JPH0998513A - Charge / discharge control device for hybrid electric vehicle - Google Patents

Abstract

The present invention relates to a charge / discharge control device for a hybrid electric vehicle including a generator driven by a prime mover,
While ensuring an initial battery travel distance and suppressing the travel ratio of power generation travel, power generation (charging) can be performed in a charging rate region with good charging efficiency during power generation travel. In a charging / discharging control device for a hybrid electric vehicle that performs a charging control for driving a generator by a vehicle-mounted prime mover to charge a battery, a charging rate at the start of initial charging and a charging rate at the end of initial charging are Set lower than the optimum charging range with good charging efficiency, and after the initial charging, perform the intermediate charging process in which the charging rate at the start of charging and the charging rate at the end of charging are closer to the optimal charging range than this initial charging It is configured to be able to shift to charging by range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hybrid electric vehicle provided with a generator and a prime mover for driving the generator so that the vehicle can travel while generating electric energy. The present invention relates to a charging / discharging control device for a hybrid electric vehicle, which controls the running of electric power.

[0002]

2. Description of the Related Art In recent years, so-called electric vehicles, which do not directly emit exhaust gas, have been attracting attention in automobiles. However, in electric vehicles, a battery, which is an energy source, corresponds to gasoline replenishment in a gasoline automobile. If the remaining capacity of the
The current situation is that this battery cannot be charged as easily as gasoline replenishment. For this reason, when the vehicle stops on the road due to insufficient battery capacity, it is not easy to take measures against the stop.

Therefore, a so-called series hybrid electric vehicle (hereinafter, abbreviated as a hybrid electric vehicle) in which a generator is mounted on the electric vehicle itself has been considered.
Various technologies have been proposed for such a hybrid electric vehicle. In a hybrid electric vehicle equipped with a generator as described above, a traveling mode (EV traveling mode) in which the vehicle is driven by operating the motor with the electric power stored in the battery and the generated electric power generated by the generator while being generated. The drive mode for driving the vehicle (power generation drive mode or HEV drive mode) can be selected by.

The control of power generation in such a hybrid electric vehicle is based on the remaining capacity of the battery, as disclosed in, for example, the power generation control method for hybrid electric vehicles and its apparatus disclosed in Japanese Patent Application Laid-Open No. 50-21210. It is common practice. That is, for example, as shown in FIG. 5, when the vehicle runs in the EV running mode [initial battery running indicated by], which does not generate power using the battery fully charged by external charging, the battery charge rate (battery remaining) gradually increases. Capacity) C (%) decreases. When the charging rate C decreases to a predetermined value (power generation start charging rate) C1, the generator is operated to switch to the HEV traveling mode [hybrid traveling]. Of course, if the vehicle is fully charged by external charging before the remaining capacity C decreases to the predetermined value C1, the EV running mode [initial battery running indicated by] can be continued.

If the EV traveling mode is too long, the temperature of the exhaust gas purifying catalyst of the engine for driving the generator is lowered and the purifying ability is deteriorated. In this respect also, the duration of the EV traveling mode is regulated. It In the HEV running mode, power is generated by operating the power generation engine and rotationally driving the turbine of the generator. Generally, the engine rotation speed and output torque (power generation load) have high power generation efficiency and exhaust gas can be easily purified. The generator is driven by to obtain a constant power output. The power output by such a generator is set to a certain level or higher so as to cover normal traveling.

That is, when a certain amount of generated power is generated by the generator in the power generation running mode, if this capacity is small, the power consumption rate during high-speed running (power consumption required for running per unit running time) When the vehicle travels with a large amount of electricity, the generated power is less than the power consumption, and the battery continues to be discharged, causing the battery to run out. Therefore, conventionally, the magnitude of the power generation output is set to be sufficiently large so that the power at a high power consumption rate can be covered by the generator. For this reason,
During the power generation running mode, normally, as shown in FIGS.
The charging and discharging of the battery will be repeated.

That is, during power generation travel [during hybrid travel indicated by], as shown in FIG. 5, the generated power exceeds the power consumption, and the battery is charged. When the charging rate C of the battery recovers to a predetermined value (power generation stop charging rate) C2, the engine for power generation and the generator are stopped,
Run the battery indicated by. Then, when the vehicle is driven again by discharging the battery, the charging rate C of the battery decreases to the power generation start charging rate C1, so the engine for power generation and the generator are operated again, and power generation traveling [hybrid traveling] is performed. To do.

Therefore, in the HEV running mode, the engine and generator for power generation are operated and stopped, that is, the electric power running and the battery running are repeated.

[0009]

By the way, as described above, the essential advantages of the electric vehicle are that the motor of the driving source does not emit exhaust gas and that the motor is quieter than the internal combustion engine, as shown in FIG. This advantage cannot be used in the hybrid driving shown in (4). Therefore, the power generation start charging rate is set as low as possible in order to maximize the traveling distance with only the initial battery shown in the traveling model shown in FIG.

However, if the power generation start charging rate is set low in this way, charging may occur in a charging rate region where the charging efficiency of the battery is poor. In this case,
There is a possibility that the fuel efficiency of the internal combustion engine for power generation during hybrid traveling deteriorates, leading to an increase in exhaust gas. However, if the battery is charged by the hybrid drive all at once in a region where the charge rate of the battery is extremely high, the power generation rate is increased, and the above-mentioned inherent advantages of the electric vehicle cannot be obtained.

The present invention was devised in view of the above-mentioned problems, and secures an initial battery traveling distance and suppresses the traveling ratio of power generation traveling (hybrid traveling) to generate the original exhaust gas of an electric vehicle. Without taking advantage of its high quietness, power generation (charging) can be avoided as much as possible in the charging rate region where charging efficiency is poor during power generation running,
An object of the present invention is to provide a charge / discharge control device for a hybrid electric vehicle, which can prevent deterioration of fuel efficiency of an internal combustion engine for power generation and reduce exhaust gas.

[0012]

Therefore, the charging / discharging control device for a hybrid electric vehicle according to the present invention according to the first aspect of the present invention has a discharge control for driving an electric motor by a battery mounted on the vehicle to drive the vehicle, as well as an onboard vehicle. In a charging / discharging control device for a hybrid electric vehicle that performs a charging control for driving a generator by a prime mover to charge the battery, an initial state in which the charging state of the battery is smaller than an optimal charging start state from a substantially fully charged state. An initial charge start state determination means for determining that the battery has been discharged to the charge start state, and when the determination signal from the initial charge start state determination means is received, the prime mover is operated to generate power to bring the battery from the optimum charge end state. Is smaller than the initial charge control state, and the charge state of the battery is determined by the discharge after the initial charge is completed. An intermediate charging start state determining means for determining that the battery has been discharged from the charging end state to an intermediate charging start state smaller than the optimum charging start state and larger than the initial charging start state, and the intermediate charging start state determining means. When the determination signal is received, the prime mover is operated to generate electric power to charge the battery to an intermediate charge end state that is smaller than the optimum charge end state and larger than the initial charge end state, and the intermediate charge control means. The state of charge of the battery due to discharge after the end of the intermediate charge end state,
The optimal charging start state determining means for determining that the battery has been discharged to the optimal charging start state, and when the determination signal from the optimal charging start state determining means is received, the prime mover is operated to generate power to optimally charge the battery. It is characterized by having an optimum charging control means for charging to the end state.

According to a second aspect of the present invention, there is provided a charge / discharge control device for a hybrid electric vehicle according to the first aspect, wherein the intermediate charging start state and the intermediate charging end state gradually increase the charging state. And a plurality of sets of the intermediate charge control means are provided, and the intermediate charge control means is configured to perform the intermediate charge control a plurality of times in accordance with the plurality of intermediate charge start states and intermediate charge end states. It is characterized in that the optimal charging control is performed through the intermediate charging control performed a plurality of times.

According to a third aspect of the present invention, there is provided a charge / discharge control device for a hybrid electric vehicle according to the first or second aspect, wherein the intermediate charge control means performs the final intermediate charge until the optimum charge start state is reached. It is characterized in that charging is performed from the final intermediate charging disclosure state that does not reach to the optimum charging end state.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION A charge / discharge control device for a hybrid electric vehicle as an embodiment of the present invention will be described below with reference to FIGS. In FIG. 1, reference numeral 1 is a battery, and the battery 1 can be repeatedly charged by a generator 6 (described later) mounted on the vehicle or an external charger (not shown) not equipped on the vehicle. Reference numeral 2 denotes a motor (a traveling electric motor) supplied with electric power from the battery 1. The motor 2 drives the drive wheels 3A and 3B of the automobile.

The output of the motor 2 is controlled by a motor controller (electric motor control means) 4 on the basis of a driver's output request operation (that is, a depressing state of an accelerator pedal (not shown)) or a current operating state of the motor 2. . Also,
When the motor controller 4 detects a braking command from depression of a brake pedal (not shown) or the like, the motor 2 is switched to a generator, and regenerative braking can be performed by applying a braking force while generating electric power with the rotational energy from the drive wheels 3A and 3B. It has become so.

Reference numeral 5 denotes an APU (Auxiliary Power Unit), which is composed of a generator 6 and a power generating internal combustion engine (hereinafter referred to as engine) 7 which is a prime mover for driving the generator 6. The APU 5 is connected to the battery 1 so that the battery 1 can be charged with the electric power generated by the generator 6. The control of the APU 5 (the generator 6 and the engine 7) is performed by the traveling management controller 9 together with the control of the motor controller 4.

The running management controller 9 includes
In terms of hardware, it has a CPU (not shown) as its main part, and also has a ROM (not shown) for storing fixed value data and the like.
Also, the calculation for controlling the motor controller 4 and the output of the control signal are performed. In this electric vehicle,
Through the APU controller 10 in the travel management controller 9, the vehicle is driven by operating the engine 7 to operate the motor 2 while charging the battery 1 with the electric power generated by the generator 6 (hybrid travel or Power generation traveling or HEV traveling) and traveling traveling the vehicle by driving the motor 2 by stopping the engine 7 and operating the electric power stored in the battery 1 (referred to as battery traveling or EV traveling). It is designed to be used.

The APU control unit 10 includes a storage unit 11 and
The calculating unit 12, the determining unit 13, and the commanding unit 14 are provided, and the detected charging rate (remaining capacity) of the battery 1 is provided.
C is the initial power generation start charging rate C1 stored in the storage unit 11.
When it decreases to, the determination means 13 determines to perform power generation travel, and the command means 14 commands power generation travel (hybrid travel).

Then, when this power generation running is started, based on the detection information from the remaining capacity detecting means (remaining capacity meter) 8,
With the characteristics shown in FIG. 2, power generation traveling and battery traveling are repeated. That is, in order to increase the initial battery running as much as possible, the charging rate for starting the first power running from the substantially fully charged state, that is, the initial power generation start charging rate (charging rate in the initial charging start state) Cs0 is set to the lowest possible value. ing. That is, the power generation region (charge region) with the highest charging efficiency is from the optimum power generation start charging rate (charge rate in the optimum charge start state) Cs1 to the optimum power generation end charge rate (charge rate in the optimum charge end state) Ce1 shown in FIG. However, the initial power generation start charge rate (charge rate in the initial charge start state) Cs0
Is set to a charging rate that is much lower than this region.

Further, since the power generation running rate inevitably increases if the power generation running is continued for a long time, the initial power generation end charging rate (the charge rate in the initial charging end state) is regulated in order to regulate one continuous power generating running. Ce0 is also set lower than the optimum power generation range (between Cs1 and Ce1). Of course, if the optimum power generation range (between Cs1 and Ce1) is close to the initial power generation start charge rate Cs0, the initial power generation end charge rate Ce0
May be set within the range of the optimum power generation range (between Cs1 and Ce1), and the initial power generation end charge rate (charge rate in the initial charge end state) Ce0 is at least equal to or less than the optimum power generation end charge rate Ce1. Set.

The determination means 13 is provided with an initial charge start state determination means 13A for determining that the charge rate has reached the initial power generation start charge rate Cs0, and the instruction means 14 is provided for the initial charge start state determination means 13A. When it is determined that the charging rate has reached the initial power generation start charging rate Cs0, the initial power generation command means (initial charging control means) for instructing the power generation running only until the charging rate reaches the initial power generation end charging rate Ce0.
14A is provided.

By the control of the initial power generation command means 14A, when the initial power generation end charging rate Ce0 can be charged, the initial power generation running is terminated. As a result, the discharge of the battery 1 is started again, and next, when the charging rate of the battery 1 is discharged to the intermediate power generation start charging rate (charging rate in the intermediate charging start state) Cs, thereafter, the charging rate of the battery 1 ends the intermediate power generation. The intermediate power generation running is performed only until the charging rate (the charging rate in the intermediate charging end state) Ce is reached.

Therefore, the determination means 13 is provided with an intermediate charge start state determination means 13B for determining that the charge rate has reached the intermediate power generation start charge rate Cs, and the instruction means 14 is provided with the intermediate charge start state determination means. If it is determined in 13B that the charging rate has reached the intermediate power generation start charging rate Cs, intermediate power generation command means (intermediate charging control means) that commands power generation running only until the charging rate reaches the intermediate power generation end charging rate Ce. 14
B is provided.

The intermediate power generation start charging rate Cs and the intermediate power generation end charging rate Ce differ depending on the number of times of intermediate power generation. For example, as shown in FIG. 2, the intermediate power generation is performed three times after the initial power generation, that is, a total of 4 times. In order to start optimum power generation after running once, for example, using the following formula,
1st intermediate power generation start charge rate Cs (1), 2nd intermediate power start charge rate Cs (2), 3rd intermediate power start charge rate Cs
(3) can be set respectively. 1st intermediate power generation end charging rate Ce (1), 2nd intermediate power generation end charging rate C
e (2) and the third intermediate power generation end charging rate Ce (3) can be set respectively. Cs (1) = Cs0 + (Cs1-Cs0) / 4 = (3.Cs0 + Cs1) / 4 Cs (2) = Cs (1) + (Cs1-Cs0) / 4 = (2.Cs0 + 2.Cs1) / 4 Cs ( 3) = Cs (2) + (Cs1-Cs0) / 4 = (Cs0 + 3.Cs1) / 4 Ce (1) = Ce0 + (Ce1-Ce0) / 4 = (3.Ce0 + Ce1) / 4 Ce (2) = Ce (1) + (Ce1-Ce0) / 4 = (2.Ce0 + 2.Ce1) / 4 Ce (3) = Ce (2) + (Ce1-Ce0) / 4 = (Ce0 + 3.Ce1) / 4 Intermediate power generation start charging rate Cs (1), Cs
(2), Cs (3) and each intermediate power generation end charging rate Ce
Although (1), Ce (2), and Ce (3) are calculated by the calculation means 12, the values calculated in advance may be stored in the storage means 11.

In this way, each intermediate power generation start charging rate Cs
By setting (1), Cs (2), Cs (3) and each intermediate power generation end charging rate Ce (1), Ce (2), Ce (3), the charging rate region for performing intermediate power generation is gradually increased. After approaching the optimum power generation range (between Cs1 and Ce1) and reaching the third intermediate power generation end charging rate Ce (3), discharging of the battery 1 starts again, and this time, the charging rate of the battery 1 is optimum power generation. After discharging to the start charge rate (charge rate in the optimum charge start state) Cs1, thereafter, the optimum power generation running is performed until the charge rate of the battery 1 reaches the optimum power generation end charge rate (charge rate in the optimum charge end state) Ce1. Do. After this, after discharging again to the optimum power generation start charging rate Cs1, the optimum power generation running is performed until the optimum power generation ending charge rate Ce1 is reached.
Power generation traveling (optimum power generation traveling) and battery traveling are repeated.

Therefore, the judging means 13 is provided with an optimum charging start state judging means 13C for judging that the charging rate has reached the optimum power generation start charging rate Cs1, and the instructing means 14 is provided.
When the optimal power generation start state determination means 13C determines that the charging rate has reached the optimal power generation start charging rate Cs1, the optimal power generation that commands power generation running only until the charging rate reaches the optimal power generation end charging rate Ce1. A command means (optimum charge control means) 14C is provided.

In the present embodiment, the intermediate power generation run is repeated three times, and then the minimum power generation run is executed.
The number of times of intermediate power generation travel is not limited to this, and may be once or twice as shown in FIG.
May be more than 3 times. Further, in this embodiment,
The starting charge rate and the ending charge rate from initial power generation to intermediate power generation to optimum power generation are increased by the same rate as after each power generation, but the first intermediate power generation for the initial power generation and the third intermediate power generation for the second intermediate power generation The start charge rate and the end charge rate of the optimum power generation for the third intermediate power generation and the third intermediate power generation generally have to be gradually increased as shown in FIG. 4, and are partially equal. Good.

Further, the power generation end charging rate by the final intermediate power generation may be the optimum power generation end charging rate Ce1. This allows
You can quickly shift to optimal charging. Since the electric vehicle as one embodiment of the present invention is configured as described above, battery running and power generation running are controlled in the mode shown in FIG. This control will be described below with reference to the flowchart of FIG. 3, for example, in the case where the optimum power generation is started after the power generation traveling is performed n times in total.

That is, if control is started immediately after full charge,
First, with the initial power generation start charging rate Cs0, the initial power generation ending charging rate Ce0, the optimum power generation starting charging rate Cs1, and the optimum power generation ending charging rate Ce1, the number of transitions is set to n, and the counter value is set to 0 (step S10). The initial power generation start charge rate Cs0 and the initial power generation end charge rate Ce0 are set as the first power generation start charge rate Cs and the power generation end charge rate Ce, respectively (step S20).

First, battery running (initial battery running)
(Step S30), it is determined whether the charging rate has dropped to the power generation start charging rate Cs while monitoring the charging rate of the battery (Step S40). When the charging rate falls to the power generation start charging rate Cs, APU (auxiliary power generation unit) 5
Is started (step S50), and power generation traveling is performed (step S60).

Then, while monitoring the charge rate of the battery, it is determined whether or not the charge rate has risen to the power generation end charge rate Ce (step S70). When the charge rate rises to the power generation end charge rate Ce, the APU 5 is stopped (step S8).
0), and then it is determined whether the counter value is less than n (step S90). If the counter value is less than n, step S1
00, the next power generation start charging rate Cs and power generation end charging rate Ce are calculated by the following equations. Cs = Cs + (Cs1-Cs0) / n Ce = Ce + (Ce1-Ce0) / n Then, the value of the counter is incremented (step S110), and the process returns to step S30 again to start a new power generation charge rate Cs, power generation end. APU based on the charging rate Ce
Power generation running (step S60) by starting 5 (step S50) and stopping of APU5, that is, power generation running stop (step S80). By repeating such processing, the power generation start charge rate Cs and the power generation end charge rate Ce are gradually increased.
When this is repeated n times, the power generation start charge rate Cs and the power generation end charge rate Ce become the optimum power generation start charge rate Cs1 and the optimum power generation end charge rate Ce1. Power generation will be repeated.

As a result, as shown in FIG. 2, for example, the initial power generation running (power generation running after full charge) is continued until the charging rate of the battery 1 is sufficiently reduced, and the charging rate of the battery 1 is initially generated. Only when the charging rate reaches Cs0, the electric power generation is started. In this way, since the mileage is secured by only the initial battery, the original advantages of electric vehicles, such as no emission of gas and higher quietness than internal combustion engines, will be fully utilized. There are advantages.

After the initial power generation is started, the power generation traveling is prevented from being continued for too long, that is, the power generation traveling at a certain charge rate, so that it is possible to prevent an increase in the power generation traveling ratio. The original advantage of the electric vehicle, which does not emit exhaust gas and is highly quiet, is fully utilized. In such power generation running, the intermediate power generation running is performed once or a plurality of times, and then the optimum power running is performed. Therefore, when it is necessary to rely on the power running, this power generation can be performed most efficiently. Therefore, there is an advantage that the fuel consumption of the internal combustion engine for power generation during power generation traveling can be improved and exhaust gas can be reduced.

Further, since the duration of the battery running mode can be relatively unknown, it is easy to keep the temperature of the exhaust gas purifying catalyst of the generator driving engine within the required range, and the exhaust gas purifying ability of the catalyst is kept good. It is convenient for you.

[0036]

As described in detail above, according to the charge / discharge control device for a hybrid electric vehicle of the present invention as set forth in claim 1, in addition to the discharge control for driving the electric motor by the on-vehicle battery to drive the vehicle, In a charge / discharge control device for a hybrid electric vehicle that performs a charge control for driving a generator by a vehicle-mounted prime mover to charge the battery, the state of charge of the battery is from a state of substantially full charge to a state of optimum charge start. An initial charge start state detecting means for detecting that the battery has been discharged to a small initial charge start state, and upon receiving a detection signal from the initial charge start state detecting means, operate the prime mover to generate electric power to optimally terminate the battery. Initial charging control means for charging to an initial charging end state smaller than the state, and the charging state of the battery due to discharging after completion of the initial charging An intermediate charge start state detecting means for detecting discharge from a charge end state to an intermediate charge start state smaller than the optimum charge start state and larger than the initial charge start state, and the intermediate charge start state detecting means. When the detection signal is received, the prime mover is operated to generate electric power to charge the battery to an intermediate charge end state that is smaller than the optimum charge end state and larger than the initial charge end state, and the intermediate charge control means. The state of charge of the battery due to discharge after the end of the intermediate charge end state,
Optimal charging start state detecting means for detecting that the battery has been discharged to the optimal charging start state, and when the detection signal from the optimal charging start state detecting means is received, the prime mover is operated to generate electricity to optimally charge the battery. With the configuration that is equipped with the optimal charging control means for charging to the end state, the initial battery traveling distance is secured, the traveling ratio of power generation traveling is suppressed, and the quietness is high without emitting the original exhaust gas of the electric vehicle. While obtaining the full advantage, it becomes possible to avoid power generation (charging) in the charging rate region where charging efficiency is poor during power generation traveling, and it is possible to prevent deterioration of fuel efficiency of the internal combustion engine for power generation. The advantage is that exhaust gas can be reduced.

According to the charging / discharging control device for a hybrid electric vehicle of the present invention described in claim 2, in the configuration of claim 1, the intermediate charging start state and the intermediate charging end state gradually increase the charging state. Thus, a plurality of sets are provided, and the intermediate charging control means is configured to perform intermediate charging control a plurality of times in accordance with the plurality of intermediate charging start states and intermediate charging end states, and the optimum charging control is performed. The means is configured to perform the optimal charging control through the intermediate charging control performed a plurality of times, thereby ensuring the initial battery traveling distance and suppressing the traveling ratio of the power generation traveling, and at the time of the power generation traveling. The advantage of being able to avoid the deterioration of charging efficiency and prevent the deterioration of fuel efficiency of the internal combustion engine for power generation and to reduce exhaust gas during power generation running It is.

According to the charge / discharge control device for a hybrid electric vehicle of the present invention as set forth in claim 3, in the configuration of claim 1 or 2, the optimum charging start state is provided at the final time of the intermediate charging by the intermediate charging control means. By being configured to perform the charging from the final intermediate charging disclosure state that does not reach until the optimal charging end state is reached, it is possible to quickly shift to the optimal charging state.

[Brief description of drawings]

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

FIG. 2 is a diagram illustrating charge / discharge control by a charge / discharge control device for a hybrid electric vehicle according to an embodiment of the present invention, and is a diagram showing a state of charge of a battery.

FIG. 3 is a diagram illustrating charge / discharge control by a charge / discharge control device for a hybrid electric vehicle according to an embodiment of the present invention, and is a diagram showing a state of charge of a battery.

FIG. 4 is a flowchart illustrating charge / discharge control by a charge / discharge control device for a hybrid electric vehicle according to an embodiment of the present invention.

FIG. 5 is a diagram showing a state of charge of a battery for explaining charge / discharge control during traveling of a conventional hybrid electric vehicle.

FIG. 6 is a diagram illustrating battery charge / discharge control during traveling of a conventional hybrid electric vehicle.

[Explanation of reference numerals] 1 battery 2 traveling motor (traveling electric motor) 3A, 3B drive wheels 4 motor controller (electric motor control means) 5 APU (Auxiliary Power Unit, auxiliary power generation unit) 6 generator 7 internal combustion for power generation as a prime mover Engine (engine) 8 Remaining capacity detecting means (remaining capacity meter) 9 Running management controller 10 APU control section 11 Storage means 12 Computing means 13 Judging means 13A Initial charging start state judging means 13B Intermediate charging start state judging means 13C Optimal charging start state Judgment means 14 Command means 14A Initial power generation command means (initial charge control means) 14B Intermediate power generation command means (intermediate charge control means) 14C Optimal power generation command means (optimal charge control means)

Claims (3)

[Claims] 1. A charging / discharging of a hybrid electric vehicle that performs discharge control for driving an electric motor to drive the vehicle by an on-vehicle battery and charge control for driving a generator by an on-vehicle prime mover to charge the battery. In the control device, an initial charge start state determination means for determining that the state of charge of the battery is discharged from a substantially full charge state to an initial charge start state smaller than the optimum charge start state, and the initial charge start state determination means. Receiving a determination signal from the motor, the prime mover is operated to generate electric power to charge the battery to an initial charging end state smaller than the optimum charging end state, and the battery is discharged by discharging after the initial charging end state. Of the intermediate charge from the initial charge end state to a value smaller than the optimum charge start state and larger than the initial charge start state. The intermediate charge start state determining means for determining that the battery has been discharged to the electric charge start state, and when the determination signal from the intermediate charge start state determining means is received, the prime mover is operated to generate power to bring the battery into the optimum charge end state. An intermediate charge control means for charging to an intermediate charge end state that is smaller than the initial charge end state, and the state of charge of the battery due to discharge after the intermediate charge end state is changed from the intermediate charge end state to the optimum charge start state. The optimal charging start state determining means for determining that the battery has been discharged to a state, and the prime mover is operated to generate power by receiving the determination signal from the optimal charging start state determining means to charge the battery to the optimal charging end state. A charging / discharging control device for a hybrid electric vehicle, comprising: 2. A plurality of sets of the intermediate charge start state and the intermediate charge end state are provided so as to gradually increase the charge state, and the intermediate charge control means is provided for the intermediate charge start state and the intermediate charge start state. The optimal charging control means is configured to perform the intermediate charging control a plurality of times according to the charging completion state, and the optimal charging control means is configured to perform the optimal charging control through the plurality of intermediate charging controls. The charge / discharge control device for a hybrid electric vehicle according to claim 1, which is characterized in that. 3. The final charging of the intermediate charging by the intermediate charging control means is configured to perform charging from the final intermediate charging disclosure state that does not reach the optimal charging start state to the optimal charging end state. The charge / discharge control device for a hybrid electric vehicle according to claim 1 or 2, characterized in that: