Phase shift full-bridge converter, control method thereof and power supplying apparatus using the same

Abstract

An embodiment of the present invention provides a phase-shifted full-bridge converter comprising: a first leg including a first switch element and a second switch element arranged in series with the first switch element; a second leg including a third switch element and a fourth switch element arranged in series with the second switch element; a third leg including a fifth switch element and a sixth switch element arranged in series with the fifth switch element; a first transformer; a second transformer; a third transformer; and a fourth transformer, wherein the primary coils of the first and second transformers are arranged in series between the first leg and the second leg, and the primary coils of the third and fourth transformers are arranged in series between the second leg and the third leg. The invention also provides a control method thereof and a power supply device using the same.

Description

Technology Field

[0001] The present invention relates to a phase-shifted full-bridge converter with a reduced number of switching elements, a control method thereof, and a power supply device using the same. Background Technology

[0002] Recently, the need for Low-Voltage DC Converters (LDCs) for low-voltage (LV) battery charging and power supply in electric vehicle (EV) charging systems has become increasingly prominent. This is because the power requirements of EV charging systems are increasing as autonomous driving technology advances. Therefore, there is a need for high-power LDC technology for use in next-generation autonomous driving technologies.

[0003] Meanwhile, to minimize the increase in volume due to increased power capacity, it is necessary to reduce the volume of the LDC. Generally, magnetic materials such as transformers and output inductors account for about 50% of the volume of an LDC converter.

[0004] Figure 1 is a circuit diagram showing a conventional 2kW PSFB converter.

[0005] Referring to Figure 1, a 2kW LDC based on PSFB (phase shift full-bridge) is mainly applied in current electric vehicles (EVs). However, as autonomous driving technology has recently advanced rapidly, there is a demand for LDCs supplying power to autonomous driving modules to increase their power capacity from 2kW to 4kW.

[0006] To meet these requirements, attempts are generally being made to achieve a power capacity of 4kW by connecting 2kW LDCs in series and parallel structures. However, connecting LDCs in this way leads to an increase in the volume of the magnetic material, which in turn increases the overall volume of the LDC system.

[0007] Figure 2 is a circuit diagram showing a conventional 4kW PSFB converter.

[0008] Referring to FIG. 2, a converter is shown that achieves a rated capacity of 4kW by connecting two 2kW PSFB converters illustrated in FIG. 1 in parallel. While the 2kW PSFB converter uses four switching elements on the primary side, the number of primary side switches in the 4kW PSFB converter of FIG. 2 increases to eight. This results in an increase in the volume of the LDC system and a problem of rising manufacturing costs.

[0009] Meanwhile, as the battery voltage has increased to the 800V level to increase the driving range of electric vehicles, the input voltage range of the LDC has expanded to the 400~800V level. Therefore, there is a need for a method to handle a wide input / output voltage range and reduce the size and cost. The problem to be solved

[0010] To solve such problems, the purpose of the embodiment of the present invention is to provide a phase-shifted full-bridge converter with a reduced number of switching elements. means of solving the problem

[0011] An embodiment of the present invention provides a phase-shifted full-bridge converter comprising: a first leg including a first switch element and a second switch element arranged in series with the first switch element; a second leg including a third switch element and a fourth switch element arranged in series with the second switch element; a third leg including a fifth switch element and a sixth switch element arranged in series with the fifth switch element; a first transformer; a second transformer; a third transformer; and a fourth transformer, wherein the primary coils of the first and second transformers are arranged in series between the first leg and the second leg, and the primary coils of the third and fourth transformers are arranged in series between the second leg and the third leg.

[0012] An embodiment of the present invention provides a phase-shifted full-bridge converter in which the first switch element is positioned at the top of the first leg, the second switch element is positioned at the bottom of the first leg, the third switch element is positioned at the top of the second leg, the fourth switch element is positioned at the bottom of the second leg, the fifth switch element is positioned at the top of the third leg, and the sixth switch element is positioned at the bottom of the third leg; the primary coils of the first and second transformers are positioned between the first contact of the first switch element and the second switch element and the second contact of the third switch element and the fourth switch element; and the primary coils of the third and fourth transformers are positioned between the second contact of the third switch element and the fourth switch element and the third contact of the fifth switch element and the sixth switch element.

[0013] An embodiment of the present invention provides a phase-shifted full-bridge converter in which, when the input voltage is a first voltage, the first leg and the third leg can each perform complementary switching and the second leg can perform complementary switching with a phase delayed compared to the first leg and the third leg, and when the input voltage is a second voltage, the first leg and the third leg can each perform complementary switching and the first leg can be phase-leading compared to the third leg.

[0014] An embodiment of the present invention provides a phase-shifted full-bridge converter in which the first voltage may be a voltage lower than the second voltage.

[0015] An embodiment of the present invention provides a phase-shifted full-bridge converter in which the first voltage may be 400V or more and less than 600V, and the second voltage may be 600V or more and less than 800V.

[0016] An embodiment of the present invention provides a phase-shifted full-bridge converter in which, at the first voltage, the primary coil of the first transformer and the primary coil of the second transformer may be electrically connected in series, the primary coil of the third transformer and the primary coil of the fourth transformer may be electrically connected in series, and the primary coil of the first transformer and the primary coil of the second transformer, the primary coil of the third transformer, and the primary coil of the fourth transformer may be electrically connected in parallel with each other, and at the second voltage, the primary coil of the first transformer, the primary coil of the second transformer, the primary coil of the third transformer, and the primary coil of the fourth transformer may be electrically connected in series.

[0017] An embodiment of the present invention provides a phase-shifted full-bridge converter capable of transferring power to the secondary side through the magnetic cores of the first transformer and the fourth transformer when the first switch element, the fourth switch element, and the fifth switch element are turned on at the first voltage.

[0018] An embodiment of the present invention provides a phase-shifted full-bridge converter in which, when the second switch element, the fourth switch element, and the sixth switch element are turned on at the first voltage, magnetic field energy stored in the second and third transformers is discharged and recirculation can occur.

[0019] An embodiment of the present invention provides a phase-shifted full-bridge converter capable of transferring power to the secondary side through the magnetic cores of the second transformer and the third transformer when the second switch element, the third switch element, and the sixth switch element are turned on at the first voltage.

[0020] An embodiment of the present invention provides a phase-shifted full-bridge converter in which recirculation can occur when the first switch element, the third switch element, and the fifth switch element are turned on at the first voltage.

[0021] An embodiment of the present invention provides a phase-shifted full-bridge converter capable of transferring power to the secondary side through the magnetic cores of the first transformer and the third transformer when the third switch element and the fourth switch element are turned off at the second voltage and the first switch element and the sixth switch element are turned on.

[0022] An embodiment of the present invention provides a phase-shifted full-bridge converter in which, when the third switch element and the fourth switch element are turned off at the second voltage and the second switch element and the sixth switch element are turned on, magnetic field energy stored in the second and fourth transformers is discharged and recirculation can occur.

[0023] An embodiment of the present invention provides a phase-shifted full-bridge converter capable of transferring power to the secondary side through the magnetic cores of the second transformer and the fourth transformer when the third switch element and the fourth switch element are turned off at the second voltage and the second switch element and the fifth switch element are turned on.

[0024] An embodiment of the present invention provides a phase-shifted full-bridge converter in which, at the second voltage, the third switch element and the fourth switch element are turned off, and the first switch element and the fifth switch element are turned on, so that recirculation can occur.

[0025] An embodiment of the present invention provides a phase-shifted full-bridge converter comprising: a secondary coil of the first transformer, a secondary coil of the second transformer, a secondary coil of the third transformer, and a secondary coil of the fourth transformer, wherein the secondary coils are connected in parallel with each other; a first diode connected in series to the secondary coil of the first transformer; a second diode connected in series to the secondary coil of the second transformer; a third diode connected in series to the secondary coil of the third transformer; and a fourth diode connected in series to the secondary coil of the fourth transformer.

[0026] An embodiment of the present invention provides a phase-shifted full-bridge converter in which the primary side of the phase-shifted full-bridge converter is configured as shown in Circuit Diagram 1.

[0027] [Circuit Diagram 1]

[0028]

[0029] An embodiment of the present invention provides a control method for a phase-shifted full-bridge converter comprising: a first leg including a first switch element and a second switch element arranged in series with the first switch element; a second leg including a third switch element and a fourth switch element arranged in series with the second switch element; a third leg including a fifth switch element and a sixth switch element arranged in series with the fifth switch element; a first transformer; a second transformer; a third transformer; and a fourth transformer, wherein when the input voltage is a first voltage, the first leg and the third leg each perform complementary switching, and the second leg performs complementary switching with a phase delayed compared to the first leg and the third leg; and when the input voltage is a second voltage, the first leg and the third leg each perform complementary switching, and the first leg has a phase leading compared to the third leg.

[0030] An embodiment of the present invention provides a control method for a phase-shifted full-bridge converter, wherein the first voltage is a voltage lower than the second voltage.

[0031] An embodiment of the present invention provides a control method for a phase-shifted full-bridge converter, wherein at the first voltage, the primary coil of the first transformer and the primary coil of the second transformer are electrically connected in series, the primary coil of the third transformer and the primary coil of the fourth transformer are electrically connected in series, the primary coil of the first transformer and the primary coil of the second transformer, the primary coil of the third transformer and the primary coil of the fourth transformer are electrically connected in parallel to each other, and at the second voltage, the primary coil of the first transformer, the primary coil of the second transformer, the primary coil of the third transformer, and the primary coil of the fourth transformer are electrically connected in series.

[0032] An embodiment of the present invention provides a power supply comprising the phase-shifted full-bridge converter described above. Effects of the invention

[0033] According to an embodiment of the present invention, the number of switch elements is reduced, thereby reducing the size of the converter.

[0034] In addition, according to an embodiment of the present invention, the cost of manufacturing a converter can be reduced due to a reduction in the number of switch elements.

[0035] In addition, according to an embodiment of the present invention, a wide input / output voltage range can be accommodated. Brief explanation of the drawing

[0036] Figure 1 is a circuit diagram showing a conventional 2kW PSFB converter. Figure 2 is a circuit diagram showing a conventional 4kW PSFB converter. FIG. 3 is a circuit diagram showing the primary side of a PSFB converter according to an embodiment of the present invention. FIG. 4 is a circuit diagram showing the secondary side of a PSFB converter according to an embodiment of the present invention. FIG. 5 is a circuit diagram showing a PSFB converter according to an embodiment of the present invention. Figure 6 is a timing diagram showing the parallel operation waveform of a PSFB converter according to an embodiment of the present invention. FIG. 7 is a circuit diagram showing the current flow in the first time mode of parallel operation of a PSFB converter according to an embodiment of the present invention. FIG. 8 is a circuit diagram showing the current flow in the second time mode of parallel operation of a PSFB converter according to an embodiment of the present invention. FIG. 9 is a circuit diagram showing the current flow in the third time mode of parallel operation of a PSFB converter according to an embodiment of the present invention. FIG. 10 is a circuit diagram showing the current flow in the fourth time mode of parallel operation of a PSFB converter according to an embodiment of the present invention. FIG. 11 is a timing diagram showing the serial operation waveform of a PSFB converter according to an embodiment of the present invention. FIG. 12 is a circuit diagram showing the current flow in the first time mode of serial operation of a PSFB converter according to an embodiment of the present invention. FIG. 13 is a circuit diagram showing the current flow in the second time mode of serial operation of a PSFB converter according to an embodiment of the present invention. FIG. 14 is a circuit diagram showing the current flow in the third time mode of serial operation of a PSFB converter according to an embodiment of the present invention. FIG. 15 is a circuit diagram showing the current flow in the fourth time mode of serial operation of a PSFB converter according to an embodiment of the present invention. FIG. 16 is a diagram showing the simulation results of a PSFB converter according to an embodiment of the present invention. FIG. 17 is a diagram showing another simulation result of a PSFB converter according to an embodiment of the present invention. FIG. 18 is a diagram showing another simulation result of a PSFB converter according to an embodiment of the present invention. FIG. 19 is a diagram showing another simulation result of a PSFB converter according to an embodiment of the present invention. Specific details for implementing the invention

[0037] Hereinafter, embodiments disclosed in this specification will be described in detail with reference to the attached drawings. Identical or similar components are assigned the same reference number regardless of drawing symbols, and redundant descriptions thereof will be omitted. The suffixes "module" and "part" used for components in the following description are assigned or used interchangeably solely for the ease of drafting the specification and do not inherently possess distinct meanings or roles.

[0038] In this description, expressions such as “include,” “equip,” or “compose” are intended to refer to certain characteristics, numbers, steps, actions, elements, parts or combinations thereof, and should not be interpreted to exclude the existence or possibility of one or more other characteristics, numbers, steps, actions, elements, parts or combinations thereof other than those described.

[0039] In addition, when describing the embodiments disclosed in this specification, if it is determined that a detailed description of related prior art could obscure the essence of the embodiments disclosed in this specification, such detailed description is omitted.

[0040] The attached drawings are intended only to facilitate understanding of the embodiments disclosed in this specification, and the technical concept disclosed in this specification is not limited by the attached drawings; it should be understood that all modifications, equivalents, and substitutions included within the concept and technical scope of the present invention are included.

[0041] Below, embodiments of the present invention will be described in detail with reference to the drawings.

[0042] FIG. 3 is a circuit diagram showing the primary side of a PSFB converter according to an embodiment of the present invention, FIG. 4 is a circuit diagram showing the secondary side of a PSFB converter according to an embodiment of the present invention, and FIG. 5 is a circuit diagram showing a PSFB converter according to an embodiment of the present invention.

[0043] Referring to FIGS. 3 to 5, a PSFB converter according to an embodiment of the present invention comprises switching elements (Q1 to Q6), transformers (T1 to T4), and diodes (D1 to D4). Each transformer (T1 to T4) has a primary coil (primary coil or primary winding) and a secondary coil (secondary coil or secondary winding) magnetically coupled to the primary coil. The primary coil has a magnetization inductance component (Lm) and a leakage inductance component (L lkg has ).

[0044] The primary side of the PSFB converter may be composed of three legs. Each leg may have two switches located at the top and bottom to perform complementary switching. Specifically, a first switch element (Q1) may be located at the top of the first leg (Leg1) and a second switch element (Q2) may be located at the bottom. A third switch element (Q3) may be located at the top of the second leg (Leg2) and a fourth switch element (Q4) may be located at the bottom. A fifth switch element (Q5) may be located at the top of the third leg (Leg3) and a sixth switch element (Q6) may be located at the bottom. The first to sixth switch elements (Q1 to Q6) are sequentially turned on or off according to a control signal and perform the necessary power conversion.

[0045] The primary coils of four transformers (T1 to T4) may be arranged on the primary side of the PSFB converter. The primary coils of the first transformer (T1) and the second transformer (T2) are connected in series. At this time, the primary coils of the first and second transformers (T1, T2) may be arranged in series between the first leg and the second leg. The primary coil of the first transformer (T1) and the primary coil of the second transformer (T2) may be arranged between a first contact (N1) located in the first leg and a second contact (N2) located in the second leg. The first contact (N1) is the contact between the first switch element (Q1) and the second switch element (Q2), and the second contact (N2) is the contact between the third switch element (Q3) and the fourth switch element (Q4). In addition, the first series additional inductor (L S1 ) can be connected in series to the primary coils of the first and second transformers (T1, T2).

[0046] The primary coil of the third transformer (T1) and the primary coil of the fourth transformer (T2) are connected in series. At this time, the primary coils of the third and fourth transformers (T3, T4) may be arranged in series between the second leg and the third leg. The primary coil of the third transformer (T3) and the primary coil of the fourth transformer (T4) may be arranged between the second contact (N2) located in the second leg and the third contact (N3) located in the third leg. The second contact (N2) is the contact between the third switch element (Q3) and the fourth switch element (Q4), and the third contact (N2) is the contact between the fifth switch element (Q5) and the sixth switch element (Q6). In addition, the second series additional inductor (L S2 ) can be connected in series to the primary coils of the third and fourth transformers (T3, T4). As shown in FIG. 3, the four transformers (T1 to T4) can be connected in a 2 series 2 parallel structure.

[0047] A first magnetizing inductor (L) to the primary coil of the first transformer (T1). m1) is connected in parallel, and a second magnetizing inductor (L) is connected to the primary coil of the second transformer (T2). m2 ) is connected in parallel, and a third magnetizing inductor (L) is connected to the primary coil of the third transformer (T3). m3 ) is connected in parallel, and the fourth magnetizing inductor (L) is connected to the primary coil of the fourth transformer (T4). m4 ) can be connected in parallel.

[0048] The first to sixth switch elements (Q1 to Q6) may be MOSFET (metal-oxide-semiconductor field effect transistor) switch elements. The switch elements (Q1 to Q6) may be composed of insulated gate type FETs, and more specifically, may be composed of N-channel enhancement type MOSFETs. In this case, the drains of the first switch element (Q1), the third switch element (Q3), and the fifth switch element (Q5) may be connected to the positive terminal of the DC power source (Vs), and the sources of the second switch element (Q2), the fourth switch element (Q4), and the sixth switch element (Q6) may be connected to the negative terminal of the DC power source (Vs).

[0049] Additionally, the source of the first switch element (Q1) can be connected to the drain of the second switch element (Q2), the source of the third switch element (Q3) can be connected to the drain of the fourth switch element (Q2), and the source of the fifth switch element (Q5) can be connected to the drain of the sixth switch element (Q6).

[0050] The first and second switch elements (Q1, Q2) can operate alternately at a variable switching frequency with a duty ratio of 50%, the third and fourth switch elements (Q3, Q4) can operate alternately at a variable switching frequency with a duty ratio of 50%, and the fifth and sixth switch elements (Q5, Q6) can operate alternately at a variable switching frequency with a duty ratio of 50%.

[0051] In addition, the secondary side of the PSFB converter may form a closed circuit by connecting the secondary coils of the first to fourth transformers (T1 to T4), the first to fourth diodes (D1 to D4), and the output capacitor (Co). The output capacitor (Co) may be a smoothing capacitor. A resistor-type output load (Ro) forming the output terminal may be connected in parallel with the smoothing capacitor (Co).

[0052] The secondary coils of the four transformers (T1 to T4) placed on the secondary side of the PSFB converter can be connected in parallel. Specifically, the secondary coil of the first transformer (T1), the secondary coil of the second transformer (T2), the secondary coil of the third transformer (T3), and the secondary coil of the fourth transformer (T4) can be connected in parallel.

[0053] Additionally, the first diode (D1) may be connected in series with the secondary coil of the first transformer (T1), the second diode (D2) may be connected in series with the secondary coil of the second transformer (T2), the third diode (D3) may be connected in series with the secondary coil of the third transformer (T3), and the fourth diode (D4) may be connected in series with the secondary coil of the fourth transformer (T4).

[0054] The coil winding ratio of the first transformer (T1) is n1, the coil winding ratio of the second transformer (T2) is n2, the coil winding ratio of the third transformer (T3) is n3, and the coil winding ratio of the fourth transformer (T4) is n4. At this time, the ratio of the number of primary windings to the number of secondary windings (n1, n2, n3, n4) may be n:1.

[0055] The first transformer (T1) and the second transformer (T2) are integrated transformers (T) to which an integrated magnetic material is applied. int1 ) and the third transformer (T3) and the fourth transformer (T4) are also integrated transformers (T) to which an integrated magnetic material is applied. int2 It can be ). In this case, the integrated transformer (T int1 , T int2 The coil winding ratio of ) can also be n:1.

[0056] A power supply device according to an embodiment of the present invention may further include a control unit (not shown), an EMI filter (not shown), etc.

[0057] The meaning of each symbol in the present invention is as follows.

[0058] V ds1 : Voltage between the drain and source of the first switch element (Q1)

[0059] V ds2 : Voltage between the drain and source of the second switch element (Q2)

[0060] V ds3 : Voltage between the drain and source of the third switch element (Q3)

[0061] V ds4 : Voltage between the drain and source of the fourth switch element (Q4)

[0062] V ds5 : Voltage between the drain and source of the fifth switch element (Q5)

[0063] V ds6 : Voltage between the drain and source of the 6th switch element (Q6)

[0064] i Llkg leakage inductance current

[0065] V Lm1 : Voltage applied to the first magnetization inductor (Lm1) on the primary side of the first transformer

[0066] V Lm2: Voltage applied to the second magnetization inductor (Lm2) on the primary side of the second transformer

[0067] V Lm3 : Voltage across the third magnetization inductor (Lm3) on the primary side of the third transformer

[0068] V Lm4 : Voltage across the fourth magnetization inductor (Lm4) on the primary side of the fourth transformer

[0069] i D1 : Current flowing through the first diode (D1)

[0070] i D2 : Current flowing through the second diode (D2)

[0071] i D3 : Current flowing through the third diode (D3)

[0072] i D4 : Current flowing through the fourth diode (D4)

[0073] V D1 : Voltage across the first diode (D1)

[0074] V D2 : Voltage across the second diode (D2)

[0075] V D3 : Voltage across the third diode (D3)

[0076] V D4 : Voltage across the fourth diode (D4)

[0077] i o : Output current flowing from the output terminal to the load

[0078] V o : DC output voltage

[0080] The PSFB converter according to an embodiment of the present invention has a switching operation that varies depending on the input voltage condition and can be classified into parallel and series modes. It can operate in parallel at a low input voltage and in series at a high input voltage. The low input voltage may be, for example, Vs 400V or more and less than 600V, and the high input voltage may be, for example, Vs 600V or more and less than 800V.

[0081] FIG. 6 is a timing diagram showing the parallel operation waveform of a PSFB converter according to an embodiment of the present invention, and FIG. 7 to 10 are circuit diagrams showing the current flow of the first to fourth time modes of parallel operation of a PSFB converter according to an embodiment of the present invention.

[0082] In the case of parallel mode, the first leg and the third leg can perform complementary switching with the same phase. Additionally, the second leg can perform complementary switching with a phase delayed compared to the first leg and the third leg. Specifically, the first and second switch elements (Q1, Q2) of the first leg operate alternately at a variable switching frequency with a duty ratio of 50%, and the fifth and sixth switch elements (Q5, Q6) of the third leg operate alternately at a variable switching frequency with a duty ratio of 50%.

[0083] Additionally, the third and fourth switch elements (Q3, Q4) of the second leg can operate alternately with each other at a variable switching frequency with a duty cycle of 50%. At this time, the third and fourth switch elements (Q3, Q4) of the second leg may have a phase delay compared to the switch elements (Q1, Q2, Q3, Q4) of the first and third legs. Through this, the 2-series 2-parallel structure of the transformer is activated, and power transfer can be achieved.

[0084] Below, the parallel mode is explained in detail.

[0085] In parallel mode, the first to sixth switch elements (Q1 to Q6) alternately turn on / off to convert input power into output.

[0086] FIG. 7 is a circuit diagram showing the current flow of the first mode of parallel operation of a PSFB converter according to an embodiment of the present invention.

[0087] Referring to FIG. 7, the current flow in the first time mode (t0 to t1) of parallel operation is shown. The first switch element (Q1) of the first leg, the fourth switch element (Q4) of the second leg, and the fifth switch element (Q5) of the third leg are turned on, and power is transferred to the secondary side through the magnetic cores of the first transformer (T1) and the fourth transformer (T4).

[0088] In the first time mode, a conduction path and current flow are formed as indicated by the dotted arrows shown in FIG. 7. Specifically, the primary coil of the first transformer (T1) and the primary coil of the fourth transformer (T4) are electrically connected in parallel. In the first time mode, the first diode (D1) and the fourth diode (D4) conduct.

[0089] FIG. 8 is a circuit diagram showing the current flow of the second mode of parallel operation of a PSFB converter according to an embodiment of the present invention.

[0090] Referring to FIG. 8, the current flow in the second time mode (t2~t3) of parallel operation is shown. The second switch element (Q2) of the first leg, the fourth switch element (Q4) of the second leg, and the sixth switch element (Q6) of the third leg are turned on, and a recirculation section occurs on the primary side.

[0091] In the second time mode, a conduction path and current flow are formed as indicated by the dotted arrows shown in FIG. 8. Specifically, the primary coil of the first transformer (T1) and the primary coil of the second transformer (T2) are electrically connected in series, and the primary coil of the third transformer (T3) and the primary coil of the fourth transformer (T4) are electrically connected in series. At this time, the 'primary coil of the first transformer (T1) and the primary coil of the second transformer (T2)' and the 'primary coil of the third transformer (T3) and the primary coil of the fourth transformer (T4)' are electrically connected in parallel with each other.

[0092] In the second time mode, power is transferred to the secondary side through the magnetic cores of the first transformer (T1) to the fourth transformer (T4), and the first diode (D1) to the fourth diode (D4) conduct. Additionally, a negative voltage is applied to the second transformer (T2) and the third transformer (T3), and the second magnetizing inductor (L m2 ) and third magnetizing inductor (L m3 The reset operation is performed as the magnetic field energy stored in ) is discharged.

[0093] FIG. 9 is a circuit diagram showing the current flow of the third mode of parallel operation of a PSFB converter according to an embodiment of the present invention.

[0094] Referring to FIG. 9, the current flow in the third time mode (t4 to t5) of parallel operation is shown. The second switch element (Q2) of the first leg, the third switch element (Q3) of the second leg, and the sixth switch element (Q6) of the third leg are turned on, and power is transferred to the secondary side through the magnetic cores of the second transformer (T2) and the third transformer (T3).

[0095] In the third time mode, a conduction path and current flow are formed as indicated by the dashed arrows shown in FIG. 9. Specifically, the primary coil of the second transformer (T2) and the primary coil of the third transformer (T3) are electrically connected in parallel. In the third time mode, the second diode (D2) and the third diode (D3) conduct. Additionally, the first magnetizing inductor (L m1 ) and the fourth magnetizing inductor (L m4 The reset operation is performed as the magnetic field energy stored in ) is discharged.

[0096] FIG. 10 is a circuit diagram showing the current flow of the fourth mode of parallel operation of a PSFB converter according to an embodiment of the present invention.

[0097] Referring to FIG. 10, the current flow in the parallel operation fourth time mode (t6~t7) is shown. The first switch element (Q1) of the first leg, the third switch element (Q3) of the second leg, and the fifth switch element (Q5) of the third leg are turned on, and a recirculation section occurs on the primary side.

[0098] In the fourth time mode, a conduction path and current flow are formed as indicated by the dotted arrow shown in FIG. 10. Specifically, the primary coil of the first transformer (T1) and the primary coil of the second transformer (T2) are electrically connected in series, and the primary coil of the third transformer (T3) and the primary coil of the fourth transformer (T4) are electrically connected in series. At this time, the 'primary coil of the first transformer (T1) and the primary coil of the second transformer (T2)' and the 'primary coil of the third transformer (T3) and the primary coil of the fourth transformer (T4)' are electrically connected in parallel with each other.

[0099] In the fourth time mode, power is transferred to the secondary side through the magnetic cores of the first transformer (T1) to the fourth transformer (T4), and the first diode (D1) to the fourth diode (D4) conduct.

[0100] FIG. 11 is a timing diagram showing the serial operation waveform of a PSFB converter according to an embodiment of the present invention, and FIG. 12 to 15 are circuit diagrams showing the current flow of the serial operation first to fourth time modes of a PSFB converter according to an embodiment of the present invention.

[0101] In serial mode, the second leg does not operate. Only the first and third legs can perform switching. The first and third legs can operate in the same way as a standard PSFB converter, and the phase of the first leg can lead the third leg. Specifically, the first and second switching elements (Q1, Q2) of the first leg operate alternately at a variable switching frequency with a duty ratio of 50%, and the fifth and sixth switching elements (Q5, Q6) of the third leg operate alternately at a variable switching frequency with a duty ratio of 50%.

[0102] At this time, the first and second switch elements (Q1, Q2) of the first leg may be in phase ahead of the fifth and sixth switch elements (Q5, Q6) of the third leg. Through this, the transformers are connected in a four-series structure, and power transfer efficiency can be increased while reducing voltage drop. In series mode, the coils of all transformers (T1, T2, T3, T4) are connected in series, allowing for stable power transfer even at high voltages.

[0103] FIG. 12 is a circuit diagram showing the current flow in the first time mode of serial operation of a PSFB converter according to an embodiment of the present invention.

[0104] Referring to FIG. 12, the current flow in the first time mode (t0 to t1) of the serial operation is shown. The first switch element (Q1) of the first leg and the sixth switch element (Q6) of the third leg are turned on, and power is transferred to the secondary side through the magnetic cores of the first transformer (T1) and the third transformer (T3).

[0105] In the first time mode, a conduction path and current flow are formed as indicated by the dotted arrows in FIG. 12. Specifically, the primary coil of the first transformer (T1) and the primary coil of the third transformer (T3) are electrically connected in series. In the first time mode, the first diode (D1) and the third diode (D3) conduct.

[0106] FIG. 13 is a circuit diagram showing the current flow in the second time mode of serial operation of a PSFB converter according to an embodiment of the present invention.

[0107] Referring to FIG. 13, the current flow in the second time mode (t2~t3) of the serial operation is shown. The second switch element (Q2) of the first leg and the sixth switch element (Q6) of the third leg are turned on, and a recirculation section occurs on the primary side.

[0108] In the second time mode, a conduction path and current flow are formed as indicated by the dotted arrow shown in FIG. 13. Specifically, the primary coil of the first transformer (T1), the primary coil of the second transformer (T2), the primary coil of the third transformer (T3), and the primary coil of the fourth transformer (T4) are electrically connected in series.

[0109] In the second time mode, power is transferred to the secondary side through the magnetic cores of the first transformer (T1) to the fourth transformer (T4), and the first diode (D1) to the fourth diode (D4) conduct. Additionally, a negative voltage is applied to the second transformer (T2) and the third transformer (T3), and the second magnetizing inductor (L m2 ) and the fourth magnetizing inductor (L m4 The reset operation is performed as the magnetic field energy stored in ) is discharged.

[0110] FIG. 14 is a circuit diagram showing the current flow in the third time mode of serial operation of a PSFB converter according to an embodiment of the present invention.

[0111] Referring to FIG. 14, the current flow in the third time mode (t4 to t5) of the serial operation is shown. The second switch element (Q2) of the first leg and the fifth switch element (Q6) of the third leg are turned on, and power is transferred to the secondary side through the magnetic cores of the second transformer (T2) and the fourth transformer (T4).

[0112] In the third time mode, a conduction path and current flow are formed as indicated by the dashed arrows shown in FIG. 14. Specifically, the primary coil of the second transformer (T2) and the primary coil of the fourth transformer (T4) are electrically connected in series. In the third time mode, the second diode (D2) and the fourth diode (D4) conduct. Additionally, the first magnetizing inductor (L m1 ) and third magnetizing inductor (L m3 The reset operation is performed as the magnetic field energy stored in ) is discharged.

[0113] FIG. 15 is a circuit diagram showing the current flow in the fourth time mode of serial operation of a PSFB converter according to an embodiment of the present invention.

[0114] Referring to FIG. 15, the current flow in the fourth time mode (t6~t7) of the serial operation is shown. The first switch element (Q1) of the first leg and the fifth switch element (Q5) of the third leg are turned on, and a recirculation section occurs on the primary side.

[0115] In the fourth time mode, a conduction path and current flow are formed as indicated by the dotted arrows shown in FIG. 15. Specifically, the primary coil of the first transformer (T1), the primary coil of the second transformer (T2), the primary coil of the third transformer (T3), and the primary coil of the fourth transformer (T4) are electrically connected in series. In the fourth time mode, power is transferred to the secondary side through the magnetic cores of the first transformer (T1) to the fourth transformer (T4), and the first diode (D1) to the fourth diode (D4) conduct.

[0116] FIG. 16 is a diagram showing the simulation results of a PSFB converter according to an embodiment of the present invention.

[0117] Referring to Fig. 16, the input voltage of 440V was converted to an output voltage of 12.5V. The circuit parameters for the converter design are as shown in Table 1 below.

[0118] parameters value Input voltage (Vs) 440V Output voltage (Vo) and power (Po) 12.5V, 4kW switching frequency (fs) 200kHz Magnetizing inductance (Lm1, Lm2, Lm3, Lm4) 45μH Leakage inductance (Llkg1, Llkg2) 1.5μH Switching parasitic capacitance (Coss) 100pF

[0119] FIG. 17 is a diagram showing another simulation result of a PSFB converter according to an embodiment of the present invention.

[0120] Referring to Fig. 17, the input voltage of 440V was converted to an output voltage of 15.1V. The circuit parameters for the converter design are as shown in Table 2 below.

[0121] parameters value Input voltage (Vs) 440V Output voltage (Vo) and power (Po) 15.1V, 4kW switching frequency (fs) 200kHz Magnetizing inductance (Lm1, Lm2, Lm3, Lm4) 45μH Leakage inductance (Llkg1, Llkg2) 1.5μH Switching parasitic capacitance (Coss) 100pF

[0122] FIG. 18 is a diagram showing another simulation result of a PSFB converter according to an embodiment of the present invention.

[0123] Referring to Fig. 18, the input voltage of 826V was converted to an output voltage of 12.5V. The circuit parameters for the converter design are as shown in Table 3 below.

[0124] parameters value Input voltage (Vs) 826V Output voltage (Vo) and power (Po) 12.5V, 4kW switching frequency (fs) 200kHz Magnetizing inductance (Lm1, Lm2, Lm3, Lm4) 45μH Leakage inductance (Llkg1, Llkg2) 1.5μH Switching parasitic capacitance (Coss) 100pF

[0125] FIG. 19 is a diagram showing another simulation result of a PSFB converter according to an embodiment of the present invention.

[0126] Referring to Fig. 19, the input voltage of 826V was converted to an output voltage of 15.1V. The circuit parameters for the converter design are as shown in Table 4 below.

[0127] parameters value Input voltage (Vs) 826V Output voltage (Vo) and power (Po) 15.1V, 4kW switching frequency (fs) 200kHz Magnetizing inductance (Lm1, Lm2, Lm3, Lm4) 45μH Leakage inductance (Llkg1, Llkg2) 1.5μH Switching parasitic capacitance (Coss) 100pF

[0128] As described above, the present invention has been explained by specific details such as specific components, limited embodiments, and drawings; however, these are provided merely to aid in a more comprehensive understanding of the invention, and the invention is not limited to the above embodiments. A person skilled in the art to which the invention pertains will be able to make various modifications and variations within the scope of the essential characteristics of the invention. Accordingly, the concept of the present invention should not be limited to the described embodiments, and all technical concepts that are equivalent to or have equivalent variations to the claims set forth below, as well as the claims themselves, should be interpreted as being included within the scope of the rights of the present invention. Furthermore, each of the above embodiments may be combined and operated as needed. Explanation of the symbols

[0129] T1, T2, T3, T4: Transformers Q1, Q2, Q3, Q4, Q5, Q6: Switch elements D1, D2, D3, D4: Diodes

Claims

Claim 1 A first leg comprising a first switch element and a second switch element arranged in series with the first switch element; a second leg comprising a third switch element and a fourth switch element arranged in series with the third switch element; a third leg comprising a fifth switch element and a sixth switch element arranged in series with the fifth switch element; a first transformer; a second transformer; a third transformer; A phase-shifted full-bridge converter comprising a first and second transformer and a fourth transformer, wherein the primary coils of the first and second transformers are arranged in series between the first leg and the second leg, the primary coils of the third and fourth transformers are arranged in series between the second leg and the third leg, and when the input voltage is a first voltage, the first leg and the third leg can each perform complementary switching, and the second leg can perform complementary switching with a phase delayed compared to the first leg and the third leg, and when the input voltage is a second voltage, the first leg and the third leg can each perform complementary switching, and the first leg can be in phase leading compared to the third leg, and the first voltage can be a lower voltage than the second voltage. Claim 2 A phase-shifted full-bridge converter according to claim 1, wherein the first switch element is positioned at the top of the first leg, the second switch element is positioned at the bottom of the first leg, the third switch element is positioned at the top of the second leg, the fourth switch element is positioned at the bottom of the second leg, the fifth switch element is positioned at the top of the third leg, and the sixth switch element is positioned at the bottom of the third leg; the primary coil of the first transformer and the primary coil of the second transformer are positioned between the first switch element and the first contact of the second switch element and the second contact of the third switch element and the fourth switch element; and the primary coil of the third transformer and the primary coil of the fourth transformer are positioned between the third switch element and the second contact of the fourth switch element and the third contact of the fifth switch element and the sixth switch element. Claim 3 delete Claim 4 delete Claim 5 A phase-shifted full-bridge converter according to claim 1, wherein the first voltage is 400V or more and less than 600V, and the second voltage is 600V or more and 800V or less. Claim 6 A phase-shifted full-bridge converter according to claim 1, wherein at the first voltage, the primary coil of the first transformer and the primary coil of the second transformer may be electrically connected in series, the primary coil of the third transformer and the primary coil of the fourth transformer may be electrically connected in series, and the primary coil of the first transformer and the primary coil of the second transformer and the primary coil of the third transformer and the primary coil of the fourth transformer may be electrically connected in parallel with each other, and at the second voltage, the primary coil of the first transformer, the primary coil of the second transformer, the primary coil of the third transformer and the primary coil of the fourth transformer may be electrically connected in series. Claim 7 A phase-shifted full-bridge converter according to claim 1, capable of transferring power to the secondary side through the magnetic cores of the first transformer and the fourth transformer when the first switch element, the fourth switch element, and the fifth switch element are turned on at the first voltage. Claim 8 A phase-shifted full-bridge converter according to claim 1, wherein when the second switch element, the fourth switch element, and the sixth switch element are turned on at the first voltage, magnetic field energy stored in the second and third transformers is discharged and recirculation can occur. Claim 9 A phase-shifted full-bridge converter according to claim 1, capable of transferring power to the secondary side through the magnetic cores of the second transformer and the third transformer when the second switch element, the third switch element, and the sixth switch element are turned on at the first voltage. Claim 10 A phase-shifted full-bridge converter according to claim 1, wherein when the first switch element, the third switch element, and the fifth switch element are turned on at the first voltage, a recirculation may occur. Claim 11 A phase-shifted full-bridge converter according to claim 1, wherein when the third switch element and the fourth switch element are turned off at the second voltage and the first switch element and the sixth switch element are turned on, power can be transferred to the secondary side through the magnetic cores of the first transformer and the third transformer. Claim 12 A phase-shifted full-bridge converter according to claim 1, wherein when the third switch element and the fourth switch element are turned off at the second voltage and the second switch element and the sixth switch element are turned on, magnetic field energy stored in the second and fourth transformers is discharged and recirculation can occur. Claim 13 A phase-shifted full-bridge converter according to claim 1, wherein when the third switch element and the fourth switch element are turned off at the second voltage and the second switch element and the fifth switch element are turned on, power can be transferred to the secondary side through the magnetic cores of the second transformer and the fourth transformer. Claim 14 A phase-shifted full-bridge converter according to claim 1, wherein when the third switch element and the fourth switch element are turned off at the second voltage and the first switch element and the fifth switch element are turned on, a recirculation may occur. Claim 15 A phase-shifted full-bridge converter according to claim 1, wherein the secondary coil of the first transformer, the secondary coil of the second transformer, the secondary coil of the third transformer, and the secondary coil of the fourth transformer are connected in parallel with each other, and the converter comprises a first diode connected in series with the secondary coil of the first transformer, a second diode connected in series with the secondary coil of the second transformer, a third diode connected in series with the secondary coil of the third transformer, and a fourth diode connected in series with the secondary coil of the fourth transformer. Claim 16 delete Claim 17 A control method for a phase-shifted full-bridge converter comprising: a first leg including a first switch element and a second switch element arranged in series with the first switch element; a second leg including a third switch element and a fourth switch element arranged in series with the second switch element; a third leg including a fifth switch element and a sixth switch element arranged in series with the fifth switch element; a first transformer; a second transformer; a third transformer; and a fourth transformer, wherein when the input voltage is a first voltage, the first leg and the third leg each perform complementary switching, and the second leg performs complementary switching with a phase delayed compared to the first leg and the third leg; and when the input voltage is a second voltage, the first leg and the third leg each perform complementary switching, and the first leg has a phase leading compared to the third leg, and the first voltage is a lower voltage than the second voltage. Claim 18 delete Claim 19 A control method for a phase-shifted full-bridge converter according to claim 17, wherein at the first voltage, the primary coil of the first transformer and the primary coil of the second transformer are electrically connected in series, the primary coil of the third transformer and the primary coil of the fourth transformer are electrically connected in series, the primary coil of the first transformer and the primary coil of the second transformer and the primary coil of the third transformer and the primary coil of the fourth transformer are electrically connected in parallel with each other, and at the second voltage, the primary coil of the first transformer, the primary coil of the second transformer, the primary coil of the third transformer and the primary coil of the fourth transformer are electrically connected in series. Claim 20 A power supply comprising a phase-shifted full-bridge converter according to any one of claims 1, 2 and 5 through 15. Claim 21 A control method for a phase-shifted full-bridge converter according to claim 17, wherein when the first switch element, the fourth switch element, and the fifth switch element are turned on at the first voltage, power can be transferred to the secondary side through the magnetic cores of the first transformer and the fourth transformer. Claim 22 A control method for a phase-shifted full-bridge converter according to claim 17, wherein when the second switch element, the fourth switch element, and the sixth switch element are turned on at the first voltage, the magnetic field energy stored in the second and third transformers is discharged and recirculation can occur. Claim 23 A control method for a phase-shifted full-bridge converter according to claim 17, wherein when the second switch element, the third switch element, and the sixth switch element are turned on at the first voltage, power can be transferred to the secondary side through the magnetic cores of the second transformer and the third transformer. Claim 24 A control method for a phase-shifted full-bridge converter in which, in the 17th paragraph, when the first switch element, the third switch element, and the fifth switch element are turned on at the first voltage, a recirculation may occur.

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