Symmetrical bidirectional wireless power transfer three-phase circuit based on direct ac-ac conversion

Abstract

The application discloses a symmetrical bidirectional wireless power transmission three-phase circuit based on direct AC-AC conversion, comprising input / output terminals UVW, three-phase / single-phase AC-AC modules, wireless power transmission modules, single-phase / three-phase AC-AC modules and input / output terminals ABC which are connected in sequence, wherein the system circuit has the bidirectional energy transmission capability of wireless power transmission. The bidirectional three-phase voltage conversion and frequency conversion of wireless power transmission are completed, direct AC-AC conversion is adopted to effectively improve the system, and the system efficiency is further improved by adopting the soft switching technology, so that the circuit is novel and practical. The symmetrical bidirectional wireless power transmission three-phase circuit based on direct AC-AC conversion can be widely applied to three-phase alternating current applications in the transportation industry and various industrial and mining enterprises.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of wireless power transmission and power electronics, in particular to a symmetrical bidirectional wireless power transmission three-phase circuit based on direct AC-AC conversion, which realizes energy transmission and input / output isolation by wireless power transmission and realizes three-phase voltage and frequency conversion output by direct AC-AC. BACKGROUND

[0002] Wireless power transmission frequency converters can be widely used in rail transportation, electric vehicles, mining industry, smart home and other fields. AC-AC direct conversion can save rectification links, reduce losses and costs, such as wireless power transmission frequency converters, which can improve system efficiency and increase the competitiveness of wireless power transmission technology.

[0003] Some people have studied the efficiency optimization of bidirectional wireless power transmission system, mainly studied how to optimize the control strategy of the operating state and overall efficiency of the bidirectional wireless power transmission system through the coordinated combination of the three control freedoms in the system, and the two ends of the wireless power transmission system are DC. Liu Fang, Chen Kainan, Jiang Ye, Zhao Zhengming, "Efficiency optimization control strategy of bidirectional wireless power transmission system", 2019, 34(05):891-901.

[0004] At present, the symmetrical bidirectional wireless power transmission three-phase circuit based on direct AC-AC conversion has not been reported. SUMMARY

[0005] The purpose of the present application is to provide a symmetrical bidirectional wireless power transmission three-phase circuit based on direct AC-AC conversion, which is based on bidirectional direct AC-AC converter, and the front and rear stages of the wireless power transmission module are free of traditional DC links, which can improve system efficiency and reduce costs.

[0006] The purpose of the present application is achieved as follows:

[0007] The symmetrical bidirectional wireless power transmission three-phase circuit based on direct AC-AC conversion, characterized by: comprising: input / output terminals UVW, three-phase / single-phase AC-AC module, wireless power transmission module, single-phase / three-phase AC-AC module, input / output terminals ABC connected in turn, the system circuit of the present application has bidirectional energy transmission capability of wireless power transmission.

[0008] The three-phase / single-phase AC-AC module works in three-phase / single-phase direct AC-AC conversion mode when energy is transmitted from UVW to ABC, acts as an excitation source for wireless power transmission and can adjust the output size; when energy is transmitted from ABC to UVW, it works in single-phase / three-phase direct AC-AC conversion mode, and realizes three-phase voltage and frequency conversion output.

[0009] Wireless power transmission module, bidirectional wireless power transmission is carried out;

[0010] Single-phase / three-phase AC-AC module, when energy is transmitted from UVW to ABC, it works in single-phase / three-phase direct AC-AC conversion mode to realize three-phase voltage and frequency conversion output; when energy is transmitted from ABC to UVW, it works in single-phase / three-phase direct AC-AC conversion mode to serve as an excitation source for wireless power transmission and adjust the output size;

[0011] The three-phase / single-phase AC-AC module adopts a three-phase full-bridge circuit topology constructed by bidirectional switches Q1-Q6, Q1 and Q4, Q3 and Q6, and Q5 and Q2 form three bridge arms respectively, the midpoint of Q1 and Q4 is U1, the midpoint of Q3 and Q6 is V1, and the midpoint of Q5 and Q2 is W1, U1 is connected to the U phase through inductor L1, V1 is connected to the V phase through inductor L2, and W1 is connected to the W phase through inductor L3, and UVW is the input / output terminal of the single-phase / three-phase AC-AC module; the common intersection of Q1, Q3, and Q5 is D, the common intersection of Q2, Q4, and Q6 is E, and DE is the connection terminal of the three-phase / single-phase AC-AC module and the wireless power transmission module; inductors L1, L2, and L3 are three-phase integrated inductors of the same magnetic core.

[0012] The single-phase / three-phase AC-AC module adopts a three-phase full-bridge circuit topology constructed by bidirectional switches S1-S6, S1 and S4, S3 and S6, and S5 and S2 form three bridge arms respectively, the midpoint of S1 and S4 is A1, the midpoint of S3 and S6 is B1, and the midpoint of S5 and S2 is C1, A1 is connected to the A phase through inductor L4, B1 is connected to the B phase through inductor L5, and C1 is connected to the C phase through inductor L6, and ABC is the input / output terminal of the single-phase / three-phase AC-AC module; the common intersection of S1, S3, and S5 is F, the common intersection of S2, S4, and S6 is G, and FG is the connection terminal of the single-phase / three-phase AC-AC module and the wireless power transmission module; inductors L4, L5, and L6 are three-phase integrated inductors of the same magnetic core.

[0013] According to actual needs, capacitors or combinations of capacitors and inductors can be added to ABC and UVW terminals to form LC filters, LCL filters, or other types of filters together with the original inductors, and the filter circuit topology is selected according to actual needs and is not limited to a specific topology type.

[0014] According to actual needs, the circuit topology of the wireless power transmission module can adopt various topologies including series-series, series-parallel, parallel-parallel, parallel-series, and multi-coil topologies, and is not limited to a specific topology type.

[0015] The present application is symmetrical with ABC and UVW, symmetrical with three-phase / single-phase AC-AC module and single-phase / three-phase AC-AC module, and self-symmetrical with wireless power transmission module: namely u R1 is symmetrical with u R .

[0016] The system circuit of the present application has two basic working conditions: forward energy transmission working condition and reverse energy transmission working condition. When energy is transmitted from UVW to ABC, the energy flow direction is: UVW→three-phase / single-phase AC-AC module→wireless power transmission module u R1 →wireless power transmission module u R →single-phase / three-phase AC-AC module→ABC; when energy is transmitted from ABC to UVW, the energy flow direction is: ABC→single-phase / three-phase AC-AC module→wireless power transmission module u R →wireless power transmission module u R1 →three-phase / single-phase AC-AC module→UVW; the forward energy transmission working condition is symmetrical with the reverse energy transmission working condition.

[0017] When energy is transmitted from UVW to ABC, UVW is an input three-phase power source and is connected to the three-phase / single-phase AC-AC module. The output side of the three-phase / single-phase AC-AC module is connected to the input side of the wireless power transmission module. The output side of the wireless power transmission module is connected to the input side of the single-phase / three-phase AC-AC module. The output ABC of the single-phase / three-phase AC-AC module is the output of the entire system of the present application, which outputs variable-voltage and variable-frequency three-phase alternating current.

[0018] When energy is transmitted from ABC to UVW, ABC is an input three-phase power source and is connected to the single-phase / three-phase AC-AC module. The output side of the single-phase / three-phase AC-AC module is connected to the input side of the wireless power transmission module. The output side of the wireless power transmission module is connected to the input side of the three-phase / single-phase AC-AC module. The output UVW of the three-phase / single-phase AC-AC module is the output of the entire system of the present application, which outputs variable-voltage and variable-frequency three-phase alternating current.

[0019] The three-phase / single-phase AC-AC module and the single-phase / three-phase AC-AC module both have two working conditions. When energy is transmitted from UVW to ABC, the three-phase / single-phase AC-AC module realizes three-phase / single-phase direct AC-AC conversion with step-up, and the single-phase / three-phase AC-AC module realizes single-phase / three-phase direct AC-AC conversion with step-down. When energy is transmitted from ABC to UVW, the single-phase / three-phase AC-AC module realizes three-phase / single-phase direct AC-AC conversion with step-up, and the three-phase / single-phase AC-AC module realizes single-phase / three-phase direct AC-AC conversion with step-down.

[0020] Since the present application is directed to three-phase circuit, the waveform fitting control of the three-phase / single-phase AC-AC module and the single-phase / three-phase AC-AC module both adopt line voltage fitting control mode, and the waveform fitting is different from the traditional PWM / PFM control mode.

[0021] During forward energy transmission, the control mode of the three-phase / single-phase AC-AC module is: selecting the highest line voltage at the moment to connect u R1 High-frequency sine waveform fitting is performed to reduce working current and improve system efficiency; high-frequency sine waveform fitting is realized by controlling bidirectional switches Q1-Q6, and variable frequency output is realized by controlling cycle time.

[0022] During forward energy transmission, the single-phase / three-phase AC-AC module adopts single-phase high-frequency sine wave fitting three-phase low-frequency sine wave, and adopts zero-crossing interception to realize waveform interception and soft switching, i.e. taking high-frequency sine half wave as a basic interception unit, and since the sine half wave has zero-crossing point, soft switching will be naturally realized when taking high-frequency sine half wave as a basic interception unit. The interception basis of the waveform is area equivalence principle, i.e. in the corresponding segmented interval, the intercepted number of u R The area corresponding to the sine half wave is the same as the corresponding u A The area of the sine wave is the same. In actual control, the interception mode in the last sine half wave interval is reasonably intercepted according to the area equivalence principle, and it is not required to work in soft switching. The advantage of this scheme is that it can realize soft switching while realizing error-free fitting. Sine waveform fitting is realized by controlling bidirectional switches S1-S6, and variable frequency output is realized by controlling cycle time.

[0023] During reverse energy transmission, the three-phase / single-phase AC-AC module adopts high-frequency alternating current sine wave fitting low-frequency alternating current sine wave by using symmetry, and adopts zero-crossing interception to realize waveform interception and soft switching, i.e. taking high-frequency sine half wave as a basic interception unit, and since the sine half wave has zero-crossing point, soft switching will be naturally realized when taking high-frequency sine half wave as a basic interception unit. The interception basis of the waveform fitting is area equivalence principle but not traditional PWM control mode, i.e. in the corresponding segmented interval, the intercepted number of u R1 The area corresponding to the sine half wave is the same as the corresponding u U The area of the sine wave is the same. In actual control, the interception mode in the last sine half wave interval is reasonably intercepted according to the area equivalence principle, and it is not required to work in soft switching. The advantage of this scheme is that it can realize soft switching while realizing error-free fitting. High-frequency sine waveform fitting is realized by controlling bidirectional switches Q1-Q6, and variable frequency output is realized by controlling cycle time.

[0024] In the reverse energy transmission, the single-phase / three-phase AC-AC module control mode is the mode of intercepting the highest line voltage to carry out high-frequency sine waveform fitting, which is beneficial to reduce the current and improve the system efficiency. The three-phase / single-phase AC-AC module sine waveform fitting is realized by controlling the bidirectional switches S1-S6, and the variable frequency output is realized by controlling the cycle time.

[0025] The beneficial effects of the present application are that the bidirectional three-phase variable voltage and frequency of wireless power transmission is completed, the system can be effectively improved by adopting direct AC-AC conversion, and the system efficiency is further improved by adopting soft switching technology, and the circuit is novel and practical.

[0026] The characteristics of the present application are:

[0027] 1. The bidirectional topology of the present application is based on bidirectional direct AC-AC converter, and the front and rear stages of the wireless power transmission module are omitted to improve the system efficiency.

[0028] 2. The system circuit of the present application is a bidirectional three-phase symmetrical topology, which can simplify the control and design: the input ABC and the output UVW are symmetrical, the front and rear stages of the wireless power transmission module can be interchanged, the three-phase / single-phase AC-AC module and the single-phase / three-phase AC-AC module are symmetrical, and the wireless power transmission module is self-symmetrical.

[0029] 3. The two basic working conditions of the system circuit of the present application are symmetrical: the forward energy transmission working condition and the reverse energy transmission working condition, and the forward energy transmission working condition and the reverse energy transmission working condition are symmetrical.

[0030] 4. The single-phase / three-phase AC-AC module and the three-phase / single-phase AC-AC module have different working conditions under different working modes.

[0031] 5. When the forward energy transmission, i.e. the energy is transmitted from UVW to ABC, the three-phase / single-phase AC-AC module realizes the step-up three-phase / single-phase direct AC-AC conversion, and the single-phase / three-phase AC-AC module realizes the step-down single-phase / three-phase direct AC-AC conversion; when the reverse energy transmission, i.e. the energy is transmitted from ABC to UVW, the single-phase / three-phase AC-AC module realizes the step-up three-phase / single-phase direct AC-AC conversion, and the three-phase / single-phase AC-AC module realizes the step-down single-phase / three-phase direct AC-AC conversion.

[0032] 6. The control mode of the present application, whether forward or reverse energy transmission, the waveform fitting control of the three-phase / single-phase AC-AC module and the single-phase / three-phase AC-AC module adopts line voltage fitting control mode, and the waveform fitting is different from the traditional PWM / PFM control mode.

[0033] 7. During positive energy transmission, the three-phase / single-phase AC-AC module adopts a dynamic maximum line voltage fitting control method. The control method is to use the highest line voltage to perform high-frequency sine wave fitting, which helps to reduce current and improve system efficiency.

[0034] This invention relates to a symmetrical bidirectional wireless power transfer three-phase circuit based on direct AC-AC conversion, which can be widely used in the transportation industry and various industrial and mining enterprises for three-phase AC applications. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the symmetrical bidirectional wireless power transfer three-phase circuit based on direct AC-AC conversion of the present invention.

[0036] Figure 2 This invention relates to a symmetrical bidirectional wireless power transfer three-phase circuit topology based on direct AC-AC conversion.

[0037] Figure 3 The circuit topology for a three-phase / single-phase AC-AC module;

[0038] Figure 4 For positive energy transfer and u R1 When ωt∈(0,π / 3), a schematic diagram of the switch states of the three-phase / single-phase AC-AC module is provided.

[0039] Figure 5 For positive energy transfer and u R1 When ωt∈(0,π / 3), the schematic diagram of the switch states of the three-phase / single-phase AC-AC module is shown.

[0040] Figure 6 For positive energy transfer and u R1 When ωt∈(π / 3,2π / 3), a schematic diagram of the switch states of the three-phase / single-phase AC-AC module is provided.

[0041] Figure 7 For positive energy transfer and u R1 When ωt∈(π / 3,2π / 3), the schematic diagram of the switch states of the three-phase / single-phase AC-AC module is shown.

[0042] Figure 8 For positive energy transfer and u R1 When ωt∈(2π / 3,π), a schematic diagram of the switch states of the three-phase / single-phase AC-AC module is provided.

[0043] Figure 9 For positive energy transfer and u R1 When ωt∈(2π / 3,π), the schematic diagram of the switch states of the three-phase / single-phase AC-AC module is shown.

[0044] Figure 10 for positive energy transfer and u R1 for positive energy transfer, ωt∈(π, 4π / 3) three-phase / single-phase AC-AC module each switch state diagram;

[0045] Figure 11 for positive energy transfer and u R1 for negative energy transfer, ωt∈(π, 4π / 3) three-phase / single-phase AC-AC module each switch state diagram;

[0046] Figure 12 for positive energy transfer and u R1 for positive energy transfer, ωt∈(4π / 3, 5π / 3) three-phase / single-phase AC-AC module each switch state diagram;

[0047] Figure 13 for positive energy transfer and u R1 for negative energy transfer, ωt∈(4π / 3, 5π / 3) three-phase / single-phase AC-AC module each switch state diagram;

[0048] Figure 14 for positive energy transfer and u R1 for positive energy transfer, ωt∈(5π / 3, 2π) three-phase / single-phase AC-AC module each switch state diagram;

[0049] Figure 15 for positive energy transfer and u R1 for negative energy transfer, ωt∈(5π / 3, 2π) three-phase / single-phase AC-AC module each switch state diagram;

[0050] Figure 16 circuit topology of single-phase / three-phase AC-AC module;

[0051] Figure 17 single-phase / three-phase AC-AC module waveform control diagram for positive energy transfer;

[0052] Figure 18 single-phase / three-phase AC-AC module each switch state diagram for positive energy transfer ωt∈(0, π / 3);

[0053] Figure 19 single-phase / three-phase AC-AC module each switch state diagram for positive energy transfer ωt∈(π / 3, 2π / 3);

[0054] Figure 20 single-phase / three-phase AC-AC module each switch state diagram for positive energy transfer ωt∈(2π / 3, π);

[0055] Figure 21The single-phase / three-phase AC-AC module each switch state diagram when forward energy transmission ωt∈(4π / 3, 5π / 3);

[0056] Figure 22 The single-phase / three-phase AC-AC module each switch state diagram when forward energy transmission ωt∈(4π / 3, 5π / 3);

[0057] Figure 23 The single-phase / three-phase AC-AC module each switch state diagram when forward energy transmission ωt∈(5π / 3, 2π);

[0058] Figure 24 The three-phase / single-phase AC-AC module adds LC filter circuit topology diagram;

[0059] Figure 25 The single-phase / three-phase AC-AC module adds LC filter circuit topology diagram;

[0060] Figure 26 The single-phase / three-phase AC-AC module and three-phase / single-phase AC-AC module both add inductance topology diagram;

[0061] Figure 27 It is UVW three-phase line voltage waveform;

[0062] Figure 28 It is ABC three-phase voltage waveform. DETAILED DESCRIPTION

[0063] The application will be further described in detail below in conjunction with embodiments and with reference to the drawings.

[0064] Figure 1 It is the symmetric bidirectional wireless power transmission three-phase circuit schematic diagram based on direct AC-AC conversion of the application.

[0065] The symmetric bidirectional wireless power transmission three-phase circuit based on direct AC-AC conversion of the application has bidirectional energy transmission capacity of wireless power transmission, comprising: input / output end UVW, three-phase / single-phase AC-AC module, wireless power transmission module, single-phase / three-phase AC-AC module and input / output end ABC connected in sequence.

[0066] The three-phase / single-phase AC-AC module works in three-phase / single-phase direct AC-AC conversion working condition when forward energy transmission, that is, energy is output from UVW to ABC, and can act as an excitation source of wireless power transmission and adjust the output size; when reverse energy transmission, that is, energy is output from ABC to UVW, it works in single-phase / three-phase direct AC-AC conversion working condition, and realizes three-phase voltage and frequency conversion output;

[0067] The wireless power transmission module performs bidirectional wireless power transmission;

[0068] The single-phase / three-phase AC-AC module works in a single-phase / three-phase direct AC-AC conversion mode when energy is transmitted from UVW to ABC, and realizes three-phase voltage and frequency conversion output; the single-phase / three-phase AC-AC module works in a single-phase / three-phase direct AC-AC conversion mode when energy is transmitted from ABC to UVW, and functions as an excitation source of wireless power transmission and can adjust the output size.

[0069] When energy is transmitted from UVW to ABC, UVW is an input three-phase power source and is connected with the three-phase / single-phase AC-AC module, the output side of the three-phase / single-phase AC-AC module is connected with the input side of the wireless power transmission module, the output side of the wireless power transmission module is connected with the input side of the single-phase / three-phase AC-AC module, and the output ABC of the single-phase / three-phase AC-AC module is the output of the whole system, which is a variable voltage and frequency three-phase alternating current.

[0070] When energy is transmitted from ABC to UVW, ABC is an input three-phase power source and is connected with the single-phase / three-phase AC-AC module, the output side of the single-phase / three-phase AC-AC module is connected with the input side of the wireless power transmission module, the output side of the wireless power transmission module is connected with the input side of the three-phase / single-phase AC-AC module, and the output UVW of the three-phase / single-phase AC-AC module is the output of the whole system, which is a variable voltage and frequency three-phase alternating current.

[0071] The system circuit of the application adopts a symmetrical structure, ABC is symmetrical with UVW, the three-phase / single-phase AC-AC module is symmetrical with the single-phase / three-phase AC-AC module, and the wireless power transmission module is self-symmetrical: that is, u R1 is symmetrical with v R1 .

[0072] The system circuit of the application has two basic working conditions: forward energy transmission working condition and reverse energy transmission working condition, and the forward energy transmission working condition is symmetrical with the reverse energy transmission working condition.

[0073] The three-phase / single-phase AC-AC module and the single-phase / three-phase AC-AC module both adopt a three-phase full-bridge circuit topology, according to actual needs, the circuit topology of the wireless power transmission module can adopt various topologies including series-series, series-parallel, parallel-parallel, parallel-series and multi-coil topology types, and is not limited to a specific topology type; the energy transmission direction and the working condition table of the three-phase / single-phase AC-AC module and the single-phase / three-phase AC-AC module are shown in Table 1.

[0074] Table 1 Energy transmission direction and module working condition

[0075]

[0076]

[0077] The three-phase / single-phase AC-AC module and the single-phase / three-phase AC-AC module both have two working conditions: when forward energy transmission, i.e. energy is output from UVW to ABC, the three-phase / single-phase AC-AC module realizes a step-up three-phase / single-phase direct AC-AC conversion, and the single-phase / three-phase AC-AC module realizes a step-down single-phase / three-phase direct AC-AC conversion; when reverse energy transmission, i.e. energy is output from ABC to UVW, the single-phase / three-phase AC-AC module realizes a step-up three-phase / single-phase direct AC-AC conversion, and the three-phase / single-phase AC-AC module realizes a step-down single-phase / three-phase direct AC-AC conversion.

[0078] The waveform fitting control of the three-phase / single-phase AC-AC module and the single-phase / three-phase AC-AC module both adopts a line voltage fitting control mode.

[0079] Figure 2 The three-phase / single-phase AC-AC module and the single-phase / three-phase AC-AC module both have two working conditions: when forward energy transmission, i.e. energy is output from UVW to ABC, the three-phase / single-phase AC-AC module realizes a step-up three-phase / single-phase direct AC-AC conversion, and the single-phase / three-phase AC-AC module realizes a step-down single-phase / three-phase direct AC-AC conversion; when reverse energy transmission, i.e. energy is output from ABC to UVW, the single-phase / three-phase AC-AC module realizes a step-up three-phase / single-phase direct AC-AC conversion, and the three-phase / single-phase AC-AC module realizes a step-down single-phase / three-phase direct AC-AC conversion.

[0080] The three-phase / single-phase AC-AC module and the single-phase / three-phase AC-AC module both adopt a full-bridge topology, and the wireless power transmission module is a series-series topology, and other topologies of different types can be used in actual applications.

[0081] Figure 3 The three-phase / single-phase AC-AC module and the single-phase / three-phase AC-AC module both have two working conditions: when forward energy transmission, i.e. energy is output from UVW to ABC, the three-phase / single-phase AC-AC module realizes a step-up three-phase / single-phase direct AC-AC conversion, and the single-phase / three-phase AC-AC module realizes a step-down single-phase / three-phase direct AC-AC conversion; when reverse energy transmission, i.e. energy is output from ABC to UVW, the single-phase / three-phase AC-AC module realizes a step-up three-phase / single-phase direct AC-AC conversion, and the three-phase / single-phase AC-AC module realizes a step-down single-phase / three-phase direct AC-AC conversion.

[0082] The three-phase / single-phase AC-AC module adopts a three-phase full-bridge circuit topology constructed by bidirectional switches Q1-Q6, Q1 and Q4, Q3 and Q6, Q5 and Q2 form three bridge arms respectively, the midpoint of Q1 and Q4 is U1, the midpoint of Q3 and Q6 is V1, and the midpoint of Q5 and Q2 is W1, U1 is connected with the U phase through inductor L1, V1 is connected with the V phase through inductor L2, and W1 is connected with the W phase through inductor L3, and UVW are the input / output terminals of the three-phase / single-phase AC-AC module; the common intersection point of Q1, Q3 and Q5 is D, the common intersection point of Q2, Q4 and Q6 is E, and DE are the connection terminals of the three-phase / single-phase AC-AC module and the wireless power transmission module; inductors L1, L2 and L3 are three-phase integrated inductors of the same magnetic core.

[0083] When forward energy transmission, i.e. energy is output from UVW to ABC, the three-phase / single-phase AC-AC module realizes a three-phase / single-phase direct AC-AC conversion; when reverse energy transmission, i.e. energy is output from ABC to UVW, the three-phase / single-phase AC-AC module realizes a single-phase / three-phase direct AC-AC conversion.

[0084] The three-phase / single-phase AC-AC module adopts dynamic maximum line voltage fitting control mode when the energy is transmitted forwardly. Table 2 is a UVW three-phase line voltage u UV VW WU Table, in which "1" represents the maximum positive value in the interval, and "-1" represents the maximum negative value in the interval.

[0085] Table 2 is a UVW three-phase line voltage u UV VW WU

[0086]

[0087]

[0088] The three-phase / single-phase AC-AC module in the forward energy transmission mode is low-frequency input and high-frequency output. The three-phase / single-phase AC-AC module adopts dynamic maximum line voltage fitting control mode, which is a mode of intercepting the highest line voltage for high-frequency sine waveform fitting, so as to reduce the current and improve the system efficiency. The high-frequency sine waveform fitting is realized by controlling the bidirectional switches Q1-Q6, and the variable frequency output is realized by changing the cycle time T. The switching states of the bidirectional switches Q1-Q6 are shown in Table 3, in which "0" represents off, "1" represents on, and "0 / 1" represents that the corresponding bidirectional switches in the same row may be on or off at the same time, and whether to be on or off depends on the sine wave fitting control algorithm.u UV UV WU "1" represents the maximum positive value in the corresponding interval of the corresponding line voltage.

[0089] Table 3 is the switching state of Q1-Q6 under the forward energy transmission mode

[0090]

[0091]

[0092] Figure 4 When the energy is transmitted forwardly and u R1 The switching state diagram of the three-phase / single-phase AC-AC module when ωt∈(0, π / 3) is shown in (a) and (b). Figure 4 (a) is the inductance energy storage mode, Figure 4 (b) is the inductance freewheeling mode.

[0093] Figure 4 (a) is u R1 When ωt∈(0, π / 3), the switching state of each switch is shown in (a) and (b). The bidirectional switches Q1 and Q3 are on, and L1 and L2 are charged and stored.​​​​​​​Figure 4 (b) is the inductive freewheeling condition.

[0094] wherein u UV is the input voltage, and u R1 is the output voltage.

[0095] The input and output voltage relationship of the three-phase / single-phase AC-AC module in the forward energy transmission is only taken as an example, and other conditions are similar and will not be described in detail.

[0096] Figure 5 When the forward energy transmission and u R1 is negative, the switch state diagram of the three-phase / single-phase AC-AC module when ωt∈(0, π / 3) is shown in the following table: Figure 5 (a) is the inductive energy storage condition, Figure 5 (b) is the inductive freewheeling condition.

[0097] Figure 5 (a) is u R1 is negative, the switch state when ωt∈(0, π / 3) is shown in the following table: the bidirectional switch Q2, Q6 is turned on, and L2 and L3 are charged and stored energy; Figure 5 (b) is the freewheeling condition: the bidirectional switch Q2, Q3 is turned on, and L2 and L3 are freewheeling.

[0098] Figure 6 When the forward energy transmission and u R1 is positive, the switch state diagram of the three-phase / single-phase AC-AC module when ωt∈(π / 3, 2π / 3) is shown in the following table: Figure 6 (a) is the inductive energy storage condition, Figure 6 (b) is the inductive freewheeling condition.

[0099] Figure 6 (a) is u R1 is positive, the switch state when ωt∈(π / 3, 2π / 3) is shown in the following table: the bidirectional switch Q4, Q6 is turned on, and L1 and L2 are charged and stored energy; Figure 6 (b) is the freewheeling condition: the bidirectional switch Q1, Q6 is turned on, and L1 and L2 are freewheeling.

[0100] Figure 7 When the forward energy transmission and u R1 is negative, the switch state diagram of the three-phase / single-phase AC-AC module when ωt∈(π / 3, 2π / 3) is shown in the following table: Figure 7 (a) is the inductive energy storage condition, Figure 7 (b) is the inductive freewheeling condition.

[0101] Figure 7 (a) is u R1For negative, ωt∈(π / 3, 2π / 3), each switch state: bidirectional switch Q2, Q4 is on, L1 and L3 charge energy storage; Figure 7 (b) is freewheeling condition: bidirectional switch Q4, Q5 is on, L1 and L3 freewheel.

[0102] Figure 8 For positive, ωt∈(2π / 3, π), each switch state: bidirectional switch Q2, Q6 is on, L2 and L3 charge energy storage; R1 For positive, ωt∈(2π / 3, π), each switch state: bidirectional switch Q2, Q6 is on, L2 and L3 charge energy storage; Figure 8 (a) is inductance energy storage condition, Figure 8 (b) is inductance freewheeling condition.

[0103] Figure 8 (a) is u R1 For positive, ωt∈(2π / 3, π), each switch state: bidirectional switch Q2, Q6 is on, L2 and L3 charge energy storage; Figure 8 (b) is freewheeling condition: bidirectional switch Q3, Q5 is on, L2 and L3 freewheel.

[0104] Figure 9 For positive, ωt∈(2π / 3, π), each switch state: bidirectional switch Q2, Q6 is on, L2 and L3 charge energy storage; R1 For negative, ωt∈(2π / 3, π), each switch state: bidirectional switch Q2, Q4 is on, L1 and L3 charge energy storage; Figure 9 (a) is inductance energy storage condition, Figure 9 (b) is inductance freewheeling condition.

[0105] Figure 9 (a) is u R1 For negative, ωt∈(2π / 3, π), each switch state: bidirectional switch Q2, Q4 is on, L1 and L3 charge energy storage; Figure 9 (b) is freewheeling condition: bidirectional switch Q4, Q5 is on, L1 and L3 freewheel.

[0106] Figure 10 For positive, ωt∈(π, 4π / 3), each switch state: bidirectional switch Q2, Q6 is on, L2 and L3 charge energy storage; R1 For positive, ωt∈(π, 4π / 3), each switch state: bidirectional switch Q2, Q6 is on, L2 and L3 charge energy storage; Figure 10 (a) is inductance energy storage condition, Figure 10 (b) is inductance freewheeling condition.

[0107] Figure 10 (a) is u R1 For positive, ωt∈(π, 4π / 3), each switch state: bidirectional switch Q2, Q6 is on, L2 and L3 charge energy storage; Figure 10 (b) is freewheeling condition: bidirectional switch Q2, Q3 is on, L2 and L3 freewheel.

[0108] Figure 11 For positive, ωt∈(π, 4π / 3), each switch state: bidirectional switch Q2, Q6 is on, L2 and L3 charge energy storage;R1 When ωt∈(π, 4π / 3), the switch state of each phase / single-phase AC-AC module is shown in the following table: Figure 11 (a) is the inductance energy storage condition, Figure 11 (b) is the inductance freewheeling condition.

[0109] Figure 11 (a) is u R1 When ωt∈(π, 4π / 3), the switch state of each phase / single-phase AC-AC module is shown in the following table: Figure 11 (b) is the freewheeling condition: bidirectional switches Q1, Q6 are turned on, and L1 and L2 are freewheeled.

[0110] Figure 12 When ωt∈(4π / 3, 5π / 3), the switch state of each phase / single-phase AC-AC module is shown in the following table: R1 When ωt∈(4π / 3, 5π / 3), the switch state of each phase / single-phase AC-AC module is shown in the following table: Figure 12 (a) is the inductance energy storage condition, Figure 12 (b) is the inductance freewheeling condition.

[0111] Figure 12 (a) is u R1 When ωt∈(4π / 3, 5π / 3), the switch state of each phase / single-phase AC-AC module is shown in the following table: Figure 12 (b) is the freewheeling condition: bidirectional switches Q4, Q5 are turned on, and L1 and L3 are freewheeled.

[0112] Figure 13 When ωt∈(4π / 3, 5π / 3), the switch state of each phase / single-phase AC-AC module is shown in the following table: R1 When ωt∈(4π / 3, 5π / 3), the switch state of each phase / single-phase AC-AC module is shown in the following table: Figure 13 (a) is the inductance energy storage condition, Figure 13 (b) is the inductance freewheeling condition.

[0113] Figure 13 (a) is u R1 When ωt∈(4π / 3, 5π / 3), the switch state of each phase / single-phase AC-AC module is shown in the following table: Figure 13 (b) is the freewheeling condition: bidirectional switches Q1, Q6 are turned on, and L1 and L2 are freewheeled.

[0114] Figure 14 When ωt∈(4π / 3, 5π / 3), the switch state of each phase / single-phase AC-AC module is shown in the following table: R1 When ωt∈(5π / 3, 2π), the switch state of each phase / single-phase AC-AC module is shown in the following table: Figure 14 (a) is the inductance energy storage condition, Figure 14 (b) is the inductance freewheeling condition.

[0115] Figure 14 (a) is u R1 is positive, and ωt∈(5π / 3, 2π), the switch state of each phase: bidirectional switch Q1, Q5 is turned on, L1 and L3 are charged and stored energy; Figure 14 (b) is a freewheeling condition: bidirectional switches Q4, Q5 are turned on, L1 and L3 are freewheeling.

[0116] Figure 15 is positive and u R1 is negative, and ωt∈(5π / 3, 2π), the switch state of each phase / single-phase AC-AC module: Figure 15 (a) is an inductive energy storage condition, Figure 15 (b) is an inductive freewheeling condition.

[0117] Figure 15 (a) is u R1 is negative, and ωt∈(5π / 3, 2π), the switch state of each phase: bidirectional switch Q2, Q6 is turned on, L2 and L3 are charged and stored energy; Figure 15 (b) is a freewheeling condition: bidirectional switches Q2, Q3 are turned on, L2 and L3 are freewheeling.

[0118] Figure 16 is the main circuit topology of the single-phase / three-phase AC-AC module.

[0119] The single-phase / three-phase AC-AC module adopts a three-phase full-bridge circuit topology constructed by bidirectional switches S1-S6, S1 and S4, S3 and S6, S5 and S2 form three bridge arms respectively, the midpoint of S1 and S4 is A1, the midpoint of S3 and S6 is B1, and the midpoint of S5 and S2 is C1, A1 is connected to phase A through inductor L4, B1 is connected to phase B through inductor L5, and C1 is connected to phase C through inductor L6, ABC is the input / output terminal of the single-phase / three-phase AC-AC module; the common intersection of S1, S3, and S5 is F, and the common intersection of S2, S4, and S6 is G, FG is the connection terminal of the single-phase / three-phase AC-AC module and the wireless power transmission module; inductors L4, L5, and L6 are three-phase integrated inductors of the same magnetic core or separate discrete inductors.

[0120] When the energy is transmitted from UVW to ABC, the single-phase / three-phase AC-AC module realizes single-phase / three-phase direct AC-AC conversion; when the energy is transmitted from ABC to UVW, the single-phase / three-phase AC-AC module realizes three-phase / single-phase direct AC-AC conversion.

[0121] The waveform fitting control of the single-phase / three-phase AC-AC module adopts line voltage fitting control instead of phase voltage fitting control. The single-phase / three-phase AC-AC module is high-frequency input and low-frequency output in the forward energy transmission mode. The switching states of the bidirectional switches S1-S6 are shown in Table 4, in which "0" represents off, "0 / 1" represents that the corresponding bidirectional switches in the same row can be turned on or off at the same time, and whether to be turned on or off depends on the sine wave fitting control algorithm. "+" represents that the corresponding interval is positive, and "-" represents that the corresponding interval is negative.

[0122] Table 4 Switching states of S1-S6 in the forward energy transmission mode

[0123] u R ]]> Figure 17 S1 S2 S3 S4 S5 S6 u AB ]]> u BC ]]> u CA <!-- 9 -->]]> + (0，π / 3) 0 / 1 0 0 0 0 / 1 0 / 1 + - + - (0，π / 3) 0 0 / 1 0 / 1 0 / 1 0 0 + - + + (π / 3，2π / 3) 0 / 1 0 / 1 0 0 0 0 / 1 + - - - (π / 3，2π / 3) 0 0 0 / 1 0 / 1 0 / 1 0 + - - + (2π / 3，π) 0 / 1 0 / 1 0 / 1 0 0 0 + + - - (2π / 3，π) 0 0 0 0 / 1 0 / 1 0 / 1 + + - + (π，4π / 3) 0 0 / 1 0 / 1 0 / 1 0 0 - + - - (π，4π / 3) 0 / 1 0 0 0 0 / 1 0 / 1 - + - + (4π / 3，5π / 3) 0 0 0 / 1 0 / 1 0 / 1 0 - + + - (4π / 3，5π / 3) 0 / 1 0 / 1 0 0 0 0 / 1 - + + + (5π / 3，2π) 0 0 0 0 / 1 0 / 1 0 / 1 - - + - (5π / 3，2π) 0 / 1 0 / 1 0 / 1 0 0 0 - - +

[0124] Figure 17 is the waveform control schematic diagram of the single-phase / three-phase AC-AC module in the forward energy transmission mode.

[0125] Due to the symmetry of three-phase alternating current, only u AB is taken as an example for illustration.

[0126] Figure 17 (a) is the schematic diagram of the high-frequency sine wave fitting low-frequency sine half wave of the single-phase / three-phase AC-AC module in the forward energy transmission mode. The area equivalent principle is adopted for waveform interception, that is, in the corresponding segmented interval, the intercepted number of u R sinusoidal half waves does not require to be an integer; AB the areas of the corresponding u R sinusoidal half waves are the same;

[0127] Figure 17 (b) is the variable-frequency output schematic diagram of the single-phase / three-phase AC-AC module in the forward energy transmission mode, Figure 18 (b) adopts different numbers of u R sinusoidal half waves to fit the waveform, which will obtain different u AB output frequencies, so as to realize variable-frequency output. The dotted line in the figure is used to represent that the appropriate waveform control is adopted for waveform interception in these u R sinusoidal half waves.

[0128] The control scheme of the single-phase / three-phase AC-AC module is to make the working current minimum to improve the system efficiency and simplify the control. Therefore, when the forward energy transmission, the control target of the three-phase / single-phase AC-AC module is to make the effective value U R1 of u R1 to be the maximum value so as to make the effective value U R of the input u R of the single-phase / three-phase AC-AC module to be the maximum value. Note: the corresponding hardware design also follows this control scheme for design.

[0129] In the positive energy transmission, the single-phase / three-phase AC-AC module adopts high-frequency AC sine wave fitting low-frequency AC sine wave, adopts zero-crossing interception to realize waveform interception and soft switching, that is, taking high-frequency sine half wave as a basic interception unit, and because of the zero-crossing point of the sine half wave, soft switching is naturally realized when taking high-frequency sine half wave as a basic interception unit. The interception basis of the waveform is the area equivalence principle, that is, in the corresponding section interval, the intercepted number of sine half waves is not required to be an integer, and the area of the intercepted sine half wave is equivalent to the area of the corresponding sine half wave in the section interval R The area of the sine half wave is equivalent to the area of the corresponding sine half wave in the section interval A The area of the sine half wave is equivalent to the area of the corresponding sine half wave in the section interval. In actual control, the interception mode in the last sine half wave interval is reasonably intercepted according to the area equivalence principle, and it is not required to work in soft switching. The advantage of this scheme is that soft switching can be realized most of the time while realizing error-free fitting. The sine wave fitting is realized by controlling the bidirectional switches S1-S6, and the variable frequency output is realized by controlling the cycle time.

[0130] In the positive energy transmission, the single-phase / three-phase AC-AC module adopts the segmented active rectification mode.

[0131] Figure 18 For the positive energy transmission ωt∈(0, π / 3), the single-phase / three-phase AC-AC module is shown in the following table: Figure 18 (a) is u R1 For the positive inductance energy storage condition, Figure 18 (b) is u R1 For the positive inductance freewheeling condition; Figure 18 (c) is u R1 For the negative inductance energy storage condition, and (d) is u R1 For the negative inductance freewheeling condition.

[0132] Figure 18 (a) is u R1 For the positive, ωt∈(0, π / 3), the inductance energy storage switch state: S2, S3, S4 are off, and S1, S5, S6 are on or off according to the sine wave fitting control algorithm. L4 (current direction A1→A), L5 (current direction B→B1), and L6 (current direction C1→C) are charged and stored; Figure 18 (b) is the freewheeling condition: S1-S6 are all off, and L4, L5, and L6 are freewheeling;

[0133] Figure 18 (c) is u R1 For the negative, ωt∈(0, π / 3), the inductance energy storage switch state: S1, S5, S6 are off, and S2, S3, S4 are on or off according to the sine wave fitting control algorithm. L4 (current direction A1→A), L5 (current direction B→B1), and L6 (current direction C1→C) are charged and stored;Figure 19 (d) is the inductive freewheeling condition: S1-S6 are all off, L4, L5, L6 freewheel.

[0134] Figure 19 (a) is the single-phase / three-phase AC-AC module switch state diagram when the forward energy transmission ωt∈(0, π / 3); Figure 19 (a) is the single-phase / three-phase AC-AC module switch state diagram when the forward energy transmission ωt∈(0, π / 3); R1 (b) is the inductive energy storage condition when the forward energy transmission ωt∈(0, π / 3); Figure 19 (b) is the inductive energy storage condition when the forward energy transmission ωt∈(0, π / 3); R1 (c) is the inductive freewheeling condition when the forward energy transmission ωt∈(0, π / 3); Figure 19 (c) is the inductive freewheeling condition when the forward energy transmission ωt∈(0, π / 3); R1 (d) is the inductive energy storage condition when the forward energy transmission ωt∈(0, π / 3); Figure 19 (d) is the inductive energy storage condition when the forward energy transmission ωt∈(0, π / 3); R1

[0135] Figure 19 (a) is the single-phase / three-phase AC-AC module switch state diagram when the forward energy transmission ωt∈(0, π / 3); R1 (b) is the inductive energy storage condition when the forward energy transmission ωt∈(0, π / 3); Figure 19 (b) is the inductive energy storage condition when the forward energy transmission ωt∈(0, π / 3);

[0136] Figure 19 (c) is the inductive freewheeling condition when the forward energy transmission ωt∈(0, π / 3); R1 (d) is the inductive freewheeling condition when the forward energy transmission ωt∈(0, π / 3); Figure 20 (d) is the inductive freewheeling condition when the forward energy transmission ωt∈(0, π / 3);

[0137] Figure 20 (a) is the single-phase / three-phase AC-AC module switch state diagram when the forward energy transmission ωt∈(0, π / 3); Figure 20 (a) is the single-phase / three-phase AC-AC module switch state diagram when the forward energy transmission ωt∈(0, π / 3); R1 (b) is the inductive energy storage condition when the forward energy transmission ωt∈(0, π / 3); Figure 20 (b) is the inductive energy storage condition when the forward energy transmission ωt∈(0, π / 3); R1 (c) is the inductive freewheeling condition when the forward energy transmission ωt∈(0, π / 3); Figure 20 (c) is the inductive freewheeling condition when the forward energy transmission ωt∈(0, π / 3); R1 (d) is the inductive energy storage condition when the forward energy transmission ωt∈(0, π / 3); Figure 20 (d) is the inductive energy storage condition when the forward energy transmission ωt∈(0, π / 3); R1

[0138] Figure 20 (a) is the single-phase / three-phase AC-AC module switch state diagram when the forward energy transmission ωt∈(0, π / 3); R1 ​​For positive, ωt∈(2π / 3, π), the inductance energy storage state of each switch: S4, S5, S6 are off, S1, S2, S3 are on or off according to the sine wave fitting control algorithm, L4 (current direction A1→A), L5 (current direction B1→B), L6 (current direction C→C1) charge energy storage; Figure 20 (b) is the freewheeling condition: S1-S6 are all off, L4, L5, L6 freewheeling;

[0139] Figure 20 (c) is the u R1 For negative, ωt∈(2π / 3, π), the inductance energy storage state of each switch: S1, S2, S3 are off, S4, S5, S6 are on or off according to the sine wave fitting control algorithm, L4 (current direction A1→A), L5 (current direction B1→B), L6 (current direction C→C1) charge energy storage; Figure 21 (d) is the inductance freewheeling condition: S1-S6 are all off, L4, L5, L6 freewheeling.

[0140] Figure 21 For positive energy transmission ωt∈(π, 4π / 3), the single-phase / three-phase AC-AC module each switch state diagram; Figure 21 (a) is the u R1 For positive, the inductance energy storage condition, Figure 21 (b) is the u R1 For positive, the inductance freewheeling condition; Figure 21 (c) is the u R1 For negative, the inductance energy storage condition, Figure 21 (d) is the u R1 For negative, the inductance freewheeling condition. ωt∈(π, 4π / 3), the single-phase / three-phase AC-AC module each switch state diagram;

[0141] Figure 21 (a) is the u R For positive, S1, S5, S6 are off, S2, S3, S4 are on or off according to the sine wave fitting control algorithm; L4 (current direction A→A1), L5 (current direction B1→B), L6 (current direction C→C1) charge energy storage; Figure 21 (b) is the u R1 For positive, the inductance freewheeling condition;

[0142] Figure 21 (c) is the u R1 For negative, S2, S3, S4 are off, S1, S5, S6 are on or off according to the sine wave fitting control algorithm, L4 (current direction A→A1), L5 (current direction B1→B), L6 (current direction C→C1) charge energy storage, Figure 22 (d) is the inductance freewheeling condition: S1-S6 are all off, L4, L5, L6 freewheeling.

[0143] Figure 22 For positive energy transmission ωt∈(4π / 3,5π / 3), single-phase / three-phase AC-AC module each switch state diagram; Figure 22 (a) for u R1 For positive inductance energy storage condition, Figure 22 (b) for u R1 For positive inductance freewheeling condition; Figure 22 (c) for u R1 For negative inductance energy storage condition, Figure 22 (d) for u R1 For negative inductance freewheeling condition.

[0144] Figure 22 (a) for u R For positive, S1, S2, S6 are off, S3, S4, S5 are on or not according to sinusoidal wave fitting control algorithm; L4(current direction A→A1), L5(current direction B1→B), L6(current direction C1→C) charge energy storage; Figure 22 (b) for u R1 For positive inductance freewheeling condition;

[0145] Figure 22 (c) for u R1 For negative, S3, S4, S5 are off, S1, S2, S6 are on or not according to sinusoidal wave fitting control algorithm, L4(current direction A→A1), L5(current direction B1→B), L6(current direction C1→C) charge energy storage, Figure 23 (d) for inductance freewheeling condition: S1-S6 are all off, L4, L5, L6 freewheel.

[0146] Figure 23 For positive energy transmission ωt∈(5π / 3,2π), single-phase / three-phase AC-AC module each switch state diagram; Figure 23 (a) for u R1 For positive inductance energy storage condition, Figure 23 (b) for u R1 For positive inductance freewheeling condition; Figure 23 (c) for u R1 For negative inductance energy storage condition, Figure 23 (d) for u R1 For negative inductance freewheeling condition. ωt∈(π,4π / 3), single-phase / three-phase AC-AC module each switch state diagram;

[0147] Figure 23 (a) for u RFor positive time, S1, S2, S3 are off, and whether S4, S5, S6 are on or not depends on the sine wave fitting control algorithm; L4 (current direction A→A1), L5 (current direction B→B1), L6 (current direction C1→C) charge energy storage; Figure 23 (b) for u R1 For positive time inductor freewheeling condition;

[0148] Figure 23 (c) for u R1 For negative, S4, S5, S6 are off, and whether S1, S2, S3 are on or not depends on the sine wave fitting control algorithm, L4 (current direction A→A1), L5 (current direction B→B1), L6 (current direction C1→C) charge energy storage, Figure 24 (d) for inductor freewheeling condition: S1-S6 are off, L4, L5, L6 freewheel.

[0149] The system circuit of the application has two basic working conditions: positive energy transmission working condition and reverse energy transmission working condition, the positive energy transmission working condition is that energy is transmitted from UVW to ABC, and the energy flow direction is: UVW→three-phase / single-phase AC-AC module→wireless power transmission module u R1 →wireless power transmission module u R →single-phase / three-phase AC-AC module→ABC; the reverse energy transmission working condition is that energy is transmitted from ABC to UVW, and the energy flow direction is: ABC→single-phase / three-phase AC-AC module→wireless power transmission module u R →wireless power transmission module u R1 →three-phase / single-phase AC-AC module→UVW; the positive energy transmission working condition and the reverse energy transmission working condition are symmetrical.

[0150] By utilizing the symmetry of ABC and UVW, the symmetry of three-phase / single-phase AC-AC module and single-phase / three-phase AC-AC module, the symmetry of u R1 and u R1 , the three-phase / single-phase AC-AC module working in the reverse energy transmission working condition is the same as the single-phase / three-phase AC-AC module working in the positive energy transmission working condition, and the single-phase / three-phase AC-AC module working in the reverse energy transmission working condition is the same as the three-phase / single-phase AC-AC module working in the positive energy transmission working condition. Related professionals can know, and no longer tedious.

[0151] Figure 25 The topology diagram of three-phase / single-phase AC-AC module with LC filter circuit;

[0152] According to actual needs, the three-phase / single-phase AC-AC module can be additionally provided with a filter circuit, such as an LC filter circuit, at the ABC end, and L1, L2 and L3 can be independent inductors or integrated inductors.

[0153] Figure 26 LC filter circuit topology for single-phase / three-phase AC-AC module;

[0154] According to actual needs, the single-phase / three-phase AC-AC module can be additionally provided with a filter circuit, such as an LC filter circuit, at the UVW end, and L4, L5 and L6 can be independent inductors or integrated inductors.

[0155] According to actual needs, LC filters, LCL filters or other types of filters can be additionally provided at the ABC and UVW ends, and the filter circuit topology is selected according to actual needs and is not limited to a specific topology type.

[0156] Figure 27 Symmetrical bidirectional wireless power transmission three-phase circuit based on direct AC-AC conversion, the circuit topology of which is provided with inductors at the ABC and UVW ends;

[0157] According to actual needs, inductors can be additionally provided at the ABC and UVW ends.

[0158] Wireless power transmission module, the series-series topology is shown in the figure, and any suitable topology can be used in actual use, and the specific selection is based on actual needs.

[0159] The power electronic bidirectional switch adopts a circuit structure formed by reverse connection of metal-oxide semiconductor field effect transistors (MOSFETs), that is, the source of the upper transistor is connected with the drain of the lower transistor, the drain of the upper transistor is connected with the source of the lower transistor as the main current port, and the gate-level driving control of the upper and lower transistors is separated. Taking Q1 as an example, when G1 applies a driving signal, the upper transistor Q 11 and the lower transistor Q12 are turned on, and the current can pass through Q 11 , D 12 from the top to the bottom or pass through Q 12 , D 11 from the bottom to the top. The control of other power electronic bidirectional switches is completely similar to S1, and is not described herein again.

[0160] The power electronic bidirectional switch in the application can not only be formed by reverse connection of metal-oxide semiconductor field effect transistors (MOSFETs), but also can be formed by reverse connection of two reverse blocking insulated gate bipolar transistors (RB-IGBTs) without anti-parallel diodes, and further can be formed by any power electronic device capable of completing an AC switching task.

[0161] Figure 27 is the UVW three-phase line voltage waveform.

[0162] For ease of viewing, the UVW end three-phase line voltage waveform, Figure 28 the waveform phase corresponds to Table 2.

[0163] Figure 28 is the ABC three-phase voltage waveform.

[0164] For ease of viewing, the ABC end three-phase voltage waveform, ​ the waveform phase corresponds to Table 3.

[0165] Finally, it should be noted that: the above examples are only to illustrate the technical solutions of the present application, rather than limit them; although the present application has been described in detail with reference to the foregoing examples, those of ordinary skill in the art should understand: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A symmetrical bidirectional wireless power transfer three-phase circuit based on direct AC-AC conversion, characterized in that: The wireless power transmission bidirectional energy transmission capability comprises: sequentially connected input / output end UVW three-phase / single-phase AC-AC module, wireless power transmission module, single-phase / three-phase AC-AC module, input / output end ABC; The three-phase / single-phase AC-AC module works in three-phase / single-phase direct AC-AC conversion working condition when energy is transmitted from UVW to ABC, acts as an excitation source of wireless power transmission and can adjust the output size; when energy is transmitted from ABC to UVW, the three-phase / single-phase AC-AC module works in single-phase / three-phase direct AC-AC conversion working condition, and three-phase voltage and frequency conversion output is realized; The wireless power transmission module performs bidirectional wireless power transmission; The single-phase / three-phase AC-AC module works in single-phase / three-phase direct AC-AC conversion working condition when energy is transmitted from UVW to ABC, and three-phase voltage and frequency conversion output is realized; when energy is transmitted from ABC to UVW, the single-phase / three-phase AC-AC module works in single-phase / three-phase direct AC-AC conversion working condition, acts as an excitation source of wireless power transmission and can adjust the output size; The ABC is symmetrical to the UVW, the three-phase / single-phase AC-AC module is symmetrical to the single-phase / three-phase AC-AC module, and the wireless power transmission module is self-symmetrical; The system circuit has two basic working conditions: forward energy transmission working condition and reverse energy transmission working condition. The forward energy transmission working condition is that energy is transmitted from UVW to ABC, and the energy flow direction is: UVW→three-phase / single-phase AC-AC module→wireless power transmission module u R1 →wireless power transmission module u R The reverse energy transmission working condition is that energy is transmitted from ABC to UVW, and the energy flow direction is: ABC→single-phase / three-phase AC-AC module→wireless power transmission module u R →wireless power transmission module u R1 →three-phase / single-phase AC-AC module→UVW; the forward energy transmission working condition and the reverse energy transmission working condition are symmetrical.

2. The symmetrical bidirectional wireless power transfer three-phase circuit based on direct AC-AC conversion of claim 1, wherein: The three-phase / single-phase AC-AC module and the single-phase / three-phase AC-AC module both have two working conditions: when energy is transmitted from UVW to ABC, the three-phase / single-phase AC-AC module realizes step-up three-phase / single-phase direct AC-AC conversion, and the single-phase / three-phase AC-AC module realizes step-down single-phase / three-phase direct AC-AC conversion; when energy is transmitted from ABC to UVW, the single-phase / three-phase AC-AC module realizes step-up three-phase / single-phase direct AC-AC conversion, and the three-phase / single-phase AC-AC module realizes step-down single-phase / three-phase direct AC-AC conversion.

3. The symmetrical bidirectional wireless power transfer three-phase circuit based on direct AC-AC conversion of claim 1, wherein: When energy is transmitted from UVW to ABC, UVW is an input three-phase power source and is connected to the three-phase / single-phase AC-AC module, the output side of the three-phase / single-phase AC-AC module is connected to the input side of the wireless power transmission module, the output side of the wireless power transmission module is connected to the input side of the single-phase / three-phase AC-AC module, and the output ABC of the single-phase / three-phase AC-AC module is the output of the entire system, which is variable-voltage and variable-frequency three-phase alternating current; When energy is transmitted from ABC to UVW, ABC is an input three-phase power source and is connected to the single-phase / three-phase AC-AC module, the output side of the single-phase / three-phase AC-AC module is connected to the input side of the wireless power transmission module, the output side of the wireless power transmission module is connected to the input side of the three-phase / single-phase AC-AC module, and the output UVW of the three-phase / single-phase AC-AC module is the output of the entire system, which is variable-voltage and variable-frequency three-phase alternating current.

4. The symmetrical bidirectional wireless power transfer three-phase circuit based on direct AC-AC conversion of claim 1, wherein: The three-phase / single-phase AC-AC module adopts a three-phase full-bridge circuit topology constructed by bidirectional switches Q1-Q6, Q1 and Q4, Q3 and Q6, and Q5 and Q2 form three bridge arms respectively, the midpoint of Q1 and Q4 is U1, the midpoint of Q3 and Q6 is V1, and the midpoint of Q5 and Q2 is W1, U1 is connected with U through inductor L1, V1 is connected with V through inductor L2, and W1 is connected with W through inductor L3, UVW is the input / output end of the single-phase / three-phase AC-AC module; the common intersection of Q1, Q3 and Q5 is D, the common intersection of Q2, Q4 and Q6 is E, and DE is the connection end of the three-phase / single-phase AC-AC module and the wireless power transmission module; inductors L1, L2 and L3 are three-phase integrated inductors of the same magnetic core; The single-phase / three-phase AC-AC module adopts a three-phase full-bridge circuit topology constructed by bidirectional switches S1-S6, S1 and S4, S3 and S6, and S5 and S2 form three bridge arms respectively, the midpoint of S1 and S4 is A1, the midpoint of S3 and S6 is B1, and the midpoint of S5 and S2 is C1, A1 is connected with A through inductor L4, B1 is connected with B through inductor L5, and C1 is connected with C through inductor L6, ABC is the input / output end of the single-phase / three-phase AC-AC module; the common intersection of S1, S3 and S5 is F, the common intersection of S2, S4 and S6 is G, and FG is the connection end of the single-phase / three-phase AC-AC module and the wireless power transmission module; inductors L4, L5 and L6 are three-phase integrated inductors of the same magnetic core; According to actual requirements, LC filters, LCL filters or other types of filters are installed on ABC and UVW ends; the circuit topology of the wireless power transmission module adopts various topologies including series-series, series-parallel, parallel-parallel, parallel-series and multi-coil topologies.

5. The symmetrical bidirectional wireless power transfer three-phase circuit based on direct AC-AC conversion of claim 1, wherein: During forward energy transmission, the control mode of the three-phase / single-phase AC-AC module is to fit a high-frequency sinusoidal waveform by intercepting the highest line voltage, which is beneficial to reduce current and improve system efficiency; the high-frequency sinusoidal waveform fitting is realized by controlling bidirectional switches Q1-Q6, and variable frequency output is realized by controlling cycle time; During the forward energy transmission, the single-phase / three-phase AC-AC module adopts high-frequency AC sine wave to fit low-frequency AC sine wave, adopts zero-crossing interception to perform waveform interception and realize soft switching, that is, taking high-frequency sine half wave as a basic interception unit, and because of the zero-crossing point of the sine half wave, soft switching will be naturally realized when taking high-frequency sine half wave as the basic interception unit; the basis for waveform interception is the area equivalence principle, that is, in the corresponding section interval, the intercepted sine half wave does not require to be a certain number of integers u R The area corresponding to the sine half wave is the same as the area of the corresponding u A sine wave in the section interval; during actual control, the interception mode in the last sine half wave section interval is performed according to the area equivalence principle to reasonably intercept the waveform and does not require to work in soft switching; the sine waveform fitting is realized by controlling bidirectional switches S1-S6, and the variable frequency output is realized by controlling the cycle time.

6. The symmetrical bidirectional wireless power transfer three-phase circuit based on direct AC-AC conversion of claim 1, wherein: By using symmetry, when the energy is transmitted reversely, the three-phase / single-phase AC-AC module adopts high-frequency AC sine wave to fit low-frequency AC sine wave, adopts zero-crossing interception to perform waveform interception and realize soft switching, that is, taking high-frequency sine half wave as a basic interception unit, because of the zero-crossing point of the sine half wave, soft switching will be realized naturally when taking high-frequency sine half wave as a basic interception unit; the basis for waveform interception is the area equivalence principle, that is, in the corresponding section interval, the intercepted sine half wave does not require to be an integer number of sine half waves u R1 The area corresponding to the sine half wave is the same as the area of the corresponding u U sine wave in the section interval; when actually controlling, the interception mode in the last sine half wave section interval is performed according to the area equivalence principle to reasonably intercept the waveform and does not require to work in soft switching; high-frequency sine waveform fitting is realized by controlling bidirectional switches Q1-Q6; variable frequency output is realized by controlling the cycle time; During reverse energy transmission, the control mode of the single-phase / three-phase AC-AC module is to fit a high-frequency sinusoidal waveform by intercepting the highest line voltage, which is beneficial to reduce current and improve system efficiency; the three-phase / single-phase AC-AC module sinusoidal waveform fitting is realized by controlling bidirectional switches S1-S6, and variable frequency output is realized by controlling cycle time.

7. The symmetrical bidirectional wireless power transfer three-phase circuit based on direct AC-AC conversion of claim 1, wherein, During forward energy transmission, the three-phase / single-phase AC-AC module is low-frequency input and high-frequency output, and the three-phase / single-phase AC-AC module adopts a dynamic maximum line voltage fitting control mode, that is, a high-frequency sinusoidal waveform is fitted by intercepting the highest line voltage; during forward energy transmission, the single-phase / three-phase AC-AC module is high-frequency input and low-frequency output.

8. The symmetrical bidirectional wireless power transfer three-phase circuit based on direct AC-AC conversion of claim 1, wherein: symmetry of ABC and UVW, symmetry of three-phase / single-phase AC-AC module and single-phase / three-phase AC-AC module, u R1 and u R1 symmetry, the three-phase / single-phase AC-AC module works in the reverse energy transmission condition and the single-phase / three-phase AC-AC module works in the forward energy transmission condition, and the single-phase / three-phase AC-AC module works in the reverse energy transmission condition and the three-phase / single-phase AC-AC module works in the forward energy transmission condition.

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