CN108111044B - Isolation flyback periodic wave type single-stage multi-input inverter with external parallel time-sharing selection switch - Google Patents

Isolation flyback periodic wave type single-stage multi-input inverter with external parallel time-sharing selection switch Download PDF

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CN108111044B
CN108111044B CN201810020144.1A CN201810020144A CN108111044B CN 108111044 B CN108111044 B CN 108111044B CN 201810020144 A CN201810020144 A CN 201810020144A CN 108111044 B CN108111044 B CN 108111044B
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input
output
power
inverter
current
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CN108111044A (en
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陈道炼
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Qingdao University
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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
    • H02M7/53—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 using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—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 using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—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 using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
    • 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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/12—Arrangements for reducing harmonics from ac input or output
    • H02M1/126—Arrangements for reducing harmonics from ac input or output using passive filters
    • 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
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • 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
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/3353—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having at least two simultaneously operating switches on the input side, e.g. "double forward" or "double (switched) flyback" converter
    • 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
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
    • 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
    • H02M7/53—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 using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—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 using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/539—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 using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters with automatic control of output wave form or frequency
    • H02M7/5395—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 using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters with automatic control of output wave form or frequency by pulse-width modulation
    • 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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0067—Converter structures employing plural converter units, other than for parallel operation of the units on a single load
    • H02M1/007—Plural converter units in cascade
    • 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

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

Abstract

The invention relates to an external parallel time-sharing selection switch isolation flyback cyclic wave type single-stage multi-input inverter, the circuit structure of which is formed by connecting a plurality of common-ground input filters and a common output isolation energy storage voltage transformation cyclic wave conversion filter circuit by a multi-input single-output high-frequency inverter circuit of an external parallel time-sharing selection four-quadrant power switch, each input end of the multi-input single-output high-frequency inverter circuit is correspondingly connected with the output end of each input filter one by one, and the output end of the multi-input single-output high-frequency inverter circuit is connected with the input end of the output isolation energy storage voltage transformation cyclic wave conversion filter circuit. The inverter has the characteristics of common ground of multiple input sources, time-sharing power supply, isolation of output and input electricity, sharing of an energy storage cycle conversion filter circuit, simple circuit, single-stage conversion, high efficiency, high reliability in load short circuit, wide application prospect and the like, and lays a key technology for a small-capacity distributed power supply system for realizing combined power supply of multiple new energy sources.

Description

Isolation flyback periodic wave type single-stage multi-input inverter with external parallel time-sharing selection switch
Technical Field
The invention relates to an external parallel time-sharing selection switch isolated flyback periodic wave type single-stage multi-input inverter, belonging to the power electronic conversion technology.
Background
The inverter is a static converter which applies a power semiconductor device to convert unstable and poor direct current electric energy into stable and good alternating current electric energy, and is used for alternating current loads or realizes alternating current grid connection. The inverter with low-frequency electrical isolation (including no electrical isolation) or high-frequency electrical isolation between the output alternating current load or the alternating current power grid and the input direct current power supply is respectively called as a low-frequency link inverter and a high-frequency link inverter. The electrical isolation element plays a major role in the inverter: (1) the electrical isolation between the output and the input of the inverter is realized, and the safety reliability and the electromagnetic compatibility of the operation of the inverter are improved; (2) the matching between the output voltage and the input voltage of the inverter is realized, namely the technical effect that the output voltage of the inverter is higher than, equal to or lower than the input voltage is realized, and the application range of the inverter is greatly widened; (3) when the working frequency of the transformer or the energy storage type transformer is above 20kHz, the volume and the weight of the transformer or the energy storage type transformer are greatly reduced, and audio noise is eliminated. Therefore, the inverter has an important application value in secondary power conversion using a dc generator, a battery, a photovoltaic cell, a fuel cell, or the like as a main dc power source.
The new energy sources (also called green energy sources) such as solar energy, wind energy, tidal energy, geothermal energy and the like have the advantages of cleanness, no pollution, low price, reliability, richness and the like, thereby having wide application prospect. Due to the increasing shortage of traditional fossil energy (non-renewable energy) such as petroleum, coal and natural gas, serious environmental pollution, global warming, nuclear waste generated by nuclear energy production, environmental pollution and the like, the development and utilization of new energy are receiving more and more attention. The new energy power generation mainly comprises photovoltaic, wind power, fuel cells, water power, geothermal energy and the like, and all the types have the defects of unstable and discontinuous power supply, change along with climatic conditions and the like, so that a distributed power supply system adopting various new energy sources for combined power supply is needed.
A traditional new energy distributed power supply system is shown in figures 1 and 2. The system generally adopts a plurality of single-input direct-current converters to convert electric energy of new energy power generation equipment which does not need energy storage, such as photovoltaic cells, fuel cells, wind driven generators and the like, through one unidirectional direct-current converter respectively, and the output ends of the new energy power generation equipment are connected to a direct-current bus of a common inverter in parallel or in series, so that the combined power supply of various new energy sources is ensured, and the coordinated work can be realized. The distributed power generation system realizes the priority utilization of the power supplied by a plurality of input sources to the load and the energy, improves the stability and the flexibility of the system, but has the defects of two-stage power conversion, low power density, low conversion efficiency, high cost and the like, and the practicability of the distributed power generation system is limited by a great degree.
In order to simplify the circuit structure and reduce the number of power conversion stages, a novel single-stage new energy distributed power supply system needs to be formed by replacing the conventional multi-input inverter with a direct-current converter and an inverter two-stage cascade circuit structure shown in fig. 1 and 2 by the novel multi-input inverter with a single-stage circuit structure shown in fig. 3. The single-stage multi-input inverter allows for multiple new energy inputs, and the nature, magnitude and characteristics of the input sources may be the same or may vary widely. The novel single-stage new energy distributed power supply system has the advantages of simple circuit structure, single-stage power conversion, low cost and the like, and a plurality of input sources simultaneously or in time-sharing mode supply power to a load in one high-frequency switching period.
Therefore, the active search for a single-stage multi-input inverter allowing multiple new energy sources to supply power jointly and a new energy source distributed power supply system thereof is urgent, and the active search has a very important significance for improving the stability and flexibility of the system and realizing the prior utilization or the full utilization of the new energy sources.
Disclosure of Invention
The invention aims to provide an external parallel time-sharing selection switch isolated flyback cyclic-wave type single-stage multiple-input inverter which has the characteristics of multiple new energy sources for combined power supply, common ground of input direct-current power supplies, external parallel time-sharing selection switches of a multiple-input single-output high-frequency inverter circuit, electrical isolation between output and input, time-sharing power supply within one switching period of multiple input power supplies, simple circuit topology, shared output isolated energy-storage variable-voltage cyclic-wave conversion filter circuit, single-stage power conversion, high conversion efficiency, high reliability during load short circuit, small output capacity, wide application prospect and the like.
The technical scheme of the invention is as follows: an external parallel time-sharing selection switch isolation flyback cyclic-wave type single-stage multiple-input inverter is formed by connecting a plurality of common-ground input filters and a common output isolation energy-storage voltage-storage cyclic-wave conversion filter circuit through a multiple-input single-output high-frequency inverter circuit, wherein each input end of the multiple-input single-output high-frequency inverter circuit is correspondingly connected with the output end of each input filter one by one, the output end of the multiple-input single-output high-frequency inverter circuit is connected with the input end of an energy-storage transformer of the output isolation energy-storage voltage-storage cyclic-wave conversion filter circuit, the multiple-input single-output high-frequency inverter circuit is formed by sequentially cascading an external multi-path parallel time-sharing selection four-quadrant power switch circuit and a bidirectional power flow single-input single-output high-frequency inverter circuit, and is equivalent to a bidirectional power flow single-input single-output, each path of the external multi-path parallel time-sharing selection four-quadrant power switch circuit is only composed of one four-quadrant power switch, output ends of the four-quadrant power switch circuit are connected in parallel, the output isolation energy storage voltage transformation cyclic wave conversion filter circuit is formed by sequentially cascading an energy storage type transformer, a cyclic wave converter and an output filter, and the cyclic wave converter is composed of four-quadrant high-frequency power switches capable of bearing bidirectional voltage stress and bidirectional current stress.
The invention relates to a multi-input inverter circuit structure formed by cascading a direct current converter and an inverter of a traditional multi-new-energy combined power supply system in two stages, which is constructed into a novel single-stage multi-input inverter circuit structure with an external parallel time-sharing selection switch, and provides the circuit structure, a topological family and an energy management control strategy of the single-stage multi-input inverter circuit structure with the isolation flyback cycloidal type single-stage multi-input inverter circuit structure with the external parallel time-sharing selection switch, namely the circuit structure is formed by connecting a plurality of common-ground input filters and a common output isolation energy storage voltage transformation cycloidal conversion filter circuit through a multi-input single-output high-frequency inverter circuit with the external parallel time-sharing selection four-quadrant power.
The external parallel time-sharing selection switch isolation flyback cyclic-wave type single-stage multi-input inverter can invert a plurality of common-ground and unstable input direct-current voltages into stable and high-quality output alternating-current power required by a load, and has the characteristics of common-ground of a multi-input direct-current power supply, no isolation between multi-input single-output high-frequency inverter circuits, electrical isolation between output and input, time-sharing power supply within one switching period of the multi-input power supply, simple circuit topology, common output isolation energy storage variable-voltage cyclic-wave conversion filter circuit, single-stage power conversion, high conversion efficiency, wide input voltage variation range, high reliability during load short circuit, small output capacity, wide application prospect and the like. The comprehensive performance of the isolated flyback periodic wave type single-stage multi-input inverter with the external parallel time-sharing selection switch is superior to that of a multi-input inverter formed by two-stage cascading of a traditional direct-current converter and an inverter.
Drawings
Fig. 1 shows a conventional two-stage new energy distributed power supply system with a plurality of unidirectional dc converters connected in parallel at output terminals.
Fig. 2 shows a conventional two-stage new energy distributed power supply system with a plurality of unidirectional dc converters connected in series at output terminals.
Fig. 3 is a schematic block diagram of a novel single-stage multiple-input inverter.
Fig. 4 is a schematic block diagram of an external parallel time-sharing selection switch isolated flyback periodic-wave type single-stage multi-input inverter.
Fig. 5 is a circuit structure diagram of an external parallel time-sharing selection switch isolation flyback periodic-wave type single-stage multi-input inverter.
Fig. 6 is a waveform diagram of a steady-state principle of an external parallel time-sharing selection switch isolated flyback cyclic single-stage multi-input inverter controlled by an output voltage instantaneous value SPWM with four working mode selections.
Fig. 7 is a schematic diagram of a circuit topology example-push-pull circuit of an external parallel time-sharing selection switch isolated flyback cyclic single-stage multiple-input inverter.
Fig. 8 is a schematic diagram of a circuit topology example of an external parallel time-sharing selection switch isolated flyback cyclic single-stage multiple-input inverter, i.e., a push-pull forward circuit.
Fig. 9 is a schematic diagram of a three-half bridge circuit of a topology example of an external parallel time-sharing selection switch isolated flyback cyclic single-stage multiple-input inverter circuit.
Fig. 10 is a schematic diagram of a circuit topology example of an external parallel time-sharing selection switch isolated flyback cyclic single-stage multiple-input inverter, i.e., a full-bridge circuit.
Fig. 11 is a master-slave power distribution energy management control block diagram of an external parallel time-sharing selection switch isolated flyback cyclic single-stage multiple-input inverter with output voltage and input current instantaneous values SPWM selected by four working modes.
Fig. 12 is a waveform diagram of a principle of master-slave power distribution energy management control of an external parallel time-sharing selection switch isolated flyback cyclic single-stage multiple-input inverter with output voltage and input current instantaneous values SPWM selected by four working modes.
Fig. 13 shows an external parallel time-sharing selection switch isolated flyback cyclic single-stage multiple-input independent power supply system with an output end connected in parallel with a single-stage isolated bidirectional charge-discharge converter.
Fig. 14, maximum power output energy management control strategy with single stage isolated bidirectional charge-discharge converter output voltage independent control loop.
FIG. 15, output voltage u of independent power supply systemoOutput current iLfAnd an output filter inductor iLf' waveform.
Detailed Description
The technical solution of the present invention is further described below with reference to the drawings and examples of the specification.
An external parallel time-sharing selection switch isolation flyback cyclic-wave type single-stage multi-input inverter is formed by connecting a plurality of common-ground input filters with a common output isolation energy storage transformation cyclic-wave conversion filter circuit through a multi-input single-output high-frequency inverter circuit, wherein each input end of the multi-input single-output high-frequency inverter circuit is correspondingly connected with the output end of each input filter one by one, the output end of the multi-input single-output high-frequency inverter circuit is connected with the input end of an energy storage type transformer of the output isolation energy storage transformation cyclic-wave conversion filter circuit, the multi-input single-output high-frequency inverter circuit is formed by sequentially cascading an external multi-path parallel time-sharing selection four-quadrant power switch circuit and a bidirectional power flow single-input single-output high-frequency inverter circuit, the multi-input single-output high-frequency inverter circuit is equivalent to a bidirectional power flow single-input single-output high-frequency inverter circuit at any moment, and each path of the external The frequency switch is formed, the output ends of all paths are connected in parallel, the output isolation energy storage voltage transformation cycle wave conversion filter circuit is formed by sequentially cascading an energy storage type transformer, a cycle wave converter and an output filter, and the cycle wave converter is formed by a four-quadrant high-frequency power switch capable of bearing bidirectional voltage stress and bidirectional current stress.
The principle block diagram and the circuit structure of the external parallel time-sharing selection switch isolation flyback cyclic single-stage multi-input inverter, and the stable principle waveform of the output voltage instantaneous value SPWM control inverter with four working mode selections are respectively shown in fig. 4, 5, 6 and 7. In FIGS. 4, 5, 6 and 7, Ui1、Ui2、…、UinInputting a DC voltage source for n paths (n is large)Natural number at 1), ZLFor single-phase output AC loads (including single-phase AC passive loads and single-phase AC grid loads), uo、ioRespectively single-phase output alternating voltage and alternating current. The n-input single-output high-frequency inverter circuit is formed by sequentially cascading an external multi-path parallel time-sharing selection four-quadrant power switch circuit and a bidirectional power flow single-input single-output high-frequency inverter circuit, wherein the external multi-path parallel time-sharing selection four-quadrant power switch circuit is formed by n four-quadrant high-frequency power switches capable of bearing bidirectional voltage stress and bidirectional current stress, the bidirectional power flow single-input single-output high-frequency inverter circuit is formed by a plurality of two-quadrant high-frequency power switches capable of bearing unidirectional voltage stress and bidirectional current stress, and power devices such as an MOSFET (metal oxide semiconductor field effect transistor), an IGBT (insulated gate bipolar transistor), a GTR (GTR) and the like can; the output isolation energy storage transformation cycle wave conversion filter circuit is formed by sequentially cascading an energy storage type transformer, a cycle wave converter and an output filter, wherein the cycle wave converter is realized by one or two four-quadrant high-frequency power switches capable of bearing bidirectional voltage stress and bidirectional current stress, and only a circuit diagram of an output capacitor filter suitable for a passive alternating current load is drawn in a space diagram, but a circuit diagram of an output capacitor inductance filter suitable for an alternating current power grid load is not drawn; the n-path input filter is an LC filter (filter inductor L with an added virtual frame)i1、Li2、…、Lin) Or a capacitor filter (filter inductor L without adding a virtual frame)i1、Li2、…、Lin) When an LC filter is adopted, the n input direct current paths are smoother. The n-input single-output high-frequency inverter circuit inputs n paths of direct-current voltage sources Ui1、Ui2、…、UinUnipolar tri-state multi-slope SPWM current wave i with modulated amplitude distributed according to sinusoidal envelope curveN1(iN11+iN12) The amplitude is demodulated into a unipolar three-state single-slope SPWM current wave i distributed according to a sinusoidal envelope line through an energy storage type transformer T isolation and a cycle converterN2(iN2++iN2-) After the output filter capacitor, high-quality sine alternating-current voltage u is obtained on the single-phase alternating-current passive load or the single-phase alternating-current power gridoOr sinusoidal alternating current ioN input single inputN input pulse currents of the high-frequency inverter circuit pass through the input filter Li1-Ci1、Li2-Ci2、…、Lin-CinOr Ci1、Ci2、…、CinThen inputting a direct current power supply U in n pathsi1、Ui2、…、UinTo obtain a smooth input direct current Ii1、Ii2、…、Iin. It should be added that the dual polarity two-state multi-level SPWM voltage wave uABOr uA′B′Has an amplitude of + - (-) (U)i1、Ui2、…、Uin) And uoN1/N2(push-pull forward type, full bridge type circuit), ± 2 (U)i1、Ui2、…、Uin) And. + -. 2uoN1/N2(push-pull circuit), ± 1/2 (U)i1、Ui2、…、Uin) And uoN1/N2(half-bridge Circuit), unipolar Tri-State multilevel SPWM Current wave iN1(iN11+iN12) Respectively, the rising slopes ofi1/L1、Ui2/L1、…、Uin/L1(push-pull, push-pull forward, full bridge) or Ui1/(2L1)、Ui2/(2L1)、…、Uin/(2L1) (half-bridge Circuit), unipolar Tri-State Single-level SPWM Current wave iN2(iN2++iN2-) Has a rising slope of-uo/L2Wherein L is1、L2The inductances of the primary winding and the secondary winding of the energy storage transformer are respectively.
An external parallel time-sharing selection switch isolation flyback periodic wave type single-stage multi-input inverter belongs to a boost-buck type inverter, and n input sources supply power to loads in parallel in a time-sharing manner. The principle of the inverter is equivalent to the superposition of currents at the input end of a plurality of flyback single-input inverters, namely the output voltage uoAnd input direct current voltage (U)i1、Ui2、…、Uin) Energy-storage transformer turn ratio (N)2/N1) Duty ratio (d)1、d2、…、dn) The relationship between is uo＝(d1Ui1+d2Ui2+…+dnUin)N2/[N1(1-d1-d2-…-dn)]. For a suitable duty cycle (d)1、d2、…、dn) And turn ratio (N) of energy-storage transformer2/N1)，uoCan be greater than, equal to or less than the sum U of the input DC voltagesi1+Ui2+…+UinThe energy storage transformer in the inverter not only improves the safety reliability and the electromagnetic compatibility of the operation of the inverter, but also plays a role in matching the output voltage with the input voltage, namely, the output voltage of the inverter is higher than, equal to or lower than the sum U of the input direct current voltagei1+Ui2+…+UinThe application range of the method is greatly widened. When d is more than 0.51+d2+…+dn< 1 or 0 < d1+d2+…+dnWhen < 0.5, u is presento＞(Ui1+Ui2+…+Uin)N2/N1Or uo＜(Ui1+Ui2+…+Uin)N2/N1I.e. the output voltage uoHigher or lower than the input DC voltage (U)i1、Ui2、…、Uin) Turns ratio (N) of energy-storage transformer2/N1) Sum of products of (U)i1+Ui2+…+Uin)N2/N1(ii) a Because the inverter belongs to a single-stage circuit structure, an energy storage type transformer is arranged at the output and the input of the inverter for isolation, and the multi-path parallel time-sharing selection four-quadrant power switch is positioned outside the high-frequency inverter circuit, the inverter is called as an external parallel time-sharing selection switch isolation flyback (boost-buck type) single-stage multi-input inverter. The energy storage type transformer has two working modes of high-frequency magnetic reset and low-frequency magnetic reset, the former is that the energy storage type transformer realizes magnetic flux reset in a high-frequency switching period, works in a DCM mode because power can not flow reversely and adopts a constant-frequency SPWM control strategy, has no audio noise, and belongs to a high-frequency link inverter; the latter is that the energy storage transformer realizes magnetic flux reset in an output low-frequency period and works in a CCM modeThe formula and the control strategy of constant frequency SPWM are adopted, audio noise exists, and the inverter does not belong to a high-frequency link inverter. The n input sources of the inverter can only supply power to the output alternating current load in a time-sharing way in a high-frequency switching period, and the duty ratios can be the same (d)1＝d2＝…＝dn) Or may be different (d)1≠d2≠…≠dn)。
The external parallel time-sharing selection switch isolation flyback cyclic-wave type single-stage multi-input inverter disclosed by the invention shares a bidirectional power flow single-input single-output high-frequency inverter circuit and an output isolation energy storage variable-voltage cyclic-wave conversion filter circuit, and is essentially different from a traditional multi-input inverter circuit structure formed by two-stage cascading of a direct-current converter and an inverter. Therefore, the inverter has novelty and creativity, has the characteristics of electrical isolation of output and input, time-sharing power supply of a multi-input power supply, simple circuit topology, single-stage power conversion, large voltage-boosting and voltage-reducing ratio, wide input voltage variation range, flexible input voltage preparation, high conversion efficiency (meaning small energy loss), high reliability in load short circuit, small output capacity, low cost, wide application prospect and the like, is an ideal energy-saving and consumption-reducing single-stage multi-input inverter, and has important value in the situation of vigorously advocating the construction of energy-saving and energy-saving society at present.
An external parallel time-sharing selection switch isolates the topology family of the flyback cycloidal single-stage multiple-input inverter circuit, as shown in fig. 7, 8, 9 and 10. The external multi-path parallel time-sharing selection four-quadrant power switch circuit is realized by n four-quadrant high-frequency power switches capable of bearing bidirectional voltage stress and bidirectional current stress, the bidirectional power flow single-input single-output high-frequency inverter circuit is realized by two or four two-quadrant high-frequency power switches capable of bearing unidirectional voltage stress and bidirectional current stress, and the output cycle conversion circuit is realized by one four-quadrant high-frequency power switch. Specifically, the push-pull, push-pull forward and half-bridge circuits shown in fig. 7, 8 and 9 are formed by n +1 four-quadrant high-frequency power switches capable of bearing bidirectional voltage stress and bidirectional current stress and 2 two-quadrant high-frequency power switches capable of bearing unidirectional voltage stress and bidirectional current stressThe full-bridge circuit shown in fig. 10 is implemented by n +1 four-quadrant high-frequency power switches capable of bearing bidirectional voltage stress and bidirectional current stress, and 4 two-quadrant high-frequency power switches capable of bearing unidirectional voltage stress and bidirectional current stress. It should be added that, in the cycloconverter in the push-pull, push-pull forward, half-bridge, full-bridge circuits shown in fig. 7-10, a four-quadrant high-frequency power switch is drawn by splitting into two-quadrant high-frequency power switches, which are identical in principle; the circuits shown in fig. 7-10 show the case where the input filter is an LC filter (the input filter capacitance of the half-bridge circuit shown in fig. 9 is two bridge arm capacitances C)1、C2) The circuit is not given in space when the input filter is a capacitive filter; the push-pull forward circuit of fig. 8 and the half-bridge circuit of fig. 9 are only suitable for the case where the n input supply voltages are substantially equal; the circuits shown in fig. 7-10 show only the circuit diagram of an output capacitive filter for a passive ac load, and not the circuit diagram of an output capacitive inductive filter for an ac grid load. The external parallel time-sharing selection switch isolates the voltage stress of the power switch of the flyback cyclic single-stage multiple-input inverter topology embodiment, as shown in table 1. In Table 1, Uimax＝max(Ui1，Ui2，…，Uin)，N＝1、2、…、n,UoFor outputting a sinusoidal voltage uoIs determined. The push-pull and push-pull forward circuits are suitable for low-power low-voltage input inversion occasions, and the half-bridge and full-bridge circuits are suitable for low-power high-voltage input inversion occasions. The circuit topology family is suitable for converting a plurality of common-ground unstable input direct-current voltages into a stable and high-quality output alternating current with a required voltage, and can be used for realizing a novel single-stage multiple new energy distributed power supply system with excellent performance and wide application prospect, such as photovoltaic cells 40-60VDC/220V50HzACor115V400HzAC, proton exchange membrane fuel cells 85-120V/220V50HzAC or115V400HzAC, medium and small sized wind power generation 24-36-48VDC/220V50HzAC or115V400HzAC, large wind power generation 510VDC/220V50HzACor115V400HzAC and the like, to supply power to alternating current loads or alternating current power grids.
The energy management control strategy is crucial to various new energy combined power supply systems. Due to the presence of multiple input sources and corresponding power switching units, multiple duty cycles need to be controlled, i.e. there are multiple degrees of freedom of control, which provides the possibility for energy management of multiple new energy sources. The energy management control strategy of the external parallel time-sharing selection switch isolation flyback cyclic single-stage multi-input inverter needs to have three functions of energy management of an input source, MPPT (maximum power point tracking) and output voltage (current) control of new energy power generation equipment such as a photovoltaic cell, a wind driven generator and the like, and sometimes, the strategy also has the three functions of energy management control of the input source and MPPT (maximum power point tracking) and output voltage (current)
Table 1 external parallel time-sharing selection switch isolated flyback cyclic single-stage multiple-input inverter topology embodiment power switch voltage stress
Figure BDA0001543290880000071
The charging and discharging control of the storage battery and the smooth and seamless switching of the system under different power supply modes need to be considered. The external parallel time-sharing selection switch isolation flyback cyclic single-stage multi-input inverter adopts two different energy management modes: (1) in the energy management mode I, namely a master-slave power distribution mode, the power required by a load is known to be provided by the 1 st, 2 nd, … th and n-1 st input sources of the master power supply equipment as much as possible, the input current of the 1 st, 2 nd, … th and n-1 st input sources is given, which is equivalent to the input power of the 1 st, 2 nd, … th and n-1 st input sources, the insufficient power required by the load is provided by the nth input source of the slave power supply equipment, and a storage battery energy storage device does not need to be added; (2) in the energy management mode II, namely the maximum power output mode, the 1 st input source, the 2 nd input source, the … th input source and the n th input source are all output to a load with the maximum power, storage battery energy storage equipment is omitted, the requirement of a grid-connected power generation system on the full utilization of energy is met, and if an output end is connected with a storage battery charging and discharging device in parallel, the stability of the output voltage (current) of an independent power supply system can be realized. When the input voltage of the n paths of new energy sources is given, the input current of the 1 st, 2 nd, … th and n paths of input sources is controlled, so that the input power of the 1 st, 2 nd, … th and n paths of input sources is controlled.
With energy-storage transformers at one output lowThe energy management control strategy of the inverter is discussed by taking a magnetic flux reset in a frequency period, operating in a CCM mode and adopting a constant-frequency SPWM control strategy as an example. An external parallel time-sharing selection switch isolation flyback cyclic single-stage multi-input inverter adopts an output voltage and input current instantaneous value SPWM master-slave power distribution energy management control strategy with four working mode selections to form an independent power supply system; or an input current instantaneous value SPWM maximum power output energy management control strategy with four working mode selections is adopted to form a grid-connected power generation system. The output power of the 1 st, 2 nd, … th input source and the output power of the n-1 st input source are fixed, and the output voltage and input current instantaneous value SPWM of the insufficient power needed by the n-th input source to supplement the load and the control diagram and the control principle waveform of the master-slave power distribution energy management are respectively shown in fig. 11 and 12. In fig. 12, the output filter capacitor CfAnd a load ZLThe parallel equivalent impedance of (2) is inductive, and the fundamental component i of the secondary winding current is inductiveN21Lags behind the output voltage uo. The basic idea of this control scheme is that the operating mode of the inverter is dependent on the output voltage uoAnd secondary winding current iN21The polarity of the converter is divided into four A, B, C, D, and each working mode is equivalent to a flyback direct current converter; the n-input single-output high-frequency inverter circuit inputs n paths of direct-current voltage sources Ui1、Ui2、…、UinUnipolar tri-state multi-slope SPWM current wave i with modulated amplitude distributed according to sinusoidal envelope curveN1Or iN11+iN12The time-sharing conduction time of the 1 st, 2 nd, … th and n-1 th power switches is the total conduction time T in one high-frequency switching period according to the product of the error current and the output voltage error signalonDistributing (realizing maximum power output of 1 st, 2 nd, … th and n-1 st input sources), distributing the rest time as the conduction time of the nth power switch (realizing complement of nth input source power), and demodulating into unipolar tristate single-slope SPWM current wave i with amplitude distributed according to sinusoidal envelope curve by the energy-storage transformer isolation and the cycle converterN2Or iN2++iN2-Filtering to obtain high-quality sinusoidal AC voltage uoOr sinusoidal alternating current io(ii) a By regulating the flowThe voltage error signal, i.e., the total duty cycle, is output to stabilize the inverter output voltage, and the control strategy is applicable to the circuits shown in fig. 7-10. Output voltage feedback signal u of inverterofWith reference sinusoidal voltage urObtaining a voltage error amplification signal u through comparison and amplification of a proportional-integral regulatoreInput current feedback signal I of inverter circuit 1, 2, … and n-1i1f、Ii2f、…、Ii(n-1)fRespectively obtaining reference current signals I after maximum power point calculation with the 1 st, 2 nd, … th and n-1 th input sourcesi1r、Ii2r、…、Ii(n-1)rComparing and amplifying by a proportional-integral regulator, and amplifying a current error signal I1e、I2e、…、I(n-1)eRespectively connected with the voltage error amplified signal ueMultiply to obtain i1e、i2e、…、i(n-1)eAnd its inverse signal-i1e、-i2e、…、-i(n-1)eThen i1e、i2e、…、i(n-1)e、ue、-i1e、-i2e、…、-i(n-1)e、-ueAre respectively matched with the unipolar sawtooth-shaped carrier wave ucComparing, the power switch control signal u of the inverter shown in fig. 7-10 is obtained by considering the output voltage, the output error voltage polarity selection signal and through a proper combinational logic circuitgss1、ugss2、…、ugssn、ugs1(ugs′1)、ugs2(ugs′2)、ugs3、ugs4。
The 1 st, 2 nd, … th and n-1 th circuit current regulators and the n-1 th circuit voltage regulator work independently respectively, the 1 st, 2 nd, … th and n-1 th circuit current regulators are used for realizing the maximum power output of the 1 st, 2 nd, … th and n-1 th circuit input sources, the n-1 th circuit voltage regulator is used for realizing the stabilization of the output voltage of the inverter, and the n-1 th circuit input sources jointly supply power to a load. By regulating the reference voltage u as the input voltage or load variesrAnd a reference current Ii1r、Ii2r、…、Ii(n-1)rOr regulating the feedback voltage uofAnd a feedback current Ii1f、Ii2f、…、Ii(n-1)fTo change the error voltage signalNumber ueAnd an error current signal I1e、I2e、…、I(n-1)eThereby changing the duty ratio d1、d2、…、dnTherefore, the regulation and stabilization of the output voltage and the input current (output power) of the inverter can be realized. When the nth input source in fig. 11-12 is designed as input current feedback to control the input current, an input current instantaneous value SPWM maximum power output energy management control strategy with four kinds of operation mode selection is constructed.
The control principle waveform shown in fig. 12 marks the high frequency switching period TSA certain high frequency switching period TSConduction time T of internal 1 st, 2 nd, … th input sourceon1、Ton2、…、TonnAnd total on-time Ton＝Ton1+Ton2+…+TonnAnd four modes of operation A, B, C, D, total on time TonVarying sinusoidally during one output voltage period, CfAnd ZLWhen the parallel equivalent impedance is inductive, capacitive and resistive, the sequence of the working modes of the inverter is A-B-C-D, D-C-B-A, A-C respectively. In addition, for the half-bridge circuit shown in fig. 9, half of the input dc voltage value (U) should be usedi1/2、Ui2/2、…、UinAnd/2) substituting into the voltage transfer ratio for calculation.
When energy is transferred in the forward direction and the energy storage transformer releases energy to the output end, the primary side of a push-pull type, push-pull forward type, half-bridge type or full-bridge type circuit needs to be prevented from generating a low-impedance loop, and the turn ratio of the energy storage transformer needs to meet the requirement
Figure BDA0001543290880000091
When energy is fed back from the output AC load side to the n-th input DC power supply side UinIn the process, the forward working condition of push-pull, push-pull forward, half-bridge and full-bridge circuits needs to be avoided, namely the turn ratio of the energy storage transformer needs to meet the requirement
Figure BDA0001543290880000092
In view of
Figure BDA0001543290880000093
Figure BDA0001543290880000094
Or (d)1maxUi1/2+d2maxUi2/2+…+dnmaxUin/2)N2/[N1(1-d1max-d2max-…-dnmax)]The maximum duty ratio d of push-pull, push-pull forward, half-bridge and full-bridge circuits can be deduced1max+d2max+…+dnmax≤0.5。
In order to form an independent power supply system capable of fully utilizing energy of multiple input sources, multiple input sources should operate in a maximum power output mode and energy storage equipment needs to be configured to achieve stabilization of output voltage, that is, a single-stage isolation bidirectional charge-discharge converter is connected in parallel to an output end of an inverter, as shown in fig. 13. The single-stage isolation bidirectional charge-discharge converter consists of an input filter (L)i、CiOr Ci) High-frequency inverter, high-frequency transformer, cycle converter, output filter (L)f′、Cf') is cascaded in sequence, and the cycle converter is composed of four-quadrant high-frequency power switches capable of bearing bidirectional voltage stress and bidirectional current stress. The single-stage isolation bidirectional charge-discharge converter is respectively equivalent to a single-stage high-frequency link DC-AC converter and a single-stage high-frequency link AC-DC converter when energy is transmitted in the forward direction (energy storage equipment is discharged) and transmitted in the reverse direction (energy storage equipment is charged).
The independent power supply system adopts a maximum power output energy management control strategy with a single-stage isolated bidirectional charge-discharge converter output voltage independent control loop, as shown in fig. 14. When the load power Po＝UoIoGreater than the sum P of the maximum powers of the plurality of input sources1max+P2max+…+PnmaxWhen the power supply is started, energy storage equipment such as a storage battery, a super capacitor and the like provides needed insufficient power to a load through a single-stage isolation bidirectional charge-discharge converter, namely a power supply mode II, and the energy storage equipment independently provides power to the load, namely a power supply mode III, and belongs to the extreme situation of the power supply mode II;when the load power Po＝UoIoLess than the sum P of the maximum powers of the plurality of input sources1max+P2max+…+PnmaxAnd in the time, the residual energy output by the plurality of input sources is used for charging the energy storage equipment through the single-stage isolation bidirectional charging and discharging converter, namely, the power supply mode I. Using the band elimination load as an example, the power flow direction control of the single-stage isolation bidirectional charge-discharge converter is discussed, as shown in fig. 15. For output filter capacitor Cf、Cf' and load ZLFor example, the parallel connection of the external parallel time-sharing selection switch and the output ends of the isolated flyback periodic-wave single-stage multi-input inverter and the single-stage isolated bidirectional charge-discharge converter is equivalent to the parallel connection and superposition of two current sources. As can be seen from the energy management control strategy shown in fig. 14, the external parallel time-sharing selection switch isolates the output current i of the flyback cyclic single-stage multiple-input inverterLfFundamental component of and output voltage uoThe same frequency and the same phase are adopted, and active power is output; the charging and discharging converter is controlled by the output voltage uoAnd a reference voltage uorefError amplified signal uoeIntercepting with high frequency carrier to generate SPWM signal for control, outputting filter inductor current iLf' and uoThere is a phase difference theta between them, and a different phase difference theta means that active power with different magnitude and direction is output. When P is presento＝P1max+P2max+…+PnmaxWhen theta is equal to 90 degrees, the active power output by the charge-discharge converter is zero, and the charge-discharge converter is in an idle state; when P is presento>P1max+P2max+…+PnmaxWhen u is turned onoThe theta is reduced to be less than 90 degrees, the charging and discharging converter outputs active power, and the energy storage equipment discharges to the load, namely the energy storage equipment provides insufficient power required by the load; when P is presento＜P1max+P2max+…+PnmaxWhen u is turned onoAnd increasing theta to be more than 90 degrees, outputting negative active power by the charging and discharging converter, feeding energy back to the energy storage device by the load, namely charging the energy storage device by residual power output by the plurality of input sources, and feeding the energy back to the energy storage device by the load to be the maximum when the theta is 180 degrees. Thus, the energy management control strategy can be based on PoAnd P1max+P2max+…+PnmaxRelative magnitude real-time controlThe power flow size and direction of the single-stage isolation bidirectional charge-discharge converter are manufactured, and smooth seamless switching of the system under three different power supply modes is realized.

Claims (2)

1. The utility model provides an external parallelly connected timesharing selection switch keeps apart flyback periodic wave type single-stage multiple input inverter which characterized in that: the inverter is formed by sequentially cascading an external bidirectional power flow multi-path parallel time-sharing selection four-quadrant power switch circuit, a bidirectional power flow single-input single-output high-frequency inverter circuit, an energy storage type transformer, a cycle converter and an output filter capacitor, wherein each path of input end of the external bidirectional power flow multi-path parallel time-sharing selection four-quadrant power switch circuit is cascaded with a path of input filter, n paths of input filters are grounded, n is the number of paths of multiple input sources, and n is a natural number greater than 1; each path of the external bidirectional power flow multi-path parallel time-sharing selection four-quadrant power switch circuit is formed by only connecting two-quadrant power switches with two source electrodes connected in series in a reverse direction, output ends of the paths are connected in parallel, a drain electrode of one two-quadrant power switch is connected with an output end of the input filter, a drain electrode of the other two-quadrant power switch is an output end, and only one path of the external bidirectional power flow multi-path parallel time-sharing selection four-quadrant power switch circuit works at any time; the bidirectional power flow single-input single-output high-frequency inverter circuit is a push-pull type, push-pull forward type, half bridge type and full bridge type circuit, wherein the push-pull type circuit consists of two quadrant high-frequency power switches bearing unidirectional voltage stress and bidirectional current stress and an energy storage type transformer primary winding with a center tap; the cycle converter is composed of two quadrant high-frequency power switches bearing unidirectional voltage stress and bidirectional current stress, and the drain electrodes of the two quadrant high-frequency power switches are respectively connected with two ends of the secondary winding of the energy storage transformerThe source electrodes of the two-quadrant high-frequency power switches are respectively connected with two ends of the output filter capacitor; the external bidirectional power flow multi-path parallel time-sharing selection four-quadrant power switch circuit and the bidirectional power flow single-input single-output high-frequency inverter circuit of the inverter input n paths of direct-current voltage sources Ui1、Ui2、…、UinThe modulated level amplitude is distributed according to the sine envelope curve and the rising slope is Ui1/L1、Ui2/L1、…、Uin/L1The single-polarity three-state multi-slope SPWM current wave is demodulated into level amplitude distributed according to a sinusoidal envelope curve through an energy storage type transformer isolation variable current and a cycle converter, and the descending slope is-uo/L2The unipolar three-state single-slope SPWM current wave obtains high-quality sinusoidal alternating-current voltage or grid-connected sinusoidal current on a single-phase alternating-current load after passing through an output filter capacitor, and the rising slopes of the unipolar three-state multi-slope SPWM current wave of only the half-bridge circuit are respectively Ui1/(2L1)、Ui2/(2L1)、…、Uin/(2L1)，L1、L2Inductances u of primary and secondary windings of energy-storage transformers, respectivelyoTo output a sinusoidal voltage transient; the working principle of the inverter is equivalent to the superposition of currents at the input end of a plurality of flyback single-input inverters, namely the output voltage uoThe turn ratio N of the multi-input direct-current voltage source and the energy storage type transformer2/N1Duty ratio d of multi-channel input source1、d2、…、dnThe relationship between is uo＝(d1Ui1+d2Ui2+…+dnUin)N2/[N1(1-d1-d2-…-dn)]Of a half-bridge circuit u onlyo＝(d1Ui1/2+d2Ui2/2+…+dnUin/2)N2/[N1(1-d1-d2-…-dn)](ii) a The voltage stress of the 1 st, 2 nd, … th and n-th parallel time-sharing selection four-quadrant power switch is respectively
Figure FDA0002393292990000011
Figure FDA0002393292990000021
The voltage stress of the two-quadrant power switch of the push-pull type, push-pull forward type high-frequency inverter circuit and the cycle converter is respectively 2Uimax、
Figure FDA0002393292990000022
The voltage stress of the two-quadrant power switch of the half-bridge high-frequency inverter circuit and the cycle converter is respectively Uimax、
Figure FDA0002393292990000023
The voltage stress of the full-bridge high-frequency inverter circuit and the voltage stress of the two-quadrant power switch of the cyclic converter are respectively Uimax、
Figure FDA0002393292990000024
Uimax＝max(Ui1，Ui2，…，Uin)，N＝1、2、…、n，UoOutputting a sine voltage effective value; an independent power supply system formed by the inverter adopts an output voltage and input current instantaneous value SPWM master-slave power distribution energy management control strategy with four working mode selections, wherein the output power of a 1 st input source, a 2 nd input source, an … th input source and an n-1 th input source are fixed, and the insufficient power required by a supplementary load of the n-1 th input source is adopted, and a grid-connected power generation system formed by the inverter adopts a 1 st input source, a 2 nd input source, an … th input source and an n-1 th input source input current instantaneous value feedback SPWM maximum power output energy management control strategy with four working mode selections; dividing the inverter according to the polarity of output voltage of the inverter and the polarity of a fundamental component of secondary winding current of the energy storage type transformer, wherein the inverter has four working modes A, B, C, D, each working mode is equivalent to a flyback direct current converter, and the sequence of the working modes of the inverter when the output filter capacitor and the parallel equivalent impedance of an alternating current load are inductive, capacitive and resistive is A-B-C-D, D-C-B-A, A-C respectively; energy storage type transformer without low impedance loop of primary circuit during forward energy transfer and energy releasing to loadThe turn ratio of the transformer should satisfy
Figure FDA0002393292990000025
Or min (U)i1/2、Ui2/2、…、Uin/2), the turn ratio of the energy storage type transformer is required to meet the condition that the energy is reversely fed back to the nth input source without forward operation
Figure FDA0002393292990000026
Or Uin/2 according to
Figure FDA0002393292990000027
Or (d)1maxUi1/2+d2maxUi2/2+…+dnmaxUin/2)N2/[N1(1-d1max-d2max-…-dnmax)]The sum d of the maximum duty cycles of the multi-input sources of the push-pull type, push-pull forward type, half-bridge type and full-bridge type circuits can be deduced1max+d2max+…+dnmaxLess than or equal to 0.5; the inverter determines the number of input sources needing to be put into operation by controlling the on and off of n external parallel time-sharing selection four-quadrant power switches according to the size of an alternating current load, wherein the n input sources are U-shaped in one high-frequency switching periodi1、Ui2、…、UinThe power is supplied to the AC load in parallel connection in sequence and time sharing, so that the single-stage high-efficiency isolation step-up/step-down inversion of n common-ground unstable input DC voltages into stable high-quality sinusoidal AC power required by one load is realized.
2. The external parallel time-sharing selection switch isolated flyback cyclic single-stage multiple-input inverter of claim 1, wherein: the output end of the external parallel time-sharing selection switch isolation flyback periodic wave type single-stage multi-input inverter is connected with a single-stage isolation bidirectional charge-discharge converter of the energy storage device in parallel, so that an independent power supply system capable of fully utilizing the energy of the n input sources and stable in output voltage is formed; the single-stage isolation bidirectional charge-discharge converter is formed by sequentially cascading an input filter, a high-frequency inverter, a high-frequency transformer, a cycle converter and an output filter, wherein the cycle converter is formed by a four-quadrant high-frequency power switch capable of bearing bidirectional voltage stress and bidirectional current stress, and the single-stage isolation bidirectional charge-discharge converter is respectively equivalent to a single-stage voltage type high-frequency link DC-AC converter and a single-stage current type high-frequency link AC-DC converter when the energy storage equipment is discharged and charged; the independent power supply system adopts a management control strategy of the maximum power output energy of n input sources with a single-stage isolation bidirectional charge-discharge converter output voltage independent control loop, the n input sources all work in a maximum power output mode, the power flow size and direction of the single-stage isolation bidirectional charge-discharge converter are controlled in real time according to the relative size of the sum of the load power and the maximum power of the n input sources, and the smooth seamless switching of the output voltage of the system and the charge and discharge of energy storage equipment is realized; when the load power is greater than the sum of the maximum powers of the n input sources, the system works in a power supply mode II in which the energy storage device provides required insufficient power to the load through the single-stage isolation bidirectional charge-discharge converter, a power supply mode III in which the energy storage device supplies power to the load independently belongs to the extreme situation of the power supply mode II, and when the load power is less than the sum of the maximum powers of the n input sources, the system works in a power supply mode I in which the residual energy output by the n input sources charges the energy storage device through the single-stage isolation bidirectional charge-discharge converter; for the output filter capacitor and the load, the output ends of the isolated flyback periodic-wave single-stage multi-input inverter and the isolated single-stage bidirectional charge-discharge converter of the external parallel time-sharing selection switch are connected in parallel and are equivalent to the parallel superposition of two current sources; the method comprises the steps that 1, 2, … and n paths of input source output currents are subjected to error amplification with 1, 2, … and n paths of input source maximum power point reference currents respectively, the 1 st, 2, … and n paths of error amplification signals are multiplied by sinusoidal synchronous signals and then are intersected with the same high-frequency carrier signal respectively to generate 1 st, 2 nd, … and n paths of signals to control an n path of input inverter, the n path of input inverter outputs filtering inductive currents which are in the same frequency and the same phase as output voltages and outputs active power, and SPWM signals are generated by the intersection of the error amplification signals of the system output voltages and the reference voltages and the high-frequency carrier signals to control the output filtering inductive currents and the system output voltages of the charge-discharge converter, wherein phase differences theta and different phase differences theta mean that active power with different magnitudes and directions are output; when the load power is equal to the sum of the maximum powers of the n input sources, theta is equal to 90 degrees, the active power output by the charging and discharging converter is zero, when the load power is larger than the sum of the maximum powers of the n input sources, the output voltage is reduced, theta is smaller than 90 degrees, the charging and discharging converter outputs the active power, namely the insufficient power required by the load by the energy storage device, when the load power is smaller than the sum of the maximum powers of the n input sources, the output voltage is increased, theta is larger than 90 degrees, and the charging and discharging converter outputs the negative active power, namely the residual power output by the n input sources to charge the.
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