Power conversion device

Abstract

A power conversion device according to the present embodiment comprises: a switching unit for switching an input voltage to transmit same; a resonance unit connected to the switching unit and including a magnetizing inductor and a variable inductor unit; and a transformation unit having a primary side connected to the magnetizing inductor in parallel, wherein the variable inductor unit is connected to the magnetizing inductor in parallel, and the variable inductor unit includes at least one auxiliary switch and at least one auxiliary inductor connected in series.

Description

power conversion device

[0001] This embodiment relates to a power conversion device.

[0002] Due to recent industrial development and the expansion of renewable energy, research is actively being conducted to improve the efficiency and density of power conversion devices.

[0003] These power conversion devices are used in applications such as microgrid systems, energy storage systems (ESS), electric vehicle OBCs (One Board Chargers) and battery charging / discharging systems, and fuel cell power conversion devices, and power conversion devices with a wide input / output voltage control range are required.

[0004] Various studies are being conducted on DC-DC converters, which are power conversion devices, to improve manufacturing costs, stability, and efficiency, and among them, LLC converters are widely used.

[0005] For these LLC topologies, much research is being conducted to secure a wide output voltage, and in the case of general LLC circuits, there is a problem that the resonance efficiency may be reduced because a wide range of operating frequencies is used to secure a wide output voltage.

[0006] The present embodiment provides a power conversion device capable of securing a wide output voltage range.

[0007] In order to solve the above technical problem, a power conversion device according to the present embodiment includes a switching unit that switches and transmits an input voltage; a resonant unit connected to the switching unit and including a magnetizing inductor and a variable inductor unit; and a transformer unit whose primary side is connected in parallel with the magnetizing inductor, wherein the variable inductor unit is connected in parallel with the magnetizing inductor, and the variable inductor unit includes at least one auxiliary switch and at least one auxiliary inductor connected in series.

[0008] Additionally, as the at least one switch is turned on / off, the magnetizing inductance value of the resonant section can be changed by the at least one auxiliary inductor and the magnetizing inductor.

[0009] Additionally, in each mode in which at least one auxiliary switch performs an ON / OFF operation, the value of the magnetizing inductance may be different for each mode.

[0010] In addition, when there are multiple modes satisfying the required output voltage, the mode having a larger value of the magnetizing inductance among the multiple modes satisfying the required output voltage can be operated.

[0011] Additionally, the variable inductor unit may include a first auxiliary switch and a first auxiliary inductor connected in series.

[0012] In addition, the variable inductor section may be such that one end of the first auxiliary switch is connected to one end of the primary side of the transformer section, the other end of the first auxiliary switch is connected to one end of the first auxiliary inductor, and the other end of the first auxiliary inductor may be connected to the other end of the primary side of the transformer section.

[0013] In addition, the variable inductor section includes a second auxiliary switch and a second auxiliary inductor connected in series, and the first auxiliary switch and the first auxiliary inductor can be connected in parallel with the second auxiliary switch and the second auxiliary inductor.

[0014] In addition, the variable inductor section may be such that one end of the second auxiliary switch is connected to one end of the primary side of the transformer section, the other end of the second auxiliary switch is connected to one end of the second auxiliary inductor, and the other end of the second auxiliary inductor is connected to the other end of the primary side of the transformer section.

[0015] In addition, the switching unit includes first to fourth switching elements formed in a full bridge structure, wherein the first switching element and the second switching element are connected in parallel, the first switching element and the third switching element are connected in series, and the second switching element and the fourth switching element can be connected in series.

[0016] In addition, the resonant part includes a resonant capacitor, and the resonant capacitor can be connected between a node between the first switching element and the second switching element and one end of the primary side of the transformer.

[0017] In addition, the resonant part may include a resonant inductor, and the resonant inductor may be connected between a node between the third switching element and the fourth switching element and the other end of the primary side of the transformer.

[0018] In addition, it may include a rectifier connected to the secondary side of the transformer and rectifying the voltage output from the secondary side of the transformer.

[0019] In addition, the filter unit may include a filter unit that smooths the voltage output from the rectifier unit, and the filter unit may include one or more capacitors.

[0020] The power conversion device according to the present embodiment can secure a wide output voltage range by adjusting the value of the magnetizing inductance.

[0021] By selecting the most efficient value of the magnetizing inductance depending on the application in which the output voltage is used, the efficiency and stability of the circuit can be increased.

[0022] Figure 1 is a block diagram of a power conversion device according to the present embodiment.

[0023] Figure 2 is a diagram illustrating a circuit of a power conversion device according to the present embodiment.

[0024] Figure 3 is a circuit including a variable inductor section in which two auxiliary switches (S1, S2) and two auxiliary inductors (Lm1, Lm2) are arranged in parallel with a magnetizing inductor (Lm0).

[0025] Figures 4 to 7 are graphs of the gain of the output voltage versus the input voltage according to the operation of the first auxiliary switch (S1) and the second auxiliary switch (S2).

[0026] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[0027] However, the technical idea of ​​the present invention is not limited to some of the embodiments described, but can be implemented in various different forms, and within the scope of the technical idea of ​​the present invention, one or more of the components between the embodiments can be selectively combined or substituted for use.

[0028] In addition, terms (including technical and scientific terms) used in the embodiments of the present invention may be interpreted as having a meaning that can be generally understood by a person of ordinary skill in the technical field to which the present invention belongs, unless explicitly and specifically defined and described, and terms that are commonly used, such as terms defined in a dictionary, may be interpreted in consideration of the contextual meaning of the relevant technology.

[0029] Additionally, the terms used in the embodiments of the present invention are intended to describe the embodiments and are not intended to limit the present invention.

[0030] In this specification, the singular may also include the plural unless specifically stated otherwise in the phrase, and when it is described as “A and / or at least one (or more) of B, C”, it may include one or more of all combinations that can be combined with A, B, C.

[0031] Additionally, in describing components of embodiments of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only intended to distinguish the components from other components, and are not intended to limit the nature, order, or sequence of the components.

[0032] And, when a component is described as being 'connected', 'coupled', or 'connected' to another component, it may include not only cases where the component is 'connected', 'coupled', or 'connected' directly to the other component, but also cases where the component is 'connected', 'coupled', or 'connected' by another component between the component and the other component.

[0033] Additionally, when described as being formed or arranged "above" or "below" each component, "above" or "below" includes not only cases where the two components are in direct contact with each other, but also cases where one or more other components are formed or arranged between the two components. Furthermore, when expressed as "above" or "below," the meaning may include not only the upward direction but also the downward direction based on one component.

[0034] Below, the configuration of a power conversion device according to the present embodiment is described with reference to the drawings.

[0035] Fig. 1 is a block diagram of a power conversion device according to the present embodiment, and Fig. 2 is a diagram illustrating a circuit of a power conversion device according to the present embodiment.

[0036] Figure 1 is a block diagram of a power conversion device according to the present embodiment.

[0037] The power conversion device (1000) according to the present embodiment may include a switching unit (200), a resonant unit (300), a transformer unit (400), a rectifier unit (500), and a filter unit (600).

[0038] The switching unit (200) switches the DC power supplied from the power supply unit (100) and transmits it to the resonance unit (300). The power supply (100) converts AC power supplied from the outside into a DC form by an inverter (not shown) and then transmits the converted DC power to the switching unit (200). At this time, the power supply (100) may be a battery or an external power source.

[0039] The resonant unit (300) resonates the power supplied from the switching unit (200) and transmits it to the transformer unit (400).

[0040] The transformer (400) transmits an output signal in the form of a resonant frequency to the rectifier (500) via the resonant section (300). The transformer (400) includes a transformer and can step down or step up the voltage received from the resonant section (300). The transformer of the transformer (400) is formed of a primary coil and a secondary coil, and can convert the magnitude of the voltage by utilizing the principle of induced electromotive force generated between the primary coil and the secondary coil.

[0041] The rectifier (500) is arranged on the secondary side of the transformer (400) and rectifies the voltage applied through a plurality of diodes based on the signal received from the transformer (400). In other words, it converts the alternating current, whose magnitude and direction periodically change over time, into a direct current, whose magnitude and direction do not change over time and whose magnitude and direction constantly flow. The rectifier (500) may be composed of a diode or a MOSFET switch.

[0042] The filter unit (600) can smooth the voltage output from the rectifier unit (500) and output it as a DC voltage. The filter unit (600) can include one or more inductors and one or more capacitors. The inductor can be connected in series with the rectifier unit (500), and the capacitor can be connected in parallel with the rectifier unit (500). Here, the inductor and capacitor can operate as an LC filter to smooth the voltage output from the rectifier unit (500) and output a DC voltage. Through this, a stable voltage can be provided to the load (700). Here, the load (700) can be an electric vehicle (EV) and a battery mounted on the electric vehicle.

[0043] Figure 2 is a diagram illustrating a circuit of a power conversion device according to the present embodiment.

[0044] As shown in Fig. 2, the switching unit (200) can receive voltage input from the power source (100).

[0045] The switching unit (200) may be configured in a full bridge form with four switching elements (Q1, Q2, Q3, Q4). The four switching elements (Q1, Q2, Q3, Q4) perform a switching operation by a gate signal supplied from the outside, and can switch the DC power supplied from the power source (100) and transmit it to the resonance unit (300).

[0046] Switching elements (Q1, Q2, Q3, Q4) can be turned on or off with a duty by a gate signal received from a control unit (not shown).

[0047] The control unit (not shown) includes switching elements (Q1, Q2, Q3, Q4) of the switching unit (200) and auxiliary switches (S1 to S) of the variable inductor unit (310) described later. N ) and the MOSFET switch of the rectifier (500) can be controlled. At this time, the control unit may be placed within the power conversion device, or may be placed separately outside the power conversion device and electrically connected to the power conversion device.

[0048] The first switching element (Q1) and the third switching element (Q3) may have one end commonly connected. The second switching element (Q2) may be connected to the other end of the first switching element (Q1), and the fourth switching element (Q4) may be connected to the other end of the third switching element (Q3). The other end of the second switching element (Q2) and the other end of the fourth switching element (Q4) may be connected in common.

[0049] That is, the first switching element (Q1) and the third switching element (Q3) can be connected in parallel. The first switching element (Q1) and the second switching element (Q2) can be connected in series. The third switching element (Q3) and the fourth switching element (Q4) can be connected in series.

[0050] The first switching element (Q1) and the second switching element (Q2) are complementarily conductive, and the third switching element (Q3) and the fourth switching element (Q4) are complementarily conductive so that the voltage input from the power source (100) can be transmitted to the resonant unit (300).

[0051] The switching elements (Q1, Q2, Q3, Q4) may be semiconductor switching elements such as metal oxide semiconductor field effect transistors (MOSFETs) or silicon carbide (SiC) based MOSFETs.

[0052] The resonant section (300) resonates the voltage passing through the switching elements (Q1, Q2, Q3, Q4) with LLC (Inductor-Inductor-Capacitor) and transmits it to the transformer section (400). The resonant section (300) is composed of a resonant capacitor (Cr), a resonant inductor (Lr), and a magnetizing inductor (L m0 ) and a variable inductor section (310).

[0053] LLC resonance is based on the resonance principle, whereby the resonant frequency of a resonant circuit is adjusted to match the switching frequency of a power switch by using resonant elements such as capacitors, inductors, or resonant circuits. In other words, by adjusting the inductor and capacitor values, selective characteristics can be created for specific frequencies, enabling power conversion through the resonance of the resonant inductor (Lr) and resonant capacitor (Cr).

[0054] That is, the output voltage can be controlled by using the resonance characteristics of the resonant inductor (Lr) and the resonant capacitor (Cr). In this embodiment, the resonant capacitor (Cr), the resonant inductor (Lr), and the magnetizing inductor (L m0 ) and a variable inductor section (310) can be used to perform LLC resonance.

[0055] In the resonant section (300), a resonant capacitor (Cr), a resonant inductor (Lr), and a magnetizing inductor (L m0 ) and the resonance frequency is determined by the resonance of the variable inductor section (310), and the output voltage is changed according to the switching frequency input to the resonant section (300).

[0056] At this time, a leakage inductor (Ll) can also be used as a resonant inductor (Lr).

[0057] A resonant capacitor (Cr) may be placed between a node between the first switching element (Q1) and the second switching element (Q2) and one end of the primary side of the transformer (400).

[0058] A resonant inductor (Lr) can be placed between the node between the third switching element (Q3) and the fourth switching element (Q4) and the other end of the primary side of the transformer (400).

[0059] However, the present invention is not limited thereto, and the resonant capacitor (Cr) and the resonant inductor (Lr) may be changed. That is, the positions of the resonant capacitor (Cr) and the resonant inductor (Lr) may be switched, or the resonant capacitor (Cr) and the resonant inductor (Lr) may be directly connected in series.

[0060] Magnetizing inductor (L m0 ) is connected in parallel with the transformer (TF) on the primary side of the transformer (TF).

[0061] Resonant capacitor (Cr), resonant inductor (Lr) and magnetizing inductor (L m0 ) can be connected in series with each other.

[0062] The variable inductor section (310) includes at least one auxiliary switch (S1 to S N ) and at least one auxiliary inductor (L m1 ~L mN ) is included. (Here, N is a natural number.)

[0063] As shown in Fig. 2, at least one auxiliary switch (S1 to S N ) and at least one auxiliary inductor (L m1 ~L mN ) can be connected in series with each other. One end of at least one auxiliary switch (S1~SN) can be connected to one end of the primary side of the transformer (TF). At least one auxiliary switch (S1~S N ) has at least one auxiliary inductor (L m1 ~L mN ) can be connected in series with at least one auxiliary inductor (L m1 ~L mN ) can be connected to the other end of the primary side of the transformer (TF).

[0064] However, it is not limited thereto, and at least one auxiliary switch (S1~SN) and at least one auxiliary inductor (L m1 ~L mN ) can be changed. That is, the auxiliary inductor (L m1 ~L mN ) is connected to one end of the primary side of the transformer (TF), and the auxiliary inductor (L m1 ~L mN ) is the other end of the auxiliary switch (S1~S N ) are connected in series to one end of the auxiliary switch (S1~S N) can be connected to the other end of the primary side of the transformer (TF).

[0065] At least one auxiliary switch (S1~S) N ) is selectively turned on / off, thereby generating a magnetizing inductor (L). m0 ) and the auxiliary inductor can be connected in parallel. In this way, the auxiliary switches (S1~S N ) can be selectively turned on / off, thereby varying the value of the magnetizing inductance among the resonance parameters (Lr, Lm, Cr) of the LLC topology. The magnetizing inductance value of the LLC resonant circuit can be selected according to the output voltage.

[0066] The transformer (400) is composed of a transformer (TF), and the primary side of the transformer (TF) is arranged in parallel with a magnetizing inductor (Lm0).

[0067] The transformer (400) includes a primary winding (L1) and a secondary winding (L2), and can convert the magnitude of the voltage by using the induced electromotive force generated between the primary winding (L1) and the secondary winding (L2). When a voltage is input to the primary winding (L1), the strength and direction of the current are formed, and the magnetic field around the primary winding (L1) changes. According to the change in this magnetic field, the magnetic flux (magnetic force) changes, and accordingly, the induced electromotive force is generated in the secondary winding (L2). The power of the primary winding (L1) and the secondary winding (L2) is the same according to the law of conservation of energy, and the number of turns wound on the coil is proportional to the voltage, so the transformation ratio can be formed differently depending on the number of turns.

[0068] At both ends of the primary winding (L1) there is a magnetizing inductor (L m ) and a variable inductor section (310) are connected in parallel. A resonant capacitor (Cr) is connected in series to one end of the primary winding (L1), and a resonant inductor (Lr) can be connected in series to the other end of the primary winding (L1).

[0069] That is, as shown in Fig. 2, at least one auxiliary switch (S1 to SN ) is connected to one end of the primary side of the transformer (TF). At least one auxiliary inductor (L m1 ~L mN ) is connected to the other end of the primary side of the transformer (TF). Accordingly, the voltage passing through the switching unit (200) is selectively changed in the value of the auxiliary inductance to cause LLC resonance, and then transmitted to the transformer unit (400).

[0070] The rectifier (500) is arranged on the secondary side of the transformer (TF) and may include a plurality of diodes (D1, D2, D3, D4). That is, the rectifier (500) can rectify the voltage transmitted from the secondary winding (L2) through the plurality of diodes (D1, D2, D3, D4) and transmit it to the filter (600). In the present embodiment, a plurality of diodes (D1, D2, D3, D4) are used, but the present invention is not limited thereto and may be configured as MOSFETs.

[0071] The filter unit (600) includes an output capacitor (C0) and can smooth the voltage output from the rectifier unit (500) and output it as a DC voltage.

[0072] In this embodiment, only the output capacitor (C0) is presented, but it is not limited thereto and one or more inductors may be further included. The inductor may be connected in series with the rectifier (500), and the output capacitor (C0) may be connected in parallel with the rectifier (500). Here, the inductor and the output capacitor (C0) may operate as an LC filter to smooth the voltage output from the rectifier (500) and output a DC voltage. Through this, a stable voltage can be provided to the load (700).

[0073] Hereinafter, a power conversion device according to the first modified example will be described with reference to FIGS. 3 to 7.

[0074] Figure 3 shows two auxiliary switches (S1, S2) and two auxiliary inductors (L m1 , L m2 ) is a magnetizing inductor (L m0) and a variable inductor section (310) arranged in parallel.

[0075] The variable inductor section (310) includes a first auxiliary switch (S1) and a first auxiliary inductor (L) connected in series with each other. m1 ) and a second auxiliary switch (S2) and a second auxiliary inductor (L) connected in series with each other. m2 ) is included.

[0076] One end of the first auxiliary switch (S1) is connected to one end of the primary side of the transformer (TF). The other end of the first auxiliary switch (S1) is connected to the first auxiliary inductor (L m1 ) is connected to one end of the first auxiliary inductor (L m1 ) is connected to the other end of the primary side of the transformer (TF).

[0077] In addition, one end of the second auxiliary switch (S2) is connected to one end of the primary side of the transformer (TF). The other end of the second auxiliary switch (S2) is connected to the second auxiliary inductor (L m2 ) is connected to one end of the second auxiliary inductor (L m2 ) is connected to the other end of the primary side of the transformer (TF).

[0078] That is, one end of the first auxiliary switch (S1) and one end of the second auxiliary switch (S2) are connected to one end of the primary side of the transformer (TF), and the other end of the primary side of the transformer (TF) is connected to the first auxiliary inductor (L m1 ) of the other end, the second auxiliary inductor (L m2 ) is connected to the other end. Accordingly, the first auxiliary inductor (L m1 ), second auxiliary inductor (L m2 ), magnetizing inductor (L m0 ) and transformer (TF) are arranged in parallel with each other.

[0079] The first auxiliary inductor (L) is turned on / off according to the on / off of the first auxiliary switch (S1) and the second auxiliary switch (S2). m1 ) and the second auxiliary inductor (L m2 ) is optionally connected. Accordingly, the magnetizing inductor (L m0) and the auxiliary inductor selected as the auxiliary switch may change the value of the magnetizing inductance participating in the resonance.

[0080] First auxiliary inductor (L m1 ), second auxiliary inductor (L m2 ) and magnetizing inductor (L m0 ) by magnetizing inductance (L) m ) The value of gain according to change is as follows.

[0081]

[0082] Here,

[0083] , , V in : Input voltage, V out : Output voltage, L m : Magnetizing inductance, L r : Resonant inductance, L r : resonant capacitance, R0: load resistance [P out / (V out *V out )], Np: number of turns on the primary side of the transformer, Ns: number of turns on the secondary side of the transformer, n: turns ratio (winding ratio) of the transformer.

[0084] At this time, the magnetizing inductance (L m ) To see the gain value according to the change in the value, the magnetizing inductance (L m ) are the same, we can see that the gain varies depending on the size of the parameter m.

[0085] Figures 4 to 7 are graphs showing the gain characteristics of the output voltage versus the input voltage according to the operation of the first auxiliary switch (S1) and the second auxiliary switch (S2), and will be explained according to the operation of each auxiliary switch. At this time, parameter L r =10μH, L m0 =100μH, L m1 =100μH, L m2 =50μH, C r=130nF. In addition, when both the first auxiliary switch (S1) and the second auxiliary switch (S2) are OFF, it is described as the first mode, when the first auxiliary switch (S1) is ON and the second auxiliary switch (S2) is OFF, it is described as the second mode, when the first auxiliary switch (S1) is OFF and the second auxiliary switch (S2) is ON, it is described as the third mode, and when both the first auxiliary switch (S1) and the second auxiliary switch (S2) are ON, it is described as the fourth mode.

[0086] Fig. 4 is a graph of a gain curve of output voltage versus input voltage according to switching frequency in the first mode in which both the first auxiliary switch (S1) and the second auxiliary switch (S2) of the variable inductor section (310) are OFF.

[0087] Magnetizing inductance (L) participating in LLC resonance in the first mode m ) is the value of the magnetizing inductor (L m0 ) is 100μH, which is the same value as m = (L r +L m ) / L r , and m=(10μH+100μH) / 10μH=11.

[0088] In this embodiment, a resonant capacitor (C0) and a resonant inductor (L r ) is a fixed value, the resonant frequency does not change. Here, if we assume that the resonant frequency is fixed at 100 kHz, the minimum operating frequency is 43 kHz and the peak gain is 2.1. And, if we assume that the minimum operating frequency in the above region is 150 kHz, the minimum gain becomes 0.87.

[0089] Fig. 5 is a graph of a gain curve of output voltage versus input voltage according to switching frequency in the second mode in which the first auxiliary switch (S1) of the variable inductor section (310) is on and the second auxiliary switch (S2) is off.

[0090] Magnetizing inductance (L) participating in LLC resonance in the second mode m ) is the value of parallel connected L m0 / L m1 The value is 50μH, and m=6.

[0091] In this case, the magnetizing inductance (L) in the second mode is higher than in the first mode. m ) is reduced in size, and when the resonant frequency is fixed at 100 kHz, the minimum operating frequency is 55 kHz and the peak gain increases to 3.1.

[0092] This allows for a wider voltage range than the first mode, and since the minimum operating frequency can be increased, the size of passive components such as transformers (TF) can be designed smaller. In addition, assuming that the minimum operating frequency in the region above the resonant frequency is 150 kHz, the minimum gain becomes 0.82, which allows for a lower output voltage than the first mode.

[0093] Fig. 6 is a graph of a gain curve of output voltage versus input voltage according to switching frequency in the third mode in which the first auxiliary switch (S1) of the variable inductor section (310) is OFF and the second auxiliary switch (S2) is ON.

[0094] Magnetizing inductance (L) participating in LLC resonance in the third mode m ) is the value of parallel-connected L m0 / L m2 The value is 33.33μH, and m=4.3.

[0095] In this case, the magnetizing inductance (L) in the third mode is higher than in the first and second modes. m ) is reduced in size, the minimum operating frequency is 62 kHz, and the peak gain is increased to 4.05.

[0096] This allows for a wider voltage range than the first and second modes, and since the minimum operating frequency can be increased, the size of passive components such as transformers (TF) can be reduced. In addition, assuming that the minimum operating frequency is 150 kHz in the region above the resonant frequency, the minimum gain becomes 0.82, which allows for a lower output voltage than the first and second modes.

[0097] Fig. 7 is a graph of a gain curve of output voltage versus input voltage according to switching frequency in the fourth mode in which both the first auxiliary switch (S1) and the second auxiliary switch (S2) of the variable inductor section (310) are ON.

[0098] Magnetizing inductance (L) participating in LLC resonance in the fourth mode m ) is the value of parallel-connected L m0 / L m1 / L m2 The value is 25μH, and m=3.5.

[0099] In this case, the magnetizing inductance (L) of the fourth mode is higher than that of the first to third modes. m ) is reduced in size, the minimum operating frequency is 68 kHz, and the peak gain is increased to 4.9.

[0100] This allows for a wider voltage range than the first or second modes, and since the minimum operating frequency can be increased, the size of passive components such as transformers (TF) can be reduced. In addition, assuming that the minimum operating frequency in the region above the resonant frequency is 150 kHz, the minimum gain becomes 0.68, which allows for a lower output voltage than the first, second, and third modes.

[0101] As you go from mode 1 to mode 4, you can increase the minimum operating frequency, which allows you to obtain higher and lower output voltages.

[0102] However, in the fourth mode, the magnetizing inductance (L m ) has the smallest size, it may have lower efficiency than the first to third modes due to losses caused by circulating current. Therefore, unless the lowest or highest output voltage is required, the second or third modes, which have less losses caused by circulating current, may be selected rather than the fourth mode.

[0103] That is, when there are multiple modes that satisfy the required output voltage, among the multiple modes that satisfy the required output voltage, the magnetizing inductance (L m ) by selecting a mode with a large value of magnetizing inductance (L m ) can be determined. The mode is selected by adjusting the auxiliary switch according to the required output voltage, and among the multiple modes, the magnetizing inductance (L m ) is adjusted to the largest value, the output voltage can be satisfied and the efficiency can be improved because the circulating current is small.

[0104] Here, the output voltage is a voltage output from the power conversion device according to an embodiment of the present invention, and the required output voltage may vary depending on the rated voltage of the load (700), etc. The required output voltage may be a target output voltage. For example, when outputting voltage to an electric vehicle, the required output voltage may vary depending on the rated voltage or charging mode of the battery of the electric vehicle, and accordingly, the control unit determines the mode in which the variable inductor unit (310) operates, and in the corresponding mode, the control unit controls the switching unit (200) to output and provide the voltage required for the electric vehicle.

[0105] Additionally, the required output voltage may vary depending on the application being used, other than electric vehicles. When a user selects and uses a specific application, a signal is input through a control unit (not shown), and the control unit adjusts the auxiliary switch accordingly to select the mode in which the variable inductor unit (310) operates.

[0106] That is, if the voltage required for each application is different, the control unit (not shown) can select a mode in which the auxiliary switch is adjusted according to each application.

[0107] Therefore, the efficiency and stability of the circuit can be increased by selecting the most efficient value of the magnetizing inductance depending on the application in which the output voltage is used.

[0108] A power conversion device according to an embodiment is configured to have one or more auxiliary switches and one or more auxiliary inductors arranged in parallel with a magnetizing inductor, so that the magnetizing inductance (L) is increased by the operation of the auxiliary switch. m ) can be adjusted to secure a wide output voltage range. That is, the output voltage can be adjusted according to the application used by using the auxiliary switch, and the operating frequency range can be minimized.

[0109] Although the embodiments of the present invention have been described with reference to the attached drawings, those skilled in the art will appreciate that the present invention can be implemented in other specific forms without altering the technical concept or essential features thereof. Therefore, the embodiments described above should be understood to be illustrative in all respects and not restrictive.

Claims

1. A switching unit that switches and transmits the input voltage; A resonant section connected to the above switching section and including a magnetizing inductor and a variable inductor section; and The primary side includes a transformer connected in parallel with the magnetizing inductor, The above variable inductor section is connected in parallel with the magnetizing inductor, A power conversion device including at least one auxiliary switch and at least one auxiliary inductor connected in series, wherein the variable inductor section is 2. In paragraph 1, As at least one of the above switches is turned ON / OFF, A power conversion device in which the magnetizing inductance value of the resonant section is changed by at least one auxiliary inductor and the magnetizing inductor.

3. In paragraph 1, A power conversion device, wherein each mode in which at least one auxiliary switch performs an ON / OFF operation has a different value of magnetizing inductance for each mode.

4. In paragraph 3, In each of the above modes, When there are multiple modes satisfying the required output voltage, A power conversion device that operates in a mode having a larger value of the magnetizing inductance among a plurality of modes that satisfy the above required output voltage.

5. In paragraph 1, A power conversion device including a first auxiliary switch and a first auxiliary inductor connected in series, wherein the variable inductor section is above.

6. In paragraph 5, The above variable inductor section, One end of the above first auxiliary switch is connected to one end of the primary side of the above transformer, The other end of the above first auxiliary switch is connected to one end of the above first auxiliary inductor, A power conversion device in which the other end of the first auxiliary inductor is connected to the other end of the primary side of the transformer.

7. In paragraph 6, The above variable inductor section includes a second auxiliary switch and a second auxiliary inductor connected in series, A power conversion device in which the first auxiliary switch and the first auxiliary inductor are connected in parallel with the second auxiliary switch and the second auxiliary inductor.

8. In paragraph 7, The above variable inductor section, One end of the above second auxiliary switch is connected to one end of the primary side of the above transformer, The other end of the second auxiliary switch is connected to one end of the second auxiliary inductor, A power conversion device in which the other end of the second auxiliary inductor is connected to the other end of the primary side of the transformer.

9. In paragraph 1, The above switching unit includes first to fourth switching elements formed in a full bridge structure, The first switching element and the second switching element are connected in parallel, The first switching element and the third switching element are connected in series, A power conversion device in which the second switching element and the fourth switching element are connected in series.

10. In paragraph 9, The above resonant part includes a resonant capacitor, A power conversion device in which the above resonant capacitor is connected between a node between the first switching element and the second switching element and one end of the primary side of the transformer.

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