CN207283412U - The common ground type isolation quasi- Z source converters of high-gain of fuel cell and photovoltaic generation - Google Patents
The common ground type isolation quasi- Z source converters of high-gain of fuel cell and photovoltaic generation Download PDFInfo
- Publication number
- CN207283412U CN207283412U CN201721283340.5U CN201721283340U CN207283412U CN 207283412 U CN207283412 U CN 207283412U CN 201721283340 U CN201721283340 U CN 201721283340U CN 207283412 U CN207283412 U CN 207283412U
- Authority
- CN
- China
- Prior art keywords
- capacitance
- diode
- oxide
- semiconductor
- metal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 238000002955 isolation Methods 0.000 title claims abstract description 11
- 239000000446 fuel Substances 0.000 title claims abstract description 10
- 239000004065 semiconductor Substances 0.000 claims abstract description 49
- 230000005611 electricity Effects 0.000 claims description 10
- 238000010586 diagram Methods 0.000 description 6
- 230000014509 gene expression Effects 0.000 description 6
- 230000000875 corresponding effect Effects 0.000 description 4
- 230000001939 inductive effect Effects 0.000 description 3
- 238000010248 power generation Methods 0.000 description 3
- 230000002596 correlated effect Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000004088 simulation Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000000686 essence Substances 0.000 description 1
- 230000002045 lasting effect Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000003071 parasitic effect Effects 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Dc-Dc Converters (AREA)
Abstract
The utility model provides the common ground type isolation quasi- Z source converters of high-gain of fuel cell and photovoltaic generation, mainly includes input dc power potential source, by the first inductance, first capacitance, the quasi- Z source networks that first diode, the second inductance and the second capacitance are formed, by the second diode, 3rd diode, the quasi- boost switching unit that 3rd capacitance, the 3rd metal-oxide-semiconductor and the 4th metal-oxide-semiconductor are formed, the first metal-oxide-semiconductor, second metal-oxide-semiconductor, no-load voltage ratio 1:nHigh frequency transformer, by the 4th capacitance, the 5th capacitance, the voltage-doubler rectifier and load resistance that the 4th diode and the 5th diode are formed.Whole circuit structure is simple, mains input current is continuous, combine quasi- Z source impedance networks and the respective single-stage buck characteristic of quasi- boost switching network, make it have the output voltage gain of higher, and the electric isolution between converter output and input is realized by high frequency transformer, and there is no the dash current that inrush current and switching tube open moment for circuit.
Description
Technical field
It the utility model is related to converters technical field, and in particular to one kind is suitable for fuel cell and photovoltaic
The common ground type isolation quasi- Z sources DC converter of high-gain of power generation.
Background technology
In recent years, with expanding economy, the increasingly increase of energy demand and as the ring caused by traditional fossil energy
Border pollution problem becomes to be on the rise.In order to realize sustainable development, people begin to focus on the hair of reproducible cleaning new energy
Exhibition and application.Generation of electricity by new energy is exactly one of application, and renewable energy power generation mainly includes water conservancy, solar energy, wind energy, fuel
Battery etc..But since the output voltage grade of fuel cell and solar photovoltaic cell panel is relatively low and fluctuation range is larger, no
It can meet some existing electrical equipments and grid-connected requirement, therefore usually require to change low tension by boosting DC/DC converters
For stable high voltage direct current, then pass through grid-connected inverters again.In recent years related scholar propose Z sources DC-DC converter and
Boost switching DC-DC converter, although each of which is utilized respectively Z source impedance networks and boost switching real-time performance output electricity
The lifting of pressure, but since parasitic parameter and the limitation of loss, their corresponding voltage gains still have greatly improved space, and
Often existing in many application scenarios needs to realize electric isolution between the output of converter and input, therefore the high increasing of isolated form
The research and development of beneficial DC-DC converter becomes more and more important.
Utility model content
The purpose of the utility model is to overcome above-mentioned the deficiencies in the prior art, there is provided one kind is suitable for fuel cell and light
The common ground type isolation quasi- Z sources DC-DC converter with higher output voltage gain of volt power generation, concrete technical scheme are as follows.
The common ground type isolation quasi- Z sources DC converting of high-gain for being suitable for fuel cell and photovoltaic generation of the utility model
Device, specifically includes input dc power potential source, by the first inductance, the first capacitance, the first diode, the second inductance and the second capacitance structure
Into quasi- Z source networks, the standard being made of the second diode, the 3rd diode, the 3rd capacitance, the 3rd metal-oxide-semiconductor and the 4th metal-oxide-semiconductor opens
Close boosting unit, the first metal-oxide-semiconductor, the second metal-oxide-semiconductor, no-load voltage ratio 1:The high frequency transformer T of n, by the 4th capacitance Co1, the 5th capacitance
Co2, the 4th diode Do1With the 5th diode Do2The voltage-doubler rectifier and load resistance R of compositionL。
Further, the one end in the DC input voitage source is connected with one end of the first inductance；First inductance
The other end is connected with the anode of the first diode and the anode of the first capacitance respectively；The cathode of first diode is respectively with
One end of two inductance is connected with the cathode of the second capacitance；The other end of second inductance respectively the anode with the second diode,
The cathode of the drain electrode of metal-oxide-semiconductor and the first capacitance connects；The cathode of second diode respectively with the cathode of the 3rd capacitance and
The drain electrode connection of first metal-oxide-semiconductor；The anode of 3rd capacitance respectively with the source electrode of the 4th metal-oxide-semiconductor and the anode of the 3rd diode
Connection；The drain electrode with the primary side positive polarity input terminal and the second metal-oxide-semiconductor of high frequency transformer respectively of the source electrode of first metal-oxide-semiconductor
Connection；The anode and input DC power of the cathode of 3rd diode source electrode with the second metal-oxide-semiconductor, the second capacitance respectively
Anode connection；The source electrode of 3rd metal-oxide-semiconductor respectively with the drain electrode of the 4th metal-oxide-semiconductor and the primary side negative polarity of high frequency transformer
Input terminal connects；The cathode of 4th capacitance is connected with the cathode of the 4th diode and one end of load respectively；Described 4th
The anode of capacitance is connected with the positive ends of Circuit Fault on Secondary Transformer and the cathode of the 5th capacitance respectively；The anode of 5th capacitance
It is connected respectively with the anode of the 5th diode and the other end of load；The cathode of 5th diode respectively with the 4th diode
Anode connected with the negative polarity end of Circuit Fault on Secondary Transformer.
The utility model has the following advantages that compared with prior art：Develop hidden inside quasi- boost switching unit
The metal-oxide-semiconductor hidden, without additionally addition power switch pipe can realize a full bridge structure, simple in structure, controlling party again
Just；And quasi- Z sources DC-DC converter (its output voltage gain is G=2n/ (1-3D)) is cascaded compared to traditional isolated form,
In the case of identical input voltage and duty cycle, the utility model circuit can be in few situation with an inductance and capacitance
Under, the output voltage gain with higher is G=2n/ (1-4D).And input power electric current is continuous, there is no circuit start impact
Electric current etc., thus the utility model circuit have be widely applied very much prospect.
Brief description of the drawings
Fig. 1 is a kind of electricity of the embodiment of the isolation of type altogether quasi- Z sources DC-DC converter of high-gain described in the utility model
Lu Tu；
Fig. 2 a, Fig. 2 b, Fig. 2 c, Fig. 2 d are groundwork modal graph of the circuit diagram shown in Fig. 1 in a switch periods.
Fig. 3 a are converter described in the utility model and the output electricity of traditional isolated form cascade quasi- Z sources DC-DC converter
Press gain contrast curve map.
Fig. 3 b are with Vdc=10V, duty cycle D=0.2, the utility model electricity is given exemplified by the no-load voltage ratio n=1 of high frequency transformer
The simulation result figure and inductive current i of correlated variables in roadL1And iL2Waveform and high frequency transformer primary side input voltage Vpr
Waveform.
Embodiment
With reference to embodiments and attached drawing is described in further detail the utility model explanation, but the utility model
Embodiment not limited to this.It is noted that if the following process or parameter for having not special detailed description, is art technology
Personnel can refer to the prior art understand or realize.
The Basic Topological of the present embodiment is as shown in Figure 1.In order to easy to verify, the device in circuit structure is accordingly to be regarded as managing
Think device.And set the first inductance L1Electric current is iL1, the second inductance L2Electric current is iL2, the first capacitance C1Voltage is VC1, second electricity
Hold C2Voltage is VC2, the 3rd capacitance C3Voltage is VC3。
Fig. 2 a, Fig. 2 b, Fig. 2 c, Fig. 2 d are groundwork modal graph of the circuit diagram shown in Fig. 1 in a switch periods.Its
Middle Fig. 2 a are (the metal-oxide-semiconductor S of operation mode 11、S2、S3、S4Be both turned on) equivalent circuit diagram, Fig. 2 b are (the metal-oxide-semiconductor S of operation mode 21、
S4Shut-off, S2、S3Conducting) circuit diagram, Fig. 2 c are (the metal-oxide-semiconductor S of operation mode 31、S3Shut-off, S2、S4It is open-minded) circuit diagram, figure
2d is (the metal-oxide-semiconductor S of operation mode 41、S4It is open-minded, S2、S3Shut-off) circuit diagram.Solid line represents have electric current to flow through in converter in figure
Part.
As shown in Fig. 2 a, Fig. 2 b, Fig. 2 c and Fig. 2 d, type isolates the quasi- Z sources DC-DC converter of high-gain at one altogether for this
Mainly there are 4 operation modes in switch periods, be described as follows respectively：
Operation mode 1：As shown in Figure 2 a, metal-oxide-semiconductor (S1、S2、S3、S4) be both turned on, the first diode D1, the second diode D2
With the 3rd diode D3Reversely cut-off shut-off.Then input voltage source V at this timedcWith the first capacitance C1And the 3rd capacitance C3Series connection,
The first inductance L is given together1Charging；Second capacitance C2With the 3rd capacitance C3The second inductance L is given in series connection together2Charging.At this time, high frequency
Transformer primary side is due to positive in parallel with the 3rd capacitance C3, then its primary side input voltage is Vpr=VC3, by high frequency transformation
Secondary side voltage V after devicescFor on the occasion of n*VC3, then the 4th diode Do1Reversely cut-off shut-off, the 5th diode Do2Forward bias is led
It is logical.
Under this operation mode, associated electrical parameters relational expression is：
VL1=Vdc+VC1+VC3 (1)
VL2=VC2+VC3 (2)
Vpr=VC3,Vsc=nVC3 (3)
Operation mode 2：As shown in Figure 2 b, the first metal-oxide-semiconductor S1, the 4th metal-oxide-semiconductor S4Shut-off, the second metal-oxide-semiconductor S2, the 3rd metal-oxide-semiconductor
S3It is open-minded, the first diode D1, the second diode D2With the 3rd diode D3Conducting.Then input voltage source V at this timedcWith the first electricity
L1 series connection is felt together to the second capacitance C2Charging；Second inductance L2To the first capacitance C1Charging；Input power VdcWith the first inductance
L1, the second inductance L2Connect to the 3rd capacitance C3Charging.At this time, high frequency transformer primary side is and the 3rd capacitance C3Reverse parallel connection,
Therefore its primary side input voltage is Vpr=-VC3, the secondary side voltage V after high frequency transformerscAlso it is negative value Vsc=-n*VC3,
Then the 4th diode Do1Positively biased turns on, the 5th diode Do2Reverse-biased shut-off.Under this operation mode, associated electrical parameters relational expression
For：
VL1=Vdc-VC2 (4)
VL2=-VC1 (5)
VC3=VC1+VC2 (6)
Vpr=-VC3,Vsc=-nVC3 (7)
Operation mode 3：As shown in Figure 2 c, the first metal-oxide-semiconductor metal-oxide-semiconductor S1, the 3rd metal-oxide-semiconductor S3Shut-off, the second metal-oxide-semiconductor S2, the 4th
Metal-oxide-semiconductor S4It is open-minded.At this time, since high frequency transformer primary side passes through the 3rd diode D3Short circuit together, therefore its primary side and
Secondary side voltage is equal to zero：Vpr=Vsc=0, then the 4th diode Do1With the 5th diode Do2All reverse-biased shut-off.This Working mould
Under state, associated electrical parameters relational expression is：
VL1=Vdc-VC2 (8)
VL2=-VC1 (9)
VC3=VC1+VC2 (10)
Vpr=Vsc=0 (11)
Operation mode 4：As shown in Figure 2 d, the first metal-oxide-semiconductor metal-oxide-semiconductor S1, the 4th metal-oxide-semiconductor S4It is open-minded, the second metal-oxide-semiconductor S2, the 3rd
Metal-oxide-semiconductor S3Shut-off.At this time, high frequency transformer primary side and the 3rd capacitance C3It is positive in parallel, therefore its primary side input voltage is Vpr
=VC3, the secondary side voltage V after high frequency transformerscFor on the occasion of Vsc=nVC3, then the 4th diode Do1Reverse-biased shut-off, the 5th
Diode Do2Forward bias turns on.Under this operation mode, associated electrical parameters relational expression is：
VL1=Vdc-VC2 (12)
VL2=-VC1 (13)
VC3=VC1+VC2 (14)
Vpr=VC3,Vsc=nVC3 (15)
Analyzed more than, to the first inductance L1, the second inductance L2Voltage-second balance principle principle, that is, inductive drop is used respectively
Average value in a switch periods is zero, and sets the time that all metal-oxide-semiconductors are both turned on (namely operation mode one is lasting
Time) it is DTs, the corresponding straight-through duty cycle of wherein D expressions, TsRepresent corresponding switch periods, then other three operation modes are all
Belong to non-pass-through state, duration is (1-D) Ts.Capacitance when simultaneous formula (1), (2), (4), (5) and (6) can try to achieve stable state
The expression formula of voltage is：
Then after high frequency transformer and voltage-doubler rectifier, the output voltage at load resistance both ends is：
Electricity when then a kind of quasi- Z sources DC-DC converter stable state of the isolation of type altogether high-gain described in the utility model exports
Pressure gain G be：
As shown in Figure 3a quasi- Z sources DC- is cascaded for the output voltage gain curve and traditional isolated form of the utility model circuit
The voltage gain curve of DC converters compares figure；Red solid line represents that the output voltage gain of the utility model circuit is bent in figure
Line, blue solid lines represent the voltage gain curve of traditional isolated form cascade quasi- Z sources DC-DC converter.As seen from the figure, this practicality is new
For type circuit in the case where duty cycle D is no more than 0.25, output voltage gain G can reach very big, hence it is evident that higher than its tradition
Isolated form cascades the voltage gain of quasi- Z sources DC-DC converter, and the duty cycle D of the utility model circuit is not over 0.25.
Fig. 3 b are with Vdc=10V, duty cycle D=0.2, the utility model electricity is given exemplified by the no-load voltage ratio n=1 of high frequency transformer
The simulation result of correlated variables in road.When D=0.2, n=1, corresponding output voltage gain G=10, capacitance voltage VC1=20V,
VC2=30V, VC3=50V, after high frequency transformer and voltage-doubler rectifier, output voltage Vo=100V.In addition, in Fig. 3 b also
Give inductive current iL1And iL2Waveform and high frequency transformer primary side input voltage VprWaveform.
In conclusion the utility model proposes one kind altogether type isolation the quasi- Z sources DC-DC converter of high-gain, with tradition
Isolated form cascade quasi- Z sources DC-DC converter compare, reduce the usage quantity of passive element, without extra power switch
Pipe, it is simple in structure, it is easy to control；Input power electric current is continuous；And in the case of identical input voltage and duty cycle, have
The output voltage gain of higher, inrush current is not present in circuit start moment, therefore the utility model circuit has very
It is widely applied prospect.
Above-described embodiment is the preferable embodiment of the utility model, but the embodiment of the utility model and from described
The limitation of embodiment, the change made under other any Spirit Essences and principle without departing from the utility model, modify, replace
Generation, combination, simplify, and should be equivalent substitute mode, is included within the scope of protection of the utility model.
Claims (2)
1. the common ground type isolation quasi- Z source converters of high-gain of fuel cell and photovoltaic generation, it is characterised in that including direct current
Potential source (V dc), by the first inductance (L 1), the first capacitance (C 1), the first diode (D 1), the second inductance (L 2), the second capacitance (C 2)
The quasi- Z source impedance networks formed, by the second diode (D2), the 3rd diode (D3), the 3rd capacitance (C3), the 3rd metal-oxide-semiconductor (S3)
With the 4th metal-oxide-semiconductor (S4) form quasi- boost switching unit, the first metal-oxide-semiconductor (S1), the second metal-oxide-semiconductor (S2), no-load voltage ratio 1:nHeight
Frequency power transformerT, by the 4th capacitance (C o1), the 5th capacitance (C o2), the 4th diode (D o1) and the 5th diode (D o2) form times
Press rectifier and load resistanceR L 。
2. the common ground type isolation quasi- Z source converters of high-gain of fuel cell according to claim 1 and photovoltaic generation, its
It is characterized in that：The direct voltage source (V dc) one end and the first inductance（L1）One end connection；First inductance（L1）'s
The other end respectively with the first diode（D1）Anode and the first capacitance（C1）Anode connection；First diode（D1）'s
Cathode respectively with the second inductance（L2）One end and the second capacitance（C2）Cathode connection；Second inductance（L2）The other end
Respectively with the second diode（D2）Anode, metal-oxide-semiconductor（S3）Drain electrode and the first capacitance（C1）Cathode connection；Described second
Diode（D2）Cathode respectively with the 3rd capacitance（C3）Cathode and the first metal-oxide-semiconductor（S1）Drain electrode connection；3rd capacitance
（C3）Anode respectively with the 4th metal-oxide-semiconductor（S4）Source electrode and the 3rd diode（D3）Anode connection；First metal-oxide-semiconductor
（S1）Source electrode respectively with high frequency transformer（T）Primary side positive polarity input terminal and the second metal-oxide-semiconductor（S2）Drain electrode connection；Institute
Stating the cathode of the 3rd diode (D3), the source electrode with the second metal-oxide-semiconductor (S2), the anode of the second capacitance (C2) and input are straight respectively
The anode connection in galvanic electricity source (Vdc)；3rd metal-oxide-semiconductor（S3）Source electrode respectively with the 4th metal-oxide-semiconductor（S4）Drain electrode and high frequency become
Depressor（T）Primary side negative polarity input terminal connection；4th capacitance（Co1）Cathode respectively with the 4th diode（Do1）'s
Cathode and load（R L ）One end connection；4th capacitance（Co1）Anode respectively with transformer（T）The positive polarity of secondary side
End and the 5th capacitance（Co2）Cathode connection；5th capacitance（Co2）Anode respectively with the 5th diode（Do2）Anode
And load（R L ）The other end connection；5th diode（Do2）Cathode respectively with the 4th diode（Do1）Anode and change
Depressor（T）The negative polarity end connection of secondary side.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201721283340.5U CN207283412U (en) | 2017-09-30 | 2017-09-30 | The common ground type isolation quasi- Z source converters of high-gain of fuel cell and photovoltaic generation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201721283340.5U CN207283412U (en) | 2017-09-30 | 2017-09-30 | The common ground type isolation quasi- Z source converters of high-gain of fuel cell and photovoltaic generation |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN207283412U true CN207283412U (en) | 2018-04-27 |
Family
ID=61987534
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201721283340.5U Expired - Fee Related CN207283412U (en) | 2017-09-30 | 2017-09-30 | The common ground type isolation quasi- Z source converters of high-gain of fuel cell and photovoltaic generation |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN207283412U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107612349A (en) * | 2017-09-30 | 2018-01-19 | 华南理工大学 | The common ground type isolation quasi- Z source converters of high-gain of fuel cell and photovoltaic generation |
| CN112234821A (en) * | 2020-11-13 | 2021-01-15 | 燕山大学 | High-gain direct-current converter topological structure based on active network |
-
2017
- 2017-09-30 CN CN201721283340.5U patent/CN207283412U/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107612349A (en) * | 2017-09-30 | 2018-01-19 | 华南理工大学 | The common ground type isolation quasi- Z source converters of high-gain of fuel cell and photovoltaic generation |
| CN112234821A (en) * | 2020-11-13 | 2021-01-15 | 燕山大学 | High-gain direct-current converter topological structure based on active network |
| CN112234821B (en) * | 2020-11-13 | 2021-09-14 | 燕山大学 | High-gain direct-current converter topological structure based on active network |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN105958823B (en) | A kind of quasi- Z source converter circuit of electric current continuous type high-gain boost switching | |
| CN206698111U (en) | It is a kind of using switched inductors and the quasi- boost switching DC DC converters of switching capacity | |
| TWI635697B (en) | Interleaved high-step-up zero-voltage switching dc-dc converter | |
| CN209120060U (en) | High-gain DC/DC converter and power-supply system based on coupling inductance | |
| TWI594554B (en) | Interleaved high efficiency high-step-up direct current transformer | |
| CN105939126B (en) | A kind of quasi- Z-source inverter of switched inductors type mixing | |
| CN106787757B (en) | A kind of CLTCL resonance DC converter | |
| CN205847093U (en) | A kind of electric current continuous high-gain boost switching quasi-Z source converter circuit | |
| CN105186912B (en) | A kind of non-isolated full-bridge grid-connected inverter of two-stage type | |
| CN109004835A (en) | The quasi- source the Z DC-DC converter of isolated form high-gain suitable for photovoltaic power generation | |
| CN110224601A (en) | A kind of high-gain Boost and its working method based on three winding coupling inductance | |
| CN102638164B (en) | High boost circuit, solar inverter and solar cell system | |
| CN105939112A (en) | High-gain quasi-switch boost DC-DC converter | |
| TWI664797B (en) | Dc power converter with high voltage gain | |
| TW202002491A (en) | Interleaved ultra-high boost converter capable of reducing current stress of energy storage elements and switching elements in a circuit | |
| CN106026728A (en) | Photovoltaic micro inverter | |
| CN107612349A (en) | The common ground type isolation quasi- Z source converters of high-gain of fuel cell and photovoltaic generation | |
| CN207283412U (en) | The common ground type isolation quasi- Z source converters of high-gain of fuel cell and photovoltaic generation | |
| CN107565814A (en) | A kind of quasi- Z source switch boosting inverters of high-gain suitable for fuel cell power generation | |
| CN110504833A (en) | A kind of high-gain boost converter based on active electric network | |
| CN206422691U (en) | A kind of type high-gain Z sources DC DC converters altogether | |
| CN106849643A (en) | A kind of switching capacity type mixes quasi- Z source converters | |
| CN207368879U (en) | A kind of quasi- boost switching DC/DC converters of the high-gain of low voltage stress | |
| CN106452152A (en) | Switch boost type high-gain quasi-Z-source inverter | |
| CN205847091U (en) | A kind of switched inductors type quasi-boost switching DC DC changer |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| 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: 20180427 |