CN206099346U - Harmonic restraint system with multistage active power filter - Google Patents
Harmonic restraint system with multistage active power filter Download PDFInfo
- Publication number
- CN206099346U CN206099346U CN201620535476.XU CN201620535476U CN206099346U CN 206099346 U CN206099346 U CN 206099346U CN 201620535476 U CN201620535476 U CN 201620535476U CN 206099346 U CN206099346 U CN 206099346U
- Authority
- CN
- China
- Prior art keywords
- active power
- power filter
- apf
- current
- operational amplifier
- 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.)
- Active
Links
Classifications
-
- 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
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/20—Active power filtering [APF]
Abstract
The utility model relates to a harmonic restraint system with multistage active power filter, multistage active power filter is parallelly connected each other, they pass through the load current that an air core coil sensor detected the non - linear load in the electric wire netting, arbitrary one -level active power filter all draws one or more from this load current and predetermines the inhibit signal value, thereby the common production of the multistage active power filter offset current opposite with predetermineeing the big or small looks equiphase of inhibit signal value pours into the electric wire netting into, non - linear load's harmonic current offsets, make the mains side electric current more be close sinusoidal wave, thereby improve the electric energy quality.
Description
Technical field
The utility model relate generally to eliminate nonlinear load harmonic electric device, exactly, be employ it is multistage
The power electronic equipment of the type such as Active Power Filter-APF or static reacance generator SVG, in the filter of any one-level active electric power
Ripple device can ensure the normal operation of remaining Active Power Filter-APF when individually being overhauled or being stopped transport.
Background technology
With the fast development of Power Electronic Technique, the various household electrical appliance for having different loads characteristic are entered on a large scale
Our life, associated therewith, some nonlinear loads such as inverter, rectifier and various Switching Power Supplies are obtained extensively
Application, harm of the resulting harmonic wave to power supply grid is also on the rise.To electrical network during power electronic devices switch motion
Substantial amounts of harmonic wave is filled with, expected standard sinusoidal current and voltage waveform serious distortion in electrical network is made.It is various due to existing
The domestic electric appliance such as the equipment to quality of power supply rdativery sensitive, such as computer equipment and air-conditioning, refrigerator, TV makes in a large number
With, the requirement to the quality of power supply also more and more higher.All kinds of power failures caused by harmonic wave and Frequent Accidents, either to production
Life or national economic development all generate very big negative effect.So the research and improvement to harmonic wave progressively starts to cause
The extensive concern of people, management, analysis and the improvement of harmonic wave have been swung to highly important status.Harmonic problem includes harmonic wave point
The aspects such as analysis, the suppression of harmonic detecting harmonic, effectively suppress harmonic wave to have become and ensure power grid security, necessity of high-quality operation
One of measure.Solving harmonic wave main path substantially has two kinds：One is that power electronic equipment itself is improved；Two is to electrical network
Carry out harmonic compensation.The application main direction of studying is exactly to carry out harmonic compensation to electrical network.
In preferable clean electric power system, electric current and voltage are all sine waves.Containing only resistance, inductance and electric capacity etc.
In the ball bearing made of linear element, the electric current for flowing through is directly proportional to the voltage for applying, and the electric current for flowing through is sine wave.Use Fourier
Analysis can resolve into essential part and its multiple non-sinusoidal signal.The basic reason that harmonic wave is produced is due to non-thread
Property load institute caused by.When electric current flows through load, non-linear relation is presented with added voltage, forming non-sinusoidal current has
Harmonic wave is produced.Switching manipulation and diode, the nonlinear characteristic of semiconductor thyristor due to semiconductor thyristor, power system
Some equipment such as power converter may producing ratio it is larger away from sinusoidal waveform.Under supply network impedance this
The non-sinusoidal cuve electric current of sample causes the voltage drop of a non-sinusoidal cuve.Shaking for harmonic voltage is produced under supply network impedance
Width is equal to the product of corresponding harmonic current and the supply network impedance Z corresponding to the power frequency.Having where harmonic source just has
Harmonic wave.It is also feasible that harmonic component reaches user by supply network.For example in supply network the operating of a user producer can
Can be disturbed by the harmonic wave that another adjacent user equipment is produced.All of nonlinear load can produce harmonic current, produce
The exemplary apparatus of raw harmonic wave have：Power supply (SMPS), electronics ballast of fluorescent lamp, speed-regulating actuator under switching mode, not between
Power-off source (UPS), magnetive cord equipment and some household electrical appliance such as television set etc..
The improvement of harmonic wave mainly has two approach：One is actively to administer, i.e., from harmonic source, harmonic source is not produced
Raw harmonic wave reduces the harmonic wave that harmonic source is produced, and this is only applicable to the power electronic equipment as major harmonic source, such as active work(
Rate factor correcting technology and PWM commutation techniques；Two is passive improvement, that is, arrange harmonic compensation device, offsets harmonic source injection electricity
The harmonic wave of net, such as various passive, active filters, this is all suitable for various harmonic sources.
Traditional compensation harmonic and idle device are LC passive power filters in power system, but due to structural principle
Upper the reason for, LC passive power filters have filtering compensation characteristic and depend on electrical network and load parameter, the drift of LC parameters
The change of filtering characteristic can be caused, with negative Voltage Cortrol effect, weight is big, the big and easy homologous ray of volume occurs resonance
Shortcoming.Because passive electric filter has the shortcoming and defect part of many, in order to solve these problems, people start
To active power filtering technology study.Active Power Filter-APF is the electric power electricity of a kind of dynamic harmonic wave and compensating reactive power
Sub-device, harmonic wave and the idle shortcoming for compensating, can making up passive filter that it can all change to frequency and size, obtains
Compensation characteristic more more preferable than passive filter is obtained, is a kind of preferable harmonic compensation device.
Utility model content
Disclosed in the utility model in one embodiment, there is provided a kind of harmonic wave with multistage Active Power Filter-APF
Suppression system, multistage Active Power Filter-APF is with electricity individually from the same electrical network of same air core coil sensor detection
The mode of stream information is arranged in parallel, and any one-level Active Power Filter-APF extracts default suppression signal from current information, from
And multistage Active Power Filter-APF produces the compensation electric current injection electrical network contrary with default suppression signal magnitude equal phase jointly.
The above-mentioned harmonics restraint system with multistage Active Power Filter-APF, the current information is non-linear in electrical network
The load current information of load or the magnitude of current information of mains side.
The above-mentioned harmonics restraint system with multistage Active Power Filter-APF, sets a total of N levels active power filtering
Device is in parallel, and N is the natural number more than zero, capture per one-level Active Power Filter-APF it is default suppress signal magnitude value N/
One gives as command signal after reversed polarity, and produces the single-stage compensation electric current I of the real-time tracking command signalC, wherein single-stage
Compensation electric current ICBut opposite in phase identical with N/mono- size for suppressing signal magnitude value, so as to the conjunction of N levels Active Power Filter-APF
Total compensation electric current of meter injection electrical network is N × IC。
The above-mentioned harmonics restraint system with multistage Active Power Filter-APF, the default suppression signal is mains side electricity
The harmonic component in harmonic component or load current information in flow.
The above-mentioned harmonics restraint system with multistage Active Power Filter-APF, the air core coil sensor include annular around
Group coil, the center that tested electric current passes through the Circular Winding coil along axis.
The above-mentioned harmonics restraint system with multistage Active Power Filter-APF, the air core coil sensor includes one
For the amplifying circuit for being amplified the induced voltage of Circular Winding coil.
The above-mentioned harmonics restraint system with multistage Active Power Filter-APF, includes per one-level Active Power Filter-APF
The receiving circuit that the imitated output quantity of the amplifying circuit is received in the way of analog signal, and produce for characterizing this
The voltage signal of current information.
The above-mentioned harmonics restraint system with multistage Active Power Filter-APF, the amplifying circuit includes first, second
Operational amplifier, to be respectively coupled to the respective positive of first, second operational amplifier defeated for the two ends correspondence of the Circular Winding coil
Enter end；First resistor is connected between the respective inverting input of first, second operational amplifier, and is put in the first computing
It is connected with second resistance between the inverting input and output end of big device, and in the inverting input of the second operational amplifier and defeated
Go out between end and be connected with second resistance, thereby form the sensing between the respective output end of first, second operational amplifier
The differential amplification signal of voltage.
The above-mentioned harmonics restraint system with multistage Active Power Filter-APF, the amplifying circuit also includes one group or many
3rd resistor and switching device that group is serially connected, the 3rd resistor and switching device of each group of series connection are both connected to first,
Between the respective inverting input of two operational amplifiers；When needing to increase the multiplication factor of the amplifying circuit, connect one or
Multiple switch device by one or more 3rd resistors and first resistor giving parallel connection；Or need to reduce the amplification electricity
During the multiplication factor on road, disconnect one or more switching devices with by one or more and first resistor 3rd resistors in parallel from
It is floating in the amplifying circuit.
The above-mentioned harmonics restraint system with multistage Active Power Filter-APF, the receiving circuit is put including the 3rd computing
Big device, the differential amplification signal of the amplifying circuit output is coupled to the positive of the 3rd operational amplifier and anti-phase by resistance
Input, and feedback resistance, therefore the 3rd computing are connected between the inverting input and output end of the 3rd operational amplifier
The differential amplification signal is switched to single-ended voltage signal by amplifier.
The above-mentioned harmonics restraint system with multistage Active Power Filter-APF, receiving circuit also includes that front stage realizes electricity
Air bound from optical coupler module and four-operational amplifier；Optical coupler module output follows the single-ended voltage signal linear change
Linear current, four-operational amplifier positive input end grounding and inverting input and outlet chamber at it are connected with resistance, by
The linear current is converted into four-operational amplifier the voltage letter linear with the single-ended voltage signal of its output end
Number.
The above-mentioned harmonics restraint system with multistage Active Power Filter-APF, multistage Active Power Filter-APF APF1～
Each APF in APFN is produced as alone ICSingle-stage compensation electric current, final multi-stage power wave filter APF1～APFN is common
Produce and default suppression signal value IFILTERCompensation electric current (N × I equal in magnitude, opposite in phaseC) injection electrical network, offset non-thread
Property load harmonic current component, make mains side electric current closer to sine wave to improve the quality of power supply.Described air core coil is passed
The induced voltage that annular winding coil is produced in sensor is the light current rather than forceful electric power for not jeopardizing personal safety, and by amplifying electricity
It is also light current that road and integrating circuit generation characterize the voltage signal of load current value size, and when any one-level active electric power
Wave filter will not produce negative electric arc when separation is unloaded from electrical network, and the coil of air core coil sensor is imitated without magnetic hysteresis
Should, also without phase error and magnetic saturation phenomenon, the frequency bandwidth of its response is wider, can almost detect the various high frequencies in harmonic wave
Composition.Compared with the Current Voltage sensor with ferrimagnet, the measurement range of air core coil or title Luo-coil is wider
And precision is higher, more meet safety and environmental requirement.
Description of the drawings
After reading described further below and reference the following drawings, feature of the present utility model and advantage will be evident that：
Fig. 1 is that compensation electric current injection electrical network is produced after Active Power Filter-APF detection nonlinear load electric current.
Fig. 2 is to inject electrical network after multistage Active Power Filter-APF series connection generation compensation electric current.
Fig. 3 is a kind of induction type air core coil sensor for detecting nonlinear load electric current.
Fig. 4 is the amplifier and integrator used cooperatively with air core coil sensor.
Fig. 5 is that multistage Active Power Filter-APF in parallel generation inject electrical network after compensation electric current.
Fig. 6 is the schematic diagram that the response band of air core coil sensor has larger width.
Fig. 7 is the receiving circuit of the amplifying circuit transmission analog signalses to APF of air core coil sensor.
Fig. 8 is a kind of alternative of differential type amplifying circuit.
Fig. 9 is that differential amplification signal turns single-ended circuit structure by both-end.
Figure 10 is another kind of closed loop detection method relative with the open loop type detection method of Fig. 5.
Specific embodiment
Referring to Fig. 1, Active Power Filter-APF APF mainly includes two large divisions：Instruction current computing module 102 and compensation
Current occuring circuit, wherein compensation current occuring circuit is subdivided at least including current follow-up control module 103 and drives electric
Road 104 and main circuit 105.Active Power Filter-APF can be generally divided into single-phase and two kinds of three-phase, and three-phase system is divided into three again
Three-phase three-wire system and three-phase four-wire system, the application is temporarily spiritual to illustrate present invention using phase three-wire three as example hereinafter.
Fig. 1 illustrates three-phase ac power supply ESAAnd ESBAnd ESC, power supply is transmitted to load 110 by electrical network, load 110 is usually non-thread
Property load be also harmonic source and target compensation.
Referring to Fig. 1, breaker in middle group S1 of main circuit 105～S2 and switches set S3～S4 and switches set S5～S6 this three groups of switches
It is parallel with one another, in addition any one single switches set S1～S2 or S3～S4 or S5～S6 also respectively with a DC voltage UDC
It is in parallel.Switching tube can be IGBT or MOSFET or BJT or GTO IGCTs etc..Between first group of two switch S1～S2
Tie point a and provide power supply ESAA phase grid branch between be connected with inductance L, inject is to the compensation electric current of the electrical network
ICA.Tie point b and offer E between second group of two switch S3～S4SBA phase grid branch between be connected with inductance L,
It is I to inject to the compensation electric current of the electrical networkCB.And the tie point c between two of the 3rd group switch S5～S6 and provide ESC's
Inductance L is connected between one phase grid branch, it is I to inject to the compensation electric current of the electrical networkCC.It should be noted that in the application
In the main circuit 105 of Fig. 1, the factors such as the component type/quantity/concrete annexation of S1～S6 are switched as just this Shen of explaination
Please spirit an example, actually any main circuit/switching tube topology that can realize identical function is applied to this reality
With new and it can be replaced, so this is not intended that main circuit of the present utility model shall be limited only to the specific topological class
Type.
Referring to Fig. 1, compensation electric current is substantially by DC capacitor voltage UDCWith the supply voltage difference effect for exchanging survey
The inductance L that surveys in exchange is upper produced, DC capacitor voltage UDCCan be dc source can also be storage capacitor provide
DC voltage, when main circuit 105 produce compensation electric current be to use as inverter, if the energy storage such as electric capacity to DC side is first
Then as rectifier when part charges.The operation of main circuit 105 is connection and the pass of switches set S1～S2 or S3～S4 or S5～S6
Disconnected decision, typically always there is a switch to be to be on shape in each switches set (S1～S2 or S3～S4 or S5～S6)
State, and while another switch is then off state.
Referring to Fig. 1, assume that three phase mains sum meets E in advanceSA+ESB+ESC=0, according to Circuit theory, compensate to three-phase
The respective compensation electric current sum of electrical network bus meets ICA+ICB+ICC=0, it is assumed that Ka and Kb and Kc are set in advance according on off state
Fixed switching coefficient, under the situation of preferable and rough calculation, compensates the differential equation and alternating current of electric current and time t in each phase
Also there is following functional relation between source：
For convenience of discussion, hereinafter we temporarily take phase grid branch E thereinSAAs research object, other
Remaining a few phase grid branch ESB～ESCOperation principles it is also substantially similar.Referring to Fig. 1, the groundwork of Active Power Filter-APF
Mechanism is, in load end by Hall current sensor 101 to load current ILDetected, and by load current ILInformation transfer
To Active Power Filter-APF.Such as harmonic and reactive currents during instruction current computing module 102 is detected by target compensation divide
The information such as amount, it is assumed that load current ILHarmonic component I in informationLHIt is detected, thereafter instruction current computing module 102 is again
By harmonic component ILHAs command signal I of a compensation electric current after reversed polarity* CA.Current follow-up control module 103 receive from
Command signal I of instruction current computing module 102* CAAfterwards, produce pulse width modulating signal PWM and be transferred to drive circuit 104,
Each switches set (S1～S2 or S3～S4 in further come the drive circuit 104 for making driving force higher to drive main circuit 105
Or S5～S6) on off state, it is therefore an objective to so that main circuit 105 produces real-time accurate tracking command signal I* CACompensation electric current
ICA.If compensation electric current ICAWith load current ILHarmonic component ILHBut polarity equal in magnitude/in opposite direction, then both phases
Mutually offset, make power supply ESAThe source current I of offerSAIn sinusoidal fundamental wave current component containing only intimate standard, be finally reached suppression
The purpose of harmonic wave in source current.
Connecting node a between first group of two switch S1～S2 is described above and power supply E is providedSAA phase electrical network
Inductance L is connected between branch road, it is I to inject to the compensation electric current of the electrical network by inductance L from node aCA, now with main circuit
105 a nodes to provide power supply ESAA phase electrical network produce compensation electric current ICACome the compensation machine of Active Power Filter-APF of demonstrating
System.In the normal operation stage of Active Power Filter-APF APF, the compensation electric current I of the output of main circuit 105CAIn command signal I* CAValue
Fluctuate, zigzag can be generally presented to follow command signal I* CAThe change of value.
Wherein formula (4) is the deformation of formula (1), it is desirable to compensate electric current ICACommand signal I of accurate tracking in real time* CA, then once mending
Repay electric current ICAGeneration is any than compensation electric current ICADeviation when, should select to turn on and off the switch S1 in main circuit 105
～S2 is reducing this deviation, and formula breaker in middle COEFFICIENT K a can generally take -1/3 or -2/3.As compensation electric current ICAIt is less than
Command signal I* CA, indicate compensation electric current ICAShould increase to make great efforts near command signal I* CA, this up-to-date style (4) equation left side should
When more than 0, namely the upper switching tube S1 switched in S1～S2 bridge arms is meaned to turn off and lower switching tube S2 is connected.Work as compensation
Electric current ICAMore than command signal I* CA, indicate compensation electric current ICAShould reduce and come near command signal I* CA, this up-to-date style (4) etc.
The formula left side should be less than 0, it is meant that the upper switching tube S1 in switch S1～S2 bridge arms should be connected and lower switching tube S2 is turned off.
Realize below scheme：Current follow-up control module 103 receives command signal I from instruction current computing module 102* CAAfterwards,
Command signal I that will be received* CAWith the actual compensation electric current I for capturingCAIt is compared, produces pulse-width signal PWM and be transferred to drive
Dynamic circuit 104, each switches set (S1～S2 in further allowing the higher drive circuit 104 of driving force to drive main circuit 105
Or S3～S4 or S5～S6) on off state, make compensation electric current ICACommand signal I of accurate tracking in real time* CA。
It is above with compensation harmonic component ILHMode explaining the operation of whole system, one it is optional but it is non-must
In the embodiment of palpus, if we require that Active Power Filter-APF is further compensate for the nothing for loading while compensation harmonic, also
Work(power, as long as then in compensation electric current ICACommand signal I* CAMiddle increase and the fundamental reactive component I for loadingLQReversed polarity into
Point.Now load current ILHarmonic component I in informationLHWith idle component ILQIt is detected, instruction current computing mould
Block 102 is again by harmonic component ILHWith idle component ILQMerge after reversed polarity as command signal I of a compensation electric current* CA, mend
Repay electric current ICA=-(ILH+ILQ).So as to compensate electric current I in whole electrical networkCAWith load current ILIn harmonic wave ILHAnd it is idle
ILQComposition is offseted, source current ISAThe eventually equal to fundamental active component of load current.
In another alternative embodiment, Active Power Filter-APF can a compensating power, now compensate electric current ICA
Command signal I* CAShould be with load current ILInstantaneous reactive component I in informationL-QBut the identical opposite polarity of size, namely
Meet compensation electric current ICA=-IL-Q, the source current I after compensationSAThe eventually equal to real component of load current.
In another alternative embodiment, it is contemplated that load current there may be negative sequence component in three-phase unbalance system,
When Active Power Filter-APF not only compensating power but also compensation harmonic electric current are also further compensate for negative-sequence current, electric current I is compensatedCA
Command signal I* CAShould be with load current ILInstantaneous reactive component I in informationL-Q, harmonic component ILH, negative sequence active component
IL-P, negative phase-sequence idle component IL-QSize is identical but opposite polarity, compensates electric current ICA=-(IL-Q+ILH+IL-P+IL-Q).After compensation
Source current ISAThe eventually equal to positive sequence real component of load current.
It is that Fig. 1 is that single-stage Active Power Filter-APF APF provides compensation for electrical network referring to slightly distinguishing in Fig. 2, with Fig. 1
Electric current, and be to adopt multistage Active Power Filter-APF APF that compensation electric current is provided for electrical network in Fig. 2.Still therein one is taken mutually electric
Net branch road ESAAs research and explaination object, other remaining a few phase grid branch ESB～ESCOperation principles it is also substantially similar.
It is that single-stage Active Power Filter-APF provides compensation electric current I for the phase electrical network in Fig. 1CA, it is in fig. 2 multistage active power filtering
Device APF1, APF2 ... APFN (N is natural number) correspondences are respectively the phase electrical network and provide compensation electric current IC1、IC2、……ICN
(N is natural number), the Active Power Filter-APF APFN of any one-level can inject corresponding compensation electric current I in the electrical networkCN,
Finally, it is I that we can calculate total total compensation electric current being infused in the phase electrical networkC1+IC2+……+ICN.If many in Fig. 2
Level Active Power Filter-APF is identical with the compensation effect of single-stage Active Power Filter-APF in Fig. 1, then ICA=IC1+IC2+……+ICN,
It is multistage replace single-stage mode can reduce single-stage Active Power Filter-APF computing pressure and greatly improve compensation precision with
Effect.
Referring to Fig. 2, first order Active Power Filter-APF APF1 is at least reserved with two port IO-1 and IO-2 to capture electricity
The sensing electric current of flow sensor 101, the rest may be inferred, and N level Active Power Filter-APFs APFN is also at least reserved with two port IO-1
And IO-2, wherein first order APF1 and second level APF2 ... N levels APFN is mode in parallel on electrical connection.This
It is embodied in, the electric current transmission line 101a of current sensor 101 is connected to the port IO-1 of first order APF1 at its X1 nodes,
Then electric current transmission line 101a is returned again from the port IO-2 of first order APF1 and is connected at the Y1 nodes of electric current transmission line 101a.According to
This analogizes, and the electric current transmission line 101a of current sensor 101 is connected to the port IO-1 of N levels APFN at its XN nodes,
Then electric current transmission line 101a is returned again from the port IO-2 of N levels APFN and is connected at the YN nodes of electric current transmission line 101a.From
And all of first order APF1 and second level APF2 ... N levels APFN are all serially connected in into same electric current transmission line 101a
On.
In one alternate embodiment, the compensation electric current I that first order APF1 is providedC1The compensation electricity provided with second level APF2
Stream IC2... and the compensation electric current I that N levels APFN are providedCNIt is equal, IC1=IC2=IC3=... ICN, now any one-level have
Active power filter APFN is captured to load current I from electric current transmission line 101aLIn default suppression signal value IFILTERAfterwards,
Command signal I of APFN itself* CA-NThe I that should be equal toFILTER÷ N (but opposite in phase).Equivalent to the single-stage that APF at different levels are provided
Compensation electric current IC1=IC2=IC3……ICN=-IFILTER/ N, so total total compensation electric current meets ICA=IC1+IC2+……+
ICN=-IFILTER.It is default to suppress signal value IFILTERIt is the component for needing to be filtered out in load current, can is above humorous
Wave component ILH, or harmonic component ILHWith idle component ILQ, can also be instantaneous reactive component IL-Q, or simultaneous with wink
When idle component IL-Q, harmonic component ILH, negative sequence active component IL-PWith negative phase-sequence idle component IL-Q, note IFILTERWith these components
Size is identical but opposite polarity.
Referring to Fig. 2, first order APF1 and second level APF2 ... N levels APFN are all concatenated, although can reduce single-stage
The computing pressure of Active Power Filter-APF, but also have drawback, such as first order APF1 runs into damage or needs maintenance burst feelings
During condition, wave filter APFN needs to be separated from electric current transmission line 101a, now in order to avoid each APF2 ... of rear class
APFN still normal works, under the premise of this of power-off net is unable to, can only will be connected to the first order on electric current transmission line 101a
Nodes X 1 and Y1 on the IO-1/IO-2 ports of APF1 short circuit by force, such as using metal clips or wire in the way of physics
101b short circuits meet electric current transmission line 101a and not turning off just can be unlikely to and have influence on below between nodes X 1 and Y1
APF2……APFN.The rest may be inferred, when N levels APFN (N is natural number) disconnect from electrical network on its IO-1/IO-2 ports
Nodes X N and YN must short circuits by force.Although wave filter unloaded from electrical network can get off, any one wave filter from
The transient state disconnected on electrical network, all can jeopardize the dangerous electric arc of personal safety in the generation of its IO-1/IO-2 near ports, because this
Belong to the category of forceful electric power.
In order to make up the deficiency of Fig. 2, the application has been set forth below the embodiment of Fig. 3.
Referring to Fig. 3, air core coil sensor 121 is used for replacing the Hall current sensor 101 of Fig. 1～2, the air core coil
Sensor 121 is used for detecting load current ILThe various components of information, air core coil 121 is not in structure using similar Hall
The such magnetic core containing ferrimagnet of current sensor 101, coil 123 is wrapped in and plays the flexible or firm of physical support effect
Property skeleton 122 on constitute Circular Winding, skeleton 122 is not magnetic core so air core coil 121, without hysteresis effect, is also missed without phase place
Difference and magnetic saturation phenomenon, the frequency bandwidth of response is from 0.1HZ to several MHZ.The theoretical foundation of air core coil sensor 121 is farad
The law of electromagnetic induction and Ampere circuit law, the load current I of electrical networkLAlong axis by air core coil sensor 121
During 123 center of coil, the magnetic field of correspondence change can be produced in the volume range of the Circular Winding encirclement of coil 123, in coil 123
Two ends produce induced voltage U1T ()=M × (di/dt), it is micro- with the alternating current i changed with time t that need to be measured
Equation is divided to be directly proportional, M is the mutual inductance of coil windings.
Referring to Fig. 4, it is contemplated that the induced voltage U that the two ends of Fig. 3 coils 123 produce1T () signal is very faint, optional
In embodiment, can first by induced voltage U1T () is integrated again after amplifying.It must be stressed that the amplification for adopting in the diagram
Circuit 123 and the integrating circuit 124 for adopting are arbitrarily optional, in this application with specific amplifying circuit 123 and integration electricity
The framework of road 124 is intended merely to prove and explain present invention spirit, actually any other applicable amplifying circuit and product
Parallel circuit type can replace amplifying circuit 123 and integrating circuit 124 in figure, and such as La Zhawei is in the integrated electricity of analog cmos
Design the various amplifiers and integrator disclosed in a book in road.Propose in the scheme of follow-up Fig. 8～9 of the utility model than
Fig. 4 more preferably amplifying circuits or integrating circuit scheme.
Referring to Fig. 4, a resistance R2 is connected between the inverting input and output end of operational amplifier A M1, in institute
The induced voltage U of input1A resistance R1, operational amplifier are connected between the inverting input of (t) and operational amplifier A M1
The positive input end grounding of AM1, calculates operational amplifier A M1 output end voltage U2(t)=- U1(t)×(R2/R1).Exist in addition
In integrating circuit 124, the voltage U of integrating circuit 124 is inputed to2Connect between the inverting input of (t) and operational amplifier A M2
There is a resistance R3, between the inverting input and output end of operational amplifier A M2 electric capacity C, operational amplifier A M2 are connected with
Positive input end grounding, calculates operational amplifier A M2 output end voltage U3T () meets：
In the detection load current I of utilization air core coil sensor 121 described aboveLOn the basis of scheme, Fig. 5 is also showed that
Another preferred embodiment.Compared with Fig. 4 in Figure 5, first order APF1 and second level APF2 ... and N levels APFN be not
It is again series relationship, the substitute is parallel with one another.Arbitrarily the wave filter APFN of one-level is individually from air core coil sensor 121
Electric current transmission line 121a on detect load current ILThe various components of information.For example in an optional embodiment, first
The compensation electric current I that level APF1 is providedC1The compensation electric current I provided with second level APF2C2... and the benefit that N levels APFN are provided
Repay electric current ICNIt is equal, IC1=IC2=IC3=... ICN, now any one-level Active Power Filter-APF APFN is from electric current transmission line
Capture to load current I on 121aLIn default suppression signal value IFILTERAfterwards, any one-level APFN command signal of itself
I* CA-NThe I that should be equal toFILTER÷N.Equivalent to the compensation electric current I of offers at different levelsC1=IC2=IC3……ICN=-IFILTER/ N,
So ICA=IC1+IC2+……+ICN=-IFILTER, this remains able to reach expected compensation effect.
Referring to Fig. 5, one of advantage of air core coil sensor 121 is the voltage U that it is exported1(t)～U3T () belongs to
The category of light current, compares the forceful electric power phenomenon of the output of Hall current sensor 101 in Fig. 2 and is produced when unloading any one-level APF
Raw electric arc, air core coil sensor 121 meets more preferably safety effect, and air core coil is sometimes referred to as Luo-coil.
When air core coil sensor 121 provides load current information on voltage and/or electric current transmission line 121a, active power filtering
Device APFN can utilize the crystal connector that similar home phone line be connected with telephone set to achieve a butt joint air core coil sensor 121,
Namely the pressure short circuit mode that electric arc can be produced in Fig. 2 can be abandoned, when any one-level APF is unloaded from electrical network, due to parallel connection
It is related to that other remaining Active Power Filter-APFs will not receive any negative effect.
Referring to Fig. 6, it is assumed that load current ILIn carry the harmonic component curve 151 of intimate triangular wave, if with Fig. 2's
Hall current sensor 101 detects that the feedback of harmonic amount curve for finally being captured is actual as shown in 152 to harmonic component
Like that, it can be found that there is distortion between the harmonic feedback quantity curve 152 of harmonic component curve 151, the instruction electricity in Fig. 1 is caused
Command signal I that stream computing module 102 is produced* CAThere is larger error, finally cause current follow-up control module 103 to produce
Pwm signal be not inconsistent with desired value yet, compensate electric current ICAAlso can deterioration in accuracy therewith.This is because Hall current sensor 101
The reason narrow to the response band width for loading A.C. current.Fig. 6 is the feedback of harmonic that air core coil sensor 121 is detected
Amount curve 153, the primitive curve of the harmonious wave component 151 of high-frequency harmonic feedback quantity curve 153 is basically identical, hardly produces and appoints
What serious distortion, thus the pwm signal that produces of current follow-up control module 103 can with it is anticipated that as switching switch,
Compensation electric current ICAWith high-precision angle value.Hall current sensor 101 is except ensureing above as the triangle of curve 151 of example
Ripple is difficult to accurately be captured, and is equally also difficult to ensure that other similar high-frequency harmonics with spike composition are accurately examined
Measure, and the alternating current detection bandwidth of air core coil sensor 121 is wider, of this sort spike harmonic wave can be not damaging
The mode for losing precision is caught.
Referring to Fig. 7, dotted line left side be air core coil sensor part of module and dotted line right side be then active power filtering
The part of module of device.Air core coil sensor also at least includes the amplifying circuit 211 detected to current signal, based on this Shen
Spirit please, the multiplication factor of amplifying circuit 211 can be controlled using multiplication factor control module 212, be examined in addition
Considering the signal that air core coil sensor detected, can in time to pass to Active Power Filter-APF any unnecessary to avoid
Postpone, signal analog quantity that amplifying circuit 211 is detected (rather than 1/0 binary digit amount) is conveyed to active power filtering
Device, Active Power Filter-APF correspondence then realizes the reception of analog signal with a receiving circuit 311.
Referring to Fig. 8, amplifying circuit 211 includes the first operational amplifier A 1 and the second operational amplifier A 2, wherein annular around
Two ends DSA, DSB correspondence of group coil is respectively coupled to the normal phase input end V of the first operational amplifierIN1With the second operation amplifier
The normal phase input end V of device A2IN2.The DSA ends of Fig. 8 coils and normal phase input end VIN1Between be connected with resistance R21, and coil
DSB ends and normal phase input end VIN2Between be connected with resistance R22, while also in the normal phase input end of the first operational amplifier A 1
VIN1With the normal phase input end V of the second operational amplifier A 2IN2Between be connected with an electric capacity C21, when signal frequency is relatively low, electricity
Hold the capacitive reactance of C21 makes greatly the input impedance of differential amplifier circuit very high very much.Referring to Fig. 8, in the anti-phase of the first operational amplifier A 1
First resistor R25 is connected between input (node N1) and the inverting input (node N2) of the second operational amplifier A 2, with
And in the inverting input and its output end V of the first operational amplifier A 1OUT1Between be connected with second resistance R23, and
The inverting input and its output end V of two operational amplifier As 2OUT2Between be connected with the electricity of second resistance R24, R23 and R24
Resistance size can be with identical, but the resistance of they and R25 can be the same or different.More rough calculating, output end
VOUT1～VOUT2Between differential voltage VOUT2- VOUT1Essentially equal to (VIN2- VIN1) × (1+2 × R23/R25), wherein
VIN2- VIN1Equal to the induced electricity pressure reduction of Circular Winding coil two ends DSA, DSB, so as to we can realize being put in the first computing
Big device and respective output ends V of second 1～A2 of operational amplifier AOUT1～VOUT2Between, capture to Circular Winding described above
The differential amplification signal of the induced voltage that coil two ends DSA～DSB is sensed.
Referring to Fig. 8, it is known that the inverting input of node N1 and the first operational amplifier A 1 is connected, node N2 and the second computing
The inverting input of amplifier A2 is connected, and first resistor R25 above is connected between node N1 and N2.It is observed that amplifying
Circuit 211 also includes one or more groups of 3rd resistors R26 being serially connected and switching device S26, and the of each group of series connection
Three resistance R26 and switching device S26 are both connected between the respective inverting inputs of first, second 1～A2 of operational amplifier A
(i.e. between node N1～N2), it is therefore intended that, it is intended that the entire gain of amplifying circuit 211 claims multiplication factor to be adjustable
's.Between node N1～N2 in addition to first resistor R25 that script is present, when each group of 3rd resistor R26 being serially connected
With 3rd resistor R26 and first resistor R25 that when S26 is connected in switching device S26, just allow in the middle of the group be connected in parallel on node N1～
Between N2.So 3rd resistor R26 (S26 connections) of the effective status introduced between node N1～N2 is more, node N1～
The total resistance of parallel connection between N2 is less, and vice versa, 3rd resistor R26 (S26 disconnections) cast out between node N1～N2
More, the total resistance of parallel connection between node N1～N2 is bigger.Turning on and off for S26 of switch can be by the multiplication factor in Fig. 7
The low and high level of the output of control module 212 carrys out the control end of controlling switch S26 and switches over.When need increase amplifying circuit 211
Multiplication factor when, connect one or more switching devices S26 with by one or more 3rd resistors R26 and first resistor
R25 gives parallel connection.Or when needing to reduce the multiplication factor of amplifying circuit 211, disconnect one or more switching devices S26 to incite somebody to action
One or more and first resistor R25 3rd resistors R26 floating from amplifying circuit (floating) in parallel, now floating shape
3rd resistor R26 of state is that high-impedance state can not consider the resistance in parallel impact that it is caused between N1～N2 nodes.
Referring to Fig. 9, the receiving circuit 311 in active filter APF includes the 3rd operational amplifier A 3, and electricity is amplified in Fig. 7
Differential amplification signal (the V of the output of road 211OUT2- VOUT1) it is coupled to the positive and inverting input of the 3rd operational amplifier A 3.
Output end V of such as the second operational amplifier A 2 in Fig. 8OUT2The positive of three operational amplifier As 3 is coupled to by resistance R32
Input VINB, output end V of the first operational amplifier A 1 in Fig. 8OUT13rd operational amplifier is coupled to by resistance R31
The inverting input V of A3INA, and it is connected with feedback resistance between the inverting input and output end of the 3rd operational amplifier A 3
R33, therefore the differential amplification signal is switched to single-ended signal by the 3rd operational amplifier A 3.3rd operational amplifier of active APF
The difference information that A3 is received is High Speed Analog amount, and here the resistance and R32 of resistance R31 can be with identical or different, differential voltage
VOUT2- VOUT1The single-ended voltage signal of the 3rd operational amplifier A 3 is converted into, equal to (VINB- VINA) × R33/R31 or
(VOUT2- VOUT1)×R33/R31.As other alternative embodiments, a reference voltage VREF can also be passed through an electricity
Resistance is input to the normal phase input end V of the 3rd operational amplifier A 3INBTo make difference value VOUT2- VOUT1Slightly upward lifting.
Referring to Fig. 9, receiving circuit 311 also includes the optocoupler that front stage circuits and late-class circuit can be caused to realize electrical isolation
Matched moulds block 345, equivalent light emitting diode and sensitive device (such as photosensitive semiconductor pipe) cooperate to carry in optical coupler module 345
For output current, optical coupler module 345 completes the conversion of electric signal-optical signal-electric signal, so as to play input signal and defeated
Go out the buffer action of signal.Due to being mutually isolated between the input and output of optical coupler module 345, electric signal transmission has the spies such as one-way
Point, thus with good electrical isolation capabilities and antijamming capability.So optical coupler module 345 in transmission information as terminal
Isolation element can greatly improve signal to noise ratio.Consider between APF at different levels it is the relation being mutually in parallel in the utility model, optocoupler
Matched moulds block 345 can effectively shield respective detection branch between different APF and the signal of other detection branch is disturbed, and same
Three-phase current signal detection branch interferences different in one-level wave filter APF are also shielded.Light in this application
Coupling module 345 receives the single-ended voltage signal of the output of the 3rd operational amplifier A 3, and generation is exported with operational amplifier A 3
Single-ended voltage signal remain the linear current I of linear relationshipFOLLOW.So optical coupler module 345 acts at least two,
First electrical isolation for being to realize front stage, second is then to form the single ended voltage letter that followed by the output of operational amplifier A 3
Number change and the linear current of linear change.Receiving circuit 311 also includes four-operational amplifier A4, four-operational amplifier A4
By linear current IFOLLOWConversion is reduced into final desired magnitude of voltage.The current output terminal of optical coupler module 345 is coupled to
A node N3 being connected with the inverting input of four-operational amplifier A4, we are also in the positive of four-operational amplifier A4
Input end grounding and it is connected with resistance R45 in its inverting input and outlet chamber, although be not expressly shown in figure, resistance
R45 can be arranged to adjustable resistance or direct and its one adjustable resistance of series connection.Four-operational amplifier A4 passes through resistance R45
The linear current I that will be absorbed in node N3FOLLOWIt is converted into the voltage signal V that it is exportedOUT-A.Due to linear current IFOLLOW
Linear relationship is kept with the single-ended voltage signal of the output of the 3rd operational amplifier A 3, then the voltage of four-operational amplifier A4 outputs
Signal VOUT-AAlso linear relationship is kept with the single-ended voltage signal of the output of the 3rd operational amplifier A 3.In four-operational amplifier A4
Inverting input and outlet chamber be connected with compensating electric capacity C42, it is in parallel with resistance R45, compensating electric capacity C42 be used for improve circuit
The bandwidth of operation of stability and reduction circuit output noise and limiting circuit is in 10kHz or so.
Referring to Figure 10, this is mainly different from the open loop type detection method of Fig. 5, in Figure 5, multistage Active Power Filter-APF with
The load current I of nonlinear load in same electrical network is individually detected from same air core coil sensor 121LIn electric current
The mode of information and be arranged in parallel, in open loop type detection method, the position of air core coil sensor 121 is generally close to non-linear
Load.But in the closed loop detection method of Figure 10, the position of air core coil sensor 121 is but proximate to AC power ES, also
It is to say, air core coil sensor 121 to Active Power Filter-APF, now there is the magnitude of current information transfer of the mains side for detecting
After active power filter is according to the harmonic component in the magnitude of current for capturing mains side, directly produce compensation electric current to filter electricity
The harmonic wave of source.
In the utility model, multistage Active Power Filter-APF is with individually from the detection of same air core coil sensor
The mode of the load current information of the nonlinear load in same electrical network is arranged in parallel, so any one-level APF is unloaded from electrical network
To get off do not affect other remaining Active Power Filter-APFs normally from air core coil sensor capture load current information, this with
Multistage Active Power Filter-APF is serially connected the mode to detect load current and is essentially different.
More than, by explanation and accompanying drawing, give the exemplary embodiments of the ad hoc structure of specific embodiment, above-mentioned practicality
It is new to propose existing preferred embodiment, but these contents are not intended as limitation.For a person skilled in the art, read
After reading described above, various changes and modifications undoubtedly will be evident that.Therefore, appending claims should be regarded as and cover originally
The true intention of utility model and whole variations and modifications of scope.Any and all model of equal value in Claims scope
Enclose and content, be all considered as still belonging in intention of the present utility model and scope.
Claims (11)
1. a kind of harmonics restraint system with multistage Active Power Filter-APF, it is characterised in that multistage Active Power Filter-APF
It is arranged in parallel in the way of the current information for individually detecting in same electrical network from same air core coil sensor, it is any one
Level Active Power Filter-APF extracts default suppression signal from current information, so as to multistage Active Power Filter-APF is produced jointly
The compensation electric current injection electrical network contrary with default suppression signal magnitude equal phase.
2. the harmonics restraint system with multistage Active Power Filter-APF according to claim 1, it is characterised in that described
Current information is the load current information or the magnitude of current information of mains side of nonlinear load in electrical network.
3. the harmonics restraint system with multistage Active Power Filter-APF according to claim 1, it is characterised in that setting
A total of N levels Active Power Filter-APF is in parallel, and N is the natural number more than zero, captures per one-level Active Power Filter-APF default
N/mono- for suppressing signal magnitude value gives as command signal after reversed polarity, and produces the list of the real-time tracking command signal
Level compensation electric current IC, wherein single-stage compensation electric current ICBut opposite in phase identical with N/mono- size for suppressing signal magnitude value, from
And it is N × I that N level Active Power Filter-APFs add up to total compensation electric current of injection electrical networkC。
4. the harmonics restraint system with multistage Active Power Filter-APF according to claim 2, it is characterised in that described
It is default to suppress signal to be the harmonic component in harmonic component or load current information in power supply lateral current magnitude.
5. the harmonics restraint system with multistage Active Power Filter-APF according to claim 1, it is characterised in that the sky
Wire-core coil sensor includes Circular Winding coil, the center that tested electric current passes through the Circular Winding coil along axis.
6. the harmonics restraint system with multistage Active Power Filter-APF according to claim 5, it is characterised in that described
Air core coil sensor includes an amplifying circuit for being used to be amplified the induced voltage of Circular Winding coil.
7. the harmonics restraint system with multistage Active Power Filter-APF according to claim 6, it is characterised in that each
Level Active Power Filter-APF is included connecing that the imitated output quantity of the amplifying circuit is received in the way of analog signal
Circuit is received, and produces the voltage signal for characterizing the current information.
8. the harmonics restraint system with multistage Active Power Filter-APF according to claim 6, it is characterised in that described
Amplifying circuit includes first, second operational amplifier, and the two ends correspondence of the Circular Winding coil is respectively coupled to first, second fortune
Calculate the respective normal phase input end of amplifier；
First resistor is connected between the respective inverting input of first, second operational amplifier, and is put in the first computing
It is connected with second resistance between the inverting input and output end of big device, and in the inverting input of the second operational amplifier and defeated
Go out between end and be connected with second resistance, thereby form the sensing between the respective output end of first, second operational amplifier
The differential amplification signal of voltage.
9. the harmonics restraint system with multistage Active Power Filter-APF according to claim 8, it is characterised in that described
Amplifying circuit also includes one or more groups of 3rd resistors being serially connected and switching device, the 3rd resistor of each group of series connection and opens
Close device to be both connected between the respective inverting input of first, second operational amplifier；
When needing to increase the multiplication factor of the amplifying circuit, connect one or more switching devices with by one or more this
Three resistance and first resistor give parallel connection；Or
When needing to reduce the multiplication factor of the amplifying circuit, one or more switching devices are disconnected with by one or more and the
The 3rd resistor of one resistor coupled in parallel is floating from the amplifying circuit.
10. the harmonics restraint system with multistage Active Power Filter-APF according to claim 7, it is characterised in that institute
Receiving circuit is stated including the 3rd operational amplifier, the differential amplification signal of the amplifying circuit output by resistance be coupled to this
The positive and inverting input of three operational amplifiers, and connect between the inverting input and output end of the 3rd operational amplifier
There is feedback resistance, therefore the differential amplification signal is switched to single-ended voltage signal by the 3rd operational amplifier.
The 11. harmonics restraint systems with multistage Active Power Filter-APF according to claim 10, it is characterised in that institute
Stating receiving circuit also includes being capable of achieving the optical coupler module and four-operational amplifier of electrical isolation；
The optical coupler module output follows the linear current of the single-ended voltage signal linear change, and four-operational amplifier positive is defeated
Enter end ground connection and be connected with resistance in its inverting input and outlet chamber, changed the linear current by four-operational amplifier
Into the voltage signal linear with the single-ended voltage signal of its output end.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201620535476.XU CN206099346U (en) | 2016-06-03 | 2016-06-03 | Harmonic restraint system with multistage active power filter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201620535476.XU CN206099346U (en) | 2016-06-03 | 2016-06-03 | Harmonic restraint system with multistage active power filter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN206099346U true CN206099346U (en) | 2017-04-12 |
Family
ID=58471748
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201620535476.XU Active CN206099346U (en) | 2016-06-03 | 2016-06-03 | Harmonic restraint system with multistage active power filter |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN206099346U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105932677A (en) * | 2016-06-03 | 2016-09-07 | 丰郅(上海)新能源科技有限公司 | Harmonic suppression system with multi-level active power filter |
| CN113990625A (en) * | 2021-11-03 | 2022-01-28 | 浙江飞旋科技有限公司 | High-frequency large-capacity power electronic unit parallel device and carrier multiplexing method |
-
2016
- 2016-06-03 CN CN201620535476.XU patent/CN206099346U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105932677A (en) * | 2016-06-03 | 2016-09-07 | 丰郅(上海)新能源科技有限公司 | Harmonic suppression system with multi-level active power filter |
| CN113990625A (en) * | 2021-11-03 | 2022-01-28 | 浙江飞旋科技有限公司 | High-frequency large-capacity power electronic unit parallel device and carrier multiplexing method |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN104993484B (en) | A kind of Active Power Filter-APF | |
| CN105932677A (en) | Harmonic suppression system with multi-level active power filter | |
| Liu et al. | Power quality improvement using controllable inductive power filtering method for industrial DC supply system | |
| TWI243526B (en) | Three-phase three-wire active power filter | |
| CN206099346U (en) | Harmonic restraint system with multistage active power filter | |
| Singh et al. | Review on power quality solution technology | |
| Geddada et al. | Modified four leg DSTATCOM topology for compensation of unbalanced and nonlinear loads in three phase four wire system | |
| Sadigh et al. | Unified power flow controller based on two shunt converters and a series capacitor | |
| CN108390572A (en) | Active third-harmonic zero-sequence voltage matrix converter input current waveform optimizes topological structure | |
| CN100488017C (en) | Device for eliminating loop in inverter parallel running system | |
| CN102291018B (en) | Single-phase rectifier with APFC (active power factor correction) circuit and alternating-current input voltage amplitude detection method thereof | |
| Chen et al. | Control strategy for three-phase four-wire PWM converter of integrated voltage compensation type active SFCL | |
| CN205565742U (en) | Mixed electric power equalizer that passive zero sequence filtering technique and active filtering technique combine | |
| CN106706995A (en) | Inductive current detection circuit in bridgeless power factor correction PFC circuit | |
| TWI580144B (en) | Power quality compensation system | |
| CN106602850A (en) | Self-coupled power ripple suppression circuit and method | |
| CN110429842B (en) | Single-sensor inverter control method combining inductance voltage and capacitance voltage | |
| CN201417951Y (en) | Tunable filter | |
| Sensarma et al. | A comparative study of harmonic filtering strategies for a shunt active filter | |
| CN209961836U (en) | Zero-crossing detection system | |
| CN209250489U (en) | power supply circuit and household appliance | |
| CN103493352B (en) | Power inverter | |
| CN106253312A (en) | A kind of three-phase imbalance intelligent compensation apparatus | |
| CN206293903U (en) | A kind of three-phase imbalance intelligent compensation apparatus | |
| CN202495811U (en) | Power supply circuit for chain-type SVG module |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant |