CN204408212U - Flyback transformer leakage inductance energy absorption feedback circuit - Google Patents

Abstract

A kind of flyback transformer leakage inductance energy absorption feedback circuit, leakage inductance energy absorbs and feedback circuit integrates, only by a clamper tube S _cwith a clamp capacitor C _cform, simple and reliable for structure.Its control method is, clamper tube to be had no progeny ON time T in flyback supervisor pass _c, T _cfor the half of leakage inductance and clamp capacitor harmonic period, much smaller than the turn-off time of supervisor.The leakage inductance energy absorbed by clamp capacitor by the resonance of clamp capacitor and leakage inductance is discharged in main power circuit, effectively reduces the shutoff voltage spike of circuit of reversed excitation supervisor, improves the efficiency of anti exciting converter.Simultaneously due to clamper tube and the incomplementarity conducting of supervisor, clamper tube ON time far little be responsible for the turn-off time, thus this absorption and feedback circuit do not affect the switching process of supervisor, are applicable to the circuit of reversed excitation of any mode of operation.Adopt the miniature photovoltaic grid-connected inverter of the utility model scheme, its circuit reliability and efficiency are obtained for great lifting.

Description

Flyback transformer leakage inductance energy absorption feedback circuit

Technical field

The utility model relates to the absorption of flyback transformer leakage inductance energy in parallel network power generation field and feedback circuit and control method thereof.

Background technology

Miniature grid-connected photovoltaic inverter improves the generating efficiency of system in the situations such as photovoltaic module power mismatch, shade, and has safety simultaneously concurrently, can realize the advantages such as the monitoring of component level, obtains the application of photovoltaic in the photovoltaic parallel in system of residents.

Miniature grid-connected photovoltaic inverter is generally arranged on the support below assembly, or is directly installed on the frame of assembly, and maintenance and trouble thereof, thus need it to have with the same life and reliability of assembly.In addition inverse to run out of doors due to micro-, ambient temperature reaches as high as 65 DEG C, for the consideration of reliability, is all generally natural heat dissipation, thus need micro-inverse have very high efficiency could under the environment of 65 DEG C reliability service.

Anti exciting converter due to structure simple, reliable operation, and input, export electrical isolation.Be widely used in current miniature photovoltaic grid-connected inverter.Especially the anti exciting converter of critical discontinuous mode of operation, owing to can realize the ZVS Sofe Switch of switching tube, obtains the favor of each Miniature inverter production firm especially.

Current industry adopts the miniature photovoltaic grid-connected inverter efficiency of critical discontinuous mode of operation circuit of reversed excitation generally can accomplish 95%, 1-2 percentage point lower than the efficiency of traditional group string inverter.The large reason that current flyback scheme efficiency is difficult to promote is that the loss of flyback transformer leakage inductance is large, the leakage inductance of flyback transformer generally can account for the 1%-2% of magnetizing inductance, if the energy of leakage inductance is left intact, will dissipate in the form of heat, and very high shutoff voltage spike can be produced on flyback main switch, add the voltage stress of switching tube, have a strong impact on the reliability service of Miniature inverter.

So, the leakage inductance energy of flyback transformer absorbs and feedback circuit is and necessity, leakage inductance energy absorbs and is discharged in main power circuit by it, eliminates the shutoff voltage spike of flyback main switch, thus effectively can promote efficiency and the reliability thereof of current miniature photovoltaic grid-connected inverter.Current existing scheme has passive RCD to absorb Dumping Arrangements, Passive LC D absorbs feedback mechanisms, conventional active clamper scheme, passive clamping+active absorbing scheme etc.Wherein passive RCD absorbs Dumping Arrangements, can only absorb and be dissipated by the leakage inductance energy absorbed, and reduces the voltage stress of main switch, can not feedback leakage inductance energy, cannot raising efficiency; Active LCD absorbs feedback mechanisms structure relative complex, realizes difficulty.Conventional active clamper scheme is due to supervisor and the complementary conducting of clamper tube, and clamper tube can affect the operating state of supervisor, and circuit of reversed excitation can not be operated in interrupted and critical discontinuous mode, thus can not be applied in the critical discontinuous flyback scheme of current extensive use; In passive clamping+active absorbing scheme, active absorption circuit is generally made up of buck or circuit of reversed excitation, and topological structure and control method are all very complicated, and during feedback buck and circuit of reversed excitation efficiency not high, assimilation effect is not good.

Summary of the invention

The problems referred to above of prior art to be solved in the utility model, provide one the most general up to now and simple, reliable, efficiently flyback transformer leakage inductance energy absorb and feedback circuit and its control method.

Circuit of reversed excitation under the mode of operations such as the utility model is applicable to continuously, interrupted, critical discontinuous, solve the absorption of existing critical discontinuous mode of operation flyback transformer leakage inductance energy and feedback circuit and control too complicated problem, improve reliability and the efficiency of circuit of reversed excitation.

The technical scheme that the above-mentioned said technical problem of the utility model solution adopts is: flyback transformer leakage inductance energy absorbs and feedback circuit one, is only made up of a clamper tube and a clamp capacitor.Clamper tube and the conducting of supervisor's incomplementarity control, and make this absorption and feedback mechanisms can be suitable for interrupted and critical discontinuous (quasi-resonance) mode of operation circuit of reversed excitation.

A kind of flyback transformer leakage inductance energy absorbs and feedback circuit, it is characterized in that absorbing and feedback circuit integrated, be only made up of a clamper tube and a clamp capacitor.Clamper tube source electrode is connected with flyback supervisor drain electrode, and clamper tube drain electrode is connected with clamp capacitor.The passage that clamper tube provides leakage inductance energy to absorb and discharge, clamp capacitor is then the medium that leakage inductance energy temporarily stores.

Described flyback transformer leakage inductance energy absorbs and feedback circuit clamper tube can adopt N-channel MOS FET, also can adopt P channel mosfet.

The utility model also provides the control method of above-mentioned absorption and feedback circuit, it is characterized in that clamper tube and the conducting of supervisor's incomplementarity.Clamper tube is only had no progeny in supervisor pass conducting T blink _c, this time is much smaller than the turn-off time of supervisor.During this period of time, the leakage inductance energy absorbed by clamp capacitor by the resonance of clamp capacitor and leakage inductance is discharged in input and output capacitors and goes.

The ON time of clamper tube can be tried to achieve by following formula:

$T_c=\mathrm{\π}\sqrt{L_k\·C_c}$

Wherein L _kfor leakage inductance inductance value, C _cfor clamp capacitor capacitance.

In control method described in the utility model, clamper tube to be had no progeny T blink in supervisor pass _cjust absorbed by leakage inductance energy and be discharged into main power circuit, clamper tube just turns off subsequently, after not interfering interrupted and critical discontinuous mode anti exciting converter excitation inductance current reset-to-zero, and the resonant process of magnetizing inductance and junction capacitance.Thus the flyback transformer leakage inductance energy that provides of the utility model absorbs and feedback circuit apparatus control method is applicable to the circuit of reversed excitation of various mode of operation.

Flyback transformer leakage inductance energy absorption feedback circuit of the present utility model and control method have following technical advantage:

1, absorption and feedback circuit one, simple and reliable

2, the switch of clamper tube does not affect the work of supervisor, is suitable for interrupted, critical discontinuous, continuous operation mode circuit of reversed excitation

3, leakage inductance energy is by clamp capacitor reliable absorbtion, eliminates the due to voltage spikes of circuit of reversed excitation main power tube, improves the reliability of circuit of reversed excitation

4, the leakage inductance energy that clamp capacitor absorbs can be discharged into main power circuit completely, improves the efficiency of circuit of reversed excitation

Accompanying drawing explanation

Below in conjunction with drawings and Examples, the utility model is described in further detail, in accompanying drawing:

Fig. 1 a, Fig. 1 b, Fig. 1 c are the miniature photovoltaic grid-connected inverter circuit theory diagrams of application the utility model flyback converter leakage inductance energy absorption and feedback circuit.

Fig. 1 a is the utility model first embodiment

Fig. 1 b is the second embodiment of the present utility model

Fig. 1 c is the 3rd embodiment of the present utility model

Fig. 2 is the generation block diagram that the utility model absorbs feedback circuit clamper tube drive singal.

Fig. 3 is a switch periods, circuit of reversed excitation supervisor, the drive singal of clamper tube and the oscillogram of leakage inductance electric current and clamp capacitor voltage.

Embodiment

Below in conjunction with drawings and Examples, the utility model is described in further detail, but should not limit protection range of the present utility model with this.

Fig. 1 a is the first embodiment of the present utility model, and in figure, 100 circuit are that the leakage inductance energy that the utility model proposes absorbs and feedback circuit, by N-channel MOS FET clamper tube S _cwith clamp capacitor C _cform.The source electrode of clamper tube and circuit of reversed excitation are responsible for S _mdrain electrode be connected, the drain electrode of clamper tube and clamp capacitor C _cpositive pole be connected, clamp capacitor C _cnegative pole be connected with the ground of circuit of reversed excitation input.

Fig. 1 b is the second embodiment of the present utility model, and in figure, 101 circuit are that the leakage inductance energy that the utility model proposes absorbs and feedback circuit, by N-channel MOS FET clamper tube S _cwith clamp capacitor C _cform.The source electrode of clamper tube and circuit of reversed excitation are responsible for S _mdrain electrode be connected, the drain electrode of clamper tube and clamp capacitor C _cpositive pole be connected, clamp capacitor C _cnegative pole be connected with the PV+ of circuit of reversed excitation input, this mode is compared the first embodiment and is reduced clamp capacitor C _cwithstand voltage.

Fig. 1 c is the 3rd embodiment of the present utility model, and in figure, 102 circuit are that the leakage inductance energy that the utility model proposes absorbs and feedback circuit, by P channel mosfet clamper tube S _cwith clamp capacitor C _cform.The source electrode of clamper tube is connected with the ground of circuit of reversed excitation input, the drain electrode of clamper tube and clamp capacitor C _cnegative pole be connected, clamp capacitor C _cpositive pole and circuit of reversed excitation supervisor S _mdrain electrode be connected.This mode compares the driving that first, second embodiment simplifies clamper tube

Fig. 2 has set forth the control method of leakage inductance energy absorption and the feedback circuit clamper tube that the utility model proposes.

Have no progeny in circuit of reversed excitation supervisor pass, clamper tube S _copen a period of time T _c, service time T _cmuch smaller than the turn-off time of supervisor.During this period of time, clamp capacitor is by clamper tube S _ccomplete absorption and the release of leakage inductance energy, the leakage inductance energy be recovered to all is discharged in main power circuit.This control method can be realized easily by analog circuit or digital circuit.

Fig. 3 gives supervisor and the drive singal of clamper tube, and leakage inductance electric current and clamp capacitor voltage waveform.The principle of leakage inductance energy feedback is exactly the resonance of clamp capacitor and leakage inductance, the ON time T of clamper tube _cbe half harmonic period, now just in time resonance is to zero for leakage inductance energy, and the leakage inductance energy absorbed by clamp capacitor is all discharged in main power circuit.

The foregoing is only preferred embodiment of the present utility model, be not limited to the utility model, for a person skilled in the art, the utility model can have various modifications and variations.All within spirit of the present utility model and principle, any amendment done, equivalent replacement, improves, all should be included within right of the present utility model.

Claims (3)

1. flyback transformer leakage inductance energy absorption feedback circuit, is characterized in that: absorb and feedback circuit integrated, be only made up of a clamper tube and a clamp capacitor; Clamper tube source electrode is connected with flyback supervisor drain electrode, and clamper tube drain electrode is connected with clamp capacitor, the passage that clamper tube provides leakage inductance energy to absorb and discharge, and clamp capacitor is then the medium that leakage inductance energy temporarily stores.

2. flyback transformer leakage inductance energy absorption feedback circuit as claimed in claim 1, is characterized in that: described clamper tube adopts N-channel MOS FET, or P channel mosfet.

3. the control method of flyback transformer leakage inductance energy absorption feedback circuit as claimed in claim 1, is characterized in that: described clamper tube and the conducting of supervisor's incomplementarity; Clamper tube is only had no progeny in supervisor pass ON time T _c, T _cmuch smaller than the turn-off time of supervisor; The ON time T of clamper tube _ccomputing formula be:

Wherein L _kfor leakage inductance inductance value, C _cfor clamp capacitor capacitance.