Novel difference fixed-frequency boost control method suitable for resonant transformation topology

Abstract

The invention discloses a novel difference fixed-frequency boost control method suitable for resonant transformation topology, and relates to the technical field of resonant converter wide-range fixed-frequency boost control. According to the method, the switching frequency of a switching tube of a rectifier full bridge is set to be half of the switching frequency of a switching tube of an inverter side full bridge, the switching frequency of the inverter side full bridge is rated resonant frequency, a half-cycle feedback current circuit is formed, the feedback energy time is adjusted by controlling the PWM proportion of a single tube, and the output voltage of the converter is pumped up. Soft switching characteristics of part of switching tubes are inherited, wide gain of the converter on a rated frequency point can be guaranteed, the situation that tube section current is too high due to the fact that traditional frequency conversion control is in a wide under-resonance interval or a low inductance ratio is avoided, meanwhile, the problem that soft switching cannot be achieved in phase-shifting control is also avoided, and the control efficiency of the converter is improved. Meanwhile, over-wide frequency range adjustment is avoided for high-frequency application, convenience is brought to design of magnetic elements, and certain high-frequency and high-power-density application potential is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of wide-range fixed-frequency boost control of resonant converters, and in particular to a novel differential fixed-frequency boost control method suitable for resonant conversion topology. Background Art

[0002] In recent years, with the advancement of science and technology and the continuous breakthroughs in power electronics technology, isolated resonant converters have been widely used in the field of DC buildings and the construction of DC power distribution systems, especially in distributed energy storage and new energy scenarios. The continuous progress and breakthroughs in the application technology of topology transformation technology and new wide bandgap devices have made high efficiency and high power density the development direction of power electronic devices, especially in the application needs of household energy storage and household adaptation, which have strict requirements on efficiency, volume, wide gain and digital control technology. Traditional LLC, CLLC and other resonant topologies have received widespread attention due to their good switching voltage stress and good EMI characteristics. However, the isolated resonant topology often adopts the frequency modulation control method when boosting, and this method is mostly adjusted within the range of 1 to 1.2 times the standardized voltage gain, and the adjustment range is relatively narrow. The working condition greater than 1.2 requires further reduction of the inductance ratio, which often leads to a decrease in the quality factor of the converter and a decrease in efficiency. The other fixed frequency, phase-shifted boost control method completely loses the soft switching characteristics, which makes the advantages of the resonant converter lost. That is, when the resonant converter represented by the traditional LLC and CLLC adopts the variable frequency control mode, it has stringent parameter design requirements in the under-frequency range, and it is difficult to balance wide gain and high efficiency. Therefore, it is urgent to propose a new type of fixed-frequency wide-gain boost control strategy to solve the problem of difficulty in balancing efficiency and wide gain, and loss of soft switching characteristics of the switch tube. Summary of the invention

[0003] In order to solve the defects of the above-mentioned technology, the present invention provides a novel differential fixed-frequency boost control method suitable for resonant conversion topology.

[0004] The technical solution adopted by the present invention to achieve the above technical effects is:

[0005] A novel differential fixed-frequency boost control method applicable to a resonant conversion topology comprises the following steps:

[0006] S1. Determine the main resonant frequency according to the resonant parameters, configure the switching frequency of the switch tube of the inverter side full bridge to be the main resonant frequency, and the switching frequency of the switch tube of the rectifier side full bridge to be half of the main resonant frequency, so as to form a half-cycle feedback current circuit;

[0007] S2, controls the PWM duty cycle of one of the single tubes on the switching tube of the full-bridge on the rectifier side, adjusts the output voltage and the energy storage time of the resonant cavity, controls the size of the resonant current pumping, further releases energy during transmission, and realizes the output voltage pumping.

[0008] Preferably, in the above-mentioned novel differential fixed-frequency boost control method applicable to the resonant conversion topology, the step S1 comprises the steps of:

[0009] S11. A switching cycle of the full bridge on the rectifier side is twice the switching cycle of the full bridge on the inverter side. During the first positive switching cycle, the resonant cavity resonates, the switch tube has a soft switching characteristic, and energy is transferred in the positive direction until entering the first negative switching cycle.

[0010] S12. In the first negative switching cycle, through diode rectification, the resonant cavity involves the excitation inductance, and the resonant cycle changes. During this period, the current direction changes, creating conditions for the soft switching of the next inverter positive cycle.

[0011] Preferably, in the above-mentioned novel differential fixed-frequency boost control method applicable to the resonant conversion topology, the step S2 comprises the steps of:

[0012] S21, in the second positive switching cycle, the switch tube of the full bridge on the rectifier side is turned on, and the energy of the output capacitor is fed back to the resonant cavity to strengthen the resonant energy of the resonant cavity. The amount of injected energy is proportional to the duty cycle of the upper tube. When the upper tube is turned off, the current flows through the lower tube diode. At this time, the current does not pass through the output load;

[0013] S22. In the second negative switching cycle, energy is released based on the energy stored in the resonant cavity, and the current continues to flow through the switch tube of the full bridge on the rectifier side until the next switching cycle arrives.

[0014] Preferably, in the above-mentioned new differential constant-frequency boost control method suitable for resonant conversion topology, the PWM duty cycle of the switch tube of the inverter side full-bridge is controlled to 47%, the PWM duty cycle of one of the upper tubes of the switch tube of the rectifier side full-bridge is controlled to 0-23.5%, and the PWM duty cycle of the remaining tubes is controlled to 23.5%.

[0015] Preferably, in the novel differential fixed-frequency boost control method applicable to the resonant conversion topology, the resonant conversion topology includes a CLLC resonant topology, and the topological structure includes an inverter side full bridge composed of switch tubes Q1 to Q4, and a switch tube Q SR1 ~Q SR4 The rectifier side full bridge is composed of the resonant inductor L r1 , resonant inductor L r2 , resonant capacitor C r1 and resonant capacitor C r2The resonant structure is formed, and one end of the primary side of the transformer is connected through the resonant inductor L r1 Connected to the connecting line between switch tube Q2 and switch tube Q4, the other end is connected through the resonant capacitor C r1 Connected to the connecting line of switch tube Q1 and switch tube Q3, the two ends of the primary side of the transformer are connected in parallel with the excitation inductor L m , one end of the secondary side of the transformer is connected through the resonant inductor L r2 Connect to the switch tube Q SR1 And the switch tube Q SR3 The other end of the connecting line is connected through the resonant capacitor C r2 Connect to the switch tube Q SR2 And the switch tube Q SR4 on the connection line.

[0016] Preferably, in the novel differential fixed-frequency boost control method applicable to the resonant conversion topology, the resonant capacitor C r1 , resonant capacitor C r2 , resonant inductor L r1 , resonant inductor L r2 The main resonant frequency of the construction is f r , the control frequency of the switch tubes Q1~Q4 is f r , the duty cycle is 47%, the switch tube Q SR1 ~Q SR4 The control frequency is f r / 2, where the switch tube Q SR2 The PWM duty cycle adjustment range of the switch is 0 to 23.5%, and the PWM duty cycle of the other switch tubes is fixed at 23.5%.

[0017] Preferably, in the novel differential fixed-frequency boost control method applicable to the resonant conversion topology, in the first positive half cycle of the switching cycle, the driving voltage signal V g1 And the driving voltage signal V of the switch tube Q4 g4 The switch tube Q1 and the switch tube Q4 are turned on, and the corresponding switch tube Q on the full bridge on the rectifier side is SR1 The driving voltage signal V sr1 And the switch tube Q SR4 The driving voltage signal V sr4 is high level, the switch tube Q SR1 And the switch tube Q SR4 The power is transferred to the secondary side through the resonant cavity and the transformer. At this time, the resonant cavity is connected by the resonant inductor L r1 , resonant inductor L r2 , resonant capacitor C r1 and resonant capacitor C r2 The resonant frequency is the main resonant frequency f r, pull the switch tube voltage down to 0 to ensure soft switching, and the current passes through the transformer and resonant inductor L r2 , switch tube Q SR1 , load RL, switch tube Q SR4 Form a forward loop.

[0018] Preferably, in the novel differential fixed-frequency boost control method applicable to the resonant conversion topology, at the reverse resonance time, the resonant cavity is reconstructed, and the resonant inductor L r1 , resonant inductor L r2 , resonant capacitor C r1 , Excitation inductance L m And resonant capacitor C r2 The composition of the resonant inductor L r1 , L r2 A slow discharge is performed, during which the resonant cavity current reverses, creating soft switching conditions for the opening of the switch tubes Q1 and Q4 corresponding to the second forward resonance.

[0019] Preferably, in the novel differential fixed-frequency boost control method applicable to the resonant conversion topology, in the energy feedback stage, the resonant cavity is reconstructed, and the resonant inductor L r1 , resonant inductor L r2 , resonant capacitor C r1 And resonant capacitor C r2 The current passes through the transformer and the resonant inductor L r2 , switch tube Q SR3 , load RL, switch tube Q SR2 A reverse loop is formed, and the output capacitor C0 discharges and feeds back part of the energy into the resonant cavity.

[0020] Preferably, in the novel differential fixed-frequency boost control method applicable to the resonant conversion topology, in the input energy storage stage, the resonant cavity is composed of a resonant inductor L r1 , resonant inductor L r2 , resonant capacitor C r1 and resonant capacitor C r2 The secondary current passes through the transformer and the resonant inductor L r2 , switch tube Q SR3 , load RL and switch tube Q SR24 Form a reverse loop.

[0021] The beneficial effects of the present invention are as follows: the present invention can realize the output voltage pumping of the converter by fixing the switching frequency of the inverter side switch tube and the rectifier side switch tube and controlling the PWM ratio of the single tube to adjust the feedback energy time, and inherits the soft switching characteristics of some switch tubes, solving the problem that traditional frequency modulation control cannot solve that it is difficult to balance efficiency and wide gain. At the same time, for high-frequency applications, it avoids excessively wide frequency range adjustment, brings convenience to the design of magnetic components, and has certain high-frequency and high-power density application potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A topological structure diagram of boost control using the CLLC topology as an example in the present invention;

[0023] Figure 2 When the duty cycle of the upper switch tube of the full bridge on the rectifier side of the present invention is 5%, the respective drive signal waveforms, key current and output voltage waveforms;

[0024] Figure 3 When the duty cycle of the upper switch tube of the full bridge on the rectifier side of the present invention is 23.5%, the respective drive signal waveforms, key current and output voltage waveforms; DETAILED DESCRIPTION

[0025] In order to further understand the present invention, the present invention is further described below with reference to the accompanying drawings and specific embodiments:

[0026] In the description of the present invention, it should be noted that the terms "vertical", "upper", "lower", "horizontal", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, "first", "second", "third", and "fourth" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0027] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection, it can be a mechanical connection, it can be an electrical connection, it can be a direct connection, it can be connected through an intermediate medium, and it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] The embodiment of the present invention proposes a novel differential fixed-frequency boost control method applicable to a resonant conversion topology, the method comprising the steps of:

[0029] S1. Determine the main resonant frequency according to the resonant parameters, configure the switching frequency of the switch tube of the inverter side full bridge to be the main resonant frequency, and the switching frequency of the switch tube of the rectifier side full bridge to be half of the main resonant frequency, so as to form a half-cycle feedback current circuit, wherein the main resonant frequency is also the rated resonant frequency;

[0030] S2, controls the PWM duty cycle of one of the single tubes on the switching tube of the full-bridge on the rectifier side, adjusts the output voltage and the energy storage time of the resonant cavity, controls the size of the resonant current pumping, further releases energy during transmission, and realizes the output voltage pumping.

[0031] Specifically, in an embodiment of the present invention, step S1 includes the steps of:

[0032] S11. A switching cycle of the full bridge on the rectifier side is twice the switching cycle of the full bridge on the inverter side. During the first positive switching cycle, the resonant cavity resonates, the switch tube has a soft switching characteristic, and energy is transferred in the positive direction until entering the first negative switching cycle.

[0033] S12. In the first negative switching cycle, through diode rectification, the resonant cavity involves the excitation inductance, and the resonant cycle changes. During this period, the current direction changes, creating conditions for the soft switching of the next inverter positive cycle.

[0034] The step S2 comprises the steps of:

[0035] S21, in the second positive switching cycle, the switch tube of the full bridge on the rectifier side is turned on, and the energy of the output capacitor is fed back to the resonant cavity to strengthen the resonant energy of the resonant cavity. The amount of injected energy is proportional to the duty cycle of the upper tube. When the upper tube is turned off, the current flows through the lower tube diode. At this time, the current does not pass through the output load;

[0036] S22. In the second negative switching cycle, energy is released based on the energy stored in the resonant cavity, and the current continues to flow through the switch tube of the full bridge on the rectifier side until the next switching cycle arrives.

[0037] Among them, as a preferred embodiment of the present invention, the PWM duty cycle of the switch tube of the inverter side full bridge is controlled to 47%, the PWM duty cycle of one of the upper tubes of the switch tube of the rectifier side full bridge is controlled to 0-23.5%, and the PWM duty cycle of the remaining tubes is controlled to 23.5%.

[0038] The present invention can avoid the situation where the tube current is too high in the wide under-resonance range or low inductance ratio of the traditional variable frequency control, and also avoid the problem that soft switching cannot be achieved in the phase shift control, and solve the problem that the traditional frequency modulation control cannot solve that efficiency and wide gain are difficult to balance. At the same time, for high-frequency applications, it avoids the adjustment of too wide a frequency range, brings convenience to the design of magnetic components, and has certain high-frequency and high-power density application potential.

[0039] In order to further illustrate the implementation principle of the present invention, the following is an example of a CLLC resonant conversion topology with a turn ratio of 2 to 1. The specific topology is as follows: Figure 1 As shown, the resonant conversion topology includes a CLLC resonant topology, and the topological structure includes an inverter side full bridge composed of switch tubes Q1 to Q4, and a switch tube Q SR1 ~Q SR4 The rectifier side full bridge is composed of the resonant inductor L r1 , resonant inductor L r2 , resonant capacitor C r1 and resonant capacitor C r2 The resonant structure is composed of Figure 1 As shown, one end of the primary side of the transformer is connected through the resonant inductor L r1 Connected to the connecting line between switch tube Q2 and switch tube Q4, the other end is connected through the resonant capacitor C r1 Connected to the connection line between switch tube Q1 and switch tube Q3. The two ends of the primary side of the transformer are connected in parallel with the excitation inductor L m , one end of the secondary side of the transformer is connected through the resonant inductor L r2 Connect to the switch tube Q SR1 And the switch tube Q SR3 The other end of the connecting line is connected through the resonant capacitor C r2 Connect to the switch tube Q SR2 And the switch tube Q SR4 The connecting line of the resonant capacitor C r1 , resonant capacitor C r2 , resonant inductor L r1 , resonant inductor L r2 The main resonant frequency of the construction is f r , the control frequency of the switch tubes Q1~Q4 is f r , the duty cycle is 47%, the switch tube Q SR1 ~Q SR4 The control frequency is f r / 2. As a preferred embodiment of the present invention, the switch tube Q SR2 The PWM duty cycle adjustment range of is 0-23.5%, and the PWM duty cycle of the other switch tubes is fixed at 23.5%. Through this setting, the effect of energy feedback to broaden the voltage gain can be achieved.

[0040] Figure 1 In, V in Indicates the input voltage, Figure 2 , Figure 3 The key waveform diagram of the cycle of the corresponding control method is shown in the figure, where V g1 ~V g4 is the driving voltage signal of the switch tubes Q1~Q4, V SR1 ~V SR4 Q is the switch tube SR1 ~Q SR4 The driving voltage signal I S1 is the current of the switch tube Q1; I Lr1 and I LM Respectively represent the current flowing through the resonant inductor L r and the magnetizing inductance L m The current I Ls is the current flowing through the secondary inductor L r2 The current, I SR1 and I SR2 Indicates the switch tube Q SR1 And the switch tube Q SR2 The current flowing through V out Indicates the output voltage.

[0041] like Figure 2 and Figure 3 As shown, during the period t0 to t1, which is the first positive half cycle of the switching cycle, the primary side (inverter side) V g1 、V g4 is high level, the switch tube Q1 and switch tube Q4 are turned on, corresponding to the secondary side (rectifier side) V SR1 、V SR4 is high level, the switch tube Q SR1 , switch tube Q SR4 The resonant inductor L is connected to the secondary side of the resonant cavity and the transformer. r1 , resonant inductor L r2 , resonant capacitor C r1 and resonant capacitor C r2 The resonant frequency is defined as the main resonant frequency f r (rated resonant frequency). Since the switching frequency is equal to the resonant frequency, the current in the resonant cavity is sinusoidal, and from the phase relationship between the current and the driving voltage, it can be found that the current lags behind the voltage, that is, the converter operates in the inductive range. In this process, the diode of the switch tube is turned on before the switch tube, and the switch tube voltage is pulled down and clamped to 0 to ensure soft switching. At this time, the secondary side switch tube is in a synchronous rectification state, and the current passes through the transformer and the resonant inductor L r2 , switch tube Q SR1 , load RL, switch tube Q SR4 Form a forward loop.

[0042] During the period from t1 to t2, this period is the dead time, and the moment t1 corresponds to V g1 、V g4 、V SR1 、V SR4 is low level, the switch tubes Q1, Q4, and Q SR1 , switch tube Q SR4 The primary side switch tube completes the charging and discharging of the output capacitor until the switch tubes Q2 and Q3 are turned on at time t2.

[0043] During the period t2 to t3, when V g2 and V g3 When the switching tube Q2 and the switching tube Q3 are turned on, the reverse resonance time is entered. Since the switching cycle of the secondary side is set to half, no switch tube is turned on in this stage, and the diode is uncontrolled for rectification. At this time, due to the freewheeling effect of the excitation inductance and the resonant inductance, the resonant cavity is reconstructed. The resonant cavity is composed of the resonant inductor L r1 , resonant inductor L r2 , resonant capacitor C r1 , Excitation inductance L m And resonant capacitor C r2 The resonant inductor is slowly discharged, and the resonant cavity current is reversed during this period, thereby establishing soft switching conditions for the opening of the switch tubes Q1 and Q4 corresponding to the second forward resonance.

[0044] During the period from t3 to t4, this period is the dead time, and the moment t3 corresponds to V g2 、V g3 becomes low level, the switch tubes Q2 and Q3 are turned off, and the primary side switch tube completes the charging and discharging of the output capacitor until V g1 、V g4 、V SR2 and V SR3 It becomes a high level and the corresponding switch tube is turned on.

[0045] During the period from t4 to t5, this stage is the energy feedback stage. At this time, the circuit forms an excitation inductance L m It is clamped again, and the resonant cavity changes again, becoming a resonant inductor L r1 , resonant inductor L r2 , resonant capacitor C r1 And resonant capacitor C r2 It should be noted that due to the change in the secondary side switch tube opening, the current direction changes compared to the first forward resonance, and the current passes through the transformer and the resonant inductor L r2 , switch tube Q SR3 , load RL, switch tube Q SR2A reverse loop is formed. At this time, the output capacitor discharges and feeds back part of the energy in the resonant cavity. The energy rises linearly until time t5. The switch tube Q SR2 Shut down.

[0046] During the period of t5 to t6, the resonant cavity does not change, but the secondary side path changes. SR2 Close, combined with the inductor freewheeling effect, the secondary side current passes through the transformer and the resonant inductor L r2 , switch tube Q SR3 , load RL and switch tube Q SR24 A reverse loop is formed. This stage is the input energy storage stage.

[0047] In the stage of t6 to t7, this period is the dead time, and t6 corresponds to V g1 、V g4 、V sr3 becomes low again, the corresponding switch tube is turned off, and the primary side switch tube completes the charging and discharging of the output capacitor until t7. g2 、V g3 It becomes a high level, and the switch tubes Q2 and Q3 are turned on.

[0048] In the stage of t7-t8, when the switch tube Q2 and the switch tube Q3 are turned on, the reverse resonance time is entered. Since the switching cycle of the secondary side is set to half, no switch tube is turned on in this stage, and the diode is not controlled for rectification. At this time, since the turn-off time in the previous stage is a negative value of the switch tube, the soft switching characteristic is lost at this time, but the secondary side diode is guaranteed to be turned on in time, the resonant cavity has not changed, and the negative cycle resonant cavity power flow transmission is carried out in this stage.

[0049] During the period from t8 to t9, this period is the dead time, and the moment t8 corresponds to V g2 、V g3 becomes low level, the switch tubes Q2 and Q3 are turned off, and the primary side switch tube completes the charging and discharging of the output capacitor until t9. g1 、V g4 、V SR1 and V SR4 It becomes a high level and the corresponding switch tube is turned on.

[0050] pass Figure 2 and Figure 3By comparison, it can be found that by adjusting the duty cycle of the switch tube QSR2, the output voltage can be effectively increased to ensure the realization of the fixed-frequency wide gain boost of the converter. The present invention avoids the situation where the tube current is too high due to the traditional frequency conversion control in a wider sub-resonance range or a lower inductance ratio, and also avoids the problem of being unable to achieve soft switching in phase shift control. It solves the problem that traditional frequency modulation control cannot solve that is difficult to balance efficiency and wide gain, and at the same time avoids excessively wide frequency range adjustment for high-frequency applications, which brings convenience to the design of magnetic components. It can meet the wide gain application requirements in high-frequency and high-power density power supply application fields such as DC power adapters in DC buildings and user-side energy storage converters.

[0051] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions only describe the principles of the present invention. The present invention may have various changes and improvements without departing from the spirit and scope of the present invention, and these changes and improvements fall within the scope of the present invention to be protected, and the scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. A novel differential fixed-frequency boost control method suitable for resonant conversion topology, characterized in that: Includes steps: S1. Determine the main resonant frequency according to the resonant parameters, configure the switching frequency of the switch tube of the inverter side full bridge to be the main resonant frequency, and the switching frequency of the switch tube of the rectifier side full bridge to be half of the main resonant frequency, so as to form a half-cycle feedback current circuit; S2, controls the PWM duty cycle of one of the single tubes on the switching tube of the full-bridge on the rectifier side, adjusts the output voltage and the energy storage time of the resonant cavity, controls the size of the resonant current pumping, further releases energy during transmission, and realizes the output voltage pumping.

2. The novel differential fixed-frequency boost control method applicable to resonant conversion topology according to claim 1 is characterized in that: The step S1 comprises the steps of: S11. A switching cycle of the full bridge on the rectifier side is twice the switching cycle of the full bridge on the inverter side. During the first positive switching cycle, the resonant cavity resonates, the switch tube has a soft switching characteristic, and energy is transferred in the positive direction until entering the first negative switching cycle. S12. In the first negative switching cycle, through diode rectification, the resonant cavity involves the excitation inductance, and the resonant cycle changes. During this period, the current direction changes, creating conditions for the soft switching of the next inverter positive cycle.

3. The novel differential fixed-frequency boost control method applicable to resonant conversion topology according to claim 1 is characterized in that: The step S2 comprises the steps of: S21, in the second positive switching cycle, the switch tube of the full bridge on the rectifier side is turned on, and the energy of the output capacitor is fed back to the resonant cavity to strengthen the resonant energy of the resonant cavity. The amount of injected energy is proportional to the duty cycle of the upper tube. When the upper tube is turned off, the current flows through the lower tube diode. At this time, the current does not pass through the output load; S22. In the second negative switching cycle, energy is released based on the energy stored in the resonant cavity, and the current continues to flow through the switch tube of the full bridge on the rectifier side until the next switching cycle arrives.

4. According to the novel differential constant-frequency boost control method suitable for resonant conversion topology described in claim 1, the PWM duty cycle of the switch tube of the inverter side full bridge is controlled to 47%, the PWM duty cycle of one of the upper tubes of the switch tube of the rectifier side full bridge is controlled to 0-23.5%, and the PWM duty cycle of the remaining tubes is controlled to 23.5%.

5. According to the novel differential fixed-frequency boost control method applicable to the resonant conversion topology of claim 1, the resonant conversion topology includes a CLLC resonant topology, and the topological structure includes an inverter side full bridge composed of switch tubes Q1 to Q4, and a switch tube Q SR1 ~Q SR4 The rectifier side full bridge is composed of the resonant inductor L r1 , resonant inductor L r2 , resonant capacitor C r1 and resonant capacitor C r2 The resonant structure is formed, and one end of the primary side of the transformer is connected through the resonant inductor L r1 Connected to the connecting line between switch tube Q2 and switch tube Q4, the other end is connected through the resonant capacitor C r1 Connected to the connecting line of switch tube Q1 and switch tube Q3, the two ends of the primary side of the transformer are connected in parallel with the excitation inductor L m , one end of the secondary side of the transformer is connected through the resonant inductor L r2 Connect to the switch tube Q SR1 And the switch tube Q SR3 The other end of the connecting line is connected through the resonant capacitor C r2 Connect to the switch tube Q SR2 And the switch tube Q SR4 on the connection line.

6. The novel differential fixed-frequency boost control method applicable to resonant conversion topology according to claim 5 is characterized in that: By the resonant capacitor C r1 , resonant capacitor C r2 , resonant inductor L r1 , resonant inductor L r2 The main resonant frequency of the construction is f r , the control frequency of the switch tubes Q1~Q4 is f r , the duty cycle is 47%, the switch tube Q SR1 ~Q SR4 The control frequency is f r / 2, where the switch tube Q SR2 The PWM duty cycle adjustment range of the switch is 0 to 23.5%, and the PWM duty cycle of the other switch tubes is fixed at 23.5%.

7. The novel differential fixed-frequency boost control method applicable to resonant conversion topology according to claim 5 is characterized in that: In the first positive half of the switching cycle, the driving voltage signal V g1 And the driving voltage signal V of the switch tube Q4 g4 The switch tube Q1 and the switch tube Q4 are turned on, and the corresponding switch tube Q on the full bridge on the rectifier side is SR1 The driving voltage signal V sr1 And the switch tube Q SR4 The driving voltage signal V sr4 is high level, the switch tube Q SR1 And the switch tube Q SR4 The power is transferred to the secondary side through the resonant cavity and the transformer. At this time, the resonant cavity is connected by the resonant inductor L r1 , resonant inductor L r2 , resonant capacitor C r1 and resonant capacitor C r2 The resonant frequency is the main resonant frequency f r , pull the switch tube voltage down to 0 to ensure soft switching, and the current passes through the transformer and resonant inductor L r2 , switch tube Q SR1 , load RL, switch tube Q SR4 Form a forward loop.

8. The novel differential fixed-frequency boost control method applicable to resonant conversion topology according to claim 5 is characterized in that: At the reverse resonance time, the resonant cavity is reconstructed by the resonant inductor L r1 , resonant inductor L r2 , resonant capacitor C r1 , Excitation inductance L m And resonant capacitor C r2 The composition of the resonant inductor L r1 , L r2 A slow discharge is performed, during which the resonant cavity current reverses, creating soft switching conditions for the opening of the switch tubes Q1 and Q4 corresponding to the second forward resonance.

9. The novel differential fixed-frequency boost control method applicable to resonant conversion topology according to claim 5 is characterized in that: In the energy feedback stage, the resonant cavity is reconstructed by the resonant inductor L r1 , resonant inductor L r2 , resonant capacitor C r1 And resonant capacitor C r2 The current passes through the transformer and the resonant inductor L r2 , switch tube Q SR3 , load RL, switch tube Q SR2 A reverse loop is formed, and the output capacitor C0 discharges and feeds back part of the energy into the resonant cavity.

10. The novel differential fixed-frequency boost control method applicable to resonant conversion topology according to claim 5, characterized in that: In the input energy storage stage, the resonant cavity is composed of the resonant inductor L r1 , resonant inductor L r2 , resonant capacitor C r1 and resonant capacitor C r2 The secondary current passes through the transformer and the resonant inductor L r2 , switch tube Q SR3 , load RL and switch tube Q SR24 Form a reverse loop.

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