Based on the two Sepic inverters of the integrated isolated form single-stage of magnetic
Technical field
The present invention relates to the inverter in a kind of transformation of electrical energy device, but relate in particular in the single-phase inversion occasion that is applied in the also step-down of both can boosting based on the two Sepic inverters of the integrated isolated form single-stage of magnetic.
Background technology
Exhaustion day by day along with the non-regenerative resource in the world; Renewable energy power generation such as solar power generation and wind power generation develops gradually even has replaced the generating of the traditional expendable energy; Because it is inexhaustible that these generations of electricity by new energy have, and advantage such as environmentally safe.Inverter is the core component of renewable energy power generation equipment, both can also can be used as interface and transfer the energy to AC network directly for AC load provides electric power.Because the randomness and the uncertainty of regenerative resource Energy distribution, this also causes the pulsating nature of its power output, mainly shows as the wide variation of direct voltage.Traditional voltage type bridge-type inverter is the voltage-dropping type inverter, and its AC side voltage peak can only be lower than dc voltage, therefore can not be applicable to the application scenario of input voltage wide variety.For addressing this problem, adopt two kinds of methods usually: a kind of is to adopt the multistage inversion transformation technique, promptly boosts through DC converter earlier and utilizes bridge inverter main circuit etc. to realize inversion again; But the circuit structure of this method is complicated, and the components and parts of use are many, and inefficiency.Another kind is to adopt power frequency to isolate inversion transformation technique, promptly utilizes bridge inverter main circuit to realize that inversion is again through the duplex frequency boostering transformer matched output voltage earlier; Owing to used Industrial Frequency Transformer, thereby increased the volume and the cost of system, reduced system effectiveness simultaneously.
Adopt the high frequency transformer that volume is little, cost is lower and efficient is higher, replace Industrial Frequency Transformer, constituting the high-frequency isolation inverter is a good thinking that addresses the above problem.This respect has been obtained a lot of achievements in research.But existing achievement in research is on the voltage-dropping type circuit basis of (comprising Buck circuit, forward converter and bridge circuit), to transform to deduce mostly; Because therefore these circuit dropping voltage characteristic in essence will realize boost function, can only utilize the no-load voltage ratio of transformer, limited because of boost capability, can not be applicable to the application scenario of wide input voltage range.In addition, also having with the anti exciting converter is the high-frequency isolation inverter structure that the basis constitutes.Anti exciting converter itself has the buck ability, thereby this structure can be applicable to the application scenario of wide input voltage range, but the transformer of anti exciting converter is a unidirectional magnetiztion, and therefore this structure can only be used for low power occasion.The achievement in research of utilizing other isolation DC/DC converters with buck ability such as Cuk converter, Sepic converter and Zeta converter to constitute the high-frequency isolation inverter also has; But the equal more complicated of structure; The switching device number that uses is huge; And need two above transformers usually, be unfavorable for the integrated design of magnetic of system.
Summary of the invention
In order to overcome the deficiency that exists in the prior art, it is a kind of based on the two Sepic inverters of the integrated isolated form single-stage of magnetic that the present invention provides.The present invention makes up a kind of single-stage single-phase inverter of realizing the buck inversion with the mode of two isolated form Sepic converters through output-parallel, and realizes that through integrated magnetic the many magnetic elements of inverter are integrated.
In order to solve the technical problem of above-mentioned existence; The present invention is achieved by the following technical solutions: a kind of based on the two Sepic inverters of the integrated isolated form single-stage of magnetic, comprise input 1, the first isolated form Sepic circuit output end 2 and the second isolated form Sepic circuit output end 3 of isolated form Sepic circuit;
In the input 1 of described isolated form Sepic circuit, first inductance L
1A termination power V
iPositive pole, first inductance L
1Another termination first power switch tube S
1The anode and first capacitor C
1An end, first power switch tube S
1Negative electrode meet power supply V
iNegative pole, first capacitor C
1Another termination second inductance L
2An end and the first winding N of high frequency transformer T
1An end, second inductance L
2The other end and the first winding N of high frequency transformer T
1Another termination power V
iThe negative pole and first power switch tube S
1Negative electrode;
In the described first isolated form Sepic circuit output end 2, the first power diode D
1Anode meet the second winding N of high frequency transformer T
2An end, this end and first capacitor C
1The first winding N of the high frequency transformer T that is connected
1An end of the same name, the first power diode D
1Negative electrode connect second capacitor C
2An end and an end of load, second capacitor C
2Another termination second power switch tube S
2Anode and the 3rd inductance L
3An end, the 3rd inductance L
3The other end of another termination load, second power switch tube S
2Negative electrode meet the second winding N of high frequency transformer T
2The other end;
In the described second isolated form Sepic circuit output end 3, the 3rd power switch tube S
3Anode meet the tertiary winding N of high frequency transformer T
3An end, this end and first capacitor C
1The first winding N of the high frequency transformer T that is connected
1An end of the same name, the 3rd power switch tube S
3Negative electrode be connected to second power switch tube S
2The anode and second capacitor C
2The junction, the second power diode D
2The anode and the first power diode D
1Negative electrode, second capacitor C
2An end that is connected with load is connected, the second power diode D
2Negative electrode meet the tertiary winding N of high frequency transformer T
3The other end.
Described first inductance L
1, second inductance L
2All be integrated on the same secondary E type magnetic core with high frequency transformer T; The first winding N of high frequency transformer T
1, the second winding N
2With tertiary winding N
3All be wound on the center pillar of magnetic core first inductance L
1With second inductance L
2Respectively by two series connection windings be wound on respectively magnetic core about on two lateral columns, and two series connection umber of turns of each inductance are identical.So just make: half winding separately of two inductance on the post of left side intercouples, and half winding separately of two inductance on the post of right side intercouples, and after the left and right sides windings in series of each inductance, still can satisfy first inductance L
1With second inductance L
2Be of coupled connections; Two windings of each inductance are at the magnetic flux equal and opposite in direction of center pillar generation simultaneously, and in the opposite direction, magnetic flux is cancelled out each other, and realizes that the decoupling zero of two coupling inductances and transformer is integrated.
The present invention adopt based on the two Sepic inverters of the integrated isolated form single-stage of magnetic, comprise two isolated form Sepic circuit units, realize inversion through the parallel connection of two outlet sides.Because of the input side of two isolated form Sepic circuit is identical in the operation principle in the half period up and down, so the present invention adopts an input side circuit, both saved the quantity of switching device and transformer, improved the utilization ratio of power device again.
The present invention can be divided into two functional modules by the former and deputy limit of transformer: half-sinusoid generation module and polarity upset module.At the half-sinusoid generation module,, rely on first inductance L through control to first power switch pipe
1, second inductance L
2With first capacitor C
1, forming a dither DC signal on the former limit of transformer, its low frequency component is that a frequency is the half-sinusoid signal of one times of output frequency.In the polarity upset module, be connected in reverse parallel in again in the load by switching tube and hold-off diode series connection, through controlling second power switch tube S
2With the 3rd power switch tube S
3The mode of complementary conducting realizes sinusoidal wave positive and negative half-wave output.Circuit input end mainly relies on the form of electric current to transmit energy to output, and output is owing to being output as current mode output, so second power switch tube S
2With the 3rd power switch tube S
3Drive signal should not add the dead band, and should between shift zone, adopt the overlapping interval method.Adopt the method for monocycle control, make inverter when operate as normal, not need bias current, inductive current is operated under the continuous mode, reduced EMI.It is fast that monocycle control also has dynamic response, suppresses power-supply fluctuation, realizes characteristics such as simple.In one-period, the circuit input end power switch tube S of winning
1The floating voltage of PWM control be the absolute value of a sine wave, and output second power switch tube S
2With the 3rd power switch tube S
3As foregoing according to principle of complementarity with power frequency work.
Owing to adopt technique scheme, provided by the invention based on the two Sepic inverters of the integrated isolated form single-stage of magnetic, compared with prior art, its beneficial effect is:
The present invention makes up a kind of single-stage single-phase inverter that can realize the buck inversion with the mode of two isolated form Sepic converters through output-parallel, and realizes that through integrated magnetic the many magnetic elements of inverter are integrated.Because the Sepic converter itself has the liftable compression functions in the circuit, utilizes the no-load voltage ratio of high frequency transformer again, makes input further enlarge, and can satisfy the requirement of photovoltaic DC-to-AC converter wide input voltage range, and can realize the buck invert function.DC power supply and constant DC source for fluctuation all can be as power supply V
iBe lower than and be not less than the external power supply V of AC side peak-peak voltage for instantaneous value
i, all can make the two Sepic inverter operate as normal of said isolated form single-stage, be a kind of regenerative resource and generation of electricity by new energy Technology Need of meeting, be applicable to the novel inverter of wide input voltage range and mid power occasion.
The present invention has only adopted an inlet circuit, has improved the utilization ratio of input power supply, has only adopted a high frequency transformer and three full control switching devices in the circuit structure, and is simple in structure.Import and the output electrical isolation owing to there is high frequency transformer to make, system input and output do not have common point, and system has more fail safe and disturbance rejection property.High frequency transformer among the present invention is two-way magnetization, can bear than high power capacity.The present invention has done the integrated processing of magnetic to magnetic element, has reduced the magnetic element volume, improves power-efficient and power density, has reduced the inductive current ripple.Adopt the method for monocycle control, make its control simple, dynamic response is fast, and tracking performance is good, and the fluctuation of power supply is had stronger inhibition ability.
Description of drawings
Fig. 1 is the electrical block diagram based on the integrated two Sepic inverters of isolated form single-stage of magnetic of the present invention;
Fig. 2-the 5th, each switch mode sketch map based on the integrated two Sepic inverters of isolated form single-stage of magnetic of the present invention;
Fig. 6 is the modulator approach based on the integrated two Sepic inverter power switching tubes of isolated form single-stage of magnetic of the present invention;
Fig. 7 is the drive waveforms sketch map based on the integrated two Sepic inverter power switching tubes of isolated form single-stage of magnetic of the present invention;
Fig. 8 is the output voltage waveform based on the integrated two Sepic inverters of isolated form single-stage of magnetic of the present invention;
Fig. 9 is the output current wave figure based on the integrated two Sepic inverters of isolated form single-stage of magnetic of the present invention;
Figure 10 is the control principle figure that adopts based on the two Sepic inverters of the integrated isolated form single-stage of magnetic of the present invention;
Figure 11 is of the present invention based on the two Sepic inverters of the integrated isolated form single-stage of magnetic given waveform that adopts and the drive waveforms that drives the 3rd, the 4th power switch pipe;
Figure 12 is the decoupling zero integrated approach based on two Sepic inverter coupling inductances of the integrated isolated form single-stage of magnetic and transformer of the present invention;
Figure 13 is of the present invention based on the integrated preceding inductance (L of the two Sepic inverter magnetic of the integrated isolated form single-stage of magnetic
1) and inductance (L
2) current waveform figure;
Figure 14 is the current waveform figure based on two Sepic inverter magnetic integrated back inductance (L1) of the integrated isolated form single-stage of magnetic and inductance (L2) of the present invention.
Main designation in the above-mentioned accompanying drawing: the 1. input of isolated form Sepic circuit; 2. the first isolated form Sepic circuit output end; 3. the second isolated form Sepic circuit output end; V
i---the inverter input supply voltage; L
1~L
2---linear inductance.L
3---filter inductance; C
1---Sepic circuit intermediate energy storage electric capacity; C
2---filter capacitor; S
1~S
2---power switch pipe; D
1~D
2---power diode; T---high frequency transformer; R---load impedance; Vp1~Vp3---power switch tube S
1~S
3Driving voltage; V
o---the load output voltage; I (R)---load output current; V
Ref1---the first isolated form Sepic circuit monocycle was controlled given voltage; V
Ref2---the second isolated form Sepic circuit monocycle was controlled given voltage; R
Int1~R
Int2---integrating circuit resistance; C
Int1~C
Int2---integrating circuit electric capacity; I (L1)---first inductance L
1Electric current; I (L2)---the second inductance (L
2) electric current; I (M1_1)---the electric current after first inductance (L1) is integrated; I (M1_2)---the second inductance (L
2) electric current after integrated.
Embodiment
Below in conjunction with accompanying drawing and embodiment the present invention is described in further detail:
Based on the two Sepic inverters of the integrated isolated form single-stage of magnetic; Shown in accompanying drawing 1; Be made up of input power supply, three switching tubes, two hold-off diodes, three inductance, two electric capacity, list former limit double-secondary transformer and output loading, it comprises input 1, the first isolated form Sepic circuit output end 2 and the second isolated form Sepic circuit output end 3 of isolated form Sepic circuit;
In the input 1 of isolated form Sepic circuit, first inductance L
1A termination power V
iPositive pole, first inductance L
1Another termination first power switch tube S
1The anode and first capacitor C
1An end, first power switch tube S
1Negative electrode meet power supply V
iNegative pole, first capacitor C
1Another termination second inductance L
2An end and the first winding N of high frequency transformer T
1An end, second inductance L
2The other end and the first winding N of high frequency transformer T
1Another termination power V
iThe negative pole and first power switch tube S
1Negative electrode;
In the first isolated form Sepic circuit output end 2, the first power diode D
1Anode meet the second winding N of high frequency transformer T
2An end, this end and first capacitor C
1The first winding N of the high frequency transformer T that is connected
1An end of the same name, the first power diode D
1Negative electrode connect second capacitor C
2An end and an end of load, second capacitor C
2Another termination second power switch tube S
2Anode and the 3rd inductance L
3An end, the 3rd inductance L
3The other end of another termination load, second power switch tube S
2Negative electrode meet the second winding N of high frequency transformer T
2The other end;
In the second isolated form Sepic circuit output end 3, the 3rd power switch tube S
3Anode meet the tertiary winding N of high frequency transformer T
3An end, this end and first capacitor C
1The first winding N of the high frequency transformer T that is connected
1An end of the same name, the 3rd power switch tube S
3Negative electrode be connected to second power switch tube S
2The anode and second capacitor C
2The junction, the second power diode D
2The anode and the first power diode D
1Negative electrode, second capacitor C
2An end that is connected with load is connected, the second power diode D
2Negative electrode meet the tertiary winding N of high frequency transformer T
3The other end.
Described first inductance L
1, second inductance L
2All be integrated on the same secondary E type magnetic core with high frequency transformer T; The first winding N of high frequency transformer T
1, the second winding N
2With tertiary winding N
3All be wound on the center pillar of magnetic core first inductance L
1With second inductance L
2Respectively by two series connection windings be wound on respectively magnetic core about on two lateral columns, and two series connection umber of turns of each inductance are identical.
In circuit of the present invention, first inductance L
1Be input inductance, main effect is energy storage and transmission, and keeps input current contact, second inductance L
2Through first power switch tube S
1Conducting and closed storage and the release of accomplishing energy; First capacitor C
1Be intermediate energy storage electric capacity, its voltage is identical with input voltage; Second capacitor C
2With the 3rd inductance L
3The resonant circuit of forming is used for output voltage filtering.High frequency transformer T among the present invention is single former limit double-secondary transformer, thus the former limit of transformer in the positive and negative half period of sine wave respectively to two secondary winding transmission of power, promptly two of the transformer secondary output circuits are not to work simultaneously.
When circuit working before sinusoidal wave in the half period time, the first isolated form Sepic circuit output end 2 is in running order, the second isolated form Sepic circuit output end 3 is not worked, circuit comprises two operation modes at this moment:
Operation mode I
Shown in accompanying drawing 2, power switch tube S
1And S
2Conducting, S
3Turn-off, power supply is through power switch tube S
1Give inductance L
1Charging, inductance L
1Electric current rise; The while capacitor C
1Through power switch tube S
1Give inductance L
2Charging, inductance L
2Electric current rises; Because power diode D
1Be in reverse blocking state, input does not transmit energy to output, and load voltage is mainly by capacitor C
2With inductance L
3The resonant circuit of forming provides.
Operation mode II
Shown in accompanying drawing 3, power switch tube S
1And S
3Turn-off S
2Conducting, power supply is through inductance L
1Give capacitor C
1Charging, stable back capacitor C
1Voltage is identical with input voltage; Simultaneously because diode D
1Forward conduction, inductance L
1And L
2Transmit energy through transformer to output, inductive current descends; Transformer secondary output energy is through power diode D
1Power to the load, and give filter capacitor C
2Charging.
When circuit working behind sine wave in the half period time, the second isolated form Sepic circuit output end 3 is in running order, the first isolated form Sepic circuit output end 2 is not worked, this moment, circuit comprised two operation modes:
Operation mode III
Shown in accompanying drawing 4, power switch tube S
1And S
3Conducting, S
2Turn-off, power supply is through power switch tube S
1Give inductance L
1Charging, inductance L
1Electric current rise; The while capacitor C
1Through power switch tube S
1Give inductance L
2Charging, inductance L
2Electric current rises; Because power diode D
2Be in reverse blocking state, input does not transmit energy to output, and load voltage is mainly by capacitor C
2With inductance L
3The resonant circuit of forming provides.
Operation mode IV
Shown in accompanying drawing 5, power switch tube S
1And S
2Turn-off S
3Conducting, power supply is through inductance L
1Give capacitor C
1Charging, stable back capacitor C
1Voltage is identical with input voltage; Simultaneously because power diode D
2Forward conduction, inductance L
1And L
2Transmit energy through transformer to output, inductive current descends; Transformer secondary output energy is through power diode D
2Power to the load, and give filter capacitor C
2Charging.
More than four operation mode free lists 1 represent; The circuit key waveforms is shown in accompanying drawing 7-9; Be the position that 2,3 work of two isolated form Sepic circuit output ends are switched at output current zero crossing place, the alternation of two isolated form Sepic circuit output ends is to keep output voltage waveforms.
The power tube switch combination state of the two Sepic inverters of table 1 isolated form single-stage
For realizing above operation principle, adopt controlling schemes shown in accompanying drawing 10: the present invention adopts two cover monocycle control system to realize invert function, chooses power diode D
1With power diode D
2The voltage at two ends is compared with given voltage behind integration as feedback voltage, obtains two cover control system outputs and drives the PWM ripple through controlling first power switch tube S with the synthetic driving PWM ripple of OR circuit
1Break-make.The main circuit output is under sinusoidal first cycling situation; Has only a cover control system job; Having added one, to have duty ratio be 0.5 power frequency drive signal or door, makes the integrator hold reset state of idle that cover control system of output, for following half power frequency period is prepared; Simultaneously first cycling control system PWM drive signal and duty ratio be 0.5 power frequency drive signal get " with ", obtain first cycle control system PWM output waveform; In like manner obtain another set of control system PWM output waveform of second cycle, 180 ° of two cover control system output waveform phase phasic differences.First power switch tube S is supplied with in OR circuit realization of final dependence two cover control system outputs simultaneously
1Driving PWM ripple.And second power switch tube S
3With the 3rd power switch tube S
4Drive waveforms should follow two given sides, keep the Chang Kaichang of half sine wave period to close, complementary each other, two given waveforms and S
3, S
4Drive waveforms shown in accompanying drawing 11.
Shown in accompanying drawing 12, this embodiment based on the two Sepic inverters of the integrated isolated form single-stage of magnetic, first inductance L
1, second inductance L
2All be integrated on the same secondary E type magnetic core with high frequency transformer T; The first winding N of high frequency transformer T
1, the second winding N
2With tertiary winding N
3All be wound on the center pillar of magnetic core first inductance L
1With second inductance L
2Be wound on respectively on two lateral columns of magnetic core by two series connection windings respectively, and guarantee that two series connection umber of turns of each inductance are identical.Wherein, half winding separately of two inductance intercouples on the post of left side, and half winding separately of two inductance intercouples on the post of right side, after the left and right sides windings in series of each inductance, still can satisfy first inductance L
1With second inductance L
2Be of coupled connections; Two windings of each inductance are at the magnetic flux equal and opposite in direction of center pillar generation simultaneously, and in the opposite direction, magnetic flux is cancelled out each other, and realizes that the decoupling zero of two coupling inductances and transformer is integrated.This magnetic integrated approach has not only reduced the volume of magnetic element, has increased power density, and has effectively eliminated second inductance L
2Middle current ripples has been optimized inverter current pulsation performance, has reduced electromagnetic interference.Shown in accompanying drawing 13-14, provided the integrated front and back of magnetic inductive current waveform.