JPH09200907A - Hybrid electric motorcar - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent overcharging by reducing the generation output in the stage where the accumulated voltage of a battery gets over the generation output decrease start voltage computed based on the rise rate of charging voltage, and stopping the generation output until it reaches the upper voltage limit value of a battery. SOLUTION: A voltage detector 280 detects the voltage (VB) of a battery (BT) for running. A voltage rise rate operating part 281 computes the rise rate ΔVB of VB, based on VB. A surplus voltage computing part computes the surplus voltage value ΔVC between a voltage upper limit value (VBmax ) of the quantity of accumulation of BT20 and a generation output decrease start voltage (VCutt ) to start the reduction of the generation output before it reaches VBmax . When a generation decrease judger judges that VB has gotten over VCutt , it reduces the generation output gradually, and this executes generation control to stop the generation output before it reaches VB max.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is equipped with a generator driven by an engine, a running battery and a running motor, and at least one of electric power generated by the generator and electric power stored in the running battery. The present invention relates to a hybrid electric vehicle that runs on electric power. In particular, the present invention relates to a hybrid electric vehicle in which the power generation output of the generator can be controlled according to the rate of increase in the voltage charged in the running battery or according to the state of charge of the running battery.

[0002]

2. Description of the Related Art In recent years, development of industrial facilities and equipment in consideration of the global environment has been actively conducted. Even in cars
Although electric vehicles without exhaust gas have been developed, there is a problem that the capacity of the battery for traveling is not yet sufficient and the continuous traveling distance is limited to this capacity. Also, it takes a long time to charge the running battery,
There is a problem that once discharged, it cannot be used immediately. Due to these problems, electric vehicles are used only for very limited purposes.

In order to compensate for such a problem, a so-called hybrid electric vehicle has been developed in which a generator driven by an engine is mounted on a vehicle and the vehicle is driven by electric power generated by the generator. SHV (series hybrid vehicl) among hybrid vehicles
In e), the operating condition of the engine can be kept constant, and the engine can always be operated near the maximum efficiency point. Since a harmful component of exhaust gas can be removed if a certain operating state can be secured, exhaust gas countermeasures can be implemented more reliably than when various operating states are assumed and exhaust gas countermeasures are taken.

In a hybrid type electric vehicle, when the vehicle is in a regenerative state, the traveling battery generally enters a charging mode, so that the storage voltage rises. In the SHV, the generator can generate electricity independently of the rotation state of the traveling motor, and the power generation state by the generator increases. Therefore, the electric power generated by the generator is used together with the regenerative power from the traveling motor. Will be charged. For this reason,
In the SHV, the degree of increase in the storage voltage of the traveling battery is larger than that in the PHV (parallel hybrid vehicle).

Generally, when the voltage for driving the battery for driving is increased, gas is generated, the charging efficiency is deteriorated, and the life of the battery for driving is shortened. Therefore, a voltage upper limit value (the voltage upper limit value is expressed as a function of temperature) is usually set for the voltage stored in the running battery, and measures are taken so that the voltage does not rise above the voltage upper limit value. There is. For example, in the case of PHV, when the voltage stored in the traveling battery during regeneration exceeds a voltage upper limit value, the regenerative torque of the traveling motor is reduced and the regenerative power is reduced. In the SHV, the stored voltage of the traveling battery often exceeds the upper limit voltage value during regeneration for the reason described above, and the generated output is often added even if the regenerative power of only the traveling motor is reduced. Therefore, there is a problem that the life of the battery for traveling is shortened. Further, when the storage voltage of the traveling battery exceeds the upper limit voltage limit value, the power consumption of the traveling motor becomes considerably smaller than the generated output not only in the regenerative state but also in the state where power is generated at a certain output. Sometimes it happens.

A technique for solving such a problem is disclosed in Japanese Patent Laid-Open No. 6-217413. In the technique disclosed in this publication, the power generation of the generator is stopped when the stored voltage of the running battery at the start of regenerative braking is equal to or higher than a predetermined value, and overcharging of the running battery can be prevented.

[0007]

However, in the technique disclosed in the above-mentioned publication, the following points are not taken into consideration. Due to emission and fuel consumption, it is necessary to gradually stop the power generation of the generator. Depending on the setting of the predetermined value, the storage voltage of the traveling battery may exceed the upper limit voltage limit value when the power generation by the generator is completely stopped, and the storage voltage of the traveling battery may be overcharged. As a result, the charging efficiency of the traveling battery mounted on the SHV is deteriorated, and the life of the traveling battery is shortened.

The present invention has been made to solve the above problems. Therefore, an object of the present invention is to provide a hybrid electric vehicle that can improve the charging efficiency of the running battery and can extend the life of the running battery.

[0009]

In order to achieve the above-mentioned object, the invention described in claim 1 is equipped with a generator driven by an engine, a battery for traveling and a motor for traveling, and the generator. In a hybrid electric vehicle in which the traveling motor is driven by at least one of the electric power generated by the traveling battery and the electric power stored in the traveling battery, a voltage increase for calculating an increase rate of the voltage charged in the traveling battery. Based on the rate calculation means and the voltage increase rate calculated by the voltage increase rate calculation means, the power generation output reduction start for starting the reduction of the power generation output of the generator before the voltage upper limit value of the running battery is reached A power generation output reduction start voltage value setting means for setting a voltage value, the voltage value of the traveling battery and the power generation output reduction start voltage value are compared, and When the voltage value of the running battery exceeds the power generation output reduction start voltage value, the power generation output is gradually reduced between the power generation output reduction start voltage value and the voltage upper limit limit value, and the voltage upper limit limit is set. Generator voltage output control means for stopping the power generation output of the generator before reaching the value,
It is characterized by having.

In the hybrid electric vehicle according to the first aspect of the present invention, the rate of increase in the voltage charged in the traveling battery is calculated by the voltage increase rate calculating means. Based on this increase rate, the power generation output reduction start voltage value setting means sets the power generation output reduction start voltage value.
The power generation output reduction start voltage value is a threshold value at which the reduction of the power generation output of the generator is started before the voltage upper limit value of the running battery is reached. The power generation output reduction start voltage value is compared with the voltage value of the traveling battery by the generator voltage output control means, and when the voltage value of the traveling battery exceeds the power generation output reduction start voltage value, The power generation output is gradually reduced up to the voltage upper limit value.
Then, the generator voltage output control means stops the power generation output of the generator until the voltage value of the traveling battery reaches the voltage upper limit value.

According to a second aspect of the invention, a generator driven by an engine, a traveling battery and a traveling motor are mounted, and the electric power generated by the generator and the electric power stored in the traveling battery are installed. In a hybrid electric vehicle in which the traveling motor is driven by at least one of the following, based on the state of charge of the traveling battery, a reduction in the power generation output of the generator before the voltage upper limit value of the traveling battery is reached. A power generation output reduction start voltage value setting means for setting a power generation output reduction start voltage value to be started, the voltage value of the traveling battery and the power generation output reduction start voltage value are compared, and the voltage value of the traveling battery is When the power generation output reduction start voltage value is exceeded, the power generation output is gradually reduced from the power generation output reduction start voltage value to the voltage upper limit value. And, characterized in that and a generator voltage output control means for stopping the power generation output of the generator to reach the upper voltage limit limiting value.

In the hybrid electric vehicle according to the second aspect of the present invention, the power generation output reduction start voltage value is set by the power generation output reduction start voltage value setting means from the charged state of the running battery. The power generation output reduction start voltage value is a threshold value at which the reduction of the power generation output of the generator is started before the voltage upper limit value of the running battery is reached. The power generation output reduction start voltage value is compared with the voltage value of the traveling battery by the generator voltage output control means, and when the voltage value of the traveling battery exceeds the power generation output reduction start voltage value, The power generation output is gradually reduced up to the voltage upper limit value. Then, the generator voltage output control means stops the power generation output of the generator until the voltage value of the traveling battery reaches the voltage upper limit value.

[0013]

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

Embodiment 1 FIG. 2 is a diagram showing a drive system and a drive control system mounted on a hybrid electric vehicle according to an embodiment of the present invention.
As shown in FIG. 2, in the hybrid electric vehicle, the generator 10 is driven by the engine 14 via the speed increaser 12. The AC power generated by the generator 10 is rectified and sent to the inverter 16, and the inverter 16 generates a three-phase AC current. The three-phase alternating current drives the traveling motor 18. When the electric power generated by the generator 10 is larger than the electric power consumed by the traveling motor 18, the traveling battery 20 is charged as surplus electric power.
On the contrary, when the electric power generated by the generator 10 is insufficient, the electric charge stored in the traveling battery 20 is discharged and the electric power is supplied to the traveling motor 18.

Devices such as the generator 10, the engine 14 and the inverter 16 are each provided with an electronic control unit (ECU) for controlling in accordance with a running state or the like. Generator 1
0 is provided with a generator ECU 22.
Reference numeral 22 controls the field current or the like to control the power generation amount of the generator 10. The engine 14 is provided with an engine ECU 24. The engine ECU 24 controls the ignition timing and the fuel injection amount of the engine 14 to control the operation of the engine 14. The inverter 16 has an ECU (E
V-ECU) 26 is provided, and the EV-ECU 26 controls the inverter 16 according to the driver's operation of the accelerator pedal or the brake pedal to drive the motor 18 with a desired torque.

The traveling battery 20 has a battery ECU.
28 is provided, and the battery ECU 28 detects the amount of electricity stored in the traveling battery 20. FIG. 1 is a block circuit diagram showing the system configuration of the battery ECU 28. As shown in FIG. 1, the battery ECU 28 includes a voltage detection unit 280, a voltage increase rate calculation unit 281, and a power generation output decrease start voltage value setting unit 28.
2 and a generator voltage output control unit 283. The voltage detection unit 280 detects the voltage V _B of the traveling battery 20. In the voltage increase rate calculating unit 281, increase the proportion [Delta] V _B voltage V _B on the basis of the voltage V _B is calculated. The increase rate ΔV _B is calculated by the following equation (1) based on the voltage V _BN at the current cycle and the voltage V _Bn-1 at the previous cycle.

ΔV _B = (V _Bn −V _Bn−1 ) / (t _n −t _n−1 ) ... (1) where t _n is the time of the current cycle and t _n−1 is the previous time. Represents the time of each cycle.

The power generation output reduction start voltage value setting unit 282
A margin voltage calculation unit and a power generation output reduction start voltage value calculation unit are provided therein. The surplus voltage calculation unit uses the traveling battery 20.
Margin voltage value ΔV between the voltage upper limit limit value V _Bmax of the stored electricity and the power generation output reduction start voltage value V _{cutt at} which the power generation output of the generator 10 starts to decrease before the voltage upper limit limit value V _Bmax is reached. Calculate _c . The margin voltage value ΔV _c is calculated based on the graph shown in FIG. Increase rate of voltage V _B Δ
Increased increased margin voltage value [Delta] V _c with the the V _B, it increases the margin voltage value [Delta] V _c when increasing the ratio [Delta] V _B is large. The power generation output reduction start voltage value calculation unit calculates the power generation output reduction start voltage value V _cutt . The power generation output reduction start voltage value V _cutt is calculated by the following equation (2) based on the voltage upper limit value V _Bmax and the margin voltage value ΔV _c .

V _cutt = V _Bmax −ΔV _c (2) As shown in FIG. 1, the generator voltage output control unit 283 has a power generation reduction determination unit, a power generation reduction time control unit, a power generation reduction command control unit, etc. Is provided. In the power generation decrease determination unit,
It is determined whether or not the voltage V _B of the running battery 20 exceeds or does not exceed the power generation output reduction start voltage value V _cutt . When the voltage V _B does not exceed the power generation output reduction start voltage value V _cutt , normal power generation control is performed. When the voltage V _B exceeds the power generation output reduction start voltage value V _cutt , the generator 1
Power generation control is performed in which the power generation output of 0 is gradually reduced and the power generation output is stopped before the voltage upper limit limit value V _Bmax is reached.
In the power generation reduction time control unit, a time T _o for keeping the power generation output reduced is set, and when the power generation reduction determination unit determines that the voltage V _B exceeds the power generation output reduction start voltage value V _cutt , the time T _o Counting starts. The power generation decrease command control unit controls the power generator output command value P _G output from the power generator output command value calculation unit 36. By controlling the generator output command value P _G , the power generation output can be gradually reduced, and the power generation control can be performed so that the power generation output can be stopped before the voltage upper limit limit value V _Bmax is reached.

That is, in the hybrid electric vehicle according to this embodiment, the voltage V of the battery 20 for traveling is
Before reaching the upper limit voltage value V _Bmax of _B , the generator 1
The power generation output of 0 is gradually reduced, and the voltage upper limit limit value V _Bmax
The feature is that the power generation output can be stopped before it exceeds. By the time the voltage upper limit value V _Bmax of the running battery 20 is reached, the power generation output of the generator 10 can be reliably stopped, overcharging can be prevented, and the engine speed can be slowly changed, so emissions and fuel consumption can be improved. . Therefore, the life of the traveling battery 20 can be extended and the charging efficiency of the traveling battery 20 can be improved.

The vehicle speed of an electric vehicle having such a drive system is adjusted by controlling the output torque of the traveling motor 18. This control is performed by the EV-ECU 26 controlling the inverter 16 as described above. This is performed by adjusting the current value and frequency of the alternating current supplied to the motor 18. The EV-ECU 22 is based on the outputs of the accelerator sensor 30 and the brake sensor 32, which detect the operation amounts of the accelerator pedal and the brake pedal operated by the driver, and the output of the rotation sensor 34, which detects the rotation speed of the traveling motor 18, respectively. The command values of the conversion power and the conversion frequency of the inverter 16 are calculated. When the driver performs an operation of accelerating or traveling at a constant speed, the EV-ECU 22 operates the inverter 16
The electric power from the generator 10 or the traveling battery 20 is converted into a predetermined alternating current, and the converted electric power is supplied to the traveling motor 18. Further, when the driver performs a deceleration operation, the EV-ECU 22 similarly controls the inverter 16, and the traveling motor 18 now acts as a generator to convert the kinetic energy of the vehicle into electric energy. , So-called regenerative braking is performed.

In the present embodiment, a braking mechanism by mechanical frictional force is provided in addition to the regenerative braking. Therefore, in a hybrid electric vehicle, the vehicle is braked by two brake systems. Furthermore, EV-E
In the CU 22, the rotation direction of the traveling motor 18 can be controlled based on the output of the shift sensor 35, and forward / backward can be selected.

As described above, in the hybrid electric vehicle according to this embodiment, the electric power supplied to the traveling motor 18 changes according to the operation of the driver. Then, the electric power generated by the generator 10 is adjusted according to the electric power consumed by the traveling motor 18. That is, the electric power required to drive the traveling motor 18 does not have an excess or deficiency and the generator 10
Generated by the electric power for charging the running battery 20,
Also, the electric power discharged from the traveling battery 20 can be reduced, and a decrease in efficiency due to charge / discharge can be prevented. Generator 10
There is a one-to-one relationship between the generated power of the engine and the shaft output of the engine 14, and controlling the generated power is equivalent to controlling the shaft output of the engine 14. In other words, if the field current corresponding to the load of the shaft output of the engine 14 is controlled, the generator 10 is equivalent to the control of the shaft output of the engine 14.
The generated power of can be controlled.

Therefore, it is necessary to control the shaft output of the engine 14 in order to control the generated electric power. As a method for controlling the shaft output of the engine 14, a method based on the opening of the throttle valve is generally known. However, when the throttle valve is closed, a throttle loss occurs and the engine 14
The thermal efficiency of is reduced. Therefore, it is a good idea to fully open the throttle valve and change the output by changing the number of revolutions of the engine 14. However, engine 1
If only the control of the rotation speed of 4 occurs, there arises a problem that the purification effect of the exhaust gas is lowered and vibration occurs in the low rotation range,
In addition, there arises a problem that noise is generated in a high rotation range. Therefore, in the present embodiment, the shaft output of the engine 14 is controlled by the throttle opening in the low rotation speed range, and the shaft output is controlled by the exhaust gas recirculation rate (EGR rate) in the high rotation speed range.

The output control of the engine 14 will be described in detail below. As described above, in the EV-ECU 26,
The torque that the traveling motor 18 should generate is calculated from the driver's operation of the accelerator pedal, brake pedal, and shift lever. Then, the inverter 16 is controlled to reach the calculated output torque of the traveling motor 18. The torque command value T _M and the current motor speed N _{M at} this time are sent to the generator ECU 22. From the torque command value T _M and the rotation speed N _M , the traveling motor 18
Can be calculated, and the generator ECU 22 calculates the power to be generated by the generator 10 based on these command values. Further, the power to be generated is also changed depending on the state of charge (SOC) of the traveling battery 20. That is, when the traveling battery 20 is always in a fully charged state, the receptiveness of regenerative electric power becomes poor, and the regenerative braking force cannot be effectively recovered. In order to effectively recover the regenerative braking force, it is necessary to maintain the SOC below the fully charged state.
Further, if the SOC drops too much, the traveling battery 20 deteriorates more quickly, so it is necessary to maintain the SOC at a certain level or more and extend the life of the traveling battery 20. In this way, the SOC is controlled within an appropriate range from the viewpoints of ensuring the acceptability of regenerative power and extending the life of the battery 20 for traveling. Therefore, when the SOC falls below the lower limit value, the generator 10 operates at the maximum output, and when the SOC exceeds the upper limit value, the generator 10 operates at the minimum output. Therefore, the generator ECU 22 is connected to the SOC from the battery ECU 28.
Information D _SOC is sent. Based on the torque command value T _M of the traveling motor 18, the rotation speed N _M, and the SOC information D _SOC , the generator output command value calculation unit 3 in the generator ECU 22.
In 6, the electric power that the generator 10 should generate, that is, the generator output command value P _G is calculated. Generator output command value P _G
The calculation method of is as follows, for example.

First, the instantaneous power consumption P _M of the traveling motor 18 is calculated by the following equation (3) from the torque command value T _M and the rotational speed N _M.

P _M = k * T _M * N _M (3) where k is a proportional constant. Then, assuming that the average motor power consumption within a predetermined time is the required motor power P _GM , this required motor power P _GM is calculated by the following equation (4).

P _GM = ave (P _M ) ... (4) When the SOC falls below the lower limit value S _min , the generator output command value P _G is set to the maximum output value P _Gmax . On the contrary, SOC
Is greater than the upper limit value S _max , the generator output command value P _G is set to the minimum output value P _Gmin .

Next, the command value N _ref of the engine speed is calculated from the calculated generator output command value P _G. The command value N _ref of the engine speed is calculated based on the graph shown in FIG. As shown in FIG. 4, the generator output command value P
_In the normal range where _G is 6 to 18 kW, the command value N _ref of the engine speed is substantially proportional to the generator output command value P _G in the range of 1200 to 2800 rpm. Generator output command value P
_In the high output range where _G is 18 kW or more, the command value N _ref of the engine speed becomes a constant value at 2800 rpm. On the other hand, in the low output range where the generator output command value P _G is 6 kW or less, the engine speed command value N _ref is 1200 rpm.
Will be a constant value.

The control of the shaft output of the engine 14 differs depending on each of the above-mentioned rotation regions. Generator output command value P _G is 6-18 kW
In the normal range (1200 to 2800 rpm), the throttle opening and the exhaust gas recirculation rate (EGR rate) are fixed, and the shaft output of the engine 14 is controlled by the rotation speed. The shaft output of the engine 14 is represented by the product of the shaft torque and the rotation speed. Since the shaft torque of the normal engine 14 has a substantially constant value with respect to the rotation speed, the shaft output of the engine 14 is substantially proportional to the rotation speed. Therefore, if the rotation speed of the engine 14 increases, the power generation output of the generator 10 can also increase.
The throttle opening at this time is set to the fully open state so that there is no throttle loss. In the EGR rate, good thermal efficiency is obtained in the above-mentioned rotational speed range, and the harmful components in the exhaust gas are set to values that decrease. In this embodiment,
The EGR rate is 10% in terms of the weight ratio of the exhaust gas to the total cylinder intake gas amount.

The field control unit 40 calculates the field PWM duty ratio IF _PW on the basis of the rotation difference ΔN _e between the engine speed command value N _ref and the current engine speed N _e .
Based on the calculated field PWM duty ratio IF _PW, field PWM circuit 42 controls the field current I _f of the generator 10 can be controlled rotational speed of the engine 10. For example,
When the current engine speed N _e is lower than the command value N _ref , the field current _If is decreased. This reduces the output of the generator 10 and reduces the load on the engine 14. The rotation speed starts to increase as the load on the engine 14 decreases. When the engine speed N _e increases and coincides with the command value N _ref , the field control unit 40 controls the field PWM circuit 42, and the field current I _f commensurate with the shaft output of the engine 14 is sent out. The rise of N _e stops. Also,
When the engine speed N _e is reduced, the field current _If is once increased to increase the load of the engine 14 contrary to the above. The engine speed N _e decreases and the command value N _ref
, The field current _If is controlled to a value in which this rotational speed and the shaft output generated by the engine 14 are balanced. As described above, the shaft output of the engine 14 in the normal range is controlled. In this embodiment, the engine speed N _e is calculated by the engine ECU 24 based on the ignition pulse from the distributor 43.

In the high output range, if an attempt is made to increase the shaft output of the engine 14 depending on the number of revolutions, engine noise increases, which may give an occupant an unpleasant impression.
Therefore, the EGR rate is changed without increasing the engine speed beyond the upper limit rotation speed (2800 rpm in the case of this embodiment) that does not give passengers an uncomfortable feeling, and the increase in shaft output is controlled. As shown in FIG. 5, in the high output range, the EGR rate is decreased as the generator output command value P _G is increased. EGR
If the rate decreases, that is, if the amount of oxygen in the intake gas increases, more fuel can be burned per cycle, so the shaft torque can be increased and the shaft output can be increased. In this way, the shaft output of the engine 14 can be controlled in the high output range.

An EGR rate command value calculating section 44 for calculating the command value of the EGR rate is provided in the engine ECU 24. The EGR valve 46 that controls the EGR amount based on this command value is provided in the EGR pipe 52 that guides the exhaust gas from the exhaust pipe 48 of the engine 14 to the intake pipe 50. Even in the operating range where the EGR rate is constant, the intake air amount varies depending on the engine speed and the pressure in the intake pipe. Therefore, the EGR valve should be introduced so that exhaust gas corresponding to the intake air amount is introduced into the intake pipe. 46 is controlled by the engine ECU 24.

In the low output range, if the shaft output of the engine is reduced by the rotational speed, combustion in the cylinder becomes unstable and the vibration level deteriorates. Therefore,
From these viewpoints, the lower limit rotation speed (in the case of the present embodiment, 12
Below 100 rpm, the engine speed is not reduced and the reduction of the shaft output is controlled by changing the throttle opening.
As shown in FIG. 6, in the low output range, the throttle opening is reduced as the generator output command value P _G is reduced. If the throttle opening is decreased, that is, the intake air amount is decreased, the fuel burned per cycle can be decreased, and the throttle loss is also generated, so that the shaft torque can be decreased and the shaft output can be decreased. In this way, the shaft output of the engine 14 can be controlled in the low output range.

The throttle opening command value calculator 54 for calculating the throttle opening command value θ _ref is a generator ECU 2
It is provided in 2. Further, the throttle opening control unit 56 that controls the throttle opening by comparing the command value θ _ref with the current throttle opening information θ _TH is used by the generator ECU 22.
Provided within. The throttle opening control unit 56 sends a drive signal to the throttle valve actuator 60,
When the current throttle opening θ _TH is smaller than the command value θ _ref , the throttle valve 58 provided in the intake pipe is rotationally controlled in the opening direction. Conversely, when the current throttle opening θ _TH is larger than the command value θ _ref , the throttle valve 58 is rotationally controlled in the closing direction.

The method of controlling the shaft output of the engine 14 in each of the above operating ranges is summarized in FIG. That is, the shaft output of the engine 14 can be controlled by controlling the throttle opening degree in the low output range, controlling the engine speed in the normal range, and controlling the EGR rate in the high output range.

Next, a method of controlling the hybrid electric vehicle according to this embodiment will be described. FIG. 8 is a control flowchart of the hybrid electric vehicle.

First of all, the ignition switch IG
It is determined whether or not is turned on (S100).
When turned on, initialization is performed (S101), and at this time, it is determined whether or not any abnormality has occurred in the vehicle (S102). If no abnormality has occurred, the engine is started (S103).

Next, the abnormality confirmation such as whether the engine has started normally is performed again (S104). If there is no abnormality, the generator output command value calculation unit 36 of the generator ECU 22 calculates the generator output command value P _G (S10).
5). The calculation of the command value P _G is determined based on the torque T _M and the rotational speed N _M of the traveling motor 18 and the state of charge (SOC) of the traveling battery 20 as described above.

On the other hand, in the battery ECU 28, the voltage detector 280 detects the voltage V _B of the running battery 20, and the voltage increase rate calculator 281 detects the voltage V _B.
Rise ratio [Delta] V _B is calculated in the voltage V _B on the basis of _B (S
106). Then, based on the increase rate ΔV _B , the margin voltage value ΔV _c is calculated by the margin voltage calculation unit of the power generation output reduction start voltage value setting unit 282 (S107). FIG.
As shown in, the margin voltage value ΔV _c changes according to the increase rate ΔV _B , and as the voltage V _B rises rapidly and the increase rate ΔV _B is larger, the margin voltage value ΔV _c is set larger. Then, the power generation output reduction start voltage value V _cutt is calculated by the power generation output reduction start voltage value calculation unit based on the margin voltage value ΔV _c (S108).

Next, the power generation decrease determination unit of the generator voltage output control unit 283 determines whether or not the voltage V _B of the running battery 20 exceeds or does not exceed the power generation output decrease start voltage value V _cutt ( S109). When the voltage V _B does not exceed the power generation output reduction start voltage value V _cutt , normal power generation control is performed. When the voltage V _B exceeds the power generation output reduction start voltage value V _cutt , the power generation output of the generator 10 is gradually decreased, and power generation control is performed to stop the power generation output before reaching the voltage upper limit limit value V _Bmax. To be done.

The voltage V _B is the power generation output reduction start voltage value V _cutt
In normal power generation control that does not exceed the
Based on the generator output command value P _G sent from the generator output command value calculation unit 36 of U22, the engine speed command value N
_ref is calculated by the engine speed command value calculation unit 38 (S110). Further, the throttle opening θ _ref is calculated by the throttle opening command value calculation unit 54 (S1
11). Further, the generator output command value P _G is the engine EC
It is sent to U24 and the EGR rate command value is calculated by the EGR rate command value calculation unit 44 (S112).

Then, the field control processing is performed in the field control unit 40 based on the engine speed command N _ref and the engine speed difference ΔN _e between the current engine speed N _e (S11).
3). That is, based on the rotational speed difference ΔN _e , the field current P
The change amount of the WM duty ratio IF _PW is calculated, and the PWM control of the field current is performed by the changed duty ratio IF _PW . Further, the throttle opening control process is performed in the throttle opening control unit 56 (S114).
Further, in the engine ECU 22, control processing of the EGR valve is performed based on the above EGR rate (S11).
5).

Then, it is determined whether or not the ignition switch is turned off (S116), and steps S104 to S115 are repeated until the ignition switch is turned off. When the ignition switch is turned off, the ending process is performed (S117), and the control ends.

Further, step S102 and step S1
If the abnormality is confirmed in 04, processing such as notifying the abnormality to the driver is performed (S118). Then, it waits until the ignition switch is turned off, and when it is turned off, the ending process is performed.

In the power generation decrease determination unit of the generator voltage output control unit 283, when the voltage V _B of the running battery 20 exceeds the power generation output decrease start voltage value V _cutt , the generator voltage output control unit 283. In the power generation reduction time control unit of _{No. 2} , counting of the time T _o for keeping the power generation output reduced is started (S120). Then, the power generation decrease command control unit controls the power generator output command value P _G output from the power generator output command value calculation unit 36 (S121). By controlling the generator output command value P _G , the power generation output can be gradually reduced, and the power generation control can be performed so that the power generation output can be stopped before the voltage upper limit limit value V _Bmax is reached. FIG. 9 described above shows the relationship between the change in the generator output command value P _G and the voltage V _B of the traveling battery 20 at the set time T _o . And the generator output command value P _G is zero (kW)
It is determined whether or not (S122), and if the generator output command value P _G is not zero, the process returns from step S111 to step S116 and then to step S121 again to return to the generator output command value P _G. Will continue to decrease. When the generator output command value P _G becomes zero, it is determined whether the total power generation reduction time has reached the preset time T _o (S123). When the set time T _o has not been reached, the generator output command value P
_G continues to have zero kW. Time T _o is the value of, for example, about 30 seconds.

Embodiment 2 In the hybrid electric vehicle according to the present invention, the margin voltage value ΔV _c described in the above embodiment can be calculated also from the SOC value of the running battery 20. Figure 10 is a margin voltage value [Delta] V _c for determining the margin voltage value [Delta] V _c SO
It is a graph which shows the relationship with C. Basically, as described in the above embodiment, the margin voltage value ΔV _c increases as the SOC increases.

FIG. 11 is a control flowchart of the hybrid electric vehicle. The control method is basically the same as the control method described with reference to FIG. 8 in the above embodiment except for the method of determining the margin voltage value ΔV _c .

[0049]

As described above, according to the present invention, when the stored voltage of the running battery exceeds the power generation output reduction start voltage value calculated based on the increase rate of the charging voltage, the power generation output of the generator is reduced. It can be gradually reduced, and overcharging can be prevented by stopping the power generation output of the generator until the upper limit voltage of the running battery is reached, so the charging efficiency of the running battery can be improved and the life of the running battery can be reduced. It is possible to provide a hybrid electric vehicle that can be extended.

Further, in the present invention, the power generation output of the generator can be gradually reduced when the stored voltage of the running battery exceeds the power generation output reduction start voltage value calculated based on the charging state, and the running battery can be gradually reduced. A hybrid electric vehicle that can improve the charging efficiency of the running battery and extend the life of the running battery by stopping the power generation output of the generator and preventing overcharging before the voltage upper limit value of Can be provided.

[Brief description of drawings]

FIG. 1 is a block circuit diagram of a battery ECU of a hybrid electric vehicle according to a first embodiment of the present invention.

FIG. 2 is a block circuit diagram of a drive system of the hybrid electric vehicle.

FIG. 3 is a diagram showing a relationship between a voltage increase rate of a traveling battery and a margin voltage value.

FIG. 4 is a diagram showing a relationship between a generator output command value and an engine speed command value.

FIG. 5 is a diagram showing a relationship between a generator output command value and an EGR rate command value.

FIG. 6 is a diagram showing a relationship between a generator output command value and a throttle opening command value.

FIG. 7 is a diagram summarizing a method of controlling the engine output for each required generator output range.

FIG. 8 is a control flowchart.

FIG. 9 is a diagram showing a relationship between a stored amount and a generator output command value.

FIG. 10 is a diagram showing a relationship between SOC and a margin voltage value in the hybrid electric vehicle according to the second embodiment of the present invention.

FIG. 11 is a control flowchart.

[Explanation of symbols]

10 generator, 14 speed increaser, 16 inverter, 18
Motor, 20 running battery, 22 generator EC
U, 24 engine ECU, 26 EV-ECU, 28
Battery ECU, 36 Generator output command value calculation unit, 38
Engine speed command value calculation unit, 40 Field control unit, 44
EGR rate command value calculation unit, 46 EGR valve, 54
Throttle opening command value calculation unit, 56 Throttle opening control unit, 58 Throttle valve, 60 Throttle actuator, 280 Voltage detection unit, 281 Voltage increase rate calculation unit, 282 Generation output decrease start voltage value setting unit, 28
3 Generator voltage output control section.

Claims (2)

[Claims] 1. A traveling motor equipped with a generator driven by an engine, a traveling battery and a traveling motor, and at least one of electric power generated by the generator and electric power stored in the traveling battery. In a hybrid electric vehicle driven by, a voltage increase rate calculation means for calculating an increase rate of the voltage charged in the running battery; and a voltage increase rate calculated by the voltage increase rate calculation means A power generation output decrease start voltage value setting means for setting a power generation output decrease start voltage value that starts decreasing the power generation output of the generator before reaching the voltage upper limit value of the drive battery, and a voltage value of the drive battery When the power generation output reduction start voltage value is compared and the voltage value of the traveling battery exceeds the power generation output reduction start voltage value, A generator voltage output control means for gradually decreasing the power generation output from the power generation output reduction start voltage value to the voltage upper limit value, and stopping the power generation output of the generator until the voltage upper limit value is reached, A hybrid electric vehicle characterized by being equipped with. 2. A traveling motor equipped with a generator driven by an engine, a traveling battery and a traveling motor, and at least one of electric power generated by the generator and electric power stored in the traveling battery. In the hybrid electric vehicle driven by, based on the state of charge of the traveling battery, a power generation output reduction start voltage value that starts decreasing the power generation output of the generator before the voltage upper limit limit value of the traveling battery is reached. Power generation output reduction start voltage value setting means for setting, the voltage value of the traveling battery and the power generation output reduction start voltage value are compared, the voltage value of the traveling battery exceeds the power generation output reduction start voltage value In the case of, the power generation output is gradually reduced from the power generation output reduction start voltage value to the voltage upper limit value, Hybrid electric vehicle, characterized in that the power output of the generator comprising: a generator voltage output control means for stopping, the before.