New energy power generation system power converter based on novel voltage-multiplying CD unit

Abstract

The invention discloses a new energy power generation system power converter based on a novel voltage-multiplying CD unit, which relates to the technical field of power electronic converters and comprises an input source, the voltage-multiplying CD unit, a switch inductance unit, an active network unit and a load which are connected in sequence. Wherein the input source is used for configuring a power supply of initial direct-current voltage and providing initial electric energy; the voltage-multiplying CD unit is used for providing multi-scene voltage multiplication, realizing energy storage and conversion through parallel charging and series discharging, and improving voltage gain; the switch inductance unit is used for adjusting voltage gain according to different load requirements and reducing input current ripples at the same time; and the active network unit is used for changing an energy transmission path. By controlling the on-off state of the power switch tube, the connection mode of the power diode, the capacitor and the inductor in the topological structure can be changed, so that the voltage stress of the power switch tube / diode is reduced, the conduction loss of a power device is reduced, and the overall performance of the converter is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronic converters, and in particular to a power converter for a new energy power generation system based on a novel voltage doubling CD unit. Background Art

[0002] The high progress of social and market benefits is inseparable from the research of emerging science and technology. Energy is an important guarantee for the vigorous development of the science and technology industry. With the rapid growth of the global population and the continuous advancement of the industrialization process, fossil energy has become scarce, and serious problems of environmental pollution and ecological imbalance have emerged while generating energy crises. Photovoltaic power generation has attracted widespread attention due to its advantages such as clean and environmentally friendly, strong renewable capacity, and occupies a dominant position in new energy power generation. However, the electric energy generated by photovoltaic panels has the disadvantages of low power quality and poor reliability, and cannot directly meet the power requirements. If the output voltage is forcibly connected to the grid after inversion, it is easy to cause serious fluctuations in the voltage and frequency of the power supply network, bringing safety hazards and maintenance burdens. Therefore, the introduction of a suitable high-gain DC converter between the photovoltaic panel and the inverter network is currently a research hotspot in photovoltaic power generation technology and a key technical problem that needs to be solved in this field.

[0003] In the field of research on front-end power conversion of new energy power generation systems, traditional Boost converters have received close attention due to their simple structure, stable operation and low cost. However, due to the existence of device parasitic parameters, the voltage gain can only reach less than ten times, and the power switch tube / diode loss is large, which seriously reduces the overall efficiency of the converter. On the basis of traditional Boost converters, in order to obtain high-gain and high-efficiency DC converters, Chinese and foreign scholars have introduced cascade units, coupled inductor units, voltage doubler CD units, and switch inductor units and derived a variety of new optimization schemes.

[0004] The cascaded Boost converter is composed of a series of boost converters. The closer to the input port, the lower the withstand voltage of the device, and it can work stably under the conditions of small size, high power and high frequency; the closer to the output port, the higher the withstand voltage of the device; each cascade requires an additional power switch tube. Therefore, the cascade unit has problems in line transmission loss and overall economic benefits. The coupled inductor Boost converter achieves high voltage gain through magnetic coupling, which helps to alleviate the reverse recovery problem of the rectifier diode. However, the non-ideal coupling of the winding will introduce leakage inductance, which is easy to cause serious resonance and voltage spikes on the switching device. It is necessary to use a clamping structure to limit the pulse voltage of the power switch tube during transient conversion, which increases the control difficulty of actual engineering applications. The Boost converter combined with the voltage doubler CD unit and the switch inductor unit realizes energy transfer through capacitors and inductors, has strong integration capabilities, and has a flexible and changeable structure and high voltage gain. It is widely used in high-gain power conversion applications at this stage. Summary of the invention

[0005] Based on this, in view of the above technical problems, it is necessary to provide a power converter for a new energy power generation system based on a novel voltage multiplier CD unit.

[0006] The present invention provides a power converter for a new energy power generation system based on a novel voltage multiplier CD unit, including an input source, a voltage multiplier CD unit, a switched-inductor unit, an active network unit, and a load connected in sequence;

[0007] Among them, the input source is used to configure a power supply for an initial DC voltage and provide initial electrical energy;

[0008] The voltage multiplier CD unit is used to provide voltage multiplication in multiple scenarios, achieve energy storage and conversion through parallel charging and series discharging, and improve voltage gain;

[0009] The switched-inductor unit is used to adjust the voltage gain according to different load requirements and reduce the input current ripple at the same time;

[0010] The active network unit is used to change the energy transmission path, reduce the input current ripple, and broaden the voltage gain variation range at the same time;

[0011] The load is used to provide a power supply device and receive and use the boosted electrical energy.

[0012] Furthermore, the voltage multiplier CD unit includes a first voltage multiplier CD unit, a second voltage multiplier CD unit, and a third voltage multiplier CD unit connected in sequence;

[0013] Among them, the first voltage multiplier CD unit is used to connect to the input source to obtain an initial voltage signal and jointly access the active network with the switched-inductor unit;

[0014] The second voltage multiplier CD unit is used to switch different voltage multiplier branches according to the type of working mode;

[0015] The third voltage multiplier CD unit is used to connect to the load, complete the final voltage superposition and stable output, and suppress the current ripple at the same time.

[0016] Furthermore, the first voltage multiplier CD unit includes: a first inductor L1, a first capacitor C1, and a first diode VD1;

[0017] Among them, one end of the first inductor L1 is connected to the anode of the first diode VD1 and serves as the first input end of the first voltage multiplier CD unit, the other end of the first inductor L1 is connected to one end of the first capacitor C1 and serves as the second input end of the first voltage multiplier CD unit, and the other end of the first capacitor C1 is connected to the cathode of the first diode VD1 and serves as the output end of the first voltage multiplier CD unit; the input end of the first voltage multiplier CD unit is connected to the positive pole of the input source.

[0018] Further, the second voltage-doubling CD unit includes: a second capacitor C2, a third capacitor C3, a fifth diode VD5, and a sixth diode VD6;

[0019] Among them, one end of the third capacitor C3 is connected to the anode of the fifth diode VD5 and serves as the first input terminal of the second voltage-doubling CD unit. The cathode of the fifth diode VD5 is connected to one end of the second capacitor C2 and serves as the first output terminal of the second voltage-doubling CD unit. The other end of the second capacitor C2 is connected to the cathode of the sixth diode VD6 and serves as the second input terminal of the second voltage-doubling CD unit. The anode of the sixth diode VD6 is connected to the other end of the third capacitor C3 and serves as the second output terminal of the second voltage-doubling CD unit.

[0020] Further, the third voltage-doubling CD unit includes: a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, a seventh diode VD7, an eighth diode VD8, and a ninth diode VD9;

[0021] Among them, one end of the fourth capacitor C4 is connected to the anode of the eighth diode VD8 and serves as the first input terminal of the third voltage-doubling CD unit. The other end of the fourth capacitor C4 is respectively connected to the anode of the seventh diode VD7, one end of the sixth capacitor C6, and the negative electrode of the load. The cathode of the eighth diode VD8 is respectively connected to the anode of the ninth diode VD9 and one end of the fifth capacitor C5. The cathode of the ninth diode VD9 is respectively connected to the other end of the sixth capacitor C6 and the positive electrode of the load. The cathode of the seventh diode VD7 is connected to the other end of the fifth capacitor C5 and serves as the second input terminal of the third voltage-doubling CD unit.

[0022] Further, the switched-inductor unit includes: a second diode VD2, a third diode VD3, a fourth diode VD4, a second inductor L2, and a third inductor L3;

[0023] Among them, the cathode of the second diode VD2 is connected to one end of the third inductor L3 and serves as the input terminal of the switched-inductor unit. The anode of the second diode VD2 is connected to the anode of the fourth diode VD4 and one end of the second inductor L2. The cathode of the fourth diode VD4 is connected to one end of the third inductor L3 and the cathode of the third diode VD3. The anode of the third diode VD3 is connected to the other end of the second inductor L2 and serves as the output terminal of the switched-inductor unit. The input terminal of the switched-inductor unit is connected to the negative electrode of the input source.

[0024] Further, the output terminal of the first voltage-doubling CD unit is connected to the first input terminal of the second voltage-doubling CD unit. The output terminal of the switched-inductor unit is connected to the second input terminal of the second voltage-doubling CD unit. The first output terminal of the second voltage-doubling CD unit is connected to the first input terminal of the third voltage-doubling CD unit. The second output terminal of the second voltage-doubling CD unit is connected to the second input terminal of the third voltage-doubling CD unit.

[0025] Further, the active network unit includes: a first power switch tube S1 and a second power switch tube S2;

[0026] Among them, the source of the first power switch tube S1 is connected to the second input terminal of the first voltage-doubling CD unit. The drain of the first power switch tube S1 is respectively connected to the negative pole of the input source and the input terminal of the switched-inductor unit. The source of the second power switch tube S2 is respectively connected to the output terminal of the switched-inductor unit and the second input terminal of the second voltage-doubling CD unit. The drain of the second power switch tube S2 is respectively connected to the positive pole of the input source and the first input terminal of the first voltage-doubling CD unit. The first power switch tube S1, the second power switch tube S2, the first voltage-doubling CD unit, and the switched-inductor unit form an active network structure.

[0027] Further, the first power switch tube S1 and the second power switch tube S2 adopt a synchronous on-off control strategy within one cycle.

[0028] Further, when the duty ratios of the first power switch tube S1 and the second power switch tube S2 are within a preset range, the power converter includes two operating modes. The first operating mode is that both the first power switch tube S1 and the second power switch tube S2 are turned on, and the second operating mode is that both the first power switch tube S1 and the second power switch tube S2 are turned off.

[0029] The beneficial effects of the present invention are as follows:

[0030] 1. The present invention combines new topology optimization technologies such as voltage-doubling CD units, switched-inductor units, and active network units. A voltage-doubling CD unit composed of a capacitor and a diode is connected in parallel across both ends of one inductor of the input-side active network unit, and another inductor is replaced by a switched-inductor unit composed of an inductor and a diode. Two voltage-doubling CD units are added on the output side to increase the voltage gain. By controlling the on-off states of the power switch tubes, the connection modes of the power diodes, capacitors, and inductors in the topology can be changed, thereby reducing the voltage stress of the power switch tubes / diodes, which helps to reduce the conduction loss of the power devices and improve the overall performance of the power electronic converter.

[0031] 2. The present invention combines the characteristics that the input current ripple of the switched-inductor unit and the active network unit is small and the voltage pumping ability of the voltage-doubling CD unit is strong. Using the idea of energy storage and conversion realized by the parallel charging and series discharging of capacitors and inductors in the voltage-doubling CD unit and the switched-inductor unit, it has the advantages of high voltage gain, small average value of inductor current, low voltage stress of power switch tubes / diodes, flexible structure, and simple control. It can effectively match the output characteristics of small voltage and large current of new energy power generation systems such as photovoltaic cells and is suitable for the application occasions of the front-stage power conversion under this background. Description of the Drawings

[0032] The accompanying drawings described herein are used to provide a further understanding of the present invention, and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention, and do not constitute an improper limitation to the present invention. In the drawings:

[0033] Figure 1 is a circuit schematic diagram of a power converter of a new energy power generation system based on a novel voltage-doubling CD unit according to an embodiment of the present invention;

[0034] Figure 2 is an equivalent circuit diagram of a stage when both the first power switch tube S1 and the second power switch tube S2 are turned on when the duty ratio of the power converter of the new energy power generation system based on the novel voltage-doubling CD unit according to the embodiment of the present invention varies within a preset range;

[0035] Figure 3 is an equivalent circuit diagram of a stage when both the first power switch tube S1 and the second power switch tube S2 are turned off when the duty ratio of the power converter of the new energy power generation system based on the novel voltage-doubling CD unit according to the embodiment of the present invention varies within a preset range;

[0036] Figure 4 is the theoretical voltage / current waveform of key components in the power converter of the new energy power generation system based on the novel voltage-doubling CD unit according to the embodiment of the present invention;

[0037] Figure 5 is a comparison curve of the voltage gain between the power converter of the new energy power generation system based on the novel voltage-doubling CD unit according to the embodiment of the present invention and traditional boost converters (traditional Boost converters, traditional switched-inductor Boost converters, traditional switched-capacitor Boost converters);

[0038] Figure 6 is the simulation waveform of the output voltage of the power converter of the new energy power generation system based on the novel voltage-doubling CD unit according to the embodiment of the present invention.

[0039] Reference numerals in the drawings: 1. First voltage-doubling CD unit; 2. Second voltage-doubling CD unit; 3. Third voltage-doubling CD unit; 4. Switched-inductor unit; 5. Active network unit. Detailed embodiments

[0040] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0041] Please refer to Figure 1 , a power converter of a new energy power generation system based on a novel voltage-doubling CD unit is provided, including an input source connected in sequence ( Figure 1Denoted as U in the figure in ), a voltage multiplier CD unit, a switched inductor unit 4, an active network unit 5, and a load Figure 1 Denoted as R in the figure);

[0042] Among them, the input source, which is a power supply for configuring the initial DC voltage, provides initial electrical energy;

[0043] The voltage multiplier CD unit is used to provide voltage multiplication in multiple scenarios, and realizes energy storage and conversion through parallel charging and series discharging to improve the voltage gain;

[0044] The switched inductor unit is used to adjust the voltage gain according to different load requirements and reduce the input current ripple at the same time;

[0045] The active network unit is used to change the energy transmission path, and while reducing the input current ripple, broaden the voltage gain variation range;

[0046] The load is used to provide a power supply device to receive and use the boosted electrical energy.

[0047] In one embodiment, the voltage multiplier CD unit includes a first voltage multiplier CD unit 1, a second voltage multiplier CD unit 2, and a third voltage multiplier CD unit 3 connected in sequence;

[0048] Among them, the first voltage multiplier CD unit 1 is used to connect to the input source to obtain the initial voltage signal and jointly access the active network with the switched inductor unit;

[0049] The second voltage multiplier CD unit 2 is used to switch different voltage multiplier branches according to the type of working mode;

[0050] The third voltage multiplier CD unit 3 is used to connect to the load, complete the final voltage superposition and stable output, and suppress the current ripple at the same time.

[0051] In one embodiment, the first voltage multiplier CD unit 1 includes: a first inductor L1, a first capacitor C1, and a first diode VD1;

[0052] Among them, one end of the first inductor L1 is connected to the anode of the first diode VD1 and serves as the first input end of the first voltage multiplier CD unit 1, the other end of the first inductor L1 is connected to one end of the first capacitor C1 and serves as the second input end of the first voltage multiplier CD unit 1, and the other end of the first capacitor C1 is connected to the cathode of the first diode VD1 and serves as the output end of the first voltage multiplier CD unit 1; the input end of the first voltage multiplier CD unit 1 is connected to the positive pole of the input source.

[0053] In one embodiment, the second voltage multiplier CD unit 2 includes: a second capacitor C2, a third capacitor C3, a fifth diode VD5, and a sixth diode VD6;

[0054] Among them, one end of the third capacitor C3 is connected to the anode of the fifth diode VD5 and serves as the first input end of the second voltage-doubling CD unit 2. The cathode of the fifth diode VD5 is connected to one end of the second capacitor C2 and serves as the first output end of the second voltage-doubling CD unit 2. The other end of the second capacitor C2 is connected to the cathode of the sixth diode VD6 and serves as the second input end of the second voltage-doubling CD unit 2. The anode of the sixth diode VD6 is connected to the other end of the third capacitor C3 and serves as the second output end of the second voltage-doubling CD unit 2.

[0055] In one embodiment, the third voltage-doubling CD unit 3 includes: a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, a seventh diode VD7, an eighth diode VD8, and a ninth diode VD9;

[0056] Among them, one end of the fourth capacitor C4 is connected to the anode of the eighth diode VD8 and serves as the first input end of the third voltage-doubling CD unit 3. The other end of the fourth capacitor C4 is respectively connected to the anode of the seventh diode VD7, one end of the sixth capacitor C6, and the negative pole of the load. The cathode of the eighth diode VD8 is respectively connected to the anode of the ninth diode VD9 and one end of the fifth capacitor C5. The cathode of the ninth diode VD9 is respectively connected to the other end of the sixth capacitor C6 and the positive pole of the load. The cathode of the seventh diode VD7 is connected to the other end of the fifth capacitor C5 and serves as the second input end of the third voltage-doubling CD unit 3.

[0057] In one embodiment, the switched-inductor unit 4 includes: a second diode VD2, a third diode VD3, a fourth diode VD4, a second inductor L2, and a third inductor L3;

[0058] Among them, the cathode of the second diode VD2 is connected to one end of the third inductor L3 and serves as the input end of the switched-inductor unit 4. The anode of the second diode VD2 is connected to the anode of the fourth diode VD4 and one end of the second inductor L2. The cathode of the fourth diode VD4 is connected to one end of the third inductor L3 and the cathode of the third diode VD3. The anode of the third diode VD3 is connected to the other end of the second inductor L2 and serves as the output end of the switched-inductor unit 4. The input end of the switched-inductor unit 4 is connected to the negative pole of the input source.

[0059] In one embodiment, the output end of the first voltage-doubling CD unit 1 is connected to the first input end of the second voltage-doubling CD unit 2. The output end of the switched-inductor unit 4 is connected to the second input end of the second voltage-doubling CD unit 2. The first output end of the second voltage-doubling CD unit 2 is connected to the first input end of the third voltage-doubling CD unit 3. The second output end of the second voltage-doubling CD unit 2 is connected to the second input end of the third voltage-doubling CD unit 3.

[0060] In one embodiment, the active network unit 5 includes: a first power switch tube S1 and a second power switch tube S2;

[0061] Among them, the source of the first power switch tube S1 is connected to the second input terminal of the first voltage-doubling CD unit 1, the drain of the first power switch tube S1 is respectively connected to the negative pole of the input source and the input terminal of the switching inductor unit 4, the source of the second power switch tube S2 is respectively connected to the output terminal of the switching inductor unit 4 and the second input terminal of the second voltage-doubling CD unit 2, and the drain of the second power switch tube S2 is respectively connected to the positive pole of the input source and the first input terminal of the first voltage-doubling CD unit 1; the first power switch tube S1, the second power switch tube S2, the first voltage-doubling CD unit 1 and the switching inductor unit 4 form an active network structure.

[0062] In one embodiment, the first power switch tube S1 and the second power switch tube S2 adopt a synchronous on-off control strategy within one cycle.

[0063] In one embodiment, when the duty cycles of the first power switch tube S1 and the second power switch tube S2 are within a preset range, the power converter includes two operating modes. The first operating mode is that both the first power switch tube S1 and the second power switch tube S2 are turned on, and the second operating mode is that both the first power switch tube S1 and the second power switch tube S2 are turned off.

[0064] In the description of the present invention, the first power switch tube S1 and the second power switch tube S2 adopt a synchronous on-off control strategy within one cycle. Among them, the synchronous on-off control strategy means that the on-time and off-time of the first power switch tube S1 and the second power switch tube S2 are the same. When the duty cycles of the first power switch tube S1 and the second power switch tube S2 are within a preset range (in the present invention, the preset duty cycle range is set to 0.1 - 0.9), the DC converter has two operating modes. The first operating mode is that both the first power switch tube S1 and the second power switch tube S2 are turned on, and the second operating mode is that both the first power switch tube S1 and the second power switch tube S2 are turned off.

[0065] Specifically, when the DC converter is in the first operating mode, that is, the stage when both the first power switch tube S1 and the second power switch tube S2 are turned on, the equivalent circuit is as Figure 2 shown. At this time, the first diode VD1, the second diode VD2, the third diode VD3, the seventh diode VD7, and the eighth diode VD8 are all turned on, and the fourth diode VD4, the fifth diode VD5, the sixth diode VD6, and the ninth diode VD9 are all turned off; the first inductor L1 and the first capacitor C1 are charged by the input source U through the first diode VD1 and the first power switch tube S1 in ; the second inductor L2 and the third inductor L3 are charged by the input source U through the second diode VD2, the third diode VD3, and the second power switch tube S2 in ; the input source U inThe second capacitor C2 and the third capacitor C3 supply energy to the first capacitor C1, the fourth capacitor C4, and the fifth capacitor C5 through the first power switch S1, the second power switch S2, the seventh diode VD7, and the eighth diode VD8; the sixth capacitor C6 supplies energy to the load R.

[0066] When the DC converter is in the second operating mode, that is, the stage where both the first power switch S1 and the second power switch S2 are turned off, the equivalent circuit is as Figure 3 shown. At this time, the fourth diode VD4, the fifth diode VD5, the sixth diode VD6, and the ninth diode VD9 are all conducting, and the first diode VD1, the second diode VD2, the third diode VD3, the seventh diode VD7, and the eighth diode VD8 are all turned off; the input source U in , the first inductor L1, the second inductor L2, the third inductor L3, and the first capacitor C1 supply energy to the second capacitor C2 and the third capacitor C3 through the fourth diode VD4, the fifth diode VD5, and the sixth diode VD6; the input source U in , the first inductor L1, the second inductor L2, the third inductor L3, the first capacitor C1, the fourth capacitor C4, and the fifth capacitor C5 supply energy to the second capacitor C2, the third capacitor C3, the sixth capacitor C6, and the load R through the fourth diode VD4 and the ninth diode VD9.

[0067] In a specific embodiment, it is assumed that the time intervals of the two operating modes of the DC converter within a switching period Ts are denoted as T1 and T2 in sequence, the voltage across the first inductor L1 is U L1 , the voltage across the second inductor L2 is U L2 , the voltage across the third inductor L3 is U L3 , the voltage across the first capacitor C1 is U C1 , the voltage across the second capacitor C2 is U C2 , the voltage across the third capacitor C3 is U C3 , the voltage across the fourth capacitor C4 is U C4 , the voltage across the fifth capacitor C5 is U C5 , the voltage across the sixth capacitor C6 is U C6 , the input voltage is U in , and the output voltage is U out .

[0068] In the circuit operating mode, "branch (......) / / branch (......)" means that two branches are in parallel.

[0069] In a switching period, the voltage across the capacitor can be approximately kept constant, then the voltage across the sixth capacitor C6 can be expressed as:

[0070] U C6 = Uout ;

[0071] Wherein, U C6 represents the voltage across the sixth capacitor C6, and U out represents the output voltage.

[0072] When the duty cycles of the first power switch tube S1 and the second power switch tube S2 vary between 0.2 and 0.8, T1 and T2 satisfy T1 = DT s , t2 = (1 - D)T s .

[0073] (1) During the stage when both the first power switch tube S1 and the second power switch tube S2 are conducting, the input source U in , (the first diode VD1, the first capacitor C1) / / the first inductor L1, the first power switch tube S1 form a loop; the input source U in , the second power switch tube S2, (the second inductor L2, the second diode VD2) / / (the third diode VD3, the third inductor L3) form a loop; the input source U in , the second power switch tube S2, the second capacitor C2, (the fourth capacitor C4, the seventh diode VD7) / / (the eighth diode VD8, the fifth capacitor C5), the third capacitor C3, the first capacitor C1, the first power switch tube S1 form a loop; the sixth capacitor C6 and the load R form a loop.

[0074] For the first inductor L1, the second inductor L2, and the third inductor L3, the voltages across both ends satisfy:

[0075] U L1 = U L2 = U L3 = U in ;

[0076] Wherein, U L1 , U L2 , U L3 respectively represent the voltages across both ends of the first inductor L1, the second inductor L2, and the third inductor L3, and U in represents the input voltage.

[0077] For the first capacitor C1, the second capacitor C2, the third capacitor C3, the fourth capacitor C4, and the fifth capacitor C5, the voltages across both ends satisfy:

[0078]

[0079] Wherein, U C1 , U C2 , U C3 , U C4 , U C5They respectively represent the voltages across the first capacitor C1, the second capacitor C2, the third capacitor C3, the fourth capacitor C4, and the fifth capacitor C5.

[0080] (2) During the stage when both the first power switch S1 and the second power switch S2 are turned off, the input source U in , the first inductor L1, the first capacitor C1, (the fifth diode VD5, the second capacitor C2) / / (the third capacitor C3, the sixth diode VD6), the second inductor L2, the fourth diode VD4, and the third inductor L3 form a loop; the input source U in , the first inductor L1, the first capacitor C1, the third capacitor C3, the fifth capacitor C5, the ninth diode VD9, the sixth capacitor C6 / / the load R, the fourth capacitor C4, the second capacitor C2, the second inductor L2, the fourth diode VD4, and the third inductor L3 form a loop.

[0081] For the first inductor L1, the second inductor L2, and the third inductor L3, the voltages across both ends satisfy:

[0082]

[0083] For the second capacitor C2, the third capacitor C3, the fourth capacitor C4, and the fifth capacitor C5, the voltages across both ends satisfy:

[0084]

[0085] In the formula, U C2 , U C3 , U C4 , U C5 respectively represent the voltages across the second capacitor C2, the third capacitor C3, the fourth capacitor C4, and the fifth capacitor C5, and U out represents the output voltage.

[0086] By establishing the inductor volt-second balance equations for the first inductor L1, the second inductor L2, and the third inductor L3, we get:

[0087]

[0088] In the formula, T s represents a switching period, and D represents the duty cycle.

[0089] The voltage gain of this converter when the duty cycles of the first power switch S1 and the second power switch S2 vary between 0.2 and 0.8 can be expressed as:

[0090]

[0091] In the formula, G represents the voltage gain.

[0092] For the first capacitor C1, the second capacitor C2, the third capacitor C3, the fourth capacitor C4, and the fifth capacitor C5, the voltage across both ends can be expressed as:

[0093]

[0094] In the formula, U C1 , U C2 , U C3 , U C4 , U C5 respectively represent the voltages across both ends of the first capacitor C1, the second capacitor C2, the third capacitor C3, the fourth capacitor C4, and the fifth capacitor C5.

[0095] For the fifth diode VD5, the sixth diode VD6, the seventh diode VD7, the eighth diode VD8, and the ninth diode VD9, the maximum voltage stress across both ends can be expressed as

[0096]

[0097] In the formula, U VD5 , U VD6 , U VD7 , U VD8 , U VD9 respectively represent the voltages across both ends of the fifth diode VD5, the sixth diode VD6, the seventh diode VD7, the eighth diode VD8, and the ninth diode VD9.

[0098] As Figure 4 shown, I L represents the current waveforms flowing through the first inductor L1, the second inductor L2, and the third inductor L3 in a switching cycle, and U C represents the voltage waveforms across both ends of the first capacitor C1, the second capacitor C2, the third capacitor C3, the fourth capacitor C4, the fifth capacitor C5, and the sixth capacitor C6 in a switching cycle, and U VD5(6)(9) represents the voltage waveforms across both ends of the fifth diode VD5, the sixth diode VD6, and the ninth diode VD9 in a switching cycle, and U VD7(8) represents the voltage waveforms across both ends of the seventh diode VD7 and the eighth diode VD8 in a switching cycle; the above waveforms correspond to the voltage and current analysis formulas of each device in the specific implementation manner.

[0099] The comparison curves of the present invention and traditional boost converters (traditional Boost converters, traditional switched-inductor Boost converters, traditional switched-capacitor Boost converters) in terms of voltage gain are as Figure 5As shown in the figure. When the duty cycle D varies between 0.2 and 0.8, compared with the traditional Boost converter, the traditional switched-inductor Boost converter, and the traditional switched-capacitor Boost converter, the voltage gain of the DC converter proposed by the present invention has significant advantages. When the duty cycle D is 0.5, the voltage gain G can reach 15 times; when the duty cycle D is 0.7, the voltage gain G can reach more than 25 times.

[0100] The output voltage simulation waveform of the power converter of the new energy power generation system based on the novel voltage-doubling CD cell of the present invention is as Figure 6 shown. When the input voltage is 12V and the duty cycles of the first power switch tube S1 and the second power switch tube S2 are both set to 0.6, the output voltage can be maintained near 230V, which is basically consistent with the theoretical calculation value; it shows that the present invention has the advantages of strong voltage pumping ability and wide voltage gain variation range, can effectively match the output characteristics of small voltage and large current of new energy power generation systems such as photovoltaic cells, and is suitable for the front-stage power conversion application occasions under this background.

[0101] In summary, by means of the above technical solutions of the present invention, the present invention combines novel topology optimization technologies such as voltage-doubling CD cells, switched-inductor cells, and active network cells. A voltage-doubling CD cell composed of a capacitor and a diode is connected in parallel across both ends of an inductor of the active network cell on the input side, and another inductor is replaced by a switched-inductor cell composed of an inductor and a diode. Two voltage-doubling CD cells are added on the output side to increase the voltage gain; by controlling the on-off states of the power switch tubes, the connection modes of the power diodes, capacitors, and inductors in the topology structure can be changed, thereby reducing the voltage stress of the power switch tubes / diodes, which helps to reduce the conduction loss of the power devices and improve the overall performance of the power electronic converter. The present invention combines the characteristics of small input current ripple of the switched-inductor cell and the active network cell and the strong voltage pumping ability of the voltage-doubling CD cell, and utilizes the idea of parallel charging and series discharging of capacitors and inductors in the voltage-doubling CD cell and the switched-inductor cell to realize energy storage and conversion. It has the advantages of high voltage gain, small average value of inductor current, low voltage stress of power switch tubes / diodes, flexible structure, and simple control, and can effectively match the output characteristics of small voltage and large current of new energy power generation systems such as photovoltaic cells, and is suitable for the front-stage power conversion application occasions under this background.

[0102] It should be understood that although the steps in the flowchart of the accompanying drawings are shown sequentially according to the indication of the arrows, these steps are not necessarily executed sequentially in the order indicated by the arrows. Unless there is a clear indication in this document, there is no strict order restriction for the execution of these steps, and they can be executed in other orders. Moreover, at least a part of the steps in the flowchart of the accompanying drawings may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but can be executed at different times, and their execution order is not necessarily sequential, but can be executed alternately or in turn with at least a part of other steps or sub-steps or stages of other steps.

Claims

1. A power converter for a new energy power generation system based on a novel voltage multiplier CD unit, characterized in that It includes an input source, a voltage - doubler CD unit, a switched - inductor unit, an active - network unit, and a load connected in sequence; Among them, the input source is a power supply for configuring an initial DC voltage, providing initial electrical energy; The voltage - doubler CD unit is used to provide voltage multiplication in multiple scenarios, achieving energy storage and conversion through parallel charging and series discharging, and enhancing voltage gain; The switched - inductor unit is used to adjust the voltage gain according to different load requirements while reducing the input current ripple; The active - network unit is used to change the energy transfer path, while reducing the input current ripple, broadening the voltage - gain variation range; The load is used to provide a power - supply device, receiving the boosted electrical energy for use.

2. The power converter of the new energy power generation system based on the novel voltage-doubling CD unit according to claim 1, wherein The voltage - doubler CD unit includes a first voltage - doubler CD unit, a second voltage - doubler CD unit, and a third voltage - doubler CD unit connected in sequence; Among them, the first voltage - doubler CD unit is used to connect to the input source to obtain an initial voltage signal and jointly access the active network with the switched - inductor unit; The second voltage - doubler CD unit is used to switch different voltage - doubling branches according to the type of working mode; The third voltage - doubler CD unit is used to connect to the load, complete the final voltage superposition and stable output, while suppressing the current ripple.

3. The power converter of the new energy power generation system based on the novel voltage multiplier CD unit according to claim 2, characterized in that, The first voltage - doubler CD unit includes: a first inductor L1, a first capacitor C1, and a first diode VD1; Among them, one end of the first inductor L1 is connected to the anode of the first diode VD1 and serves as the first input terminal of the first voltage - doubler CD unit, the other end of the first inductor L1 is connected to one end of the first capacitor C1 and serves as the second input terminal of the first voltage - doubler CD unit, the other end of the first capacitor C1 is connected to the cathode of the first diode VD1 and serves as the output terminal of the first voltage - doubler CD unit; the input terminal of the first voltage - doubler CD unit is connected to the positive pole of the input source.

4. The power converter of the new energy power generation system based on the novel voltage-doubling CD unit according to claim 2, wherein The second voltage - doubler CD unit includes: a second capacitor C2, a third capacitor C3, a fifth diode VD5, and a sixth diode VD6; Among them, one end of the third capacitor C3 is connected to the anode of the fifth diode VD5 and serves as the first input terminal of the second voltage - doubler CD unit, the cathode of the fifth diode VD5 is connected to one end of the second capacitor C2 and serves as the first output terminal of the second voltage - doubler CD unit, the other end of the second capacitor C2 is connected to the cathode of the sixth diode VD6 and serves as the second input terminal of the second voltage - doubler CD unit, the anode of the sixth diode VD6 is connected to the other end of the third capacitor C3 and serves as the second output terminal of the second voltage - doubler CD unit.

5. The power converter of the new energy power generation system based on the novel voltage multiplier CD unit according to claim 2, wherein The third voltage - doubler CD unit includes: a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, a seventh diode VD7, an eighth diode VD8, and a ninth diode VD9; One end of the fourth capacitor C4 is connected to the anode of the eighth diode VD8 and serves as the first input terminal of the third voltage-doubling CD unit. The other end of the fourth capacitor C4 is respectively connected to the anode of the seventh diode VD7, one end of the sixth capacitor C6, and the negative terminal of the load. The cathode of the eighth diode VD8 is respectively connected to the anode of the ninth diode VD9 and one end of the fifth capacitor C5. The cathode of the ninth diode VD9 is respectively connected to the other end of the sixth capacitor C6 and the positive terminal of the load. The cathode of the seventh diode VD7 is connected to the other end of the fifth capacitor C5 and serves as the second input terminal of the third voltage-doubling CD unit; The second voltage-doubling CD unit and the third voltage-doubling CD unit are located on the output side of the DC converter. By combining with the active network unit and the switched-inductor unit, while reducing the input current ripple, the voltage gain variation range is increased.

6. The power converter of the new energy power generation system based on the novel voltage-doubling CD unit according to claim 2, characterized in that, The switched-inductor unit includes: a second diode VD2, a third diode VD3, a fourth diode VD4, a second inductor L2, and a third inductor L3; Among them, the cathode of the second diode VD2 is connected to one end of the third inductor L3 and serves as the input terminal of the switched-inductor unit. The anode of the second diode VD2 is connected to the anode of the fourth diode VD4 and one end of the second inductor L2. The cathode of the fourth diode VD4 is connected to one end of the third inductor L3 and the cathode of the third diode VD3. The anode of the third diode VD3 is connected to the other end of the second inductor L2 and serves as the output terminal of the switched-inductor unit; The input terminal of the switched-inductor unit is connected to the negative terminal of the input source.

7. The power converter of the new energy power generation system based on the novel voltage multiplier CD unit according to claim 6, characterized in that, The output terminal of the first voltage-doubling CD unit is connected to the first input terminal of the second voltage-doubling CD unit. The output terminal of the switched-inductor unit is connected to the second input terminal of the second voltage-doubling CD unit. The first output terminal of the second voltage-doubling CD unit is connected to the first input terminal of the third voltage-doubling CD unit. The second output terminal of the second voltage-doubling CD unit is connected to the second input terminal of the third voltage-doubling CD unit.

8. The power converter of the new energy power generation system based on the novel voltage-doubling CD unit according to claim 2, characterized in that The active network unit includes: a first power switch tube S1 and a second power switch tube S2; Among them, the source electrode of the first power switch tube S1 is connected to the second input terminal of the first voltage-doubling CD unit. The drain electrode of the first power switch tube S1 is respectively connected to the negative terminal of the input source and the input terminal of the switched-inductor unit. The source electrode of the second power switch tube S2 is respectively connected to the output terminal of the switched-inductor unit and the second input terminal of the second voltage-doubling CD unit. The drain electrode of the second power switch tube S2 is respectively connected to the positive terminal of the input source and the first input terminal of the first voltage-doubling CD unit; The first power switch tube S1, the second power switch tube S2, the first voltage-doubling CD unit, and the switched-inductor unit form an active network structure.

9. The power converter of the new energy power generation system based on the novel voltage multiplier CD unit according to claim 8, characterized in that, The first power switch tube S1 and the second power switch tube S2 adopt a synchronous on-off control strategy within one cycle.

10. The power converter of the new energy power generation system based on the novel voltage-doubling CD unit according to claim 9, characterized in that, When the duty cycles of the first power switch tube S1 and the second power switch tube S2 are within a preset range, the power converter includes two operating modes. The first operating mode is that both the first power switch tube S1 and the second power switch tube S2 are turned on, and the second operating mode is that both the first power switch tube S1 and the second power switch tube S2 are turned off.

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