CN117458887B - Global optimal control method and system for three-level resonant converter - Google Patents

Global optimal control method and system for three-level resonant converter Download PDF

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CN117458887B
CN117458887B CN202311755293.XA CN202311755293A CN117458887B CN 117458887 B CN117458887 B CN 117458887B CN 202311755293 A CN202311755293 A CN 202311755293A CN 117458887 B CN117458887 B CN 117458887B
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pulse width
switch tube
converter
resonant converter
normalized
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CN117458887A (en
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胡松
韩磊
刘继承
鲁明丽
丑永新
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Changshu Institute of Technology
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Changshu Institute of Technology
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0048—Circuits or arrangements for reducing losses
    • H02M1/0054—Transistor switching losses
    • H02M1/0058—Transistor switching losses by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/01—Resonant DC/DC converters
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

The invention discloses a global optimal control method for a three-level resonant converter, which comprises the following steps: obtaining an equivalent power model by a modulation method aiming at the three-level resonant converter; performing optimization control on the obtained equivalent power model to obtain a loss optimal path; different working modes are obtained through different control angle combinations, and final optimization is completed through mode optimization output loop-free mode, so that a global optimal control angle is obtained. The invention can ensure that the switching tube realizes soft switching under the wide voltage gain range of the three-level resonant converter, thereby reducing switching loss; and the converter is enabled to always operate in a loss optimal path; meanwhile, the circulating power of the primary side and the secondary side of the converter is completely eliminated, and the overall operation efficiency of the converter is improved.

Description

Global optimal control method and system for three-level resonant converter
Technical Field
The invention relates to the technical field of optimal control of DC-DC converters, in particular to a global optimal control method and a global optimal control system for a three-level resonant converter.
Background
At present, common new energy automobiles are mainly divided into oil-electricity hybrid electric automobiles and pure electric automobiles. The gas generated in the running process of the pure electric vehicle has little pollution to the environment, for example, the hydrogen fuel cell vehicle only generates water and heat in the running process and does not generate other polluted gas.
In a hydrogen fuel cell vehicle, a hydrogen fuel cell is a main power source, but the electric energy output by the hydrogen fuel cell is unstable, so that the electric energy cannot be directly supplied to the vehicle. In order to be able to match the output of the hydrogen fuel cell to the requirements of the vehicle, it is necessary to convert the electrical energy output from the hydrogen fuel cell using a DC-DC converter. The conventional DC-DC converter has the defects of low output power, large input current ripple, large output voltage ripple and the like. Therefore, the research on the optimal control method applied to the DC-DC converter can enable the output power of the hydrogen fuel cell to meet the requirements of the electric automobile, and has important theoretical significance and practical value.
Disclosure of Invention
The invention aims to provide a global optimal control method and a global optimal control system for a three-level resonant converter, which can meet the requirement of stable and wide voltage range of output electric energy, ensure that a switching tube realizes soft switching, reduce switching loss, ensure that the converter always operates in an optimal path of loss, completely eliminate the circulating power of a primary side and a secondary side of the converter, and improve the overall operation efficiency of the converter.
The technical solution for realizing the purpose of the invention is as follows:
a global optimal control method for a three-level resonant converter, comprising the steps of:
s01: obtaining an equivalent power model by a modulation method aiming at the three-level resonant converter;
s02: performing optimization control on the obtained equivalent power model to obtain a loss optimal path;
s03: different working modes are obtained through different control angle combinations, and final optimization is completed through mode optimization output loop-free mode, so that a global optimal control angle is obtained.
In a preferred embodiment, a dual-step modulation method is adopted in the step S01, and the method includes:
s11: switching tube for controlling primary side of three-level resonant converterIs 0 to +.>Switch tube->Pulse width of +.>To->Switch tube->Pulse width of +.>To->Switch tube->Pulse width of +.>To the point ofSwitch tube->Pulse width of +.>To->Switch tube->Pulse width of +.>To->The method comprises the steps of carrying out a first treatment on the surface of the Thereby generating an alternating voltage +.>Contains->、/>、0、/>、/>Five voltage levels, ">For input voltage +.> ，/>Is pulse width;
s02: switching tube for controlling secondary side of three-level resonant converterAnd->Pulse width of +.>To->Switch tube->And->Pulse width of +.>To->And switch tube->、/>Hysteresis switch tube->The angle is->Thereby generating an alternating voltage +.>；
S03: will resonate the currentIs set at the zero crossing of the switching tube>、/>And->So that the resonance current is +.>、/>、/>In phase, the cyclic power of the primary side and the secondary side of the converter is eliminated.
In a preferred technical solution, the method for obtaining the equivalent power model in the step S01 includes:
performing steady-state analysis on the three-level resonant converter by using a fundamental wave approximation method, and establishing an equivalent circuit model of the three-level resonant converter in a phasor domain to obtainAnd->Fundamental phasors of two voltages, +.>And->The normalized phasor expression is as follows:
in the method, in the process of the invention,is->Normalized phasors of>Is->Normalized phasors of>For the number of turns of the transformer, ">Is the voltage gain;
according to normalized switching frequencyNormalized quality factor->The normalized impedance of the capacitor is obtained:；
wherein,for the switching angular frequency of the switch,/>for normalizing the resonance angular frequency +.>Is externally connected with a resonance capacitor>Is externally connected with a resonant inductor>For normalizing the impedance +.>Is a load resistance;
obtaining a normalized resonance current expression according to a phasor domain equivalent circuit model of the three-level resonance converter;
wherein,for peak current +.>For resonance current +.>With alternating voltage->Is a phase shift angle of (2);
calculating normalized power：
。
In a preferred embodiment, the method of optimizing control in step S02 includes obtaining an equation set of control coordinates that minimizes an effective value of the resonant current based on a change in power and current according to a change in control coordinates.
In a preferred technical scheme, the equation expression of the optimization control algorithm is:
in the method, in the process of the invention,to control angle->For resonance current +.>The square of the effective value is used to determine,
，
will be、/>、/>Substituting the expression into an equation of the optimization control algorithm to obtain an equation set of the optimization control algorithm:
the optimal path expression of loss is obtained by simplifying the equation set of the optimization control algorithm, and is as follows:
。
in a preferred embodiment, the step S03 includes controlling a control angle of the inverterThe converter realizes the operation without backflow power, and the loss optimal path expression is further optimized as follows:
。
in a preferred technical solution, the step S03 further includes controlling the global loss optimal path, and the control method includes:
substituting the optimized loss optimal path relation into normalized powerSimplifying to obtain global loss optimal power：
By controllingPulse width +.>Controlling global loss optimum power->Is of a size of (a) and (b).
The invention also discloses a global optimal control system for the three-level resonant converter, which comprises the following components:
the equivalent power model calculation module is used for obtaining an equivalent power model by a modulation method aiming at the three-level resonant converter;
the optimization control module performs optimization control on the obtained equivalent power model to obtain a loss optimal path;
and the global optimal control module obtains different working modes through different control angle combinations, and finally optimizes the overall optimal control angle through mode optimization output loop-free mode.
In a preferred technical scheme, the optimization control method of the optimization control module comprises the steps of obtaining an equation set of control coordinates which enables the effective value of the resonance current to be minimum on the basis that the power and the current change along with the change of the control coordinates;
the equation expression of the optimization control algorithm is as follows:
in the method, in the process of the invention,to control angle->For resonance current +.>The square of the effective value is used to determine,
，
will be、/>、/>Substituting the expression into an equation of the optimization control algorithm to obtain an equation set of the optimization control algorithm:
the optimal path expression of loss is obtained by simplifying the equation set of the optimization control algorithm, and is as follows:
the invention also discloses a computer storage medium, on which a computer program is stored, which when executed implements the global optimum control method for a three-level resonant converter.
Compared with the prior art, the invention has the remarkable advantages that:
(1) The global optimal control method suitable for the three-level resonant converter can completely eliminate the circulating power of the primary side and the secondary side of the converter in the application of high voltage and high power range, so that the current stress is minimized, and the conduction loss of the converter is reduced.
(2) The invention can realize the soft switching of the switching tube of the three-level resonant converter in the full power range, reduce the switching loss of the converter and improve the operation efficiency of the converter.
(3) The invention can optimize the control angles of three degrees of freedom, can realize more accurate control of the converter and improves the system performance.
Drawings
FIG. 1 is a functional block diagram of a global optimum control method for a three-level resonant converter;
FIG. 2 is a circuit topology of a three-level resonant converter;
FIG. 3 is a waveform diagram of the operation of a three-level resonant converter using a two-step modulation method;
FIG. 4 is an equivalent circuit model of a three-level resonant converter built under the phasor domain using fundamental approximation;
FIG. 5 is a schematic diagram of a preferred embodiment of the present invention，/>，/>，/>，/>、/>、/>And each switching tube current waveform diagram;
FIG. 6 is a diagram，/>，/>，/>，/>、/>、/>And each switching tube current waveform diagram;
FIG. 7 is a schematic diagram of a preferred embodiment of the present invention，/>，/>，/>，/>、/>、/>And a current waveform diagram of each switching tube.
Detailed Description
The principle of the invention is as follows: applying a double-step modulation method to the three-level resonant converter to obtain an equivalent power model; optimizing the equivalent power model by using an optimization control algorithm to obtain a loss optimal path; and outputting a loop-free mode through a mode optimization method to finish final optimization, so as to obtain a global optimal control angle. The invention can ensure that the switching tube realizes soft switching under the wide voltage gain range of the three-level resonant converter, thereby reducing switching loss; and the converter is enabled to always operate in a loss optimal path; meanwhile, the circulating power of the primary side and the secondary side of the converter is completely eliminated, and the overall operation efficiency of the converter is improved.
Example 1:
as shown in fig. 1, a global optimum control method for a three-level resonant converter includes the steps of:
s01: obtaining an equivalent power model by a modulation method aiming at the three-level resonant converter;
s02: performing optimization control on the obtained equivalent power model to obtain a loss optimal path;
s03: different working modes are obtained through different control angle combinations, and final optimization is completed through mode optimization output loop-free mode, so that a global optimal control angle is obtained.
The topology of the three-level resonant converter is shown in fig. 2. The topology of the converter is conventional and will not be described in detail here.
In a preferred embodiment, a two-step modulation method is used in step S01, and the method includes:
s11: switching tube for controlling primary side of three-level resonant converterIs 0 to +.>Switch tube->Pulse width of +.>To->Switch tube->Pulse width of +.>To->Switch tube->Pulse width of +.>To the point ofSwitch tube->Pulse width of +.>To->Switch tube->Pulse width of +.>To->The method comprises the steps of carrying out a first treatment on the surface of the Thereby generating an alternating voltage +.>Contains->、/>、0、/>、/>Five voltage levels, as shown in fig. 3, < >>For input voltage +.> ，/>Is pulse width;
s02: switching tube for controlling secondary side of three-level resonant converterAnd->Pulse width of +.>To->Switch tube->And->Pulse width of +.>To->And switch tube->、/>Hysteresis switch tube->The angle is->Thereby generating an alternating voltage +.>；
S03: will resonate the currentIs set at the zero crossing of the switching tube>、/>And->So that the resonance current is +.>、/>、/>In phase, the cyclic power of the primary side and the secondary side of the converter is eliminated.
In a preferred embodiment, the method for obtaining the equivalent power model in step S01 includes:
steady-state analysis is carried out on the three-level resonant converter by applying a fundamental wave approximation method, and an equivalent circuit model of the three-level resonant converter in a phasor domain is established, as shown in figure 4, to obtainAnd->Fundamental phasors of two voltages, +.>And->The normalized phasor expression is as follows:
in the method, in the process of the invention,is->Normalized phasors of>Is->Normalized phasors of>For the number of turns of the transformer, ">Is the voltage gain, defined as->，/>Is the output voltage;
according to normalized switching frequencyNormalized quality factor->The normalized impedance of the capacitor is obtained:；
wherein,is the angular frequency of the switchRate of->For normalizing the resonance angular frequency +.>Is externally connected with a resonance capacitor>Is externally connected with a resonant inductor>For normalizing the impedance +.>Is a load resistance;
obtaining a normalized resonance current expression according to a phasor domain equivalent circuit model of the three-level resonance converter;
wherein,for peak current +.>For resonance current +.>With alternating voltage->Is a phase shift angle of (2);
calculating normalized power：
。
In particular, the method comprises the steps of,the formula is:
in particular, the method comprises the steps of,the formula of (2) is:
in a preferred embodiment, the method of optimizing control in step S02 includes obtaining a system of equations for the control coordinates that minimize the effective value of the resonant current based on the power and current changes as the control coordinates change.
The equation expression of the optimization control algorithm is as follows:
in the method, in the process of the invention,to control angle->For resonance current +.>The square of the effective value is used to determine,
，
will be、/>、/>Substituting the expression into an equation of the optimization control algorithm to obtain an equation set of the optimization control algorithm:
the optimal path expression of loss is obtained by simplifying the equation set of the optimization control algorithm, and is as follows:
in a preferred embodiment, in the mode selection step S03, different control angle combinations can obtain different operation modes, but in order to achieve complete elimination of the circulating power of the converter, only if the control angle of the converter satisfiesThe converter can only realize the operation without the backflow power. The loss optimal path relation can be further optimized as:
。
in a preferred embodiment, the global loss optimal path is controlled, and the control method includes:
substituting the optimized loss optimal path relation into normalized powerSimplifying to obtain global loss optimal power：
By controllingPulse width +.>Controlling global loss optimum power->Is of a size of (a) and (b).
In another embodiment, a computer storage medium has a computer program stored thereon, which when executed implements the global optimal control method for a three-level resonant converter described above. Any of the above-described global optimal control methods for the three-level resonant converter may be employed, and will not be described here.
In another embodiment, a global optimum control system for a three-level resonant converter includes:
the equivalent power model calculation module is used for obtaining an equivalent power model by a modulation method aiming at the three-level resonant converter;
the optimization control module performs optimization control on the obtained equivalent power model to obtain a loss optimal path;
and the global optimal control module obtains different working modes through different control angle combinations, and finally optimizes the overall optimal control angle through mode optimization output loop-free mode.
The specific implementation method of each module may be implemented by any global optimal control method for the three-level resonant converter, which is not described herein.
The design parameters and simulation tests of a specific transducer are given below:
in order for the converter to operate efficiently, appropriate parameter design is required:
selection of，/>，/>，/>，/>The number of turns n of the transformer is 0.833.
Design input voltage V 1 400V, output voltage V 2 240V, rated at 1000W.
The simulation is carried out according to the designed input voltage, output voltage and power, and all switches can realize soft switching.
To verify the correctness of the theory, simulation tests were performed in PSIM.
When (when)，/>，/>，/>，/>、/>、/>And the current waveforms of the switching tubes are shown in fig. 5.
When (when)，/>，/>，/>，/>、/>、/>And the current waveforms of the switching tubes are shown in fig. 6.
When (when)，/>，/>，/>，/>、/>、/>And the current waveforms of the switching tubes are shown in FIG. 7。
After verification by combining simulation waveforms, the theory is found to be consistent with the reality, and the invention is proved to be feasible. The three-level resonant converter can be enabled to realize soft switching of the switching tube under a wide voltage gain range, so that switching loss is reduced; and the converter is enabled to always operate in a loss optimal path; meanwhile, the circulating power of the primary side and the secondary side of the converter is completely eliminated, and the overall operation efficiency of the converter is improved.
The foregoing examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the foregoing examples, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principles of the present invention should be made therein and are intended to be equivalent substitutes within the scope of the present invention.

Claims (8)

1. A global optimum control method for a three-level resonant converter, comprising the steps of:
s01: obtaining an equivalent power model by a modulation method aiming at the three-level resonant converter;
s02: performing optimization control on the obtained equivalent power model to obtain a loss optimal path;
s03: different working modes are obtained through different pulse width combinations, and the pulse width of the converter is controlled through optimizing the working modesThe converter realizes the completion of final optimization of no-return power operation, and the overall optimal pulse width is obtained;
in the step S01, a double-step modulation method is adopted, and the method comprises the following steps:
s11: switching tube for controlling primary side of three-level resonant converterIs 0 to +.>SwitchTube->Pulse width of +.>To->Switch tube->Pulse width of +.>To->Switch tube->Pulse width of +.>To->Switch tube->Pulse width of +.>To->Switch tube->Pulse width of +.>To->The method comprises the steps of carrying out a first treatment on the surface of the Thereby generating an alternating voltage +.>Contains->、/>、0、/>、/>Five voltage levels, ">For input voltage +.> ，/>Is pulse width; the switch tube-/>Is arranged at the primary side, is a switch tube>-/>Form a first bridge arm，Switch tube->-/>Forming a second bridge arm; the alternating voltage->Is the midpoint voltage of two bridge arms of the primary side;
s12: switching tube for controlling secondary side of three-level resonant converterAnd->Pulse width of +.>To->Switch tube->And->Pulse width of +.>To->And switch tube->、/>Hysteresis switch tube->Pulse widthDegree is->Thereby generating an alternating voltage +.>The method comprises the steps of carrying out a first treatment on the surface of the The switch tube->-/>Is arranged on the secondary side, and the switch tube is +.>-/>Form a third bridge arm, a switch tube>-A fourth bridge arm is formed; ac voltage->The midpoint voltage of two bridge arms of the secondary side;
s13: will resonate the currentIs set at the zero crossing of the switching tube>、/>And->To the opening point of (a)So that the resonance current and the switch tube are +>、/>、/>The same phase, eliminating the circulating power of the primary side and the secondary side of the converter;
the method for obtaining the equivalent power model in the step S01 includes:
performing steady-state analysis on the three-level resonant converter by using a fundamental wave approximation method, and establishing an equivalent circuit model of the three-level resonant converter in a phasor domain to obtainAnd->Fundamental phasors of two voltages, +.>And->The normalized phasor expression is as follows:
，
，
in the method, in the process of the invention,is->Normalized phasors of>Is->Normalized phasors of>For the turns ratio of primary and secondary side of the transformer, < >>Is the voltage gain;
according to normalized switching frequencyNormalized quality factor->The normalized impedance of the capacitor is obtained:；
wherein,for the switching angular frequency +.>For normalizing the resonance angular frequency +.>Is externally connected with a resonance capacitor>Is externally connected with a resonant inductor>For normalizing the impedance +.>Is a load resistance;
obtaining a normalized resonance current expression according to a phasor domain equivalent circuit model of the three-level resonance converter;
，
wherein,for peak current +.>For resonance current +.>With alternating voltage->Is a phase shift angle of (2);
calculating normalized power：
。
2. The global optimal control method for a three-level resonant converter according to claim 1, wherein the method of optimizing control in step S02 comprises obtaining a system of equations for a pulse width that minimizes an effective value of a resonant current on the basis of a change in power and current with a change in pulse width.
3. The global optimal control method for a three-level resonant converter according to claim 2, wherein the equation expression of the method of optimal control is:
，
in the method, in the process of the invention,for pulse width +.>For resonance current +.>The square of the effective value is used to determine,
，
will be、/>、/>Substituting the expression into an equation of the optimization control algorithm to obtain an equation set of the optimization control algorithm:
，
，
，
，
the optimal path expression of loss is obtained by simplifying the equation set of the optimization control algorithm, and is as follows:
。
4. the global optimum control method for a three-level resonant converter according to claim 3, wherein when the converter in step S03 realizes no-return power operation, the loss optimum path expression is further optimized as:
。
5. the global optimum control method for a three-level resonant converter according to claim 4, wherein said step S03 further comprises controlling a global loss optimum path, the control method comprising:
substituting the optimized loss optimal path relation into normalized powerSimplifying to obtain global loss optimal power +.>：
，
By controllingPulse width +.>Controlling global loss optimum power->Is of a size of (a) and (b).
6. A global optimum control system for a three-level resonant converter, comprising:
the equivalent power model calculation module is used for obtaining an equivalent power model by a modulation method aiming at the three-level resonant converter;
the optimization control module performs optimization control on the obtained equivalent power model to obtain a loss optimal path;
the global optimal control module obtains different working modes through different pulse width combinations, and controls the pulse width of the converter through optimizing the working modesThe converter realizes the completion of final optimization of no-return power operation, and the overall optimal pulse width is obtained;
the equivalent power model calculation module adopts a double-step modulation method, and the method comprises the following steps:
s11: switching tube for controlling primary side of three-level resonant converterIs 0 to +.>Switch tube->Pulse width of +.>To->Switch tube->Pulse width of +.>To->Switch tube->Pulse width of +.>To->Switch tube->Pulse width of +.>To->Switch tube->Pulse width of +.>To->The method comprises the steps of carrying out a first treatment on the surface of the Thereby generating an alternating voltage +.>Contains->、/>、0、/>、/>Five voltage levels, ">For input voltage +.> ，/>Is pulse width; the switch tube-/>Is arranged at the primary side, is a switch tube>-/>Form a first bridge arm，Switch tube->-/>Forming a second bridge arm; the alternating voltage->Is the midpoint voltage of two bridge arms of the primary side;
s12: switching tube for controlling secondary side of three-level resonant converterAnd->Pulse width of +.>To->Switch tube->And->Pulse width of +.>To->And switch tube->、/>Hysteresis switch tube->Pulse width of +.>Thereby generating an alternating voltage +.>The method comprises the steps of carrying out a first treatment on the surface of the The switch tube->-/>Is arranged on the secondary side, and the switch tube is +.>-/>Form a third bridge arm, a switch tube>-A fourth bridge arm is formed; ac voltage->The midpoint voltage of two bridge arms of the secondary side;
s13: will resonate the currentIs set at the zero crossing of the switching tube>、/>And->So that the resonance current is +.>、/>、/>In phase, eliminate the first converterThe cyclic power of the secondary side and the secondary side;
the method for obtaining the equivalent power model by the equivalent power model calculation module comprises the following steps:
performing steady-state analysis on the three-level resonant converter by using a fundamental wave approximation method, and establishing an equivalent circuit model of the three-level resonant converter in a phasor domain to obtainAnd->Fundamental phasors of two voltages, +.>And->The normalized phasor expression is as follows:
，
，
in the method, in the process of the invention,is->Normalized phasors of>Is->Normalized phasors of>For the turns ratio of primary and secondary side of the transformer, < >>Is the voltage gain;
according to normalized switching frequencyNormalized quality factor->The normalized impedance of the capacitor is obtained:；
wherein,for the switching angular frequency +.>For normalizing the resonance angular frequency +.>Is externally connected with a resonance capacitor>Is externally connected with a resonant inductor>For normalizing the impedance +.>Is a load resistance;
obtaining a normalized resonance current expression according to a phasor domain equivalent circuit model of the three-level resonance converter;
，
wherein,for peak current +.>For resonance current +.>With alternating voltage->Is a phase shift angle of (2);
calculating normalized power：
。
7. The global optimal control system for a three-level resonant converter according to claim 6, wherein the optimal control method of the optimal control module comprises obtaining a system of equations for minimizing an effective value of a resonant current based on a change in power and current with a change in pulse width;
the equation expression of the optimization control method is as follows:
，
in the method, in the process of the invention,for pulse width +.>For resonance current +.>The square of the effective value is used to determine,
，
will be、/>、/>Substituting the expression into an equation of the optimization control algorithm to obtain an equation set of the optimization control algorithm:
，
，
，
，
the optimal path expression of loss is obtained by simplifying the equation set of the optimization control algorithm, and is as follows:
。
8. a computer storage medium having stored thereon a computer program, characterized in that the computer program, when executed, implements the global optimum control method for a three-level resonant converter according to any of claims 1-5.
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CN108521217A (en) * 2018-04-24 2018-09-11 南京工程学院 A kind of LLC resonant converter method for optimally designing parameters minimum based on loss
CN113037097A (en) * 2021-04-29 2021-06-25 常熟理工学院 Modulation control method of resonant double-active-bridge converter
CN114649954A (en) * 2022-03-23 2022-06-21 华中科技大学 Three-phase three-level ANPC series resonance type double-active-bridge DC/DC converter
CN116094329A (en) * 2022-08-16 2023-05-09 常熟理工学院 Hybrid bridge resonant converter, modulation method and modulation system

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108521217A (en) * 2018-04-24 2018-09-11 南京工程学院 A kind of LLC resonant converter method for optimally designing parameters minimum based on loss
CN113037097A (en) * 2021-04-29 2021-06-25 常熟理工学院 Modulation control method of resonant double-active-bridge converter
CN114649954A (en) * 2022-03-23 2022-06-21 华中科技大学 Three-phase three-level ANPC series resonance type double-active-bridge DC/DC converter
CN116094329A (en) * 2022-08-16 2023-05-09 常熟理工学院 Hybrid bridge resonant converter, modulation method and modulation system

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