CN112886836B - Flyback micro inverter analog control circuit and peak current control method - Google Patents
Flyback micro inverter analog control circuit and peak current control method Download PDFInfo
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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
- H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
- H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
- H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/145—Conversion of ac power input into dc 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 thyratron or thyristor type requiring extinguishing means
- H02M7/155—Conversion of ac power input into dc 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 thyratron or thyristor type requiring extinguishing means using semiconductor devices only
- H02M7/162—Conversion of ac power input into dc 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 thyratron or thyristor type requiring extinguishing means using semiconductor devices only in a bridge configuration
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/381—Dispersed generators
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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
- H02M1/00—Details of apparatus for conversion
- H02M1/06—Circuits specially adapted for rendering non-conductive gas discharge tubes or equivalent semiconductor devices, e.g. thyratrons, thyristors
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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
- 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
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
- H02J2300/20—The dispersed energy generation being of renewable origin
- H02J2300/22—The renewable source being solar energy
- H02J2300/24—The renewable source being solar energy of photovoltaic origin
- H02J2300/26—The renewable source being solar energy of photovoltaic origin involving maximum power point tracking control for photovoltaic sources
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
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Abstract
The invention relates to the technical field of power electronic application, and aims to provide a flyback micro inverter analog control circuit and a peak current control method. The analog control circuit comprises a maximum power point tracking analog control circuit, a power grid phase-locked circuit and a main power switch tube drive control analog circuit, and realizes the functions of maximum power point tracking and grid-connected current sine of the flyback micro photovoltaic grid-connected inverter through analog control; the flyback converter works in an inductive current discontinuous mode and adopts primary side peak current control. Compared with the prior art, the analog control of the invention can effectively reduce the control cost and complexity of the micro inverter, and has the advantages of easy integration, simple control, low cost and the like. In addition, the analog control technology lays a foundation for further developing a special integrated control chip of the flyback micro-inverter, and is beneficial to reducing the cost of the micro-inverter.
Description
Technical Field
The invention belongs to the technical field of power electronic application, and relates to the field of control of micro inverters. The invention is a flyback micro inverter analog control circuit based on peak current control, which can effectively reduce the control cost and complexity of the micro inverter, further promote the development of a flyback micro inverter special integrated control chip and is beneficial to reducing the cost of micro inverter.
Background
With the reduction of the reserves of the traditional fossil energy and the increase of the mining difficulty, and the reduction of the application cost of various renewable energy sources, the research and the application of the renewable energy sources are generally increased by human beings. The solar energy has the advantages of wide distribution, easy acquisition, zero emission, sustainability and the like, and becomes a hot spot for the application research of renewable energy sources. For the solar photovoltaic power generation technology, there are two main types of applications, centralized type and distributed type. Among them, the module-level photovoltaic power generation system in distributed application has many advantages and is gradually becoming a main stream of research.
The miniature photovoltaic grid-connected inverter mainly realizes the functions of tracking the maximum power point of the photovoltaic cell panel, injecting sine alternating current into a power grid and the like. The flyback miniature photovoltaic inverter has the advantages of simple structure, small number of components, simple control, electrical isolation and the like, and is widely applied to a component-level photovoltaic power generation system. At present, a digital control technology taking a DSP or FPGA digital controller as a platform is mainly adopted for controlling the flyback micro inverter, but the digital control has the defects of difficult integration, high control cost, poor real-time performance and the like, and the wider application of the micro inverter is limited.
Disclosure of Invention
The invention aims to solve the technical problem of overcoming the defects in the prior art and provides an analog control circuit of a flyback micro inverter and a peak current control method.
In order to solve the technical problem, the solution of the invention is as follows:
the simulation control circuit of the flyback miniature inverter is provided, and the functions of maximum power point tracking and grid-connected current sine of the flyback miniature photovoltaic grid-connected inverter are realized through simulation control; the analog control circuit comprises a maximum power point tracking analog control circuit, a power grid phase-locking circuit and a main power switch tube drive control analog circuit;
the maximum power point tracking analog control circuit determines the increase and decrease condition of the current peak current reference amplitude by performing exclusive OR logic judgment on the increase and decrease condition of the output power of the photovoltaic panel and the increase and decrease condition of the output voltage of the photovoltaic panel, so as to determine the current peak current reference value;
the power grid phase-locking circuit consists of a power grid zero-crossing detection and phase tracking circuit and is used for determining real-time phase information of power grid voltage;
the current peak value reference value of the driving control circuit is obtained by multiplying the output of the maximum power point tracking analog control circuit and the output of the power grid phase-locking circuit, and the driving turn-off signal is obtained by comparing the primary side current with the peak value current reference value; the turn-off time is determined by comparing the current flowing through the main power switch tube with a sinusoidal current reference value, and the turn-on time of the main power switch tube is determined by a pulse signal with fixed frequency.
In the invention, the maximum power point tracking analog control circuit specifically comprises a multiplier circuit, a sampling holding comparison circuit, a logic judgment circuit and an amplitude increasing and decreasing control circuit which are electrically connected in sequence.
In the invention, the multiplier circuit comprises a multiplier, and two input ends of the multiplier are respectively the output voltage i of the photovoltaic panelpvAnd vpvThe output of the multiplier is connected to a sample-and-hold capacitor C1 of the sample-and-hold comparator circuit via a charging resistor R7.
In the invention, the sample-hold comparison circuit comprises two comparators COM1 and COM2, two single-pole single-throw switches T1 and T2, sample-hold capacitors C1, C2, C3 and C4, and four charge-discharge resistors R5, R6, R7 and R8; the outputs of the two comparators are connected with the input end of an exclusive-OR gate in the logic judgment circuit; sampling signal v of photovoltaic panel output voltagepvThe capacitor C3 is connected with the capacitor C3 through a charging resistor R5, one end of the capacitor C3 is connected with the positive end of the comparator COM1, the other end of the capacitor C3 is connected with the switch T2, the other end of the switch T2 is connected with the capacitor C4 through a charging resistor R6, and meanwhile, one end, connected with the resistor R6, of the capacitor C4 is connected with the negative end of the comparator COM 1; one end of the capacitor C1 is connected to the positive terminal of the comparator COM2, and is also connected to the switch T1, the other end of the switch T1 is connected to the capacitor C2 through a charging resistor R8, and a segment of the capacitor C2 connected to the resistor is connected to the negative terminal of the COM 2.
In the invention, the logic judgment circuit comprises an exclusive-OR gate, the input end of the exclusive-OR gate is connected with the output ends of two comparators in the sampling and holding circuit, and the output end of the exclusive-OR gate is connected with the input end of the latch D; the clock end of the latch D is connected with a clock signal CLK, and the output end of the latch D is connected with the amplitude increase and decrease control circuit.
In the invention, the amplitude increase and decrease control circuit comprises a NOT gate, two single-pole single-throw switches T3 and T4, a direct-current voltage source DC, 2 charge and discharge resistors R1 and R2, two voltage dividing resistors R3 and R4 and a charge and discharge capacitor C5; the control end of the switch tube T3 is directly connected with the output of a latch D in the logic judgment circuit, and the output of the latch D is also connected with the control end of the switch tube T4 through a NOT gate; the positive electrode of a direct-current voltage source DC is connected with one end of a switch tube T3, the other end of a switch T3 is connected with a resistor R1, the other end of the resistor R1 is simultaneously connected with a resistor R3, a capacitor C5 and a switch T4, the other end of a switch T4 is connected with the resistor R2, the other end of a resistor R3 is connected with the resistor R4, and the other end of a resistor R4 is simultaneously connected with the other end of the capacitor C5, the other end of the R2 and the negative electrode of the direct-current voltage source DC.
The invention further provides a flyback miniature photovoltaic grid-connected inverter which comprises a flyback converter, a full-bridge power frequency inverter circuit and a C-L output filter; the grid-connected inverter also comprises the analog control circuit so as to realize analog control on the inverter.
The invention further provides a method for realizing peak current control by utilizing the flyback micro inverter analog control circuit, which comprises the following steps:
(1) flyback converter employing primary side peak current control
The maximum power point tracking analog control circuit judges and determines the increase and decrease condition of the current peak current reference amplitude by carrying out XOR logic on the increase and decrease condition of the output power of the photovoltaic panel and the increase and decrease condition of the output voltage of the photovoltaic panel so as to determine the current peak current reference value; the power grid phase-locked circuit performs power grid zero-crossing detection and power grid phase tracking; the current peak value reference value in the main power switch tube driving control analog circuit is obtained by multiplying the output of the maximum power point tracking analog control circuit and the output of the power grid phase-locking circuit, the driving turn-off signal is obtained by comparing the primary current with the peak current reference value, and the main switch tube turn-on signal is triggered and determined by the pulse with fixed frequency; the maximum power point tracking analog control circuit gives a current peak current reference amplitude value through logic judgment so as to realize the tracking of the maximum power point;
(2) flyback converter working in discontinuous mode of inductive current
The method comprises the steps that peak current control is adopted, a primary side peak current reference amplitude is multiplied by a power grid phase to serve as a primary side peak current reference value of a flyback converter, and a switching tube turn-off signal is generated by comparing the primary side peak current reference amplitude with a primary side current of the flyback converter; the average value of the secondary side current is sinusoidal current, and the sinusoidal full-wave current is injected into the power grid after passing through the full-bridge power frequency inverter circuit, so that the function of sinusoidal current grid connection is realized.
In the invention, in the process of tracking the maximum power point: when the current power is increased and the voltage of the photovoltaic panel is increased, reducing the peak current reference value of the next period; when the current power is increased and the voltage of the photovoltaic panel is reduced, increasing the peak current reference value of the next period; when the current power is reduced and the voltage of the photovoltaic cell panel is reduced, reducing the peak current reference value of the next period; when the current power is reduced and the voltage of a photovoltaic panel battery is increased, increasing the peak current reference value of the next period; after a certain period number, the peak current reference value is stabilized near the maximum power point, and the maximum power point tracking is realized.
Compared with the prior art, the invention has the beneficial effects that:
1. compared with a digital control technology, the analog control can effectively reduce the control cost and complexity of the micro inverter and has the advantages of easy integration, simple control, low cost and the like.
2. In addition, the analog control technology lays a foundation for further developing a special integrated control chip of the flyback micro-inverter, and is beneficial to reducing the cost of the micro-inverter.
Drawings
FIG. 1 is a schematic diagram of an analog control circuit according to the present invention;
fig. 2 is a main waveform diagram of a flyback micro-inverter;
fig. 3 is a schematic diagram of a maximum power point tracking analog control circuit.
Detailed Description
Embodiments of the present invention are described in detail below with reference to the accompanying drawings.
Fig. 1 is a schematic diagram of an analog control circuit of a flyback micro inverter, which mainly comprises a main power circuit, namely a photovoltaic panel, a flyback converter, a full-bridge power frequency inverter circuit and a C-L output filter; the control circuit comprises a maximum power point tracking analog control circuit, a power grid phase-locking circuit and a main power switch tube drive control analog circuit.
Fig. 2 is a main waveform diagram of the flyback micro-inverter. In the invention, the flyback converter is controlled by primary peak current and works in an inductive current discontinuous mode.
When the flyback converter is controlled by primary side peak current and works in an inductive current discontinuous mode, the primary side current peak is as follows:
assuming that the grid voltage is:
the turn-off time of the switching tube is as follows:
the secondary side current average value is:
when the converter employs primary side peak current control, that is:
ip，peak(θg)＝IP·sin(θg)
then there are:
in the above formula, the meaning of each symbol or code is:
Θ g represents the instantaneous phase of the power grid voltage, Vpv represents the output voltage of the photovoltaic panel, Lm represents the transformer excitation inductance, ton represents the switching-on time of the main switching tube QM, Vg represents the effective value of the power grid voltage, N represents the transformer secondary side and primary side turn ratio, Tsw represents the switching period of the main switching tube QM, and Ip represents the maximum value of the primary side peak current envelope.
That is, when the flyback converter adopts primary peak current control and works in an inductive current discontinuous mode, the average value of the secondary current is sinusoidal current. After passing through the full-bridge power frequency inverter circuit, the sinusoidal full-wave current is injected into the power grid.
For peak current control, the primary peak current is referenced to the amplitude and the sine signal sin (θ) obtained by sampling the grid voltageg) Multiplying the peak current reference value by the primary side peak current reference value to generate a turn-off signal of the main switching tube by comparing the peak current reference value with the primary side current; the main power switch tube turn-on signal is determined by a DCM turn-on signal with fixed frequency.
Sine signal sin (theta)g) Obtained by the network phase-locking circuit. And the power grid phase-locked circuit completes power grid zero-crossing detection and power grid phase tracking.
The reference amplitude of the primary peak current is given by the maximum power point tracking control circuit. The maximum power point tracking control circuit mainly includes a multiplier circuit, a sample-hold comparison circuit, a logic judgment circuit, and an amplitude increase/decrease control circuit, as shown in fig. 3. The peak current amplitude increase and decrease control circuit works under the control of the logic judgment circuit and outputs the peak current amplitude I at high levelpIncrease and vice versa IpAnd (4) increasing. The Q + and Q-signals are signals of positive and negative half periods of the power grid voltage, Q + represents the positive half period of the power grid voltage, and Q-represents the negative half period of the power grid voltage.
Referring to fig. 1, a flyback converter includes a main power switch QMWhen the transformer is switched on, the primary side of the transformer has current ipAs shown in fig. 2. When the primary current rises to the peak current reference value irefWhen the primary side switching tube is turned off, the switching tube is turned on again when a DCM (discontinuous conduction mode) conduction signal with fixed frequency arrives. When the primary peak current reference sine is in phase with the grid voltageAnd when the sine is generated, the average value of the output grid-connected current is the sine current.
The multiplier calculates the power of the photovoltaic panel and reflects the power on the capacitor C1The above. Capacitor C2For the sample-and-hold capacitor, after the power of the photovoltaic panel is sampled and held, the output end of the comparator 2 outputs a high-low level signal, the high level indicates that the output power of the photovoltaic panel is increased, and the low level indicates that the output power of the photovoltaic panel is decreased.
The voltage of the photovoltaic panel outputs a high-low level signal after passing through the comparator 1, the high level represents the rising of the output voltage of the photovoltaic panel, and the low level represents the falling of the output voltage of the photovoltaic panel.
The power increase and decrease signal and the photovoltaic panel output voltage increase and decrease signal are used as control signals of the peak current amplitude control circuit after passing through an exclusive-or gate and a D latch, and the photovoltaic panel output power increase and decrease condition and the photovoltaic panel output voltage increase and decrease condition are used as control signals of peak current reference after passing through an exclusive-or logic.
According to fig. 3, when the current power increases and the voltage of the photovoltaic panel increases, the peak current reference value of the next cycle should be decreased; when the current power is increased and the voltage of the photovoltaic panel is reduced, the peak current reference value of the next period is increased; when the current power is reduced and the voltage of the photovoltaic cell panel is reduced, the peak current reference value of the next period is reduced; when the current power is reduced and the voltage of a photovoltaic panel battery is increased, the peak current reference value of the next period is increased; after a certain period number, the peak current reference value is stabilized near the maximum power point, and the maximum power point tracking is realized.
The power increase and decrease condition of the current period, the voltage increase and decrease condition of the photovoltaic panel of the current period, and the peak current reference amplitude I of the next periodpThe logical relationship between them is as follows:
| P | Vpv | Ip |
| 1 (increase) | 1 (increase) | 0 (decrease) |
| 1 (increase) | 0 (decrease) | 1 (increase) |
| 0 (decrease) | 0 (decrease) | 0 (decrease) |
| 0 (decrease) | 1 (increase) | 1 (increase) |
The output of the D latch is used as a control signal of the current peak value reference amplitude increase and decrease control circuit. When the D latch outputs a low level, the amplitude increase and decrease control circuit enables the peak current reference amplitude to be reduced, namely the primary side peak current reference value is reduced; when the D latch outputs a high level, the amplitude increase and decrease control circuit enables the peak current reference amplitude to be increased, namely the primary side peak current reference value is increased.
Under the control of the analog control circuit, the flyback micro inverter finally realizes the functions of maximum power point tracking and sine current grid connection.
Claims (4)
1. A flyback miniature inverter analog control circuit realizes the functions of maximum power point tracking and grid-connected current sine of a flyback miniature photovoltaic grid-connected inverter through analog control; the power grid phase-locked loop control circuit is characterized in that the analog control circuit comprises a maximum power point tracking analog control circuit, a power grid phase-locked circuit and a main power switch tube driving control analog circuit;
the maximum power point tracking analog control circuit determines the increase and decrease condition of the current peak current reference amplitude by performing exclusive OR logic judgment on the increase and decrease condition of the output power of the photovoltaic panel and the increase and decrease condition of the output voltage of the photovoltaic panel, so as to determine the current peak current reference value;
the power grid phase-locking circuit consists of a power grid zero-crossing detection and phase tracking circuit and is used for determining real-time phase information of power grid voltage;
the current peak value reference value of the main power switch tube driving control analog circuit is obtained by multiplying the output of the maximum power point tracking analog control circuit and the output of the power grid phase-locking circuit, and the driving turn-off signal is obtained by comparing the primary current with the peak current reference value; determining the turn-off time by comparing the current flowing through the main power switch tube with a sinusoidal current reference value, wherein the turn-on time of the main power switch tube is determined by a pulse signal with fixed frequency;
the maximum power point tracking analog control circuit specifically comprises a multiplier circuit, a sampling holding comparison circuit, a logic judgment circuit and an amplitude increasing and decreasing control circuit which are electrically connected in sequence;
the multiplier circuit comprises a multiplier, and two input ends of the multiplier are respectively the output current i of the photovoltaic panelpvAnd the output voltage v of the photovoltaic panelpvThe output end of the multiplier is connected with a sample-hold capacitor C1 in the sample-hold comparison circuit through a charging resistor R7;
the sample-hold comparison circuit comprises two comparators COM1 and COM2, two single-pole single-throw switches T1 and T2, sample-hold capacitors C1, C2, C3 and C4, and four charging and discharging resistors R5, R6, R7 and R8; the outputs of the two comparators are connected with the input end of an exclusive-OR gate in the logic judgment circuit; sampling signal v of photovoltaic panel output voltagepvThe capacitor C3 is connected with the charging resistor R5, one end of the resistor R5 connected with the capacitor C3 is connected with the positive end of the comparator COM1 and the switch T2, the other end of the switch T2 is connected with the capacitor C4 through the charging resistor R6, and meanwhile, the capacitor C4 is connected with the resistor R6One end of the capacitor is connected with the negative end of the comparator COM 1; one end of the capacitor C1 connected with the resistor R7 is connected with the positive end of the comparator COM2 and is also connected with the switch T1, the other end of the switch T1 is connected with the capacitor C2 through a charging resistor R8, and the other end of the capacitor C2 connected with the resistor R8 is connected with the negative end of the COM 2;
the logic judgment circuit comprises an exclusive-OR gate, the input end of the exclusive-OR gate is connected with the output ends of the two comparators in the sampling and holding circuit, and the output end of the exclusive-OR gate is connected with the input end of the latch D; the clock end of the latch D is connected with a clock signal CLK, and the output end of the latch D is connected with an amplitude increase and decrease control circuit;
the amplitude increase and decrease control circuit comprises a NOT gate, two single-pole single-throw switches T3 and T4, a direct-current voltage source DC, 2 charge and discharge resistors R1 and R2, two voltage dividing resistors R3 and R4 and a charge and discharge capacitor C5; the control end of the switch tube T3 is directly connected with the output of a latch D in the logic judgment circuit, and the output of the latch D is also connected with the control end of the switch tube T4 through a NOT gate; the positive electrode of a direct-current voltage source DC is connected with one end of a switch tube T3, the other end of a switch T3 is connected with a resistor R1, the other end of the resistor R1 is simultaneously connected with a resistor R3, a capacitor C5 and a switch T4, the other end of the switch T4 is connected with the resistor R2, the other end of a resistor R3 is connected with the resistor R4, and the other end of a resistor R4 is simultaneously connected with the other end of the capacitor C5, the other end of the R2 and the negative electrode of the direct-current voltage source DC; one end of the resistor R3 connected with the resistor R4 is used as the output of the maximum power point tracking analog control circuit.
2. A flyback miniature photovoltaic grid-connected inverter comprises a flyback converter, a full-bridge power frequency inverter circuit and a C-L output filter; the grid-connected inverter is characterized by further comprising the flyback micro-inverter analog control circuit disclosed by claim 1, so that analog control over the inverter is achieved.
3. A method for peak current control using the flyback micro-inverter analog control circuit of claim 1, comprising:
(1) flyback converter employing primary side peak current control
The maximum power point tracking analog control circuit judges and determines the increase and decrease condition of the current peak current reference amplitude by carrying out XOR logic on the increase and decrease condition of the output power of the photovoltaic panel and the increase and decrease condition of the output voltage of the photovoltaic panel so as to determine the current peak current reference value; the power grid phase-locked circuit performs power grid zero-crossing detection and power grid phase tracking; the current peak value reference value in the main power switch tube driving control analog circuit is obtained by multiplying the output of the maximum power point tracking analog control circuit and the output of the power grid phase-locking circuit, the driving turn-off signal is obtained by comparing the primary current with the peak current reference value, and the main switch tube turn-on signal is triggered and determined by the pulse with fixed frequency; the maximum power point tracking analog control circuit gives a current peak current reference amplitude value through logic judgment so as to realize the tracking of the maximum power point;
(2) flyback converter working in discontinuous mode of inductive current
The method comprises the steps that peak current control is adopted, a primary side peak current reference amplitude is multiplied by a power grid phase to serve as a primary side peak current reference value of a flyback converter, and a switching tube turn-off signal is generated by comparing the primary side peak current reference amplitude with a primary side current of the flyback converter; the average value of the secondary side current is sinusoidal current, and the sinusoidal full-wave current is injected into the power grid after passing through the full-bridge power frequency inverter circuit, so that the function of sinusoidal current grid connection is realized.
4. The method of claim 3, wherein in performing maximum power point tracking: when the current power is increased and the voltage of the photovoltaic panel is increased, reducing the peak current reference value of the next period; when the current power is increased and the voltage of the photovoltaic panel is reduced, increasing the peak current reference value of the next period; when the current power is reduced and the voltage of the photovoltaic cell panel is reduced, reducing the peak current reference value of the next period; when the current power is reduced and the voltage of a photovoltaic panel battery is increased, increasing the peak current reference value of the next period; after a certain period number, the peak current reference value is stabilized near the maximum power point, and the maximum power point tracking is realized.
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| CA2655007C (en) * | 2009-02-20 | 2017-06-27 | Queen's University At Kingston | Photovoltaic cell inverter |
| CN106255270B (en) * | 2016-08-30 | 2019-02-22 | 华中科技大学 | Primary side feedback inverse-excitation type LED constant-current driver based on power tube drain electrode detection technique |
| CN108696164B (en) * | 2018-08-22 | 2024-01-05 | 西华大学 | Flyback single-phase photovoltaic grid-connected micro inverter controlled by DCM frequency conversion and control method |
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