Power converter

Abstract

A power converter is provided with: a first leg which is connected between an input power source and a reference potential, and which includes 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 connected in parallel with the first leg between the input power supply and the reference potential, the second leg including a first capacitor and a second capacitor connected in series, the first capacitor and the second capacitor being connected to form a second connection point; a coupling inductance unit which is connected between the first connection point and the second connection point and has a center tap connected to a load; and a first resonant inductor which is connected in series with the coupling inductance unit between the first connection point and the second connection point, and which constitutes a series resonant circuit with each of the first capacitor and the second capacitor.

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, a power converter is provided, comprising: a first bridge arm, which is connected between an input power supply and a reference potential, and includes a first switching element and a second switching element connected in series, and the first switching element is connected to the second switching element to form a first connection point; a second bridge arm, which is connected in parallel with the first bridge arm between the input power supply and the reference potential, and includes a first capacitor and a second capacitor connected in series, and the first capacitor is connected to the second capacitor to form a second connection point; a coupled inductor unit, which is connected between the first connection point and the second connection point, and a center tap is connected to a load; and a first resonant inductor, which is connected in series with the coupled inductor unit between the first connection point and the second connection point, and forms a series resonant circuit with the first capacitor and the second capacitor respectively.

[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, one end of the first coil and one end of the second coil are connected to form the center tap, and the power converter also has an output filter capacitor and a third switching element and a fourth switching element as rectifying elements, the other end of the first coil is connected to the third switching element, the other end of the second coil is connected to the fourth switching element, the third switching element is connected to the fourth switching element to form a third connection point, and the output filter capacitor is connected between the center tap and the third connection point.

[0009] Furthermore, according to the power converter of the present disclosure, the coupled inductor unit may further include a third coil, and the third coil is connected between the first coil and the second connection point.

[0010] Furthermore, according to the power converter of the present disclosure, the capacitance of the first capacitor may be equal to the capacitance of the second capacitor.

[0011] Furthermore, according to the power converter of the present disclosure, the first resonant inductor may be formed of a line parasitic inductance.

[0012] In addition, according to the power converter disclosed in the present invention, the resonant frequency of the series resonant circuit may be the same as the operating frequency of the power converter.

[0013] Furthermore, according to the power converter of the present disclosure, the first coil and the second coil may have the same number of turns.

[0014] 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, one end of the first coil and one end of the second coil are connected to form the center tap, the other end of the first coil is connected to the second connection point, and the other end of the second coil is connected to the first connection point. The power converter also has an output filter capacitor and a first rectifier bridge arm and a second rectifier bridge arm respectively connected in parallel with the output filter capacitor, the first rectifier bridge arm includes a third switch element and a fifth switch element connected in series, the connection point of the third switch element and the fifth switch element is connected to the center tap, the second rectifier bridge arm includes a fourth switch element and a sixth switch element connected in series, the connection point of the fourth switch element and the sixth switch element is connected to the first connection point, one end of the output filter capacitor is connected to the fourth switch element and the fifth switch element, and the other end of the output filter capacitor is connected to the third switch element and the sixth switch element.

[0015] Furthermore, according to the power converter of the present disclosure, the number of turns of the first coil may be zero, and the number of turns of the second coil may be an arbitrary natural number.

[0016] In addition, according to the power converter disclosed in the present invention, the first switch element group may include the first switch element and the third switch element, the second switch element group may include the second switch element and the fourth switch 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.

[0017] 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.

[0018] 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 fourth switch element, the second switch element group may include the second switch element, the fifth switch element and the sixth switch 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.

[0019] 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.

[0020] In addition, according to the power converter disclosed in the present invention, the power converter may also be provided with a reference potential control unit for controlling the voltage of the reference potential, and the reference potential control unit includes: a third capacitor, which is connected between the reference potential and the benchmark potential; a third bridge arm, which is connected between the input power supply and the reference potential, including a fifth switching element and a sixth switching element connected in series, and the fifth switching element is connected to the sixth switching element to form a fourth connection point; and a second resonant inductor, which is connected between the fourth connection point and the reference potential.

[0021] In addition, according to the power converter disclosed in the present invention, the reference potential control unit may also include a 4th bridge arm, the 4th bridge arm is connected between the reference potential and the reference potential, and includes a 7th switching element and an 8th switching element connected in series, the 7th switching element is connected to the 8th switching element to form a 5th connection point, and the 2nd resonant inductor is connected between the 4th connection point and the 5th connection point.

[0022] Effects of the Invention

[0023] According to the present disclosure, a power converter capable of achieving soft switching can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] 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:

[0025] 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.

[0026] Figure 2 This is a schematic diagram schematically showing an example of a switching sequence of a switching element in the power converter according to the first embodiment of the present disclosure.

[0027] Figure 3 It is a schematic diagram schematically showing the flow of power current in the power converter according to the first embodiment of the present disclosure.

[0028] Figure 4 It is a schematic diagram schematically showing the flow of power current in the power converter according to the first embodiment of the present disclosure.

[0029] Figure 5 This is a schematic diagram schematically showing a current waveform flowing through a switching element in the power converter according to the first embodiment of the present disclosure.

[0030] Figure 6 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.

[0031] Figure 7 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.

[0032] Figure 8 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. 9 This is a block diagram schematically showing the configuration structure of the main parts of the power converter according to Embodiment 5 of the present disclosure. DETAILED DESCRIPTION

[0034] 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.

[0035] Hereinafter, the present disclosure will be described in detail with reference to the accompanying drawings.

[0036] (Implementation Method 1)

[0037] 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 four switching elements Q1 to Q4, a coupled inductor unit TX1, capacitors C1 to C3, and a resonant inductor. In this embodiment, the switching elements may be various transistors, and the same applies to other embodiments.

[0038] like Figure 1 As 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, a coupled inductor unit TX1, a capacitor C1, a capacitor C2, and a capacitor C3. 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 A, the capacitor C1 (the first capacitor) and the capacitor C2 (the second capacitor) connected in series can be regarded as constituting the second bridge arm, and the capacitor C1 and the capacitor C2 are connected to form the second connection point B. In addition, in the power converter 100 of the present embodiment, the coupled inductor unit TX1 is connected between the first connection point A and the second connection point B, and the center tap is connected to the load. The resonant inductor L1 (first resonant inductor) is connected in series with the coupled inductor unit TX1 between the first connection point A and the second connection point B, and forms a series resonant circuit with the capacitor C1 and the capacitor C2, respectively. In a preferred embodiment, the resonant inductor L1 is connected between the coupled inductor unit TX1 and the second connection point B. In the present invention, the resonant inductor L1 may also be formed by line parasitic inductance.

[0039] In this embodiment, if Figure 1As shown, the coupled inductor unit TX1 includes a magnetically coupled coil P1 (first coil) and a coil P2 (second coil). In the present embodiment, one end of the coil P1 is connected to one end of the coil P2 to form a center tap, which is connected to the load. It should be noted that the non-same-name end of the coil P1 can be connected to the same-name end of the coil P2, or the same-name end of the coil P1 can be connected to the non-same-name end of the coil P2. The other end of the coil P1 is connected to the switching element Q3 (the third switching element), and the other end of the coil P2 is connected to the switching element Q4 (the fourth switching element), and the switching element Q3 is connected to the switching element Q4 to form the third connection point Vo_return. The capacitor C3 is connected between the center tap and the third connection point Vo_return. In the present embodiment, the capacitor C3 functions as an output filter capacitor, and the switching element Q3 and the switching element Q4 function as rectifying elements.

[0040] In this embodiment, the switch element Q1 can be connected to the input power supply VIN+, and the switch element Q2 can be connected to the reference potential. Here, the reference potential can be a ground potential or other adjustable potential. The first bridge arm including the switch element Q1 and the switch element Q2 connected in series and the second bridge arm including the capacitor C1 and the capacitor C2 connected in series are connected in parallel between the input power supply and the reference potential.

[0041] In this embodiment, regarding the polarity relationship between the coil P1 and the coil P2, Figure 1 Since 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.

[0042] It should be noted that the power converter 100 of the present embodiment also includes a control circuit that provides control signals Vg1-Vg4 to the gates of the switching elements Q1-Q4. 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.

[0043] Next, the operation mode of the power converter 100 according to the present embodiment will be described.

[0044] In the power converter 100 of the present embodiment, the first switch element group includes switch element Q1 and switch element Q3, and the corresponding control signals Vg1 and Vg3 are synchronized, and the second switch element group includes switch element Q2 and switch element Q4, and the corresponding control signals Vg2 and Vg4 are synchronized. In the present embodiment, the first switch element group is controlled to be synchronously turned on or off, and the second switch element group is controlled to be synchronously turned on or off. The first switch element group and the second switch element group are controlled to have equal on-duty ratios, and the phases of the control signals of the first switch element group and the second switch element group differ by 180 degrees. For example, when the control signals Vg1 and Vg3 are at a high level, the control signals Vg2 and Vg4 are at a low level, and the phases of the control signals Vg1 and Vg3 differ by 180 degrees from the control signals Vg2 and Vg4. In one half cycle, the control signals Vg1 and Vg3 provide a high level to turn on the switch elements Q1 and Q3, so that the switch elements Q1 and Q3 are simultaneously turned on with a 50% duty cycle. In another half cycle, the control signals Vg2 and Vg4 provide a high level to turn on the switch elements Q2 and Q4, so that the switch elements Q2 and Q4 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.

[0045] Figure 2 This is a schematic diagram schematically showing an example of a switching sequence of a switching element in the power converter according to the first embodiment of the present disclosure. Figure 3 It is a schematic diagram schematically showing the flow of power current in the power converter according to the first embodiment of the present disclosure. Figure 4 It is a schematic diagram schematically showing the flow of power current in the power converter according to the first embodiment of the present disclosure.

[0046] like Figure 2 As shown, at the time t1-t2, the control signals Vg1 and Vg3 are high, and the control signals Vg2 and Vg4 are low, so the switch elements Q1 and Q3 are turned on, and the switch elements Q2 and Q4 are turned off. The power current in the circuit is as follows Figure 3 As shown. Figure 2 As shown, at time t3-t4, the control signals Vg1 and Vg3 are at low level, and the control signals Vg2 and Vg4 are at high level, so the switch elements Q1 and Q3 are turned off, and the switch elements Q2 and Q4 are turned on. The power current in the circuit is as follows: Figure 4 shown.

[0047] When the switch element Q1 and the switch element Q3 are turned on and the switch element Q2 and the switch element Q4 are turned off, Figure 3As shown in FIG. 1 , since the switch element Q1 is turned on, the voltage at the first connection point A becomes the voltage of the input power supply VIN+, and a voltage difference is formed between the first connection point A and the second connection point B. Therefore, the current flows from the input power supply VIN+ through the switch element Q1 and the first connection point A to the second coil P2, and then flows to the second connection point B through the capacitor C3, the switch element Q3 and the resonant inductor L1. Since the current from the first connection point A to the second connection point B is generated, as shown in FIG. Figure 3 As shown, a current flows to the input power supply VIN+ through capacitor C2, and a current flows to the reference potential through capacitor C1. In addition, due to the magnetic coupling between coil P1 and coil P2, a demagnetization current is generated from coil P1 to capacitor C3 to switching element Q3. When the number of turns of coil P1 and coil P2 is equal, the two currents are equal in magnitude when parasitics are ignored. It should be noted that in the working timing of this half cycle, it can be regarded as capacitor C1 being charged and capacitor C2 being discharged.

[0048] During another half cycle, that is, when the switch element Q1 and the switch element Q3 are turned off and the switch element Q2 and the switch element Q4 are turned on, Figure 4 As shown in FIG. 1 , since the switch element Q2 is turned on, the voltage at the first connection point A becomes the voltage of the reference potential, and a voltage difference is formed between the first connection point A and the second connection point B, so the current flows from the second connection point B to the first connection point A via the resonant inductor L1, the coil P1, the capacitor C3, and the switch element Q4, and flows to the reference potential through the switch element Q2, and flows to the outside. Since the current from the second connection point B to the first connection point A is generated, as shown in FIG. Figure 4 As shown, a current flows from the input power supply VIN+ to the capacitor C2, and a current flows from the reference potential to the capacitor C1. Similarly, due to the magnetic coupling between the coil P1 and the coil P2, a demagnetization current flows from the coil P2 to the capacitor C3 to the switching element Q4. When the number of turns of the coil P1 and the coil P2 are equal, the two currents are equal in magnitude when parasitics are ignored. It should be noted that in the working sequence of this half cycle, it can be regarded as the capacitor C1 is discharged and the capacitor C2 is charged.

[0049] In this embodiment, since the capacitor C1 and the capacitor C2 function as resonant capacitors, it is preferred that the capacitances of the capacitor C1 and the capacitor C2 are equal. Accordingly, the structure of the resonant capacitor becomes symmetrical. In addition, in this embodiment, it is preferred that the operating frequency of the power converter 100 is equal to the resonant frequency of the capacitor C1 and the capacitor C2 and the resonant inductor L1. The resonant frequency of the capacitor C1 and the capacitor C2 and the resonant inductor L1 can be calculated by the following formula 1.

[0050] Equation 1: fr=1 / 2π / (Lr*Cr)^0.5

[0051] Wherein, fr is the resonant frequency, Lr is the inductance value of the resonant inductor L1, and Cr is the capacitance value of the capacitor C1 or the capacitor C2.

[0052] In addition, in the present embodiment, the number of turns of the coil P1 and the coil P2 are preferably the same, thereby achieving a gain ratio of the output voltage Vo to the input voltage Vin of 1 to 4.

[0053] The operation mode of the power converter 100 according to the present embodiment was simulated by simulation. Figure 5 Schematic diagram schematically showing the current waveform flowing through the switching element in the power converter according to the first embodiment of the present disclosure. Figure 5 , an example of a current _Q1 flowing through the switching element Q1 , a current _Q2 flowing through the switching element Q2 , a current _Q3 flowing through the switching element Q3 , and a current _Q4 flowing through the switching element Q4 is shown.

[0054] In this embodiment, if Figure 5 As shown, when the switch element is turned on, the current passes through the body tube, and when it is turned off, the current is close to zero, so each switch element in this embodiment can achieve zero voltage turn-on and zero current turn-off, can achieve soft switching, and can reduce the switching loss of each switch element. In addition, since there is no spike on the Vds of each switch element, it is helpful to select a MOS tube with a lower withstand voltage.

[0055] Furthermore, in this embodiment, in practical applications, the transformer leakage inductance can be used to replace the resonant inductor L1 at high switching frequencies, and no actual inductance is required, so space and cost can be saved.

[0056] In addition, in this embodiment, by adopting LLC, the duty cycle D≈50% (slightly less than 50%) remains unchanged, and compared with the traditional isolated half-bridge LLC, the effective value passing through the transformer coil (primary and secondary sides) can be reduced.

[0057] Furthermore, in this embodiment, the input ripple current can be made smaller by making the resonant capacitor structure symmetrical.

[0058] (Implementation Method 2)

[0059] Figure 6 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.

[0060] The difference between the power converter 200 of this embodiment 2 and the power converter 100 of embodiment 1 is mainly that the structure of the coupled inductor unit is different. Below, mainly explain the difference. In embodiment 2, the same mark is marked for the same structure as embodiment 1, and the explanation is omitted, and the explanation of the same effect based on the same structure is omitted.

[0061] like Figure 6 As shown, the power converter 200 of the present embodiment has a coupled inductor unit TX2. The coupled inductor unit TX2 includes a coil P2 (first coil) and a coil P3 (second coil) connected in series, and also includes a coil P1 (third coil). The coil P1 is connected between the coil P2 and the second connection point B. The number of turns of the coil P1 is set to n1, the number of turns of the coil P2 and the coil P3 are equal, and the number of turns of the coil P2 and the coil P3 are set to n2. When n1 is 0, the structure of the power converter 200 of the present embodiment becomes the same as the structure of the power converter 100 of the first embodiment.

[0062] In this embodiment, the relationship between the output voltage Vo and the input voltage Vin satisfies the following equation 2.

[0063] Equation 2: Vo=Vin*n2 / (2*n1+4n2)

[0064] In this embodiment, the gain ratio of the output voltage to the input voltage can be adjusted by adjusting the number of turns n1 and n2 of the coil. Furthermore, when the number of turns n1 and n2 of the coil is fixed, a fixed output gain ratio can be achieved.

[0065] (Implementation method 3)

[0066] Figure 7 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.

[0067] The difference between the power converter 300 of this embodiment 3 and the power converter 100 of embodiment 1 is mainly that the structure of the output rectifier unit is different. Below, mainly explain at the difference. In embodiment 3, for the structure identical with embodiment 1, mark the same mark, and omit explanation, and omit the explanation of the same action effect based on the same structure.

[0068] like Figure 7 As shown, in the power converter 300 of this embodiment, similarly to the power converter 100 of the first embodiment, the coupled inductor unit TX1 includes a magnetically coupled coil P1 (first coil) and a coil P2 (second coil), and one end of the coil P1 is connected to one end of the coil P2 to form a center tap. Figure 7As shown, in the power converter 300 of the present embodiment, the other end of the coil P1 is connected to the second connection point B, and the other end of the coil P2 is connected to the first connection point A. The power converter 300 of the present embodiment is provided with a capacitor C3, and a first rectifier bridge arm and a second rectifier bridge arm respectively connected in parallel with the capacitor C3. The first rectifier bridge arm includes a switch element Q3 (the third switch element) and a switch element Q5 (the fifth switch element) connected in series, and the connection point of the switch element Q3 and the switch element Q5 is connected to the center tap. The second rectifier bridge arm includes a switch element Q4 (the fourth switch element) and a switch element Q6 (the sixth switch element) connected in series, and the connection point of the switch element Q4 and the switch element Q6 is connected to the first connection point A. One end of the capacitor C3 is connected to the switch element Q4 and the switch element Q5, and the other end of the capacitor C3 is connected to the switch element Q3 and the switch element Q6.

[0069] In the present embodiment, the capacitor C3 functions as an output smoothing capacitor, and the switching element Q3 , the switching element Q4 , the switching element Q5 , and the switching element Q6 function as rectifying elements.

[0070] In the power converter 400 of the present embodiment, the first switch element group includes switch element Q1, switch element Q3 and switch element Q4, and the corresponding control signals Vg1, Vg3 and Vg4 are synchronized, and the second switch element group includes switch element Q2, switch element Q5 and switch element Q6, and the corresponding control signals Vg2, Vg5 and Vg6 are synchronized. In the present embodiment, 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, the first switch element group and the second switch element group are controlled to have equal conduction duty ratios, and the phases of the control signals of the first switch element group and the second switch element group differ by 180 degrees. For example, when the control signals Vg1, Vg3 and Vg4 are at a high level, the control signals Vg2, Vg5 and Vg6 are at a low level, and the phases of the control signals Vg1, Vg3 and Vg4 differ by 180 degrees from the control signals Vg2, Vg5 and Vg6. In one half cycle, the control signals Vg1, Vg3, and Vg4 provide a high level to turn on the switch elements Q1, Q3, and Q4, so that the switch elements Q1, Q3, and Q4 are simultaneously turned on with a 50% duty cycle. In another half cycle, the control signals Vg2, Vg5, and Vg6 provide a high level to turn on the switch elements Q2, Q5, and Q6, so that the switch elements Q2, Q5, and Q6 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] Furthermore, in the present embodiment, the number of turns of the coil P1 and the coil P2 may be any natural number.

[0072] In the present embodiment, when the number of turns of the coil P1 is n1 and the number of turns of the coil P2 is n2, the relationship between the output voltage Vo and the input voltage Vin satisfies the following equation 3.

[0073] Equation 3: Vo=Vin*n2 / (2*n1+2n2)

[0074] In this embodiment, the gain ratio of the output voltage to the input voltage can be adjusted by adjusting the number of turns n1 and n2 of the coil. Furthermore, when the number of turns n1 and n2 of the coil is fixed, a fixed output gain ratio can be achieved.

[0075] In the present embodiment, when the number of turns of the coil P1 is zero, the number of turns of the coil P2 is preferably an arbitrary natural number. In the present embodiment, when the number of turns of the coil P2 is zero, the number of turns of the coil P1 is preferably zero.

[0076] (Implementation 4)

[0077] Figure 8 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.

[0078] The difference between the power converter 400 of this embodiment and the power converter 100 of embodiment 1 is mainly that the power converter 400 also has a reference potential control unit for controlling the voltage of the reference potential. Below, mainly describe the difference. In embodiment 4, the same mark is marked for the structure identical with embodiment 1, and description is omitted, and the description of the same action effect based on the same structure is omitted.

[0079] In the power converter 400 of this embodiment, as Figure 8 As shown in FIG. 1 , the reference potential control unit includes a switch element Q5 (fifth switch element), a switch element Q6 (sixth switch element), a resonant inductor L2 (second resonant inductor), and a capacitor C4 (third capacitor). Figure 8 As shown, capacitor C4 is connected between reference potential C and reference potential. Here, the reference potential may also be ground potential. Switching element Q5 and switching element Q6 are connected in series between input power supply VIN+ and reference potential, and switching element Q5 and switching element Q6 are connected to form a fourth connection point D. Here, it can be regarded that switching element Q5 and switching element Q6 constitute the third bridge arm. That is, the third bridge arm is connected between input power supply VIN+ and reference potential, and includes switching element Q5 and switching element Q6 connected in series. In addition, resonant inductor L2 is connected between the fourth connection point D and reference potential C.

[0080] In this embodiment, the control circuit also provides control signals Vg5 and Vg6 to the gates of the switch element Q5 and the switch element Q6. The control signals Vg5 and Vg6 are complementary, so that the switch element Q5 and the switch element Q6 are complementary turned on. When the on-duty ratio of the switch element Q5 is set to d1, the relationship between the output voltage Vo and the input voltage Vin satisfies the following equation 4.

[0081] Equation 4: Vo=Vin*(1-d1) / 4

[0082] According to the present embodiment, by controlling the on-duty ratio of the switching element Q5 , the gain ratio between the output voltage and the input voltage can be adjusted.

[0083] In this embodiment, according to Formula 4, for example, if Vin=48 and the required Vo=1, it is only necessary to control d1=(Vin-4Vo) / Vin=91.7%.

[0084] For the BUCK converter, the larger the value of d1, the higher the efficiency. It can be seen that when Vo<<Vin, the value of d1 is large, and the BUCK stage can achieve high efficiency. For the non-isolated LLC resonant converter with a fixed DC gain of 1 / 4, high efficiency can also be achieved.

[0085] (Implementation 5)

[0086] Fig. 9 This is a block diagram schematically showing the configuration structure of the main parts of the power converter according to Embodiment 5 of the present disclosure.

[0087] The main difference between the power converter 500 of this embodiment and the power converter 400 of embodiment 4 is that the reference potential control unit in the power converter 500 is replaced by a BUCK-BOOST converter by a BUCK converter. Hereinafter, the difference will be mainly described. In embodiment 5, the same reference mark is used for the same structure as embodiment 4, and the description is omitted, and the description of the same effect based on the same structure is omitted.

[0088] In the power converter 500 of this embodiment, Fig. 9 As shown, the reference potential control unit further includes a fourth bridge arm. The fourth bridge arm is connected between the reference potential C and the reference potential, and includes a switch element Q7 (the seventh switch element) and a switch element Q8 (the eighth switch element) connected in series, and the switch element Q7 and the switch element Q8 are connected to form a fifth connection point E. The resonant inductor L2 is connected between the fourth connection point D and the fifth connection point E.

[0089] In this embodiment, the control circuit also provides control signals Vg5, Vg6, Vg7, and Vg8 to the gates of the switching elements Q5, Q6, Q7, and Q8. The control signals Vg5, Vg6, Vg7, and Vg8 are PWM (Pulse Width Modulation) signals with the same frequency. The control signal Vg5 and the control signal Vg6 are complementary, and the on-duty cycle of the control signal Vg5 is set to d1. The control signal Vg7 and the control signal Vg8 are complementary, and the on-duty cycle of the control signal Vg7 is set to d2. By controlling the on-duty cycles d1 and d2 and the phase angles of the control signals Vg6 and Vg6, the switching elements Q5, Q6, Q7, and Q8 form a BUCK-BOOST conversion through the resonant inductor L2 and the capacitor C4, and the voltage across the capacitor C4 is controlled, thereby controlling the voltage at the reference potential C.

[0090] According to the present embodiment, the voltage at the reference potential C can be buck-boost controlled.

[0091] In addition, in the present disclosure, any changes or substitutions that can be conceived by those skilled in the art can be made to the BUCK control in the fourth embodiment and the BUCK-BOOST control in the fifth embodiment.

[0092] 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 connected between an input power supply and a reference potential, 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 connected in parallel with the first bridge arm between the input power supply and the reference potential, and comprising a first capacitor and a second capacitor connected in series, wherein the first capacitor and the second capacitor are connected to form a second connection point; a coupled inductor unit connected between the first connection point and the second connection point, and having a center tap connected to a load; and The first resonant inductor is connected in series with the coupled inductor unit between the first connection point and the second connection point, and forms a series resonant circuit with the first capacitor and the second capacitor, respectively.

2. The power converter according to claim 1, wherein: The coupled inductor unit includes a first coil and a second coil that are magnetically coupled. One end of the first coil is connected to one end of the second coil to form the center tap. The power converter further includes an output smoothing capacitor and a third switching element and a fourth switching element as rectifying elements. The other end of the first coil is connected to the third switching element. The other end of the second coil is connected to the fourth switching element. The third switch element is connected to the fourth switch element to form a third connection point, The output filter capacitor is connected between the center tap and the third connection point.

3. The power converter according to claim 2, wherein: The coupled inductor unit further includes a third coil connected between the first coil and the second connection point.

4. The power converter according to claim 1, wherein: The capacitance of the first capacitor is equal to the capacitance of the second capacitor.

5. The power converter according to claim 1, wherein: The first resonant inductor is formed by line parasitic inductance.

6. The power converter according to claim 1, wherein: The resonant frequency of the series resonant circuit is the same as the operating frequency of the power converter.

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

8. The power converter according to claim 1, wherein: The coupled inductor unit includes a first coil and a second coil that are magnetically coupled. One end of the first coil and one end of the second coil are connected to form the center tap, the other end of the first coil is connected to the second connection point, and the other end of the second coil is connected to the first connection point. The power converter further comprises an output filter capacitor and a first rectifier bridge arm and a second rectifier bridge arm respectively connected in parallel with the output filter capacitor. The first rectifier bridge arm includes a third switch element and a fifth switch element connected in series, and a connection point between the third switch element and the fifth switch element is connected to the center tap. The second rectifier bridge arm includes a fourth switching element and a sixth switching element connected in series, a connection point between the fourth switching element and the sixth switching element is connected to the first connection point, One end of the output filter capacitor is connected to the fourth switching element and the fifth switching element. The other end of the output smoothing capacitor is connected to the third switching element and the sixth switching element.

9. The power converter according to claim 8, wherein: The number of turns of the first coil is zero, The number of turns of the second coil is an arbitrary natural number.

10. The power converter according to any one of claims 2 to 7, wherein: The first switch element group includes the first switch element and the third switch element, The second switch element group includes the second switch element and the fourth switch 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 claim 8 or 9, wherein: The first switch element group includes the first switch element, the third switch element and the fourth switch element, The second switch element group includes the second switch element, the fifth switch element and the sixth switch 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.

13. The power converter according to claim 12, 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.

14. The power converter according to any one of claims 1 to 9, wherein: The power converter further includes a reference potential control unit for controlling the voltage of the reference potential. The reference potential control unit comprises: a third capacitor connected between the reference potential and the base potential; a third bridge arm connected between an input power supply and the reference potential, comprising a fifth switch element and a sixth switch element connected in series, wherein the fifth switch element and the sixth switch element are connected to form a fourth connection point; and A second resonant inductor is connected between the fourth connection point and the reference potential.

15. The power converter according to any one of claims 1 to 9, wherein: The reference potential control unit further includes a fourth bridge arm, the fourth bridge arm is connected between the reference potential and the base potential, and includes a seventh switch element and an eighth switch element connected in series, the seventh switch element is connected to the eighth switch element to form a fifth connection point, The second resonant inductor is connected between the fourth connection point and the fifth connection point.

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