Background technology
Along with the growing tension of traditional energy, the application of novel clean energy resource (as solar energy, fuel cell) generating obtains promoting gradually.A distinguishing feature of this class energy is that input voltage and input power excursion are very big.With the solar electricity generation field battery is example, and same Battery pack plate is under different illumination conditions, and its VD can differ one times at the most.This type of sun-generated electric power inserts threephase load or electrical network, must have an energy to keep the constant three-phase DC/AC inverter circuit of output three-phase alternating voltage as interface in big input voltage range.
The circuit of realizing above function at present mainly contains two big classes:
One, isolated form; Two, non-isolation type.Wherein isolated form can be divided into, and adopts the high frequency transformer isolated form and adopts the Industrial Frequency Transformer isolated form.The advantage of isolated form is to realize the electrical isolation of electrical network and solar cell, thereby security of system is good; No-load voltage ratio by the design transformer is easier to realize voltage transformation, thereby control is simple relatively.But because all power will pass through transformer, thereby the efficient of system reduces.Mainly adopt the BOOST booster circuit to realize boosting for the three-phase non-isolation type.Level three-phase full-bridge inverter in back only has only a phase brachium pontis to be operated in the high frequency state at one time, and the inverter mode of operation that other two-phase brachium pontis are operated in the low frequency state is to improving the solar inverter efficient meaning of having large improvement.Need the prime booster circuit can provide one of output in power frequency period, to have the DC voltage waveform of the sinusoidal wave head of six arteries and veins for this reason.If adopt the isolated form booster circuit as prime, then all energy will reduce overall efficiency by transformer; If prime adopts the BOOST circuit to boost, because its output is the DC voltage waveform that has the sinusoidal wave head of six arteries and veins in a power frequency period, this to control brought big difficulty (particularly the output voltage when solar cell is lower, the step-up ratio of BOOST circuit near or greater than 2 o'clock); When DC input voitage was low, the decrease in efficiency of complete machine was obvious simultaneously.
At isolated form and non-isolation type pluses and minuses separately, the someone proposes part isolated form translation circuit.This circuit has two independent DC converter between solar DC power supply and output stage, the input of these two DC converter is attempted by the positive and negative two ends of solar DC power supply, their output is cascaded to make up and generates three phase full wave rectification steamed bun ripple DC voltage waveform, again through the output stage paraphase, keep the constant three phase sine alternating voltage of output, incorporate threephase load or AC network into.Owing to adopted two converters to finish combined DC/DC conversion, so complex structure, the utilance of device is lower, and cost is higher relatively.
Summary of the invention
The utility model proposes a kind of combined high-efficiency three-phase DC/AC inverter circuit of part isolated form of compactness at the deficiency with top isolated form inverter circuit technology.
The technical solution adopted in the utility model is as follows:
The positive and negative two ends of solar cell link to each other with the positive-negative input end of DC converter, and the output negative terminal of DC converter links to each other with the input anode of this converter, and are flat with the output DC of raising converter; So be output as the three phase full wave rectification voltage waveform of band direct current platform between the output plus terminal of converter and the negative terminal of solar cell; With of copped wave, the paraphase of this output voltage, generate the output of three phase sine alternating voltage again, incorporate three-phase alternating current electrical network or load into through band LC filtering output translator.
Beneficial effect
1, adopt the three-phase DC/AC inverter circuit of isolated form input prime with respect to tradition, the portion of energy of DC power supply directly flows into output translator by power supply without high frequency chopping, and overall efficiency and device volume all reduce a lot.
2, with respect to the three-phase DC/AC inverter circuit of tradition band BOOST booster circuit input prime, the step-up ratio of DC converter descends a lot, and the control characteristic of circuit and the efficient of booster circuit just improve a lot, thereby higher cost performance and power density are arranged.
3, with respect to traditional part isolated form DC/AC inverter, the DC converter circuit obtains simplifying, and the utilance of device is improved, and the reliability of device is improved.
Embodiment
Below in conjunction with accompanying drawing the utility model is described in further detail.
Referring to Fig. 1,1 is solar energy Equivalent DC power supply, the positive input terminal of output that it is positive and DC converter 2 and the negative output terminal of this converter link together, and an input of the output translator 3 of the output that Equivalent DC power supply 1 is negative and the negative input end of DC converter 2 and band LC filtering links together; The positive output of DC converter 2 and another input of output translator 3 link together.The positive output end of DC converter 2 and Equivalent DC power supply 1 are connected with the input of output translator 3 as both cascade output of DC converter 2 and Equivalent DC power supply 1.The output of output translator 3 links together with three ac circuit ends of three-phase alternating current electrical network or load 4 respectively.
During the utility model operation work, the output voltage of Equivalent DC power supply 1 is fed to the input of DC converter 2, because the negative output terminal of DC converter 2 links to each other with positive input terminal, the output DC of having raised DC converter 2 is flat, so the output voltage U dc between the negative terminal of the positive output end of DC converter 2 and Equivalent DC power supply 1 is the three phase full wave rectification voltage waveform of band direct current platform; Then, this voltage U dc feed-in band LC filtering output translator 3 through the control of output translator 3, generates three phase sine alternating voltage Uac output; At last, this voltage U ac incorporates three-phase alternating current electrical network or load 4 into.
DC converter 2 of the present utility model can be the full-bridge isolated converter, forward converter, and anti exciting converter, PUSH-PULL circuit or half-bridge are isolated inverter circuit.
Embodiment one
As shown in Figure 2, entire circuit comprises four major parts, and is corresponding with the structured flowchart among Fig. 1, one, Equivalent DC power supply 1; Two, DC converter 2; Three, output translator 3; Four, threephase load or electrical network 4.Wherein DC converter 2 is by switching tube VT1, fly-wheel diode VD1, and inductance L 1, switching tube VTh1~VTh4, high frequency transformer T1, rectifier diode VD2~VD5, capacitor C 1 is formed; Output translator 3 is by switching tube VTL1~VTL6, inductance L f1~Lf3, and capacitor C f1~Cf3 forms.The drain electrode of the switching tube VT1 of the anode of Equivalent DC power supply 1 and DC converter 2, rectifier diode VD4, the anode of VD5 links to each other.The anode of the fly-wheel diode VD1 of the negative terminal of Equivalent DC power supply 1 and DC converter 2, the source electrode of switching tube VTh3 and VTh4, and the negative dc bus of the three-phase full-bridge inverter of output translator 3 connects.The source electrode of switching tube VT1 links to each other with an end of inductance L 1 and the negative electrode of fly-wheel diode VD1.The other end of inductance L 1 links to each other with the drain electrode of switching tube VTh1 and VTh2.The source electrode of switching tube VTh1 is connected with an end of the drain electrode of VTh3 and high frequency transformer T1 input; The source electrode of switching tube VTh2 is connected with the other end of the drain electrode of VTh4 and high frequency transformer T1 input.Rectifier diode VD2~VD5 forms rectifier bridge, it exchanges the input two ends and links to each other with the output two ends of high frequency transformer T1 respectively, the negative terminal of its direct current output links to each other with the anode of Equivalent DC power supply 1 and an end of capacitor C 1 links to each other, and the anode of its direct current output is connected with the other end of capacitor C 1 and the three-phase full-bridge inverter positive direct-current bus of output translator 3.Switching tube VTL1~the VTL6 of output translator 3 forms three-phase full-bridge inverter, and inductance L f1~Lf3 and capacitor C f1~Cf3 form three-phase low-pass filter; The positive bus-bar of three-phase full-bridge inverter links to each other with the positive output end that rectifier diode VD2~VD5 forms rectifier bridge, and the negative busbar of three-phase full-bridge inverter links to each other with the negative terminal of Equivalent DC power supply 1; Three ac output ends of three-phase full-bridge inverter link to each other respectively with three inputs of three-phase low-pass filter; Three outputs of three-phase low-pass filter link to each other respectively with the three-phase terminal of threephase load or electrical network 4.
The input dc power corrugating Udc of output translator 3 as shown in Figure 1, it is produced jointly by Equivalent DC power supply 1 and DC converter 2.Wherein the sinusoidal steamed bun ripple direct current part of Udc-Vin by the switching tube of DC converter 2 with the input direct voltage high frequency chopping after by transformer T1, rectifier diode VD2~VD5 rectification and capacitor C 1 filtering produce, the input two ends that this part steamed bun ripple and input direct voltage Vin level connect together and be added in output translator 3.Adopt isolated form to import the three-phase DC/AC inverter circuit of prime with respect to tradition, the portion of energy of DC power supply directly flows into output translator 3 by power supply without high frequency chopping, and overall efficiency and device volume all reduce a lot.With respect to the three-phase DC/AC inverter circuit of tradition band BOOST booster circuit input prime, the step-up ratio of DC converter 2 descends a lot, and the control characteristic of circuit and the efficient of booster circuit just improve a lot, thereby higher cost performance and power density are arranged.With respect to traditional part isolated form DC/AC inverter, the DC converter circuit obtains simplifying, and the utilance of device is improved, and the reliability of device is improved.
Embodiment two
As shown in Figure 3, entire circuit comprises four major parts, and is corresponding with the structured flowchart among Fig. 1, one, Equivalent DC power supply 1; Two, DC converter 2; Three, output translator 3; Four, threephase load or electrical network 4.Wherein DC converter 2 is by switching tube VTh1~VTh4, high frequency transformer T1, and rectifier diode VD1~VD4, inductance L 1 capacitor C 1 is formed; Output translator 3 is by switching tube VTL1~VTL6, inductance L f1~Lf3, and capacitor C f1~Cf3 forms.The drain electrode of the switching tube VTh1 of the anode of Equivalent DC power supply 1 and DC converter 2, the drain electrode of switching tube VTh2, and rectifier diode VD3, the anode of VD4 links to each other.The switching tube VTh3 of the negative terminal of Equivalent DC power supply 1 and DC converter 2 and the source electrode of VTh4, and the emitter of the switching tube VTL4~VTL6 of output translator 3 links to each other.The source electrode of switching tube VTh1 is connected with an end of the drain electrode of VTh3 and high frequency transformer T1 input; The source electrode of switching tube VTh2 is connected with the other end of the drain electrode of VTh4 and high frequency transformer T1 input.Rectifier diode VD1~VD4 forms rectifier bridge, it exchanges the input two ends and links to each other with the output two ends of high frequency transformer T1 respectively, the negative terminal of its direct current output links to each other with the anode of Equivalent DC power supply 1 and an end of capacitor C 1, and the anode of its direct current output is connected with an end of inductance L 1.Switching tube VTL1~the VTL6 of output translator 3 forms three-phase full-bridge inverter, and inductance L f1~Lf3 and capacitor C f1~Cf3 form three-phase low-pass filter; The positive bus-bar of three-phase full-bridge inverter links to each other with an end of inductance L 1 and capacitor C 1, and the negative busbar of three-phase full-bridge inverter links to each other with the negative terminal of Equivalent DC power supply 1; Three ac output ends of three-phase full-bridge inverter link to each other respectively with three inputs of three-phase low-pass filter; Three outputs of three-phase low-pass filter link to each other respectively with the three-phase terminal of threephase load or electrical network 4.
The input dc power corrugating Udc of output translator 3 as shown in Figure 1, it is produced jointly by Equivalent DC power supply 1 and DC converter 2.Wherein the sinusoidal steamed bun ripple direct current part of Udc-Vin by the switching tube of DC converter 2 with the input direct voltage high frequency chopping after by transformer T1, rectifier diode VD1~VD4 rectification, inductance L 1 and capacitor C 1 filtering produce, the input two ends that this part steamed bun ripple and input direct voltage Vin level connect together and be added in output translator 3.Adopt isolated form to import the three-phase DC/AC inverter circuit of prime with respect to tradition, the portion of energy of DC power supply directly flows into output translator by power supply without high frequency chopping, and overall efficiency and device volume all reduce a lot.With respect to the three-phase DC/AC inverter circuit of tradition band BOOST booster circuit input prime, the step-up ratio of DC converter 2 descends a lot, and the control characteristic of circuit and the efficient of booster circuit just improve a lot, thereby higher cost performance and power density are arranged.With respect to traditional part isolated form DC/AC inverter, the DC converter circuit obtains simplifying, and the utilance of device is improved, and the reliability of device is improved.