JPH08256403A - Power generation control method and device in series hybrid vehicle - Google Patents

Abstract

PURPOSE: To prevent engine noise and the like from being conspicuous when a vehicle speed goes down. CONSTITUTION: The number of motor revolutions NM is detected, and the map of the maximum number of engine revolutions 200 is referred to (118). The upper limit of the target value of the number of engine revolutions is restricted on the basis of the maximum number of engine revolutions NEMAX obtained by referring thereto (120, 122). Since the maximum number of engine revolutions NEMAX is changed according to the number of motor revolutions NM, the number of engine revolutions can be suppressed in the case of a low vehicle speed, so that the sound of an engine may be prevented from being conspicuous and the like.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art FIG. 3 shows an outline of a so-called SHV system configuration. In this system, a three-phase AC motor 10 is used as a motor for running the vehicle, and the drive power of this motor 10 is the inverter 12
Is supplied from the battery 14 or the engine-driven generator 16. Further, the battery 14 can be charged by electric power from an external power source (not shown), regenerative electric power from the motor 10, or the generated output of the engine-driven generator 16.

An EV ECU 18 and a generator ECU 20 are provided as control devices. The EVECU 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 EVECU 18 supplies the control signal SW to the inverter 12 based on the determined torque command, and controls the operation of each switching element forming the inverter 12. As a result, the output torque of the motor 10 becomes a torque according to pedal operation or the like. Further, the EVECU 18 includes the voltage sensor 24 and the current sensor 2.
The motor voltage V _M and the current I _M detected by 6 are monitored and reflected in the control of the inverter 12.

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

The engine 28 is normally operated with the throttle fully open (WOT). This is to keep the fuel economy of the engine 28 good and to keep 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 the region where the throttle operation is required for efficiency, the generator ECU 20 operates the throttle opening θ.

Therefore, by setting the control target of the field current _If and the engine speed N _E according to the output power of the motor 10, the charging / discharging frequency of the battery 14 can be suppressed, and the charging / discharging balance of the battery 14 can be suppressed. Can be appropriately balanced. That is, if the power consumed by the motor 10 can be covered by the generator 30, charging / discharging of the battery 14 is substantially unlikely to occur, and loss due to charging / discharging efficiency of the battery 14 can be reduced. Further, if the charge / discharge balance of the battery 14 can be balanced, the SOC (state of charge) of the battery 14 can be maintained at, for example, about 80%, and its life can be extended.

On the other hand, assuming that the output power of the motor 10 is used as it is to determine the control target of the field current _If , the engine speed N is changed by the variation of the output of the motor 10.
_E will change. Since the output fluctuation of the motor 10 is generally abrupt or frequent, a similar property appears in the change of the engine speed N _E. However, the engine speed N _E
If the value changes, the emission will worsen. Therefore, conventionally, the output of the motor 10 is detected, the detected values are averaged over a predetermined time, and then the power generation output of the generator 30, and thus the control target of the field current _If and the engine speed N _E is set. I was trying to set it. That is, as shown in FIG. 4, the motor power consumption P _M (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.
Had been set as the control target of. As a result, the power consumption P _M of the motor 14 can be covered by the power generation output P _{G and} the charge and discharge balance of the battery 14 can be balanced while suppressing the power generation output fluctuation of the generator 30 and eventually the engine speed N _E.

FIG. 5 shows an example of the operation flow of the generator ECU 20. The flow shown in this figure is as shown in FIG.
This is one of the procedures for realizing the control shown in, that is, the quasi-steady state control of the engine speed N _E.

In this figure, the generator ECU 20 is
First, a variable P for accumulating the detected value of the motor power consumption P _M and a built-in timer are reset to 0 (100).
Subsequently, the generator ECU 20 inputs information on the motor power consumption P _M from the EVECU 18 (102), accumulates this in the variable P (104), and increments the timer by 1 (106). The generator ECU 20 repeats the above steps 102 to 106 until the content of the timer reaches the average time T (108). The 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, The motor power consumption P _M is detected by multiplying the motor current I _M detected by.

The generator ECU 20 calculates the contents of the variable P, that is, the integrated value of the motor power consumption P _M over the time T, at the time T.
By dividing by, the average value of the motor power consumption P _M is obtained, and this is set as the control target of the power generation output P _G (11
0). The generator ECU 20 converts the obtained control target into an engine speed equivalent value (112), and converts this into the engine 28.
It is compared with the detected value of the engine speed N _E supplied from (114). The generator ECU 20 controls drive elements such as transistors according to the result of this comparison,
Controlling the field current _{I f} of the generator 30 (116). As a result, the field current _If and the engine speed N _E become values corresponding to the average value of the motor power consumption P _M , and the quasi-steady control as shown in FIG. 4 is realized.

[0011]

However, such control may result in deterioration of feeling due to the difference between the engine speed and the motor speed (more generally, vehicle speed). For example, consider the case where the motor power consumption P _M gradually decreases as shown in FIG. Such a behavior appears, for example, when the vehicle speed gradually decreases (when high-load running shifts to low-load running). Since the control target of the power generation output P _G is set at the previous average time T, the power generation output P _G is slightly shorter than the average time T in order to decrease with the decrease in the motor power consumption P _M. Will be delayed. In this delay period, in some cases, the power generation output P _G greatly exceeds the motor power consumption P _M. Under these circumstances, the noise of the generator may be heard in the ear despite the vehicle speed decreasing, or the vehicle may accelerate even if the vehicle operator does not step on the accelerator. You may feel uncomfortable. Such a problem becomes remarkable especially when the average time T is set to be long.

[0012] The present invention has been made to solve the above problems, and even if the average time of the motor power consumption is set to be relatively long, it is possible to cope with the change in the motor power consumption. The purpose is to prevent the deterioration of feeling due to the delay of the power generation output.

[0013]

In order to achieve such an object, a power generation control method according to the present invention is applied to an SHV in which a mechanical output of an engine drives a generator and a power output of a generator drives a motor. , The step of detecting the motor output and the vehicle speed, the step of setting the power generation target in the next cycle by averaging the detected values of the motor output over a predetermined cycle, and the field current of the generator controlled according to the set power generation target The step of controlling the power generation output of the generator and the engine speed by controlling the engine speed, and the step of controlling the engine speed by limiting the engine speed based on the detected vehicle speed. To do.

Further, the power generation control device according to the present invention includes means for detecting the motor output and means for averaging the detected values of the motor output over a predetermined cycle to set a power generation target in the next cycle. Means for controlling the power output of the generator and the engine speed by controlling the field current of the power generator in accordance with the power generation target, the mechanical output of the engine drives the generator, and the power output of the generator drives the motor. An electric power generation control device mounted on an SHV for driving a vehicle includes means for detecting a vehicle speed and means for controlling an engine speed, an upper limit for the engine speed based on the detected vehicle speed. And

[0015]

In the present invention, in controlling the engine speed, the engine speed is limited to the upper limit 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 strange feeling occurs due to the delay of the power generation output with respect to the motor power consumption. Can be prevented.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment 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 is premised on the configuration shown in FIG. 3, but the present invention is limited to such a configuration. Not a thing. Furthermore, FIG.
The same variables and similar processing steps as those of the conventional example shown in FIG. 6 are designated by the same reference numerals, and the description thereof will be omitted.

FIG. 1 shows the flow of operation of the generator ECU 20 in the first embodiment of the present invention. In this embodiment, after the execution of step 112, the motor rotation 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 receives the motor rotation speed N via the EV ECU 18.
Enter information about _M , which refers to maximum engine speed map 200. The maximum engine speed map 200 shows the motor speed N _M as the maximum engine speed N
It is a map associated with _EMAX , for example, a map of step-like characteristics as shown in the figure. By referring to this maximum engine speed map 200, it is possible to determine the maximum engine speed N _EMAX according to the detected value of the motor speed N _M.

The 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 is the maximum engine speed N.
_In case of exceeding _EMAX , generator EUC
20 sets the maximum engine speed N _EMAX obtained in step 118 to the engine speed target value actually used for control instead of the engine speed target value obtained in step 112 (122). Generator ECU2
0 means that the engine speed target value is the maximum engine speed N _EMAX after the execution of step 122 or in step 120.
After it is determined that the following is true, the process proceeds to step 114.

As described above, in this embodiment, the engine speed N _E can be limited to the upper limit by the maximum engine speed N _EMAX determined according to the motor 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),
It is possible to realize an SHV with a better feeling. It is not necessary to take noise measures for the engine 28 alone or sound insulation measures for the vehicle.

The above-described control, that is, the upper limit of the engine speed N _E according to the motor speed N _M is particularly effective when the average time T has to be set to a long value. That is, when traveling in an urban area where there are many stopped states, the frequency of the motor power consumption P _M having a large value is low, so the control target of the generator output P _G is suppressed by setting the average time T longer. be able to. Accordingly, a relatively small rated generator can be used 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 with} respect to the motor power consumption P _M
If the deterioration of the feeling due to the delay of is prevented without the variable control of the average time T, it is possible to suppress the physique and cost of the generator 30, which is a great advantage. This becomes clearer when compared with a configuration in which variable control of the average time T is performed according to the vehicle speed as disclosed in, for example, Japanese Patent Laid-Open No. 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 in 18 is transferred to the generator ECU 20, and the maximum engine rotation speed map 200
However, the 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 the speedometer. May be input. Also, the maximum engine speed N
_Instead of _EMAX , for example, the amount of maximum power generation output or the like may be associated with the motor rotation speed N _M (or the amount corresponding thereto) on the map 200.

Further, when the maximum engine speed N _EMAX is set to the engine speed target value, the power generation shortage amount P _S may be detected as shown in FIG. 2 (1
24). That is, when it is determined in step 120 that the engine speed target value exceeds the maximum engine speed N _EMAX , the maximum engine speed N _{EM is determined.
When the} control is performed by using _AX as the target value of the engine speed, the motor power consumption P _M is corresponding to the difference between the maximum engine speed N _{EM AX} and the engine speed target value obtained in step 112. The power generation output P _G is insufficient, and the amount is taken out (discharged) from the battery 14. To prevent this, before executing 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 , this power generation shortage amount P _S is added 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 the engine speed is controlled, the engine speed is limited to the upper limit based on the detected value of the vehicle speed. It is possible to prevent or reduce a feeling problem that the vehicle feels uncomfortable such as acceleration.

[Brief description of drawings]

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

FIG. 2 is a flowchart showing a flow of operations of a generator ECU according to a second embodiment of the present invention.

FIG. 3 is a block diagram showing an outline of a system configuration of a series hybrid vehicle (SHV).

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

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

FIG. 6 is a timing chart showing conventional problems.

[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 rotation speed, _NE engine rotation speed, _If field current, P _M motor power consumption, P _G power generation output, T average time.

Claims (2)

[Claims] 1. A series hybrid vehicle in which a generator is driven by a mechanical output of an engine and a motor is driven by a generated output of the generator, a step of detecting a motor output and a vehicle speed, and a detected value of the motor output over a predetermined period. A step of setting a power generation target in the next cycle by averaging, a step of controlling the power generation output of the generator and the engine speed by controlling the field current of the generator according to the set power generation target, In controlling the rotation speed, a step of limiting an upper limit of the rotation speed of the engine based on the detected vehicle speed is included, and a power generation control method. 2. A means for detecting a motor output, a means for setting a power generation target in the next cycle by averaging detected values of the motor output over a predetermined cycle, and a field current of a generator according to the set power generation target. And a means for controlling the power generation output of the generator and the number of revolutions of the engine by controlling the motor, and is mounted on a series hybrid vehicle that drives the generator by the mechanical output of the engine and drives the motor by the power output of the generator. The power generation control device according to claim 1, further comprising: a unit configured to detect a vehicle speed, and a unit configured to limit an engine speed based on the detected vehicle speed when controlling the engine speed.