JPH08322159A - Overdischarging prevention unit - Google Patents

Abstract

PURPOSE: To take out a required amount of electricity without entering into overdischarging region by detecting the discharging depth of a battery and limiting the dischargeable current at a lower level as the discharging depth increases. CONSTITUTION: A control unit 92 reads in each load current and terminal voltage through a battery sensor 102 and determines the residual capacity of each battery 81a. The dischargeable current is set at a lower level as the residual capacity of battery 81a decreases, i.e., the discharge depth thereof increases. More specifically, residual capacity is determined for each battery 81a and the discharging current is limited with reference to a battery 81a having lowest residual capacity. Consequently, a required amount of electricity can be taken out without entering into the overdischarging region.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery over-discharge prevention device used in an electric vehicle such as an electric motorcycle.

[0002]

2. Description of the Related Art For example, an electric motorcycle has a structure in which a current corresponding to an accelerator operation amount is supplied from a battery to a drive motor and the drive force of the drive motor is transmitted to a rear wheel through a power transmission unit. There is.

By the way, the relationship between the discharge electric quantity Ah of the battery and the discharge current value I is as shown in FIG.
As the discharge current I increases, the amount of electricity Ah that can be taken out decreases. Therefore, when the discharge current IA is large, a large load is applied to the battery, so that the battery remaining capacity needs to be large. When the discharge current IB is small, the load on the battery is also small, and therefore the battery remaining capacity can be small.

Further, if discharging is continued in the state where the remaining capacity of the battery is small, over-discharging will occur and the life of the battery will be significantly deteriorated. For this reason, conventionally, when the amount of discharged electricity of the battery exceeds a certain value, for example, 80% of the battery capacity, it is regarded as over-discharge, and the discharged amount of electricity is suppressed or a warning lamp gives a warning.

[0005]

However, in the above-mentioned conventional method for limiting the amount of discharged electricity of a battery, there is no problem when a small load current (discharge current) is passed, but when the load current is large, the remaining capacity of the battery is reduced. There is a problem that the battery may enter the over-discharged area depending on the reason, which shortens the battery life.

In this case, it can be considered to set the discharge electricity amount of the battery as low as 30% of the battery capacity. However, this causes a problem that the battery capacity is extremely limited and it becomes impossible to take out a necessary amount of electricity.

The present invention has been made in view of the above conventional circumstances, and an object of the present invention is to provide a battery over-discharge prevention device which can take out a necessary amount of electricity without entering the over-discharge region.

The present invention comprises a discharge depth detecting means for detecting the discharge depth of the battery, and a discharge current value control means for limiting the dischargeable current value to a smaller value as the discharge depth from the discharge depth detecting means is larger. A battery over-discharge prevention device characterized by the above.

Here, the large depth of discharge in the present invention means that the integrated value of the discharged electricity amount is large or that the battery residual capacity is small. Further, the present invention can be applied to both the case of detecting the depth of discharge of a plurality of batteries as a whole and the case of detecting the depth of discharge of each battery.

[0010]

According to the over-discharge prevention device of the present invention, the dischargeable current value is limited to a small value so that the battery does not enter the over-discharge region as the depth of discharge of the battery increases. Instead, the amount of electricity according to the remaining battery capacity can be taken out.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 8 are views for explaining a battery overdischarge prevention device according to an embodiment of the present invention. FIG. 1 is a side view of an electric scooter to which the device of the present embodiment is applied, and FIG. FIG. 3 is a configuration diagram showing an electric system of the electric scooter, FIG. 3 is a map diagram for setting a discharge level from a terminal voltage and a load current, FIG. 4 is a schematic configuration diagram of the apparatus of the above embodiment, and FIG. 5 is a terminal voltage and a discharge current. FIG. 6 is a map diagram for setting the dischargeable current value from FIG. 6, FIG. 6 is a diagram showing a modification of the battery voltage detection method,
7 and 8 are map diagrams showing the relationship between the dischargeable current value and the discharge depth.

In the figure, reference numeral 1 is an electric scooter to which the apparatus of this embodiment is applied, and a body frame 2 of the scooter 1 has a down tube 4 attached to a head pipe 3 for pivotally supporting a front fork 12. The down tube 4 has a front tube 5 extending rearward and downward from the head pipe 3, an intermediate tube 6 extending substantially horizontally rearward from the front tube 5, and an obliquely upward direction from the intermediate tube 6. It is composed of a rear tube 7 that extends.

The rear tube 7 is connected to a pair of left and right rear frames 9 and 9 which are bent and extend upward and rearward from the rear tube 7, and the seat frame 10 is provided on the rear frames 9 and 9.
A seat 26 on which an occupant is seated is disposed so as to be openable and closable via the. A front wheel 14 is pivotally supported by an axle 13 on the lower end of the front fork 12, and a handle 15 is fixed on the upper end. An accelerator grip 16 and a rear wheel brake lever 59 are provided at the left end of the handle 15.
A front wheel brake lever (not shown) is attached to the right end.

A front cowl 63 and a rear leg shield 64 are provided around the head pipe 3 and a front fender 65 is provided above the front wheel 14. A foot board 30 that constitutes a foot rest is disposed above the intermediate tube 6, and an under cover 67 covers the lower portion of the foot board 30. Further, the left and right sides of the rear frames 9, 9 are rear side covers 6
8, the lower part of the seat 26 is covered with a rear cover 69, and the upper part of the rear wheel 21 is covered with a rear fender 70.

A power unit 19 is pivotally supported on the rear frame 9 via a pivot shaft 18 so as to be vertically swingable, and a rear wheel 21 is pivotally supported on a rear end of the power unit 19 by an axle 20. ing. A shock absorber 23 is installed between the power unit 19 and the rear frame 9, and the shock absorber 23 absorbs a shock from the road surface.

The power unit 19 is composed of a three-phase AC drive motor 32 and a power transmission device 33 for transmitting the driving force of the motor 32 to the rear wheels 21. The drive motor 32 is arranged with its axis in the vehicle width direction, and is fixed to the unit case 35 by bolts.
A drive chain is wound around an output shaft 37 of the drive motor 32 via a sprocket (not shown), and the drive chain is connected to the rear wheel 21 via a reduction gear. The power transmission device 33 may be a V-belt type continuously variable transmission, a gear type transmission, or the like.

An assembled battery 81 is arranged on the intermediate tube 6, and the assembled battery 81 includes four 12V batteries 8
1a is connected in series. The batteries 81a are housed in a resin support box 77, and the support box 77 is detachably attached to the intermediate tube 6 via a bracket (not shown). The assembled battery 81 is covered with the foot board 30 and the under cover 67,
Avoids damage due to external force.

A charger 8 to which a household power source (AC 100V) for charging the assembled battery 81 is connected
2 and a charging port 83 to which a power source (direct current) dedicated to charging is connected
Are electrically connected to each other, and the charger 82 and the charging port 8
3 is disposed in the seat frame 10. The battery pack 81 is charged by rotating the seat 26 upward to connect the plug 82a of the charger 82 to the power source or by connecting the charging connector 84 to the charging port 83.

A controller 86 is arranged between the rear frames 9 and 9 and is composed of an inverter as a power section and a control unit 92 as a control section. The controller 86 is housed in a thick-walled aluminum case 87 that opens to the front of the vehicle body, and a cover lid 93 is openably and closably arranged in the front opening of the case 87. In the case 87, left and right flanges 87a integrally formed with the case 87 are bridged over the left and right rear frames 9, respectively, and they are fastened and fixed by bolts 89, which also functions as a reinforcing material. ing. Further, a cooling fin (not shown) is integrally formed on the case 87 so that it can be effectively cooled by the running wind.

The control unit 92 is shown in FIG.
As shown in FIG. 1, the key-operated main switch 109 and the converter 110 are connected in series.
A power relay 96 is connected to 10 in parallel. An emergency stop switch 97 and a normally open (OFF) start switch 98 are connected to the controller 86. Here, 104 is a start indicator, 105 is an overheat indicator, 106 is a power fault indicator, 113 is a head lamp, 115 is a flasher relay, 116 is an audio pilot, 119 and 120 are left and right flasher lamps, respectively. Is a speedometer lamp. Further, 124 is a horn, 126 is a tail lamp, 12
Reference numeral 7 is a stop lamp, 130 and 131 are front and rear wheel brake sensors, 135 is a main stand switch, and 137 is a buzzer, which are connected to the converter 110.

Further, a potentiometer-type accelerator sensor 99 for detecting the rotational operation amount of the accelerator grip 16 is connected to the controller 86, and the controller 86 supplies a current corresponding to the operation amount of the accelerator grip 16 to the assembled battery. 81 is supplied to the drive motor 32 via the power relay 96.

Here, in order to start and drive the electric scooter 1, the main switch 109 and the start switch 98 are turned on. Next, when the accelerator grip 16 is gradually rotated toward you, the fully closed switch 100 is automatically turned on, and when the accelerator grip 16 is further rotated, a current corresponding to the rotation amount is supplied from the assembled battery 81 to the drive motor 32. It This starts and accelerates. To stop it, the main switch 109 is turned off.

When an emergency stop is made while the electric scooter 1 is running, the emergency stop switch 97 is turned off. Then, the inverter, which is the power section of the controller 86, is immediately turned off, which causes the drive motor 32 to stop. In this case, the control unit 92, which is the control unit, is held in the ON state, and the memory before the emergency stop is left as it is. Therefore, the emergency stop switch 9
By turning on 7 again, the control unit 92
Will return to the state it was in immediately before turning off, and you will be able to drive.

The electric scooter 1 of this embodiment is provided with a battery pack over-discharge prevention device. The overdischarge prevention device obtains the remaining capacity of each battery 81a based on the battery sensor 102 that detects the load current and terminal voltage of each battery 81a, and the detection value from the sensor 102, and determines the remaining capacity according to the remaining capacity. The control unit 92 is configured to suppress and control the current supplied to the drive motor 32.

The battery sensor 102 includes a Hall CT for detecting the load current of each battery 81a, a current sensor such as a shunt resistor, and a voltage sensor for detecting the terminal voltage of each battery 81a. Each battery 8
The voltage of 1a is V1-V2, V2-, as shown in FIG.
It can be calculated by V3, V3-V4, V4, or by directly detecting the voltage value of each battery 81a as shown in FIG.

The control unit 92 serves as a remaining capacity calculating means for obtaining the remaining capacity of each battery 81a from the voltage value / current value of the battery 81a, and an over-discharged battery for detecting a battery whose remaining capacity is in the over-discharge region. It functions as a detection means. The remaining capacity calculation means reads the load current I and the terminal voltage V from the battery sensor 102 and calculates the remaining capacity (V · I) of each battery 81a. The control unit 92 is connected to a remaining capacity meter 103 for displaying the minimum remaining capacity of the batteries 81a, and the capacity meter 103 is provided with a warning lamp and a warning buzzer (not shown).

As shown in FIG. 3, the above-mentioned over-discharged battery detecting means has a built-in map for selecting a discharge level from the remaining capacity obtained above. This discharge level is set to three levels: a high level (H) of about 70% remaining capacity, a medium level (M) of about 40% remaining capacity, and a low level (L) of about 20% remaining capacity. Then, the control unit performs the following output control based on the discharge level selected based on the map.

That is, the battery 81 with the minimum remaining capacity is
When the remaining capacity of a is larger than the high level H (see FIG.
Point A), a current corresponding to the operation amount of the accelerator grip 16 is output to the drive motor 32, and normal operation control is performed. When the minimum remaining capacity is from high level H to medium level M (point B in FIG. 3), the current remains in the normal operation control and the remaining capacity meter 1
The warning lamp No. 03 is turned on, and the warning buzzer sounds for a predetermined time or until the stop operation is performed. In this case, 4
A number is displayed so that the remaining capacity of one of the batteries 81a is decreasing.

When the minimum remaining capacity is in the middle level M to the low level L (point C in FIG. 3), the current from the battery 81a to the drive motor 32 is limited and output. Further, when the minimum remaining capacity becomes lower than the low level L (point D in FIG. 3), the current supply to the drive motor 32 is stopped.

Here, the current value is limited according to the depth of discharge of the battery 81a. As a concrete limiting method, the methods shown in FIGS. 5, 7, and 8 can be adopted. First, FIG. 5 is a map diagram for setting the dischargeable current value according to the minimum remaining capacity obtained from the terminal voltage V and the discharge current I of each battery 81a, and the dischargeable current value is limited based on this. To be done. That is, when the minimum remaining capacity of the remaining capacity obtained from the terminal voltage and the discharge current is 50%, the discharge current is limited to the IA value or less, and when the minimum remaining capacity is 25%, the discharge current is limited to the IB value or less. Prevent entry into the discharge area.

FIG. 7 is a map diagram in which the discharge amount Ah of the battery is integrated and the dischargeable current is set to a smaller value as the discharge electricity amount Ah is larger. For example, the discharge integrated amount is Q (Ah). The maximum dischargeable current of the battery is limited to the IA value. In this case, for example, when a discharge current exceeding IA is passed, the discharged electricity amount exceeds 100% of the battery capacity and enters the overdischarge region, but the current of IB is 70% region of the battery capacity, and there is no problem.

FIG. 8 is a map diagram in which the dischargeable current is set to a smaller value as the battery remaining capacity Ah is smaller. For example, in the battery having the remaining capacity Q '(Ah), the maximum dischargeable current is set to the IA' value. Restrict. In this case, for example, if it exceeds IA ', it enters the overdischarge region, but if it is IB', the remaining capacity is 30% of the battery capacity, and there is no problem.

As described above, according to this embodiment, the remaining capacity or the discharged electricity amount of each battery 81a is calculated, and the discharge current is limited with the battery 81a having the smallest remaining capacity or the battery 81a having the largest discharged amount as a reference. By doing so, it is possible to perform accurate control according to the discharge status of each battery 81a, detect the over-discharged state quickly, and improve the life of the entire assembled battery 81.

In the above embodiment, the case of applying to an electric scooter is taken as an example, but the overdischarge preventing device of the present invention is not limited to this. For example, it can be applied to an electric vehicle or other electric vehicles.

[0035]

As described above, according to the battery over-discharge prevention device of the present invention, the depth of discharge of the battery is detected,
Since the dischargeable current value is made smaller as the depth of discharge becomes larger so as not to enter the over-discharge region, it is possible to take out an electric quantity according to the battery capacity without causing a decrease in battery life due to over-discharge. effective.

[Brief description of drawings]

FIG. 1 is a side view of an electric scooter to which an overdischarge prevention device according to an exemplary embodiment of the present invention is applied.

FIG. 2 is a configuration diagram showing an electric system of the electric scooter.

FIG. 3 is a map diagram for setting a discharge level based on a relationship between a load current and a terminal voltage of the device of the above embodiment.

FIG. 4 is a schematic configuration diagram of the apparatus of the embodiment.

FIG. 5 is a map diagram for setting a dischargeable current value based on the relationship between the terminal voltage and the discharge current of the apparatus of the above embodiment.

FIG. 6 is a schematic configuration diagram showing a voltage detection method for each unit cell according to a modification of the embodiment.

FIG. 7 is a map diagram for setting a dischargeable current value in the above embodiment.

FIG. 8 is a map diagram for setting a dischargeable current value in the above embodiment.

FIG. 9 is a diagram showing characteristics of a general battery.

[Explanation of reference numerals] 81a battery 92 control unit (discharge depth detection means, discharge current value control means)

Claims (1)

[Claims] 1. A discharge depth detection means for detecting a discharge depth of a battery, and a discharge current value control means for limiting a dischargeable current value to a smaller value as the discharge depth from the discharge depth detection means is larger. A battery over-discharge prevention device characterized by: