CN113541486B

CN113541486B - Interleaved diode capacitor network high-gain ZVT (zero voltage zero volt) direct current converter and auxiliary circuit

Info

Publication number: CN113541486B
Application number: CN202110697676.0A
Authority: CN
Inventors: 张岩; 李新颖; 程钰杰
Original assignee: Nanjing Junyao Technology Co ltd; Xian Jiaotong University
Current assignee: Nanjing Junyao Technology Co ltd; Xian Jiaotong University
Priority date: 2021-06-23
Filing date: 2021-06-23
Publication date: 2023-03-28
Anticipated expiration: 2041-06-23
Also published as: CN113541486A

Abstract

The invention discloses a high-gain ZVT (zero voltage variation) direct-current converter and an auxiliary circuit of an interleaved diode capacitor network, wherein the ZVT auxiliary circuit comprises a first auxiliary circuit, a second auxiliary circuit and a resonant inductor, the first auxiliary circuit comprises a first auxiliary switching tube and a first auxiliary diode, the second auxiliary circuit comprises a second auxiliary switching tube and a second auxiliary diode, the first auxiliary circuit and the second auxiliary circuit share one resonant inductor and are used for realizing ZVS (zero voltage switching) switching-on and switching-off of the first controllable switching tube and the second controllable switching tube in the direct-current converter, the first auxiliary switching tube and the second auxiliary switching tube realize ZCS switching-on, and all diodes realize ZCS switching-off. The high-efficiency high-power-density switch has the characteristics of expandable high-voltage gain, low input current ripple, low voltage stress, wide-range soft switching and simple parameter design while realizing high efficiency and high power density.

Description

Interleaved diode capacitor network high-gain ZVT (zero voltage zero volt) direct current converter and auxiliary circuit

Technical Field

The invention belongs to the field of converters, and particularly relates to a high-gain ZVT (zero voltage zero volt) direct current converter of an interleaved diode capacitor network and an auxiliary circuit.

Background

Due to exhaustion of fossil fuels and environmental pollution, new energy sources are increasingly attracting attention. Photovoltaic and fuel cell technologies in new energy are ideal ways for future household new energy power generation due to wide application region, short construction period, cleanness and no pollution. However, both of the two energy sources have the obvious characteristics of low output voltage and wide fluctuation range, so that a front-level high-gain direct-current converter is required to perform boost conversion and ensure the voltage stability of a direct-current bus, and the direct-current bus is further connected to a power grid through a grid-connected inverter.

The main technical challenge currently faced is how to handle incoming large currents and outgoing high voltages with a minimum of power devices and passive components. Input-parallel output series LLC or dual active bridge converters are the preferred solutions to achieve high gain and high efficiency. However, the coordinated control of voltage and current sharing among modules significantly increases the cost and complexity of the system, making it more suitable for high-power applications. In applications where forced isolation is not required, non-isolated DC-DC converters have the potential advantage of achieving higher efficiency and power density. The two-phase interleaved boost diode capacitor (TIBD) converter consists of two parts, namely a two-phase interleaved boost input and a diode capacitor boost unit (VMC), and has similar excellent performance. The staggered boost input part enables input current to be continuous and ripples to be reduced, the current stress of the controllable switch tube is reduced, the diode capacitor boosting unit achieves high gain and simultaneously reduces the voltage stress of all semiconductor devices, and therefore low-on-state resistance power devices can be used for reducing conduction loss. In addition, fewer magnetic elements may enable high power density integration. However, for the TIBD converter, as the number of semiconductor devices increases, hard switching causes higher power loss and severe electromagnetic interference, and soft switching is particularly necessary. Unlike an isolated DC-DC converter which naturally implements soft switching using transformer leakage inductance, all the inductor current and capacitor voltage in the TIBD converter are constant DC components, and there is no voltage current zero crossing, so soft switching is difficult to implement. Existing soft switching solutions for TIBD converters are more limited to a specific TIBD topology, and there is a lack of systematic soft switching design solutions for this type of topology with superior performance.

Zero voltage switching is more suitable for high frequency power converters employing MOSFETs or GaN than zero current switching. The simplest and straightforward method is critical conduction mode, where a small boost inductor is designed to achieve current return to zero at the end of a switching cycle. However, the high peak-to-average current ratio and input ripple limit its application in very low power conversion. For a quasi-resonant TIBD converter, a small inductor is inserted into the switched capacitor network and then the large capacitor is replaced with a small resonant capacitor. But the energy transferred to the load by the resonant capacitor is limited at this time, and the voltage gain is low. Unlike the ZVS approach, the ZVT topology removes the auxiliary leg from the main circuit and only acts when the main switch switches. Therefore, the additional voltage stress and power loss are small. Although there are ZVT methods for TIBD converters, each method is only suitable for a specific topology, and the ZVS range is limited and varies with different resonance parameters.

The staggered non-isolated diode capacitor network high-gain direct current converter adopts a double boost circuit staggered working mode, which is beneficial to reducing input current ripples and prolonging the service lives of a fuel cell and a photovoltaic panel. The high gain characteristic of the diode capacitor network enables the voltage stress of the semiconductor device to be greatly reduced, and the low-voltage switch tube can improve the efficiency of the circuit while reducing the cost and conduction loss of the circuit. The reduction of the number of the magnetic pieces and the switching tubes is beneficial to reducing the circuit volume and the driving cost, and has the advantage of high power density. However, the hard switching mode of this type of converter limits further improvement of the switching frequency of this type of converter, and the power density is limited, so that the goals of miniaturization and light weight cannot be achieved.

Disclosure of Invention

The invention aims to provide a high-gain ZVT (zero volt-ampere) direct current converter and an auxiliary circuit of an interleaved diode capacitor network, which have the characteristics of expandable high voltage gain, low input current ripple, low voltage stress, wide-range soft switching and simple parameter design while realizing high efficiency and high power density.

The technical solution for realizing the purpose of the invention is as follows:

a high-gain direct current converter ZVT auxiliary circuit of an interleaved diode capacitor network comprises a first auxiliary circuit, a second auxiliary circuit and a resonant inductor, wherein the first auxiliary circuit comprises a first auxiliary switching tube and a first auxiliary diode, the second auxiliary circuit comprises a second auxiliary switching tube and a second auxiliary diode, the first auxiliary circuit and the second auxiliary circuit share one resonant inductor and are used for realizing ZVS (zero voltage switching) switching-on and switching-off of a first controllable switching tube and a second controllable switching tube in a direct current converter, the first auxiliary switching tube and the second auxiliary switching tube realize ZCS switching-on, and all diodes realize ZCS switching-off.

Further, the drain of the first auxiliary switch tube is connected with one end of the resonant inductor and is also connected with the anode of the first auxiliary diode, the drain of the second auxiliary switch tube is connected with the other end of the resonant inductor and is also connected with the anode of the second auxiliary diode, the source of the first auxiliary switch tube is connected with the drain of one of the controllable switch tubes of the converter, the source of the second auxiliary switch tube is connected with the drain of the other controllable switch tube, the cathode of the first auxiliary diode is connected with one end of a certain capacitor in the diode capacitor boosting unit in the converter, and the cathode of the second auxiliary diode is connected with one end of a certain capacitor in the diode capacitor boosting unit in the converter.

Preferably, the source of the first auxiliary switching tube is connected to the source of the second auxiliary switching tube, the drain of the first auxiliary switching tube is connected to one end of the resonant inductor, and is also connected to the anode of the first auxiliary diode and the cathode of the second auxiliary diode, the other end of the resonant inductor is connected to the drain of one of the controllable switching tubes of the converter, the drain of the second auxiliary switching tube is connected to the drain of the other controllable switching tube, the cathode of the first auxiliary diode is connected to one end of the first capacitor in the diode capacitor boosting unit in the converter, and the anode of the second auxiliary diode is connected to one end of the second capacitor in the diode capacitor boosting unit.

A high-gain ZVT direct current converter based on a staggered diode capacitor network of a ZVT auxiliary circuit comprises two staggered input ends, a diode capacitor boosting unit and an output end load, wherein the two staggered input ends comprise an input end power supply, a first staggered inductor, a second staggered inductor, a first controllable switch tube, a second controllable switch tube, a first resonant capacitor and a second resonant capacitor, the positive pole of the input end power supply is simultaneously connected with one ends of the first staggered inductor and the second staggered inductor, the other end of the first staggered inductor is connected with the drain electrode of the first controllable switch tube, and the source electrode of the first controllable switch tube is connected with the negative pole of the input end power supply; the other end of the second interleaved inductor is connected with the drain electrode of a second controllable switching tube, the source electrode of the second controllable switching tube is connected with the negative electrode of the input end power supply, the capacitor is connected with the switching tube in parallel, and the capacitor is connected with the switching tube in parallel; a ZVT auxiliary circuit is added between the two-phase staggered input end and the diode capacitor boosting unit to realize soft switching of the first controllable switching tube and the second controllable switching tube, and the ZVT auxiliary circuit comprises a first auxiliary switching tube, a second auxiliary switching tube, a first auxiliary diode, a second auxiliary diode and a resonant inductor.

Furthermore, the diode capacitor boosting unit is a Bi-fold Dickson boosting unit and comprises 6 capacitors and 6 diodes, the drain electrode of the first controllable switch tube is connected with one ends of the first capacitor, the third capacitor, the fourth capacitor and the sixth capacitor and one end of a resonance inductor, the other end of the resonance inductor is connected with the drain electrode of the first auxiliary switch tube, the anode of the first auxiliary diode and the cathode of the second auxiliary diode, the drain electrode of the second controllable switch tube is connected with the anode of the first diode, one end of the second capacitor, one end of the fifth capacitor and the drain electrode of the second auxiliary switch tube, and the source electrode of the second auxiliary switch tube is connected with the source electrode of the first auxiliary switch tube; the other end of the first capacitor is connected with the cathode of the first diode, the cathode of the first auxiliary diode and the anode of the second diode, the other end of the second capacitor is connected with the cathode of the second diode and the anode of the third diode, the other end of the third capacitor is connected with the cathode of the third diode and one end of a load, the other end of the fourth capacitor is connected with the anode of the fourth diode, the anode of the second auxiliary diode and the cathode of the fifth diode, the other end of the fifth capacitor is connected with the anode of the fifth diode and the cathode of the sixth diode, the other end of the sixth capacitor is connected with the anode of the sixth diode and the other end of the load, and the cathode of the fourth diode is connected with the cathode of the input end power supply.

A control method based on the interleaved diode capacitor network high-gain ZVT direct current converter is characterized in that a control cycle of the control method is divided into a first half cycle and a second half cycle, and the first half cycle and the second half cycle are symmetrical, and the method comprises the following steps:

t ₀ ～t ₁ in the stage, the first controllable switch tube is turned off, the first resonant capacitor is connected in parallel to cause zero voltage to be turned off, the voltage of the first resonant capacitor rapidly rises to the voltage at two ends of the fourth capacitor, the second diode, the fourth diode and the sixth diode are turned on, and the first diode, the third diode and the fifth diode are turned off in a reverse bias mode; the first auxiliary switch tube and the second auxiliary switch tube are in an off state, and the second controllable switch tube is kept on;

t ₁ ～t ₂ stage, the first auxiliary switch tube is turned on, and other semiconductor devices are kept at the last stageThe state of (2); the voltage of the resonant inductor is equal to the voltage across the fourth capacitor, and the current of the resonant inductor starts from zero with a slope V _C4 /L _r The voltage rises linearly, and the first auxiliary switch tube is switched on for zero current;

t ₂ ～t ₃ step two, the resonant inductor current rises to the first inductor current, and the second diode, the fourth diode and the sixth diode are turned off at zero current; the resonance inductor starts to resonate with the first resonance capacitor;

t ₃ ～t ₄ in the stage, the voltage at two ends of the first resonant capacitor is reduced to zero, the resonant inductive current is larger than the first inductive current, the current starts to reversely flow through the switch tube, and all diodes are reversely biased and turned off;

t ₄ ～t ₅ the first auxiliary switching tube is turned off, the first auxiliary diode is turned on, and other semiconductor devices keep the state of the previous stage;

t ₅ ～t ₆ step two, the resonant inductor current is reduced to zero, and the first auxiliary diode realizes zero current turn-off; the input end power supply linearly magnetizes the first inductor, and the second inductor is linearly magnetized by the input end power supply in the first half of the switching period;

t ₆ and at the moment, the second controllable switch tube is turned off, the first half cycle is finished, the second half cycle is symmetrically executed, and the next cycle is repeated after the second half cycle is finished.

Compared with the prior art, the invention has the following remarkable effects:

1) The auxiliary circuit comprises a first auxiliary switching tube, a second auxiliary switching tube, a first auxiliary diode, a second auxiliary diode and a resonant inductor, wherein the auxiliary circuit is added into a converter circuit, the voltage gain is adjusted by controlling the duty ratio of a controllable switching tube in topology, ZVS (zero voltage switching) switching-on of the two controllable switching tubes, ZCS (zero voltage switching) switching-on of the auxiliary switching tube and ZCS (zero voltage switching) switching-off of all diodes are realized under the condition that the voltage stress of a main circuit semiconductor device is not changed, so that the efficiency and the power density of the converter are further improved, and the problem of electromagnetic interference is effectively inhibited;

2) The modularized diode capacitor boosting unit has simple working principle, parameter design and controller design, high voltage gain and is beneficial to engineering application;

3) The converter provided by the invention has the advantages that the input current ripple is remarkably reduced through the ZVT auxiliary circuit, and the service lives of a photovoltaic panel and a fuel cell are prolonged;

4) All main circuit semiconductor devices of the invention keep low voltage when the voltage stress is unchanged, and auxiliary circuit semiconductor devices have low voltage stress, so that low-voltage devices can be used for reducing conduction loss;

5) The ZVT auxiliary circuit design is suitable for TIBD converters, realizes soft switching of all semiconductor devices, has universality, and has wide application prospect in a new energy distributed power generation system due to the zero-voltage conversion soft switching topology.

Drawings

Fig. 1 is a general topology structure diagram of a TIBD converter.

Fig. 2 is a typical topology diagram of a TIBD converter with different diode-capacitor voltage boosting units, wherein (a) is a topology diagram of the diode-capacitor voltage boosting unit being an interleaved voltage doubling unit; (b) The diode capacitance boosting unit is a topological diagram of a Cockcroft-Walton boosting unit; (c) A topological diagram of a diode capacitor boosting unit as a Dickson boosting unit; (d) A topological diagram of a diode capacitor boosting unit which is a Bi-fold Dickson boosting unit; (e) A topological diagram of a diode capacitor boosting unit which is a Bi-fold Dickson boosting unit; (f) - (i) is a topological diagram of a diode capacitance boosting unit which is a Cockcroft-Walton and Dickson derivative boosting unit.

FIG. 3 is an equivalent circuit diagram of the TIBD converter of FIG. 2 (d), wherein (a) is the first controllable switch tube S ₁ = OFF, second controllable switch tube S ₂ Equivalent circuit diagram of = ON; (b) Is a first controllable switch tube S ₁ = ON, second controllable switch tube S ₂ Equivalent circuit diagram of = OFF.

FIG. 4 is a functional block diagram of the TIBD converter of FIG. 2 (d), wherein (a) is a circuit with a first controllable switch S ₁ A boost circuit diagram of (a); (b) Is provided with a second controllable switch tube S ₂ A boost circuit diagram of (a); and (c) is a load charging circuit diagram.

Fig. 5 is a simplified diagram of a universal topology of the TIBD converter according to the three functional blocks of fig. 4.

FIG. 6 (a) shows the converter of FIG. 2 (d) including a first controllable switch S ₁ ZVT auxiliary circuit diagram of the boost circuit of (1); in the drawing (b), is S ₁ ＝OFF，S ₂ Fig. 6 (a) is an equivalent circuit diagram of the circuit when = ON, sa = OFF.

FIGS. 7 (a) - (f) show the converter of FIG. 2 (d) including S ₁ Boost circuit of S ₁ And turning off to each mode equivalent circuit diagram for realizing ZVS turning-on.

FIG. 8 shows the converter of FIG. 2 (d) including S ₁ Other ZVT auxiliary circuit diagrams of the boost circuit of (a).

FIG. 9 shows the converter of FIG. 2 (d) including S ₁ The ZVT auxiliary circuit general topology structure diagram of the boost circuit.

FIG. 10 (a) shows the converter of FIG. 2 (d) including S ₂ The optimal ZVT auxiliary circuit diagram of the boost circuit of (1); (b) The converter of fig. 2 (d) contains an optimal ZVT auxiliary circuit diagram of two boost circuits.

Fig. 11 is a simplified optimized ZVT auxiliary circuit for the converter of fig. 2 (d).

FIG. 12 (a) is a diagram of an optimal ZVT assist circuit for the converter of FIG. 2 (a) including two boost circuits; (b) The optimized ZVT auxiliary circuit diagram is simplified for the converter of fig. 2 (a).

Fig. 13 is another TIBD converter of fig. 2 with a simplified optimal ZVT auxiliary circuit.

Fig. 14 is a general topology block diagram of a TIBD converter with a simplified optimal ZVT auxiliary circuit.

Fig. 15 is a theoretical waveform diagram for constructing the ZVT converter of fig. 11.

Fig. 16 (a) to (f) are equivalent circuit diagrams of the respective operation modes of the converter modes 1 to 6 in fig. 11.

FIG. 17 shows the difference in R _L And the voltage gain ratio M and the duty ratio D under the influence.

Fig. 18 is a graph comparing the efficiency of different ZVT IDBD converters.

Fig. 19 is a comparative evaluation graph of several typical ZVT IDBD converters.

Fig. 20 is a diagram of driving signals of the controllable switch tube in the experiment.

Fig. 21 is a power loss distribution diagram of the converter of fig. 11.

FIG. 22 shows the input voltage V _in ＝25V，V _o ＝400V，R _L Graph of experimental results at 1000 Ω.

FIG. 23 shows the input voltage V _in ＝25V，V _o ＝400V，R _L Graph of experimental results at 500 Ω.

FIG. 24 shows the input voltage V _in ＝15V，V _o ＝400V，R _L Graph of experimental results at 1000 Ω.

FIG. 25 (a) shows R _L A dynamic response diagram of the input voltage stepped from 15V to 25V at 800 Ω; (b) Is a V _in Dynamic response diagram of load step from 0.4A to 0.8A when = 20V.

FIG. 26 (a) is a graph of efficiency at different loads; and (b) is a voltage gain ratio diagram under different loads.

Detailed Description

In order to make the technical solution of the present invention better understood, the technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. It is to be understood that the described examples are only a few, not all examples of the present invention, and are not intended to limit the scope of the present disclosure. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present disclosure. All other examples, which can be obtained by a person skilled in the art without making any creative effort based on the examples in the present invention, shall fall within the protection scope of the present invention.

Various schematic structural diagrams in accordance with disclosed examples of the invention are shown in the figures. The figures are not drawn to scale, wherein certain details are exaggerated and possibly omitted for clarity of presentation. The invention is described in further detail below with reference to the accompanying drawings:

a classic interleaved diode capacitor network high-gain DC converter is shown in FIG. 1, wherein two input sides of the converter are crossedThe staggered structure reduces input current ripples and current stress of the switching tube. The output side of the diode capacitor network is composed of two basic diode capacitor boosting units, namely Cockcroft-Walton and Dickson, and diode boosting structures derived from the diode capacitor boosting units. The converter has the advantages, high efficiency and high power density are achieved, the working principle, the parameter design and the control structure are simple, and the boost unit is of a modularized boost unit structure, so that the boost unit is particularly suitable for the preceding-stage direct current boost conversion occasion of new energy power generation. However, the hard switching operation mode of this type of converter limits further improvement of the switching frequency of this type of converter, and cannot achieve the goal of miniaturization and light weight. On the basis of analyzing the converter, the invention finds that the converter can be divided into three parts according to the circuit function: comprising S ₁ And L ₁ Comprises S ₂ And L ₂ The capacitor and the load form a discharge loop, as shown in fig. 4. Because the circuit works in an interleaving mode, when one of the switching tubes acts, the other switching tube is always conducted, and the two boost circuits do not influence each other. To realize the inclusion of S ₁ And L ₁ To soft-switch all semiconductor devices in the boost circuit of (1), a ZVT auxiliary circuit is added as shown in FIG. 9, according to L _r In the implementation of S ₁ The energy feedback loop after ZVS is turned on, and the auxiliary circuit structure is shown in fig. 9 (a) or fig. 9 (b). First auxiliary diode D _a One end of (1) and a resonant inductor L _r And a one-way switch tube S _a And the other end of the capacitor is connected with one capacitor in the diode capacitor boosting network. Since the auxiliary circuit is only at S ₁ Operating around the turn-on time, including S ₂ And L ₂ All semiconductors in the boost circuit of (a) are still operating in hard switching mode. Also, to implement the inclusion of S ₂ And L ₂ The soft switching of all semiconductor devices in the boost circuit of (1) adds a ZVT auxiliary circuit similar to the structure of FIG. 9. At the same time, includes S ₁ And L ₁ All semiconductor devices in the boost circuit of (1) operate in a hard switching mode. To realize twoThe soft switching of all semiconductor devices of the boost circuit is realized by adding the auxiliary circuits of the two boost circuits into the hard switching main circuit simultaneously and realizing the soft switching of all semiconductor devices of the circuit. Because the two auxiliary circuits only work near the turn-on time of the corresponding controllable switch tubes and the two controllable switch tubes work in the staggered mode, the two auxiliary circuits can share one resonant inductor, the two auxiliary circuits can be simplified into one auxiliary circuit, and the two unidirectional switch tubes can be replaced by bidirectional switch tubes. The simplified auxiliary circuit structure has two forms depending on whether the resonant inductors of the two auxiliary circuits have a common connection. The final simplified ZVT assist circuit structure is shown in fig. 14. The simplified auxiliary circuit is composed of a first auxiliary switch tube S _a And a second auxiliary switch tube S _b A first auxiliary diode D _a And a second auxiliary diode D _b Resonant inductance L _r And (4) forming. In order to realize ZVS turn-off of the controllable switching tubes, two small capacitors C are connected in parallel at two ends of the two controllable switching tubes _s1 And C _s2 . Finally, the controllable switching tube realizes ZVS on and off, the auxiliary switching tube realizes ZCS on, and all diodes realize ZCS off.

The invention is described in detail below with reference to the figures and specific examples.

Fig. 1 shows a general topology of a two-phase interleaved boost diode-capacitor (TIBD) converter, consisting of two-phase interleaved input and diode-capacitor boost units. Fig. 2 shows several typical hard-switched (HS) TIBD converters, with basic diode-capacitor voltage boosting cells (VMC) in the dashed box, with increased cell count to improve voltage gain. The topologies in fig. 2 (b) and (c) are composed of two most basic Cockcroft-Walton and Dickson diode capacitance boosting units, and diode capacitance boosting units of other topologies can be derived from the two basic boosting units. The operation principle of the TIBD converter in fig. 2 (a), (d), (e), (f) and (i) is explained in detail in the prior art. In order to better explain the design idea of the ZVT auxiliary soft switch of this topology, the basic operation principle of the hard switch topology of this topology needs to be introduced, and the converter of the Bi-fold Dickson boost unit in fig. 2 (d) is taken as an example to analyze. In order to obtain high voltage gain, the duty ratio of the two controllable switching tubes is larger than 0.5, and the phase of the two controllable switching tubes is shifted by 180 degrees, so that three circuit states exist in one switching period. When both switches are on at the same time, all diodes are reverse biased and both inductors are charged by the input voltage source. The two circuit states are shown in fig. 3 (a) and (b). The converter can be considered to consist of two interleaved boost circuits. One of the boost circuits is composed of V _in 、L ₁ 、S ₁ 、D ₂ 、D ₄ 、D ₆ 、C ₁ 、C ₂ 、C ₄ 、C ₅ 、C ₆ And (4) forming. Another boost circuit is composed of V _in 、L ₂ 、S ₂ 、D ₁ 、D ₃ 、D ₅ 、C ₁ 、C ₂ 、C ₃ 、C ₄ 、C ₅ And (4) forming. For containing S ₁ When S is a boost circuit ₁ When conducting, L ₁ Is supplied by voltage source V _in Is magnetized and is not influenced by the switch tube S ₂ The effect of the switching on or off action. When one switch tube is turned on or off, the other switch tube is always kept in a conducting state, so that the two boost circuits are not influenced by each other. When S is ₁ When disconnected, the circuit state is as shown in FIG. 3 (a), V _in And L ₁ Three diode capacitor parallel branches are charged, and the state simplifies the circuit structure as shown in fig. 4 (a). For another boost circuit, when S ₂ When the switch is turned off, the circuit state is as shown in fig. 3 (b), and the simplified circuit configuration is as shown in fig. 4 (b). Thus, the circuit in fig. 2 (d) can be considered to be composed of three functional parts as shown in fig. 4, the third part being a discharge loop composed of an output capacitor and a load. As can be seen from fig. 4 (a) and (b), the two boost circuits share part of the capacitance without the semiconductor device and the inductance overlapping. The general structure of this type of converter can therefore be further summarized in fig. 5, where the dotted line portion connected to point g indicates that the connecting branch may or may not exist according to different diode-capacitor boosting unit structures.

To realize the inclusion of S ₁ The soft switching of all semiconductor devices in the boost circuit of (a), adding a ZVT auxiliary circuit to the topology of fig. 2 (d) is shown in fig. 6 (a).Due to the first auxiliary switch tube S _a Is a one-way switch tube and is only at S ₁ Conducting near the turn-on time, so that a second controllable switch tube S is included ₂ All semiconductor devices in the boost circuit of (1) are still operating in a hard switching state. Wherein the dotted line is S ₁ L after ZVS switching on _r Transferring energy to a first capacitor C ₁ Of the substrate. In order to illustrate the working principle of the auxiliary circuit, a first controllable switch tube S ₁ ＝OFF，S ₂ = ON and first auxiliary switching tube S _a The equivalent circuit when = OFF is given as shown in fig. 6 (b). At the switch tube S ₁ The second controllable switch tube S is turned on from the off state ₂ Always kept on, inductor L ₂ Is always by V _in Is magnetized and thus comprises a second controllable switching tube S ₂ The boost circuit does not affect the circuit comprising the first controllable switch tube S ₁ The operating state of the boost circuit. Comprises a first controllable switch tube S ₁ The equivalent circuit of the boost circuit in each mode is shown in fig. 7, and the shaded area in fig. 7 (a) is an added auxiliary circuit. FIG. 6 (b) shows a first controllable switch tube S ₁ The boost circuit is simplified as shown in FIG. 7 (b), and the input terminal is supplied with power V _in And a first inductance L ₁ Three diode capacitor branches are charged in series. Once S is present _a On, the circuit operates as shown in fig. 7 (c). Due to L _r Voltage at both ends is V _C4 ，i _Lr Increase linearly from zero, S _a ZCS is turned on, and the current flowing through the three diode capacitor branches begins to decrease. When i is _Lr ＝I _L1 While the current through the three diode-capacitor branches is reduced to zero, D ₂ 、D ₄ And D ₆ ZCS off is achieved and the circuit state changes as shown in fig. 7 (d). L is _r Start and C _S1 Occurrence of resonance, V _CS1 From V at the end of the state with a sinusoidal law _C4 Reducing to zero. When V is _CS1 When =0, the circuit state becomes as shown in fig. 7 (e) and the current starts to flow in reverse through the switching tube S ₁ . During this state, the first controllable switch S ₁ Achieving ZVS turn-on. In order to reduce the frequency of the power supply due to i _Lr Conduction losses due to circulating currents, first auxiliary switching tube S _a Is turned off and the circuit enters the state shown in fig. 7 (f). L is _r Energy of (D) through _a Is transferred to C ₁ . When i is _Lr Reduced to zero, D _a ZCS off is achieved and the state ends. The next state is that the two controllable switching tubes are simultaneously conducted, which is the same as the hard switching topology. Similarly, the above ZVT auxiliary circuit design method can also be applied to the other hard-switched TIBD converters in fig. 2. Since this type of converter can be functionally decomposed into three parts as shown in fig. 4, the different parts are the multiple parallel diode capacitor branches in the two boost circuits and the capacitors in the load supply loop. But whether containing S ₁ The boost circuit has a plurality of diode capacitance branches, because the auxiliary branch L _r -S _a In the first auxiliary switch tube S _a After being turned on, to I _L1 All diodes in the boost circuit can achieve ZCS turn-off when the current transfer is completed. After that, C _S1 And L _r Onset of resonance, V _CS1 Eventually resonating to zero. Thus, S ₁ The ZVS conduction condition is provided. Thus, comprising S ₁ All semiconductor devices in the boost circuit of (1) realize soft switching.

When S is ₁ After ZVS turn-on is achieved, if L _r Transfer energy to other capacitors, to contain S ₁ The added ZVT assist circuit of the boost circuit of (a) is shown in fig. 8. For these circuits, only the operating state of fig. 7 (f) differs among the corresponding simplified equivalent circuits. The dotted line in FIG. 8 is L _r Feeding back energy to the current paths of the different capacitors. The conduction loss of the auxiliary circuit in fig. 8 (a), (c) and (d) is larger than that of the auxiliary circuit in fig. 6 (a), 8 (b) and (e) because two controllable switching tubes are added in the energy feedback loop. Since the voltage stress of Sa in fig. 6 (a) and 8 (a) is lower than that of other circuits, a low on-resistance switch tube can be selected to reduce the conduction loss of the auxiliary circuit. Therefore, in the case of including S ₁ The auxiliary circuit in fig. 6 (a) is the most preferable design scheme among the auxiliary circuits of the boost circuit design of (a). Comparing all the auxiliary circuits in fig. 6 (a) and fig. 8, the general structure of the ZVT auxiliary circuit designed for one boost circuit in the TIBD converter is shown in fig. 9. According to the aboveThe design concept of the auxiliary circuit is that the shaded area in FIG. 10 (a) is to include S ₂ The dotted line is the resonant inductor energy feedback loop. Likewise, containing S ₂ All semiconductor devices in the boost circuit of (1) realize soft switching but contain S ₁ All semiconductor devices in the boost circuit of (1) are still operating in a hard switching state. In order to realize soft switching of all semiconductor devices in fig. 2 (d), a ZVT auxiliary circuit designed for two boost circuits is added at the same time, and the soft switching topology is shown in fig. 10 (b). Because the two auxiliary circuits only act in a short time near the turn-on time of the corresponding controllable switch tubes and the two controllable switch tubes work in a staggered way, the two auxiliary circuits do not influence each other. Considering the staggered working mode of the two auxiliary circuits, the two auxiliary circuits can share one resonant inductor, the two unidirectional switching tubes can be replaced by bidirectional switching tubes, and further the two unidirectional switching tubes are simplified into one auxiliary circuit, and the simplified soft switching circuit is shown in fig. 11. The diode capacitor boosting unit is a Bi-fold Dickson boosting unit and a first controllable switch tube S ₁ Drain electrode of the first capacitor C ₁ A third capacitor C ₃ A fourth capacitor C ₄ A sixth capacitor C ₆ And a resonant inductor L _r And a resonant inductor L _r And the other end of the first auxiliary switch tube S _a Drain electrode of (1), first auxiliary diode D _a And a second auxiliary diode D _b Is connected to the cathode of a second controllable switching tube S ₂ Has a drain connected with a first diode D ₁ Anode of, a second capacitor C ₂ A fifth capacitor C ₅ And a second auxiliary switching tube S _b And a second auxiliary switching tube S _b Source electrode and first auxiliary switch tube S _a Is connected to the source of (a); a first capacitor C ₁ And the other end of the first diode D ₁ Cathode of (1), first auxiliary diode D _a And a second diode D ₂ Is connected to the anode of a second capacitor C ₂ And the other end of the second diode D ₂ And a third diode D ₃ Is connected to the anode of a third capacitor C ₃ And the other end of the first diode D and a third diode D ₃ Cathode and cathode ofR carries _L One end connected to a fourth capacitor C ₄ And the other end of the fourth diode D ₄ Anode of (2), second auxiliary diode D _b And a fifth diode D ₅ Is connected to the cathode of a fifth capacitor C ₅ And the other end of the first diode D and a fifth diode D ₅ And a sixth diode D ₆ Is connected to the cathode of a sixth capacitor C ₆ And the other end of the first diode D and a sixth diode D ₆ Anode and load R _L Is connected to the other end of the fourth diode D ₄ Cathode and input terminal power supply V _in And connecting the negative electrode.

According to the same design concept, an optimal ZVT auxiliary circuit of two boost circuits is added to the hard-switching TIBD topology in fig. 2 (a), and the soft-switching circuit topology is shown in fig. 12 (a). Since the resonant inductances in the two auxiliary circuits do not have a common termination point, the final simplified auxiliary circuit is shown in FIG. 12 (b), L _r The energy feedback loop is shown in dashed lines. The diode capacitor boosting unit is a staggered voltage-multiplying unit and comprises 3 capacitors and 4 diodes, and the first controllable switch tube S ₁ The drain electrode of the first diode D is connected with the second diode D ₂ Anode of, a second capacitor C ₂ And a second auxiliary switching tube S _b Source electrode of (2), second controllable switch tube S ₂ Has a drain connected with a first diode D ₁ Anode of, first capacitor C ₁ And a first auxiliary switching tube S _a A source electrode of (a); resonant inductor L _r One terminal and a second auxiliary diode D _b An anode and a second auxiliary switch tube S _b A drain connected to the first auxiliary diode D _a Anode and first auxiliary switch tube S _a Drain electrode connected to a first capacitor C ₁ And the other end of the second diode D ₂ Cathode, third diode D ₃ Anode and second auxiliary diode D _b Cathode connection, second capacitor C ₂ And the other end of the first diode D ₁ Cathode, fourth diode D ₄ Anode and first auxiliary diode D _a Is connected to the cathode of a third diode D ₃ Cathode and fourth diode D ₄ Cathode, tenth capacitor C _o One end and a load R _L One end connected and the input end connectedSource V _in Negative electrode and tenth capacitor C _o The other end and a load R _L The other end is connected.

Applying the above-mentioned design idea of the ZVT auxiliary circuit to other topologies in fig. 2, and finally designing an optimal soft switching topology as shown in fig. 13, where fig. 13 (a) is a topology diagram of the converter with the ZVT auxiliary circuit in fig. 2 (b), and the diode capacitor boosting unit is a Cockcroft-Walton boosting unit, and includes 4 capacitors and 4 diodes; first controllable switch tube S ₁ Drain electrode of the first capacitor C ₁ And a second auxiliary switching tube S _b Source electrode of (2), second controllable switch tube S ₂ Has a drain connected with a first diode D ₁ Anode of (2), second capacitor C ₂ And a first auxiliary switching tube S _a A source electrode of (a); resonant inductor L _r One terminal and a second auxiliary diode D _b Anode and second auxiliary switch tube S _b A drain connected to the first auxiliary diode D _a Anode and first auxiliary switch tube S _a Drain electrode connected to a first capacitor C ₁ Is connected with the first auxiliary diode D _a Cathode, second auxiliary diode D _b Cathode, first diode D ₁ Cathode, second diode D ₂ Anode and third capacitor C ₃ One terminal of (C), a second capacitor C ₂ The other end of the first diode D is connected with a second diode D ₂ Cathode and third diode D ₃ Anode, third capacitance C ₃ The other end of the second diode D is connected with a third diode D ₃ Cathode and fourth diode D ₄ Anode, fourth diode D ₄ Cathode is connected with tenth capacitor C _o One end and a load R _L One end, input end power supply V _in Negative pole connected to tenth capacitor C _o The other end and a load R _L The other end;

fig. 13 (b) is a topology diagram of the converter with ZVT auxiliary circuit in fig. 2 (c), and the diode capacitor boosting unit is a Dickson boosting unit, and includes 4 capacitors and 4 diodes; the first controllable switch tube S ₁ Has a drain connected with a first diode D ₁ Anode and second capacitor C ₂ And a second auxiliary switching tube S _b Source electrode of (2), second controllable switch tube S ₂ Drain electrode of the first capacitor C ₁ One terminal, a third capacitor C ₃ And a first auxiliary switching tube S _a A source electrode of (a); resonant inductor L _r One end and a second auxiliary diode D _b An anode and a second auxiliary switch tube S _b A drain connected to the first auxiliary diode D _a Anode and first auxiliary switch tube S _a Drain electrode connected to a first capacitor C ₁ Is connected with the first auxiliary diode D _a Cathode, second auxiliary diode D _b Cathode, first diode D ₁ Cathode, second diode D ₂ Anode, second capacitor C ₂ The other end of the first diode D is connected with a second diode D ₂ Cathode and third diode D ₃ Anode, third capacitor C ₃ The other end of the second diode D is connected with a third diode D ₃ Cathode and fourth diode D ₄ Anode, fourth diode D ₄ Cathode is connected with tenth capacitor C _o One end and a load R _L One end, input end power supply V _in Negative electrode connected with capacitor C _o The other end and a load R _L The other end;

fig. 13 (c) is a topology diagram of the converter with ZVT auxiliary circuit in fig. 2 (e), and the diode-capacitor boosting unit is a Bi-fold Dickson boosting unit, and includes 4 capacitors and 4 diodes; the first controllable switch tube S ₁ Has its drain connected to the first diode D ₁ Anode and third capacitor C ₃ One terminal, a fourth capacitor C ₄ One end and a first auxiliary switch tube S _a The drain electrode of the first controllable switch tube S ₂ Drain electrode of the first capacitor C ₁ One terminal, a second capacitor C ₂ One terminal and a resonant inductor L _r One terminal, resonant inductor L _r The other end is connected with a first auxiliary diode D _a Cathode, second auxiliary diode D _b Anode and second auxiliary switch tube S _b Drain electrode of (1), second auxiliary switch tube S _b Source and S of _a Is connected to the source of the first capacitor C ₁ The other end of the first diode D ₁ Cathode, second diode D ₂ Anode and second auxiliary diode D _b Cathode, second capacitor C ₂ The other end of the second diode D is connected with a third diode D ₃ Anode, fourth diode D ₄ Cathode and first auxiliary diode D _a Anode, second diode D ₂ Cathode is connected with third capacitor C ₃ Another end and a load R _L One terminal, a fourth diode D ₄ Anode is connected with fourth capacitor C ₄ The other end and a load R _L The other end, a third diode D ₃ Cathode and input power supply V _in Connecting the negative electrodes;

FIG. 13 (d) is a converter topology of FIG. 2 (f) with ZVT auxiliary circuit, the diode capacitor boost unit is a Cockcroft-Walton and Dickson derived boost unit, which includes 7 capacitors and 7 diodes; first controllable switch tube S ₁ Drain electrode of the first capacitor C ₁ One terminal, a third capacitor C ₃ One terminal, a fifth capacitor C ₅ One end and a first auxiliary switch tube S _a The drain electrode of the first controllable switch tube S ₂ Drain electrode of the first capacitor is connected with the second capacitor C ₂ One terminal, a fourth capacitor C ₄ One terminal, a sixth capacitor C ₆ One terminal, the first diode D ₁ Anode and resonant inductor L _r One terminal, resonant inductor L _r The other end is connected with a first auxiliary diode D _a Cathode, second auxiliary diode D _b An anode and a second auxiliary switch tube S _b Drain electrode of (1), second auxiliary switch tube S _b Source electrode and first controllable switch tube S _a Is connected to the source of the first capacitor C ₁ The other end of the first diode D ₁ Cathode, second diode D ₂ Anode and second auxiliary diode D _b Cathode, fourth capacitor C ₄ The other end of the second diode D is connected with a fourth diode D ₄ Anode, fifth diode D ₅ Cathode and first auxiliary diode D _a Anode, second capacitor C ₂ The other end of the first diode D is connected with a second diode D ₂ Cathode and third diode D ₃ Anode, fifth capacitor C ₅ Is connected to the fifth diode D ₅ Anode and sixth diode D ₆ Cathode, third capacitor C ₃ The other end of the second diode D is connected with a third diode D ₃ Cathode and diode D _o Anode, sixth capacitor C ₆ The other end of the second diode D is connected with a sixth diode D ₆ Anode, tenth capacitor C _o And a load R _L One terminal, diode D _o Cathode is connected with tenth capacitor C _o And a loadR _L The other end, a fourth diode D ₄ Cathode connected with input end power supply V _in And a negative electrode.

FIG. 13 (e) is a converter topology of FIG. 2 (g) with ZVT auxiliary circuit, the diode capacitor boost unit is a Cockcroft-Walton and Dickson derived boost unit, comprising 7 capacitors and 7 diodes; first controllable switch tube S ₁ Drain electrode of the first capacitor is connected with the second capacitor C ₂ One terminal, a fourth capacitor C ₄ One terminal and a resonant inductor L _r One end, the second controllable switch tube S ₂ Drain electrode of the first capacitor C ₁ One end of (C), a fifth capacitor C ₅ One end of (1), a first diode D ₁ Anode, fifth diode D ₅ Cathode and second auxiliary switch tube S _b Drain electrode of (1), second auxiliary switch tube S _b Source electrode of (1) and first auxiliary switch tube S _a Source connection of, a resonant inductor L _r Is connected with the first auxiliary diode D _a Anode, second auxiliary diode D _b Cathode and first auxiliary switch tube S _a Drain electrode of (1), first capacitor C ₁ The other end of the first diode D is connected with a second diode D ₂ Cathode and third diode D ₃ Anode, second capacitor C ₂ The other end of the first diode D ₁ Cathode, second diode D ₂ An anode, the other end of the third capacitor C3 and a first auxiliary diode D _a Cathode, third capacitor C ₃ The other end of the second diode D is connected with a third diode D ₃ Cathode and fourth diode D ₄ Anode, fourth diode D ₄ Cathode is connected with tenth capacitor C _o One end and a load R _L One terminal, a fourth capacitor C ₄ Is connected to the fifth diode D ₅ Anode and sixth diode D ₆ Cathode and sixth capacitor C ₆ One terminal and a second auxiliary diode D _b Anode, fifth capacitor C ₅ The other end of the second diode D is connected with a sixth diode D ₆ Anode and diode D ₇ Cathode, sixth capacitor C ₆ Another end of the diode D ₇ Anode, tenth capacitor C _o Another end of (1) and a load R _L And the other end of the same.

FIG. 13 (f) is a converter topology of FIG. 2 (h) with ZVT assist circuit, the diode capacitance boostingThe voltage unit is a Cockcroft-Walton and Dickson derived voltage boosting unit and comprises 3 capacitors and 3 diodes, and a first controllable switch tube S ₁ Drain electrode of the first capacitor is connected with the second capacitor C ₂ One terminal, a third diode D ₃ Cathode and first auxiliary switch tube S _a Drain electrode of (2), a second controllable switch tube S ₂ Drain electrode of the first capacitor C ₁ One end of (1), a first diode D ₁ Anode and resonant inductor L _r One terminal, resonant inductor L _r The other end is connected with a first auxiliary diode D _a Cathode, second auxiliary diode D _b An anode and a second auxiliary switch tube S _b Drain electrode of (1), first auxiliary switch tube S _a And a second auxiliary switch S _b Is connected to the source of the first capacitor C ₁ Is connected with the first auxiliary diode D _a Anode, third diode D ₃ Anode and third capacitor C ₃ And a load R _L One terminal of (C), a second capacitor C ₂ The other end of the first auxiliary diode D is connected with a second auxiliary diode D _b Cathode, first diode D ₁ Cathode and second diode D ₂ Anode, third capacitor C ₃ The other end of the first diode D is connected with a second diode D ₂ Cathode and load R _L The other end; the topology of the auxiliary circuits of fig. 2 (i) and 2 (h) are similar.

Comparing the above soft switching topologies, it can be seen that there are two basic structures of the ZVT auxiliary circuit, as shown in fig. 14, the circuit structure of the ZVT auxiliary circuit in fig. 14 (a) is: the first auxiliary switch tube S _a Drain and resonant inductor L _r One end of the first auxiliary diode is connected with the first auxiliary diode D _a Anode connected, a second auxiliary switching tube S _b Drain and resonant inductor L _r The other end is connected with a second auxiliary diode D _b Anode connected to a first auxiliary switching tube S _a A source connected to the drain of one of the controllable switching tubes of the converter, a second auxiliary switching tube S _b A source connected to the drain of another controllable switch tube, a first auxiliary diode D _a A cathode connected to one end of a capacitor in a diode-capacitor boosting unit in the converter, and a second auxiliary diode D _b Some electricity in the diode capacitor boosting unit in the cathode and converterOne end of the container is connected. Fig. 14 (b) shows a circuit configuration of the ZVT auxiliary circuit: the first auxiliary switch tube S _a Source electrode and second auxiliary switch tube S _b Is connected with the source electrode of the first auxiliary switch tube S _a Drain and resonant inductor L of _r Is connected to one end of the first auxiliary diode D _a And a second auxiliary diode D _b Is connected to the cathode of the resonant inductor L _r The other end of the first auxiliary switch tube S is connected with the drain electrode of one controllable switch tube of the converter _b Is connected with the drain of another controllable switching tube, a first auxiliary diode D _a A cathode connected to one end of the first capacitor in the diode capacitor boosting unit in the converter, and a second auxiliary diode D _b And the anode is connected with one end of a second capacitor in the diode capacitor boosting unit. Due to L in the topology of FIG. 12 (b) _r The energy feedback loop has one more switching tube compared with the energy feedback loop in the topology of fig. 11, so the conduction loss of the auxiliary circuit in fig. 11 is lower. For the same reason, the simplified auxiliary circuit structure in fig. 14 (b) is superior to the simplified auxiliary circuit structure in fig. 14 (a).

The operation principle and parameter design of the ZVT converters with 3 VMC units in fig. 11 are illustrated as a general case. The two controllable switching tubes have the same driving signals and have the conduction duty ratio larger than 0.5, and the phase difference between the two controllable switching tubes is 180 degrees so as to realize high voltage gain. FIG. 15 shows the switching period T _s The theoretical waveforms for the converter of fig. 11, and the operating mode in the first half of the switching cycle are shown in fig. 16. D and D are the duty cycles of the main and auxiliary switches, respectively. α represents a phase shift angle between the main switch and the auxiliary switch. There are 12 modes in a switching cycle. However, due to the symmetrical working principle, only the first six modes were analyzed. At t ₆ To t ₇ During a time interval of (2), through S ₁ Is equal to S ₂ Input current I at turn-off _in . And at t ₀ To t ₁ Due to part of the input current flowing through D ₄ Thus at S ₁ Flows through S when turned off ₂ Current of less than I _in . Such absence between the two half switching cyclesThe symmetrical state does not affect the current and voltage relationship in the main circuit. C _S1 And C _S2 Same capacity value C _S1 ＝C _S2 ＝C _S 。

To simplify the steady state operation analysis, the following assumptions were made:

1) The capacitance and boost inductance in the VMC are large enough so they can be considered as a constant voltage source and a constant current source.

2) All semiconductor devices are ideal devices.

The working process of the topology is as follows:

mode 1: (t) ₀ ～t ₁ ):t ₀ At any moment, switch tube S ₁ Turn-off, shunt capacitance C _S1 Resulting in zero voltage turn-off, capacitor voltage V _Cs1 Quickly rises to V _C4 Second diode D ₂ 、D ₄ 、D ₆ On and the first diode D ₁ 、D ₃ 、D ₅ Reverse bias turn-off; first auxiliary switch tube S _a 、S _b Is in an off state and switches the transistor S ₂ Kept on, and the equivalent circuit is as shown in fig. 16 (a);

therefore, the two resonant capacitor voltages, the resonant inductor current and the duration expression are respectively:

mode 2: (t) ₁ ～t ₂ ):t ₁ At the moment, the first auxiliary switch tube S _a Turning on, and keeping the state of the previous mode by other semiconductor devices; resonant inductor voltage equal to V _C4 Resonant inductance L _r Current i of _Lr Starting from zero with a slope V _C4 /L _r Linearly rises due to the sum of L _r In the same branch, S _a Zero current switching-on is realized, and an equivalent circuit is shown in fig. 16 (b);

therefore, the two resonant capacitor voltages, the resonant inductor currents and the duration expressions are respectively:

mode 3: (t) ₂ ～t ₃ ):t ₂ Time of day, resonant inductor current i _Lr Up to the inductor current I _L1 At this time, the second diode D ₂ 、D ₄ 、D ₆ Zero current turn-off is realized; resonant inductor L _r Start and capacitance C _S1 Resonance, the equivalent circuit is shown in fig. 16 (c);

the expressions of two resonance capacitor voltages, resonance inductance currents and duration time obtained by the resonance equivalent circuit are respectively as follows:

wherein:

mode 4: (t) ₃ ～t ₄ ):t ₃ Time of day, capacitor voltage V _Cs1 Decreases to zero and resonates the inductor current i _Lr Is greater than I _L1 The current starts to flow reversely through the switch tube S ₁ All diodes are reverse biased off; in this mode S ₁ Zero voltage turn-on can be achieved with an equivalent circuit as shown in fig. 16 (d);

mode 5: (t) ₄ ～t ₅ ):t ₄ At the moment, the first auxiliary switch tube S _a Is turned off and the first auxiliary diode D _a Turning on, and keeping the state of the previous mode by other semiconductor devices; resonant inductor voltageIs equal to-V _C1 Thus i of _Lr With a slope V _C1 /L _r Linearly decreasing, the equivalent circuit is as shown in fig. 16 (e);

mode 6: (t) ₅ ～t ₆ ):t ₅ Time, i _Lr Reduced to zero, D _a Zero current turn-off is realized; input end power supply V _in For inductor L ₁ Linear magnetization and inductance L ₂ Always from input supply V during the first half of the switching cycle _in Linear magnetization is carried out; third capacitor C ₃ And a sixth capacitance C ₆ The series connection supplies power to the load in the whole switching period; t is t ₆ Time of day, S ₂ Off, the second half of the switching cycle begins and the equivalent circuit is as shown in fig. 16 (f).

considering the symmetry of the circuit operation in the front and back half periods

According to the principle of volt-second equilibrium, L ₁ The average value of the voltages across the period is zero, so the following equation can be obtained:

according to the charge balance principle, flows through D _a And D ₁ Is negativeCurrent carrying current from flowing through D _a 、D ₂ 、D ₄ And D ₆ The following equation can be obtained for the charge relationship of (a):

wherein:

according to the equivalent circuit of mode 1, the series of voltage relationships between different capacitances is written as follows:

from equation (7) to equation (10), the voltage gain can be expressed as:

wherein:

for a converter with N VMC cells, the voltage gain can be derived as:

wherein:

to visually display the voltage gain characteristic, the gain curve of M as a function of D under different load conditions is shown in fig. 17. As the duty cycle and the number of VMC units increase, the voltage gain increases significantly. It can be seen that the voltage gain is affected by the load.

To reduce the mainTurn-off loss of switch, v _CS1 And v _CS2 Should have a rise time of more than 3t _off Wherein t is _off Is the switch off time obtained from device data sheets or experimental tests. Thus, C _s Is calculated as follows:

in order to reduce the influence of the auxiliary branch on the main circuit, the time interval t ₁₃ Should be less than 1/10 of the half switching period. Thus, L _r Designed by the following formula:

in FIG. 16 (C) C _S1 In a resonant state, v _CS1 Is derived as in equation (15). From this formula, it can be seen that v _CS1 Is always reduced to zero over a period of pi/2 electrical degrees under any load and input voltage conditions. In other words, S ₁ ZVT can be always switched on under any load and input voltage condition, and wide-range soft switching is realized. Due to the symmetry of the working principle, S ₂ Also has a wide range ZVT turn-on characteristic.

v _CS1 (t)＝V _C4 cosω _r (t-t ₂ ) (15)

According to FIG. 15, S ₁ Must be at t ₃ Then turn on to achieve ZVT. Thus, the time interval t ₁ To a switching tube S ₁ The turn-on time should be greater than t ₁₃ . From this relationship, α:

in FIG. 15, at S ₁ Turn off S after the turn-on moment _a To ensure S ₁ ZVT of is on. Therefore, d/f must be satisfied _s >(1-α/2π)/f _s . The duty cycle d of the auxiliary switch can be represented by the following formulaTo obtain:

the time interval t being reduced when the duty cycle D is reduced ₆ To t ₇ Increases and the operating mode 6 disappears first. Thus, during mode 5, S ₂ Is turned off and the first diode D ₁ ，D ₃ ，D ₅ After turning on, the energy of the resonant inductor still passes through D _a Is fed back to C ₁ . However, this operational difference does not affect the voltage, current relationship in the main circuit. Therefore, when at t ₄ Is turned off at a moment S ₂ When D is obtained _min ：

According to fig. 15, the duration of mode 1 decreases as D increases. When it is reduced to 0, D is obtained _max ：

The maximum voltage and current ratings of the switching tube and diode are listed in table 1 according to fig. 15 and the operating principle. The effective current values of the switching tube and the diode are calculated by applying the equation (20).

TABLE 1

For large capacitors and inductors, the voltage and current ripple coefficients are used to design their parameters. Then, for a given current ripple factor δ _L Can be realized by simulationConverter circuit to obtain L ₁ And L ₂ . Another method is to calculate according to the formula in table 2. Also, a formula or simulation result may be applied to design the capacitance.

TABLE 2

Compared with other soft switching design methods, the ZVT circuit design method has small additional voltage stress and power loss. Therefore, to evaluate the performance of the converter constructed in fig. 11, a comparison was made with the latest other converters of different boost technologies and soft switching technologies in table 3. The Switching Device Power (SDP) of a semiconductor is expressed as the product of voltage stress and current stress. The total SDP is a measure of the total semiconductor device requirements and is an important cost indicator for the converter. The peak voltage and current of the power device under experimental operating conditions were used to calculate SDP. Also, the power densities were compared under the same operating conditions. By using SIMetrix software, a comparison of efficiencies at different loads is given in fig. 18. Although the inverter auxiliary circuit in fig. 11 has one more switching tube, the number of other elements is smaller than that of the conventional inverter. Moreover, the converter has the advantages of scalable high voltage gain, higher efficiency, lower SDP, higher power density, lower voltage stress and wider ZVS range than other converters. Documents [ T.Nouri, N.Vosoughi Kurdkandi and M.Shaneh, "A Novel ZVS High-Step-Up Converter With build-In Transformer Voltage Multiplier Cell," In IEEE Transactions on Power Electronics, vol.35, no.12, pp.12871-12886, dec.2020.]Is a typical non-isolated coupled inductor ZVS high gain dc converter with limited soft switching range, although the converter has similar performance to the ZVT converter constructed in fig. 11. Prior documents [ M.Jabbari and M.Mokhdar, "" High-Frequency Resonant ZVS Boost Converter With group Switches and Continuous Input Current, "" in IEEE Transactions on Industrial Electronics, vol.67, no.2, pp.1059-1067, feb.2020]Of resonant cascade structures of convertersZVS converters, which perform the worst due to transferring energy to the load in a resonant mode of operation. Although the literature [ S.Li, Y.ZHEN, B.Wu and K.M.Smedley, "A Family of sensitive Two-Switch Boosting Switch With ZVS Operation and a Line Regulation Range," in IEEE Transactions on Power Electronics, vol.33, no.1, pp.448-459, jan.2018]The switched capacitor ZVS converter in (1) has the potential advantages of high efficiency and high power density, but the voltage gain is too low to be applied in experimental conditions. Documents [ Z.Liao, Y.Lei and R.C.N.Pilawa-Podgurski, "" Analysis and Design of a High Power sensitivity Flying-packer Multilevel Boost Converter for High Step-Up Conversion, "" in IEEE Transactions on Power Electronics, vol.34, no.5, pp.4087-4099, may 2019]The medium multilevel converter operates on hard switching with the switching frequency set to 100kHz for fair comparison. The converter also has poor performance. Documents [ L.Shih, Y.Liu and H.Chiu, "A Novel Hybrid Mode Control for a Phase-Shift Fuel-Bridge Converter feeding High Efficiency Over a Full-Load Range," in IEEE Transactions on Power Electronics, vol.34, no.3, pp.2794-2804, march 2019]The phase-shifted full-bridge converter can represent an isolated bridge soft switching converter, and the converter has the advantages of less device number, low voltage stress of a low-voltage side switching tube and low current stress of a high-voltage side diode. However, high gain applications are inefficient and the control algorithm is complex to achieve a wide range of ZVS. V _in ＝20V，V _o ＝400V，P _o A comparison of the overall performance between these converters when =320W is shown in fig. 19, where 5 denotes best, 4 denotes excellent, 3 denotes normal, 2 denotes poor, 1 denotes very poor, and the parameters refer to reference table 3. It is evident from this figure that the converter in fig. 11 has better performance than the other converters.

TABLE 3

Example 1

Based on the auxiliary circuit and the converter in the embodiment, consideration is given to hardnessThe device circuit works at V _in ＝15V～25V，V _o ＝400V，f _s ＝500kHz，R _L ＝500Ω～1000Ω，δ _L ＝0.3，δ _C In the case of =0.02, the detailed parameter design is as follows:

1) Resonance parameter C _s And L _r : due to I _in ＝6.4A～21.3A，V _o ＝400V，t _off =3ns, according to formula (13), C _s Is 1.44nF, C is selected accordingly _s Was 1.5nF. Then, L is calculated from the formula (14) _r The design value was 1uH.

2) Control variables α, D: applying the equations (16) - (19) in order, the calculated α =16 pi/9, d =0.12 _min ＝0.51，D _max ＝0.89。

3) A semiconductor device: the resonance parameter L _r And C _s Substituting table 1, the maximum voltage and current stress of the main switch was calculated to be 66.7V and 23.9A. Therefore, the main switch is selected as GaN device GS61008T and the diode is selected as NTSB40200CTG.

4) Large capacitance and inductance: the calculated values of the passive elements are respectively L according to the table 2 and the working range ₁ ＝L ₂ ＝33.6uH，C ₁ ＝C ₄ ＝1.2uH，C ₂ ＝C ₅ ＝0.6uH，C ₃ ＝C ₆ =0.3uH. Finally, the device specifications of the converter in fig. 11 are listed in table 4.

At S _a At the turn-on instant of (2), the current flows in reverse direction through S _b . From the reverse conduction characteristic of the data sheet GS61008T, the tube drop on the positive voltage drive signal is much less than the tube drop on the zero voltage drive signal. Therefore, when one auxiliary switch is turned on, a positive drive signal should also be applied to the other auxiliary switch to reduce conduction losses. FIG. 20 shows the driving signals applied in the experiment, the inverter of FIG. 11 being in the rated condition V _in ＝20V，V _o ＝400V，R _L The power loss distribution at =500 Ω is shown in fig. 21. Since the main power loss is mainly due to conduction losses of the semiconductor devices, in order to further improve the converter efficiency, semiconductor devices with low on-resistance may be used in the hardware design.

In order to verify the theoretical analysis and evaluate the performance of the constructed transducer, a 320W hardware prototype was constructed with specifications as in table 4. The control board is realized by the DSP TMS320F 28335. The efficiency was measured using a digital power meter YOKOGAWA WT 1804E.

TABLE 4

Fig. 22-24 show experimental waveforms at steady state at different input voltages and loads. The voltage stress of the main switch and the diode measured in these figures is 67V and 133V, which substantially coincides with the theoretical values of 66.7V and 133.3V. In fig. 22 (a), it can be seen that the controllable switch S is turned on before the gate drive signal is turned on ₁ And S ₂ Has dropped to zero, so the main switch realizes ZVT turn-on, thereby greatly reducing the switching loss of the two switches. FIGS. 22 (b) and (c) show D ₁ ，D ₂ ，D ₅ And D ₆ ZCS is turned off, thus eliminating reverse recovery losses and suppressing EMI noise. And a resonant inductor current i _Lr The effectiveness of the theoretical analysis is further demonstrated, as is the theoretical waveform in fig. 15. To verify parametric design, fig. 23 and 24 show soft switching waveforms for different loads and input voltages. It can be seen that soft switching of all semiconductor devices is achieved over the entire input voltage and load range.

The dynamic response of the output voltage when the load and input voltage are stepped is shown in fig. 25. A conventional PI controller is used to regulate the output voltage. It is apparent that the converter of fig. 11 is capable of regulating the output voltage over a wide range of load and input voltage variations.

To validate the loss profile analysis, fig. 26 (a) plots the efficiency curves at different power levels. The measured curve is very close to the theoretical efficiency curve. Thus, the efficiency advantage of the ZVT converter is verified. Under this operating condition, the efficiency of the converter in fig. 11 peaks at 94.9%. Fig. 26 (b) shows a comparison of the voltage gain ratio between the theoretical value and the experimental result. The two curves are also very close. Therefore, the effectiveness of the above theoretical analysis and parameter design was verified.

On the basis of the topology of the high-gain direct-current converter of the prior staggered diode capacitor network, the switching-on and switching-off of all switching tubes ZVS and all diodes ZCS of the converter are realized by the soft switch design scheme of the universal ZVT auxiliary circuit. The auxiliary switching tube realizes ZCS on, and the auxiliary diode realizes ZCS off. Therefore, the efficiency is improved while the switching frequency is increased, the high power density is realized, and the electromagnetic interference is restrained.

The above-mentioned contents are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modification made on the basis of the technical solution according to the technical idea of the present invention falls within the protection scope of the claims of the present invention.

Claims

1. A high-gain DC converter ZVT auxiliary circuit with staggered diode capacitor networks is characterized by comprising a first auxiliary circuit, a second auxiliary circuit and a resonant inductor (a)L _r ) The first auxiliary circuit comprises a first auxiliary switch tube (S _a ) And a first auxiliary diode: (D _a ) The second auxiliary circuit comprises a second auxiliary switch tube (S _b ) And a second auxiliary diode: (D _b ) The first auxiliary circuit and the second auxiliary circuit share a resonant inductor (L _r ) For implementing ZVS on and off of the first controllable switch tube and the second controllable switch tube in the dc converter, and the first auxiliary switch tube (S _a ) And a second auxiliary switch tube (S _b ) Realize ZCS and turn on, all diodes realize ZCS and turn off, wherein:

the first auxiliary switch tube (a)S _a ) Drain and resonant inductor (L _r ) One end of the first auxiliary diode is connected with the first auxiliary diodeD _a ) Anode connection, second auxiliary switch tube (S _b ) Drain and resonant inductor (L _r ) The other end is connected with a second auxiliary diode (c)D _b ) Anode connection, first auxiliary switch tube (a)S _a ) A source electrode connected to the drain electrode of one of the controllable switching tubes of the converter, a second auxiliary switching tube(s) ((S _b ) A source connected to the drain of another controllable switch tube, a first auxiliary diode(s) ((D _a ) Cathode and second auxiliary diode: (D _b ) The cathode is connected to a diode capacitor boosting unit in the converter;

or, the first auxiliary switch tube (a)S _a ) Source and second auxiliary switch tube (S _b ) Is connected with the source electrode of the first auxiliary switch tube (a)S _a ) Drain and resonant inductor of (1)L _r ) Is connected to one end of the first auxiliary diode and is connected to the first auxiliary diode (D _a ) And a second auxiliary diode: (D _b ) Cathode connection, resonance inductance: (L _r ) The other end of the first auxiliary switch tube is connected with the drain electrode of one controllable switch tube of the converter, and a second auxiliary switch tube: (S _b ) Is connected with the drain of another controllable switch tube, a first auxiliary diode(s) ((s))D _a ) Cathode and second auxiliary diode: (D _b ) The anode is connected to a diode capacitor boosting unit in the converter.

2. An interleaved diode capacitor network high gain ZVT DC converter comprising the ZVT auxiliary circuit of claim 1, comprising two interleaved input terminals, a diode capacitor boosting unit and an output terminal load (b: (b))R _L ) The two phase interlaced input terminals include an input terminal power supply (V _in ) First interleaved inductor (a)L ₁ ) A second interleaved inductor (a)L ₂ ) A first controllable switch tube (a)S ₁ ) A second controllable switch tube (a)S ₂ ) A first resonant capacitor (C _s1 ) And a second resonanceVolume (A), (B)C _s2 ) The input terminal power supply (V _in ) The positive electrode is simultaneously connected with the first interleaved inductor (L) ₁ ) And a second interleaved inductor (L ₂ ) Is connected to a first interleaved inductor (L ₁ ) The other end and a first controllable switch tube (a)S ₁ ) Is connected with the drain of the first controllable switch tube (a)S ₁ ) Source of (2) is connected to input power supplyV _in ) A negative electrode; second interleaved inductor (L ₂ ) The other end and a second controllable switch tube (S ₂ ) Drain electrode of (1), a second controllable switch tubeS ₂ ) Source of (2) is connected with input end power supplyV _in ) Negative electrode, first resonant capacitor: (C _s1 ) And a first controllable switch tube (S ₁ ) Parallel connection, a second resonance capacitance (C _s2 ) And a second controllable switch tube (a)S ₂ ) Parallel connection; it is characterized by that between the described two-phase staggered input end and diode capacitor boosting unit a ZVT auxiliary circuit is added to implement first controllable switch tubeS ₁ ) And a second controllable switch tube (S ₂ ) The ZVT auxiliary circuit comprises a first auxiliary switch tube (S _a ) A second auxiliary switch tube (S _b ) A first auxiliary diode (D _a ) A second auxiliary diode (c)D _b ) And a resonant inductor (L _r ）；

The first controllable switch tube (S ₁ ) And a second controllable switch tube (S ₂ ) Has a drive signal phase difference of 180 ^o The on duty ratio of the first auxiliary switch tube and the second auxiliary switch tube are the same and are both more than 0.5: (S _a ) And a second auxiliary switch tube (S _b ) Has a drive signal phase difference of 180 ^o And is only conducted before the corresponding controllable switch tube is turned on.

3. According to the rightThe interleaved diode-capacitor network high-gain ZVT (zero volt Current) DC converter as claimed in claim 2, wherein the diode-capacitor boosting unit is a Bi-fold Dickson boosting unit, and comprises 6 capacitors and 6 diodes, and the first controllable switch tube(s) ((S ₁ ) The drain of (2) is connected with a first capacitorC ₁ ) A third capacitor (C ₃ ) A fourth capacitor (C ₄ ) A sixth capacitor (C ₆ ) And a resonant inductor: (L _r ) And a resonant inductor: (L _r ) The other end of the first switch tube and a first auxiliary switch tube (S _a ) Drain electrode of (1), first auxiliary diodeD _a ) And a second auxiliary diode: (D _b ) Is connected to the cathode of a second controllable switching tube (a)S ₂ ) Drain electrode of (is connected with a first diode: (D ₁ ) Anode, second capacitor: (C ₂ ) Fifth capacitor (c)C ₅ ) And a second auxiliary switching tube (S _b ) And a second auxiliary switching tube(s) ((s))S _b ) Source electrode and first auxiliary switch tube (S _a ) Is connected to the source of (a); a first capacitor (C ₁ ) The other end of (1) and a first diodeD ₁ ) The cathode, the first auxiliary diode: (D _a ) And a second diode: (D ₂ ) Anode connection of (2), second capacitance (C ₂ ) And the other end of (b) and a second diodeD ₂ ) And a third diode: (D ₃ ) Anode connection of (2), third capacitance (C ₃ ) And the other end of (c) and a third diodeD ₃ ) A cathode and a load (R _L ) One end of the fourth capacitor is connected withC ₄ ) And the other end of (b) and a fourth diodeD ₄ ) (ii) an anode, a second auxiliary diodeD _b ) Anode and fifth diode (c) (ii)D ₅ ) Is connected to the cathode, a fifth capacitorC ₅ ) And the other end of (b) and a fifth diodeD ₅ ) And a sixth diode (c)D ₆ ) Is connected to the cathode, a sixth capacitorC ₆ ) And the other end of (b) and a sixth diodeD ₆ ) An anode and a load of (R _L ) Is connected to the other end of the fourth diode: (D ₄ ) Cathode and input power supply of (V _in ) The negative electrode is connected.

4. The interleaved diode-capacitor network high-gain ZVT (zero voltage Voltage Transformer) DC converter as claimed in claim 2, wherein the diode-capacitor voltage boosting unit is an interleaved voltage doubling unit comprising 3 capacitors and 4 diodes, and the first controllable switch tube(s), (b), (c), (d) and (d) is/are connected to the first controllable switch tube(s) (b) ((c))S ₁ ) Drain electrode of (2) is connected to the second diodeD ₂ ) Anode, second capacitor: (C ₂ ) And a second auxiliary switching tube (S _b ) Source electrode of (1), second controllable switch tubeS ₂ ) Drain electrode of (2) is connected with the first diodeD ₁ ) The anode and the first capacitor (C ₁ ) And a first auxiliary switch tube (a)S _a ) A source electrode of (a); resonance inductor (a)L _r ) One end and a second auxiliary diode (D _b ) An anode and a second auxiliary switch tube (S _b ) A drain electrode connected to the first auxiliary diode(s)D _a ) An anode and a first auxiliary switch tube (S _a ) Drain electrode connection, first capacitor (C ₁ ) The other end of (A) and a second diode (A)D ₂ ) Cathode, third diode: (D ₃ ) An anode and a second auxiliary diode (D _b ) Cathode connection, second capacitanceC ₂ ) The other end of (1) and a first diodeD ₁ ) Cathode, fourth diode: (D ₄ ) An anode and a first auxiliary diode: (D _a ) Is connected to the cathode of a third diode (a)D ₃ ) Cathode and fourth diode (D ₄ ) Cathode, tenth capacitor (C _o ) One end and a load (R _L ) One end connected to the input end power supply (V _in ) Negative electrode and tenth capacitorC _o ) Another end and a load (R _L ) The other end is connected.

5. The interleaved diode capacitor network high gain ZVT dc converter as claimed in claim 2, wherein said diode capacitor boost unit is a Cockcroft-Walton boost unit comprising 4 capacitors and 4 diodes; first controllable switch tube (S ₁ ) The drain of (2) is connected with a first capacitorC ₁ ) And a second auxiliary switching tube (S _b ) Source electrode of (2), second controllable switch tube (S ₂ ) Drain electrode of (is connected with a first diode: (D ₁ ) Anode, second capacitor: (C ₂ ) And a first auxiliary switch tube (a)S _a ) A source electrode of (a); resonant inductor (L _r ) One end and a second auxiliary diode (D _b ) An anode and a second auxiliary switch tube (S _b ) A drain electrode connected to the first auxiliary diode(s)D _a ) An anode and a first auxiliary switch tube (S _a ) Drain electrode connection, first capacitor (C ₁ ) The other end of (b) is connected with a first auxiliary diode (b) ((b))D _a ) Cathode, second auxiliary diode: (D _b ) Cathode, first diode (D ₁ ) Cathode, second diode: (D ₂ ) An anode and a third capacitor (C ₃ ) One terminal of (a second capacitor:)C ₂ ) The other end of (b) is connected to a second diodeD ₂ ) Cathode and third diode: (D ₃ ) Anode, third capacitor (C ₃ ) The other end of (b) is connected with a third diodeD ₃ ) Cathode and fourth diode: (D ₄ ) Anode, fourth diode: (D ₄ ) The cathode is connected with a tenth capacitorC _o ) One end and a load (R _L ) One end, input end power supply (V _in ) Negative electrode is connected to tenth capacitor (C _o ) Another end and a load (R _L ) And the other end.

6. The interleaved diode capacitor network high gain ZVT dc converter as claimed in claim 2, wherein said diode capacitor boost unit is a Dickson boost unit comprising 4 capacitors and 4 diodes; the first controllable switch tube (S ₁ ) Drain electrode of (is connected with a first diode: (D ₁ ) Anode, second capacitor (C ₂ ) And a second auxiliary switching tube (S _b ) Source electrode of (1), second controllable switch tubeS ₂ ) The drain of (2) is connected with a first capacitorC ₁ ) One terminal, a third capacitor (C ₃ ) And a first auxiliary switch tube (a)S _a ) A source electrode of (a); resonant inductor (L _r ) One end and a second auxiliary diode (D _b ) An anode and a second auxiliary switch tube (S _b ) A drain electrode connected to the first auxiliary diode(s)D _a ) An anode and a first auxiliary switch tube (S _a ) Drain electrode connection, first capacitor (C ₁ ) The other end of (b) is connected with a first auxiliary diode (b) ((b))D _a ) Cathode, second auxiliary diode: (D _b ) Cathode, first diode (D ₁ ) Cathode, second diode: (D ₂ ) Anode, second capacitor (C ₂ ) The other end of (b) is connected to a second diodeD ₂ ) Cathode and third diode: (D ₃ ) Anode, third capacitor (C ₃ ) The other end of (b) is connected with a third diodeD ₃ ) Cathode and fourth diode: (D ₄ ) Anode, fourth diode: (D ₄ ) The cathode is connected with a tenth capacitorC _o ) One end and a load (R _L ) One end, input end power supply (V _in ) Negative electrode connection capacitorC _o ) Another end and a load (R _L ) And the other end.

7. The interleaved diode capacitor network high gain ZVT dc converter as claimed in claim 2, wherein said diode capacitor boost unit is a Bi-fold Dickson boost unit comprising 4 capacitors and 4 diodes; the first controllable switch tube (S ₁ ) Drain electrode of (is connected with a first diode: (D ₁ ) Anode and third capacitorC ₃ One terminal, a fourth capacitorC ₄ One end and a first auxiliary switch tube (S _a ) Drain electrode of (1), second controllable switch tubeS ₂ ) The drain of (A) is connected with a first capacitor (C ₁ ) One terminal, a second capacitor (C ₂ ) One terminal and a resonant inductor (L _r ) One terminal, resonant inductor: (L _r ) The other end is connected with a first auxiliary diode (D _a ) Cathode, second auxiliary diode: (D _b ) An anode and a second auxiliary switch tube (S _b ) Drain electrode of (1), second auxiliary switch tubeS _b ) Source electrode of andS _a ) Is connected to the source of the first capacitorC ₁ ) The other end of (2) is connected to a first diodeD ₁ ) Cathode, second diode: (D ₂ ) An anode and a second auxiliary diode (D _b ) Cathode, second capacitor (a)C ₂ ) Another end of (1)Connected to the third diode (D ₃ ) Anode, fourth diode: (D ₄ ) Cathode and first auxiliary diode: (D _a ) Anode, second diode: (D ₂ ) The cathode is connected with a third capacitorC ₃ ) Another end and a load (R _L ) One terminal, a fourth diode (D ₄ ) Anode connected to fourth capacitorC ₄ ) Another end and a load (R _L ) The other end, a third diode: (D ₃ ) Cathode and input power supply (V _in ) And connecting the negative electrode.

8. The interleaved diode capacitor network high gain ZVT dc converter as claimed in claim 2, wherein said diode capacitor boost unit is a Cockcroft-Walton and Dickson derived boost unit comprising 7 capacitors and 7 diodes; first controllable switch tube (a)S ₁ ) The drain of (2) is connected with a first capacitorC ₁ ) One terminal, a third capacitor (C ₃ ) One terminal, a fifth capacitor (C ₅ ) One end and a first auxiliary switch tube (S _a ) Drain electrode of (2), second controllable switch tubeS ₂ Drain electrode of (2) is connected with a second capacitor (C ₂ ) One terminal, a fourth capacitor (C ₄ ) One terminal, a sixth capacitor (C ₆ ) One terminal, a first diode (D ₁ ) Anode and resonance inductor (L _r ) One terminal, a resonant inductor (L _r ) The other end is connected with a first auxiliary diode (D _a ) Cathode, second auxiliary diode: (D _b ) An anode and a second auxiliary switch tube (S _b ) Drain electrode of (1), second auxiliary switch tubeS _b Source electrode of (2) and first controllable switch tube (S _a ) Is connected to the source of the first capacitorC ₁ ) The other end of (2) is connected to a first diodeD ₁ ) Cathode, second diode: (D ₂ ) An anode and a second auxiliary diode (D _b ) Cathode, fourth capacitor (C ₄ ) The other end of (b) is connected with a fourth diodeD ₄ ) Anode, fifth diode: (D ₅ ) Cathode and first auxiliary diode: (D _a ) Anode, second capacitor (C ₂ ) The other end of (b) is connected to a second diodeD ₂ ) Cathode and third diode: (D ₃ ) Anode, fifth capacitor (a)C ₅ ) The other end of (b) is connected with a fifth diodeD ₅ ) Anode and sixth diode: (D ₆ ) Cathode, third capacitor (C ₃ ) The other end of (b) is connected with a third diodeD ₃ ) Cathode and diode (a)D _o ) Anode, sixth capacitor: (C ₆ ) The other end of (b) is connected with a sixth diodeD ₆ ) Anode, tenth capacitor (C _o ) And a load (R _L ) One terminal, a diode (D _o ) The cathode is connected with a tenth capacitorC _o ) And a load (R _L ) The other end, a fourth diode: (D ₄ ) Cathode connected to input power supplyV _in ) And a negative electrode.