CN210469122U - Double-ring full-resonance type soft switching converter - Google Patents
Double-ring full-resonance type soft switching converter Download PDFInfo
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- CN210469122U CN210469122U CN201920191239.XU CN201920191239U CN210469122U CN 210469122 U CN210469122 U CN 210469122U CN 201920191239 U CN201920191239 U CN 201920191239U CN 210469122 U CN210469122 U CN 210469122U
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Abstract
The utility model discloses a soft switching converter of dicyclo full resonance type, the dicyclo indicates the LLC multiresonance of leading resonance LrLBCr title, and the LC single resonance of supplementary half-bridge resonance Lo (C3+ C4), LLC leading resonance circuit comprises leading resonance LB, Lr, Cr, and all four switching device of full-bridge are all shunt capacitance ware, realize the whole resonance of four pipes of full-bridge. The utility model discloses the converter can export bigger power under same transformer, inductance and electric capacity resonance specification, and the power tube realizes that zero voltage opens, and zero current is turn-offed, and electric capacity C3, C4, C5, C6 and power tube Q1, Q2, Q3, Q4 are parallelly connected respectively, have fully reduced the voltage change rate of dv/dt, and efficiency improvement and electromagnetic radiation reduce.
Description
Technical Field
The utility model relates to a switching power supply converter technical field especially relates to a dicyclo full resonant mode soft switching converter.
Background
In the field of power electronics, one type of electric energy is converted into another type of electric energy, such as direct current to direct current, and also alternating current to direct current, and direct current to alternating current. The input direct current voltage is converted into another direct current voltage value, the size of the transformer is reduced by improving the switching frequency, the voltage stabilizing function is realized, the conversion efficiency is improved, the equipment is small, the cost is low, the transformer is small and light, and the power density is improved. For example, industrial frequency transformers are quite large in size and weight, the output voltage changes along with the change of the input voltage, the higher the frequency, the smaller the size and the lighter the weight, and the power electronic technology revolution is also the revolution of the converter technology.
In the switching converter, the current of a power tube which plays a role in adjustment is tried to change according to a sine wave rule, the switching tube is switched on and off when the voltage is zero, and the switching tube is switched on and off when the current is zero, so that the efficiency of the converter reaches the highest limit point, the height change of the output voltage cannot be adjusted, the conversion with the lowest loss is achieved as far as possible by changing the working principle and structure, the transformer can be used more efficiently and at higher frequency, and the power density of the converter is also improved.
Compared with the traditional converter with hard switch, the converter using the soft switch technology has the advantages of high conversion efficiency, small electromagnetic interference and capability of improving power density, thereby being widely applied. The occupied ratio is higher and higher, and research and application of new soft switching technology become the key and mainstream in the field of switching converters.
From the development history and milestones of the converter, the earliest technology, which can also be called as a generation technology, such as the half bridge of fig. 2 and the full bridge of fig. 3, is completely hard switching, i.e., the on and off of high voltage and large current, and each single transistor is also provided with an illustrated RC absorber, R has relatively large loss, low conversion efficiency, low switching frequency, large equipment and high cost, and belongs to low-end technology content. The second generation should belong to a phase shift circuit, or a limited bipolar circuit, also called pseudo phase shift mode. Referring to fig. 4, the phase shift type, the transistors Q1 and Q2, the transistors Q3 and Q4 are all shifted by almost full pulse width to form duty modulation. Because the pulse width is full all the time, the zero voltage conduction of the other tube can be generated by the inductive exciting current of the switch tube, an RC absorber is not needed at all, the transistor Q3 and the transistor Q4 are over front arms, the ZVS (zero voltage) conduction is realized, and the ZVS (zero current) disconnection is realized by the hysteresis arms of the transistor Q1 and the transistor Q2. The transistor Q3 and the transistor Q4 are arranged on the leading arm and a small capacitor, so that the loss of large-current turn-off can be reduced, but the dead time is short and fixed, the occupation ratio of light load and no load is very small, namely the conduction time is very short, the current is very small, the processes of charging and discharging the capacitor C3 and the capacitor C4 cannot be performed, the conduction loses ZVS (zero voltage), the capacitor can be absorbed by a tube to generate loss, and the using frequency is higher than that of a hard switch, but not higher.
In order to solve the deficiency, pseudo phase shift, i.e. limited bipolar circuit, is adopted, such as transistor Q1 and transistor Q2, the full pulse width is fixed on-time, the transistor Q3 and the transistor Q4 adopt variable pulse width PWM, the PWM is high under large current, the dead time is short, but the full charge and the discharge of the capacitor C3 and the capacitor C4 can be realized in a short time, under light load and no load, the PWM is low, the conduction time of the transistor Q3 and the transistor Q4 is very short, but the dead time is very large, because the fixed conduction time of the transistor Q1 and the transistor Q2 is not changed, the circuit is always in a conduction state, and a little air gap is left in the transformer, so that the primary inductance is reduced, the exciting current is increased, and therefore, due to the fact that sufficient time is provided for charging and discharging the capacitor C3 and the capacitor C4, the turn-off loss of the transistor Q3 and the transistor Q4 can be reduced more by increasing the capacitance.
Since the output passes through the rectifier diode and then is connected with the inductor of the L0 in series, the L0 is in inductive freewheeling, so that the hard switching process of the diode D1 and the diode D2 has reverse recovery time, and the loss of the rectifier diode is large. Therefore, the second generation is called edge-resonant soft switch regardless of the phase shift circuit or the limited bipolar circuit, but actually, it still shows hard switching characteristics. The soft component and effect are rather limited.
Then, the third generation LLC multi-resonance soft switch is formed by the inductor LB, the inductor Lr, and the capacitor Cr, as shown in fig. 5. When the switching frequency is operated at the resonance frequency, i.e.
In this case, the inductive reactance Lr is equal to the capacitive reactance Cr, the reactance value of the resonance is zero, the state of the sine wave current is shown in fig. 6, ir is the resonance current, iL is the resonance currentBIs composed of LBThe inductance generates an excitation current. The output voltage and load power are adjusted by changing the frequency to produce an inductive voltage division, e.g. reactance Xz, inductive reactance XL, capacitive reactance
The frequency increases, XL increases, Xc decreases, Xz increases, and the inductance L increases with increasing frequencyBAlso, the value of (d) is increased, resulting in a shorter time of the exciting current iLBBecome smaller so that LBThe value of (A) is not suitable for large or small, and L is generallyBAs the load power is further reduced, a higher frequency is required, the on-time is also reduced, the exciting current is further reduced, the transistor Q1 and the transistor Q2 lose the zero-voltage on-condition and enter capacitive turn-on, and the capacitor energy Wc is 2 × 1/2CU2f, f are further increased to proportionally increase Wc, so that the frequency range needs to be controlled, such as entering frequency conversion and generating variable pulse width at the same time, until the duty ratio at the highest frequency, such as three times of the resonant frequency, is zero. Or alternatively, intermittent oscillations are formed, the average frequency is limited and not very high. The inductive reactance of the inductor LB also changes with the frequency, and when the frequency is low, the output power is large, but the superimposed iLBThe current is also relatively large, causing the loss of the transistor Q1 and the transistor Q2 switching tube and the L of the parallel inductorBThe loss and the loss of the resonant series inductor Lr are both larger, when the output voltage and the power are reduced, the loss of the switch tube caused by capacitive absorption is large due to the loss of ZVS (zero voltage) opening, and the loss comes from the junction capacitance and the parallel connection of the power switch tubeThe sum of the containers.
That is, there is a certain contradiction between the fact that when the frequency is low, the current loss is large because the exciting current is superposed to form the non-conversion power, and when the frequency is high, 1/2 × 2Cu is needed2The value of f is increased, but the exciting current is reduced, and on the contrary, the efficiency is highest only when the exciting current works at the resonance frequency point, and once the deviation is larger, the conversion efficiency is greatly reduced no matter at higher frequency or lower frequency. The output rectifier diode is not connected with an inductor for filtering in series, but is directly filtered by a capacitor, and belongs to zero on-off, so that the loss is relatively low. The LLC multi-resonant converter is a third-generation technology, and the efficiency and the frequency of the LLC multi-resonant converter are higher than those of the second-generation phase shift and limited bipolarity.
In a fourth generation quasi-resonant soft switching converter, as shown in fig. 7, a capacitor C1+ a capacitor C2 are resonant capacitors, and are replaced by a capacitor Cr. The principle of the circuit is that the highest frequency is designed at the resonant frequency of an inductor Lr and a capacitor Cr, the switching frequency is always lower than the resonant frequency or is up to the resonant frequency, the half-cycle conduction time is set to be Ton, a mode of fixing pulse width and variable frequency, namely PFM, is adopted, and the resonant frequency is set to be fTThe switching frequency is fo, when fo is 0.6fT～fTIn between, full duty cycle, and below 0.6fTWhen the frequency of the circuit is lowered, the circuit is completely PFM, and the circuit current always works in a sine wave current state due to the clamping action of the diode D1 and the diode D2, namely zero current conduction and zero current disconnection, so that a double-zero system is called as a quasi-character, namely a quasi-resonance soft switch, and once the working frequency is lowered continuously, the working frequency is 0.6fTHereinafter, PFM is performed with the same duty ratio (referred to as PFM duty ratio), and the presence of dead time causes loss of the zero-voltage conduction condition despite the zero-current conduction and off relationship, so that the junction capacitance is absorbed by the switching tube and loss occurs, and the value Pw of this output power becomes 2 × 1/2CU2f, proportional relation with f, the frequency reduces the output power and reduces, so change the range of the frequency very big, if in order to limit the frequency range, when the turn-on period is less than the resonance period, enter the heavy current and turn off, lose the zero current and turn off.
In another converter, as shown in fig. 9, a two-stage converter is adopted, one stage is fixed in frequency, and the resonant frequency of the inductor Lr and the capacitor Cr is designed to be a switching frequency. The high-voltage and low-voltage Buck converter is characterized in that the zero-current conduction and the zero-current turn-off of the complete sine wave current are performed at the first stage, the efficiency is highest, HV + and HVo are amplitude-modulated, the magnitude of the amplitude determines the magnitude of output voltage, another Buck, namely a Buck circuit, is added, the Buck converter is composed of an inductor L0, a transistor Q3 and a diode D1, but a transistor Q3 switching tube works on and off of high voltage and high current, and large loss exists. The overall efficiency is still very high due to the highest conversion efficiency between the amplitude modulated voltages HV + and HVo. This method is also commonly used in practice, but how to improve the dynamic response speed is also a circuit principle and a control method.
SUMMERY OF THE UTILITY MODEL
In order to overcome the defects of the prior art, the utility model provides a double-ring full-resonance type soft switching converter, which utilizes two generations, three generations and four generations respectively in a long composite way, and generates a new topological structure circuit principle and a working mode.
In order to solve the technical problem, the utility model provides a following technical scheme: a double-ring full-resonance type soft switching converter comprises a limited bipolar LLC full-bridge main resonance circuit and an auxiliary resonance half-bridge, namely an LC auxiliary resonance circuit, and realizes full-soft switching of full-bridge four tubes, and is characterized in that double resonance of the LLC full-bridge main resonance circuit and the LC auxiliary resonance circuit generates double soft switching, namely zero-voltage switching-on and zero-current switching-off, so that a very tiny conversion process with little loss of a power switch tube is realized, the conversion efficiency is greatly improved, the switching frequency can be improved, and a high-efficiency miniaturized converter is realized; the LLC full-bridge main resonance circuit is composed of a main resonance inductor LB, an inductor Lr and a capacitor Cr, and is controlled in a limited bipolar full-bridge circuit structure mode, the transistor Q3 and the transistor Q4 are always turned off in advance of the transistor Q1 and the transistor Q2, the transistor Q3 and the transistor Q4 are subjected to pulse width modulation PWM, and excitation current generated by a series loop of the inductor LB, the inductor Lr and the capacitor Cr ensures that the capacitor C6 and the capacitor C5 which are connected in parallel with the transistor Q3 and the transistor Q4 are fully charged and fully discharged, so that zero voltage is generated for switching on, the larger the capacitors of the capacitor C5 and the capacitor C6 are, the smaller the turn-off loss of the transistor Q3 and the transistor Q4 is, but the turn-off loss cannot be; the transistor Q1 and the transistor Q2 are fixed in pulse width and are also connected with the capacitor C3 and the capacitor C4 in parallel, half-bridge resonance is adopted, the capacitor C1 and the capacitor C2 are connected in series to divide voltage into half of input voltage, the inductor L0 generates exciting current in the on half-cycle time, after the transistor Q1 and the transistor Q2 are turned off, the inductor L0 generates resonance with the capacitor C3+ the capacitor C4, the capacitor C3 and the capacitor C4 which are connected with the transistor Q1 and the transistor Q2 in parallel are fully charged or fully discharged, zero voltage is generated to be turned on, and the larger the capacitors C3 and the C4 are, the smaller the turn-off loss is but the larger the turn-off loss is; all four switch devices of the full bridge are connected with the capacitor in parallel, after the turn-off time (toff) is formed, the waveform of a VDS (very high voltage digital subscriber line) of a switch tube such as an MOSFET (metal-oxide-semiconductor field effect transistor) is trapezoidal, the dv/dt change rate is low, the VDS is in a quite low voltage state in the time from the large current to zero when the switch tube is turned off, the loss coefficient P is I multiplied by V, the change process loss is transferred to the capacitor for absorption, the maximum characteristic of the topological technology is achieved, the characteristic of perfect combination is achieved through the technical characteristic of limited bipolarity, a particularly large effect is achieved, the loss in the dynamic process of switching of the switch is enabled to be small enough, the switching frequency is further improved, compared with the common technology, on the premise that the size of the same size of a radiator of the switch tube is the same as that of a transformer, higher output power can be, thereby realizing high efficiency, low cost and miniaturization.
A double-loop full-resonance type soft switching converter comprises an LLC full-bridge main resonance circuit and an LC auxiliary resonance circuit which are limited and bipolar, and is characterized in that the LLC full-bridge main resonance circuit is composed of a main resonance inductor LB, an inductor Lr and a capacitor Cr, all four switching devices of a full bridge are connected in parallel with a capacitor, the positive electrode of an input voltage is connected with one end of a capacitor C1, one end of a capacitor C1 is connected with the collector of a transistor Q1, the other end of the capacitor C1 is connected with one end of a capacitor C2, one end of a capacitor C2 is connected with one end of an inductor L0, one end of an inductor L0 is connected with the emitter of a transistor Q1, the collector of a transistor Q1 is connected with one end of a capacitor C3, one end of a capacitor C3 is connected with the collector of a transistor Q4, the collector of a transistor Q4 is connected with one end of a capacitor C5, the emitter of a transistor Q1 is connected with the collector, the other end of the capacitor C3 is connected with one end of a capacitor C4, one end of a capacitor C4 is connected with one end of an inductor LB, the inductor LB is connected with the input end of the transformer B in parallel, the other end of the inductor LB is connected with one end of an inductor Lr, the other end of the inductor Lr is connected with one end of a capacitor Cr, the other end of the capacitor Cr is connected with the emitter of a transistor Q4, the emitter of a transistor Q4 is connected with the collector of a transistor Q3, the collector of a transistor Q3 is connected with the other end of a capacitor C5, the other end of a capacitor C5 is connected with one end of a capacitor C6, one end of a capacitor C6 is connected with the emitter of a transistor Q3, the emitter of a transistor Q3 is connected with the other end of a capacitor C4, the other end of a capacitor C4 is connected with the emitter of a transistor Q2, the emitter of a transistor Q2 is connected with the other end of a capacitor C2, the other end, the cathodes of the diode D1 and the diode D2 are connected to the anode of the polarity capacitor E, which is connected in parallel with the load. As an optimized technical scheme of the utility model, soft switching converter not only has inductance LB, inductance Lr, electric capacity Cr of main resonance, and supplementary resonance inductance L0 (electric capacity C3+ electric capacity C4) in addition, LLC + LC mode promptly to the characteristics that combine together with limited bipolar circuit technical characteristic are perfect to combine together, thereby improved the technique and the performance of converter greatly.
As a preferred embodiment of the present invention, the output voltage is determined by using the primary-secondary turn ratio of the transformer, and the transistor Q1, the transistor Q2, the transistor Q3, and the transistor Q4 may be power MOSFETs, insulated gate bipolar transistors IGBTs, or bipolar transistors BJTs.
As a preferred technical solution of the present invention, the inductor LB connected in parallel to the primary side of the transformer does not exist alone, but the magnitude of the LB value is determined by the magnitude of the air gap left by the transformer.
As an optimized technical solution of the present invention, the leakage inductance of the transformer is also a part of the series resonance inductor Lr, the transformer winding structure is changed, the leakage inductance is increased, or the leakage inductance is relatively large because of low output voltage, the resonance inductance Lr can be directly replaced by the leakage inductance of the transformer, and the transformer core has an air gap, that is, the inductance LB and the inductance Lr are concentrated inside the transformer to form the transformer, and the LB inductance and the Lr inductance are combined together and still are LLC.
As a preferred embodiment of the present invention, under any duty ratio of the transistor Q3 and the transistor Q4, the value of the inductor LB required for zero voltage conduction can be satisfied, and similarly, the transistor Q1 and the transistor Q2 are duty ratios with fixed pulse widths as long as the value of the inductor L0 under zero voltage conduction of the transistor Q1 and the transistor Q2 is satisfied.
As a preferred technical scheme of the utility model, switch operating frequency can be fixed frequency, also can be the mode of frequency conversion, no matter be higher than resonant frequency, still be less than resonant frequency.
Compared with the prior art, the utility model discloses the beneficial effect that can reach is: the utility model discloses soft switching converter adopts limited bipolarity topological structure principle, because the parallel capacitance of power switch tube device is bigger, and the softened is effectual, and the interchange dynamic loss of conversion process is very little, simultaneously, has slowed down the rising and the fall time curve of switch tube voltage, is the orbit of trapezoidal wave according to this curve, and the loss shifts the absorption and has reduced greatly, has fully reduced the switching loss of switch tube. And EMI reduces, and circuit operating system is stable easily, and the reliability has also improved, not only great improvement efficiency, simultaneously, improvement frequency that can be great can realize the miniaturization of equipment, also the cost is reduced. The transformer can output larger power under the same transformer size and specification of the same frequency, and the loss of the power tube of the switching device is greatly reduced, so that the size of a required radiator is reduced, the switching frequency can be further improved, the size of the transformer is reduced, the miniaturization and the cost reduction of equipment are realized, and the power density of the converter is also improved.
Drawings
Fig. 1 is a schematic diagram of a double-resonance type full-soft switching converter of the present invention;
FIG. 2 is a schematic diagram of a hard-switched half-bridge converter generation;
FIG. 3 is a schematic diagram of a hard-switched full-bridge converter;
FIG. 4 is a schematic diagram of a second generation edge-resonant phase-shifting and limited bipolar circuit;
FIG. 5 is a schematic diagram of a third generation LLC multi-resonant soft switching converter circuit structure;
FIG. 6 is a current waveform diagram of Lr of the LLC;
FIG. 7 is a schematic diagram of a circuit configuration of a four-generation LC quasi-resonant soft-switching converter;
FIG. 8 is a sine wave current diagram of the conduction of the switching tube;
FIG. 9 is a continuous sinusoidal current graph with two stages, one stage on and off at zero voltage and zero current;
fig. 10 is a current waveform diagram of an exciting current ILB output rectifier diode of the double-loop full-resonance type soft switching converter, in which the resonant current waveforms of the transistor Q1 and the transistor Q3, and the transistor Q3 and the transistor Q4 correspond to the driving waveforms of the transistor Ir, LB;
fig. 11 is a diagram that maximally realizes the fixed pulse width of the transistors Q1 and Q2, and the maximum PWM pulse width of the transistors Q3 and Q4, i.e., the waveforms of the ds poles of the left and right arms, respectively;
FIG. 12 is a graph of two-sided ds voltage waveforms with reduced PWM;
FIG. 13 is a graph of the two sides ds voltage waveform with continued reduction in PWM;
fig. 14 shows two-sided ds voltage waveform diagrams for PWM under very small conditions.
Fig. 15 is a graph of a near sine wave current waveform with large PWM duty cycle for the transistor Q1, transistor Q2, transistor Q3, transistor Q4 main loop llc resonant tank converter;
FIG. 16 is a current waveform diagram of the drive and loop with reduced duty cycle;
FIG. 17 is a current waveform diagram of the drive and loop with reduced duty cycle;
FIG. 18 is a current waveform diagram of the drive and loop with the duty cycle reduced;
FIG. 19 is a drive and loop current waveform diagram at very small duty cycles and minimum duty cycles;
FIG. 20 is a drive and loop current waveform diagram at very small duty cycles and minimum duty cycles;
FIG. 21 is a graph of the waveform of switching tube ds and the waveform of the loop sine wave current.
Detailed Description
The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are presented herein only to illustrate and explain the present invention, and not to limit the present invention.
Referring to fig. 1, a double-loop full-resonance soft switching converter is a combination of LLC multi-resonance principle and limited bipolar technology principle, where an inductor LB inductor Lr capacitor Cr is multi-resonance, the inductor Lr and the capacitor Cr are main series resonance, the inductor LB and a parallel resonance of a primary side of a transformer provide an inductor energy of a minimum excitation current, regardless of the duty ratios of a transistor Q3 and a transistor Q4 and the output power, the duty ratios of a transistor Q3 and a transistor Q4 are smaller than those of a transistor Q1 and a transistor Q2, the transistors Q1 and a transistor Q2 are turned off in advance for a certain time, the zero-voltage conduction of a transistor Q4 of a transistor Q3 is generated by charging and discharging a capacitor C5C 6 of a capacitor C5, and if the output power is reduced, that the duty ratios of the transistors Q3, Q4 and PWM are reduced and the time is longer, the inductor LB provides a capacitor C5 by the continuous conduction of a transistor Q1 and a transistor Q2, The charging and discharging of the capacitor C6, under the full-range PWM modulation, the transistor Q3 and the transistor Q4 are always turned on at zero voltage. The half-bridge inductor Lr (capacitor C3+ capacitor C4) divided by the capacitor C1 and the capacitor C2 generates the inductance energy of the storage inductor LB, and the transistor Q1 and the transistor Q2 also form a zero-voltage conduction condition through the LC resonant circuit. Here a fixed switching frequency.
Referring to fig. 1, a double-loop full-resonance type soft switching converter includes a limited bipolar LLC full-bridge main resonant circuit and an LC auxiliary resonant circuit, wherein the LLC full-bridge main resonant circuit is composed of a main resonant inductor LB, an inductor Lr, and a capacitor Cr, all four switching devices of the full bridge are connected in parallel with a capacitor, a positive terminal of an input voltage is connected to one end of a capacitor C1, one end of a capacitor C1 is connected to a collector of a transistor Q1, the other end of a capacitor C1 is connected to one end of a capacitor C2, one end of a capacitor C2 is connected to one end of an inductor L0, one end of an inductor L0 is connected to an emitter of a transistor Q1, a collector of a transistor Q1 is connected to one end of a capacitor C3, one end of a capacitor C3 is connected to a collector of a transistor Q4, a collector of a transistor Q4 is connected to one end of a capacitor C5, an emitter of a transistor Q1 is connected to a collector of a transistor Q, the other end of the capacitor C3 is connected with one end of a capacitor C4, one end of a capacitor C4 is connected with one end of an inductor LB, the inductor LB is connected with the input end of the transformer B in parallel, the other end of the inductor LB is connected with one end of an inductor Lr, the other end of the inductor Lr is connected with one end of a capacitor Cr, the other end of the capacitor Cr is connected with the emitter of a transistor Q4, the emitter of a transistor Q4 is connected with the collector of a transistor Q3, the collector of a transistor Q3 is connected with the other end of a capacitor C5, the other end of a capacitor C5 is connected with one end of a capacitor C6, one end of a capacitor C6 is connected with the emitter of a transistor Q3, the emitter of a transistor Q3 is connected with the other end of a capacitor C4, the other end of a capacitor C4 is connected with the emitter of a transistor Q2, the emitter of a transistor Q2 is connected with the other end of a capacitor C2, the other end, the cathodes of the diode D1 and the diode D2 are connected to the anode of the polarity capacitor E, which is connected in parallel with the load.
The utility model provides a solve above-mentioned problem like this, by B, C, D constitutes a major loop, BC is transformer primary voltage, first transistor Q1 switches on, third transistor Q3 also switches on simultaneously, then transistor Q3 always turns off in advance than transistor Q1, it is unloaded to get into the transformer, B-C's equivalent resistance is the biggest, this moment, the exciting current that inductance LB's inductance produced is by B, C to the loop that switches on of D point, to electric capacity C5, electric capacity C6 charges to D point level and is in Vin + voltage, this moment transistor Q4's voltage just goes out at zero voltage state, wait for transistor Q4 to switch on. Similarly, the second transistor Q2 is turned on, the fourth transistor Q4 is also turned on at the same time, then the transistor Q4 is always turned off earlier than the transistor Q2, if the transformer is unloaded, the resistance between B-C is the largest, at this time, the exciting current generated by the inductor LB is discharged from B, C to the conducting loop at the point D, the capacitor C5 and the capacitor C6 are discharged to the level at the point D, and at this time, the voltage of the transistor Q3 is at the zero voltage state, and the transistor Q3 is waited to be turned on. The inductor Lr and the capacitor Cr are series resonant circuits.
The utility model discloses an auxiliary resonance circuit is established ties by electric capacity C1, electric capacity C2, and A point voltage is in the mid point, 1/2Vin promptly. After the first transistor Q1 is turned on, the inductor L0 generates an excitation current, when the transistor Q1 is turned off, the inductor energy of the inductor L0 is released, after the resonance of the inductor L0 with the capacitor C3 and the capacitor C4, the B point is lowered to the voltage point of Vin + by the conduction of the transistor Q1, the second transistor Q2 is at the zero voltage position, the zero voltage conduction is waited, similarly, after the second transistor Q2 is turned on, the inductor L0 generates an excitation current in the opposite direction, when the transistor Q2 is turned off, the inductor energy of Li is released in the reverse direction, after the resonance of the inductor L0 with the capacitor C3 and the capacitor C4C, the B point is raised to the voltage point of Vin + by the zero voltage Vin-, the zero voltage conduction of the transistor Q1 is waited, and the process is repeated.
Because the reverse diodes are arranged in the transistors, if the reverse diodes are not arranged in the Bipolar Junction Transistor (BJT), the reverse diodes need to be connected in parallel outside, and for points B and D, the voltage is not higher than Vin + voltage, nor lower than Vin-negative voltage, and swings between Vin + and Vin-voltage.
According to the utility model provides a constitute by two parts resonance circuit. One part is main resonance, the other part is auxiliary resonance, so the double resonance circuit is called as a double resonance circuit, and the full soft switch transformer circuit is realized. The transistors Q1, Q2, Q3 and Q4 are all connected in parallel with a capacitor, and on the premise that zero voltage conduction can be generated, the existence of the capacitor can form a zero voltage or low voltage turn-off process, and as the loss power I × V is very small from the V value, the generated loss coefficient is reduced, that is, the turn-off loss of the power switch tube is transferred to the capacitor and is absorbed sufficiently, so that the high-efficiency converter is generated because the loss is very small. As shown in fig. 10, the drive voltage waveform, goes backPath current irExcitation current ilBAnd outputting the power waveform of the rectifier tube.
Since the auxiliary resonance is only a fixed constant between the inductor L0 and the capacitor C3+ the capacitor C4, the rise and fall times a of the transistors Q1 and Q2 are not V of the common techniqueDSVertical waves, but trapezoidal waves, the inclination being TDSThe current generated by the output power in the main resonant inductor LB inductor Lr capacitor Cr loop is the same, the duty ratio is the same, the turn-off current is not necessarily close to zero turn-off, the current of the switch tube is not the same, so the point D is not a vertical wave and is a trapezoidal wave, but the rising time and the falling time are not the same, namely the gradient of the charging and discharging speed of the capacitor C3 and the capacitor C4 caused by the change of the current is not constant, the primary resistance of the transformer is very large in no-load or light-load, and the gradient is relatively large only when the exciting current of the inductor LB is small. When the actually measured duty ratios are different in size, the Tds of the bridge arm with the changed duty ratios is almost the same.
The output rectifier tube is directly used for capacitance filtering, the rectifier diode is switched on and off under zero current, and under high frequency, a fast recovery diode or an ultra-fast recovery diode is needed.
The utility model provides a two resonant type soft switching converters entirely, not only can make full use of resonant circuit transmission energy's ability, at same transformer, the same parameter of power tube, under the same radiator condition, can provide bigger electric current to the load, export bigger power, moreover, in the further improved circuit, the power tube realizes that zero voltage opens, and zero current is turn-offed, conversion loss greatly reduced.
This can further increase the switching frequency, and the transformer of the inverter can be made smaller, thereby achieving miniaturization and cost reduction. Meanwhile, zero voltage is conducted, the voltage conversion rate of dv/dt is reduced by the wave-shaped trapezium of the switch tube, and electromagnetic radiation is reduced. Therefore, the utility model provides a soft switching converter of two resonant modes has electromagnetic interference little, and is efficient, with low costs etc. outstanding characteristics.
Specifically, as shown in fig. 1, the inductor LB, the inductor Lr, the capacitor Cr, and the transistor Q3 and the transistor Q4 of the main resonant LLC circuit of the full bridge circuit are turned on earlier than the transistor Q1 and the transistor Q2, the transistor Q1 and the transistor Q2 are turned on continuously, the loop continues to flow current, and the capacitor C5 and the capacitor C6 are charged and discharged, when a point D reaches Vin +, the transistor Q4 is turned on at zero voltage, and when the point D reaches Vin-, the transistor Q3 is turned on at zero voltage.
The pseudo phase shift, i.e., the limited bipolar control circuit, is adopted, and the maximum duty cycle of the transistor Q3 and the transistor Q4 is required to be smaller than that of the transistor Q1 and the transistor Q2, i.e., about 3% lower, i.e., about 0.03 full cycle time, and the time process of full charging and full discharging of the capacitor C5 and the capacitor C6 can still be allowed under the minimum loop current. Therefore, zero voltage conduction of the transistors Q3 and Q4 is realized, because the transistors Q1 and Q2 are connected with capacitors in parallel, the point B can reach Vin + in a certain time to generate zero voltage conduction of the transistor Q1, the point B reaches Vin-to generate zero voltage conduction of the transistor Q2, and because the auxiliary resonant current, namely the inductor L0, enables the capacitors C3 and C4 to be fully filled and completely discharged, the pulse widths of the transistors Q1 and Q2 cannot reach 50 percent and are 47 percent, and 3 percent of the pulse widths are reserved as a resonant time period. If the full charge and discharge process is not completed, the transistors Q1 and Q2 are not necessarily turned on at zero voltage, but at a certain voltage, so that the turn-on condition of completely zero voltage is lost.
Since the transistors Q3 and Q4 are PWM-modulated, the duty ratio varies, and the on time is variable. The maximum pulse width is set as the sine wave half cycle of the inductor Lr capacitor Cr, if there is no inductor LB, the primary resistor of the transformer is connected in series, and a switching tube, an output diode, and the transformer are all in an ideal state, i.e., the junction capacitor of the transistor and the turn capacitor of the transformer are ignored, at this time, the zero current is naturally turned off, the exciting current is superposed with the inductor LB, and the current is turned off at the peak current generated in the half cycle time, and the current is very small. However, the duty ratio changes, the on-time changes and becomes smaller, V ═ Vo (peak value) sin 2 pi ft according to the sine wave voltage value law, for example, 180 degrees in a half cycle, becomes 0, the voltage value, which is considered herein to be larger as the curve of the sine wave law increases with the shortening of the on-time, and sin90 ° -1 in the half cycle, that is, 90 °, becomes the maximum value of the sine wave, and then decreases again from the maximum value of 1. Then the transistors Q3 and Q4 are normally turned off at a certain current value, and the capacitors C5 and C6 exist to transfer the energy generated by the current to the capacitors for absorption.
This turn-off loss is greatly reduced, and the conversion efficiency is improved, as is the case with the transistor Q1 and the transistor Q2, and the turn-off loss is also reduced by the capacitors C3 and C4 connected in parallel, so that the conversion efficiency is improved. The practical result is that the loss of the transistor Q1 and the transistor Q2 with fixed pulse width is larger than that of the transistor Q3 and the transistor Q4, namely that the transistor Q1 and the transistor Q2 are two branches, one branch is LLC of the main loop, the other branch is LC auxiliary resonance, and two branches are superposed.
Then the auxiliary resonance of the inductor L0 (capacitor C3+ capacitor C4) and the current of the inductor L0 is a triangular wave. Whether the LLC of the main resonance or the LC of the auxiliary resonance, the energy of the inductor is usually larger than that of the parallel capacitor of the transistor, since the transistors Q1, Q2, Q3 and Q4 all have internal reverse diodes, for IGBT and BJT devices, if this internal reverse diode is not present, a fast reverse diode needs to be connected in parallel externally, in that the excess energy is absorbed by the input voltage by clamping the reverse diodes at the Vin + voltage and Vin-voltage.
The utility model discloses a LLC + LC's of technique double resonance topological mode, from the effect of experiment, the reference waveform, the DS ripples of switch tube, the waveform under the different duty cycles in return circuit, surveyability.
The dual resonant soft switching converter of the present technology will be described and illustrated at the end.
Low loss and high efficiency are thus achieved. In the prior art, the switching power tube is not connected with a capacitor in parallel, and is not zero current but is turned off by large current. Although the third generation LLC multi-resonant soft switching converter is widely used, the converter still is not the converter with the highest efficiency, for example, the switch-off current is usually relatively large, the dv/dt of the DS pole of the power tube is very high, usually only tens of nanoseconds, and less than 100 nanoseconds, then the power tube will enter high voltage in a short time, and a certain loss exists in a large current interval. According to the structural principle, all four switching devices are connected with capacitors in parallel, so that a switching track is changed from square waves into trapezoidal waves, the time reaches more than hundreds or five hundreds of nanoseconds and is far higher than the turn-off time of a switch, and zero current turn-off is generated, so that the loss is reduced, the conversion efficiency is improved, and the conversion efficiency is higher than that of the existing LLC multi-resonant converter, so that the conversion efficiency of the switching converter is further improved.
The embodiments of the present invention are not limited to the above embodiments, and according to the contents of the above embodiments of the present invention, the above preferred embodiments can also make modifications, replacements or combinations of other forms by using conventional technical knowledge and conventional means in the field without departing from the basic technical idea of the present invention, and the obtained other embodiments all fall within the scope of the present invention.
Claims (7)
1. A double-loop full-resonance type soft switching converter comprises an LLC full-bridge main resonance circuit and an LC auxiliary resonance circuit which are limited and bipolar, and is characterized in that the LLC full-bridge main resonance circuit is composed of a main resonance inductor LB, an inductor Lr and a capacitor Cr, all four switching devices of a full bridge are connected in parallel with a capacitor, the positive electrode of an input voltage is connected with one end of a capacitor C1, one end of a capacitor C1 is connected with the collector of a transistor Q1, the other end of the capacitor C1 is connected with one end of a capacitor C2, one end of a capacitor C2 is connected with one end of an inductor L0, one end of an inductor L0 is connected with the emitter of a transistor Q1, the collector of a transistor Q1 is connected with one end of a capacitor C3, one end of a capacitor C3 is connected with the collector of a transistor Q4, the collector of a transistor Q4 is connected with one end of a capacitor C5, the emitter of a transistor Q1 is connected with the collector, the other end of the capacitor C3 is connected with one end of a capacitor C4, one end of a capacitor C4 is connected with one end of an inductor LB, the inductor LB is connected with the input end of the transformer B in parallel, the other end of the inductor LB is connected with one end of an inductor Lr, the other end of the inductor Lr is connected with one end of a capacitor Cr, the other end of the capacitor Cr is connected with the emitter of a transistor Q4, the emitter of a transistor Q4 is connected with the collector of a transistor Q3, the collector of a transistor Q3 is connected with the other end of a capacitor C5, the other end of a capacitor C5 is connected with one end of a capacitor C6, one end of a capacitor C6 is connected with the emitter of a transistor Q3, the emitter of a transistor Q3 is connected with the other end of a capacitor C4, the other end of a capacitor C4 is connected with the emitter of a transistor Q2, the emitter of a transistor Q2 is connected with the other end of a capacitor C2, the other end, the cathodes of the diode D1 and the diode D2 are connected to the anode of the polarity capacitor E, which is connected in parallel with the load.
2. The dual-ring full-resonance type soft-switching converter according to claim 1, wherein the transistors Q1, Q2, Q3 and Q4 are power MOSFETs.
3. The double-ring full-resonance type soft switching converter according to claim 1, wherein the transistors Q1, Q2, Q3 and Q4 are insulated gate bipolar transistors IGBTs.
4. The dual-ring full-resonance type soft-switching converter according to claim 1, wherein the transistors Q1, Q2, Q3 and Q4 are bipolar transistors BJT.
5. The dual-ring full-resonance type soft switching converter according to claim 1, wherein the maximum duty cycle of the transistors Q3 and Q4 is small for the transistors Q1 and Q2.
6. The dual-ring full-resonance type soft switching converter according to claim 5, wherein the maximum duty cycle of the transistors Q3 and Q4 is 3% less than that of the transistors Q1 and Q2.
7. A double-ring full-resonance type soft-switching converter according to claim 3 or 4, wherein the transistors Q1, Q2, Q3 and Q4 have internal reverse diodes.
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| CN109742957A (en) * | 2019-02-12 | 2019-05-10 | 深圳市新能力科技有限公司 | A kind of bicyclic complex resonance type soft switch transducer |
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| CN109742957A (en) * | 2019-02-12 | 2019-05-10 | 深圳市新能力科技有限公司 | A kind of bicyclic complex resonance type soft switch transducer |
| CN109742957B (en) * | 2019-02-12 | 2024-02-09 | 深圳市新能力科技有限公司 | Double-ring full-resonance type soft switching converter |
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