JPH0847107A - Generating controlling method for series hybrid vehicle - Google Patents

Abstract

PURPOSE:To improve the power efficiency by so deciding a target generating energy in response to a requested driving power from a motor as to reduce the discharge power of a battery when a vehicle is in a slow accelerating state. CONSTITUTION:When the slow accelerating state of a vehicle is detected by an ECU 28, a target generating energy is so decided according to the driving power required from a motor 10 as to reduce the discharge power of a battery 16. The slow accelerating state of the vehicle can be detected by the change of an accelerator S or the charge state, and the driving power required from the motor 10 can be known on the basis of a vehicle speed SPD (number of revolutions of the motor N) or an accelerator opening S (torque command). Thus, when the vehicle is in the slow accelerating state, the calculation of the mean input power to the motor 10 is not conducted, and hence the response delay of the generating energy control is reduced, and a difference between the input voltage and the generating energy to the motor 10 is reduced. In this manner, the power efficiency as the entire vehicle can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a series hybrid vehicle in which the power output of a generator driven by an engine can be used to charge a battery and drive a motor, and the discharge power of the battery can be used to drive a motor. (SHV), and more particularly, to a power generation control method thereof.

[0002]

2. Description of the Related Art SHV is a vehicle capable of supplying driving power for a motor from both a generator and a battery, and a vehicle capable of charging a battery with a power output of the generator. SHV
The first method for controlling the power generation output of the generator in
There is a method of changing the target power generation amount according to the vehicle speed. For example, if the vehicle speed is in the range of 0 to 20 km / h, 20 to 20
When it is 40 km / h, when it is 40-60 km / h, different target power generation amounts are set for ...
The target power generation amount is determined according to the detected vehicle speed (motor rotation speed). Since the output of the motor depends on its rotation speed, it is possible to generate electric power according to the output required by the motor by controlling the field current of the generator based on the determined target power generation amount. Is. In addition, by taking the state of charge (SOC) of the battery into consideration when determining the target amount of power generation, it is possible to prevent a significant change in the SOC of the battery and extend its life.

A second method of controlling the power generation output of the generator in SHV is to change the target power generation amount according to the accelerator opening. For example, similar to the method using the speed described above, the target amount of power generation is set by dividing the accelerator opening into regions, and the target amount of power generation is determined according to the input accelerator opening. The accelerator opening indicates the acceleration request from the vehicle operator, and the output torque of the motor is controlled according to the accelerator opening.Therefore, control the field current of the generator based on the determined target power generation amount. Thus, it is possible to generate electric power according to the output required from the motor. Also in this method, it is preferable to take the SOC of the battery into consideration when determining the target power generation amount.

A third method for controlling the power generation output of the generator in SHV is to change the target power generation amount according to the SOC of the battery. For example, if the SOC is less than a predetermined value, it is considered necessary to charge, and the generator is operated,
On the contrary, when it is equal to or more than the predetermined value, the generator is stopped. While the generator is operating, its rotation speed is kept constant.

Each of these methods is a method developed from the viewpoint of keeping the fuel consumption rate and emission of the engine in good condition. Here, it is known that the fuel consumption rate and emission of the engine are improved by maintaining the engine speed within a certain range. Further, even when the engine speed is changed as little as possible and even when it is changed, it is possible to suppress the deterioration of the fuel consumption rate and the emission by making the change as gentle as possible. Therefore,
According to the method in which the target power generation amount is a constant value in each region of the vehicle speed or the accelerator opening degree, or the target power generation amount is also a constant value while the generator is operating, as in the above-described methods, The fuel efficiency and emission of the engine can be maintained in a relatively good state.

However, these methods have limitations in improving the electric power efficiency of the entire vehicle. That is, since the input power to the motor fluctuates depending on the driving method and other factors, when the input power to the motor exceeds the power generation amount (target power generation amount) and when it falls below the power generation amount (target power generation amount) alternately. appear. When it is higher, the amount of (input power to the motor)-(power generation) is covered by the battery discharge, and when it is lower, (power generation)-(input power to the motor).
Power is used to charge the battery. Therefore, in the power output of the generator, the electric power input to the motor when the battery is once charged and then discharged causes a loss due to the charging efficiency and the discharging efficiency of the battery. This loss is the cause of the reduction in power efficiency of the entire vehicle.

Fourthly, as a method of controlling the power generation output of the generator in the SHV, there is a method previously proposed by the applicant of the present application (Japanese Patent Application No. 5-29085). This method is a method of detecting the input power from the generator and the battery to the motor, averaging them over time, and correcting the preset target power generation amount according to the average input power. By doing this, the amount of power generation will change in a manner that follows the fluctuations in the input power to the motor, so that the difference between the input power to the motor and the amount of power generation will be It becomes smaller than.
As a result, the power efficiency of the entire vehicle is improved.

[0008]

However, even in the above-mentioned fourth method, the difference between the input power to the motor and the power generation amount may become large. That is, in this method, since the average input power to the motor is calculated, a delay in the response of the power generation amount control to the fluctuation of the input power to the motor is inevitable. Therefore, if the vehicle is in a gentle acceleration (slow acceleration) state at a certain point in time, electric power will be taken out from the battery while the response of the power generation control is delayed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and reduces the response delay of the power generation control when the vehicle is in a slow acceleration state to reduce the input to the motor. The difference between the electric power and the amount of power generation is made smaller,
An object of the present invention is to suppress the frequency of charge and discharge of the battery to improve the power efficiency of the entire vehicle and at the same time extend the life of the battery. A further object of the present invention is to minimize the difference between the input power to the motor and the amount of power generation when the vehicle is not in the slow acceleration state. It is an object of the present invention to maintain the engine speed at which the fuel efficiency and the emission of the engine are good, including when the vehicle is in a slow acceleration state. An object of the present invention is to suppress fluctuations in the engine speed so that the fuel efficiency and the emission of the engine are improved, even when the vehicle is in a slow acceleration state.

[0010]

In order to achieve such an object, the present invention provides an engine, a generator driven by the engine, a battery charged by the generated output of the generator,
In an SHV equipped with a motor driven by the power output of the generator and the discharge power of the battery, and a means for target-controlling the power output of the power generator according to the target power generation amount, it is detected that the vehicle is in a slow acceleration state and When it is detected that the vehicle is in an accelerated state, the target power generation amount is determined according to the driving power required by the motor so that the discharging power of the battery becomes small.

According to the present invention, when it is not detected that the vehicle is in a slow acceleration state, the input power from the generator and the battery to the motor is averaged over a predetermined time, and the target power generation amount is calculated based on the obtained average value. It is characterized by determining.

The present invention is obtained by averaging the input power from the generator and the battery to the motor over a predetermined time when the determined target power generation amount does not belong to the range where the engine efficiency is good. The target power generation amount is corrected and determined based on the average value.

According to the present invention, when the difference between the determined target power generation amount and the current power generation output of the generator is equal to or larger than a predetermined amount, the target power generation output is set to be less than the predetermined amount. It is characterized in that the amount is modified and determined.

[0014]

In the present invention, when it is detected that the vehicle is in a slow acceleration state, the discharge power of the battery is reduced.
The target power generation amount is determined according to the drive power required from the motor. The fact that the vehicle is in a gradual acceleration state can be detected by a change in the accelerator opening degree, SOC, etc., and the drive power required from the motor can be known based on the vehicle speed (motor rotation speed) and the accelerator opening degree (torque command). . As described above, in the present invention, when the vehicle is in the slow acceleration state, the average input power to the motor is not calculated, so the response delay of the power generation control in this case is reduced, and the input to the motor is reduced. The difference between the voltage and the amount of power generation becomes smaller. this is,
This leads to an improvement in the frequency of battery charging / discharging, and eventually in the power efficiency of the vehicle as a whole, and an extension of battery life by suppressing SOC fluctuations.

In the present invention, when it is not detected that the vehicle is in the slow acceleration state, the target power generation amount is determined according to the above-mentioned fourth method, that is, the method previously proposed by the applicant of the present application. Therefore, even when the vehicle is not in the slow acceleration state, the difference between the input power to the motor and the power generation amount becomes small, and the SHV with improved power efficiency can be obtained.

In the present invention, when the determined target power generation amount does not belong to the range where the efficiency of the engine is good, the target power generation amount is determined according to the method previously proposed by the applicant of the present application. That is, if the target output control of the generator based on the determined target power output causes the engine speed to fall outside the specified range and fuel consumption and emission problems occur, even if the vehicle is in a slow acceleration state. The method previously proposed by the applicant of the present application is used to ensure suboptimal power efficiency.

In the present invention, when the difference between the determined target power generation amount and the current power generation output of the generator is a predetermined amount or more, the difference between the current target power generation output and the current power generation output of the generator is less than the predetermined amount. The target power generation amount is corrected and decided. Therefore, when the power generation output is controlled according to the initially determined target power generation amount, such a situation is avoided when the engine speed fluctuates sharply and the fuel consumption rate and emission of the engine deteriorate.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an SHV according to an embodiment of the present invention.
The system configuration of is shown. In this embodiment, a three-phase AC motor is used as the vehicle traveling motor 10, and its output shaft is connected to the drive wheels 14 via the transaxle 12 and the like. The drive power source of the motor 10 is a battery 16 and a generator 18. The discharge power of the battery 16 is supplied to the motor 10 after being converted into three-phase AC by the inverter 20, and the power output of the generator 18 is rectified by the rectifier 22 and further converted into three-phase AC by the inverter 20. And then supplied to the motor 10. Therefore, in this embodiment, the motor 10 can be driven by utilizing the discharged power of the battery 16 and the generated output of the generator 18, and the battery can be driven by the generated output of the other generator 18 and the regenerated power of the motor 10 outside the vehicle not shown. 16 can be charged.
Further, the generator 18 is driven by the mechanical output of the engine 26, which is increased in speed by the speed increaser 24. Engine 2
The rotational speed N _{E of} 6 can be controlled by the field current I _f of the generator 18 that is the load of the engine 26 when other operating conditions (throttle opening degree, etc.) are constant.

The ECU 28 controls the entire system shown in this figure. For example, when the vehicle operator depresses an accelerator pedal (not shown), the ECU 28 determines a torque command according to the accelerator opening S, and controls the current vector of the motor 10 according to the determined torque command. More specifically, this control is realized by applying a PWM (pulse width modulation) signal or the like to the inverter 20 and switching its switching element.

The ECU 28 controls the field current I _f of the generator 18.
In order to control the throttle opening of the engine 26 and the engine 26, a power generation control routine is executed at a predetermined frequency. This routine, because a duty control of the field current I _f therein, a short pinion intervals of about μsec~ number msec as shown in FIG. 2, is activated by means of the timer interruption or the like.
The ECU 28 also executes a target power generation amount determination routine that determines the target power generation amount P _T of the generator 18. As shown in FIG. 2, this routine is started by means such as a timer interrupt at intervals of about tens to hundreds of msec. When a certain condition is satisfied, the power generation control routine is called and executed in the target power generation amount determination routine.

In order to execute these operations, the ECU 28 detects the rotation speed N _E of the engine 26, and the temperature sensor 3 detects the water temperature θ _{E of the} engine 26.
2. Rectifier 2 for generating voltage V _G and current I _G of generator 18
2 voltage sensor 34 and current sensor 3 to be detected in the latter stage
6, voltage sensor 38 and current sensor 40 for detecting input voltage V _M and current I _M to the inverter 20, motor 10
Rotation speed sensor 42 for detecting the rotation speed N of the vehicle (vehicle speed SPD)
The detected value is input from a sensor such as.

FIG. 3 shows the contents of the target power generation amount determination routine.

In this routine, first, it is determined whether the calculation timing of the accelerator opening change amount ΔS has come (100). As described below, in this example,
Gradient of time change of accelerator opening S (= ΔS / calculation cycle)
However, since it is used to determine whether or not the vehicle is in the slow acceleration state, step 100 is provided to wait for the elapse of the calculation cycle of the accelerator opening change amount ΔS. If the calculation timing of the accelerator opening change amount ΔS has not arrived,
The normal target power generation amount determination process shown in steps 102 to 114 is executed.

The processing shown in steps 102 to 114 is processing according to the method proposed by the applicant of the present application in Japanese Patent Application No. 5-29085. In step 102,
The product of the input voltage V _M to the inverter 20 and the input current I _M is calculated, and thereafter this product is treated as the instantaneous input power P _M to the motor 10. The ECU 28 uses the input power P _M
Is integrated into the variable Sum (104), and the number of times of integration is counted by the variable i (106). If the cumulative number of times i has not reached the predetermined value j (108), the ECU 28 ends the target power generation amount determination routine.

When the cumulative number of times i reaches a predetermined value j, the ECU 2
In step 8, the motor input power integrated value Sum is divided by the integration number j (110) to obtain the average input power P _M ⁻ to the motor 10. The ECU 28 uses the calculated average input power P _M ⁻ as the battery 1
The value is divided by the charging / discharging efficiency η _{BAT of} 6 (112) and converted into a value that takes into consideration the charging and discharging of the battery 16. The value thus obtained is used as the target power generation amount P _{T in the} power generation control routine. The ECU 28
The used variables i and Sum are reset to 0, and the target power generation amount determination routine ends (114).

After that, when the power generation control routine is started by the timer interrupt, the target power generation amount P _T determined in step 112 is used in the power generation control routine. FIG.
Shows an example of the power generation control routine used in this embodiment. For the details of the function of this routine, the applicant of the present application has previously filed Japanese Patent Application No. 5-23.
See 1714.

The ECU 28 first uses the target power generation amount P _T determined in the target power generation amount determination routine as a key,
By referring to the map g showing the correspondence between the power generation amount of the generator 18 and the rotation speed N _E of the engine 26, the target engine rotation speed N _E that is the rotation speed N _E corresponding to the target power generation amount P _T.
Determine _T (200). Further, the ECU 28 uses the determined target power generation amount P _T as a key and refers to the map h showing the correspondence relationship between the power generation amount of the generator 18 and the throttle opening, thereby making a throttle corresponding to the target power generation amount P _T. The basic throttle opening S ₀ , which is the opening, is determined (20
2). At that time, the water temperature θ _E detected by the temperature sensor 32 is also used to reflect the warm-up state of the engine 26.

The ECU 28 determines that the current rotational speed N _E detected by the rotational speed sensor 32 is N _T −ΔN <N _E ≦ N _T
It is judged whether or not it is within the range of −ΔN (204, 206).
ECU28 turns on / off the field current I _f of the generator 18 in accordance with the determination result (208, 210). Number of revolutions N
_{When E} is in the range of N _T −ΔN <N _E ≦ N _T −ΔN, the ECU 28 determines that the power generation amount of the generator 18, that is, the product P of the voltage V _G and the current I _G is P _T −ΔP <P. ≤ P _T -ΔP
It is judged whether or not it is within the range (212, 214). ECU
28 is a throttle opening command correction amount Δ according to the determination result.
Increase or decrease S _ref (216, 218). The ECU 28
After executing step 208, 210, 214, 216 or 218, the throttle opening command correction amount ΔS _ref is added to the basic throttle opening S ₀ to obtain the throttle opening command S _ref (220), which is output to the engine 26. Then, the throttle opening is controlled (222). The ECU 28 ends the power generation control routine at this point.

The target power generation amount determination routine and the power generation control routine are periodically executed by timer interrupts. If the calculation timing of the accelerator opening change amount ΔS comes when the target power generation amount determination routine is started (100), the ECU 28 subtracts the accelerator opening amount at the previous calculation timing from the current accelerator opening S. Then, the accelerator opening change amount ΔS is calculated (116). The ECU 28 determines whether the calculated accelerator opening change amount ΔS is positive (118) and is equal to or less than a predetermined value K (120). The determination in step 118 is a determination as to whether or not the vehicle is in an accelerated state, and the determination in step 120 is a determination as to whether or not the acceleration is gentle. Therefore, when the vehicle operator depresses the accelerator pedal and the depressing method is gentle and the accelerator opening S changes by an amount of K or less within the calculation cycle of the accelerator opening change amount ΔS, step 118 The determination conditions of 120 and 120 are satisfied. If either of the conditions is not satisfied, step 102
The subsequent normal processing is executed. Note that K is made sufficiently small so that the emission of the engine 26 does not deteriorate when step 134 described below is executed.

The ECU 28 executes steps 118 and 120.
When it can be considered that the vehicle is in the slow acceleration state, the target power generation amount P _T is determined by referring to the map f of FIG. 5 using the vehicle speed SPD and the throttle opening S as keys (122). ). The rotation speed N of the motor 10 detected by the rotation speed sensor 42 is used as the vehicle speed SPD, and the throttle opening command S is used as the throttle opening S.
_{Use ref} etc. The ECU 28 determines the target power generation amount P determined.
_T is the fuel consumption rate / good emission range P shown in FIG.
_It is determined whether or not ₁ ≦ P _T ≦ P ₂ is satisfied (124), and if not, the process proceeds to step 102 to avoid deterioration of the fuel consumption rate or emission. E if yes
The CU 28 determines whether the target power generation amount P _T belongs to the range of P−γ <P _T <P + γ (126, 128). If it does not belong, it is considered that when the power generation control routine is executed based on the determined target power generation amount P _T , the power generation amount P of the generator 18 and the rotation speed N _{E of the} engine 26 suddenly change, resulting in deterioration of emission and the like. Therefore, the ECU 28
The target power generation amount P _T is limited so as to belong to the range of P−γ <P _T <P + γ (130, 132). It should be noted that in the figure, the restrictions are given by the equations P _T = P + γ and P _T = P−γ, but for example, P _T = P _T −γ, P _T = P
You may make restrictions by formulas, such as _T + (gamma). ECU 28
Starts the power generation control routine after executing steps 126 to 132 (134).

Therefore, according to the present embodiment, when the vehicle is in the slow acceleration state, the target power generation amount P _T is determined according to the vehicle speed SPD and the throttle opening S. No response delay occurs. As a result, the power efficiency of the entire vehicle can be improved and the life of the battery 16 can be extended. Furthermore, since steps 102 to 114 are executed when the vehicle is not in the slow acceleration state, the power efficiency is good when the vehicle is not in the slow acceleration state. In addition, since the running step 102-114 when P ₁ ≦ P _T ≦ P ₂ is not satisfied, the deterioration of fuel consumption rate and emission is less likely to occur. Furthermore, P-γ <P
_{When T} <P + γ is not satisfied, the target power generation amount P _T is limited, so that the fuel efficiency and the emission are further improved.

The reason why the steps 122 to 134 are executed only in the slow acceleration state is that the rotation speed N _{E of the} engine 26 is changed when the target power generation amount P _T is changed from time to time in the rapid acceleration state. This is because a sudden change occurs and the emission is deteriorated.

In the above description, the target power generation amount P _T when the vehicle is not in the slow acceleration state is determined by the method proposed by the applicant of the present application in Japanese Patent Application No. 5-29085. The present invention is not limited to this method, and can be combined with any conventionally known method using vehicle speed SPD (motor rotation speed N), SOC, accelerator opening S, and the like. Further, when determining the target power generation amount P _T when the vehicle is not in a slow acceleration state, the vehicle speed SPD (motor rotation speed N) is divided into regions, and the target power generation amount P _T is determined for each region. It is good (see Japanese Patent Application No. 5-29085).

Further, in the above description, whether or not the vehicle is in the gradual acceleration state is determined based on the accelerator opening change amount ΔS. However, this is due to a change in SOC or a change in motor input power P _M. You may make it based on this. Further, the motor input power P _M is substituted by the inverter input power, but the actual motor input power P _M is used as a method for detecting the current and voltage of the winding to obtain the product, or for the torque command. The detection may be performed using a method of multiplying the rotation speed N. In that case, it is necessary to consider the power conversion efficiency of the inverter 20. Furthermore, the charge / discharge efficiency η _BAT of the battery 16 may be treated as a variable instead of a constant.
That is, the charge-discharge efficiency eta from _BAT depends on the degree of deterioration of the battery 16, charge and discharge efficiency eta _BAT detects this deterioration degree
It is also possible to adopt a method of sequentially correcting (Japanese Patent Application No. 4-
70650, Japanese Patent Application No. 5-29085). The details of the power generation control routine may have other contents.

[0036]

As described above, according to the present invention,
When the vehicle is in a gradual acceleration state, the target power generation amount is determined according to the drive power demanded by the motor so that the discharge power of the battery becomes small. Therefore, calculate the average input power to the motor. The response delay due to does not occur when the vehicle is in a slow acceleration state, the power efficiency of the entire vehicle can be improved, and the battery life can be extended.

Further, according to the present invention, the target power generation amount is determined according to the method previously proposed by the applicant when the vehicle is not in the slow acceleration state, so that the power efficiency is also good when the vehicle is not in the slow acceleration state. SHV is obtained.

According to the present invention, the target power generation amount is determined according to the method previously proposed by the applicant when the determined target power generation amount does not belong to the range where the efficiency of the engine is good. The situation in which the engine speed falls outside the predetermined range and the fuel efficiency and emission deteriorate is less likely to occur, and suboptimal power efficiency can be secured.

According to the present invention, when the difference between the determined target power generation amount and the current power generation output of the generator is equal to or more than the predetermined amount, the difference between the current power generation output of the generator is less than the predetermined amount. Since the target power generation amount is corrected and determined so that the engine speed can be prevented from changing abruptly, and the fuel consumption rate and emission of the engine can be kept good.

[Brief description of drawings]

FIG. 1 is a block diagram showing a system configuration of a series hybrid vehicle according to an embodiment of the present invention.

FIG. 2 is a diagram showing execution frequencies of a power generation control routine and a target power generation amount determination routine in this embodiment.

FIG. 3 is a flowchart showing the contents of a target power generation amount determination routine in this embodiment.

FIG. 4 is a flowchart showing the contents of a power generation control routine in this embodiment.

FIG. 5 is a diagram showing the contents of a map showing the relationship between vehicle speed, throttle opening, and target power generation amount.

FIG. 6 is a diagram showing a region of power generation amount in which a fuel consumption rate and an emission are good.

FIG. 7 is a diagram for explaining deterioration of power efficiency of the entire vehicle due to charge / discharge of a battery.

[Explanation of symbols]

10 Motor 16 Battery 18 Generator 20 Inverter 26 Engine 28 ECU 30,42 Rotation Speed Sensor 32 Temperature Sensor 34,38 Voltage Sensor 36,40 Current Sensor S Accelerator Opening ΔS Accelerator Opening Change A K Accelerator Opening Change Time Constant threshold P _M motor input power V _M the inverter input voltage I _M inverter input current Sum motor input power integration value P _M ^- average motor input power P _T target power generation quantity eta _BAT charge-discharge efficiency SPD speed N motor speed P of the battery ₁ , P ₂ Upper and lower thresholds of power generation P P power generation V _G Power generation voltage I _G Power generation current γ Target power generation change limit value

Claims (4)

[Claims] 1. An engine, a generator driven by the engine, a battery charged by the generated output of the generator, a motor driven by the generated output of the generator and discharge power of the battery, and a generator according to the target power generation amount. In a series hybrid vehicle equipped with a means for controlling the power generation output, the step of detecting that the vehicle is in a gradual acceleration state, and the discharge power of the battery is reduced when the gradual acceleration state is detected. And a step of deciding a target power generation amount according to a driving power required from the motor, the power generation control method comprising: 2. The power generation control method according to claim 1, wherein when the slow acceleration state is not detected, the input power from the generator and the battery to the motor is averaged over a predetermined time period to obtain the power. A power generation control method comprising the step of determining a target power generation amount based on the average value. 3. The power generation control method according to claim 1, wherein when the determined target power generation amount does not belong to a range where the efficiency of the engine is good, the input power from the generator and the battery to the motor is given for a predetermined time. A power generation control method comprising the step of: averaging over, and correcting and determining a target power generation amount based on the obtained average value. 4. The power generation control method according to claim 1, wherein when the difference between the determined target power generation amount and the current power generation output of the generator is equal to or greater than a predetermined amount, the difference between the current power generation output of the generator. A method for controlling power generation, comprising the step of correcting and determining the target power generation amount so that is less than a predetermined amount.