JP3209127B2 - Power generation control device for hybrid electric vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power generation control apparatus for a hybrid electric vehicle, and more particularly to a power generation control technique when the vehicle stops.

[0002]

2. Description of the Related Art In recent years, technical development of electric vehicles has been advanced from the viewpoint of low pollution and energy saving.
A so-called hybrid electric vehicle including an engine-driven generator as a power supply source of a vehicle drive motor and a battery charger has attracted attention. In such a hybrid electric vehicle, a generator having an output smaller than the output of the driving motor is often used.

For this reason, various measures have been taken to prevent a decrease in the state of charge (SOC) of the battery, such as generating electricity when the motor load for driving the vehicle is light, such as when the vehicle is stopped or coasting down. I have. In particular, a control is employed in which the generator is driven to charge the battery and recover the SOC value within a range (about several kw) where the engine noise is not a concern when the vehicle is stopped. That is, while the vehicle is stopped, power is generated at the maximum output allowable from the viewpoint of engine noise, and the SOC
The charging is continued until the value reaches a preset value.

On the other hand, in a battery mounted on a vehicle, so-called gassing occurs, in which the amount of gas generated from the electrolyte rapidly increases at the end of charging. In order to avoid this gassing, a control is adopted in which it is estimated that gassing will occur when the voltage between the terminals of the battery exceeds a predetermined gas generation voltage, power generation is stopped for 5 seconds, and then power generation is restarted. I have.

[0005]

However, when the battery temperature is low, such as in the morning of winter, or when the battery has deteriorated, the internal resistance of the battery increases and the voltage across the terminals of the battery tends to increase. Therefore, when the voltage between the terminals of the battery exceeds the gas generation voltage during power generation while the vehicle is stopped, even if power generation is stopped for 5 seconds and then power generation is restarted, almost Since the power consumption is not performed, the voltage between the terminals of the battery immediately exceeds the predetermined gas generation voltage. For this reason, a so-called hunting phenomenon occurs, and not only does the fuel efficiency of the driving engine of the generator decrease, but also a problem arises that the passenger is uncomfortable.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a power generation control device for a hybrid electric vehicle which can avoid a hunting phenomenon of a driving engine of a generator while the vehicle is stopped. Make it an issue.

[0007]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a generator driven by an engine, a battery for receiving power generated by the generator and supplying power to a vehicle drive motor. A power generation control device for a hybrid electric vehicle, comprising: a gassing determination unit configured to determine whether gassing of the battery has occurred; and a generator configured to determine that the gassing has occurred when the vehicle is stopped. Power supply limiting means for limiting power supply to the battery; and
After restriction of the power supply, the state of charge of the battery is given by
Wherein a power storage state reduction determining means for determining that it has decreased more than the amount, if under low is determined, in that it comprises a power supply limit canceling means for canceling the limitation of the power supply by the power supply limiting means And

According to the present invention, first, the gassing judging means includes the voltage between the terminals of the battery, the SOC of the battery.
The presence or absence of battery gassing is determined based on the value or a signal from the gas sensor. Then, if it is determined that gassing has occurred, the power supply limiting unit reduces the number of revolutions of the engine that drives the generator, or reduces the engine to supply power to the battery by the generator. Restrict. Thereafter, the storage state reduction determining unit directly or indirectly lowers the storage state of the battery by a predetermined amount or more based on the integration of the current supplied to the battery or based on the power consumption of the motor or the like. Determine what you have done. Then, when the low under charge state of the battery is determined, the power supply restriction releasing means releases the restriction of the power supply of the battery.

With this configuration, power supply to the battery, which is not particularly limited, is not restarted when the battery is fully charged. As a result, according to the present invention, it is possible to avoid the hunting phenomenon of the engine for driving the generator while the vehicle is stopped, and to improve the fuel efficiency of the engine for driving the generator. In addition, it is possible to prevent the passenger from feeling uncomfortable due to the engine sound.

[0010] Incidentally, as one of the desirable embodiments of the present invention,
The storage state reduction determining means may be configured to determine a reduction in the storage state based on a history of the running state of the vehicle. With this configuration, it is possible to easily determine a decrease in the state of charge of the battery with a small error compared to current integration or the like.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a system configuration of a hybrid electric vehicle. The generator 10 is driven by the engine 10, and the generated power drives the motor 16 via the inverter 14. Also, the generator 1
When the electric power generated by the motor 2 is smaller than the electric power consumed by the motor 16, the electric power stored in the battery 18 is further added to drive the motor 16. The rotation of the motor 16 is transmitted to the wheels 22 via the speed reducer 20, and the vehicle is driven. In addition to braking by a mechanical brake, so-called regenerative braking that controls the inverter 14 so that the motor 16 acts as a generator and charges the battery 18 with the generated power is used for braking the vehicle. Can be

The operation control of each section is performed by each electronic control unit (ECU) shown in the figure. EV-ECU2
Reference numeral 4 controls the inverter 14 based on the operation amount of an accelerator pedal or a brake pedal (not shown) and the rotation speed of the motor 16 to operate the motor 16 at a desired rotation speed and a desired torque. The generator ECU 26 basically controls the generator 12 and the engine 10 so as to generate electric power corresponding to the electric power consumed by the motor 16, and based on the SOC value input from the battery ECU 30, If it is determined that the power storage state of the battery 18 has decreased, the power supply to the battery 18 is performed to supplement the decrease. At this time, when the terminal voltage VB of the battery 18 input from the battery ECU 30 exceeds the gas generation voltage VBmax set in advance, the battery 18
Control to limit power supply to the The engine 10
The throttle valve 28 is normally operated with the throttle valve 28 fully open (WOT) in order to maintain good fuel economy and to keep emissions at the lowest possible level. For this reason,
The generator ECU 26 controls the amount of power generation by controlling only the field current supplied to the generator 12 in principle. Then, only when the throttle operation is necessary for efficiency, the opening degree of the throttle valve 28 is operated.

Hereinafter, the power generation control process of the generator ECU 26 in the hybrid electric vehicle having such a configuration will be described in more detail with reference to the flowcharts of FIGS.

In executing the processing shown in these figures, a power generation prohibition flag fpginh indicating that power generation by the generator 12 is to be prohibited is stored in a memory (not shown) provided in the A storage area for a minimum power generation instruction flag fpgmin for instructing power generation and a variable SOCSTOP for storing the SOC value of the battery 18 at the time when the power supply to the battery 18 is stopped by the control described later is secured. You.

First, the generator ECU 26 is an EV-ECU.
It is determined whether or not the vehicle speed input from 24 has reached a certain speed, thereby determining whether or not the vehicle is stopped (S1). If the vehicle is stopped, it is determined whether or not the SOC value of battery 18 input from battery ECU 30 is less than the upper limit SOC value at which power generation is permitted (S2). The engine 10 is configured to perform 0 kW power generation on the assumption that the battery 18 does not need to be charged.
Then, the generator 12 is controlled (S3). On the other hand, if the vehicle is not stopped (S1), a process for canceling the power generation restriction is performed as described later with reference to FIG. If the SOC value of the battery 18 is less than the upper limit value at which power generation is permitted (S2), it is determined whether the value of the power generation prohibition flag fpginh is 1 (S4). If the value of the power generation prohibition flag fpginh is 1 and it is instructed that power generation by the generator 12 should be prohibited, the engine 10 to the generator 12 are controlled to generate 0 kW power (S5). Also, the value of the power generation prohibition flag fpginh is 0, and the generator 1
If the power generation by No. 2 is not prohibited, it is next determined whether or not the value of the minimum power generation instruction flag fpgmin is 1 (S6).

If the value of the minimum power generation instruction flag fpgmin is 1, the engine 10 to the generator 12 are controlled so as to generate power at the minimum output (here, 3 kW) that the engine 10 and the generator 12 can perform. (S7). At this time, the voltage VB between the terminals of the battery 18 becomes the gas generation voltage VB.
If a signal indicating that the power generation has exceeded the maximum is input from the battery ECU 30 (S8), in order to temporarily stop the subsequent power generation,
1 is stored as the value of the power generation prohibition flag fpginh (S9), and the current SOC value of the battery 18 input from the battery ECU 30 is stored as the value of the variable SOCSTOP (S10). On the other hand, if the terminal voltage VB of the battery 18 does not exceed the gas generation voltage VBmax (S8), the minimum power generation is maintained.

On the other hand, if the value of the minimum power generation instruction flag fpgmin is 0 (S6), the engine 10 through the generator 10 generate electric power at the maximum output (here, 7 kW) permitted when the vehicle is stopped from the viewpoint of engine noise. 12 (S1
1). At this time, a signal indicating that the inter-terminal voltage VB of the battery 18 has exceeded the gas generation voltage VBmax is output from the battery ECU.
If it is input from S30 (S12), 1 is stored as the value of the minimum power generation instruction flag fpgmin in order to limit the subsequent power generation to the minimum output (S13).

Next, after the vehicle starts running (see S1 in FIG. 2).
The power generation control of the generator ECU 26 in FIG.
Description will be made based on the flowchart shown in FIG. As shown in the figure, the generator ECU 26 firstly operates the battery ECU 3.
It is determined whether the SOC value input from 0 is smaller than a value obtained by subtracting a constant value from the value of the variable SOCSTOP already stored in the memory (S101, see S10 in FIG. 2). If it is smaller, it is determined that a certain amount of power of the battery 18 has been consumed, and the minimum power generation instruction flag f
pgmin, power generation prohibition flag fpginh, and variable SOCST
The value of OP is reset to 0 (S102), and returns to the power generation normally performed during traveling (S103). When the SOC value is larger than a value obtained by subtracting a constant value from the value of the variable SOCSTOP, the engine 10 to the generator 12 are controlled so as to generate power with a lower output than normal power generation performed during traveling ( S104). According to the above-described processing, it is determined that the power storage state of battery 18 has decreased based on the SOC value input from battery ECU 30, and the restriction on power supply to battery 18 by generator 12 is released based on the result. Can be.

According to the power generation control process of the hybrid electric vehicle described above, when the terminal voltage VB of the battery 18 exceeds the gas generation voltage VBmax while the vehicle is stopped, first,
Power generation with minimum output is performed. After that, the battery 1 again
When the terminal voltage VB exceeds the gas generation voltage VBmax, the generator 12 generates 0 kW power. Further, even after the vehicle starts running, normal power generation is not restarted immediately, and power generation with suppressed output is performed. In this way, when gassing occurs while the vehicle is stopped, power supply to the battery 18 by the generator 12 is limited.

The power supply is limited until the state of charge of the battery 18 is reduced.
When the power storage state of the battery 18 decreases, the power supply restriction is released, and the normal power supply to the battery 18 by the generator 12 is resumed. In this way, the power supply to the unlimited battery 18 is not restarted when the battery 18 is fully charged. As a result, the hunting phenomenon of the engine 10 while the vehicle is stopped can be avoided, and the fuel efficiency of the engine 10 can be improved. Further, it is possible to prevent the sound of the engine 10 from giving the passenger discomfort.

The power generation control process of the hybrid electric vehicle described above can be implemented in various modifications. For example, in the above description, a decrease in the state of charge of the battery 18 based on the SOC value is determined. Instead, the decrease in the state of charge of the battery 18 is determined based on the running state history of the vehicle, as shown in FIG. You may decide. According to the flowchart shown in the figure, the generator ECU 26 first sets the EV-EC
Based on the vehicle speed input from U24, it is determined whether the vehicle is running at a speed equal to or higher than a certain speed for a certain time (S20).
1). If the vehicle has been running at a speed higher than a certain speed for a certain period of time, it is determined that a certain amount of power has been consumed by the battery 18, and the values of the minimum power generation instruction flag fpgmin and the power generation prohibition flag fpginh are reset to 0. (S2
02), return to normal power generation performed during traveling (S2)
03). On the other hand, if the vehicle has not traveled at a speed equal to or higher than a certain speed for a certain time, the engine 10 to the generator 12 are controlled so as to generate power at a lower output than normal power generated during running (S204). In this way, it is possible to indirectly determine a decrease in the state of charge of the battery 18 based on the history of the running state of the vehicle, and release the restriction on the power supply to the battery 18 by the generator 12 based on the result. .

Alternatively, as shown in FIG. 3C, it may be estimated that the state of charge of the battery 18 has decreased after a certain period of time has elapsed after the start of vehicle running. In the execution of the control processing of the figure, a storage area for a variable tpg representing the elapsed time since the vehicle restarted traveling is further secured in a memory (not shown) provided in the generator ECU 26, and 0 is stored as an initial value. You. When the vehicle starts running (S1 in FIG. 2), the generator ECU 26 first checks the value of the variable tpg to determine whether or not a predetermined time has elapsed after the start of the vehicle running (S301). If the predetermined time has not elapsed, a certain number is added to the value of the variable tpg (S302), and the engine 10 to the generator 12 are controlled so as to perform power generation with a lower output than normal power generation during running (S302). S303). On the other hand, if a certain period of time has elapsed after the start of traveling of the vehicle (S30)
1) Store 0 in the minimum power generation instruction flag fpgmin, the power generation prohibition flag fpginh, and the variable tpg and reset them (S3).
04), it is determined that the storage state of the battery 18 has decreased, and the restriction on the power supply to the battery 18 by the generator 12 is released, and the power generation returns to the normal power generation (S305). Even in this case, it is possible to easily determine a decrease in the state of charge of the battery 18 and release the restriction on the power supply to the battery 18 by the generator 12.

[Brief description of the drawings]

FIG. 1 is a diagram showing a system configuration of the present hybrid electric vehicle.

FIG. 2 is a flowchart illustrating processing of a generator ECU.

FIG. 3 is a flowchart illustrating processing of a generator ECU.

[Explanation of symbols]

10 engine, 12 generator, 16 motor, 18
Battery, 24 EV-ECU, 26 generator ECU,
30 Battery ECU.

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B60L ⁷ /00-13/00 B60K 6/02 B60L 3/00 G01R 31/36 H01M 10/48

Claims (2)

(57) [Claims] 1. A power generation control device for a hybrid electric vehicle, comprising: a generator driven by an engine; and a battery that receives power generated by the generator and supplies power to a vehicle drive motor, a gassing determination means for determining occurrence of gassing of the battery, when the fact that the gassing has occurred is determined when the vehicle is stopped, and the power supply limiting means for limiting the power supply to the battery by the generator, the after restriction of the power supply by the power supply limiting means, a charge state reduction determining means for determining that the state of charge of the battery has dropped more than a predetermined amount, when under low is determined, the power by the power supply limiting means A power supply control device comprising: a power supply restriction release unit that releases a supply restriction. 2. The power generation control device according to claim 1, wherein the storage state reduction determination unit determines the reduction in the power storage state based on a history of a running state of the vehicle.