JP7469110B2 - Uninterruptible power system - Google Patents

Description

The present invention relates to an uninterruptible power supply, and in particular to one that has a power outage detection device.

Uninterruptible power supplies equipped with a secondary battery that supplies backup power to a load device connected to an external power source in the event of a power outage are known, for example, from Patent Document 1. Such uninterruptible power supplies are provided with a power outage detection means that detects the occurrence of a power outage so that the power supply to the load device is not stopped even in the event of a power outage, and when a power outage is detected, the secondary battery immediately begins discharging and power is supplied to the load device.

Conventional power outage detection means are known that are connected to an external power source, monitor the voltage of a charging line that supplies power from the external power source to charge a secondary battery, and determine that a power outage has occurred by detecting a drop in this voltage during a power outage. However, with this power outage detection means, when a power outage is detected and power is switched from the secondary battery to the load device, the charging line voltage quickly returns to normal because the charging line is connected to the output side of the secondary battery. This means that even when there is a power outage, it is undesirably determined that there is no power outage. For example, even if the power outage is resolved and commercial power is restored, this cannot be detected.

In addition to or instead of the above power outage detection means, power outages are also detected by monitoring the discharge current of secondary batteries. However, power outage detection by current detection takes longer than voltage detection, and there are cases where momentary power outages cannot be detected. Also, when the power consumption of the load device is small, the discharge current is also small, making it difficult to reliably detect power outages.

Patent Publication 2016-10288

The present invention was made to solve the above problems, and aims to provide a power outage detection means that can reliably and instantly detect power outages and is also inexpensive.

The present invention relates to
A secondary battery that supplies power to a load device connected to an external power source during a power outage;
a charging circuit that receives power from the external power source when there is no power outage and charges the secondary battery;
a switch element that is provided on a discharge line that discharges power from the secondary battery to the load device, the switch element having an open position that cuts off the discharge line when there is no power outage and a closed position that conducts the discharge line when there is a power outage;
a first rectifying element that is provided in series between the switch element and the secondary battery in the discharge line and selectively passes a current in a direction from the secondary battery to the load device;
a second rectifying element that is provided in parallel with the switch element and selectively passes a current in a direction from the load device to the secondary battery; and a second rectifying element that is provided in parallel with the switch element and selectively passes a current in a direction from the load device to the secondary battery, the second rectifying element being an element that allows a voltage of the external power source connected to the load device to be applied to the load device side of the first rectifying element when the switch element is in an open position and there is no power failure.
A power outage detection means for detecting a power outage;
Equipped with
The power failure detection means includes:
A voltage detection unit that detects a potential difference across the first rectifying element;
A power outage determination unit that determines a power outage state based on the potential difference detected by the voltage detection unit,
The power outage determination unit is configured to determine that a power outage has occurred when a voltage on the secondary battery side of the first rectifying element is higher than a voltage on the load device side of the first rectifying element.

According to the present invention, the potential difference between both sides of the first rectifying element provided on the discharge line is such that, during a non-power outage, the voltage on the load device side of the first rectifying element is higher than the voltage on the secondary battery side. During a power outage, the voltage on the load device side drops to zero, and the voltage on the load device side of the first rectifying element becomes lower than the voltage on the secondary battery side. Therefore, by determining whether the potential difference is positive or negative, it is possible to reliably detect the moment a power outage occurs, the moment a power outage returns to a non-power outage state, and even when a power outage is occurring.

In this case, it is preferable that the power failure detection means further includes a current detection unit that detects a discharge current from the secondary battery, and the power failure determination unit is configured to determine that the load device is stopped when the discharge current detected by the current detection unit falls below a predetermined value when it is determined that a power failure has occurred.

Conventionally, in order to grasp the operating status of a load device during a power outage, the load device is configured to output a signal indicating the operating status to the control device of the uninterruptible power supply. However, with the above configuration, the operating status of the load device can be managed without using a signal from the load device. In particular, by using a charge/discharge ammeter that has traditionally been used to manage charging and discharging currents as the current detection unit that detects the discharge current, it is possible to eliminate the wiring for the above signal from the load device, and this can be achieved extremely inexpensively.

Here, the power failure detection means preferably includes a charge/discharge control unit that controls charging/discharging of the secondary battery to perform at least charging and discharging processes, and the power failure determination unit is preferably provided in the charge/discharge control unit.

It is also preferable that the charge/discharge control unit includes a processor, and the power failure determination unit is configured to determine that a power failure has occurred when a signal corresponding to the power failure is input from the voltage detection unit during processing other than the discharge processing, and to start the discharge processing using an interrupt function of the processor.

This invention uses the interrupt function of the processor, so when a power outage occurs, a signal corresponding to the power outage is immediately input to the processor and discharge processing can be started at the same time, making it ideal for dealing with momentary power outages.

The current detection unit is preferably provided on a common ground line connected to the external power supply, the load device, and the secondary battery. It is also preferable that the switch element and the second rectifier element are configured with a single MOSFET. Furthermore, the external power supply is preferably a DC power supply driven by external power.

FIG. 1 is a schematic circuit diagram illustrating an embodiment of an uninterruptible power supply according to the present disclosure.

As shown in FIG. 1, the uninterruptible power supply 10 of this embodiment includes a secondary battery 1 that supplies power to a load device 21 connected to an external power source 22 during a power outage. Here, the external power source 22 receives power from a commercial AC power source and supplies DC power to the load device 21 (e.g., a server).

The secondary battery 1 is generally configured by connecting multiple secondary battery cells in series or in series and parallel. In this embodiment, the positive electrode side of the secondary battery 1 is connected to an external power source 22 via a charging line 4, and is also connected to a load device 21 via a discharging line 3 arranged in parallel with the charging line 4.

On the charging line 4, there is provided a charging circuit 8 for receiving power from the external power source 22 to charge the secondary battery 1 when there is no power outage, i.e., when there is no power outage, and a rectifying element, such as a diode 9, that passes only current in the direction toward the secondary battery 1, i.e., the charging current.

On the other hand, on the discharge line 3, there is provided a switch element 5 having an open position that cuts off the discharge line 3 when there is no power outage and a closed position that makes the discharge line 3 conductive when there is a power outage, and a first rectifier element 7 that selectively passes only the current flowing from the secondary battery 1 toward the load device 21, i.e., the discharge current. The first rectifier element 7 is connected in series with the switch element 5 to the secondary battery 1 side of the switch element 5.

In addition, a second rectifying element 6 is provided in parallel with the switch element 5 on the discharge line 3. The second rectifying element 6 allows the input voltage of the load device 21 (i.e., the supply voltage of the external power source 22 connected to the load device 21) to be applied to the first rectifying element 7 even when the switch element 5 is in the open position.
Here, the first rectifying element 7 can be configured, for example, by a diode, and the combination of the switch element 5 and the second rectifying element 6 can be configured by one MOSFET.
Also, a voltage detector 11 is provided for detecting the potential difference across the first rectifying element 7 .

The negative electrode side of the secondary battery 1 is connected to a ground line 13. A current detection unit 12, for example an ammeter, is provided on the ground line 13 so as to be able to measure current in both directions, and the current detection unit 12 can measure the charging current when the secondary battery 1 is being charged, and the discharging current when the secondary battery 1 is being discharged.

The uninterruptible power supply 10 includes a secondary battery 1, a charging circuit 8, a diode 9, a switch element 5, a first rectifier element 7, a second rectifier element 6, and a voltage detector 11, as well as a control device 2 that controls the charging and discharging of the secondary battery 1.

A signal A, which is detected by the voltage detector 11 and which indicates the potential difference across the first rectifying element 7, is input to an input port 15 of the control device 2. A signal B, which is detected by the current detector 12 and which indicates the current value, is input to an input port 16 of the control device 2. A signal C for opening and closing the switch element 5 is output from an output port 17 of the control device 2.
In this embodiment, the control device 2 includes a charge/discharge control unit 23 for controlling the charging and discharging of the secondary battery 1 , and the charge/discharge control unit 23 is provided with a processor 24 .

The uninterruptible power supply 10 of this embodiment is equipped with a power outage detection means for detecting a power outage, and this power outage detection means is configured with a voltage detector 11 and a power outage determination unit that determines the state of a power outage based on the potential difference signal from the voltage detector 11, and this power outage determination unit is provided in the charge/discharge control unit 23 arranged in the control device 2.
In this embodiment, the power failure detection means further includes a current detection unit 12 .

Next, the operation of the power failure detection means when transitioning from no power failure to a power failure will be described.
When there is no power outage, the switch element 5 for discharging is open, but the voltage of the external power source 22 is applied to the load device 21 side of the first rectifier element 7 via a second rectifier element 6 arranged in parallel with the switch element 5, bypassing the switch element 5, while the voltage of the secondary battery 1, which is lower than the voltage of the external power source 22, is applied to the secondary battery 1 side of the first rectifier element 7.
In this embodiment, the voltage of the external power source 22 is set to always be higher than the voltage of the secondary battery 1, so that when there is no power outage, the voltage on both sides of the first rectifier element 7 is higher on the load device 21 side and lower on the secondary battery 1 side. At this time, signal A from the voltage detector 11 is set to be proportional to the voltage obtained by subtracting the voltage on the secondary battery 1 side from the voltage on the load device 21 side, so that when there is no power outage, signal A represents a positive value.

On the other hand, during a power outage, the voltage of the external power source 22 becomes zero, so that the voltage on both sides of the first rectifier element 7 is lower on the load device 21 side and higher on the secondary battery 1 side. Therefore, signal A during a power outage will show a negative value.

Signal A representing the voltage value is sent to input port 15 of control device 2, but the interrupt port of processor 24 of charge/discharge control unit 23 in control device 2 constantly monitors the signal representing the positive/negative of signal A (positive/negative signal), and when this positive/negative signal changes from positive to negative, the interrupt function of processor 24 causes processor 24 to, for example, suspend charging processing and perform a process of determining that a power outage has occurred as a power outage determination process, and when processor 24 determines that a power outage has occurred, charge/discharge control unit 23 of control device 2 outputs signal C from output port 17 of control device 2 to close switch element 5. At this time, charge/discharge control unit 23 can also perform processes such as displaying a lamp indicating a power outage.

Conversely, when the power is restored and the power is no longer in a power outage state, the value of signal A becomes negative, so the processor 24 determines that the power is no longer in a power outage state, and the charge/discharge control unit 23 outputs signal C to switch element 5 to open switch element 5.

The power outage detection means of this embodiment, which operates as described above, is configured with a voltage detector 11 and a power outage determination unit that determines the state of a power outage based on the potential difference signal A from the voltage detector 11, and as explained above, the power outage determination process of the power outage determination unit is performed by a processor 24 provided in the charge/discharge control unit 23.

Here, the power outage detection means may also include a load device monitoring unit that monitors the operating state of the load device 21 during a power outage. In this case, the load device monitoring unit of the power outage detection means also includes a current detection unit 12 arranged on the ground line 13. Signal B is output from the current detection unit 12 and input to the charge/discharge control unit 23 via the input port 16. During a power outage, signal B represents a value proportional to the discharge current. Then, the charge/discharge control unit 23 is configured to determine that the load device 21 is stopped when signal B falls below a predetermined value. This makes it possible to monitor the operating state of the load device 21.

REFERENCE SIGNS LIST 1 Secondary battery 2 Control device 3 Discharge line 4 Charging line 5 Switch element 6 Second rectifying element 7 First rectifying element 8 Charging circuit 9 Diode 10 Uninterruptible power supply 11 Voltage detector 12 Current detector
13 Ground line 15, 16 Input port 17 Output port 21 Load device 22 External power supply 23 Charge/discharge control unit 24 Processor

Claims (7)

A secondary battery that supplies power to a load device connected to an external power source during a power outage;
a charging circuit that receives power from the external power source when there is no power outage and charges the secondary battery;
a switch element that is provided on a discharge line that discharges power from the secondary battery to the load device, the switch element having an open position that cuts off the discharge line when there is no power outage and a closed position that conducts the discharge line when there is a power outage;
a first rectifying element that is provided in series between the switch element and the secondary battery in the discharge line and selectively passes a current in a direction from the secondary battery to the load device;
a second rectifying element that is provided in parallel with the switch element and selectively passes a current in a direction from the load device to the secondary battery; and a second rectifying element that is provided in parallel with the switch element and selectively passes a current in a direction from the load device to the secondary battery, the second rectifying element being an element that allows a voltage of the external power source connected to the load device to be applied to the load device side of the first rectifying element when the switch element is in an open position and there is no power failure.
A power outage detection means for detecting a power outage;
Equipped with
The power failure detection means includes:
A voltage detection unit that detects a potential difference across the first rectifying element;
A power outage determination unit that determines a power outage state based on the potential difference detected by the voltage detection unit,
An uninterruptible power supply device, wherein the power outage determination unit is configured to determine that a power outage has occurred when a voltage on the secondary battery side of the first rectifying element is higher than a voltage on the load device side. The uninterruptible power supply according to claim 1, wherein the power failure detection means further includes a current detection unit that detects a discharge current from the secondary battery, and the power failure determination unit is configured to determine that the load device is stopped if the discharge current detected by the current detection unit falls below a predetermined value when it is determined that a power failure has occurred. The uninterruptible power supply according to claim 1 or 2, further comprising a charge/discharge control unit that controls charging/discharging of the secondary battery to perform at least charging and discharging processes, and the power failure determination unit is provided in the charge/discharge control unit. The uninterruptible power supply according to claim 3, wherein the charge/discharge control unit includes a processor, and the power failure determination unit is configured to determine that a power failure has occurred using an interrupt function of the processor when a signal corresponding to the power failure is input from the voltage detection unit during processing other than the discharge processing, and to start the discharge processing. 3. The uninterruptible power supply according to claim 2 , wherein the current detection unit is provided on a common ground line connected to the external power supply, the load device, and the secondary battery. An uninterruptible power supply according to any one of claims 1 to 4, in which the switch element and the second rectifier element are configured with a single MOSFET. 7. The uninterruptible power supply according to claim 1 , wherein the external power supply is a DC power supply driven by external power.

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