CN208461714U - A kind of double Buck full-bridge grid-connected inverter system under multiple-frequency modulation - Google Patents
A kind of double Buck full-bridge grid-connected inverter system under multiple-frequency modulation Download PDFInfo
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- CN208461714U CN208461714U CN201821427583.6U CN201821427583U CN208461714U CN 208461714 U CN208461714 U CN 208461714U CN 201821427583 U CN201821427583 U CN 201821427583U CN 208461714 U CN208461714 U CN 208461714U
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/40—Arrangements for reducing harmonics
Abstract
The utility model discloses the full-bridge grid-connected inverter system of double Buck under a kind of multiple-frequency modulation, including double Buck grid-connected inverter circuits and control circuit two parts, double full-bridge grid-connected inverter circuits of Buck are by DC input voitage E, full-bridge power switch pipe S1~S6And sustained diode1~D2, inductance LA~LDComposition；Control circuit is by reference voltage Uref, triangular carrier, PLL phase locking unit, voltage adder, multiplier, current adder, PR controller, the composition such as frequency multiplication SPWM modulator；By multiple-frequency modulation, common mode leakage current available effective inhibition while the inductance volume of double Buck gird-connected inverters reduces, system cost is reduced；And the freewheeling path not poor body diode of passage capacity, reduces reverse recovery loss, realizes inverter being isolated in freewheeling period power grid and DC voltage, total harmonic distortion factor reduces, and inverter efficiency and reliability improve.
Description
Technical field
The utility model relates to photovoltaic combining inverter fields, and in particular to double Buck full-bridges under a kind of multiple-frequency modulation are simultaneously
Net inverter system.
Background technique
The existing full-bridge grid-connected inverter of double Buck with no common mode leakage current, loss is small, DC voltage utilization rate is high, defeated
Out the advantages that three level, but there are two bulky DC inductances in its inverter circuit, and when circuit works, always only one
A inductance is in running order, leads to that magnetic element utilization rate is low, system cost is high, power density becomes smaller；Meanwhile double Buck are complete
Decoupling is not implemented between bridge gird-connected inverter DC side and exchange side, this makes grid-connected current DC component content higher.If adopting
With bipolarity multiple-frequency modulation strategy, the equivalent operation frequency of gird-connected inverter topology is original 2 times, defeated so as to reduce
Current ripples, reduction grid-connected current harmonic content, the volume for making output filter and loss decline out.And existing dual-buck
Gird-connected inverter can generate biggish common mode leakage current according to multiple-frequency modulation again, reduce power grid quality.
Summary of the invention
For above-mentioned deficiency in the prior art, double Buck full-bridges under a kind of multiple-frequency modulation provided by the utility model are simultaneously
Net inverter system, can solve that existing double step-down combining inverter current harmonic content is big, alternating current-direct current side is not isolated and filters
Big, the at high cost problem of inductance volume.
The technical solution that the utility model solves above-mentioned technical problem is as follows: double Buck full-bridges under a kind of 1. multiple-frequency modulations
Grid-connected inverter system, including the full-bridge grid-connected inverter circuit of double Buck and control circuit two parts, double full-bridge grid-connected inversions of Buck
Circuit is by DC input voitage E, full-bridge power switch pipe S1~S6With four sustained diodes1~D2, inductance LA~LDComposition；
The switching tube and four freewheeling diodes collectively constitute inverter, are responsible for DC voltage being converted to alternating voltage, institute
The inductance L statedA~LDFor circuit filtering；Control circuit is by reference voltage Uref, triangular carrier, PLL phase locking unit, voltage adder
The composition such as device, multiplier, current adder, PR controller, frequency multiplication SPWM modulator, the reference voltage UrefWith direct current
It flows E and is sent into the voltage adder, the signal multiplication that obtained error signal and the PLL phase locking unit obtain is grid-connected electricity
Flow reference signal iref, actual current signal i in double full-bridge grid-connected inverter circuits of BuckgWith grid-connected current reference signal
irefIt is poor to make in current adder, and error signal passes through the PR controller, described in conjunction with the triangular carrier
Frequency multiplication SPWM modulator be to produce the PWM wave driving power switch tube S1~S6。
Further, the power switch tube S1~S6It is metal-oxide half field effect transistor MOSFET, the power switch
Pipe S5Drain electrode and DC voltage UdcAnode is connected, the power switch tube S5Source electrode respectively with power switch tube S1Leakage
Pole, diode D2Cathode, power switch tube S3Drain electrode and diode D4Cathode be connected；The power switch tube S6's
Source electrode and UdcCathode is connected, the power switch tube S6Drain electrode respectively with power switch tube S2Source electrode, diode D1Just
Pole, power switch tube S4Source electrode and diode D3Anode be connected；The power switch tube S1Grid as node A simultaneously
Respectively with diode D1Cathode and inductance LAOne end be connected；The power switch tube S1Source electrode as node A and respectively with
D1Cathode and inductance LAOne end be connected；The inductance LDThe other end as output end G, output end G be grounded；Two pole
Pipe D2Anode as node B and respectively with switching tube S2Drain electrode and inductance LBOne end be connected；The power switch tube S3
Source electrode as node D and respectively with diode D3Cathode, inductance LBOne end and inductance LDOne end be connected；Two pole
Pipe D4Anode as node C and respectively with S4Drain electrode, inductance LAOne end and inductance LCOne end be connected.
The utility model has the following beneficial effects:
The full-bridge grid-connected inverter system of double Buck under multiple-frequency modulation, realized in structure exchange side and DC side every
From reducing the DC component of grid-connected voltage；Switching frequency rises to original 2 times, it is hereby achieved that higher output is electric
Voltage-frequency rate, power network current total harmonic distortion factor reduce；Multiple-frequency modulation is used in control, filter inductance volume reduces, cost reduces,
The also available effective inhibition of resulting common mode leakage current.
Detailed description of the invention
Fig. 1 is the circuit system schematic diagram of the utility model；
Fig. 2 is output voltage u of the utility model under multiple-frequency modulationAB, uCDWaveform diagram and power switch tube S1~S6It drives
Dynamic waveform diagram；
Fig. 3 is the equivalent common mode resonance circuit diagram of the inverter circuit in positive half period of the utility model；
Fig. 4 is the equivalent common mode resonance circuit diagram of the inverter circuit in negative half-cycle of the utility model；
Fig. 5 is the grid-connected current modulated using frequency multiplication SPWM, Voltage experiments waveform；
Fig. 6 is output voltage, the leakage current experimental waveform modulated using frequency multiplication SPWM；
Fig. 7 is that the THD modulated using frequency multiplication SPWM contains spirogram.
Specific embodiment
Specific embodiment of the present utility model is described below.
As shown in Figure 1, the full-bridge grid-connected inverter system of double Buck under a kind of multiple-frequency modulation, including double Buck are full-bridge grid-connected
Inverter circuit and control circuit two parts, double full-bridge grid-connected inverter circuits of Buck are by DC input voitage E, full-bridge power switch pipe
S1~S6With four sustained diodes1~D2, inductance LA~LDComposition；Switching tube and four freewheeling diodes collectively constitute inversion
Device is responsible for DC voltage being converted to alternating voltage, inductance LA~LDFor circuit filtering；Control circuit is by reference voltage
Uref, triangular carrier, PLL phase locking unit, voltage adder, multiplier, current adder, PR controller, frequency multiplication SPWM modulator etc.
Composition, reference voltage UrefVoltage adder, the signal that obtained error signal and PLL phase locking unit obtain are sent into DC current E
Being multiplied is grid-connected current reference signal iref, actual current signal i in double full-bridge grid-connected inverter circuits of BuckgWith grid-connected electricity
Flow reference signal irefIt is poor to make in current adder, and error signal passes through PR controller, in conjunction with triangular carrier, frequency multiplication
SPWM modulator produces PWM wave driving power switching tube S1~S6.Power switch tube S1~S6It is OH crystal
Pipe MOSFET, power switch tube S5Drain electrode and DC voltage UdcAnode is connected, power switch tube S5Source electrode respectively with function
Rate switching tube S1Drain electrode, diode D2Cathode, power switch tube S3Drain electrode and diode D4Cathode be connected；Power
Switching tube S6Source electrode and UdcCathode is connected, power switch tube S6Drain electrode respectively with power switch tube S2Source electrode, diode
D1Anode, power switch tube S4Source electrode and diode D3Anode be connected；Power switch tube S1Grid as node A
And respectively with diode D1Cathode and inductance LAOne end be connected；Power switch tube S1Source electrode as node A and respectively with D1
Cathode and inductance LAOne end be connected；Inductance LDThe other end as output end G, output end G be grounded；Diode D2Anode
As node B and respectively with switching tube S2Drain electrode and inductance LBOne end be connected；Power switch tube S3Source electrode as node
D and respectively with diode D3Cathode, inductance LBOne end and inductance LDOne end be connected；Diode D4Anode as node C
And respectively with S4Drain electrode, inductance LAOne end and inductance LCOne end be connected.
In one embodiment of the utility model, for the power switch tube S for reducing device1~S6Switching loss, this is inverse
Variable topological works in such a way that the half period controls.Power switch tube S1、S2、S5、S6It works in positive half period, power switch tube S3、
S4、S5、S6It works in negative half-cycle.Driving and output voltage u of the system under frequency multiplication SPWM modulation strategyAB, uCDWaveform such as Fig. 2
It is shown.Wherein power switch tube S5Driving signal in positive half period and power switch tube S4It is identical, it is opened in negative half-cycle and power
Close pipe S2It is identical.
For the common mode leakage current for analyzing this inverter, its common mode equivalent resonance circuit need to be established.Ground capacity CPVWith every
Effect from DC power supply, therefore common mode leakage current itcmIt is only related with alternating-current voltage source.When not considering DC power supply UdcTo itcm
Influence when, as can be seen from Figure 3 in positive half period power switch tube S1、S2、S5、S6Work, power switch tube S3、S4It turns off always,
It is as shown in Figure 3 in the equivalent common mode resonance circuit of positive half period that the inversion topological can be obtained in conjunction with Fig. 1.Similarly, Fig. 4 is negative half-cycle
Equivalent common mode resonance circuit.Wherein, uAN、uBN、uCNAnd uDNRespectively inverter leg midpoint A, B, C, D are to DC voltage cathode N
Between voltage.
According to prior art common-mode voltage u effective to inverterecmCarry out derive, the u of Fig. 3 can be obtainedecmAre as follows:
In formula (1), uecmFor equivalent common-mode voltage, ucmFor common-mode voltage, udmFor differential mode voltage, and:
ucm=uAB=uCN-uDN (3)
By formula (1) it is found that working as LC+LA≠LD+LBWhen, udmProduct term is not zero.It therefore, is elimination udmTo common mode leakage current
Influence, enable L1+LA=L4+LB.L is enabled for convenience of analysisC=LD；LA=LB, then formula (1) can be rewritten as:
Calculate leakage current itcm, formula may be expressed as:
In formula (5), CPVFor ground capacity, t is time variable；
Convolution (4) and formula (5) formula are it is found that if uAN+uBNIt is kept constant in positive half period, then can effectively inhibit positive half cycle
The common mode leakage current of phase.
Similarly analysis chart 4 can obtain the u of negative half-cycleecmAre as follows:
Therefore, if uCN+uDNIt is kept constant in negative half-cycle, then can effectively inhibit the common mode leakage current of negative half-cycle.
And the utility model proposes topology and its modulation strategy in, according to igDirection and power switch tube S1~S6
Switch conditions, which has six kinds of operational modals in single power frequency period, and every kind of mode is all satisfied:
Therefore the common mode leakage current i of frequency multiplication SPWM modulation system is usedtcm=0, the common mode electric leakage of double Buck gird-connected inverters
Stream is effectively suppressed, and inductance volume can reduce, reduce cost；And freewheeling path not poor two pole of body of passage capacity
Pipe, reduces reverse recovery loss, realizes inverter being isolated in freewheeling period power grid and DC voltage, inverter can be improved
Efficiency and reliability.
For the correctness of proof theory analysis and the reasonability of parameter designing, the utility model is emulated in MATLAB7.1
Emulation platform has been built in software to emulate to using the full-bridge grid-connected inverter of double Buck of frequency multiplication SPWM modulation strategy respectively
Verifying.
The main circuit specific experiment parameter of double full-bridge grid-connected inverters of Buck, as shown in table 1:
1 simulation parameter of table
Fig. 5 is network voltage ugidWith grid current igWaveform, it can be seen from the figure that ugidAnd igSame-phase is kept, it is defeated
Grid-connected voltage u outgidFor 220V, grid-connected current igFor 15A.Fig. 6 is inverter output voltage uABWith common mode leakage current itcmWaveform.
As seen from the figure, plan is modulated by frequency multiplication SPWM, realizes positive half period and negative half-cycle inverter output voltage uABRespectively in 0V and
Change between 360V, between 0V and -360V with 2 times of switching frequency, that is, 10KHZ frequencies, so that THD value reduces, mentions
High and network electric energy quality.Common mode leakage current itcm5mA or so is substantially remained in, only amplitude is larger in zero crossing, and maximum is no more than
90mA meets the standard of DIN V VDE V 0126-1-1.
It can be obtained by Fig. 7, emulation measures when the system topological use multiple-frequency modulation that only THD is 0.15%, compares using monopole
Traditional dual Buck inverter of property SPWM modulation strategy, THD value reduce nearly 85%, substantially increase grid-connected current quality；
Due to switching tube S5、S6So that DC side is realized decoupling with side is exchanged, so grid-connected current DC component is only 0.03%, compares
Using traditional dual Buck inverter of Unipolar SPWM modulation strategy, DC component is also significantly reduced.
In conclusion the utility model proposes a kind of multiple-frequency modulation under double Buck grid-connected inverter circuits can be great
It improves and network electric energy quality, THD reduces nearly 85%；And the simultaneously raising of network electric energy quality, reduce filter inductance volume and
Cost improves the power density of system.Inverter direct-flow side is isolated with exchange side, so that grid-connected current DC component is significantly
Reduce, further improves simultaneously network electric energy quality.
Claims (2)
1. the full-bridge grid-connected inverter system of double Buck under a kind of multiple-frequency modulation, including the full-bridge grid-connected inverter circuit of double Buck and control
Circuit two parts processed, it is characterised in that: double full-bridge grid-connected inverter circuits of Buck are by DC input voitage E, full-bridge power switch pipe
S1~S6With four sustained diodes1~D2, inductance LA~LDComposition；The switching tube and four common group of freewheeling diode
At inverter, it is responsible for DC voltage being converted to alternating voltage, the inductance LA~LDFor circuit filtering；Control circuit
By reference voltage Uref, triangular carrier, PLL phase locking unit, voltage adder, multiplier, current adder, PR controller, frequency multiplication
The composition such as SPWM modulator, the reference voltage UrefThe voltage adder, obtained error are sent into DC current E
The signal multiplication that signal and the PLL phase locking unit obtain is grid-connected current reference signal iref, double Buck are full-bridge grid-connected inverse
Actual current signal i in power transformation roadgWith grid-connected current reference signal irefIt is poor to make in current adder, error signal warp
The PR controller is crossed, in conjunction with the triangular carrier, the frequency multiplication SPWM modulator produces PWM wave and drives institute
The power switch tube S stated1~S6。
2. the full-bridge grid-connected inverter system of double Buck under a kind of multiple-frequency modulation according to claim 1, it is characterised in that:
The power switch tube S1~S6It is metal-oxide half field effect transistor MOSFET, the power switch tube S5Drain electrode and direct current
Voltage UdcAnode is connected, the power switch tube S5Source electrode respectively with power switch tube S1Drain electrode, diode D2It is negative
Pole, power switch tube S3Drain electrode and diode D4Cathode be connected；The power switch tube S6Source electrode and UdcCathode is connected
It connects, the power switch tube S6Drain electrode respectively with power switch tube S2Source electrode, diode D1Anode, power switch tube S4
Source electrode and diode D3Anode be connected；The power switch tube S1Grid as node A and respectively with diode D1It is negative
Pole and inductance LAOne end be connected；The power switch tube S1Source electrode as node A and respectively with D1Cathode and inductance LA's
One end is connected；The inductance LDThe other end as output end G, output end G be grounded；The diode D2Anode as section
Point B and respectively with switching tube S2Drain electrode and inductance LBOne end be connected；The power switch tube S3Source electrode as node D
And respectively with diode D3Cathode, inductance LBOne end and inductance LDOne end be connected；The diode D4Anode as section
Point C and respectively with S4Drain electrode, inductance LAOne end and inductance LCOne end be connected.
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| CN201821427583.6U CN208461714U (en) | 2018-09-03 | 2018-09-03 | A kind of double Buck full-bridge grid-connected inverter system under multiple-frequency modulation |
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| CN201821427583.6U CN208461714U (en) | 2018-09-03 | 2018-09-03 | A kind of double Buck full-bridge grid-connected inverter system under multiple-frequency modulation |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112187072A (en) * | 2020-10-29 | 2021-01-05 | 哈尔滨理工大学 | Low-voltage large-current output rectifier |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112187072A (en) * | 2020-10-29 | 2021-01-05 | 哈尔滨理工大学 | Low-voltage large-current output rectifier |
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| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CB03 | Change of inventor or designer information | ||
| CB03 | Change of inventor or designer information |
Inventor after: Li Jia Inventor after: Lin Chunxu Inventor after: Mao Dengyu Inventor after: Ren Jinzhou Inventor after: Dai Yunzhong Inventor before: Li Jia Inventor before: Lin Chunxu Inventor before: Mao Dengyu Inventor before: Ren Jinzhou |
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| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20190201 Termination date: 20190903 |