Power converter

Abstract

Provided is a power converter including: a first leg including a first switching element and a second switching element connected in series, the first switching element and the second switching element being connected to form a first connection point; a second leg including a third switching element and a fourth switching element connected in series, the third switching element and the fourth switching element being connected to form a second connection point; a first LC resonant cavity connected between the first connection point and the second connection point; a first rectifying element and a second rectifying element as switching elements; and a coupling inductance unit which is connected to the second switching element, the third switching element, the first rectifying element, and the second rectifying element, and which has a center tap connected to a load.

Description

Technical Field

[0001] The present disclosure relates to a power converter, and in particular to a non-isolated power converter. Background Art

[0002] A power converter is an electronic device that can convert one type of current into another type of current. There are both DC power conversion and AC power conversion. Most intermediate bus converters (IBCs) provide isolation from input to output by using a transformer, and usually also require an inductor for output filtering.

[0003] In existing communication systems, isolated intermediate bus architecture is widely used for safety and power efficiency considerations. In this architecture, the input voltage of the system is first converted into an intermediate voltage by an isolated intermediate bus converter (IBC), and then converted into the voltage required by the load circuit by multiple subsequent non-isolated load point power supplies.

[0004] Since the input voltage range that the load point power supply at the back stage of the intermediate bus converter can adapt to is limited, the intermediate bus converter needs to control the output voltage within a certain range. In order to adapt to a wider input voltage, when the intermediate bus converter transforms the input voltage, the wider input voltage range will cause energy storage components such as inductors to continuously store and release more energy during the voltage conversion process, resulting in an increase in the volume and loss of the energy storage components.

[0005] However, in many new applications, non-isolated intermediate bus converters are proposed to achieve smaller size, higher efficiency and lower cost. Summary of the invention

[0006] The present disclosure is developed in view of the above situation, and an object of the present disclosure is to provide a power converter capable of achieving soft switching.

[0007] In order to achieve the above-mentioned purpose, according to the present disclosure, there is provided a power converter, comprising: a first bridge arm, which includes a first switching element and a second switching element connected in series, the first switching element being connected to the second switching element to form a first connection point; a second bridge arm, which includes a third switching element and a fourth switching element connected in series, the third switching element being connected to the fourth switching element to form a second connection point; a first LC resonant cavity connected between the first connection point and the second connection point; a first rectifying element and a second rectifying element as switching elements; and a coupled inductor unit, which is respectively connected to the second switching element, the third switching element, the first rectifying element and the second rectifying element, and a center tap is connected to a load.

[0008] In addition, according to the power converter disclosed in the present invention, the coupled inductor unit may also include a magnetically coupled first coil and a second coil and a magnetically coupled third coil and a fourth coil, the center taps of the first coil and the second coil are connected to the center taps of the third coil and the fourth coil, and are connected to the load, the first coil is connected to the second switching element, the second coil is connected to the first rectifying element, the third coil is connected to the third switching element, and the fourth coil is connected to the second rectifying element.

[0009] In addition, according to the power converter disclosed in the present invention, the coupled inductor unit may also include a magnetically coupled first coupled inductor and a second coupled inductor, one end of the first coupled inductor is connected to the second switching element and the third switching element, and is connected to the load, the other end of the first coupled inductor is connected to the first rectifying element and the second rectifying element, respectively, and the second coupled inductor is connected in series with the first LC resonant cavity between the first connection point and the second connection point.

[0010] In addition, according to the power converter disclosed in the present invention, the first coupled inductor may also include a first coil and a second coil connected in series, one end of the first coil is connected to one end of the second coil to constitute one end of the first coupled inductor, the other end of the first coil and the other end of the second coil constitute the other end of the first coupled inductor, the other end of the first coil is connected to the first rectifying element, and the other end of the second coil is connected to the second rectifying element.

[0011] In addition, according to the power converter disclosed in the present invention, the first bridge arm may also include a fifth switching element and a sixth switching element connected in series with the first switching element and the second switching element, the fifth switching element being connected to the sixth switching element to form a third connection point, the second bridge arm may also include a seventh switching element and an eighth switching element connected in series with the third switching element and the fourth switching element, the seventh switching element being connected to the eighth switching element to form a fourth connection point, the power converter may also include a second LC resonant cavity, the second LC resonant cavity being connected between the third connection point and the fourth connection point, the fifth switching element being connected to the second switching element to form a fifth connection point, the eighth switching element being connected to the third switching element to form a sixth connection point, and the coupled inductor unit being connected between the fifth connection point and the sixth connection point.

[0012] In addition, according to the power converter disclosed in the present invention, the coupled inductor unit may also include a first coil and a second coil connected in series, the center taps of the first coil and the second coil are connected to the load, the first coil is connected to the sixth connection point and to the first rectifier element, and the second coil is connected to the fifth connection point and to the second rectifier element.

[0013] In addition, according to the power converter disclosed in the present invention, the coupled inductor unit may also include a first coil and a second coil connected in series and a third coil and a fourth coil connected in series, the center taps of the first coil and the second coil are connected to the center taps of the third coil and the fourth coil, and are connected to the load, the first coil is connected to the sixth connection point, the second coil is connected to the fifth connection point, the third coil is connected to the first rectifying element, the fourth coil is connected to the second rectifying element, the first coil and the fourth coil are magnetically coupled, and the second coil and the third coil are magnetically coupled.

[0014] In addition, according to the power converter disclosed in the present invention, the first switch element group may include the first switch element, the third switch element and the second rectifier element, the second switch element group may include the second switch element, the fourth switch element and the first rectifier element, the first switch element group may be controlled to be synchronously turned on or off, the second switch element group may be controlled to be synchronously turned on or off, and the first switch element group and the second switch element group may be controlled to have equal on-duty cycles.

[0015] In addition, according to the power converter disclosed in the present invention, the first switching element group and the second switching element group can also be controlled so that their respective on-duty ratios are 50% without considering dead time, and the phases of the control signals of the first switching element group and the second switching element group differ by 180 degrees.

[0016] In addition, according to the power converter disclosed in the present invention, the first switch element group may include the first switch element, the third switch element, the sixth switch element, the eighth switch element and the second rectifier element, the second switch element group may include the second switch element, the fourth switch element, the fifth switch element, the seventh switch element and the first rectifier element, the first switch element group is controlled to be synchronously turned on or off, the second switch element group is controlled to be synchronously turned on or off, and the first switch element group and the second switch element group are controlled to have equal on-duty cycles.

[0017] In addition, according to the power converter disclosed in the present invention, the first LC resonant cavity may include a first resonant inductor and a first resonant capacitor connected in series, the second LC resonant cavity may include a second resonant inductor and a second resonant capacitor connected in series, and the capacitance of the first resonant capacitor is equal to the capacitance of the second resonant capacitor.

[0018] Furthermore, according to the power converter disclosed herein, the resonant frequency of the first LC resonant cavity, the resonant frequency of the second LC resonant cavity, and the operating frequency of the power converter may be the same.

[0019] Furthermore, according to the power converter of the present disclosure, the first coil and the second coil may have the same number of turns.

[0020] Furthermore, according to the power converter of the present disclosure, the first coil, the second coil, the third coil, and the fourth coil may have the same number of turns.

[0021] Effects of the Invention

[0022] According to the present disclosure, a power converter capable of achieving soft switching can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above objects, advantages and features of the present disclosure will become more apparent through the detailed description of the preferred embodiments adopted with reference to the following combined drawings, in which:

[0024] Figure 1 This is a block diagram schematically showing the configuration structure of the main parts of the power converter according to the first embodiment of the present disclosure.

[0025] Figure 2 It is a schematic diagram schematically showing a first mode of the power converter according to Embodiment 1 of the present disclosure.

[0026] Figure 3 It is a schematic diagram schematically showing the second mode of the power converter according to the first embodiment of the present disclosure.

[0027] Figure 4 This is a block diagram schematically showing the configuration structure of the main parts of the power converter according to the second embodiment of the present disclosure.

[0028] Figure 5 This is a block diagram schematically showing the configuration structure of the main parts of the power converter according to the third embodiment of the present disclosure.

[0029] Figure 6 It is a schematic diagram schematically showing a first mode of a power converter according to Embodiment 3 of the present disclosure.

[0030] Figure 7It is a schematic diagram schematically showing the second mode of the power converter according to the third embodiment of the present disclosure.

[0031] Figure 8 It is a schematic diagram schematically showing a voltage waveform and a current waveform of a control signal in a power converter according to Embodiment 3 of the present disclosure.

[0032] Fig. 9 This is a block diagram schematically showing the configuration structure of the main parts of the power converter according to the fourth embodiment of the present disclosure.

[0033] Fig.10 It is a schematic diagram schematically showing a first mode of a power converter according to a fourth embodiment of the present disclosure.

[0034] Fig.11 It is a schematic diagram schematically showing the second mode of the power converter according to the fourth embodiment of the present disclosure. DETAILED DESCRIPTION

[0035] The present disclosure is further described in detail below in conjunction with the accompanying drawings and implementation methods. It is understood that the specific implementation methods described herein are only used to explain the relevant inventions, rather than to limit the inventions. It should also be noted that, for ease of description, only the parts related to the relevant inventions are shown in the accompanying drawings. In addition, there are cases where the same symbols are marked on the same elements and repeated descriptions are omitted. In addition, there are cases where repeated descriptions are omitted for elements with the same or corresponding functions and structures.

[0036] Hereinafter, the present disclosure will be described in detail with reference to the accompanying drawings.

[0037] (Implementation Method 1)

[0038] Figure 1 Schematically shows a block diagram of the configuration structure of the main part of the power converter according to the first embodiment of the present disclosure. Figure 1 As shown, the power converter 100 according to the first embodiment of the present disclosure includes six switching elements Q1 to Q6, a coupled inductor unit, and an LC resonant tank. In this embodiment, the switching elements may be various transistors, and the same applies to other embodiments.

[0039] like Figure 1As shown, in the first embodiment of the present disclosure, the power converter 100 includes a switching element Q1, a switching element Q2, a switching element Q3, a switching element Q4, an LC resonant cavity, a first rectifying element Z1, a second rectifying element Z2, and a coupled inductor unit 110. In addition, the first rectifying element Z1 and the second rectifying element Z2 can be switching elements. In the power converter 100 of the present embodiment, the switching element Q1 (the first switching element) and the switching element Q2 (the second switching element) connected in series can be regarded as constituting the first bridge arm, the switching element Q1 and the switching element Q2 are connected to form the first connection point Pt1, and the switching element Q3 (the third switching element) and the switching element Q4 (the fourth switching element) connected in series can be regarded as constituting the second bridge arm, and the switching element Q3 and the switching element Q4 are connected to form the second connection point Pt2. In addition, in the power converter 100 of the present embodiment, an LC resonant cavity (the first LC resonant cavity) is connected between the first connection point Pt1 and the second connection point Pt2. The LC resonant cavity includes a resonant capacitor C1 and a resonant inductor L1. Here, the resonant inductor L1 may also be formed by line parasitic inductance.

[0040] In this embodiment, the coupled inductor unit 110 is connected to the switch element Q2, the switch element Q3, the first rectifier element Z1 and the second rectifier element Z2 respectively, and the center tap is connected to the load R8. Figure 1 As shown, the coupled inductor unit 110 includes a magnetically coupled coil P1 (first coil) and a coil S1 (second coil), and a magnetically coupled coil P2 (third coil) and a coil S2 (fourth coil). In this embodiment, the center taps of the coils P1 and S1 are connected to the center taps of the coils P2 and S2, and connected to a load R8, and the coils P1 and P2 are connected in series, and the coils S1 and S2 are connected in series.

[0041] In this embodiment, for example, the coil P1 may be connected to the switch element Q2, the coil S1 may be connected to the first rectifier element Z1, the coil P2 may be connected to the switch element Q3, and the coil S2 may be connected to the second rectifier element Z2. In a preferred embodiment, the first rectifier element Z1 is connected between the coil S1 and the reference potential, and the second rectifier element Z2 is connected between the coil S2 and the reference potential. In addition, in this embodiment, the switch element Q1 may be connected to the input power supply VIN+, the switch element Q4 may be connected to the reference potential, the load R8 may be connected between the coupled inductor unit 110 and the reference potential, and the capacitor C2 may be connected in parallel with the load R8. Here, the reference potential may also be the ground potential.

[0042] In this embodiment, regarding the polarity relationship between coil P1, coil S1, coil P2, and coil S2, Figure 1Since the power converter 100 of the present embodiment is configured as a non-isolated power converter, it does not have a so-called primary side and a secondary side in a strict sense of an isolated power converter.

[0043] It should be noted that the power converter 100 of the present embodiment also includes a control circuit, which provides control signals Vg1-Vg4, VgZ1, and VgZ2 to the gates of the switching elements Q1-Q4 and the first rectifier element Z1 and the second rectifier element Z2 as the switching elements. However, since the present disclosure does not involve the specific structure of the control circuit, in order to make the description of the present disclosure clearer, its illustration is omitted and no specific description is given.

[0044] Next, the operation mode of the power converter 100 according to the present embodiment will be described.

[0045] In the power converter 100 of the present embodiment, the switch element Q1, the switch element Q3, and the second rectifying element Z2 are a group, and the corresponding control signals Vg1, Vg3, and VgZ2 are synchronized. The switch element Q2, the switch element Q4, and the first rectifying element Z1 are a group, and the corresponding control signals Vg2, Vg4, and VgZ1 are synchronized. For example, when the control signals Vg1, Vg3, and VgZ2 are high level, the control signals Vg2, Vg4, and VgZ1 are low level, and the phase difference between the control signals Vg1, Vg3, and VgZ2 and the control signals Vg2, Vg4, and VgZ1 is 180 degrees. In one half cycle, the control signals Vg1, Vg3, and VgZ2 provide a high level to turn on the switch element Q1, the switch element Q3, and the second rectifier element Z2, so that the switch element Q1, the switch element Q3, and the second rectifier element Z2 are simultaneously turned on with a 50% duty cycle. In another half cycle, the control signals Vg2, Vg4, and VgZ1 provide a high level to turn on the switch element Q2, the switch element Q4, and the first rectifier element Z1, so that the switch element Q2, the switch element Q4, and the first rectifier element Z1 are simultaneously turned on with a 50% duty cycle. It should be noted that the duty cycle here is the duty cycle without considering the dead time.

[0046] Figure 2 It is a schematic diagram schematically showing a first mode of the power converter according to Embodiment 1 of the present disclosure. Figure 2 Schematic diagram showing the flow of current when the switching element Q1 , the switching element Q3 , and the second rectifying element Z2 are turned on. Figure 3 It is a schematic diagram schematically showing the second mode of the power converter according to the first embodiment of the present disclosure. Figure 3 This is a schematic diagram showing the flow of current when the switching element Q2, the switching element Q4, and the first rectifying element Z1 are turned on.

[0047] When the switch element Q1, the switch element Q3, and the second rectifying element Z2 are turned on, Figure 2 As shown, two current loops are formed in the power converter 100. In one current loop, the current passes through the switching element Q1, through the LC resonant cavity formed by the resonant capacitor C1 and the resonant inductor L1, through the switching element Q3, through the coil P2 included in the coupling inductor unit 110, flows to the load, and returns to the ground. In the other current loop, the current passes through the second rectifier element Z2, through the coil S2 included in the coupling inductor unit 110, flows to the load, and returns to the ground. Because the coil P2 and the coil S2 are coupled, when the number of turns of the coil P2 and the coil S2 is the same, the two currents are equal in magnitude when parasitics are ignored. It should be noted that in the working timing of this half cycle, the resonant capacitor C1 is charged.

[0048] During another half cycle, that is, when the switch element Q2, the switch element Q4, and the first rectifier element Z1 are turned on, Figure 3 As shown, two current loops are also formed in the power converter 100. In one current loop, the current flows through the switching element Q4, the LC resonant cavity, and the switching element Q2 to the coupled inductor unit 110, and flows through the coil P1 included in the coupled inductor unit 110 to the load and returns to the ground. In the other current loop, the current flows through the first rectifier element Z1 and the coil S1 included in the coupled inductor unit 110 to the load and returns to the ground. Similarly, because the coil P1 is coupled to the coil S1, when the number of turns of the coil P1 and the coil S1 is the same, the two currents are equal in magnitude when parasitics are ignored. It should be noted that in the working sequence of this half cycle, the resonant capacitor C1 is discharged.

[0049] Regarding the relationship between the output voltage Vo and the input voltage Vin, the number of turns of the coil P1 and the coil P2 is the same, and the number of turns of the coil S1 and the coil S2 is the same. When the number of turns of the coil P1 and the coil P2 is n1, and the number of turns of the coil S1 and the coil S2 is n2, Vo=Vin*n2 / [2*(n1+n2)]. When the number of turns of the coil P1, the coil P2 and the coil S1, the coil S2 are the same, the gain ratio of the output voltage to the input voltage is 1 to 4.

[0050] In the power converter 100 of the present embodiment, the resonant inductor L1 may also be a parasitic inductor on the line. The resonant inductor L1 is independent of the coil P1 , the coil S1 , the coil P2 , and the coil S2 , and has no coupling relationship.

[0051] In the power converter 100 of the present embodiment, by connecting an LC resonant cavity between the connection point Pt1 and the connection point Pt2, a resonant current can be generated, and when the switching frequency of each switching element is equal to the resonant frequency of the LC resonant cavity, soft switching can be achieved, each switching element can achieve zero voltage conduction and zero current disconnection, and the switching loss of each switching element can be reduced. In addition, the currents of the switching elements Q1, Q3 and the switching elements Q2, Q4 all flow to the load, so the currents of the rectifier elements Z1, Z2 as the switching elements are reduced.

[0052] (Implementation Method 2)

[0053] Figure 4 This is a block diagram schematically showing the configuration structure of the main parts of the power converter according to the second embodiment of the present disclosure.

[0054] The power converter 200 of this embodiment 2 is different from the power converter 100 of embodiment 1 mainly in that the structure of the coupled inductor unit is different, that is, a part of the coil of the coupled inductor unit is connected to the position of the LC resonant cavity. Hereinafter, the difference will be mainly described. In embodiment 2, the same mark is marked for the same structure as embodiment 1, and the description is omitted, and the description of the same effect based on the same structure is omitted.

[0055] like Figure 4 As shown, in the power converter 200 of the present embodiment, the coupled inductor unit includes a first coupled inductor TR_S and a second coupled inductor TR_P that are magnetically coupled. One end of the first coupled inductor TR_S is connected to the switching element Q2 and the switching element Q3, and is connected to the load, the other end of the first coupled inductor TR_S is connected to the first rectifying element Z1 and the second rectifying element Z2, respectively, and the second coupled inductor TR_P is connected in series with the LC resonant cavity between the first connection point Pt1 and the second connection point Pt2.

[0056] In this embodiment, if Figure 4As shown, for example, the first coupling inductor TR_S may include a coil S1 (first coil) and a coil S2 (second coil) connected in series, one end of the coil S1 is connected to one end of the coil S2, forming one end of the first coupling inductor TR_S, the other end of the coil S1 and the other end of the coil S2 forming the other end of the first coupling inductor TR_S, the other end of the coil S1 is connected to the first rectifying element Z1, and the other end of the coil S2 is connected to the second rectifying element Z2. In addition, in the present embodiment, the first rectifying element Z1 and the second rectifying element Z2 may be respectively connected between the first coupling inductor TR_S and the reference potential. In addition, in the present embodiment, for example, the first rectifying element Z1 may be connected to the non-same-name end of the coil S1, and the 20th rectifying element Z2 may be connected to the same-name end of the coil S2, and of course, they may be interchanged.

[0057] In this embodiment, the current flows in the direction Figure 1 The embodiment 1 shown is the same as that of the embodiment 1 and can achieve the same effect as that of the embodiment 1, and will not be described in detail here.

[0058] According to the structures of Embodiments 1 and 2, in such non-isolated conversion, energy can be provided to the output through the input in a half cycle, and an effect similar to that of a half bridge can be achieved, and the input current can be half a sine wave.

[0059] (Implementation 3)

[0060] Figure 5 This is a block diagram schematically showing the configuration structure of the main parts of the power converter according to the third embodiment of the present disclosure.

[0061] like Figure 5As shown, the power converter 300 of this embodiment includes a first bridge arm, a second bridge arm, a first LC resonant cavity, a second LC resonant cavity and a coupled inductor unit 310. The first bridge arm includes a switching element Q1 (first switching element), a switching element Q2 (second switching element), a switching element Q5 (fifth switching element), and a switching element Q6 (sixth switching element) connected in series in sequence. The second bridge arm includes a switching element Q7 (seventh switching element), a switching element Q8 (eighth switching element), a switching element Q3 (third switching element), and a switching element Q4 (fourth switching element) connected in series in sequence. Switching element Q1 is connected to switching element Q2 to form a first connection point Pt1, switching element Q3 is connected to switching element Q4 to form a second connection point Pt2, switching element Q5 is connected to switching element Q6 to form a third connection point Pt3, switching element Q7 is connected to switching element Q8 to form a fourth connection point Pt4, and switching element Q2 is connected to switching element Q5 to form a fifth connection point Pt5, and switching element Q8 is connected to switching element Q3 to form a sixth connection point Pt6. The first LC resonant cavity is connected between the first connection point Pt1 and the second connection point Pt2, and the second LC resonant cavity is connected between the third connection point Pt3 and the fourth connection point Pt4. The coupled inductor unit 310 is connected between the fifth connection point Pt5 and the sixth connection point Pt6. Figure 5 As shown, in a preferred embodiment, the coupled inductor unit 310 includes a coil S1 (first coil) and a coil S2 (second coil) connected in series, the center taps of the coil S1 and the coil S2 are connected to the load R8, the coil S1 is connected to the sixth connection point Pt6, the coil S2 is connected to the fifth connection point Pt5, and is connected to the second rectifier element Z2.

[0062] In addition, in this embodiment, if Figure 5 As shown, for example, the first rectifying element Z1 may be connected between the coil S1 and the reference potential, and the second rectifying element Z2 may be connected between the coil S2 and the reference potential.

[0063] Furthermore, in the power converter 300 of the present embodiment, the coil S1 and the coil S2 are magnetically coupled, and the center taps of the coil S1 and the coil S2 are connected to each other and are connected to the load R8 .

[0064] In addition, in the power converter 300 of the present embodiment, the first LC resonant cavity may include a resonant capacitor C1 and a resonant inductor L1 connected in series, and the second LC resonant cavity may include a resonant capacitor C2 and a resonant inductor L2 connected in series. In the present embodiment, the capacitances of the resonant capacitor C1 and the resonant capacitor C2 may be equal. In addition, the resonant inductor L1 and the resonant inductor L2 may also be composed of line parasitic inductances.

[0065] In this embodiment, the switch element Q1 and the switch element Q7 may be connected to the input power supply VIN+, the switch element Q4 and the switch element Q6 may be connected to a reference potential, the load R8 may be connected between the coupled inductor unit 310 and the reference potential, and the capacitor C3 may be connected in parallel with the load R8. Here, the reference potential may also be a ground potential.

[0066] In this embodiment, regarding the polarity relationship between the coil S1 and the coil S2, Figure 5 The same-named ends are indicated by dots. In this embodiment, the non-same-named ends of the coil S1 and the same-named ends of the coil S2 may be connected to the load, or the same-named ends of the coil S1 and the non-same-named ends of the coil S2 may be connected to the load. Because the power converter 300 of this embodiment is configured as a non-isolated power converter, there is no so-called primary side and secondary side in the strict sense of the isolated power converter.

[0067] It should be noted that the power converter 300 of the present embodiment is also provided with a control circuit, which provides control signals Vg1-Vg8, VgZ1, and VgZ2 to the gates of the switch elements Q1-Q8, the first rectifier element Z1, and the second rectifier element Z2. However, since the present disclosure does not involve the specific structure of the control circuit, in order to make the description of the present disclosure clearer, its diagram is omitted and no specific description is given.

[0068] Next, the operation mode of the power converter 300 according to the present embodiment will be described.

[0069] In the power converter 300 of the present embodiment, the first switch element group includes switch element Q1, switch element Q3, switch element Q6, switch element Q8 and the second rectifier element Z2, and the second switch element group includes switch element Q2, switch element Q4, switch element Q5, switch element Q7 and the first rectifier element Z1. The first switch element group is controlled to be synchronously turned on or off, and the corresponding control signals Vg1, Vg3, Vg6, Vg8 and VgZ2 are synchronized. The second switch element group is controlled to be synchronously turned on or off, and the corresponding control signals Vg2, Vg4, Vg5, Vg7 and VgZ1 are synchronized. For example, it can be configured that the first switch element group and the second switch element group are controlled to have equal conduction duty ratios.

[0070] For example, when the control signals Vg1, Vg3, Vg6, Vg8, and VgZ2 are at a high level, the control signals Vg2, Vg4, Vg5, Vg7, and VgZ1 are at a low level, and the control signals Vg1, Vg3, Vg6, Vg8, and VgZ2 are complementary to the control signals Vg2, Vg4, Vg5, Vg7, and VgZ1, and their phases differ by 180 degrees. In one half cycle, the control signals Vg1, Vg3, Vg6, Vg8, and VgZ2 provide a high level to turn on the switch element Q1, the switch element Q3, the switch element Q6, the switch element Q8, and the second rectifier element Z2, so that they are simultaneously turned on with a 50% duty cycle. In another half cycle, the control signals Vg2, Vg4, Vg5, Vg7, and VgZ1 provide a high level to turn on the switch element Q2, the switch element Q4, the switch element Q5, the switch element Q7, and the first rectifier element Z1, so that they are simultaneously turned on with a 50% duty cycle. It should be noted that the duty cycle here is the duty cycle without considering the dead time.

[0071] Figure 6 It is a schematic diagram schematically showing a first mode of a power converter according to Embodiment 3 of the present disclosure. Figure 6 Schematic diagram showing the flow of current when the switching element Q1 , the switching element Q3 , the switching element Q6 , the switching element Q8 , and the second rectifying element Z2 are turned on. Figure 7 It is a schematic diagram schematically showing the second mode of the power converter according to the third embodiment of the present disclosure. Figure 7 Schematic diagram showing the flow of current when the switching element Q2 , the switching element Q4 , the switching element Q5 , the switching element Q7 , and the first rectifying element Z1 are turned on.

[0072] When the switch element Q1, the switch element Q3, the switch element Q6, the switch element Q8, and the second rectifying element Z2 are turned on, Figure 6 As shown, in the power converter 300, the current passes through the switching element Q1, through the first LC resonant cavity formed by the resonant capacitor C1 and the resonant inductor L1, through the switching element Q3, through the coil S1 included in the coupling inductor unit 310, flows to the load, and returns to the ground. In addition, the current passes through the switching element Q6, through the second LC resonant cavity formed by the resonant capacitor C2 and the resonant inductor L2, through the switching element Q8, through the coil S1 included in the coupling inductor unit, flows to the load, and returns to the ground. In addition, through the magnetic coupling of the coil S1 and the coil S2, the current passes through the second rectifying element Z2, through the coil S2 included in the coupling inductor unit 310, flows to the load, and returns to the ground. Because the coil S1 and the coil S2 are magnetically coupled, when the number of turns of the coil S1 and the coil S2 is the same, the current flowing through the two coils is equal when parasitics are ignored. It should be noted that in the working sequence of this half cycle, the resonant capacitor C1 is charged and the resonant capacitor C2 is discharged.

[0073] During another half cycle, that is, when the switch element Q2, the switch element Q4, the switch element Q5, the switch element Q7, and the first rectifier element Z1 are turned on, Figure 7 As shown, in the power converter 300, the current passes through the switching element Q7, passes through the second LC resonant cavity formed by the resonant capacitor C2 and the resonant inductor L2, passes through the switching element Q5, passes through the coil S2 included in the coupling inductor unit 310, flows to the load, and returns to the ground. In addition, the current passes through the switching element Q4, passes through the first LC resonant cavity formed by the resonant capacitor C1 and the resonant inductor L1, passes through the switching element Q2, passes through the coil S2 included in the coupling inductor unit 310, flows to the load, and returns to the ground. In addition, through the magnetic coupling of the coil S2 and the coil S1, the current passes through the first rectifier element Z1, passes through the coil S1 included in the coupling inductor unit 310, flows to the load, and returns to the ground. Similarly, because the coil S1 and the coil S2 are magnetically coupled, when the number of turns of the coil S1 and the coil S2 is the same, the current flowing through the two coils is equal when parasitics are ignored. It should be noted that in the working sequence of this half cycle, the resonant capacitor C2 is charged and the resonant capacitor C1 is discharged.

[0074] Regarding the relationship between the output voltage Vo and the input voltage Vin, when the number of turns of the coil S1 and the coil S2 is the same, the gain ratio of the output voltage to the input voltage is 1 to 4.

[0075] In the power converter 300 of the present embodiment, the resonant inductor L1 and the resonant inductor L2 are independent from the coil S1 and the coil S2 and have no coupling relationship.

[0076] In the power converter 300 of the present embodiment, by connecting the first LC resonant cavity between the connection point Pt1 and the connection point Pt2, and connecting the second LC resonant cavity between the connection point Pt3 and the connection point Pt4, a resonant current can be generated, and when the switching frequency of each switching element is equal to the resonant frequency of the first LC resonant cavity and the second LC resonant cavity, soft switching can be achieved, each switching element can achieve zero voltage conduction and zero current disconnection, and the switching loss of each switching element can be reduced. Moreover, relative to the isolation converter, the current can be greatly reduced for the secondary side of the traditional LC. Moreover, because the coil is a fully coupled relationship, the number of coil turns can be reduced, and winding is convenient. In addition, according to the structure of the power converter of the present embodiment, it can be easily driven. In addition, according to the structure of the power converter of the present embodiment, when the number of turns of the coil S1 and the coil S is the same, the structure is symmetrical, because the current flows through the coil S1 and the coil S2 at the same time, the peak factor can be reduced, and the input current can be reduced. Furthermore, according to the structure of the power converter of this embodiment, by integrating into a full-bridge-like structure, energy can be supplied from the so-called primary side to the so-called secondary side in both half cycles, thereby reducing the input current.

[0077] The operation of the power converter 300 according to this embodiment is simulated through simulation. Figure 8 Schematic diagram schematically showing the voltage waveform and current waveform of the control signal in the power converter according to the third embodiment of the present disclosure. Figure 8 In the figure, an example of control signals Vg1, Vg3, Vg6, Vg8, VgZ2 and control signals Vg2, Vg4, Vg5, Vg7, VgZ1 are shown, and an example of the resonant current iL1 of the first LC resonant cavity and the resonant current iL2 of the second LC resonant cavity are shown.

[0078] (Implementation 4)

[0079] Fig. 9 This is a block diagram schematically showing the configuration structure of the main parts of the power converter according to the fourth embodiment of the present disclosure.

[0080] The difference between the power converter 400 of this embodiment and the power converter 300 of embodiment 3 is mainly that the structure of the coupled inductor unit is different. Below, mainly explain the difference. In embodiment 4, the same mark is marked for the same structure as embodiment 3, and the explanation is omitted, and the explanation of the same effect based on the same structure is omitted.

[0081] like Fig. 9As shown, in the power converter 400 of the present embodiment, the coupled inductor unit 410 includes a coil P1 (first coil) and a coil P2 (second coil) connected in series and a coil S1 (third coil) and a coil S2 (fourth coil) connected in series, the center taps of the coil P1 and the coil P2 are connected to the center taps of the coil S1 and the coil S2, and are connected to a load R8, the coil P1 is connected to the sixth connection point Pt6, the coil P2 is connected to the fifth connection point Pt5, the coil S1 is connected to the first rectifying element Z1, the coil S2 is connected to the second rectifying element Z2, the coil P1 and the coil S2 are magnetically coupled, and the coil P2 and the coil S1 are magnetically coupled.

[0082] Similarly, in the power converter 400 of the present embodiment, the first switch element group includes switch element Q1, switch element Q3, switch element Q6, switch element Q8 and the second rectifier element Z2, and the second switch element group includes switch element Q2, switch element Q4, switch element Q5, switch element Q7 and the first rectifier element Z1. The first switch element group is controlled to be synchronously turned on or off, and the corresponding control signals Vg1, Vg3, Vg6, Vg8 and VgZ2 are synchronized. The second switch element group is controlled to be synchronously turned on or off, and the corresponding control signals Vg2, Vg4, Vg5, Vg7 and VgZ1 are synchronized.

[0083] Fig.10 It is a schematic diagram schematically showing a first mode of a power converter according to a fourth embodiment of the present disclosure. Fig.10 Schematic diagram showing the flow of current when the switching element Q1 , the switching element Q3 , the switching element Q6 , the switching element Q8 , and the second rectifying element Z2 are turned on. Fig.11 It is a schematic diagram schematically showing the second mode of the power converter according to the fourth embodiment of the present disclosure. Fig.11 Schematic diagram showing the flow of current when the switching element Q2 , the switching element Q4 , the switching element Q5 , the switching element Q7 , and the first rectifying element Z1 are turned on.

[0084] When the switch element Q1, the switch element Q3, the switch element Q6, the switch element Q8 and the second rectifying element Z2 are turned on, Fig.10As shown, in the power converter 400, the current passes through the switching element Q1, passes through the first LC resonant cavity formed by the resonant capacitor C1 and the resonant inductor L1, passes through the switching element Q3, passes through the coil P1 included in the coupling inductor unit 410, flows to the load, and returns to the ground. In addition, the current passes through the switching element Q6, passes through the second LC resonant cavity formed by the resonant capacitor C2 and the resonant inductor L2, passes through the switching element Q8, passes through the coil P1 included in the coupling inductor unit 410, flows to the load, and returns to the ground. In addition, through the magnetic coupling of the coil P1 and the coil S2, the current passes through the second rectifying element Z2, passes through the coil S2 included in the coupling inductor unit 410, flows to the load, and returns to the ground. Because the coil P1 and the coil S2 are magnetically coupled, when the number of turns of the coil P1 and the coil S2 is the same, the current flowing through the two coils is equal when parasitics are ignored. It should be noted that in the working sequence of this half cycle, the resonant capacitor C1 is charged and the resonant capacitor C2 is discharged.

[0085] During another half cycle, that is, when the switch element Q2, the switch element Q4, the switch element Q5, the switch element Q7, and the first rectifier element Z1 are turned on, Fig.11 As shown, in the power converter 400, the current passes through the switching element Q7, passes through the second LC resonant cavity formed by the resonant capacitor C2 and the resonant inductor L2, passes through the switching element Q5, passes through the coil P2 included in the coupling inductor unit 410, flows to the load, and returns to the ground. In addition, the current passes through the switching element Q4, passes through the first LC resonant cavity formed by the resonant capacitor C1 and the resonant inductor L1, passes through the switching element Q2, passes through the coil P2 included in the coupling inductor unit 410, flows to the load, and returns to the ground. In addition, through the magnetic coupling of the coil P2 and the coil S1, the current passes through the first rectifier element Z1, passes through the coil S1 included in the coupling inductor unit 410, flows to the load, and returns to the ground. Similarly, because the coil P2 and the coil S1 are magnetically coupled, when the number of turns of the coil P2 and the coil S1 is the same, the current flowing through the two coils is equal when parasitics are ignored. It should be noted that in the working sequence of this half cycle, the resonant capacitor C2 is charged and the resonant capacitor C1 is discharged.

[0086] Regarding the relationship between the output voltage Vo and the input voltage Vin, the number of turns of the coil P1 and the coil P2 is the same, and the number of turns of the coil S1 and the coil S2 is the same. When the number of turns of the coil P1 and the coil P2 is n1, and the number of turns of the coil S1 and the coil S2 is n2, Vo=Vin*n2 / [2*(n1+n2)]. When the number of turns of the coil P1, the coil P2 and the coil S1, the coil S2 are the same, the gain ratio of the output voltage to the input voltage is 1 to 4.

[0087] In the power converter 400 of the present embodiment, the resonant inductor L1 and the resonant inductor L2 are independent of the coil S1 , the coil S2 , the coil P1 , and the coil P2 , and have no coupling relationship therebetween.

[0088] The power converter 400 according to this embodiment can achieve the same effects as the power converter 300 according to Embodiment 3. The details will not be described here.

[0089] It should be noted that the topological structure of the power converter 200 of the second embodiment of the present disclosure can be regarded as an evolution of the topological structure of the power converter 100 of the first embodiment. The topological structure of the power converter 400 of the fourth embodiment of the present disclosure can be regarded as a structure obtained by coupling the transformers in the two-phase structure of the power converter 100 of the first embodiment when the timing is staggered by 180° and merging the primary windings. The topological structure of the power converter 300 of the third embodiment of the present disclosure can be regarded as a structure obtained by merging the coil P1 and the coil S1 and the coil P2 and the coil S2 in the power converter 400 of the fourth embodiment.

[0090] Above, although the present disclosure has been illustrated in conjunction with the preferred embodiments of the present disclosure, it will be understood by those skilled in the art that various modifications, substitutions and changes may be made to the present disclosure without departing from the spirit and scope of the present disclosure. Therefore, the present disclosure should not be limited by the above-mentioned embodiments, but by the attached claims and their equivalents.

Claims

1. A power converter comprising: A first bridge arm, comprising a first switch element and a second switch element connected in series, wherein the first switch element and the second switch element are connected to form a first connection point; a second bridge arm, comprising a third switch element and a fourth switch element connected in series, wherein the third switch element is connected to the fourth switch element to form a second connection point; a first LC resonant cavity connected between the first connection point and the second connection point; A first rectifying element and a second rectifying element as switching elements; as well as A coupled inductor unit is connected to the second switching element, the third switching element, the first rectifying element, and the second rectifying element, respectively, and a center tap is connected to a load.

2. The power converter according to claim 1, wherein: The coupled inductor unit includes a magnetically coupled first coil and a second coil and a magnetically coupled third coil and a fourth coil, wherein the center taps of the first coil and the second coil are connected to the center taps of the third coil and the fourth coil and are connected to the load, The first coil is connected to the second switching element, the second coil is connected to the first rectifying element, the third coil is connected to the third switching element, and the fourth coil is connected to the second rectifying element.

3. The power converter according to claim 1, wherein: The coupled inductor unit includes a first coupled inductor and a second coupled inductor that are magnetically coupled. One end of the first coupled inductor is connected to the second switching element and the third switching element and is connected to the load, and the other end of the first coupled inductor is connected to the first rectifying element and the second rectifying element, respectively. The second coupling inductor is connected in series with the first LC resonant cavity between the first connection point and the second connection point.

4. The power converter according to claim 3, wherein: The first coupled inductor includes a first coil and a second coil connected in series. One end of the first coil is connected to one end of the second coil to constitute one end of the first coupled inductor, the other end of the first coil and the other end of the second coil constitute the other end of the first coupled inductor, the other end of the first coil is connected to the first rectifying element, and the other end of the second coil is connected to the second rectifying element.

5. The power converter according to claim 1, wherein: The first bridge arm further includes a fifth switch element and a sixth switch element connected in series with the first switch element and the second switch element, wherein the fifth switch element is connected to the sixth switch element to form a third connection point. The second bridge arm further includes a seventh switch element and an eighth switch element connected in series with the third switch element and the fourth switch element, wherein the seventh switch element is connected to the eighth switch element to form a fourth connection point. The power converter further includes a second LC resonant cavity connected between the third connection point and the fourth connection point. The fifth switching element is connected to the second switching element to form a fifth connection point, the eighth switching element is connected to the third switching element to form a sixth connection point, and the coupled inductor unit is connected between the fifth connection point and the sixth connection point.

6. The power converter according to claim 5, wherein: The coupled inductor unit includes a first coil and a second coil connected in series, wherein center taps of the first coil and the second coil are connected to the load. The first coil is connected to the sixth connection point and to the first rectifying element. The second coil is connected to the fifth connection point and is also connected to the second rectifying element.

7. The power converter according to claim 5, wherein: The coupled inductor unit includes a first coil and a second coil connected in series and a third coil and a fourth coil connected in series, the center taps of the first coil and the second coil are connected to the center taps of the third coil and the fourth coil, and are connected to the load, The first coil is connected to the sixth connection point, the second coil is connected to the fifth connection point, the third coil is connected to the first rectifying element, and the fourth coil is connected to the second rectifying element. The first coil and the fourth coil are magnetically coupled, and the second coil and the third coil are magnetically coupled.

8. The power converter according to any one of claims 1 to 4, wherein: The first switching element group includes the first switching element, the third switching element, and the second rectifying element. The second switching element group includes the second switching element, the fourth switching element, and the first rectifying element. The first switch element group is controlled to be synchronously turned on or off. The second switch element group is controlled to be turned on or off synchronously, The first switching element group and the second switching element group are controlled to have the same on-duty ratio.

9. The power converter according to claim 8, wherein: The first switching element group and the second switching element group are controlled so that their respective on-duty ratios are both 50% without considering the dead time. The control signals of the first switching element group and the second switching element group are 180 degrees out of phase with each other.

10. The power converter according to any one of claims 5 to 7, wherein: The first switching element group includes the first switching element, the third switching element, the sixth switching element, the eighth switching element, and the second rectifying element. The second switching element group includes the second switching element, the fourth switching element, the fifth switching element, the seventh switching element, and the first rectifying element. The first switch element group is controlled to be synchronously turned on or off. The second switch element group is controlled to be turned on or off synchronously, The first switching element group and the second switching element group are controlled to have the same on-duty ratio.

11. The power converter according to claim 10, wherein: The first switching element group and the second switching element group are controlled so that their respective on-duty ratios are both 50% without considering the dead time. The control signals of the first switching element group and the second switching element group are 180 degrees out of phase with each other.

12. The power converter according to any one of claims 5 to 7, wherein: The first LC resonant cavity includes a first resonant inductor and a first resonant capacitor connected in series, The second LC resonant cavity includes a second resonant inductor and a second resonant capacitor connected in series, The capacitance of the first resonant capacitor is equal to the capacitance of the second resonant capacitor.

13. The power converter according to claim 12, wherein: The first resonant inductor and / or the second resonant inductor is / are formed by line parasitic inductance.

14. The power converter according to any one of claims 5 to 7, wherein: The resonant frequency of the first LC resonant cavity, the resonant frequency of the second LC resonant cavity and the operating frequency of the power converter are the same.

15. The power converter according to claim 6, wherein: The first coil and the second coil have the same number of turns.

16. The power converter according to claim 2 or 7, wherein: The first coil, the second coil, the third coil, and the fourth coil have the same number of turns.

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