CN118316314A - Resonant converter - Google Patents

Abstract

The present disclosure provides a resonant converter that may be applied in the field of power electronic converters. The resonant converter includes: the full-bridge inverter circuit is respectively configured to be connected with two ends of an input power supply at a first end and a second end; the resonant circuit comprises a first capacitor, a variable capacitor unit and a first inductor which are sequentially connected in series, wherein one end of the first capacitor is configured to be connected with the midpoint of a first half-bridge of the full-bridge inverter circuit, and one end of the first inductor is configured to be connected with the midpoint of a second half-bridge of the full-bridge inverter circuit; the transformer comprises a primary side and a secondary side, wherein the primary side is configured to be connected with the variable capacitance unit in parallel, and the secondary side is configured to be connected with the input end of the voltage doubling rectifying circuit; and a voltage doubler rectifying circuit, an output terminal of the voltage doubler rectifying circuit being configured to supply a target voltage to a load.

Description

Resonant Converter

Technical Field

The present disclosure relates to the field of power electronic converters, and more specifically, to a resonant converter.

Background technique

High-voltage power supply is the core technology in application scenarios such as electrostatic dust removal, X-ray imaging, and semiconductor material preparation. High-voltage power supply can convert the input low-voltage AC power and output high-voltage DC load power supply with a voltage of tens of kilovolts or even hundreds of thousands of volts. As the power device of the system, the technical level of high-voltage DC load power supply directly affects the performance of the equipment system.

In the process of realizing the concept of the present disclosure, the inventors found that the device performance of the resonant converter in the related art was insufficient and it was difficult to meet the power supply requirements of different responsibilities in actual applications.

Summary of the invention

In view of this, the present disclosure provides a resonant converter.

One aspect of the present disclosure provides a resonant converter, comprising:

A full-bridge inverter circuit, wherein the first end and the second end of the full-bridge inverter circuit are respectively configured to be connected to two ends of an input power supply;

A resonant circuit, comprising a first capacitor, a variable capacitor unit and a first inductor connected in series in sequence, wherein one end of the first capacitor is configured to be connected to a midpoint of a first half-bridge of the full-bridge inverter circuit, and one end of the first inductor is configured to be connected to a midpoint of a second half-bridge of the full-bridge inverter circuit;

A transformer, comprising a primary side and a secondary side, wherein the primary side is configured to be connected in parallel with the variable capacitance unit, and the secondary side is configured to be connected to an input end of a voltage doubler rectifier circuit; and

The above-mentioned voltage doubler rectifier circuit, the output end of the above-mentioned voltage doubler rectifier circuit is configured to provide a target voltage to a load.

According to an embodiment of the present disclosure, the above-mentioned resonant converter is configured to determine the equivalent impedance of the above-mentioned variable capacitor unit based on the switching frequency of the above-mentioned full-bridge inverter circuit, determine the resonant parameters of the above-mentioned resonant circuit based on the above-mentioned equivalent impedance, and adjust the input voltage provided by the above-mentioned input power supply based on the above-mentioned resonant parameters to obtain the above-mentioned target voltage.

According to an embodiment of the present disclosure, the variable capacitance unit includes a second inductor, a second capacitor and a third capacitor, wherein the second inductor is configured to be connected in series with the second capacitor, and the third capacitor is configured to be connected in parallel with the second inductor and the second capacitor.

According to an embodiment of the present disclosure, the switching frequency of the full-bridge inverter circuit is configured so that the second inductor and the second capacitor connected in series are equivalent to a capacitor.

According to an embodiment of the present disclosure, the third capacitor includes a winding parasitic capacitor of the transformer.

According to an embodiment of the present disclosure, the full-bridge inverter circuit includes a first field effect tube, a second field effect tube, a third field effect tube and a fourth field effect tube, wherein the first field effect tube and the second field effect tube constitute the first half bridge, and the third field effect tube and the fourth field effect tube constitute the second half bridge;

Among them, the drain of the above-mentioned first field effect tube and the drain of the above-mentioned third field effect tube are configured to be connected to the first end of the above-mentioned full-bridge inverter circuit, the source of the above-mentioned first field effect tube and the drain of the above-mentioned second field effect tube are configured to be connected to the midpoint of the above-mentioned first half bridge, the source of the above-mentioned second field effect tube and the source of the above-mentioned fourth field effect tube are configured to be connected to the second end of the above-mentioned full-bridge inverter circuit, and the source of the above-mentioned third field effect tube and the drain of the above-mentioned fourth field effect tube are configured to be connected to the midpoint of the above-mentioned second half bridge.

According to an embodiment of the present disclosure, the gate of the first field effect transistor, the gate of the second field effect transistor, the gate of the third field effect transistor, and the gate of the fourth field effect transistor are configured to be respectively connected to the controller to respectively receive respective control signals;

The controller is configured to control the voltage gain of the target voltage by modulating the duty cycle and phase shift angle of each of the control signals.

According to an embodiment of the present disclosure, the voltage doubling rectifier circuit includes N voltage doubling units, which are configured to be connected in parallel in sequence, and each of the voltage doubling units includes a fourth capacitor, a fifth capacitor, a first diode and a second diode, wherein N is a positive integer.

According to an embodiment of the present disclosure, one end of the fourth capacitor of the i-th voltage doubling unit is configured to connect to the anode of the second diode of the i-1-th voltage doubling unit, and the other end is configured to respectively connect to the cathode of the first diode of the i-th voltage doubling unit and the anode of the second diode of the i-th voltage doubling unit, the anode of the first diode of the i-th voltage doubling unit is configured to respectively connect to the cathode of the second diode of the i-1-th voltage doubling unit and one end of the fifth capacitor of the i-th voltage doubling unit, and the other end of the fifth capacitor of the i-th voltage doubling unit is configured to connect to the cathode of the second diode of the i-1-th voltage doubling unit, wherein the above i is a positive integer greater than 1 and less than or equal to the above N;

One end of the fourth capacitor of the first voltage doubling unit is configured to be connected to one end of the secondary side of the transformer, and the anode of the first diode of the first voltage doubling unit is configured to be connected to the other end of the secondary side;

The anode of the first diode of the first voltage doubling unit is configured to be connected to the negative electrode of the load, and the cathode of the second diode of the Nth voltage doubling unit is configured to be connected to the positive electrode of the load.

According to an embodiment of the present disclosure, the above-mentioned resonant converter further includes:

A support capacitor, wherein the support capacitor is configured to be connected in parallel with the full-bridge inverter circuit, the positive electrode of the support capacitor is configured to be connected to the first end of the full-bridge inverter circuit, and the negative electrode of the support capacitor is configured to be connected to the second end of the full-bridge inverter circuit.

According to the embodiments of the present disclosure, by introducing a variable capacitor unit in the resonant circuit of the resonant converter, the parameters of the resonant circuit can change with the switching frequency of the full-bridge inverter circuit, thereby achieving adaptation to a wide range of input voltage and load changes within a very small frequency change range. This enables the resonant converter to achieve a technical effect of having a higher power supply efficiency within a wide voltage and full load range.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

FIG1A schematically shows a schematic diagram of an LCC converter according to a comparative example of the present disclosure;

FIG1B schematically shows a schematic diagram of a voltage gain characteristic of an LCC converter according to a comparative example of the present disclosure;

FIG1C schematically shows a diagram of a curve showing a relationship between a phase shift angle and a voltage gain of an LCC converter according to a comparative example of the present disclosure;

FIG2 schematically shows a schematic diagram of a resonant converter according to an embodiment of the present disclosure;

FIG3 schematically shows a schematic diagram of a full-bridge inverter circuit according to an embodiment of the present disclosure;

FIG4 schematically shows a schematic diagram of a variable capacitance unit according to an embodiment of the present disclosure;

FIG5A schematically shows a schematic diagram of a voltage doubler rectifier circuit according to an embodiment of the present disclosure;

FIG5B schematically shows a schematic diagram of a voltage doubler rectifier circuit according to another embodiment of the present disclosure;

FIG6 schematically shows a schematic diagram of a resonant converter according to another embodiment of the present disclosure;

FIG7 schematically shows a schematic diagram of an equivalent capacitance characteristic curve of a resonant converter under different switching frequencies according to an embodiment of the present disclosure;

FIG8 schematically shows a schematic diagram of a voltage gain characteristic curve of a resonant converter according to an embodiment of the present disclosure;

FIG. 9 schematically shows a diagram of a curve showing a relationship between a phase shift angle and a voltage gain of a resonant converter according to an embodiment of the present disclosure.

Detailed ways

Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "include", "comprising", etc. used herein indicate the existence of the features, steps, operations and/or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification, and should not be interpreted in an idealized or overly rigid manner.

In the case of using expressions such as "at least one of A, B, and C, etc.", it should generally be interpreted in accordance with the meaning of the expression generally understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and/or A, B, C, etc.). In the case of using expressions such as "at least one of A, B, or C, etc.", it should generally be interpreted in accordance with the meaning of the expression generally understood by those skilled in the art (for example, "a system having at least one of A, B, or C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and/or A, B, C, etc.).

In the technical solution disclosed in the present invention, the acquisition, storage and application of user personal information involved are in compliance with the provisions of relevant laws and regulations, necessary confidentiality measures are taken, and do not violate public order and good morals.

In the technical solution of the present disclosure, the user's authorization or consent is obtained before obtaining or collecting the user's personal information.

In the related art, LCC resonant converters (LLC resonant converters) often use modulation methods such as variable frequency, fixed frequency phase shift or fixed frequency variable duty cycle. The variable frequency modulation method adjusts the output voltage by changing the switching frequency of the LCC resonant converter. When the switching frequency is higher than the peak frequency, it can achieve soft switching of the power switch tube, so it has higher efficiency; but when the voltage gain or output load changes in a wide range, the switching frequency changes in a wide range, the voltage/current stress of the power device is large, which is not conducive to the design of inductors, transformers and EMI filters, and the loss is large, resulting in reduced efficiency.

The idea of the phase shift modulation method or the variable duty cycle modulation method is the same, both of which are to achieve output voltage regulation by changing the voltage pulse width applied to the resonant cavity of the LCC resonant converter. Because its switching frequency is fixed, it is conducive to the design of magnetic components and is easy to achieve high frequency and high power density. However, the voltage gain of the converter under this modulation method varies greatly with the load, so that the converter can only be designed according to the lower limit of the gain range. As the load decreases, the soft switching condition of the switch tube (field effect tube) is easily lost, and as the load increases, the voltage gain of the circuit is significantly reduced. Especially in boost circuit applications, to achieve a larger range of output voltage regulation, a minimum load must be limited, which reduces the adjustable range of the phase shift angle. Therefore, the phase shift or variable duty cycle modulation method is suitable for applications with a smaller range of voltage and load changes.

In practical applications, the voltage and load of the LCC resonant converter are not constant. When the working conditions change, the LCC resonant converter will deviate from its optimal steady-state operating point, resulting in low converter efficiency and loss of soft switching characteristics of the switch tube. It is crucial to control the working mode of the converter in a changing working environment to maintain its stable working state. Although this can be achieved by changing the circuit control strategy and the parameters of the resonant components, the changes brought about by changing the control strategy are very limited. In practical applications, once the passive components such as capacitors and inductors are designed, the parameters of the resonant cavity cannot be changed. Therefore, in order to meet the wide range of voltage or load changes, it is necessary to study and propose a suitable LCC resonant converter.

FIG. 1A schematically shows a schematic diagram of an LCC converter according to a comparative example of the present disclosure.

As shown in FIG1A , the LCC converter 100 based on the LCC topology structure is mainly composed of a full-bridge inverter module 110, an LCC resonant cavity 120, a step-up transformer 130 and an output voltage doubler rectifier circuit 140. The LCC resonant cavity 120 is composed of a resonant inductor L _r , a series resonant capacitor C _r , and a parallel resonant capacitor C _p . In a steady state, a square wave is output to the full-bridge inverter module 110 through a power supply 150, and power output and soft switching of the switch tube (field effect tube Q ₁ ~ Q ₄ ) are realized through different resonant states of the resonant inductor L _r , the series resonant capacitor C _r , and the parallel resonant capacitor C _p in the switching cycle. The parameter design of the LCC resonant cavity 120 and its control method are the key points and difficulties of the high-power high-voltage DC power supply, and its working state is directly related to the working quality of the power supply system.

Table I

parameter symbol Numeric Input voltage V _in 200V The output voltage V _o 400V rated power P _o 1000W Resonant Inductor _L 110uF Series resonant capacitor C _r 0.2uF Series resonant capacitor C _p 0.25uF Transformer ratio N 0.5

Table 1 may represent the parameters of the LCC converter 100 of the comparative example of the present disclosure. Based on the above design parameters.

Further, the operating characteristic information of the LCC converter 100 according to the comparative example of the present disclosure can be determined by the following formula (1) and formula (2).

In the above formulas (1) and (2), θ is the phase shift angle, N is the transformation ratio of the boost transformer 130, fs is the switching frequency of the full-bridge inverter module 110, fr is the resonant frequency of the LCC resonant cavity 120, and Q is the quality factor of the LCC converter. By adjusting the phase shift angle θ or the switching frequency fs, the output voltage of the LCC converter can be adjusted.

FIG. 1B schematically shows a schematic diagram of voltage gain characteristics of an LCC converter according to a comparative example of the present disclosure.

FIG1C schematically shows a diagram of a curve showing a relationship between a phase shift angle and a voltage gain of an LCC converter according to a comparative example of the present disclosure.

1B and 1C , the LCC converter 100 of the comparative example of the present disclosure can be set by the parameters in Table 1. Under different load conditions, the voltage gain characteristics of the LCC converter 100 can be represented by FIG. 1B .

When the parameters are set correctly (fs=55kHz), the influence of the phase angle θ on the voltage gain M can be shown in FIG. 1C .

As shown in FIG1B , when the variable frequency control method is used to modulate the LCC converter 100, when the voltage gain is set to M=2, the switching frequency changes in a wide range (from 54kHz to 43kHz) with the load changing from 10% to 100% under the condition of constant input voltage. The maximum gain of the LCC converter is determined by the 100% load condition, and a higher gain requirement (such as M=3) cannot be achieved.

As shown in FIG. 1C , when the phase-shift control method is used to modulate the LCC converter 100, even if a larger voltage gain and a wider gain range can be achieved under other load conditions, the maximum gain and gain range of the LCC converter can only be designed to be 0.91 under 100% load conditions, which greatly limits the working conditions of the converter.

In view of this, an embodiment of the present disclosure provides a resonant converter in order to at least partially solve the above technical problems. Specifically, the resonant converter includes: a resonant converter, including: a full-bridge inverter circuit, the first end and the second end of the full-bridge inverter circuit are respectively configured to connect the two ends of the input power supply; a resonant circuit, including a first capacitor, a variable capacitor unit and a first inductor connected in series in sequence, wherein one end of the first capacitor is configured to connect the midpoint of the first half-bridge of the full-bridge inverter circuit, and one end of the first inductor is configured to connect the midpoint of the second half-bridge of the full-bridge inverter circuit; a transformer, including a primary side and a secondary side, wherein the primary side is configured to be connected in parallel with the variable capacitor unit, and the secondary side is configured to connect the input end of the voltage doubler rectifier circuit; and a voltage doubler rectifier circuit, the output end of the voltage doubler rectifier circuit is configured to provide a target voltage to the load.

According to the embodiments of the present disclosure, by introducing a variable capacitor unit in the resonant circuit of the resonant converter, the parameters of the resonant circuit can change with the switching frequency of the full-bridge inverter circuit, thereby achieving adaptation to a wide range of input voltage and load changes within a very small frequency change range. This enables the resonant converter to achieve a technical effect of having a higher power supply efficiency within a wide voltage and full load range.

FIG. 2 schematically shows a schematic diagram of a resonant converter according to an embodiment of the present disclosure.

As shown in FIG. 2 , the resonant converter includes: a full-bridge inverter circuit 210 , a resonant circuit 220 , a transformer 230 and a voltage doubler rectifier circuit 240 .

The first end and the second end of the full-bridge inverter circuit 210 are respectively configured to be connected to two ends of the input power source 250 .

The resonant circuit 220 includes a first capacitor _Cr , a variable capacitance unit 221 and a first inductor _Lr connected in series in sequence, wherein one end of the first capacitor _Cr is configured to connect to the midpoint of the first half bridge of the full-bridge inverter circuit 210, and one end of the first inductor _Lr is configured to connect to the midpoint of the second half bridge of the full-bridge inverter circuit 210.

The transformer 230 includes a primary side and a secondary side, wherein the primary side is configured to be connected in parallel with the variable capacitor unit 221 , and the secondary side is configured to be connected to the input end of the voltage doubler rectifier circuit 240 .

The output terminal of the voltage doubler rectifier circuit 240 is configured to provide a target voltage to the load 260 .

According to the embodiment of the present disclosure, the full-bridge inverter circuit 210 can be formed by field effect transistors, diodes and other components in the related art. The embodiment of the present disclosure does not limit the specific circuit structure of the full-bridge inverter circuit, and those skilled in the art can select it according to actual needs.

According to the embodiments of the present disclosure, the variable capacitance unit 221 may include an element or device capable of changing the capacitance value, such as a solid dielectric variable capacitor, a gas dielectric variable capacitor, etc. in the related art. The embodiments of the present disclosure do not limit the specific type of the variable capacitance unit 221, and those skilled in the art may select it according to actual needs, as long as the capacitance value can be changed.

According to an embodiment of the present disclosure, the full-bridge inverter circuit 210 may include a first half-bridge and a second half-bridge. The full-bridge inverter circuit 210 controls the AC current waveform input by the AC power source 250 through the switching state, so that the AC current waveform is synchronized with the AC voltage waveform. At the same time, the output voltage can also be controlled.

It should be understood that the left side of the transformer 230 may be the primary side of the transformer 230, and the right side may be the secondary side of the transformer 230. The transformer 230 may be used for electrical isolation between the primary side and the secondary side, energy transmission, and increasing the voltage level of the secondary side.

According to an embodiment of the present disclosure, the voltage doubler rectifier circuit 240 is used to rectify and filter the high frequency AC voltage output by the transformer 230, thereby outputting a DC voltage to the load 260. The voltage doubler rectifier circuit 240 can be constructed by an N-order half-wave voltage doubler rectifier circuit in the related art.

According to an embodiment of the present disclosure, the number of turns of the primary coil of the transformer 230 may be smaller than the number of turns of the secondary coil.

According to an embodiment of the present disclosure, when the voltage doubler rectifier circuit 240 includes an N-order half-wave voltage doubler rectifier circuit, and when the primary-to-secondary coil turns ratio of the transformer 230 is 1:M, that is, the primary-to-secondary transformation ratio between the primary and secondary sides is 1:M, the voltage step-up ratio that can be achieved by the transformer 230 and the voltage doubler rectifier circuit 240 can be M×N, thereby increasing the voltage level provided to the load 260.

According to the embodiments of the present disclosure, by introducing a variable capacitor unit in the resonant circuit of the resonant converter, the parameters of the resonant circuit can change with the switching frequency of the full-bridge inverter circuit, thereby achieving adaptation to a wide range of input voltage and load changes within a very small frequency change range. This enables the resonant converter to achieve a technical effect of having a higher power supply efficiency within a wide voltage and full load range.

FIG3 schematically shows a schematic diagram of a full-bridge inverter circuit according to an embodiment of the present disclosure.

As shown in FIG3 , the full-bridge inverter circuit 210 includes a first field effect transistor Q ₁ , a second field effect transistor Q ₂ , a third field effect transistor Q ₃ and a fourth field effect transistor Q ₄ , wherein the first field effect transistor Q 1 and the second field effect transistor Q ₂ constitute a first half-bridge 211 , and the third field effect transistor and the fourth field effect transistor constitute a second half-bridge 212 ;

As shown in Figures 2 and 3, the drain of the first field effect transistor _Q1 and the drain of the third field effect transistor _Q3 are configured to be connected to the first end of the full-bridge inverter circuit 210, the source of the first field effect transistor _Q1 and the drain of the second field effect transistor _Q2 are configured to be connected to the midpoint of the first half-bridge 211, the source of the second field effect transistor _Q2 and the source of the fourth field effect transistor _Q4 are configured to be connected to the second end of the full-bridge inverter circuit 210, and the source of the third field effect transistor _Q3 and the drain of the fourth field effect transistor _Q4 are configured to be connected to the midpoint of the second half-bridge 212.

According to the embodiments of the present disclosure, the first field effect transistor to the fourth field effect transistor may be an NPN enhanced field effect transistor, that is, an N-channel field effect transistor. However, it is not limited thereto, and may also be a PNP field effect transistor, that is, a P-channel field effect transistor. Those skilled in the art may adjust the connection relationship between the first field effect transistor and the fourth field effect transistor when selecting a PNP field effect transistor as any one of the first field effect transistor to the fourth field effect transistor, and the embodiments of the present disclosure do not limit this.

As shown in FIG3 , the first field effect transistor _Q1 and the third field effect transistor _Q3 can be used as upper switch transistors of the DC-AC converter, and the second field effect transistor _Q2 and the fourth field effect transistor _Q4 can be used as lower switch transistors of the DC-AC converter.

FIG. 4 schematically shows a schematic diagram of a variable capacitance unit according to an embodiment of the present disclosure.

2 to 4 , the variable capacitance unit 221 includes a second inductor _La , a second capacitor _Ca and a third capacitor C _P , wherein the second inductor _La is configured to be connected in series with the second capacitor _Ca , and the third capacitor C _P is configured to be connected in parallel with the second inductor _La and the second capacitor _Ca.

According to the embodiments of the present disclosure, the variable capacitance unit 221 is constructed by the second inductor _La , the second capacitor _Ca and the third capacitor C _P , which can reduce the number of components of the variable capacitance unit, simplify the overall circuit complexity of the resonant converter, and reduce the manufacturing difficulty, thereby achieving the technical effect of improving the working reliability and preparation efficiency of the resonant converter.

According to an embodiment of the present disclosure, the switching frequency of the full-bridge inverter circuit 210 is configured such that the second inductor _La and the second capacitor _Ca connected in series are equivalent to a capacitor.

According to an embodiment of the present disclosure, the resonant converter is configured to determine the equivalent impedance of the variable capacitor unit 221 based on the switching frequency of the full-bridge inverter circuit 210, determine the resonant parameters of the resonant circuit 220 based on the equivalent impedance, and adjust the input voltage provided by the input power supply based on the resonant parameters to obtain the target voltage.

As shown in FIG4 , according to the connection relationship between the second inductor _La , the second capacitor _Ca and the third capacitor C _P in the variable capacitor unit 221, it can be known that the equivalent impedance can be changed by changing the switching frequency of the full-bridge inverter circuit 210. Therefore, by changing the frequency within an appropriate range, the variable capacitor unit 221 can be switched between inductance or capacitance, so that the parameters of the variable capacitor unit 221 can also be changed. By changing the switching frequency of the full-bridge inverter circuit 210, the overall resonant cavity parameters of the resonant converter can be adjusted in real time to adapt to different power supply voltages and load conditions, thereby improving the adaptability of the resonant converter.

According to an embodiment of the present disclosure, the voltage doubler rectifier circuit 240 includes N voltage doubler units, which are configured to be connected in parallel in sequence, and each voltage doubler unit includes a fourth capacitor, a fifth capacitor, a first diode and a second diode, where N is a positive integer.

According to an embodiment of the present disclosure, one end of the fourth capacitor of the i-th voltage multiplier unit is configured to connect to the anode of the second diode of the i-1-th voltage multiplier unit, and the other end is configured to respectively connect to the cathode of the first diode of the i-th voltage multiplier unit and the anode of the second diode of the i-th voltage multiplier unit, the anode of the first diode of the i-th voltage multiplier unit is configured to respectively connect to the cathode of the second diode of the i-1-th voltage multiplier unit and one end of the fifth capacitor of the i-th voltage multiplier unit, and the other end of the fifth capacitor of the i-th voltage multiplier unit is configured to connect to the cathode of the second diode of the i-1-th voltage multiplier unit, wherein i is a positive integer greater than 1 and less than or equal to N;

One end of the fourth capacitor of the first voltage doubling unit is configured to be connected to one end of the secondary side of the transformer 230, and the anode of the first diode of the first voltage doubling unit is configured to be connected to the other end of the secondary side;

The anode of the first diode of the first voltage multiplier unit is configured to be connected to the negative electrode of the load, and the cathode of the second diode of the Nth voltage multiplier unit is configured to be connected to the positive electrode of the load.

FIG5A schematically shows a schematic diagram of a voltage doubler rectifier circuit according to an embodiment of the present disclosure.

As shown in FIG. 5A , the voltage doubler rectifier circuit 240 in this embodiment may include two voltage doubler units, namely, a first voltage doubler unit 241 and a second voltage doubler unit 242 .

The first voltage doubling unit 241 includes a fourth capacitor CH ₁₄ , a first diode DH ₁₁ , a fifth capacitor CH ₁₅ and a second diode DH ₁₂ . The second voltage doubling unit 242 includes a fourth capacitor CH ₂₄ , a first diode DH ₂₁ , a fifth capacitor CH ₂₅ and a second diode DH ₂₂ .

The anode of the first diode _DH11 of the first voltage doubler unit 241 is connected to the third terminal of the voltage doubler rectifier circuit 240 , so that the anode of the first diode _DH11 and the fourth capacitor _CH14 of the first voltage doubler unit 241 are connected to the transformer 243 .

A cathode of the first diode _DH11 of the first voltage doubler unit 241 and a cathode of the second diode DH22 of the second voltage doubler unit ₂₄₂ are connected to a load 260 .

FIG5B schematically shows a schematic diagram of a voltage doubler rectifier circuit according to another embodiment of the present disclosure.

As shown in FIG. 5B , the voltage doubler rectifier circuit 240 in this embodiment may include N voltage doubler units, that is, the voltage doubler rectifier circuit 240 includes a first voltage doubler unit 241 to an Nth voltage doubler unit 24N.

The first voltage doubling unit 241 includes a fourth capacitor CH ₁₄ , a first diode DH ₁₁ , a fifth capacitor CH ₁₅ and a second diode DH ₁₂ . The Nth voltage doubling unit 24N includes a fourth capacitor CH _N4 , a first diode DH _N1 , a fifth capacitor CH _N5 and a second diode DH _N2 .

One end of the fourth capacitor CH _N4 of the Nth voltage multiplier unit 24N is connected to the anode of the second diode of the N-1th voltage multiplier unit, and the other end of the fourth capacitor CH _N4 is configured to be respectively connected to the cathode of the first diode DH _N1 of the Nth voltage multiplier unit 24N and the anode of the second diode DH _N2 of the Nth voltage multiplier unit 24N, the anode of the first diode DH _N1 of the Nth voltage multiplier unit 24N is respectively connected to the cathode of the N-1th voltage multiplier unit and one end of the fifth capacitor CH _N5 of the Nth voltage multiplier unit 24N, and the other end of the fifth capacitor CH _N5 of the Nth voltage multiplier unit 24N is connected to the cathode of the second diode DH _N2 of the Nth voltage multiplier unit 24N.

The anode of the first diode _DH11 of the first voltage doubling unit 241 is connected to the third terminal of the voltage doubling rectifier circuit 240, and the cathode of the second diode _DHN2 of the Nth voltage doubling unit 24N is connected to the fourth terminal of the voltage doubling rectifier circuit 240. The third terminal and the fourth terminal of the voltage doubling rectifier circuit 240 are connected to the load 260 to realize power supply to the load 260.

It should be noted that the embodiments of the present disclosure do not limit the number of N, and those skilled in the art may select it according to actual needs.

FIG6 schematically shows a schematic diagram of a resonant converter according to another embodiment of the present disclosure.

As shown in FIG. 6 , the resonant converter may further include a support capacitor C _in .

The support capacitor C _in is configured to be connected in parallel with the full-bridge inverter circuit 210 , the positive electrode of the support capacitor C _in is configured to be connected to the first end of the full-bridge inverter circuit 210 , and the negative electrode of the support capacitor C _in is configured to be connected to the second end of the full-bridge inverter circuit 210 .

According to an embodiment of the present disclosure, the third capacitor C _P includes a winding parasitic capacitance of the transformer 230 .

As shown in Figures 4 and 6, the third capacitor C _P in the variable capacitor unit 221 can be implemented by the parasitic capacitance of the winding of the transformer 230, thereby further reducing the number of components of the resonant converter, simplifying the circuit structure load of the resonant converter, and improving the equipment reliability of the resonant converter.

According to the implementation of the present disclosure, a variable capacitance unit is constructed by connecting the second inductor _La in series with the second capacitor _Ca , and the third capacitor C _P in parallel with the second inductor _La and the second capacitor _Ca , and the variable capacitance unit 221 (i.e., the resonant capacitor C _pequ ) is introduced into the resonant converter. According to the characteristics of the resonant series circuit (i.e., the second inductor _La and the second capacitor _Ca connected in series), the switching frequency is changed, that is, the equivalent impedance also changes accordingly. By changing the frequency within an appropriate range, the resonant series circuit can be made equivalent to inductive or capacitive, so the parameters of the resonant circuit 220 also change accordingly. Based on this principle, by changing the switching frequency, the resonant cavity parameters of the resonant converter can be adjusted in real time to adapt to different voltage and load conditions.

FIG. 7 schematically shows a schematic diagram of an equivalent capacitance characteristic curve of a resonant converter under different switching frequencies according to an embodiment of the present disclosure.

FIG8 schematically shows a schematic diagram of a voltage gain characteristic curve of a resonant converter according to an embodiment of the present disclosure.

FIG. 9 schematically shows a diagram of a curve showing a relationship between a phase shift angle and a voltage gain of a resonant converter according to an embodiment of the present disclosure.

As shown in FIG. 4 to FIG. 9 , by setting the parameters of the second inductor _La and the second capacitor _Ca in the resonant converter to _La = 80uH, _Ca = 0.25uF, and setting other parameters of the resonant converter provided by the embodiment of the present disclosure according to the contents shown in Table 1, the equivalent capacitance characteristic curve under different switching frequencies as shown in FIG. 7 can be obtained.

Furthermore, the resonant converter designed based on the above parameters can also obtain corresponding voltage gain characteristics under different loads (as shown in Figure 8), as well as the influence of the phase shift angle θ on the voltage gain M after changing the equivalent parallel resonant capacitor Cpequ by adjusting the switching frequency (as shown in Figure 9).

As shown in FIG8 , compared with the LCC converter provided in the comparative example of the present disclosure, the resonant converter provided in the embodiment of the present disclosure can obtain a higher voltage gain. The maximum voltage gain of the resonant converter provided in the embodiment of the present disclosure under full load can reach 3.6, while the LCC converter provided in the comparative example of the present disclosure can only provide a maximum voltage gain of 2.3. At the same time, the frequency variation range of the LCC converter provided in the comparative example of the present disclosure is small, and it is difficult to adapt to a wider range of voltage changes.

As shown in Figure 9, within the overall variation range of the phase shift angle θ, the voltage gain characteristic curves of the resonant converter provided by the embodiment of the present disclosure under different load conditions are very different. When θ=0, the voltage gain difference under different load conditions is the largest, but it is still much smaller than the LCC converter provided in the comparative example of the present disclosure. In addition, in order to make the equivalent parallel resonant capacitor _Cpeq (that is, the variable capacitor unit 221) match the change in load or voltage, its frequency variation range is very small, only 43.7kHz~45.4kHz, and the influence of the variable capacitor unit 221 on devices such as inductors, transformers and filters can be ignored. Therefore, the resonant converter provided by the embodiment of the present disclosure is more suitable for application scenarios where the voltage or load changes over a wide range.

According to an embodiment of the present disclosure, the gate of the first field effect transistor _Q1 , the gate of the second field effect transistor _Q2 , the gate of the third field effect transistor _Q3 and the gate of the fourth field effect transistor _Q4 are configured to be respectively connected to the controller to respectively receive respective control signals.

The controller is configured to control the voltage gain of the target voltage by modulating the duty cycle and phase shift angle of each control signal.

According to the embodiments of the present disclosure, by controlling the gates of the first field effect transistor _Q1 to the fourth field effect transistor _Q4 of the full-bridge inverter circuit through a controller, the voltage gain can be controlled, thereby further improving the operating characteristics of the resonant converter to adapt to different operating requirements and improve the working stability and reliability of the resonant converter.

It will be appreciated by those skilled in the art that the features described in the various embodiments and/or claims of the present disclosure may be combined and/or combined in a variety of ways, even if such combinations and/or combinations are not explicitly described in the present disclosure. In particular, the features described in the various embodiments and/or claims of the present disclosure may be combined and/or combined in a variety of ways without departing from the spirit and teachings of the present disclosure. All of these combinations and/or combinations fall within the scope of the present disclosure.

The embodiments of the present disclosure are described above. However, these embodiments are only for illustrative purposes and are not intended to limit the scope of the present disclosure. Although the embodiments are described above separately, this does not mean that the measures in the various embodiments cannot be used in combination to advantage. The scope of the present disclosure is defined by the attached claims and their equivalents. Without departing from the scope of the present disclosure, those skilled in the art may make a variety of substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims (10)

1. A resonant converter, comprising: A full-bridge inverter circuit, wherein a first end and a second end of the full-bridge inverter circuit are respectively configured to be connected to two ends of an input power supply; A resonant circuit, comprising a first capacitor, a variable capacitance unit and a first inductor connected in series in sequence, wherein one end of the first capacitor is configured to be connected to a midpoint of a first half-bridge of the full-bridge inverter circuit, and one end of the first inductor is configured to be connected to a midpoint of a second half-bridge of the full-bridge inverter circuit; A transformer, comprising a primary side and a secondary side, wherein the primary side is configured to be connected in parallel with the variable capacitance unit, and the secondary side is configured to be connected to an input end of a voltage doubler rectifier circuit; and The voltage doubler rectifier circuit, the output end of the voltage doubler rectifier circuit is configured to provide a target voltage to a load. 2. The resonant converter according to claim 1, wherein the resonant converter is configured to determine the equivalent impedance of the variable capacitor unit based on the switching frequency of the full-bridge inverter circuit, determine the resonant parameters of the resonant circuit based on the equivalent impedance, and adjust the input voltage provided by the input power supply based on the resonant parameters to obtain the target voltage. 3. The resonant converter according to claim 1, wherein the variable capacitance unit comprises a second inductor, a second capacitor and a third capacitor, wherein the second inductor is configured to be connected in series with the second capacitor, and the third capacitor is configured to be connected in parallel with the second inductor and the second capacitor. 4 . The resonant converter according to claim 3 , wherein a switching frequency of the full-bridge inverter circuit is configured so that the second inductor and the second capacitor connected in series are equivalent to a capacitor. 5 . The resonant converter of claim 3 , wherein the third capacitor comprises a winding parasitic capacitance of the transformer. 6. The resonant converter according to claim 1, wherein the full-bridge inverter circuit comprises a first field effect transistor, a second field effect transistor, a third field effect transistor and a fourth field effect transistor, wherein the first field effect transistor and the second field effect transistor constitute the first half bridge, and the third field effect transistor and the fourth field effect transistor constitute the second half bridge; Among them, the drain of the first field effect tube and the drain of the third field effect tube are configured to connect the first end of the full-bridge inverter circuit, the source of the first field effect tube and the drain of the second field effect tube are configured to connect the midpoint of the first half bridge, the source of the second field effect tube and the source of the fourth field effect tube are configured to connect the second end of the full-bridge inverter circuit, and the source of the third field effect tube and the drain of the fourth field effect tube are configured to connect the midpoint of the second half bridge. 7. The resonant converter according to claim 6, wherein the gate of the first field effect transistor, the gate of the second field effect transistor, the gate of the third field effect transistor and the gate of the fourth field effect transistor are configured to be respectively connected to a controller to respectively receive respective control signals; The controller is configured to control the voltage gain of the target voltage by modulating the duty cycle and phase shift angle of each of the control signals. 8. The resonant converter according to claim 1, wherein the voltage doubler rectifier circuit comprises N voltage doubler units, the N voltage doubler units are configured to be connected in parallel in sequence, each of the voltage doubler units comprises a fourth capacitor, a fifth capacitor, a first diode and a second diode, wherein N is a positive integer. 9. The resonant converter according to claim 8, wherein one end of the fourth capacitor of the i-th voltage doubler unit is configured to be connected to the anode of the second diode of the i-1-th voltage doubler unit, and the other end is configured to be respectively connected to the cathode of the first diode of the i-th voltage doubler unit and the anode of the second diode of the i-th voltage doubler unit, the anode of the first diode of the i-th voltage doubler unit is configured to be respectively connected to the cathode of the second diode of the i-1-th voltage doubler unit and one end of the fifth capacitor of the i-th voltage doubler unit, and the other end of the fifth capacitor of the i-th voltage doubler unit is configured to be connected to the cathode of the second diode of the i-1-th voltage doubler unit, wherein i is a positive integer greater than 1 and less than or equal to N; One end of the fourth capacitor of the first voltage doubling unit is configured to be connected to one end of the secondary side of the transformer, and the anode of the first diode of the first voltage doubling unit is configured to be connected to the other end of the secondary side; The anode of the first diode of the first voltage multiplier unit is configured to be connected to the negative electrode of the load, and the cathode of the second diode of the Nth voltage multiplier unit is configured to be connected to the positive electrode of the load. 10. The resonant converter according to claim 1, further comprising: A support capacitor, wherein the support capacitor is configured to be connected in parallel with the full-bridge inverter circuit, the positive electrode of the support capacitor is configured to be connected to the first end of the full-bridge inverter circuit, and the negative electrode of the support capacitor is configured to be connected to the second end of the full-bridge inverter circuit.