CN102347706A

CN102347706A - Photovoltaic or wind-energy signal source type pure sine wave grid-connected inverter

Info

Publication number: CN102347706A
Application number: CN2010102448033A
Authority: CN
Inventors: 冯益安
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-07-27
Filing date: 2010-07-27
Publication date: 2012-02-08

Abstract

The invention discloses a photovoltaic or wind-energy signal source type pure sine wave grid-connected inverter, belongs to energy-efficient direct current to alternating current grid-connected power equipment, and mainly solves the problem of quality reduction of the electric energy of a power grid caused by more simulation waveform burrs which are generated by adopting digital pulse width modulation (PWM) and increase of harmonic waves of the power grid in the current grid-connected inverter. With amplification of an alternating current signal through a triode or a field effect tube, the alternating current signal is acquired from the power grid, a synchronous alternator or a 50-Hz oscillation circuit; the alternating current signal is subjected to filtering, voltage dividing or voltage reducing and current dividing or current reducing, then serves as a signal source and is directly applied to a base of the triode or the field effect tube through a driving circuit; the alternating current output of a collector of the triode or a drain of the field effect tube is controlled; the phase of a current is changed by using an inversion phase device to make the current and the power grid in-phase; a voltage is changed to make an output voltage greater than or equal to the voltage of the power grid; and output synchronous alternating currents are converged and then connected to the power grid. A sine wave signal which is synchronous with the power grid is used as a basic signal for amplifying the triode or the field effect tube, and the waveform of the sine wave signal is pure sine wave, so that the harmonic pollution of the power grid is avoided, the quality of grid-connected electric energy can be greatly improved, and the photovoltaic or wind-energy signal source type pure sine wave grid-connected inverter is low in cost, simple in circuit and easy to produce and convert.

Description

A kind of photovoltaic or wind energy signal source formula pure sine wave combining inverter

Technical field:

Photovoltaic or wind energy electric power grid-connection device

Background technology:

Present combining inverter adopts pulsewidth PWM modulation more; The waveform that produces is a simulation waveform; " burr " is more; Harmonic wave is more; Cause when being incorporated into the power networks that the electrical network quality of power supply descends more; Pollute to electrical network, also do not have at present a pure sine wave do not have a burr and guarantee the combining inverter that the output current phase place is identical.

Summary of the invention:

A kind of photovoltaic or wind energy signal source formula pure sine wave combining inverter belong to the high energy efficiency direct current and become to exchange the power equipment that is incorporated into the power networks, and mainly solve present combining inverter because the simulation waveform burr of taking pwm pulsewidth digital modulation to produce is more and cause that mains by harmonics increases the problem that causes the electrical network quality of power supply to descend.Method is: obtain AC signal from electrical network or synchronous alternator or 50 hertz of concussion resonant circuits; Through filtering; Dividing potential drop or step-down; Shunting or stream falls after be added in through drive circuit on the grid of base stage or field effect transistor of triode as signal source; Interchange output through push-pull type or full bridge circuit control transistor collector or field effect transistor drain electrode; And change current phase through the paraphase device and make and the electrical network homophase; Change voltage; Make the voltage of output voltage more than or equal to electrical network; Perhaps the battery direct current boosts through the high frequency booster circuit and becomes after the high voltage direct current again that the bridge circuit through field effect transistor is transformed into the alternating current that is a bit larger tham greater than electrical network, and the alternating current that the phase place of output is identical is connected to the grid after the pooling.Because the sine wave signal of employing and synchronized is as the basis signal of triode or field effect transistor amplification; Waveform after it amplifies still is a pure sine wave, can not produce harmonic pollution to electrical network, can increase substantially and network electric energy quality; And cost is lower, circuit is simple, is easy to produce transform.

Description of drawings:

Fig. 1 is common push-pull dc-to-ac schematic block circuit diagram.

Fig. 2 is amended push-pull dc-to-ac schematic block circuit diagram.

Fig. 3 is common full-bridge type inverter circuit theory diagram.

Fig. 4 is amended full-bridge type inverter circuit theory diagram.

Fig. 5 is existing high frequency boost type inverter circuit theory diagram commonly used.

Fig. 6 is amended high frequency boost type inverter circuit theory diagram.

Fig. 7 is the simple structure figure that obtains the synchronous ac signal from electrical network.Wherein (1) is that current-limiting resistance (2) is a phase inverter for divider resistance (3).

Embodiment:

Electric current and the electrical network " synchronously " accomplishing to be incorporated into the power networks and must make output, promptly frequency is identical, voltage is identical or higher slightly, and phase place is identical, is complementary with the main flow electricity pure sine wave of electrical network.Grid-connection device does not produce harmonic wave preferably, does not have burr in the waveform or has few burr.

Triode or field effect transistor have amplification to AC signal, and according to law of conservation of energy, energy can not produce without foundation, can not unprovokedly disappear." amplification " of triode is exactly the direct current energy that has consumed power supply in fact; Amplified AC power; Exactly direct current has been transformed into by " alternating current "; So simply say; The field effect transistor of triode or similar functions is exactly one " inverter "; But amplification according to base stage " AC signal " as changing foundation, the output frequency and the intensity size of the frequency of AC signal, current strength size determined set electrode current.

Traditional inverter all is to produce one " AC signal " by " Waveform generating circuit ", carries out " power amplification " through triode or field effect transistor then and realizes that direct current is to " inversion " that exchange.Such as square-wave inverter also is at first to produce " square wave " pulse signal, again " square wave " is carried out power amplification.Like this in traditional various inverters, no matter square wave is still revised ripple, or the emulation ripple, all be that one " Waveform generating circuit " arranged." waveform " of this Waveform generating circuit be the output of determined set electrode " waveform " in fact.So as long as in this " Waveform generating circuit " lining pure sinusoidal waveform can be provided, the alternating current of output is exactly " a pure sine wave ".But our traditional forms of enterprises has walked a lot of detours here, at first is that " square wave " produces, and is triangular wave then, is to revise ripple then, is the emulation ripple then, also have PWM ripple etc., but rarely found usefulness this " Waveform generating circuit " directly produces pure sine wave.Can produce one 50 hertz AC signal with oscillating circuit fully such as off-grid inverter.Be added on the base stage with drive circuit again, just can realize that pure sine wave leaves the net inverter.

In like manner; Can obtain AC signal from electrical network or synchronous alternator or 50 hertz of oscillating circuits; This AC signal can be regarded as by " Waveform generating circuit " and produces; This AC signal is passed through filtering, dividing potential drop or step-down, shunts or falls stream directly is added in triode or field effect transistor later on as signal source base stage; Through two triodes the selectivity of AC signal positive-negative half-cycle is amplified, form the interchange output of collector electrode or field effect transistor drain electrode.

To this, the conventional inverter circuit has two by all means push-pull circuits (like Fig. 1), and four by all means full bridge circuits (like Fig. 3) all are the amplifications fully of considering AC signal is carried out the positive-negative half-cycle waveform.Consider the high efficiency that high frequency boosts, 6 by all means high frequency booster circuits (like Fig. 5) are just arranged, wherein front two is used for high frequency by all means and boosts, and back four is used for the bridge circuit conversion by all means.

But, must accomplish that phase place is consistent for the synchronization AC electricity.The existence of phase difference can cause the quality of power supply to descend or loss each other.Differ 180 energy of will cancelling out each other when spending such as phase difference, the part that energy is little will be cancelled fully, so for being incorporated into the power networks, phase place is consistent not to have the existence at phase angle to require most important to being incorporated into the power networks.

But some equipment has inverting function.Such as: it is anti-phase or paraphase that the phase of ac signal of transistor base and collector electrode differs 180 degree.Inductance element possibly paraphase have phase difference according to access way is different.Alternating current paraphase through electric capacity.

So be both combining inverter, different according to access way, when being incorporated into the power networks, just possibly commit the opposite mistake of phase place.Therefore the phase adjusted of combining inverter is the sport technique segment of a key in practical application.

When electrical network obtains AC signal, can obtain synchronous AC signal, also can pass through the paraphase device and make its paraphase, through paraphase again after triode or the field effect transistor power amplification, just become the alternating current identical with the electrical network phase place.Therefore combining inverter is exported the output that exchanges that can be divided into electrical network homophase or anti-phase; Different phase and net mode are different; Homophase can directly insert electrical network such as plug with on & off switch, the need of anti-phase insert through inductance or electric capacity, perhaps the transformer access through anti-phase.

Because mains by harmonics increases year by year at present; Voltage jump; The AC signal of obtaining possibly not be very stable; So the power plant can be through small-sized synchronous generator or through obtaining stable sine wave AC signal with the synchronized resonant circuit; Also the AC signal in the electrical network can be stored; The AC signal of electrical network and synchronized, signal can not produce harmonic pollution to electrical network for the alternating current that produces as the pure sinusoid waveform thus, can keep also and can improve the electrical network quality of power supply.

Bottom makes following brief description with reference to the accompanying drawings:

The circuit of inverter is respectively push-pull dc-to-ac circuit (like Fig. 1), full-bridge type inverter circuit (like Fig. 3), high frequency boost type inverter circuit (like Fig. 5) basically, can use as combining inverter through revising to these three kinds of circuit.Alter mode such as Fig. 2 Fig. 4 are shown in Figure 6, all are " Waveform generating circuit " in original (Fig. 1, Fig. 3, Fig. 5) is replaced by 50 hz ac synchronizing signals or anti-phase (paraphase) signal that obtains from electrical network.Change the homophase or the anti-phase of signal according to the output of circuit, purpose is the alternating current that obtains when being incorporated into the power networks with the electrical network homophase.Because Fig. 2 and Fig. 4 pass through " transformer " and are connected to the grid, thus boost back anti-phase again just and synchronized through the alternating current of field effect transistor anti-phase through coil, so in the leaching process of signal, need not do " paraphase " processing.But also net mode is because the process high frequency boosts, and directly grafting is to electrical network for the synchronization AC electricity among Fig. 6, and this just need do anti-phase and handle the paraphase processing of perhaps when output, doing AC signal when signal is imported.So obtaining in the AC signal of Fig. 7 has the electronic component of a phase inverter (3) among electric capacity Fig. 7 as paraphase in the simple circuit.It is filtering that this paraphase mode cans be compared to, and major function is paraphase in fact.

The inverter that the output current phase place is identical with electrical network is called " same-phase inverter ", and being called of paraphase " antiphase inverter ", two kinds of inverters intervention method that when being incorporated into the power networks has fundamental difference.

In above Fig. 1 to Fig. 6, Fig. 1 and Fig. 2 compare, and Fig. 3 and Fig. 4 compare, and Fig. 5 and Fig. 6 are relatively.Fig. 7 obtains the simple diagram that exchanges reversed phase signal from electrical network.In Fig. 7, the effect of current-limiting resistance (1) is the overall electrical resistance that improves circuit, and its resistance is bigger, according to power consumption its power consumption is lower than below 1 watt.The effect of divider resistance (2) is to allow divider resistance obtain less voltage, and the power supply road is selected to use.Phase inverter (3) here is a capacitor, plays inverting function.

Claims

1. photovoltaic or wind energy signal source formula pure sine wave combining inverter; It is characterized in that: obtain AC signal from electrical network or synchronous alternator or 50 hertz of concussion resonant circuits; Through filtering; Dividing potential drop or step-down; Shunting or stream falls after be added in the base stage of triode or field effect transistor through drive circuit as signal source; Interchange output through push-pull type or full bridge circuit control transistor collector or field effect transistor drain electrode; And change current phase through the paraphase device and make and the electrical network homophase; Change voltage; Make the voltage of output voltage more than or equal to electrical network; Perhaps produce the alternating current greater than electrical network through bridge circuit again through the high frequency booster circuit, the synchronous AC of output is connected to the grid after the pooling.

2. according to a kind of photovoltaic according to claim 1 or wind energy signal source formula pure sine wave combining inverter; It is characterized in that obtaining the AC signal of homophase or anti-phase from electrical network; Alternating current and the electrical network homophase or the anti-phase of output, in-phase current directly is incorporated into the power networks, and is connected to the grid after the negative-phase sequence curent paraphase.

3. according to according to claim 1 and described a kind of photovoltaic of claim 2 or wind energy signal source formula pure sine wave combining inverter; It is characterized in that the paraphase device is a capacitor; Can be added in the back that the input signal front also can be added in output circuit, form two kinds of combining inverters with electrical network homophase and anti-phase.