KR101609245B1 - Apparatus for storing energy - Google Patents

Abstract

One embodiment of the invention relates to an energy storage device. A step-up type converter that boosts a voltage of energy received from a power source and outputs the voltage to a DC link capacitor stage; A charging switch for storing the energy received from the power source in the battery; A bidirectional switch for outputting energy stored in the battery to a power system; And a common switch / low frequency filter connected between the charge switch and the battery to reduce the energy stored in the battery and connected between the bidirectional switch and the battery to boost the energy discharged from the battery. And an energy storage device. Accordingly, the battery charging efficiency can be improved by passing a single step-down converter to store the energy supplied from the power source in the battery.

Description

[0001] APPARATUS FOR STORING ENERGY [0002]

The present invention relates to an energy storage device.

In recent years, there has been an increasing tendency to add an ESS (Energy Storage System) to a PCS (Power Conditioning System) in order to provide stable load power to the AC system in preparation for power failure. (Hereinafter referred to as an energy storage device including the PCS and the ESS).

Generally, the energy storage device has a first function of outputting energy supplied from a power source to a power system, a second function of outputting energy stored in the battery to a power system, and a third function of storing energy supplied from the power source into a battery Can be performed.

Here, the energy stored in the energy storage device to perform the first function is boosted through a boost converter, and the energy stored to perform the second function is boosted by a bi-directional converter (Buck-boost converter) And is boosted. The energy input to perform the third function is reduced through both the step-up converter and the bidirectional converter.

In each converter, losses are caused by resistance component and pulse width modulation (PWM) switching, and the more the converter stages are touched, the worse it becomes.

That is, there is a problem in that energy efficiency is deteriorated due to the energy storage device performing the third function several times over the converter stage.

Japanese Patent Application Laid-Open No. 10-2014-0097628

In order to solve the above problems, an embodiment of the present invention provides an energy storage device for passing a single step-down converter in order to store energy supplied from a power supply in a battery.

An energy storage device according to an embodiment of the present invention includes: a DC link capacitor stage; A step-up type converter for boosting a voltage of energy received from a power source and outputting the voltage to the DC link capacitor stage; A bidirectional switch for outputting energy stored in the battery to the DC link capacitor stage and storing energy stored in the DC link capacitor stage in the battery; A charging switch for receiving energy from the power source and storing the energy in the battery; And a common switch for reducing the energy stored in the battery from the bidirectional switch and / or the charging switch and for boosting the energy discharged from the battery to the bidirectional switch and / or the charging switch; . ≪ / RTI >

The bidirectional switch includes a first switch, the common switch includes a second switch, the charge switch includes a third switch, and the bidirectional switch and the common switch are respectively connected to a first switch and a second switch, The common switch / low-frequency filter and the charge switch control ON / OFF of the second switch and the third switch to control the voltage of the energized energy by controlling on / off of the second switch and the third switch, respectively, .

The boost converter further includes an inverter for converting a voltage of energy output from the step-up type converter from a direct current to an alternating current. The step-up type converter receives energy from a solar cell and calculates a maximum power point tracking )can do.

The bidirectional switch and the common switch may reduce the energy of the DC link capacitor stage and store the energy in the battery, boost the energy stored in the battery, and output it to the DC link capacitor stage.

In addition, the charging switch includes a diode connected in a direction to prevent energy from flowing from the battery to the power source. The charging switch receives energy from a solar cell and calculates a maximum power point tracking )can do.

The energy storage device according to an embodiment of the present invention includes: a boost converter that boosts a voltage of energy received from a solar cell and outputs the boosted voltage to a DC link capacitor stage; A bidirectional converter that steps down the voltage of the DC link capacitor energy and stores the voltage in the battery, boosts the voltage of the energy stored in the battery, and outputs the voltage to the DC link capacitor stage; A step-down type converter for reducing the voltage of the energy received from the solar cell and storing the reduced voltage in the battery; . ≪ / RTI >

Further, the bidirectional converter includes a first switch and a second switch, the step-down type converter includes a second switch and a third switch, and the bidirectional converter controls ON / OFF of the first switch and the second switch And the step-down type converter can control on / off of the second switch and the third switch to reduce the voltage of the energy to be conducted.

In addition, the step-down type converter may include a diode connected in a direction to prevent energy from flowing from the battery to the solar cell.

By passing a single step-down converter in order to store the energy supplied from the power source in the battery, the charging efficiency of the battery can be improved.

1 is a block diagram showing an energy storage device and an energy storage system according to an embodiment of the present invention.
2 is a block diagram illustrating an operation and a bi-directional converter in which an energy storage device outputs energy according to an embodiment of the present invention.
3 is a block diagram illustrating an operation and a step-down converter in which an energy storage device stores energy according to an embodiment of the present invention.
4 is a circuit diagram showing an energy storage device according to an embodiment of the present invention.

It is noted that the technical terms used herein are used only to describe specific embodiments and are not intended to limit the invention. It is also to be understood that the technical terms used herein are to be interpreted in a sense generally understood by a person skilled in the art to which the present invention belongs, Should not be construed to mean, or be interpreted in an excessively reduced sense. Further, when a technical term used herein is an erroneous technical term that does not accurately express the spirit of the present invention, it should be understood that technical terms that can be understood by a person skilled in the art are replaced. In addition, the general terms used in the present invention should be interpreted according to a predefined or prior context, and should not be construed as being excessively reduced.

Also, the singular forms "as used herein include plural referents unless the context clearly dictates otherwise. In this application, the term "comprising" should not be construed as necessarily including the various elements or steps described in the specification, and some of the elements or portions thereof may not be included, Or < / RTI > additional elements or steps.

Further, the suffix "part" for a component used in the present specification is given or mixed in consideration of ease of specification, and does not have a meaning or role that is different from itself.

Furthermore, terms including ordinals such as first, second, etc. used in this specification can be used to describe various elements, but the elements should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, wherein like reference numerals refer to like or similar elements throughout the several views, and redundant description thereof will be omitted.

In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. It is to be noted that the accompanying drawings are only for the purpose of facilitating understanding of the present invention, and should not be construed as limiting the scope of the present invention with reference to the accompanying drawings.

1 is a block diagram showing an energy storage device and an energy storage system according to an embodiment of the present invention.

Referring to FIG. 1, an energy storage system may include an energy storage device 100, a power source 200, a battery 300, an inverter 400, and a power system 500.

The energy storage device 100 may also include a boost converter 110, a bidirectional switch 120, a common switch / low frequency filter 130, a charge switch 140 and a DC link capacitor stage 150.

The energy storage system will now be described with reference to FIG.

The energy storage device 100 outputs the energy supplied from the power source 200 to the power system 500 and outputs the energy stored in the battery 300 to the power system 500, Energy can be stored in the battery 300.

The power source 200 can convert energy other than the external electricity into electric energy. Here, energy other than electricity may include renewable energy. For example, the power source 200 may include a solar cell, and may convert light energy into electrical energy and output the electrical energy to the energy storage device 100.

The battery 300 may store the energy received from the power source 200 or the power system 500.

The inverter 400 may convert the voltage of the energy output from the energy storage device 100 from DC to AC. Here, the inverter 400 may include a single-phase inverter composed of four switches and a three-phase inverter composed of six switches.

In addition, the inverter 400 may be included in the energy storage device 100.

The power system 500 includes a system in which a power plant, a transmission and transmission facility, a distribution facility, and other auxiliary facilities are organically combined. The power system 500 may receive energy from the power source 200 or the battery 300, and may store energy with the battery.

Generally, the voltage range of the power supply 200 may be higher than the battery 300 and lower than the DC link capacitor stage 150. Therefore, when the energy converted by the power source 200 is transmitted to the battery 300, it is necessary to step up the voltage when the voltage is lowered and is sent to the power system 500 via the DC link capacitor stage 150.

Hereinafter, the energy storage device 100 will be described in detail with reference to FIG.

The step-up type converter 110 can increase the voltage of the energy received from the power supply 200 and output it to the DC link capacitor stage 150. Where the DC link capacitor stage 150 may be between the boost converter and the inverter. The step-up converter 110 serves to boost the output from the power source 200 to the DC link capacitor stage 150 and the inverter 400 supplies the energy stored in the DC link capacitor stage 150 to the power system 500 ). The energy type stored in the DC link capacitor stage 150 is a DC component, and the inverter can convert this DC power supply to AC power for the system.

Here, the boost converter may include an inductor, a diode, and a switch for power. Ideally, a step-up converter can increase the voltage without loss of power. However, an actual step-up converter has a loss of energy due to each resistance component of the circuit and pulse width modulation (PWM) switching.

In addition, the step-up type converter 110 can receive energy from a solar cell and perform maximum power point tracking. Accordingly, the solar cell can generate maximum output power, and at the same time, can increase the voltage of the output energy.

The bi-directional switch 120 may output the energy stored in the battery 300 to the DC link capacitor stage 150. Here, the bi-directional switch 120 is reversible since bi-directional refers to the direction from the battery 300 to the DC link capacitor stage 150 and vice versa. That is, when the switch of the bidirectional switch 120 is operated, the energy received from the DC link capacitor stage 150 may be stored in the battery 300. In this case, the energy input from the DC link capacitor stage 150 can be reduced and stored in the battery 300. The voltage down-converting process can be implemented by a buck-boost converter, which will be described later with reference to FIGS. 2 and 4. FIG.

The common switch / low frequency filter 130 is connected between the charging switch 140 and the battery 300 so as to reduce the energy stored in the battery 300 and to supply the energy between the bidirectional switch 120 and the battery 300 So that the energy discharged from the battery 300 can be boosted to the DC link capacitor stage 150. Here, the common switch / low frequency filter 130 can perform both functions of a switch and a filter. For example, the common switch / low-frequency filter 130 performs the function of a switch so as to not only output the energy stored in the battery 300 but also operate with the charging switch 140 to input energy from the power source 200 You can get it.

Further, by performing the function of the filter, the common switch / low-frequency filter 130 can filter the high-frequency noise included in the DC voltage and convert the rectangular wave into a constant voltage.

The boosting process of the voltage can be implemented by a buck-boost converter, which will be described later with reference to FIG. 2 and FIG.

The charging switch 140 can receive energy from the power source 200 and output it to the battery 300. [ The charging switch 140 can cooperate with the common switch / low frequency filter 130 to reduce the voltage of the energy received from the power source 200. The voltage lowering process will be described later with reference to FIG. 3 and FIG.

Also, the charging switch 140 may receive energy from a solar cell and perform maximum power point tracking. Accordingly, the solar cell can generate maximum output power, and at the same time, can lower the voltage of the output energy. The step-down of the voltage can be realized by a buck converter, which will be described later with reference to FIGS. 3 and 4. FIG.

2 is a block diagram illustrating an operation and a bi-directional converter in which an energy storage device outputs energy according to an embodiment of the present invention.

Referring to FIG. 2, the bidirectional switch 120 and the common switch / low-pass filter 130 may operate as a buck-boost converter in cooperation with each other.

The operation in which the energy storage device 100 outputs energy can be divided into two types. The first operation is the operation of accepting a voltage from the power source 200 to the DC link capacitor stage 150 and then outputting energy to the power system 500 via the inverter. The second operation is the operation of boosting the voltage from the battery 300 to the DC link capacitor stage 150 and then outputting energy to the power system 500 via the inverter. Additionally, the energy storage device 100 may perform a third operation in which power is input from the power system 500 via the inverter, DC link capacitor stage 150, to the battery 300 while reducing the voltage.

A buck-boost converter including the bidirectional switch 120 and the common switch / low-pass filter 130 can increase or decrease the voltage in association with the second operation and the third operation. Specifically, when the bidirectional converter performs a third operation to charge energy from the DC link capacitor stage 150 to the battery 300, it can operate as a buck converter. On the other hand, when the bidirectional converter performs the second operation of discharging energy from the battery 300 to the DC link capacitor stage 150, it can operate as a boost converter.

On the other hand, when the energy storage device 100 performs an operation of outputting energy, the bidirectional switch 120 conducts the energy while performing the PWM operation (on / off), and the charging switch 140 stops the operation Off) energy can be cut off.

3 is a block diagram illustrating an operation and a step-down converter in which an energy storage device stores energy according to an embodiment of the present invention.

Referring to FIG. 3, the common switch / low frequency filter 130 and the charge switch 140 may operate as a buck converter by interlocking with each other.

The operation of storing energy by the energy storage device 100 can be classified into two types. The first operation is to increase the voltage at the power supply 200 by way of the boost converter 110 to the DC link capacitor stage 150 and to boost the boosted energy of the DC link capacitor stage 150 via the bi- And the voltage is decreased. The second operation is an operation for reducing the voltage while transmitting energy to the step-down type converter including the charge switch 140 in the power source 200. [

In order to perform the first operation, the bidirectional switch 120 and the common switch / low frequency filter 130 complementarily conduct the PWM switch operation (turn on / off repetition) and energize the charge switch 140, (Continuously off) to cut off the conduction of energy. Since the first operation is caused by the resistance component and the pulse width modulation (PWM) switching in both the step-up converter 110 and the bidirectional converter, the energy loss may be large.

In order to perform the second operation, the bidirectional switch 120 stops operation (keeps off) and cuts off the conduction of energy, and the common switch / low frequency filter 130 and the charge switch 140 complementarily perform the PWM switch operation (The charging switch is turned off when the common switch is turned on, and the charging switch is turned on when the common switch is turned off). That is, by passing a single step-down converter in order to store the energy supplied from the power source into the battery, the efficiency of charging the battery can be improved.

4 is a circuit diagram showing an energy storage device according to an embodiment of the present invention.

Referring to FIG. 4, the bi-directional switch 120 included in the energy storage device 100 may include a first switch 121.

The common switch / low frequency filter 130 included in the energy storage device 100 may include a second switch 131, an inductor 132, and a capacitor 133.

The charging switch 140 included in the energy storage device 100 may also include a third switch 141 and a diode 142. [

The bidirectional switch 120 and the common switch / low frequency filter 130 may include a first switch 121, a second switch 131 and an inductor 132 as bidirectional synchronous buck / have.

That is, the bidirectional switch 120 and the common switch / low-frequency filter 130 control ON / OFF of the first switch 121 and the second switch 131 to increase or decrease the voltage of the energized conduction, respectively .

Specifically, the intermediate voltage between the bidirectional switch 120 and the common switch / low frequency filter 130 will be described. When the first switch 121 is turned on and the second switch 131 is turned off, the magnitude of the intermediate voltage is equal to the magnitude of the input voltage. In the second state in which the first switch 121 is turned off and the second switch 131 is turned on, the magnitude of the intermediate voltage is zero. The on / off control of the first switch 121 and the second switch 131 may mean repetition of the first state and the second state.

By repeating the first state and the second state, the intermediate voltage can be in the form of a square wave. At this time, the inductor 132 and the capacitor 133 included in the common switch / low frequency filter 130 can filter high frequency components included in the intermediate voltage. Thus, the intermediate voltage may be converted to a form of a smoothed voltage while passing through the common switch / low-pass filter 130. [

Here, the magnitude of the smoothed voltage is an average voltage of the square wave. Thus, the magnitude of the smoothed voltage is a product of the voltage of the first state of the square wave and the duty ratio of the square wave. If the duty ratio is not 100%, the magnitude of the smoothed voltage is smaller than the voltage of the first state of the square wave. That is, the voltage of the energy input through the bidirectional switch 120 can be reduced and output as a smoothed voltage through the common switch / low-frequency filter 130.

When the bidirectional converter reverses the above-described voltage down-converting process, the voltage can be boosted. Accordingly, the voltage of the energy input through the common switch / low-frequency filter 130 is stepped up to output the energy boosted through the bidirectional switch 120.

The common switch / low frequency filter 130 and the charging switch 140 may include a second switch 131, a third switch 141 and an inductor 132 as a step-down type converter. Here, the second switch 131 and the inductor 132 can commonly use elements in the bidirectional converter.

The common switch / low-frequency filter 130 and the charge switch 140 can control on / off of the second switch 131 and the third switch 141, respectively, to reduce the voltage of the energy to be conducted. The voltage step-down process is substantially the same as the step-down process of the bidirectional converter.

However, the step-down type converter can not reverse the above-described voltage step-down process. The charging switch 140 may include a diode 142 connected in a direction to prevent energy from flowing from the battery 300 to the power source 200. For example, the power source 200 performs a power generation function of converting energy other than electricity into electric energy, but may not perform a function of converting electric energy into energy other than electricity.

Here, at least three problems may occur when energy flows from the battery 300 to the power source 200 through the charging switch 140. [ First, the power source 200 may be damaged. Secondly, when energy is output from the battery 300 to the power system 500, energy may leak. Third, performance of the maximum output point operation (MPPT) in the charge switch 140 may be hindered. That is, the charging switch 140 includes the diode 142 connected in a direction to prevent energy from flowing from the battery 300 to the power source 200, thereby solving the above three problems.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Therefore, the spirit of the present invention should not be construed as being limited to the above-described embodiments, and all of the equivalents or equivalents of the claims, as well as the following claims, I will say.

100: Energy storage device 110: Boost converter
120: bi-directional switch 121: first switch
130: common switch / low frequency filter 131: second switch
132: Inductor 133: Capacitor
140: charge switch 141: third switch
142: diode 150: DC link capacitor stage
200: Power source 300: Battery
400: inverter 500: power system

Claims (8)

DC link capacitor stage;
A step-up type converter for boosting a voltage of energy received from a power source and outputting the voltage to the DC link capacitor stage;
A bidirectional switch for outputting energy stored in the battery to the DC link capacitor stage and storing energy stored in the DC link capacitor stage in the battery;
A charging switch for receiving energy from the power source and storing the energy in the battery; And
A common switch for reducing the energy stored in the battery from the bidirectional switch and / or the charging switch and for boosting the energy discharged from the battery to the bidirectional switch and / or the charging switch; Lt; / RTI >
Wherein the charge switch performs a pulse width modulation (PWM) switching operation complementarily with the common switch to determine a step-down voltage according to a maximum power point tracking (MPPT).
The method according to claim 1,
Wherein the bi-directional switch includes a first switch,
Wherein the common switch includes a second switch,
Wherein the charge switch includes a third switch,
Wherein the bidirectional switch and the common switch control on / off of the first switch and the second switch, respectively, to step up or step down the voltage of the energized conduction,
Wherein the common switch and the charge switch control ON / OFF of the second switch and the third switch, respectively, to reduce the voltage of the conductive energy.
The method according to claim 1,
Further comprising an inverter for converting a voltage of energy output from the DC link capacitor stage from a direct current to an alternating current and outputting the voltage to a power system and converting a voltage of energy input from the power system from alternating current to direct current.
delete The method according to claim 1,
Wherein the charging switch comprises a diode connected in a direction to prevent energy from flowing from the battery to the power source.
delete delete delete

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