JPH0515072A - Method for charging battery of self-running type carrier car - Google Patents

Abstract

PURPOSE:To enable charge recovery to be performed in a short time by integrating a discharge power which is in operation and a charge power which is being charged by a control device and constantly charging power to an initial capacity of a battery when an amount of remaining capacity of the battery reaches a specified residual capacity. CONSTITUTION:When a power switch of a traveling robot is activated and a carrier car starts its operation, a discharge current Id starts to flow and an amount of remaining capacity Cn of a battery is reduced at a lapse of time as shown by a downward curve. On the other hand, an integrating wattmeter value Cs increases. A CPU 5 constantly reads the integrating wattmeter value Cs at a constant sampling time Ts and stores the amount of remaining capacity which is obtained by subtracting the integrating wattmeter value Cs from a battery capacity C'0 at a time when the power switch is turned on into a memory 6 of the CPU 5. Then, when a traveling robot performs charging while it is working at a certain point Th, the amount of remaining capacity Cn increases corresponding to an amount of charging which is performed in parallel as shown by an upward curve. On the other hand, the integrating wattmeter value Cs is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for charging a battery used in a self-propelled carrier such as a mobile robot,
In particular, the present invention relates to a battery charging method in which the capacity of the battery does not become insufficient even if the battery is charged during operation and the deterioration of the transfer efficiency is prevented.

[0002]

2. Description of the Related Art In a conventional mobile robot such as this (including an automated guided vehicle), when a power consumption during operation is accumulated by a built-in control device and the power consumption drops to a predetermined value, a charging station is charged.
There is known a charging method for preventing the battery from being over-discharged or conversely overcharging the battery by returning to the power supply and recharging only by the power consumption (Japanese Patent Laid-Open No. 57-15).
3536 publication).

[0003]

By the way, in the above-mentioned conventional method, since charging power as much as discharging power of the battery is supplied every time charging is performed, a charging station is provided at the work base. In the case of the method in which the mobile robot charges the battery while working, the charging time is longer than the working time, which deteriorates the transfer efficiency. SUMMARY OF THE INVENTION It is an object of the present invention to provide a battery charging method for a self-propelled guided vehicle that solves the above-mentioned problems (problems) of the prior art.

[0004]

According to the present invention, in a self-propelled carrier that moves by using a battery mounted as a drive source, discharge power during operation and charging power during charging are provided inside the self-propelled carrier. The present invention relates to a battery charging method for a self-propelled carrier vehicle in which the battery is charged up to the initial battery capacity C ₀ when the battery remaining capacity Cn reaches a predetermined battery capacity Cn ′ after being accumulated by the control device. In this case, the relationship of the charging efficiency γ corresponding to the charging current I _S is stored in the memory in advance, and the charging current I _S is measured by the charging power integrating device inside the self-propelled vehicle or the device for measuring the charging current. However, it is desirable to detect the remaining capacity Cn in consideration of the charging efficiency γ obtained from the charging current I _S.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to FIGS. In FIG. 1 showing a method of an embodiment of the present invention, reference numeral 1 is an electric component which becomes an electric load on a battery 2, and is a vehicle drive electric device 3, a transmission device 4, and a microcomputer for driving a vehicle. C
It comprises a PU 5 and a memory 6 such as a RAM and a ROM required for the operation of the CPU. The memory 6 is backed up by a battery (not shown). The current I _ch supplied from the commercial power source via the charger 7 is supplied to charge the battery 2 via the power receiving device 8 and the integrating wattmeter 9, and also supplies the load current I _L to the load electrical component 1. . Further, the battery 2 supplies the discharge current Id to the load electric component 1 through the integrating wattmeter 9 when it is not charged. As described above, since both charging and discharging of the battery are performed via the integrated wattmeter 9, both charging power and discharging power can be integrated and the output current I _{ch of the} charger 7 can be obtained.
Is to have been added to the charging current Is the load current I _L. When the transport vehicle charges while performing work, the charger output current is supplied from the charger 7 to both the battery 2 and the load electrical component 1 via the power receiving device 8. The electric power counted by the integrated wattmeter 9 is added (integrated) at the time of discharging, and subtracted at the time of charging. This measured value is digitized and read by the CPU 5. Information on the terminal voltage V _T of the battery 2 is also read by the CPU 5 for control.

FIG. 2 is a graph showing the charging efficiency γ of the battery. The vertical axis shows the charging efficiency and the horizontal axis shows the discharge rate C. The discharge rate C is 1C when the battery is charged at 10 amperes with the nominal battery capacity of 10 Ah (ampere hour), and corresponds to the charge current. Similarly, when charged at 20, 30, 40 and 50 amps, the discharge rate is 2C, 3
Represented as C, 4C and 5C. Charging capacity (charging current X hours)
Assuming that the charging efficiency is 1 when is converted to 100% battery capacity, the charging efficiency is 0.99 in 1C charging as shown in FIG. 2, and the efficiency decreases as the discharging rate increases,
With 5C charging, the charging efficiency is 0.90. This is because as the charging efficiency increases, rapid chemical changes are promoted, resulting in energy consumption due to gasification of hydrogen, oxygen, etc., resulting in reduced efficiency. However, the charging efficiency is guaranteed only until the battery terminal voltage (referred to as a gassing voltage) at which gas is suddenly generated. The characteristic between the discharge rate C and the charging efficiency γ (FIG. 2) is stored in the CPU 5 for carrying out the method of the present invention. Figure 3
Shows the characteristic curves of constant current charging and constant voltage charging.
The time to switch from constant current charging to constant voltage charging is when the battery terminal voltage reaches the above-mentioned gassing voltage.

FIG. 4 is a graph for explaining the operation of the embodiment of the present invention, in which the horizontal axis represents time and the vertical axis represents the remaining battery charge Cn (ampere hour). The initial capacity of the battery is represented by C ₀ , which is also a target value for recharging the battery having a decreased capacity to restore the battery capacity. C ₀ 'is the battery capacity when the power switch is turned on. When the power switch (not shown) of the mobile robot is activated to start the operation of the carrier vehicle, the discharge current Id starts to flow, and the remaining capacity Cn of the battery decreases with time as shown by the descending line in the figure. On the contrary, the integrated power meter value Cs increases. The CPU 5 always reads the integrated power meter value Cs at a constant sampling time Ts, and subtracts the integrated power meter value Cs from the battery capacity C ₀ 'at the time of turning on the power switch to obtain the remaining capacity (Cn = C ₀ ' -Cs). It is stored in the memory 6 of the CPU 5. Next, when the mobile robot performs charging at the same time while working at a certain time Tk, the remaining capacity Cn increases as shown by the rising line in the figure corresponding to the parallel charging, and conversely the integrating wattmeter The value Cs decreases.

Here, the CPU 5 reads the integrated power meter value Cs at the constant sampling time Ts as described above.
The CPU 5 performs the following operation in consideration of the charging efficiency γ mentioned above. Even if the charging method is the constant current-constant voltage charging shown in FIG. 3, since the discharge current flowing when the mobile robot is working changes according to the operating load, the actual charging current also changes. Therefore, the charging current Is flowing in the battery is calculated by the following equation (1) by the processing of the CPU 5 from the difference between the previously sampled integrated power meter value Cs ₋₁ and the latest sampled value Cs. Is = (Cs ₋₁ −Cs) / Ts (1) When the charging current Is is obtained in this way, the discharge rate corresponding to it is obtained. C is obtained, and the charging efficiency γ is obtained from the charging efficiency characteristic of FIG. 2 stored in the memory 6 in advance. Then, using this charging efficiency γ, the remaining capacity Cn obtained by the following equation (2) is stored in the memory 6. Cn = C ₀ '-Cs × γ (2) The mobile robot operates by repeating the charging and discharging described above. Can be done. The charging can be stopped at any time by a stop command from the CPU 5. For example, it is possible to issue a charge stop signal from the CPU 5 to the charger 7 via the transmission device 4, or to provide a contact between the battery 2 and the power receiving device 8 which can be controlled by the CPU 5. Time point T
in conjunction with the work, including the charge in k, and to have ended the work at the time Tk _+1, the remaining capacity Cn at that point in time Tk _{+1
(k + 1)} is often lower than the power-on capacity C ₀ ′. However, if the remaining capacity becomes equal to the capacity at power-on, and if the work is still continuing, only charging is terminated. Further, if only discharging without charging is started from the time point T _{k + 1} , the remaining capacity decreases and the integrated power count value increases as described above, and the repetition is continued. . If the repetition continues, the remaining capacity Cn eventually becomes zero, which causes an inconvenient situation. Therefore, before the situation occurs, charging is started at the time Tm when the predetermined remaining capacity Cn ′ is reached and the remaining capacity Cn is the power source. Input capacity C ₀ '
Under the control of the CPU 5, only charge is performed until the remaining capacity Cn
Is performed up to the time point Tn until the value becomes equal to the power-on capacity C ₀ '. Since only the charging is performed during this charging time (Tn-Tm), the remaining capacity can be restored to the initial value with a sharp increase curve as shown in the figure.

[0009]

As described above, according to the method of the present invention, the work by discharging alone and the work by using both charging and discharging are repeated while the charging efficiency is taken into consideration by mounting the integrating wattmeter and the CPU. Not only decreases rapidly, but it also becomes possible to recover the charge when the remaining battery capacity reaches a predetermined value in an extremely short time. Therefore, the conventional problem that the time required for charging becomes longer than the time required for work, and as a result, the transfer efficiency is lowered, is solved.

[Brief description of drawings]

FIG. 1 is a block circuit diagram showing an embodiment for carrying out the method of the present invention.

FIG. 2 is a graph showing characteristics of discharge rate and charging efficiency in this example.

FIG. 3 is a graph showing the characteristics of constant current charging and constant voltage charging in this example.

FIG. 4 is a graph showing changes in the remaining battery charge in this example.

[Explanation of symbols]

1: Load electrical parts 2: Battery 3: Electric vehicle drive device 4: Transmission device 5: CPU 6: Memory 7: Charger 8: Power receiving device 9: Integrated wattmeter

Claims (2)

[Claims] 1. In a self-propelled carrier that moves by using a battery as a drive source, the discharging power during operation and the charging power during charging are integrated by a control device provided inside the self-propelled carrier, and the battery is integrated. The battery charging method for a self-propelled guided vehicle, wherein the battery is charged to the initial battery capacity C ₀ when the remaining capacity Cn of the battery reaches a predetermined remaining capacity Cn ′. 2. The relationship of the charging efficiency γ corresponding to the charging current I _S is stored in advance in a memory, and the charging current I _S is measured by a charging power accumulator or a device for measuring the charging current inside the self-propelled carrier. The battery charging method for a self-propelled guided vehicle according to claim 1, wherein the remaining capacity Cn is detected in consideration of the charging efficiency γ obtained from the charging current I _S.