Full-cycle power transfer soft-switching converter based on input enhancement multiplexing circuit

Abstract

The present invention discloses a full-cycle power transmission soft-switching converter based on an input enhancement multiplexing circuit, which belongs to the technical field of power electronic devices, and includes: an input power module, a main power and input enhancement secondary side series module, a soft switch and input enhancement primary side parallel module, a rectifier bridge module, an energy recovery module, a filter module and an output loop. The converter realizes the soft switching of the main power switch through the soft switch and input enhancement multiplexing circuit, and strengthens the input power supply voltage to improve the voltage gain. With this design, the converter can transmit power to the filter module and the output loop in the whole cycle, and can achieve high conversion efficiency, high voltage gain and low ripple of the converter. The beneficial effects of the present invention are: high conversion efficiency; PWM fixed frequency control is adopted, and the control method is simple; the soft switching range of the switch is widened, and the device loss is reduced; the voltage fluctuation of the filter inductor is small, so that the current ripple is small; the main transformer has a large turns ratio, which reduces the primary conduction loss and secondary voltage stress.

Description

Technical Field

[0001] The invention relates to the technical field of power electronic devices, and in particular to a full-cycle power transmission soft switching converter based on an input enhancement multiplexing circuit. Background Art

[0002] With the rapid development of power electronics technology, the application field of DC-DC converters, as key devices for power conversion, continues to expand. Among them, the isolated full-bridge converter, with its high power output and excellent input-output electrical isolation characteristics, occupies a pivotal position in renewable energy systems, electric vehicles, industrial control systems, communications and data center servers, and has a wide range of application scenarios. Among them, the phase-shifted full-bridge converter is widely used in the industrial field due to its advantages such as natural zero voltage switching, simple structure and high efficiency.

[0003] However, the traditional phase-shifted full-bridge converter has several well-known disadvantages. First, under light load conditions, it is difficult to achieve zero voltage switching of the lagging bridge arm switch, resulting in low efficiency and output voltage noise. Second, the duty cycle loss problem causes a serious drop in the output voltage, and the voltage gain is far from the theoretical value, which hinders the high frequency of the phase-shifted full-bridge converter. Third, the output current ripple is large, resulting in a large filter inductor size. Fourth, the parasitic oscillation on the rectifier diode increases the voltage stress of the device, resulting in large electromagnetic interference.

[0004] There are many solutions to solve the above problems, but they each have their own shortcomings and limitations. For example, the main transformer excitation inductance can be reduced, but this method will greatly increase circuit losses; variable inductance can be used instead of changing the series inductance on the primary side to reduce duty cycle loss, but this method will cause serious heating of the inductor core; asymmetric control methods can also be used to achieve soft switching, but the filter inductor design is difficult. Summary of the invention

[0005] Technical purpose: In view of the defects in the prior art, the present invention discloses a full-cycle power transmission soft-switching converter based on an input enhancement multiplexing circuit. The control method is relatively simple. The reverse voltage is generated by the primary side of the main transformer during the freewheeling period, so that the primary side circulating current is rapidly reduced, and the zero-current shutdown of the lagging bridge arm switch is achieved, thereby solving the technical problem of a narrow soft switching range. The input power supply voltage is enhanced by connecting the soft switch and the input enhancement secondary side in series to solve the current technical problem of too low voltage gain caused by duty cycle loss. An energy recovery module is added to suppress the oscillation of the rectifier diode, and power can be transmitted to the filter module and the output circuit during the entire cycle of the converter, thereby reducing the current ripple of the filter inductor, and simply and efficiently achieving the invention purpose of improving circuit performance and improving work efficiency.

[0006] Technical solution: In order to achieve the above technical objectives, the present invention adopts the following technical solution.

[0007] A full-cycle power transmission soft-switching converter based on an input enhancement multiplexing circuit comprises: an input power module, a main power and input enhancement secondary side series module, a soft switch and input enhancement primary side parallel module, a rectifier bridge module, an energy recovery module, a filter module and an output loop;

[0008] The input power module is used to provide a DC voltage V in ;

[0009] The main power and input enhanced secondary side series module comprises a main transformer T1 and an auxiliary transformer T2 connected in series; the main power and input enhanced secondary side series module is used to provide positive and negative alternating AC voltages to the main transformer T1, the positive polarity input end of the main power and input enhanced secondary side series module is connected to the positive pole of the input power module, and the negative polarity input end of the main power and input enhanced secondary side series module is connected to the negative pole of the input power module;

[0010] The soft switch and input enhancement primary parallel module includes an auxiliary transformer T2 reused with the main power and input enhancement secondary series module; the soft switch and input enhancement primary parallel module is used to control the auxiliary transformer T2 voltage to always be connected in series with the input power module in a forward polarity within a cycle range, thereby enhancing the input voltage, the positive polarity input end of the input enhancement primary parallel module is connected to the positive pole of the input power module, and the negative polarity input end of the input enhancement primary parallel module is connected to the negative pole of the input power module;

[0011] The rectifier bridge module includes a main transformer T1 multiplexed with the input enhanced secondary series module; the rectifier bridge module is used to rectify the AC voltage of the main transformer T1 into a high-frequency square wave DC voltage, and output it through the first output end of the rectifier bridge module and the second output end of the rectifier bridge module;

[0012] The energy recovery module, whose first input end and second input end are respectively connected to the first output end and the second output end of the rectifier bridge module; is used to suppress the voltage oscillation generated during the rectification process of the rectifier bridge module and improve electromagnetic interference, and outputs through the output end of the energy recovery module;

[0013] The filter module and the output circuit, the first input end and the second input end are connected to the first output end and the second output end of the rectifier bridge module, and the third input end is connected to the output end of the energy recovery module; it is used to receive the high-frequency square wave output by the rectifier bridge module and filter the output DC voltage V o .

[0014] Beneficial effects:

[0015] (1) The structure is simple and the cost is low, which can improve the shortcomings of the traditional phase-shifted full-bridge control circuit PSFB.

[0016] (2) It can expand the soft switching range of the lagging bridge arm and improve the duty cycle loss.

[0017] (3) Reduce the volume and weight of the output filter inductor.

[0018] (4) It can improve the voltage gain of the circuit, allowing the main transformer to use a larger turns ratio, reducing primary conduction loss and secondary voltage stress.

[0019] (5) Suppress secondary voltage oscillation and reduce rectifier diode voltage stress.

[0020] (6) It can reduce the circulating current and the conduction loss of the device.

[0021] (7) PWM constant frequency control is adopted, and the control method is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A topological structure diagram of a full-cycle power transmission converter based on a soft switch and input enhancement multiplexing circuit of the present invention;

[0023] Figure 2 is a driving signal V of a full-cycle power transmission converter based on a soft switch and input enhancement multiplexing circuit of the present invention. gs , rectifier module voltage v rec , the second and fourth power switch tubes Q2, Q4 current i Q2 、i Q4 , the primary current i of the main transformer T1 p 、Diode D C1 Current i Dc1 、Diode D C2 Current i Dc2 , buffer capacitor C S Voltage Cs , buffer capacitor C S Current i Cs 、Auxiliary transformer T2 primary side voltage v p1 Timing diagram;

[0024] Figures 3 to 8 A circuit topology modal diagram of a full-cycle power transmission converter based on a soft switch and input enhancement multiplexing circuit of the present invention;

[0025] Fig. 9 A schematic diagram of the rectifier-side voltage and output voltage of a full-cycle power transmission converter based on a soft switch and input enhancement multiplexing circuit of the present invention;

[0026] Fig.10 It is a schematic diagram of the rectifier side voltage and output voltage of the existing PSFB converter.

[0027] Among them, 1 is the input power module, 2 is the main power and input enhanced secondary side series module, 3 is the soft switch and input enhanced primary side parallel module, 4 is the rectifier bridge module, 5 is the energy recovery module, and 6 is the filter module and the output loop. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0029] As attached Figure 1 As shown, a full-cycle power transmission converter based on a soft switch and input enhancement multiplexing circuit includes: an input power module 1, a main power and input enhancement secondary side series module 2, a soft switch and input enhancement primary side parallel module 3, a rectifier bridge module 4, an energy recovery module 5, a filter module and an output loop 6.

[0030] The input power module 1 is used to provide a DC voltage V in ;

[0031] The main power and input enhanced secondary side series module 2 includes a main transformer T1 and an auxiliary transformer T2 connected thereto; the main power and input enhanced secondary side series module 2 is used to provide a positive and negative alternating AC voltage to the main transformer T1, the positive polarity input end of the main power and input enhanced secondary side series module 2 is connected to the positive pole of the input power module 1, and the negative polarity input end of the main power and input enhanced secondary side series module 2 is connected to the negative pole of the input power module 1;

[0032] The soft switch and input enhancement primary parallel module 3 includes an auxiliary transformer T2 reused with the main power and input enhancement secondary series module 2; the soft switch and input enhancement primary parallel module 3 is used to control the auxiliary transformer T2 voltage to always be consistent with the input power module V within a cycle range. in Connect in series in the forward polarity to enhance the input voltage, the positive polarity input end of the input enhancement primary parallel module 3 is connected to the positive pole of the input power module, and the negative polarity input end of the input enhancement primary parallel module 3 is connected to the negative pole of the input power module;

[0033] The rectifier bridge module 4 includes a main transformer T1 multiplexed with the input enhanced secondary series module 2; the rectifier bridge module 4 is used to rectify the AC voltage of the main transformer T1 into a high-frequency square wave, and output it through the first output end of the rectifier bridge module 4 and the second output end of the rectifier bridge module 4;

[0034] The energy recovery module 5 has a first input terminal and a second input terminal connected to the first output terminal and the second output terminal of the rectifier bridge module 4, respectively; it is used to suppress the voltage oscillation and improve the electromagnetic interference generated during the rectification process of the rectifier bridge module 4, specifically the voltage oscillation and electromagnetic interference when the rectifier diode in the rectifier bridge module 4 is turned off, and output through the output terminal of the energy recovery module 5;

[0035] The filter module and the output circuit 6, whose first input terminal and second input terminal are connected to the first output terminal and the second output terminal of the rectifier bridge module 4, and whose third input terminal is connected to the output terminal of the energy recovery module 5; is used to receive the high-frequency square wave output by the rectifier bridge module 4 and filter the output DC voltage V o .

[0036] The converter of the present invention connects the secondary side of the auxiliary transformer T2 in series with the primary side of the main transformer, so as to always connect it in series with the input power supply Vin in the same polarity, and improve the voltage gain by enhancing the input voltage. The secondary side of the auxiliary transformer of the present invention only needs one winding, and the structure is simple. The buffer capacitor Cs of the energy recovery module clamps the secondary side of the main transformer to VCs in working mode 6. VC s The buffer capacitor C of the energy recovery module s The voltage average value; VCs' reflected to the primary side of the main transformer causes the primary current to decrease rapidly, where VCs and VCs' satisfy VCs'=VCs×N T1 , N T1 The turns ratio of the main transformer. Due to the clamping effect of the buffer capacitor Cs, the voltage oscillation is reduced when the rectifier diode is turned off. Since the primary current has been reduced to zero before the lagging bridge arm switch tube, that is, the fourth power switch tube Q4 and the second power switch tube Q2 are turned off, the zero current shutdown of the lagging bridge arm can be achieved.

[0037] The main power and input enhanced secondary side series module 2 includes a first power switch tube Q1, a second power switch tube Q z , the third power switch tube Q3, the fourth power switch tube Q4, the DC blocking capacitor C B , a main transformer T1, an auxiliary transformer T2; wherein the first power switch tube Q1, the second power switch tube Q2, the third power switch tube Q3, and the fourth power switch tube Q4 constitute a PSFB circuit;

[0038] The drain of the first power switch tube Q1 is connected to the drain of the second power switch tube Q2, and serves as the positive polarity input terminal of the main power and input enhanced secondary side series module 2, and is connected to the positive electrode of the input power module 1; the source of the third power switch tube Q3 is connected to the source of the fourth power switch tube Q4, and serves as the negative polarity input terminal of the main power and input enhanced secondary side series module 2, and is connected to the negative electrode of the input power module 1;

[0039] The source of the first power switch tube Q1 is connected to the drain of the third power switch tube Q3, and the midpoint is used as the midpoint f of the first bridge arm; the source of the second power switch tube Q2 is connected to the drain of the fourth power switch tube Q4, and the midpoint is used as the midpoint h of the second bridge arm;

[0040] The midpoint f of the first bridge arm and the DC blocking capacitor C B One end of the DC blocking capacitor C B The other end of is connected to the same-name end of the primary side of the main transformer T1; the opposite-name end of the primary side of the main transformer T1 is connected to the same-name end of the secondary side of the auxiliary transformer T2, and the opposite-name end of the secondary side of the auxiliary transformer T2 is connected to the midpoint h of the second bridge arm.

[0041] The first power switch tube Q1, the second power switch tube Q2, the third power switch tube Q3, and the fourth power switch tube Q4 each have a junction capacitor connected in parallel between the drain and the source, which are C OSS1 , C OSS2 , C OSS3 , C OSS4 , and the reverse parallel body diodes between the drain and the source are VD1, VD2, VD3, and VD4 respectively.

[0042] The soft switch and input enhancement primary parallel module 3 includes a second power switch tube Q2, a fourth power switch tube Q4, and an auxiliary transformer T2. The soft switch and input enhancement primary parallel module 3 and the main power and input enhancement secondary series module 2 reuse the second power switch tube Q2, the fourth power switch tube Q4, and the auxiliary transformer T2.

[0043] Among them, the drain of the second power switch tube Q2 is used as the positive polarity input terminal of the main power and soft switch and input enhanced primary parallel module 3, connected to the positive electrode of the input power module 1, and the source of the fourth power switch tube Q4 is used as the negative polarity input terminal of the soft switch and input enhanced primary parallel module 3, connected to the negative electrode of the input power module 1;

[0044] The source of the second power switch tube Q2 is connected to the drain of the fourth power switch tube Q4, and the midpoint serves as the midpoint h of the second bridge arm;

[0045] The negative electrode of the constant voltage capacitor C1 is connected to the negative electrode of the input power module 1, and the positive electrode of the constant voltage capacitor C1 is connected to the opposite-name terminal of the primary side of the auxiliary transformer T2; the same-name terminal of the primary side of the auxiliary transformer T2 and the same-name terminal of the secondary side of the auxiliary transformer T2 are commonly connected to the midpoint h of the second bridge arm.

[0046] The rectifier bridge module 4 includes a first power diode D1, a second power diode D2, a third power diode D3, a fourth power diode D4, and a main transformer T1; the rectifier bridge module 4 and the main power and input enhanced secondary side series module 2 reuse the main transformer T1; the first power diode D1, the second power diode D2, the third power diode D3, and the fourth power diode D4 constitute a rectifier diode;

[0047] Among them, the anode of the first power diode D1 is connected to the same-name terminal of the secondary side of the main transformer T1, and the cathode of the first power diode D1 is connected to the cathode of the second power diode D2, and serves as the first output terminal of the rectifier bridge module 4; the anode of the second power diode D2 is connected to the opposite-name terminal of the secondary side of the main transformer T1;

[0048] The cathode of the third power diode D3 is connected to the same-name terminal of the secondary side of the main transformer T1, and the anode of the third power diode D3 is connected to the anode of the fourth power diode D4, and serves as the second output terminal of the rectifier bridge module 4; the cathode of the fourth power diode D4 is connected to the opposite-name terminal of the secondary side of the main transformer T1;

[0049] The energy recovery module 5 includes a buffer capacitor C S 、Diode D C1 、Diode D C2 ;

[0050] Snubber capacitor C S The positive electrode of is used as the first input end of the energy recovery module 5, connected to the first output end of the rectifier bridge module 4, that is, connected to the cathode of the second power diode D2, and the buffer capacitor C S The cathode of the diode D C1 The cathode and diode D C2 The anodes of diodes D are connected together; C1 The anode of the fourth power diode D4 is used as the second input terminal of the energy recovery module 5 and connected to the second output terminal of the rectifier bridge module 4;

[0051] Diode D C2 The cathode of the energy recovery module 5 is used as the output end, and the third input end of the filter module and the output loop 6 is connected, that is, the filter capacitor C o positive electrode.

[0052] The filter module and the output loop 6 include a filter inductor L o 、Filter capacitor C o , load R;

[0053] Filter inductor L oOne end of the filter module is used as the first input end of the output loop 6, connected to the first output end of the rectifier bridge module 4, and is also the first input end of the energy recovery module 5, that is, the buffer capacitor C S The positive terminal and the other end are connected to the filter capacitor C o The positive electrode of the filter capacitor C is connected to the positive electrode of the load R; o The positive electrode of the filter module is used as the third input terminal of the output loop 6, and is connected to the output terminal of the energy recovery module 5, that is, the diode D C2 The cathode of the filter capacitor C o The negative electrode of the filter module is used as the second input terminal of the output loop 6, connected to the second output terminal of the rectifier bridge module 4, and also the second input terminal of the energy recovery module 5, that is, connected to the diode D C1 Anode of filter capacitor C o The negative electrode of the load R is also connected to the negative electrode of the load R; the two ends of the load R serve as the output ends of the filter module and the output circuit 6, and the output DC voltage V o ; Among them, the filter capacitor C o The cathode of the third power diode D3 anode, the fourth power diode D4 anode, and the diode D C1 The anodes are commonly grounded.

[0054] The present invention applies a half-input voltage V with the same frequency as the switching frequency, alternating positive and negative, to the primary side of the auxiliary transformer T2 through a large constant voltage capacitor C1 and a high-frequency switch tube Q4. in Therefore, the secondary side of the auxiliary transformer T2 will also induce a voltage of the same frequency. Through the reasonable configuration of the transformer same-name terminal in this application, it can be ensured that this voltage is always consistent with the input power module voltage V in The polarity is connected in series, thereby strengthening the input power supply voltage and improving the voltage gain. The present invention eliminates the primary side circulating current, does not use the excitation current, but realizes ZCS shutdown through the lagging bridge arm, thereby widening the soft switching range of the lagging bridge arm switch.

[0055] In order to reduce the impact on the output voltage ripple and voltage gain, the ripple of the constant voltage capacitor C1 should be as small as possible. Generally, the ripple ΔV of the constant voltage capacitor C1 is taken as C1 It is 1% of the input voltage and its value is calculated according to formula 1:

[0056]

[0057] Among them, I o is the output current, T s is the switching period, N T1 is the main transformer turns ratio, ΔV C1 is the ripple of constant voltage capacitor C1.

[0058] Below Figure 1 The main circuit structure is shown, combined with the ideal signal waveform Figure 2 , stage modal series Figure 3-Figure 9 , specifically describing the working principle and working mode of the full-cycle power transmission converter based on soft switching and input enhancement multiplexing circuit of the present invention.

[0059] In the present invention, the first to fourth power switch tubes Q1, Q2, Q3, and Q4 are all controlled by PWM fixed frequency, and are turned on for 50% of a switching cycle, and the upper and lower tubes of the same bridge arm are set with a dead time of 3% of the switching cycle. D is the duty cycle, defined as Among them, T on T is the time that Q1, Q4 (or Q2, Q3) are turned on together in one switching cycle. s is a switching cycle. The output voltage is controlled by the duty cycle D.

[0060] Working mode 1: Figure 3 The circuit topology shown corresponds to Figure 2 In the period [t0, t1] shown in the figure, at time t0, the second power switch tube Q2 is turned off, and the primary side current i p Very small, only the main transformer T1 excitation current, reducing the circulating current loss. The second and fourth switch tube equivalent capacitance C oss2 , C oss4 The first to fourth power diodes D1, D2, D3, and D4 in the rectifier bridge module are all turned off, and their voltages are clamped to the buffer capacitor C. S The diode turns off and the rectifier is disconnected from the output side. C1 In forward conduction, the power of the load R is supplied by the buffer capacitor C in the energy recovery module. S Even if the rectifier is disconnected from the output side, power is still continuously transmitted to the filter module and the output loop. At time t1, the charging and discharging process ends, and the fourth power switch tube Q4 is turned on.

[0061] Working mode 2: Figure 4 The circuit topology shown corresponds to Figure 2 In the period [t1, t2] shown in the figure, at time t1, the first power switch tube Q1 and the fourth power switch tube Q4 are turned on at the same time, and the secondary side voltage of the auxiliary transformer T2 is equal to the power supply voltage V in The first and fourth power diodes D1 and D4 are turned on. The primary current i p At t1, the primary side voltage v of the auxiliary transformer T2 is p1 reaches negative half of the input voltage Vin During this period, the secondary current of the main transformer T1 is less than the output inductor current i Lo , diode D C1 Keep the on state and store the current in the buffer capacitor C S The energy in the load is transferred to the load R until the secondary current of the main transformer T1 is equal to the output inductor current i Lo .

[0062] Working mode 3: Figure 5 The circuit topology shown corresponds to Figure 2 In the period [t2, t3] shown in the figure, at time t2, the secondary current of the main transformer T1 begins to be greater than the output inductor current i Lo , diode D C1 Reverse bias, diode D C2 The primary leakage inductance of the main transformer is L lk1 Start with the snubber capacitor C S Resonance, the input power is transferred from the input side to the output side in a resonant mode. The primary side current i of the main transformer T1 p is through the diode D C2 The resonant current i Dc2 and output filter inductor L o The current i Lo The sum of the currents reflected to the primary side. Therefore, the energy delivered through the main transformer T1 is the parallel combination of the PSFB circuit and the energy recovery module, increasing the total power from input to output.

[0063] Working mode 4: Figure 6 The circuit topology shown corresponds to Figure 2 In the period [t3, t4] shown in the figure, at time t3, the diode D C2 The current i Dc2 The resonance is zero, and the diode D C2 Reverse bias shutdown, buffer capacitor C S Voltage Cs Main transformer T1 primary side current i p Remains unchanged, its size is the output filter inductor L o The current i Lo Current reflected to the primary side.

[0064] Working mode 5: Figure 7 The circuit topology shown corresponds to Figure 2 In the period [t4, t5] shown in the figure, at time t4, the first power switch tube Q1 is turned off, and the primary side current i p Start to measure the equivalent capacitance C of the first and third switch tubes oss1 , C oss3At time t5, the third power switch tube Q3 is turned on in a zero voltage mode. The primary side current i p Start to descend.

[0065] Working mode 6: Figure 8 The circuit topology shown corresponds to Figure 2 In the period [t5, t6] shown in the figure, at time t5, the secondary current of the main transformer T1 is less than the output filter inductor current i Lo , so the diode D C1 Forward bias. Buffer capacitor C S The voltage v Cs Through the rectifier bridge module, it is reflected to the primary leakage inductance L of the main transformer lk1 Therefore, the primary leakage inductance of the main transformer is L lk1 Withstanding reverse pressure, the primary current i of the main transformer T1 p Rapidly reduce, reduce the current loss of a cycle. In this mode, the input power module is no longer involved, but the soft switch and input enhanced primary parallel module act as the power supply of the main transformer T1.

[0066] Through the analysis of the working mode of the circuit, we can know that the present invention realizes the full-cycle power transmission of the converter of the present invention through the soft switch and the input enhanced primary parallel module. The circuit has the following advantages: (1) simple structure and low cost, which can improve the shortcomings of the traditional phase-shifted full-bridge control circuit PSFB; (2) can expand the soft switching range of the lagging bridge arm and improve the duty cycle loss; (3) reduce the volume and weight of the output filter inductor; (4) can improve the voltage gain of the circuit, so that the main transformer can use a larger turns ratio, reduce the primary conduction loss and secondary voltage stress; (5) suppress the secondary voltage oscillation and reduce the voltage stress of the rectifier diode; (6) can reduce the circulating current and reduce the conduction loss of the device.

[0067] Specifically, ignoring the commutation process, the following can be made for working mode 3, working mode 4, and working mode 6: Fig. 9 and attached Fig.10 Simplified rectifier side voltage comparison diagram.

[0068] To simplify the analysis, Fig. 9 and attached Fig.10 The voltages in the table are all average values. Fig. 9 1 is a schematic diagram of the voltage on the rectifier side and the output voltage of the converter of the present invention, and dynamic 10 is a schematic diagram of the voltage on the rectifier side and the output voltage of the existing PSFB converter. T Represents the turns ratio of the existing PSFB converter, N T1 represents the turns ratio of the converter of the present invention. D is the duty cycle. V Cs The buffer capacitor C of the energy recovery module sThe average voltage value, which can be known from working mode 3, is V Cs =1.5V in / N T1 -V o The buffer capacitor C s The size is determined by:

[0069]

[0070] Where P o is the output power.

[0071] According to the above figure, in the interval [0.5DT s , 0.5T s ], the output filter inductor L can be derived o Ripple formula:

[0072]

[0073]

[0074] Where L o1 is the output filter inductor required by the converter of the present invention, L o2 is the output filter inductance required by the existing PSFB converter, ΔI1 is the ripple of the output filter inductance of the converter of the present invention, and ΔI2 is the ripple of the output filter inductance of the existing PSFB converter. Under the same ripple requirements, it can be seen from equations (3) and (4) that the output filter inductance required by the converter of the present invention is significantly smaller than that of the existing PSFB converter. Since the inductance value is proportional to the square of the number of turns, the smaller the inductance value, the smaller the volume and weight of the inductance.

[0075] In general, the transformer turns ratio (primary turns to secondary turns) is determined by the minimum input voltage. o The volt-second balance derives the following formula:

[0076]

[0077]

[0078]

[0079] Formula (7) is derived by combining formula (5) and (6), where M1(D) is the voltage gain expression of the existing PSFB converter, M2(D) is the voltage gain expression of the converter of the present invention, and N T Represents the existing PSFB converter turns ratio, N T1 represents the turns ratio of the converter of the present invention. D is the duty cycle.

[0080] Under the condition that the circuit parameter requirements are the same, formula (7) is always greater than one in the entire duty cycle D range, that is, the turns ratio of the present invention is larger. The larger the turns ratio, the smaller the primary current, which can reduce the conduction loss.

[0081] The "first" and "second" in the names of "first" and "second" mentioned in the embodiments of this application are only used as name identifications and do not represent their importance rankings.

[0082] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A full-cycle power transmission soft switching converter based on input enhancement multiplexing circuit, characterized in that: include: Input power module, main power and input enhanced secondary side series module, soft switch and input enhanced primary side parallel module, rectifier bridge module, energy recovery module, filter module and output circuit; The input power module is used to provide a DC voltage V in ; The main power and input enhanced secondary side series module comprises an H-bridge formed by the first power switch tube Q1 to the fourth power switch tube Q4, and the primary side of the main transformer T1 and the secondary side of the auxiliary transformer T2 connected at the midpoint of the bridge arm of the H-bridge; the main power and input enhanced secondary side series module is used to provide positive and negative alternating AC voltage to the primary side of the main transformer T1; The soft switch and input enhancement primary parallel module includes the secondary side of the auxiliary transformer T2 reused with the main power and input enhancement secondary series module, the second power switch tube Q2 and the fourth power switch tube Q4, and the series-connected constant voltage capacitor C1 connected in parallel on both sides of the fourth power switch tube Q4, and the primary side of the auxiliary transformer T2; the soft switch and input enhancement primary parallel module is used to control the auxiliary transformer T2 voltage to always be connected in series with the input power module in a forward polarity within a cycle range, thereby enhancing the input voltage; The rectifier bridge module includes a rectifier bridge composed of a first power diode D1 to a fourth power diode D4, and a secondary side of a main transformer T1 connected to the midpoint of a bridge arm; the rectifier bridge module is used to rectify the AC voltage of the main transformer T1 into a high-frequency square wave DC voltage, and output it through a first output end of the rectifier bridge module and a second output end of the rectifier bridge module; The energy recovery module, whose first input end and second input end are respectively connected to the first output end and the second output end of the rectifier bridge module; is used to suppress the voltage oscillation generated during the rectification process of the rectifier bridge module and improve electromagnetic interference, and outputs through the output end of the energy recovery module; The filter module and the output circuit have a first input terminal and a second input terminal connected to the first output terminal and the second output terminal of the rectifier bridge module respectively, and a third input terminal connected to the output terminal of the energy recovery module; and are used to filter the high-frequency square wave output by the rectifier bridge module and output a DC voltage V o .

2. According to claim 1, a full-cycle power transmission soft switching converter based on input enhancement multiplexing circuit is characterized in that: The main power and input enhanced secondary side series module includes a first power switch tube Q1, a second power switch tube Q2, a third power switch tube Q3, a fourth power switch tube Q4, a DC blocking capacitor C B , the primary side of the main transformer T1, the secondary side of the auxiliary transformer T2; The drain of the first power switch tube Q1 is connected to the drain of the second power switch tube Q2, and serves as the positive polarity input terminal of the main power and input enhanced secondary side series module, and is connected to the positive electrode of the input power module. The source of the third power switch tube Q3 is connected to the source of the fourth power switch tube Q4, and serves as the negative polarity input terminal of the main power and input enhanced secondary side series module, and is connected to the negative electrode of the input power module. The source of the first power switch tube Q1 is connected to the drain of the third power switch tube Q3, and the midpoint serves as the midpoint of the first bridge arm. f The source of the second power switch tube Q2 is connected to the drain of the fourth power switch tube Q4, and the midpoint serves as the midpoint of the second bridge arm. h ; Midpoint of the first bridge arm f With the DC blocking capacitor C B One end of the DC blocking capacitor C B The other end is connected to the same-name end of the primary side of the main transformer T1; the opposite-name end of the primary side of the main transformer T1 is connected to the same-name end of the secondary side of the auxiliary transformer T2, and the opposite-name end of the secondary side of the auxiliary transformer T2 is connected to the midpoint of the second bridge arm. h connect.

3. The full-cycle power transmission soft switching converter based on input enhancement multiplexing circuit according to claim 2 is characterized in that: A junction capacitor is connected in parallel between the drain and source of each power switch tube, and a body diode is connected in anti-parallel between the drain and source.

4. The full-cycle power transmission soft switching converter based on input enhancement multiplexing circuit according to claim 1 is characterized in that: The soft switch and input enhancement primary parallel module includes a second power switch tube Q2, a fourth power switch tube Q4, and a primary side of an auxiliary transformer T2. The soft switch and input enhancement primary parallel module and the main power and input enhancement secondary series module reuse the second power switch tube Q2, the fourth power switch tube Q4, and the secondary side of the auxiliary transformer T2. Among them, the drain of the second power switch tube Q2 is used as the positive polarity input terminal of the main power and soft switch and input enhanced primary parallel module, connected to the positive electrode of the input power module, and the source of the fourth power switch tube Q4 is used as the negative polarity input terminal of the soft switch and input enhanced primary parallel module, connected to the negative electrode of the input power module; The source of the second power switch tube Q2 is connected to the drain of the fourth power switch tube Q4, and the midpoint serves as the midpoint of the second bridge arm. h ; The negative electrode of the constant voltage capacitor C1 is connected to the negative electrode of the input power module 1, and the positive electrode of the constant voltage capacitor C1 is connected to the opposite end of the primary side of the auxiliary transformer T2; the same end of the primary side of the auxiliary transformer T2 and the opposite end of the secondary side of the auxiliary transformer T2 are connected to the midpoint of the second bridge arm. h .

5. The full-cycle power transmission soft switching converter based on input enhancement multiplexing circuit according to claim 1 is characterized in that: The rectifier bridge module includes a first power diode D1, a second power diode D2, a third power diode D3, a fourth power diode D4, and a secondary side of a main transformer T1; The anode of the first power diode D1 is connected to the same-name terminal of the secondary side of the main transformer T1, and the cathode of the first power diode D1 is connected to the cathode of the second power diode D2, and serves as the first output terminal of the rectifier bridge module; the anode of the second power diode D2 is connected to the opposite-name terminal of the secondary side of the main transformer T1; The cathode of the third power diode D3 is connected to the same-name terminal on the secondary side of the main transformer T1, the anode of the third power diode D3 is connected to the anode of the fourth power diode D4, and serves as the second output terminal of the rectifier bridge module; the cathode of the fourth power diode D4 is connected to the opposite-name terminal on the secondary side of the main transformer T1.

6. The full-cycle power transmission soft switching converter based on input enhancement multiplexing circuit according to claim 1 is characterized in that: The energy recovery module includes a buffer capacitor C S 、Diode D C1 、Diode D C2 ; Snubber capacitor C S The positive electrode is used as the first input terminal of the energy recovery module, connected to the first output terminal of the rectifier bridge module, and the buffer capacitor C S The cathode of the diode D C1 The cathode and diode D C2 The anodes of diodes D are connected together; C1 The anode of the power supply is used as the second input terminal of the energy recovery module and connected to the second output terminal of the rectifier bridge module; Diode D C2 The cathode serves as the output end of the energy recovery module, connecting the filter module with the third input end of the output loop.

7. The full-cycle power transmission soft switching converter based on input enhancement multiplexing circuit according to claim 1 is characterized in that: The filter module and the output circuit include a filter inductor L o 、Filter capacitor C o , load R; filter inductor L o One end of the filter module is used as the first input end of the output circuit, connected to the first output end of the rectifier bridge module, and the other end is connected to the filter capacitor C o The positive electrode of the filter capacitor C is connected to the positive electrode of the load R; o The positive electrode of the filter module is used as the third input terminal of the output circuit, and is connected to the output terminal of the energy recovery module; the filter capacitor C o The negative electrode of the filter module is used as the second input terminal of the output circuit, and is connected to the second output terminal of the rectifier bridge module; the filter capacitor C o The negative electrode of the load R is also connected to the negative electrode of the load R; the two ends of the load R serve as the output ends of the filter module and the output circuit, and the output DC voltage V o .

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