CN-122026729-A - CLLC resonant converter control method and system based on passive control

CN122026729ACN 122026729 ACN122026729 ACN 122026729ACN-122026729-A

Abstract

The invention provides a passive control-based CLLC resonant converter control method and system. The system comprises a CLLC resonant converter main circuit, a sampling module, a controller and a driving circuit, wherein the sampling module is used for acquiring input voltage, output voltage and output current of the CLLC resonant converter in real time, the controller is used for determining the current working mode of the CLLC resonant converter and respectively determining corresponding switching frequency and phase shifting angle according to the determined working mode to generate driving signals, and the driving circuit is used for respectively controlling a primary side switching tube and a secondary side switching tube of the CLLC resonant converter according to the driving signals output by the controller to realize closed-loop control of the CLLC resonant converter. The invention gets rid of the dependence on a small signal linearization model, and remarkably improves the dynamic response speed and the global stability of the system under large signal disturbance by injecting the energy function of the virtual damping remodelling system.

Inventors

WANG CHENG
ZHU LIJIN
LI JINGZHE
XU JIAHAO
MA XUJUN
LI XIAOWEI
ZHANG KAI
FANG XIONGFENG

Assignees

南京理工大学

Dates

Publication Date: 20260512
Application Date: 20260212

Claims (8)

1. The control method of the CLLC resonant converter based on the passive control is characterized by comprising the following steps of: step 1, constructing a gain-frequency lookup table offline, wherein the gain-frequency lookup table takes voltage gain and quality factor as input indexes and normalized frequency as output; Step 2, acquiring input voltage, output voltage and output current of the CLLC resonant converter in real time, calculating target voltage gain required by the CLLC resonant converter to maintain energy balance, determining the current working mode of the CLLC resonant converter, if the CLLC resonant converter works under normal load, performing step 3, judging the working condition to be light load or no-load, and performing step 4; Step 3, determining a normalized frequency from a gain-frequency lookup table according to a target voltage gain required by the CLLC resonant converter to maintain energy balance and a quality factor estimated in real time, thereby determining a switching frequency, and setting a phase shift angle to 0 at the same time, and performing step 5; step 4, locking the switching frequency to be Calculating a phase shift angle between a primary side bridge arm and a secondary side bridge arm according to a target voltage gain required by the CLLC resonant converter to maintain energy balance; And 5, generating driving signals to respectively control the primary side switching tube and the secondary side switching tube according to the determined switching frequency and phase shift angle, so as to realize closed-loop control of the CLLC resonant converter.
2. The control method of a CLLC resonant converter based on passive control according to claim 1, wherein the relationship between the voltage gain and the quality factor in the gain-frequency lookup table and the normalized frequency is specifically: In the formula, Is the voltage gain; is normalized frequency; Is the inductance ratio; is the figure of merit.
3. The control method of CLLC resonant converter based on passive control according to claim 1, wherein the calculation method of target voltage gain required for CLLC resonant converter to maintain energy balance is: (1) Construction of open-loop port Hamiltonian System equation According to kirchhoff's law, a state equation of the CLLC resonant converter is established: Wherein the method comprises the steps of 、、 Respectively acquiring input voltage, output voltage and output current of the CLLC resonant converter in real time; Is the target voltage gain; Is primary side resonant inductance Is set to be a current of (a); Representative of When the symbol of (b) When it is positive, when Negative in time; Secondary resonant inductor for conversion to primary side Current of (a), i.e Wherein For actually flowing through Is set to be a current of (a); Secondary resonant inductor for conversion to primary side I.e. ; For exciting inductance Is set to be a current of (a); Is primary side resonance capacitor Is a voltage of (2); For conversion to secondary side resonance capacitance of primary side Voltage of (i.e.) Wherein Secondary side resonance capacitor as primary side The voltage across the terminals; For conversion to secondary side resonance capacitance of primary side I.e. ; The state equation of the CLLC resonant converter is arranged into a matrix form to obtain the Hamiltonian comprising the inductance, the capacitance and the total energy stored by the coupling elements in the network Anti-symmetric interconnection matrix reflecting energy exchange structure inside system Positive damping matrix reflecting inherent loss characteristics of system Input matrix representing external input to system state access mode Control input quantity ; According to the arranged matrix, a port controlled Hamiltonian model of the CLLC resonant converter is established, and inductance current and capacitance voltage are selected as state variables The open-loop port hamilton system equation is described as: In the formula, Output for the CLLC resonant converter system; (2) Construction of closed-loop port Hamiltonian system model To track the reference value of the system output voltage Selecting Corresponding state As the expected balance point of the system, and constructing a closed-loop port Hamiltonian system model so that the closed-loop system is in Asymptotically stable: In the formula, Is a desired energy function of a closed loop system and satisfies At the desired balance point The following conditions are satisfied: Wherein, the Is the desired equilibrium point; As a function of the energy injected into the system; Is an anti-symmetric interconnection matrix, and satisfies , Here order ; Is a desired positive damping matrix and meets , ; To inject an interconnect matrix for reshaping the internal energy coupling structure of the system; for injecting a damping matrix, introducing virtual damping to the system to accelerate error convergence; Order the Wherein For injection damping of the primary side of the transformer, Is injection damping of the secondary side of the transformer and meets ; (3) Simultaneous open loop port hamilton system equation Hamiltonian system model with closed loop port Obtaining a control amount : According to the passive control principle, the open loop system is controlled to input Under the action of (a), the expected closed loop Hamiltonian dynamics characteristics are satisfied, namely, the following steps: substituting the matrix equation to obtain: due to open-loop port hamilton equation Comprises Inverse solving the control amount required for maintaining energy balance I.e. the target voltage gain required by the CLLC resonant converter to maintain energy balance: Wherein the method comprises the steps of The damping is injected into the secondary side of the device, In the form of a turn ratio of a transformer, 、、 Respectively input voltage, output voltage and output current which are acquired in real time, Is the output voltage reference.
4. The control method of the CLLC resonant converter based on the passive control according to claim 1, wherein the specific method for determining the current working mode of the CLLC resonant converter is as follows: output voltage to be collected in real time And a load voltage threshold A comparison is made to determine the current mode of operation when When the load is judged to be the normal load working condition, executing the step 3, and when And (4) judging the working condition to be light load or no-load, and executing the step (4).
5. The method for controlling a CLLC resonant converter based on passive control of claim 1, wherein the switching frequency in step 3 The method comprises the following steps: In the formula, For a normalized frequency corresponding to the target voltage gain required for the CLLC resonant converter to maintain energy balance, Is the series resonant frequency of the CLLC resonant converter.
6. The method for controlling a CLLC resonant converter based on passive control according to claim 1, wherein in step 4, the phase shift angle between the primary leg and the secondary leg is calculated according to the target voltage gain required for maintaining energy balance of the CLLC resonant converter The specific method of (a) is as follows: operating in buck mode, target voltage gain, based on phase-shift control gain characteristics of CLLC resonant converters Phase shift angle between primary side bridge arm and secondary side bridge arm The following relationships are satisfied: the switching frequency is set Locked at No longer follows the look-up table change, at this time ; The method further comprises the following steps: 。
7. A CLLC resonant converter control system based on passive control, for executing the control method according to any one of claims 1 to 6, comprising: CLLC resonant converter main circuit; The sampling module is used for collecting the input voltage, the output voltage and the output current of the CLLC resonant converter in real time; The controller is used for determining the current working mode of the CLLC resonant converter, respectively determining the corresponding switching frequency and phase shift angle according to the determined working mode and generating a driving signal; And the driving circuit is used for respectively controlling the primary side switching tube and the secondary side switching tube of the CLLC resonant converter according to the driving signals output by the controller, so as to realize closed-loop control of the CLLC resonant converter.
8. The passive control-based CLLC resonant converter control system of claim 7, wherein the CLLC resonant converter main circuit comprises a primary side full-bridge inverter circuit, a resonant network, a high-frequency isolation transformer circuit and a secondary side full-bridge rectifier circuit which are sequentially connected, wherein an input end of the primary side full-bridge inverter circuit is connected with an input power supply.

Description

CLLC resonant converter control method and system based on passive control Technical Field The invention belongs to the technical field of power electronic converter control, and particularly relates to a passive control-based CLLC resonant converter control method and system. Background Along with the rapid development of the vehicle-mounted charger, the distributed energy storage system and the direct-current micro-grid of the new energy automobile, the high-efficiency DC/DC converter which can realize energy bidirectional flow and has an electrical isolation function becomes a research hot spot. The CLLC resonant converter is an ideal bidirectional converter topology by virtue of excellent bidirectional symmetry, soft switching characteristics in a full load range and higher power density. However, CLLC resonant converters are essentially a high-order, strongly nonlinear, multivariable coupled system. Conventional control strategies mainly employ PI (proportional-integral) control, the design of which typically relies on a small signal linearization model established at a specific steady-state operating point. This control method based on linearization model has obvious limitations. Firstly, when the working point of the converter is subjected to wide-range changes such as wide-voltage-range input or large-fluctuation load, the fixed PI parameters are difficult to ensure the dynamic performance and stability of the system, secondly, in order to maintain the stability of the system, the PI control often has to reduce the bandwidth, so that the dynamic response of the system is slow, the overshoot is large and the recovery time is long when the load is suddenly changed or the mode is switched, and in addition, under the light-load or no-load working condition, the gain characteristic curve of the CLLC converter is gentle, the simple variable-frequency control regulation capability is limited, and the instability of the output voltage is easy to be caused. Disclosure of Invention The invention aims to provide a passive control-based CLLC resonant converter control method, which aims to overcome the defects of poor dynamic performance, difficult parameter setting and weak disturbance rejection of the traditional linear control in the prior art. The technical scheme for realizing the purpose of the invention is that the CLLC resonant converter control method based on passive control comprises the following steps: step 1, constructing a gain-frequency lookup table offline, wherein the gain-frequency lookup table takes voltage gain and quality factor as input indexes and normalized frequency as output; step 2, acquiring input voltage, output voltage and output current of the CLLC resonant converter in real time, calculating target voltage gain, determining the current working mode of the CLLC resonant converter, if the CLLC resonant converter works under normal load, performing step 3, judging the working condition to be light load or no load, and performing step 4; Step 3, determining a normalized frequency from a gain-frequency lookup table according to a target voltage gain required by the CLLC resonant converter to maintain energy balance and a quality factor estimated in real time, thereby determining a switching frequency, and setting a phase shift angle to 0 at the same time, and performing step 5; Step 4, locking the switching frequency to a preset value, and calculating a phase shift angle between a primary side bridge arm and a secondary side bridge arm according to a target voltage gain required by the CLLC resonant converter to maintain energy balance; And 5, generating driving signals to respectively control the primary side switching tube and the secondary side switching tube according to the determined switching frequency and phase shift angle, so as to realize closed-loop control of the CLLC resonant converter. The invention also provides a CLLC resonant converter control system based on passive control, which comprises: CLLC resonant converter main circuit; The sampling module is used for collecting the input voltage, the output voltage and the output current of the CLLC resonant converter in real time; The controller is used for determining the current working mode of the CLLC resonant converter, respectively determining the corresponding switching frequency and phase shift angle according to the determined working mode and generating a driving signal; And the driving circuit is used for respectively controlling the primary side switching tube and the secondary side switching tube of the CLLC resonant converter according to the driving signals output by the controller, so as to realize closed-loop control of the CLLC resonant converter. Compared with the prior art, the invention has the remarkable advantages that: (1) The invention designs the controller based on the passive control principle from the system energy point of view, does not depend on a small signal linearization model, and can a