CN106787911A - A kind of miniature photovoltaic grid-connected inverter and control method - Google Patents
A kind of miniature photovoltaic grid-connected inverter and control method Download PDFInfo
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Classifications
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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
- H02M7/53871—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 with automatic control of output voltage or current
- H02M7/53873—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 with automatic control of output voltage or current with digital control
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- H02J3/383—
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- 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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- Inverter Devices (AREA)
- Dc-Dc Converters (AREA)
Abstract
This application discloses a kind of miniature photovoltaic grid-connected inverter and control method, inverter includes the power decoupled module being connected in turn between photovoltaic panel and public electric wire net, crisscross parallel flyback module, full-bridge inverting module and LC filtration modules, power decoupled module, crisscross parallel flyback module, full-bridge inverting module and LC filtration modules are connected with control unit respectively, crisscross parallel flyback module circuit of reversed excitation balanced by two-way bringing onto load and active-clamp function is constituted, the two-way circuit structure is identical with parameter, and should be in a switch periods, alternate 180 ° of work.Disclosed herein as well is a kind of control method of miniature photovoltaic grid-connected inverter, the alternation simultaneously of the two-way flyback portion of crisscross parallel, volume of transformer and increase power density can be effectively reduced, effectively reduce component number, reduce output current ripple, coupled capacitor volume is reduced, cost is reduced, is more suitable for applying and is promoted.
Description
Technical field
The application is related to a kind of miniature photovoltaic grid-connected inverter and control method, can be by the direct current from photovoltaic panel
Can be converted into public exchange power network with frequency with the AC energy of phase and inject public electric wire net, realize the profit of recyclable clean energy resource
With with conversion.
Background technology
At present, the topological structure of miniature photovoltaic grid-connected inverter is mainly normal shock and Flyback configuration, and wherein forward structure is needed
Decoupling transformer is wanted, component is more, relatively costly, be not suitable for small-power and use and popularize；Flyback configuration is due to its primary side
Leakage inductance is present, and when each switch periods is turned off, the high-voltage pulse spike that primary side leakage inductance is produced easily causes component damage, passes
RCD (Resistance Capacitance Diode) clamp circuit of system is applied in Flyback configuration, for absorbing leakage inductance
Energy and high-voltage pulse, but it is that this leakage inductance energy is converted into heat-energy losses, it is less efficient.
In the prior art, mainly including following two technical schemes：
(1) disclosed in the 201210012195.2 of Chinese patent application using the inverse-excitation type light of interleaving parallel-connection active clamping
Volt combining inverter, the inventive structure is helped and reduces output current ripple, leakage inductance energy is realized again and is absorbed and effectively utilization,
Efficiency is improve, and improves the EMI characteristics of high-frequency circuit.
(2) a kind of solar photovoltaic grid-connection crisscross parallel flyback is disclosed in the 201110186983.9 of Chinese patent application
Inverter, reduces the THD of grid-connected current.
Although above two scheme has certain actual effect, but there are problems that.For example, having in scheme (1)
Source clamp circuit is parallel to transformer primary side, and the part characteristic requirement to the active clamping circuir is higher, and clamping capacitance is resistance to
Pressure value is high, and pressure voltage and the drive circuit requirement for clamping auxiliary switch are high.Without for leakage present in flyback in scheme (2)
The clamp circuit felt and design, leakage inductance easily causes device failure and system effectiveness reduction.In other scheme (1) and scheme (2)
The structure of crisscross parallel is all employed, but the function of balanced regulation and control two-way Flyback configuration bearing power is not set, easily
Because physical cause or interference cause two-way load imbalance, certain all the way power termination it is excessive, damage and component or cause temperature
Degree is raised and causes system unstable.
The content of the invention
It is an object of the invention to provide a kind of miniature photovoltaic grid-connected inverter and control method, to overcome in the prior art
Problem.
To achieve the above object, the present invention provides following technical scheme：
The embodiment of the present application discloses a kind of miniature photovoltaic grid-connected inverter, and the direct current energy from photovoltaic panel is converted into
With public exchange power network with frequency is with the AC energy of phase and injects public electric wire net, the inverter includes being connected to light underlying surface in turn
Power decoupled module, crisscross parallel flyback module, full-bridge inverting module and LC filtration modules between plate and public electric wire net, it is described
Power decoupled module, crisscross parallel flyback module, full-bridge inverting module and LC filtration modules are connected with control unit respectively, described
Crisscross parallel flyback module includes balanced and active-clamp function the circuit of reversed excitation of two-way bringing onto load, the knot of the two-way circuit of reversed excitation
Structure is identical with parameter, and in switch periods, the two-way circuit of reversed excitation alternates 180 ° of work.
Preferably, in above-mentioned miniature photovoltaic grid-connected inverter, the circuit of reversed excitation includes realizing active-clamp and bears
Carry the circuit unit of equalization function.
Preferably, in above-mentioned miniature photovoltaic grid-connected inverter, include respectively per circuit of reversed excitation described in road main switch,
Clamp switch pipe, main transformer, active clamping circuir and current sampler, the main switch are placed in current sampler with ground
Between, the current sampler connects main transformer and main switch, and the active clamping circuir includes that clamping capacitance and clamp are auxiliary
Switching tube, the clamping capacitance is helped to be placed between the drain electrode of main switch and the drain electrode of clamp switch pipe, the clamp auxiliary is opened
Pipe is closed to be placed between clamping capacitance and ground.
Preferably, in above-mentioned miniature photovoltaic grid-connected inverter, circuit of reversed excitation also includes output diode described in per road
And filter capacitor, the output diode and filter capacitor are placed in transformer secondary, connection rear class part.
Preferably, in above-mentioned miniature photovoltaic grid-connected inverter, the main switch is partly led for N-channel metal oxide
Body FET (Metal-Oxide-Semiconductor Field-Effect Transistor, MOSFET).
Preferably, in above-mentioned miniature photovoltaic grid-connected inverter, the clamp auxiliary switch is P-channel
MOSFET。
Preferably, above-mentioned P-channel MOSFET drive circuits are relatively easy to relative to N-channel MOS FET, and clamp auxiliary is opened
Close pipe and clamping capacitance be parallel to the hourglass source electrode both sides of main switch, relative to be parallel to transformer primary side two survey pressure voltage compared with
It is low, it is possible to decrease cost.
Preferably, in above-mentioned miniature photovoltaic grid-connected inverter, the current sampler is current transformer, the electricity
Current transformer primary side connects main switch and main transformer, secondary connection sampling resistor.
Preferably, in above-mentioned miniature photovoltaic grid-connected inverter, described control unit includes electric current loop and feed-forward voltage
Ring double -loop control, the electric current loop is used to track and sample grid voltage amplitude and phase and output voltage and current amplitude phase
Position, is compared with reference current value, by current compensation, coordinates electric voltage feed forward link, obtains controlling flyback portion dutycycle
Parameter, output in occupancy controller, the electric current of controlled output and line voltage same-phase.
Preferably, in above-mentioned miniature photovoltaic grid-connected inverter, described control unit also includes that load balancing controls mould
Block, the load balancing control module is in each switch periods according to the active-clamp flyback topologies output in a balanced way of two-way bringing onto load
The difference of average current size, generates a small variable, in the middle of output to the road occupancy controller, changes two-way flyback
Partial driving pulse dutycycle, makes two line structures reach the effect of load balancing.
Accordingly, disclosed herein as well is a kind of control method of miniature photovoltaic grid-connected inverter, bringing onto load described in per road
In a balanced way in active-clamp flyback topologies, in switch periods, the main switch with clamp auxiliary switch alternate conduction, it is inverse
Become device and work in discontinuous mode (DCM, Discontinuous Conduction Mode).
Preferably, in the control method of above-mentioned miniature photovoltaic grid-connected inverter, in the middle of a switch periods, master is worked as
When switching tube is turned on, corresponding clamp auxiliary switch is closed, after main switch is turned off, by relative after one section of Dead Time
Auxiliary switch is answered to turn on, before switch periods start next time, corresponding clamp auxiliary switch is closed, by one section of dead band
After time, main switch conducting starts new switch periods.
Preferably, in the control method of above-mentioned miniature photovoltaic grid-connected inverter, two-way bringing onto load is equal in Dead Time
The circuit of reversed excitation of weighing apparatus and active-clamp characteristic does not work, and Dead Time is auxiliary more than main switch opening time maximum and clamp
Switching tube turn-off time maximum sum is helped, less than transformer primary side leakage inductance and a quarter of clamping capacitance harmonic period.
Compared with prior art, the advantage of the invention is that：
(1), the flyback topologies of crisscross parallel of the present invention have active-clamp and load balancing characteristic, and active clamping circuir is not
The drain-source voltage pincers of flyback main switch can be only put in a safe range when flyback main switch is turned off, it is ensured that anti-
Swash the safety of main switch, and collect and recycle the energy of transformer primary side leakage inductance, improve the efficiency of total system；
(2), crisscross parallel two-way circuit of reversed excitation alternation in switch periods of the invention, can effectively reduce transformation
Body is accumulated and increase power density, effectively reduces component number, reduces output current ripple, reduces coupled capacitor body
Product, reduces cost, is more suitable for application distribution formula photovoltaic generation and BIPV application；
(3), the load balancing characteristic in crisscross parallel flyback topologies of the invention being capable of real-time adjustment two-way circuit of reversed excitation
Output current size, it is to avoid the load imbalance caused by physical parameter difference or interference, and then cause on thermal temperature
Rise, damaged system.The characteristic effectively protects component, improves the stability of system.
(4), the flyback portion in the present invention is worked under DCM patterns, need to only control flyback portion main switch to drive arteries and veins
Amplitude change of the dutycycle of punching according to the phase and reference current of line voltage, you can output is with line voltage with frequency with phase
Electric current, control is simple, low cost, it is easy to accomplish.
Brief description of the drawings
In order to illustrate more clearly of the embodiment of the present application or technical scheme of the prior art, below will be to embodiment or existing
The accompanying drawing to be used needed for having technology description is briefly described, it should be apparent that, drawings in the following description are only this
Some embodiments described in application, for those of ordinary skill in the art, on the premise of not paying creative work,
Other accompanying drawings can also be obtained according to these accompanying drawings.
Fig. 1 show the functional-block diagram of miniature photovoltaic grid-connected inverter in the specific embodiment of the invention；
Fig. 2 show balanced and active-clamp characteristic the crisscross parallel flyback portion of bringing onto load in the specific embodiment of the invention
Circuit diagram；
Fig. 3 show flyback topologies structure working principle oscillogram in the specific embodiment of the invention；
Balanced and active-clamp characteristic the flyback portion of bringing onto load is operated in during Fig. 4 show the specific embodiment of the invention
The principle schematic of DCM patterns；
Fig. 5 show the overall control principle schematic diagram of inverter in the specific embodiment of the invention；
Fig. 6 show the block diagram of PI (Proportional Integral) control principle in the specific embodiment of the invention；
Fig. 7 show in the specific embodiment of the invention frame for controlling two-way Flyback configuration current loading control principle in a balanced way
Figure；
Fig. 8 show the switch of the interleaving parallel-connection active clamping flyback portion in a balanced way of bringing onto load in the specific embodiment of the invention
Pipe drive control schematic diagram.
Specific embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, detailed retouching is carried out to the technical scheme in the embodiment of the present invention
State, it is clear that described embodiment is only a part of embodiment of the invention, rather than whole embodiments.Based on the present invention
In embodiment, the every other implementation that those of ordinary skill in the art are obtained on the premise of creative work is not made
Example, belongs to the scope of protection of the invention.
With reference to shown in Fig. 1, be converted into the direct current energy from photovoltaic panel and public friendship by miniature photovoltaic grid-connected inverter
, with frequency is with the AC energy of phase and injects public electric wire net, inverter power output is maximum up to 250 watts, belongs to small work(for stream power network
Rate scope, each flyback portion can bear peak power no more than 200 watts.
Inverter includes the power decoupled module, the crisscross parallel flyback that are connected in turn between photovoltaic panel and public electric wire net
Module, full-bridge inverting module and LC filtration modules, power decoupled module, crisscross parallel flyback module, full-bridge inverting module and LC
Filtration module is connected with control unit respectively, and crisscross parallel flyback module includes two-way circuit of reversed excitation, two-way circuit topology, the unit
Device and parameter are identical, in switch periods, alternate 180 ° of work.
In the technical scheme, the inverter uses balanced and active-clamp characteristic the crisscross parallel flyback mould of bringing onto load
Block, output peak power is no more than 250 watts, is adapted to distributed photovoltaic power generation system and BIPV application.
In the technical scheme, relative to traditional forward converter, circuit of reversed excitation does not need decoupling transformer, reduces first device
Number of packages amount and volume, save cost and take up room, and are more suitable for low-power applications.
Relative to the RCD clamp circuits used in traditional flyback topologies structure by transformer primary side leakage inductance energy with heat shape
Formula discharges, and improves system temperature, reduces efficiency, also shortens system lifetim, the present invention having using crisscross parallel
Source clamp flyback topologies can effectively improve system effectiveness, and temperature will not be caused to raise, and reduce system ripple, extend system
Life-span.
Fig. 2 is to show balanced and active-clamp the crisscross parallel Flyback configuration 200 of bringing onto load, the Flyback configuration 200 by
Balanced and active-clamp characteristic the flyback topologies part 201 and 202 of two hardware configuration identical bringing onto loads constitutes, two of which
Flyback topologies part interlocks 180 ° in a switch periods and takes turns to operate, and has dead in the middle of two flyback topologies part alternations
Area's time, two flyback portions do not work in Dead Time, and Dead Time is more than main switch opening time maximum and clamp
Auxiliary switch turn-off time maximum sum, less than transformer primary side leakage inductance and a quarter of clamping capacitance harmonic period.
Per bringing onto load all the way, the flyback topologies structure of balanced and active-clamp characteristic is by main flyback portion, active-clamp part
Constituted with current sample part, by taking the active-clamp flyback topologies part 201 of Part I bringing onto load equalization characteristic as an example, mainly
By transformer TR1, Current Transmit 1, current sampling resistor R1, flyback main switch Q1, clamping capacitance Cclamp1 and clamp
The switching tube Q2 and output diode D1 being connected with main transformer secondary and filter capacitor C1 is constituted, here for explanation side
Just, primary transformer coil leakage inductance is showed with individual component Lleakage1.
Wherein, main flyback portion transformer TR1 connection photovoltaic panels and the output of rear pole, there is the work of energy conversion and isolation
With the primary side of Current Transmit 1 is placed between transformer primary side and flyback main switch Q1, and current sampling resistor R1 is placed in electric current
Transformer CT1 secondary connects post processing electric circuit, and flyback main switch Q1 is placed between transformer CT1 and ground, output diode
D1 and filter capacitor C1 are placed in transformer TR1 secondary, connection rear class part.The clamping capacitance Cclamp1 connections of active-clamp part
Flyback main switch drains and clamp auxiliary switch Q2 drain electrode, clamp auxiliary switch Q2 be placed in clamping capacitance Cclamp1 and
Between ground.
Further, using high pressure resistant, the N-channel MOS FET of resistance to high current realizes flyback portion master to flyback main switch Q1
The break-make of circuit.
Further, active clamping circuir auxiliary switch controls break-make, itself and this road flyback using the MOSFET of P-channel
Main switch alternate conduction.
In the technical scheme, relative to individually Flyback configuration all the way, due to being operated in switch switching state, output ripple
It is larger and when ripple is larger, easily to cause temperature to rise, it is necessary to use larger capacity and the filter capacitor of volume, reduce system peace
Full property and efficiency.The two-way flyback topologies structure of the bringing onto load interleaving parallel-connection active clamping in a balanced way that the present invention is used, two-way is anti-
Structure is swashed in a switch periods, and staggeredly 180 degree alternation, the equivalent ripple of so output is greatly reduced, and can effectively be subtracted
Small filter capacitor volume and raising system effectiveness and life-span.
With reference to shown in Fig. 3, in a switch periods, flyback main switch Q1 and clamp switch pipe Q2 is also to replace work
Make, middle one section of Dead Time, two pipes are not turned in Dead Time.When flyback main switch Q1 is turned on, magnetic core of transformer T1 storages
Energy is deposited, reversely cut-off is not turned on secondary side diode D1, when main open pipe pipe Q1 is turned off, secondary diode D1 forward conductions,
The energy transmission of transformer TR1 storages there occurs resonance to primary side, primary side leakage inductance Lleakage1 and clamping capacitance Cclamp1,
Now electric current flows to clamping capacitance from leakage inductance, and clamping capacitance charges, and collects the energy of leakage inductance release, as clamp auxiliary switch Q2
During opening, now, the energy being stored in clamping capacitance Cclamp1 starts to release energy, electric current change flow direction, start by
Clamping capacitance is flowed out, and the energy of clamping capacitance memory storage is also circulated and is discharged into secondary lateral load, is effectively utilized leakage inductance energy, is subtracted
Lack the loss of energy, improve system effectiveness, and due to the effect of clamping capacitance, flyback main switch drain-source when off
Step voltage is clamped within a safety value, effectively protects main switch, improves the security of system.
In the technical scheme, efficiency higher can be realized by active clamping circuir, in addition the alternation of two-way flyback, can
With effective ripple for reducing output, filter capacitor volume and capacity can be reduced, improve system lifetim.
In the technical scheme, during circuit of reversed excitation normal work, because transformer primary side leakage inductance can be produced when main switch is turned off
High pulse voltage, active clamping circuir of the present invention, can flyback main switch shut-off after open, using clamping capacitance
Clamp voltage, magnitude of voltage is in safe range between making the drain-source of flyback main switch, effectively protects flyback main switch, and utilize
The energy of leakage inductance storage can effectively be collected and recycled to leakage inductance and clamping capacitance resonance, improve whole efficiency.
With reference to shown in Fig. 4, flyback portion is worked under DCM, i.e., in each switch periods, primary side excitation inductance current all can
Return to zero-current point.
For the operation principle of analytic explanation DCM patterns, it is assumed that the power output of photovoltaic module keeps constant, and circuit is
Into stable state.Assume that the input capacitance of back exciting converter is sufficiently large, can ignore the ripple of input voltage simultaneously.When flyback inversion
When device primary side main switch Q1 is turned on, static exciter inductance Lm electric currents are started from scratch rising.ON time tonAt the end of electricity
Stream peak value ip,peakCan be expressed as：
Wherein, θgIt is the phase angle of line voltage, VpvIt is the input voltage of back exciting converter, i.e. photovoltaic panel output is electric
Pressure, Lm is the magnetizing inductance of transformer.
After primary side main switch Q1 is turned off, the energy transfer being stored in magnetizing inductance has arrived the secondary of transformer, secondary
The electric current of diode begins to decline.Ideally line voltage vgCan be：
Wherein VgIt is the virtual value of line voltage, then diode current drops to the time t required for zerooffCan be with table
It is shown as：
Wherein N is the ratio between the transformer secondary number of turn and primary side number of turn.According to formula (I) and (III), become in a switch periods
The average value of depressor secondary current can be expressed as：
As long as the ON time t of main switch Q1 as can be seen from the above equationonAs phase angle is changed with sinusoidal form, it is possible to
Ensure the sineization of grid-connected current.Therefore, the dutycycle of main switch Q1 can be expressed as：
Wherein DpIt is the peak value of dutycycle d in half power frequency period.By controlling DpSize can control grid-connected current
Size.
In the technical scheme, flyback topologies are worked under electric current DCM, relative to interrupted and critical (BCM, Boundary
ConductionMode), it is necessary to moment concern changed power calculates and then judges to enter DCM patterns or BCM moulds under mixed mode
Formula, DCM patterns have control easy, it is easy to accomplish the characteristics of, need to only control the duty of the drive waveforms of two-way flyback main switch
Than changing according to electric network voltage phase and reference current amplitude, you can complete flyback output current and follow line voltage frequency and phase
The requirement of position.
With reference to shown in Fig. 5, whole system control ring 500 is by electric current loop with feed-forward voltage ring group into wherein electric current loop 501 is led
To be used for track and sample grid voltage amplitude and phase and output voltage and current amplitude phase, be compared with reference current value
Compared with, through overregulating i.e. current compensation 502, coordinate the electric current of electric voltage feed forward link 503, controlled output and line voltage same-phase,
Whole back exciting converter part works in electric current DCM patterns, can reduce switch and damage and control method simplicity, it is easy to control and real
Existing, cost of implementation is relatively low relative to DCM＆BCM；Voltage loop and electric current loop realize photovoltaic panel voltage sample and power output jointly
Sampling, MPPT functions are realized with hop algorithm.Load balancing part 504 is mainly used to detect and control two active-clamps of parallel connection
The working condition of flyback portion, keeps the equilibrium of two-way electric current.
With reference to shown in Fig. 6, whole PI control loops are made up of electric current loop and electric voltage feed forward two parts, the output of real-time sampling
Current value Iac is anti-by again compared with electric voltage feed forward, obtaining control after PI controls compared with software reference current value Iref
The parameter of part dutycycle is swashed, in output to occupancy controller.
It is load balancing control principle drawing with reference to shown in Fig. 7, the Current Transmit 1 and CT2 being series in circuit are real-time
Detect that two-way flyback portion exports average current, compare, when finding difference occur, show that two-way circuit of reversed excitation occurs not
Situation in a balanced way, the current differential can enter a PI control loop, generate a small variable, output to Duty ratio control
In the middle of device, change the driving pulse dutycycle of two-way flyback portion.Can so make because of situations such as physical characteristic or interference
Cause certain all the way electric current it is excessive or too small, cause system work it is abnormal, cause temperature to raise, damage system.The load balancing
Control can ensure system steady operation in the case of safe and efficient.
In the technical scheme, the bringing onto load balance module that this case is used has regulating load characteristic in a balanced way, i.e. control system
The average output current of system detection two-way circuit of reversed excitation, when detecting because the reasons such as physical characteristic or interference cause two-way anti-
When excitation circuit output current is inconsistent, an amount trimmed, the amount trimmed can be produced to enter in the middle of the control for producing driving pulse,
Make the dutycycle width of two-way driving pulse that opposite change to occur, that is, detect the larger road dutycycle of output current and slightly subtract
Small, the less road dutycycle of output current slightly increases.Load balancing characteristic ensure that the power equalization of two-way Flyback configuration, keep away
Exempt from, because the unbalanced temperature for causing of power is raised or component damage, to greatly improve the stability of system.
With reference to shown in Fig. 8, can be added from PI controllers and the parameter of load balancing controller obtain be worth to control
The parameter of dutycycle, is then compared with triangle carrier signal, and two-part triangle carrier signal frequency is consistent with amplitude,
Single-phase differs 180 degree, and the drive signal of two-way flyback portion main switch is obtained more afterwards, per the active pincers of flyback portion all the way
The drive waveforms of position auxiliary switch are identical with the drive waveforms amplitude size and frequency of this road flyback main switch, phase difference
180 degree.
By working waveform figure：The envelope of clamp voltage and flyback output current is all the half-sine wave for 100Hz
Shape；In flyback main switch shutdown moment, a high pulse voltage produced due to leakage inductance is had, but due to active-clamp
Presence, clamping capacitance by the magnitude of voltage clamp control in a scope for safety；Two-way flyback working effect is identical, all defeated
Go out the half-sine wave electric current of same frequency and amplitude.
For miniature photovoltaic grid-connected inverter involved in the present invention, due to being adapted to the voltage and work(of major part photovoltaic panel
This Miniature inverter need to be only fixedly mounted on photovoltaic panel rear side by rate application, user, connect photovoltaic panel and public electric wire net, be opened
Breakdown closes and the system just can be used, so with the effect that can as simply as possible realize energy conversion.
It should be noted that and, term " including ", "comprising" or its any other variant be intended to nonexcludability
Include so that process, method, article or equipment including a series of key elements not only include those key elements, but also
Including other key elements being not expressly set out, or also include for this process, method, article or equipment it is intrinsic want
Element.In the absence of more restrictions, the key element limited by sentence "including a ...", it is not excluded that wanted including described
Also there is other identical element in process, method, article or the equipment of element.
The above is only the specific embodiment of the application, it is noted that for the ordinary skill people of the art
For member, on the premise of the application principle is not departed from, some improvements and modifications can also be made, these improvements and modifications also should
It is considered as the protection domain of the application.
Claims (10)
1. a kind of miniature photovoltaic grid-connected inverter, the direct current energy from photovoltaic panel is converted into public exchange power network with frequency
With phase AC energy and inject public electric wire net, it is characterised in that the inverter include be connected to photovoltaic panel and public affairs in turn
Power decoupled module, crisscross parallel flyback module, full-bridge inverting module and LC filtration modules between common-battery net, the power solution
Coupling module, crisscross parallel flyback module, full-bridge inverting module and LC filtration modules are connected with control unit respectively, described to interlock simultaneously
Connection flyback module includes two-way circuit of reversed excitation, and the structure and parameter of the two-way circuit of reversed excitation is identical, and in switch periods, this two
Road circuit of reversed excitation alternates 180 ° of work.
2. miniature photovoltaic grid-connected inverter according to claim 1, it is characterised in that：The circuit of reversed excitation has including realization
Source clamps the circuit unit with load-balancing function.
3. miniature photovoltaic grid-connected inverter according to claim 2, it is characterised in that：Circuit of reversed excitation described in per road is wrapped respectively
Main switch, clamp switch pipe, main transformer, active clamping circuir and current sampler are included, the main switch is placed in electric current
Between sampler and ground, the current sampler connects main transformer and main switch, and the active clamping circuir includes clamp
Electric capacity and clamp auxiliary switch, the clamping capacitance are placed between the drain electrode of main switch and the drain electrode of clamp switch pipe, institute
Clamp auxiliary switch is stated to be placed between clamping capacitance and ground.
4. miniature photovoltaic grid-connected inverter according to claim 3, it is characterised in that：Circuit of reversed excitation described in per road also includes
Output diode and filter capacitor, the output diode and filter capacitor are placed in main transformer secondary, connection rear class part.
5. miniature photovoltaic grid-connected inverter according to claim 3, it is characterised in that：The main switch is N-channel gold
Category oxide semiconductor field effect pipe, the clamp auxiliary switch is the MOSFET of P-channel.
6. miniature photovoltaic grid-connected inverter according to claim 3, it is characterised in that：The current sampler is that electric current is mutual
Sensor, the current transformer primary side connects main switch and main transformer, secondary connection sampling resistor.
7. miniature photovoltaic grid-connected inverter according to claim 1, it is characterised in that：Described control unit includes electric current loop
With feed-forward voltage ring double -loop control, the electric current loop is used to track and sample grid voltage amplitude and phase and output voltage and electricity
Stream amplitude phase, is compared with reference current value, by current compensation, coordinates electric voltage feed forward link, obtains control flyback portion
Divide the parameter of dutycycle, in output to occupancy controller, the electric current of controlled output and line voltage same-phase.
8. miniature photovoltaic grid-connected inverter according to claim 7, it is characterised in that：Described control unit also includes load
Equalization control module, the load balancing module is sampled two-way circuit of reversed excitation output average current size, root in each switch periods
Generate a small variable according to contrast difference, output in the middle of the road occupancy controller, change two-way bringing onto load it is balanced and
The driving pulse dutycycle of active-clamp characteristic circuit of reversed excitation.
9. the control method of the miniature photovoltaic grid-connected inverter described in claim 3, it is characterised in that：Circuit of reversed excitation described in per road
In, the main switch works in discontinuous mode with clamp auxiliary switch alternate conduction in switch periods, inverter.
10. the control method of miniature photovoltaic grid-connected inverter according to claim 9, it is characterised in that：In a switch
In the middle of cycle, when main switch is turned on, corresponding this road clamp auxiliary switch is closed, after main switch is turned off, by one
Corresponding this road auxiliary switch conducting after section Dead Time, before switch periods start next time, corresponding this road clamp auxiliary is opened
Close pipe to close, by after one section of Dead Time, main switch conducting starts new switch periods；Two-way band is born in Dead Time
The active-clamp flyback topologies for carrying equalization characteristic do not work, and Dead Time is more than main switch opening time maximum and clamp
Auxiliary switch turn-off time maximum sum, less than transformer primary side leakage inductance and a quarter of clamping capacitance harmonic period.
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| CN112886836A (en) * | 2021-01-18 | 2021-06-01 | 浙江大学 | Flyback micro inverter analog control circuit and peak current control method |
| CN113315401A (en) * | 2021-06-03 | 2021-08-27 | 昱能科技股份有限公司 | Micro inverter and grid-connected output control method and device thereof |
| CN113489304A (en) * | 2020-03-16 | 2021-10-08 | 北京新能源汽车股份有限公司 | Power factor correction method of inverter, controller, inverter and electric vehicle |
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