CN103944402B - The control method of the independent-excited push-pull converter of a kind of ZVT and changer - Google Patents

Abstract

The present invention discloses control method and the independent-excited push-pull converter of the independent-excited push-pull converter of a kind of ZVT, the Dead Time of two main power MOS pipes driving signals of a controller output is regulated according to the size of coupling transformer exciting curent in push-pull converter, in Dead Time, in push-pull converter one is needed the electric charge release stored from the main power MOS pipe parasitic capacitance of the switching-on state of off state complete by the energy utilizing described coupling transformer exciting curent, after the internal anti-parallel diodes conducting of this main power MOS pipe, described controller output drive signal controls the conducting of this main power MOS pipe, realize ZVT.Make the condition realizing former limit metal-oxide-semiconductor ZVT unrelated with the size of the scope of input voltage, output loading, it is possible to ensure that circuit realizes ZVT in full-load range.

Description

The control method of the independent-excited push-pull converter of a kind of ZVT and changer

Technical field

The present invention relates to a kind of push-pull converter, push away particularly to a kind of independent-excited with ZVT characteristic Draw changer, additionally relate to the control method of the independent-excited push-pull converter of ZVT.

Background technology

Push-pull converter circuit structure is simple, and drive circuit is without isolation, and during circuit work, transformator is two-way swashs Magnetic, the utilization rate of magnetic core is high, and the most this changer has the advantage that volume is little, efficiency is high and dynamic response is good, But because the voltage stress of changer operationally switching tube is 2 times of input voltage, so this changer is normal Apply the middle large-power occasions in low pressure input.

Push-pull converter circuit topology is as it is shown in figure 1, two switching tube Q1 and Q2 in circuit are respectively with one The individual armature winding two ends with centre tapped isolating transformer are connected, and transformer secondary is by commutation diode D1 and D2, energy storage inductor L1 and filter capacitor C1 form full-wave rectifier filter circuit, at some output electricity Pressing without regulation or the application scenario the highest to output voltage required precision, the inductance L1 in circuit can save Slightly, in this case, push-pull converter mainly realizes the most defeated by the way of regulation transformer turn ratio Enter output voltage conversion.

Push-pull converter, during work, is realized wheel conductance by driving Signal-controlled switch pipe Q1 and Q2 Logical, during switching tube Q1 conducting, input voltage vin is added in primary side winding Np1 of transformator by switching tube Q1 On, due to the effect of transformator, the voltage at the switching tube Q2 two ends being now in off state is 2Vin, In the time of switching tube Q1 conducting, input power Vin passes through transformer primary side winding Np1, vice-side winding Ns2 Energy is provided to load.In like manner, when switching tube Q1 switches to off state from conducting state, switching tube Q2 Beginning to turn on, now input power Vin is that load carries by transformer primary side winding Np2, vice-side winding Ns1 Energizing quantity.Situation about simultaneously turning on occurs during switching in working order in order to avoid switching tube Q1 and Q2, Require to arrange a certain size " Dead Time " during the control of switching tube Q1 and Q2.So-called " dead band Time ", it is in a switch periods, drives Signal-controlled switch pipe Q1 and Q2 to be simultaneously in off state Persistent period.Power MOSFET mainly drives the dutycycle size of signal to realize by regulation.

Efficiency and volume are two the important indexs judging Switching Power Supply performance quality, design in Switching Power Supply In, improve switching frequency be the important means realizing Switching Power Supply miniaturization, but high frequency will make transformator or The core loss of inductance increases, and makes the switching loss of power switch pipe strengthen, and also will bring more electromagnetism simultaneously Problem in terms of interference.Soft switch technique is to make one of power inverter important technology being able to high frequency, its profit With electric capacity and the resonance principle of inductance, make the electric current (or voltage) of switching device by sinusoidal or close to sine rule Rule change, when current over-zero, makes device turn off, it is achieved zero-current switching (ZCS, Zero Current Switching), or when voltage zero-cross, make device open-minded, it is achieved no-voltage opens (ZVS, Zero Voltagt Switching), thus reduce switching loss.

Publication number 103078514A, on May 1 2013 publication date, entitled " it is humorous that one has multiplication of voltage The push-pull converter of ability of shaking " propose a kind of secondary commutation diode there is recommending of zero-current switching characteristic Formula changer, circuit structure is as shown in Figure 2.The former rim portion of this circuit is basic with conventional push-pull converter Identical, transformer secondary then uses the mode that simplex winding exports, and current rectifying and wave filtering circuit flows rectification again by using Mode realize.Meanwhile, in order to allow circuit have Sofe Switch characteristic, the size of times voltage capacitance Cs needs root Properly choose according to the equivalent leakage inductance of transformer secondary winding.The shortcoming of this implementation is taking of electric capacity Cs Being worth closely related with the equivalent leakage inductance of transformer secondary winding, during manufacturing, transformer primary is secondary The leakage inductance precision on limit is difficult to control to, and therefore during batch production, the Sofe Switch characteristic of circuit will be difficult to ensure that.With Time, in order to realize zero-current switching, main power circuit need to add one have larger current tolerance times Voltage capacitance, makes the cost of circuit and volume all increased.

Publication number 1592061, March 9 2005 publication date, entitled " push-pull converter and use In power supply unit, the method for uninterrupted power supply system " propose a kind of primary side switch pipe and there is no-voltage open Closing the push-pull converter of characteristic, circuit structure is as shown in Figure 3.The circuit structure of this implementation is with common Push-pull converter essentially identical, the no-voltage of primary side switch pipe open mainly by change drive signal The mode of dutycycle size realizes.In the moment of two the master power switch pipe duty switchings in former limit, profit By the size of transformer excitation electric current, needing to post from off state switching-on state of switch pipe Raw electric capacity discharges, and realizes ZVT with this.The control method of this scheme is: at input voltage Relatively low or in the case of being output as heavy duty, it is close that push-pull converter need to be operated in driving signal dutyfactor Under conditions of 0.5；And higher at input voltage or in the case of being output as underloading, push-pull converter work Making in PWM mode, the driving signal dutyfactor now controlling two switching tubes in former limit is obviously reduced, this Under mode of operation, circuit cannot realize ZVT.The shortcoming of this implementation is that circuit realiration no-voltage is opened The condition closed is relevant with the size of output loading all the time, and higher at input voltage or be output as the bar of underloading Under part, this control mode will be unable to realize ZVT, especially under conditions of high frequency, it will brings Bigger switching loss.

Summary of the invention

For prior art exist technological deficiency, it is an object of the invention to provide a kind of ZVT it swash The control method of formula push-pull converter, makes the condition realizing former limit metal-oxide-semiconductor ZVT and input voltage Scope, output loading size unrelated, it is possible to ensure circuit in full-load range, realize ZVT.

Further object is that the independent-excited push-pull converter that above-mentioned control method is provided.

To achieve these goals, first purpose of the present invention can be realized by following technical measures: one Plant the control method of the independent-excited push-pull converter of ZVT, according to transformer excitation electricity in push-pull converter The size of stream regulates the Dead Time of two driving signals of a controller output, in Dead Time, profit Switch to lead from off state by one of them needs of push-pull converter with the energy of described transformer excitation electric current The electric charge release that the main power MOS pipe parasitic capacitance of logical state stores is complete, when in this main power MOS pipe After portion's anti-parallel diodes conducting, described controller output drive signal controls this main power MOS pipe leads Logical, it is achieved ZVT.

The dead time range Tdt of two main power MOS pipes driving signals of controller of the present invention control:

$\frac{8\·L_m\·C_s}{T_{\mathrm{on}\max }}\≤\mathrm{Tdt}\≤\sqrt{8\·L_m\·C_s}$

T_onmaxBeing the maximum ON time of main power MOS pipe, the former limit that Lm is expressed as coupling transformer is excitatory Inductance value, C_sIt it is the parasitic capacitance size of main power MOS pipe.Two main power MOS pipes of push-pull circuit Parameter is just as.

Another object of the present invention can be realized by technical measures once: a kind of use described control method The independent-excited push-pull converter of ZVT, including:

One transformator, it comprises and has centre tapped first primary side winding and the second primary side winding and at least One vice-side winding；

One input voltage source, its positive pole is connected with the centre cap of transformer primary side winding, and negative pole is connected to ground；

First main power MOS pipe, its drain electrode is connected with one end of transformator the first primary side winding, and source electrode connects To ground；

Second main power MOS pipe, its drain electrode is connected with one end of transformator the second primary side winding, and source electrode connects To ground；

The first described main power MOS pipe and the second main power MOS pipe each have a parasitic capacitance and The diode of individual reverse parallel connection；

One rectification filtering unit, it is connected, by secondary with the first vice-side winding and second vice-side winding of transformator The alternating voltage that winding produces is converted to DC voltage provides energy for output loading；

Characterized by further comprising the controller for realizing the main power MOS pipe ZVT in two, former limit, Described controller has the first driving signal output port and second and drives signal output port, and first drives signal The grid of output port and the first main power MOS pipe connects, and second drives signal output port and the second main merit The grid of rate metal-oxide-semiconductor connects；

Regulate two of the output of controller according to the size of transformer excitation electric current in push-pull converter to drive The Dead Time of dynamic signal, in Dead Time, utilizes the energy of described transformer excitation electric current will recommend conversion The electricity that one of them needs of device store from the main power MOS pipe parasitic capacitance of the switching-on state of off state Lotus release is complete, and after the internal anti-parallel diodes conducting of this main power MOS pipe, described controller is defeated Go out to drive signal to control the conducting of this main power MOS pipe, it is achieved ZVT.

The dead time range Tdt of two driving signals of described controller output:

$\frac{8\·L_m\·C_s}{T_{\mathrm{on}\max }}\≤\mathrm{Tdt}\≤\sqrt{8\·L_m\·C_s}$

Preferential, described controller drives signal output port to export the driving letter of two phase 180 ° Number, and two dutycycles driving signal are equal in magnitude.

Preferential, described rectification filtering unit is a full-wave rectifying circuit, and it is secondary that described transformator includes first Limit winding and the second vice-side winding, the first vice-side winding and the second vice-side winding are exported by described full-wave rectifying circuit Alternating voltage be converted to DC voltage and provide energy for output loading.

Further, described full-wave rectifying circuit uses devices.

Preferential, described rectification filtering unit is a bridge rectifier, and described transformator comprises a secondary Winding, these vice-side winding two ends connect bridge rectifier.

Preferential, described rectification filtering unit is a current-doubling rectifier, and described transformator comprises a secondary Winding, these vice-side winding two ends connect current-doubling rectifier.

The beneficial effects of the present invention is: according to the size of transformer excitation electric current, drive letter by regulation two Number Dead Time realize the ZVT of former limit metal-oxide-semiconductor, in circuit without adding any device In the case of, only need to can be achieved with former limit metal-oxide-semiconductor ZVT, a side by specific Power MOSFET Face can reduce the volume of circuit, also reduces the totle drilling cost of circuit simultaneously.The exciting curent of transformator will not be with The change of output loading and change, the condition therefore realizing ZVT is unrelated with output loading, so energy Enough under full-load range, maintain higher conversion efficiency.

Accompanying drawing explanation

Fig. 1 is prior art push-pull converter circuit theory diagrams；

Fig. 2 is the push-pull converter circuit theory diagrams that prior art has multiplication of voltage resonant capacity；

Fig. 3 is the push-pull converter circuit theory that prior art primary side switch pipe has ZVT characteristic Figure；

Fig. 4 is first embodiment of the invention circuit theory diagrams；

Fig. 5 is the work wave that first embodiment of the invention circuit test results draws；

Fig. 6 is the work of circuit in the case of first embodiment of the invention drives signal Dead Time relatively big two Voltage waveform；

Fig. 7 is second embodiment of the invention circuit theory diagrams；

Fig. 8 is third embodiment of the invention circuit theory diagrams；

Fig. 9 is fourth embodiment of the invention circuit theory diagrams.

Detailed description of the invention

Fig. 4 is first embodiment of the invention circuit theory diagrams, as it can be seen, this circuit includes an input voltage Source Vin, its positive pole is connected with the primary side winding centre cap of transformator T1, and its negative pole is connected to ground；Also wrap Include the first main power MOS pipe Q11 and the second main power MOS pipe Q12, the first main merit connected with push pull mode The drain electrode of rate metal-oxide-semiconductor Q11 is connected with one end of transformator the first primary side winding, and source electrode is connected to ground；Second is main The drain electrode of power MOS pipe Q12 is connected with one end of transformator the second primary side winding, and source electrode is connected to ground；Q11 With the driving signal output port that the grid of Q12 connects controller respectively.The secondary of coupling transformer T1 is with complete Ripple current rectifying and wave filtering circuit is connected, and full-wave rectifier filter circuit is mainly by diode D11, D12 and filter capacitor Co is constituted, and resistance Ro is output loading.Controller noted above drives signal output port two phase of output The driving signal of 180 °, and two dutycycles driving signal are equal in magnitude.Signal is driven to may utilize able to programme Digital signal processing chip (DSP) or single-chip microcomputer draw, it is possible to by special power management IC (such as TL494 Or SG3525) draw.

Size according to transformer excitation electric current regulates the Dead Time of two driving signals of controller output It is limited in the range of formula regulation, in Dead Time, utilizes the energy of transformer excitation electric current by wherein one The electric charge that individual needs store from the main power MOS pipe parasitic capacitance of the switching-on state of off state releases Finishing, after metal-oxide-semiconductor internal anti-parallel diodes conducting, controller output drive signal controls this main merit Rate metal-oxide-semiconductor turns on, it is achieved ZVT.

In Fig. 4, electric capacity Cs11 and Cs12, diode Ds11 and Ds12 are metal-oxide-semiconductor Q11 and Q12 respectively Parasitic capacitance and body diode, Lk11, Lk12, Lk13, Lk14 be respectively winding Np11, Np12, Np13, The equivalent leakage inductance of self of Np14.Realize ZVT to allow circuit be easier to, can allow coupling transformation Between winding Np11 and Np12 of two, the former limit of device T1, coupling is preferably, two winding coupled of primary and secondary side Poor, less to reach Lk11, Lk12, and the purpose that Lk13 and Lk14 is relatively large, increase leakage inductance Lk13 Can realize by changing the winding method of transformator with the method for Lk14.

Fig. 5 is the work wave that first embodiment of the invention circuit test results draws, in figure, Vgs is for controlling The main power MOS pipe Q11 of control of device output and the driving voltage waveform signal of Q12 turn-on and turn-off, Vds1 With the running voltage that Vds2 is respectively main power MOS pipe Q1 and Q2 Drain-Source two ends in the course of the work Waveform, ID is secondary commutation diode D11 and D12 current waveform in the course of the work, and IQ is former limit master Power M0S pipe Q11 and Q12 current waveform in the course of the work.Below by the work introducing this circuit Process illustrates the operation principle utilizing transformer excitation electric current to realize former limit metal-oxide-semiconductor ZVT.

In t0～the t1 moment: before the instant t 0, the exciting curent of transformator reaches reverse maximum, i.e. Im(t0) =-Im, in the t0 moment, main power MOS pipe Q11 turn on, input voltage vin through primary side winding Np11, Leakage inductance Lk11, main power MOS pipe Q11 are to ground, owing to leakage inductance Lk11 is for the magnetizing inductance of former limit The least, therefore input voltage vin almost all is added in primary side winding Np11, this moment transformator forward Excitatory, the different name end of primary side winding Np11 is just, Same Name of Ends is negative, transformer principle can draw, becomes Depressor primary side winding Np12, the Same Name of Ends polarity of vice-side winding Ns11, Ns12 are negative, and different name end is just, The induced voltage of primary side winding Np12 is Vin, the input that voltage the is 2 times electricity of main power MOS pipe Q12 Pressing, i.e. 2Vin, secondary side diode D11 is reversely ended, D12 forward conduction, and vice-side winding Ns12 passes through two Pole pipe D12, leakage inductance Lk14 provide energy to load.In the t1 moment, main power MOS pipe Q11 turns off, The t0-t1 stage, the exciting curent Im(t of transformator) rise to forward maximum+Im from reverse maximum-Im.

The t1-t2 moment: main power MOS pipe Q11 and Q12 is in off state, when circuit enters dead band Between.In the t1 moment, main power MOS pipe Q11 turns off, and the exciting curent of transformator reaches forward maximum, I.e. Im(t1)=+ Im, if Dead Time is the shortest, it is believed that exciting curent keeps not in Dead Time Become, be equivalent to a constant-current source.Owing to inductive current can not suddenly change, now the polarity of primary side winding Np11 is turned over Turn, the Same Name of Ends of Np11 is just, different name end is negative, simultaneously primary side winding Np12, vice-side winding Ns11, The Same Name of Ends polarity of Ns12 is just also, different name end polarity is negative.Coupling transformer T1 degaussing in Dead Time, Primary side winding Np11 gives the parasitic capacitance Cs11 charging of main power MOS pipe Q11, and Np12 gives main merit simultaneously Rate metal-oxide-semiconductor Q12 parasitic capacitance Cs12 electric discharge because primary side winding Np11 of coupling transformer T1 with Preferably, therefore the size of current of the charging and discharging of Cs11, Cs12 is identical, and its electric current is transformation in Np12 coupling The half of device exciting curent.In the process, the drain source voltage Vds1 of Q11 starts linear rise from 0V, The drain source voltage Vds2 of Q12 is from the size linear decline of 2Vin.As two main power MOS pipe Q11 and When drain source voltage Vds1, Vds2 of Q12 reach Vin, primary side winding Np11 and the electricity at Np12 two ends Pressure is for 0V, and to maintain Vin constant for the voltage of Vds1 and Vds2 in theory, but because there being the existence of leakage inductance, Cs11, Cs12 may proceed to charging and discharging respectively.To the t2 moment, parasitic capacitance Cs12 is discharged to 0V, with The body diode Ds12 conducting of its parallel connection, the no-voltage of this moment Q12 is opened condition and is established.According to electric capacity The principle of constant-current charge (or electric discharge) can draw, allows Vds2 drop to the minimum time of 0V in the t1-t2 stage It is spaced apart:

$t_{12}=\frac{2\·V_{\mathrm{in}}\·C_s}{\frac{I_{m\max }}{2}}=\frac{4\·V_{\mathrm{in}}\·C_s}{I_{m\max }}$ Formula (1)

The driving of former limit main power MOS pipe ZVT is realized during wherein t12 is expressed as the embodiment of the present invention The trailing edge of signal 1 is to driving minimum Dead Time between the rising edge of signal 2, and Vin is the big of input voltage Little, Cs is the parasitic capacitance size of main power MOS pipe, is denoted as Cs11 in circuit theory diagrams shown in Fig. 4 And Cs12.Push-pull circuit usually requires that the metal-oxide-semiconductor using same parameter, and therefore two parasitic capacitances are the same. Im is the maximum exciting curent of transformator, and this electric current can represent by below equation:

$I_{m\max }=\frac{V_{\mathrm{in}}\·T_{\mathrm{on}\max }}{2\·L_m}$ Formula (2)

In above-mentioned expression formula, Tonmax is the maximum ON time of main power MOS pipe Q11, because of two main power The maximum ON time of metal-oxide-semiconductor is consistent, the size of Tonmax will according to transformer magnetizing inductance Lm, Magnetic core of transformer allows the maximum exciting curent Imsat passed through to determine, specifically can be according to formulaCalculate；Lm is expressed as the former limit magnetizing inductance amount of coupling transformer, according to more than The size that two computing formula can draw two driving signal minimum Dead Times is:

$t_{12}=\frac{8\·L_m\·C_s}{T_{\mathrm{on}\max }}$ Formula (3)

In the t2-t3 moment: in the t2 moment, junction capacity Cs12 of main power MOS pipe Q12 is discharged to 0V, body Diode Ds12 turns on, and the condition of ZVT is founded, meanwhile, and the electricity of vice-side winding Ns11 Pressure is more than output voltage, and secondary commutation diode D11 turns on, the demagnetizing current of transformator through leakage inductance Ls13, Commutation diode D11 provides energy to load, after secondary commutation diode D11 turns on, and vice-side winding Ns11 Being output voltage clamp, the voltage Vs11 at its two ends is it is believed that be equal to size Vo of output voltage.According to The operation principle of transformator is it is known that there is following relation in input voltage vin and output voltage Vo:

$\frac{\mathrm{Vin}}{\mathrm{Vo}}=\frac{\mathrm{Vp}11}{\mathrm{Vs}11}=\mathrm{Nps}$ Formula (4)

Wherein Nps is the turn ratio of primary side winding Np11 and vice-side winding Ns11, Vp11 and Vs11 is respectively For primary side winding Np11 and the voltage of vice-side winding Ns11.From above-mentioned relation it is recognised that in the t2-t3 moment In, primary side winding Np11 voltage swing is approximately Vin, because of the circle of transformer primary side winding Np11 and Np12 Number ratio is identical, and the size of the voltage Vp12 of primary side winding Np12 is also approximately at Vin, main power MOS pipe The drain source voltage Vds2 that drain source voltage Vds1 is 2Vin, Q12 of Q11 is 0V.Therefore, as long as ensureing Transformator also in degaussing, can realize former limit metal-oxide-semiconductor ZVT in Dead Time.Owing to former limit is leaked Lk11, Lk12 are relatively small compared with secondary leakage inductance Lk13, Lk14 in sense, therefore transformator during this Demagnetizing current major part all circulate on former limit, the body diode Ds12 of main power MOS pipe Q12 can be real Turn on the most reliably, it is ensured that next stage Q12, its drain source voltage of turn-on instant Vds2 was in minima.At t3 In the moment, main power MOS pipe Q12 turns on, and this stage terminates.

In the t3-t4 moment: in the t3 moment, it is open-minded that main power MOS pipe Q12 realizes no-voltage, and turn-on consumption is real Now minimizing, now input voltage arrives through primary side winding Np12, leakage inductance Lk12, main power MOS pipe Q12 Ground, transformator inverse-exciting, vice-side winding Ns11 passes through leakage inductance Lk13 and commutation diode D11 to defeated Going out load and provide energy, to the t4 moment, transformer excitation electric current reaches reverse maximum, i.e. Im(t4)=-Im, Main power MOS pipe Q12 turns off.

After the t4 moment, by repeating the work process of next cycle, just repeat no more at this.

Can draw from above-mentioned analysis, the present invention realizes the condition of ZVT:

1, minimum ON time limits:

According to law of conservation of energy, the energy that transformator stores must be greater than or equal to two main power MOS The junction capacity of pipe stores the summation of energy, if ON time is the shortest, the energy that transformator stores is the least, extremely In district's time, the junction capacity electric charge of main power MOS pipe cannot discharge complete, it is impossible to reaches ZVT Condition, the minimum ON time of the most main power MOS pipe have to limit, its minimum ON time T_onminCan be calculated by below equation:

$\frac{1}{2}\·L_m\·{\mathrm{Im}}^2\≥\frac{1}{2}\·\mathrm{Cs}1\·{(2\·\mathrm{Vin})}^2+\frac{1}{2}\·\mathrm{Cs}2\·{(2\·\mathrm{Vin})}^2$ Formula (5)

$I_m=\frac{V_{\mathrm{in}}\·\frac{T_{\mathrm{on}\min }}{2}}{L_m}$ Formula (6)

Simultaneous two above formula can draw the minimum ON time of main power MOS pipe:

$T_{\mathrm{on}\min }=\sqrt{32\·L_m\·C_s}$ Formula (7)

2, maximum Dead Time limits:

From the work process in t2-t3 moment it is known that main power MOS pipe Q12 realizes ZVT Condition occurs in the demagnetization process of coupling transformer T1, but if the Dead Time of two driving signals is oversize, Transformator is allowed to have time enough to complete magnetic reset, the body diode of former limit main power MOS pipe Q12 Ds12, secondary commutation diode D11 can turn off naturally because demagnetizing current drops to zero, transformer secondary Winding Ns11 is no longer output voltage clamp, now input voltage source Vin will pass through primary side winding Np12, Leakage inductance Lk11 give main power MOS pipe Q12 parasitic capacitance Cs12 charging, its drain source voltage Vds2 from 0V begins to ramp up, and in like manner the drain source voltage Vds1 at Q11 two ends begins to decline from 2Vin, during this Generation is vibrated by circuit, and under the conditions of this, the work wave of circuit is as shown in Figure 6.

Therefore, under conditions of driving signal Dead Time longer two, circuit can not realize ZVT, In order to realize high efficiency power conversion, it is necessary to the maximum of transformer dead zone time is any limitation as.And according to volt Second equilibrium principle can show that transformator demagnetizing current is main merit from the time of forward maximum+Im release to zero The half of rate metal-oxide-semiconductor Q11 ON time, it may be assumed that

$T_{13}\≤\frac{T_{\mathrm{on}\min }}{2}=\sqrt{8\·L_m\·C_s}$ Formula (8)

Wherein T13 is expressed as the degaussing time of transformator, is also that controller of the present invention controls two driving letters simultaneously Number maximum Dead Time.

The present invention realizes ZVT by the Dead Time size controlling two the main power MOS pipes in former limit, The scope of two driving signal Dead Time sizes can be drawn, when circuit design, the most really by above analysis The maximum ON time of fixed two main power MOS pipes, it is possible to obtain controller and control two main power MOS The dead time range of pipe, represents with symbol Tdt at this:

$\frac{8\·L_m\·C_s}{T_{\mathrm{on}\max }}\≤\mathrm{Tdt}\≤\sqrt{8\·L_m\·C_s}$ Formula (9)

From expression formula it can be seen that the condition that realizes of the independent-excited push-pull circuit ZVT shown in Fig. 4 is with defeated Go out to load unrelated, as long as therefore ensureing that the Dead Time of two driving signals of controller output is in expression formula above Within the scope of, circuit just can realize ZVT in full-load range, makes circuit have higher turning Change efficiency.

Being second embodiment of the present invention circuit theory diagrams as shown in Figure 7, this embodiment is first embodiment Self-powered synchronous rectification scheme.As it can be seen, be with the difference of first embodiment, the rectification circuit of secondary is by In one embodiment, commutation diode D11 and D12 replaces with devices Q23 and Q24, synchronizes The drain electrode of rectifier tube Q23 is connected with the Same Name of Ends of the vice-side winding Ns21 of coupling transformer T2, and source electrode connects To the outfan of circuit, its grid is connected to the different name end of secondary another winding Ns22, the drain electrode of Q24 and coupling The Same Name of Ends of the vice-side winding Ns22 closing transformator T2 is connected, and source electrode is connected to outfan, and its grid connects Same Name of Ends to vice-side winding Ns21.Push-pull circuit self-powered synchronous rectification is the most conventional known technology, Owing to length is limited, its operation principle is not described in detail at this.Second embodiment of the invention secondary is adopted Mode with self-powered synchronous rectification can reduce the loss of rectifying part circuit, in conjunction with two described in first embodiment Drive the control method of signal Dead Time, it is possible to further improve the overall transformation efficiency of circuit.

The second main power MOS pipe in the former limit of embodiment realizes the same first embodiment of operation principle of ZVT, Just repeat no more at this.

Third embodiment of the present invention circuit theory diagrams as shown in Figure 8, as it can be seen, with first embodiment Difference is, the coupling transformer T3 secondary only one of which winding Ns31 of independent-excited push-pull circuit, with secondary around What group Ns31 two ends were connected is a bridge rectifier, and third embodiment of the invention secondary uses bridge-type whole Current circuit, in conjunction with the control method of two driving signal Dead Times described in first embodiment, it is possible to realization has relatively High conversion efficiency, meanwhile, transformer secondary is reduced to a winding, it is possible to preferably simplify transformator around Technique processed, reduces the man-hour of coiling transformator, thus improves production efficiency.

The 3rd main power MOS pipe in the former limit of embodiment realizes the same first embodiment of operation principle of ZVT, Just repeat no more at this.

Fourth embodiment of the present invention circuit theory diagrams as shown in Figure 9, as it can be seen, with first embodiment Difference is, the coupling transformer T4 secondary only one of which winding Ns41 of independent-excited push-pull circuit, with secondary around What group two ends were connected is a current-doubling rectifier, and four embodiment of the invention secondary uses and flows rectified current again Road, in conjunction with the control method of two driving signal Dead Times described in first embodiment, answering at low-voltage, high-current Being capable of higher conversion efficiency by occasion, transformer secondary is reduced to a winding simultaneously, it is possible to preferably Simplify the technique for coiling of transformator, reduce the man-hour of coiling transformator, thus improve production efficiency.

The 4th main power MOS pipe in the former limit of embodiment realizes the same first embodiment of operation principle of ZVT, Just repeat no more at this.

Below it is only the preferred embodiment of the present invention, it is noted that above-mentioned preferred implementation should not regard For limitation of the present invention, for those skilled in the art, in the essence without departing from the present invention In god and scope, it is also possible to making some improvements and modifications, these improvements and modifications also should be regarded as the guarantor of the present invention Protect scope, the most no longer repeat by embodiment, the model that protection scope of the present invention should be limited with claim Enclose and be as the criterion.

Claims (8)

1. the control method of the independent-excited push-pull converter of a ZVT, it is characterised in that:

The two of a controller output are regulated according to the size of coupling transformer exciting curent in push-pull converter Individual main power MOS pipe drives the Dead Time of signal, in Dead Time, utilizes described coupling transformer to swash The energy of magnetoelectricity stream is by the push-pull converter main power needed from the switching-on state of off state The electric charge release that metal-oxide-semiconductor parasitic capacitance stores is complete, when the internal anti-parallel diodes of this main power MOS pipe After conducting, described controller output drive signal controls the conducting of this main power MOS pipe, it is achieved no-voltage is opened Close；

The dead time range Tdt of two main power MOS pipes driving signals of described controller control:

$\frac{8\·L_m\·C_s}{T_{on\max }}\≤Tdt\≤\sqrt{8\·L_m\·C_s}$

Tonmax is the maximum ON time of main power MOS pipe, and Lm is expressed as the former limit of coupling transformer and swashs Magnetoelectricity sensibility reciprocal, Cs is the parasitic capacitance size of main power MOS pipe.

Control method the most according to claim 1, it is characterised in that: two described main power MOS The driving signal that pipe drives signal to be two phase 180 °, and two dutycycle size phases driving signal Deng.

3. use an independent-excited push-pull converter for the ZVT of control method described in claim 1, Including:

One transformator, it comprises and has centre tapped first primary side winding and the second primary side winding and at least One vice-side winding；

One input voltage source, its positive pole is connected with the centre cap of transformer primary side winding, and negative pole is connected to ground；

First main power MOS pipe, its drain electrode is connected with one end of transformator the first primary side winding, and source electrode connects To ground；

Second main power MOS pipe, its drain electrode is connected with one end of transformator the second primary side winding, and source electrode connects To ground；

The first described main power MOS pipe and the second main power MOS pipe each have a parasitic capacitance and The diode of individual reverse parallel connection；

One rectification filtering unit, it is connected with the vice-side winding of transformator, by the alternating voltage of vice-side winding generation Be converted to DC voltage and provide energy for output loading；

Characterized by further comprising the controller for realizing the main power MOS pipe ZVT in two, former limit, Described controller has the first driving signal output port and second and drives signal output port, and first drives signal The grid of output port and the first main power MOS pipe connects, and second drives signal output port and the second main merit The grid of rate metal-oxide-semiconductor connects；

The two of a controller output are regulated according to the size of coupling transformer exciting curent in push-pull converter The Dead Time of individual driving signal, in Dead Time, the energy utilizing described coupling transformer exciting curent will One of them main power MOS pipe parasitic capacitance needing to switch to conducting state from off state of push-pull converter The electric charge release stored is complete, after the internal anti-parallel diodes conducting of this main power MOS pipe, described Controller output drive signal controls the conducting of this main power MOS pipe, it is achieved ZVT；

Two dead time range Tdt driving signals of described controller output:

$\frac{8\·L_m\·C_s}{T_{on\max }}\≤Tdt\≤\sqrt{8\·L_m\·C_s}$

Tonmax is the maximum ON time of main power MOS pipe, and Lm is expressed as the former limit of coupling transformer and swashs Magnetoelectricity sensibility reciprocal, Cs is the parasitic capacitance size of main power MOS pipe.

Independent-excited push-pull converter the most according to claim 3, it is characterised in that: described controller Signal output port is driven to export the driving signal of two phase 180 °, and two duties driving signal Ratio is equal in magnitude.

Independent-excited push-pull converter the most according to claim 3, it is characterised in that: described rectification filter Ripple unit is a full-wave rectifying circuit, and described transformator includes the first vice-side winding and the second vice-side winding, institute State full-wave rectifying circuit and the alternating voltage that the first vice-side winding and the second vice-side winding export is converted to unidirectional current Press and provide energy for output loading.

Independent-excited push-pull converter the most according to claim 5, it is characterised in that: described all wave rectification Circuit use synchronous rectification mode carry out rectification.

Independent-excited push-pull converter the most according to claim 3, it is characterised in that: described rectification filter Ripple unit is a bridge rectifier, and described transformator comprises a vice-side winding, and these vice-side winding two ends connect Bridge rectifier.

Independent-excited push-pull converter the most according to claim 3, it is characterised in that: described rectification filter Ripple unit is a current-doubling rectifier, and described transformator comprises a vice-side winding, and these vice-side winding two ends connect Current-doubling rectifier.