JP3047737B2 - Control device for series hybrid vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device mounted on a series hybrid vehicle.

[0002]

2. Description of the Related Art As a system configuration of an electric vehicle, a hybrid vehicle equipped with an engine in addition to a traveling motor is known. For example, a series hybrid vehicle is known as a hybrid vehicle. In a series hybrid vehicle, a generator is driven by an engine, and a generated output of the generator is supplied as driving power to a traveling motor and supplied as charging power to a battery. The traveling motor is driven not only by the power output of the generator but also by the discharged power of the battery, and charges the battery with the regenerated power during regeneration.
Therefore, the energy balance of a series hybrid vehicle is exclusively the driving of the motor by the output of the generator, the charging of the battery by the output of the generator, the driving of the motor by the output of the battery, and the charging of the battery by the regenerative power of the motor. It is determined by four types of energy supply paths. Japanese Patent Laying-Open No. 5-328523 discloses a configuration for controlling the power generation output of a generator for charging a battery.

[0003]

A battery that can be mounted on a series hybrid vehicle, such as a lead battery, has a state of charge (SO
When the state of charge (C) is extremely reduced or becomes overcharged, the life is shortened. That is, in order to secure the life of the battery, it is preferable to target-control the SOC to a predetermined range, for example, a range of 70 to 90% of the full charge. On the other hand, in order to keep the fuel and emission of the engine in a good state, it is preferable that the engine be operated in a region where the number of rotations is good, and that the number of rotations be kept as small as possible.

Accordingly, in controlling the power output of the generator, first, a power output that can substantially cover the output of the traveling motor is generated (that is, the power is generated so as not to be affected by the charge / discharge efficiency of the battery). Output is directly supplied to the traction motor to improve energy efficiency); second, a power generation output capable of maintaining the SOC of the battery within a predetermined range is generated; Of these, those that fluctuate greatly in a short time or those that exceed the maximum output value of the generator need to be covered by a battery.

[0005] When such control is performed, for example, when the vehicle is stopped in a state where the SOC of the battery is low, the engine speed is maintained at a high speed even though the vehicle is stopped. This is because the output of the generator, which is the load of the engine, is controlled to a large value to recover the capacity of the battery, and the engine speed is increased. Therefore, if the power generation output control is performed with a target of a large value when the SOC is low or the like, the engine speed becomes a high speed regardless of the stop state of the vehicle. this is,
In a vehicle driven only by the engine, the engine speed is significantly different from a low speed (idle speed) when the vehicle stops. Therefore, for a pilot who is accustomed to the engine-only vehicle, it is uncomfortable that the engine speed of the series hybrid vehicle is high even when the engine is stopped. Of course, if the engine speed is high while the vehicle is stopped, the noise inside the vehicle will be loud and the discomfort will be felt.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to eliminate uncomfortable feeling when a vehicle stops and reduce noise by controlling charging of a battery. It is another object of the present invention to bring the feeling when the vehicle is stopped closer to a vehicle having only an engine. It is a further object of the present invention to quickly charge a battery immediately after vehicle restart. An object of the present invention is to secure the SOC of the battery.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an engine in which the number of revolutions decreases as the load is reduced, and a power generation output corresponding to the load which can be controlled by the engine. Generator, a battery that can be charged by the power output of the generator, and a traveling motor that can be driven by the power output of the generator and the discharge output of the battery, in a control device mounted on a series hybrid vehicle, Power generation control means for setting a target according to the power consumed as a vehicle and controlling the power generation output of the generator, stop detection means for detecting that the series hybrid vehicle on which the vehicle is mounted is stopped, and when the stop is detected A rotation speed reducing means for changing the target to a lower value.

The present invention is also characterized in that the rotation speed reducing means changes the above target so that the rotation speed of the engine becomes a uniform idle rotation speed.

The present invention further provides a running restart detecting means for detecting that the series hybrid vehicle on which the vehicle is mounted has restarted running, and when the restart of running is detected, the target is set higher for a predetermined time. Rotation speed increasing means for changing the rotation speed to a value.

[0010] The present invention is characterized by comprising charging securing means for prohibiting the change of the target by the rotational speed reducing means when the SOC of the battery has dropped to below a predetermined level.

[0011]

In the present invention, the control target of the power generation output is determined according to the power consumed as the vehicle, and the power generation output of the generator is controlled according to the determined target. At this time, if it is detected that the mounted series hybrid vehicle is stopped, the control target of the power generation output is changed to a lower value, and the control is performed according to the changed target. Here, the generator is the load of the engine, and the rotation speed of the engine decreases as the load is reduced. Therefore, if the control is performed according to the changed target, the load on the engine is reduced, resulting in a lower rotation speed. As described above, when the series hybrid vehicle to be mounted is stopped, the number of revolutions of the engine is reduced, so that a sense of discomfort due to the high engine revolution when the vehicle is stopped is reduced, and noise is also reduced.

Further, in the present invention, the control target of the power generation output is changed so that the engine speed becomes the same idle speed when the mounted series hybrid vehicle is stopped. Therefore, a feeling exactly the same as that of a vehicle driven only by the engine is realized. Further, the engine speed does not fluctuate at the time of stoppage, so that the feeling is also good in that respect.

When the control target of the power generation output is reduced as described above, the energy balance of the battery is temporarily biased toward the discharging side. In the present invention, in order to overcome such a situation,
When the mounted series hybrid vehicle resumes running, the control target of the power generation output is changed to a higher value for a predetermined time. That is, the decrease in the power generation output during the stop period is compensated for by the increase in the power generation output immediately after the vehicle restarts.

In the present invention, when the SOC of the battery has dropped below a predetermined level, change of the target by the rotation speed reducing means is prohibited. That is, since it is not preferable to reduce the power generation output and suppress charging in a state where the SOC of the battery is lowered in terms of extending the life of the battery, the target control of the power generation output according to the SOC is continued. Is done.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a system configuration suitable for each embodiment of the present invention. In the system shown in FIG. 1, the driving power of the traveling motor 10 is covered by the discharge power of the battery 12 and the power output of the generator 14.
Is a series hybrid vehicle driven by an engine 16.

The traveling motor 10 is a three-phase AC motor, and its driving power is supplied from a battery 12 and a generator 14 via an inverter 18. The inverter 18 is connected to the battery 1
2 and the output of the generator 14
This is means for converting into three-phase AC power under the control of U20. The three-phase AC power obtained by the inverter 18 is supplied to the motor 10. When the motor 10 is driven by this electric power, its mechanical output is transmitted through the reduction gear 22 to the driving wheels 24.
Is transmitted to When an AC generator is used as the generator 14, a rectifier is provided at the subsequent stage.

The EV-ECU 20 controls the inverter 18 so that a necessary output can be obtained from the motor 10. For example, when the vehicle operator depresses the accelerator pedal, the EV-ECU 20 calculates a torque command value based on the depression amount of the accelerator pedal. EV-ECU 20
The calculated torque command value and the rotation speed of the motor 10 detected by the rotation sensor 26 (hereinafter referred to as the motor rotation speed)
Based on N _M, and outputs a current command to the inverter 18, the vector control of the current of the motor 10. Thus, an output corresponding to the amount of depression of the accelerator pedal is obtained from the motor 10. Similarly, when the vehicle operator depresses the brake pedal, the output torque related to the regenerative braking is generated.

The engine 16 and the generator 14 are EFI-
It is controlled by the ECU 28 and the generator ECU 30.
Generator ECU30 is, numerical values of SOC or the like to be detected by the battery ECU 32, based on the average output P _M of the motor 10 to be broadcast from the EV-ECU 20, so that the driving of the motor 10, the request of the charging of the battery 12 are satisfied , The power generation output command P _GEN is determined. The generator ECU 30 controls the power output of the generator 14 with the determined power output command P _GEN as a target, and controls the starter 34 when the engine 16 is started. The EFI-ECU 28 determines the EF of the engine 16.
An I (fuel injection device) 36 is controlled to detect a rotation speed N _E ^* of the engine 16 (hereinafter, referred to as an engine rotation speed) and to return to the generator ECU 30.

The engine 16 used in FIG.
Is an engine driven by a WOT (wide open throttle) in principle in order to secure good fuel economy and maintain low emissions. That is, the throttle 38 of the engine 16 is maintained in a fully open state in principle. Therefore, when the load of the engine 16 is determined, the rotation speed is uniquely determined, and when the power generation output of the generator 14 increases, the engine 1
The load of No. 6 increases, and its rotation speed increases. The power output of the generator 14 can be controlled by the field current _If . Therefore, the generator ECU30 is when controlling the power output of the generator 14, firstly over the designated generation output command P _GEN, the determined power generation output command P _GEN reference to the relationship shown in FIG. 2, for example, an engine The rotational speed command _NE is determined. Generator ECU30, based on the determined engine speed command N _E, and while monitoring the engine rotation speed N _E ^* fed back from the EFI-ECU 28, and controls the field current I _f of the generator 14, thereby The power generation output of the generator 14 is controlled to the value of the power generation output command _PGEN . Generator ECU3
0 indicates that the throttle 38 of the engine 16 is normally kept fully open. However, when high efficiency can be obtained when the throttle 38 is not fully opened, the command relating to the opening of the throttle 38, that is, the engine throttle opening command θ _th is appropriately determined. , Throttle 38
Control. In the example of FIG. 2, power output throttle 38 in the region of 6~18kW is controlled to fully open, the following regions 6 kW ^* rotational speed N _E of the engine 16 is 1200rp
The throttle 38 is controlled to be m.

FIG. 3 shows a flow of the operation of the generator ECU 30 according to the first embodiment of the present invention.

In this embodiment, when the operator turns on the key switch, the generator ECU 30 executes initial processing, that is, resets various flags and counters in response to the key switch (100). The generator ECU 30 then
A signal is supplied to the starter 34 to start the engine 16 (102).

After the engine 16 is started, the generator ECU
30, a first signal indicative of the average output P _M of the motor 10 E
A signal indicating the SOC of the battery 12 is input from the V-ECU 20 from the battery ECU 32, and a power generation output command P _GEN is determined by calculation based on these so as to satisfy the requirements of driving the motor 10 and charging the battery 12 ( 1
04). The generator ECU 30 determines the determined power generation output command P
The engine speed command N _E and engine throttle opening command theta _th for realizing _GEN, determined based on the relationship of FIG. 2 (106).

Generator ECU 30 converts the SOC input from battery ECU 32 to a predetermined SOC decrease determination threshold SOC.
Compare with _MIN (108). At that time, SOC <SOC
If it is _MIN , it can be considered that the SOC of the battery 12 has dropped, so the generator ECU 30 executes step 112 via step 110, and executes step 112.
Each command determined in step 06 is output. That is, the field current I _f, which corresponds to the determined engine speed command N _E supplied to the generator 14, and controls the engine throttle opening command theta _th determining the degree of opening of the throttle 38. If the key switch is not turned off at this time, the generator ECU 3
0 continuously executes the processing after step 104 (11
4) If it is off, a predetermined end process is executed to end the operation (116).

Since the power generation output of the power generator 14 is controlled based on the SOC and the like, normally, SOC ≧ SOC _MIN is satisfied in step 108. In this case, the generator ECU30 compares the absolute value of the motor rotational speed N _M and a predetermined stop decision threshold value N _STOP (118). The stop determination threshold N _STOP is set to a value of about 2 km / h in terms of vehicle speed. Incidentally, in the system configuration of FIG. 1 because it is not the clutch, the transmission or the like is provided between the motor 10 and the drive wheels 24, it is possible to handle the motor rotational speed N _M as a vehicle speed.

When the vehicle is running, step 1
At | 18, | N _M | ≧ N _STOP holds. in this case,
Generator ECU 30 executes step 120. In step 120, generator ECU 30 determines whether or not the vehicle operator has depressed the accelerator pedal. When the accelerator is depressed (on in the figure), the generator ECU 30 determines whether or not a later-described stop flag f is 1 (12).
2). If the vehicle has not yet stopped after execution of step 100 or 110, the operation of the generator ECU 30 proceeds to step 112 because the stop flag is 0. When the accelerator is not depressed (off in the figure), the generator EC
The operation of U30 immediately proceeds to step 112.

Thereafter, when the vehicle decelerates and substantially stops, in step 118, | N _M | <N _STOP is established. In this case, generator ECU 30 determines in step 106
Newly set to the engine rotation speed command N _E and the results multiplied by α engine speed command change coefficient determined engine speed command N _E at (124). This α is 0 <α <
Therefore, the engine speed command _NE is reduced and corrected in step 124. Generator ECU3
0 compares the engine speed command N _E with the engine idle speed N _I (126).
_E is sets the engine idle speed N _I of the engine speed command N _E when less than the engine idle speed N _I (128). That is, the engine speed command N
The lower limit of _E and engine idle speed N _I. Generator ECU 30 sets 1 to stop flag f (130),
One is added to the stop time counter K (132). Generator ECU30, the step 112 reduced corrected engine speed command N _E by the engine speed command change coefficient α
Output.

Therefore, in this embodiment, when the vehicle stops, the engine speed N _E ^* decreases. That is, when the field current I _f that corresponds to the reduced engine speed command N _E in step 124 or 128 is supplied to the generator 14, the generator output SOC of power and the battery 12 necessary for driving the motor 10 Is smaller than the sum of the electric power necessary for the management and maintenance of the engine 16. As a result, the load on the engine 16 is reduced, and the rotational speed N _E ^* is reduced. As a result, a sense of discomfort for the driver is reduced and noise is also reduced.

Thereafter, if the key switch has not been turned off and the vehicle has been stopped, the process proceeds to steps 124 to 124.
132 is repeatedly executed. At some point, for example, when the driver steps on the accelerator and the vehicle starts running, step 118
| N _M | ≧ N _STOP holds. In this case, step 122 is executed after step 120. Step 1
Since the stop flag to be determined in 22 is set to 1 when step 130 was executed last time, the operation of the generator ECU 30 proceeds to step 134.

In step 134, the generator ECU 30
Is the stop time determination threshold K
_It is determined whether or not the value has exceeded _MAX . When the value of the stop time counter K is less than the stop time determination threshold value K _MAX , it can be considered that the stop time elapsed before the vehicle starts running is relatively short. If the value is equal to or greater than the stop time determination threshold value K _MAX ,
It can be considered that the stop time elapsed before the vehicle starts running is relatively long. If the stop time is short, step 110 is executed, and the stop flag f, the stop time counter K, and the later-described engine speed increase time counter J are reset to zero.

If the stop time is long, the generator ECU 3
0, multiplied by the engine speed command change coefficient β (β> 1) to the engine speed command N _E, increases corrects the engine speed command N _E (136). If the result engine speed command N _E of the correction has reached a predetermined engine speed maximum value N _EMAX (138), the generator ECU30 limits the engine rotation speed command N _E of the engine speed maximum value N _EMAX ( 1
40). The engine speed command N thus obtained
_E is output at step 112 through step 142 and the like, and the power generation output of the generator 14 increases. This control is performed to compensate for the discharge of the battery 12 caused by the reduction of the power generation output during the stop. Generator EC
U30 adds 1 to the engine speed increase time counter J after executing step 138 or 140 in order to manage and limit the period during which the power generation output of the generator 14 is increased (14).
2) Until the value of the engine speed increase time counter J reaches the predetermined engine speed increase time determination threshold value _JMAX , the routine that passes through step 136 and the like is repeatedly executed (144), and the engine speed increase time is set. After the value of the counter J reaches the predetermined engine speed increase time determination threshold value _JMAX , step 110 is executed.

When the vehicle is stopped, step 124 and the like are executed as described above, and the
Power generation output decreases. In this state, the SOC of the battery 12 decreases when the electric auxiliary equipment that receives power supply from the battery 12, such as an air conditioner, continues to operate. Therefore, in this embodiment, step 108 is executed to prevent the SOC from decreasing . That is, when SOC <SOC _MIN is satisfied, step 124 and the like are not executed, and the same control as when the vehicle travels based on the power generation output command _PGEN determined in step 104 is executed.

FIG. 4 shows a part of the operation of the generator ECU 30 in the second embodiment of the present invention. In this embodiment, in step 118, | N _M | <N
If it is determined that the _STOP, engine Al dollar rotational speed N _I is set to the engine rotation speed command N _E (146). After execution of step 146, the process moves to step 130. Accordingly, in this embodiment, since the fact that the engine speed N _E ^* is controlled to the engine idle speed N _I when the vehicle is stopped, exactly the same feeling as the vehicle that is driven only by the engine can get. Further, in this embodiment, the vehicle value of engine speed command N _E which is output in step 112 at the time of stopping does not depend on the value of the engine speed command N _E which is determined in step 106. Thus, for example, even if the SOC is consumed power of the battery 12 of the battery 12 is lowered by the electrical auxiliary machine of the vehicle, without the value change of the engine speed command N _E which is output in step 112, Also in this aspect, the uncomfortable feeling of the vehicle operator can be reduced.

FIG. 5 shows a part of the operation of the generator ECU 30 in the third embodiment of the present invention. In this embodiment, although not shown, step 108 described above is omitted instead of | N _M | <
If it is determined that N _STOP , step 148 is executed. In step 148, generator ECU 30
The value of the stop time counter K is compared with a predetermined SOC decrease determination threshold value K _SOC . As a result of this comparison, if K ≧ K _SOC , the operation of step 112 is immediately executed without executing the operation of step 124. Therefore, in this embodiment, the degree of decrease in the SOC of the battery 12 is determined without detecting and determining the SOC of the battery 12.

[0035] In the above description, it is conducted in accordance with the determination of whether the vehicle is stationary motor rotational speed N _M. Such processing is possible because the output shaft of the motor 10 is connected to the drive wheels 24 without passing through a transmission or the like. When the reduction gear between the motor 10 and the drive wheel 24 is interposed, or performs the processing that takes into account the reduction ratio applied to the motor rotational speed N _M, or based on the vehicle speed detected by the vehicle speed sensor Preferably, a treatment is performed. The determination as to whether or not the vehicle is stopped can also be performed using information other than these pieces of information. For example, to monitor the average output P _M of the motor 10, or EV-
The torque command determined by the ECU 20 may be monitored.

[0036]

As described above, according to the present invention,
When the series hybrid vehicle to be mounted is stopped, the control target of the power generation output is changed to a lower value, and the engine speed is reduced, so that discomfort caused by high engine rotation at stop can be reduced. A series hybrid vehicle with low noise can be realized.

Further, according to the present invention, the control target of the power generation output is changed so that the rotation speed of the engine becomes the idle rotation speed when the mounted series hybrid vehicle is stopped. The feeling exactly the same as that of a driven vehicle can be realized. Also,
Since the rotation speed of the engine does not fluctuate at the time of stop, the feeling is also good in that respect.

According to the present invention, the control target of the power generation output is changed to a higher value for a predetermined time when the mounted series hybrid vehicle resumes running. The reduction is compensated for by an increase in the power generation output immediately after the restart of traveling, and the bias of the energy balance of the battery can be prevented.

According to the present invention, when the SOC of the battery is reduced to less than a predetermined level, the change of the target by the rotation speed reducing means is prohibited.
There power output without charge is reduced can be suppressed in a state in which reduced, it is possible to maintain the SOC of the battery to a suitable range.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a system configuration suitable for first to third embodiments of the present invention.

FIG. 2 is a diagram illustrating an example of a relationship between a power generation output command and an engine speed command.

FIG. 3 is a flowchart illustrating an operation of a generator ECU according to the first embodiment of the present invention.

FIG. 4 is a flowchart showing a main part of an operation of a generator ECU according to a second embodiment of the present invention.

FIG. 5 is a flowchart showing a main part of the operation of a generator ECU according to a third embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 10 motor 12 battery 14 generator 16 engine 30 generator ECU f stop flag _If field current of generator J engine speed increase time counter J _MAX engine speed increase time determination threshold K stop time counter K _MAX stop time charge state determination threshold value N _E engine speed command N _EMAX engine speed maximum value N _I engine idle speed N _M motor rotational speed N _sTOP stop decision threshold value P _GEN generator output command P _M average motor output SOC cell SOC _MIN , K _SOC SOC decrease judgment threshold α, β Engine speed command change coefficient θ _th Engine throttle opening command

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B60L 11/12 B60L 11/10 F02B 61/00 F02D 29/06

Claims (4)

(57) [Claims] 1. An engine whose rotation speed decreases as a load is reduced, a generator driven by the engine capable of controlling a power generation output corresponding to the load, a battery chargeable by the power generation output of the generator, A control device mounted on a series hybrid vehicle having a driving motor that can be driven by a generator output and a battery discharge output, sets a target according to the power consumed as a vehicle and controls the generator output. a power generation control means for the stop detecting means for series hybrid vehicle according to the mounting is detected to be stopped, when the stop is detected, the rotation speed reducing means for changing the target to a lower value, mounted The series hybrid vehicle according to
Running restart detecting means for detecting the restart of the vehicle, and when the restart of running is detected,
A rotation speed increasing means for changing the target to a higher value . 2. The control device according to claim 1, wherein when the state of charge of the battery is reduced to less than a predetermined level,
Charge securing hand that prohibits changing the target by the rotational speed reduction means
Control device characterized by comprising a stage. 3. An engine in which the number of revolutions decreases as the load is reduced.
Engine and the power output corresponding to the load can be controlled and
Generator driven by the
Rechargeable battery, generator output and battery discharge
A driving motor that can be driven by an output.
The control device mounted on the hybrid vehicle sets a target in accordance with the power consumed by the vehicle and starts the generator.
Power generation control means for controlling the power output and the series hybrid vehicle to be mounted must be stopped
Stop detection means for detecting the above, and if the stop is detected, change the above target to a lower value
Rotation speed reducing means, and when the state of charge of the battery is reduced to less than a predetermined degree,
Charge securing hand that prohibits changing the target by the rotational speed reduction means
Control device characterized by comprising a stage. 4. The control device according to claim 1, wherein the rotation speed reducing means controls the rotation speed of the engine to be equal to the idle rotation speed.
A control device for changing the target so that the number of turns is equal to the number of turns .