CN113630029A - Multi-level photovoltaic inverter - Google Patents

Multi-level photovoltaic inverter Download PDF

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Publication number
CN113630029A
CN113630029A CN202110662339.8A CN202110662339A CN113630029A CN 113630029 A CN113630029 A CN 113630029A CN 202110662339 A CN202110662339 A CN 202110662339A CN 113630029 A CN113630029 A CN 113630029A
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power switch
switch tube
diode
output
winding
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袁源兰
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Shenzhen Songsheng Innovation Technology Co ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/483—Converters with outputs that each can have more than two voltages levels
    • H02M7/487—Neutral point clamped inverters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381—Dispersed generators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/493—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode the static converters being arranged for operation in parallel
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/22—The renewable source being solar energy
    • H02J2300/24—The renewable source being solar energy of photovoltaic origin
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/56—Power conversion systems, e.g. maximum power point trackers

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Inverter Devices (AREA)

Abstract

The invention provides a multi-level photovoltaic inverter which mainly comprises an inverter bridge arm, a freewheeling diode, a double-winding reverse-phase coupling split inductor and a controller. The inverter bridge arms comprise power switching tubes and power diodes, and coupling inductors are arranged among the bridge arms to avoid the direct-connection risk of the inverter bridge arms. The controller samples AC/DC voltage and current signals and adjusts input voltage and output current accordingly. And a multi-carrier interleaved modulation strategy is adopted, the inversion midpoint output voltage is five levels, and the inversion midpoint output voltage can be output in a reactive power mode. The DC-AC power converter has the unique advantages of multiple levels, high efficiency, high reliability, capability of outputting reactive power and the like, and can be widely applied to various unidirectional and bidirectional DC-AC power converters.

Description

Multi-level photovoltaic inverter
Technical Field
The invention relates to the technical field of photovoltaics, in particular to a multi-level photovoltaic inverter.
Background
The photovoltaic modules or the photovoltaic string output direct current which changes randomly, and the inverter converts the direct current into alternating current with the same frequency and phase as the alternating current network. The direct-current voltage of the photovoltaic module is inversely proportional to the ambient temperature, and the direct-current input voltage is low in a high-temperature environment, so that a direct-current-direct-current conversion circuit (DC/DC) can be added, and a Boost circuit (Boost) is generally used to form a two-stage three-phase inverter as shown in fig. 1. When the direct current input voltage is higher than the alternating current output voltage peak value, the booster circuit does not work, the direct current input directly enters the inverter circuit through Lb and Db or a bypass diode additionally, namely the voltages at two ends of Cin and Cb are equal, the DC/AC circuit realizes inversion alternating current output, and Maximum Power Point Tracking (MPPT) is realized by the DC/AC circuit; when the direct current input voltage is lower than the alternating current output voltage peak value, the booster circuit works to enable the voltage at two ends of Cb to be higher than the alternating current output voltage peak value, the DC/AC inverter circuit realizes alternating current output, MPPT tracking is realized by the DC/DC booster circuit, and a plurality of booster circuits can be used to form multi-path MPPT.
The three-phase inverter circuit generally uses a traditional two-level inverter topology, needs to use a high voltage-resistant power switch device and has high power loss, so that the system conversion efficiency is reduced, the output filter inductor is large in size, the conversion efficiency is further reduced, the cost is increased, and the output electric energy quality is poor. In recent years, multilevel topologies have become increasingly used, and low voltage-tolerant power switching tubes can be used to reduce losses, while reducing inductor size and improving power quality. The circuit structure of the diode clamping or neutral point grounding type three-level topology (I3) is simpler, but the number of power switching tubes is larger, the system control becomes more complicated, and meanwhile, the clamping diode increases the total loss and reduces the conversion efficiency. Two power switch tubes are added to a bidirectional switch neutral point grounding three-level topology to form a transverse bridge arm, so that a control strategy is complex. In order to improve bridge arm through risks in I3 and T3 topologies, a dual buck three-level topology (a three-level dual buck half-bridge inverter, vol 24 No. 2 in 2009) and an in-phase coupling inductor form (a coupling inductor three-level dual buck inverter, vol 23 No. 11 in 2008) thereof have been proposed in recent years, and more power devices are added to the dual buck three-level topology, but the output voltage of an inversion midpoint is still only three levels. The improved (A New Single-Phase pi-Type 5-Level Inverter Using 3-Terminal Switch-Network, IEEE industry electronics 2016 volume 63, Phase 11) inversion midpoint output voltage is five levels, but the adopted control strategy is too complex and cannot output reactive power.
In general more levels modes such as five levels, seven levels and the like, the higher level of the output midpoint voltage can reduce the power loss of the switching device, but the power devices are increased in a geometric series manner, and the control of the power devices is more complicated, so that the photovoltaic inverter, the frequency converter, the uninterruptible power supply and the like only use a three-level topology. In addition, some high-efficiency multi-level topological structures proposed in recent years are all European and American national patents, and a serious technical barrier is created for popularization and application of domestic new energy power generation. In order to improve many defects of the prior art and further improve the performance and reliability of a photovoltaic power generation system, a novel bridge-arm-free direct and higher-level photovoltaic inverter with fewer power devices has become one of the research focuses in the field of new energy power electronics.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a multilevel photovoltaic inverter, wherein coupling inductors are arranged between inverter bridge arms to avoid the direct-connection risk of the inverter bridge arms, a controller samples alternating current and direct current voltage and current signals to correspondingly adjust input voltage and output current, a multi-carrier interleaved modulation strategy is adopted, the output voltage of an inverter midpoint is five levels and can be output in a reactive power mode, and the multilevel photovoltaic inverter has the unique advantages of multilevel, high efficiency, high reliability, capability of reactive power output and the like, and can be widely applied to various unidirectional and bidirectional direct current-alternating current power converters.
The invention provides a multi-level photovoltaic inverter, which comprises an inverter bridge arm, a fly-wheel diode, a double-winding reverse-phase coupling split inductor, an output filter capacitor, a controller, a direct-current bus voltage-dividing capacitor and a plurality of direct-current converters, the output filter capacitor is connected in parallel with the two ends of the alternating current output or the public power grid, the output filter capacitor is connected with the double-winding reverse-phase coupling split inductor, the double-winding reverse-phase coupling split inductor and the freewheeling diode are connected with the inverter bridge arm, the direct current bus voltage-dividing capacitor is connected with the inverter bridge arm in parallel, the inverter bridge arm and the direct current bus voltage-dividing capacitor are connected with the direct current converter, the controller detects and samples voltage or current signals of an alternating current side and a direct current side, and adjusts and controls direct current input voltage and alternating current output current of the photovoltaic grid-connected inverter.
Further, the inverter bridge arm comprises a power switch tube and a power diode, the power switch tube is connected with the power diode, and the power switch tube is connected with the double-winding reverse-phase coupling split inductor, the freewheeling diode and the direct current converter.
Further, the controller comprises a direct current bus voltage sampling module, an alternating current output voltage sampling module, a double-winding reverse-phase coupling split inductive current sampling module, a sine wave modulation module, a voltage compensator, a current compensator, a phase-locked loop module and an alternating current peak value calculation module, wherein the direct current bus voltage sampling module detects and samples direct current bus voltage, the alternating current output voltage sampling module detects and samples alternating current output amplitude value and then is connected to the phase-locked loop module and the input end of the alternating current peak value calculation module, the double-winding reverse-phase coupling split inductive current sampling module detects and samples alternating current output filter inductive current amplitude value, the sine wave modulation module is used for generating driving signals of each power switching tube, the voltage compensator adjusts the direct current bus voltage amplitude value based on a voltage reference signal, and the phase-locked loop module generates alternating current frequency and phase signals, and the current compensator controls the double-winding reverse-phase coupling split inductance current waveform to change along with the change of alternating current output, the alternating current peak value calculation module is used for calculating the size of the alternating current output or the voltage peak value of a public power grid, and the alternating current peak value calculation module is multiplied by the output signal of the phase-locked loop module and then divided by the output signal of the direct current bus voltage sampling module to be used as a feedforward signal output by the current compensator to limit the output power.
The controller further comprises a first adder, a second adder, a third adder, a first multiplier, a second multiplier and a divider, wherein the DC bus voltage sampling module detects the amplitude of the sampled DC input voltage and then is connected to the negative terminal of the first adder and the input terminal of the divider, the positive terminal of the first adder is connected with a voltage reference signal, the voltage error signal at the output terminal of the first adder is connected to the input terminal of a voltage compensator, the output terminal of the voltage compensator is connected to the input terminal of the multiplier, the AC output voltage sampling module detects the amplitude of the sampled AC output and then is connected to the input terminals of the phase-locked loop module and the AC peak value calculation module, the output terminal of the phase-locked loop module is connected to the other input terminal of the first multiplier and the input terminal of the second multiplier, the current reference signal at the output terminal of the first multiplier is connected to the positive terminal of the second adder, the AC output filter inductor current sampling module detects the amplitude of the sampled double-winding reverse-phase coupling split inductor current and then is connected to the second adder The output end of the divider is connected to the other input end of the divider, the output end of the divider is connected to one positive input end of the third adder, the output end of the third adder is connected to the other positive input end of the third adder, and the output end of the third adder is connected to the input control end of the sine wave modulation module to generate driving signals of each power switching tube.
Further, the inverter bridge arm is an I-type inverter bridge arm, the I-type inverter bridge arm includes a first power switch tube, a second power switch tube, a third power switch tube, a fourth power switch tube, a body diode of the first power switch tube, a body diode of the second power switch tube, a body diode of the third power switch tube, a body diode of the fourth power switch tube, a first clamp diode, a second clamp diode, and a clamp capacitor, the dc bus voltage-dividing capacitor includes a first dc bus voltage-dividing capacitor and a second dc bus voltage-dividing capacitor, the freewheeling diode includes a first freewheeling diode and a second freewheeling diode, the positive electrode of the output of the photovoltaic module or the pre-stage dc converter is connected to the positive electrode of the first dc bus voltage-dividing capacitor, the negative electrode of the first freewheeling diode and the drain electrode of the first power switch tube, the negative electrode of the output of the photovoltaic module or the pre-stage dc converter is connected to the negative electrode of the second dc bus voltage-dividing capacitor, The anode of a second fly-wheel diode and the source of a fourth power switch tube, the cathode of a first direct-current bus voltage-dividing capacitor and the anode of a second direct-current bus voltage-dividing capacitor are grounded and connected with the anode of a first clamping diode and the cathode of a second clamping diode, the source of the first power switch tube, the drain of the second power switch tube and the cathode of the first clamping diode are connected with one end of the clamping capacitor, the source of a third power switch tube, the drain of the fourth power switch tube and the anode of the second clamping diode are connected with the other end of the clamping capacitor, the source of the second power switch tube and the cathode of the second fly-wheel diode are connected with the homonymous end of one winding of the double-winding reverse-phase coupling split inductor, the drain of the third power switch tube and the anode of the first fly-wheel diode are connected with the heteronymous end of the other winding of the double-winding reverse-phase coupling split inductor, the heteronymous end of one winding of the double-winding reverse-phase coupling split inductor and the other winding of the double-winding reverse-winding split inductor are connected with one end of an output filter capacitor and one end of an alternating-current output or a public power grid, the other end of the output filter capacitor and the other end of the alternating current output are grounded through a zero line or a neutral line.
Further, the inverter bridge arm is a T-type inverter bridge arm, the T-type inverter bridge arm includes a first power switch tube, a second power switch tube, a third power switch tube, a fourth power switch tube, a body diode of the first power switch tube, a body diode of the second power switch tube, a body diode of the third power switch tube, a body diode of the fourth power switch tube, a first clamp diode, and a second clamp diode, the dc bus voltage-dividing capacitor includes a first dc bus voltage-dividing capacitor and a second dc bus voltage-dividing capacitor, the freewheeling diode includes a first freewheeling diode and a second freewheeling diode, the positive pole of the output of the photovoltaic module or the preceding dc converter is connected to the positive pole of the first dc bus voltage-dividing capacitor, the negative pole of the output of the photovoltaic module or the preceding dc converter is connected to the negative pole of the second dc bus voltage-dividing capacitor, The anode of a second fly-wheel diode and the source of a second power switch tube, the cathode of a first direct current bus voltage-dividing capacitor and the anode of a second direct current bus voltage-dividing capacitor are grounded and connected with the anode of a first clamping diode and the cathode of a second clamping diode, the cathode of the first clamping diode is connected with the drain of a second power switch tube, the anode of the second clamping diode is connected with the source of a third power switch tube, the source of the first power switch tube, the source of the second power switch tube and the cathode of the second fly-wheel diode are connected with the homonymous end of a winding of the double-winding reverse-phase coupling split inductor, the drain of the second power switch tube, the drain of the third power switch tube and the anode of the first fly-wheel diode are connected with the heteronymous end of another winding, the heteronymous end of the winding of the double-winding reverse-phase coupling split inductor and the homonymous end of the other winding are connected with one end of an output filter capacitor and a live wire of an alternating current output or a public power grid, the other end of the output filter capacitor and the other end of the alternating current output are grounded through a zero line or a neutral line.
Further, the inverter bridge arm is an FC-type inverter bridge arm, the FC-type inverter bridge arm includes a first power switch tube, a second power switch tube, a third power switch tube, a fourth power switch tube, a body diode of the first power switch tube, a body diode of the second power switch tube, a body diode of the third power switch tube, a body diode of the fourth power switch tube, a first flying capacitor, and a second flying capacitor, the dc bus voltage-dividing capacitor includes a first dc bus voltage-dividing capacitor and a second dc bus voltage-dividing capacitor, the freewheeling diode includes a first freewheeling diode, a second freewheeling diode, a third freewheeling diode, and a fourth freewheeling diode, an anode of the output of the photovoltaic module or the preceding-stage dc converter is connected to an anode of the first dc bus voltage-dividing capacitor, a cathode of the first freewheeling diode, and a drain of the first power switch tube, a cathode of the output of the photovoltaic module or the preceding-stage dc converter is connected to a cathode of the second dc voltage-dividing capacitor, The anode of the second fly-wheel diode and the drain of the second power switch tube are connected to one end of the first flying capacitor, the anode of the third fly-wheel diode and the cathode of the second fly-wheel diode are connected to the other end of the first flying capacitor, the anode of the first fly-wheel diode and the cathode of the fourth fly-wheel diode are connected to one end of the second flying capacitor, the source of the third power switch tube and the drain of the fourth power switch tube are connected to the other end of the second flying capacitor, the source of the second power switch tube and the cathode of the third fly-wheel diode are connected to the same-name end of one winding of the double-winding reverse-phase coupling split inductor, the drain of the third power switch tube and the anode of the fourth fly-wheel diode are connected to the different-name end of the other winding, the different-name end of one winding and the same-name end of the other winding of the double-winding reverse-phase coupling split inductor are connected to one end of the output filter capacitor and the AC output or the same-name end of the public power grid The live wire is connected with the other end of the output filter capacitor, and the zero line or the neutral line of the other end of the alternating current output is grounded.
Furthermore, the inversion bridge arm adopts an HB type inversion bridge arm, the HB type inversion bridge arm comprises a first power switch tube, a second power switch tube, a body diode of the first power switch tube and a body diode of the second power switch tube, the DC bus voltage-dividing capacitor comprises a first DC bus voltage-dividing capacitor and a second DC bus voltage-dividing capacitor, the fly-wheel diode comprises a first fly-wheel diode and a second fly-wheel diode, the anode output by the photovoltaic component or the preceding DC converter is connected to the anode of the first DC bus voltage-dividing capacitor, the cathode of the first fly-wheel diode and the drain of the first power switch tube, the cathode output by the photovoltaic component or the preceding DC converter is connected to the cathode of the second DC bus voltage-dividing capacitor, the anode of the second fly-wheel diode and the source of the second power switch tube, the cathode of the first DC bus voltage-dividing capacitor and the anode of the second DC bus voltage-dividing capacitor are grounded, the source electrode of the first power switch tube and the cathode of the second freewheeling diode are connected to a winding homonymous end of the double-winding reverse-phase coupling split inductor, the drain electrode of the second power switch tube and the anode of the first freewheeling diode are connected to a winding homonymous end of the other winding, the winding heteronymous end of the double-winding reverse-phase coupling split inductor and the other winding homonymous end of the double-winding reverse-phase coupling split inductor are connected to one end of the output filter capacitor and a live wire at one end of the alternating current output or public power grid, and the other end of the output filter capacitor and the other end of the alternating current output are grounded through a zero line or a neutral line.
Further, the inverter bridge arm is a CHB-type inverter bridge arm, the CHB-type inverter bridge arm includes a first power switch tube, a second power switch tube, a third power switch tube, a fourth power switch tube, a body diode of the first power switch tube, a body diode of the second power switch tube, a body diode of the third power switch tube, and a body diode of the fourth power switch tube, the double-winding reverse-phase coupling split inductor includes a first double-winding reverse-phase coupling split inductor and a second double-winding reverse-phase coupling split inductor, the dc bus voltage-dividing capacitor includes a first dc bus voltage-dividing capacitor, a second dc bus voltage-dividing capacitor, a third dc bus voltage-dividing capacitor and a fourth dc bus voltage-dividing capacitor, the freewheeling diode includes a first freewheeling diode, a second freewheeling diode, a third freewheeling diode and a fourth freewheeling diode, and the positive electrode of the first output of the photovoltaic module or the preceding stage dc converter is connected to the positive electrode of the first dc bus voltage-dividing capacitor, A cathode of a fourth fly-wheel diode and a drain of a first power switch tube, a cathode of a first output of the photovoltaic component or the preceding direct-current converter is connected to a cathode of a second direct-current bus voltage-dividing capacitor, an anode of the first fly-wheel diode and a source of the fourth power switch tube, an anode of a second output of the photovoltaic component or the preceding direct-current converter is connected to an anode of a third direct-current bus voltage-dividing capacitor, a cathode of a third fly-wheel diode and a drain of a second power switch tube, a cathode of a second output of the photovoltaic component or the preceding direct-current converter is connected to a cathode of the fourth direct-current bus voltage-dividing capacitor, an anode of the second fly-wheel diode and a source of the third power switch tube, a source of the first power switch tube and a cathode of the first fly-wheel diode are connected to a homonymous end of one winding of the first double-winding reverse-phase coupling split inductor, a drain of the fourth power switch tube and an anode of the fourth fly-wheel diode are connected to a homonymous end of the other winding, a heteronymous end of one winding of the first double-winding reverse-phase coupling split inductor and the other winding are connected to an output filter tube One end of a wave capacitor is connected with a live wire at one end of an alternating current output or public power grid, the other end of an output filter capacitor is connected with a zero line or a neutral line at the other end of the alternating current output, the negative electrode of a third direct current bus voltage-dividing capacitor is connected with the positive electrode of a fourth direct current bus voltage-dividing capacitor, the source electrode of a second power switch tube and the cathode of a second fly-wheel diode are connected to the homonymous end of one winding of a second dual-winding reverse-phase coupling split inductor, the drain electrode of the third power switch tube and the anode of the third fly-wheel diode are connected to the homonymous end of the other winding, and the heteronymous end of one winding of the second dual-winding reverse-phase coupling split inductor and the homonymous end of the other winding of the second dual-winding reverse-phase coupling split inductor are connected to the negative electrode of the first direct current bus voltage-dividing capacitor and the positive electrode of the second direct current bus voltage-dividing capacitor.
Furthermore, the inverter bridge arm is an I-type three-phase inverter bridge arm, the I-type three-phase inverter bridge arm comprises an a-phase I-type bridge arm power switch tube, a B-phase I-type bridge arm power switch tube and a C-phase I-type bridge arm power switch tube, and the a-phase I-type bridge arm power switch tube, the B-phase I-type bridge arm power switch tube and the C-phase I-type bridge arm power switch tube are connected between the double-winding reverse-phase coupling split inductor and the direct-current bus voltage-dividing capacitor.
Compared with the prior art, the invention has the beneficial effects that:
the invention provides a multi-level photovoltaic inverter, wherein double-winding reverse-phase coupling split inductors are adopted between inverter bridge arms, and excitation inductors of the split inductors can play a role of the split inverter bridge arms to avoid direct connection risks, so that the working reliability of the inverter is improved; the inverter midpoint output voltage is five levels, so that the conversion efficiency of the inverter can be improved, the quality of alternating current output electric energy is improved, and the volume and the weight of an output filter inductor can be reduced; in a complete high-frequency switching period, the leakage inductance of the double-winding reverse-phase coupling split inductor has two charging and discharging processes, so that the ripple wave of the output filter inductor is equivalent frequency doubling switching frequency, and the volume and the weight of the output filter inductor are further reduced; the power tubes work by alternately rotating the high-frequency switches in a half power frequency period, so that the thermal stress of a power device can be reduced, and the working reliability of the inverter is further improved.
The foregoing description is only an overview of the technical solutions of the present invention, and in order to make the technical solutions of the present invention more clearly understood and to implement them in accordance with the contents of the description, the following detailed description is given with reference to the preferred embodiments of the present invention and the accompanying drawings. The detailed description of the present invention is given in detail by the following examples and the accompanying drawings.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limiting the invention. In the drawings:
fig. 1 is a schematic diagram of a two-stage three-phase inverter according to the background art of the present invention;
fig. 2 is a schematic diagram of a topological structure of a multi-path MPPT two-stage multi-level photovoltaic inverter according to the present invention;
fig. 3 is a schematic diagram of a dual-winding reverse-phase coupling split-inductor I-type multilevel photovoltaic inverter and a controller thereof according to a first embodiment of the present invention;
FIG. 4 is a schematic diagram of the main operating waveforms of the first embodiment of the present invention;
fig. 5 is a schematic diagram of a two-winding reverse-phase coupling split-inductor T-type multilevel photovoltaic inverter according to a second embodiment of the present invention;
fig. 6 is a schematic diagram of a dual-winding reverse-phase coupling split inductor flying capacitor type multilevel photovoltaic inverter according to a third embodiment of the present invention;
fig. 7 is a schematic diagram of a dual-winding reverse-phase coupling split-inductor two-level type multi-level photovoltaic inverter according to a fourth embodiment of the present invention;
fig. 8 is a schematic diagram of a dual-winding reverse-phase coupling split inductor cascaded multilevel photovoltaic inverter according to a fifth embodiment of the present invention;
fig. 9 is a schematic diagram of a two-winding reverse-phase coupling split-inductor three-phase I-type multi-level photovoltaic inverter according to a sixth embodiment of the present invention.
Detailed Description
The present invention will be further described with reference to the accompanying drawings and the detailed description, and it should be noted that any combination of the embodiments or technical features described below can be used to form a new embodiment without conflict.
As shown in fig. 2, the multi-path MPPT function is realized by a plurality of dc converters from 1 to n, where Vpv1, …, and Vpvn are output voltages of a photovoltaic module or a photovoltaic string, and Vdc is an output voltage of the dc converter, that is, an inverter dc input voltage. The photovoltaic inverter mainly comprises an inverter bridge arm, a freewheeling diode, a double-winding reverse-phase coupling split inductor, an output filter capacitor, a controller, a direct-current bus voltage-dividing capacitor and a plurality of direct-current converters, wherein Vac is an alternating-current output or public power grid, Cb1 and Cb2 are direct-current bus voltage-dividing capacitors, D3 and D4 are freewheeling diodes, Lf is a double-winding reverse-phase coupling split inductor, namely an alternating-current output filter inductor, and plays a role of a split inverter bridge arm to avoid direct connection risk, and Cf is an output filter capacitor. The output filter capacitors are connected in parallel at two ends of an alternating current output or public power grid, the output filter capacitors are connected with the double-winding reverse-phase coupling split inductor, the double-winding reverse-phase coupling split inductor and the freewheeling diode are connected with an inverter bridge arm, the direct current bus voltage-dividing capacitor is connected with the inverter bridge arm in parallel, the inverter bridge arm and the direct current bus voltage-dividing capacitor are connected with a direct current converter, the direct current converter is connected with a photovoltaic module or a photovoltaic module string output voltage, and the controller detects and samples voltage or current signals at an alternating current side and a direct current side and generates a power switch tube PWM (pulse width modulation) wave-generating signal so as to correspondingly adjust and control the direct current input voltage and the alternating current output current of the photovoltaic grid-connected inverter.
The inverter bridge arm comprises a power switch tube and a power diode, the power switch tube is connected with the power diode, and the power switch tube is connected with the double-winding reverse-phase coupling split inductor, the fly-wheel diode and the direct current converter.
In the first embodiment, as shown in fig. 3, the dual-winding reverse-phase coupling split-inductor I-type multilevel photovoltaic inverter is implemented by using an I-type inverter arm, where the I-type inverter arm includes a first power switch tube S1, a second power switch tube S2, a third power switch tube S3, a fourth power switch tube S4, a body diode Ds1 of the first power switch tube S1, a body diode Ds2 of the second power switch tube S2, a body diode Ds3 of the third power switch tube S3, a body diode Ds4 of the fourth power switch tube S4, a first clamp diode D1, and a second clamp diode D2, where the dc bus voltage-dividing capacitors include a first dc bus voltage-dividing capacitor Cb1 and a second dc bus voltage-dividing capacitor Cb2, the freewheeling diodes include a first freewheeling diode D3 and a second freewheeling diode D4, a clamping capacitor Cc is optionally used for absorbing voltage spikes across the S2, S3 turn-off transients. The positive pole of the output Vdc of the photovoltaic module or the preceding-stage direct-current converter is connected to the positive pole of a first direct-current bus voltage-dividing capacitor Cb1, the cathode of a first fly-wheel diode D4 and the drain (D) of a first power switch tube S1, the negative pole of the output Vdc of the photovoltaic module or the preceding-stage direct-current converter is connected to the negative pole of a second direct-current bus voltage-dividing capacitor Cb2, the anode of a second fly-wheel diode D3 and the source (S) of a fourth power switch tube S4, the negative poles of the first direct-current bus voltage-dividing capacitor Cb1 and the positive pole of the second direct-current bus voltage-dividing capacitor Cb2 are grounded and connected with the anode of a first clamping diode D1 and the cathode of a second clamping diode D2, the source (S) of the first power switch tube S1, the drain (D) of the second power switch tube S2 and the cathode of the first clamping diode D1 are connected to one end of the Cc, the source (S3) of the third power switch tube S4, the drain (D) and the anode of the second clamping diode D2 are connected to the other end of the clamping capacitor, the source electrode (S) of the second power switch tube S2 and the cathode electrode of the second fly-wheel diode D3 are connected to a winding homonymous end of the double-winding reverse-phase coupling split inductor Lf, the drain electrode (D) of the third power switch tube S3 and the anode electrode of the first fly-wheel diode D4 are connected to the other winding homonymous end of the double-winding reverse-phase coupling split inductor Lf, the one winding homonymous end and the other winding homonymous end of the double-winding reverse-phase coupling split inductor Lf are connected to an output filter capacitor, namely one end of an inversion output midpoint Cf and a live wire at one end of an alternating current output or public power grid, and the other end of the output filter capacitor Cf and the other end of the alternating current output are grounded through a zero line or a neutral line (N).
The controller comprises a plurality of key modules, wherein Hvb is a direct current bus voltage sampling module, Hvac is an alternating current output voltage sampling module, Hiac is an Lf current sampling module, SPWM is a sine wave modulation module, Gcv is a voltage compensator, Gci is a current compensator, PLL is a phase-locked loop module, Vacm is an alternating current peak value calculation module, Vref is a voltage reference signal, and the controller also comprises an adder 1, an adder 2, an adder 3, a multiplier 1, a multiplier 2 and a divider. The amplitude of the Hvb detection sampling Vdc is connected to the negative end of the adder 1 and one input end of the divider, the positive end of the adder 1 is connected with Vref, the voltage error signal of the output end of the adder is connected to the input end of Gcv, and the output end of Gcv is connected to one input end of the multiplier 1. Hvac detects the amplitude of sampled Vac and then connects to the input end of PLL and Vacm, the output end of PLL connects to the other input end of multiplier 1 and one input end of multiplier 2, its output end current reference signal Iref connects to the positive end of adder 2, Hiac detects the amplitude of sampled Lf current and then connects to the negative end of adder 2, its output end current error signal connects to the input end of Gci. The Vacm output terminal is connected to the other input terminal of the multiplier 2, the output terminal thereof is connected to the other input terminal of the divider, the output terminal of the divider is connected to a positive input terminal of the adder 3, the output terminal Gci is connected to the other positive input terminal of the adder 3, and the output terminal of the adder 3 is connected to the SPWM input control terminal, so as to generate the driving signals of each power switch tube. The alternating current output uses an inductance-capacitance type (LC) filter, and when the filter is used for a photovoltaic grid-connected inverter, the inductance-capacitance-inductance type (LCL) filter can also be adopted to further reduce the inductance of the output filter and the volume of the filter. Hvb detects the sampled dc bus voltage Vdc, Gcv adjusts the magnitude of the dc bus voltage based on the voltage reference signal Vref. PLL generates AC frequency and phase signals
Figure BDA0003115854250000121
And multiplied by the output signal of Gcv to generate the current reference signal Iref. Gci is a current compensator to control the Lf current waveform to follow the Vac variation. Vacm is used for calculating the size of an alternating current output or a voltage peak value of a public power grid, and the alternating current output or the voltage peak value is multiplied by a PLL output signal and then divided by an Hvb output signal to be used as a feedforward signal output by Gci, so that the output power limiting function is achieved.
The main working waveform is shown in fig. 4, a multi-carrier interleaved modulation strategy is adopted, and the working mode of the double-winding reverse-phase coupling split inductor is combined, so that the output voltage of the midpoint of the inverter is five levels. The direct current-alternating current inverter circuit can realize bidirectional flow of energy, so that the inverter has active power and reactive power output capacity, and the specific working process is described as follows:
(t 0-t 1): the alternating current output sine wave voltage is positive, the alternating current output sine wave current is also positive, and the alternating current output sine wave voltage is in an active inversion state 1: namely, when the S1, the S3 high frequency switch, the S2 are always on and the S4 is always off, two operation modes exist during this period, namely, the S1 duty cycle (D1) is greater than 0.5 or less than 0.5. When D1 is less than 0.5, S1 is on, S2 and S3 are on: the point in the Lf inversion output generates a positive middle potential with the amplitude of "+ 1/4", the Lf excitation inductance and the leakage inductance thereof are in a positive charging state, and energy is transmitted from Vdc and Cb1 to alternating current output; when S1 turns off, S2, S3 continues to turn on: the neutral point of the Lf inversion output generates zero potential to the ground, the amplitude of the zero potential is indicated as 0, the Lf excitation inductor is in a forward constant current state due to short circuit of D1 and D2 in the period, meanwhile, the D1 clamps S1 to turn off instant peak voltage, the Lf leakage inductor is in a forward discharge state, and alternating current output energy forms a follow current loop through D1, S2 and Lf; when S1 continues to be off, S2 continues to be on, and S3 is off: the mid-point of the Lf inversion output generates a positive mid-potential opposite to the ground, the amplitude of the positive mid-potential is denoted by + 1/4', the Lf excitation inductor is in a positive discharging state through D1, D4 and Cb1 in the period, meanwhile, D4 clamps S3 to turn off an instant spike voltage, the Lf leakage inductor is in a positive charging state, and energy is output from Vdc, Cb1 through D1, S2 and Lf in an alternating current mode; when S1 continues to be turned off, S2 continues to be turned on, and S3 is turned on: the point of the Lf inverter output generates zero potential with the amplitude of 0 relative to the ground, the Lf excitation inductor is in a forward constant current state due to the short circuit of D1 and D2 again in the period, the Lf leakage inductor is in a forward discharge state, and the alternating current output energy forms a freewheeling circuit through D1, S2 and Lf. In the D1>0.5 operating mode, when S1 is on, S2 is continuously on, and S3 is continuously off: the point in the Lf inversion output generates a positive high potential with the amplitude of "+ 1/2", the Lf excitation inductor is short-circuited by the D4 and is in a positive constant current state, the Lf leakage inductor is in a positive charging state, and energy is transmitted from Vdc and Cb1 to the alternating current output; when S1, S2 continue to be on and S3 is on: the neutral point of the Lf inversion output generates a positive middle potential with the amplitude of "+ 1/4", the Lf excitation inductor is in a positive charging state in the period, the Lf leakage inductor is in a positive discharging state, and the alternating current output energy forms a follow current loop through D1, S2 and Lf; when S1, S2 continue to be on and S3 is off: the point in the Lf inverting output generates a positive high potential with the amplitude of "+ 1/2", during which the Lf magnetic inductor is again short-circuited by the D4 and is in a positive constant current state, at the same time, the D4 clamps the S3 to turn off the instantaneous spike voltage, the Lf leakage inductor is in a positive charging state, and energy is transmitted from Vdc and Cb1 to the alternating current output; when S1 is turned off, S2 continues to be turned on, and S3 continues to be turned off: the neutral point of the Lf inversion output generates a positive neutral potential with the amplitude of "+ 1/4", during which the Lf excitation inductor is in a positive discharge state through D1, D4 and Cb1, meanwhile, the D1 clamps S1 turns off an instantaneous spike voltage, the Lf leakage inductor is in a positive charging state, and the alternating current output energy forms a follow current loop through D1, S2 and Lf;
(t 1-t 2): the voltage of the alternating-current output sine wave is negative, the current of the alternating-current output sine wave is positive, and the voltage is in a reactive rectification state 1: namely S2, S4 high frequency switch, S3 is always on and S1 is always off. When S2 is turned on, Vac charges the Lf energy storage through D1, which is called as a negative energy storage state; when S2 is turned off, the D3 clamps S2 to turn off the transient spike voltage, and the energy stored in Lf is free-wheeling discharged to Cb2 through D3, Vac, which is called a negative-going released state. During this period, although S3 is always on and the high frequency switch S4 is on, since no current flows due to the effect of the coupling inductance, the effect is negligible and is only used to simplify the control strategy.
(t 2-t 3): the alternating current output sine wave voltage is negative, the alternating current output sine wave current is also negative, and the state is an active inversion state 2: namely, when the S2, the S4 high frequency switch, the S3 are always on and the S1 is always off, two operation modes exist during this period, namely, the S4 duty cycle (D1) is greater than 0.5 or less than 0.5. In the working mode of D1<0.5, when S2 and S3 continue to be on and S4 is on: the midpoint of the Lf inversion output generates negative middle potential to the ground, the amplitude of the negative middle potential is indicated by '-1/4', the Lf excitation inductance and the leakage inductance thereof are in a negative charging state in the period, and energy is transmitted to the alternating current output from Vdc and Cb 2; when S2, S3 continue to be on and S4 is off: the neutral point of the Lf inversion output generates zero potential to the ground, the amplitude of the zero potential is indicated by 0, the Lf excitation inductor is in a negative constant current state due to short circuit of D1 and D2 in the period, meanwhile, the D2 clamps S4 to turn off instant peak voltage, the Lf leakage inductor is in a negative discharge state, and alternating current output energy forms a follow current loop through D2, S3 and Lf; when S2 is turned off, S3 continues to be turned on, and S4 continues to be turned off: the neutral point of the Lf inversion output generates negative neutral potential to the ground, the amplitude of the negative neutral potential is indicated by '-1/4', the Lf excitation inductor is in a negative discharging state through D2, D3 and Cb2 in the period, meanwhile, the D3 clamps S2 turns off instant peak voltage, the Lf leakage inductor is in a negative charging state, and energy is output from Vdc and Cb2 through D2, S3 and Lf; when S2 is on, S3 continues to be on, and S4 continues to be off: the point of the Lf inversion output generates zero potential to the ground, the amplitude of the zero potential is indicated as 0, the Lf excitation inductor is in a negative constant current state due to short circuit of D1 and D2 again in the period, the Lf leakage inductor is in a negative discharge state, and the alternating current output energy forms a freewheeling circuit through D2, S3 and Lf. When D1>0.5 operating mode, S2 continues to be off, S3 continues to be on, and S4 turns on: the midpoint of the Lf inversion output generates negative high potential to the ground, the amplitude of the negative high potential is indicated as-1/2', the Lf excitation inductor is in a negative constant current state due to the short circuit of D3 in the period, the Lf leakage inductor is in a negative charging state, and energy is transmitted to alternating current output from Vdc and Cb 2; when S2 turns on, S3 and S4 continue to turn on: the neutral point of the Lf inversion output generates negative neutral potential to the ground, the amplitude of the negative neutral potential is indicated by '-1/4', the Lf excitation inductor is in a negative charging state in the period, the Lf leakage inductor is in a negative discharging state, and the alternating current output energy forms a follow current loop through D2, S3 and Lf; when S2 turns off, S3, S4 continues to turn on: the neutral point of the Lf inversion output generates negative high potential to the ground, the amplitude of the negative high potential is indicated as-1/2', the Lf magnetic inductor is in a negative constant current state due to the short circuit of the D3 again in the period, meanwhile, the D3 clamps the S2 to turn off the instantaneous peak voltage, the Lf leakage inductor is in a negative charging state, and energy is transmitted to the alternating current output from Vdc and Cb 2; when S2 continues to be off, S3 continues to be on, and S4 is off: the neutral point of the Lf inversion output generates negative neutral potential to the ground, the amplitude of the negative neutral potential is indicated by '-1/4', the Lf excitation inductor is in a negative discharging state through D2, D3 and Cb2 in the period, meanwhile, the D2 clamps S4 turns off instant peak voltage, the Lf leakage inductor is in a negative charging state, and alternating current output energy forms a follow current loop through D2, S3 and Lf;
(t 3-t 4): the alternating current output sine wave voltage is positive, the alternating current output sine wave current is negative, namely, the reactive power rectification state 2: namely S1, S3 high frequency switch, S2 is always on and S4 is always off. When S3 is turned on, Vac charges the Lf energy storage through D2, which is called a forward energy storage state; when S3 is turned off, the D4 clamps S3 to turn off the transient spike voltage, and the energy stored in Lf is free-wheeling discharged to Cb1 through D4, Vac, which is called a forward release state. During this period, although the S1 high frequency switch S2 is always on, the coupling inductance acts and no current flows, so its effect is negligible and is only used to simplify the control strategy.
As can be seen from the above description, S1, S2, D1 and D3, and S3, S4, D2 and D4 respectively form two inverter bridge arms, and the two inverter bridge arms are internally connected in series only by power switching tubes and power diodes, and there is no direct series connection of the switching tubes, which is also called a bridge arm commutation no-dead-zone technique. The excitation inductor of the double-winding reverse-phase coupling split inductor Lf can avoid the through risk which may occur in S1, S2, S3 and S4, so that the working reliability of the inverter is improved. The voltages at the two ends of D3 and D4 are all input voltages Vdc, and two low-voltage diodes can be respectively connected in series. By adopting a multi-carrier interleaved modulation strategy and combining a working mode of a double-winding reverse-phase coupling split inductor, the output voltage of an inversion midpoint is five levels of +1/2, +1/4, + 0, -1/4 and-1/2, the conversion efficiency of the inverter can be improved, the quality of alternating current output electric energy is improved, and the volume and the weight of an output filter inductor can be reduced. In a complete high-frequency switching period, the leakage inductance of the double-winding reverse-phase coupling split inductor has two charging and discharging processes, so that the output filter inductor ripple is equivalent frequency doubling switching frequency, and the volume and the weight of the output filter inductor are further reduced. The power tubes work as high-frequency switches, but all work alternately in a half power frequency period, so that the thermal stress can be reduced, and the working reliability is further improved. The inverter can output reactive power in a smooth control mode, so that compensation can be flexibly provided for an alternating current power grid, and the inverter can also work in an alternating current-direct current rectification working mode through the control mode, so that the inverter and the control strategy thereof can be widely applied to various unidirectional and bidirectional direct current-alternating current power converters. In order to realize topology expansion, the full-bridge inverter can also be formed by combining one I-type five-level half bridge with another conventional type half bridge or two I-type five-level half bridges.
The power switch tube in the multilevel photovoltaic inverter can use an Insulated Gate Bipolar Transistor (IGBT), a power triode (GTR), a metal oxide field effect transistor (MOSFET) or a wide bandgap power switch tube gallium nitride (GaN), silicon carbide (SiC) and the like, and the power diode can adopt an ultrafast recovery or SiC diode and the like. When the inverter is applied to a photovoltaic power generation system, the parallel technology of a plurality of inverters, the multi-path Maximum Power Point Tracking (MPPT) technology, the staggered parallel technology, the coupling inductor structure and the like can be easily used. The controller can be built by using discrete electronic components, and can also be designed and used by using special integrated circuits, such as an analog control chip, a singlechip (MCU) programmed by software, a Digital Signal Processor (DSP) or a programmable logic device (FPGA/CPLD) and the like. The DC-AC inverter circuit and the controller can adopt a discrete semiconductor device mode or a respective integrated and mixed integrated mode, and can also be uniformly integrated into a power semiconductor to form a large-scale mixed power semiconductor integrated circuit, and the volume of the photovoltaic inverter can be further reduced by the design of the high-integration mode.
The double-winding reverse-phase coupling split inductor, namely the alternating current output filter inductor Lf, has various structural forms, including the general structures of a double-winding reverse-phase coupling transformer and an independent inductor, so that the leakage inductance of the transformer can be small in value, and the output filter function is realized by the independent inductor. The independent inductor can also be integrated into the two-winding inverse-phase coupling transformer, or the leakage inductance of the two-winding inverse-phase coupling transformer can be used as an output filter inductor, and the leakage flux path is provided by the middle magnetic column with an air gap in the magnetic core. Another coupling inductance structure is that two side columns for providing leakage magnetic flux are added outside the magnetic core. E-core structures, toroidal and hybrid cores, and ferrite, amorphous, powder core, etc. may be used.
In the second embodiment, as shown in fig. 5, the dual-winding reverse-phase coupling split-inductor T-type multi-level photovoltaic inverter includes a T-type inverter arm, where the inverter arm includes a first power switch tube S1, a second power switch tube S2, a third power switch tube S3, a fourth power switch tube S4, a body diode of the first power switch tube S1, a body diode of the second power switch tube S2, a body diode of the third power switch tube S3, a body diode of the fourth power switch tube S4, a first clamping diode D1, and a second clamping diode D2, where the dc bus voltage-dividing capacitors include a first dc bus voltage-dividing capacitor Cb1 and a second dc bus voltage-dividing capacitor Cb2, the freewheeling diodes include a first freewheeling diode D4 and a second freewheeling diode D3, and the positive electrode of the output Vdc of the photovoltaic module or the pre-stage dc converter is connected to the positive electrode of the first dc voltage-dividing capacitor Cb1, The cathode of a first freewheeling diode D4 and the drain (D) of a first power switch tube S1, the cathode of the output Vdc of the photovoltaic module or the preceding-stage DC converter is connected to the cathode of a second DC bus voltage-dividing capacitor Cb2, the anode of a second freewheeling diode D3 and the source (S) of a second power switch tube S2, the cathodes of the first DC bus voltage-dividing capacitor Cb1 and the second DC bus voltage-dividing capacitor Cb2 are grounded and connected with the anode of a first clamping diode D1 and the cathode of the second clamping diode D2, the cathode of the first clamping diode D1 is connected to the drain (D) of the second power switch tube S2, the anode of the second clamping diode D2 is connected to the source (S3) of a third power switch tube S3, the source (S) of the first power switch tube S1, the source (S) of the second power switch tube S2 and the cathode of the second freewheeling diode D3 are connected to the same-name end of a double-winding reverse-phase coupling inductor Lf, and the drain of the second power switch tube S2 (D) and the drain (D2 and the second power switch tube S2, The drain (D) of the third power switch tube S3 and the anode of the first freewheeling diode D4 are connected to the different name end of the other winding, the different name end of one winding and the same name end of the other winding of the double-winding reverse-phase coupling split inductor Lf, namely the inverting output midpoint, are connected to one end of an output filter capacitor Cf and a live wire at one end of an alternating current output or public power grid, and the other end of the output filter capacitor Cf and the other end of the alternating current output are grounded through a zero line or a neutral line (N). Compared with fig. 3, only the inverter bridge arm is changed from I type to T type, two low voltage diodes can be respectively used for D3 and D4 in series, and one T-type five-level half bridge can be used to form a full bridge inverter together with another conventional half bridge or two T-type five-level half bridges. The working principle of other parts is basically the same as that of the figures 2-4, and the description is not repeated here.
In the third embodiment, as shown in fig. 6, a Flying Capacitor (FC) type inverter leg is adopted as the inverter leg, and the Flying Capacitor (FC) type inverter leg includes a first power switch tube S1, a second power switch tube S2, a third power switch tube S3, a fourth power switch tube S4, a body diode of the first power switch tube S1, a body diode of the second power switch tube S2, a body diode of the third power switch tube S3, a body diode of the fourth power switch tube S4, and a first flying capacitor CF1A second flying capacitor CF2The direct current bus voltage division capacitor comprises a first direct current bus voltage division capacitor and a second direct current bus voltage division capacitor, the freewheeling diode comprises a first freewheeling diode D3, a second freewheeling diode D2 and a third freewheeling diode D1, the positive electrode of the output Vdc of the photovoltaic module or the preceding-stage direct-current converter is connected to the positive electrode of the first direct-current bus voltage-dividing capacitor Cb1, the negative electrode of the first freewheeling diode D3 and the drain electrode (D) of the first power switching tube S1, the negative electrode of the output Vdc of the photovoltaic module or the preceding-stage direct-current converter is connected to the negative electrode of the second direct-current bus voltage-dividing capacitor Cb2, the positive electrode of the second freewheeling diode D2 and the source electrode (S) of the fourth power switching tube S4, the negative electrode of the first direct-current bus voltage-dividing capacitor Cb1 and the positive electrode of the second direct-current bus voltage-dividing capacitor Cb2 are grounded, and the source electrode (S) of the first power switching tube S1 and the drain electrode (D) of the second power switching tube S2 are connected to the first flying capacitor C.F1One terminal, third freewheeling diode D1 anodeThe cathode of the second fly-wheel diode D2 is connected to the first flying capacitor CF1The other end of the first fly-wheel diode D3 is connected with the anode of the first fly-wheel diode D4 and the cathode of the fourth fly-wheel diode D4F2One end of the third power switch tube S3, the source (S) of the fourth power switch tube S4, the drain (D) is connected to the second flying capacitor CF2And at the other end, the source (S) of the second power switch tube S2 and the cathode of the third freewheeling diode D1 are connected to the homonymous end of one winding of the double-winding reverse-phase coupling split inductor Lf, the drain (D) of the third power switch tube S3 and the anode of the fourth freewheeling diode D4 are connected to the heteronymous end of the other winding, the heteronymous end of one winding of the double-winding reverse-phase coupling split inductor Lf and the homonymous end of the other winding, namely the neutral point of the inversion output, are connected to one end of the output filter capacitor Cf and a live wire at one end of an alternating current output or public power grid, and the other end of the output filter capacitor Cf and the other end of the alternating current output are grounded through a zero line or a neutral line (N). Compared with fig. 3, only the inverter bridge arm is changed from the type I to the type FC, and one FC type five-level half bridge and one other conventional type half bridge or two FC type five-level half bridges can be used to form a full-bridge inverter. The working principle of other parts is basically the same as that of the figures 2-4, and the description is not repeated here.
In the fourth embodiment, a dual-winding reverse-phase coupling split-inductor two-level multi-level photovoltaic inverter is shown in fig. 7, the inverter leg is an HB-type inverter leg, the HB-type inverter leg includes a first power switch tube S1, a second power switch tube S4, a body diode of the first power switch tube S1, and a body diode of the second power switch tube S4, the dc bus voltage-dividing capacitor includes a first dc bus voltage-dividing capacitor and a second dc bus voltage-dividing capacitor, the freewheeling diode includes a first freewheeling diode D1 and a second freewheeling diode D4, the positive electrode of the Vdc output of the pv module or the pre-stage dc converter is connected to the positive electrode of the first dc bus voltage-dividing capacitor Cb1, the negative electrode of the first freewheeling diode D4, and the drain (D) of the first power switch tube S1, the negative electrode of the Vdc output of the pv module or the pre-stage dc converter is connected to the negative electrode of the second dc bus voltage-dividing capacitor Cb2, the second freewheeling diode D1, and the source (S4) of the second power switch tube S4, the negative electrode of a first direct current bus voltage-dividing capacitor Cb1 and the positive electrode of a second direct current bus voltage-dividing capacitor Cb2 are grounded, the source electrode (S) of a first power switch tube S1 and the cathode of a second fly-wheel diode D1 are connected to a winding homonymous end of a double-winding reverse-phase coupling split inductor Lf, the drain electrode (D) of the second power switch tube S4 and the anode of a first fly-wheel diode D4 are connected to a winding heteronymous end of the other winding, the homonymous end of one winding and the other winding homonymous end of the double-winding reverse-phase coupling split inductor Lf, namely the HB inversion output midpoint is connected to one end of an output filter capacitor Cf and a live wire at one end of an alternating current output or public power grid, and the other end of the output filter capacitor Cf and a neutral wire (N) at the other end of the alternating current output are grounded. Compared with fig. 3, only the inverter bridge arm is changed from the I-type to the HB-type, and it should be noted that the inverter midpoint output voltage is three levels. The D1 and D4 can also use two low voltage diodes connected in series, respectively, or can use one HB type tri-level half bridge mentioned above and one other conventional type half bridge or two HB type tri-level half bridges mentioned above to form a full bridge inverter. The working principle of other parts is basically the same as that of the figures 2-4, and the description is not repeated here.
In the fifth embodiment, as shown in fig. 8, the dual-winding reverse-phase coupling split-inductor cascaded multilevel photovoltaic inverter is an inverter leg of a Cascaded (CHB) type, where the inverter leg includes a first power switch tube S1, a second power switch tube S2, a third power switch tube S3, a fourth power switch tube S4, a body diode of the first power switch tube S1, a body diode of the second power switch tube S2, a body diode of the third power switch tube S3, and a body diode of the fourth power switch tube S4, the dual-winding reverse-phase coupling split inductor includes a first dual-winding reverse-phase coupling split inductor Lf1 and a second dual-winding reverse-phase coupling split inductor Lf2, the dc bus voltage-dividing capacitor includes a first dc bus voltage-dividing capacitor Cb1, a second dc bus voltage-dividing capacitor Cb2, a third dc voltage-dividing capacitor Cb3 and a fourth dc bus voltage-dividing capacitor Cb4, the freewheeling diode comprises a first freewheeling diode D1, a second freewheeling diode D2, a third freewheeling diode D3, a fourth freewheeling diode D4, Vdc1 and Vdc2 which are two DC input voltages not in common with the ground of the inverter, the anode of a first output Vdc1 of the photovoltaic module or the preceding direct-current converter is connected to the anode of a first DC bus voltage-dividing capacitor Cb1, the cathode of a fourth freewheeling diode D4 and the drain (D) of a first power switch tube S1, the cathode of a first output Vdc1 of the photovoltaic module or the preceding direct-current converter is connected to the cathode of a second DC bus voltage-dividing capacitor Cb2, the anode of a first freewheeling diode D1 and the source (S) of a fourth power switch tube S4, the anode of a second output Vdc2 of the photovoltaic module or the preceding direct-current converter is connected to the anode of a third DC bus voltage-dividing capacitor Cb 8, the cathode of a third freewheeling diode D3 and the drain (D2), the cathode of the second output Vdc 6327 of the photovoltaic module or the preceding direct-current converter is connected to the drain (D4) of the fourth DC bus voltage-dividing capacitor Cb4, The anode of a second fly-wheel diode D2 and the source (S) of a third power switch tube S3 are connected, the source (S) of the first power switch tube S1 and the cathode of the first fly-wheel diode D1 are connected to a winding dotted terminal of a first double-winding reverse-phase coupling split inductor Lf1, the drain (D) of a fourth power switch tube S4 and the anode of a fourth fly-wheel diode D4 are connected to a winding dotted terminal of the other winding, the winding dotted terminal of the first double-winding reverse-phase coupling split inductor Lf1 and the other winding dotted terminal CHB1 are connected to one end of an output filter capacitor Cf and one end of an alternating current output or public power grid live wire, the other end of the output filter capacitor Cf and the other end of the alternating current output are grounded, the cathode of a third direct current bus voltage-dividing capacitor Cb3 and the anode of a fourth direct current bus capacitor Cb4 are grounded, the source (S2) and the source (S2 of the second fly-wheel diode D2 are connected to one winding dotted terminal of the second double-winding reversed-winding split inductor Lf2, the drain (D) of the third power switch tube S3 and the anode of the third freewheeling diode D3 are connected to the different name end of the other winding, and the different name end of one winding and the same name end of the other winding of the second double-winding reverse-phase coupling split inductor Lf2 are connected to the negative electrode of the first direct-current bus voltage-dividing capacitor Cb1 and the positive electrode of the second direct-current bus voltage-dividing capacitor Cb 2. Compared with the fig. 3, only the inverter bridge arm is changed from the I type to the CHB type, and the D1, D2, D3 and D4 can also respectively use two low-voltage diodes in series connection, or one CHB type five-level half bridge and another conventional type half bridge or two CHB type five-level half bridges can be combined to form a full-bridge inverter. The working principle of other parts is basically the same as that of the figures 2-4, and the description is not repeated here.
In the sixth embodiment, as shown in fig. 9, the dual-winding reverse-phase coupling split-inductor three-phase I-type multilevel photovoltaic inverter includes an I-type three-phase inverter leg, where the I-type three-phase inverter leg includes an a-phase I-type bridge power switching tube, a B-phase I-type bridge power switching tube, and a C-phase I-type bridge power switching tube, and the a-phase I-type bridge power switching tube, the B-phase I-type bridge power switching tube, and the C-phase I-type bridge power switching tube are connected between the dual-winding reverse-phase coupling split inductor and the dc bus voltage-dividing capacitor. Vdc is inverter direct-current input voltage, Va is a alternating-current output or a public power grid, Cb1 and Cb2 are direct-current bus voltage-dividing capacitors, a-phase I-type bridge arm power switching tubes are Sa1, Sa2, Sa3 and Sa4, Dsa1, Dsa2, Dsa3 and Dsa4 are body diodes of the direct-current bus voltage-dividing capacitors, Da1 and Da2 are clamp diodes, Da3 and Da4 are free-wheeling diodes, a clamp capacitor Cca is optionally used for absorbing voltage spikes at two ends at the moment when Sa2 and Sa3 are turned off, Lfa is a double-winding reverse-phase coupling split inductor, namely an alternating-current output filter inductor, and plays a role of a split inverter bridge arm to avoid direct connection risk, and Cfa is an alternating-current output filter capacitor. Vdc is from photovoltaic module or preceding stage dc converter output, and its positive pole is connected to Cb1 positive pole, Da4 cathode and Sa1 drain (D), and the negative pole is connected to Cb2 negative pole, Da3 anode and Sa4 source (S). The negative electrode of Cb1 and the positive electrode of Cb2 are grounded and connected with the anode of Da1 and the cathode of Da2, the cathode of Sa1 source (S), Sa2 drain (D) and Da1 are connected to one end of Cca, and the anode of Sa3 source (S), Sa4 drain (D) and Da2 are connected to the other end of Cca. Sa2 has its source (S) and Da3 cathode connected to the synonym terminal of one winding of Lfa, and its Sa3 drain (D) and Da4 anode connected to the synonym terminal of the other winding. And the different-name end of one winding of the Lfa and the same-name end of the other winding of the Lfa, namely the neutral point of the inversion output, are connected to one end of the Cfa and one end of the a alternating current output or one end of a public power grid, the other end of the Cfa and the other end of the alternating current output are grounded through a zero line or a neutral line (N), and optionally, the other end of the Cfa and the other end of the alternating current output, namely the N line, can also be ungrounded, so that a grounded or floating alternating current system is formed. The above processes form A phase inversion alternating current output, and B phase and C phase are constructed by analogy. Compared with the figure 3, only a single-phase inverter is changed into a three-phase inverter, only a direct current-alternating current inverter circuit consisting of a B-phase inverter bridge arm, a C-phase inverter bridge arm, a freewheeling diode and a double-winding reverse-phase coupling split inductor is added, and the series form of two low-voltage diodes can be respectively used for Da 3-Da 4, Db 3-Db 4 and Dc 3-Dc 4. The three-phase inverter can use three independent controllers or share one controller, an SPWM module and an internal carrier circuit thereof in the controller need to be phase-shifted and staggered by 120 degrees, the working principle of the controller is basically the same as that of the three-phase inverter shown in the figures 2-4, and in addition, the three-phase inverter can be formed by the aid of the three-phase inverter shown in the figures 5-7, and repeated description is omitted.
The invention provides a multi-level photovoltaic inverter which mainly comprises an inverter bridge arm, a freewheeling diode, a double-winding reverse-phase coupling split inductor and a controller. The inverter bridge arms comprise power switching tubes and power diodes, and coupling inductors are arranged among the bridge arms to avoid the direct-connection risk of the inverter bridge arms. The controller samples AC/DC voltage and current signals and adjusts input voltage and output current accordingly. And a multi-carrier interleaved modulation strategy is adopted, the inversion midpoint output voltage is five levels, and the inversion midpoint output voltage can be output in a reactive power mode. The DC-AC power converter has the unique advantages of multiple levels, high efficiency, high reliability, capability of outputting reactive power and the like, and can be widely applied to various unidirectional and bidirectional DC-AC power converters.
The invention relates to a high-performance safety photovoltaic inverter which can be applied to photovoltaic grid-connected, photovoltaic off-grid and photovoltaic energy storage inverters, converters, Uninterruptible Power Supplies (UPS), active filters (APF), frequency converters, motor drivers and various unidirectional and bidirectional direct current and alternating current power converters.
The foregoing is merely a preferred embodiment of the invention and is not intended to limit the invention in any manner; those skilled in the art can readily practice the invention as shown and described in the drawings and detailed description herein; however, those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiments as a basis for designing or modifying other structures for carrying out the same purposes of the present invention without departing from the scope of the invention as defined by the appended claims; meanwhile, any changes, modifications, and evolutions of the equivalent changes of the above embodiments according to the actual techniques of the present invention are still within the protection scope of the technical solution of the present invention.

Claims (10)

1. A multilevel photovoltaic inverter characterized by: comprises an inverter bridge arm, a fly-wheel diode, a double-winding reverse-phase coupling split inductor, an output filter capacitor, a controller, a direct-current bus voltage-dividing capacitor and a plurality of direct-current converters, the output filter capacitor is connected in parallel with the two ends of the alternating current output or the public power grid, the output filter capacitor is connected with the double-winding reverse-phase coupling split inductor, the double-winding reverse-phase coupling split inductor and the freewheeling diode are connected with the inverter bridge arm, the direct current bus voltage-dividing capacitor is connected with the inverter bridge arm in parallel, the inverter bridge arm and the direct current bus voltage-dividing capacitor are connected with the direct current converter, the controller detects and samples voltage or current signals of an alternating current side and a direct current side, and adjusts and controls direct current input voltage and alternating current output current of the photovoltaic grid-connected inverter.
2. A multilevel photovoltaic inverter according to claim 1 wherein: the inverter bridge arm comprises a power switch tube and a power diode, the power switch tube is connected with the power diode, and the power switch tube is connected with the double-winding reverse-phase coupling split inductor, the freewheeling diode and the direct current converter.
3. A multilevel photovoltaic inverter as claimed in claim 2 wherein: the controller comprises a direct current bus voltage sampling module, an alternating current output voltage sampling module, a double-winding reverse-phase coupling split inductive current sampling module, a sine wave modulation module, a voltage compensator, a current compensator, a phase-locked loop module and an alternating current peak value calculation module, wherein the direct current bus voltage sampling module detects sampled direct current bus voltage, the alternating current output voltage sampling module detects sampled alternating current output amplitude value and then is connected to the phase-locked loop module and the input end of the alternating current peak value calculation module, the double-winding reverse-phase coupling split inductive current sampling module detects sampled alternating current output filter inductive current amplitude value, the sine wave modulation module is used for generating driving signals of various power switching tubes, the voltage compensator adjusts the direct current bus voltage amplitude value based on a voltage reference signal, and the phase-locked loop module generates alternating current frequency and phase signals, and the current compensator controls the double-winding reverse-phase coupling split inductance current waveform to change along with the change of alternating current output, the alternating current peak value calculation module is used for calculating the size of the alternating current output or the voltage peak value of a public power grid, and the alternating current peak value calculation module is multiplied by the output signal of the phase-locked loop module and then divided by the output signal of the direct current bus voltage sampling module to be used as a feedforward signal output by the current compensator to limit the output power.
4. A multilevel photovoltaic inverter according to claim 3 wherein: the controller also comprises a first adder, a second adder, a third adder, a first multiplier, a second multiplier and a divider, wherein the DC bus voltage sampling module detects the amplitude of the sampled DC input voltage and then is connected to the negative terminal of the first adder and the input terminal of the divider, the positive terminal of the first adder is connected with a voltage reference signal, the voltage error signal at the output terminal of the first adder is connected to the input terminal of a voltage compensator, the output terminal of the voltage compensator is connected to the input terminal of the multiplier, the AC output voltage sampling module detects the amplitude of the sampled AC output and then is connected to the input terminals of a phase-locked loop module and an AC peak value calculation module, the output terminal of the phase-locked loop module is connected to the other input terminal of the first multiplier and the input terminal of the second multiplier, the current reference signal at the output terminal of the first multiplier is connected to the positive terminal of the second adder, the AC output filter inductor current sampling module detects the amplitude of the sampled double-winding reverse-phase coupling split inductor current and then is connected to the second negative terminal, the output end of the third adder is connected with the input control end of the sine wave modulation module to generate driving signals of each power switch tube.
5. A multilevel photovoltaic inverter as claimed in claim 2 wherein: the inverter bridge arm is an I-type inverter bridge arm, the I-type inverter bridge arm comprises a first power switch tube, a second power switch tube, a third power switch tube, a fourth power switch tube, a body diode of the first power switch tube, a body diode of the second power switch tube, a body diode of the third power switch tube, a body diode of the fourth power switch tube, a first clamping diode, a second clamping diode and a clamping capacitor, the direct-current bus voltage-dividing capacitor comprises a first direct-current bus voltage-dividing capacitor and a second direct-current bus voltage-dividing capacitor, the freewheeling diode comprises a first freewheeling diode and a second freewheeling diode, the positive electrode of the output of the photovoltaic component or the preceding-stage direct-current converter is connected to the positive electrode of the first direct-current bus voltage-dividing capacitor, the negative electrode of the first freewheeling diode and the drain electrode of the first power switch tube, the negative electrode of the output of the photovoltaic component or the preceding-stage direct-current converter is connected to the negative electrode of the second direct-current bus voltage-dividing capacitor, The anode of a second fly-wheel diode and the source of a fourth power switch tube, the cathode of a first direct-current bus voltage-dividing capacitor and the anode of a second direct-current bus voltage-dividing capacitor are grounded and connected with the anode of a first clamping diode and the cathode of a second clamping diode, the source of the first power switch tube, the drain of the second power switch tube and the cathode of the first clamping diode are connected with one end of the clamping capacitor, the source of a third power switch tube, the drain of the fourth power switch tube and the anode of the second clamping diode are connected with the other end of the clamping capacitor, the source of the second power switch tube and the cathode of the second fly-wheel diode are connected with the homonymous end of one winding of the double-winding reverse-phase coupling split inductor, the drain of the third power switch tube and the anode of the first fly-wheel diode are connected with the heteronymous end of the other winding of the double-winding reverse-phase coupling split inductor, the heteronymous end of one winding of the double-winding reverse-phase coupling split inductor and the other winding of the double-winding reverse-winding split inductor are connected with one end of an output filter capacitor and one end of an alternating-current output or a public power grid, the other end of the output filter capacitor and the other end of the alternating current output are grounded through a zero line or a neutral line.
6. A multilevel photovoltaic inverter as claimed in claim 2 wherein: the inverter bridge arm is a T-shaped inverter bridge arm, the T-shaped inverter bridge arm comprises a first power switch tube, a second power switch tube, a third power switch tube, a fourth power switch tube, a body diode of the first power switch tube, a body diode of the second power switch tube, a body diode of the third power switch tube, a body diode of the fourth power switch tube, a first clamping diode and a second clamping diode, the direct-current bus voltage-dividing capacitor comprises a first direct-current bus voltage-dividing capacitor and a second direct-current bus voltage-dividing capacitor, the freewheeling diode comprises a first freewheeling diode and a second freewheeling diode, the positive electrode output by the photovoltaic component or the preceding-stage direct-current converter is connected to the positive electrode of the first direct-current bus voltage-dividing capacitor, the negative electrode output by the photovoltaic component or the preceding-stage direct-current converter is connected to the negative electrode of the second direct-current bus voltage-dividing capacitor, The anode of a second fly-wheel diode and the source of a second power switch tube, the cathode of a first direct current bus voltage-dividing capacitor and the anode of a second direct current bus voltage-dividing capacitor are grounded and connected with the anode of a first clamping diode and the cathode of a second clamping diode, the cathode of the first clamping diode is connected with the drain of a second power switch tube, the anode of the second clamping diode is connected with the source of a third power switch tube, the source of the first power switch tube, the source of the second power switch tube and the cathode of the second fly-wheel diode are connected with the homonymous end of a winding of the double-winding reverse-phase coupling split inductor, the drain of the second power switch tube, the drain of the third power switch tube and the anode of the first fly-wheel diode are connected with the heteronymous end of another winding, the heteronymous end of the winding of the double-winding reverse-phase coupling split inductor and the homonymous end of the other winding are connected with one end of an output filter capacitor and a live wire of an alternating current output or a public power grid, the other end of the output filter capacitor and the other end of the alternating current output are grounded through a zero line or a neutral line.
7. A multilevel photovoltaic inverter as claimed in claim 2 wherein: the inverter bridge arm is an FC-type inverter bridge arm, the FC-type inverter bridge arm comprises a first power switch tube, a second power switch tube, a third power switch tube, a fourth power switch tube, a body diode of the first power switch tube, a body diode of the second power switch tube, a body diode of the third power switch tube, a body diode of the fourth power switch tube, a first flying capacitor and a second flying capacitor, the DC bus voltage-dividing capacitor comprises a first DC bus voltage-dividing capacitor and a second DC bus voltage-dividing capacitor, the fly-wheel diode comprises a first fly-wheel diode, a second fly-wheel diode, a third fly-wheel diode and a fourth fly-wheel diode, the positive electrode output by the photovoltaic component or the preceding-stage DC converter is connected to the positive electrode of the first DC bus voltage-dividing capacitor, the negative electrode of the first fly-wheel diode and the drain electrode of the first power switch tube, the negative electrode output by the photovoltaic component or the DC converter is connected to the negative electrode of the second DC bus voltage-dividing capacitor, The anode of the second fly-wheel diode and the drain of the second power switch tube are connected to one end of the first flying capacitor, the anode of the third fly-wheel diode and the cathode of the second fly-wheel diode are connected to the other end of the first flying capacitor, the anode of the first fly-wheel diode and the cathode of the fourth fly-wheel diode are connected to one end of the second flying capacitor, the source of the third power switch tube and the drain of the fourth power switch tube are connected to the other end of the second flying capacitor, the source of the second power switch tube and the cathode of the third fly-wheel diode are connected to the same-name end of one winding of the double-winding reverse-phase coupling split inductor, the drain of the third power switch tube and the anode of the fourth fly-wheel diode are connected to the different-name end of the other winding, the different-name end of one winding and the same-name end of the other winding of the double-winding reverse-phase coupling split inductor are connected to one end of the output filter capacitor and the AC output or the same-name end of the public power grid The live wire is connected with the other end of the output filter capacitor, and the zero line or the neutral line of the other end of the alternating current output is grounded.
8. A multilevel photovoltaic inverter as claimed in claim 2 wherein: the inversion bridge arm adopts an HB type inversion bridge arm, the HB type inversion bridge arm comprises a first power switch tube, a second power switch tube, a body diode of the first power switch tube and a body diode of the second power switch tube, the DC bus voltage-dividing capacitor comprises a first DC bus voltage-dividing capacitor and a second DC bus voltage-dividing capacitor, the freewheel diode comprises a first freewheel diode and a second freewheel diode, the positive pole of the output of the photovoltaic component or the preceding DC converter is connected to the positive pole of the first DC bus voltage-dividing capacitor, the negative pole of the first freewheel diode and the drain electrode of the first power switch tube, the negative pole of the output of the photovoltaic component or the preceding DC converter is connected to the negative pole of the second DC bus voltage-dividing capacitor, the positive pole of the second freewheel diode and the source electrode of the second power switch tube, the negative pole of the first DC bus voltage-dividing capacitor and the positive pole of the second DC bus voltage-dividing capacitor are grounded, the source electrode of the first power switch tube and the cathode of the second freewheeling diode are connected to a winding homonymous end of the double-winding reverse-phase coupling split inductor, the drain electrode of the second power switch tube and the anode of the first freewheeling diode are connected to a winding homonymous end of the other winding, the winding heteronymous end of the double-winding reverse-phase coupling split inductor and the other winding homonymous end of the double-winding reverse-phase coupling split inductor are connected to one end of the output filter capacitor and a live wire at one end of the alternating current output or public power grid, and the other end of the output filter capacitor and the other end of the alternating current output are grounded through a zero line or a neutral line.
9. A multilevel photovoltaic inverter as claimed in claim 2 wherein: the inverter bridge arm is a CHB type inverter bridge arm, the CHB type inverter bridge arm comprises a first power switch tube, a second power switch tube, a third power switch tube, a fourth power switch tube, a body diode of the first power switch tube, a body diode of the second power switch tube, a body diode of the third power switch tube and a body diode of the fourth power switch tube, the double-winding reverse-phase coupling split inductor comprises a first double-winding reverse-phase coupling split inductor and a second double-winding reverse-phase coupling split inductor, the direct-current bus voltage-dividing capacitor comprises a first direct-current bus voltage-dividing capacitor, a second direct-current bus voltage-dividing capacitor, a third direct-current bus voltage-dividing capacitor and a fourth direct-current bus voltage-dividing capacitor, the fly-wheel diode comprises a first fly-wheel diode, a second fly-wheel diode, a third fly-wheel diode and a fourth fly-wheel diode, and the positive electrode of the first output of the photovoltaic component or the pre-stage direct-current converter is connected to the positive electrode of the first direct-current bus voltage-dividing capacitor, A cathode of a fourth fly-wheel diode and a drain of a first power switch tube, a cathode of a first output of the photovoltaic component or the preceding direct-current converter is connected to a cathode of a second direct-current bus voltage-dividing capacitor, an anode of the first fly-wheel diode and a source of the fourth power switch tube, an anode of a second output of the photovoltaic component or the preceding direct-current converter is connected to an anode of a third direct-current bus voltage-dividing capacitor, a cathode of a third fly-wheel diode and a drain of a second power switch tube, a cathode of a second output of the photovoltaic component or the preceding direct-current converter is connected to a cathode of the fourth direct-current bus voltage-dividing capacitor, an anode of the second fly-wheel diode and a source of the third power switch tube, a source of the first power switch tube and a cathode of the first fly-wheel diode are connected to a homonymous end of one winding of the first double-winding reverse-phase coupling split inductor, a drain of the fourth power switch tube and an anode of the fourth fly-wheel diode are connected to a homonymous end of the other winding, a heteronymous end of one winding of the first double-winding reverse-phase coupling split inductor and the other winding are connected to an output filter tube One end of a wave capacitor is connected with a live wire at one end of an alternating current output or public power grid, the other end of an output filter capacitor is connected with a zero line or a neutral line at the other end of the alternating current output, the negative electrode of a third direct current bus voltage-dividing capacitor is connected with the positive electrode of a fourth direct current bus voltage-dividing capacitor, the source electrode of a second power switch tube and the cathode of a second fly-wheel diode are connected to the homonymous end of one winding of a second dual-winding reverse-phase coupling split inductor, the drain electrode of the third power switch tube and the anode of the third fly-wheel diode are connected to the homonymous end of the other winding, and the heteronymous end of one winding of the second dual-winding reverse-phase coupling split inductor and the homonymous end of the other winding of the second dual-winding reverse-phase coupling split inductor are connected to the negative electrode of the first direct current bus voltage-dividing capacitor and the positive electrode of the second direct current bus voltage-dividing capacitor.
10. A multilevel photovoltaic inverter according to claim 3 wherein: the inverter bridge arm is an I-type three-phase inverter bridge arm, the I-type three-phase inverter bridge arm comprises an A-phase I-type bridge arm power switch tube, a B-phase I-type bridge arm power switch tube and a C-phase I-type bridge arm power switch tube, and the A-phase I-type bridge arm power switch tube, the B-phase I-type bridge arm power switch tube and the C-phase I-type bridge arm power switch tube are connected between the double-winding reverse-phase coupling split inductor and the direct-current bus voltage-dividing capacitor.
CN202110662339.8A 2021-06-15 2021-06-15 Multi-level photovoltaic inverter Pending CN113630029A (en)

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Cited By (7)

* Cited by examiner, † Cited by third party
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CN114499259A (en) * 2022-01-11 2022-05-13 浙江大学 Single-phase five-level photovoltaic grid-connected inverter and control method thereof
CN114900029A (en) * 2022-05-09 2022-08-12 南京航空航天大学 Single-phase single-stage coupling inductance type split source boost inverter and method thereof
CN115642826A (en) * 2022-12-14 2023-01-24 惠州市乐亿通科技有限公司 Bidirectional split-phase inverter circuit and bidirectional split-phase inverter
CN115664248A (en) * 2022-12-14 2023-01-31 惠州市乐亿通科技有限公司 Bidirectional inverter circuit and bidirectional inverter
CN115995994A (en) * 2022-11-04 2023-04-21 惠州市乐亿通科技有限公司 Split-phase three-bridge arm inverter circuit and modulation method
CN116191918A (en) * 2022-12-14 2023-05-30 惠州市乐亿通科技有限公司 Non-staggered parallel soft switch split-phase inverter circuit, modulation method and split-phase inverter
CN116455251A (en) * 2023-06-14 2023-07-18 麦田能源股份有限公司 Three-level converter and control method thereof

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114499259A (en) * 2022-01-11 2022-05-13 浙江大学 Single-phase five-level photovoltaic grid-connected inverter and control method thereof
CN114900029A (en) * 2022-05-09 2022-08-12 南京航空航天大学 Single-phase single-stage coupling inductance type split source boost inverter and method thereof
CN115995994A (en) * 2022-11-04 2023-04-21 惠州市乐亿通科技有限公司 Split-phase three-bridge arm inverter circuit and modulation method
CN115995994B (en) * 2022-11-04 2023-07-28 惠州市乐亿通科技有限公司 Split-phase three-bridge arm inverter circuit and modulation method
CN115642826A (en) * 2022-12-14 2023-01-24 惠州市乐亿通科技有限公司 Bidirectional split-phase inverter circuit and bidirectional split-phase inverter
CN115664248A (en) * 2022-12-14 2023-01-31 惠州市乐亿通科技有限公司 Bidirectional inverter circuit and bidirectional inverter
CN115664248B (en) * 2022-12-14 2023-03-21 惠州市乐亿通科技有限公司 Bidirectional inverter circuit and bidirectional inverter
CN116191918A (en) * 2022-12-14 2023-05-30 惠州市乐亿通科技有限公司 Non-staggered parallel soft switch split-phase inverter circuit, modulation method and split-phase inverter
CN116191918B (en) * 2022-12-14 2023-10-27 惠州市乐亿通科技有限公司 Modulation method of non-staggered parallel soft switch split-phase inverter circuit and split-phase inverter
CN116455251A (en) * 2023-06-14 2023-07-18 麦田能源股份有限公司 Three-level converter and control method thereof
CN116455251B (en) * 2023-06-14 2023-08-29 麦田能源股份有限公司 Three-level converter and control method thereof

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