JP3214285B2 - Power generation control method and device in series hybrid vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for controlling power generation in a series hybrid vehicle (SHV), and more particularly to control of the engine speed.

[0002]

2. Description of the Related Art FIG. 3 schematically shows a so-called SHV system configuration. In this system, a three-phase AC motor 10 is used as a motor for driving a vehicle.
From the battery 14 or the engine-driven generator 16. Further, the battery 14 can be charged by the power output from the engine drive generator 16 in addition to the power from the external power supply (not shown) and the regenerative power from the motor 10.

[0005] As a control device, an EV ECU 18 and a generator ECU 20 are provided. The EV ECU 18 is
The output torque of the motor 10 is controlled by controlling the operation of the inverter 12 according to the depression of the accelerator pedal or the brake pedal by the vehicle operator. That is, E
VECU18, based on the amount of depression of the accelerator pedal and a brake pedal, also with reference to the rotational speed N _M of the motor 10 detected by the rotation sensor 22, determines a torque command for the motor 10. The EV ECU 18 supplies a control signal SW to the inverter 12 based on the determined torque command, and controls the operation of each switching element included in the inverter 12. As a result, the output torque of the motor 10 becomes a torque corresponding to the pedal operation or the like. The EV ECU 18 includes a voltage sensor 24 and a current sensor 2.
Monitoring the motor voltage V _M and the current I _M is detected by the 6, it is reflected in the control of the inverter 12.

[0004] The generator ECU 20 controls the power output of the engine-driven generator 16 while exchanging necessary information with the EV ECU 18. As shown in this figure, the engine-driven generator 16 includes an engine 28 and a generator 30 driven by the mechanical output of the engine 28.
It is composed of In this figure, the generator 30 is a three-phase AC generator, and its power output is rectified by a rectifier 32 and then supplied to the inverter 12 and the battery 14.

[0005] The engine 28 is normally operated with the throttle fully open (WOT). This is to keep the fuel efficiency of the engine 28 good and to reduce its emission to the lowest possible level. Generator ECU20 while inputting information such as the rotational speed _{N E} from the engine 28, controls the field current _{I f} of the generator 30. Since the engine 28 as described above is operated at full throttle, the rotational speed N _E of the engine 28 can be controlled only by the field current I _f of the generator 30, furthermore, thereby engine generator The power output of the machine 16 is also determined.
In a region where a throttle operation is necessary for efficiency, the generator ECU 20 operates the throttle opening θ.

Accordingly, the field current I _f, by determining in turn in accordance with the control target engine speed N _E to the output power of the motor 10, can suppress the discharge frequency of the battery 14, also the charge and discharge balance of the battery 14 Can be suitably balanced. That is, if the power consumed by the motor 10 can be covered by the generator 30, charging and discharging in the battery 14 is substantially unlikely to occur, and loss due to charging and discharging efficiency of the battery 14 can be reduced. If the charge / discharge balance of the battery 14 can be balanced, the SOC (charged state) of the battery 14 can be maintained at, for example, about 80%, and the life thereof can be extended.

On the other hand, _if the control target of the field current _If is determined by using the output power of the motor 10 as it is, the engine speed N
_E will change. Since the output variation of the motor 10 is generally rapidly or frequently, it appears similar properties to changes in the engine speed N _E. However, the engine speed _NE
Changes, the emission deteriorates and the like. Therefore, conventionally, detects the output of the motor 10, after averaging over the detected value to a predetermined time, the power generation output of the generator 30, a control target of the thus the field current I _f and the engine speed N _E Had to be set. That is, as shown in FIG. 4, the motor power consumption _PM (or the inverter input power) is averaged over a predetermined time T, and the obtained average value is used as the power generation output P _{G at the} next time T.
Was set as the control target. Thus, power output fluctuation of the power generator 30, while thus suppressing the fluctuation of the engine speed N _E, catering the motor power P _M by the power generation output P _G, it is possible to balance the charge and discharge balance of the battery 14.

FIG. 5 shows an example of the flow of the operation of the generator ECU 20. The flow shown in FIG.
Control shown in, i.e., one of the steps for realizing the quasi-stationary control of the engine speed N _E.

[0009] In this figure, the generator ECU 20 comprises:
First, reset the variables P and built-in timer for accumulating the detected value of the motor power P _M to 0 (100).
Generator ECU20 is subsequently enter information about motor power _{P M} from EVECU18 (102), it is incremented by 1 with a (104) timer for integrating it into a variable P (106). The generator ECU 20 repeats the above steps 102 to 106 until the content of the timer reaches the average time T (108). EVECU1
In 8, the multiplication of the motor rotational speed N _M is detected by the torque command and rotation sensor 22 determined in accordance with the depression amount of the accelerator or the brake or the motor voltage V _M and a current sensor 26 detected by the voltage sensor 24, by the multiplication of the motor current I _M is detected by, and detects the motor power P _M.

[0010] The power generator ECU20, the contents of the variable P, that the accumulated value of the motor power consumption _{P M} over time T Time T
In by dividing, the average value of the motor power P _M, which sets the control target of the power generation output P _G (11
0). The generator ECU 20 converts the obtained control target into a value corresponding to the engine speed (112),
Comparing the detected value of the engine speed _{N E} which is supplied from a (114). The generator ECU 20 controls drive elements such as transistors in accordance with the result of the comparison,
Controlling the field current _{I f} of the generator 30 (116). Thus, the field current I _f and the engine speed N _E becomes a value commensurate with the average value of the motor power P _M, the quasi-stationary control as shown in FIG. 4 is realized.

[0011]

However, such control may cause a deterioration in feeling due to a difference between the engine speed and the motor speed (more generally, the vehicle speed). For example, as shown in Figure 6, consider a case where the motor power P _M gradually decreases. Such a behavior appears, for example, when the vehicle speed gradually decreases (when the vehicle shifts from high load traveling to low load traveling). Control target of the power generation output P _G is from being set at an average time T in the previous, the power generation output P _G is reduced with a decrease in motor power P _M, although shorter than the average time T, slightly Delay. In this delay period, in some cases, the power generation output P _G is the much higher than the motor power P _M. In such a situation, the noise of the generator may be heard even though the vehicle speed is decreasing, or the vehicle may accelerate even though the vehicle operator is not stepping on the accelerator. You may feel uncomfortable. Such a problem becomes remarkable especially when the average time T is set to be longer.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and even when the average time of the motor power consumption is set to be relatively long, it is possible to prevent the motor power consumption from changing. An object of the present invention is to prevent a feeling from being deteriorated due to a delay in a power generation output.

[0013]

In order to achieve the above object, a power generation control method according to the present invention is directed to an SHV in which a generator is driven by a mechanical output of an engine and a motor is driven by a power output of the generator. Detecting the motor output and the vehicle speed, averaging the detected values of the motor output over a predetermined cycle, setting a power generation target in the next cycle, and controlling the field current of the generator according to the set power generation target. Controlling the power output of the generator and the number of revolutions of the engine by controlling the number of revolutions of the engine, and, in controlling the number of revolutions of the engine, the step of limiting the upper limit of the number of revolutions of the engine based on the detected vehicle speed, I do.

Further, the power generation control device according to the present invention includes a means for detecting a motor output, and a means for setting a power generation target in the next cycle by averaging the detected value of the motor output over a predetermined cycle. Means for controlling the generator current and the number of revolutions of the engine by controlling the field current of the generator in accordance with the power generation target, and driving the generator by the mechanical output of the engine and the motor by the power output of the generator A power generation control device mounted on the SHV for driving the vehicle, comprising: means for detecting the vehicle speed; and means for limiting the upper limit of the engine speed based on the detected vehicle speed in controlling the engine speed. And

[0015]

In the present invention, in controlling the engine speed, the upper limit of the engine speed is limited based on the detected value of the vehicle speed. Therefore, for example, when the detected vehicle speed is low, the engine speed can be suppressed, so that the engine sound becomes apparent or a sense of discomfort occurs due to a delay in the power generation output with respect to the motor power consumption. Can be prevented. In particular, engine rotation
The power generation shortage caused by the difference between the number and the upper limit
If you try to include in the power generation target in the cycle of
Insufficient power generation without causing engine noise and other manifestations
The amount can be supplemented.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. Further, since the present invention can be implemented under the system configuration shown in FIG. 3, the following description presupposes the configuration shown in FIG. 3, but the present invention is limited to such a configuration. Not something. Further, FIG.
The same reference numerals are given to the same variables and the same processing steps as in the conventional example shown in FIG. 6, and the description will be omitted.

FIG. 1 shows a flow of the operation of the generator ECU 20 in the first embodiment of the present invention. In this embodiment, after execution of step 112, the motor speed N
_M is detected, and the maximum engine speed map 200 is referred to based on the result (118). That is, the generator ECU 20 controls the motor rotation speed N via the EV ECU 18.
Information about _M is input, and thereby the maximum engine speed map 200 is referred to. The maximum engine speed map 200 indicates that the motor speed _NM is the maximum engine speed N
_This is a map associated with _EMAX , for example, a map of step-like characteristics as shown in the figure. By referring to the maximum engine speed map 200 may determine the maximum engine speed N _EMAX in accordance with the detected value of the motor rotational speed N _M.

Generator ECU 20 compares the determined maximum engine speed N _EMAX with the engine speed target value obtained in step 112 (120). As a result, the engine speed target value becomes the maximum engine speed N
_{If EMAX} is exceeded, the generator EUC
In step 20, the maximum engine speed N _EMAX obtained in step 118 is set as the engine speed target value actually used for control, instead of the engine speed target value obtained in step 112 (122). Generator ECU2
0 indicates that the target engine speed is set to the maximum engine speed N _EMAX after execution of step 122 or in step 120.
After it is determined that it is below, the process proceeds to step 114.

[0019] Thus, in this embodiment, the engine speed N _E, it is possible to limit restricted by the maximum engine speed N _EMAX was determined in accordance with the motor rotational speed N _M. Accordingly, the phenomenon is less likely to occur such learn the or discomfort may become engine sound harsh at the motor rotational speed N _M is less situation (situation that low-speed traveling),
An SHV with a better feeling can be realized. There is no need to take measures against noise of the engine 28 alone or sound insulation of the vehicle.

The control described above, i.e., the upper limit of the engine rotational speed N _E corresponding to the motor rotation speed N _M is particularly effective when it is necessary to set the average time T in the long value. That is, when the vehicle is traveling in an urban area is often stopped state, suppressing the control target of the generator output P _G by the motor power P _M is set longer the average time T since the less frequently a large value be able to. Along with this, it is possible to use a generator having a relatively small rating as the generator 30, which is advantageous in reducing the size of the device and reducing the cost. Therefore, as in the present embodiment, the power generation output P _G to the motor power P _M
If the deterioration of the feeling due to the delay of the above is prevented without variable control of the average time T, there is a great merit in that the physique and cost of the generator 30 can be suppressed. This becomes clearer when compared with a configuration in which the average time T is variably controlled in accordance with the vehicle speed as disclosed in, for example, JP-A-6-245320. However, the present invention can be combined with the configuration disclosed in JP-A-6-245320.

In the above description, the EV ECU
The motor rotation speed _{N M} obtained by 18 is transferred to the generator ECU 20, thereby the maximum engine speed map 200
However, an output signal from the rotation sensor 22, for example, a pulse signal indicating the angular position of the rotor of the motor 10 may be input to the generator ECU 20, or a signal for driving a speedometer may be used. May be input. Also, the maximum engine speed N
Instead of _EMAX, for example, the amount of such maximum power output, may be associated with the motor rotation speed on the map 200 N _{M (or} the amount corresponding thereto).

Furthermore, when setting the maximum engine speed N _EMAX to the engine rotational speed target value, as shown in FIG. 2, it may be configured to detect the power generation shortage P _S (1
24). That is, when it is determined in step 120 that the target engine speed exceeds the maximum engine speed N _EMAX , the maximum engine speed N _{EM is determined.}
If the _AX performs control as a target value of the engine speed, the amount corresponding to the difference between the engine rotational speed target value obtained by the maximum engine speed N _{EM AX} and step 112, to the motor power P _M power output P _G is insufficient, that amount is taken out from the battery 14 (discharge). To prevent this, prior to performing step 122, N
_EMAX - calculates the (engine speed target value), which is stored in the variable _{P S} is converted into electric power (124). Further, when determining the control target of the power generation output _{P G,} so as to add the power shortage _{P S} to P / T (126).
In this way, when there is a margin in the engine rotational speed N _E as viewed from the motor rotation speed N _M, ie without generating a manifestation of the engine noise, power shortage P _S generated in previous time Can be supplemented. Thereby, the charge / discharge balance of the battery 14 can be improved as compared with the embodiment of FIG.

[0023]

As described above, according to the present invention,
When controlling the engine speed, the upper limit of the engine speed is limited based on the detected value of the vehicle speed. It is possible to prevent or reduce a feeling problem such as a feeling of strangeness such as acceleration of the vehicle. In particular, the engine times
The power generation shortage caused by the difference between the number of turns and the upper limit
If you want to include the power generation target in the next cycle
Power generation without generating engine noise etc.
The shortage can be compensated.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a flow of an operation of a generator ECU according to a first embodiment of the present invention.

FIG. 2 is a flowchart illustrating a flow of an operation of a generator ECU according to a second embodiment of the present invention.

FIG. 3 is a block diagram schematically illustrating a system configuration of a series hybrid vehicle (SHV).

FIG. 4 is a timing chart showing an outline of quasi-stationary control of the engine speed.

FIG. 5 is a flowchart showing a flow of an operation of a generator ECU in a conventional example.

FIG. 6 is a timing chart showing a conventional problem.

[Explanation of symbols]

10 motors, 12 inverters, 14 batteries, 1
6 engine drive generator, 18 EV ECU, 20 generator ECU, 22 rotation sensor, 24 voltage sensor, 2
6 current sensor, 28 engine, 30 generator, _{N M}
Motor speed, _{N E} engine speed, _{I f} field current, _{P M} motor power, _{P G} power output, T Mean Time.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B60L 11/02-11/14 B60K 6/02 F02D 29/06

Claims (4)

(57) [Claims] In a series hybrid vehicle in which a generator is driven by a mechanical output of an engine and a motor is driven by a power output of the generator, a step of detecting a motor output and a vehicle speed; Setting the power generation target in the next cycle by averaging; controlling the generator's field current in accordance with the set power generation target to control the power generation output of the generator and the engine speed; and A step of controlling the engine speed based on the detected vehicle speed in controlling the engine speed. 2. A power generation control method according to claim 1, wherein the power generation is performed by a difference between an engine speed and an upper limit thereof.
Transfer the power shortage to the power generation target in the next cycle
A power generation control method comprising: 3. A means for detecting a motor output, a means for setting a power generation target in the next cycle by averaging the detected value of the motor output over a predetermined cycle, and a field current of the generator according to the set power generation target. Means for controlling the power output of the generator and the number of revolutions of the engine by controlling the power of the generator. A power generation control device, comprising: a means for detecting a vehicle speed; and a means for controlling an engine speed to limit an upper limit of the engine speed based on the detected vehicle speed. 4. A power generation control device according to claim 3, wherein the power generation is caused by a difference between an engine speed and an upper limit thereof.
Transfer the power shortage to the power generation target in the next cycle
A power generation control device comprising means.