Efficient combined resonant DC-AC converter for high-frequency AC power distribution system
By combining the design of CLCL resonant converter and Buck converter, soft switches and high-efficiency energy transmission in high-frequency AC distribution systems are realized, solving the problem of hard switches and low efficiency of existing high-frequency inverters, and has low THD and wide range adaptability.
Patent Information
- Application Number
- CN202510406063.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-02
- Publication Date
- 2025-07-01
AI Technical Summary
Existing high-frequency inverters have hard switching problems in high-frequency AC distribution systems, their efficiency needs to be improved, and the output voltage THD is high, so they cannot maintain high efficiency and stability within a wide input and wide load range.
The combined structure of the main power circuit CLCL resonant converter and the partial power circuit Buck converter is adopted, and soft switches are realized through the resonant network and the H-bridge circuit, and the variable duty cycle modulation strategy and complementary conduction bridge arm design are used to achieve efficient energy flow and low THD output.
The soft switch of the converter is realized, which reduces switching losses, improves the efficiency of power transmission, reduces total harmonic distortion, and has the ability to adapt to a wide input and a wide load range. It has a simple structure and low cost.
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Figure CN120237975A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of DC-AC converters, and particularly relates to an efficient combined resonant DC-AC converter for high-frequency AC power distribution systems. Background Art
[0002] High-frequency AC power distribution systems have been widely used in many industrial applications. As a key component of high-frequency AC (HFAC) systems, high-frequency inverters are the core hub connecting DC power sources to HFAC buses, and have an important impact on the reliability and power quality of the entire power distribution system. Compared with DC distributed power systems, they have the advantages of high efficiency, safety, and simple structure. However, the performance of existing high-frequency inverters is still insufficient. The paper "High Frequency AC Power Distribution Network for Electric Vehicle Auxiliary Electrical System" published in the IEEE Energy Conversion Congress and Exposition journal in 2020 proposed a current-source half-bridge CLCL high-frequency resonant inverter topology. The filter uses a CLCL parallel-series resonant network, which can effectively reduce the output voltage THD and has the characteristic that the output voltage is not affected by load changes, but there is a hard-switching problem for the switching tubes. The paper "A Soft-Switching Current-Fed Resonant Inverter for HFAC EV Auxiliary Electrical System" published in the IEEE Transactions on Transportation Electrification journal in 2024 proposed an improved CLCL resonant inverter topology. This topology has the ability to regulate the output voltage, can operate under wide input voltage conditions, and the THD is less than 2% within the entire load range, and the output voltage quality is relatively high, but the efficiency needs to be improved. Summary of the Invention
[0003] Aiming at the deficiencies of the above-mentioned existing technologies, the purpose of the present invention is to provide an efficient combined resonant DC-AC converter for high-frequency AC power distribution systems, which can improve the power transmission efficiency and system reliability, achieve soft switching, and has many advantages such as low total harmonic distortion of the output voltage, wide input and wide load ranges.
[0004] To achieve the above purpose, the present invention provides the following technical solutions:
[0005] An efficient combined resonant DC-AC converter for a high-frequency AC power distribution system, which is composed of a main power circuit CLCL resonant converter and a partial power circuit Buck converter; wherein, the main power circuit CLCL resonant converter includes a primary circuit of a high-frequency transformer T and a secondary circuit of the high-frequency transformer T; the secondary circuit of the main power circuit CLCL resonant converter of the high-frequency transformer T includes a secondary winding N of the transformer S and a load R o ; the primary circuit of the main power circuit CLCL resonant converter of the high-frequency transformer T includes a primary winding N of the transformer P , an H-bridge circuit, a resonant network, and a DC voltage source V in ; the H-bridge circuit includes a first power transistor S1, a second power transistor S2, a third power transistor S3, and a fourth power transistor S4 with junction capacitors and anti-parallel diodes; the resonant network includes a series resonant capacitor C s , a series resonant inductor L s , a parallel resonant capacitor C p , and a parallel resonant inductor L p ; the partial power circuit Buck converter includes a buck inductor L, a DC-side capacitor C in , a fifth power transistor S5, and a sixth power transistor S6.
[0006] Furthermore, the resonant network forms a loop by connecting the midpoint of the first bridge arm and the midpoint of the second bridge arm; the same-named end of the primary winding N P is connected to the positive pole of the parallel resonant capacitor C p , the upper end of the parallel resonant inductor L p , and the right side of the upper end of the series resonant inductor L s ; the different-named end of the primary winding N P is connected to the negative pole of the parallel resonant capacitor C p , the lower end of the parallel resonant inductor L p , the source electrode of the third power transistor S3, and the drain electrode of the fourth power transistor S4; the drain electrode of the first power transistor S1 is connected to the DC-side capacitor C in , the drain electrode of the third power transistor S3 is connected to the positive pole of the DC voltage source V in , and the source electrodes of the second power transistor S2 and the fourth power transistor S4 are connected to the negative pole of the DC voltage source V in ; the same-named end of the winding N S of the secondary circuit of the main power circuit CLCL resonant converter of the high-frequency transformer T is connected to the upper end of the load R o , and the different-named end of the secondary winding N S is connected to the lower end of the load R o .
[0007] Furthermore, the partial power circuit Buck converter and the CLCL resonant converter share a DC voltage source V in, the output side of the Buck converter is connected to the first bridge arm of the H-bridge circuit, which is composed of the first power transistor S1 and the second power transistor S2; the partial power circuit Buck converter includes a buck inductor L and a DC-side capacitor C in , the fifth power transistor S5 with an antiparallel diode, and the sixth power transistor S6 being a diode; the left end of the buck inductor L is connected to the source of the fifth power transistor S5 and the cathode of the sixth power transistor S6, and the right end of the buck inductor L is connected to the positive electrode of the DC-side capacitor C in and the drain of the first power transistor S1, and the negative electrode of the output capacitor C in is connected to the sources of the second power transistor S2 and the fourth power transistor S4, the anode of the sixth power transistor S6, and the negative electrode of the DC voltage source V in .
[0008] Further, the switching frequency f of the main power circuit CLCL resonant converter s operates at the resonant frequency with a fixed duty cycle; the duty cycles of the first power transistor S1 and the fourth power transistor S4 in the primary H-bridge circuit are 0.5 and they are driven in the same way, the duty cycles of the second power transistor S2 and the third power transistor S3 are 0.5 and they are driven in the same way, the first power transistor S1 and the second power transistor S2 are complementary-conducted, and the third power transistor S3 and the fourth power transistor S4 are complementary-conducted; the switching frequency f of the main power circuit CLCL resonant converter s is:
[0009]
[0010] where, L p is the parallel resonant inductor, C p is the parallel resonant capacitor, C s is the series resonant capacitor, and L s is the series resonant inductor.
[0011] Further, the partial power circuit Buck converter adopts a modulation strategy with a variable duty cycle. Denote the voltage value of the DC voltage source V in as U in , then the output voltage U A of the partial power circuit Buck converter is:
[0012] U A = DU in
[0013] where, D is the duty cycle of the partial power circuit Buck converter, and U in is the voltage value of the DC voltage source V in .
[0014] Further, when driving the first power transistor S1 and the fourth power transistor S4 in the primary H-bridge circuit during the positive half-cycle, the input voltage U of the resonant network ABThe output voltage U of the Buck converter in the partial power circuit A , when driving the second power transistor S2 and the third power transistor S3 in the negative half cycle, the input voltage U of the resonant network AB is the voltage value U in of the DC voltage source V in and its opposite number can be summarized as:
[0015]
[0016] wherein, V in is the DC voltage source, D is the duty cycle of the Buck converter in the partial power circuit, and T s is the switching period of the main power circuit.
[0017] Furthermore, the gain |G| of the resonant network can be obtained by the fundamental wave analysis method:
[0018]
[0019] wherein is the equivalent load on the output side of the resonant network, and are the impedances of the parallel resonant branch and the series resonant branch respectively, and are the quality factors of the parallel resonant network and the series resonant network respectively, and are the parallel resonant angular velocity and the series resonant angular velocity respectively, and are the ratios of the angular velocity ω o of the resonant network to the resonant angular frequency ω p of the parallel resonant network and the angular frequency ω s of the series resonant network respectively.
[0020] Compared with the prior art by adopting the above technical solutions, the present invention has the following beneficial effects:
[0021] (1). An efficient combined resonant DC-AC converter for a high-frequency AC power distribution system proposed by the present invention has a relatively simple structure, realizes the soft-switching operation of the converter power transistors, reduces the switching loss of the converter, and is beneficial to the high-frequency operation of the converter and the reduction of the device volume.
[0022] (2). An efficient combined resonant DC-AC converter for a high-frequency AC power distribution system proposed by the present invention adopts a CLCL resonant converter for the main power circuit and a Buck converter for the partial power circuit, and can realize efficient energy flow.
[0023] (3) The efficient combined resonant DC-AC converter proposed by the present invention for a high-frequency AC power distribution system uses different input voltages of two bridge arms to achieve partial power processing, which is beneficial to reducing the total number of components and costs and realizing two connection architectures.
[0024] (4) The efficient combined resonant DC-AC converter proposed by the present invention for a high-frequency AC power distribution system has the main power circuit CLCL resonant converter operating at the resonant point, and the output voltage has very low total harmonic distortion. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.
[0026] Attached Figure 1 is the circuit drawing of the efficient combined resonant DC-AC converter for a high-frequency AC power distribution system of the present invention;
[0027] Attached Figure 2 is the main waveform schematic drawing of the implementation circuit of the efficient combined resonant DC-AC converter for a high-frequency AC power distribution system of the present invention;
[0028] Attached Figure 3 is the schematic drawing of the switching mode [t0~t1] of the embodiment of the efficient combined resonant DC-AC converter for a high-frequency AC power distribution system of the present invention;
[0029] Attached Figure 4 is the schematic drawing of the switching mode [t1~t2] of the embodiment of the efficient combined resonant DC-AC converter for a high-frequency AC power distribution system of the present invention;
[0030] Attached Figure 5 is the schematic drawing of the switching mode [t2~t3] of the embodiment of the efficient combined resonant DC-AC converter for a high-frequency AC power distribution system of the present invention;
[0031] Attached Figure 6 is the schematic drawing of the switching mode [t3~t4] of the embodiment of the efficient combined resonant DC-AC converter for a high-frequency AC power distribution system of the present invention;
[0032] Attached Figure 7 is the simulation waveform diagram of the power transistors S1~S4 when the input voltage U in is 48V and the duty cycle is 0.65;
[0033] Appended Figure 8 is the input voltage U in When it is 54.6V and the duty cycle is 0.45, it is the simulation waveform diagram of power tubes S1 to S4. Specific implementation manners
[0034] Next, certain details of the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.
[0035] An efficient combined resonant DC-AC converter for a high-frequency AC power distribution system, as Figure 1 shown, the converter is composed of a main power circuit CLCL resonant converter and a partial power circuit Buck converter; wherein, the main power circuit CLCL resonant converter includes a primary circuit of a high-frequency transformer T and a secondary circuit of the high-frequency transformer T; the secondary circuit of the high-frequency transformer T of the main power circuit CLCL resonant converter includes a secondary winding N of the transformer S , load R o ; the primary circuit of the high-frequency transformer T of the main power circuit CLCL resonant converter includes a primary winding N of the transformer P , H-bridge circuit, resonant network, DC voltage source V in ; the H-bridge circuit includes a first power tube S1, a second power tube S2, a third power tube S3, and a fourth power tube S4 with junction capacitors and anti-parallel diodes; the resonant network includes a series resonant capacitor C s , series resonant inductor L s , parallel resonant capacitor C p , parallel resonant inductor L p ; the partial power circuit Buck converter includes a buck inductor L, a DC side capacitor C in , a fifth power tube S5, and a sixth power tube S6.
[0036] Furthermore, the resonant network forms a loop by connecting the midpoint of the first bridge arm and the midpoint of the second bridge arm; the same-name end of the primary winding N P is connected to the positive pole of the parallel resonant capacitor C p , the upper end of the parallel resonant inductor L p and the right side of the series resonant inductor L s , the different-name end of the primary winding N P is connected to the negative pole of the parallel resonant capacitor C p , the lower end of the parallel resonant inductor L pThe lower end, the source of the third power transistor S3, and the drain of the fourth power transistor S4; the drain of the first power transistor S1 is connected to the DC-side capacitor C in , the drain of the third power transistor S3 is connected to the positive pole of the DC voltage source V in , the sources of the second power transistor S2 and the fourth power transistor S4 are connected to the negative pole of the DC voltage source V in ; the winding N S of the secondary circuit of the high-frequency transformer of the main power circuit CLCL resonant converter is connected to the load R o at the upper end, and the end with the opposite name of the secondary winding N S is connected to the load R o at the lower end.
[0037] Furthermore, the partial power circuit Buck converter and the CLCL resonant converter share a DC voltage source V in , the output side of the Buck converter is connected to the first bridge arm of the H-bridge circuit, which is composed of the first power transistor S1 and the second power transistor S2; the partial power circuit Buck converter includes a buck inductor L, a DC-side capacitor C in , a fifth power transistor S5 with an anti-parallel diode, and a sixth power transistor S6 with a diode; the left end of the buck inductor L is connected to the source of the fifth power transistor S5 and the cathode of the sixth power transistor S6, and the right end of the buck inductor L is connected to the positive pole of the DC-side capacitor C in and the drain of the first power transistor S1, and the negative pole of the output capacitor C in is connected to the sources of the second power transistor S2 and the fourth power transistor S4, the anode of the sixth power transistor S6, and the negative pole of the DC voltage source V in .
[0038] Furthermore, the switching frequency f s of the main power circuit CLCL resonant converter operates at the resonant frequency, and the duty cycle is fixed; the duty cycles of the first power transistor S1 and the fourth power transistor S4 in the primary H-bridge circuit are 0.5 and they are driven in the same way, the duty cycles of the second power transistor S2 and the third power transistor S3 are 0.5 and they are driven in the same way, the first power transistor S1 and the second power transistor S2 are complementary-conducted, and the third power transistor S3 and the fourth power transistor S4 are complementary-conducted; the switching frequency f s of the main power circuit CLCL resonant converter is:
[0039]
[0040] wherein, L p is the parallel resonant inductor, C p is the parallel resonant capacitor, C s is the series resonant capacitor, and L s is the series resonant inductor.
[0041] Furthermore, the partial power circuit Buck converter adopts a modulation strategy with variable duty cycle. Denote the voltage value of the DC voltage source V in as U in . Then the output voltage U A of the partial power circuit Buck converter is:
[0042] U A = DU in
[0043] where D is the duty cycle of the partial power circuit Buck converter, and U in is the voltage value of the DC voltage source V in .
[0044] Furthermore, when driving the first power transistor S1 and the fourth power transistor S4 of the primary H-bridge circuit in the positive half-cycle, the input voltage U AB of the resonant network is the output voltage U A of the partial power circuit Buck converter. When driving the second power transistor S2 and the third power transistor S3 in the negative half-cycle, the input voltage U AB of the resonant network is the opposite of the voltage value U in of the DC voltage source V in . It can be summarized as:
[0045]
[0046] where V in is the DC voltage source, D is the duty cycle of the partial power circuit Buck converter, and T s is the switching period of the main power circuit.
[0047] Furthermore, the resonant network gain |G| can be obtained through the fundamental wave analysis method:
[0048]
[0049] where is the equivalent load on the output side of the resonant network, and are the impedances of the parallel resonant branch and the series resonant branch respectively, and are the quality factors of the parallel resonant network and the series resonant network respectively, and are the parallel resonant angular velocities and the series resonant angular velocities respectively, and are the ratios of the resonant network angular velocity ω o to the parallel resonant network resonant angular frequency ω p and the series resonant network angular frequency ω s respectively.
[0050] Combined with Figures 2 to 8 A detailed discussion is carried out on the specific working principle of the high - efficiency combined resonant DC - AC converter for high - frequency AC power distribution systems described in the present invention. It is known from Figure 2 that the converter can be divided into four modes within one cycle, namely [t0 - t1], [t1 - t2], [t2 - t3], and [t3 - t4];
[0051] 1. Mode 1 [t0 - t1] The circuit topology is as shown in Figure 3 shown:
[0052] At time t0, turn off power transistors S2 and S3. The primary current of the high - frequency transformer flows through the junction capacitance C of power transistor S2 oss2 , the junction capacitance C of power transistor S4 oss4 , the primary winding N P , the junction capacitance C of power transistor S1 oss1 , the junction capacitance C of power transistor S3 oss3 , the series - resonant capacitance C s , the series - resonant inductor L s , the parallel - resonant capacitance C p , the parallel - resonant inductor L p to form a resonant cavity, step - down inductor L, power transistors S5 and S6, output capacitance C in , the secondary current of the high - frequency transformer flows through the secondary winding N S , load R o ; In this stage, the energy of the resonant cavity discharges the voltages across the parallel capacitances C of power transistors S1 and S4 oss1 , C oss4 from DU in and U in to zero respectively, and charges the voltages across the parallel capacitances C of power transistors S2 and S3 oss2 , C oss3 from zero to DU in and U in respectively; During this process, through the charging and discharging of the junction capacitances of power transistors by the energy of the resonant cavity, zero - voltage switching (ZVS) can be achieved when the power transistors conduct subsequently. For example, when power transistors S1 and S4 conduct at time t1, since the voltages across their junction capacitances C oss1 , C oss4 have been discharged to zero, turning on power transistors S1 and S4 at this time will not cause switching losses due to non - zero voltages, effectively reducing the losses of the converter.
[0053] 2. Mode 2 [t1 - t2] The circuit topology is as shown in Figure 4 shown:
[0054] At time t1, power transistors S1 and S4 are turned on simultaneously. Due to the effect of junction capacitors C oss1 and C oss4 , power transistors S1 and S4 are at zero voltage. The primary current of the high-frequency transformer flows through the junction capacitor C oss1 of power transistor S1, the junction capacitor C oss4 of power transistor S4, the primary winding N P , the series resonant capacitor C s , the series resonant inductor L s , the parallel resonant capacitor C p , the parallel resonant inductor L p to form a resonant cavity, step-down inductor L, power transistors S5 and S6, output capacitor C in , and the secondary current of the high-frequency transformer flows through the secondary winding N S , load R o ;
[0055] At this time, the input voltage U AB of the resonant network is
[0056] U AB = DU in
[0057] where D is the duty cycle of the Buck converter in the partial power circuit, and U in is the voltage value of the DC voltage source V in . In this mode, power transistors S1 and S4 maintain the zero-voltage conduction state, ensuring the continuous realization of soft switching and further reducing the switching loss.
[0058] 3. Mode 3 [t2 - t3] The circuit topology is as shown in Figure 5 :
[0059] At time t2, turn off power transistors S1 and S4. The primary current of the high-frequency transformer flows through the junction capacitor C oss2 of power transistor S2, the junction capacitor C oss4 of power transistor S4, the primary winding N P , the junction capacitor C oss1 of power transistor S1, the junction capacitor C oss3 of power transistor S3, the series resonant capacitor C s , the series resonant inductor L s , the parallel resonant capacitor C p , the parallel resonant inductor L p to form a resonant cavity, step-down inductor L, power transistors S5 and S6, output capacitor C in , the secondary current of the high-frequency transformer flows through the secondary winding N S , load R o ; During this stage, the energy of the resonant cavity charges the parallel capacitors C of power transistors S2 and S3oss2 , C oss3 The voltages at both ends of the in and U in are discharged to zero respectively, and the parallel capacitors C oss1 , C oss4 at both ends of the power transistors S1 and S4 are charged from zero to in and U in respectively;
[0060] 4. The circuit topology in Mode 4 [t3 - t4] is as Figure 6 shown:
[0061] At time t3, the power transistors S2 and S3 are turned on together. Due to the effect of the junction capacitors C oss2 , C oss3 , the power transistors S2 and S3 are at zero voltage. The primary current of the high - frequency transformer flows through the junction capacitor C oss2 of the power transistor S2, the junction capacitor C oss3 of the power transistor S3, the primary winding N P , the series - resonant capacitor C s , the series - resonant inductor L s , the parallel - resonant capacitor C p , the parallel - resonant inductor L p to form a resonant cavity, and the secondary current of the high - frequency transformer flows through the secondary winding N S and the load R o ;
[0062] At this time, the input voltage U AB of the resonant network is
[0063] U AB =-U in
[0064] where U in is the voltage value of the DC voltage source V in . In this mode, the power transistors S2 and S3 are turned on under zero - voltage conditions, which continues to ensure the effective implementation of the soft - switching technology and reduces the energy loss during the switching process.
[0065] In this embodiment, Attachment Figure 7 and Attachment Figure 8 are the simulation waveform diagrams of the first power transistor S1, the second power transistor S2, the third power transistor S3, and the fourth power transistor S4 of an efficient combined resonant DC - AC converter for a high - frequency AC power distribution system according to the present invention. The embodiment of the zero - voltage switching (ZVS) technology in Attachment Figure 7 and Attachment Figure 8 has been marked in the figure. Among them, the input voltage U Figure 7 in Attachment in is 48V and the duty cycle is 0.65; AttachmentFigure 8 Input voltage U in is 54.6V and the duty cycle is 0.45. The specific simulation parameters are shown in Table 1.
[0066] Table 1 Simulation parameters under two working conditions
[0067] <![CDATA[U in > D Turn ratio <![CDATA[f CLCL > <![CDATA[f Buck > <![CDATA[C p > <![CDATA[L p > <![CDATA[C s > <![CDATA[L s > <![CDATA[U o amplitude]]> Operating condition 1 48V 0.65 2 150 kHz 100 kHz 101 nF 11 μH 21.3 nF 52 μH 100V Operating condition 2 54.6V 0.45 2 150 kHz 100 kHz 101 nF 11 μH 21.3 nF 52 μH 100V
[0068] Among them, f LCLC is the frequency of the main power circuit CLCL resonant converter, and f Buck is the frequency of the partial power circuit Buck converter.
[0069] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. An efficient combined resonant DC-AC converter for a high-frequency AC power distribution system, characterized in that The converter is composed of a main power circuit CLCL resonant converter and a partial power circuit Buck converter; among them, the main power circuit CLCL resonant converter includes a primary circuit of high-frequency transformer T and a secondary circuit of high-frequency transformer T; the secondary circuit of the main power circuit CLCL resonant converter of high-frequency transformer T includes a secondary winding N of the transformer S , load R o ; the primary circuit of the main power circuit CLCL resonant converter of high-frequency transformer T includes a primary winding N of the transformer P , H-bridge circuit, resonant network, DC voltage source V in ; the H-bridge circuit includes a first power transistor S1, a second power transistor S2, a third power transistor S3, and a fourth power transistor S4 with junction capacitors and anti-parallel diodes; the resonant network includes a series resonant capacitor C s , series resonant inductor L s , parallel resonant capacitor C p , parallel resonant inductor L p ; the partial power circuit Buck converter includes a buck inductor L, a DC-side capacitor C in , a fifth power transistor S5, and a sixth power transistor S6; the converter utilizes the cooperation between the resonant network in the circuit and the junction capacitors of the power transistors to achieve zero-voltage switching (ZVS) and reduce switching losses.
2. The high-efficiency combined resonant DC-AC converter for a high-frequency AC power distribution system according to claim 1, wherein The resonant network forms a loop by connecting the midpoints of the first and second bridge arms; the primary winding N P 's same-name terminal is connected to the positive electrode of the parallel resonant capacitor C p , the upper end of the parallel resonant inductor L p in series with the upper end of the series resonant inductor L s on the right side. The opposite-name terminal of the primary winding N P is connected to the negative electrode of the parallel resonant capacitor C p , the lower end of the parallel resonant inductor L p , the source electrode of the third power transistor S3, and the drain electrode of the fourth power transistor S4; the drain electrode of the first power transistor S1 is connected to the DC-side capacitor C in , the drain electrode of the third power transistor S3 is connected to the positive electrode of the DC voltage source V in , the source electrodes of the second power transistor S2 and the fourth power transistor S4 are connected to the negative electrode of the DC voltage source V in ; the same-name terminal of the winding N S of the secondary circuit of the main power circuit CLCL resonant converter high-frequency transformer is connected to the upper end of the load R o , and the opposite-name terminal of the secondary winding N S is connected to the lower end of the load R o .
3. An efficient combined resonant DC-AC converter for a high-frequency AC power distribution system according to claim 1, characterized in that, The partial power circuit Buck converter and the CLCL resonant converter share a DC voltage source V in , and the output side of the Buck converter is connected to the first arm of the H-bridge circuit, which is composed of the first power transistor S1 and the second power transistor S2; the partial power circuit Buck converter includes a buck inductor L and a DC-side capacitor C in , the fifth power transistor S5 with an anti-parallel diode, and the sixth power transistor S6 as a diode; the left end of the buck inductor L is connected to the source of the fifth power transistor S5 and the cathode of the sixth power transistor S6, and the right end of the buck inductor L is connected to the positive electrode of the DC-side capacitor C in and the drain of the first power transistor S1, and the negative electrode of the output capacitor C in is connected to the sources of the second power transistor S2 and the fourth power transistor S4, the anode of the sixth power transistor S6, and the negative electrode of the DC voltage source V in .
4. An efficient combined resonant DC-AC converter for a high-frequency AC power distribution system according to claim 1, characterized in that, The switching frequency f of the main power circuit CLCL resonant converter s operates at the resonant frequency with a fixed duty cycle; the duty cycles of the first power transistor S1 and the fourth power transistor S4 in the primary H-bridge circuit are 0.5 and they are driven by the same signal, the duty cycles of the second power transistor S2 and the third power transistor S3 are 0.5 and they are driven by the same signal, the first power transistor S1 and the second power transistor S2 conduct complementarily, and the third power transistor S3 and the fourth power transistor S4 conduct complementarily; the switching frequency f of the main power circuit CLCL resonant converter s is as follows: Among them, L p is the parallel resonance inductor, C p is the parallel resonance capacitor, C s is the series resonance capacitor, L s is the series resonance inductor; the switching frequency and driving method are adapted to ZVS, ensuring that the power transistor realizes zero-voltage conduction and turn-off at specific moments, and further reducing the switching loss.
5. The high-efficiency combined resonant DC-AC converter for a high-frequency AC power distribution system according to claim 1, wherein The partial power circuit Buck converter adopts a modulation strategy with variable duty cycle. Denote the voltage value of the DC voltage source V in as U in . Then the output voltage U A of the partial power circuit Buck converter is: U A = DU in Among them, D is the duty cycle of the Buck converter in the partial power circuit, and U in is the voltage value of the DC voltage source V in . By adjusting the duty cycle, the output voltage of the Buck converter is changed, and then the input voltage of the resonant network is adjusted, creating favorable conditions for realizing ZVS.
6. The high-efficiency combined resonant DC-AC converter for a high-frequency AC power distribution system according to claim 1, wherein When driving the first power transistor S1 and the fourth power transistor S4 of the primary H-bridge circuit in the positive half-cycle, the input voltage U of the resonant network AB is the output voltage U of the Buck converter of the partial power circuit A . When driving the second power transistor S2 and the third power transistor S3 in the negative half-cycle, the input voltage U of the resonant network AB is the opposite of the voltage value U in of the DC voltage source V in . It can be summarized as: Among them, V in is a DC voltage source, D is the duty cycle of the Buck converter in the partial power circuit, and T s is the switching period of the main power circuit.
7. An efficient combined resonant DC-AC converter for a high-frequency AC power distribution system according to claim 1, characterized in that, The resonant network gain |G| can be obtained by the fundamental wave analysis method: wherein is the equivalent load on the output side of the resonant network, and are the impedance of the parallel resonant branch and the impedance of the series resonant branch respectively, and are the quality factor of the parallel resonant network and the quality factor of the series resonant network respectively, and are the parallel resonant angular velocity and the series resonant angular velocity respectively, and are the angular velocity ω of the resonant network o and the resonant angular frequency ω p of the parallel resonant network and the angular frequency ω s of the series resonant network respectively.