KR102223422B1 - Uninterruptible power supply and method for thereof - Google Patents

Abstract

Disclosed is an uninterruptible power supply. An uninterruptible power supply according to an embodiment of the present invention includes a converter that converts AC power input from a commercial power source into DC power, an inverter that converts DC power into AC power and supplies it to a load, a battery, and a device in a first mode. A control signal is generated to supply power to the load by discharging the battery until the remaining amount of the battery reaches a preset lower limit value in the set time period, and when the load exceeds a preset reference value in the second mode, the commercial power supply is inputted. It includes a control unit that limits the input current and discharges the battery to generate a control signal for supplying power to the load.

Description

Uninterruptible power supply and its control method TECHNICAL FIELD

The present invention relates to an uninterruptible power supply and a control method thereof, and more particularly, to an uninterruptible power supply and a control method thereof capable of operating within a range having maximum efficiency even when a load amount changes.

Uninterruptible Power Supply (UPS) is widely used to prepare for accidents such as power outages, instantaneous power outages, and voltage drops in industrial fields that require constant and stable power supply.

This uninterruptible power supply has maximum efficiency when supplying 60 to 80% of the rated capacity of power to the load end. Therefore, in order for the uninterruptible power supply to operate in a range having the maximum efficiency, the capacity of the uninterruptible power supply should be selected in consideration of the size of the load.

When the amount of load over time is constant, since the amount of load can be easily predicted, it is possible to easily determine the capacity of the uninterruptible power supply that can operate with maximum efficiency.

However, it is difficult to determine the capacity of an uninterruptible power supply that can operate with maximum efficiency when the load amount varies over time. Loads with large changes in load capacity over time include conveyor belts, elevators, escalators, screen doors, and radars.

In the case of a load having the above characteristics, if the capacity of the uninterruptible power supply is determined according to the maximum load, the maximum efficiency operation range is determined based on the load having a temporary peak value, so the capacity of the uninterruptible power supply may increase unnecessarily. There is a problem that there is.

Alternatively, if the capacity of the uninterruptible power supply device is determined according to a typical load amount by excluding the temporary peak value, there arises a problem that the operation efficiency of the uninterruptible power supply device may be deteriorated.

Accordingly, there has been a need for an uninterruptible power supply device capable of stably supplying power to a load having a characteristic of a large change in the amount of load over time and capable of operating within the maximum efficiency range.

The present invention has been conceived to solve the above problems, and an object of the present invention is to provide an uninterruptible power supply device capable of operating within a maximum efficiency range while stably supplying power to a load having a large fluctuation amount.

The technical problems of the present invention are not limited to the technical problems mentioned above, and other technical problems that are not mentioned will be clearly understood by those skilled in the art from the following description.

Disclosed is an uninterruptible power supply. An uninterruptible power supply according to an embodiment of the present invention includes a converter that converts AC power input from a commercial power source into DC power, an inverter that converts DC power into AC power and supplies it to a load, a battery, and a device in a first mode. A control signal is generated to supply power to the load by discharging the battery until the remaining amount of the battery reaches a preset lower limit value in the set time period, and when the load exceeds a preset reference value in the second mode, the commercial power supply is inputted. It includes a control unit that limits the input current and discharges the battery to generate a control signal for supplying power to the load.

According to an embodiment of the present invention, the controller receives a first mode operation time and a lower limit value of the remaining battery capacity when the first mode is set, and when the first mode operation time enters, the output voltage of the converter is applied to the battery. It is possible to generate a control signal lower than the voltage.

According to an embodiment of the present invention, when the remaining capacity of the battery reaches the preset lower limit value, the control unit generates a control signal such that the output voltage of the converter has a value higher than the operating voltage of the battery. I can.

According to an embodiment of the present invention, when the controller senses the current supplied to the load when it is set to the second mode, and determines that the size of the load exceeds the load amount reference value, the control unit determines the output voltage of the converter. It is possible to generate a control signal lower than the operating voltage of the battery.

According to an embodiment of the present invention, when the remaining capacity of the battery reaches the preset lower limit, the output voltage of the converter is operating in the battery even if the size of the load exceeds the load amount reference value. It is possible to generate a control signal to have a value higher than the voltage.

According to the above-described uninterruptible power supply device, it is possible to achieve the effect that the uninterruptible power supply device can be controlled to operate within the maximum efficiency range even when the load amount changes in a short time.

1 is a functional block diagram illustrating an uninterruptible power supply device according to an embodiment of the present invention.
2 is a flowchart illustrating a method of controlling an uninterruptible power supply when operating in a first mode according to an embodiment of the present invention.
3 is a flowchart illustrating a method of controlling an uninterruptible power supply according to another embodiment of the present invention.
4 is a graph for explaining a power supply trend of a commercial power supply and a power supply trend of a battery according to a load amount when the uninterruptible power supply device operates in a second mode according to an embodiment of the present invention.
5 is a graph for explaining a power supply trend of commercial power and a power supply trend of a battery according to another embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Advantages and features of the present invention, and a method of achieving them will become apparent with reference to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments to be posted below, but may be implemented in various different forms, and only these embodiments make the posting of the present invention complete, and common knowledge in the technical field to which the present invention pertains. It is provided to completely inform the scope of the invention to those who have, and the invention is only defined by the scope of the claims. The same reference numerals refer to the same elements throughout the specification.

Unless otherwise defined, all terms (including technical and scientific terms) used in the present specification may be used with meanings that can be commonly understood by those of ordinary skill in the art to which the present invention belongs. In addition, terms defined in a commonly used dictionary are not interpreted ideally or excessively unless explicitly defined specifically.

In addition, in the present specification, the singular form may also be included in the plural form unless specifically stated in the phrase. As used herein, "comprises" and/or "comprising" refers to the presence of one or more other components, steps, actions and/or elements in which the recited component, step, operation and/or element is Or does not preclude additions.

1 is a functional block diagram illustrating an uninterruptible power supply device according to an embodiment of the present invention.

The uninterruptible power supply according to an embodiment of the present invention includes a converter 110, an inverter 130, a battery 150, and a converter control unit 170. In FIG. 1, only components related to the present invention are shown, and those of ordinary skill in the art to which the present invention pertains can see that other general-purpose components may be further included in addition to the components illustrated in FIG. 1. have.

The converter 110 converts AC power input from the commercial power supply 200 into DC power and supplies load power to the inverter 130 or supplies power to the battery 150.

The output terminal of the converter 110 is connected to the battery 150 through a DC-Link terminal. Accordingly, when the output voltage of the converter 110 is artificially lowered through PWM control and the output voltage of the converter 110 is lower than the operating voltage of the battery 150, the battery 150 is discharged and power is supplied to the load terminal.

*Therefore, in the control method of the uninterruptible power supply 100 according to an embodiment of the present invention, the output voltage of the converter 110 is controlled to supply only the power supplied from the commercial power to the load 300 or the battery 150 The power stored in) can be controlled to be supplied to the load 300.

The inverter 130 converts DC power into stable AC power and supplies it to the load 300. Specifically, the inverter 130 supplies the power of the commercial power supply 110 converted to DC power through the converter 110 to the load 300, or converts the power supplied by the battery 150 to AC power to load the load. Supply to (300).

The battery 150 is connected to the DC bus of the converter 110 and the inverter 130 and supplies stored power to the load 300 when an abnormality occurs in the commercial power supply 200.

The controller 170 controls the overall operation of the uninterruptible power supply 100.

The controller 170 controls the converter 130 so that only power supplied from the commercial power supply is supplied to the load 300, or discharges the battery 150 to supply the power stored in the battery 150 to the load 300 You can do it.

Specifically, when the uninterruptible power supply 100 is set to the first mode, the control unit 170 according to an embodiment of the present invention is, regardless of the load amount, until the remaining amount of the battery reaches a preset lower limit value at a preset time period. A control signal for supplying power to a load is generated by discharging the battery.

To this end, the controller 170 may generate a control signal for setting the output voltage of the converter 110 to a value lower than the battery operating voltage. In the first mode, when the remaining capacity of the battery reaches a preset lower limit, the controller 170 generates a control signal that sets the output voltage of the converter 110 to be equal to or higher than the battery operating voltage, stops discharging the battery, and uses a commercial power supply. Charge 150.

In another embodiment, when the uninterruptible power supply 100 is set to the second mode,

When the load exceeds a preset reference value, the controller 170 limits the input current input from the commercial power supply 200 and discharges the battery 150 to generate a control signal for supplying power to the load 300.

When the amount of current input from the commercial power source increases as the load amount increases, the uninterruptible power supply device 100 operates outside the maximum efficiency range. Accordingly, when the load is increased, the amount of current input from the commercial power is limited to operate within the maximum efficiency range, but the battery 150 supplies insufficient power.

According to the above-described uninterruptible power supply 100, even when the load amount changes in a short time, it is possible to achieve an effect that the uninterruptible power supply 100 can be controlled to operate within the maximum efficiency range.

Hereinafter, a method of controlling the uninterruptible power supply in each mode will be described in detail.

2 is a flowchart illustrating a method of controlling an uninterruptible power supply when operating in a first mode according to an embodiment of the present invention.

The control unit 170 first receives a first mode operation time and a lower limit value of the remaining battery capacity (S210). The first mode operation time and the lower limit of the remaining battery capacity may be received by a user through a user interface provided in the uninterruptible power supply 100 or through RS-485 serial communication. .

Meanwhile, the "first mode operation time" refers to a time set to supply the power stored in the battery 150 to the load 300. For example, depending on the characteristics of the load, there may be a case where the amount of load increases rapidly in a specific time period. Accordingly, when the first mode operation time is set to a time period in which the load amount increases rapidly, the battery 150 as well as the commercial power supply 200 supplies power to the load during that time period.

In addition, the "battery remaining capacity lower limit" means the minimum remaining capacity of the battery 150 required to stably perform the inherent function of the uninterruptible power supply.

If the power stored in the battery 150 is used without limitation during the "first mode operation time" when the load increases rapidly, the unique function of the uninterruptible power supply 100 cannot be executed when an abnormality occurs in the commercial power supply 200. Cases can arise.

Accordingly, the power stored in the battery 150 is used during the "first mode operation time" when the load increases rapidly, but the minimum amount of battery for performing the operation as the uninterruptible power supply 100 must be set. This is the "lower limit of the remaining battery capacity".

After receiving the above-described setting values, it is determined whether the current time has entered the first mode operation time set by the user (S220). When the first mode operation time has not been entered, the operation is performed in the normal mode (S250). Here, the general mode refers to a mode operated by the conventional uninterruptible power supply 100.

When entering the first mode operation time, the control unit 170 generates a control signal that lowers the output voltage of the converter 110 than the operation of the battery 150 (S230). As described above, the output terminal of the converter 110 is connected to the battery 150 through a DC-Link. When the output voltage of the converter 110 is lower than the operation of the battery 150, the battery 150 is discharged. And supply power to the load 300.

When the battery 150 starts to supply power to the load 300, the controller 170 determines whether the remaining capacity of the battery has reached a preset lower limit of the remaining battery capacity (S240).

As a result of the determination, when the remaining capacity of the battery 150 exceeds a preset lower limit of the remaining battery capacity, the battery 150 continues to supply power to the load 300. That is, the control unit 170 maintains the output voltage of the converter 110 to be lower than the operating voltage of the battery 150.

When the remaining capacity of the battery 150 reaches a preset lower limit of the remaining battery capacity, the control unit 170 generates a control signal that causes the output voltage of the converter 110 to have a higher value than the operating voltage of the battery 150. . That is, the uninterruptible power supply 100 is controlled to switch from the first mode to the normal mode.

According to the above-described control method of the uninterruptible power supply 100, by using the power stored in the battery 150 during a time when the load increases rapidly, the uninterruptible power supply 100 operates outside the maximum efficiency range as the load increases rapidly. The effect of being able to be prevented from doing can be achieved.

3 is a flowchart illustrating a method of controlling an uninterruptible power supply according to another embodiment of the present invention.

When the operation mode of the uninterruptible power supply 200 is set to the second mode, the load amount reference value and the battery remaining capacity lower limit value are received (S310).

Here, the "load amount reference value" means the size of the load 300 through which the battery 150 supplies power as the size of the load 300 increases. The "battery remaining capacity lower limit" is the same as described in FIG. 2. In addition, since the method of receiving the above-described setting values is also the same as that described in FIG. 2, redundant descriptions will be omitted.

Thereafter, the control unit 170 determines whether the size of the load 300 exceeds the above-described reference value (S320). When the size of the load 300 is determined, the size of the current supplied to the load 300 is determined, and the controller 170 senses the current supplied to the load 300 so that the size of the load 300 exceeds the reference value. You can judge whether or not.

When the load exceeds the reference value, a control signal for limiting the amount of current input from the commercial power supply 200 is generated (S330). When the size of the load 300 increases and the size of the current input to the load 300 increases, the size of the current input from the commercial power supply 200 increases to cope with this.

For the above reasons, when the current input from the commercial power supply 200 increases, the uninterruptible power supply 100 operates outside the maximum efficiency range. Accordingly, the control unit 170 according to an embodiment of the present invention controls the current input from the commercial power source 200 to not increase when the amount of current to be supplied to the load 300 increases due to an increase in the amount of load. Current is controlled to be supplied from the battery 150.

The control unit 170 generates a control signal that lowers the output voltage of the converter 100 than the operating voltage of the battery 150 so that the battery 150 supplies current to the load 300 (S340).

As described above, when the current to be supplied to the load 300 increases, the amount of current input from the commercial power supply 200 is limited and the insufficient amount is limited to the battery 150 to supply the uninterruptible power supply 100 ) Can be controlled to operate within the maximum efficiency range.

As the battery 150 supplies current to the load 300, the remaining capacity of the battery decreases and reaches the lower limit of the remaining battery capacity (S350). A control signal is generated so that the output voltage of 110 has a value higher than the operating voltage of the battery 150.

That is, the operation mode of the uninterruptible power supply 100 is switched to the normal mode (S360). As described above, the normal mode refers to a mode operated by the conventional uninterruptible power supply 100.

4 is a graph for explaining a power supply trend of a commercial power supply and a power supply trend of a battery according to a load amount when the uninterruptible power supply device operates in a second mode according to an embodiment of the present invention.

The graph shown in FIG. 4 is for simplifying and visually explaining the transition of power supplied by the commercial power supply and the battery according to the size of the load, and does not reflect the actual operating characteristics of the commercial power supply and the battery.

In the 0≤t<t ₁ section, as the size of the load 300 increases, the size of the power supplied by the commercial power supply 200 also increases. However, since the size of the load in the corresponding section _{does not exceed the reference value (R th} ), even if all the power input from the commercial power supply 200 is supplied to the load 300, the uninterruptible power supply 100 is within the maximum efficiency range. Will work in

In the _{section t 1} ≤ t <t ₂ , the load 300 is in _{a state in which the reference value R th} has been exceeded. At this time, if the commercial power supply 200 supplies power required by the load, the uninterruptible power supply 100 operates outside the maximum efficiency range.

Accordingly, the controller 170 generates a signal that controls the magnitude of the current input from the commercial power supply 200, and makes the output voltage of the converter 110 less than the operating voltage of the battery 150 so that the battery 150 supplies insufficient power. It generates a lowering control signal.

In the t≥t ₂ section, when the size of the load 300 becomes _{less than or equal to the reference value R th} , the uninterruptible power supply 100 is at maximum efficiency even if the current supplied by the commercial power supply 200 is transferred to the load 300 as it is. Since it is possible to operate within the range, the control unit 150 generates a control signal that maintains the output voltage of the converter 110 higher than the operating voltage of the battery 150 to prevent power supply from the battery 150 to the load 300. Stop.

On the other hand, in the above-described embodiment, a case where the size of the load 300 is _{less than or equal to the reference value R th} and the battery 150 no longer supplies power to the load 300 has been described as an example, but the battery 150 There may be a case in which power supply from the battery 150 to the load 300 is stopped depending on the remaining capacity of.

5 is a graph for explaining a power supply trend of commercial power and a power supply trend of a battery according to another embodiment of the present invention.

As in FIG. 4, the graph shown in FIG. 5 is for simplifying and visually explaining the transition of the power supplied by the commercial power source and the battery according to the size of the load, and does not reflect the actual operating characteristics of the commercial power source and the battery.

In the 0≤t<t ₃ section, as the size of the load 300 increases, the size of the power supplied by the commercial power supply 200 also increases. However, since the size of the load in the corresponding section _{does not exceed the reference value (R th} ), even if all the power input from the commercial power supply 200 is supplied to the load 300, the uninterruptible power supply 100 is within the maximum efficiency range. Will work in

That is, since the battery 150 does not supply power to the load 300, the remaining capacity of the battery also maintains a constant value.

In the _{section t 3} ≤ t <t ₄ , the load 300 is in _{a state in which the reference value R th} has been exceeded. At this time, if the commercial power supply 200 supplies power required by the load, the uninterruptible power supply 100 operates outside the maximum efficiency range.

Accordingly, the controller 170 generates a signal that controls the magnitude of the current input from the commercial power supply 200, and makes the output voltage of the converter 110 less than the operating voltage of the battery 150 so that the battery 150 supplies insufficient power. It generates a lowering control signal. Accordingly, the remaining capacity of the battery 150 also decreases with the passage of time.

In the t≥t ₄ section, the size of the load 300 still exceeds the _{reference value R th.} However, since the remaining capacity of the battery 150 has reached a preset lower limit value, if the power supply from the battery 150 to the load 300 is maintained as it is, the uninterruptible power supply 100 cannot perform its original function. .

Therefore, even if the size of the load 300 _{exceeds the reference value R th} , the controller 170 determines the level of the output voltage of the converter 110 when the remaining capacity of the battery 150 reaches a preset lower limit value. 150) Power supply from the battery 150 to the load 300 is stopped by generating a control signal higher than the operating voltage.

Accordingly, in the period t≥t ₄ , the controller 170 does not limit the amount of current input from the commercial power supply 200 even if the uninterruptible power supply 100 operates outside the maximum efficiency range.

The load 300 supplies stable power even if an abnormality occurs in the commercial power supply 200 by maintaining the remaining capacity of the battery 150 larger than the lower limit value than the uninterruptible power supply 100 operating within the maximum efficiency range. Because it is more important.

Meanwhile, the above-described method can be written as a program that can be executed on a computer, and can be implemented in a general-purpose digital computer that operates the program using a computer-readable recording medium. In addition, the structure of the data used in the above-described method can be recorded on a computer-readable recording medium through various means. The computer-readable recording medium includes a storage medium such as a magnetic storage medium (eg, ROM, floppy disk, hard disk, etc.), and an optical reading medium (eg, CD-ROM, DVD, etc.).

Those of ordinary skill in the technical field related to the present embodiment will appreciate that it may be implemented in a modified form without departing from the essential characteristics of the above-described description. Therefore, the disclosed methods should be considered from an explanatory point of view rather than a limiting point of view. The scope of the present invention is shown in the claims rather than the above description, and all differences within the scope equivalent thereto should be construed as being included in the present invention.

Claims (5)

A converter that converts AC power input from a commercial power source into DC power;
An inverter converting DC power into AC power and supplying it to a load;
battery; And
In the first mode, the output voltage of the converter is lowered than the voltage of the battery to discharge the battery until the remaining amount of the battery reaches a preset lower limit value regardless of the load amount in a preset time period, so that the commercial power supply and the battery load the load. Generates a control signal that supplies power to the
In the second mode, if the load exceeds a preset reference value, the commercial power supply is operated within the maximum efficiency range by limiting the input current input from the commercial power so that the commercial power does not supply all necessary power from the load. As the input current is limited, the output voltage of the converter is operated by the battery until the remaining capacity of the battery reaches a preset lower limit value so that the commercial power supply insufficient power to supply the power consumed by the load from the battery. Including a control unit for generating a control signal lower than the voltage,
The control unit,
An uninterruptible power supply for receiving a first mode operation time and a lower limit value of the remaining battery capacity when the first mode is set, and generating a control signal for lowering an output voltage of the converter than the battery voltage when the first mode operation time is reached. delete The method of claim 1,
The control unit,
When the remaining capacity of the battery reaches the preset lower limit value, the uninterruptible power supply device generates a control signal such that the output voltage of the converter has a value higher than the operating voltage of the battery. The method of claim 1,
The control unit,
When set to the second mode, when it is determined that the size of the load exceeds the reference value of the load by sensing the current supplied to the load, the uninterruptible power supply generates a control signal that lowers the output voltage of the converter than the operating voltage of the battery Feeding device. The method of claim 4,
The control unit,
When the remaining capacity of the battery reaches the preset lower limit value, generating a control signal such that the output voltage of the converter has a value higher than the operating voltage of the battery even when the size of the load exceeds the load amount reference value. Uninterruptible power supply.

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