WO2021101266A1

WO2021101266A1 - Power system

Info

Publication number: WO2021101266A1
Application number: PCT/KR2020/016369
Authority: WO
Inventors: 박정언
Original assignee: 한국항공우주연구원
Priority date: 2019-11-20
Filing date: 2020-11-19
Publication date: 2021-05-27

Abstract

A power system according to an embodiment of the present invention is formed such that a path having a higher power transmission efficiency to a load can be selected in real time by means of changing a control method of a converter switch provided inside a boost converter, even without adding a separate device to an existing power system. The power system according to an embodiment of the present invention has an enhanced power transmission efficiency from a power source unit to a load.

Description

Power system

The present invention relates to a power system that delivers power generated by a power source to a load.

In general, a solar power generation system refers to a power system that converts light energy into electrical energy using a solar panel and delivers the converted electrical energy to a load. As an alternative to resolving global warming and depleting fossil fuels, research and development of solar power generation systems is continuously and actively conducted.

In the solar panel used in the solar power generation system, the power generated varies depending on the temperature of the solar panel and the amount of insolation incident on the solar panel. Accordingly, through the control of tracking the maximum power point in the PV curve of the photovoltaic panel that changes according to the temperature of the photovoltaic panel and the amount of insolation incident on the photovoltaic panel, that is, the maximum power point tracking (MPPT) control. , So that the maximum power can be generated from the solar panel. However, as will be described later, when the control unit transfers the power generated from the solar panel to the load, the power transfer efficiency to the load is high only when the control unit controls the converter MPPT, and the control unit must not control the converter MPPT. In each case, the efficiency of power transfer to the load is high. Accordingly, there is a need to provide a power system that allows the controller to operate in a case where the converter is controlled by MPPT and a case where MPPT is not controlled.

An object of the present invention is to provide a power system capable of improving power transfer efficiency from the power supply to the load by changing the transmission path of the power in real time in delivering the power generated by the power supply to the load.

In order to achieve the above object, a power system according to a first embodiment of the present invention includes a power supply unit for generating power; A boost converter unit for boosting an input voltage by power generated from the power unit and transferring it to a load; And a control unit configured to form a first power transfer path or a second power transfer path for transferring the power from the power supply unit to the load by controlling the boost converter unit, wherein the first power transfer path is formed by the control unit. When the input voltage is boosted by the boost converter unit, the input voltage is transferred to the load, and the second power transmission path is formed by the control unit, the input voltage is boosted by the boost converter unit. It can be delivered to the load without going through the process of being.

The boost converter unit may include an inductor having one end connected to the power supply unit and charged by a current output from the power supply unit; A reverse current prevention element preventing reverse current from flowing from the load to the inductor; And a converter switch having one end connected between the other end of the inductor and the reverse current preventing element, and the other end connected to the ground.

The control unit calculates a magnitude of first power when power is transmitted to the load through the first power transmission path, and second power when power is transmitted to the load through the second power transmission path A magnitude of is calculated, and the converter switch is controlled according to a result of comparing the magnitude of the first power and the magnitude of the second power, and as a result of the comparison, the magnitude of the first power is greater than the magnitude of the second power. When greater than or equal to, the converter switch is turned on and off according to the duty ratio determined by the MPPT (Maximum Power Point Tracking) algorithm to form the first power transfer path. When it is smaller than the magnitude of the second power, the second power transmission path may be formed by controlling the converter switch to be turned off.

In order to achieve the above object, a power system according to a second embodiment of the present invention includes a power supply unit for generating power; A switching unit for selecting a power transmission path through which the power generated by the power unit is transmitted to the load; A boost converter unit that boosts an input voltage by power generated from the power unit and transfers it to the load; And a control unit for controlling a switching operation of the switching unit, wherein the switching unit includes a first switch and a second switch, and the control unit controls the first switch and the second switch in a first switching mode. A first power transmission path through which power is transmitted from a power supply to the load through the boost converter is formed, and the first switch and the second switch are controlled in a second switching mode, so that the load is not passed through the boost converter from the power supply. A second power transfer path through which power is transferred may be formed.

The boost converter unit may include an inductor whose one end is connected to or disconnected from the power supply unit according to a switching operation of the switching unit; A converter switch connected to the other end of the inductor or connected to the power supply according to a switching operation of the switching unit; And a reverse current preventing element for preventing reverse current from flowing from the load to the inductor.

The first switch has one end connected to the power supply, the other end connected to one end or an open terminal of the inductor according to a switching operation controlled by the control unit, and the second switch has one end connected to the converter switch and the It is connected to the reverse current prevention element, and the other end may be connected to the power supply unit or the other end of the inductor according to a switching operation controlled by the control unit.

The control unit calculates a magnitude of first power when power is delivered to the load through the first power transfer path, and a magnitude of second power when power is delivered to the load through the second power transfer path And comparing the magnitude of the first power and the magnitude of the second power. As a result of the comparison, when the first power is greater than or equal to the second power, the other end of the first switch is connected to the inductor. When the first switching mode is connected to one end and the other end of the second switch is connected to the other end of the inductor, and as a result of the comparison, when the first power is less than the second power, the first switch is The second switching mode may be controlled in which the other end is connected to the open terminal and the other end of the second switch is connected to the power supply.

When controlling the switching unit in the first switching mode, the control unit controls the boost converter unit in MPPT, and when controlling the switching unit in the second switching mode, the control unit controls the converter switch without MPPT controlling the boost converter unit. It can be turned off.

In order to achieve the above object, a power system according to a third embodiment of the present invention includes a power supply unit for generating power; A switching unit for selecting a power transmission path through which the power generated by the power unit is transmitted to the load; A buck converter unit stepping down an input voltage due to power generated from the power supply unit and transferring it to the load; And a control unit for controlling a switching operation of the switching unit, wherein the switching unit includes a first switch, a second switch, and a third switch, and the control unit includes the first switch, the second switch, and the third switch. By controlling in a first switching mode, a first power transmission path through which electric power is transmitted from the power supply unit to the load through the buck converter unit is formed, and the first switch, the second switch, and the third switch are set in a second switching mode. By controlling, it is possible to form a second power transmission path through which power is transmitted from the power supply unit to the load without passing through the buck converter unit.

The buck converter unit includes: a converter switch whose one end is connected to or disconnected from the power supply unit according to a switching operation of the switching unit; A reverse current prevention element having one end connected to the ground or connected to the power supply according to a switching operation of the switching unit, and the other end connected to the other end of the converter switch; And an inductor having one end connected to the other end of the converter switch and the other end connected to the load.

The first switch has one end connected to the ground, the other end connected to one end of the reverse current preventing element or turned off according to a switching operation of the switching unit controlled by the control unit, and the second switch has one end connected to the It is connected to a power supply, and the other end is connected to one end of the converter switch or to one end of the reverse current preventing element according to a switching operation of the switching unit controlled by the control unit, and the third switch has one end of the inductor. It is connected to the other end, and the other end may be turned off according to a switching operation of the switching unit controlled by the control unit, or may be connected to the other end of the converter switch.

The control unit calculates a magnitude of first power when power is delivered to the load through the first power transfer path, and a magnitude of second power when power is delivered to the load through the second power transfer path And comparing the magnitude of the first power and the magnitude of the second power, and as a result of the comparison, when the magnitude of the first power is greater than or equal to the magnitude of the second power, the other end of the first switch Is connected to one end of the reverse current preventing element, the other end of the second switch is connected to one end of the converter switch, and the first switching mode is controlled to turn off the other end of the third switch, and the comparison result, When the magnitude of the first power is smaller than the magnitude of the second power, the other end of the first switch is turned off, the other end of the second switch is connected to one end of the reverse current preventing element, and the third switch It is possible to control the second switching mode in which the other end is connected to the other end of the converter switch.

When controlling the switching unit in the first switching mode, the control unit may MPPT control the buck converter unit, and when controlling the switching unit in the second switching mode, the buck converter unit may not MPPT control.

In order to achieve the above object, a power system according to a fourth embodiment of the present invention includes a power supply unit for generating power; A buck-boost converter unit for boosting or stepping down an input voltage by power generated from the power supply unit and transferring it to a load; And a control unit for controlling the buck-boost converter unit to form a first power transfer path, a second power transfer path, or a third power transfer path for transferring power from the power supply unit to the load, wherein the control unit 1 When the power transmission path is formed, the input voltage is transferred to the load through a process of boosting by the buck-boost converter unit, and when the second power transmission path is formed by the control unit, the input voltage When the third power transmission path is formed by the control unit, the input voltage is boosted and stepped down by the buck-boost converter unit when the voltage is stepped down by the buck-boost converter unit and transferred to the load. It can be delivered to the load without going through the process of being.

The buck-boost converter unit may include an inductor charged by a current output from the power supply unit; A first converter switch provided between one end of the inductor and the power supply unit; A second converter switch provided between the other end of the inductor and the load; A third converter switch provided between one end of the inductor and a ground; And a fourth converter switch provided between the other end of the inductor and the ground.

The control unit calculates a magnitude of first power when power is transmitted to the load through the first power transmission path, and third power when power is transmitted to the load through the third power transmission path And control the first converter switch, the second converter switch, the third converter switch, and the fourth converter switch according to a result of comparing the magnitude of the first power and the magnitude of the third power. And, as a result of the comparison, when the magnitude of the first power is greater than or equal to the magnitude of the third power, the buck-boost converter unit controls the MPPT to form the first power transfer path, and as a result of the comparison, the When the magnitude of the first power is smaller than the magnitude of the third power, the buck-boost converter unit may form the third power transmission path without MPPT control.

When the comparison result shows that the first power is greater than or equal to the third power, the first converter switch is turned on and the third power transfer path is formed. The converter switch is turned off, and the on-off operation of the second converter switch and the fourth converter switch is alternately controlled according to a duty ratio according to the MPPT algorithm to boost the input voltage, and as a result of the comparison, the first power is When the magnitude is smaller than the magnitude of the third power, the first converter switch and the second converter switch are turned on to form the third power transmission path, and the third converter switch and the fourth converter switch Can be turned off.

The control unit calculates the magnitude of the second power when power is transferred to the load through the second power transfer path, and the third power when power is transferred to the load through the third power transfer path. And controlling the first converter switch, the second converter switch, the third converter switch, and the fourth converter switch according to a result of comparing the magnitude of the second power and the magnitude of the third power. And, as a result of the comparison, when the magnitude of the second power is greater than or equal to the magnitude of the third power, the buck-boost converter unit controls the MPPT to form the second power transfer path, and the comparison result, the When the magnitude of the second power is smaller than the magnitude of the third power, the buck-boost converter unit may form the third power transmission path without MPPT control.

The control unit, in the comparison result, when the magnitude of the second power is greater than or equal to the magnitude of the third power, to form the second power transmission path, the second converter switch is turned on and the fourth The converter switch is turned off, and the on-off operation of the first converter switch and the third converter switch is alternately controlled according to a duty ratio according to the MPPT algorithm to step down the input voltage, and as a result of the comparison, the second power is When the magnitude is smaller than the magnitude of the third power, in order to form the third power transmission path, the first converter switch and the second converter switch are turned on, and the third converter switch and the fourth converter switch Can be turned off.

The power system according to the first embodiment of the present invention has higher power transfer efficiency to the load by changing the control method of the converter switch provided inside the boost converter without adding a separate element to the existing power system. It is configured so that the route can be selected in real time. According to the power system according to the first embodiment of the present invention, the efficiency of power transfer from the power supply unit to the load can be improved.

In the power system according to the second and third embodiments of the present invention, since a switching element is provided in a path through which power is transmitted, a path having higher power transfer efficiency to a load according to the switching operation of the switching element It is configured to be able to select in real time. According to the power system according to the second and third embodiments of the present invention, the efficiency of power transfer from the power supply to the load can be improved.

The power system according to the fourth embodiment of the present invention transfers power to the load by changing the control method of a plurality of converter switches provided inside the buck-boost converter without adding additional elements to the existing power system. It is configured so that a route with higher efficiency can be selected in real time. According to the power system according to the fourth embodiment of the present invention, the efficiency of power transfer from the power source to the load can be improved.

1A is a diagram illustrating a PV curve of a solar panel that changes according to the temperature of the solar panel when the amount of insolation incident on the solar panel is 1 kW/m ^2.

1B is a diagram showing a P-V curve of a solar panel that changes according to the amount of insolation incident on the solar panel when the temperature of the solar panel is 25°C.

2 is a diagram showing power transfer efficiency of a converter used in a solar power generation system according to a load factor.

FIG. 3 is a diagram showing power delivered to a load when MPPT control is used and power delivered to a load when MPPT control is not used.

4 is a diagram showing a power system according to a first embodiment of the present invention.

5A is a diagram illustrating a case in which a first power transmission path is formed in the power system of FIG. 4.

5B is a diagram illustrating a case in which a second power transmission path is formed in the power system of FIG. 4.

6 is a flowchart illustrating a method of controlling the power system of FIG. 4.

7 is a diagram showing a power system according to a second embodiment of the present invention.

8A is a diagram illustrating an equivalent circuit when the power system of FIG. 7 operates in a first switching mode.

8B is a diagram illustrating an equivalent circuit when the power system of FIG. 7 operates in a second switching mode.

9 is a diagram showing a power system according to a third embodiment of the present invention.

10A is a diagram illustrating an equivalent circuit when the power system of FIG. 9 operates in a first switching mode.

10B is a diagram illustrating an equivalent circuit when the power system of FIG. 9 operates in a second switching mode.

11 is a diagram showing a power system according to a fourth embodiment of the present invention.

12A is a diagram illustrating a case in which a first power transmission path is formed in the power system of FIG. 11.

12B is a diagram illustrating a case in which a second power transmission path is formed in the power system of FIG. 11.

12C is a diagram illustrating a case in which a third power transmission path is formed in the power system of FIG. 11.

13A is a flowchart illustrating a method of controlling the power system of FIG. 11.

13B is another flowchart illustrating a method of controlling the power system of FIG. 11.

Hereinafter, a power system according to the present invention will be described in detail with reference to the accompanying drawings. The accompanying drawings are provided by way of example only in order to sufficiently convey the technical idea of the present invention to those skilled in the art, and the present invention is not limited to the drawings presented below and may be embodied in any other form. have. In addition, the term'… Terms such as'sub' and'module' mean a unit that processes at least one function or operation, which may be implemented as hardware or software, or a combination of hardware and software.

1A is a view showing a PV curve of a solar panel that changes according to the temperature of the solar panel when the solar radiation incident on the solar panel is 1kW/m ² , and FIG. 1B is a diagram showing the PV curve of the solar panel when the temperature of the solar panel is 25°C. At this time, it is a diagram showing the PV curve of the solar panel that changes according to the amount of insolation incident on the solar panel.

In FIGS. 1A and 1B, the x-axis represents an output voltage of a solar panel and an input voltage of a converter to be described later. In FIGS. 1A and 1B, the y-axis represents power generated by the solar panel.

As shown in FIGS. 1A and 1B, power generated by the solar panel varies according to the temperature of the solar panel and the amount of insolation incident on the solar panel. In order to generate the maximum power from the solar panel, the output voltage of the solar panel (or the input voltage of the converter) must be the same as the output voltage corresponding to the maximum power point of the P-V curve. To this end, the controller unit controls the MPPT of the converter connected to the output terminal of the solar panel, so that the output voltage of the solar panel (or the input voltage of the converter) matches the output voltage corresponding to the maximum power point of the P-V curve. Here, the MPPT control is a control that matches the output voltage of the solar panel (or the input voltage of the converter) with the output voltage corresponding to the maximum power point of the PV curve in order to generate the maximum power from the solar panel. Say.

As a method for controlling MPPT, a P&O (Perturbation and Obsevation, post-perturbation estimation) method is generally used. The P&O method is a method of following the maximum power point by comparing the previous output power with the current output power while periodically increasing or decreasing the output voltage of the solar panel.

According to the P&O method, the controller MPPT controls the converter so that the output voltage of the solar panel (or the input voltage of the converter) follows the maximum power point of the P-V curve, as shown in the dotted line shown in FIGS. 1A and 1B. That is, the control unit MPPT controls the converter so that the output voltage of the solar panel (or the input voltage of the converter) becomes the same as the voltage corresponding to the maximum power point of the PV curve, thereby generating the maximum power in the solar panel. You will be able to. However, in addition to the above-described P&O method, various MPPT algorithms such as InCond (Incremental Conductance) method are known, and of course, any one of these various MPPT algorithms may be used for MPPT control mentioned below.

2 is a diagram showing power transfer efficiency of a converter used in a solar power generation system according to a load factor. Referring to FIG. 2, it can be seen that the converter used in the solar power generation system has a high power transfer efficiency of about 95% or more at a load ratio of 60% or more, but the power transfer efficiency is less than 95% at a load ratio of less than 60%.

On the other hand, when the controller transfers power generated from the solar panel to the load, more power may be delivered to the load when the controller does not MPPT the converter compared to when the controller MPPT controls the converter. .

FIG. 3 is a diagram showing power delivered to a load when MPPT control is used and power delivered to a load when MPPT control is not used. More specifically, FIG. 3 shows that when the amount of irradiation incident on the solar panel is 1000W/m ² and the temperature of the solar panel is 25˚C and 75˚C, respectively, the controller MPPT controls the converter to generate it in the solar panel. This is a graph that analyzes the case of transmitting the power to the load and the case of transmitting the power output from the solar panel to the load without the controller controlling the MPPT of the converter through simulation. A region in which more power is transmitted to the load when the controller does not MPPT the converter than when the controller MPPT controls the converter is shown in shades in FIG. 3.

When the controller MPPT controls the converter, the output voltage of the solar panel (or the input voltage of the converter) is variable so that the solar panel always generates maximum power regardless of the load voltage. Accordingly, the power delivered to the load in the period in which the load voltage is 240V ~ 320V is about 6750W or about 5380W regardless of the load voltage.

According to FIG. 3, when the amount of irradiation incident on the solar panel is 1000 W/m ² , the temperature of the solar panel is 25° C., and the load voltage is 270 V to 315 V, the controller controls the converter MPPT. In contrast, when the controller does not MPPT the converter, it can be seen that the maximum power of about 300W is further delivered to the load.

In addition, according to FIG. 3, when the amount of irradiation incident on the solar panel is 1000 W/m ² and the temperature of the solar panel is 75° C., in the section where the load voltage is 240 V to 255 V, the controller MPPT controls the converter. Compared to the case, when the controller does not MPPT the converter, it can be seen that the maximum power of about 220W is further delivered to the load.

As described above, according to FIG. 3, when the control unit transfers power generated from the solar panel to the load, the power transfer efficiency to the load is relatively high only when the control unit controls the converter MPPT, and the control unit does not control the converter MPPT. It can be seen that there are cases in which the power transfer efficiency to the load is relatively high.

In FIG. 3, the amount of power transferred to the load was compared only when the amount of insolation incident on the solar panel is 1000W/m ² and the temperature of the solar panel is 25°C and 75°C, respectively. However, the insolation and temperature are values that continuously change throughout the day (generally, insolation is about 0 to 1500 W/m ² , and the temperature varies in the range of about -20 to 80 °C). Therefore, in addition to the shaded portions in FIG. 3, when the controller does not MPPT the converter, compared to the case where the controller MPPT controls the converter, the number of load voltage intervals in which more power can be delivered to the load is Can exist.

Referring to FIG. 4, the power system 1000a according to the first embodiment of the present invention includes a power supply unit 110, a boost converter unit 120, and a control unit 130.

The power supply unit 110 is a component that generates power, and may be a solar panel that converts light energy into electrical energy. In this case, the solar panel is a combination of solar cell modules capable of converting sunlight into direct current power and outputting it. Can be configured. The solar cell module may be made of a series connection or parallel connection of solar cell cells, or a combination of series-parallel connection.

4 illustrates a battery for storing DC power as an example of the load 10a, but it may correspond to the load 10a as long as it is a device receiving the DC power.

The boost converter unit 120 may receive an input voltage due to power generated from the power supply unit 110, boost the input voltage, and transfer the voltage to the load 10a. Here, the input voltage refers to a voltage constituting power generated from the power supply unit 110 and a voltage applied to the input terminal of the boost converter unit 120. The boost converter unit 120 may include an inductor 121, a converter switch 122, and a reverse current prevention element 123.

One end of the inductor 121 is connected to the power supply unit 110, the other end of the inductor 121 is connected to the converter switch 122, and electrical energy is supplied to the inductor 121 by the input current output from the power supply unit 110. Is charged. Here, the input current is a current constituting power generated from the power supply unit 110 and refers to a current flowing from the power supply unit 110 to the boost converter unit 120.

The reverse current prevention element 123 is configured to prevent a reverse current from flowing from the load 10a to the inductor 121. As the reverse current prevention device 123, various devices such as diodes and FETs may be used.

One end of the converter switch 122 is connected between the other end of the inductor 121 and the reverse current prevention element 123, and the other end is connected to the ground. The converter switch 122 is a device that determines whether to conduct current through conduction (on state) or non-conduction (off state), and, for example, a semiconductor switch, a metal oxide semiconductor field effect transistor (MOSFET) may be used. However, it is not limited thereto.

The control unit 130 is a component that controls the boost converter unit 120, and specifically, the input voltage output from the power supply unit 110 by MPPT control of the boost converter unit 120 is boosted by the boost converter unit 120. A first power transmission path that is transmitted to the load 10a through the process may be formed.

Alternatively, the control unit 130 does not control the boost converter unit 120 to MPPT, but controls the converter switch 122 to be off, so that the input voltage output from the power supply unit 110 is boosted by the boost converter unit 120 It is possible to form a second power transmission path that is transmitted to the load 10a without passing through.

In addition, the control unit 130 calculates the magnitude of the first power (P1) in the case of transmitting power to the load 10a through the first power transfer path, and provides power to the load 10a through the second power transfer path. The magnitude of the second power (P2) in the case of transmitting is calculated. Thereafter, the controller 130 compares the calculated magnitudes P1 and P2 of the first power and the second power, and controls the converter switch 122 of the boost converter 120 according to the comparison result.

At this time, if the comparison result is that the first power is greater than or equal to the second power, the controller 130 controls on and off the converter switch 122 according to the duty ratio determined by the MPPT algorithm to control the first power. If a power transmission path is formed and the comparison result is that the magnitude of the first power (P1) is smaller than the magnitude of the second power (P2), the converter switch 122 is turned off without MPPT control to transmit the second power. Form a path

Here, the first power is power transferred from the power supply 110 to the load 10a when the control unit 130 controls the boost converter unit 120 to MPPT, and the second power is the control unit 130 This is the power transferred from the power supply unit 110 to the load 10a when 120 is not controlled by MPPT.

The first power level P1 may be calculated by the control unit 130 using the MPPT algorithm by receiving values of the open-circuit voltage V1 and the short-circuit current I1 of the output terminal of the power supply unit 110.

When the control unit 130 receives the current voltage V2 of the load 10a and the current voltage V2 of the load 10a is applied to the power supply unit 110, the second power level P2 is determined by the power supply unit 110 It can be calculated by calculating the value of the power output from. Alternatively, the magnitude P2 of the second power may be calculated by the controller 130 receiving the current voltage V2 of the load 10a and the current flowing through the load 10a.

According to the first embodiment of the present invention, the controller 130 compares the magnitude of the first power (P1) and the magnitude of the second power (P2), and 2 Since it is configured to select a path having a higher power transfer efficiency to the load 10a among the power transfer paths in real time, the power transfer efficiency of the load 10a can be maximized.

The power system 1000a according to the first embodiment of the present invention may further include an input side storage unit 140 that stores an input voltage by power generated from the power supply unit 110. In this case, the input-side storage unit 140 may be connected between the power supply unit 110 and the boost converter unit 120. The input-side storage unit 140 serves to supply a stable DC voltage to the boost converter unit 120 when noise or voltage fluctuates in the input voltage output from the power supply unit 110, and the input-side storage unit 140 As the furnace, a capacitor may be used.

In addition, the power system 1000a according to the first embodiment of the present invention may further include an output side storage unit 150 that stores the voltage boosted by the boost converter unit 120. At this time, the output-side storage unit 150 is connected between the boost converter unit 120 and the load 10a. The output-side storage unit 150 serves to rectify a voltage to supply a DC voltage to the load 10a, and a capacitor may be used as the output-side storage unit 150.

5A is a diagram illustrating a case where a first power transmission path is formed in the power system of FIG. 4, and FIG. 5B is a diagram illustrating a case where a second power transmission path is formed in the power system of FIG. 4. Hereinafter, the first power transfer path and the second power transfer path will be described in more detail with reference to FIGS. 5A and 5B.

First, referring to FIG. 5A, when the magnitude of the first power P1 is greater than or equal to the magnitude of the second power P2, the controller 130 forms a first power transmission path.

When the magnitude of the first power (P1) is greater than or equal to the magnitude of the second power (P2), it means that more power is transmitted to the load 10a when the boost converter unit 130 is MPPT-controlled. 130) forms a first power transmission path in a manner of controlling the on/off of the converter switch 122 using the duty ratio determined according to the MPPT algorithm.

While the converter switch 122 is turned on, an input current flows in the solid line direction of FIG. 5A to charge energy in the inductor 121, and the input current in the dotted line direction of FIG. 5A while the converter switch 122 is operated off. As the flow flows, the energy charged in the inductor 121 and the input current output from the power supply unit 110 flow into the load 10a at the same time, thereby boosting the input voltage.

At this time, since the input voltage output from the power supply unit 110 is boosted so that the maximum power can be delivered to the load 10a by the MPPT control of the control unit 130, the maximum power followed by the MPPT control is transmitted to the load 10a. Can be.

Next, referring to FIG. 5B, when the magnitude P1 of the first power is smaller than the magnitude P2 of the second power, the controller 130 forms a second power transmission path.

When the magnitude of the first power P1 is smaller than the magnitude of the second power P2, it means that more power is transmitted to the load 10a when the boost converter unit 120 is not MPPT controlled. 130) turns off the converter switch 122 without controlling the boost converter unit 120 by MPPT. When the converter switch 122 is turned off, the input voltage is not boosted by the boost converter unit 120, so the current voltage of the load 10a is applied to the power supply unit 110. Here, that the voltage of the load 10a is applied to the power supply unit 110 means that a voltage equal to the difference between the voltage of the load 10a and the voltage across the reverse current prevention element 123 is applied across the power supply unit 110. That is, the current output from the power supply unit 110 flows in the solid line direction of FIG. 5B and is transferred to the load 10a as it is only through the inductor 121 and the reverse current prevention element 123.

At this time, since a DC voltage is applied to the inductor 121, the inductor 121 operates like a short circuit, and thus, core loss due to the inductor 121 does not occur.

Meanwhile, when a diode is used as the reverse current prevention element 123, the anode of the diode is connected to the other end of the inductor 121 and the converter switch 122, and the cathode of the diode is connected to the load 10a, Reverse current does not flow from the load 10a to the inductor 121. Since the voltage drop of the diode is about 0.7V, which is a very small value, most (99% or more) of the power generated by the power supply unit 110 may be delivered to the load 10a.

Alternatively, a FET may be used as the reverse current prevention element 123, and in this case, the controller 130 may control the FET to be turned on and off. By controlling the FET to be turned on and off by the control unit 130, it is possible to prevent a reverse current from flowing from the load 10a to the inductor 121. In addition, the diode has a voltage drop even in a small amount, whereas the voltage drop theoretically does not exist in the ON state of the FET, and thus power transfer efficiency to the load 10a may be higher than when a diode is used.

6 is a flowchart illustrating a method of controlling the power system of FIG. 4. The method of controlling the power system of FIG. 4 may be performed by the control unit 130 described above.

The control method of the power system according to the first embodiment of the present invention includes a first power level P1 and a second power when the control unit 130 transfers power to the load 10a through the first power transfer path. The step of calculating the magnitude P2 of the second power when power is delivered to the load 10a through the power transfer path may be performed (S110).

As described above, the first power is power transferred from the power supply unit 110 to the load 10a when the control unit 130 controls the boost converter unit 120 to MPPT, and the second power is the control unit 130 This is the power transferred from the power supply unit 110 to the load 10a when the boost converter unit 120 is not MPPT controlled.

However, it is also possible to directly calculate the magnitude of the first power (P1) and the magnitude of the second power (P2) through sensing the voltage of the output terminal of the power supply unit 110, the voltage of the load 10a, and the current. Through the method, the magnitude of the first power (P1) and the magnitude of the second power (P2) may be calculated.

For example, one solar cell of the same model as the solar cell constituting a solar panel is separately provided for sensing and calculation purposes, not for power generation purposes, and the current of the one solar cell at the corresponding temperature and insolation And/or after sensing the voltage, the magnitude of the first power P1 may be calculated by calculating the power of the entire solar panel.

Accordingly, a method of calculating the magnitude of the first power P1 and the magnitude of the second power P2 is not limited, and it should be understood that all other computation methods are included.

Next, the controller 130 compares the magnitude of the first power (P1) and the magnitude of the second power (P2) (S120), and thereafter, according to the comparison result, the controller 130 determines the boost converter unit 120 Controls the converter switch 122 included in) (S130).

More specifically, when the magnitude of the first power P1 is greater than or equal to the magnitude of the second power P2, the controller 130 forms a first power transmission path.

When the magnitude of the first power (P1) is greater than or equal to the magnitude of the second power (P2), it means that more power is transmitted to the load 10a when the boost converter unit 130 is MPPT-controlled. In step 130), a first power transmission path is formed by controlling the on/off of the converter switch 122 using the duty ratio determined according to the MPPT algorithm (S131).

At this time, since the input voltage output from the power supply unit 110 is boosted to deliver the maximum power to the load 10a by the MPPT control of the control unit 130, the maximum power followed by the MPPT control is transmitted to the load 10a. Can be.

Although mentioned above, various algorithms such as the P&O method and the InCond method are known as the MPPT algorithm, and among these various MPPT algorithms for MPPT control mentioned in the power system control method according to the first embodiment of the present invention Either can be used.

When the magnitude P1 of the first power is smaller than the magnitude P2 of the second power, the controller 130 forms a second power transmission path.

When the magnitude of the first power P1 is smaller than the magnitude of the second power P2, it means that more power is transmitted to the load 10a when the boost converter unit 120 is not MPPT controlled. In operation S132, the boost converter 120 is not controlled by MPPT, but the converter switch 122 is turned off to form a second power transmission path (S132).

At this time, when the converter switch 122 is turned off, the input voltage is not boosted by the boost converter unit 120, so the current voltage of the load 10a is applied to the power supply unit 110. Here, that the voltage of the load 10a is applied to the power supply unit 110 means that a voltage equal to the difference between the voltage of the load 10a and the voltage across the reverse current prevention element 123 is applied across the power supply unit 110. That is, the current output from the power supply unit 110 is transmitted to the load 10a as it is through only the inductor 121 and the reverse current prevention element 123.

According to the first embodiment of the present invention, by changing only the control method of the converter switch of the boost converter unit without adding a separate element to the existing power system, the load among the paths in which MPPT control is performed and the paths in which MPPT control is not performed. Power can be delivered to the load by selecting a path with higher power transfer efficiency to the road in real time. According to the power system according to the first embodiment of the present invention, power can be delivered to a load with higher efficiency compared to a conventional power system using only MPPT control.

Referring to FIG. 7, a power system 1000b according to a second embodiment of the present invention includes a power supply unit 210, a switching unit 220, a boost converter unit 230, and a control unit 240.

The power supply unit 210 is a component that generates power, and may be a solar panel that converts light energy into electrical energy. In this case, the solar panel is a combination of solar cell modules that can convert sunlight into DC power and output it. Can be configured. The solar cell module may be made of a series connection or parallel connection of solar cells, or a combination of series-parallel connection.

The switching unit 220 includes a first switch 221 and a second switch 222 as a configuration capable of selecting a power transmission path when the power generated by the power supply unit 210 is transferred to the load 10b. . Here, the first switch 221 and the second switch 222 may be any device having a function of switching a path through which a current flows.

7 illustrates a battery for storing DC power as an example of the load 10b, but it may correspond to the load 10b as long as it is a device receiving the DC power.

The boost converter unit 230 may receive an input voltage by power generated from the power supply unit 210, boost the input voltage, and transfer the voltage to the load 10b. Here, the input voltage refers to a voltage constituting power generated from the power supply unit 210 and a voltage applied to the input terminal of the boost converter unit 230. The boost converter unit 230 may include an inductor 231, a converter switch 232, and a reverse current prevention element 233.

One end and the other end of the inductor 231 are connected to the switching unit 220. One end of the inductor 231 is connected to or disconnected from the power supply 210 according to the switching operation of the switching unit 220, and the other end of the inductor 231 is connected to the power supply 210 according to the switching operation of the switching unit 220. Or connected to the converter switch 232.

The converter switch 232 is connected to the other end of the inductor 231 or to the power supply 210 according to the switching operation of the switching unit 220. The converter switch 232 is a device that determines whether to conduct current through conduction (on state) or non-conduction (off state), and, for example, a MOSFET, which is a semiconductor switch, may be used, but is not limited thereto.

The reverse current prevention element 233 is configured to prevent a reverse current from flowing from the load 10b to the inductor 231. Various devices such as diodes and FETs may be used as the reverse current prevention device 233.

Meanwhile, in the power system according to the second embodiment of the present invention, a specific circuit structure in which the first switch 221 and the second switch 222 of the switching unit 220 are connected is as follows.

The first switch 221 has one end connected to the power supply 210 and the other end connected to one end of the inductor 231 or connected to an open terminal according to a switching operation of the first switch 221. Here, that the other end of the first switch 221 is connected to the open terminal means that no element is electrically connected to the other end of the first switch 221.

The second switch 222 is provided so that one end is connected to one end of the converter switch 232 and the reverse current prevention element 233, and the other end is connected to the other end of the power supply unit 210 or the inductor 231 according to the switching operation. .

The control unit 240 is a component that controls the MPPT control of the boost converter unit 230 and the switching operation of the switching unit 220. More specifically, the control unit 240 controls the first switch 221 and the second switch 222 in the first switching mode to power the load 10b from the power supply unit 210 through the boost converter unit 230. This can form a first power transfer path to be transferred.

Here, the power is transmitted through the boost converter unit 230, since power is transferred from the power supply unit 210 to the load 10b, the voltage output from the power supply unit 210 is variable by the boost converter unit 230. It means going through the process of becoming.

In addition, the control unit 240 controls the first switch 221 and the second switch 222 in a second switching mode, so that power is transferred from the power supply unit 210 to the load 10b without passing through the boost converter unit 230. A second power transmission path to be transmitted may be formed.

Here, that the power is transmitted without passing through the boost converter unit 230, since power is transferred from the power supply unit 210 to the load 10b, the voltage output from the power supply unit 210 is transmitted by the boost converter unit 230. It means that it doesn't go through the process of being variable.

In addition, the control unit 240 calculates the magnitude of the first power when power is delivered to the load 10b through the first power transfer path, and transfers power to the load 10b through the second power transfer path. The magnitude of the second power in the case is calculated. Thereafter, the control unit 240 compares the calculated magnitudes of the first power and the second power, and controls the switching operation of the switching unit 220 according to the comparison result.

At this time, if the comparison result is that the first power is greater than or equal to the second power, the control unit 240 controls the first switch 221 and the second switch 222 in a first switching mode, and the If the comparison result shows that the first power is smaller than the second power, the first switch 221 and the second switch 222 are controlled in the second switching mode.

Here, the first power is the power transferred from the power supply 210 to the load 10b when the control unit 240 controls the boost converter unit 230 to MPPT, and the second power is the control unit 240 is the boost converter unit ( When the MPPT control 230) is not performed, this is the power transferred from the power supply unit 210 to the load 10b.

The magnitude of the first power may be calculated by the control unit 240 using the MPPT algorithm by receiving values of the open-circuit voltage V1 and the short-circuit current I1 of the output terminal of the power supply unit 210.

The magnitude of the second power is output from the power supply 210 when the control unit 240 receives the current voltage V2 of the load 10b and the current voltage V2 of the load 10b is applied to the power supply 210. It can be calculated by calculating the power value. Alternatively, the magnitude of the second power may be calculated by the controller 240 receiving the current voltage V2 of the load 10b and the current flowing through the load 10b.

According to the second embodiment of the present invention, the controller 240 compares the magnitude of the first power and the magnitude of the second power, and according to the comparison result, a load among the first power transfer path and the second power transfer path Since it is configured to select a path having a higher power transfer efficiency to (10b) in real time, the power transfer efficiency to the load (10b) can be maximized.

The power system 1000b according to the second embodiment of the present invention may further include an input side storage unit 250 that stores an input voltage by power generated from the power supply unit 210. In this case, the input-side storage unit 250 may be connected between the power supply unit 210 and the boost converter unit 230. The input-side storage unit 250 serves to supply a stable DC voltage to the boost converter unit 230 when noise or voltage fluctuates in the input voltage output from the power supply unit 210, and the input-side storage unit 250 As the furnace, a capacitor may be used.

In addition, the power system 1000b according to the second embodiment of the present invention may further include an output side storage unit 260 that stores the voltage boosted by the boost converter unit 230. At this time, the output-side storage unit 260 is connected between the boost converter unit 230 and the load 10b. The output-side storage unit 260 serves to rectify a voltage to supply a DC voltage to the load 10b, and a capacitor may be used as the output-side storage unit 260.

FIG. 8A is a diagram illustrating an equivalent circuit when the power system of FIG. 7 operates in a first switching mode, and FIG. 8B is a diagram illustrating an equivalent circuit when the power system of FIG. 7 operates in a second switching mode. Hereinafter, the first switching mode and the second switching mode will be described in more detail with reference to FIGS. 8A and 8B.

First, referring to FIG. 8A, power generated by the power supply unit 210 is transmitted to a first power transmission path, which is a path transmitted to the load 10b through the boost converter unit 230. The control unit 240 tracks the maximum power by controlling the boost converter unit 230 by MPPT control, varying the voltage output from the power supply unit 210 and transmitting it to the load 10b.

In the first switching mode forming the first power transmission path, when the magnitude of the first power is greater than or equal to the magnitude of the second power, the other end of the first switch 221 is connected to one end of the inductor 231 , This is a mode in which the other end of the second switch 222 is connected to the other end of the inductor 231.

When the first power is greater than or equal to the second power, it means that more power is transmitted to the load 10b when the boost converter unit 230 is MPPT controlled. MPPT control. At this time, the control unit 240 connects the other end of the first switch 221 to one end of the inductor 231 so that the current output from the power supply unit 210 flows to the inductor 231 and charges the inductor 231. 2 Connect the other end of the switch 222 to the other end of the inductor 231 so that the inductor 231 is connected to the converter switch 232 and the reverse current prevention element 233.

At this time, since the voltage output from the power supply unit 210 is variable so as to transmit the maximum power to the load 10b by the MPPT control of the control unit 240, the maximum power followed by the MPPT control will be delivered to the load 10b. I can.

Next, referring to FIG. 8B, power generated by the power supply unit 210 is transmitted to the load 10b through only the reverse current prevention element 233. The control unit 240 controls the boost converter unit 230 to be transferred to the load 10b without changing the voltage generated by the power supply unit 210 by turning off the converter switch 232 without performing MPPT control. In this case, the power transmitted from the power supply unit 210 to the load 10b is transmitted through the second power transmission path without passing through the boost converter unit 230.

In the second switching mode forming the second power transmission path, when the magnitude of the first power is smaller than the magnitude of the second power, the other end of the first switch 221 is connected to the open terminal, and the second switch 222 The other end of) is a mode connected to the power supply 210.

When the first power is less than the second power, it means that more power is transmitted to the load 10b when the boost converter unit 230 is not MPPT controlled. MPPT is not controlled. At this time, the control unit 240 connects the other end of the first switch 221 to the open terminal to cut off the circuit line connected from the power supply 210 to the inductor 231 located at the input terminal of the boost converter unit 230, and The other end of the switch 222 is connected to the power supply unit 210, and the power unit 210 is connected to the converter switch 232 and the reverse current prevention element 233.

At this time, the controller 240 turns off the converter switch 232. When the converter switch 232 is turned off, the current voltage of the load 10b is applied to the power supply unit 210. Here, that the voltage of the load 10b is applied to the power supply 210 means that a voltage equal to the voltage difference between the voltage of the load 10b and the voltage across the reverse current prevention element 233 is applied to the power supply 210, and at this time, the power supply unit The current output from 210 is transferred to the load 10b as it is through only the reverse current prevention element 233.

Meanwhile, when a diode is used as the reverse current prevention element 233, the anode of the diode is connected to the other end of the inductor 231 and the converter switch 232, and the cathode of the diode is connected to the load 10b, Reverse current does not flow from the load 10b to the inductor 231. Since the voltage drop of the diode is about 0.7V, which is a very small value, most (99% or more) of the power generated by the power supply 210 may be transferred to the load 10b.

Alternatively, a FET may be used as the reverse current prevention element 233. When the FET is used, the controller 240 may control the FET on and off, and the inductor 231 in the load 10b by the on/off control of the FET. It can prevent reverse current from flowing in the) direction. In addition, since the diode does not have a voltage drop theoretically when the FET is turned on, compared to a small amount of a voltage drop in the diode, power transfer efficiency to the load 10b may be higher than when a diode is used.

On the other hand, simply by keeping the converter switch 232 in the off state, power can be delivered to the load 10b without performing MPPT control, but if the switching unit 220 is provided as in the second embodiment of the present invention When operating in the second switching mode, a bypass path can be formed so that the current output from the power supply unit 210 does not pass through the inductor 231, so that a ripple phenomenon that may be caused by the inductor 231 can be prevented in advance. .

According to the second embodiment of the present invention, by changing the structure of adding only a two poles switch element without adding a resistor, an inductor or a capacitor, power is transferred among the paths in which MPPT control is performed and the paths in which MPPT control is not performed. You can choose a path with higher efficiency to deliver power to the load. Therefore, there is an effect that power can be delivered to the load with higher efficiency than when performing only MPPT control.

Referring to FIG. 9, a power system 1000c according to a third embodiment of the present invention includes a power supply unit 310, a switching unit 320, a buck converter unit 330, and a control unit 340.

The power supply unit 310 is a component that generates power, and may be a solar panel that converts light energy into electrical energy. In this case, the solar panel is a combination of solar cell modules that can convert sunlight into DC power and output it. Can be configured. The solar cell module may be made of a series connection or parallel connection of solar cells, or a combination of series-parallel connection.

The switching unit 320 is a configuration capable of selecting a power transmission path when the power generated by the power supply unit 310 is transferred to the load 10c, and includes a first switch 321, a second switch 322, and a second switch. It includes three switches 323. Here, the first switch 321, the second switch 322, and the third switch 323 may be any element having a function of switching a path through which current flows.

9 illustrates a battery for storing DC power as an example of the load 10c, but it may correspond to the load 10c as long as it is a device receiving the DC power.

The buck converter unit 330 may receive an input voltage due to power generated from the power supply unit 310, step down the input voltage, and transfer the voltage to the load 10c. Here, the input voltage refers to a voltage constituting power generated from the power supply unit 310 and a voltage applied to the input terminal of the buck converter unit 330. The buck converter unit 330 may include a converter switch 331, a reverse current prevention element 332, and an inductor 333.

The converter switch 331 has one end and the other end connected to the switching unit 320. One end of the converter switch 331 is connected to or disconnected from the power supply 310 according to the switching operation of the switching unit 320, and the other end of the converter switch 331 prevents reverse current according to the switching operation of the switching unit 320 It may be connected only to the device 332 or may be connected to the other end of the reverse current prevention device 332 and the inductor 333 together.

The converter switch 331 is a device that determines whether to conduct current through conduction (on state) or non-conduction (off state), and, for example, a MOSFET, which is a semiconductor switch, may be used, but is not limited thereto.

One end of the reverse current preventing element 332 is connected to the ground or connected to the power supply 310 according to the switching operation of the switching unit 320, and the other end of the reverse current preventing element 332 is connected to the other end of the converter switch 331. Connected. Various devices such as diodes and FETs may be used as the reverse current prevention device 332.

One end of the inductor 333 is connected to the other end of the converter switch 331, and the other end of the inductor 333 is connected to the load 10c.

Meanwhile, in the power system 1000c according to the third embodiment of the present invention, a specific circuit in which the first switch 321, the second switch 322, and the third switch 323 of the switching unit 320 are connected. The structure is as follows.

One end of the first switch 321 is connected to the ground, and the other end is provided to be connected to one end of the reverse current preventing element 332 or turned off according to a switching operation controlled by the controller 340. Here, that the other end of the first switch 321 is turned off means that no circuit elements are electrically connected to the other end of the first switch 321.

The second switch 322 has one end connected to the power supply 310 and the other end connected to one end of the converter switch 331 or the reverse current prevention element 332 according to a switching operation controlled by the controller 340. It is prepared to be connected to one end.

The third switch 323 has one end connected to the other end of the inductor 333, and the other end is provided to be turned off according to a switching operation controlled by the controller 340 or connected to the other end of the converter switch 331. Here, that the other end of the third switch 323 is turned off means that no circuit elements are electrically connected to the other end of the third switch 323.

In addition, the other end of the converter switch 331 is a point where the reverse current prevention element 332 and the inductor 333 are connected.

The control unit 340 is a component that controls the MPPT control of the buck converter unit 330 and the switching operation of the switching unit 320. More specifically, the control unit 340 controls the first switch 321, the second switch 322, and the third switch 323 in a first switching mode, and controls the buck converter unit 330 from the power supply unit 310. A first power transfer path through which power is transferred to the load 10c may be formed.

Here, power is transmitted through the buck converter unit 330, since power is transferred from the power supply unit 310 to the load 10c, the voltage output from the power supply unit 310 is stepped down by the buck converter unit 330. It means going through the process of becoming.

In addition, the control unit controls the first switch 321, the second switch 322, and the third switch 323 in the second switching mode, so that the load 10c from the power supply unit 310 without passing through the buck converter unit 330 ) May form a second power transfer path through which power is transferred.

Here, that the power is transmitted without passing through the buck converter unit 330 is that since power is transferred from the power supply unit 310 to the load 10c, the voltage output from the power supply unit 310 is transmitted by the buck converter unit 330. It means not going through the process of being forced to go through.

In addition, the control unit 340 calculates the magnitude of the first power (P1) in the case of transmitting power to the load 10c through the first power transfer path, and transmits power to the load 10c through the second power transfer path. The magnitude of the second power (P2) in the case of transmitting is calculated. Thereafter, the controller 340 compares the calculated magnitude P1 of the first power and the magnitude P2 of the second power, and controls the switching operation of the switching unit 320 according to the comparison result.

At this time, if the comparison result is the case where the magnitude of the first power (P1) is greater than or equal to the magnitude of the second power (P2), the first switch 321, the second switch 322, and the 3 If the switch 323 is controlled in the first switching mode, and the comparison result is a case where the magnitude of the first power (P1) is less than the magnitude of the second power (P2), the first switch 321 and the second switch Control 322 and the third switch 323 in the second switching mode.

Here, the first power is power transferred from the power supply unit 310 to the load 10c when the control unit 340 controls the buck converter unit 330 MPPT, and the second power is the control unit 340 When MPPT control 330 is not performed, this is the power transferred from the power supply unit 310 to the load 10c.

The first power level P1 may be calculated by the control unit 340 using the MPPT algorithm by receiving values of the open-circuit voltage V1 and the short-circuit current I1 of the output terminal of the power supply unit 310.

When the control unit 340 receives the current voltage V2 of the load 10c and the current voltage V2 of the load 10c is applied to the power supply 310, the second power level P2 is determined by the power supply unit 310. It can be calculated by calculating the value of the power output from. Alternatively, the magnitude P2 of the second power may be calculated by the controller 340 receiving the current voltage V2 of the load 10c and the current I2 flowing through the load 10c.

According to the third embodiment of the present invention, the control unit 340 compares the magnitude of the first power (P1) and the magnitude of the second power (P2), and 2 Since it is configured to select a path having a higher power transfer efficiency to the load 10c among the power transfer paths in real time, the power transfer efficiency to the load 10c can be maximized.

The power system 1000c according to the third embodiment of the present invention may further include an input side storage unit 350 that stores an input voltage by power generated from the power supply unit 310. In this case, the input-side storage unit 350 may be connected between the power supply unit 310 and the buck converter unit 330. The input-side storage unit 350 serves to supply a stable DC voltage to the buck converter unit 330 when noise or voltage fluctuates in the input voltage output from the power supply unit 310, and the input-side storage unit 350 As the furnace, a capacitor may be used.

In addition, the power system 1000c according to the third embodiment of the present invention may further include an output side storage unit 360 that stores a voltage stepped down by the buck converter unit 330. In this case, the output-side storage unit 360 may be connected between the buck converter unit 330 and the load 10c. The output-side storage unit 360 serves to rectify a voltage to supply a DC voltage to the load 10c, and a capacitor may be used as the output-side storage unit 360.

10A is a diagram illustrating an equivalent circuit when the power system of FIG. 9 operates in a first switching mode, and FIG. 10B is a diagram illustrating an equivalent circuit when the power system of FIG. 9 operates in a second switching mode. Hereinafter, the first switching mode and the second switching mode will be described in more detail with reference to FIGS. 10A and 10B.

First, referring to FIG. 10A, power generated by the power supply unit 310 is transmitted to a first power transmission path transmitted to the load 10c through the buck converter unit 330. The control unit 340 follows the maximum power by controlling the buck converter unit 330 by MPPT control, stepping down the voltage output from the power supply unit 310 and transferring the voltage to the load 10c.

Specifically, in the first switching mode forming the first power transmission path, when the magnitude of the first power (P1) is greater than or equal to the magnitude of the second power (P2), the other end of the first switch 321 is This mode is connected to one end of the reverse current prevention element 332, the other end of the second switch 322 is connected to one end of the converter switch 331, and the other end of the third switch 323 is turned off.

When the magnitude of the first power (P1) is greater than or equal to the magnitude of the second power (P2), it means that more power is delivered to the load 10c when the buck converter unit 330 is MPPT controlled. The 340 MPPT controls the buck converter unit 330. At this time, the controller 340 connects the other end of the first switch 321 to one end of the reverse current preventing element 332 so that one end of the reverse current preventing element 332 is connected to the ground, and The other end is connected to one end of the converter switch 331 so that the power supply 310 is connected to the converter switch 331, and the other end of the third switch 323 is turned off so that the converter switch 331 is directly transferred to the load 10c. It blocks the bypass path to which it is connected.

At this time, since the voltage output from the power supply 310 is stepped down so as to deliver the maximum power to the load 10c by the MPPT control of the control unit 340, the maximum power followed by the MPPT control will be delivered to the load 10c. I can.

Here, the MPPT control is performed by the control unit 340 controlling the on/off of the converter switch 331 according to the duty ratio determined by the MPPT algorithm.

More specifically, while the control unit 340 turns on the converter switch 331, an input current flows in the dotted line direction of FIG. 10A, energy is charged to the inductor 333, and power is transferred to the load 10c. Here, the input current is a current constituting power generated from the power supply unit 310 and refers to a current flowing from the power supply unit 310 to the buck converter unit 330. Thereafter, when the controller 340 turns off the converter switch 331, current flows in the solid line direction of FIG. 10B, and energy stored in the inductor 333 is released. In this way, when the on-off operation of the converter switch 331 is alternately repeated, the input voltage output from the power supply unit 310 is stepped down and transmitted to the load 10c.

Next, referring to FIG. 10B, power generated by the power supply unit 310 is transmitted to the load 10c through only the reverse current prevention element 332. The control unit 340 does not MPPT control the buck converter unit 330, and controls the voltage generated by the power supply unit 310 to be transmitted to the load 10c without being stepped down. In this case, the power transmitted from the power supply unit 310 to the load 10c is transmitted through the second power transmission path without passing through the buck converter unit 330.

Specifically, in the second switching mode forming the second power transmission path, when the magnitude of the first power is smaller than the magnitude of the second power, the other end of the first switch 321 is turned off, and the second switch ( In this mode, the other end of 322 is connected to one end of the reverse current prevention element 332 and the other end of the third switch 323 is connected to the other end of the converter switch 331.

When the magnitude of the first power (P1) is smaller than the magnitude of the second power (P2), it means that more power is transmitted to the load 10c when the buck converter unit 330 is not MPPT controlled. The 340 does not MPPT control the buck converter unit 330. At this time, the control unit 340 turns off the other end of the first switch 321 and at the same time, the other end of the second switch 322 is connected to one end of the reverse current prevention element 332 to prevent a reverse current from the power supply unit 310 ( 332), let the current flow directly. In addition, the control unit 340 connects the other end of the third switch 323 to the other end of the converter switch 331, thereby bypassing the inductor 333 from the converter switch 331 and directly connected to the load 10c. Form a path

When the second power transmission path is formed, the current voltage of the load 10c is applied to the power supply unit 310. Here, that the voltage of the load 10c is applied to the power supply 310 means that a voltage equal to the voltage difference between the voltage of the load 10c and the voltage across the reverse current prevention element 332 is applied to the power supply 310, at this time The current output from the power supply 310 flows in the direction of an arrow in FIG. 10B and is transferred to the load 10c as it is only through the reverse current prevention element 332.

When a diode is used as the reverse current prevention element 332, the voltage drop of the diode is about 0.7V, which is a very small value, so most (99% or more) of the power generated by the power supply 310 is applied to the load 10c. Can be delivered.

Alternatively, a field effect transistor (FET) may be used as the reverse current prevention element 332. When the FET is used, the control unit 340 can control the FET on and off, and the reverse current is reduced by the on/off control of the FET. You can prevent it from flowing. In addition, the diode does not theoretically have a voltage drop when the FET is turned on, whereas the diode has a voltage drop even if it is a small amount, so power transfer efficiency to the load 10c may be higher than when a diode is used.

On the other hand, referring to Figure 10a, without controlling the switching unit 320 as in the present invention, simply by keeping the converter switch 331 in the on state, without MPPT control, power is delivered to the load (10c). You can see that you can.

However, if the switching unit 320 is provided as in the third embodiment of the present invention, a bypass path can be formed so that the current output from the power supply unit 310 does not pass through the inductor 333 when operating in the second switching mode. Therefore, a ripple phenomenon that may be caused by the inductor 333 can be prevented in advance.

Meanwhile, the first power transmission path refers to all paths that can be transmitted while being MPPT controlled because power output from the power supply unit 310 is transmitted to the load 10c, and the second power transmission path is performed by the power supply unit 310. Since the output power is transmitted to the load 10c, it means all paths that are transmitted without MPPT control. In addition, the switching unit 320 may have various circuit structures to form the first power transmission path and the second power transmission path.

According to the third embodiment of the present invention, by changing the structure of adding only the switch element without adding a resistor, an inductor, or a capacitor, a path having higher power transfer efficiency among the paths in which MPPT control is performed and the paths in which MPPT control is not performed is provided You can choose to deliver power to the load. Therefore, there is an effect that power can be delivered to the load with higher efficiency than when performing only MPPT control.

Referring to FIG. 11, a power system 1000d according to a fourth embodiment of the present invention includes a power supply unit 410, a buck-boost converter unit 420, and a control unit 430.

The power supply unit 410 is a component that generates power, and may be a solar panel that converts light energy into electrical energy. In this case, the solar panel is a combination of solar cell modules that can convert sunlight into DC power and output it. Can be configured. The solar cell module may be made of a series connection or parallel connection of solar cells, or a combination of series-parallel connection.

11 illustrates a battery for storing DC power as an example of the load 10d, but it may correspond to the load 10d as long as it is a device receiving the DC power.

The buck-boost converter unit 420 may receive an input voltage by power generated from the power supply unit 410, and may boost or decrease the input voltage to transfer the voltage to the load 10d. Here, the input voltage refers to a voltage constituting power generated from the power supply unit 410 and a voltage applied to the input terminal of the buck-boost converter unit 420. The buck-boost converter unit 420 may include an inductor 421 and a plurality of converter switches S1 to S4.

In the buck-boost converter unit 420, an inductor 421 and a plurality of converter switches S1 to S4 may form an H-bridge.

Electrical energy may be charged in the inductor 421 by an input current output from the power supply unit 410. Here, the input current refers to a current constituting power generated from the power supply unit 410 and a current flowing from the power supply unit 410 to the buck-boost converter unit 420.

Among the plurality of converter switches S1 to S4, the first converter switch S1 is provided between one end of the inductor 421 and the power supply unit 410, and the second converter switch S2 is connected to the other end of the inductor 421. It is provided between the loads 10d. In addition, the third converter switch S3 is provided between one end of the inductor 421 and the ground, and the fourth converter switch S4 is provided between the other end of the inductor 421 and the ground.

Each of the converter switches S1 to S4 is a device that determines whether to conduct current through conduction (on state) or non-conduction (off state), and, for example, a semiconductor switch MOSFET may be used, but is not limited thereto. Does not.

Meanwhile, the buck-boost converter unit 420 may operate as a boost converter that boosts the input voltage depending on how the plurality of converter switches S1 to S4 are controlled, or as a buck converter that steps down the input voltage. It can also work.

For example, in a state in which the first converter switch S1 is always on and the third converter switch S3 is always off, the buck-boost converter unit 420 is connected to the second converter switch S2. The fourth converter switch S4 may operate as a boost converter in which an input voltage is boosted by an on/off alternating operation.

Alternatively, the buck-boost converter unit 420 operates in a state in which the second converter switch S2 is always on and the fourth converter switch S4 is always off, the first converter switch S1 and the third It can also operate as a buck converter in which the input voltage is stepped down by an on/off alternating operation of the converter switch S3.

The control unit 430 is a component that controls the buck-boost converter unit 420, and specifically controls the buck-boost converter unit 420 by MPPT control so that the input voltage output from the power supply unit 410 is the buck-boost converter unit 420 ) To form a first power transfer path that is transferred to the load 10d through a process of boosting.

Alternatively, the control unit 430 MPPT controls the buck-boost converter unit 420 to transfer the input voltage output from the power supply unit 410 to the load 10d through a step-down process by the buck-boost converter unit 420 It is possible to form a second power transmission path.

Alternatively, the control unit 430 does not MPPT control the buck-boost converter unit 420, and the input voltage output from the power supply unit 410 is boosted and stepped down by the buck-boost converter unit 420 without going through the load. It is possible to form a third power transmission path delivered to (10d).

More specifically, the control unit 430 calculates the magnitude P1 of the first power in the case of transmitting power to the load 10d through the first power transfer path, and the load 10d through the third power transfer path. In the case of transferring power to, the magnitude of the third power (P3) may be calculated. Thereafter, the controller 430 compares the calculated magnitude P1 of the first power and the magnitude P3 of the third power, and according to the comparison result, a plurality of converter switches of the buck-boost converter unit 420 ( On/off of S1~S4) can be controlled.

Here, the first power is power transferred from the power supply unit 410 to the load 10d when the control unit 430 controls the MPPT while operating the buck-boost converter unit 420 as a boost converter, and the third power is the control unit ( When 430 does not MPPT control the buck-boost converter unit 420, this is the power transferred from the power supply unit 410 to the load 10d.

The first power level P1 may be calculated by the control unit 430 using the MPPT algorithm by receiving values of the open-circuit voltage V1 and the short-circuit current I1 of the output terminal of the power supply unit 410.

The third power level P3 may be calculated by receiving the current voltage V2 of the load 10d and the current I2 flowing through the load 10d by the control unit 430.

According to the fourth embodiment of the present invention, the controller 430 compares the magnitude of the first power (P1) and the magnitude of the third power (P3), and according to the comparison result, the first power transfer path and the third power Since it is configured to select a path having a higher power transfer efficiency to the load 10d among the transfer paths in real time, the power transfer efficiency to the load 10d can be maximized.

On the other hand, the control unit 430 calculates the magnitude of the second power (P2) in the case of transmitting power to the load 10d through the second power transfer path, and transmits power to the load 10d through the third power transfer path. It is possible to calculate the magnitude P3 of the third power in the case of delivering. Thereafter, the control unit 430 compares the calculated magnitude P2 of the second power and the magnitude P3 of the third power, and according to the comparison result, a plurality of converter switches of the buck-boost converter unit 420 ( S1~S4) can be controlled.

Here, the second power is power transferred from the power supply unit 410 to the load 10d when the control unit 430 controls the MPPT while operating the buck-boost converter unit 420 as a buck converter, and the third power is the control unit ( When 430 does not MPPT control the buck-boost converter unit 420, this is the power transferred from the power supply unit 410 to the load 10d.

The second power level P2 may be calculated by the control unit 430 using the MPPT algorithm by receiving values of the open-circuit voltage V1 and the short-circuit current I1 of the output terminal of the power supply unit 410.

As described above, according to the fourth embodiment of the present invention, the controller 430 compares the magnitude of the second power (P2) and the magnitude of the third power (P3), and Since it is configured to select a path having a higher power transfer efficiency to the load 10d among the 3 power transfer paths in real time, the power transfer efficiency to the load 10d can be maximized.

The power system 1000d according to the fourth embodiment of the present invention may further include an input side storage unit 440 for storing an input voltage by power generated from the power supply unit 410. In this case, the input-side storage unit 440 may be connected between the power supply unit 410 and the buck-boost converter unit 420. The input-side storage unit 440 serves to supply a stable DC voltage to the buck-boost converter unit 420 when noise or voltage fluctuates in the input-side voltage output from the power supply unit 410, and the input-side storage unit ( As 440), a capacitor may be used.

In addition, the power system 1000d according to the fourth embodiment of the present invention may further include an output side storage unit 450 that stores a voltage boosted or stepped down by the buck-boost converter unit 420. In this case, the output-side storage unit 450 may be connected between the buck-boost converter unit 420 and the load 10d. The output-side storage unit 450 serves to rectify a voltage to supply a DC voltage to the load 10d, and a capacitor may be used as the output-side storage unit 450.

FIG. 12A is a diagram illustrating a case in which a first power transmission path is formed in the power system of FIG. 11, FIG. 12B is a diagram illustrating a case in which a second power transmission path is formed in the power system of FIG. 11, and FIG. 12C is A diagram showing a case in which a third power transmission path is formed in the power system of 11. Hereinafter, an operation process of the power system 1000d according to the fourth embodiment of the present invention will be described in more detail with reference to FIGS. 12A, 12B, and 12C.

First, referring to FIG. 12A, the first power transmission path is the power formed when the input voltage output from the power supply unit 410 is boosted by the buck-boost converter unit 420 and is transferred to the load 10d. It is a delivery path. That is, at this time, the buck-boost converter unit 420 operates as a boost converter.

The controller 430 forms a first power transmission path when the first power level P1 is greater than or equal to the third power level P3. Here, that the magnitude of the first power (P1) is greater than or equal to the magnitude of the third power (P3) means that more power is delivered to the load (10d) when the buck-boost converter unit 420 is MPPT controlled. Therefore, the control unit 430 boosts the voltage output from the power supply unit 410 while MPPT control of the buck-boost converter unit 420 and transfers it to the load 10d.

At this time, the control unit 430 sets the second converter switch S2 and the fourth converter switch S4 to the duty according to the MPPT algorithm in a state in which the first converter switch S1 is turned on and the third converter switch S3 is turned off. On/off control is performed alternately according to the ratio.

More specifically, while the second converter switch S2 is operated in OFF and the fourth converter switch S4 is operated in ON, an input current flows in the dotted line direction of FIG. 5A to charge energy in the inductor 421, While the second converter switch (S2) is operating in ON and the fourth converter switch (S4) is operating in off state, the input current flows in the direction of the solid line in FIG. As the input current is simultaneously transferred to the load 10d, the input voltage is boosted.

Since the input voltage output from the power supply unit 410 is boosted to deliver the maximum power to the load 10d by the MPPT control of the control unit 430, the maximum power followed by the MPPT control will be delivered to the load 10d. I can.

Next, referring to FIG. 12B, the second power transmission path is formed when the input voltage output from the power supply unit 410 is stepped down by the buck-boost converter unit 420 and is transferred to the load 10d. It is a power transmission path. That is, at this time, the buck-boost converter unit 420 operates as a buck converter.

The controller 430 forms a second power transmission path when the magnitude of the second power P2 is greater than or equal to the magnitude of the third power P3. Here, that the magnitude of the second power (P2) is greater than or equal to the magnitude of the third power (P3) means that more power is delivered to the load (10d) when the buck-boost converter unit 420 is MPPT controlled. Therefore, while controlling the buck-boost converter unit 420 to MPPT, the control unit 430 steps down the voltage output from the power supply unit 410 and transfers it to the load 10d.

At this time, in a state in which the second converter switch S2 is turned on and the fourth converter switch S4 is turned off, the control unit 430 sets the duty of the first converter switch S1 and the third converter switch S3 according to the MPPT algorithm. On/off control is performed alternately according to the ratio.

More specifically, while the first converter switch S1 is on and the third converter switch S3 is off, the inductor 421 is charged with energy while the input current flows in the dotted line direction of FIG. 12B. Electric power is delivered to the load 10d. Thereafter, while the first converter switch S1 is turned off and the third converter switch S3 is turned on, a current flows in the solid line direction of FIG. 12B to discharge energy stored in the inductor 421. As the on-off operation of the first converter switch S1 and the third converter switch S3 is alternately repeated, the input voltage output from the power supply unit 410 is stepped down and transmitted to the load 10d.

The input voltage output from the power supply unit 410 is stepped down so that the maximum power can be delivered to the load 10d by the MPPT control of the control unit 430, so that the maximum power followed by the MPPT control will be delivered to the load 10d. I can.

Next, referring to FIG. 12C, the third power transfer path is to be transferred to the load 10d without going through the process of boosting and stepping down the input voltage output from the power supply unit 410 by the buck-boost converter unit 420. It is the power transmission path that is formed when. That is, at this time, the buck-boost converter unit 420 does not operate as a converter.

The control unit 430 provides the third power when the first power P1 is smaller than the third power P3 or the second power P2 is smaller than the third power P3. It forms a delivery path. Here, when the magnitude of the first power (P1) or the magnitude of the second power (P2) is smaller than the magnitude of the third power (P3), the load 10d when the buck-boost converter unit 420 is not MPPT controlled. ) Means more power is delivered. Accordingly, the control unit 430 does not MPPT the buck-boost converter unit 420 but controls the buck-boost converter unit 420 so that the voltage output from the power supply unit 410 is transmitted to the load 10d as it is.

At this time, the control unit 430 turns on the first converter switch S1 and the second converter switch S2, and turns off the third converter switch S3 and the fourth converter switch S4.

In the case of forming the third power transmission path, the current load 10d voltage is applied to the power supply unit 410, and the power is directly transmitted without switching loss, core loss, and/or conduction loss by the buck-boost converter unit 420. It is supplied to the load 10d. For reference, when the third power transmission path is formed, since a DC voltage is applied to the inductor 421, the inductor 421 operates like a short circuit, and thus, core loss due to the inductor 421 does not occur. Here, that the voltage of the load 10d is applied to the power supply unit 410 means that the value of the voltage of the load 10d is applied to the power supply unit 410 as it is. That is, the current output from the power supply unit 410 flows in the solid line direction of FIG. 12C and is transmitted to the load 10d as it is only through the inductor 421.

The control method of the power system according to the fourth embodiment of the present invention may be performed by the controller 430.

First, the control unit 430 transmits power to the load 10d through the first power transfer path and the first power amount P1 when power is transferred to the load 10d through the first power transfer path. The magnitude P3 of the third power in the case is calculated (S411).

In this case, the first power transfer path is a power transfer path formed when the input voltage output from the power supply unit 10 is boosted by the buck-boost converter unit 420 and is transferred to the load 10d. That is, at this time, the buck-boost converter unit 420 operates as a boost converter.

As described above, the first power is power transferred from the power supply unit 410 to the load 10d when the control unit 430 controls the MPPT while operating the buck-boost converter unit 420 as a boost converter, and the third power When the control unit 430 does not MPPT control the buck-boost converter unit 420, is power transferred from the power supply unit 410 to the load 10d.

However, it is also possible to directly calculate the magnitude of the first power (P1) and the magnitude of the third power (P3) through sensing the voltage at the output terminal of the power supply unit 410, the voltage of the load 10d, and current. Through the method, the magnitude of the first power (P1) and the magnitude of the third power (P3) may be calculated.

Accordingly, a method of calculating the magnitude of the first power P1 and the magnitude of the third power P3 is not limited, and it should be understood that all other computation methods are included.

Next, the controller 430 compares the magnitude of the first power (P1) and the magnitude of the third power (P3) (S412), and then, according to the comparison result, the controller 430 performs a first converter switch ( S1), the second converter switch S2, the third converter switch S3, and the fourth converter switch S4 are controlled (S413).

Specifically, when the magnitude of the first power P1 is greater than or equal to the magnitude of the third power P3, the controller 430 performs the step of forming a first power transmission path (S413-1).

When the magnitude of the first power P1 is greater than or equal to the magnitude of the third power P3, it means that more power is delivered to the load 10d when the buck-boost converter unit 420 is MPPT controlled. . Accordingly, the control unit 430 boosts the voltage output from the power supply unit 410 while MPPT control of the buck-boost converter unit 420 and transfers it to the load 10d.

More specifically, while the second converter switch S2 is turned off and the fourth converter switch S4 is turned on, an input current flows through the inductor 421 to charge energy in the inductor 421. Thereafter, while the second converter switch S2 is turned on and the fourth converter switch S4 is turned off, the energy charged in the inductor 421 and the input current output from the power supply unit 410 are simultaneously applied to the load 10d. As it is transferred to, the input voltage is boosted.

At this time, since the input voltage output from the power supply unit 410 is boosted to deliver the maximum power to the load 10d by the MPPT control of the control unit 430, the maximum power followed by the MPPT control is transferred to the load 10d. Can be.

Although mentioned above, various algorithms such as the P&O method and the InCond method are known as the MPPT algorithm, and among these various MPPT algorithms for MPPT control mentioned in the power system control method according to the fourth embodiment of the present invention. Either can be used.

When the magnitude of the first power P1 is smaller than the magnitude of the third power P3, the controller 430 performs the step of forming a third power transmission path (S413-2).

When the magnitude of the first power P1 is smaller than the magnitude of the third power P3, it means that more power is delivered to the load 10d when the buck-boost converter unit 420 is not MPPT controlled. . Accordingly, the control unit 430 does not MPPT the buck-boost converter unit 420 but controls the buck-boost converter unit 420 so that the voltage output from the power supply unit 410 is transmitted to the load 10d as it is.

In the case of forming the third power transmission path, the current load 10d voltage is applied to the power supply unit 410, and the power is directly transmitted without switching loss, core loss, and/or conduction loss by the buck-boost converter unit 420. It is supplied to the load 10d. At this time, since a DC voltage is applied to the inductor 421, the inductor 421 operates like a short circuit, and thus, core loss due to the inductor 421 does not occur. Here, that the voltage of the load 10d is applied to the power supply unit 410 means that the value of the voltage of the load 10d is applied to the power supply unit 410 as it is. That is, the current output from the power supply unit 410 is transferred to the load 10d as it is through only the inductor 421.

Meanwhile, FIG. 13B is another flowchart illustrating a method of controlling the power system of FIG. 11.

Another embodiment of the control method of the power system according to the fourth embodiment of the present invention may also be performed by the controller 430.

First, the control unit 430 transmits power to the load 10d through the second power transfer path and the second power amount P2 when power is transferred to the load 10d through the second power transfer path. The magnitude P3 of the third power in the case is calculated (S421).

In this case, the second power transfer path is a power transfer path formed when the input voltage output from the power supply unit 10 is stepped down by the buck-boost converter unit 420 and is transferred to the load 10d. That is, at this time, the buck-boost converter unit 420 operates as a buck converter.

Next, the controller 430 compares the magnitude of the second power (P2) and the magnitude of the third power (P3) (S422), and then, according to the comparison result, the controller 430 performs a first converter switch ( S1), the second converter switch S2, the third converter switch S3, and the fourth converter switch S4 are controlled (S423).

Specifically, when the magnitude of the second power P2 is greater than or equal to the magnitude of the third power P3, the controller 430 performs the step of forming a second power transmission path (S423-1).

When the magnitude of the second power P2 is greater than or equal to the magnitude of the third power P3, it means that more power is delivered to the load 10d when the buck-boost converter unit 420 is MPPT controlled. . Accordingly, the control unit 430 MPPT controls the buck-boost converter unit 420 to step down the voltage output from the power supply unit 410 and transfer it to the load 10d.

More specifically, while the first converter switch S1 is on and the third converter switch S3 is off, energy is charged to the inductor 421 and power is transferred to the load 10d. Energy stored in the inductor 421 is discharged while the first converter switch S1 is turned off and the third converter switch S3 is turned on. As the on-off operation of the first converter switch S1 and the third converter switch S3 is alternately repeated, the input voltage output from the power supply unit 410 is stepped down and transmitted to the load 10d.

At this time, since the input voltage output from the power supply unit 410 is stepped down to deliver the maximum power to the load 10d by the MPPT control of the control unit 430, the maximum power followed by the MPPT control is transmitted to the load 10d. Can be.

When the magnitude of the second power P2 is smaller than the magnitude of the third power P3, the controller 430 performs a step of forming a third power transmission path (S423-2).

That the second power P2 is smaller than the third power P3 means that more power is delivered to the load 10d when the buck-boost converter unit 420 is not MPPT controlled. . Accordingly, the control unit 430 does not MPPT the buck-boost converter unit 420 but controls the buck-boost converter unit 420 so that the voltage output from the power supply unit 410 is transmitted to the load 10d as it is.

In the case of forming the third power transmission path, the current load 10d voltage is applied to the power supply unit 410, and the power is directly transmitted without switching loss, core loss, and/or conduction loss by the buck-boost converter unit 420. It is supplied to the load 10d. At this time, since a DC voltage is applied to the inductor 421, the inductor 421 operates like a short circuit, and thus, core loss due to the inductor 421 does not occur.

Meanwhile, that the voltage of the load 10d is applied to the power supply unit 410 means that the value of the voltage of the load 10d is applied to the power supply unit 410 as it is. That is, the current output from the power supply unit 410 is transferred to the load 10d as it is through only the inductor 421.

The control method of the first converter switch S1, the second converter switch S2, the third converter switch S3, and the fourth converter switch S4 is a path for transferring power to the load 10d by MPPT control or In order to select a path for transmitting power to the load 10d without performing MPPT control, it can be controlled in various ways other than the above-described control method, and the fourth embodiment of the present invention includes all of these various control methods. .

According to the fourth embodiment of the present invention, MPPT is achieved by changing only the control method of the converter switches S1 to S4 of the buck-boost converter unit 420 without adding additional elements to the existing power system circuit structure. Among the paths in which the control is performed and the paths in which MPPT control is not performed, a path having higher power transfer efficiency to the load 10d may be selected to deliver power to the load. Therefore, there is an effect that power is delivered to the load with higher efficiency than when only MPPT control is performed.

In addition, in the case of the H-bridge type buck-boost converter used in the fourth embodiment of the present invention, a FET is generally used as the converter switches S1 to S4. When forming the third power transfer path, a diode Since power loss is less than when using a DC-DC converter with a device, the power transfer efficiency can be higher.

As described above, although the present invention has been described by limited embodiments and drawings, the present invention is not limited to the above-described embodiments, and various modifications and variations are made from these descriptions to those of ordinary skill in the field to which the present invention pertains. It is possible. Therefore, the technical idea of the present invention should be grasped only by the claims, and all equivalent or equivalent modifications thereof will be said to belong to the scope of the technical idea of the present invention.

Claims

A power supply for generating electric power;

A boost converter unit for boosting an input voltage by power generated from the power unit and transferring it to a load; And

A control unit for controlling the boost converter unit to form a first power transmission path or a second power transmission path for transferring the power from the power supply unit to the load; and

When the first power transmission path is formed by the control unit, the input voltage is transferred to the load through a process of boosting by the boost converter unit,

When the second power transmission path is formed by the control unit, the input voltage is transmitted to the load without going through a process of being boosted by the boost converter unit.
The method of claim 1,

The boost converter unit,

An inductor having one end connected to the power supply and charged by the current output from the power supply;

A reverse current prevention element preventing reverse current from flowing from the load to the inductor; And

A converter switch having one end connected between the other end of the inductor and the reverse current preventing element, and the other end connected to the ground.
The method of claim 2,

The control unit,

Calculate the magnitude of the first power when power is delivered to the load through the first power transfer path, and the magnitude of the second power when power is transferred to the load through the second power transfer path And controlling the converter switch according to a result of comparing the magnitude of the first power and the magnitude of the second power,

As a result of the comparison, when the magnitude of the first power is greater than or equal to the magnitude of the second power, the converter switch is turned on and off according to a duty ratio determined by a maximum power point tracking (MPPT) algorithm to control the first power. Form a delivery path,

As a result of the comparison, when the magnitude of the first power is smaller than the magnitude of the second power, the converter switch is turned off to form the second power transmission path.
A power supply for generating electric power;

A switching unit for selecting a power transmission path through which the power generated by the power unit is transmitted to the load;

A boost converter unit that boosts an input voltage by power generated from the power unit and transfers it to the load; And

Includes; a control unit for controlling the switching operation of the switching unit,

The switching unit includes a first switch and a second switch,

The control unit,

Controlling the first switch and the second switch in a first switching mode to form a first power transfer path through which power is transferred from the power supply to the load through the boost converter,

And controlling the first switch and the second switch in a second switching mode to form a second power transmission path through which power is transmitted from the power supply to the load without passing through the boost converter.
The method of claim 4,

The boost converter unit,

An inductor whose one end is connected to or disconnected from the power supply unit according to a switching operation of the switching unit;

A converter switch connected to the other end of the inductor or connected to the power supply according to a switching operation of the switching unit; And

And a reverse current prevention element for preventing reverse current from flowing from the load to the inductor.
The method of claim 5,

The first switch has one end connected to the power supply, and the other end connected to one end or an open terminal of the inductor according to a switching operation controlled by the control unit,

Wherein the second switch has one end connected to the converter switch and the reverse current preventing element, and the other end connected to the power supply unit or the other end of the inductor according to a switching operation controlled by the control unit.
The method of claim 6,

The control unit,

Calculate a magnitude of first power when power is delivered to the load through the first power transfer path, and calculate a magnitude of second power when power is delivered to the load through the second power transfer path, Comparing the magnitude of the first power and the magnitude of the second power,

As a result of the comparison, when the first power is greater than or equal to the second power, the second end of the first switch is connected to one end of the inductor, and the other end of the second switch is connected to the other end of the inductor. 1 controlled by switching mode,

As a result of the comparison, when the first power is less than the second power, the second switching mode is controlled in which the other end of the first switch is connected to the open terminal and the other end of the second switch is connected to the power supply. Power system, characterized in that.
The method of claim 7,

The control unit,

When controlling the switching unit in the first switching mode, MPPT control of the boost converter unit,

When controlling the switching unit in the second switching mode, the boost converter unit is operated to turn off the converter switch without MPPT control.
A power supply for generating electric power;

A switching unit for selecting a power transmission path through which the power generated by the power unit is transmitted to the load;

A buck converter unit stepping down an input voltage due to power generated from the power supply unit and transferring it to the load; And

Includes; a control unit for controlling the switching operation of the switching unit,

The switching unit includes a first switch, a second switch and a third switch,

The control unit,

Controlling the first switch, the second switch, and the third switch in a first switching mode to form a first power transfer path through which power is transferred from the power supply to the load through the buck converter,

Power, characterized in that by controlling the first switch, the second switch, and the third switch in a second switching mode to form a second power transfer path through which power is transferred from the power supply to the load without passing through the buck converter. system.
The method of claim 9,

The buck converter unit,

A converter switch whose one end is connected to or disconnected from the power supply according to a switching operation of the switching unit;

A reverse current prevention element having one end connected to the ground or connected to the power supply according to a switching operation of the switching unit, and the other end connected to the other end of the converter switch; And

Power system comprising: an inductor having one end connected to the other end of the converter switch and the other end connected to the load.
The method of claim 10,

The first switch, one end is connected to the ground, the other end is connected or turned off to one end of the reverse current preventing element according to a switching operation of the switching unit controlled by the control unit,

The second switch, one end is connected to the power supply, the other end is connected to one end of the converter switch or connected to one end of the reverse current prevention element according to the switching operation of the switching unit controlled by the control unit,

Wherein the third switch has one end connected to the other end of the inductor, and the other end is turned off according to a switching operation of the switching unit controlled by the control unit or connected to the other end of the converter switch.
The method of claim 11,

The control unit,

Calculate a magnitude of first power when power is delivered to the load through the first power transfer path, and calculate a magnitude of second power when power is delivered to the load through the second power transfer path, Comparing the magnitude of the first power and the magnitude of the second power,

As a result of the comparison, when the magnitude of the first power is greater than or equal to the magnitude of the second power, the other end of the first switch is connected to one end of the reverse current preventing element, and the other end of the second switch is connected to the converter. Connected to one end of the switch and controlled in the first switching mode to turn off the other end of the third switch,

As a result of the comparison, when the magnitude of the first power is smaller than the magnitude of the second power, the other end of the first switch is turned off, the other end of the second switch is connected to one end of the reverse current prevention element, and the And controlling the second switching mode in which the other end of the third switch is connected to the other end of the converter switch.
The method of claim 12,

The control unit,

When controlling the switching unit in the first switching mode, MPPT control of the buck converter unit,

When controlling the switching unit in the second switching mode, the buck converter unit does not MPPT control.
A power supply for generating electric power;

A buck-boost converter unit for boosting or stepping down an input voltage by power generated from the power supply unit and transferring it to a load; And

And a controller configured to form a first power transfer path, a second power transfer path, or a third power transfer path for transferring power from the power supply to the load by controlling the buck-boost converter,

When the first power transmission path is formed by the controller, the input voltage is boosted by the buck-boost converter and transferred to the load,

When the second power transmission path is formed by the control unit, the input voltage is transmitted to the load through a step-down process by the buck-boost converter unit,

When the third power transmission path is formed by the control unit, the input voltage is transmitted to the load without going through a process of stepping up and stepping down by the buck-boost converter unit.
The method of claim 14,

The buck-boost converter unit,

An inductor charged by the current output from the power supply unit;

A first converter switch provided between one end of the inductor and the power supply unit;

A second converter switch provided between the other end of the inductor and the load;

A third converter switch provided between one end of the inductor and a ground; And

And a fourth converter switch provided between the other end of the inductor and the ground.
The method of claim 15,

The control unit,

Calculate the magnitude of first power when power is delivered to the load through the first power transfer path, and calculate the magnitude of third power when power is delivered to the load through the third power transfer path And controlling the first converter switch, the second converter switch, the third converter switch, and the fourth converter switch according to a result of comparing the magnitude of the first power and the magnitude of the third power,

As a result of the comparison, when the magnitude of the first power is greater than or equal to the magnitude of the third power, the buck-boost converter unit controls the MPPT to form the first power transfer path,

As a result of the comparison, when the magnitude of the first power is smaller than the magnitude of the third power, the buck-boost converter unit forms the third power transmission path without MPPT control.
The method of claim 16,

The control unit,

As a result of the comparison, when the magnitude of the first power is greater than or equal to the magnitude of the third power, the first converter switch is turned on and the third converter switch is turned off to form the first power transmission path. And boosting the input voltage by alternately controlling the on-off operation of the second converter switch and the fourth converter switch according to a duty ratio according to an MPPT algorithm,

As a result of the comparison, when the magnitude of the first power is smaller than the magnitude of the third power, in order to form the third power transmission path, the first converter switch and the second converter switch are turned on, and the The power system, characterized in that turning off the three converter switch and the fourth converter switch.
The method of claim 15,

The control unit,

Calculate the magnitude of the second power when power is delivered to the load through the second power transfer path, and the magnitude of the third power when power is delivered to the load through the third power transfer path And controlling the first converter switch, the second converter switch, the third converter switch, and the fourth converter switch according to a result of comparing the magnitude of the second power and the magnitude of the third power,

As a result of the comparison, when the magnitude of the second power is greater than or equal to the magnitude of the third power, the buck-boost converter unit controls the MPPT to form the second power transfer path,

As a result of the comparison, when the magnitude of the second power is smaller than the magnitude of the third power, the buck-boost converter unit forms the third power transmission path without MPPT control.
The method of claim 18,

The control unit,

As a result of the comparison, when the magnitude of the second power is greater than or equal to the magnitude of the third power, the second converter switch is turned on and the fourth converter switch is turned off to form the second power transmission path. And, by alternately controlling the on-off operation of the first converter switch and the third converter switch according to a duty ratio according to the MPPT algorithm to step down the input voltage,

As a result of the comparison, when the magnitude of the second power is smaller than the magnitude of the third power, in order to form the third power transmission path, the first converter switch and the second converter switch are turned on, and the second power The power system, characterized in that turning off the three converter switch and the fourth converter switch.