CN116683774A - Micro inverter, control method thereof and photovoltaic system comprising micro inverter - Google Patents

Micro inverter, control method thereof and photovoltaic system comprising micro inverter Download PDF

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Publication number
CN116683774A
CN116683774A CN202310675090.3A CN202310675090A CN116683774A CN 116683774 A CN116683774 A CN 116683774A CN 202310675090 A CN202310675090 A CN 202310675090A CN 116683774 A CN116683774 A CN 116683774A
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CN
China
Prior art keywords
switching tube
bridge
leg
inverter
micro
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202310675090.3A
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Chinese (zh)
Inventor
王凡
王立祥
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Qingdao North Chaoneng Electric Co ltd
Suzhou Enyipu Technology Co ltd
Original Assignee
Qingdao North Chaoneng Electric Co ltd
Suzhou Enyipu Technology Co ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Application filed by Qingdao North Chaoneng Electric Co ltd, Suzhou Enyipu Technology Co ltd filed Critical Qingdao North Chaoneng Electric Co ltd
Priority to CN202310675090.3A priority Critical patent/CN116683774A/en
Publication of CN116683774A publication Critical patent/CN116683774A/en
Pending legal-status Critical Current

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Classifications

    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS 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
    • H02M3/00Conversion of dc power input into dc power output
    • H02M3/22Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28Conversion 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
    • H02M3/325Conversion 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
    • H02M3/335Conversion 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
    • H02M3/33569Conversion 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
    • H02M3/33576Conversion 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
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02JCIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381Dispersed generators
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS 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
    • H02M3/00Conversion of dc power input into dc power output
    • H02M3/22Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28Conversion 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
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS 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
    • H02M3/00Conversion of dc power input into dc power output
    • H02M3/22Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28Conversion 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
    • H02M3/325Conversion 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
    • H02M3/335Conversion 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
    • H02M3/33569Conversion 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
    • H02M3/33573Full-bridge at primary side of an isolation transformer
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS 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
    • H02M7/00Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48Conversion 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
    • H02M7/4815Resonant converters
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS 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
    • H02M7/00Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48Conversion 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
    • H02M7/53Conversion 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
    • H02M7/537Conversion 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
    • H02M7/5387Conversion 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
    • H02M7/53871Conversion 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 with automatic control of output voltage or current
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02SGENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
    • H02S40/00Components or accessories in combination with PV modules, not provided for in groups H02S10/00 - H02S30/00
    • H02S40/30Electrical components
    • H02S40/32Electrical components comprising DC/AC inverter means associated with the PV module itself, e.g. AC modules
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02JCIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20The dispersed energy generation being of renewable origin
    • H02J2300/22The renewable source being solar energy
    • H02J2300/24The renewable source being solar energy of photovoltaic origin
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/50Photovoltaic [PV] energy
    • Y02E10/56Power conversion systems, e.g. maximum power point trackers

Landscapes

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

Abstract

The invention relates in particular to a micro-inverter, a control method thereof and a photovoltaic system comprising the micro-inverter. The micro inverter comprises a transformer, a first H bridge, a second H bridge and a third H bridge; the transformer comprises a primary winding and a secondary winding; the input end of the first H bridge is used as the input end of the micro inverter to be connected with a direct current source, the output end of the first H bridge is connected with the primary winding, the input end of the second H bridge is connected with the secondary winding, the output end of the second H bridge is connected with the input end of the third H bridge, and the output end of the third H bridge is used as the output end of the micro inverter to be connected with a power grid; the first H-bridge includes first to fourth switching tubes, the second H-bridge includes fifth to eighth switching tubes, and the third H-bridge includes ninth to twelfth switching tubes. The invention reduces loss, improves efficiency, reduces volume and reduces cost.

Description

Micro inverter, control method thereof and photovoltaic system comprising micro inverter
Technical Field
The invention relates in particular to a micro-inverter, a control method thereof and a photovoltaic system comprising the micro-inverter.
Background
The micro inverter has received a lot of attention because it can realize MPPT (Maximum Power Point Tracking ) at the module level for the electricity generation between every photovoltaic module is not mutually influenced, and does not have the short-circuit effect of module series connection, and the partial shielding and the inconsistent orientation of subassembly also can not influence the generated energy of whole cluster subassembly, can realize the operation and maintenance at the module level moreover, so has received extensive attention.
In practical applications, the micro-inverter usually uses diodes for rectification, and uses bus capacitors for filtering the rectified dc current. The scheme has the advantages of simple circuit structure, no need of a driving circuit to drive the diode, simpler control algorithm, no need of considering the problem of the direction angle of the switching tube, and smooth and stable direct-current voltage on the bus capacitor. However, the diode can generate voltage drop when being conducted, when the current is larger, the diode can generate larger loss, the whole machine efficiency is reduced, the heat dissipation requirement is higher, larger heat dissipation fins are needed for heat dissipation, and meanwhile, the volume of the bus capacitor with high voltage and high capacity is larger, so that the whole machine volume is greatly increased, the power density of the whole machine is reduced, and the whole machine cost is increased.
Disclosure of Invention
The invention aims to provide a micro-inverter, a control method thereof and a photovoltaic system comprising the micro-inverter, which reduce loss, improve efficiency, reduce volume and reduce cost.
The invention discloses a micro inverter, which comprises a transformer, a first H bridge, a second H bridge and a third H bridge;
the transformer comprises a primary winding and a secondary winding; the input end of the first H bridge is used as the input end of the micro inverter to be connected with a direct current source, the output end of the first H bridge is connected with the primary winding, the input end of the second H bridge is connected with the secondary winding, the output end of the second H bridge is connected with the input end of the third H bridge, and the output end of the third H bridge is used as the output end of the micro inverter to be connected with a power grid;
the first H-bridge includes first to fourth switching tubes, the second H-bridge includes fifth to eighth switching tubes, and the third H-bridge includes ninth to twelfth switching tubes.
Optionally, the first capacitor is further included, and the first capacitor is disposed at an input end of the first H-bridge.
Optionally, the first inductor and the second capacitor form a resonant network, and are arranged between the secondary winding and the input end of the second H-bridge.
Optionally, the first inductance is leakage inductance between the primary winding and the secondary winding.
Optionally, the filter further comprises a second inductor and a third capacitor, wherein the second inductor and the third capacitor form a filter network and are arranged at the output end of the third H bridge.
The invention discloses a photovoltaic system comprising the micro inverter described above, and further comprising a photovoltaic module as a direct current source;
and the input end of the micro inverter is connected with the photovoltaic module.
And the output end of the micro inverter is connected with a power grid.
The invention discloses a control method of a micro inverter, wherein the micro inverter is the micro inverter described above, a first H bridge comprises a first bridge arm and a second bridge arm, a first switching tube and a second switching tube are respectively arranged on an upper bridge arm and a lower bridge arm of the first bridge arm, a third switching tube and a fourth switching tube are respectively arranged on an upper bridge arm and a lower bridge arm of the second bridge arm, and the method comprises the following steps:
and controlling the switching actions of the first switching tube to the fourth switching tube, so that the first switching tube and the fourth switching tube are switched on when the second switching tube and the third switching tube are switched off, and the second switching tube and the third switching tube are switched on when the first switching tube and the fourth switching tube are switched off, and the direct current output by the direct current source is inverted into high-frequency alternating current through the first H bridge.
Optionally, the method further comprises:
the angle of movement between the first switching tube and the fourth switching tube is controlled such that the energy transferred from the primary winding to the secondary winding of the transformer becomes larger when the angle of movement becomes smaller, and the energy transferred from the primary winding to the secondary winding becomes smaller when the angle of movement becomes larger.
Optionally, the second H-bridge includes a third leg and a fourth leg, a fifth switching tube and a sixth switching tube are respectively disposed on an upper leg and a lower leg of the third leg, a seventh switching tube and an eighth switching tube are respectively disposed on an upper leg and a lower leg of the fourth leg, and the method includes:
and controlling the switching actions of the fifth switching tube to the eighth switching tube, so that the fifth switching tube and the eighth switching tube are switched on when the sixth switching tube and the seventh switching tube are switched off, and the sixth switching tube and the seventh switching tube are switched on when the fifth switching tube and the eighth switching tube are switched off, and thereby the high-frequency alternating current output by the secondary winding of the transformer is rectified into high-frequency direct current through the second H bridge.
Optionally, the third H-bridge includes a fifth leg and a sixth leg, a ninth switching tube and a tenth switching tube are respectively disposed on an upper leg and a lower leg of the fifth leg, an eleventh switching tube and a twelfth switching tube are respectively disposed on an upper leg and a lower leg of the sixth leg, and the method includes:
and controlling the switching actions of the ninth switching tube to the twelfth switching tube, so that the ninth switching tube and the twelfth switching tube are switched on when the tenth switching tube and the eleventh switching tube are switched off, and the tenth switching tube and the eleventh switching tube are switched on when the ninth switching tube and the twelfth switching tube are switched off, and the high-frequency direct current output by the second H bridge is inverted into power frequency alternating current through the third H bridge and is combined into a power grid.
Compared with the prior art, the invention has the main differences and effects that:
the invention can realize high-frequency inversion through the first H bridge, realize high-frequency rectification through the second H bridge and realize power frequency inversion through the third H bridge, thereby being capable of integrating the power generated by the photovoltaic module into a power grid. The second H bridge can adopt a switching tube rectification scheme, compared with a diode rectification scheme, the switching tube rectification conduction loss is smaller, the efficiency is improved, and the heat dissipation requirement is lower. The micro inverter does not need to adopt a bus capacitor, thereby reducing the volume, improving the power density and reducing the cost.
Drawings
FIG. 1 is a schematic diagram of a photovoltaic system including a micro-inverter according to an embodiment of the present invention;
FIG. 2 is a schematic waveform of a primary winding current and a control signal for a first H-bridge according to an embodiment of the present invention;
fig. 3 is a waveform schematic diagram of control signals for a first switching tube and a fourth switching tube of a first H-bridge according to an embodiment of the invention;
FIG. 4 is a schematic waveform of the secondary winding current and a schematic waveform of the control signal for the second H-bridge in accordance with an embodiment of the invention;
FIG. 5 is a schematic waveform of the secondary winding current and a schematic waveform of the high frequency DC current rectified by the second H-bridge in accordance with an embodiment of the present invention;
fig. 6 is a schematic waveform of a high-frequency dc current rectified by a second H-bridge, a schematic waveform of a power-frequency ac current inverted by a third H-bridge, and a schematic waveform of a power-frequency ac current filtered by a filter network according to an embodiment of the present invention.
Detailed Description
In order to make the purpose and technical solutions of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. It will be apparent that the described embodiments are some, but not all, embodiments of the invention. All other embodiments, which can be made by a person skilled in the art without creative efforts, based on the described embodiments of the present invention fall within the protection scope of the present invention.
A first embodiment of the invention relates to a photovoltaic system comprising a micro-inverter. Fig. 1 is a schematic diagram of a photovoltaic system including a micro-inverter according to an embodiment of the present invention. The following is a detailed description with reference to fig. 1.
As shown in fig. 1, the photovoltaic system 10 may include a micro-inverter that may include a transformer T1, a first H-bridge 101, a second H-bridge 102, and a third H-bridge 103.
The transformer T1 may include a primary winding and a secondary winding, and the transformer T1 may function to isolate and step up and down voltages.
The input of the first H-bridge 101 may be used as an input of a micro-inverter for connection to a direct current source 201, which direct current source 201 may be a photovoltaic module in the photovoltaic system 10, and in other embodiments may be a load such as a battery, and the output of the first H-bridge 101 may be connected to a primary winding. The first H-bridge 101 may be a full-bridge circuit structure, which may include a first leg and a second leg, and each leg may include an upper leg and a lower leg connected in series. A first switching tube Q1 may be disposed on an upper leg of the first leg, a second switching tube Q2 may be disposed on a lower leg of the first leg, a third switching tube Q3 may be disposed on an upper leg of the second leg, and a fourth switching tube Q4 may be disposed on a lower leg of the second leg. The first bridge arm and the second bridge arm may be connected in parallel with the dc source 201, and midpoints of the first bridge arm and the second bridge arm may be connected to two ends of the primary winding of the transformer T1, respectively.
An input of the second H-bridge 102 may be connected to the secondary winding and an output of the second H-bridge 102 may be connected to an input of the third H-bridge 103. The second H-bridge 102 may be a full-bridge circuit structure that may include a third leg and a fourth leg, and each leg may include an upper leg and a lower leg connected in series. A fifth switching tube Q5 may be disposed on an upper leg of the third leg, a sixth switching tube Q6 may be disposed on a lower leg of the third leg, a seventh switching tube Q7 may be disposed on an upper leg of the fourth leg, and an eighth switching tube Q8 may be disposed on a lower leg of the fourth leg. The midpoints of the third bridge arm and the fourth bridge arm can be respectively connected with two ends of the secondary winding of the transformer T1.
The output of the third H-bridge 103 may be used as the output of the micro-inverter for connecting to the Grid. Third H-bridge 103 may be a full-bridge circuit structure that may include a fifth leg and a sixth leg, and each leg may include an upper leg and a lower leg connected in series. A ninth switching tube Q9 may be provided on the upper leg of the fifth leg, a tenth switching tube Q10 may be provided on the lower leg of the fifth leg, an eleventh switching tube Q11 may be provided on the upper leg of the sixth leg, and a twelfth switching tube Q12 may be provided on the lower leg of the sixth leg. The fifth bridge arm, the sixth bridge arm, the third bridge arm and the fourth bridge arm can be connected in parallel, and midpoints of the fifth bridge arm and the sixth bridge arm can be respectively connected with two ends of the Grid.
The invention can realize high-frequency inversion through the first H bridge, realize high-frequency rectification through the second H bridge and realize power frequency inversion through the third H bridge, thereby being capable of integrating the power generated by the photovoltaic module into a power grid. The second H bridge can adopt a switching tube rectification scheme, compared with a diode rectification scheme, the switching tube rectification conduction loss is smaller, the efficiency is improved, and the heat dissipation requirement is lower. The micro inverter does not need to adopt a bus capacitor, thereby reducing the volume, improving the power density and reducing the cost.
In one embodiment, the micro-inverter may further include a first capacitor C1, and the first capacitor C1 may be disposed at an input terminal of the first H-bridge 101. Specifically, the first capacitor C1 may be connected in parallel with the dc source 201 and the first and second legs of the first H-bridge 101. The first capacitor C1 may be used as a filter capacitor to reduce the voltage ripple on the left side thereof. When the photovoltaic module is connected to the left side, MPPT tracking accuracy of the photovoltaic system can be improved, and when the load such as a battery is arranged on the left side, small voltage ripple can effectively meet ripple voltage requirements of the load.
In one embodiment, the micro-inverter may further include a first inductance L1 and a second capacitance C2, and the first inductance L1 and the second capacitance C2 may form the resonant network 104 and may be disposed between the secondary winding and the input of the second H-bridge 102. Specifically, the first inductor L1 may be connected in series between one end of the secondary winding and a midpoint of the third leg of the second H-bridge 102, and the second capacitor C2 may be connected in series between the other end of the secondary winding and a midpoint of the fourth leg of the second H-bridge 102. The existence of the resonant network 104 can enable the switching tubes in the first H bridge 101 and the second H bridge 102 to realize ZVS (Zero Voltage Switch, zero voltage switching), reduce the switching loss of the high-frequency switching tube and effectively improve the overall efficiency.
In one embodiment, the first inductor L1 may be an independent inductor device, and in another embodiment, the first inductor L1 may be a leakage inductance between the primary winding and the secondary winding, and the leakage inductance may be used as a resonant inductance in a circuit, so as to realize magnetic integration, and help to improve the power density of the whole machine.
In one embodiment, the micro-inverter may further include a second inductor L2 and a third capacitor C3, and the second inductor L2 and the third capacitor C3 may form the filter network 105 and may be disposed at an output terminal of the third H-bridge 103. Specifically, the second inductor L2 may be connected in series at a midpoint of the fifth leg of the third H-bridge 103 and one end of the Grid, and the third capacitor C3 may be connected in parallel with the Grid. The presence of the filter network 105 can enable the filtering of the interference signals of the direct current input end, so as to avoid affecting the normal operation of the power grid.
In one embodiment, the switching actions of the first to fourth switching transistors Q1 to Q4 may be controlled such that the first and fourth switching transistors Q1 and Q4 may be turned on when the second and third switching transistors Q2 and Q3 are turned off, and the second and third switching transistors Q2 and Q3 may be turned on when the first and fourth switching transistors Q1 and Q4 are turned off, so that the direct current output from the direct current source 201 may be inverted into a high frequency alternating current through the first H bridge 101.
Fig. 2 is a schematic waveform of a primary winding current and a schematic waveform of a control signal for a first H-bridge according to an embodiment of the invention. The following is a detailed description with reference to fig. 2.
As shown in fig. 2, the current I1 may be a primary winding current, and the first to fourth signals Vg1 to Vg4 may be gate driving signals of the first to fourth switching transistors Q1 to Q4, respectively.
When the second signal Vg2 and the third signal Vg3 are at low level, the second switching tube Q2 and the third switching tube Q3 may be turned off, the current I1 may be positive, at this time, the current I1 may flow through the first switching tube Q1 and the fourth switching tube Q4, the first signal Vg1 and the fourth signal Vg4 may be set at high level, and the first switching tube Q1 and the fourth switching tube Q4 may be turned on for ZVS.
When the first signal Vg1 and the fourth signal Vg4 are at low level, the first switching tube Q1 and the fourth switching tube Q4 may be turned off, the current I1 may be negative, at this time, the current I1 may flow through the second switching tube Q2 and the third switching tube Q3, the second signal Vg2 and the third signal Vg3 may be set at high level, and the second switching tube Q2 and the third switching tube Q3 may be turned on for ZVS.
In one embodiment, the shift angle between the first switching tube Q1 and the fourth switching tube Q4 may be controlled such that the energy transferred from the primary winding to the secondary winding of the transformer T1 may become larger when the shift angle becomes smaller, and the energy transferred from the primary winding to the secondary winding may become smaller when the shift angle becomes larger.
Fig. 3 is a waveform schematic diagram of control signals for a first switching tube and a fourth switching tube of a first H-bridge according to an embodiment of the invention. The details are described below in connection with fig. 3.
As shown in fig. 3, the first signal Vg1 and the fourth signal Vg4 may be gate driving signals of the first switching transistor Q1 and the fourth switching transistor Q4, respectively.
By controlling the phase shift angle between the first signal Vg1 and the fourth signal Vg4, the magnitude of the output energy of the transformer T1 can be controlled, and the smaller the phase shift angle, the larger the output energy, and conversely, the smaller the output energy.
In one embodiment, the switching actions of the fifth to eighth switching tubes Q5 to Q8 may be controlled such that the fifth and eighth switching tubes Q5 and Q8 may be turned on when the sixth and seventh switching tubes Q6 and Q7 are turned off, and the sixth and seventh switching tubes Q6 and Q7 may be turned on when the fifth and eighth switching tubes Q5 and Q8 are turned off, so that the high frequency ac current output from the secondary winding of the transformer T1 may be rectified into the high frequency dc current through the second H bridge 102.
Fig. 4 is a schematic waveform of the secondary winding current and a schematic waveform of the control signal for the second H-bridge according to an embodiment of the invention. The details are described below in connection with fig. 4.
As shown in fig. 4, the current I2 may be a secondary winding current, and the fifth to eighth signals Vg5 to Vg8 may be gate driving signals of the fifth to eighth switching transistors Q5 to Q8, respectively.
When the sixth signal Vg6 and the seventh signal Vg7 are at the low level, the sixth switching tube Q6 and the seventh switching tube Q7 may be turned off, the current I2 may be positive, at this time, the current I2 may flow through the fifth switching tube Q5 and the eighth switching tube Q8, the fifth signal Vg5 and the eighth signal Vg8 may be set at the high level, and the fifth switching tube Q5 and the eighth switching tube Q8 may be turned on to realize ZVS.
When the fifth signal Vg5 and the eighth signal Vg8 are at the low level, the fifth switching tube Q5 and the eighth switching tube Q8 may be turned off, the current I2 may be negative, the current I1 may flow through the sixth switching tube Q6 and the seventh switching tube Q7, the sixth signal Vg6 and the seventh signal Vg7 may be set at the high level, and the sixth switching tube Q6 and the seventh switching tube Q7 may be turned on to realize ZVS.
Fig. 5 is a schematic waveform diagram of the secondary winding current and a schematic waveform diagram of the high frequency dc current rectified by the second H-bridge according to an embodiment of the present invention. The details are described below in connection with fig. 5.
As shown in fig. 5, the current I2 may be a secondary winding current, and the current I3 may be a high frequency direct current rectified by the second H-bridge 102. The high-frequency alternating current I2 can be rectified into a high-frequency direct current I3 by the second H-bridge 102.
In one embodiment, the switching actions of the ninth to twelfth switching transistors Q9 to Q12 may be controlled such that the ninth and twelfth switching transistors Q9 and Q12 may be turned on when the tenth and eleventh switching transistors Q10 and Q11 are turned off and the tenth and eleventh switching transistors Q10 and Q11 may be turned on when the ninth and twelfth switching transistors Q9 and Q12 are turned off, so that the high frequency direct current output from the second H bridge 102 may be inverted into a power frequency alternating current through the third H bridge 103 and incorporated into the Grid.
Fig. 6 is a schematic waveform of a high-frequency dc current rectified by a second H-bridge, a schematic waveform of a power-frequency ac current inverted by a third H-bridge, and a schematic waveform of a power-frequency ac current filtered by a filter network according to an embodiment of the present invention. The details are described below in connection with fig. 6.
As shown in fig. 6, the current I3 may be a high frequency dc current rectified by the second H-bridge 102, the current I4 may be a power frequency ac current inverted by the third H-bridge 103, and the current I5 may be a power frequency ac current filtered by the filter network 105. Through the third H-bridge 103, the high frequency direct current I3 may be inverted to a power frequency alternating current I4, and through the filter network 105, the power frequency alternating current I4 may be filtered to a power frequency alternating current I5 to be incorporated into the power Grid.
A second embodiment of the present invention relates to a micro inverter that may be the micro inverter already described in the first embodiment, and may include a transformer, a first H-bridge, a second H-bridge, and a third H-bridge;
the transformer may include a primary winding and a secondary winding; the input end of the first H bridge can be used as the input end of the micro inverter for connecting a direct current source, the output end of the first H bridge can be connected with a primary winding, the input end of the second H bridge can be connected with a secondary winding, the output end of the second H bridge can be connected with the input end of the third H bridge, and the output end of the third H bridge can be used as the output end of the micro inverter for connecting a power grid;
the first H-bridge may include first to fourth switching tubes, the second H-bridge may include fifth to eighth switching tubes, and the third H-bridge may include ninth to twelfth switching tubes.
In one embodiment, the micro-inverter may further include a first capacitor, which may be disposed at an input of the first H-bridge.
In one embodiment, the micro-inverter may further include a first inductor and a second capacitor, which may form a resonant network, and may be disposed between the secondary winding and an input of the second H-bridge.
In one embodiment, the first inductance may be leakage inductance between the primary winding and the secondary winding.
In one embodiment, the micro-inverter may further include a second inductor and a third capacitor, which may form a filter network, and may be disposed at an output of the third H-bridge.
The first embodiment is a system embodiment corresponding to the present embodiment, and the present embodiment can be implemented in cooperation with the first embodiment. The related technical details mentioned in the first embodiment are still valid in this embodiment, and in order to reduce repetition, a detailed description is omitted here. Accordingly, the related art details mentioned in the present embodiment can also be applied to the first embodiment.
A third embodiment of the present invention relates to a control method of a micro inverter, which may be the micro inverter already described in the first and second embodiments, and in which the first H-bridge includes a first leg and a second leg, the first switching tube and the second switching tube may be disposed at an upper leg and a lower leg of the first leg, respectively, the third switching tube and the fourth switching tube may be disposed at an upper leg and a lower leg of the second leg, respectively, and the method may include:
the switching actions of the first switching tube to the fourth switching tube can be controlled, so that the first switching tube and the fourth switching tube can be switched on when the second switching tube and the third switching tube are switched off, and the second switching tube and the third switching tube can be switched on when the first switching tube and the fourth switching tube are switched off, and the direct current output by the direct current source can be inverted into high-frequency alternating current through the first H bridge.
In one embodiment, the method may further comprise:
the angle of movement between the first switching tube and the fourth switching tube may be controlled such that energy transferred from the primary winding to the secondary winding of the transformer may become larger when the angle of movement becomes smaller, and energy transferred from the primary winding to the secondary winding may become smaller when the angle of movement becomes larger.
In one embodiment, the second H-bridge includes a third leg and a fourth leg, the fifth switching tube and the sixth switching tube may be disposed on an upper leg and a lower leg of the third leg, respectively, the seventh switching tube and the eighth switching tube may be disposed on an upper leg and a lower leg of the fourth leg, respectively, and the method may include:
the switching actions of the fifth switching tube to the eighth switching tube can be controlled, so that the fifth switching tube and the eighth switching tube can be switched on when the sixth switching tube and the seventh switching tube are switched off, and the sixth switching tube and the seventh switching tube can be switched on when the fifth switching tube and the eighth switching tube are switched off, and therefore high-frequency alternating current output by the secondary winding of the transformer can be rectified into high-frequency direct current through the second H bridge.
In one embodiment, the third H-bridge includes a fifth leg and a sixth leg, the ninth switching tube and the tenth switching tube may be disposed on an upper leg and a lower leg of the fifth leg, respectively, the eleventh switching tube and the twelfth switching tube may be disposed on an upper leg and a lower leg of the sixth leg, respectively, and the method may include:
the switching actions of the ninth switching tube and the twelfth switching tube can be controlled, so that the ninth switching tube and the twelfth switching tube can be switched on when the tenth switching tube and the eleventh switching tube are switched off, and the tenth switching tube and the eleventh switching tube can be switched on when the ninth switching tube and the twelfth switching tube are switched off, and the high-frequency direct current output by the second H bridge can be inverted into power frequency alternating current through the third H bridge to be integrated into a power grid.
The first embodiment and the second embodiment are a system embodiment and an apparatus embodiment corresponding to the present embodiment, respectively, and the present embodiment can be implemented in cooperation with the first embodiment and the second embodiment. The related technical details mentioned in the first embodiment and the second embodiment are still valid in this embodiment, and in order to reduce repetition, a detailed description is omitted here. Accordingly, the related technical details mentioned in the present embodiment can also be applied to the first embodiment and the second embodiment.
It should be noted that, each method embodiment of the present invention may be implemented in software, hardware, firmware, or the like. Regardless of whether the invention is implemented in software, hardware, or firmware, the instruction code may be stored in any type of computer accessible memory (e.g., permanent or modifiable, volatile or non-volatile, solid or non-solid, fixed or removable media, etc.). Also, the Memory may be, for example, programmable array logic (Programmable Array Logic, abbreviated as "PAL"), random access Memory (Random Access Memory, abbreviated as "RAM"), programmable Read-Only Memory (Programmable Read Only Memory, abbreviated as "PROM"), read-Only Memory (ROM), electrically erasable programmable Read-Only Memory (Electrically Erasable Programmable ROM, abbreviated as "EEPROM"), magnetic disk, optical disk, digital versatile disk (Digital Versatile Disc, abbreviated as "DVD"), and the like.
It should be noted that, in each embodiment of the present invention, each unit/module mentioned in each embodiment of the device is a logic unit/module, and in physical terms, one logic unit may be a physical unit, or may be a part of a physical unit, or may be implemented by a combination of multiple physical units, where the physical implementation manner of the logic unit itself is not the most important, and the combination of functions implemented by the logic units is the key to solve the technical problem posed by the present invention. Furthermore, in order to highlight the innovative part of the present invention, the above-described device embodiments of the present invention do not introduce elements that are less closely related to solving the technical problem posed by the present invention, which does not indicate that the above-described device embodiments do not have other elements.
It should be noted that in the claims and the description of this patent, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

Claims (10)

1. The miniature inverter is characterized by comprising a transformer, a first H bridge, a second H bridge and a third H bridge;
the transformer comprises a primary winding and a secondary winding; the input end of the first H bridge is used as the input end of the micro inverter to be connected with a direct current source, the output end of the first H bridge is connected with the primary winding, the input end of the second H bridge is connected with the secondary winding, the output end of the second H bridge is connected with the input end of the third H bridge, and the output end of the third H bridge is used as the output end of the micro inverter to be connected with a power grid;
the first H-bridge includes first to fourth switching tubes, the second H-bridge includes fifth to eighth switching tubes, and the third H-bridge includes ninth to twelfth switching tubes.
2. The micro-inverter of claim 1, further comprising a first capacitor disposed at an input of the first H-bridge.
3. The micro-inverter of claim 1, further comprising a first inductance and a second capacitance, the first inductance and the second capacitance forming a resonant network and being disposed between the secondary winding and an input of the second H-bridge.
4. The micro-inverter of claim 3, wherein the first inductance is leakage inductance between the primary winding and the secondary winding.
5. The micro-inverter of claim 1, further comprising a second inductor and a third capacitor, the second inductor and the third capacitor forming a filter network and being disposed at an output of the third H-bridge.
6. A photovoltaic system comprising the micro-inverter according to any one of claims 1 to 5, and further comprising a photovoltaic module as a direct current source;
and the input end of the micro inverter is connected with the photovoltaic module.
And the output end of the micro inverter is connected with a power grid.
7. A control method of a micro inverter according to any one of claims 1 to 5, wherein a first H-bridge includes a first leg and a second leg, a first switching tube and a second switching tube are provided at an upper leg and a lower leg of the first leg, respectively, a third switching tube and a fourth switching tube are provided at an upper leg and a lower leg of the second leg, respectively, and the method includes:
and controlling the switching actions of the first switching tube to the fourth switching tube, so that the first switching tube and the fourth switching tube are switched on when the second switching tube and the third switching tube are switched off, and the second switching tube and the third switching tube are switched on when the first switching tube and the fourth switching tube are switched off, and the direct current output by the direct current source is inverted into high-frequency alternating current through the first H bridge.
8. The method of claim 7, wherein the method further comprises:
the angle of movement between the first switching tube and the fourth switching tube is controlled such that the energy transferred from the primary winding to the secondary winding of the transformer becomes larger when the angle of movement becomes smaller, and the energy transferred from the primary winding to the secondary winding becomes smaller when the angle of movement becomes larger.
9. The method of claim 7 or 8, wherein the second H-bridge comprises a third leg and a fourth leg, a fifth switching tube and a sixth switching tube are disposed on an upper leg and a lower leg of the third leg, respectively, a seventh switching tube and an eighth switching tube are disposed on an upper leg and a lower leg of the fourth leg, respectively, and the method comprises:
and controlling the switching actions of the fifth switching tube to the eighth switching tube, so that the fifth switching tube and the eighth switching tube are switched on when the sixth switching tube and the seventh switching tube are switched off, and the sixth switching tube and the seventh switching tube are switched on when the fifth switching tube and the eighth switching tube are switched off, and thereby the high-frequency alternating current output by the secondary winding of the transformer is rectified into high-frequency direct current through the second H bridge.
10. The method of claim 9, wherein a third H-bridge includes a fifth leg and a sixth leg, a ninth switching tube and a tenth switching tube are disposed on an upper leg and a lower leg of the fifth leg, respectively, an eleventh switching tube and a twelfth switching tube are disposed on an upper leg and a lower leg of the sixth leg, respectively, and the method includes:
and controlling the switching actions of the ninth switching tube to the twelfth switching tube, so that the ninth switching tube and the twelfth switching tube are switched on when the tenth switching tube and the eleventh switching tube are switched off, and the tenth switching tube and the eleventh switching tube are switched on when the ninth switching tube and the twelfth switching tube are switched off, and the high-frequency direct current output by the second H bridge is inverted into power frequency alternating current through the third H bridge and is combined into a power grid.
CN202310675090.3A 2023-06-08 2023-06-08 Micro inverter, control method thereof and photovoltaic system comprising micro inverter Pending CN116683774A (en)

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Publication number Priority date Publication date Assignee Title
CN103618336A (en) * 2013-12-09 2014-03-05 盐城工学院 Output digital modulation circuit and control system of rectifier type high-frequency chain grid-connected inverter
CN103888013A (en) * 2014-03-31 2014-06-25 盐城工学院 Minitype inverter based on high-frequency alternating-current voltage reduction theory and digital control device thereof
CN209313742U (en) * 2018-10-30 2019-08-27 中国电力科学研究院有限公司 A kind of three-phase photovoltaic grid-connected power-generation inversion device
WO2021232706A1 (en) * 2020-05-22 2021-11-25 广州视源电子科技股份有限公司 Three-bridge arm topology apparatus, control method, inverter system and uninterrupted power supply system

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103618336A (en) * 2013-12-09 2014-03-05 盐城工学院 Output digital modulation circuit and control system of rectifier type high-frequency chain grid-connected inverter
CN103888013A (en) * 2014-03-31 2014-06-25 盐城工学院 Minitype inverter based on high-frequency alternating-current voltage reduction theory and digital control device thereof
CN209313742U (en) * 2018-10-30 2019-08-27 中国电力科学研究院有限公司 A kind of three-phase photovoltaic grid-connected power-generation inversion device
WO2021232706A1 (en) * 2020-05-22 2021-11-25 广州视源电子科技股份有限公司 Three-bridge arm topology apparatus, control method, inverter system and uninterrupted power supply system

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