阅读说明：本技术 一种低输入电流纹波高增益软开关直流变换器 (Low-input-current-ripple high-gain soft-switching direct-current converter ) 是由 林国庆 王建 于 2021-09-08 设计创作，主要内容包括：本发明涉及一种低输入电流纹波高增益软开关直流变换器。包括输入端口,负载端口,第一开关管、第二开关管,第一二极管、第二二极管、第三二极管,输入电感、耦合电感,第一电容、第二电容、第三电容、第四电容、第五电容及负载；通过对两个开关管的互补控制,可以实现两个开关管的零电压导通和三个二极管的零电流关断。本发明的低输入电流纹波高增益软开关直流变换器具有电压增益高、输入电流纹波小、变换效率高、开关管电压应力小等优点,非常适合于非隔离的可再生能源发电系统。(The invention relates to a low-input-current-ripple high-gain soft-switching direct-current converter. The circuit comprises an input port, a load port, a first switch tube, a second switch tube, a first diode, a second diode, a third diode, an input inductor, a coupling inductor, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor and a load; by complementary control of the two switching tubes, zero voltage conduction of the two switching tubes and zero current turn-off of the three diodes can be realized. The low-input-current-ripple high-gain soft-switching direct-current converter has the advantages of high voltage gain, small input current ripple, high conversion efficiency, small voltage stress of a switching tube and the like, and is very suitable for a non-isolated renewable energy power generation system.)

1. A low-input-current-ripple high-gain soft-switching direct-current converter is characterized by comprising an input port, a load port, a first switching tube, a second switching tube, a first diode, a second diode, a third diode, an input inductor, a coupling inductor, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor and a load; the positive electrode of the input port is connected with one end of the primary side of the coupling inductor, one end of the first capacitor and the drain electrode of the first switching tube through the input inductor, the negative electrode of the input port is connected with the source electrode of the first switching tube, one end of the second capacitor, one end of the fifth capacitor and the negative electrode of the load port, the other end of the first capacitor is connected with the source electrode of the second switching tube and the cathode of the third diode, the drain electrode of the second switching tube is connected with the other end of the fifth capacitor and the positive electrode of the load port, the other end of the second capacitor is connected with the other end of the primary side of the coupling inductor, one end of the third capacitor and the anode of the first diode, the other end of the third capacitor is connected with one end of the secondary side of the coupling inductor and the anode of the second diode, one end of the fourth capacitor is connected with the cathode of the second diode and the anode of the third diode, and the other end of the secondary side of the coupling inductor, The cathode of the first diode is connected.

2. The soft-switching direct-current converter with low input current ripple and high gain according to claim 1, wherein zero-voltage turn-on of two switching tubes and zero-current turn-off of three diodes are realized through complementary control of the two switching tubes.

3. The soft switching DC converter with low input current ripple and high gain according to claim 1 or 2, wherein the first switching tube S₁And a second switching tube S₂Complementary to each otherConducting with dead time, and coupling leakage inductance of inductor with S in dead time₁、S₂Junction capacitance C_s1、C_s2Resonance generation to realize S₁The zero voltage soft switch of (1); leakage inductance and S using input inductance and coupling inductance₁、S₂Junction capacitance C_s1、C_s2Resonance generation to realize S₂The zero voltage soft switch, therefore, two switch tubes can realize zero voltage turn-on, and all diodes can realize zero current turn-off due to the existence of the leakage inductance of the coupling inductor.

4. The low-input-current-ripple high-gain soft-switching direct-current converter according to claim 1, wherein the voltage gain of the high-gain direct-current converter isD is the conduction duty ratio of the first switching tube, N is the ratio of the number of turns of the secondary side to the number of turns of the primary side of the coupling inductor equivalent ideal transformer, and V is_oTo output a voltage, V_inIs the input voltage.

Technical Field

The invention relates to the technical field of power electronics, in particular to a low-input-current-ripple high-gain soft-switching direct-current converter.

Background

Energy is a material basis and a power source for the development and progress of the whole human society, and with the increasing exhaustion of the traditional fossil energy and the increasing serious problems of environmental pollution, global warming and the like caused by the traditional fossil energy, the development and the utilization of new energy are more and more paid attention by people. At present, the more applied new energy power generation modes mainly include photovoltaic power generation, fuel cell power generation and the like, have the characteristics of wide resource distribution, large development potential, small environmental impact and sustainable utilization, and have become the hot spots of concern and research of various countries in the world.

Because the direct-current output voltage level of the single photovoltaic cell is low and cannot meet the voltage level requirement of the direct-current side of the grid-connected inverter, a direct-current converter with a high step-up ratio is required to be added at the front end of the direct-current bus side of the power generation system to improve the voltage level, and the power generation system is ensured to inject the generated electric energy into a power grid. Therefore, the high-gain dc converter is receiving more and more attention from researchers at home and abroad.

The conventional high-gain direct current converter generally realizes various boosting functions by adjusting the turn ratio of the coupling inductor, but the boosting function realized by simply adjusting the turn ratio of the coupling inductor has the following problems: the voltage stress of the switching device is high, the voltage peak caused by the leakage inductance of the coupling inductor can increase the voltage stress of the switching tube or the diode, the stress of the switching device is further increased, and the serious electromagnetic interference problem is caused.

Meanwhile, for new energy such as photovoltaic energy, fuel cells and the like, the input current ripple of the boost converter not only affects the power generation efficiency, but also affects the service life of the new energy, so that the research on the boost converter with low current ripple, high voltage gain, low voltage stress and high efficiency is of great significance.

Disclosure of Invention

The invention aims to provide a low-input-current-ripple high-gain soft-switching direct-current converter which has the advantages of high voltage gain, small input current ripple, high conversion efficiency, small voltage stress of a switching tube and the like and is very suitable for a non-isolated renewable energy power generation system.

In order to achieve the purpose, the technical scheme of the invention is as follows: a low-input-current-ripple high-gain soft-switching direct-current converter comprises an input port, a load port, a first switching tube, a second switching tube, a first diode, a second diode, a third diode, an input inductor, a coupling inductor, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor and a load; the positive electrode of the input port is connected with one end of the primary side of the coupling inductor, one end of the first capacitor and the drain electrode of the first switching tube through the input inductor, the negative electrode of the input port is connected with the source electrode of the first switching tube, one end of the second capacitor, one end of the fifth capacitor and the negative electrode of the load port, the other end of the first capacitor is connected with the source electrode of the second switching tube and the cathode of the third diode, the drain electrode of the second switching tube is connected with the other end of the fifth capacitor and the positive electrode of the load port, the other end of the second capacitor is connected with the other end of the primary side of the coupling inductor, one end of the third capacitor and the anode of the first diode, the other end of the third capacitor is connected with one end of the secondary side of the coupling inductor and the anode of the second diode, one end of the fourth capacitor is connected with the cathode of the second diode and the anode of the third diode, and the other end of the secondary side of the coupling inductor, The cathode of the first diode is connected.

In an embodiment of the invention, zero-voltage conduction of the two switching tubes and zero-current turn-off of the three diodes are realized through complementary control of the two switching tubes.

In an embodiment of the present invention, the first switch tube S₁And a second switching tube S₂Complementary conduction with a dead time, by coupling the leakage inductance of the inductor with S during the dead time₁、S₂Junction capacitance C_s1、C_s2Resonance generation to realize S₁The zero voltage soft switch of (1); leakage inductance and S using input inductance and coupling inductance₁、S₂Junction capacitance C_s1、C_s2Resonance generation to realize S₂The zero voltage soft switch, therefore, two switch tubes can realize zero voltage turn-on, and all diodes can realize zero current turn-off due to the existence of the leakage inductance of the coupling inductor.

In one embodiment of the present inventionIn one embodiment, the high-gain DC converter has a voltage gain ofD is the conduction duty ratio of the first switching tube, N is the ratio of the number of secondary turns to the number of primary turns of the coupling inductor, and V is_oTo output a voltage, V_inIs the input voltage.

In an embodiment of the present invention, the coupling inductor may be equivalent to the excitation inductor L_mConnected in parallel with the primary side of the ideal transformer and the leakage inductance L of the coupling inductance_kThe number of primary and secondary turns of the coupled inductor in series connection is N_pAnd N_s。

Compared with the prior art, the invention has the following beneficial effects: the low-input-current-ripple high-gain soft-switching direct-current converter improves the voltage gain by using the coupling inductor and the capacitor diode boosting network, realizes zero-voltage conduction of the main switching tube and the auxiliary switching tube and zero-current turn-off of the diode by using the auxiliary switching tube to control the leakage inductance of the coupling inductor and the resonance process of the junction capacitor of the switching tube, and has the advantages of high voltage gain, small input current ripple, high conversion efficiency, small voltage stress of the switching tube, high reliability and the like.

Drawings

FIG. 1 is a schematic diagram of a low input current ripple high gain soft switching DC converter according to the present invention

Fig. 2 shows the main operating waveforms.

Fig. 3 is an equivalent circuit diagram of each mode.

FIG. 4 shows simulated waveforms of the driving and drain-source voltages of the switching tube.

Fig. 5 shows simulated waveforms of the switching tube and the inductor current.

Fig. 6 is a simulation waveform of each capacitor voltage.

Detailed Description

The technical scheme of the invention is specifically explained below with reference to the accompanying drawings.

The invention relates to a low-input-current-ripple high-gain soft switching direct-current converter which comprises an input port, a load port, a first switching tube, a second switching tube, a first diode, a second diode, a third diode, an input inductor, a coupling inductor, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor and a load, wherein the input port is connected with the load port; the positive electrode of the input port is connected with one end of the primary side of the coupling inductor, one end of the first capacitor and the drain electrode of the first switching tube through the input inductor, the negative electrode of the input port is connected with the source electrode of the first switching tube, one end of the second capacitor, one end of the fifth capacitor and the negative electrode of the load port, the other end of the first capacitor is connected with the source electrode of the second switching tube and the cathode of the third diode, the drain electrode of the second switching tube is connected with the other end of the fifth capacitor and the positive electrode of the load port, the other end of the second capacitor is connected with the other end of the primary side of the coupling inductor, one end of the third capacitor and the anode of the first diode, the other end of the third capacitor is connected with one end of the secondary side of the coupling inductor and the anode of the second diode, one end of the fourth capacitor is connected with the cathode of the second diode and the anode of the third diode, and the other end of the secondary side of the coupling inductor, The cathode of the first diode is connected; and zero voltage conduction of the two switching tubes and zero current turn-off of the three diodes are realized through complementary control of the two switching tubes.

The following is a specific implementation process of the present invention.

As shown in fig. 1, the present invention relates to a circuit structure of a low input current ripple high gain soft switching dc converter: the circuit comprises an input port, an inductor, a coupling inductor, two switching tubes, three diodes and five capacitors.

Main switch tube S₁And an auxiliary switching tube S₂Complementary conduction with dead time, using the leakage inductance of the coupling inductor and the switch tube S in the dead time₁、S₂Junction capacitance C_s1、C_s2Resonance generation to realize switch tube S₁The zero voltage soft switch of (1); leakage inductance and switch tube S using input inductance and coupling inductance₁、S₂Junction capacitance C_s1、C_s2Resonance generation to realize switch tube S₂The zero-voltage soft switch can realize zero-voltage switching-on of the two switching tubes, and zero-current switching-off of all diodes can be realized due to the existence of leakage inductance of the coupling inductorAnd the reverse recovery problem of the diode is solved. The realization of the soft switch enables the leakage inductance energy of the coupling inductor to be effectively utilized, thereby reducing the voltage stress of the switch tube, selecting the power tube with low voltage-resistant grade to reduce the cost of the converter and improving the efficiency of the converter.

The voltage gain of the high-gain DC converter of the invention isThe voltage gain M is much higher than that of a conventional Boost converter (Boost converter) by 1/(1-D).

The low-input-current-ripple high-gain soft-switching direct-current converter improves the voltage gain by using the coupling inductor and the capacitor diode boosting network, realizes zero-voltage conduction of the main switching tube and the auxiliary switching tube and zero-current turn-off of the diode by using the auxiliary switching tube to control the leakage inductance of the coupling inductor and the resonance process of the junction capacitor of the switching tube, and has the advantages of high voltage gain, small input current ripple, high conversion efficiency, small voltage stress of the switching tube, high reliability and the like.

The working principle is as follows:

to simplify the analysis, the following assumptions were made: capacitor C₁、C₂、C₃、C₄、C_oThe value is large enough, and voltage ripples at two ends of the capacitor are ignored; both switching tubes and diodes are ideal devices.

For the sake of principle analysis, the coupling inductor in fig. 1 is equivalent to an excitation inductor L_mLeakage inductance L connected in parallel with primary side of ideal transformer and coupled with coupling inductance_kAre connected in series. The circuit has 8 working modes in one switching period, the main working waveform of the converter is shown in figure 2, the equivalent circuit of each mode is shown in figure 3, and the simulation waveforms are shown in figures 4 to 6.

The working mode of the switching tube of the converter is as follows: main switch tube S₁And an auxiliary switching tube S₂Complementary conduction and dead time.

1) Mode 1 (t)₀-t₁)：t₀Before the moment, the switch tube S₂And a diode D₁、D₂Is in conductionState, switching tube S₁And a diode D₃In an off state. t is t₀Time switch tube S₂Turn off due to parallel capacitance C_s2Action of S₂The near zero voltage is turned off. In this stage, the leakage inductance L_kAnd a capacitor C_s1、C_s2Resonance occurs, the switch tube S₂Drain-source voltage v_ds2Begins to increase gradually from 0 and switches on and off the tube S₁Drain-source voltage v_ds1And begins to taper. Each current flow path is shown in fig. 3 (a).

2) Mode 2 (t)₁-t₂)：t₁Time switch tube S₁Drain-source voltage v_ds1When the voltage is reduced to 0, the diode in the body is conducted, and the input power supply V_inTo the inductance L₁Charging, current i_L1Linearly increasing; leakage inductance current i_LkLinear reduction, exciting inductive current i_LmContinues to increase linearly and flows through the diode D due to leakage inductance₁、D₂Current i of_D1、i_D2And also linearly decreases. Each current flow path is shown in fig. 3 (b).

3) Mode 3 (t)₂-t₃)：t₂Time switch tube S₁Is turned on when S₁Conducting for zero voltage. The operation mode of this stage is the same as the previous mode, and the current flow paths are as shown in fig. 3 (c).

4) Mode 4 (t)₃-t₄)：t₃Time of day leakage current i_LkReduced to and excitation inductance current i_LmEqual when flowing through diode D₁、D₂Current i of_D1、i_D2Also reduced to 0, diode D₁、D₂And naturally shutting down. Capacitor C₂、C₃、C₄Connected in series with the secondary winding via a diode D₃And a switching tube S₁Capacitor C₁Charging, diode current i_D3Starts to rise linearly from 0; output capacitor C_oTo a load R_oAnd (5) supplying power. Each current flow path is shown in fig. 3 (d).

5) Mode 5 (t)₄-t₅)：t₄Time switch tube S₁Turn off due to parallel capacitance C_s1Action of S₁The near zero voltage is turned off. In this phase, the input inductance L₁And leakage inductance L_kTogether with a capacitor C_s1、C_s2Resonance occurs, the switch tube S₁Drain-source voltage v_ds1Gradually increases from 0 to open and close the tube S₂Drain-source voltage v_ds2Gradually decrease; each current flow path is shown in fig. 3 (e).

6) Modal 6 (t)₅-t₆)：t₅Time switch tube S₂Drain-source voltage v_ds2When the voltage is reduced to 0, the diode in the body is conducted, and the leakage inductance current i_LkStarting linear reduction, exciting inductor current i_LmContinuing to increase linearly, diode D₃Current i of_D3And also linearly decreases. Each current flow path is shown in fig. 3 (f).

7) Mode 7 (t)₆-t₇)：t₆Time of day leakage current i_LkReduced to and excitation inductance current i_LmEqual when flowing through diode D₃Is reduced to 0, diode D₃And naturally shutting down. In this phase, the secondary windings are each passed through a diode D₁、D₂Capacitor C₃、C₄Charging, diode current i_D1、i_D2Increases linearly from 0; exciting inductor current i_LmStarting to decrease linearly, current i_LkThe linear reduction continues. Each current flow path is shown in fig. 3 (g).

8) Mode 8 (t)₇-t₀)：t₇Time switch tube S₂Conduction, S₂Conducting for zero voltage. In this phase, the leakage inductance current i_LkAnd exciting inductor current i_LmAfter the linearity is reduced to 0, the reverse linearity is increased and the output capacitance C is_oChanging from a charged state to a discharged state. Each current flow path is shown in fig. 3 (h).

And when the complete working cycle is ended, starting to enter the next working cycle.

And (3) gain analysis:

suppose a main switch S₁The conduction duty ratio is D, N is the number of turns of the secondary side of the coupling inductor and the primary sideRatio of turns, by inductance L₁、L_k、L_mThe voltage of each capacitor and the expression of the output voltage obtained by the volt-second balance are as follows:

V_C2＝V_in

the converter voltage gain is then:

utilizing saber simulation software to simulate the circuit, wherein simulation parameters are as follows: v_in＝40V，L₁＝200uH，L_k＝8uH，L_m＝100uH，C₂＝47uF，C₁＝C₃＝C₄＝10uF，C_o＝100uF，C_s1＝C_s22.5nF, 100kHz of switching frequency, 0.6 of main switching tube duty ratio D, 2 of turn ratio N, and load R_o800 Ω. As can be seen from FIG. 4, the two switching tubes realize zero-voltage soft switching, the voltage stress of the switching tubes is only 100V, and the power tube with low withstand voltage level can be selected to reduce the cost of the converter, thereby improving the efficiency of the converter. As can be seen from fig. 5, the input current ripple is about 1.231A and about 25% of the input current when the fuel cell is fully loaded, and the input current ripple is small, which is beneficial to improving the power generation efficiency and the service life of the fuel cell or the photovoltaic panel; and because of the existence of the leakage inductance of the coupling inductor, the problem of reverse recovery of each diode is solved. As can be seen from FIG. 6, the output voltage V_o393.5V, the voltage gain is 9.84 times, and the theoretical analysis showsAnd (5) the consistency is achieved.

The above are preferred embodiments of the present invention, and all changes made according to the technical scheme of the present invention that produce functional effects do not exceed the scope of the technical scheme of the present invention belong to the protection scope of the present invention.