JP2000014030A - Charge control equipment for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charge control equipment for preventing overcharge of each cell caused by a large charging current. SOLUTION: When a cell voltage reaches a full charge voltage, each of the bypass circuits (15-1)-(15-n) bypasses a charging current, and outputs a bypassing signal. A regenerative braking part 4c of charge control equipment 4 responds to a regenerative braking command of an ECU 3, executes regenerative braking, and converts the kinetic energy of a generator-motor(G/M) to electric energy. When the bypassing signal is received, a bypass operation detecting part 3a of the ECU 3 outputs a charge limiting signal to a charging part 4b. In a normal period, the charging part 4b converts electric energy generated by the regenerative braking part 4c into a comparatively large charging current IH. When the charge limiting signal is received, the charging part 4b limits the electric energy within a comparatively small charging current IH.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle charging control device for charging a battery mounted on an electric vehicle or a hybrid vehicle, and more particularly, to a vehicle capable of preventing overcharge and extending the life of the battery. The present invention relates to a charge control device for a vehicle.

[0002]

2. Description of the Related Art Vehicles that use a battery as a power source, such as electric vehicles and hybrid vehicles (hereinafter referred to as electric vehicles), are becoming widespread in consideration of the environment. Such a secondary battery for an electric vehicle requires a large-capacity battery that can secure power equivalent to that of a gasoline engine, but can be charged as easily and in a short time as gasoline refueling. Large capacity secondary batteries have not been developed yet.

In order to prevent the secondary battery from being overcharged, it is desirable to control the charge amount by accurately grasping the charge amount of the battery. However, a technique for accurately detecting the charge amount has been established. At present, a certain amount of overcharging is usually performed in order to effectively use the capacity of the battery. However, overcharging not only promotes battery deterioration but also wastes electrical energy.

In order to solve such problems, for example, Japanese Patent Application Laid-Open No. 6-261452 or Japanese Patent Application Laid-Open No. 4-2
In Japanese Patent Application Laid-Open No. 99032, a secondary battery is configured by connecting a plurality of battery cells in series, and a terminal voltage of each battery cell is detected, and a charging current to a battery cell whose terminal voltage has reached a predetermined value is bypassed. A storage power supply device provided with a limiting circuit has been proposed.

FIG. 8 is a block diagram showing the configuration of the above-described conventional charge limiting circuit. The battery 9 is configured by connecting a plurality of battery cells 90-1, 90-2,..., 90-n in series, and the load 7 is supplied with electric energy from the battery 9. When charging the battery 9, a charging circuit 8 is connected, and the charging circuit 8 charges the battery 9 using electric power supplied from the commercial power supply 6.

Each of the battery cells 90-1, 90-2,.
The bypass circuits 5-1 to 5-n are connected in parallel to 0-n. Each of the bypass circuits 5-1 to n acts so as to pass the charging current as the bypass current IBP when the cell voltage becomes the full charge voltage VFU. Therefore, the charging current is preferentially supplied to the battery cells 90-i that have not been fully charged.

FIG. 9 is a diagram showing an example of the configuration of the bypass circuit 5. The base of a transistor Tr is connected to the connection point of voltage dividing resistors R2 and R3 connected in series between input and output terminals. The collector of the transistor Tr is connected to the input terminal, and the emitter is connected to the output terminal via the bypass resistor R4.

According to such a configuration, the cell voltage V of one of the battery cells 90-i increases and the full charge voltage V
When the charge reaches FU, the base voltage of the transistor Tr rises and turns on, and the charging current is bypassed via the transistor Tr and the bypass resistor R4, thereby preventing the battery cell from being deteriorated due to overcharging.

[0009]

In an electric vehicle, not only charging with a commercial power supply in a stopped state but also regenerative braking in which a battery is charged by using a drive motor as a generator during braking even during traveling is performed. Will be However,
In regenerative braking, electric power is generated in accordance with the rotation speed of the drive motor, so that a relatively large current (or voltage) is supplied to the battery during braking from a high-speed running state.

As described above, when a large charging current is supplied to the battery, the terminal voltage of the bypass resistor R4 increases even during the bypass by the bypass circuit 5-i, so that the voltage applied to the battery cell 90-i also decreases. There is a problem that the battery may rise and an overcharged state may occur.

The above-mentioned problem is not peculiar to regenerative braking of an electric vehicle. Even in a hybrid vehicle having an engine and a motor as power sources, the driving motor functions as a generator during operation of the engine, and the charging current is reduced. Therefore, not only during the regenerative braking as described above, but also when the engine is operated at a high rotation speed, a large charging current is generated, and the same problem as described above may occur.

An object of the present invention is to solve the above-mentioned problems of the prior art and to prevent a battery cell from being overcharged by a relatively large charging current that can occur during regenerative braking or the like. Is to provide.

[0013]

In order to achieve the above-mentioned object, the present invention provides a chargeable / dischargeable battery formed by connecting a plurality of cells in series, a power generator for charging the battery, A charge control device for controlling the charging of the battery by the power generation device, wherein the charge control device is connected in parallel to each of the cells, and detects that the terminal voltage of each of the cells has reached a predetermined value or more. Bypass means for bypassing a charging current to a cell, and bypass operation detecting means for detecting whether or not each of the bypass means is performing a bypass operation, wherein the charge control device is When a bypass operation of at least one bypass unit is detected, a charging current supplied to the battery is limited.

According to the above configuration, when one of the cells constituting the battery is fully charged, the charging current is bypassed and supplied preferentially to other cells, and the charging current itself is also limited. Since the bypass current is reduced, an increase in the voltage applied to the fully charged cell due to the bypass current is suppressed, and deterioration of the battery due to overcharging can be prevented.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram of a vehicle charging control device according to one embodiment of the present invention, and the same reference numerals as those described above denote the same or equivalent parts. Although an electric vehicle using a motor as a power source will be described below as an example, the present invention can be similarly applied to a so-called hybrid vehicle using a motor and an engine as a drive source.

In the present embodiment, the operating state of each bypass circuit that bypasses the charging current to each cell, that is, whether each bypass circuit is bypassing the charging current or not is determined. Is characterized in that the supply of the charging current is limited.

In FIG. 1, a generator electric motor (G / M) having a function of generating and electrically driving is mechanically connected to driving wheels WR and WL of a vehicle via appropriate gear means (not shown). The capacitor 1 functioning as a capacitor is, for example, a large-capacity electric double layer capacitor, and includes a plurality of cells 1
, 10-n are connected in series.

The charge control device 4 controls charging of the capacitor 1 from the electric motor (G / M) and power supply from the capacitor 1 to the electric motor (G / M).
Each of the bypass circuits 15-1 to 15-n as bypass means includes:
The cell voltage of each of the cells 10-1 to 10-n is monitored, and when the cell voltage becomes the full charge voltage VFU, the charge current is bypassed and a signal indicating that the battery is being bypassed is output to the ECU 3. If the rated voltage of each cell is, for example, 2.5 V, the full charge voltage VFU is desirably set to 2.3 to 2.5 V, which is lower than that.

The inverter section 4a of the charging control device 4 converts a DC current output from the capacitor 1 into an AC current and supplies the AC current to the generator motor (G / M), and also generates the generator motor (G / M). Converts the generated AC current into a DC current and supplies it to the capacitor 1.

The ECU 3 outputs a regenerative braking command to the charging control device 4 in response to a separately input braking command. The regenerative braking unit 4c of the charge control device 4 responds to the regenerative braking command sent from the ECU 3 to
/ M) function as a generator to execute regenerative braking for generating a braking force on the drive wheels WR and WL, thereby converting the kinetic energy of the generator electric motor (G / M) into an alternating current. The AC current is converted into a DC current by the inverter unit 4a, and is supplied from the charging unit 4b to the capacitor 1 as a charging current.

The bypass operation detecting section 3a of the ECU 3 functions as a bypass operation detecting means.
When the bypass signals output from 1 to n are received, it is determined that one of the cells 10-i is in a fully charged state and the bypass circuit 15-i has been activated, and is sent to the charging unit 4b of the charging control device 4. Outputs charge limit command.

The charging section 4b normally converts an alternating current output from the generator motor (G / M) during regenerative braking into a relatively large charging current IH and outputs the converted current.
Upon receiving a charge limit command from the bypass operation detecting unit 3a of U3, the output current is limited from the charge current IH to a smaller charge current IL.

FIG. 2 is a block diagram showing a configuration example of the bypass circuit 15, and the same reference numerals as those described above denote the same or equivalent parts.

The bypass resistor R4 of each bypass circuit 15 has a photocoupler 15 as a signal generating means during bypass.
One photodiode 153 is connected in parallel, and a phototransistor 152 paired with each photodiode 153 is provided.
Are commonly connected to each other for each photocoupler and connected to the ECU 3. In the ECU 3, the common emitter line is grounded, and the common collector line is pulled up and connected to the bypass operation detecting unit 3a. The signal on the common collector line is the signal during bypass.

As described above, in the present embodiment, whether or not each bypass circuit is performing the bypass operation can be directly detected by the bypass current flowing during the bypass operation. Compared to a case where the detection is performed based on the above, not only a sensor or the like for detecting the cell voltage is unnecessary, but also accurate detection becomes possible.

FIGS. 3 and 4 are flowcharts showing the operation of the present embodiment. In particular, FIG. 4 shows the operation of the bypass operation detecting unit 3a, and FIG. 4 shows the operation of the charging unit 4b. FIG. 5 is a time chart showing the transition state of the voltage level of each part in FIG.
Is composed of three cells 10a, 10b, and 10c.

FIG. 5A shows a cell 1 having a sufficient charge amount.
0c, the terminal voltage of the cell 10c with insufficient charge, and (b) the terminal voltage of the cell 10b with an intermediate charge between the two.

The bypass operation detecting section 3a determines in step S1
When a braking command is received in step S1, a regenerative braking command is output to the regenerative braking unit 4c of the charging control device 4 at time t1 in step S12. As a result, the regenerative braking is executed by the generator motor (G / M) functioning as a generator.

In step S13, each bypass circuit 15
It is determined from -i whether a bypass signal has been transmitted. If the cell voltage V of each of the cells 10a, 10b, and 10c is lower than the full charge voltage VFU as at time t1 in FIG. , 10b, and 10c, the bypass signal is not output. The bypass operation detection unit 3a does not output the charge limit signal unless the bypass signal is received.

Thereafter, the charging of the cells 10a, 10b, and 10c proceeds, and as shown in FIG. 3A, when the terminal voltage of the cell 10a reaches the full charge voltage VFU at time t2, the cell 10a is charged. The bypass circuit 15 is energized to bypass the charging current, and the bypass operation detecting unit 3
With respect to “a”, a bypass signal is output. Upon receiving the bypass signal in step S13, the bypass operation detection unit 3a outputs a charge restriction command in step S14.

On the other hand, the charging section 4b performs step S21.
In step S22, it is determined whether a charge limit command has been received. If the charge limit command has not been received, the output current is set to a relatively large charge current IH in step S22. Therefore, after the time t1, the cells 10a, 10b, 10c
Is rapidly charged with a relatively large charging current IH. Also, at time t2, a charge limit command is sent out, and when it is received in step S21,
In step S23, the output current is limited to a relatively small charging current IL (<IH).

Thereafter, at time t3, the cell 10b
When the terminal voltage of the cell 10 reaches the full charge voltage VFU, the cell 10
The charging circuit is bypassed by energizing the bypass circuit 15b, and a bypass signal is output to the bypass operation detecting unit 3a. Further, at time t4, when the terminal voltage of the cell 10c reaches the full charge voltage VFU, the bypass circuit 15 of the cell 10c is energized to bypass the charging current and to bypass the bypass operation detecting unit 3a. A signal is output.

As described above, according to the present embodiment, when one of the cells 10 reaches the fully charged state and its bypass circuit 15 functions, the charging current due to regenerative braking is automatically limited in response to this. Therefore, overcharging of each cell is prevented.

In the above embodiment, the charging unit 4b
Has described that the charging current is controlled in two stages of a relatively large charging current IH or a charging current IL smaller than this, but as shown in FIG. The charging current may be decreased stepwise as IH → IM → IL every time the output is performed.

Further, in FIGS. 5 and 6, it has been described that the small charging current IL continues to be supplied even after the bypass signal is output from all the bypass circuits 15. However, the bypass signal is output from all the bypass circuits 15. After the output, the supply of the charging current may be stopped.

FIG. 7 is a block diagram of a vehicle charge control device according to a second embodiment of the present invention. The same reference numerals as those described above denote the same or equivalent parts. In this embodiment,
The vehicle charge control device of the present invention is applied to a so-called hybrid vehicle in which a motor and an engine 2 are combined.

The hybrid vehicle is provided with a motor dedicated to power generation and a motor dedicated to electric power separately, and the engine drives the motor dedicated to power generation to charge the battery.
There has been proposed a parallel type in which a generator electric motor is provided that functions as both a generator and an electric motor, and the generator electric motor assists engine power and charges a battery as a generator. Further, there has been proposed a combination system in which each system is combined to selectively drive one of an engine and a generator electric motor.

FIG. 7 is a block diagram of a hybrid vehicle employing the above-described parallel system or combination system.
M), and the driving shafts of the vehicle are connected to each other.
WL indicates only the engine 2, only the generator electric motor (G / M), or the engine 2 and the generator electric motor (G / M).
M).

In the hybrid vehicle having such a configuration,
Even during the regenerative braking described above, a charging current is generated during the operation of the engine 2, and the magnitude of the charging current depends on the engine speed. Therefore, if the charging unit 4b controls the current output from the charging control device 4 during the operation of the engine 2 based on the charging limit command output from the bypass operation detecting unit 3a of the ECU 3 in the same manner as described above, the engine rotation speed Irrespective of this, charging with an appropriate charging current becomes possible.

[0040]

As is apparent from the above description, according to the present invention, the following effects are achieved. (1) According to the first aspect, when any of the cells constituting the storage battery (capacitor) reaches full charge, the charging current is bypassed and supplied preferentially to other cells, and the charging current itself is reduced. Is also limited and the bypass current is reduced,
An increase in the voltage applied to the fully charged cell due to the bypass current is suppressed, and deterioration of the battery due to overcharging can be prevented. (2) According to the second aspect, whether or not each bypass circuit is performing the bypass operation can be directly detected by the bypass current flowing during the bypass operation, so that accurate detection becomes possible. (3) According to claim 3, the charging circuit supplies a relatively large charging current IH until the bypass operation is detected, and a relatively small charging current IL when the bypass operation is detected.
Therefore, the charging of the cell proceeds rapidly until the bypass is started, and even after the bypass is started, it is possible to continue charging other cells while preventing overcharging of the cell. it can. (4) According to the fourth aspect, since the charging current decreases as the number of cells in the fully charged state increases, overcharging of the remaining cells can be prevented more favorably. (5) According to claim 5, the current generated during regenerative braking is:
Since the battery is always supplied to the battery as a charging current after being controlled to the optimum size, overcharging of the cell is prevented even during regenerative braking that can generate a large generated current.

[Brief description of the drawings]

FIG. 1 is a block diagram of a vehicle charging control device according to one embodiment of the present invention.

FIG. 2 is a diagram illustrating one embodiment of a bypass circuit illustrated in FIG. 1;

FIG. 3 is a flowchart showing the operation of the embodiment.

FIG. 4 is a time chart showing operation timings of the embodiment.

FIG. 5 is a time chart illustrating an example of an operation timing according to the embodiment;

FIG. 6 is a time chart showing another example of the operation timing of the present embodiment.

FIG. 7 is a block diagram of a vehicle charging control device according to another embodiment of the present invention.

FIG. 8 is a block diagram of a conventional technique.

FIG. 9 is a diagram illustrating a configuration example of a bypass circuit according to the related art.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Capacitor, 2 ... Engine, 3 ... ECU, 4 ... Charge control device, 5, 15 ... Bypass circuit, 10 ... Cell

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Koichiro Ozawa 1-4-1, Chuo, Wako, Saitama Prefecture Inside Honda R & D Co., Ltd. (72) Inventor Kazuhiro Hara 1-4-1, Chuo, Wako, Saitama No. Within Honda R & D Co., Ltd. (72) Inventor Yasuo Yamada 1-4-1 Chuo, Wako-shi, Saitama Pref. Inside of Honda R & D Co., Ltd. (72) Iwao Shimane 1-4-chuo, Wako-shi, Saitama No. 1 F-term in Honda R & D Co., Ltd. (Reference) 5G003 AA07 BA03 CA01 CA11 CB09 CC02 DA07 DA11 FA06 GB06 GC05 5G065 BA00 DA06 EA10 GA03 GA09 HA17 JA07 LA01 LA02 LA07 MA10 5H111 BB02 BB06 CC01 CC11 CC16 DD03 DD08 DD11 GG05 GG05 GG05

Claims (5)

[Claims] 1. A vehicle comprising: a chargeable / dischargeable capacitor configured by connecting a plurality of cells in series; a power generation device for charging the power storage device; and a charge control device for controlling charging of the power storage device by the power generation device. In the charging control device, a bypass unit that is connected in parallel to each of the cells, detects that the terminal voltage of each cell has become equal to or higher than a predetermined value, and bypasses a charging current to the cell, And a bypass operation detecting means for detecting whether or not the bypass operation is being performed. The charging control device supplies the battery to the battery when the bypass operation detecting means detects a bypass operation of at least one bypass means. A charging control device for a vehicle, comprising: charging means for limiting a charging current to be applied. 2. Each of the bypass means is connected in parallel with each of the battery cells, and is turned on when the terminal voltage of the battery cell reaches a predetermined full charge voltage, thereby bypassing a charge current. A bypass signal generation unit that is energized by a current to generate a bypass signal, wherein the bypass operation detection unit detects a bypass operation by each bypass unit based on the presence or absence of the bypass signal. The charge control device for a vehicle according to claim 1, wherein: 3. The charging means supplies a first charging current until the bypass operation detecting means detects a bypass operation by any of the bypass means, and when the bypass operation is detected, the charging means supplies the first charging current. 3. The vehicle charging control device according to claim 1, wherein a second charging current smaller than the first charging current is supplied instead of the first charging current. 4. 4. The vehicle according to claim 1, wherein the charging unit gradually reduces the charging current each time the bypass operation detecting unit detects a bypass operation by each bypass unit. Charge control device. 5. The charging control device according to claim 1, further comprising: regenerative braking means for generating a charging current during regenerative braking, wherein the charging means limits a charging current generated during the regenerative braking. 5. The vehicle charge control device according to any one of claims 4 to 4.