CN118041113A - DAB-based SWISS-type three-phase bidirectional converter control method - Google Patents
DAB-based SWISS-type three-phase bidirectional converter control method Download PDFInfo
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Classifications
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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
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/66—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal
- H02M7/68—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters
- H02M7/72—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/79—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/797—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
-
- 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
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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
- H02M1/00—Details of apparatus for conversion
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
- H02M1/083—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the ignition at the zero crossing of the voltage or the current
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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
- H02M1/00—Details of apparatus for conversion
- H02M1/42—Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
- H02M1/4208—Arrangements for improving power factor of AC input
- H02M1/4233—Arrangements for improving power factor of AC input using a bridge converter comprising active switches
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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
- H02M3/33573—Full-bridge at primary side of an isolation transformer
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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
- H02M3/33584—Bidirectional converters
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- 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
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Rectifiers (AREA)
Abstract
The invention discloses two control methods for unit power factor correction of a SWISS-based three-phase bidirectional converter based on DAB, and belongs to the field of three-phase bidirectional AC/DC converters in the field of power electronics. The SWISS type converter based on DAB consists of a low-frequency sector selection circuit and a high-frequency switch network, the network side is connected with a low-frequency SWISS converter circuit topology, and triple-power-frequency steamed bread waves are respectively generated between po and on nodes and are respectively used as the input of the DAB converters at the high-frequency switch. Each DAB converter in the high-frequency switch network is isolated through a transformer, and the primary side and the secondary side of the transformer are respectively two full bridges, and output is used for connecting any load. And through switching of working modes of the DAB converter, the duty ratio of the two full bridges and the phase shift angle corresponding to the voltage waveform are controlled to realize power factor correction. The invention can realize high-efficiency work, wide-range output and high electric energy quality, simultaneously ensure the optimization of soft switching of all switching tubes and peak current of the transformer, and improve the efficiency of the converter.
Description
Technical Field
The invention relates to a control method of a SWISS three-phase bidirectional converter based on DAB, and belongs to the field of three-phase bidirectional AC/DC converters in the field of power electronics.
Background
With the popularization of new energy technologies, the ac/dc hybrid micro-grid technology has been actively researched and developed due to its potential in high energy utilization, multi-energy compatibility and fusion with the prior art. Within this technical framework, three-phase AC/DC converters connected to an AC/DC grid are considered as a key component of a hybrid micro-grid. For converter research, high efficiency, low cost, high power quality and stable output voltage have been constantly pursued targets. In addition, in certain operating situations, three-phase bi-directional AC/DC converters are also required to meet a wide range of regulation of the output DC voltage as well as a wide range of load power variations.
In the bidirectional operating state of the converter, taking a rectifying state as an example, a conventional three-phase AC-DC rectifier generally adopts a two-stage structure, and a Power Factor Correction (PFC) circuit is connected to a DC-DC circuit. The AC-DC output is a constant direct current voltage, which is regulated by a DC-DC circuit. A novel three-phase Buck SWISS rectifier topological structure is provided by an on-line technology, and comprises a low-frequency sector selection circuit and two Buck circuits for realizing power factor control, wherein the integrated control can be realized between the sector selection circuit and the Buck circuits without a large-capacity decoupling capacitor, and the three-phase Buck SWISS rectifier topological structure belongs to a single-stage structure. The diode in the circuit is replaced by a switching tube, so that the bidirectional flow of power can be realized. Compared with other three-phase AC/DC converters, fewer high-frequency switches are needed, the switching loss caused by high-frequency modulation is reduced, and the rectification works in a Buck mode, so that the output voltage change in a wider range can be realized. However, high frequency switching rarely causes stress concentration in the switching tubes, limiting the power class of the converter. In addition, the soft switching of the switching tube cannot be realized by adopting the method adopted by the technology, and the efficiency of the converter is low.
In order to solve the problems of hard switching operation and concentrated switching stress of the SWISS rectifier, and for the purpose of electrical isolation, a novel isolated SWISS rectifier, called a SWISS phase-shifting full bridge rectifier (SPFR), is proposed by another on-line technology. The technology replaces Buck circuit with phase-shifting full-bridge circuit topology to realize AC-DC rectifier, and provides a novel modulation strategy to realize soft switching in SPFR. The soft switching of the high frequency switch not only depends on the energy stored in the transformer leakage inductance and the energy in the magnetizing inductance, so the power coupling between the two full bridges affects the zero voltage switching condition of the lagging leg. The method adopted by the technology is only suitable for a rectification mode, is not suitable for occasions of power bidirectional flow, and meanwhile, the peak value and the effective value current of the transformer and the switching tube are large, and the conduction loss cannot be optimized.
Disclosure of Invention
In order to realize bidirectional and high-efficiency operation, wide-range output and high power quality of the SWISS converter, the invention provides a control method of the SWISS type three-phase bidirectional converter based on DAB. Fig. 1 is a schematic diagram of a topology structure of a SWISS-type three-phase bidirectional converter based on DAB, and two corresponding control strategies are provided for the topology to realize power factor correction and output voltage control, so that stable control and high efficiency of the DAB converter are comprehensively optimized, mode control of conduction loss and zero-voltage soft switching is optimized, soft switching of all working modes of the DAB converter and optimization of peak current of a transformer can be realized on the basis, and further high-efficiency work, wide-range output and high-power quality input of the SWISS-type converter based on DAB can be realized.
The aim of the invention is achieved by the following technical scheme.
The invention discloses a SWISS type converter based on DAB, which is characterized in that: the SWISS type converter based on DAB is an isolated three-phase AC/DC converter, a network side is connected to a SWISS converter circuit topology working at low frequency, the power grid voltage passes through the SWISS converter, and three times of power frequency steamed bread waves are generated between po and on nodes and are respectively used as the input of the DAB converters at high frequency switches; each DAB converter is isolated through a transformer, and the primary side and the secondary side of the transformer are respectively two full bridges and output for connecting any load; the switching of working modes of the DAB converter is used for controlling the duty ratio of two full bridges and the phase shift angle corresponding to the voltage waveform to realize the power factor correction of the converter; the output side is connected with the outputs of the two DAB converters in parallel to obtain output voltage. The control method for unit power factor correction of SWISS type converter based on DAB disclosed by the invention comprises the following two steps:
the control method for the current-free sampling power factor correction of the SWISS type converter based on DAB comprises the following steps:
Step one: the voltage error obtained by subtracting the voltage reference V ref and the output voltage feedback V o is outputted as an input current amplitude control quantity y, y epsilon < -1,1 > through an output voltage controller;
Step two: sampling an input side a-phase voltage V ga, and obtaining a grid phase voltage amplitude V m and a phase angle theta of the a-phase after passing through a second-order generalized integrator and a phase-locked loop, wherein theta is E [0,2 pi ]; respectively adding or subtracting 2 pi/3 to the phase angle theta to obtain phase angles of a c phase and a b phase, and further obtaining cosine values of the three-phase angles; multiplying the input current amplitude control quantity y and the maximum phase angle cosine value by a multiplier to obtain an input current given value of the DAB converter connected with the po node, and similarly multiplying the input current amplitude control quantity y and the minimum phase angle cosine value by the multiplier to obtain an input current given value of the DAB converter connected with the on node by y cos min, and respectively calculating to obtain phase shift angle values corresponding to the two DAB converters by the two input current given values;
Step three: generating a driving signal of a bidirectional switch in the SWISS converter according to the sector where the network side three-phase voltage is located; the expression of the primary input side voltage v in_p of the DAB converter connected with the output of the po node is
Wherein V ab、vba、vbc、vcb、vca、vac is the difference between the phase voltages of ab phase, ba phase, bc phase, cb phase, ca phase, ac phase, V m is the phase voltage amplitude, and θ is the phase angle of the a phase voltage.
The expression of the primary input side voltage v in_n of the DAB converter connected with the output of the on node is
According to the sampled output voltage v o of the secondary side of the DAB converter, the equivalent voltage gains M p and M n,Mp of the DAB converter connected with the po node and the on node are respectively calculated, v o/(nvin_p),Mn is v o/(nvin_n, and n is the ratio of the number of turns of the secondary side to the number of turns of the primary side of the transformer.
Step four: according to the phase shift angles obtained by the second and third steps and the values of M p and M n, dividing the two DAB converters to work in the following 7 modes: when M p or M n is smaller than 1, judging that the DAB works in three working modes of mode 1 or mode 1.5 or mode 2, further judging that the DAB converter works in one specific working mode of the three working modes according to the phase shift angle, and calculating to obtain the corresponding duty ratio and phase shift angle under mode 1 or mode 1.5 or mode 2; when M p or M n is larger than 1, judging that DAB works in four working modes of mode 3 or mode 3c or mode 3.5 or mode 4, further judging that the DAB converter works in one specific working mode of the four working modes according to the phase shift angle and the input voltage, and calculating to obtain the corresponding duty ratio and the phase shift angle under the corresponding mode 3 or mode 3c or mode 3.5 or mode 4; through the mode switching mode, the power factor correction and the output voltage control of the SWISS converter based on DAB are realized, the conduction loss and the mode control of the zero-voltage soft switch are optimized, and the optimization of soft switches of 8 switching tubes and peak current of a transformer under seven modes of each DAB converter is ensured.
According to the M p value and the phase shift angle value obtained by calculation in the second step and the third step, the DAB converter connected with the dividing po node works in the following 7 modes:
When M p is smaller than 1, DAB works in three working modes of mode 1, mode 1.5 or mode 2: calculating the phase shift angle of three working modes and the critical phase shift angle of mode switching, wherein
The y cos_max is an input current given value of the DAB converter connected with the po node, L r is an inductance value of the series inductor, T s is a switching period, I ZVS1 is a minimum current amplitude of the DAB converter primary side full-bridge switching tube for realizing soft switching, and I ZVS2 is a minimum current amplitude of the DAB converter secondary side full-bridge switching tube for realizing soft switching; The phase shift angle corresponding to the DAB converter in mode 1 is used; /(I) The phase shift angle is corresponding to the phase shift angle of the DAB converter under the mode 1.5; /(I)The phase shift angle corresponding to the DAB converter in mode 2 is used; /(I)When M p is smaller than 1, determining that the DAB converter is particularly operated in a critical phase shift angle of a mode 1 or a mode 1.5; /(I)When M p is smaller than 1, determining that the DAB converter is particularly operated in a critical phase shift angle of a mode 1.5 or a mode 2; under the condition that M p is smaller than 1, further judging that the DAB converter works in a specific working mode in the three working modes according to the phase shift angle:
When (when) When the DAB converter works in the mode 1, the corresponding duty ratio and phase shift angle of the DAB converter in the mode 1 are calculated and obtained
Wherein,The phase shift angle of the DAB converter connected with the po node is D 1p which is the duty ratio of the primary side full bridge of the DAB converter, and D 2p which is the duty ratio of the secondary side full bridge of the DAB converter;
When (when) When the DAB converter works in the mode 2, the corresponding duty ratio and phase shift angle of the DAB converter in the mode 2 are calculated and obtained
When (when)When the DAB converter is in the mode 1.5, the corresponding duty ratio and phase shift angle of the DAB converter in the mode 1.5 are calculated and obtained
At this time ifIt is explained that the DAB converter is operating in mode 1.5; if/>Judging that the DAB converter works in a mode 2, and obtaining the duty ratio and the phase shift angle according to an expression in the mode 2;
When M p is larger than 1, determining that DAB works in four working modes of mode 3 or mode 3c or mode 3.5 or mode 4: calculating the phase shift angle of four working modes, and the critical phase shift angle and critical input voltage of mode switching, wherein
The phase shift angle corresponding to the DAB converter working under the condition of the mode 3 is obtained; /(I)The corresponding phase shift angle of the DAB converter under the condition of the mode 3c is obtained; /(I)The phase shift angle is corresponding to the DAB converter working under the condition of the mode 3.5; /(I)The phase shift angle of the DAB converter under the condition of mode 4 is corresponding; /(I)In order to determine that the DAB converter is particularly operated in the critical phase shift angle of mode 3 or mode 3.5 when M p is greater than 1,/>When M p is larger than 1, determining that the DAB converter is particularly operated in a critical phase shift angle of a mode 3.5 or a mode 4; v in_th is the critical phase shift angle for determining whether the DAB converter is operating in mode 3 c;
Under the condition that M p is larger than 1, further judging that the DAB converter works in a specific working mode in the four working modes according to the phase shift angle and the input voltage:
When (when) When the DAB converter is judged to work in a mode 3 or a mode 3c, and the DAB converter is further judged to work in one specific working mode of the two working modes according to the magnitude of the input voltage:
When v in_p≤Vin_th is reached, the DAB converter is judged to work in the mode 3c, and the corresponding duty ratio and phase shift angle of the DAB converter in the mode 3c are calculated
When v in_p>Vin_th is reached, the DAB converter is judged to work in the mode 3, and the corresponding duty ratio and phase shift angle of the DAB converter in the mode 3 are calculated
When (when)When the DAB converter works in the mode 4, the corresponding duty ratio and phase shift angle of the DAB converter in the mode 4 are calculated and obtained
When (when)When the DAB converter is in the mode 3.5, the corresponding duty ratio and phase shift angle of the DAB converter in the mode 3.5 are calculated
At this time ifIt is explained that the DAB converter is operating in mode 3.5; if/>Judging that the DAB converter works in a mode 4, and obtaining the duty ratio and the phase shift angle according to an expression in the mode 4;
Under the condition that M p is equal to 1, the corresponding duty ratio and phase shift angle of the DAB converter are obtained by direct calculation
Obtained in the above modesWhen power flows forward/>Greater than 0; when power flows in reverse/>Less than 0.
In the fourth step, the DAB converter connected with the node is divided to work in the following specific implementation method of 7 modes according to the M n value and the phase shift angle value calculated in the second step and the third step, and the specific implementation method comprises the following steps:
When M n is smaller than 1, DAB works in three working modes of mode 1, mode 1.5 or mode 2: calculating the phase shift angle of three working modes and the critical phase shift angle of mode switching, wherein
Y cos_min is an input current given value of the DAB converter connected with the on node, L r is an inductance value of the series inductor, T s is a switching period, I ZVS1 is a minimum current amplitude of the DAB converter primary side full-bridge switching tube for realizing soft switching, and I ZVS2 is a minimum current amplitude of the DAB converter secondary side full-bridge switching tube for realizing soft switching; The phase shift angle corresponding to the DAB converter in mode 1 is used; /(I) The phase shift angle is corresponding to the phase shift angle of the DAB converter under the mode 1.5; /(I)The phase shift angle corresponding to the DAB converter in mode 2 is used; /(I)When M n is smaller than 1, determining that the DAB converter is particularly operated in a critical phase shift angle of a mode 1 or a mode 1.5; /(I)When M n is smaller than 1, determining that the DAB converter is particularly operated in a critical phase shift angle of a mode 1.5 or a mode 2; under the condition that M n is smaller than 1, further judging that the DAB converter works in a specific working mode in the three working modes according to the phase shift angle:
When (when) When the DAB converter works in the mode 1, the corresponding duty ratio and phase shift angle of the DAB converter in the mode 1 are calculated and obtained
Wherein,The phase shift angle of the DAB converter connected with the on node is D 1n which is the duty ratio of the primary side full bridge of the DAB converter connected with the on node, and D 2n which is the duty ratio of the secondary side full bridge of the DAB converter connected with the on node;
When (when) When the DAB converter works in the mode 2, the corresponding duty ratio and phase shift angle of the DAB converter in the mode 2 are calculated and obtained
When (when)When the DAB converter is in the mode 1.5, the corresponding duty ratio and phase shift angle of the DAB converter in the mode 1.5 are calculated and obtained
At this time ifIt is explained that the DAB converter is operating in mode 1.5; if/>Judging that the DAB converter works in a mode 2, and obtaining the duty ratio and the phase shift angle according to an expression in the mode 2;
When M n is larger than 1, determining that DAB works in four working modes of mode 3 or mode 3c or mode 3.5 or mode 4: calculating the phase shift angle of four working modes, and the critical phase shift angle and critical input voltage of mode switching, wherein
The phase shift angle corresponding to the DAB converter working under the condition of the mode 3 is obtained; /(I)The corresponding phase shift angle of the DAB converter under the condition of the mode 3c is obtained; /(I)The phase shift angle is corresponding to the DAB converter working under the condition of the mode 3.5; /(I)The phase shift angle of the DAB converter under the condition of mode 4 is corresponding; /(I)In order to determine that the DAB converter is particularly operated in the critical phase shift angle of mode 3 or mode 3.5 when M p is greater than 1,/>When M p is larger than 1, determining that the DAB converter is particularly operated in a critical phase shift angle of a mode 3.5 or a mode 4; v in_th is the critical phase shift angle for determining whether the DAB converter is operating in mode 3 c;
Under the condition that M n is larger than 1, further judging that the DAB converter works in a specific working mode in the four working modes according to the phase shift angle and the input voltage:
When (when) When the DAB converter is judged to work in a mode 3 or a mode 3c, and the DAB converter is further judged to work in one specific working mode of the two working modes according to the magnitude of the input voltage:
When v in_n≤Vin_th is reached, the DAB converter is judged to work in the mode 3c, and the corresponding duty ratio and phase shift angle of the DAB converter in the mode 3c are calculated
When v in_n>Vin_th is reached, the DAB converter is judged to work in the mode 3, and the corresponding duty ratio and phase shift angle of the DAB converter in the mode 3 are calculated
When (when)When the DAB converter works in the mode 4, the corresponding duty ratio and phase shift angle of the DAB converter in the mode 4 are calculated and obtained
When (when)When the DAB converter is in the mode 3.5, the corresponding duty ratio and phase shift angle of the DAB converter in the mode 3.5 are calculated
At this time ifIt is explained that the DAB converter is operating in mode 3.5; if/>Judging that the DAB converter works in a mode 4, and obtaining the duty ratio and the phase shift angle according to an expression in the mode 4;
Under the condition that M n is equal to 1, the corresponding duty ratio and phase shift angle of the DAB converter are obtained by direct calculation
Obtained in the above modesWhen power flows forward/>Greater than 0; when power flows in reverse/>Less than 0.
Step five: according to the phase shift angles and the duty ratios corresponding to the DAB converters connected with the po node and the on node obtained in the step four, driving signals corresponding to two full-bridge switching tubes corresponding to the two DAB converters are respectively generated, and the driving signals are used for driving 16 switching tubes to work; the DAB converter switches the working modes according to the requirements, so that the power factor correction and the output voltage control of the SWISS type converter based on DAB are realized, the conduction loss and the mode control of the zero-voltage soft switch are optimized, and the soft switch realization of 16 switching tubes in the two DAB converters and the optimization of the peak current of the transformer are ensured.
The control method for the input current sampling power factor correction of the SWISS type converter based on DAB comprises the following steps:
Step one: the voltage error obtained by subtracting the voltage reference V ref and the output voltage feedback V o is outputted by the output voltage controller, and the reference value y v,yv of the input current amplitude is defined as the reference value of the per unit value of the input current amplitude, and y v epsilon < -1,1 >; phase locking is carried out on the three-phase voltage to obtain a phase angle theta m of a synthesized voltage vector, abc-dq conversion of the three-phase power grid current obtained through sampling is sent into the phase angle theta m, and a per unit value I m *,Im * epsilon < -1,1 > of the input current amplitude is obtained through a calculation unit; wherein the positive and negative of I m * are determined by the power flow direction, I m * >0 and I gd >0 in forward power flow, and I m * <0 and I gd <0 in reverse power flow. Wherein i gd is a current component corresponding to the d axis after the three-phase grid current is subjected to abc-dq transformation. Judging the positive and negative of the I m * according to the positive and negative of the I gd; then the current error obtained by subtracting the input current amplitude reference value y v and the input current amplitude per unit value I m * is outputted as an input current amplitude control value y, y epsilon < -1,1 > through an input current controller;
Step two: sampling an input side a-phase voltage V ga, and obtaining a grid phase voltage amplitude V m and a phase angle theta of the a-phase after passing through a second-order generalized integrator and a phase-locked loop, wherein theta is E [0,2 pi ]; respectively adding or subtracting 2 pi/3 to the phase angle theta to obtain phase angles of a c phase and a b phase, and further obtaining cosine values of the three-phase angles; multiplying the input current amplitude control quantity y and the maximum phase angle cosine value by a multiplier to obtain an input current given value of the DAB converter connected with the po node, and similarly multiplying the input current amplitude control quantity y and the minimum phase angle cosine value by the multiplier to obtain an input current given value of the DAB converter connected with the on node by y cos min, and respectively calculating to obtain phase shift angle values corresponding to the two DAB converters by the two input current given values;
The control method of the SWISS type converter input current sampling power factor correction based on DAB is the same as the steps three, four and five of the control method of the no current sampling power factor correction.
In the third step of the two control methods, the driving signal of the bidirectional switch in the SWISS converter is determined according to the sector where the three-phase power grid voltage synthesis vector is located; the third step of generating the driving signals of the bidirectional switches in the SWISS converter is aimed at three groups of bidirectional switches, wherein the driving signals comprise six switching tubes, and the six switching tubes are divided into three groups, namely S va,Svb,Svc, and the driving signals of the six switching tubes are all power frequency square wave signals; each group of switching tubes consists of emitters of two switching tubes which are in anti-series connection, and driving signals of the two switching tubes in each group are consistent; for the topology structure of the SWISS converter in the SWISS type converter based on DAB shown in FIG. 1, three-phase voltages at the network side abc correspond to three bridge arms respectively, Q 1、Q3、Q5 forms an upper bridge arm, and Q 2、Q4、Q6 forms a lower bridge arm; the a-phase bridge arm is formed by connecting an emitter electrode of Q 1 and a collector electrode of Q 2; the b-phase bridge arm is formed by connecting an emitter electrode of Q 3 and a collector electrode of Q 4; the c-phase bridge arm is formed by connecting an emitter electrode of Q 5 and a collector electrode of Q 6; the collector electrodes of the switching tubes Q 1、Q3、Q5 are connected together to serve as the positive electrode of the input end of the DAB converter connected with the po node, and the positive electrode is defined as a node p; the emitter of the switch tube Q 2、Q4、Q6 is connected together to be used as the negative electrode of the input end of the DAB converter connected with the on node, and the node is defined as a node n; the three groups of bidirectional switches are connected in parallel and respectively used as the negative electrode of the input end of the DAB converter connected with the po node and the positive electrode of the input end of the DAB converter connected with the on node, and the node is defined as a node o; the driving signal is still determined according to the sector where the three-phase grid voltage synthesis vector is located; the driving signals for generating the bidirectional switches in the SWISS converter are aimed at the three groups of bidirectional switches and six switching tubes on the bridge arm; in each sector, a corresponding upper bridge arm switching tube with the phase voltage value at the maximum value is conducted; a corresponding lower bridge arm switch tube with the phase voltage value at the minimum value is conducted; a corresponding bidirectional switch with the phase voltage value at the middle position is conducted; the switching frequency of the switching tube on the bridge arm is power frequency, and the switching frequency of the bidirectional switch is double power frequency.
For the topology structure of the SWISS rectifier in the SWISS rectifier based on DAB shown in FIG. 2, the three-phase voltages on the network side abc correspond to three bridge arms respectively, D 1、D3、D5 forms an upper bridge arm, and D 2、D4、D6 forms a lower bridge arm; the a-phase bridge arm is formed by connecting an anode of D 1 and a cathode of D 2; the b-phase bridge arm is formed by connecting an anode of D 3 and a cathode of D 4; the c-phase bridge arm is formed by connecting an anode of D 5 and a cathode of D 6; the cathodes of the diodes D 1、D3、D5 are connected together to serve as the positive electrode of the input end of the DAB converter connected with the po node, and the positive electrode is defined as a node p; the anodes of the diodes D 2、D4、D6 are connected together to serve as the negative electrode of the input end of the DAB converter connected with the on node, and the node is defined as a node n; the three groups of bidirectional switches are connected in parallel and respectively used as the negative electrode of the input end of the DAB converter connected with the po node and the positive electrode of the input end of the DAB converter connected with the on node, and the node is defined as a node o; and a corresponding bidirectional switch with the phase voltage value at the middle position in each sector is conducted, and the switching frequency of each group of bidirectional switches is twice the power frequency.
In the fifth step, driving signals corresponding to two full-bridge switching tubes corresponding to the two DAB converters are respectively generated according to the phase shift angles and the duty ratios corresponding to the DAB converters connected with the po node and the on node obtained in the fourth step, wherein the driving signals are used for driving 16 switching tubes to work; the driving signals for generating the switching tubes are aimed at two DAB converters, wherein the driving signals comprise 16 switching tubes, namely Q p1,Qp2,Qp3,Qp4,Qp5,Qp6,Qp7,Qp8 and Q n1,Qn2,Qn3,Qn4,Qn5,Qn6,Qn7,Qn8 respectively; the driving signals of the switching tubes of the 16 switching tubes are 50% square wave signals, Q p1 is complementary to Q p2, Q p3 is complementary to Q p4, Q p5 is complementary to Q p6, and Q p7 is complementary to Q p8; q n1 is complementary to Q n2, Q n3 and Q n4, Q n5 is complementary to Q n6, and Q n7 is complementary to Q n8; the time that Q p3 advanced Q p1 is controlled by D 1p, and the time that Q p7 advanced Q p5 is controlled by D 2p; the time that Q n3 advanced Q n1 is controlled by D 1n, and the time that Q n7 advanced Q n5 is controlled by D 2n; the phase difference between the neutral lines of the two full-bridge secondary side voltage square waves of the DAB converter connected with the po node isThe phase difference between the neutral lines of two full-bridge secondary side voltage square waves of the DAB converter connected with the node is/>And define
For the topological structure of the DAB converter connected with the po node, the primary side full bridge of the DAB converter comprises 4 switching tubes Q p1-Qp4; the switching tube Q p1 and the switching tube Q p2 form a bridge arm, and the source electrode of the Q p1 is connected with the drain electrode of the Q p2; the switching tube Q p3 and the switching tube Q p4 form a bridge arm, and the source electrode of the Q p3 is connected with the drain electrode of the Q p4; the drain of the switch tube Q p1 is connected with the drain of the switch tube Q p3 together and is connected with the collector of the Q 1、Q3、Q5, and the drain is connected with the cathode of the D 1、D3、D5 under the SWISS rectifier topology; the sources of the switching tube Q p2 and the switching tube Q p4 are connected together and connected with a node o; the source electrode of the switching tube Q p1 is connected with one end of a series inductor, and the other end of the inductor is connected with the same-name end of the primary side transformer winding; the synonym end of the primary side winding of the transformer is connected with the source electrode of Q p3; the driving signals of the switching tubes Q p1 and Q p2 are respectively driving signals with the duty ratio of 0.5, and the driving signals are complementary and have dead time; the driving signals of the switching tubes Q p3 and Q p4 are respectively driving signals with the duty ratio of 0.5, and the driving signals are complementary and have dead time; the time when the driving signals of the switching transistor Q p1 and the switching transistor Q p4 overlap divided by half of the switching period is defined as a duty ratio D 1p;
The secondary side full bridge of the DAB converter connected with the po node comprises 4 switching tubes Q p5-Qp8; the switching tube Q p5 and the switching tube Q p6 form a bridge arm, and the source electrode of the Q p5 is connected with the drain electrode of the Q p6; the switching tube Q p7 and the switching tube Q p8 form a bridge arm, and the source electrode of the Q p7 is connected with the drain electrode of the Q p8; the drains of the switching tubes Q p5 and Q p7 are connected together and connected with the positive electrode of the output capacitor to serve as the positive electrode of the output voltage; the sources of the switching tube Q p6 and the switching tube Q p8 are connected together and connected with the negative electrode of the output capacitor to serve as the negative electrode of the output voltage; the same-name end of the secondary side of the transformer is connected with the source electrode of the switching tube Q p5, and the different-name end of the secondary side winding of the transformer is connected with the source electrode of the switching tube Q p7; the driving signals of the switching tubes Q p5 and Q p6 are respectively driving signals with the duty ratio of 0.5, and the driving signals are complementary and have dead time; the driving signals of the switching tubes Q p7 and Q p8 are respectively driving signals with the duty ratio of 0.5, and the driving signals are complementary and have dead time; the time that the drive signals of the switch Q p5 and the switching transistor Q p8 overlap divided by half the switching period is defined as the duty ratio D 2p;
for the topological structure of the DAB converter connected with the on node, the primary side full bridge of the DAB converter comprises 4 switching tubes Q n1-Qn4; the switching tube Q n1 and the switching tube Q n2 form a bridge arm, and the source electrode of the Q n1 is connected with the drain electrode of the Q n2; the switching tube Q n3 and the switching tube Q n4 form a bridge arm, and the source electrode of the Q n3 is connected with the drain electrode of the Q n4; the drain electrode of the switch tube Q n1 is connected with the drain electrode of the switch tube Q n3 and is connected with a node o; the sources of the switch tube Q n2 and the switch tube Q n4 are connected together and connected with the emitter of the Q 2、Q4、Q6, and the anode of the switch tube Q n2 is connected with the anode of the D 2、D4、D6 under the SWISS rectifier topology; the source electrode of the switching tube Q n1 is connected with one end of a series inductor, and the other end of the inductor is connected with the same-name end of the primary side transformer winding; the synonym end of the primary side winding of the transformer is connected with the source electrode of Q n3; the driving signals of the switching tubes Q n1 and Q n2 are respectively driving signals with the duty ratio of 0.5, and the driving signals are complementary and have dead time; the driving signals of the switching tubes Q n3 and Q n4 are respectively driving signals with the duty ratio of 0.5, and the driving signals are complementary and have dead time; the time when the driving signals of the switching transistor Q n1 and the switching transistor Q n4 overlap divided by half of the switching period is defined as a duty ratio D 1n;
the secondary side full bridge of the DAB converter connected with the on node comprises 4 switching tubes Q n5-Qn8; the switching tube Q n5 and the switching tube Q n6 form a bridge arm, and the source electrode of the Q n5 is connected with the drain electrode of the Q n6; the switching tube Q n7 and the switching tube Q n8 form a bridge arm, and the source electrode of the Q n7 is connected with the drain electrode of the Q n8; the drains of the switching tubes Q n5 and Q n7 are connected together and connected with the positive electrode of the output capacitor to serve as the positive electrode of the output voltage; the sources of the switching tube Q n6 and the switching tube Q n8 are connected together and connected with the negative electrode of the output capacitor to serve as the negative electrode of the output voltage; the same-name end of the secondary side of the transformer is connected with the source electrode of the switching tube Q n5, and the different-name end of the secondary side winding of the transformer is connected with the source electrode of the switching tube Q n7; the driving signals of the switching tubes Q n5 and Q n6 are respectively driving signals with the duty ratio of 0.5, and the driving signals are complementary and have dead time; the driving signals of the switching tubes Q n7 and Q n8 are respectively driving signals with the duty ratio of 0.5, and the driving signals are complementary and have dead time; the time that the drive signals of the switch Q n5 and the switching transistor Q n8 overlap divided by half the switching period is defined as the duty ratio D 2n;
The method comprises the steps of obtaining phase shift angles and duty ratios corresponding to DAB converters connected by a po node and an on node according to a step four, respectively generating driving signals corresponding to two full-bridge switching tubes corresponding to the two DAB converters, wherein the driving signals are used for driving 16 switching tubes Q p1,Qp2,Qp3,Qp4,Qp5,Qp6,Qp7,Qp8 and Q n1,Qn2,Qn3,Qn4,Qn5,Qn6,Qn7,Qn8 to work, realizing power factor correction and output voltage control of the SWISS type converter based on DAB, optimizing the conduction loss and the modal control of a zero-voltage soft switch, and guaranteeing the soft switch realization of the two switching tubes of the two DAB converters 16 and the optimization of the peak current of a transformer.
The beneficial effects are that:
1. The invention discloses two control methods for power factor correction of SWISS type converter based on DAB, which are characterized in that firstly, aiming at the condition that the equivalent gain M p or M n is smaller than 1, the working mode of soft switch of DAB converter can be realized under the condition that the phase shift angle is small is analyzed and extracted, and the conduction loss is minimum; extracting the working mode corresponding to the minimum value of the peak current of the transformer in the DAB converter when the phase shift angle is large; and then, obtaining two critical phase shift angles according to the relation between the phase shift angles and the duty ratio, and further dividing the intermediate mode. Then, aiming at the condition that the equivalent gain M p or M n is larger than 1, the working mode of the soft switch of the DAB converter can be realized under the condition that the phase shift angle is small is analyzed and extracted; extracting the working mode corresponding to the minimum value of the peak current of the transformer in the DAB converter when the phase shift angle is large; then, according to the relation between the phase shift angle and the duty ratio, two critical phase shift angles are obtained, and then the intermediate mode is divided; zero-crossing modes are classified in consideration of the zero-crossing problem of the input voltage. Under the above conditions, 8 switching tubes in each DAB converter: when the alternating voltage is near 0V, the partial switching tube realizes zero-voltage soft switching, and the partial switching tube realizes zero-current soft switching; all switching tubes can realize zero-voltage soft switching in other cases. Meanwhile, the minimum peak current of the transformer can be realized, the conduction loss of the DAB converter is optimized, and the high efficiency of the SWISS type converter based on DAB is realized.
2. According to the seven working modes capable of realizing 8 switching tube soft switches and minimum conduction loss in each DAB converter in the beneficial effect 1, the control methods of the two SWISS type converters based on DAB are provided.
First control strategy: the voltage setting is compared with the converter output voltage, the amplitude control quantity of the input current is obtained through the voltage controller, the amplitude control quantity is multiplied by the maximum phase angle cosine value to be used as the reference value of the DAB converter input current connected with the po node, and the amplitude control quantity is multiplied by the minimum phase angle cosine value to be used as the reference value of the DAB converter input current connected with the on node.
A second control strategy: the voltage setting is compared with the converter output voltage, the amplitude reference quantity of the input current is obtained through a voltage controller, the obtained amplitude reference quantity of the input current is compared with the sampled input current amplitude, the amplitude control quantity of the input current is obtained through a current controller, the amplitude control quantity is multiplied by a maximum phase angle cosine value to be used as the reference value of the DAB converter input current connected with a po node, and the amplitude control quantity is multiplied by a minimum phase angle cosine value to be used as the reference value of the DAB converter input current connected with an on node.
And calculating the phase shift angle and the duty ratio corresponding to each mode of each DAB converter according to the relation between the current reference value and the phase shift angle of the DAB converter and the duty ratios corresponding to the two full bridges of the primary side and the secondary side. And generating driving signals corresponding to the two full-bridge switching tubes corresponding to the two DAB converters through the duty ratio and the phase shift angle. By means of the control strategy, the power factor correction and the control of the output voltage of the SWISS type converter based on DAB can be realized, and the sine of the input current can be maintained. Meanwhile, seven working modes can be switched according to the needs, and control of output voltage is achieved.
3. The invention discloses two control methods for power factor correction of SWISS type converters based on DAB, wherein the control quantity of duty ratio and phase shift angle is completed by combining the output of a controller in the first step with the phase angle in the second step and the relational expression in the fourth step, and the control is uniform and simple.
4. According to the control method for power factor correction of the SWISS type converter based on DAB, corresponding driving signals corresponding to two full-bridge switching tubes corresponding to two DAB converters are respectively generated according to phase shift angles and duty ratios corresponding to the DAB converters connected with a po node and an on node, the driving signals are used for driving 16 switching tubes to work, so that power factor correction and output voltage control of the SWISS type converter based on DAB are realized, the modal control of conduction loss and zero voltage soft switching is optimized, and optimization of soft switching of 16 switching tubes and peak current of a transformer in the two DAB converters is ensured.
Drawings
Fig. 1 shows a schematic diagram of a topology of a SWISS-type three-phase bidirectional converter based on DAB of the present embodiment;
FIG. 2 shows a schematic diagram of the topology of a SWISS type rectifier based on DAB of this embodiment;
FIG. 3a shows a closed-loop control block diagram of the no-current sampling power factor correction of the present invention;
FIG. 3b shows a closed-loop control block diagram of input current sampling power factor correction of the present invention;
FIG. 4a shows a block diagram of the modulation scheme of the DAB converter connected to the po node in the present invention;
FIG. 4b shows a block diagram of the modulation scheme of the DAB converter connected to the on node in the present invention;
FIG. 5a shows voltage and current waveforms for forward power mode 1 in the present invention;
FIG. 5b shows the voltage and current waveforms for reverse power mode 1 in the present invention;
FIG. 6a shows voltage and current waveforms for the forward power mode 2 of the present invention;
FIG. 6b shows voltage and current waveforms for reverse power mode 2 in the present invention;
FIG. 7a shows voltage and current waveforms for the forward power mode 1.5 of the present invention;
FIG. 7b shows the voltage and current waveforms for reverse power mode 1.5 in the present invention;
FIG. 8a shows voltage and current waveforms for the forward power mode 3c of the present invention;
FIG. 8b shows the voltage and current waveforms of the reverse power mode 3c of the present invention;
FIG. 9a shows voltage and current waveforms for forward power mode 3 in the present invention;
Fig. 9b shows the voltage and current waveforms for reverse power mode 3 in the present invention;
FIG. 10a shows voltage and current waveforms for the forward power mode 4 of the present invention;
FIG. 10b shows the voltage and current waveforms of the reverse power mode 4 of the present invention;
FIG. 11a shows voltage and current waveforms for the forward power mode 3.5 of the present invention;
fig. 11b shows the voltage and current waveforms for the reverse power mode 3.5 of the present invention.
Detailed Description
The technical problems and advantages solved by the technical solution of the present invention are also described in detail below with reference to the accompanying drawings and examples, and it should be noted that the described examples are only intended to facilitate understanding of the present invention and are not intended to limit the present invention in any way.
The control method of power factor correction of the SWISS type converter based on DAB of the embodiment is realized based on a circuit shown in fig. 1. The SWISS type converter based on DAB consists of a low-frequency sector selection circuit and a high-frequency switch network, wherein the low-frequency sector selection circuit consists of 6 switch tubes and 3 groups of bidirectional switch tubes, the high-frequency switch network consists of two DAB converters, and each full bridge at two sides of a transformer of each DAB converter consists of 4 switch tubes.
The driving signals of 3 groups of bidirectional switching tubes of the SWISS converter in the low-frequency sector selection circuit are all power frequency square wave signals. Each group of switching tubes is composed of emitters of two switching tubes which are in anti-series connection, and driving signals of the two switching tubes in each group are consistent. For the topology of the DAB-based SWISS-type converter shown in fig. 1, the network side abc three-phase voltages correspond to three legs respectively, Q 1、Q3、Q5 constitutes the upper leg, and Q 2、Q4、Q6 constitutes the lower leg. The a-phase bridge arm is formed by connecting an emitter electrode of Q 1 and a collector electrode of Q 2; the b-phase bridge arm is formed by connecting an emitter electrode of Q 3 and a collector electrode of Q 4; the c-phase bridge arm is formed by connecting an emitter of Q 5 and a collector of Q 6. The collector electrodes of the switching tubes Q 1、Q3、Q5 are connected together to serve as the positive electrode of the input end of the DAB converter connected with the po node, and the positive electrode is defined as a node p; the emitter of the switch tube Q 2、Q4、Q6 is connected together to be used as the negative electrode of the input end of the DAB converter connected with the on node, and the node is defined as a node n; the three groups of bidirectional switches are connected in parallel and respectively used as the negative electrode of the input end of the DAB converter connected with the po node and the positive electrode of the input end of the DAB converter connected with the on node, and the node is defined as a node o. The drive signal is still determined by the sector in which the three-phase grid voltage combining vector is located. Preferably, the driving signal for generating the switch in the third step is directed to the three groups of bidirectional switches and six switching tubes on the bridge arm. In each sector, a corresponding upper bridge arm switching tube with the phase voltage value at the maximum value is conducted; a corresponding lower bridge arm switch tube with the phase voltage value at the minimum value is conducted; a corresponding bi-directional switch with the phase voltage value in the neutral position is turned on. The switching frequency of the switching tube on the bridge arm is power frequency, and the switching frequency of the bidirectional switch is double power frequency. For example, in the sector 1, v ga>vgb>vgc, where v ga、vgb、vgc is the phase voltage of the three phases of the network side abc, the upper tube Q 1 corresponding to the a-phase bridge arm is turned on, the lower tube Q 6 corresponding to the c-phase bridge arm is turned on, and the bi-directional switch S vb corresponding to the b-phase bridge arm is turned on.
For the topology of the DAB-based SWISS-type rectifier shown in fig. 2, the network side abc three-phase voltages correspond to three legs respectively, D 1、D3、D5 constitutes the upper leg, and D 2、D4、D6 constitutes the lower leg. The a-phase bridge arm is formed by connecting an anode of D 1 and a cathode of D 2; the b-phase bridge arm is formed by connecting an anode of D 3 and a cathode of D 4; the c-phase bridge arm is formed by connecting an anode of D 5 and a cathode of D 6. The cathodes of the diodes D 1、D3、D5 are connected together to serve as the positive electrode of the input end of the DAB converter connected with the po node, and the positive electrode is defined as a node p; the anodes of the diodes D 2、D4、D6 are connected together to serve as the negative electrode of the input end of the DAB converter connected with the on node, and the node is defined as a node n; the three groups of bidirectional switches are connected in parallel and respectively used as the negative electrode of the input end of the DAB converter connected with the po node and the positive electrode of the input end of the DAB converter connected with the on node, and the node is defined as a node o. And a corresponding bidirectional switch with the phase voltage value at the middle position in each sector is conducted, and the switching frequency of each group of bidirectional switches is twice the power frequency. For example, in sector 1 v ga>vgb>vgc, the bi-directional switch S vb corresponding to b is turned on. According to the conduction rule, the output voltage between the po and on nodes is the steamed bread wave with triple frequency, and SWISS rectification is realized.
The SWISS converter is followed by two DAB converter circuits. Each DAB converter comprises 8 switching tubes, 16 switching tubes in total, namely Q p1,Qp2,Qp3,Qp4,Qp5,Qp6,Qp7,Qp8 and Q n1,Qn2,Qn3,Qn4,Qn5,Qn6,Qn7,Qn8. Taking the DAB converter connected with the po node as an example for explanation, the node A and the node B are respectively midpoints of two bridge arms of the primary side full bridge, and the node C and the node D are respectively midpoints of two bridge arms of the secondary side full bridge. i rp is the current of the primary winding of the transformer. v in_p and v o are the input and output voltages of the primary side and the secondary side of the DAB converter connected to the po node respectively, and define the voltage gain M p＝vo/nvin_p of the converter, where n is the ratio of the number of secondary side turns to the number of primary side turns of the transformer. Accordingly, the voltage gain M n of the DAB converter connected to the on node may be expressed as M n＝vo/nvin_n,vin_n being the primary side input voltage of the DAB converter connected to the on node.
The primary full bridge of the DAB converter connected to the po node comprises 4 switching tubes Q p1-Qp4. The switching tube Q p1 and the switching tube Q p2 form a bridge arm, and the source electrode of the Q p1 is connected with the drain electrode of the Q p2. The switching tube Q p3 and the switching tube Q p4 form a bridge arm, and the source electrode of the Q p3 is connected with the drain electrode of the Q p4. The drain of the switch tube Q p1 is connected with the drain of the switch tube Q p3 together and is connected with the collector of the Q 1、Q3、Q5, and the drain is connected with the cathode of the D 1、D3、D5 under the SWISS rectifier topology; the sources of the switching tube Q p2 and the switching tube Q p4 are connected together and connected to the node o. The source electrode of the switch tube Q p1 is connected with one end of a series inductor, and the other end of the inductor is connected with the homonymous end of the primary side transformer winding. The synonym end of the primary winding of the transformer is connected with the source electrode of Q p3. The driving signals of the switching transistors Q p1 and Q p2 are driving signals with a duty ratio of 0.5, respectively, and the driving signals are complementary and have dead time. The driving signals of the switching transistors Q p3 and Q p4 are driving signals with a duty ratio of 0.5, respectively, and the driving signals are complementary and have dead time. The time that the drive signals of the switching transistor Q p1 and the switching transistor Q p4 overlap divided by half the switching period is defined as the duty ratio D 1p.
The secondary side full bridge of the DAB converter connected with the po node comprises 4 switching tubes Q p5-Qp8. The switching tube Q p5 and the switching tube Q p6 form a bridge arm, and the source electrode of the Q p5 is connected with the drain electrode of the Q p6. The switching tube Q p7 and the switching tube Q p8 form a bridge arm, and the source electrode of the Q p7 is connected with the drain electrode of the Q p8. The drains of the switch transistors Q p5 and Q p7 are connected together and connected with the positive electrode of the output capacitor to serve as the positive electrode of the output voltage. The sources of the switch tube Q p6 and the switch tube Q p8 are connected together and connected with the negative electrode of the output capacitor to serve as the negative electrode of the output voltage. The same name end of the secondary side of the transformer is connected with the source electrode of the switching tube Q p5, and the different name end of the secondary side winding of the transformer is connected with the source electrode of the switching tube Q p7. The driving signals of the switching transistors Q p5 and Q p6 are driving signals with a duty ratio of 0.5, respectively, and the driving signals are complementary and have dead time. The driving signals of the switching transistors Q p7 and Q p8 are driving signals with a duty ratio of 0.5, respectively, and the driving signals are complementary and have dead time. The time that the drive signals of the switch Q p5 and the switching transistor Q p8 overlap divided by half the switching period is defined as the duty cycle D 2p.
The primary side full bridge of the DAB converter connected with the on node comprises 4 switching tubes Q n1-Qn4; the switching tube Q n1 and the switching tube Q n2 form a bridge arm, and the source electrode of the Q n1 is connected with the drain electrode of the Q n2; the switching tube Q n3 and the switching tube Q n4 form a bridge arm, and the source electrode of the Q n3 is connected with the drain electrode of the Q n4; the drain electrode of the switch tube Q n1 is connected with the drain electrode of the switch tube Q n3 and is connected with a node o; the sources of the switch tube Q n2 and the switch tube Q n4 are connected together and connected with the emitter of the Q 2、Q4、Q6, and the anode of the switch tube Q n2 is connected with the anode of the D 2、D4、D6 under the SWISS rectifier topology; the source electrode of the switching tube Q n1 is connected with one end of a series inductor, and the other end of the inductor is connected with the same-name end of the primary side transformer winding; the synonym end of the primary side winding of the transformer is connected with the source electrode of Q n3; the driving signals of the switching tubes Q n1 and Q n2 are respectively driving signals with the duty ratio of 0.5, and the driving signals are complementary and have dead time; the driving signals of the switching tubes Q n3 and Q n4 are respectively driving signals with the duty ratio of 0.5, and the driving signals are complementary and have dead time; the time when the driving signals of the switching transistor Q n1 and the switching transistor Q n4 overlap divided by half of the switching period is defined as a duty ratio D 1n;
the secondary side full bridge of the DAB converter connected with the on node comprises 4 switching tubes Q n5-Qn8; the switching tube Q n5 and the switching tube Q n6 form a bridge arm, and the source electrode of the Q n5 is connected with the drain electrode of the Q n6; the switching tube Q n7 and the switching tube Q n8 form a bridge arm, and the source electrode of the Q n7 is connected with the drain electrode of the Q n8; the drains of the switching tubes Q n5 and Q n7 are connected together and connected with the positive electrode of the output capacitor to serve as the positive electrode of the output voltage; the sources of the switching tube Q n6 and the switching tube Q n8 are connected together and connected with the negative electrode of the output capacitor to serve as the negative electrode of the output voltage; the same-name end of the secondary side of the transformer is connected with the source electrode of the switching tube Q n5, and the different-name end of the secondary side winding of the transformer is connected with the source electrode of the switching tube Q n7; the driving signals of the switching tubes Q n5 and Q n6 are respectively driving signals with the duty ratio of 0.5, and the driving signals are complementary and have dead time; the driving signals of the switching tubes Q n7 and Q n8 are respectively driving signals with the duty ratio of 0.5, and the driving signals are complementary and have dead time; the time that the drive signals of the switch Q n5 and the switching transistor Q n8 overlap divided by half the switching period is defined as the duty ratio D 2n;
example 1: fig. 3a is a closed-loop control block diagram of the no-current sampling power factor correction of the present invention.
The control method for the current-free sampling power factor correction of the SWISS type converter based on DAB disclosed by the embodiment comprises the following specific control steps:
Step one: the voltage error obtained by subtracting the voltage reference V ref and the output voltage feedback V o is outputted as an input current amplitude control quantity y, y epsilon < -1,1 > through an output voltage controller;
Step two: sampling an input side a-phase voltage V ga, and obtaining a grid phase voltage amplitude V m and a phase angle theta of the a-phase after passing through a second-order generalized integrator and a phase-locked loop, wherein theta is E [0,2 pi ]; respectively adding or subtracting 2 pi/3 to the phase angle theta to obtain phase angles of a c phase and a b phase, and further obtaining cosine values of the three-phase angles; multiplying the input current amplitude control quantity y and the maximum phase angle cosine value by a multiplier to obtain an input current given value of the DAB converter connected with the po node, and similarly multiplying the input current amplitude control quantity y and the minimum phase angle cosine value by the multiplier to obtain an input current given value of the DAB converter connected with the on node by y cos min, and respectively calculating to obtain phase shift angle values corresponding to the two DAB converters by the two input current given values;
Step three: fig. 4a and fig. 4b are block diagrams of modulation flow of DAB converters to which the po node and the on node are connected, respectively, in the present invention. Generating a driving signal of a bidirectional switch in the SWISS converter according to the sector where the network side three-phase voltage is located; the expression of the primary input side voltage v in_p of the DAB converter connected with the output of the po node is shown in the formula (1), and the expression of the primary input side voltage v in_n of the DAB converter connected with the output of the on node is shown in the formula (2).
According to the sampled output voltage v o of the secondary side of the DAB converter, the equivalent voltage gains M p and M n,Mp of the DAB converter connected with the po node and the on node are respectively calculated, v o/(nvin_p),Mn is v o/(nvin_n, and n is the ratio of the number of turns of the secondary side to the number of turns of the primary side of the transformer.
Step four: according to the phase shift angles obtained by the second and third steps and the values of M p and M n, dividing the two DAB converters to work in the following 7 modes: when M p or M n is smaller than 1, judging that the DAB works in three working modes of mode 1 or mode 1.5 or mode 2, further judging that the DAB converter works in one specific working mode of the three working modes according to the phase shift angle, and calculating to obtain the corresponding duty ratio and phase shift angle under mode 1 or mode 1.5 or mode 2; when M p or M n is larger than 1, judging that DAB works in four working modes of mode 3 or mode 3c or mode 3.5 or mode 4, further judging that the DAB converter works in one specific working mode of the four working modes according to the phase shift angle and the input voltage, and calculating to obtain the corresponding duty ratio and the phase shift angle under the corresponding mode 3 or mode 3c or mode 3.5 or mode 4; through the mode switching mode, the power factor correction and the output voltage control of the SWISS converter based on DAB are realized, the conduction loss and the mode control of the zero-voltage soft switch are optimized, and the optimization of soft switches of 8 switching tubes and peak current of a transformer under seven modes of each DAB converter is ensured.
According to the M p value and the phase shift angle value obtained by calculation in the second step and the third step, the DAB converter connected with the dividing po node works in the following 7 modes:
When M p is smaller than 1, DAB works in three working modes of mode 1, mode 1.5 or mode 2: and calculating the phase shift angle of the three working modes and the critical phase shift angle of the mode switching, wherein the phase shift angle is shown in a formula (3). Under the condition that M p is smaller than 1, further judging that the DAB converter works in a specific working mode in the three working modes according to the phase shift angle:
When (when) When the DAB converter is judged to work in a mode 1, and the corresponding duty ratio and phase shift angle of the DAB converter in the mode 1 are calculated, as shown in a formula (4), and voltage and current waveforms corresponding to forward and reverse power are shown in figures 5a and 5b respectively; when/>When the DAB converter is judged to work in a mode 2, and the corresponding duty ratio and phase shift angle of the DAB converter in the mode 2 are calculated, as shown in a formula (5), and voltage and current waveforms corresponding to forward and reverse power are shown in fig. 6a and 6b respectively; when/>When the DAB converter is in the mode 1.5, the corresponding duty ratio and phase shift angle of the DAB converter in the mode 1.5 are calculated, as shown in the formula (6), and the voltage and current waveforms corresponding to the forward and reverse power are shown in fig. 7a and 7b respectively. At this time/>It is explained that the DAB converter is operating in mode 1.5; if/> The DAB converter is judged to work in the mode 2, and the duty ratio and the phase shift angle are obtained according to the expression in the mode 2.
When M p is larger than 1, determining that DAB works in four working modes of mode 3 or mode 3c or mode 3.5 or mode 4: and calculating the phase shift angle of the four working modes, and the critical phase shift angle and the critical input voltage of the mode switching, as shown in a formula (7).
Under the condition that M p is larger than 1, further judging that the DAB converter works in a specific working mode in the four working modes according to the phase shift angle and the input voltage:
When (when) When the DAB converter is judged to work in a mode 3 or a mode 3c, and the DAB converter is further judged to work in one specific working mode of the two working modes according to the magnitude of the input voltage: when v in_p≤Vin_th is reached, the DAB converter is judged to work in the mode 3c, and the corresponding duty ratio and phase shift angle of the DAB converter in the mode 3c are calculated, as shown in a formula (8), and voltage and current waveforms corresponding to forward and reverse power are shown in fig. 8a and 8b respectively; when v in_p>Vin_th is reached, the DAB converter is judged to work in a mode 3, and the corresponding duty ratio and phase shift angle of the DAB converter under the mode 3 are calculated, as shown in a formula (9), and voltage and current waveforms corresponding to forward and reverse power are shown in fig. 9a and 9b respectively; when (when)When the DAB converter is judged to work in a mode 4, and the corresponding duty ratio and phase shift angle of the DAB converter in the mode 4 are calculated and obtained, as shown in a formula (10), voltage and current waveforms corresponding to forward and reverse power are shown in fig. 10a and 10b respectively; when/>When the DAB converter is operated in the mode 3.5, the corresponding duty ratio and phase shift angle of the DAB converter in the mode 3.5 are calculated, as shown in the formula (11), and the voltage and current waveforms corresponding to the forward and reverse power are shown in fig. 11a and 11b respectively. At this time/>It is explained that the DAB converter is operating in mode 3.5; if/>The DAB converter is determined to operate in mode 4 and the duty cycle and phase shift angle are determined again from the expression in mode 4.
Under the condition that M p is equal to 1, the corresponding duty ratio and phase shift angle of the DAB converter are directly calculated, and are shown as a formula (12). Obtained in the above modesWhen power flows forward/>Greater than 0; when power flows in reverse/>Less than 0.
According to the M n value and the phase shift angle value obtained by calculation in the second step and the third step, the DAB converter connected with the dividing on node works in the following 7 modes:
When M n is smaller than 1, DAB works in three working modes of mode 1, mode 1.5 or mode 2: and calculating the phase shift angle of the three working modes and the critical phase shift angle of the mode switching, wherein the phase shift angle is shown in a formula (13). Under the condition that M n is smaller than 1, further judging that the DAB converter works in a specific working mode in the three working modes according to the phase shift angle:
When (when) When the DAB converter is judged to work in a mode 1, and the corresponding duty ratio and phase shift angle of the DAB converter in the mode 1 are calculated, as shown in a formula (14); when/>When the DAB converter works in the mode 2, the corresponding duty ratio and the phase shift angle of the DAB converter in the mode 2 are obtained through calculation, and the phase shift angle is shown as a formula (15); when/> When the DAB converter is in the mode 1.5, the corresponding duty ratio and phase shift angle of the DAB converter in the mode 1.5 are calculated, and the phase shift angle is shown as a formula (16). At this time/>It is explained that the DAB converter is operating in mode 1.5; if/>The DAB converter is judged to work in the mode 2, and the duty ratio and the phase shift angle are obtained according to the expression in the mode 2.
When M n is larger than 1, determining that DAB works in four working modes of mode 3 or mode 3c or mode 3.5 or mode 4: and calculating the phase shift angle of the four working modes, and the critical phase shift angle and the critical input voltage of the mode switching, as shown in a formula (17). Under the condition that M n is larger than 1, further judging that the DAB converter works in a specific working mode in the four working modes according to the phase shift angle and the input voltage:
When (when) When the DAB converter is judged to work in a mode 3 or a mode 3c, and the DAB converter is further judged to work in one specific working mode of the two working modes according to the magnitude of the input voltage: when v in_n≤Vin_th is reached, judging that the DAB converter works in the mode 3c, and calculating to obtain the corresponding duty ratio and phase shift angle of the DAB converter in the mode 3c, wherein the duty ratio and phase shift angle are shown as a formula (18); when v in_n>Vin_th is reached, judging that the DAB converter works in a mode 3, and calculating to obtain the corresponding duty ratio and phase shift angle of the DAB converter in the mode 3, wherein the duty ratio and phase shift angle are shown as a formula (19); when/>When the DAB converter is judged to work in a mode 4, and the corresponding duty ratio and phase shift angle of the DAB converter in the mode 4 are calculated, as shown in a formula (20); when/> When the DAB converter is in the mode 3.5, the corresponding duty ratio and phase shift angle of the DAB converter in the mode 3.5 are calculated, and the phase shift angle is shown as a formula (21). At this time/>It is explained that the DAB converter is operating in mode 3.5; if/>The DAB converter is determined to operate in mode 4 and the duty cycle and phase shift angle are determined again from the expression in mode 4.
Under the condition that M n is equal to 1, the corresponding duty ratio and phase shift angle of the DAB converter are directly calculated, and are shown as a formula (22). Obtained in the above modesWhen power flows forward/>Greater than 0; when power flows in reverse/>Less than 0.
Step five: according to the phase shift angles and the duty ratios corresponding to the DAB converters connected with the po node and the on node obtained in the step four, driving signals corresponding to two full-bridge switching tubes corresponding to the two DAB converters are respectively generated, and the driving signals are used for driving 16 switching tubes to work; the DAB converter switches the working modes according to the requirements, so that the power factor correction and the output voltage control of the SWISS type converter based on DAB are realized, the conduction loss and the mode control of the zero-voltage soft switch are optimized, and the soft switch realization of 16 switching tubes in the two DAB converters and the optimization of the peak current of the transformer are ensured.
Example 2: fig. 3b is a closed loop control block diagram of the no current sample power factor correction of the present invention.
The control method for input current sampling power factor correction of the SWISS type converter based on DAB disclosed by the embodiment comprises the following specific control steps:
Step one: the voltage error obtained by subtracting the voltage reference V ref and the output voltage feedback V o is outputted by the output voltage controller, and the reference value y v,yv of the input current amplitude is defined as the reference value of the per unit value of the input current amplitude, and y v epsilon < -1,1 >; phase locking is carried out on the three-phase voltage to obtain a phase angle theta m of a synthesized voltage vector, abc-dq conversion of the three-phase power grid current obtained through sampling is sent to obtain a component i gd of the three-phase power grid current on the d axis and a component i gq of the three-phase power grid current on the q axis, and the amplitude of the input current is calculated Carrying out per unit processing on the input current amplitude I m to obtain a per unit value I m *,Im * epsilon < -1,1 > of the input current amplitude; wherein the positive and negative of I m * are determined by the power flow direction, I m * >0 and I gd >0 in forward power flow, and I m * <0 and I gd <0 in reverse power flow. Judging the positive and negative of the I m * according to the positive and negative of the I gd; then the current error obtained by subtracting the input current amplitude reference value y v and the input current amplitude per unit value I m * is outputted as an input current amplitude control value y, y epsilon < -1,1 > through an input current controller;
Step two: sampling an input side a-phase voltage V ga, and obtaining a grid phase voltage amplitude V m and a phase angle theta of the a-phase after passing through a second-order generalized integrator and a phase-locked loop, wherein theta is E [0,2 pi ]; respectively adding or subtracting 2 pi/3 to the phase angle theta to obtain phase angles of a c phase and a b phase, and further obtaining cosine values of the three-phase angles; multiplying the input current amplitude control quantity y and the maximum phase angle cosine value by a multiplier to obtain an input current given value of the DAB converter connected with the po node, and similarly multiplying the input current amplitude control quantity y and the minimum phase angle cosine value by the multiplier to obtain an input current given value of the DAB converter connected with the on node by y cos min, and respectively calculating to obtain phase shift angle values corresponding to the two DAB converters by the two input current given values;
The control method of the SWISS type converter input current sampling power factor correction based on DAB is the same as the steps three, four and five of the control method of the no current sampling power factor correction.
The topological structure of a two-stage AC-DC converter is widely adopted in the fields of bidirectional charge and discharge of electric automobiles and new energy power generation, and a front stage adopts a non-isolated AC-DC converter topology, such as a T-shaped three-level topology; the latter stage employs an isolated DC-DC converter topology, such as a CLLC resonant converter topology. Under the topological structure of the T-type three-level topological cascading CLLC resonant converter, the CLLC resonant bidirectional converter is difficult to realize smooth switching of bidirectional power, so that the application of the CLLC resonant bidirectional converter in the field of frequent bidirectional power switching such as energy storage is limited, and the regulation range of output voltage under the topology is smaller. The efficiency of the two-stage AC-DC converter topology applied to the electric vehicle bidirectional charge and discharge and new energy power generation fields is about 96.5%, and the SWISS type converter based on DAB adopting the control method in embodiments 1 and 2 belongs to a single-stage AC-DC converter, and the efficiency can reach about 97.5%. The DAB-based SWISS-type converter can achieve a wider range of output voltages and higher operating efficiency with fewer power electronics used than the two-stage AC-DC converter topology.
While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
Claims (7)
1. DAB-based SWISS-type converter characterized by: the SWISS type converter based on DAB is an isolated three-phase AC/DC converter, a network side is connected to a SWISS converter circuit topology working at low frequency, the power grid voltage passes through the SWISS converter, and three times of power frequency steamed bread waves are generated between po and on nodes and are respectively used as the input of the DAB converters at high frequency switches; each DAB converter is isolated through a transformer, and the primary side and the secondary side of the transformer are respectively two full bridges and output for connecting any load; the switching of working modes of the DAB converter is used for controlling the duty ratio of two full bridges and the phase shift angle corresponding to the voltage waveform to realize the power factor correction of the converter; the output side is connected with the outputs of the two DAB converters in parallel to obtain output voltage.
2. A SWISS-type converter currentless sampling power factor correction control method based on DAB as claimed in claim 1, characterized in that: comprises the following steps of the method,
Step one: the voltage error obtained by subtracting the voltage reference V ref and the output voltage feedback V o is outputted as an input current amplitude control quantity y, y epsilon < -1,1 > through an output voltage controller;
Step two: sampling an input side a-phase voltage V ga, and obtaining a grid phase voltage amplitude V m and a phase angle theta of the a-phase after phase locking by a second-order generalized integrator, wherein theta is 0 and 2 pi; respectively adding or subtracting 2 pi/3 to the phase angle theta to obtain phase angles of a c phase and a b phase, and further obtaining cosine values of the three-phase angles; multiplying the input current amplitude control quantity y and the maximum phase angle cosine value by a multiplier to obtain an input current given value of the DAB converter connected with the po node, and similarly multiplying the input current amplitude control quantity y and the minimum phase angle cosine value by the multiplier to obtain an input current given value of the DAB converter connected with the on node by y cos min, and respectively calculating to obtain phase shift angle values corresponding to the two DAB converters by the two input current given values;
Step three: generating a driving signal of a bidirectional switch in the SWISS converter according to the sector where the network side three-phase voltage is located; the expression of the primary input side voltage v in_p of the DAB converter connected with the output of the po node is
Wherein V ab、vba、vbc、vcb、vca、vac is the difference between the phase voltages of ab phase, ba phase, bc phase, cb phase, ca phase, ac phase, V m is the phase voltage amplitude, θ is the phase angle of the a phase voltage;
the expression of the primary input side voltage v inn of the DAB converter connected with the output of the on node is
According to the sampled output voltage v o of the secondary side of the DAB converter, respectively calculating equivalent voltage gains M p and M n,Mp of the DAB converter connected with the po node and the on node, wherein v o/(nvin_p),Mn is v o/(nvin_n, and n is the ratio of the number of turns of the secondary side to the number of turns of the primary side of the transformer;
step four: according to the phase shift angles obtained by the second and third steps and the values of M p and M n, dividing the two DAB converters to work in the following 7 modes: when M p or M n is smaller than 1, judging that the DAB works in three working modes of mode 1 or mode 1.5 or mode 2, further judging that the DAB converter works in one specific working mode of the three working modes according to the phase shift angle, and calculating to obtain the corresponding duty ratio and phase shift angle under mode 1 or mode 1.5 or mode 2; when M p or M n is larger than 1, judging that DAB works in four working modes of mode 3 or mode 3c or mode 3.5 or mode 4, further judging that the DAB converter works in one specific working mode of the four working modes according to the phase shift angle and the input voltage, and calculating to obtain the corresponding duty ratio and the phase shift angle under the corresponding mode 3 or mode 3c or mode 3.5 or mode 4; through the mode switching mode, the power factor correction and the output voltage control of the SWISS converter based on DAB are realized, the conduction loss and the mode control of the zero-voltage soft switch are optimized, and the optimization of soft switches of 8 switching tubes and peak current of a transformer under seven modes of each DAB converter is ensured;
step five: according to the phase shift angles and the duty ratios corresponding to the DAB converters connected with the po node and the on node obtained in the step four, driving signals corresponding to two full-bridge switching tubes corresponding to the two DAB converters are respectively generated, and the driving signals are used for driving 16 switching tubes to work; the DAB converter switches the working modes according to the requirements, so that the power factor correction and the output voltage control of the SWISS type converter based on DAB are realized, the conduction loss and the mode control of the zero-voltage soft switch are optimized, and the soft switch realization of 16 switching tubes in the two DAB converters and the optimization of the peak current of the transformer are ensured.
3. A control method for input current sampling power factor correction based on a SWISS-type converter of DAB according to claim 1, characterized in that: comprises the following steps of the method,
Step one: the voltage error obtained by subtracting the voltage reference V ref and the output voltage feedback V o is outputted by the output voltage controller, and the reference value y v,yv of the input current amplitude is defined as the reference value of the per unit value of the input current amplitude, and y v epsilon < -1,1 >; phase locking is carried out on the three-phase voltage to obtain a phase angle theta m of a synthesized voltage vector, abc-dq conversion of the three-phase power grid current obtained through sampling is sent into the phase angle theta m, and a per unit value I m *,Im * epsilon < -1,1 > of the input current amplitude is obtained through a calculation unit; wherein the positive and negative of I m * are determined by the power flow direction, I m * >0 and I gd >0 in forward power flow, and I m * <0 and I gd <0 in reverse power flow; wherein i gd is a current component corresponding to a d axis after the three-phase grid current is subjected to abc-dq transformation; judging the positive and negative of the I m * according to the positive and negative of the I gd; then the current error obtained by subtracting the input current amplitude reference value y v and the input current amplitude per unit value I m * is outputted as an input current amplitude control value y, y epsilon < -1,1 > through an input current controller;
Step two: sampling an input side a-phase voltage V ga, and obtaining a grid phase voltage amplitude V m and a phase angle theta of the a-phase after phase locking by a second-order generalized integrator, wherein theta is 0 and 2 pi; respectively adding or subtracting 2 pi/3 to the phase angle theta to obtain phase angles of a c phase and a b phase, and further obtaining cosine values of the three-phase angles; multiplying the input current amplitude control quantity y and the maximum phase angle cosine value by a multiplier to obtain an input current given value of the DAB converter connected with the po node, and similarly multiplying the input current amplitude control quantity y and the minimum phase angle cosine value by the multiplier to obtain an input current given value of the DAB converter connected with the on node by y cos min, and respectively calculating to obtain phase shift angle values corresponding to the two DAB converters by the two input current given values;
Step three: generating a driving signal of a bidirectional switch in the SWISS converter according to the sector where the network side three-phase voltage is located; the expression of the primary input side voltage v in_p of the DAB converter connected with the output of the po node is
Wherein V ab、vba、vbc、vcb、vca、vac is the difference between the phase voltages of ab phase, ba phase, bc phase, cb phase, ca phase, ac phase, V m is the phase voltage amplitude, θ is the phase angle of the a phase voltage;
The expression of the primary input side voltage v in_n of the DAB converter connected with the output of the on node is
According to the sampled output voltage v o of the secondary side of the DAB converter, respectively calculating equivalent voltage gains M p and M n,Mp of the DAB converter connected with the po node and the on node, wherein v o/(nvin_p),Mn is v o/(nvin_n, and n is the ratio of the number of turns of the secondary side to the number of turns of the primary side of the transformer;
step four: according to the phase shift angles obtained by the second and third steps and the values of M p and M n, dividing the two DAB converters to work in the following 7 modes: when M p or M n is smaller than 1, judging that the DAB works in three working modes of mode 1 or mode 1.5 or mode 2, further judging that the DAB converter works in one specific working mode of the three working modes according to the phase shift angle, and calculating to obtain the corresponding duty ratio and phase shift angle under mode 1 or mode 1.5 or mode 2; when M p or M n is larger than 1, judging that DAB works in four working modes of mode 3 or mode 3c or mode 3.5 or mode 4, further judging that the DAB converter works in one specific working mode of the four working modes according to the phase shift angle and the input voltage, and calculating to obtain the corresponding duty ratio and the phase shift angle under the corresponding mode 3 or mode 3c or mode 3.5 or mode 4; through the mode switching mode, the power factor correction and the output voltage control of the SWISS converter based on DAB are realized, the conduction loss and the mode control of the zero-voltage soft switch are optimized, and the optimization of soft switches of 8 switching tubes and peak current of a transformer under seven modes of each DAB converter is ensured;
Step five: according to the phase shift angles and the duty ratios corresponding to the DAB converters connected with the po node and the on node obtained in the step four, driving signals corresponding to two full-bridge switching tubes corresponding to the two DAB converters are respectively generated, and the driving signals are used for driving 16 switching tubes to work; the DAB converter switches the working modes according to the requirements, so that the power factor correction and the output voltage control of the SWISS type converter based on DAB are realized, the conduction loss and the mode control of the zero-voltage soft switch are optimized, and the soft switch realization of 16 switching tubes in the two DAB converters and the optimization of the peak current of the transformer are ensured. .
4. A control method according to claim 2 or 3, characterized in that: in the fourth step, the DAB converter connected with the po node is divided to work in the following specific implementation method of 7 modes according to the M p value and the phase shift angle value calculated in the second step and the third step, and the specific implementation method comprises the following steps:
When M p is smaller than 1, DAB works in three working modes of mode 1, mode 1.5 or mode 2: calculating the phase shift angle of three working modes and the critical phase shift angle of mode switching, wherein
The y cos_max is an input current given value of the DAB converter connected with the po node, L r is an inductance value of the series inductor, T s is a switching period, I ZVS1 is a minimum current amplitude of the DAB converter primary side full-bridge switching tube for realizing soft switching, and I ZVS2 is a minimum current amplitude of the DAB converter secondary side full-bridge switching tube for realizing soft switching; The phase shift angle corresponding to the DAB converter in mode 1 is used; /(I) The phase shift angle is corresponding to the phase shift angle of the DAB converter under the mode 1.5; /(I)The phase shift angle corresponding to the DAB converter in mode 2 is used; /(I)When M p is smaller than 1, determining that the DAB converter is particularly operated in a critical phase shift angle of a mode 1 or a mode 1.5; /(I)When M p is smaller than 1, determining that the DAB converter is particularly operated in a critical phase shift angle of a mode 1.5 or a mode 2; under the condition that M p is smaller than 1, further judging that the DAB converter works in a specific working mode in the three working modes according to the phase shift angle:
When (when) When the DAB converter works in the mode 1, the corresponding duty ratio and phase shift angle of the DAB converter in the mode 1 are calculated and obtained
Wherein,The phase shift angle of the DAB converter connected with the po node is D 1p which is the duty ratio of the primary side full bridge of the DAB converter, and D 2p which is the duty ratio of the secondary side full bridge of the DAB converter;
When (when) When the DAB converter works in the mode 2, the corresponding duty ratio and phase shift angle of the DAB converter in the mode 2 are calculated and obtained
When (when)When the DAB converter is in the mode 1.5, the corresponding duty ratio and phase shift angle of the DAB converter in the mode 1.5 are calculated and obtained
At this time ifIt is explained that the DAB converter is operating in mode 1.5; if/>Judging that the DAB converter works in a mode 2, and obtaining the duty ratio and the phase shift angle according to an expression in the mode 2;
When M p is larger than 1, determining that DAB works in four working modes of mode 3 or mode 3c or mode 3.5 or mode 4: calculating the phase shift angle of four working modes, and the critical phase shift angle and critical input voltage of mode switching, wherein
The phase shift angle corresponding to the DAB converter working under the condition of the mode 3 is obtained; /(I)The corresponding phase shift angle of the DAB converter under the condition of the mode 3c is obtained; /(I)The phase shift angle is corresponding to the DAB converter working under the condition of the mode 3.5; /(I)The phase shift angle of the DAB converter under the condition of mode 4 is corresponding; /(I)In order to determine that the DAB converter is particularly operated in the critical phase shift angle of mode 3 or mode 3.5 when M p is greater than 1,/>When M p is larger than 1, determining that the DAB converter is particularly operated in a critical phase shift angle of a mode 3.5 or a mode 4; v in_th is the critical phase shift angle for determining whether the DAB converter is operating in mode 3 c;
Under the condition that M p is larger than 1, further judging that the DAB converter works in a specific working mode in the four working modes according to the phase shift angle and the input voltage:
When (when) When the DAB converter is judged to work in a mode 3 or a mode 3c, and the DAB converter is further judged to work in one specific working mode of the two working modes according to the magnitude of the input voltage:
When v in_p≤Vin_th is reached, the DAB converter is judged to work in the mode 3c, and the corresponding duty ratio and phase shift angle of the DAB converter in the mode 3c are calculated
When v in_p>Vin_th is reached, the DAB converter is judged to work in the mode 3, and the corresponding duty ratio and phase shift angle of the DAB converter in the mode 3 are calculated
When (when)When the DAB converter works in the mode 4, the corresponding duty ratio and phase shift angle of the DAB converter in the mode 4 are calculated and obtained
When (when)When the DAB converter is in the mode 3.5, the corresponding duty ratio and phase shift angle of the DAB converter in the mode 3.5 are calculated
At this time ifIt is explained that the DAB converter is operating in mode 3.5; if/>Judging that the DAB converter works in a mode 4, and obtaining the duty ratio and the phase shift angle according to an expression in the mode 4;
Under the condition that M p is equal to 1, the corresponding duty ratio and phase shift angle of the DAB converter are obtained by direct calculation
Obtained in the above modesWhen power flows forward/>Greater than 0; when power flows in reverse/>Less than 0.
5. A control method according to claim 2 or 3, characterized in that: in the fourth step, the DAB converter connected with the node is divided to work in the following specific implementation method of 7 modes according to the M n value and the phase shift angle value calculated in the second step and the third step, and the specific implementation method comprises the following steps:
When M n is smaller than 1, DAB works in three working modes of mode 1, mode 1.5 or mode 2: calculating the phase shift angle of three working modes and the critical phase shift angle of mode switching, wherein
Y cos_min is an input current given value of the DAB converter connected with the on node, L r is an inductance value of the series inductor, T s is a switching period, I ZVS1 is a minimum current amplitude of the DAB converter primary side full-bridge switching tube for realizing soft switching, and I ZVS2 is a minimum current amplitude of the DAB converter secondary side full-bridge switching tube for realizing soft switching; The phase shift angle corresponding to the DAB converter in mode 1 is used; /(I) The phase shift angle is corresponding to the phase shift angle of the DAB converter under the mode 1.5; /(I)The phase shift angle corresponding to the DAB converter in mode 2 is used; /(I)When M n is smaller than 1, determining that the DAB converter is particularly operated in a critical phase shift angle of a mode 1 or a mode 1.5; /(I)When M n is smaller than 1, determining that the DAB converter is particularly operated in a critical phase shift angle of a mode 1.5 or a mode 2; under the condition that M n is smaller than 1, further judging that the DAB converter works in a specific working mode in the three working modes according to the phase shift angle:
When (when) When the DAB converter works in the mode 1, the corresponding duty ratio and phase shift angle of the DAB converter in the mode 1 are calculated and obtained
Wherein,The phase shift angle of the DAB converter connected with the on node is D 1n which is the duty ratio of the primary side full bridge of the DAB converter connected with the on node, and D 2n which is the duty ratio of the secondary side full bridge of the DAB converter connected with the on node;
When (when) When the DAB converter works in the mode 2, the corresponding duty ratio and phase shift angle of the DAB converter in the mode 2 are calculated and obtained
When (when)When the DAB converter is in the mode 1.5, the corresponding duty ratio and phase shift angle of the DAB converter in the mode 1.5 are calculated and obtained
At this time ifIt is explained that the DAB converter is operating in mode 1.5; if/>Judging that the DAB converter works in a mode 2, and obtaining the duty ratio and the phase shift angle according to an expression in the mode 2;
When M n is larger than 1, determining that DAB works in four working modes of mode 3 or mode 3c or mode 3.5 or mode 4: calculating the phase shift angle of four working modes, and the critical phase shift angle and critical input voltage of mode switching, wherein
The phase shift angle corresponding to the DAB converter working under the condition of the mode 3 is obtained; /(I)The corresponding phase shift angle of the DAB converter under the condition of the mode 3c is obtained; /(I)The phase shift angle is corresponding to the DAB converter working under the condition of the mode 3.5; /(I)The phase shift angle of the DAB converter under the condition of mode 4 is corresponding; /(I)In order to determine that the DAB converter is particularly operated in the critical phase shift angle of mode 3 or mode 3.5 when M p is greater than 1,/>When M p is larger than 1, determining that the DAB converter is particularly operated in a critical phase shift angle of a mode 3.5 or a mode 4; v in_th is the critical phase shift angle for determining whether the DAB converter is operating in mode 3 c;
Under the condition that M n is larger than 1, further judging that the DAB converter works in a specific working mode in the four working modes according to the phase shift angle and the input voltage:
When (when) When the DAB converter is judged to work in a mode 3 or a mode 3c, and the DAB converter is further judged to work in one specific working mode of the two working modes according to the magnitude of the input voltage:
When v in_n≤Vin_th is reached, the DAB converter is judged to work in the mode 3c, and the corresponding duty ratio and phase shift angle of the DAB converter in the mode 3c are calculated
When v in_n>Vin_th is reached, the DAB converter is judged to work in the mode 3, and the corresponding duty ratio and phase shift angle of the DAB converter in the mode 3 are calculated
When (when)When the DAB converter works in the mode 4, the corresponding duty ratio and phase shift angle of the DAB converter in the mode 4 are calculated and obtained
When (when)When the DAB converter is in the mode 3.5, the corresponding duty ratio and phase shift angle of the DAB converter in the mode 3.5 are calculated
At this time ifIt is explained that the DAB converter is operating in mode 3.5; if/>Judging that the DAB converter works in a mode 4, and obtaining the duty ratio and the phase shift angle according to an expression in the mode 4;
Under the condition that M n is equal to 1, the corresponding duty ratio and phase shift angle of the DAB converter are obtained by direct calculation
Obtained in the above modesWhen power flows forward/>Greater than 0; when power flows in reverse/>Less than 0.
6. A control method according to claim 2 or 3, characterized in that: step three, determining a driving signal of a bidirectional switch in the SWISS converter according to a sector where a three-phase grid voltage synthesis vector is located; the third step of generating the driving signals of the bidirectional switches in the SWISS converter is aimed at three groups of bidirectional switches, wherein the driving signals comprise six switching tubes, and the six switching tubes are divided into three groups, namely S va,Svb,Svc, and the driving signals of the six switching tubes are all power frequency square wave signals; each group of switching tubes consists of emitters of two switching tubes which are in anti-series connection, and driving signals of the two switching tubes in each group are consistent; for the topological structure of the SWISS converter in the SWISS type converter based on DAB for realizing bidirectional power flow, the three-phase voltages at the network side abc correspond to three bridge arms respectively, Q 1、Q3、Q5 forms an upper bridge arm, and Q 2、Q4、Q6 forms a lower bridge arm; the a-phase bridge arm is formed by connecting an emitter electrode of Q 1 and a collector electrode of Q 2; the b-phase bridge arm is formed by connecting an emitter electrode of Q 3 and a collector electrode of Q 4; the c-phase bridge arm is formed by connecting an emitter electrode of Q 5 and a collector electrode of Q 6; the collector electrodes of the switching tubes Q 1、Q3、Q5 are connected together to serve as the positive electrode of the input end of the DAB converter connected with the po node, and the positive electrode is defined as a node p; the emitter of the switch tube Q 2、Q4、Q6 is connected together to be used as the negative electrode of the input end of the DAB converter connected with the on node, and the node is defined as a node n; the three groups of bidirectional switches are connected in parallel and respectively used as the negative electrode of the input end of the DAB converter connected with the po node and the positive electrode of the input end of the DAB converter connected with the on node, and the node is defined as a node o; the driving signal is still determined according to the sector where the three-phase grid voltage synthesis vector is located; the driving signals for generating the bidirectional switches in the SWISS converter are aimed at the three groups of bidirectional switches and six switching tubes on the bridge arm; in each sector, a corresponding upper bridge arm switching tube with the phase voltage value at the maximum value is conducted; a corresponding lower bridge arm switch tube with the phase voltage value at the minimum value is conducted; a corresponding bidirectional switch with the phase voltage value at the middle position is conducted; the switching frequency of the switching tube on the bridge arm is power frequency, and the switching frequency of the bidirectional switch is double power frequency;
For the topological structure of the SWISS rectifier in the SWISS rectifier based on DAB, the network side abc three-phase voltages respectively correspond to three bridge arms, D 1、D3、D5 forms an upper bridge arm, and D 2、D4、D6 forms a lower bridge arm; the a-phase bridge arm is formed by connecting an anode of D 1 and a cathode of D 2; the b-phase bridge arm is formed by connecting an anode of D 3 and a cathode of D 4; the c-phase bridge arm is formed by connecting an anode of D 5 and a cathode of D 6; the cathodes of the diodes D 1、D3、D5 are connected together to serve as the positive electrode of the input end of the DAB converter connected with the po node, and the positive electrode is defined as a node p; the anodes of the diodes D 2、D4、D6 are connected together to serve as the negative electrode of the input end of the DAB converter connected with the on node, and the node is defined as a node n; the three groups of bidirectional switches are connected in parallel and respectively used as the negative electrode of the input end of the DAB converter connected with the po node and the positive electrode of the input end of the DAB converter connected with the on node, and the node is defined as a node o; and a corresponding bidirectional switch with the phase voltage value at the middle position in each sector is conducted, and the switching frequency of each group of bidirectional switches is twice the power frequency.
7. A control method according to claim 2 or 3, characterized in that: step five, respectively generating driving signals corresponding to two full-bridge switching tubes corresponding to the two DAB converters according to the phase shift angles and the duty ratios corresponding to the DAB converters connected with the po node and the on node obtained in the step four, wherein the driving signals are used for driving 16 switching tubes to work; the driving signals for generating the switching tubes are aimed at two DAB converters, wherein the driving signals comprise 16 switching tubes, namely Q p1,Qp2,Qp3,Qp4,Qp5,Qp6,Qp7,Qp8 and Q n1,Qn2,Qn3,Qn4,Qn5,Qn6,Qn7,Qn8 respectively; the driving signals of the switching tubes of the 16 switching tubes are 50% square wave signals, Q p1 is complementary to Q p2, Q p3 is complementary to Q p4, Q p5 is complementary to Q p6, and Q p7 is complementary to Q p8; q n1 is complementary to Q n2, Q n3 and Q n4, Q n5 is complementary to Q n6, and Q n7 is complementary to Q n8; the time that Q p3 advanced Q p1 is controlled by D 1p, and the time that Q p7 advanced Q p5 is controlled by D 2p; the time that Q n3 advanced Q n1 is controlled by D 1n, and the time that Q n7 advanced Q n5 is controlled by D 2n; the phase difference between the neutral lines of the two full-bridge secondary side voltage square waves of the DAB converter connected with the po node isThe phase difference between the neutral lines of two full-bridge secondary side voltage square waves of the DAB converter connected with the on node is/>And define/>
For the topological structure of the DAB converter connected with the po node, the primary side full bridge of the DAB converter comprises 4 switching tubes Q p1-Qp4; the switching tube Q p1 and the switching tube Q p2 form a bridge arm, and the source electrode of the Q p1 is connected with the drain electrode of the Q p2; the switching tube Q p3 and the switching tube Q p4 form a bridge arm, and the source electrode of the Q p3 is connected with the drain electrode of the Q p4; the drain of the switch tube Q p1 is connected with the drain of the switch tube Q p3 together and is connected with the collector of the Q 1、Q3、Q5, and the drain is connected with the cathode of the D 1、D3、D5 under the SWISS rectifier topology; the sources of the switching tube Q p2 and the switching tube Q p4 are connected together and connected with a node o; the source electrode of the switching tube Q p1 is connected with one end of a series inductor, and the other end of the inductor is connected with the same-name end of the primary side transformer winding; the synonym end of the primary side winding of the transformer is connected with the source electrode of Q p3; the driving signals of the switching tubes Q p1 and Q p2 are respectively driving signals with the duty ratio of 0.5, and the driving signals are complementary and have dead time; the driving signals of the switching tubes Q p3 and Q p4 are respectively driving signals with the duty ratio of 0.5, and the driving signals are complementary and have dead time; the time when the driving signals of the switching transistor Q p1 and the switching transistor Q p4 overlap divided by half of the switching period is defined as a duty ratio D 1p;
The secondary side full bridge of the DAB converter connected with the po node comprises 4 switching tubes Q p5-Qp8; the switching tube Q p5 and the switching tube Q p6 form a bridge arm, and the source electrode of the Q p5 is connected with the drain electrode of the Q p6; the switching tube Q p7 and the switching tube Q p8 form a bridge arm, and the source electrode of the Q p7 is connected with the drain electrode of the Q p8; the drains of the switching tubes Q p5 and Q p7 are connected together and connected with the positive electrode of the output capacitor to serve as the positive electrode of the output voltage; the sources of the switching tube Q p6 and the switching tube Q p8 are connected together and connected with the negative electrode of the output capacitor to serve as the negative electrode of the output voltage; the same-name end of the secondary side of the transformer is connected with the source electrode of the switching tube Q p5, and the different-name end of the secondary side winding of the transformer is connected with the source electrode of the switching tube Q p7; the driving signals of the switching tubes Q p5 and Q p6 are respectively driving signals with the duty ratio of 0.5, and the driving signals are complementary and have dead time; the driving signals of the switching tubes Q p7 and Q p8 are respectively driving signals with the duty ratio of 0.5, and the driving signals are complementary and have dead time; the time that the drive signals of the switch Q p5 and the switching transistor Q p8 overlap divided by half the switching period is defined as the duty ratio D 2p;
for the topological structure of the DAB converter connected with the on node, the primary side full bridge of the DAB converter comprises 4 switching tubes Q n1-Qn4; the switching tube Q n1 and the switching tube Q n2 form a bridge arm, and the source electrode of the Q n1 is connected with the drain electrode of the Q n2; the switching tube Q n3 and the switching tube Q n4 form a bridge arm, and the source electrode of the Q n3 is connected with the drain electrode of the Q n4; the drain electrode of the switch tube Q n1 is connected with the drain electrode of the switch tube Q n3 and is connected with a node o; the sources of the switch tube Q n2 and the switch tube Q n4 are connected together and connected with the emitter of the Q 2、Q4、Q6, and the anode of the switch tube Q n2 is connected with the anode of the D 2、D4、D6 under the SWISS rectifier topology; the source electrode of the switching tube Q n1 is connected with one end of a series inductor, and the other end of the inductor is connected with the same-name end of the primary side transformer winding; the synonym end of the primary side winding of the transformer is connected with the source electrode of Q n3; the driving signals of the switching tubes Q n1 and Q n2 are respectively driving signals with the duty ratio of 0.5, and the driving signals are complementary and have dead time; the driving signals of the switching tubes Q n3 and Q n4 are respectively driving signals with the duty ratio of 0.5, and the driving signals are complementary and have dead time; the time when the driving signals of the switching transistor Q n1 and the switching transistor Q n4 overlap divided by half of the switching period is defined as a duty ratio D 1n;
the secondary side full bridge of the DAB converter connected with the on node comprises 4 switching tubes Q n5-Qn8; the switching tube Q n5 and the switching tube Q n6 form a bridge arm, and the source electrode of the Q n5 is connected with the drain electrode of the Q n6; the switching tube Q n7 and the switching tube Q n8 form a bridge arm, and the source electrode of the Q n7 is connected with the drain electrode of the Q n8; the drains of the switching tubes Q n5 and Q n7 are connected together and connected with the positive electrode of the output capacitor to serve as the positive electrode of the output voltage; the sources of the switching tube Q n6 and the switching tube Q n8 are connected together and connected with the negative electrode of the output capacitor to serve as the negative electrode of the output voltage; the same-name end of the secondary side of the transformer is connected with the source electrode of the switching tube Q n5, and the different-name end of the secondary side winding of the transformer is connected with the source electrode of the switching tube Q n7; the driving signals of the switching tubes Q n5 and Q n6 are respectively driving signals with the duty ratio of 0.5, and the driving signals are complementary and have dead time; the driving signals of the switching tubes Q n7 and Q n8 are respectively driving signals with the duty ratio of 0.5, and the driving signals are complementary and have dead time; the time that the drive signals of the switch Q n5 and the switching transistor Q n8 overlap divided by half the switching period is defined as the duty ratio D 2n;
The method comprises the steps of obtaining phase shift angles and duty ratios corresponding to DAB converters connected by a po node and an on node according to a step four, respectively generating driving signals corresponding to two full-bridge switching tubes corresponding to the two DAB converters, wherein the driving signals are used for driving 16 switching tubes Q p1,Qp2,Qp3,Qp4,Qp5,Qp6,Qp7,Qp8 and Q n1,Qn2,Qn3,Qn4,Qn5,Qn6,Qn7,Qn8 to work, realizing power factor correction and output voltage control of the SWISS type converter based on DAB, optimizing the conduction loss and the modal control of a zero-voltage soft switch, and guaranteeing the soft switch realization of the two switching tubes of the two DAB converters 16 and the optimization of the peak current of a transformer.
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