A high-gain dc-dc converter based on switched inductor and switched capacitor

Abstract

The application provides a high-gain DC-DC converter based on switched inductance and switched capacitance, comprising an active switched inductance network, a first passive switched capacitance network, a second passive switched capacitance network and an RCD circuit, wherein an input end of the active switched inductance network is connected with a direct-current power supply, output ends of the active switched inductance network are connected with the first passive switched capacitance network and the second passive switched capacitance network respectively, and the first passive switched capacitance network and the second passive switched capacitance network are connected with the RCD circuit respectively.The high-gain DC-DC converter has the advantages of high voltage gain, low voltage stress and current stress of components, small inductance current ripple, low loss and high efficiency, and is suitable for two-stage micro photovoltaic grid-connected inverters, fuel cell power generation systems, servo motor driving systems, vehicle-mounted inverters, uninterrupted power supplies (UPS) and other occasions.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of converters, in particular to a high-gain DC-DC converter based on switched inductor and switched capacitor. BACKGROUND

[0002] Photovoltaic power generation is one of the important forms of using solar energy. The traditional centralized photovoltaic grid-connected power generation system has many problems such as reliability, MPPT tracking efficiency, system scalability, etc. The micro-inverter grid-connected system can effectively solve the problem of the influence of the reliability of the centralized inverter on the system in the centralized grid-connected scheme, and the photovoltaic micro-inverter is the core unit of the micro-inverter grid-connected system. Compared with the single-stage photovoltaic grid-connected inverter, the two-stage photovoltaic grid-connected inverter can parallel the energy storage capacitor on the intermediate bus, and the required energy storage capacitor capacity is relatively small, but the output voltage of the photovoltaic cell is generally much lower than the required DC voltage of the grid-connected inverter, so the DC-DC converter in the front stage of the two-stage circuit topology needs to have a very high boost ratio. At the same time, in fuel cell power generation systems, servo motor drive systems, vehicle-mounted inverters, uninterruptible power supplies (UPS), and other application scenarios, high-boost-ratio DC-DC converters are also needed for power conversion.

[0003] In order to solve the above problems, domestic and foreign scholars have carried out a lot of research work on isolated high-boost-ratio DC-DC converters. The isolated high-boost-ratio DC-DC converter mainly combines the Boost converter with the isolation transformer, and uses the turns ratio of the transformer to improve the boost ratio of the converter, but the transformer occupies a large volume, and the leakage inductance of the transformer cannot transfer energy to the secondary side, which will cause the switching tube to produce serious turn-off oscillation. Therefore, in some occasions that do not require electrical isolation, non-isolated high-voltage gain DC-DC converters can be used.

[0004] The non-isolated high-boost-ratio DC-DC converter mainly applies switched capacitor, switched inductor and coupled inductor to the switching converter to improve the boost ratio. Among them, the cascaded Boost converter can effectively improve the voltage gain of the converter and widen the input voltage range, but the circuit structure is complex, the cost is high, and the control difficulty is also geometrically increased. The high-gain DC-DC converter based on switched capacitor has high voltage gain, the voltage stress of the switching tube and the diode is correspondingly reduced, and the loss is small, but the volume of the magnetic element is correspondingly large, which is not conducive to improving the power density, and there is a large pulse current during startup. The high-gain DC-DC converter based on switched inductor has a smaller single inductor volume, the same working mode, but the voltage gain is difficult to achieve 10 times or more in actual application, and the inductance needs to be equalized for current sharing optimization. The high-gain DC-DC converter based on coupled inductor proposed by some scholars can also obtain a high boost ratio, but the voltage stress of the output diode is high. SUMMARY

[0005] The application provides a high-gain DC-DC converter based on switched inductance and switched capacitance, which comprises an active switched inductance network, a first passive switched capacitance network, a second passive switched capacitance network and an RCD circuit, wherein the input end of the active switched inductance network is connected with a direct current power supply, the output end of the active switched inductance network is connected with the first passive switched capacitance network and the second passive switched capacitance network respectively, and the first passive switched capacitance network and the second passive switched capacitance network are connected with the RCD circuit respectively.

[0006] As a further improvement of the application, the active switched inductance network comprises a first inductor, a second inductor, a first power switch tube and a second power switch tube, wherein one end of the first inductor is connected with the cathode of the first power switch tube, the first passive switched capacitance network and the second passive switched capacitance network respectively, and the other end of the first inductor is connected with the negative electrode of the input end and the cathode of the second power switch tube respectively.

[0007] One end of the second inductor is connected with the positive electrode of the input end and the anode of the first power switch tube respectively, and the other end of the second inductor is connected with the first passive switched capacitance network, the second passive switched capacitance network and the anode of the second power switch tube respectively.

[0008] The anode of the first power switch tube is also connected with the positive electrode of the input end, and the cathode of the first power switch tube is also connected with the first passive switched capacitance network and the second passive switched capacitance network respectively.

[0009] The anode of the second power switch tube is also connected with the first passive switched capacitance network and the second passive switched capacitance network respectively, and the cathode of the second power switch tube is also connected with the negative electrode of the input end.

[0010] As a further improvement of the application, the first passive switched capacitance network comprises a first capacitor and a first diode, wherein the negative electrode of the first capacitor is connected with the anode of the first diode and the RCD circuit respectively, and the positive electrode of the first capacitor is connected with the second passive switched capacitance network, the anode of the second power switch tube and the other end of the second inductor respectively.

[0011] The cathode of the first diode is connected with the cathode of the first power switch tube, and the anode of the first diode is also connected with the RCD circuit.

[0012] As a further improvement of the application, the second passive switched capacitor network comprises a second capacitor, a third capacitor, a fourth capacitor, a second diode, a third diode, a fourth diode, wherein the negative pole of the second capacitor is connected to the positive pole of the first capacitor, the anode of the second diode, the anode of the second power switch tube and the other end of the second inductor respectively, and the positive pole of the second capacitor is connected to the cathode of the third diode and the anode of the fourth diode respectively.

[0013] The negative pole of the third capacitor is connected to the positive pole of the fourth capacitor, the cathode of the second diode and the anode of the third diode respectively, and the positive pole of the third capacitor is connected to the cathode of the fourth diode and the RCD circuit respectively.

[0014] The negative pole of the fourth capacitor is connected to the cathode of the first diode and the cathode of the first power switch tube respectively, and the positive pole of the fourth capacitor is also connected to the cathode of the second diode and the anode of the third diode respectively.

[0015] The anode of the second diode is also connected to the positive pole of the first capacitor, the other end of the second inductor and the anode of the second power switch tube respectively, and the cathode of the second diode is also connected to the anode of the third diode.

[0016] The cathode of the third diode is also connected to the anode of the fourth diode.

[0017] The cathode of the fourth diode is also connected to the RCD circuit.

[0018] As a further improvement of the application, the RCD circuit comprises a fifth capacitor, a fifth diode and a resistor, wherein the negative pole of the fifth capacitor is connected to the anode of the fifth diode, one end of the resistor and the negative pole of the output voltage respectively, and the positive pole of the fifth capacitor is connected to the positive pole of the third capacitor and the cathode of the fourth diode respectively.

[0019] The cathode of the fifth diode is connected to the anode of the first diode and the negative pole of the first capacitor respectively, and the anode of the fifth diode is also connected to one end of the resistor and the negative pole of the output voltage respectively.

[0020] One end of the resistor is also connected to the negative pole of the output voltage, and the other end of the resistor is connected to the positive pole of the third capacitor, the cathode of the fourth diode and the positive pole of the output voltage respectively.

[0021] As a further improvement of the application, the first power switch tube and the second power switch tube are power MOSFET tubes or IGBT tubes.

[0022] As a further improvement of the present application, the first diode, the second diode, the third diode, the fourth diode and the fifth diode are power diodes.

[0023] The present application has the following advantages: 1. The high-gain DC-DC converter based on switched-inductor and switched-capacitor has the advantages of high voltage gain, low voltage and current stress of components, small inductor current ripple, low loss and high efficiency; 2. The high-gain DC-DC converter based on switched-inductor and switched-capacitor is suitable for two-stage micro photovoltaic grid-connected inverters, fuel cell power generation systems, servo motor drive systems, vehicle-mounted inverters, uninterruptible power supplies (UPS) and other application occasions. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is the circuit schematic diagram of the high-gain DC-DC converter of the present application;

[0025] Figure 2 is Figure 1 the working waveform diagram of the high-gain DC-DC converter shown, Figure 2(a) is the CCM mode, and Figure 2(b) is the DCM mode;

[0026] Figure 3 is Figure 1 the equivalent circuit diagram of the current continuous mode (CCM) and the current discontinuous mode (DCM) of the high-gain DC-DC converter shown;

[0027] Figure 4 is Figure 1 the equivalent circuit diagram of the current continuous mode (CCM) and the current discontinuous mode (DCM) of the high-gain DC-DC converter shown;

[0028] Figure 5 is Figure 1 the equivalent circuit diagram of the current discontinuous mode (DCM) of the high-gain DC-DC converter shown;

[0029] Figure 6 is Figure 1 the critical relationship diagram of the current continuous mode (CCM) and the current discontinuous mode (DCM) of the high-gain DC-DC converter shown;

[0030] Figure 7 is Figure 1 the simulation result diagram of the input voltage and the output voltage of the high-gain DC-DC converter shown;

[0031] Figure 8(a) is Figure 1 the current waveform diagram of the high-gain DC-DC converter shown flowing through the first inductor L1 and the second inductor L2, and Figure 8(b) is Figure 1The diagram shows the voltage waveforms of the drain and source terminals of the switching transistors flowing through the first inductor L1 and the second inductor L2 in the high-gain DC-DC converter.

[0032] Figure 9(a) is Figure 1 The voltage waveforms of each diode in the high-gain DC-DC converter are shown in Figure 9(b). Figure 1 The voltage waveforms of each capacitor in the high-gain DC-DC converter are shown.

[0033] Explanation of the labels in the diagram: V i V is the input voltage. o For output voltage; I L1 I L2 These are the average currents of inductors L1 and L2, respectively; V C1 V C2 V C3 V C4 V Co Capacitors C1, C2, C3, C4, and C are respectively. o Average voltage; V S1 V S2 These are the average voltages of switches S1 and S2, respectively; V D1 V D2 V D3 V D4 V Do Diodes D1, D2, D3, D4, and D are respectively. o The average voltage. Detailed Implementation

[0034] like Figure 1 As shown, the high-gain DC-DC converter based on switched inductors and switched capacitors disclosed in this invention includes an active switched inductor network and two different passive switched capacitor networks. The passive switched capacitor networks include a first passive switched capacitor network 2, a second passive switched capacitor network 3, and an RCD circuit. The input terminal of the high-gain DC-DC converter based on switched inductors and switched capacitors is connected to a DC voltage source, and the output terminal uses capacitor filtering. In this embodiment, the topology combines one active switched inductor network and two passive switched capacitor networks.

[0035] Specifically, the high-gain DC-DC converter disclosed in this embodiment includes: an active switching inductor network and two different passive switching capacitor networks, a DC voltage source, and an RCD circuit. The input terminal V of the active switching inductor network 1... i The active switching inductor network 1 is connected to a DC power supply. Its output terminal is connected to the first passive switching capacitor network 2 and the second passive switching capacitor network 3, respectively. The first passive switching capacitor network 2 and the second passive switching capacitor network 3 are connected to the RCD circuit, respectively.

[0036] The active switching inductor network 1 comprises a first inductor L1, a second inductor L2, a first power switch S1 and a second power switch S2; one end of the first inductor L1 is connected with the cathode of the first power switch S1, the first passive switching capacitor network 2 and the second passive switching capacitor network 3 respectively, the other end of the first inductor L1 is connected with the cathode of the second power switch S2 and the input terminal V i respectively, one end of the second inductor L2 is connected with the positive terminal of the input terminal V i respectively, the other end of the second inductor L2 is connected with the anode of the second power switch S2, the first passive switching capacitor network 2, the second passive switching capacitor network 3 and the anode of the second power switch S2 respectively.

[0037] The first passive switching capacitor network 2 comprises a first capacitor C1 and a first diode D1; the negative terminal of the first capacitor C1 is connected with the anode of the first diode D1 and the RCD circuit respectively, the positive terminal of the first capacitor C1 is connected with the second passive switching capacitor network 3, the anode of the second power switch S2 and the other end of the second inductor L2 respectively, the cathode of the first diode D1 is connected with the cathode of the first power switch S1.

[0038] The second passive switching capacitor network 3 comprises a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a second diode D2, a third diode D3 and a fourth diode D4; the negative terminal of the second capacitor C2 is connected with the positive terminal of the first capacitor C1, the anode of the second diode D2 and the anode of the second power switch S2 and the other end of the second inductor L2, the positive terminal of the second capacitor C2 is connected with the cathode of the third diode D3 and the anode of the fourth diode D4, the negative terminal of the third capacitor C3 is connected with the positive terminal of the fourth capacitor C4, the cathode of the second diode D2 and the anode of the third diode D3 respectively, the positive terminal of the third capacitor C3 is connected with the cathode of the fourth diode D4 and the RCD circuit respectively, the negative terminal of the fourth capacitor C4 is connected with the cathode of the first diode D1 and the cathode of the first power switch S1 respectively.

[0039] As a preferred, the first power switch S1 and the second power switch S2 are power MOSFET tubes or IGBT tubes, the first diode D1, the second diode D2, the third diode D3, the fourth diode D4, the fifth diode D o are power diodes.

[0040] In order to simplify the analysis process, it is assumed that all devices are ideal devices, and the influence of their parasitic parameters on the operation of the circuit is not considered; all capacitors are large enough to make the capacitor voltage tend to a stable value; the specifications of the inductors are completely symmetrical, and the specifications of the capacitors are completely symmetrical.

[0041] The power switching transistors of the converter use the same control method. Depending on whether the inductor current is continuous or not, the converter can operate in continuous current mode (CCM) and discontinuous current mode (DCM), and its operating waveform is shown in Figure 2.

[0042] (A) The converter operates in continuous current mode (CCM), which includes the following two modes:

[0043] In mode 1 ([t0, t0+DT]), both switches S1 and S2 are on. The equivalent operating circuit is as follows: Figure 3 As shown. Inductors L1 and L2 are both connected to the input power supply V. i During charging, diodes D0 and D3 are forward biased, while diodes D1, D2, and D4 are reverse biased. Capacitor C2 is charged through V. i Charging with C4, capacitor C o Charge to (V) C1 +V C2 +V C3 The load passes through V o -C1-S2-V i -S1-C4-C3-V o The circuit is connected to the input power supply. At this point, according to Kirchhoff's voltage law, the voltage equation can be written as follows:

[0044] V L1，on =V L2，on =V i V C2 =V C4 +V i V o =V C1 +V C2 +V C3

[0045] In mode 2 ([t0+DT,T]), the first power switch S1 and the second power switch S2 are simultaneously turned off. The equivalent operating circuit is as follows: Figure 4 As shown. Diodes D1, D2, and D4 begin to conduct, while D3 and D5... o Reverse bias. Both inductor L1 and inductor L2 are discharging. Capacitor C1, capacitor C3, and diode C4 are connected through V. i The first inductor L1 and the second inductor L2 are charging, and the fifth capacitor C is charging. o Power is supplied to the load. Applying Kirchhoff's voltage law to this range, we obtain the following voltage equation:

[0046] V i =V L1,off +V L2,off +V c1 V C1= V C4 , V C2 = V C3 , V o = V Co

[0047] In continuous current mode (CCM), both the first inductor L1 and the second inductor L2 satisfy the volt-second balance:

[0048]

[0049]

[0050]

[0051]

[0052]

[0053] where D is the duty cycle of the switch, V i is the input voltage, V o is the output voltage, V L1，on , V L2，on are the average voltages of the first inductor L1 and the second inductor L2 when the first power switch S1 and the second power switch S2 are turned on, V L1，off , V L2，off are the average voltages of the first inductor L1 and the second inductor L2 when the first power switch S1 and the second power switch S2 are turned off, V C1 , V C2 , V C3 , V C4 , V Co are the average voltages of the first capacitor C1, the second capacitor C2, the third capacitor C3, the fourth capacitor C4, and the fifth capacitor C o , V S1 , V S2 are the average voltages of the first power switch S1 and the second power switch S2, V D1 , V D2 , V D3 , V D4 , V Do are the average voltages of the first diode D1, the second diode D2, the third diode D3, the fourth diode D4, and the fifth capacitor D o , M ideal is the theoretical gain of the converter, and T is the switching period.

[0054] The current loop in Figure 3 and Figure 4 is represented by the KCL equation:

[0055] IC4,on =I C4,on -I C4,on I C1,on =I C3,on =I o +I Co,on I S1,on =I L1,on -I C4,on

[0056] I C2,off =-I C3,off I Co,off =-I o I L1,off =I L2,off =I C1,off +I C4,off

[0057] From the ampere-second balance of charging and discharging of each capacitor and the conservation of power on the input and output sides, we can obtain:

[0058]

[0059]

[0060]

[0061]

[0062] In the formula I in For the input current, I o For the output current, I L1，on I L2，on I represents the average current in inductors L1 and L2 when the first power switch S1 and the second power switch S2 are turned on, respectively. L1，off I L2，off These are the average currents of the first inductor L1 and the second inductor L2 when the first power switch S1 and the second power switch S2 are turned off, respectively. L1 I L2 The average currents I of the first inductor L1 and the second inductor L2 are respectively. C1，on I C2，on I C3，on I C4，on I Co，on The capacitors C1, C2, C3, C4, and C5 are respectively the capacitors when the first power switch S1 and the second power switch S2 are turned on. o The charging and discharging current, I C1，off I C2，off I C3，off I C4，offThe average current of the first power switch S1 and the second power switch S2, M is the gain of the converter. S1，on The average current of the first power switch S1 and the second power switch S2, M is the gain of the converter.

[0063] In the power switch on mode, the first power switch S1, the second power switch S2 and the fifth diode D o , the third diode D3 have current stress, and the relationship is as follows:

[0064] I Do =-I C1,on , I D3 =I C2,on

[0065] In the power switch off mode, the first diode D1, the second diode D2 and the fourth diode D4 have current stress, and the relationship is as follows:

[0066] I D1 =I C1,off , I D4 =I C4,off -I C4,off , I D4 =I C2,off

[0067]

[0068] In the formula, I D1 , I D2 , I D3 , I D4 , I Do are the average currents of the first diode D1, the second diode D2, the third diode D3, the fourth diode D4 and the fifth diode D o , respectively, and I S1 , I S2 are the average currents of the first power switch S1 and the second power switch S2, respectively.

[0069] (B) The converter works in the current discontinuous mode (DCM) and includes the following three modes:

[0070] Mode 1: [t0, t0+DT] time, the first power switch S1 and the second power switch S2 are in the on state. The equivalent working circuit is shown in Figure 3 . The first inductor L1 and the second L2 are all through the input power V iCharging, fifth diode D0, third diode D3 forward biased, first diode D1, second diode D2, fourth diode D4 reverse biased, second capacitor C2 charges through V i and fourth capacitor C4 o to (V C1 +V C2 +V C3 ), load is powered by V o -C1-S2-V i -S1-C4-C3-V o The peak currents of the first inductor L1 and the second inductor L2 can be expressed as:

[0071]

[0072] Mode 2: [t0+DT, t0+(1-Dx)T], the first power switch S1 and the second power switch S2 are off. The equivalent circuit is shown in Figure 4 . The first diode D1, the second diode D2, the fourth diode D4 start to conduct, while the third diode D3, the fifth diode D o are reverse biased. The first inductor L1 and the second inductor L2 are discharged. The first capacitor C1, the third capacitor C3, the fourth capacitor C4 charge through V i , the first inductor L1 and the second inductor L2, the fifth capacitor C o powers the load, and the inductor current decreases to 0 at the end of mode 2. The voltage across the first capacitor C1 can be expressed as:

[0073]

[0074] The peak currents of the first inductor L1 and the second inductor L2 can be expressed as:

[0075]

[0076] The average current of the first diode D1 is:

[0077]

[0078] Mode 3: [t0+(1-Dx)T, T], the first power switch S1 and the second power switch S2 are still off, and the equivalent circuit is shown in Figure 5 . The currents of the first inductor L1 and the second inductor L2 have decreased to 0, so the voltage across the inductor is 0, and the power supply and the inductor no longer provide energy to the outside. All diodes are in reverse bias, and the load is powered by the energy stored in the fifth capacitor C o . According to the inductor volt-second balance principle, we have:

[0079]

[0080] In the discontinuous current mode (DCM), according to the KCL equation, the following can be obtained:

[0081]

[0082]

[0083]

[0084] When the converter works in the critical condition between the DCM mode and the CCM mode, the following can be obtained:

[0085]

[0086] In the formula, V i is the input voltage, V o is the output voltage, V C1 is the average voltage of the first capacitor C1, I L1p , I L2p are the peak currents of the first inductor L1 and the second inductor L2 respectively, I D1 , I D2 , I D3 , I D4 , I Do are the average currents of the first diode D1, the second diode D2, the third diode D3, the fourth diode D4 and the fifth diode D o respectively, Dx is the time ratio at the end of mode 2, D is the duty cycle of the power switch tube, M DCM is the converter gain in the discontinuous current mode (DCM), fs is the switching frequency, R is the load resistance value, L is the inductance of the first inductor L1 and the second inductor L2, τ is the time constant, and τ b is the critical time constant.

[0087] The critical time constant τ b is related to the duty cycle D of the power switch tube, as shown in the figure. Figure 6 When τ>τ b , the converter works in the CCM mode, and when τ<τ b , the converter works in the DCM mode. As can be seen from the figure, when the duty cycle is close to the limit values 0 and 1, a smaller τ value is needed to make the converter work in the CCM mode, and vice versa.

[0088] In summary, the high-gain DC-DC converter based on switched inductance and switched capacitance provided by the application has a higher voltage gain while maintaining low voltage stress and current stress of the components.

[0089] Simulation experiments are conducted by using the high-gain DC-DC converter based on switched inductor and switched capacitor provided in the embodiment, and the following results are obtained.

[0090] When the switching frequency fs is 49 kHz, the input voltage V i = 20 V, the duty cycle D = 0.6, the first capacitor C1, the second capacitor C2, the third capacitor C3, the fourth capacitor C4 and the fifth capacitor C o = 100 μF, the first inductor L1 and the second inductor L2 are 400 μH, and the load resistance R is 200 Ω, the simulation results of the input voltage and the output voltage are as shown in Figure 7 The simulation output voltage is 279 V, and the theoretical output voltage is 280 V, so the simulation voltage gain conforms to the theoretical value.

[0091] The current waveforms of the first inductor L1 and the second inductor L2 and the voltage waveforms of the power switch tube drain-source are shown in Fig. 8. The inductor current waveforms are the same, which are sawtooth waves, and the current average values are about 10.5 A, and are always greater than 0, so the converter works in the CCM mode. The stress of the first power switch tube S1 and the second power switch tube S2 is 50 V, which is the same as the theoretical value, and is much smaller than the output voltage.

[0092] The voltage waveforms of the capacitors and diodes are shown in Fig. 9. The voltage stress of the first capacitor C1 and the fourth capacitor C4 is about 80 V, and the voltage stress of the second capacitor C2 and the third capacitor C3 is about 100 V, which are the same as the calculated theoretical values. The voltage stress of all diodes is 100 V, and when the first diode D1, the second diode D2 and the fourth diode D o are forward biased, the third diode D3 and the fifth diode D

[0093] The high-gain DC-DC converter based on switched inductor and switched capacitor has the advantages of high voltage gain, low voltage stress and current stress of components, small inductor current ripple, low loss and high efficiency.

[0094] The above is the further detailed description of the present application in combination with the specific preferred embodiments, and the specific implementation of the present application should not be limited to these descriptions. For ordinary skilled persons in the technical field to which the present application belongs, some simple deductions or substitutions can be made without departing from the concept of the present application, and all of them should be regarded as falling within the protection scope of the present application.

Claims

1. A high-gain DC-DC converter based on switched-inductor and switched-capacitor, characterized in that: The application relates to a switching power supply circuit, which comprises an active switching inductor network (1), a first passive switching capacitor network (2), a second passive switching capacitor network (3) and an RCD circuit, wherein the input end (V i ) of the active switching inductor network (1) is connected with a direct current power supply, the output end of the active switching inductor network (1) is connected with the first passive switching capacitor network (2) and the second passive switching capacitor network (3) respectively, the first passive switching capacitor network (2) and the second passive switching capacitor network (3) are connected with the RCD circuit respectively, the active switching inductor network (1) comprises a first inductor (L1), a second inductor (L2), a first power switch tube (S1) and a second power switch tube (S2), wherein One end of the first inductor (L1) is connected with the cathode of the first power switch tube (S1), the first passive switch capacitor network (2) and the second passive switch capacitor network (3) respectively, and the other end of the first inductor (L1) is connected with the input end (V i ) negative electrode and the cathode of the second power switch tube (S2) respectively; One end of the second inductor (L2) is connected with the input end (V i ) positive electrode, the anode of the first power switch tube (S1), the other end of the second inductor (L2) is connected with the first passive switch capacitor network (2), the second passive switch capacitor network (3), the anode of the second power switch tube (S2) respectively; Anode of the first power switch tube (S1) is connected with input end (V i ) positive pole, and cathode of the first power switch tube (S1) is connected with the first passive switch capacitor network (2) and the second passive switch capacitor network (3) respectively. Anode of the second power switch tube (S2) is connected with the first passive switch capacitor network (2) and the second passive switch capacitor network (3) respectively, and cathode of the second power switch tube (S2) is connected with the input end (V i ) negative electrode. The first passive switched capacitor network (2) comprises a first capacitor (C1) and a first diode (D1), wherein, The negative pole of the first capacitor (C1) is connected with the anode of the first diode (D1) and the RCD circuit respectively, and the positive pole of the first capacitor (C1) is connected with the second passive switched capacitor network (3), the anode of the second power switch tube (S2) and the other end of the second inductor (L2) respectively; The cathode of the first diode (D1) is connected with the cathode of the first power switch tube (S1), and the anode of the first diode (D1) is also connected with the RCD circuit; The second passive switched capacitor network (3) comprises a second capacitor (C2), a third capacitor (C3), a fourth capacitor (C4), a second diode (D2), a third diode (D3) and a fourth diode (D4), wherein, The negative pole of the second capacitor (C2) is connected with the positive pole of the first capacitor (C1), the anode of the second diode (D2), the anode of the second power switch tube (S2) and the other end of the second inductor (L2) respectively, and the positive pole of the second capacitor (C2) is connected with the cathode of the third diode (D3) and the anode of the fourth diode (D4) respectively; The negative pole of the third capacitor (C3) is connected with the positive pole of the fourth capacitor (C4), the cathode of the second diode (D2) and the anode of the third diode (D3) respectively, and the positive pole of the third capacitor (C3) is connected with the cathode of the fourth diode (D4) and the RCD circuit respectively; the negative pole of the fourth capacitor (C4) is connected with the cathode of the first diode (D1) and the cathode of the first power switch tube (S1) respectively, and the positive pole of the fourth capacitor (C4) is also connected with the cathode of the second diode (D2) and the anode of the third diode (D3) respectively; The anode of the second diode (D2) is also connected with the positive pole of the first capacitor (C1), the other end of the second inductor (L2) and the anode of the second power switch tube (S2) respectively, and the cathode of the second diode (D2) is also connected with the anode of the third diode (D3); The cathode of the third diode (D3) is also connected with the anode of the fourth diode (D4); The cathode of the fourth diode (D4) is also connected with the RCD circuit.

2. The high-gain DC-DC converter of claim 1, wherein: The RCD circuit comprises a fifth capacitor (C o ), a fifth diode (D o ), a resistor (R), wherein, The negative electrode of the fifth capacitor (C o ) is connected with the anode of the fifth diode (D o ), one end of the resistor (R), and the negative electrode of the output voltage (V o ), and the positive electrode of the fifth capacitor (C o ) is connected with the positive electrode of the third capacitor (C3) and the cathode of the fourth diode (D4); the cathode of the fifth diode (D o ) is connected with the anode of the first diode (D1) and the negative electrode of the first capacitor (C1), and the anode of the fifth diode (D o ) is also connected with one end of the resistor (R) and the negative electrode of the output voltage (V o ). One end of the resistor (R) is also connected to the negative pole of the output voltage (V o ), and the other end of the resistor (R) is respectively connected to the positive pole of the third capacitor (C3), the cathode of the fourth diode (D4), and the positive pole of the output voltage (V o ).

3. The high-gain DC-DC converter of claim 1 or 2, characterized in that: The first power switch tube (S1) and the second power switch tube (S2) are power MOSFET tubes or IGBT tubes.

4. The high-gain DC-DC converter of claim 2, wherein: The first diode (D1), the second diode (D2), the third diode (D3), the fourth diode (D4), the fifth diode (D o ) are power diodes.

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