KR102175583B1 - Resonant converter including power network with passive devices - Google Patents

Abstract

The embodiments include a load unit including a load whose load range varies; In a power conversion system including a power supply source for supplying power to the load, it relates to a resonant converter disposed between the power supply source and the load unit. The resonant converter may include a power network for transferring power from the power supply source to a load unit; An inverter unit disposed between the power supply source and a power network; And a rectifier disposed between the power network and the load unit.

Description

Resonant converter including a power network made of passive elements {RESONANT CONVERTER INCLUDING POWER NETWORK WITH PASSIVE DEVICES}

The present invention relates to a power network applied to a resonant converter, and more particularly, to a four-terminal network made of passive elements, which contributes to optimization such as improvement of power factor of the resonant converter when applied to a resonant converter.

The transformer is the most representative device for converting impedance. When a transformer is used, the load impedance viewed from the power supply source changes as shown in the following equation according to the coil turns ratio.

[Equation 1]

However, as can be seen from the above equation, when a transformer is used, since the real component (R _L ) and the imaginary component (X _L ) of the load impedance are converted at the same ratio, converting an arbitrary load impedance into a specific impedance required by the system is impossible.

In order to overcome this, there is an attempt to use a power network made of passive elements. However, the power network can be modeled with various combinations of passive elements, and the number of possible combinations increases exponentially with the number of passive elements. For example, the number of combinations composed of two passive elements is two, but the number of combinations composed of four passive elements reaches 182.

Therefore, in the case of applying a power network composed of passive elements to a resonant converter, it is mainly driven at a single optimum frequency, and if it is designed to satisfy a wide input voltage range, in view of the characteristics of a resonant converter that is good only under rated conditions. There is a limit that makes it practically impossible to experiment with numerous combinations individually.

Patent Publication No. 10-2018-0058003

According to an embodiment of the present invention, when applied to a resonant converter, a resonant converter having a four-terminal network made of passive elements may be provided that contributes to optimization such as improvement of the power factor of the resonant converter.

A resonant converter applied to a power conversion system having a power supply source and a load according to an aspect of the present invention transmits power from the power supply source to a load, and includes a power network comprising a passive element; An inverter unit disposed between the power supply source and a power network; And a rectifier disposed between the power network and the load.

In one embodiment, the power network may include a first network impedance, a second network impedance, a third network impedance, and a fourth network impedance.

In one embodiment, the imaginary component of each network impedance is each expressed as follows,

Here, X ₁₁ is the imaginary component of the first network impedance, X ₂₂ is the imaginary component of the fourth network impedance, X ₁₂ is the imaginary component of the second network impedance, and X _in and R _in are the input impedance viewed from the power source. Indicate the components, R _L represents the real component of the load impedance, and R _L,crit represents the value of R _L that makes R _in the maximum when R _L fluctuates.

In one embodiment, the power network may be modeled as a T-type equivalent circuit, and the T-type equivalent circuit includes: a first equivalent impedance and a second equivalent impedance arranged in series between an input terminal and an output terminal of the power network; And a third equivalent impedance extending from a node between the first equivalent impedance and the second equivalent impedance and connected in parallel with the first equivalent impedance and the second equivalent impedance, and the imaginary component of the first equivalent impedance is X ₁₁ -X ₁₂ , the imaginary component of the second equivalent impedance is represented by X ₂₂ -X ₁₂ , and the imaginary component of the third equivalent impedance is represented by X ₁₂ .

In one embodiment, the power network is configured such that the equivalent impedances of the T-type equivalent circuit satisfy the following equation,

Here, X ₁ represents the imaginary component of the first equivalent impedance, X ₂ represents the imaginary component of the second equivalent impedance, and X ₃ represents the imaginary component of the third equivalent impedance.

In one embodiment, the power network includes: a first capacitor and a second capacitor disposed in series between an input terminal and an output terminal of the power network; A first inductor disposed between the first capacitor and the second capacitor; And a second inductor extending from a node between the first inductor and the second capacitor and connected in parallel with the first inductor and the second capacitor.

In one embodiment, when the power conversion system is configured to vary the input voltage input to the power network according to the frequency, the power network is designed to have an optimized power factor value at the first frequency f ₀ or the second frequency f ₁ Can be.

In one embodiment, the optimized power factor value of the resonant converter may be 0.9 to 1.

In one embodiment, the power network is further configured to satisfy the following equation at the first frequency,

Where X _{11_0} is the imaginary component of the first network impedance at the first frequency, X _{12_0} is the imaginary component of the second network impedance at the first frequency, X _{22_0} is the imaginary component of the fourth network impedance at the first frequency, and R _{L_0} is It represents the real component of the load impedance at the first frequency.

In one embodiment, the power network is further configured to satisfy the following equation at the second frequency,

Here, X _{11_1} is the imaginary component of the first network impedance at the second frequency, X _{12_1} is the imaginary component of the second network impedance at the second frequency, X _{22_1} is the imaginary component of the fourth network impedance at the second frequency, and R _{L_1} is It represents the real component of the load impedance at the second frequency.

In one embodiment, the power network may be reciprocal.

In the power network comprising passive elements included in the resonant converter according to an aspect of the present invention, the resonant converter is optimized power factor or power factor within the allowable range of power factor fluctuations despite fluctuations in driving conditions such as load fluctuations or input voltage fluctuations. It is configured to be able to maintain.

In one embodiment, the power network is configured such that the resonant converter can maintain an optimized power factor or a power factor within a power factor fluctuation tolerance, even though the load of the system fluctuates.

In general, a designer designs a resonant converter to have a high power factor, and as a result, the resonant converter according to the present invention may have a high power factor despite variations in driving conditions. For this reason, the entire power conversion system to which the resonant converter is applied can have high efficiency.

In particular, in designing the power network according to the above embodiment, it is possible to design a combination of passive elements optimized for a resonant converter without a case study for each combination. As a result, it is possible to save resources such as time and money that may be consumed in case studies.

In another embodiment, the power network is configured such that the resonant converter is capable of maintaining an optimized power factor or a power factor within a power factor fluctuation tolerance range even though the input voltage of the system fluctuates.

Accordingly, the resonant converter to which the power network 130 is applied may have a high power factor even if the input voltage is changed over a wider range, and thus the rated condition is extended. Consequently, the overall efficiency of the power conversion system including the resonant converter may be improved.

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

In order to more clearly describe the technical solutions of the embodiments of the present invention or prior art, the drawings necessary in the description of the embodiments are briefly introduced below. It is to be understood that the following drawings are for the purpose of describing the embodiments of the present specification and not for the purpose of limitation. In addition, some elements to which various modifications such as exaggeration and omission are applied may be shown in the drawings below for clarity of description.
1 is a system structure diagram schematically modeling a power conversion system including a power conversion network according to an embodiment of the present invention.
2 is a diagram showing a result of applying a power network according to an embodiment of the present invention.
3A and 3B are diagrams for explaining an equivalent circuit of a power network according to an embodiment of the present invention.
4 is a schematic circuit diagram of a power conversion system 1 including a resonant converter according to a first embodiment of the present invention.
5A to 5C are diagrams for explaining a load impedance according to a variation range according to the first embodiment of the present invention.
6 is a diagram for explaining a variation of an input impedance according to a variation of a load according to the first embodiment of the present invention.
7 is a diagram schematically modeling the power conversion system of FIG. 4 according to the first embodiment of the present invention.
8A and 8B are diagrams for explaining a power factor according to a variation range of a load according to the first embodiment of the present invention.
9 is a circuit diagram of a power network, according to a second embodiment of the present invention.
10A to 10C are diagrams for explaining an input impedance and a voltage gain according to a frequency according to a second embodiment of the present invention.
11A and 11B are diagrams for explaining a voltage V1 waveform and a current I1 waveform at an input terminal of a resonant converter according to a second embodiment of the present invention.

The terms used in the present invention are only used to describe the determined embodiment, and are not intended to limit the present invention. Singular expressions used in the scope of the present invention and the appended claims are intended to include plural expressions as well, unless clearly indicated otherwise in the context below. In addition, the term "and/or" used in the present invention should be understood to include any or all possible combinations of one or more related listed items.

Terms such as first, second and third are used to describe various parts, components, regions, layers, and/or sections, but are not limited thereto. These terms are only used to distinguish one part, component, region, layer or section from another part, component, region, layer or section. Accordingly, a first part, component, region, layer or section described below may be referred to as a second part, component, region, layer or section without departing from the scope of the present invention.

Although not defined differently, all terms including technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms defined in a commonly used dictionary are additionally interpreted as having a meaning consistent with the related technical literature and the presently disclosed content, and are not interpreted in an ideal or very formal meaning unless defined.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings.

1 is a system structure diagram of a simple model of a power conversion system including a power conversion network according to an embodiment of the present invention.

Referring to FIG. 1, the power conversion system 1 includes a power supply source 110 for supplying power; A power network 130 for converting input power; And a load unit 150 receiving power through the power network 130.

The power supply 110 supplies AC power. In one embodiment, the power supply may be configured to supply AC power by itself, such as a single or three phase power supply, or may be configured to supply AC power from a DC voltage source utilizing an inverter circuit.

The power network 130 is connected to the load unit 150 including the load impedance Z _L. The role of the power network 130 is to convert the input impedance Z _{in which} is the impedance when the load impedance Z _L is viewed from the power supply 110 to a desired value.

2 is a diagram showing a result of applying a power network according to an embodiment of the present invention.

An example of converting an arbitrary load impedance (Z _L ) into an input impedance (Z _in ) required by the system is shown. In this case, R represents the real component of Z and X represents the imaginary component of Z. By converting the load impedance (Z _L ) into a specific input impedance (Z _in ), it is possible to satisfy the characteristics required by the system. For example, the power factor at the input terminal can be improved or the voltage applied to the load can be boosted or stepped down. When a transformer is used, the real component (R _L ) and the imaginary component (X _L ) of the load impedance (Z _L ) are converted at the same ratio. However, according to embodiments of the present invention, there is a feature that the load impedance (Z _L ) can be converted to an arbitrary value.

The power network 130 may include a plurality of passive elements. In the case of including 3 or more terminals, it can be used as a resonant converter with more resonant frequency, and in the case of including 4 or more terminals, it is more effective for start up and short circuit protection. to be.

Therefore, for convenience of description below, the power network 130 includes a first network impedance (Z ₁₁ ), a second network impedance (Z ₁₂ ), a third network impedance (Z ₂₁ ), and a fourth network impedance (Z _{22 ).} The embodiments will be described by referring to a 4-terminal power network including ). However, the power network 130 according to the embodiments of the present invention is not intended to be limited to a four-terminal power network, and may also be applied to a power network 130 including a combination of two or more various passive elements. .

The input/output relationship of a 4-terminal network made of passive elements at an arbitrary frequency can be generalized by the following equation.

[Equation 2]

Here, V ₁ is the voltage at the input end of the power network 130, V ₂ is the voltage at the output end of the power network 130, I ₁ is the current at the input end of the power network 130, and I ₂ is the power network 130. Shows the current at the output stage. In addition, Z ₁₁ may be represented as R ₁₁ +jX ₁₁ , Z ₁₂ as R ₁₂ +jX ₁₂ , Z ₂₁ as R ₂₁ +jX ₂₁ , and Z ₂₂ as R ₂₂ +jX ₂₂ .

Here, the power network circuit 130 may be composed of a passive element, and preferably may be composed only of a capacitor, an inductor, or a combination thereof. That is, the power network circuit 130 may be a lossless system having only reactive components. Assuming that there is no loss in the power network 130, it can be expressed as a modified equation as follows. In this case, if the power network 130 is reciprocal, X ₁₂ =X ₂₁ .

[Equation 3]

Here, X ₁₁ , X ₁₂ , and X ₂₂ are related to degrees of freedom for designing the 4-terminal power network 130, and each value may be determined according to the purpose of the system intended by the designer.

The input impedance (Z _in ) and the output impedance (eg, load impedance (Z _L )) are each defined by the following equation. In this case, R represents the real component of Z and X represents the imaginary component of Z.

[Equations 4 and 5]

Based on the above equations, the relationship between the output impedance Z _L and the input impedance Z _{in of the} 4-terminal power network 130 may be expressed by the following equation.

[Equations 6 and 7]

3A and 3B are diagrams for explaining an equivalent circuit of a power network according to an embodiment of the present invention.

When X ₁₁ , X ₁₂ , and X ₂₂ are determined, it can be implemented as a T-type equivalent model or a pi-type equivalent model. In one embodiment, the power network 130 may be implemented as a T-type equivalent model. As shown in FIG. 3A, the T-type equivalent circuit includes: a first equivalent impedance Z ₁ and a second equivalent impedance Z ₂ arranged in series between the input terminal and the output terminal of the power network; And the first equivalent impedance (Z ₁₎ and the second equivalent impedance (Z ₂₎ extends between nodes, the first equivalent impedance (Z ₁₎ and the second equivalent impedance (Z ₂₎ and the parallel connected third equivalent impedance ( Z ₃ ). In this case, the first, equivalent impedance, second equivalent impedance, and third equivalent impedance may be expressed as follows using a first network impedance, a second network impedance, a third network impedance, and a fourth network impedance, respectively.

[Equations 8 to 10]

Z ₁ =jX ₁₁ -jX ₁₂

Z ₂ =jX ₂₂ -jX ₁₂

Z ₃ =jX ₁₂

In some embodiments, when the power conversion system 1 is configured in an isolated type, the power network 130 may further include a transformer. For example, as shown in FIG. 3B, the isolated network may further include a transformer wound at a ratio of n.

When designing degrees of freedom X ₁₁ , X ₁₂ , and X ₂₂ of a 4-terminal network based on Equations 6 and 7 above, the output impedance can be converted into an arbitrary input impedance. The variable related to the load is a constant, and the design degree of freedom is three, and the equations that must be satisfied are two equations for R _in and X _in . For this reason, there are countless solutions to convert the output impedance. Therefore, since the 4-terminal power network 130 has a high degree of freedom, it can be easily utilized to design an optimized power network.

In particular, when a resonant converter based on the power network 130 and other components is included in the power conversion system 1, it is optimized to drive the resonant converter (for example, the power factor of the resonant converter can be improved). The power network 130 can be designed

Embodiment 1

4 is a circuit diagram of a power conversion system 1 including a resonant converter, according to a first embodiment of the present invention.

4, the power conversion system 1 is a resonant converter (RC, Resonant Converter) that transfers power from the power supply source 110, the load unit 150, and the power supply source 110 to the load unit 150. ). The resonant converter includes a power network 130. In addition, in some embodiments, the resonant converter may further include one or more of the inverter unit 120 and the rectifier circuit 140.

In some embodiments, the inverter circuit may be classified according to the number of active elements or output types. The inverter circuit includes, for example, a full bridge inverter that synthesizes a square wave voltage from a DC voltage source through four switches, a half bridge inverter that synthesizes a square wave voltage through two switches, and the like.

In addition, the power conversion system 1 may further include a controller (not shown). The controller serves to control the output voltage of the inverter unit 120. The controller may include one or more of a current command generator, a weak magnetic flux controller, a current controller, a voltage controller, a step voltage generator, a compensation voltage generator, a PWM unit, and a coordinate converter, but is not limited thereto.

5A to 5C are diagrams for explaining a load impedance according to a variation range according to the first embodiment of the present invention. Variation ranges for each impedance component of the load are represented by regions including respective points Z _L and Z _{in in} FIGS. 5A to 5C.

The load impedance included in the load unit 150 is a variable load that fluctuates within a specific range. When looking at the load impedance from the power supply source 110, the load impedance is determined by the components of the resonant converter disposed between the power supply source 110 and the load impedance (for example, the power network 130). Is converted to the input impedance of

5A is an example in which the real component of the input impedance fluctuates within a relatively narrow range when the real component of the load impedance changes over a relatively wide range, and FIG. 5B is an example of the input impedance when the real component of the load impedance changes over a wide range. This is an example in which the imaginary component of is fluctuated in a narrow range. Finally, FIG. 7C is an example in which the input impedance does not change even if the load impedance changes.

When the power system includes a converter and a load, the load impedance is generally not fixed at one point and varies within a certain range. In particular, when the converter is a resonant converter, if the load impedance fluctuates due to the characteristics of the resonant converter optimized at one frequency, the power factor of the input terminal of the resonant converter decreases, resulting in inefficient driving of the entire power system. there is a problem.

As described above, the four-terminal power network 130 has a high degree of freedom. Therefore, when the power network 130 included in the power conversion system 1 is designed to convert a load varying in a specific range into an input impedance in a range required by the system, the load impedance connected to the resonant converter is varied. It can solve the problem of power factor drop.

In one embodiment, in order to solve the problem of lowering the power factor due to fluctuations in load impedance, the power network 130 is designed to have a power factor (or power factor intended by the designer) optimized for the resonant converter when applied to a resonant converter. Can be. In addition, in some embodiments, the power network 130 may be designed to have a power factor within an allowable range of power factor fluctuations based on the optimized power factor. For example, when the power factor variation allowable range is 10%, the power network 130 may be designed such that the resonant converter has a power factor value between 0.9 and 1.

Since the power factor is usually set to an optimal value, in most cases, the power network 130 may be designed to have a power factor of 1 or a value close to 1 (eg, 0.85 or more) of the resonant converter. .

However, the optimized power factor value and the permissible range of power factor fluctuations depend on the characteristics of the system and may be variously determined accordingly. Accordingly, the above-described optimization values for load fluctuations (eg, 1 or a power factor value close to 1) are merely illustrative. The design of the power network 130 is not limited thereto, and in certain cases (e.g., to increase switching characteristics), the power network 130 may be intentionally designed to have a power factor value lower than 1 Will be clear to you.

6 is a diagram for explaining a variation of an input impedance according to a variation of a load according to the first embodiment of the present invention.

When the load impedance fluctuates with a range, the fluctuation of the input impedance appears as shown in FIG. 6. Here, R _L represents the real component of the load impedance (Z _L ).

As shown in FIG. 6, when analyzing the graph form of R _in according to R _L , the graph form has one maximum point. The R _L value (hereinafter referred to as “ _L,crit ”) that makes R _in the maximum is expressed by the following equation.

[Equation 11]

Depending on the region where R _L fluctuates, the form in which the input impedance fluctuates. For example, the R _L, characteristics when subject to _crit the border R _L is R _L, much smaller than _crit (area A1), as R _L is increased R _in a linearly increasing, and is held constant X _in have. In addition, R _in is a characteristic that is linearly reduced, and X _in is kept constant, as R _L, and the _crit the border R _L is R _L, much greater if (area A3) R _L is increased _crit. On the other hand, when R _L is in the vicinity of R _L,crit (area A2), there is a characteristic that R _in hardly changes when R _L changes.

In one embodiment, A1 and A3 represent a range in which the Xin value is maintained at approximately 10%, and A2 represents a range in which the value of Rin is maintained within approximately 10%. For example, when A1 to A3 are expressed based on the m value, the area A1 may be expressed as m<0.2, the area A2 may be expressed as 1/1.5 (=0.67)<m<1.5, and the area A3 may be expressed as 5<m. .

However, these figures are merely exemplary. As described above, since fluctuations in input impedance and optimized power factor values are different according to system characteristics, ranges representing areas A1, A2, and A3 may be different according to system characteristics.

When information on the load fluctuation range shown in FIG. 5 is obtained, it is possible to predict how the input impedance of the resonant converter will fluctuate, so this can be applied to the design of the resonant converter.

If the ratio of R _L,crit and R _L is defined as a variable called m, you can select the value of m to control the fluctuation of the input impedance according to the fluctuation of the load. At this time, the values of X ₁₁ , X ₁₂ , and X ₂₂ according to m are uniquely determined as shown in the following equation.

[Equations 12 to 14]

In order for the power conversion system 1 including the resonant converter to be optimized, the resonant converter must have a high power factor even when including a variable load having a fluctuation range of 10% to 100%, for example. That is, the input impedance converted through the power network 130 has a value capable of maintaining the power factor of the power conversion system 1 close to 1 or 1. Hereinafter, a process of designing a four-terminal power network to maintain the power factor at the input terminal of the resonant converter at (or close to 1) will be described in detail.

7 is a diagram schematically modeling the power conversion system of FIG. 4 according to the first embodiment of the present invention. When the power transmission is mostly performed by the fundamental wave component, the power conversion system 1 of FIG. 4 can be simply modeled as shown in FIG. 7 using a converter and power network 130. Here, V ₁ is the fundamental wave component of the voltage synthesized by the inverter. R _L is an effective resistance component simply modeled according to the fundamental wave assumption of a rectifier circuit, and its value is determined according to the output voltage/output power condition.

At this time, the imaginary component (X _in ) of the input impedance is designed to be 0, and the power factor of the power conversion system 1 is maintained close to 1 or 1. The real component (R _in ) of the input impedance is determined according to the input voltage/output power condition. The component of the input impedance can be expressed by the following equations.

[Equations 15 and 16]

Here, P _o is the output power, and V _in is the magnitude of the voltage applied to the power supply 110. In one embodiment, when the power conversion system 1 includes a DC voltage source and an inverter, V _in represents the DC voltage magnitude of the DC voltage source.

8A and 8B are diagrams for explaining a power factor according to a variation range of a load according to the first embodiment of the present invention.

In one embodiment, when the variable region of the load exists in the region A1 shown in FIG. 6 (i.e., m<<1), the resonant converter to which the power network 130 according to the first embodiment is applied is ( For example, as shown in FIG. 8, it has a power factor value of 0.85 or higher) or maintained close to 1.

As described above, when using the resonant converter to which the power network 130 according to the first embodiment of the present invention is applied, it can have a high power factor even though the load varies, and as a result, the entire system can have high efficiency. .

In particular, in designing the power network 130 according to the first embodiment, a combination of passive elements optimized for a resonant converter can be designed without a case study for each combination. As a result, it is possible to save resources such as time and money that may be consumed in case studies.

Embodiment 2

In general, converters are preferred to be driven over a wide input voltage range. However, in the case of a resonant converter, if it is designed to satisfy a wide input voltage range, the efficiency is good under the rated condition, but it is inefficiently driven under other driving conditions.

In this example, the resonant converter is designed so that the output impedance has an optimized power factor (or a power factor intended by the designer) for two driving frequencies f ₀ and f ₁ . In one embodiment, a process of designing the power network 130 for converting the input impedance Z _in so that the power factor of the resonant converter becomes 1 will be described in detail.

The input impedance (Z _{in_0} ), optimized at the frequency (f ₀ ), converted from the output impedance (Z _{L_0} ), is expressed as follows.

[Equations 17 and 18]

Here, X _{11_0} is the imaginary component of the first network impedance at the frequency (f ₀ ), X _{12_0} is the imaginary component of the second network impedance at the frequency (f ₀ ), and X _{22_0} is the fourth network impedance at the frequency (f ₀ ). The imaginary component, R _{L_0} , represents the real component of the load impedance at the frequency (f ₀ ).

The frequency (f ₁₎ an input impedance (Z _{in_1)} converted from the output impedance (Z _{L_1)} optimization is expressed as follows.

[Equations 19 and 20]

Here, X _{11_1} is the imaginary component of the first network impedance at the frequency (f ₁ ), X _{12_1} is the imaginary component of the second network impedance at the frequency (f ₁ ), and X _{22_1} is the fourth network impedance at the frequency (f ₁ ). The imaginary component, R _{L_1} , represents the real component of the load impedance at the frequency (f ₁ ).

In one embodiment, the imaginary component of the transformed input impedance to be optimized for each frequency (f ₀ , f ₁ ) is determined to be each zero.

When the power network 130 of the resonant converter is configured to satisfy Equations 17 to 20, the resonant converter is optimized for two driving frequencies and, as a result, has high system efficiency.

When the power network 130 designed as described above is applied to a resonant converter, the resonant converter can be efficiently driven even when an input voltage is changed over a wider range.

In the above embodiment, in order to solve the problem of lowering the power factor due to the fluctuation of the load impedance, the power network 130 is designed to have a power factor optimized for the resonant converter (or the power factor intended by the designer) when applied to the resonant converter. However, in some embodiments, the power network 130 may be designed to have a power factor within an allowable range of power factor fluctuations based on the optimized power factor. For example, when the power factor variation allowable range is 10%, the power network 130 may be designed such that the resonant converter has a power factor value between 0.9 and 1.

However, the optimized power factor value and the permissible range of power factor fluctuations depend on the characteristics of the system and may be variously determined accordingly. Therefore, the optimization values (eg, power factor of ₁ ) for each frequency (f ₀ , f ₁ ) described above are merely illustrative. The design of the power network 130 is not limited thereto, and in certain cases (e.g., to increase switching characteristics), the power network 130 may be intentionally designed to have a power factor value lower than 1 Will be clear to you.

9 is a circuit diagram of a power network, according to a second embodiment of the present invention.

In an embodiment, the power network 130 satisfying Equations 17 to 20 may include two capacitors and two inductors.

Referring to FIG. 9, a power network 130 according to a second embodiment includes: a first capacitor and a second capacitor disposed in series between an input terminal and an output terminal of the power network 130; A first inductor disposed between the first capacitor and the second capacitor; And a second inductor extending from a node between the first inductor and the second capacitor and connected in parallel with the first inductor and the second capacitor.

10A to 10C are diagrams for explaining an input impedance and a voltage gain according to a frequency according to a second embodiment of the present invention.

In one embodiment, in the resonant converter, two optimized frequencies (f ₀ , f ₁ ) are set to 100 kHz and 180 kHz, respectively, and the voltage gain is 2 times difference and R _{in_0} and R _{in_1} are 4 times different from each other at the two frequencies. It is set to come out. The resonant converter is configured such that X _{in_0} and X _{in_1} are 0 at both frequencies, and as a result, the power factor at the input end of the resonant converter is further configured to be 1.

When configured as described above, the real component (R _in ) and the imaginary component (X _in ) of the input impedance (Z _in ) of the resonant converter as viewed from the power supply source 110 of the power conversion system 1 are shown _in FIG. And as shown in Fig. 10B, respectively. In addition, the voltage gain of the resonant converter appears as shown in FIG. 10C according to the frequency. When the voltage gain result as shown in FIG. 10C is obtained, it means that the resonant converter can maintain the output voltage constant by changing the frequency even if the input voltage is a difference of two times.

11A and 11B are diagrams for explaining a voltage (V ₁ ) waveform and a current (I ₁ ) waveform at an input terminal of a resonant converter according to a second embodiment of the present invention.

In the above embodiment, the resonant converter is configured to change the frequency to keep the output voltage constant, even if the input voltage differs by 2 times. In one example, when the first input voltage is 150V and the second input voltage is 300V, when the input voltage is doubled from 150V to 300V, the output voltage remains constant even if the frequency is changed from 100kHz to 180kHz. In this case, in a situation in which the output voltage of the resonant converter is kept constant, waveforms of the voltage V ₁ and the current I ₁ of the input terminal appear as shown in FIGS. 11A and 11B.

Referring to FIGS. 11A and 11B, it can be seen that the power factor of the input end of the resonant converter is maintained close to 1 at two frequencies. This means that even if the input voltage of the resonant converter is doubled, the resonant converter is driven efficiently.

As described above, when using the resonant converter to which the power network 130 according to the second embodiment of the present invention is applied, the resonant converter is optimized and driven at two driving frequencies. Therefore, even if the input voltage is changed in a wider range, it can have a high power factor, thereby having the effect of extending the rated condition. Eventually, the efficiency of the entire system can be improved.

The present invention described above has been described with reference to the embodiments shown in the drawings, but these are merely exemplary, and those of ordinary skill in the art will understand that various modifications and variations of the embodiments are possible therefrom. However, such modifications should be considered to be within the technical protection scope of the present invention. Therefore, the true technical scope of the present invention should be determined by the technical spirit of the appended claims.

Claims (12)

As a resonant converter applied to a power conversion system having a power supply and a load,
The resonant converter,
A power network configured to transmit power from the power supply source to a load and comprising a passive element;
An inverter unit disposed between the power supply source and a power network; And
Comprising a rectifier disposed between the power network and a load,
The power network is a four-terminal network, and the input/output relationship of the four-terminal network is expressed by the following equation,
[Equation]

Here, V1 is the voltage at the input end of the power network, V2 is the voltage at the output end of the power network, I1 is the current at the input end of the power network, I2 is the current at the output end of the power network, and Z11 is the first network impedance (Z11 = R11 +jX11), a second network impedance (Z12=R12+jX12), a third network impedance (Z21=R21+jX21), and a fourth network impedance (Z22=R22+jX22),
The imaginary component (X11) of the impedance of the first network, the imaginary component (X12) of the impedance of the second network, and the imaginary component (X22,) of the impedance of the fourth network are expressed as follows,

Here, Xin and Rin represent the components of the input impedance viewed from the power supply source, RL represents the real component of the load impedance, and RL,crit represent the RL value that causes Rin to become the maximum when RL fluctuates. Resonant converter.
delete delete The method of claim 1,
The power network may be modeled as a T-type equivalent circuit, and the T-type equivalent circuit,
A first equivalent impedance and a second equivalent impedance arranged in series between the input terminal and the output terminal of the power network; And
A third equivalent impedance extending from a node between the first equivalent impedance and the second equivalent impedance and connected in parallel with the first equivalent impedance and the second equivalent impedance,
Resonant type, characterized in that the imaginary component of the first equivalent impedance is X ₁₁ -X ₁₂ , the imaginary component of the second equivalent impedance is X ₂₂ -X ₁₂ , and the imaginary component of the third equivalent impedance is X ₁₂ Converter.
The method of claim 4,
The power network is configured such that the equivalent impedances of the T-type equivalent circuit satisfy the following equation,

Here, X ₁ represents an imaginary component of the first equivalent impedance, X ₂ represents an imaginary component of the second equivalent impedance, and X ₃ represents an imaginary component of the third equivalent impedance.
The method of claim 1, wherein the power network,
A first capacitor and a second capacitor arranged in series between the input terminal and the output terminal of the power network;
A first inductor disposed between the first capacitor and the second capacitor; And
And a second inductor extending from a node between the first inductor and the second capacitor and connected in parallel with the first inductor and the second capacitor.
The method of claim 6,
When the frequency is variable in the power conversion system,
The first, second and fourth network impedances (Z11, Z12, Z22) are designed to satisfy the following equation at a first frequency f0 or a second frequency f1,
[Equation]

[Equation]

Resonant converter.
The method of claim 7,
A resonant converter, characterized in that when the load impedance fluctuates, the power factor value of the resonant converter maintains a preset value.
The method of claim 7,
The power network is further configured to satisfy the following equation at the first frequency,

Where X _{11_0} is the imaginary component of the first network impedance at the first frequency, X _{12_0} is the imaginary component of the second network impedance at the first frequency, X _{22_0} is the imaginary component of the fourth network impedance at the first frequency, and R _{L_0} is Resonant converter, characterized in that it represents a real component of the load impedance at the first frequency.
The method of claim 7,
The power network is further configured to satisfy the following equation at the second frequency,

Here, X _{11_1} is the imaginary component of the first network impedance at the second frequency, X _{12_ 1} is the imaginary component of the second network impedance at the second frequency, X _{22_ 1} is the imaginary component of the fourth network impedance at the second frequency, R _{L_1} is a resonant converter, characterized in that the real component of the load impedance at the second frequency.
. The method of claim 1,
The power network is a resonant converter, characterized in that configured in a reciprocal (reciprocal). The method of claim 8,
Resonant converter, characterized in that the power factor value of the resonant converter maintains 0.9 to 1 when the input voltage fluctuates.

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