SOC falls below the threshold value Shv, the hybrid vehicle runs in CS (Charge Sustaining) mode until the system is stopped.

CD mode is a mode in which electric driving (EV driving) is prioritized over hybrid driving (HV driving) so as to reduce the battery 50's power storage ratio SOC, and CS mode is a mode in which EV driving and HV driving are used in combination so as to maintain the battery 50's power storage ratio SOC within a control range including the target ratio SOC* (e.g., threshold value Shv). EV driving is driving with the engine 22 stopped, and HV driving is driving with the engine 22 operating.

During HV driving, the HV ECU 70 sets the required driving torque Tus (required from the drive shaft 37) required for driving based on the accelerator pedal position Acc and the vehicle speed V, and calculates the required driving power Pus by multiplying the set required driving torque Tus by the rotation speed Nd of the drive shaft 37 (rotation speed Nm2 of the motor MG2). Next, the required vehicle power Pe* (required from the engine 22) is set by subtracting the required charging/discharging power Pb* (the discharging side is a positive value) of the battery 50 from the required driving power Pus. For example, the required charging/discharging power Pb* uses the output limit Wout in CD mode, and uses a power set to minimize the difference between the storage percentage SOC and the target percentage SOC* in CS mode. Then, the target rotation speed Ne* and target torque Te* of the engine 22 and torque commands Tm1* and Tm2* of the motors MG1 and MG2 are set so that the vehicle power requirement Pe* is output from the engine 22 and the running torque requirement Tus (running power requirement Pus) is output to the drive shaft 37 within the range of the input/output limits Win and Wout of the battery 50. Furthermore, the target rotation speed Ne* and target torque Te* are sent to the engine ECU 28, and the torque commands Tm1* and Tm2* are sent 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 operates based on the target rotation speed Ne* and the target torque Te*. Motor ECU 40 controls the drive of motors MG1, MG2 (specifically, controls the switching of multiple switching elements of inverters 41, 42) so that motors MG1, MG2 are driven by torque commands Tm1*, Tm2*. In HV driving, when engine 22 stop conditions are met, engine 22 is stopped and the vehicle transitions to EV driving. The stop conditions are set so that they are more likely to be met in CD mode than in CS mode (making it easier to transition to EV driving).

In EV driving, the HV ECU 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* for motor MG1 to a value of 0, and sets the torque command Tm2* for 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 motors MG1 and MG2 by the motor ECU 40 has been described above. In EV driving, when the start conditions for the engine 22 are met, the engine 22 is started and the vehicle transitions to HV driving. The start conditions are set so that they are less likely to be met in CD mode than in CS mode (making it more difficult to transition to HV driving).

Next, we will explain 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 CD mode. Figure 2 is a flowchart showing an example of a catalyst heating routine executed by the engine ECU 28. This routine is executed repeatedly in CD mode.

When the catalyst heating routine of FIG. 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 driving power Pus (step S100). Here, the temperature Tc of the catalyst 26a is input as a value detected by the temperature sensor 26c. The temperature Tc of the catalyst 26a may also be input as a value estimated based on the engine 22 rotation speed Ne, load factor KL, coolant temperature Tw, etc. The voltage Vc[i] of the battery cell 50[i] is input as a value detected by the 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 the 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 pedal 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 (rotation speed Nm2 of the motor MG2), and is further input via communication from the HVECU 70.

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 it from operation, but also keeping it stopped.

If it is determined in step S110 that the catalyst 26a is inactive, the polarization sign index TWoutip[i] and 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].

Figure 3 is an explanatory diagram showing the relationship between the operating time of the hybrid vehicle 20 and the voltage Vc[i] of the battery cell 50[i]. Figure 3 shows the case where the current Ib of the battery 50 is constant in CD mode. In the figure, "Vcip[i]" and "Vcth[i]" represent the inflection point voltage when the voltage of the battery cell 50[i] drops, and a threshold voltage 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 figure, the voltage Vc[i] of the battery cell 50[i] decreases as the operating time of the hybrid vehicle 20 (the duration of CD mode) increases. At this time, the greater 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 decrease 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 decrease in the voltage Vc[i] of the battery cell 50[i] is thought to be due to polarization of the battery cell 50[i].

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

In the embodiment, the polarization prediction index TWoutip[i] of the battery cell 50[i] is calculated 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] according to equation (1). The polarization prediction index TWoutth[i] of the battery cell 50[i] is calculated using the voltage Vc[i] and internal resistance Rc[i] of the battery 50[i], the current Ib of the battery 50, and the threshold voltage Vcth[i] according to equation (2). In the embodiment, because the battery cells 50[i] have the same specifications, 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]" represents the open-circuit voltage Vcoc[i] of the battery cell 50[i], and the value in brackets { } represents 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 Twooutip[i].

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)

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 determines whether polarization is predicted for 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 for any of the battery cells 50[i], the power supply circuit 27 is stopped (step S170), and this routine is terminated.

If, in step S140, the sum (ΣTWoutth[i]) of the polarization prediction indicators TWoutth[i] of the battery cells 50[i] is less than the required driving power Pus, 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). Activation of the power supply circuit 27 heats the catalyst 26a.

Next, the system determines whether the catalyst 26a is active or inactive (step S160). If it determines that the catalyst 26a is inactive, the system returns to step S150. Steps S150 through S160 are repeatedly executed until the catalyst 26a becomes active. If it determines in step S160 that the catalyst 26a is active, the system shuts down the power supply circuit 27 (step S170) and terminates this routine. 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 battery 50 output occurs due to a sudden voltage drop caused by polarization of at least one of the battery cells 50[i]. This prevents the catalyst 26a from being inactive and causing emissions to deteriorate when, in CD mode, a drop in battery 50 output occurs due to a sudden drop in voltage caused by polarization of at least one of the battery cells 50[i] and driving power Pus is supplemented by power from the engine 22.

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 activated to supply power to the electrically heated catalyst 26 (heater 26b), heating and activating the catalyst 26a. This prevents a situation in which, in CD mode, a drop in battery 50 output 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 attempted to be supplemented by power from the engine 22, resulting in a deterioration in emissions due to an inactive catalyst 26a.

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

In the routine of Figure 4, when the sum (ΣTWoutth[i]) of the polarization prediction indicators TWoutth[i] of the battery cells 50[i] is less than the required driving 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 predictor 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 predictor 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].

In the catalyst heating routines of Figures 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 driving 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] for at least one battery cell 50[i] is less than the threshold voltage Vcth[i].

In the catalyst heating routines of Figures 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 also 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 threshold voltage Vcth[i] and then the inflection point voltage Vcip[i].

In the embodiment, the hybrid vehicle 20 is equipped with an engine ECU 28, a motor ECU 40, a battery ECU 52, and an HV ECU 70. However, at least two of these may be configured as an integrated unit.

In this embodiment, the hybrid vehicle 20 is configured to include an engine 22 and motor MG1 connected via a planetary gear 30 to a drive shaft 37 connected to drive wheels 39a, 39b, a motor MG2 connected to drive shaft 37, and a battery 50 capable of exchanging power with motors MG1, MG2. However, this is not limited to this, and any hybrid vehicle configuration may be used that includes a running engine with an electrically heated catalyst attached to the exhaust system, a running motor, and a battery with multiple 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.

The following explains 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. 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, motor ECU 40, and hybrid ECU 70 correspond to the "control device."

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, as the Examples are examples used to specifically explain the form 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.

The above describes the forms for implementing this disclosure using examples, but the disclosure is not limited to these examples in any way, and it goes without saying that the disclosure can be implemented in various forms without departing from the spirit of the disclosure.

This disclosure can be used in the hybrid vehicle manufacturing industry, etc.

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 HV ECU, 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 (4)

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. 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. 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. 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.