Novel high-gain DC-DC converter based on photovoltaic panel and DC bus

Abstract

The invention provides a novel high-gain DC-DC converter based on a photovoltaic panel and a DC bus, and relates to the technical field of power electronics and control thereof. Comprising an input stage of a conventional SEPIC converter; the boosting unit is composed of an impedance network and a switched capacitor network, the impedance network comprises external inductors connected in series and capacitors and diodes connected in series with the external inductors, and the impedance characteristic of the input side is adjusted through the combination of the capacitors, the diodes and the inductors; the switched capacitor network comprises a capacitor and a diode which are connected in series, and charge transfer and voltage multiplication are achieved through charging and discharging of the capacitor and unilateral conductivity of the diode. The load unit realizes voltage conversion and stable output through the synergistic effect of an impedance network and a switched capacitor network in the boost unit.

Description

Technical Field

[0001] The present invention relates to the field of power electronics and control technology, and in particular to a novel high-gain DC-DC converter based on a photovoltaic panel and a DC bus. Background Art

[0002] In recent years, the global energy system has been rapidly transitioning toward a low-carbon, clean energy future. Traditional fossil fuels face depletion risks and environmental pressures, making renewable energy, represented by solar photovoltaics, a key driver of energy mix optimization. However, the output voltage of photovoltaic modules is typically low, unable to directly meet the requirements of high-voltage DC systems or inverter inputs. This necessitates the use of efficient, high-gain DC-DC converters to boost voltage, posing a key challenge in power electronics.

[0003] Existing technologies require boosting low voltages to hundreds or even thousands of volts. Therefore, research on high-gain DC-DC converters focuses on the following areas: 1. Multi-stage boost converters employ a cascade topology to cascade multiple boosts to increase gain; 2. Inductor-capacitor (LC) network enhancement topology integration, introducing coupled inductor and capacitor networks; 3. Switched capacitor converters, which utilize capacitor charging and discharging to achieve high-gain conversion, such as voltage doubling circuits; and 4. Hybrid high-gain DC-DC converters, which combine switched capacitors and coupled inductors to further increase gain and reduce switching losses. Existing high-gain DC-DC converter technology mainly develops around multi-stage boost, LC network enhancement, switched capacitors, and hybrid topologies, but has the following shortcomings: limited voltage gain: The gain of traditional non-isolated topologies such as SEPIC is limited by the duty cycle, making it difficult to meet high boost requirements; high device stress: In multi-stage cascade or coupled inductor topologies, the voltage stress on power devices (such as switches and diodes) is close to the output voltage, resulting in increased losses and higher device costs; ripple and efficiency issues: large input current ripple affects the maximum power point tracking (MPPT) efficiency of photovoltaic panels, and complex topologies may introduce additional losses.

[0004] To address the shortcomings of current technical methods, the present invention proposes a cascaded high-gain DC-DC converter based on the SEPIC topology, which cascades a traditional SEPIC converter with a switched capacitor converter to achieve a higher voltage gain. At the same time, the adopted topology structure reduces the ripple in the circuit and reduces the voltage stress of semiconductor devices and back-end capacitors. Summary of the Invention

[0005] The main purpose of the present invention is to provide a novel high-gain DC-DC converter based on a photovoltaic panel and a DC bus, so as to solve at least one technical problem involved in the above prior art.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is: a new high-gain DC-DC converter based on a photovoltaic panel and a DC bus, comprising: a SEPIC input unit and a boost unit connected to the outside of the SEPIC input unit, the boost unit being connected to a load unit; The SEPIC input unit includes the input stage of the traditional SEPIC converter, wherein: the positive pole of the PV module is connected to one end of the inductor L1, and the other end of the inductor L1 is connected to the power switch tube The drain of the PV module is connected to one end of the capacitor CS, and the capacitor CS is connected in series with the inductor L2; the negative electrode of the PV module is connected to the power switch tube The source and the other end of inductor L2; The boost unit consists of an impedance network and a switched capacitor network. The impedance network includes an external inductor (L3-L5) connected in series with capacitors (C1-C6) and diodes (D1-D3). The combination of capacitors, diodes, and inductors adjusts the input impedance characteristics. The switched capacitor network includes capacitors (C7-C9) and diodes (D4-D6) connected in series. It utilizes the charging and discharging of capacitors and the unidirectional conductivity of diodes to achieve charge transfer and voltage multiplication. The load unit realizes voltage conversion and stable output through the coordinated action of the impedance network and the switched capacitor network in the boost unit.

[0007] In the preferred solution, the impedance network is: three "capacitor + diode" series branches are connected in parallel, and then connected to three "capacitor + inductor" parallel units respectively, forming a network structure that can adjust the input impedance and assist voltage conversion. Specifically: Three series branches, namely, C1 and D1 in series, C2 and D3 in series, and C3 and D4 in series; After the three series branches are connected in parallel, one end is connected to the positive input of the circuit, and the other end is connected to one end of the inductors L3, L4, and L5, that is, C4 is connected in parallel with L3, C5 is connected in parallel with L4, and C6 is connected in parallel with L5. The other ends of L3, L4, and L5 are connected to the switched capacitor network part together.

[0008] In the preferred solution, the connection relationship of components in the switched capacitor network is: D4 and C7 are connected in series and then in parallel with C8; After D5 and C9 are connected in series, they are cross-connected with the circuit composed of D4, C7, and C8. D6 is connected between related nodes to realize the functions of charge transfer and voltage multiplication, and cooperate to complete the capacitor charging and discharging and voltage regulation in high-gain conversion.

[0009] In the preferred embodiment, in the switched capacitor network, one end of C8 is connected to the cathode of D4 and one end of C7; the anode of D4 is connected to the other end of C7, and forms a node with the anode of D5 and one end of C9; D6 is connected in series between D5 and C9, and the anode of D5 and the cathode of D6 are connected to the other end of C8.

[0010] In a preferred embodiment, the converter operates in continuous conduction mode (CCM) and discontinuous conduction mode (DCM). Specifically, when the converter operates in boundary conduction mode (BCM), a specific relationship exists between the duration of the inductor current and the switching period, and a normalized proportionality coefficient can be obtained. The proportionality coefficient is used to determine whether the converter operates in continuous conduction mode or discontinuous conduction mode. at this time equal , the normalized ,when When the converter works , otherwise it is in Next, the formula is: (12); Where, is the normalization coefficient, is the duty cycle.

[0011] In the preferred solution, when the converter operates in CCM, it has two operating modes: Mode 1 :when When the switch Conductivity, diode Shutdown, In this mode, Discharge, while Charging; in mode 1, the circuit is obtained by KVL: (1); Where: Inductance The voltages are ;capacitance and The voltages are and ; Mode 2 : Moment, switch at this time Disconnect, diode conduction, Disconnect; in this mode, Charging, while Discharge; applying KVL we get: (2); In formula (2), the capacitor The voltage is .

[0012] In the preferred embodiment, in continuous conduction mode CCM, Perform volt-second balance analysis and deduce the voltage gain from the above equations (1) and (2). The formulas are: (3); Where: represents the voltage gain ratio; Indicates duty cycle; 、 Represent the input and output voltages respectively.

[0013] In the preferred solution, when the converter operates in DCM, the operation process is divided into three stages. The first two stages are similar to the first two modes in continuous conduction mode. In the third stage, the power switch is turned off, the inductor energy is released, and the inductor current linearly decays to zero.

[0014] In the preferred solution, by analyzing the equivalent circuit diagrams under different modes: the output current can be obtained and the average current of the six diodes ( ) is: (4); Where: diode The average current is ; is the output current, Available The peak current is: (5); Where: yes The peak current of any diode in is the duty cycle, the inductor The total current is , the calculation process is as follows: (6); Where: It is an inductor The current size ( ), the inductance is ( ), It can be expressed as: (7); From equations (5), (6), and (7), we can conclude that: (8); Where: is the load resistance, is the proportionality coefficient, is the switching frequency ( ); From formula (8), we can get: (9); Applying the volt-second balance rule to the five inductors yields: (10); Solving equation (10), we can get: (11); Where: yes Voltage gain under is the duty cycle, is the output voltage, is the input voltage, is the proportionality coefficient.

[0015] The present invention provides a novel high-gain DC-DC converter based on a photovoltaic panel and a DC bus, comprising a SEPIC input unit and a boost unit connected to the outside of the SEPIC input unit, wherein the boost unit is connected to a load unit; wherein the SEPIC input unit comprises an input stage of a traditional SEPIC converter, wherein: the positive electrode of the PV module is connected to one end of an inductor L1, and the other end of the inductor L1 is connected to a power switch tube The drain of the PV module is connected to one end of the capacitor CS, and the capacitor CS is connected in series with the inductor L2; the negative electrode of the PV module is connected to the power switch tube The source of the boost unit and the other end of the inductor L2; the boost unit is composed of an impedance network and a switched capacitor network: the impedance network includes an external inductor (L3-L5) connected in series with capacitors (C1-C6) and diodes (D1-D3) connected in series with it. The input side impedance characteristics are adjusted by the combination of capacitors, diodes and inductors; the switched capacitor network includes capacitors (C7-C9) and diodes (D4-D6) connected in series, and uses the charging and discharging of capacitors and the unidirectional conductivity of diodes to achieve charge transfer and voltage multiplication; the load unit achieves voltage conversion and stable output through the coordinated action of the impedance network and the switched capacitor network in the boost unit.

[0016] The technical effects are as follows: 1) The combination of the external impedance network and the switched capacitor network greatly improves the internal converter voltage gain.

[0017] 2) The voltage stress of the entire semiconductor device is much lower than half of the output voltage value, which reduces device loss and improves efficiency.

[0018] 3) Improved applicability, using only a single switch for control, making it easy to design a drive circuit; based on the nestable external boost structure, the internal converter can be selected according to actual application requirements, which has high flexibility and practical value.

[0019] 4) The increase in the number of converter devices used is mainly concentrated in capacitors and switching devices. From the power loss analysis, the capacitor loss accounts for a relatively small proportion. Due to the lower voltage stress, low-voltage and low-cost devices can be selected during the converter design process, which reduces costs and improves economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will be further described below with reference to the accompanying drawings and examples: Figure 1 It is a topological structure diagram of the converter of the present invention; Figure 2 It is the main waveform diagram of the converter in one switching cycle of the present invention; Figure 3 is the equivalent circuit diagram of mode 1 of the present invention; Figure 4 is the equivalent circuit diagram of Mode 2 of the present invention; Figure 5 is the equivalent circuit diagram of mode 3 under DCM of the present invention; Figure 6 FIG. 4 is a diagram of boundary conditions between CCM and DCM operation of the converter of the present invention. DETAILED DESCRIPTION

[0021] Example 1 like Figure 1-6 As shown, a novel high-gain DC-DC converter based on a photovoltaic panel and a DC bus includes: A SEPIC input unit and a boost unit connected to the outside of the SEPIC input unit, wherein the boost unit is connected to a load unit.

[0022] The SEPIC input unit includes the input stage of the traditional SEPIC converter, wherein: the positive pole of the PV module is connected to one end of the inductor L1, and the other end of the inductor L1 is connected to the power switch tube The drain of the PV module is connected to one end of the capacitor CS, and the capacitor CS is connected in series with the inductor L2; the negative electrode of the PV module is connected to the power switch tube the source and the other end of inductor L2.

[0023] The boost unit consists of an impedance network and a switched capacitor network. The impedance network includes an external inductor (L3-L5) connected in series with capacitors (C1-C6) and diodes (D1-D3). The combination of capacitors, diodes, and inductors adjusts the input-side impedance characteristics. The switched capacitor network includes capacitors (C7-C9) and diodes (D4-D6) connected in series. It uses the charging and discharging of capacitors and the unidirectional conductivity of diodes to achieve charge transfer and voltage multiplication.

[0024] The load unit realizes voltage conversion and stable output through the coordinated action of the impedance network and the switched capacitor network in the boost unit.

[0025] In the SEPIC stage of this embodiment, the component connection relationship is as follows: Input source and inductor: The positive pole of the DC input source Vin is connected to one end of the inductor L1. The other end of L1 is the key node, and the power switch and capacitor are subsequently connected.

[0026] Power switch S1: The power switch S1 is a MOSFET (including a body diode). Its drain is connected to the other end of L1 and its source is grounded (the negative pole of the circuit). Energy transfer is regulated by controlling the on and off of S1.

[0027] Capacitors and inductors: One end of capacitor CS is connected to the node where L1 and S1 drain are connected, and the other end is connected to one end of inductor L2; the other end of L2 is connected to the circuit output (connecting the switched capacitor network and the load side).

[0028] In this embodiment, Vin passes through L1 and forms a loop with S1, CS, and L2. S1 is turned on and off to control the energy storage and release of L1. CS cooperates with L2 to achieve voltage conversion and output power transmission and voltage stabilization. It is the core link of the power conversion of the entire converter and cooperates with the impedance network and switch capacitor network to achieve high-gain DC-DC conversion.

[0029] In the preferred solution, the impedance network is: three "capacitor + diode" series branches are connected in parallel, and then connected to three "capacitor + inductor" parallel units respectively, forming a network structure that can adjust the input impedance and assist voltage conversion. Specifically: There are three series branches, namely, C1 and D1 are connected in series, C2 and D3 are connected in series, and C3 and D4 are connected in series.

[0030] After the three series branches are connected in parallel, one end is connected to the positive input of the circuit, and the other end is connected to one end of the inductors L3, L4, and L5, that is, C4 is connected in parallel with L3, C5 is connected in parallel with L4, and C6 is connected in parallel with L5. The other ends of L3, L4, and L5 are connected to the switched capacitor network part together.

[0031] In the preferred solution, the connection relationship of components in the switched capacitor network is: D4 and C7 are connected in series and then in parallel with C8; After D5 and C9 are connected in series, they are cross-connected with the circuit composed of D4, C7, and C8. D6 is connected between related nodes to realize the functions of charge transfer and voltage multiplication, and cooperate to complete the capacitor charging and discharging and voltage regulation in high-gain conversion.

[0032] In the switched capacitor network, one end of C8 is connected to the cathode of D4 and one end of C7; the anode of D4 is connected to the other end of C7, and forms a node with the anode of D5 and one end of C9.

[0033] D6 is connected in series between D5 and C9, and the anode of D5 and the cathode of D6 are connected to the other end of C8.

[0034] The output of the network is connected in parallel with the output of the SEPIC circuit, acting together on the load R. The capacitor can also play a decoupling and buffering role during the switching process, reducing the output ripple.

[0035] In the preferred embodiment, the converter operates in continuous conduction mode (CCM) and discontinuous conduction mode ( ), specifically: when the converter operates in boundary conduction mode (BCM), the duration of the inductor current has a specific relationship with the switching period, and a normalized proportional coefficient can be obtained. According to the proportional coefficient, it is determined whether the converter operates in continuous conduction mode or discontinuous conduction mode. In this embodiment, It is the boundary conduction mode (Boundary Conduction Mode).

[0036] Depend on Figure 2 It can be seen that the waveform of the converter working state can be distinguished between CCM and DCM. Figure 2 (a) It can be seen that the CCM down-converter has two operating modes. The time of mode 1 is , the time of mode 2 is (1- D ) .in is the switching period, D is the duty cycle ， and are the input and output voltages, is the power switch trigger pulse amplitude. Figure 2 (b) It can be seen that there are three working modes, among which the first two working modes are similar to mode 1 and mode 2 under CCM.

[0037] Depend on Figure 2 (a) It can be seen that in CCM, the SEPIC input unit is composed of the inductor and , coupling capacitor , main switching device and diodes SEPIC is a single-ended dual-inductor buck-boost converter. Its characteristics are: it can work normally under the condition that the input voltage is greater than or less than the output voltage; the output voltage polarity is the same as the input. At this time, the inductor current It is never zero, and even the minimum value is greater than 0 within a switching cycle; the inductor current waveform is a continuous sawtooth wave; energy is continuously transferred between input and output, and the output ripple is small.

[0038] from Figure 2 (b) It can be seen that in DCM, the inductor current drops to zero in each cycle, and there is a period of zero inductor current. Compared with CCM, DCM has a more complex control strategy, but it is more efficient under light loads.

[0039] Boost unit: The impedance network consists of Series, Series, where and and and The parallel connection achieves multiple voltage boosts through the "inductor + capacitor + diode" combination structure. It is essentially a high-gain boost path that increases the output voltage.

[0040] The first boost unit: capacitor Connect a capacitor to one end On the other end, The other end is connected to the inductor One end, inductor The other end is connected to the capacitor , capacitor diode cathode, The other end is connected to the capacitor ,inductance .

[0041] Second boost unit: capacitor Connect a capacitor to one end , The other end is connected to the inductor ,diode Anode, inductor The other end is connected to the diode Anode, capacitor ,capacitance The other end is connected to the capacitor ,inductance .

[0042] The switched capacitor network (auxiliary boost) consists of Series, 、 and Through rapid switching, multiple capacitors are charged and discharged in turn, and voltage superposition is achieved at the output end.

[0043] Depend on Figure 6 It can be seen that when MCCM is equal to MDCM, it is the boundary conduction mode.

[0044] Depend on Figure 2 The working waveform of the converter can be seen. Figure 2 (a) is the waveform of the converter in continuous conduction mode.

[0045] Figure 2 (b) is the waveform of the discontinuous conduction mode of the converter.

[0046] The switching mode analysis of the converter in this embodiment is as follows.

[0047] When the converter operates in CCM, it has two operating modes: 1) Continuous Conduction Mode Analysis Mode 1 [ ]: like Figure 3 As shown, when When the switch Conductivity, diode Shutdown, In this mode, Discharge, while Charging; in mode 1, the circuit is obtained by KVL: (1); Where: Inductance The voltages are ;capacitance and The voltages are and .

[0048] Mode 2[ ]: At this moment, the equivalent circuit is as Figure 4 As shown. Disconnect, diode conduction, Disconnect. In this mode, Charging, while Discharge. Applying KVL yields: (2); In formula (2), the capacitor The voltage is .

[0049] The two working modes are controlled by the switch tube and diodes , and switch freely, specifically: Mode 1, switch Conductivity, diode Shutdown, Internal SPEIC level, voltage source To supply energy to the entire system, the current starts from the positive pole of the power supply and passes through the inductor Enter the switch after energy storage : , energy storage To the inductor Power supply, forming a parallel circuit: ; Impedance network part, conduction, Towards Provide current: ; Switch capacitor part, capacitor Discharging to the load R, the output current path is: Mode 2, switch Disconnect, diode conduction, Disconnect. Inductor The energy stored in the original cannot pass discharge, thus passing through the capacitor Transferring energy to the right: Current path: .

[0050] Impedance network discharge path: .

[0051] 2) Intermittent conduction analysis When the converter operates in The operation process can be divided into three different stages. The working methods of the first two stages are similar to The first and second modes are similar and can be seen from Figure 2 As can be seen from the converter working state waveform, mode 1 is the switch Conductivity, diode Shutdown, conduction; mode 2 is switching Disconnect, diode conduction, Disconnect. Mode 3 is switch Off, diode By controlling the switch and The turn-on and turn-off stages are divided into three stages.

[0052] The first two stages are similar to Mode 1 and Mode 2 in CCM, and the third stage switches Shutdown, and Also turned off.

[0053] exist In the third stage of the mode, the equivalent circuit of the converter is shown in the figure. In this stage, the power switch Turn off. Since the energy stored in the inductor has been released, the inductor current begins to decrease in a linear decay manner and eventually decreases to zero. The specific process is as follows: In this state, the changes of current and voltage are stagnant until the next switching cycle begins. Typical waveforms in this mode are as follows Figure 5 As shown in Figure 1, it shows the process of the inductor current gradually decreasing and finally reaching zero, and the diode is also completely turned off when the inductor current reaches zero.

[0054] This embodiment is analyzed by voltage gain as follows.

[0055] 1) In continuous conduction mode, Perform volt-second balance analysis and deduce from the above equations (1) and (2): (3); Where: Voltage gain ratio available Indicates duty cycle express; 、 Represent the input and output voltages respectively.

[0056] 2) : By analyzing the equivalent circuit diagrams in different modes: the output current ( ) and the average current of the six diodes ( ) is: (4); Where: diode The average current is ; is the output current, Available.

[0057] Depend on Figure 5 Available, The peak current is: (5); Where: yes The peak current of any diode in is the duty cycle.

[0058] inductance The total current is , the calculation process is as follows: (6); Where: It is an inductor The current size ( ), the inductance is ( ), It can be expressed as: (7); From equations (5), (6), and (7), we can conclude that: (8); Where: is the load resistance, is the proportionality coefficient, is the switching frequency ( ); From formula (8), we can get: (9); pass Figure 3-Figure 5 , applying the volt-second balance rule to the five inductors yields: (10); Solving equation (10), we can get: (11); Where: yes The voltage gain under .

[0059] For inductance The volt-second balance rule applies because, in steady-state periodic operation, the magnetic flux of an inductor must be zero net value within a cycle. This means that the time (or magnitude) of the positive voltage applied across the inductor must cancel the time (or magnitude) of the negative voltage applied, preventing core flux accumulation and magnetic saturation. Balancing has the following effects: 1. It prevents core saturation. If flux continues to accumulate in a certain direction, it will lead to core saturation, magnetic induction intensity reaching its limit, inductor failure, and circuit damage. Volt-second balance ensures that the magnetic flux returns to its initial state, thus avoiding saturation. 2. It ensures steady-state circuit operation, and the average value of the inductor current determines the average characteristics of the circuit output. Volt-second balance ensures that the inductor voltage is zero within each cycle, thereby improving output stability.

[0060] When the converter operates in The duration of the inductor current has a specific relationship with the switching period. equal , the normalized , as shown in formula (12). When the converter works , otherwise it is in Down. and The relationship curve is as follows Figure 6 Show.

[0061] (12); Where, is the normalization coefficient, is the duty cycle.

[0062] In use, the SEPIC stage in this embodiment serves as a basic power conversion unit. By controlling the on / off state of S1, it achieves energy storage (inductor energy storage) and release (supply to the load and subsequent network), completing basic DC-DC voltage conversion and ensuring efficient energy transfer. The impedance network, through its unique series-parallel topology, effectively suppresses input current ripple. The inductor's energy storage and release characteristics, combined with the capacitor's charging and discharging, stabilize the input current. The switched capacitor network's capacitor charging and discharging, combined with the diode's unidirectional conduction, enables charge transfer. During the switching cycle, the orderly charging and discharging process significantly boosts voltage. Combined with the overall architecture, this helps the converter achieve high gain, further amplifying the internal SEPIC converter's voltage gain to meet high-voltage output requirements. The impedance network, switched capacitor network, and SEPIC stage work together to increase the voltage gain by a factor of (2+2D) (where D is the duty cycle), meeting high-gain application requirements, improving load operating stability, and reducing power loss.

[0063] The above embodiments are merely preferred technical solutions of the present invention and should not be construed as limiting the present invention. The scope of protection of the present invention shall be the technical solutions set forth in the claims, including equivalent alternatives to the technical features of the technical solutions set forth in the claims. In other words, equivalent alternatives and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A novel high-gain DC-DC converter based on photovoltaic panels and DC bus, characterized in that: include: A SEPIC input unit and a boost unit connected to the outside of the SEPIC input unit, wherein the boost unit is connected to a load unit; The SEPIC input unit includes the input stage of the traditional SEPIC converter, wherein: the positive pole of the PV module is connected to one end of the inductor L1, and the other end of the inductor L1 is connected to the power switch tube The drain of the PV module is connected to one end of the capacitor CS, and the capacitor CS is connected in series with the inductor L2; the negative electrode of the PV module is connected to the power switch tube The source and the other end of inductor L2; The boost unit consists of an impedance network and a switched capacitor network. The impedance network includes an external inductor (L3-L5) connected in series with capacitors (C1-C6) and diodes (D1-D3). The combination of capacitors, diodes, and inductors adjusts the input impedance characteristics. The switched capacitor network includes capacitors (C7-C9) and diodes (D4-D6) connected in series. It utilizes the charging and discharging of capacitors and the unidirectional conductivity of diodes to achieve charge transfer and voltage multiplication. The load unit realizes voltage conversion and stable output through the coordinated action of the impedance network and the switched capacitor network in the boost unit.

2. The novel high-gain DC-DC converter based on photovoltaic panels and DC bus according to claim 1 is characterized in that: The impedance network consists of three "capacitor + diode" series branches connected in parallel, which are then connected to three "capacitor + inductor" parallel units to form a network structure that can adjust the input impedance and assist in voltage conversion. Specifically: Three series branches, namely, C1 and D1 in series, C2 and D3 in series, and C3 and D4 in series; After the three series branches are connected in parallel, one end is connected to the positive input of the circuit, and the other end is connected to one end of the inductors L3, L4, and L5, that is, C4 is connected in parallel with L3, C5 is connected in parallel with L4, and C6 is connected in parallel with L5. The other ends of L3, L4, and L5 are connected to the switched capacitor network part together.

3. The novel high-gain DC-DC converter based on photovoltaic panels and DC bus according to claim 1 is characterized in that: In the switched capacitor network, the component connection relationship is: D4 and C7 are connected in series and then in parallel with C8; After D5 and C9 are connected in series, they are cross-connected with the circuit composed of D4, C7, and C8. D6 is connected between related nodes to realize the functions of charge transfer and voltage multiplication, and cooperate to complete the capacitor charging and discharging and voltage regulation in high-gain conversion.

4. The novel high-gain DC-DC converter based on photovoltaic panels and DC bus according to claim 3 is characterized in that: In the switched capacitor network, one end of C8 is connected to the cathode of D4 and one end of C7; the anode of D4 is connected to the other end of C7, and forms a node with the anode of D5 and one end of C9; D6 is connected in series between D5 and C9, and the anode of D5 and the cathode of D6 are connected to the other end of C8.

5. The novel high-gain DC-DC converter based on photovoltaic panels and DC bus according to claim 1 is characterized in that: The converter operates in continuous conduction mode (CCM) and discontinuous conduction mode (DCM). Specifically, when the converter operates in boundary conduction mode (BCM), the duration of the inductor current has a specific relationship with the switching period, and a normalized proportionality coefficient can be obtained. Based on the proportionality coefficient, it is determined whether the converter operates in continuous conduction mode or discontinuous conduction mode. at this time equal , the normalized ,when When the converter works , otherwise it is in Next, the formula is: （12）； Where, is the normalization coefficient, is the duty cycle.

6. The novel high-gain DC-DC converter based on photovoltaic panels and DC bus according to claim 5, characterized in that: When the converter operates in CCM, it has two operating modes: Mode 1 :when When the switch Conductivity, diode Shutdown, In this mode, Discharge, while Charging; in mode 1, the circuit is obtained by KVL: (1)； Where: Inductance The voltages are ;capacitance and The voltages are and ; Mode 2 : Moment, switch at this time Disconnect, diode conduction, Disconnect; in this mode, Charging, while Discharge; applying KVL we get: (2)； In formula (2), the capacitor The voltage is .

7. The novel high-gain DC-DC converter based on photovoltaic panels and DC bus according to claim 6, characterized in that: In continuous conduction mode CCM, Perform volt-second balance analysis and deduce the voltage gain from the above equations (1) and (2). The formulas are: (3)； Where: represents the voltage gain ratio; Indicates duty cycle; 、 Represent the input and output voltages respectively.

8. The novel high-gain DC-DC converter based on photovoltaic panels and DC bus according to claim 5, characterized in that: When the converter operates in DCM, the operation process is divided into three stages. The first two stages are similar to the first two modes in continuous conduction mode. In the third stage, the power switch is turned off, the inductor energy is released, and the inductor current linearly decays to zero.

9. The novel high-gain DC-DC converter based on photovoltaic panels and DC bus according to claim 8, characterized in that: By analyzing the equivalent circuit diagrams in different modes: the output current can be obtained and the average current of the six diodes ( ) is: (4)； Where: diode The average current is ; is the output current, Available The peak current is: (5)； Where: yes The peak current of any diode in is the duty cycle, the inductor The total current is , the calculation process is as follows: (6)； Where: It is an inductor The current size ( ), the inductance is ( ), It can be expressed as: (7)； From equations (5), (6), and (7), we can conclude that: (8)； Where: is the load resistance, is the proportionality coefficient, is the switching frequency ( ); From formula (8), we can get: (9)； Applying the volt-second balance rule to the five inductors yields: (10)； Solving equation (10), we can get: (11)； Where: yes Voltage gain under is the duty cycle, is the output voltage, is the input voltage, is the proportionality coefficient.

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