JP5200797B2 - Control method and apparatus for hybrid vehicle - Google Patents

Description

  The present invention relates to control of a hybrid vehicle including an engine and a drive motor, and particularly relates to a control procedure during regenerative braking.

  Conventionally, in a hybrid vehicle, it is known to regenerate kinetic energy and charge a battery by causing a driving motor to generate electricity during braking (regenerative braking). In addition, even if the generated electric power becomes larger than a predetermined value, it is not preferable to send an overcurrent exceeding the allowable charge current to the battery. In such a case, the power generation operation efficiency of the drive motor is reduced. It is also known that the power is reduced so that excessive power is not generated (see, for example, Patent Document 1).

However, if the operating efficiency is reduced in this way, the amount of heat generated by the drive motor that operates to generate electricity may increase and reliability may be reduced. It is proposed to operate the starter to forcibly rotate the engine (motoring). The rotational energy of the engine motored in this way can be used for driving the generator after the end of regenerative braking.
JP 2006-197756 A JP-A-7-131905

  However, even if trying to consume surplus power by motoring the engine as in the latter conventional example, the rotation does not start immediately, so surplus generated power cannot be consumed for a while at the beginning of motoring. become.

  The present invention has been made in view of such a point, and an object of the present invention is to start up the engine rotation at the initial stage of motoring in the hybrid vehicle in which the engine is motored during regenerative braking as described above. It is to make it possible to completely consume the surplus power.

  In order to achieve the above object, in the present invention, while the engine speed at the initial stage of motoring is low, the efficiency of the motor operation of the generator for the motoring is reduced.

  Specifically, the invention of claim 1 includes a first step of regenerating kinetic energy by causing a driving motor to generate electricity during braking of an automobile, a second step of charging the battery with the generated power, and the generated power is a battery. And a third step of consuming surplus power by operating a generator connected to the engine when the charge limit is greater than or equal to a predetermined charge limit of the hybrid vehicle. When the engine speed increases due to the motor operation of the generator, the fourth aspect is characterized in that the operation efficiency of the generator is lower than its maximum efficiency until it reaches the set speed. .

  By the above-described method, during regenerative braking of the hybrid vehicle, the driving motor is operated to generate electric power to regenerate kinetic energy (first step), and the battery is charged thereby (second step). At this time, the generated power is generally increased in accordance with an increase in the braking force requirement for the automobile. However, in this case, the generated power may reach a charge limit corresponding to the charge allowable current of the battery.

  Therefore, the motor connected to the engine is operated to consume surplus generated power exceeding the charge limit (third step). At this time, by setting the operating efficiency of the generator to a state lower than the maximum efficiency until the engine speed rises and reaches the set rotational speed (fourth step), the power consumption for motor operation is correspondingly increased. The excess power can be consumed even if the engine speed is low.

  However, if the operating efficiency is lowered in this manner, the heat generation of the generator increases accordingly, and therefore, in the fourth step, it is preferable to increase the operating efficiency of the generator as the engine speed increases. If the engine speed is equal to or higher than the set speed, surplus power can be consumed without reducing the operating efficiency of the generator. After that, if the engine speed reaches a predetermined speed higher than the set speed, it is better not to increase the engine speed any more from the viewpoint of vibration, noise, reliability, etc. The efficiency is lowered (fifth step: claim 2).

  Preferably, when the generated power of the drive motor increases to exceed the charge limit as described above, the start of engine motoring in the third step is delayed for a predetermined period, and the power generation operation of the drive motor is It is to reduce the efficiency (sixth step: claim 3). In other words, since a hybrid vehicle may shift to a motor-driven acceleration operation after a short deceleration, the motoring is frequently started and stopped by not performing motoring of the engine for a while. It is prevented from being repeated.

Then, while delaying the start of engine motoring, in the sixth step, the efficiency of the power generation operation of the drive motor is decreased, and if the efficiency of the power generation operation decreases until the generated power reaches the charge limit , Engine motoring is started (Claim 4).

  If the generator operating efficiency is increased as described above in response to the rise of the engine speed and sufficient surplus power can be consumed at the set rotational speed or higher, not only the generator operating efficiency but also the power generation of the drive motor can be achieved. The operating efficiency may be increased (seventh step: claim 5).

Further, after the engine operating speed of the generator has been reduced again so that the engine speed that rises reaches the predetermined rotational speed and the engine speed does not increase as described above, the operating efficiency of the generator is reduced. If the braking force request further increases even when the predetermined lower limit value is reached, the power generation operation efficiency of the drive motor is reduced again accordingly (eighth and ninth steps: claims 5 and 6).

  From another point of view, the present invention relates to a motor regeneration control unit that regenerates kinetic energy by causing a drive motor to generate electricity during braking of an automobile, a charge control unit that charges a battery with the generated power, and the generated power is a battery. The above-mentioned generator is intended for a control device for a hybrid vehicle comprising engine / motoring control means for consuming surplus power by operating a generator connected to an engine when a predetermined charging limit is exceeded. When the engine speed increases due to the operation of the motor, generator efficiency control means is provided for setting the operating efficiency of the generator to be lower than its maximum efficiency until it reaches the set speed (claim). Item 7).

  According to the control device having this configuration, the control method according to the first aspect of the present invention can be easily executed, and the operational effects of the invention can be obtained easily and reliably.

  And, while the generator efficiency control means increases the operating efficiency of the generator with the increase until the engine speed reaches the set speed, if the engine speed reaches a predetermined speed higher than the set speed, If the operating efficiency of the generator is lowered again (claim 8), the operation of the invention according to claim 2 described above can be obtained.

  Further, the motor regeneration control means controls the generated power of the driving motor in response to the braking force request, and the engine / motoring control means increases the generated power in response to the increase in the braking force request and the charge limit The motor efficiency control is configured to start the motor operation control of the generator after the elapse of a predetermined delay period, and further reduce the efficiency of the power generation operation of the drive motor at least during the delay period. If a means is provided (Claim 9), the effect | action of the invention which concerns on Claim 3 mentioned above is acquired.

In that case, the operating efficiency of the driving motor may be lowered until the generated power reaches the charging limit by the motor efficiency control means in the delay period.

Preferably, the motor efficiency control means is configured to increase the power generation operation efficiency of the drive motor in accordance with the increase in the engine speed after the generator operation efficiency is increased to the maximum efficiency by the generator efficiency control means. Or when the demand for braking force further increases after the generator operating efficiency is reduced to the predetermined lower limit by the generator efficiency control means, the power generating operating efficiency of the drive motor is reduced accordingly. (Claims 11 and 12).

As described above, according to the hybrid vehicle control method and the like according to the present invention, the driving motor generates power during braking of the vehicle to regenerate kinetic energy, thereby charging the battery and generating the generated power. When the battery is above the specified charge limit, the engine is motored by the generator to consume excess power. In the initial stage of the motoring, the engine speed rises until the set speed is reached. By making the efficiency of the motor operation of the generator lower than its maximum efficiency, surplus power can be consumed even if the engine speed is low.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the following description of the preferred embodiment is merely illustrative in nature, and is not intended to limit the present invention, its application, or its use.

(Outline of control system)
FIG. 1 schematically shows a power system of a hybrid vehicle 10 (HEV) equipped with a control system according to the present invention. In the figure, a thick solid line indicates a power transmission path, and a thin solid line indicates a power transmission path. A one-dot chain line indicates a signal transmission path.

  The hybrid vehicle 10 shown in the figure is of a so-called series type, and includes a motor 14 (drive motor) that directly drives the wheels 12, a battery 16 that supplies power to the motor 14, and an engine 18. A generator 20 that generates power, an inverter 22 that connects the motor 14 and the battery 16, and an inverter 24 that connects the generator 20 and the battery 16.

  More specifically, the motor 14 is connected to the battery 16 via the inverter 22 and is connected to the generator 20 via the inverters 22 and 24, whereby the electric power stored in the battery 16 or the generator 20 generates power. The power supply is activated. Further, the output of the motor 14 (the driving force of the wheels 12) is controlled by controlling the inverter 22 and adjusting the electric power supplied to the motor 14 via the inverter 22. Further, the motor 14 can also generate electricity, and is driven by the wheels 12 when the automobile 10 is braked to generate electric power. This generated power is charged into the battery 16 via the inverter 22.

  The generator 20 is connected to the battery 16 via the inverter 24 and is connected to the motor 14 via the inverters 22 and 24, and supplies the electric power generated by being driven by the engine 18 to the motor 14 and the battery 16. To do. It is also possible to receive power from the battery 16 via the inverter 24 and operate the motor, thereby forcibly rotating the engine 18 (motoring).

  The two inverters 22 and 24 convert the DC power from the battery 16 into AC power and send it to the motor 14 and the generator 20, or conversely, convert the AC power from the motor 14 and the generator 20 into DC power. To the battery 16. And it is controlled by the control unit 50 described below, and the electric power transmitted between the motor 14, the battery 16, and the generator 20 is adjusted.

  The control unit 50 controls the motor 14, the engine 18, the generator 20, and the inverters 22 and 24. That is, the control unit 50 includes an engine controller 50a that mainly controls the operation of the engine 18, and a HEV controller 50b that mainly controls the inverters 22 and 24 to control the operation of the motor 14 and the generator 20. .

  As shown in the control system in FIG. 2, in addition to the signal from the battery controller 40 being input to the control unit 50, a vehicle speed sensor 52 for detecting the vehicle speed and the accelerator operation amount of the driver (accelerator pedal depression amount) An accelerator sensor 54 that detects the amount of braking, a brake sensor 56 that detects the amount of brake operation (the amount by which the brake pedal is depressed), an airflow sensor 58 that detects the intake flow rate of the engine 18, and the phase (angle) of the crankshaft 18a. At least signals from the crank angle sensor 62 to be detected and the cam angle sensor 64 to detect the phase (angle) of the camshaft 18b are input.

  In the illustrated example, the battery controller 40 is separate from the control unit 50, and includes a battery current sensor 42 that detects the current of the battery 16, a battery voltage sensor 44 that detects the voltage of the battery 16, and the temperature of the battery 16. Signals from the battery temperature sensor 46 to be detected are input, the SOC (charged state, remaining capacity) of the battery 16 and the magnitude of the electric load are calculated based on these signals, and output to the control unit 50.

  The control unit 50 controls the inverters 22 and 24 based on the various signals, thereby controlling the motor 14 and the generator 20 and also controlling the state of charge of the battery 16. The control unit 50 also controls the operation of the engine 18, more specifically, the fuel injection valve 18d and the spark plug 18e provided for each cylinder 18c.

  As an example, as shown in the map of FIG. 3, the control unit 50 performs ON / OFF control of the engine 18 based on the vehicle load and the SOC of the battery 16 to stop the operating engine 18 or stop the engine. 18 is restarted. The vehicle load is a load determined from the traveling state of the automobile 10 and the operating state of the electric load, and the control unit 50 uses the vehicle load sensor 52 or the accelerator sensor 54 as a signal related to the traveling state among the vehicle loads. Calculate based on.

  As shown in FIG. 3, when the vehicle load is large, for example, when the motor 14 is in a high output state in order to drive the automobile 10 at a high speed, or the electric load operates while consuming a large amount of electric power during traveling. In such a case, since there is a possibility that the battery 16 may be insufficiently supplied with power, the control unit 50 operates the engine 18 to generate power in the generator 20, and the generated power is supplied to the motor 14 via the inverters 22 and 24. Or supplied to the battery 16.

  Further, even when the SOC of the battery 16 is low, the control unit 50 operates the engine 18 in order to charge the battery 16. That is, the engine 18 is operated except when it is in a state in which it can sufficiently travel with only the electric power of the battery 16 (it can travel stably for a long time).

  It should be noted that the ON / OFF control of the engine 18 by the control unit 50, that is, the conditions for the automatic stop and restart, may be based on other factors such as the temperature of the engine coolant other than the vehicle load and the SOC of the battery 16. Good. For example, when the engine 18 is in a cold state (cooling water temperature is 50 degrees or less), the engine 18 is warmed up when the engine 18 is stopped based on the vehicle load or SOC (based on the map of FIG. 3). You may be allowed to drive to get on.

  Further, in this embodiment, the control unit 50 stops the operation of the engine 18 during braking of the automobile 10 and regenerates the kinetic energy associated with traveling by causing the motor 14 to generate electricity by the driving force from the wheels 12. The battery 16 is charged with the generated power.

(Control during regenerative braking)
Thus, the electric power generated by the power generation operation of the motor 14 generally increases in accordance with an increase in the braking force request to the automobile 10 (determined based on whether the brake pedal is stepped on or off, the vehicle speed, etc.) In such a case, the generated power may exceed the charging limit of the battery 16, and it is not preferable to send an overcurrent that exceeds the charging allowable current to the battery 16. By operating the motor and motoring the engine 18, excess generated power is consumed.

  However, the rotation of the engine 18 does not start immediately even by motoring, and there is a possibility that excessive generated power cannot be consumed while the engine speed is low at the initial stage of motoring. In this regard, as a feature of the present invention, in this embodiment, the efficiency of motor operation of the generator 20 for motoring is reduced until the engine speed reaches a preset speed at the initial stage of motoring. Thus, the power consumption is increased.

Embodiment 1
Below, with reference to FIG.4 and FIG.5, specific Embodiment 1 of the control procedure of the motor 14 at the time of regenerative braking and the generator 20 is described.

  First, in step S1 after the start in the flowchart shown in FIG. 4, it is determined whether or not to perform regenerative braking control based on the vehicle speed of the vehicle 10, signals from the accelerator sensor 54, the brake sensor 56, and the like. On the other hand, for example, if the brake pedal is depressed and a braking force request exceeding a predetermined value is generated, it is determined that regenerative braking control is to be performed (YES), and the process proceeds to step S2.

  In step S2, it is determined whether or not the generated power P_regen (hereinafter referred to as motor regenerative power P_regen) of the motor 14 that regenerates the driving force from the wheels 12 is smaller than the charging limit Pbat_lim of the battery 16, and YES. If there is, the process proceeds to step S3, and the operation efficiency ηmot of the motor 14 is set to the maximum efficiency ηmot_max, and the process returns. The battery charge limit Pbat_lim not only varies depending on the type of the battery 16 but also varies depending on the state of charge (SOC) thereof, and is specified based on the SOC calculated by the battery controller 40, for example.

  Then, regenerative braking control is started, and as shown at times t0 to t1 in the time chart of FIG. 5, a motor regenerative torque (control target value, hereinafter referred to as target motor regenerative torque) representing a braking force request is obtained. The motor regenerative power P_regen increases in response to the rise ((a) in the same figure) ((b) in the same figure), and the charging power of the battery 16 also increases ((f) in the same figure). During this time, the motor efficiency ηmot is set to the maximum efficiency ηmot_max (shown by a solid line in FIG. 5E), and the heat generation is minimized.

  When the motor regenerative power P_regen reaches the battery charge limit Pbat_lim at time t1, it is determined as NO in step S2, and the process proceeds to step S4. Here, it is determined whether or not the product obtained by multiplying the motor regenerative power P_regen by the minimum efficiency ηmot_min of the motor 14 is smaller than the battery charge limit Pbat_lim (ηmot × ηmot_min <Pbat_lim?). If this determination is YES, the process proceeds to step S5, and the efficiency ηmot of the power generation operation of the motor 14 is controlled (ηmot = Pbat_lim ÷ P_regen) so that the motor regenerative power P_regen becomes just the battery charge limit Pbat_lim, and the process returns. .

  Then, as shown at times t1 to t2 in FIG. 5, even if the target motor regenerative torque increases (FIG. 5A), the motor efficiency ηmot gradually decreases (FIG. 5E). The electric power P_regen is maintained at the battery charge limit Pbat_lim ((b) in the figure). Thus, when the motor efficiency ηmot decreases, the heat generation of the motor 14 gradually increases accordingly.

  If the target motor regenerative torque further increases, the motor regenerative power P_regen becomes equal to or higher than the battery charge limit Pbat_lim even when the motor efficiency ηmot is decreased to the minimum value (time t2 in FIG. 5 (e)) (FIG. 5). (b)). In this case, NO is determined in step S4, and the process proceeds to step S6, where the motor efficiency ηmot is set to the minimum efficiency ηmot_min, while the generator 20 is operated to start motoring of the engine 18.

  With the start of this engine motoring, the generator rotational speed ng (same as the rotational speed of the engine 18) starts to rise as shown at times t2 to t3 in FIG. 5 ((c) in FIG. 5). Excessive power is consumed due to the pumping work and mechanical loss associated therewith (hereinafter also referred to as waste power). The electric power thus discharged increases as the generator rotational speed ng increases as shown in FIG. 6D, but the rotation of the engine 18 does not start up immediately, and the pump work per hour is small while it is low. Therefore, the surplus generated power cannot be consumed.

  On the other hand, in the flow of FIG. 4, after confirming in step S7 that the current motor regenerative power P_regen is smaller than the maximum value P_regen_max that is the upper limit in the configuration (determination is YES), the process proceeds to step S8, as described above. It is determined whether or not the generator rotational speed ng that rises to a smaller value than the preset rotational speed ng_set. This set rotational speed ng_set is set in association with the lower limit of the rotational speed at which electric power can be efficiently consumed by motoring of the engine 18, and if the determination is YES with ng <ng_set, the motor operation of the generator 20 is performed. Power consumption is increased by reducing the efficiency.

  That is, in step S9, which has been determined as YES in step S8 as described above, the generator efficiency ηgen is lower than the maximum efficiency ηgen_max while the generator rotational speed ng is lower than the set rotational speed ng_set, and the generator The efficiency is set so as to gradually increase as the rotational speed ng increases. For example, the generator efficiency ng_trq (separately set in a map or the like) is multiplied by the generator rotational speed ng, and this is divided by the required power consumption Pdis (= P_regen−Pbat_lim). Determine ηgen and return.

  As a result of such control, the efficiency ηgen of the generator 20 increases as the rotational speed ng increases at time t2 to t3 in FIG. 5 (shown by a broken line in FIG. 5E), so that the surplus of the motor regenerative power P_regen is reduced. While consuming, the heat generation of the generator 20 can be minimized. When the generator rotational speed ng reaches the set rotational speed ng_set ((c) in the figure), it is determined NO in step S8 and the process proceeds to step S10.

  In this step S10, it is determined whether or not the generator rotational speed ng is larger than the rotational upper limit ng_max. The rotation upper limit ng_max is determined, for example, from the viewpoint of vibration, noise, reliability associated with motoring of the engine 18, and if ng ≦ ng_max and NO, there is room for further increasing the engine rotation and increasing power consumption. Therefore, the process proceeds to step S11, the generator efficiency ηgen is set to the maximum efficiency ηgen_max, and the process returns.

  That is, when the motoring rotational speed of the engine 18 reaches the set rotational speed ng_set and surplus power can be consumed by motoring, the generator efficiency ηgen is increased until it further increases and exceeds the rotational upper limit ng_max. Keep it at the highest level to minimize its fever.

  When the generator efficiency ηgen is maintained at the maximum efficiency ηgen_max and the time t3 to t4 elapses in FIG. 5 and the generator rotation speed ng exceeds the rotation upper limit ng_max ((c) in FIG. 5), the step S10 is performed. YES, that is, it is determined that the engine speed cannot be increased any more, and the process proceeds to step S12. Here, the generator efficiency ηgen is calculated by the same equation as in step S9 so that the engine rotation, that is, the generator rotation speed ng does not increase even if the motor regenerative power P_regen further increases.

  Subsequently, in step S13, it is determined whether or not the generator efficiency ηgen calculated as described above is smaller than the minimum efficiency ηgen_min (ηgen <ηgen_min). If NO, the process returns, whereas if it is smaller than the minimum efficiency ηgen_min, In step S14, the minimum efficiency ηgen_min is set and the process returns. As a result, as shown at times t4 to t5 in FIG. 5, the generator efficiency ηgen decreases as the motor regenerative power P_regen increases ((b) in FIG. 5) ((e) in FIG. 5). The motoring rotation speed, that is, the generator rotation speed ng is maintained at the rotation upper limit ng_max ((c) in the figure).

  When the generator efficiency ηgen becomes the minimum efficiency ηgen_min at time t5, the efficiency cannot be lowered any further, and the motor regenerative power P_regen at this time becomes its maximum value P_regen_max. Therefore, after that, it is determined as NO in step S7 and the process proceeds to step S15, and the motor regenerative power P_regen does not increase ((b) in the figure), so the generator efficiency ηgen is maintained at the minimum efficiency ηgen_min. become.

  The entire flow of FIG. 4 corresponds to the first step of regenerating kinetic energy by causing the motor 14 to generate electricity during braking of the automobile 10 and the second step of charging the battery 16 thereby, this embodiment. Then, as shown in FIGS. 5A and 5B, the motor regenerative power P_regen increases with an increase in the braking force request (target motor regenerative torque).

  Steps S4 and S5 correspond to the sixth step of reducing the efficiency ηmot of the power generation operation of the motor 14 when the motor regenerative power P_regen becomes equal to or higher than the charge limit P_bat_lim. If the reduced motor efficiency ηmot becomes the minimum efficiency, this corresponds to the third step in which the engine 18 is motored by the motor operation of the generator 20 to consume surplus power.

  Further, steps S8 and S9 correspond to the fourth step in which the generator efficiency η_gen is lower than its maximum value until the engine speed (= generator speed ng) reaches the set speed ng_set by motoring. In the fourth step, the generator efficiency η_gen is increased as the generator rotational speed ng increases.

  Furthermore, steps S10 to 14 correspond to the fifth step in which the generator efficiency η_gen is maintained at its highest value until the generator rotational speed ng reaches its upper rotational speed limit ng_max, and when the rotational upper limit ng_max is exceeded, the generator efficiency η_gen is decreased again. doing. In step S10, the process may proceed to step S12 not only when the generator rotational speed ng reaches the rotation upper limit ng_max, but also when the increase width (ΔP_regen) of the motor regenerative power P_regen is greater than or equal to a predetermined value, for example. .

  The control procedure at the time of regenerative braking as described above is executed by the control unit 50. In this sense, the control unit 50 has a software program mode and the motor regenerative control according to the claims. Means, charging control means, engine / motoring control means, motor efficiency control means, and generator efficiency control means.

  Therefore, according to the control apparatus for a hybrid vehicle according to the first embodiment, first, the motor 14 is operated to generate electricity when the vehicle 10 is decelerated to regenerate kinetic energy, thereby charging the battery 16 and the generated power, that is, If the motor regenerative power P_regen is equal to or greater than the charging limit Pbat_lim of the battery 16, the engine 18 is motored by the motor operation of the generator 20, and surplus power is consumed.

  In addition, by setting the motor operation efficiency ηgen of the generator 20 to be lower than the maximum efficiency until the engine speed rises at the initial stage of the motoring and reaches the set speed ng_set, the engine speed is reduced. Can use up the surplus power.

  Further, in this embodiment, even if the motor regenerative power P_regen exceeds the charging limit Pbat_lim, the engine motoring is not started immediately, and the power generation efficiency ηmot of the motor 14 is decreased for a while to reduce the motor regeneration. The power P_regen is suppressed. This is for preventing the motor 10 from being repeatedly started and stopped in consideration of the fact that the motor vehicle 10 again shifts to the acceleration operation by the motor drive after a short deceleration traveling.

  Further, in this embodiment, when the motoring is performed, the generator rotational speed ng (engine rotational speed) does not exceed the upper rotational speed limit ng_max, thereby preventing excessive vibration, noise, etc., and causing the passenger to feel uncomfortable. And the decline in reliability is suppressed.

Embodiment 2
6 and 7 show a control procedure during regenerative braking according to the second embodiment. The second embodiment is characterized by the control of the operating efficiency ηmot and ηgen of the motor 14 and the generator 20 after the engine rotation has increased to some extent by motoring. Except for this point, the embodiment 2 is shown in FIG. Since the flow of the second embodiment is the same as that of the first embodiment (see FIG. 4), the same control steps are denoted by the same reference numerals and description thereof is omitted.

  That is, as described above, according to the control device of the present invention, the rotational speed of the engine 18 that is motored during regenerative braking, that is, the generator rotational speed ng is equal to or higher than the set rotational speed ng_set, so that the power can be sufficiently discharged. For example, the generator efficiency ηgen is increased to the maximum efficiency ηgen_max, but as shown at times t3 to t4 in the time chart of FIG. 7, in the second embodiment, the generator rotational speed ng is increased ((c) in FIG. 7). Accordingly, the motor efficiency ηmot is also increased ((e) in the same figure) (seventh step), whereby the heat generation of the motor 14 can be suppressed.

  In addition, if the generator speed ng that rises reaches the rotation upper limit ng_max (time t5: FIG. 5 (c)), the generator efficiency ηgen is reduced again as in the first embodiment (fifth step). When the generator efficiency ηgen to be reduced becomes the minimum efficiency ηgen_min (time t6: FIG. 5E), the motor efficiency ηmot is reduced again as the motor regenerative power P_regen increases. (Eighth step).

  More specifically, as shown in the flowchart of FIG. 6, first, the same control procedure as that in the first embodiment is executed from step S1 to S4, and in step S60, which is determined to be NO in step S4, step S6 is performed. In contrast to this, the motor efficiency of the engine 18 is started by operating the generator 20 without setting the motor efficiency ηmot.

  In subsequent steps S7 to S9, the motor efficiency ηmot is once reduced, and the generator efficiency ηgen is maintained at the maximum efficiency ηgen_max in step S11 until it is determined in step S10 that the rotation upper limit ng_max has been exceeded. On the other hand, in step S111, the motor efficiency ηmot is increased by the same calculation as in step S5, and it is determined whether the calculated motor efficiency ηmot is larger than the maximum efficiency ηmot_max (step S112). If the maximum efficiency ηmot_max is exceeded, the maximum efficiency ηmot_max is set (step S113), and the process returns.

  Then, when the generator speed ng exceeds the rotation upper limit ng_max at time t5 shown in FIG. 7 while maintaining not only the generator efficiency ηgen but also the motor efficiency ηmot (FIG. 7 (c)), In step S10, it is determined as YES, and the process proceeds to step S12, where the generator efficiency ηgen is set so that the engine rotation, that is, the generator rotational speed ng does not increase even if the motor regenerative power P_regen further increases. As a result, as shown at times t5 to t6 in FIG. 7, the generator efficiency ηgen decreases as the motor regenerative power P_regen increases ((b) in FIG. 7) ((e) in FIG. 7). The motoring rotational speed of the engine 18, that is, the generator rotational speed ng is maintained at the upper rotational speed limit ng_max ((c) in the figure).

  If the generator efficiency ηgen becomes the minimum efficiency ηgen_min at time t6, the generator efficiency ηgen cannot be further reduced. In this case, in step S141, the motor efficiency ηmot is calculated by the same equation as in steps S5 and S111. It is determined whether or not the motor efficiency ηmot thus calculated is smaller than the minimum efficiency ηmot_min (step S142). If NO, the process returns. If it is smaller than the minimum efficiency ηmot_min, the minimum efficiency is obtained. It sets to ηmot_min (step S143) and returns.

Embodiment 3
Next, FIG.8 and FIG.9 shows the control procedure at the time of the regenerative braking based on Embodiment 3. FIG. In the second embodiment, when the motor regenerative power P_regen becomes equal to or higher than the charging limit Pbat_lim, the motoring of the engine 18 is started immediately without decreasing the motor efficiency ηmot.

  Except this point, the flow of the third embodiment shown in FIG. 8 is the same as that of the second embodiment (see FIG. 6). In short, the flow of FIG. 8 is obtained by deleting steps S4 and S5 and steps S111 to S113 from the flow of FIG.

  According to the third embodiment, as shown at time t1 in the time chart of FIG. 9, when the motor regenerative power P_regen becomes equal to or higher than the battery charge limit Pbat_lim (NO in step S2), the motoring of the engine 18 is immediately performed. It starts (step S60).

  Therefore, according to the third embodiment, since the operation efficiency of the motor 14 is not lowered at the initial stage of regenerative braking, the heat generation can be minimized. Immediately after regenerative braking, motoring of the engine 18 is started, and vibration and noise become large. However, for example, when the vehicle 10 decelerates like when running on a winding road, it often shifts to acceleration operation immediately. It is suitable when it is preferable to keep the engine speed high to some extent. It is preferable to properly use the control as in the first and second embodiments and the control as in the third embodiment according to the traveling state of the automobile 10.

  Note that the control device for a hybrid vehicle according to the present invention is not limited to the above-described embodiment, but includes other various configurations. For example, the hybrid vehicle 10 to which the present invention is applied is not limited to a so-called series system, and may be a parallel system or a series / parallel system.

  As described above, according to the hybrid vehicle control method and the like according to the present invention, the surplus power can be consumed and the battery is excessively charged until the engine starts motoring during regenerative braking. Since it is not charged, it is also suitable for passenger cars.

1 is an overall configuration diagram of a hybrid vehicle according to an embodiment of the present invention. It is a figure which shows the control system. It is a figure which shows an example of the control map which divided the operating area | region of the engine into two. It is a flowchart figure which shows the control procedure at the time of regeneration control of Embodiment 1. FIG. It is a time chart which shows the motor regeneration torque at the time of the same regeneration control, motor regeneration electric power, generator rotation speed, waste electric power, operation efficiency of a motor and a generator, and change of battery electric power. FIG. 6 is a view corresponding to FIG. 4 according to the second embodiment. FIG. 6 is a view corresponding to FIG. FIG. 6 is a view corresponding to FIG. 4 according to the third embodiment. FIG. 6 is a view corresponding to FIG.

10 Hybrid car 14 Motor (drive motor)
16 Battery 18 Engine 20 Generator 50 Control unit (motor regeneration control means, charge control means, engine motoring control means, motor efficiency control means, generator efficiency control means)

Claims (12)

A first step of regenerating kinetic energy by causing the drive motor to generate electricity during braking of the automobile, a second step of charging the battery with the generated power, and when the generated power is greater than or equal to a predetermined charge limit of the battery, A third step of activating a generator coupled to the engine to consume excess power and controlling the hybrid vehicle,
In the third step, when the engine speed increases due to the motor operation of the generator, there is a fourth step in which the operation efficiency of the generator is lower than its maximum efficiency until it reaches the set speed. ,
A control method of a hybrid vehicle characterized by the above. In the fourth step, the generator's operating efficiency is increased as the engine speed increases,
The hybrid vehicle control method according to claim 1, further comprising a fifth step of reducing the operation efficiency of the generator again when the engine speed reaches a predetermined speed higher than the set speed. In the first step, the generated power of the drive motor is controlled according to the braking force request,
A sixth step of delaying the start of the third step for a predetermined period and reducing the efficiency of the power generation operation of the drive motor when the generated power increases in response to the increase in the braking force request and exceeds the charging limit. The control method of the hybrid vehicle in any one of Claim 1 or 2 which has these. The hybrid vehicle control method according to claim 3, wherein in the sixth step, the operation efficiency of the drive motor is reduced so that the generated power becomes the charge limit . In the fourth step, after increasing the operating efficiency of the generator to the maximum efficiency, the seventh step of increasing the power generation operating efficiency of the drive motor according to the increase in the engine speed,
After reducing the generator operating efficiency to a predetermined lower limit in the fifth step, when the braking force request further increases, there is an eighth step of reducing the power generating operating efficiency of the driving motor accordingly. The method for controlling a hybrid vehicle according to claim 4. The fifth step includes a ninth step of reducing the power generation operation efficiency of the driving motor in response to an increase in the braking force requirement after the generator operation efficiency is reduced to a predetermined lower limit value in the fifth step. 3. A control method for a hybrid vehicle according to 2. Motor regeneration control means for regenerating kinetic energy by driving the drive motor during braking of the automobile, charging control means for charging the battery with the generated power, and when the generated power is greater than or equal to a predetermined charge limit of the battery An engine motoring control means for consuming surplus power by operating a generator connected to the engine, and a control device for a hybrid vehicle,
Generator efficiency control means for lowering the operating efficiency of the generator below its maximum efficiency when the engine speed increases due to the motor operation of the generator until it reaches the set speed. A control device for a hybrid vehicle.   The generator efficiency control means increases the operating efficiency of the generator as the engine speed reaches the set speed, and increases the operating efficiency of the generator if the engine speed reaches a predetermined speed higher than the set speed. The control apparatus for a hybrid vehicle according to claim 7, wherein The motor regeneration control means controls the generated power of the driving motor in response to the braking force request.
The engine / motoring control means is configured to start motor operation control of the generator after elapse of a predetermined delay period when the generated power increases in response to an increase in the braking force request and exceeds a charging limit.
9. The hybrid vehicle control device according to claim 7, further comprising motor efficiency control means for reducing the efficiency of the power generation operation of the drive motor during at least the delay period. The control apparatus for a hybrid vehicle according to claim 9, wherein the motor efficiency control means reduces the operation efficiency of the drive motor so that the generated power becomes the charge limit during the delay period. The motor efficiency control means increases the power generation operation efficiency of the drive motor in accordance with the increase in engine speed after the generator operation efficiency is increased to the maximum efficiency by the generator efficiency control means, while the generator efficiency control means 11. The hybrid according to claim 10, wherein when the braking force demand further increases after the operating efficiency of the motor is reduced to a predetermined lower limit value , the power generation operating efficiency of the drive motor is reduced accordingly. Automotive control device. Motor efficiency control means is provided for reducing the power generation operation efficiency of the drive motor in response to a further increase in braking force demand after the generator operation efficiency is reduced to a predetermined lower limit by the generator efficiency control means. The hybrid vehicle control device according to claim 8.

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