JPH08126211A - Charge/discharge controller - Google Patents

Abstract

PURPOSE: To improve the working ratio of the load by canceling a discharge inhibition state to restart discharge when a current supplied from a d.c. power supply is detected even after the terminal voltage of a storage battery has dropped to the predetermined level of discharge inhibition. CONSTITUTION: A current from a d.c. power supply with unstable output (e.g. a solar cell 1) flows through a reverse blocking diode 2 and a CT 10, together with the output of a storage battery 4, to a load 6. The passage of the current is made or broken by means of a switch 5. A charge/discharge control unit 13 outputs a load connection control signal 9 according to the input signals from the CT 10 and a storage battery voltage detection unit 8, and thereby opens or closes the switch 5. When the output of the solar cell 1 is reduced and the output voltage of the storage battery 4 drops to a specified value, a load connection control signal 9 opens the switch 5 to bring the system into the discharge inhibition state. When the CT 10 thereafter detects a current from the solar cell 1 having a specified value of above, a charge/discharge controller 3 closes the switch 5 to restart discharge even if the terminal voltage has not been recovered. This improves the working ratio of the load.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charge / discharge control device. More specifically, the present invention relates to a charge / discharge control device provided with means for detecting a current supplied from a DC power source whose output is unstable or a voltage corresponding to the current.

[0002]

2. Description of the Related Art A conventional charge / discharge control device is shown in FIG.
And the technique shown in FIG. 11 is known.

FIG. 10 is a block circuit diagram of a charge / discharge control device. 1 is a solar battery which is an example of a power source with unstable output, 2 is a backflow prevention diode, 3 is a discharge control unit, 4 is a storage battery, 5 is a switch or element for connecting a load, and б is a load. Reference numeral 8 is a storage battery voltage detection unit, which is input to the discharge control unit 3. Reference numeral 9 is a load connection control signal, which is output from the discharge control unit 3 and is input to the load connection switch 5 or element 5.

FIG. 11 is a timing chart showing the operation of FIG. The vertical axis of each graph shown in FIG. 11 represents the following contents.

Graph (a): Charging current by solar cell Graph (b): Battery voltage graph (c): Load permission state graph (d) showing whether the battery is connected to the load connection terminal and the load can be used : Load request state indicating whether or not a load is connected On the other hand, the horizontal axis in FIG. 11 represents time common to each graph. On this horizontal axis, a-7 is at the start of load connection, b
At the start of discharge inhibition when -7 has reached the predetermined voltage 1 of f, that is, the discharge inhibition voltage, d-7 has reached the predetermined voltage 2 of g, that is, the discharge permission voltage, and the discharge inhibition is released. E-7 is the end of the load connection.

The operation of the charge / discharge control device will be described below.

The recording start time (left end on the horizontal axis) in FIG. 11 is
In FIG. 10, almost no electromotive force is generated by the solar cell 1 and almost no current is stored in the storage battery 4 via the backflow prevention diode 2. At this time, the charge / discharge control device is not in the discharge prohibited state. Then a
If a load is connected from the time point of −7, the storage battery 4 is discharged with the lapse of time, and the terminal voltage drops.

This voltage is taken into the discharge control unit 3 by the storage battery voltage detection unit 8 and drops to f, which is a predetermined voltage 1 that must terminate the discharge determined by the storage battery 4, when the discharge control unit 3 loads the load. The connection control signal 9 is output and the load connection switch or the element 5 is opened. This timing is b-7 in FIG. Then
Since the current to the load б does not flow through the load connecting switch or the element 5, the discharging of the storage battery 4 is stopped.
As a result, as shown in the graph (b) of FIG.
Voltage starts to rise.

In the conventional charge / discharge control device, the condition for permitting the discharge again is to recover the voltage of the self (storage battery 4) or to connect it, in order to avoid oscillation of the overdischarge prevention circuit. Storage battery 4 by charging with solar cell 1
The terminal voltage of 1 is higher than the above-mentioned f which is the predetermined voltage 1 and is a predetermined voltage 2 corresponding to the storage battery to be used, which is g. Therefore, when the discharge is prohibited and the terminal voltage of the storage battery 4 is between f which is the predetermined voltage 1 and g which is the predetermined voltage 2, even if the current from the solar cell 1 exists with a margin. However, the current was supplied only to the storage battery 4, and even if a load was connected, the load could not be used because the switch or element for connecting the load was in the open state. That is, in FIG. 4, since the current cannot be supplied to the load from the time point b-2 to the time d-2, the load cannot be used. That is, even if the user connects the load, the current cannot be supplied to the load, which is a great disadvantage for the user.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a charging / discharging control device capable of increasing the load operating rate and realizing stable load operation by shortening the time period when the load cannot be used. To aim.

[0011]

The present invention relates to a current supplied from a DC power supply or a current supplied from the DC power supply in a charge / discharge control device having an overdischarge prevention function used together with a DC power supply and a storage battery whose output is unstable. When a means A for detecting a voltage is provided and the terminal voltage of the storage battery drops to a discharge prohibited state, even if the terminal voltage of the storage battery does not recover to the value before the drop, When it is detected by the means A that the current is being supplied, the discharge inhibition state at the storage battery voltage is released, and the discharge of the DC power supply is restarted.

Further, according to the present invention, when the discharge inhibition state of the charge / discharge control device is brought into an oscillating state by releasing the discharge inhibition state, the solar cell for instructing to release the discharge inhibition state at the storage battery voltage. It is characterized in that the charging current value is gradually increased.

Furthermore, according to the present invention, when the discharge prohibition state is released and the discharge prohibition circuit of the charge / discharge control device is in an oscillating state, the solar cell is instructed to release the discharge prohibition state at the storage battery voltage. The charging current value is gradually increased, and at the same time, the voltage value indicating the discharge prohibited state in the storage battery voltage is also sequentially increased.

[0014]

[Action]

(Claim 1) According to the invention of claim 1, since the means for detecting the current supplied from the DC power supply or the voltage corresponding to the current is provided, the terminal voltage E of the storage battery drops and the discharge prohibition state is set. After that, even if the terminal voltage of the storage battery does not rise to the original value E, it is possible to detect that there is current supply from the DC power supply. As a result, when this detection signal is present, the discharge inhibition state is canceled and the current supply from the storage battery to the load is restarted, so the load operating rate can be improved.

According to the invention of claim 2, when the discharge prohibition circuit is in an oscillating state due to the release of the discharge prohibition state, the release of the discharge prohibition is stopped and the occurrence of the oscillation state is avoided. Since the control to operate is provided, stable load operation can be realized.

(Claim 3) According to the invention of claim 3, when the discharge prohibition circuit of the charge / discharge control device is oscillated by the release of the discharge prohibition state, the discharge prohibition state at the storage battery voltage is set. Since the charging current value by the solar cell for instructing the cancellation of the above is sequentially increased, the voltage value for instructing the discharge inhibition state in the storage battery voltage is also sequentially increased, so that the oscillation of the discharge control circuit can be avoided and the storage battery can be avoided at the same time. It is also possible to increase the voltage value.

[0017]

[Example embodiment]

(DC power source with unstable output) In the present invention, examples of the "DC power source with unstable output" include sunlight, solar heat,
Geothermal power, wind power, tidal power, or hydraulic power is used as an energy source, and a power supply whose output is direct current can be mentioned. In particular,
In a direct current power source that uses sunlight as an energy source, that is, a solar cell, for example, without using an electric power company, its user
Immediately becoming a general consumer. Therefore, it is strongly desired to improve the load utilization rate, which is the object of the present invention.

(Storage Battery) In the present invention, examples of the “storage battery” include a lead storage battery, a nickel-cadmium battery, and a lithium battery. In particular, a lightweight and small storage battery is preferable when used with a solar cell that is lightweight and capable of being a thin plate.

(Charging / Discharging Control Device Having Over-Discharge Prevention Function) In the present invention, the "charging / discharging control device having an over-discharge prevention function" includes, for example, the one shown in FIG.

FIG. 1 is a block circuit diagram of the charge / discharge control device. As the above-mentioned "DC power source with unstable output", the solar cell 1 is used as the "means A for detecting the current supplied from the DC power source or the voltage corresponding to the current", which will be described later, and the solar cell charging current detection. It has a section 10. Due to the function of the solar cell charging current detection unit 10, the electricity generated by the solar cell 1 can be efficiently supplied to the load.

(Means A for detecting current supplied from DC power supply or voltage corresponding to the current) In the present invention, "means A for detecting current supplied from DC power supply or voltage corresponding to the current" , For example, the solar cell charging current detection unit 10 (FIG. 1), the solar cell charging current detection resistor 12
(FIG. 5), a solar cell output voltage detecting unit 16 (FIG. 7) is included. In particular, a solar cell output voltage detection unit 16 (FIG. 7) is preferable because it can be manufactured at low cost and the oscillation state of the discharge inhibition circuit can be avoided.

[0022]

EXAMPLE An example of the present invention will be described below.

(Embodiment 1) This embodiment is different from the conventional one in that a solar cell charging current detecting section is provided in the charge / discharge control device. This example will be described below with reference to FIGS. 1 and 2.

FIG. 1 is a block circuit diagram of the charge / discharge control device of the present invention. In FIG. 1, 1 is a solar battery which is an example of a DC power supply whose output is unstable, 2 is a backflow prevention diode, 3 is a discharge controller, 4 is a storage battery, 5 is a switch or element for connecting a load, 6 is a load, 8 Is the battery voltage detector,
Reference numeral 9 is a load connection control signal, 10 is a solar cell charging current detection unit, and 8 and 10 are input to the discharge control unit 3.

FIG. 2 is a timing chart showing the operation of FIG. The vertical axis of each graph shown in FIG. 2 represents the following contents.

Graph (a): Charging current by solar cell Graph (b): Storage battery voltage graph (c): Load permission state graph showing whether the storage battery is connected to the load connection terminal and the load can be used (graph) (d) : Load request state indicating whether or not a load is connected On the other hand, the horizontal axis of FIG. 2 represents time common to each graph. On this horizontal axis, a-1 is the start of load connection, b
-1 is the predetermined voltage 1 of f, that is, when the discharge inhibition starts when the discharge inhibition voltage is reached, c-1 indicates that the charging current by the solar cell is h
When the predetermined current is reached, the discharge prohibition is released, and the above-described load permission state is permitted, e-1 is the end of the load connection, and g is the predetermined voltage 2, that is, the discharge permission voltage.

The operation of the charge / discharge control device will be described below.

At the recording start time (left end on the horizontal axis) in FIG. 2, there is almost no electromotive force due to the solar cell 1 in FIG.
This shows a state in which almost no current is stored in the storage battery 4 via the backflow prevention diode 2. At this time, the charge / discharge control device is not in the discharge prohibited state. After that, a-1
If the load is connected from the point of time, the storage battery 4 is discharged with the lapse of time, and the terminal voltage drops.

This voltage is taken into the discharge control unit 3 by the storage battery voltage detection unit 8, and when it drops to f, which is the predetermined voltage 1 that must terminate the discharge determined by the storage battery 4, the discharge control unit 3 loads the load. The connection control signal 9 is output and the load connection switch or the element 5 is opened. This timing is b-1 in FIG. Then, the current to the load 6 stops flowing through the switch for connecting the load or the element 5, so that the discharge of the storage battery 4 is stopped. As a result, the voltage of the storage battery 4 starts to rise as shown in the graph (b) of FIG.

The operation after the voltage rise of the storage battery 4 is the difference between the present invention and the conventional one. That is, in the present invention, as shown in the graph (a) of FIG. 2, when the charge from the solar cell 1 increases, the solar cell charge current detection unit 10 is used to determine the charge current of the solar cell 1. By detecting, the output current of the solar cell 1 can be detected. As a result, when the value of the charging current exceeds the predetermined current h, it becomes possible to immediately output the load connection signal for canceling the discharge inhibition state. Therefore, in the charge / discharge control device of this example, the current supply from the storage battery 4 to the load can be immediately restarted. Therefore, the conventional problem, that is, the problem that the load cannot be used unless the terminal voltage of the storage battery 4 rises to the predetermined voltage 2 (g) higher than the predetermined voltage 1 (f), is solved, and the load operating rate can be improved. It was

(Embodiment 2) The present invention is different in that a resistor for converting a current into a voltage is provided in place of the solar cell charging current detector of the embodiment 1. As shown in Drawing 3 and Drawing 4, it carried out using resistance 12 for solar cell charge current detection, and resistance voltage detection part 13 for solar cell charge current detection. However, FIG. 3 is a block circuit diagram of the charge and discharge control device of the present invention, and FIG. 4 is a timing chart showing the operation of FIG. In FIG. 4, the graph (a) ′ represents the solar cell charging current detection resistance voltage which is the difference from the storage battery voltage.

Other points were the same as in Example 1.

In this example, a resistor for converting a current into a voltage is used instead of the solar cell charging current detector,
The equivalent detection function could be realized at a lower cost. Therefore, the charge / discharge control device can be provided at low cost.

(Embodiment 3) The present invention is different in that a solar cell output voltage detector is provided in place of the current detection resistor of Embodiment 2. FIG. 5 is a block circuit diagram of the charge / discharge control device of the present invention, and FIG. 6 is a timing chart showing the operation of FIG. In FIG. 6, the graph (a) ″ is
It represents the solar cell output voltage.

Other points were the same as in Example 2.

In this example, the solar cell output voltage detecting section was used in place of the current detecting resistor, so that the loss due to the current detecting resistor could be reduced. As a result, the change in the output voltage of the solar cell can be detected with high sensitivity, and it is possible to determine at a higher speed whether or not the predetermined voltage 4, that is, h ″ is exceeded. Further, the current detection circuit has a simpler configuration. As a result, it has become possible to provide a charge / discharge control device at a lower cost.

Comparative Example In this example, the above-described Examples 1 to 1 were used.
In No. 3, the case where the discharge prohibition circuit becomes the oscillation state by releasing the discharge prohibition state will be described.

FIG. 7 is a timing chart showing the operation of the block circuit diagram (FIG. 1) of the first embodiment. The vertical axis of each graph shown in FIG. 7 represents the following contents.

Graph (a): Solar battery charging current Graph (b): Storage battery voltage graph (c): Load permission state graph (d) showing whether the storage battery is connected to the load connection terminal and the load can be used : Load request state indicating whether or not a load is connected On the other hand, the horizontal axis of FIG. 7 represents time common to each graph. On this horizontal axis, a-4 is at the start of load connection, b
-4 is the first voltage at the start of discharge prohibition when the voltage reaches the predetermined voltage 1 of f, that is, the discharge prohibition voltage, and c-4 cancels the discharge prohibition when the charging current by the solar cell reaches the predetermined current of h, and the above-mentioned load permission state Is the first time, and e-4 is the end of the load connection, and g is the predetermined voltage 2, that is, the discharge permission voltage. However, like b-4, b-4 ′ and b-4 ″ represent the second and third times of the start of discharge inhibition when the predetermined voltage 1 of f, that is, the discharge inhibition voltage is reached. ,
c-4 ′ and c-4 ″ are, like c-4, when the charging current by the solar cell reaches the predetermined current of h, the discharge prohibition is released, and the above-mentioned load permission state is permitted. Shows the second and third times.

As shown in FIG. 7, when the storage battery voltage drops rapidly after the discharge is permitted again, the discharge prohibition state (c-4 ') again occurs, and the above-mentioned discharge prohibition state is released. When the condition to be satisfied is satisfied, the discharge prohibited state is released (b-4 ′). This repetition (b-
4 ", c-4" and thereafter), the discharge control circuit is in an oscillating state. As a result, the operation of the connected load becomes unstable, which is not preferable. Further, in the case where a mechanical switch is used as the load connection control switch or the element 5, there is a problem that the reliability of the entire system is deteriorated, which is not preferable.

(Embodiment 4) In the present embodiment, when the discharge prohibition state is released and the discharge prohibition circuit of the charging / discharging control device is in an oscillating state, a solar cell for instructing to release the discharge prohibition state at the storage battery voltage This is different from the first embodiment in that the charging current value according to the above is sequentially increased. The generation of a rapid voltage drop in the oscillation state was performed by providing a means for detecting the amount of voltage change per unit time.

FIG. 8 is a timing chart showing the operation of this example. The vertical axis of each graph shown in FIG. 8 represents the following contents.

Graph (a): Charging current by solar cell Graph (b): Storage battery voltage graph (c): Load permission state graph showing whether the storage battery is connected to the load connection terminal and the load can be used Graph (d) : Load request state indicating whether or not a load is connected On the other hand, the horizontal axis of FIG. 8 represents time common to each graph. On this horizontal axis, a-5 is at the start of load connection, b
-5 is the first voltage at the start of the discharge inhibition when the voltage reaches the predetermined voltage 1 of f, that is, the discharge inhibition voltage, c-5 releases the discharge inhibition when the charging current by the solar cell reaches the predetermined current of h, and the above-mentioned load permission state is reached. Is the first time when is permitted, e-1 is the end of the load connection, and g is the predetermined voltage 2, that is, the discharge permission voltage.

In this example, after the occurrence of a rapid voltage drop (c-5 ') in the oscillating state is detected, the second time (b-5) at the time of starting the discharge inhibition when the predetermined voltage 1 of f, that is, the discharge inhibition voltage is reached. In the curve of the storage battery voltage rising from '), the charging current by the solar cell reaches the predetermined current of h'and the discharge prohibition is released. Further, after detecting the occurrence of a rapid voltage drop (c-5 ″) in the oscillation state, f
In the curve of the storage battery voltage that rises from the third time (b-5 ") at the start of the discharge inhibition when the predetermined voltage 1 of 1, that is, the discharge inhibition voltage is reached, the charging inhibition by the solar cell reaches the predetermined current of h" It was decided to. However,
It is assumed that h, h ′, and h ″ have the following relationship.

H <h '<h ”As a result, the oscillation of the discharge control circuit described in the comparative example can be avoided, the system reliability can be improved, and the normal operation of the load can be guaranteed. It was

In this example, as the means for detecting the occurrence of the rapid voltage drop in the oscillating state, the case where the amount of voltage change per unit time is detected has been described, but the time interval at which the voltage drop occurs is also detected. It was confirmed separately that similar results were obtained.

(Embodiment 5) In this embodiment, when the discharge prohibition state is released and the discharge prohibition circuit of the charging / discharging control device is in an oscillating state, the solar cell is instructed to release the discharge prohibition state at the storage battery voltage. The present embodiment is different from the fourth embodiment in that the charging current value according to step 1 is sequentially increased, and at the same time, the voltage value indicating the discharge prohibition state in the storage battery voltage is also sequentially increased.

FIG. 8 is a timing chart showing the operation of this example.

In the graph (b) of FIG. 8, each voltage value indicating the discharge prohibited state at the storage battery voltage, that is, b-
The following relationship was established between 6 ', b-6 ", and b-6"'.

B-6 '<b-6 "<b-6"' The other points were the same as in Example 4.

In this example, the oscillation of the discharge control circuit can be avoided, and at the same time, the value of the storage battery voltage is gradually increased to the predetermined voltage 2 (g).
That is, it became possible to approach the discharge permission voltage. As a result, even if the load is used or the discharge control circuit oscillates, the storage battery voltage can be raised to the predetermined voltage 2 (g), which enables more efficient operation of the system in terms of time.

[0052]

【The invention's effect】

(Claim 1) As described above, according to the invention of claim 1, a charge / discharge control device capable of improving the load operation rate can be obtained.

(Claim 2) According to the invention of claim 2, there is provided a charge and discharge control device capable of avoiding oscillation of the discharge control circuit.

(Claim 3) According to the invention of claim 3, it is possible to obtain a charge / discharge control device capable of avoiding oscillation of the discharge control circuit and at the same time increasing the value of the storage battery voltage.

[Brief description of drawings]

FIG. 1 is a block circuit diagram of a charge / discharge control device according to a first embodiment.

FIG. 2 is a timing chart showing the operation of FIG.

FIG. 3 is a block circuit diagram of a charge / discharge control device according to a second embodiment.

FIG. 4 is a timing chart showing the operation of FIG.

FIG. 5 is a block circuit diagram of a charge / discharge control device according to a third embodiment.

FIG. 6 is a timing chart showing the operation of FIG.

FIG. 7 is a timing chart showing the operation of a comparative example.

FIG. 8 is a timing chart showing the operation of the charge / discharge control device according to the fourth embodiment.

FIG. 9 is a timing chart showing the operation of the charge / discharge control device according to the fifth embodiment.

FIG. 10 is a block circuit diagram of a charge / discharge control device according to a conventional example.

11 is a timing chart showing the operation of FIG.

[Explanation of symbols]

1 solar cell (an example of a power source with unstable output), 2 backflow prevention diode, 3 discharge control unit, 4 storage battery, 5 load connection switch or element, 6 load, 8 storage battery voltage detection unit, 9 load connection control signal, 10 solar cell charging current detection part, 12 solar cell charging current detection resistance, 13 solar cell charging current detection resistance voltage detection part, 16 solar cell output voltage detection part, a-1, a-2, a-3, a -4, a-5, a-6, a
-7 First time when load connection starts, b-1, b-2, b-3, b-4, b-5, b-6, b
-7 First time when discharge prohibition starts, b-4 ', b-5', b-6 'Second time when discharge prohibition starts, b-4 ", b-5", b-6 "When discharge prohibition starts 3rd time, b-5 "', b-6"' 4th time at the start of discharge inhibition, c-1, c-2, c-3, c-4, c-5, c-6, d
-7 First time when discharge prohibition is released, c-4 ', c-5', c-6 'Second time when discharge prohibition is started, c-4 ", c-5", c-6 "When discharge prohibition is started 3rd time, c-5 "', c-6"' 4th time at the start of discharge inhibition, e-1, e-2, e-3, e-4, e-7 At the end of load connection, t1, t2 , T3, t4, t5, t6, t7 first discharge prohibition period, t4 ', t5', t6 'second discharge prohibition period, t4 ", t5", t6 "third discharge prohibition period, t5"' , T6 "'The fourth discharge prohibition period.

Claims (3)

[Claims] 1. A charging / discharging control device having an overdischarge prevention function used together with a DC power supply and an accumulator with an unstable output, having means A for detecting a current supplied from the DC power supply or a voltage corresponding to the current. In addition, when the terminal voltage of the storage battery drops and the discharge prohibition state is reached, even if the terminal voltage of the storage battery does not recover to the value before the drop, it is possible that the current is supplied from the DC power supply. A charging / discharging control device characterized in that, when detected by the means A, the discharge inhibition state at the storage battery voltage is released and the discharge of the DC power supply is restarted. 2. When the discharge prohibition circuit of the charge / discharge control device is in an oscillating state by releasing the discharge prohibition state,
The charging / discharging control device according to claim 1, wherein the charging current value by the solar cell that instructs to release the discharge prohibited state at the storage battery voltage is sequentially increased. 3. When the discharge prohibition circuit of the charge / discharge control device is in an oscillation state due to the release of the discharge prohibition state,
The charging current value by the solar cell for instructing to release the discharge prohibited state at the storage battery voltage is sequentially increased, and at the same time, the voltage value for instructing the discharge prohibited state at the storage battery voltage is also sequentially increased. The charge / discharge control device according to 1 or 2.