CN113054849B - Parallel current sharing control method and device based on Boost and LLC resonant converter - Google Patents

Parallel current sharing control method and device based on Boost and LLC resonant converter Download PDF

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CN113054849B
CN113054849B CN202110332827.2A CN202110332827A CN113054849B CN 113054849 B CN113054849 B CN 113054849B CN 202110332827 A CN202110332827 A CN 202110332827A CN 113054849 B CN113054849 B CN 113054849B
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boost
lbfn
llc resonant
resonant converter
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CN113054849A (en
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王峰
王学华
阮新波
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Huazhong University of Science and Technology
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Huazhong University of Science and 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
    • H02M1/32—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
    • H02M3/22—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
    • H02M3/285—Single converters with a plurality of output stages connected in parallel
    • 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 disclosesA parallel current sharing control method and device based on Boost and LLC resonant converter are disclosed, belonging to the field of DC converter control, the method comprises: s1: detecting the filter capacitor voltage V output by each Boost and LLC resonant converter module on And the actual current i on the preceding Boost inductor Lbn (ii) a Will measure the actual current i Lbn Input inductor current feedback function G in Obtaining a feedback signal i Lbfn (ii) a S2: will refer to the output voltage V ref And the filter capacitor voltage V on Differencing to obtain a voltage error signal e vn (ii) a S3: will voltage error signal e vn Input voltage controller G vc Obtaining a feedback signal i Lbfn Corresponding control instruction value i Lbfn_ref Simulating a virtual resistor connected in series with the front stage Boost inductor; s4: using control command value i Lbfn_ref Obtaining a modulation signal e determining a duty cycle in To perform parallel current sharing control on the parallel system. According to the parallel current sharing control method, when the parallel system is started or is disturbed externally, the duty ratio of each Boost and LLC resonant converter module can be adjusted in real time to realize parallel current sharing control.

Description

Parallel current sharing control method and device based on Boost and LLC resonant converter
Technical Field
The invention belongs to the field of direct current converter control, and particularly relates to a parallel current-sharing control method and device based on Boost and LLC resonant converters.
Background
With the rapid development of science and technology, the applications of high-power communication power supplies, aerospace vehicles, ship secondary conversion power supplies, large-scale high-speed computer CPU power supplies and the like are increasing day by day, and the requirements on the voltage and current level, the capacity and the power density of a DC converter are higher and higher. In low-voltage and high-power occasions, in order to reduce the current stress of a power semiconductor device and facilitate the selection of a proper power semiconductor device, one of the common solutions is to adopt an Input-Parallel Output-Parallel (IPOP) combined converter. As a basic module constituting the IPOP system, the converter selected for use must have an electrical isolation function.
In the case of a high-power dc converter, a full-bridge LLC resonant converter is usually employed in the converter topology. However, the mainstream control method of the LLC resonant converter is frequency conversion control, which is not favorable for optimally designing the magnetic element and the output filter capacitor. In order to overcome the defect of the frequency conversion control, a non-isolated PWM chopping converter can be cascaded in front of the frequency conversion control to form a combined converter formed by cascading the PWM chopping and the LLC resonant converter. In an IPOP system formed by taking a Boost and LLC resonant converter as a basic module, under the influence of a manufacturing process of a resonant element and the like, resonant parameters of the LLC resonant converter in different modules have certain difference, so that input and output currents of each module are uneven. The problem of uneven current can cause uneven electrical stress and thermal stress among the modules of the Boost and LLC resonant converter, the efficiency and the reliability of the IPOP system are obviously reduced, and even the IPOP system can not work normally in severe cases.
To solve this problem, current sharing control is usually introduced in the IPOP system. The current sharing control method commonly used at present comprises an average current method and an output impedance method. The active current sharing method adopts a current sensor to sample output current signals of all parallel modules, generates current sharing bus signals according to a certain method, compares the current sharing bus signals with output current signals of all phases respectively, generates error signals, sends the error signals to a control link, and adjusts the control of all phase modules, thereby realizing current sharing among the modules.
The active current sharing method has high precision and small current sharing error, but needs a current sensor and an auxiliary circuit thereof, so the cost is high, and meanwhile, the control method is sensitive to noise and the stability of the system is easily influenced. The output impedance method changes the equivalent output resistance of each parallel module of the combined direct current converter and the output characteristic of the regulator through an artificial series resistor or a virtual resistor, thereby realizing the current sharing. The method is simple to implement, but the output external characteristic is sacrificed to obtain a better current sharing effect. And the resistor can generate larger power loss when being connected with the actual resistor in series, and is not suitable for occasions with high power and high performance requirements.
Disclosure of Invention
Aiming at the defects or the improvement requirements of the prior art, the invention provides a parallel current sharing control method and a parallel current sharing control device based on a Boost LLC resonant converter, and aims to solve the technical problem that an IPOP system formed by the Boost LLC resonant converter as a basic module is difficult to stably and reliably work due to the difference of LLC resonant parameters of different modules.
In order to achieve the above object, according to an aspect of the present invention, there is provided a parallel current sharing control method based on Boost plus LLC resonant converters, including:
s1: detecting filter capacitor voltage V output by each Boost and LLC resonant converter module in parallel system on And the actual current i on the preceding Boost inductor Lbn (ii) a The actual current i Lbn Input inductor current feedback function G in Obtaining the actual current i Lbn Corresponding feedback signal i Lbfn ；
S2: will refer to the output voltage V ref And said filter capacitor voltage V on Difference is made to obtain a voltage error signal e vn ；
S3: the voltage error signal e vn Input voltage controller G vc Obtaining the feedback signal i Lbfn Corresponding control instruction value i Lbfn_ref Simulating a virtual resistor connected in series with the front stage Boost inductor;
s4: using the control instruction value i Lbfn_ref Obtaining the feedback signal i Lbfn Corresponding modulation signal e for determining duty ratio in And the parallel current sharing control is carried out on the parallel system.
In one embodiment, before S1, the method further includes:
comparing a physical model obtained by actual resistors connected in series with the preceding stage Boost inductor with a mathematical model obtained by a simulated virtual resistor to obtain the inductor current feedback function G in 。
In one embodiment, the inductor current feedback function G in The expression of (a) is:
G in ＝R/V Cbn
wherein R is the resistance value of the designed virtual resistor, V Cbn And outputting the voltage of the capacitor for the previous stage Boost of the nth module, wherein n is 1 or 2.
In one embodiment, the S4 includes:
s41: control theInstruction value i Lbfn_ref And the feedback signal i Lbfn Differencing to obtain the modulation signal e in ，e in ＝i Lbfn_ref －i Lbfn ；
S42: using said modulated signal e in And carrying out parallel current sharing control on the parallel system.
In one embodiment, the S42 includes:
modulating the modulated signal e in Generating a preceding-stage Boost switching tube Q in each Boost and LLC resonant converter module through PWM modulation b The control signal of (2);
the control signal is used for controlling the switching tube Q bn And switching on and off according to a certain rule, adjusting the duty ratio of the front stage Boost of each Boost and LLC resonant converter module, and absorbing voltage gain fluctuation of a rear stage LLC due to parameter errors so as to realize current sharing among the Boost and LLC resonant converter modules of the parallel system.
According to another aspect of the present invention, there is provided a parallel current sharing control apparatus based on Boost plus LLC resonant converter, including:
a detection module for detecting the filter capacitor voltage V output by each Boost and LLC resonant converter module in the parallel system on And the actual current i on the preceding Boost inductor Lbn (ii) a The actual current i Lbn Input inductor current feedback function G in Obtaining the actual current i Lbn Corresponding feedback signal i Lbfn ；
A difference module for outputting a reference output voltage V ref And said filter capacitor voltage V on Difference is made to obtain a voltage error signal e vn ；
An input module for inputting the voltage error signal e vn Input voltage controller G vc Obtaining the feedback signal i Lbfn Corresponding control instruction value i Lbfn_ref Simulating a virtual resistor connected in series with the front stage Boost inductor;
a control module for utilizing the control instruction value i Lbfn_ref Obtaining the feedback signal i Lbfn Corresponding determinationModulated signal e of duty cycle in And the parallel current sharing control is carried out on the parallel system.
According to another aspect of the invention, a computer-readable storage medium is provided, on which a computer program is stored which, when being executed by a processor, carries out the steps of the method.
In general, compared with the prior art, the above technical solutions conceived by the present invention can achieve the following beneficial effects:
1. the control method provided by the invention feeds back the physical quantity corresponding to the Boost inductive current containing the front stage Boost to the controller in a mode of an inductive current feedback function, thereby simulating a virtual resistor in control. The virtual resistor is connected with the Boost inductor in series, so that the instantaneous output impedance of the whole parallel system can be changed, and the whole parallel system can absorb external characteristic fluctuation caused by the inconsistency of the resonant parameters of the rear-stage LLC.
2. The Boost and LLC resonant converter modules are mutually independent on hardware, a current sharing bus is not needed, and the duty ratio of the front stage Boost of each Boost and LLC resonant converter module can be adjusted in real time in the transient process of starting a parallel system or suffering external disturbance so as to maintain a satisfactory current sharing effect.
Drawings
Fig. 1 is a schematic diagram of a parallel connection structure of two Boost plus LLC resonant converter modules in an embodiment of the present invention;
fig. 2 is a flowchart of a parallel current sharing control method based on Boost plus LLC resonant converter in an embodiment of the present invention;
FIG. 3a is a flow chart of a parallel current sharing control method based on Boost plus LLC resonant converter in another embodiment of the invention;
fig. 3b is a schematic structural diagram of a Boost plus LLC resonant converter module adopting the parallel current-sharing control method shown in fig. 3 a;
FIG. 4 is a block diagram of a single Boost plus LLC resonant converter module control system in the IPOP system of FIG. 3 b;
FIGS. 5a, 5b and 5c show two resonance parameters L according to an embodiment of the present invention r 、L m 、C r Working oscillograms when Boost and LLC resonant converter modules with 10% of errors are naturally connected in parallel;
FIGS. 6a, 6b and 6c show two resonance parameters L according to an embodiment of the present invention r 、L m 、C r An IPOP system formed by Boost and LLC resonant converter modules with 10% of errors obtains a working oscillogram by adopting the parallel current-sharing control method;
fig. 7 is a schematic structural diagram of a parallel current sharing control device based on Boost plus LLC resonant converters in an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
Fig. 1 is a structural diagram of two parallel connection of a Boost and LLC resonant converter module, and fig. 1 is a Boost and LLC resonant converter module, specifically including a dc power supply 2, a preceding stage Boost converter 3, a subsequent stage LLC resonant converter 4, and a controller 5. Wherein, Boost converter 3 is composed of Boost inductor L b1 Switching tube Q b1 Diode D 1 And an output capacitor C b1 Forming; LLC resonant converter 4 is composed of full-bridge switching tube Q 1 ～Q 4 Resonant capacitor C r1 Resonant inductance L r1 High frequency rectifier transformer T 1 And a synchronous rectification circuit of the secondary side; the controller 5 is composed of a voltage controller and an inductive current feedback damping link. And 6, another Boost plus LLC resonant converter module.
Under the working state that the two Boost and LLC resonant converter modules are connected in parallel, the working current of each module is reduced, and the improvement of the overall efficiency is facilitated. The submodules are mutually independent and backup, and the reliability of the system is enhanced. In an ideal situation, parameters of the upper and lower Boost and LLC resonant converter modules are the same, and power borne by different modules is the same. However, in the actual production process, due to the limitation of the manufacturing process, the parameters of the two Boost and LLC resonant converter modules may not be completely consistent, and can only be controlled within a certain error range. For Boost plus LLC circuits, small errors in the resonant parameters of the subsequent LLC resonant converter result in large unbalanced currents. All modules are designed according to rated power, and the modules bearing more power are overloaded for a long time and are easy to damage, so that the parallel system cannot work normally.
In this embodiment, the rated power of the module 1 is 1kW, the input dc voltage is 70-120V, and the output voltage is 28V. The switching frequency of the front stage Boost is 100kHz, and the Boost inductor L b At 0.16mH, the switching frequency of the latter stage LLC is 0.9 times the resonant frequency, i.e. f s ＝0.9*f r 200kHz, resonance parameter L r1 ＝6.2μH，C r1 ＝90nF，L m1 240 muH, and the transformation ratio k of the high-frequency rectifier transformer is 8. The resonance parameters of module 2 are all 90% of module 1, i.e. L r2 ＝5.6μH，C r2 ＝81nF，L m2 The other parameters are the same as for module 1, 216 μ H.
As shown in fig. 2, the present invention provides a parallel current sharing control method based on Boost and LLC resonant converter, including:
s1: detecting filter capacitor voltage V output by each Boost and LLC resonant converter module in parallel system on And the actual current i on the preceding Boost inductor Lbn (ii) a Will measure the actual current i Lbn Input inductor current feedback function G in Obtain the actual current i Lbn Corresponding feedback signal i Lbfn ；
S2: will refer to the output voltage V ref And the filter capacitor voltage V on Differencing to obtain a voltage error signal e vn ；
S3: will voltage error signal e vn Input voltage controller G vc Obtaining a feedback signal i Lbfn Corresponding control instruction value i Lbfn_ref Simulating a virtual resistor connected in series with the front stage Boost inductor;
s4: using control command value i Lbfn_ref Obtaining a feedback signal i Lbfn Corresponding modulation signal e for determining duty ratio in To perform parallel current sharing control on the parallel system.
In one embodiment, before S1, the method further includes:
comparing a physical model obtained by actual resistors connected in series with a preceding stage Boost inductor with a mathematical model obtained by a simulated virtual resistor to obtain an inductor current feedback function G in 。
In one embodiment, the inductor current feedback function G in The expression of (a) is:
G in ＝R/V Cbn
wherein R is the resistance value of the designed virtual resistor, V Cbn The subscript n here is 1 or 2, which is the voltage of the output capacitor of the preceding stage Boost of the nth module.
In one embodiment, S4 includes:
s41: will control the instruction value i Lbfn_ref And a feedback signal i Lbfn Differencing to obtain a modulated signal e in ；
S42: using modulated signals e in And carrying out parallel current sharing control on the parallel system.
In one embodiment, S42 includes:
will modulate signal e in Generating a preceding-stage Boost switching tube Q in each Boost and LLC resonant converter module through PWM modulation bn The control signal of (2);
the control signal is used for controlling the switching tube Q bn And on-off according to a certain rule, the duty ratio of the front stage Boost of each Boost and LLC resonant converter module is adjusted, and voltage gain fluctuation caused by parameter errors of a rear stage LLC is absorbed, so that current sharing among the Boost and LLC resonant converter modules of the parallel system is realized.
FIG. 3a is a flow chart of a parallel current sharing control method based on Boost plus LLC resonant converter in another embodiment of the invention; fig. 3b is a schematic structural diagram of a Boost plus LLC resonant converter module adopting the parallel current-sharing control method shown in fig. 3 a; FIG. 4 is a drawing3b, a block diagram of a control part of a single Boost plus LLC resonant converter module. Wherein G is vc A proportional-integral controller is adopted as a voltage controller; R/V cb Is the inductance current feedback coefficient, Z in_LLC Is the equivalent impedance looking into the input of the subsequent stage LLC, and k is the transformation ratio of the transformer. An embodiment of the present invention will be described below with reference to fig. 3b and 4.
Firstly, detecting the voltage V of an output filter capacitor of a Boost and LLC module o And a preceding Boost inductor current i Lb And sent to the controller to boost the inductor current i Lb Through the inductor current feedback function G in ＝R/V Cbn Calculating to obtain a boost voltage inductive current feedback signal i Lbf 。
Then, a voltage command value V is inputted ref Subtracting the measured output voltage value V o Then sent to the voltage controller G vc The output signal is used as the instruction value of the boost inductor current. The command value and the boost inductor current feedback signal i Lbf The difference is used to obtain a modulation signal which determines the duty ratio.
Secondly, the modulation signal is sent to a PWM modulator to generate a front-stage Boost switching tube Q b The PWM control signal of (1).
And finally, establishing a parallel system of two Boost and LLC resonant converters through a PLECS simulation platform, wherein parameters are as the example, and when the input voltage V is in When the voltage is 100V, the two Boost and LLC resonant converter modules naturally run in parallel, and the result is as shown in fig. 5a, 5b and 5c, specifically including the input current i of the two Boost and LLC resonant converter modules Lb Current i of LLC resonant cavity at the later stage Lr And the current i rectified by the secondary side rect The operation results of the control method according to the invention are shown in fig. 6a, 6b and 6 c. Comparing fig. 5a, fig. 5b and fig. 5c with fig. 6a, fig. 6b and fig. 6c, it can be seen that, after the control scheme of the present invention is adopted, the current imbalance phenomenon caused by the difference of LLC resonance parameters between two Boost and LLC resonant converter modules in the parallel system is significantly improved. Obviously, the current sharing control method provided by the invention can ensure that the Boost and LLC circuit is reliable and stable under the condition of modular parallel operationAnd (7) working.
According to another aspect of the present invention, as shown in fig. 7, there is provided a parallel current sharing control device based on Boost plus LLC resonant converter, including: a detection module 701, a difference making module 702, an input module 703 and a control module 704.
A detection module 701, configured to detect a filter capacitor voltage V output by each Boost plus LLC resonant converter module in the parallel system on And the actual current i on the preceding Boost inductor Lbn (ii) a Will measure the actual current i Lbn Input inductor current feedback function G in Obtain the actual current i Lbn Corresponding feedback signal i Lbfn ；
A difference module 702 for outputting a reference output voltage V ref And the filter capacitor voltage V on Differencing to obtain a voltage error signal e vn ；
An input module 703 for inputting the voltage error signal e vn Input voltage controller G vc Obtaining a feedback signal i Lbfn Corresponding control instruction value i Lbfn_ref Simulating a virtual resistor connected in series with the front stage Boost inductor;
a control module 704 for utilizing the control instruction value i Lbfn_ref Obtaining a feedback signal i Lbfn Corresponding modulation signal e for determining duty ratio in To perform parallel current sharing control on the parallel system.
According to another aspect of the present invention, a computer-readable storage medium is provided, on which a computer program is stored, which, when being executed by a processor, performs the steps of a method for parallel current sharing control based on Boost plus LLC resonant converters.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims (5)

1. A parallel current sharing control method based on Boost and LLC resonant converter is characterized by comprising the following steps:
s1: detecting output filter capacitor voltage V of each Boost and LLC resonant converter module in parallel system on And the actual current i on the preceding Boost inductor Lbn (ii) a The actual current i Lbn Input inductor current feedback function G in Obtaining the actual current i Lbn Corresponding feedback signal i Lbfn ；
S2: will refer to the output voltage V ref And said filter capacitor voltage V on Differencing to obtain a voltage error signal e vn ；
S3: the voltage error signal e vn Input voltage controller G vc Obtaining the feedback signal i Lbfn Corresponding control instruction value i Lbfn_ref Simulating a virtual resistor connected in series with the front stage Boost inductor;
s4: using the control instruction value i Lbfn_ref Obtaining the feedback signal i Lbfn Corresponding modulation signal e for determining duty ratio in To perform parallel current sharing control on the parallel system;
before S1, the method further includes: comparing a physical model obtained by actual resistance of the preceding stage Boost inductor in series with a mathematical model obtained by simulated virtual resistance to obtain the inductance current feedback function G in (ii) a The inductor current feedback function G in The expression of (a) is:
G in ＝R/V Cbn ；
wherein R is the resistance value of the designed virtual resistor, V Cbn And outputting the voltage of the capacitor for the previous stage Boost of the nth module, wherein n is 1 or 2.
2. The parallel current sharing control method based on Boost plus LLC resonant converter as claimed in claim 1, wherein said S4 includes:
s41: the control instruction value i Lbfn_ref And the feedback signal i Lbfn Differencing to obtain the modulation signal e in ，e in ＝i Lbfn_ref －i Lbfn ；
S42: using said modulated signal e in And carrying out parallel current sharing control on the parallel system.
3. The parallel current sharing control method based on Boost plus LLC resonant converter as claimed in claim 1, wherein said S42 includes:
modulating the modulated signal e in Generating a preceding-stage Boost switching tube Q in each Boost and LLC resonant converter module through PWM modulation bn The control signal of (2); the control signal is used for controlling the switching tube Q bn And switching on and off according to a preset rule, adjusting the duty ratio of the front stage Boost of each Boost and LLC resonant converter module, and absorbing voltage gain fluctuation of a rear stage LLC due to parameter errors so as to realize current sharing among the Boost and LLC resonant converter modules of the parallel system.
4. A parallel current sharing control device based on Boost plus LLC resonant converters, characterized in that it is used to execute the method of any of claims 1-3, comprising:
a detection module for detecting the filter capacitor voltage V output by each Boost and LLC resonant converter module in the parallel system on And the actual current i on the preceding Boost inductor Lbn (ii) a The actual current i Lbn Input inductor current feedback function G in Obtaining the actual current i Lbn Corresponding feedback signal i Lbfn ；
A difference module for outputting a reference output voltage V ref And said filter capacitor voltage V on Differencing to obtain a voltage error signal e vn ；
An input module for inputting the voltage error signal e vn Input voltage controller G vc Obtaining the feedback signal i Lbfn Corresponding control instruction value i Lbfn_ref Simulating a virtual resistor connected in series with the front stage Boost inductor;
a control module for utilizing the control instruction value i Lbfn_ref Obtaining the feedback signal i Lbfn Corresponding modulation signal e for determining duty ratio in And the parallel current sharing control is carried out on the parallel system.
5. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out the steps of the method of any one of claims 1 to 3.
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