KR20210093687A - Power control circuit of renewable energy source, and control method using thereof - Google Patents

Abstract

The present invention relates to a power control circuit for a renewable energy source to accurately measure and control the voltage and current of a battery and a power control method using the same. According to one embodiment of the present invention, a control circuit operating in a buck-boost mode comprises: an input terminal to which a renewable energy source is connected; a second output terminal connecting one side to a first current sensor for detecting an output current and connecting the other side to a battery and an external load; a second output terminal connected to the external load; a first sensing terminal connecting one side to a second current sensor for detecting a charge/discharge current of the battery and connecting the other side to the battery; and a second sensing terminal connecting one side to a second current sensor.

Description

Power control circuit of renewable energy source and power control method using the same {POWER CONTROL CIRCUIT OF RENEWABLE ENERGY SOURCE, AND CONTROL METHOD USING THEREOF}

The present invention relates to a power control circuit and method of a renewable energy source, and more particularly, when supplying power in parallel from various renewable energy sources such as solar light and piezoelectric module, the charging of the battery, including the battery And it relates to a technology for controlling the power according to the discharge state.

Recently, the use of renewable energy has been greatly increased, and a system that receives power from various new and renewable energy sources is being applied. In the case of photovoltaic (PV), it has the advantage of being able to easily generate power from sunlight, but since it cannot supply power when there is no or weak sunlight, most renewable power generation uses batteries in the middle. The energy storage system (ESS) utilized is being used to increase the efficiency of power supply.

When a new and renewable energy source is connected from a single entity, the power control device can measure the current and voltage, so it is possible to control the charging and discharging in consideration of the state of the battery by determining the battery charging voltage and charging current. When batteries are connected in parallel from a renewable energy source, it is difficult to control in parallel because the respective charging and discharging currents flow in each circuit, and the voltage and current of the battery must be controlled through communication or a separate measuring circuit. There is this.

1 is a circuit diagram showing an example of a conventional solar-linked power control device. Referring to FIG. 1 , each power control device receives power from a renewable power source 20 that is sunlight. When the magnitude of the voltage input from the renewable power source is small, the output voltage is boosted through the booster power switch 105 , the inductor 103 , and the booster diode 104 in order to use the booster circuit. When the magnitude of the voltage input from the renewable power source is large, the output voltage is controlled through the buck-mode switch 102 in order to operate as a chopper circuit. For protection of the circuit, a filter 101 and an output diode 106 or an output inductor are applied to the circuit. The output terminal terminals 108A and 108B are connected to an external load, and the battery is connected to the battery connection terminal 115 . The current sensors 107A and 107B for detecting the current of each line are connected to an output terminal terminal and a battery connection terminal.

When only one circuit 100 on the left of FIG. 1 is connected to the battery and the load, the sum of the load current and the battery current is detected in the upper current sensor 107A, and the lower current sensor 107B of the battery connection terminal 115 is The charging and discharging current of the battery can be detected. That is, the current to be supplied from the power control device based on the current detected through the current sensors 107A and 107B may be controlled according to the state of the battery. At this time, the current detected by each sensor is as follows [Equation 1].

[Equation 1]

At this time, when there is only one circuit, since the detected current i _b1 of the battery connection terminal 115 is equal to the charging and discharging current of the battery by i _bat , there is no problem in controlling the charging and discharging of the battery. However, when two or more circuits are connected in parallel with the battery as shown in FIG. 1 , the current detected in each circuit is as follows according to the current path 127A.

[Equation 2]

Since currents detectable in each control circuit 100 are i _s1 and i _b1 , is ₂ and i _b2 , the total charging and discharging current i _bat of the battery cannot be measured in each control circuit 100 . Accordingly, in the conventional control circuit 100 as shown in FIG. 1 , there is a disadvantage in that a separate current measuring circuit must be added or each circuit 100 is connected by communication to combine the measured currents with each other.

Republic of Korea Patent Publication No. 10-2016-0142979 (2016.12.14)

The present invention is intended to solve the above problems, and when power is supplied in parallel from various renewable energy sources such as solar light and piezoelectric module, in parallel to control the charging and discharging voltage and current of the battery An object of the present invention is to provide a circuit and a control method capable of accurately measuring and controlling battery voltage and current in each connected power circuit.

In the power control circuit of a renewable energy source operating in a buck-boost mode according to an embodiment of the present invention, an input terminal to which the renewable energy source is connected, a first current sensor for detecting an output current is connected to one side, and , a first output terminal to which the battery and an external load are connected to the other side, a second output terminal to be connected to an external load, a second current sensor for detecting the charge/discharge current of the battery is connected to one side, and the battery is connected to the other side The first sensing terminal and one side may include a second sensing terminal to which the second current sensor is connected.

According to an embodiment of the present invention, when only one power control circuit is connected to the battery, the other end of the second sensing terminal may be connected to the second output terminal.

According to an embodiment of the present invention, when the plurality of power control circuits are connected in parallel with the battery, the second sensing terminal of the other circuit other than the battery is located on the other side of the first sensing terminal of one of the plurality of power control circuits. connected, and the other end of the second sensing terminal of one of the plurality of power control circuits may be connected with the second output terminal of the plurality of power control circuits.

Each of the plurality of power control circuits according to an embodiment of the present invention compares the size of the charging/discharging current of the battery measured by the second current sensor with the maximum charging current of the battery to determine the current and output currents flowing through the external load. The magnitudes of the output currents can be individually adjusted within a range where the sum coincides with the magnitude of the charge and discharge currents of the battery.

According to an embodiment of the present invention, when the input voltage from the renewable energy source is changed, each of the plurality of power control circuits compares the input voltage with the size of the charging/discharging voltage of the battery to buck-mode or boost-mode can operate as

In a power control method using a power control circuit of a renewable energy source operating in a buck-boost mode according to an embodiment of the present invention, each of a plurality of power control circuits connected in parallel with a battery is output through a first current sensor Detecting the current, each of the plurality of power control circuits detecting the charge/discharge current of the battery through the second current sensor, and each of the plurality of power control circuits by the maximum charging current of the battery and the second current sensor Comparing the measured size of the charging and discharging current of the battery and individually adjusting the size of the output currents within a range in which the sum of the current flowing through the external load and the output current matches the size of the charging and discharging current of the battery. there is.

In the power control method according to an embodiment of the present invention, when an input voltage from a renewable energy source is changed, each of a plurality of power control circuits compares the input voltage with the size of the charging/discharging voltage of the battery in the buck-mode or operating in a boost-mode.

According to the control circuit and method provided as an embodiment of the present invention, when power is supplied in parallel to a load through a battery in connection with a renewable energy source, the charge/discharge current of the battery is accurately detected in each control circuit By providing a current sensor arrangement and wiring method and a control method of the power control circuit, stable charging and discharging control of the battery can be performed directly in the power control circuit in the power control circuit connecting the battery.

1 is a circuit diagram showing an example of a conventional solar-linked power control device.
2 is a graph showing changes in voltage and power due to charge/discharge control of a battery connected to a renewable energy source.
3 is a circuit diagram of a power control circuit according to an embodiment of the present invention.
4 is a graph illustrating a buck-boost mode operation change of a power control circuit according to an embodiment of the present invention.
5 is a graph illustrating a verification result for parallel control of a power control circuit according to an embodiment of the present invention.
6 is a graph illustrating a verification result for a control mode change of a power control circuit according to an embodiment of the present invention.
7 is a flowchart of a power control method according to an embodiment of the present invention.

Terms used in this specification will be briefly described, and the present invention will be described in detail.

The terms used in the present invention have been selected as currently widely used general terms as possible while considering the functions in the present invention, which may vary depending on the intention or precedent of a person skilled in the art, the emergence of new technology, and the like. In addition, in specific cases, there are also terms arbitrarily selected by the applicant, and in this case, the meaning will be described in detail in the description of the corresponding invention. Therefore, the term used in the present invention should be defined based on the meaning of the term and the overall content of the present invention, rather than the name of a simple term.

When a part "includes" a certain component throughout the specification, this means that other components may be further included, rather than excluding other components, unless otherwise stated. Also, throughout the specification, when a part is "connected" with another part, this includes not only the case of being "directly connected" but also the case of being connected "with another configuration in between".

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art can easily carry out the present invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

2 is a graph showing changes in voltage and power due to charge/discharge control of a battery connected to a renewable energy source.

Looking at the battery terminal charging voltage 61 of FIG. 2 , the current control mode is used until the maximum battery charging voltage 55 is reached, and the state of charge (SOC) of the battery according to the current control mode is It is formed by the rising curve 52A. When the battery charging voltage 61 reaches the maximum battery voltage 55, the voltage control mode is changed from the time of arrival, the charging current decreases, and the charging current becomes 0 when charging is completed. Therefore, in order to control the charging and discharging of the battery, it is necessary to accurately control the charging voltage and the charging current of the battery. However, in the conventional circuit as shown in FIG. 1, for the above control, the sum of the currents of the two circuits is separately calculated, measured by a separate measurement circuit, or a method of calculating by communication has to be used.

3 is a circuit diagram of a power control circuit according to an embodiment of the present invention.

Referring to FIG. 3 , the arrangement structure of the basic elements constituting the power control circuit 110 according to an embodiment of the present invention has a structure capable of operating in the buck-boost mode as shown in FIG. 1 , but unlike FIG. 1 , the battery It includes new sensing terminals to which a current sensor for accurately detecting the charge/discharge current of 200 is connected, and has a structure different from that of FIG. 1 in the connection method of the terminals of the output terminal. For example, in the power control circuit 110, a first current sensor 117A for detecting an output current is connected to one side, and a battery 200 and an external load 220 are connected to a first output terminal ( 118A), the second output terminal 118B connected to the external load 220, a second current sensor 117B for detecting the charge/discharge current of the battery 200 is connected to one side, and the battery 200 is connected to the other side It may include a first sensing terminal 120A to which is connected, and a second sensing terminal 120B to which a second current sensor 117B is connected to one side thereof.

When only the single power control circuit 110 is connected to the battery 200 , the second sensing terminal 120B is connected to the second output terminal 118B serving as a ground of the power control circuit 110 . Thus, the single power control circuit _{can detect the battery charge/discharge current i bat} directly from the second current sensor 117B. That is, when only the piezoelectric element module located on the left side of FIG. 3 is connected to the battery 200 and the external load 220 through the power control circuit 110, only the output current passing through the first output terminal 118A Since it is used for charging and discharging of the battery 200 , the current i _bat detected by the second current sensor 117B becomes the charging/discharging current of the battery 200 .

When the plurality of power control circuits 110 are connected in parallel with the battery 200 , the other side of the first sensing terminal 120A of one of the plurality of power control circuits 110 is other than the battery 200 . The second sensing terminal 120B of the circuit is connected, and the other side of the second sensing terminal 120B of one of the plurality of power control circuits 110 is the second output terminal of the plurality of power control circuits 110 ( 118B). For example, when two power control circuits 110 connected to each of the piezoelectric element module and the solar module are connected in parallel with the battery 200 as shown in FIG. 3 , the first sensing of the piezoelectric element module side circuit 110 . The terminal 120A may be directly connected to the battery 200 , and the second sensing terminal 120B may be connected to the first sensing terminal 120A of the solar module side circuit 110 . In addition, the second sensing terminal 120B of the solar module side circuit 110 may be connected to the second output terminal 118B of the circuit 110 on both sides. At this time, the currents respectively detected along the current path in the two power control circuits 110 are shown in the following [Equation 3].

[Equation 3]

According to the above-described connection relationship, since both the piezoelectric element module side circuit 110 and the solar module side circuit 110 share the battery charge/discharge current, each power control circuit 110 is each second current sensor 117B. It is possible to directly detect the battery charge/discharge current i _bat of the same size. Therefore, unlike the conventional circuit 100 as shown in FIG. 1 , even if a separate measurement circuit is not built or an operation is performed through communication, the control circuit 110 according to an embodiment of the present invention is the second current sensor 117B. It is possible to individually _{detect the battery current i bat} through , and use it for charge/discharge control of the battery 200 and control of power supplied from a renewable energy source.

Referring to FIG. 2 , since the maximum charging current 51 according to the charging voltage 61 in the charging control of the battery 200 _{becomes the value of the battery charging and discharging current i bat} , each power control circuit 110 in FIG. 3 . The output currents i _s1 and i _s2 can be controlled in consideration of the size of the battery charge/discharge current i _{bat .} For example, when the size of the _{battery charging/discharging current i bat} is large compared to the maximum charging current determined by the capacity of the battery 200 _{, the output currents i s1} and i _s2 of each power control circuit 110 decrease can be controlled with _{Conversely, when the size of the battery charging and discharging current i bat} is small compared to the maximum charging current determined by the capacity of the battery 200 , the _{output currents i s1} and i _s2 of each power control circuit 110 are controlled in an increasing direction. can _{At this time, since the sum of the output currents i s1} and i _{s2 and the current i L} flowing to the load on the structure of the circuit 110 must match the battery charging and discharging current i _bat , the output currents i _s1 and i _s2 are mutually can be adjusted.

4 is a graph illustrating a buck-boost mode operation change of a power control circuit according to an embodiment of the present invention.

4 shows an actual power control method implemented by each power control circuit 110 . Referring to FIG. 4 , power based on intersections 57A and 57B between the input voltage 54 of a renewable energy source such as a piezoelectric element module and a solar module and a battery discharge voltage 55A and a charging voltage 55B It can be seen that the operation of the buck-boost mode of the control circuit 110 is determined. That is, the power control circuit 110 operates in the buck-mode when the input voltage 54 is higher than the discharge voltage 55A or the charging voltage 55B, and is lower than the discharge voltage 55A or the charging voltage 55B. , turn on/off the power switches 102 and 105 to operate in boost-mode. Also, referring to FIG. 2 , the power control circuit 110 operates in the current control mode before reaching the maximum charging voltage point 55 in consideration of the size _{of the battery charging current i bat , and the maximum point 55 .} changes to voltage control mode to maintain a constant charging voltage.

5 is a graph showing a verification result for parallel control of a power control circuit according to an embodiment of the present invention, and FIG. 6 is a graph showing a verification result for a control mode change of the power control circuit.

Referring to FIG. 5 , when there is one voltage input V _in1 , the battery charging current I _bat is maintained low and rises as the _{input V in2} is inputted from the other power control circuit 110 . At this time, since the power control circuit 110 to which _{V in1} is input detects that _{I bat rises through the second current sensor 117B, V in2} is input and the input current I _in1 decreases at the same time. Able to know. In addition, it can be seen that the load current I _load is controlled by dividing the output current to maintain a constant state by the accurate detection of the battery current of each circuit 110 even when the new power control circuit 110 is connected.

Referring to FIG. 6 , it can be seen that when the input voltage is changed, the control mode of the power control circuit 110 is changed to the buck-mode and the boost-mode to be normally controlled. In addition, _{even if the load current I load} is changed, it can be seen that the battery charge/discharge current of each power control circuit 110 is well controlled. That is, through the verification results of FIGS. 5 and 6 , the power control circuit 110 according to an embodiment of the present invention supplies power to the load in parallel through the battery 200 , the power control circuit 110 . ), it can be seen that the battery charge/discharge current can be accurately detected and mutually controlled without additional configuration.

7 is a flowchart of a power control method according to an embodiment of the present invention.

Referring to FIG. 7 , the power control method using the power control circuit 110 according to an embodiment of the present invention includes the steps of detecting the output current of the circuit 110 through the first current sensor 117A (S10), Detecting the charging/discharging current of the battery 200 through the second current sensor 117B (S20) and adjusting the size of the output current based on the charging/discharging current of the battery 200 (S30). can This means a control process that is individually performed by a plurality of power control devices connected in parallel with the battery 200 . Detailed information on each step will be replaced with the circuit 110 described above with reference to FIGS. 3 to 4 .

The above description of the present invention is for illustration, and those of ordinary skill in the art to which the present invention pertains can understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. For example, each component described as a single type may be implemented in a distributed manner, and likewise components described as distributed may also be implemented in a combined form.

The scope of the present invention is indicated by the following claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention. .

101: filter 102: buck-mode switch
103: inductor 104: booster diode
105: switch for booster power
110: power control circuit 117A: first current sensor
117B: second current sensor 118A: first output terminal
118B: second output terminal 120A: first sensing terminal
120B: second sensing terminal 127B: current path
200: battery 220: external load

Claims (7)

In the power control circuit of a renewable energy source operating in a buck-boost mode,
an input terminal to which a renewable energy source is connected;
a first output terminal to which a first current sensor for detecting an output current is connected to one side, and a battery and an external load are connected to the other side;
a second output terminal connected to the external load;
a first sensing terminal to which a second current sensor for detecting the charge/discharge current of the battery is connected to one side and the battery is connected to the other side; and
A power control circuit including a second sensing terminal to which the second current sensor is connected to one side.
The method of claim 1,
When only one power control circuit is connected with the battery,
The other end of the second sensing terminal is a power control circuit, characterized in that connected to the second output terminal.
The method of claim 1,
When a plurality of power control circuits are connected in parallel with the battery,
A second sensing terminal of the other circuit other than the battery is connected to the other side of the first sensing terminal of one of the plurality of power control circuits,
The power control circuit, characterized in that the other side of the second sensing terminal of the plurality of power control circuits is connected to the second output terminal of the plurality of power control circuits.
4. The method of claim 3,
Each of the plurality of power control circuits,
A range in which the sum of the current flowing through the external load and the output currents by comparing the maximum charging current of the battery with the size of the charging/discharging current of the battery measured by the second current sensor coincides with the size of the charging/discharging current of the battery Power control circuit, characterized in that for individually adjusting the magnitude of the output currents in the.
4. The method of any one of claims 1 or 3,
When the input voltage from the renewable energy source changes,
The power control circuit, characterized in that it operates in a buck-mode or a boost-mode by comparing the magnitude of the input voltage and the charging/discharging voltage of the battery.
In a power control method using a power control circuit of a renewable energy source operating in a buck-boost mode,
detecting an output current through a first current sensor by each of a plurality of power control circuits connected in parallel with the battery;
detecting, by each of the plurality of power control circuits, a charging/discharging current of the battery through a second current sensor; and
Each of the plurality of power control circuits compares the maximum charging current of the battery with the size of the charging/discharging current of the battery measured by the second current sensor, and the sum of the current flowing through the external load and the output currents is the charging of the battery. and individually adjusting the magnitudes of the output currents within a range consistent with the magnitudes of the discharge currents.
7. The method of claim 6,
When the input voltage from the renewable energy source is changed, each of the plurality of power control circuits compares the input voltage with the size of the charging/discharging voltage of the battery and operating in the buck-mode or the boost-mode power control method.

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