CN-121689837-B - Control method for wide-voltage operation of CLLC resonant converter

CN121689837BCN 121689837 BCN121689837 BCN 121689837BCN-121689837-B

Abstract

The invention relates to the technical field of power electronics, and discloses a control method for wide-voltage operation of a CLLC resonant converter. In the CLLC resonant converter, a primary side homonymous terminal is connected to an emitter of a switching tube Q1 and a collector of the switching tube Q2, a heteronymous terminal is connected to an emitter of a switching tube Q3 and a collector of the switching tube Q4, a secondary side homonymous terminal is connected to an emitter of the switching tube S1 and a collector of the switching tube S2, and the heteronymous terminal is connected to an emitter of the switching tube S3 and a collector of the switching tube S4. The circuit has simple structure, can effectively widen the voltage gain range, realizes higher voltage gain with lower loss and cost, is more suitable for wide-range voltage operation, and has higher stability.

Inventors

LUO HUAN
LIU YANG
ZHANG MIAO
Ai Gaomin
ZOU YULIN
MA HAIYUE
Liu Cekai
ZHANG JIESONG

Assignees

四川大学

Dates

Publication Date: 20260508
Application Date: 20260209

Claims (8)

1. In the CLLC resonant converter, a primary side homonymous terminal is connected to an emitter of a switching tube Q1 and a collector of a switching tube Q2, a primary side homonymous terminal is connected to an emitter of a switching tube Q3 and a collector of a switching tube Q4, a secondary side homonymous terminal is connected to an emitter of a switching tube S1 and a collector of a switching tube S2, and a secondary side homonymous terminal is connected to an emitter of the switching tube S3 and a collector of the switching tube S4; The method is characterized in that the O mode of the PO mode is as follows: When the output voltage of the secondary side is greater than zero in the positive half period, the phase difference is advanced relative to the ending phase of the O mode Switching on the switching tube S2; When the output voltage of the secondary side is smaller than zero in the negative half period, the phase difference is advanced relative to the ending phase of the O mode Switching on the switching tube S1; the control method of the switching tube S1 and the switching tube S2 comprises the following steps: collecting output voltage of CLLC resonant converter Inputting the error amplifier to obtain the switching frequency ; The switching frequency is set Input sawtooth wave generator for generating sawtooth carrier Input to the non-inverting input of the second comparator to switch the frequency Input comparison generator for generating modulation wave An inverting input terminal of the second comparator; connecting the output terminal of the second comparator to the clock terminal of the D trigger; the D end of the D trigger is connected to a non-Q end, the non-Q end is connected to a first input end of a second AND gate through a second NOT gate, the Q end is connected to a first input end of a first AND gate through a first NOT gate, and the clock end is connected to second input ends of the first AND gate and the second AND gate; the first driving circuit generates a driving signal The second driving circuit generates a driving signal by controlling the switch tube S1 A control switch tube S2; wherein the saw tooth carrier wave Modulated wave Is of the phase difference of (a) 。
2. The control method for wide-voltage operation of a CLLC resonant converter of claim 1, wherein the phase difference Equal to the phase difference between the initial phase and the end phase of the O mode.
3. A control method for a CLLC resonant converter wide voltage operation as claimed in claim 1, characterized by determining the phase difference The formula of (2) is as follows: ; ; ; in the formula, Is a coefficient of proportionality and is used for the control of the power supply, , In order to normalize the switching frequency, For normalizing the set minimum value of the switching frequency, For the switching frequency to be the switching frequency, At the frequency of the resonance and, Is used as a control coefficient of the proportion, In order to integrate the control coefficient(s), For the output voltage of the CLLC resonant converter, As a reference voltage to be applied to the circuit, The duration of time is indicated and, Representing the differential amount of time.
4. A method for controlling a wide voltage operation of a CLLC resonant converter as claimed in claim 3, wherein the switching frequency is set to Input comparison generator for generating modulation wave Comprising: ; ; in the formula, Representing a clipping function.
5. A control method for CLLC resonant converter wide voltage operation as claimed in claim 3, wherein said first and second driving circuits are gate driving chips; The isolation power supply is connected to the gate driving chip through the gate driving resistor to supply power to the gate driving chip.
6. A control method for wide-voltage operation of a CLLC resonant converter as claimed in claim 3, further comprising control methods of switching tube Q1, switching tube Q2, switching tube Q3 and switching tube Q4: will saw tooth carrier wave The inverting input end of the first comparator is grounded, and the output end is connected to the clock end of the JK trigger; the J end and the K end of the JK trigger are connected to the power supply voltage, and the Q end and the non-Q end of the JK trigger are respectively connected to the third driving circuit and the fourth driving circuit; the third driving circuit generates a driving signal Control the switching tube Q1 and the switching tube Q4, and the fourth driving circuit generates a driving signal The switching tube Q2 and the switching tube Q3 are controlled.
7. The method of claim 6, wherein the third driving circuit and the fourth driving circuit are gate driving chips; The isolation power supply is connected to the gate driving chip through the gate driving resistor to supply power to the gate driving chip.
8. A method of controlling wide voltage operation of a CLLC resonant converter as claimed in any one of claims 3 to 7, wherein the switching frequency is set to Input sawtooth wave generator for generating sawtooth carrier The method specifically comprises the following steps: for switching frequency Proportional control is carried out to obtain a frequency signal Then reset by a reset key to generate a sawtooth carrier ; Will saw tooth carrier wave Inputting the signal to the non-inverting input end of the third comparator, and inputting pi-shaped filtering to the inverting input end of the third comparator; the input of the third comparator is connected to the reset key.

Description

Control method for wide-voltage operation of CLLC resonant converter Technical Field The invention relates to the technical field of power electronics, in particular to a control method for wide-voltage operation of a CLLC resonant converter. Background The CLLC resonant converter has a simple topological structure, can realize the soft switching of a primary switching tube and a secondary rectifying tube, supports the bidirectional transmission of V2G energy, and is widely applied to an On-Board Charger (OBC) of an electric automobile. The continuous development of the electric automobile charging technology brings forward wider requirements on the working voltage range of a rear-stage DC/DC converter device of the vehicle-mounted charger. In terms of converter topology, to obtain higher voltage gain, some additional components can be added on the basis of CLLC resonant converters. However, adding components tends to add additional cost and complexity, and may lose soft switching under the PFM (Pulse Frequency Modulation, pulse frequency control) control strategy, resulting in increased converter losses. In the modeling analysis method, the parameter design of the existing CLLC resonant converter is mostly dependent on frequency domain analysis, but has limited precision and larger error, and the design result is often required to be subjected to repeated iterative correction, so that the method is not suitable for the situation that the switching frequency deviates from the resonant frequency too far. In terms of control strategy, the most widely used control strategy for CLLC resonant converters is PFM. When the CLLC resonant converter works near the resonant frequency, the control mode has the advantages of high converter efficiency, simple control and the like, but when the CLLC resonant converter needs to output higher voltage, the switching frequency of the CLLC resonant converter can deviate from the resonant frequency seriously, so that the design difficulty of the magnetic element is increased, and the converter efficiency is reduced obviously. Since the conventional PFM control strategy only controls the switching frequency variation, the voltage regulation capability is limited. In summary, the conventional CLLC resonant converter has the following limitation in terms of widening the voltage gain range that additional components are generally introduced in the topology aspect, so that the structure is complicated and the loss is increased, and in terms of control strategy, the conventional CLLC resonant converter mostly adopts PFM control, and the output voltage is controlled by adjusting the switching frequency, but in order to realize higher voltage gain, the switching frequency is often greatly reduced, and the switching frequency is seriously deviated from the resonant frequency, so that the efficiency is affected. Disclosure of Invention In order to solve the technical problems in the prior art, the invention aims to provide a control method for the wide-voltage operation of a CLLC resonant converter, which can operate under a wider range of voltage, supports the deep discharge of an electric automobile battery, has high stability, does not need to introduce additional components and parts, and avoids the complicated structure and the increase of loss. Specifically, the invention provides a control method for the wide-voltage operation of a CLLC resonant converter, which has the following technical scheme: In the CLLC resonant converter, a primary side homonymous end is connected to an emitter of a switching tube Q1 and a collector of a switching tube Q2, a primary side heteronymous end is connected to an emitter of a switching tube Q3 and a collector of a switching tube Q4, a secondary side homonymous end is connected to an emitter of a switching tube S1 and a collector of a switching tube S2, and a secondary side heteronymous end is connected to an emitter of a switching tube S3 and a collector of a switching tube S4; The O mode of the PO mode is: When the output voltage of the secondary side is greater than zero in the positive half period, the phase difference is advanced relative to the ending phase of the O mode Switching on the switching tube S2; When the output voltage of the secondary side is smaller than zero in the negative half period, the phase difference is advanced relative to the ending phase of the O mode The switching tube S1 is turned on. Compared with the prior art, the technical scheme provided by the invention has a simple structure, components are not added on the basis of the topological structure of the traditional CLLC resonant converter, only one of a group of synchronous switching tubes on the secondary side is conducted in advance under the O mode by adjusting the O mode of the PO mode of the CLLC resonant converter, the secondary side resonant cavity clamp is in a zero voltage state, the voltage gain range of the CLLC resonant converter can be effectively widen