Bidirectional WPT AC-AC frequency conversion system based on variable topology bidirectional AC / AC

Abstract

The invention discloses a bidirectional WPT AC-AC frequency conversion system based on variable topology bidirectional AC / AC. The bidirectional WPT AC-AC frequency conversion system comprises a variable topology bidirectional AC / AC-1 unit, a wireless electric energy transmission unit and a variable topology bidirectional AC / AC-2 unit which are connected in sequence, the circuit has two energy transmission modes of forward energy transmission and reverse energy transmission. During forward energy transmission, the energy transmission path is from the AB side to the MN side of the variable topology bidirectional AC / AC-1 unit to the OP side of the wireless power transmission unit to the variable topology bidirectional AC / AC-2 unit to the GH side. And during reverse energy transmission, the energy transmission path is from the GH side to the OP side of the variable topology bidirectional AC / AC-2 unit to the MN side of the wireless power transmission unit to the variable topology bidirectional AC / AC-1 unit to the AB side. According to the circuit, efficient two-way wireless electric energy transmission is achieved, the wireless electric energy transmission front stage and the wireless electric energy transmission rear stage of the circuit both adopt the variable topology two-way AC / AC scheme to achieve the wireless electric energy transmission frequency conversion output function, the system efficiency is improved, the cost is reduced, the circuit is novel, reliable and practical, and the control scheme is novel.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless power transmission, and in particular relates to a bidirectional WPT AC-AC frequency conversion system based on a variable topology bidirectional AC / AC. Background Art

[0002] Wireless power transmission frequency conversion circuits are widely used in rail transit, electric vehicles, mining, smart homes and other fields. AC systems require power factor correction. The use of bridgeless power factor correction can effectively improve system efficiency by removing the uncontrolled rectification link. For AC input frequency conversion systems, the use of AC / AC direct conversion will eliminate the rectification link and effectively improve system efficiency while reducing costs. If these two types of technologies are used at the same time, the system efficiency of wireless power transmission frequency conversion circuits will be greatly improved. The bidirectional wireless power transmission system makes the application of wireless power transmission more flexible, realizes 4-quadrant operation, and makes the application range more extensive. However, there are no reports on the use of bridgeless PFC direct AC / AC solutions in both the front and rear stages of bidirectional wireless power transmission.

[0003] The existing technical solutions for AC input and AC output of wireless power transmission mostly adopt the method of first performing diode power frequency rectification after AC input, then performing power factor correction after rectification, and then performing high-frequency inversion to excite the sending coil of the wireless power transmission. After the wireless power transmission receiving coil inputs high-frequency AC, it first performs diode high-frequency rectification, and then performs inverter output of power frequency AC. Therefore, the existing solutions have too many links and low efficiency. Summary of the invention

[0004] The present invention provides a bidirectional WPT AC-AC frequency conversion system based on a variable topology bidirectional AC / AC, which is used to solve the technical problem of too many AC-AC stages and low efficiency under the technical conditions of wireless power transmission. The present invention realizes bidirectional AC-AC energy transmission with fewer stages and higher efficiency.

[0005] The present invention provides a bidirectional WPT AC-AC frequency conversion system based on a variable topology bidirectional AC / AC, comprising a variable topology bidirectional AC / AC-1 unit, a wireless power transmission unit and a variable topology bidirectional AC / AC-2 unit connected in sequence; The variable topology bidirectional AC / AC-1 unit comprises: A first variable topology LCL filter composed of a first inductor L11, a second inductor L12 and a first equivalent programmable capacitor C11, wherein the first variable topology LCL filter is composed of a fifth power electronic AC switch Q5 and a first capacitor C1 connected in series, and the switching of the first equivalent programmable capacitor C11 is controlled by controlling the on and off of the fifth power electronic AC switch Q5, and the size of the first equivalent programmable capacitor C11 is adjusted by controlling the duty cycle of the fifth power electronic AC switch Q5; a first bridge arm formed by a first power electronic AC switch Q1 and a second power electronic AC switch Q2, wherein an intersection point between the first power electronic AC switch Q1 and the second power electronic AC switch Q2 is M; and A second bridge arm formed by a third power electronic AC switch Q3 and a fourth power electronic AC switch Q4, wherein an intersection point between the third power electronic AC switch Q3 and the fourth power electronic AC switch Q4 is N; Among them, one end of the first inductor L11 is connected to the first low-frequency AC The other end of the first inductor L11 is connected to point C, and point C is simultaneously connected to one end of the first equivalent programmable capacitor C11, one end of the first power electronic AC switch Q1, and one end of the third power electronic AC switch Q3. The port point B of the first equivalent programmable capacitor C11 is connected to the other end and one end of the second inductor L12, the other end of the second inductor L12 is connected to the point D, and the point D is connected to one end of the second power electronic AC switch Q2 and one end of the fourth power electronic AC switch Q4; Furthermore, the variable topology bidirectional AC / AC-2 unit comprises: a third bridge arm formed by a sixth power electronic AC switch S1 and a seventh power electronic AC switch S2, wherein an intersection point between the sixth power electronic AC switch S1 and the seventh power electronic AC switch S2 is O; a fourth bridge arm formed by an eighth power electronic AC switch S3 and a ninth power electronic AC switch S4, wherein an intersection point between the eighth power electronic AC switch S3 and the ninth power electronic AC switch S4 is P; and A second variable topology LCL filter composed of a third inductor L21, a fourth inductor L22 and a second equivalent programmable capacitor C21, wherein the second equivalent programmable capacitor C21 is composed of a tenth power electronic AC switch S5 and a second capacitor C2 connected in series, and the switching of the second equivalent programmable capacitor C21 is controlled by controlling the on and off of the tenth power electronic AC switch S5, and the size of the second equivalent programmable capacitor C21 is adjusted by controlling the duty cycle of the tenth power electronic AC switch S5; One end of the third inductor L21 is connected to the intersection E of the sixth power electronic AC switch S5 and the eighth power electronic AC switch S3, and the other end of the third inductor L21 is connected to the second low-frequency AC Point G is connected to one end of the second equivalent programmable capacitor C21, and the other end of the second equivalent programmable capacitor C21 is connected to one end of the seventh power electronic AC switch S2 and one end of the ninth power electronic AC switch S4, respectively. Point F is connected to one end of the fourth inductor L22, and the other end of the fourth inductor L22 is connected to the second low-frequency AC The port H point.

[0006] Furthermore, the first high frequency AC on one side of the wireless power transmission unit Connected to the MN of the variable topology bidirectional AC / AC-1 unit, the second high frequency AC on the other side of the wireless power transmission unit connected to the OP of the variable topology bidirectional AC / AC-2 unit; When energy is transferred in the forward direction, that is, when energy is transferred from AB to GH, the variable topology bidirectional AC / AC-1 unit performs power factor correction control while performing direct AC / AC conversion, and the wireless power transmission unit is used to transfer energy from MN to OP, and the variable topology bidirectional AC / AC-2 unit performs direct AC / AC voltage and frequency conversion GH side output; When energy is transferred in the reverse direction, that is, when energy is transferred from GH to AB, the variable topology bidirectional AC / AC-2 unit performs direct AC / AC conversion while performing power factor correction control, and the wireless power transmission unit is used to transfer energy from OP to MN, and the variable topology bidirectional AC / AC-1 unit performs direct AC / AC voltage and frequency conversion and AB side output.

[0007] Furthermore, when energy is transferred in the forward direction, the fifth power electronic AC switch Q5 of the variable topology bidirectional AC / AC-1 unit is always disconnected, the first capacitor C1 is not connected to the circuit, and the first variable topology structure LCL filter is changed to a dual-inductor structure, and the variable topology bidirectional AC / AC-2 unit converts the first high-frequency AC Converted into a second low frequency AC Output; When energy is transferred in reverse, the tenth power electronic AC switch S5 of the variable topology bidirectional AC / AC-2 unit is always disconnected, the second capacitor C2 is not connected to the circuit, and the second variable topology structure LCL filter is changed to a dual-inductor structure. When energy is transferred in reverse, the variable topology bidirectional AC / AC-1 unit converts the second high-frequency AC Convert to the first low frequency Output.

[0008] Furthermore, the operating conditions of the variable topology bidirectional AC / AC-1 unit include: Working condition 1-1: is positive and The current flows from top to bottom; Working condition 1-2: is positive and The current flows from bottom to top; Conditions 1-3: is negative and The current flows from top to bottom; Conditions 1-4: is negative and The current flows from bottom to top; Among them, working condition 1-1, working condition 1-2, working condition 1-3 and working condition 1-4 each have sub-working condition a: the first inductor L11 and the second inductor L12 are both charged, and sub-working condition b: the first inductor L11 and the second inductor L12 are both discharged; Working condition 1-1-a sub-working condition: is positive, Q1 and Q2 are closed, L11 and L12 are positively charged; sub-condition 1-1-b of operating condition: is positive, Q1 and Q4 are closed, L11 and L12 continue to discharge, Current from top to bottom; sub-condition 1-2-a: is positive, Q3 and Q4 are closed, L11 and L12 are positively charged; sub-condition 1-2-b: is positive, Q2 and Q3 are closed, L11 and L12 are discharged in the forward direction. Current from bottom to top; sub-condition 1-3-a: is negative, Q1 and Q2 are closed, and L11 and L12 are reversely charged; sub-condition 1-3-b: is negative, Q2 and Q3 are closed, L11 and L12 are discharged in reverse direction. Current from top to bottom; working condition 1-4-a sub-working condition: is negative, Q3 and Q4 are closed, L11 and L12 are reversely charged; sub-condition 1-4-b: is negative, Q1 and Q4 are closed, L11 and L12 are discharged in reverse direction. The current flows from bottom to top; During forward energy transmission, the various operating conditions of the variable topology bidirectional AC / AC-1 unit are switched to perform power factor correction and direct AC / AC conversion, and the MN side of the wireless power transmission unit is stimulated.

[0009] Furthermore, the operating conditions of the variable topology bidirectional AC / AC-2 unit include: Working condition 2-1: is positive and The current flows from top to bottom; Working condition 2-2: is positive and The current flows from bottom to top; Working condition 2-3: is negative and The current flows from top to bottom; Working conditions 2-4: is negative and The current flows from bottom to top; Among them, working condition 2-1, working condition 2-2, working condition 2-3 and working condition 2-4 each have sub-working condition a: the third inductor L21 and the fourth inductor L22 are both charged, and sub-working condition b: the third inductor L21 and the fourth inductor L22 are both discharged; Working condition 2-1-a sub-working condition: is positive, S1 and S2 are closed, L21 and L22 are positively charged; sub-condition 2-1-b: is positive, S1 and S4 are closed, L21 and L22 continue to discharge, Current from top to bottom; sub-condition 2-2-a: is positive, S3 and S4 are closed, L21 and L22 are positively charged; sub-condition 2-2-b of working condition: is positive, S2 and S3 are closed, L21 and L22 are discharged in the forward direction. Current from bottom to top; sub-condition 2-3-a: is negative, S1 and S2 are closed, L21 and L22 are reversely charged; sub-condition 2-3-b: is negative, S2 and S3 are closed, L21 and L22 discharge in reverse direction. Current from top to bottom; sub-condition 2-4-a: is negative, S3 and S4 are closed, L21 and L22 are reversely charged; sub-condition 2-4-b: is negative, S1 and S4 are closed, and L21 and L22 discharge in reverse direction; The current flows from bottom to top; During reverse energy transmission, the various operating conditions of the variable topology bidirectional AC / AC-2 unit are switched to perform power factor correction and direct AC / AC conversion, and the OP side of the wireless power transmission unit is stimulated.

[0010] Furthermore, when the energy is transferred in the forward direction, the variable topology bidirectional AC / AC-2 unit controls the duty cycle of the tenth power electronic AC switch S5 to program the size of the second equivalent programmable capacitor C21, and the second variable topology structure LCL filter is " The "type" capacitor programmable LCL filter is used to meet the active impedance matching under different load conditions.

[0011] Furthermore, when energy is transferred in the reverse direction, the variable topology bidirectional AC / AC-1 unit controls the duty cycle of the fifth power electronic AC switch Q5 to program the size of the first equivalent programmable capacitor C11, and the first variable topology structure LCL filter is " The "type" capacitor programmable LCL filter is used to meet the active impedance matching under different load conditions.

[0012] The bidirectional WPT AC-AC frequency conversion system based on variable topology bidirectional AC / AC of the present application has the ability to realize bidirectional wireless power transmission. The front and rear stages of the wireless power transmission of the circuit of the present application both adopt a direct AC / AC solution to realize the frequency conversion output function of wireless power transmission, thereby improving system efficiency and reducing costs. The circuit is novel, reliable, and practical, and the control scheme is novel. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0014] Figure 1 The present invention is a block diagram of a multifunctional circuit structure of wireless power transmission based on bidirectional bridgeless AC / AC; Figure 2 The block diagram of the bidirectional WPT AC-AC frequency conversion system based on the variable topology bidirectional AC / AC of the present invention; Figure 3 The main circuit topology diagram of the bidirectional WPT AC-AC frequency conversion system based on the variable topology bidirectional AC / AC of the present invention; Figure 4 This is the topological diagram of the main circuit of the system when energy is transferred in the forward direction; Figure 5 This is the topological diagram of the main circuit of the system when energy is transferred in reverse direction; Figure 6 It is the equivalent main circuit topology diagram of the time-varying topology bidirectional AC / AC-1 unit with forward energy transfer; Figure 7 This is a schematic diagram of the working condition 1-1 of the variable topology bidirectional AC / AC-1 unit in the forward energy transfer mode. is positive, Working diagram when the current flows from top to bottom (↓); Figure 8 The schematic diagram of the working condition 1-2 of the variable topology bidirectional AC / AC-1 unit in the forward energy transfer mode is shown in FIG. is positive, Working diagram when the current flows from bottom to top (↑); Fig. 9 The schematic diagram of the working condition 1-3 of the variable topology bidirectional AC / AC-1 unit in the forward energy transfer mode is shown in FIG. is negative, Working diagram when the current flows from top to bottom (↓); Fig.10 The schematic diagram of the working conditions 1-4 of the variable topology bidirectional AC / AC-1 unit in the forward energy transfer mode is shown in FIG. is negative, Working diagram when the current flows from bottom to top (↑); Fig.11 The equivalent main circuit topology diagram of the energy forward transfer time-varying topology bidirectional AC / AC-2 unit; Fig.12 The equivalent main circuit topology diagram of the time-varying topology bidirectional AC / AC-1 unit with reverse energy transfer; Fig.13 The equivalent main circuit topology of the time-varying topology bidirectional AC / AC-2 unit with reverse energy transfer; Fig.14 The schematic diagram of the working condition 2-1 of the variable topology bidirectional AC / AC-2 unit with reverse energy transfer is shown in Figure 2-1. is positive, Working diagram when the current flows from top to bottom (↓); Fig.15 The schematic diagram of the working of the variable topology bidirectional AC / AC-2 unit 2-2 is shown in Figure 2. is positive, Working diagram when the current flows from bottom to top (↑); Fig.16 The schematic diagram of the working condition 2-3 of the variable topology bidirectional AC / AC-2 unit when the energy is reversely transferred, that is, the variable topology bidirectional AC / AC-2 unit is is negative, Working diagram when the current flows from top to bottom (↓); Fig.17 The schematic diagram of the working condition 2-4 of the variable topology bidirectional AC / AC-2 unit when the energy is reversely transferred, that is, the variable topology bidirectional AC / AC-2 unit is is negative, Working diagram when the current flows from bottom to top (↑); Fig.18 The present invention is a circuit diagram of a bidirectional WPT AC-AC frequency conversion system circuit based on a variable topology bidirectional AC / AC using a MOSFET-based power electronic AC switch. DETAILED DESCRIPTION

[0015] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0016] Figure 1 It is a structural block diagram of a multifunctional circuit for wireless power transmission based on bidirectional bridgeless AC / AC, which includes, in sequence, a low-frequency diode rectifier unit for rectifying low-frequency AC into DC, a power factor correction unit for realizing power factor correction, an inverter excitation unit for realizing high-frequency inverter excitation, a wireless power transmission unit for realizing wireless power transmission, a high-frequency diode rectifier unit for rectifying high-frequency AC into DC, a DC-DC unit for realizing voltage stabilization, and an inverter output unit.

[0017] The existing solutions have many unit levels, high cost and low efficiency, while the circuit topology of the present invention is simple, low cost and high efficiency.

[0018] Figure 2 The block diagram of the bidirectional WPT AC-AC frequency conversion system based on the variable topology bidirectional AC / AC of the present invention; The present invention comprises three units, namely, a variable topology bidirectional AC / AC-1 unit, a wireless power transmission unit, and a variable topology bidirectional AC / AC-2 unit, which are connected in sequence; The circuit of the present invention has two working conditions: forward energy transmission and reverse energy transmission. During forward energy transmission, the variable topology bidirectional AC / AC-1 unit completes power factor correction while realizing direct AC / AC excitation of the wireless power transmission unit. The wireless power transmission unit realizes wireless power transmission to transmit energy from MN to OP, and the variable topology bidirectional AC / AC-2 unit realizes direct AC / AC frequency conversion and voltage conversion output. During reverse energy transmission, the variable topology bidirectional AC / AC-2 unit completes power factor correction while realizing direct AC / AC excitation of the wireless power transmission unit. The wireless power transmission unit realizes wireless power transmission to transmit energy from OP to MN, and the variable topology bidirectional AC / AC-1 unit realizes direct AC / AC frequency conversion and voltage conversion output. In the forward energy transfer, that is, the energy is transferred from the AB side Transmitted to GH side When the input end of the variable topology bidirectional AC / AC-1 unit is the AB side , the output end MN of the variable topology bidirectional AC / AC-1 unit is connected to the primary input end of the wireless power transmission unit, and the primary input end of the wireless power transmission unit is MN; the secondary output end OP of the wireless power transmission unit is connected, and the secondary output end OP of the wireless power transmission unit is connected to the input end of the variable topology bidirectional AC / AC-2 unit, and the output end of the variable topology bidirectional AC / AC-2 unit is the system output of the forward energy transmission of the present invention, and outputs variable voltage and variable frequency AC; In reverse energy transfer, energy is transferred from the GH side. Transmitted to AB side When the input end of the variable topology bidirectional AC / AC-2 unit is the GH side , the input end OP of the variable topology bidirectional AC / AC-2 unit is connected to the primary input end of the wireless power transmission unit, and the primary input end of the wireless power transmission unit is OP; the secondary output end MN of the wireless power transmission unit is connected, and the secondary output end OP of the wireless power transmission unit is connected to the input end of the variable topology bidirectional AC / AC-2 unit, and the output end AB of the variable topology bidirectional AC / AC-1 unit is the system output of the forward energy transmission of the present invention, and outputs variable voltage and variable frequency AC; During forward energy transmission, the variable topology bidirectional AC / AC-1 unit realizes direct AC / AC conversion while completing the power factor correction function to complete the variable frequency high frequency excitation on the MN side of the wireless power transmission. At this time, the variable topology bidirectional AC / AC-1 unit adopts the power factor correction control algorithm and completes the low frequency / high frequency AC / AC conversion; during forward energy transmission, the variable topology bidirectional AC / AC-2 unit realizes high frequency / low frequency AC / AC voltage and frequency conversion GH side output; During reverse energy transmission, the variable topology bidirectional AC / AC-2 unit realizes direct AC / AC conversion while completing the power factor correction function to complete the variable frequency high-frequency excitation on the OP side of the wireless power transmission. At this time, the variable topology bidirectional AC / AC-2 unit adopts the power factor correction control algorithm while completing the low-frequency / high-frequency AC / AC conversion; during reverse energy transmission, the variable topology bidirectional AC / AC-1 unit realizes high-frequency / low-frequency AC / AC voltage and frequency conversion AB side output.

[0019] Figure 3 The main circuit topology diagram of the bidirectional WPT AC-AC frequency conversion system based on the variable topology bidirectional AC / AC of the present invention; The present invention comprises three units, namely, a variable topology bidirectional AC / AC-1 unit, a wireless power transmission unit, and a variable topology bidirectional AC / AC-2 unit, which are connected in sequence; The variable topology bidirectional AC / AC-1 unit includes: A first variable topology LCL filter composed of a first inductor L11, a second inductor L12 and a first equivalent programmable capacitor C11, wherein the first variable topology LCL filter is composed of a fifth power electronic AC switch Q5 and a first capacitor C1 connected in series, and the switching of the first equivalent programmable capacitor C11 is controlled by controlling the on and off of the fifth power electronic AC switch Q5, and the size of the first equivalent programmable capacitor C11 is adjusted by controlling the duty cycle of the fifth power electronic AC switch Q5; a first bridge arm formed by a first power electronic AC switch Q1 and a second power electronic AC switch Q2, wherein an intersection point between the first power electronic AC switch Q1 and the second power electronic AC switch Q2 is M; and A second bridge arm formed by a third power electronic AC switch Q3 and a fourth power electronic AC switch Q4, wherein an intersection point between the third power electronic AC switch Q3 and the fourth power electronic AC switch Q4 is N; Among them, one end of the first inductor L11 is connected to the first low-frequency AC The other end of the first inductor L11 is connected to point C, and point C is simultaneously connected to one end of the first equivalent programmable capacitor C11, one end of the first power electronic AC switch Q1, and one end of the third power electronic AC switch Q3. The port point B of the first equivalent programmable capacitor C11 is connected to the other end and one end of the second inductor L12, the other end of the second inductor L12 is connected to the point D, and the point D is connected to one end of the second power electronic AC switch Q2 and one end of the fourth power electronic AC switch Q4; The variable topology bidirectional AC / AC-2 unit includes: a third bridge arm formed by a sixth power electronic AC switch S1 and a seventh power electronic AC switch S2, wherein an intersection point between the sixth power electronic AC switch S1 and the seventh power electronic AC switch S2 is O; a fourth bridge arm formed by an eighth power electronic AC switch S3 and a ninth power electronic AC switch S4, wherein an intersection point between the eighth power electronic AC switch S3 and the ninth power electronic AC switch S4 is P; and A second variable topology LCL filter composed of a third inductor L21, a fourth inductor L22 and a second equivalent programmable capacitor C21, wherein the second equivalent programmable capacitor C21 is composed of a tenth power electronic AC switch S5 and a second capacitor C2 connected in series, and the switching of the second equivalent programmable capacitor C21 is controlled by controlling the on and off of the tenth power electronic AC switch S5, and the size of the second equivalent programmable capacitor C21 is adjusted by controlling the duty cycle of the tenth power electronic AC switch S5; One end of the third inductor L21 is connected to the intersection E of the sixth power electronic AC switch S5 and the eighth power electronic AC switch S3, and the other end of the third inductor L21 is connected to the second low-frequency AC Point G is connected to one end of the second equivalent programmable capacitor C21, and the other end of the second equivalent programmable capacitor C21 is connected to one end of the seventh power electronic AC switch S2 and one end of the ninth power electronic AC switch S4, respectively. Point F is connected to one end of the fourth inductor L22, and the other end of the fourth inductor L22 is connected to the second low-frequency AC The port H point.

[0020] The first high frequency AC on one side of the wireless power transmission unit Connected to the MN of the variable topology bidirectional AC / AC-1 unit, the second high frequency AC on the other side of the wireless power transmission unit connected to the OP of the variable topology bidirectional AC / AC-2 unit; When energy is transferred in the forward direction, that is, when energy is transferred from AB to GH, the variable topology bidirectional AC / AC-1 unit performs power factor correction control while performing direct AC / AC conversion, and the wireless power transmission unit is used to transfer energy from MN to OP, and the variable topology bidirectional AC / AC-2 unit performs direct AC / AC voltage and frequency conversion GH side output; When energy is transferred in the reverse direction, that is, when energy is transferred from GH to AB, the variable topology bidirectional AC / AC-2 unit performs power factor correction control while performing direct AC / AC conversion, and the wireless power transmission unit is used to transfer energy from OP to MN, and the variable topology bidirectional AC / AC-1 unit performs direct AC / AC voltage and frequency conversion output on the AB side; When energy is transferred in the forward direction, the fifth power electronic AC switch Q5 of the variable topology bidirectional AC / AC-1 unit is always disconnected, the first capacitor C1 is not connected to the circuit, and the first variable topology structure LCL filter is changed to a dual-inductor structure. The variable topology bidirectional AC / AC-2 unit converts the first high-frequency AC Converted into a second low frequency AC Output; When the energy is transferred in the forward direction, the variable topology bidirectional AC / AC-2 unit controls the duty cycle of the tenth power electronic AC switch S5 to program the size of the second equivalent programmable capacitor C21. The second variable topology structure LCL filter is " "Type" capacitor programmable LCL filter, used to meet active impedance matching under different load conditions; When energy is transferred in reverse, the variable topology bidirectional AC / AC-1 unit controls the duty cycle of the fifth power electronic AC switch Q5 to program the size of the first equivalent programmable capacitor C11. The first variable topology structure LCL filter is " "Type" capacitor programmable LCL filter, used to meet active impedance matching under different load conditions; When energy is transferred in reverse, the tenth power electronic AC switch S5 of the variable topology bidirectional AC / AC-2 unit is always disconnected, the second capacitor C2 is not connected to the circuit, and the second variable topology structure LCL filter is changed to a dual-inductor structure. When energy is transferred in reverse, the variable topology bidirectional AC / AC-1 unit converts the second high-frequency AC Convert to the first low frequency Output.

[0021] The wireless power transmission unit adopts a series-parallel topology, and can be used in any appropriate topology in practice, which is selected and designed according to actual needs; The system of the present invention has symmetry, including circuit topology symmetry and working condition symmetry. Circuit topology symmetry: the variable topology bidirectional AC / AC-1 unit is symmetrical with the variable topology bidirectional AC / AC-2 unit, and the wireless power transmission is self-symmetrical; working condition symmetry: the forward energy transmission and the reverse energy transmission are symmetrical working conditions.

[0022] Figure 4 This is the topological diagram of the main circuit of the system when energy is transferred in the forward direction; When the energy is transferred in the forward direction, the energy is transferred from AB to GH. The fifth power electronic AC switch Q5 of the variable topology bidirectional AC / AC-1 unit is always disconnected, the first capacitor C1 is not connected to the circuit, and the first variable topology structure LCL filter is changed to a dual-inductor structure. The variable topology bidirectional AC / AC-1 unit completes the power factor correction while realizing the direct AC-AC conversion from low-frequency AC to high-frequency AC, and performs high-frequency excitation on the MN end of the wireless power transmission. When the energy is transferred in the forward direction, the tenth power electronic AC switch S5 of the variable topology bidirectional AC / AC-2 unit is controlled, and the duty cycle of the tenth power electronic AC switch S5 is controlled to realize the programmability of the second equivalent programmable capacitor C21, and the second variable topology structure LCL filter becomes The variable topology bidirectional AC / AC-2 unit realizes direct AC-AC conversion of high-frequency AC into low-frequency AC output, and completes active impedance matching under different load conditions by controlling the second equivalent programmable capacitor C21.

[0023] Figure 5 This is the topological diagram of the main circuit of the system when energy is transferred in reverse direction; When energy is transferred in reverse, energy is transferred from GH to AB. The tenth power electronic AC switch S5 of the variable topology bidirectional AC / AC-2 unit is always disconnected, the second capacitor C2 is not connected to the circuit, and the second variable topology structure LCL filter is changed to a dual-inductor structure. The variable topology bidirectional AC / AC-2 unit completes power factor correction while realizing direct AC-AC conversion from low-frequency AC to high-frequency AC, and performs high-frequency excitation on the OP end of the wireless power transmission. When energy is transferred in reverse, the fifth power electronic AC switch Q5 of the variable topology bidirectional AC / AC-1 unit is controlled, and the duty cycle of the fifth power electronic AC switch Q5 is controlled to realize the programmability of the first equivalent programmable capacitor C11, and the first variable topology structure LCL filter is changed to become The variable topology bidirectional AC / AC-1 unit realizes direct AC-AC conversion of high-frequency AC into low-frequency AC output, and completes active impedance matching under different load conditions by controlling the first equivalent programmable capacitor C11.

[0024] Figure 6 It is the equivalent main circuit topology diagram of the time-varying topology bidirectional AC / AC-1 unit with forward energy transfer; When energy is transferred in the forward direction, Q5 of the variable topology bidirectional AC / AC-1 unit is always disconnected, and C1 is not connected to the circuit; the equivalent main circuit is composed of L11, L12 and Q1~Q4, Q1 and Q2 form a bridge arm with the intersection point M, Q3 and Q4 form another bridge arm with the intersection point N, and L11=L12 is preferred; The forward transmission time-varying topology bidirectional AC / AC-1 unit, as the excitation source of the wireless power transmission unit, completes two functions at the same time: power factor correction and direct AC / AC excitation, that is, it requires the completion of power factor correction control and direct AC / AC conversion control but does not necessarily require the realization of sinusoidal waveform output; the reverse transmission time-varying topology bidirectional AC / AC-1 unit realizes the high-frequency / low-frequency direct AC / AC voltage and frequency conversion AB side output.

[0025] Figure 7-Figure 10 The various working conditions of the time-varying topology bidirectional AC / AC-1 unit with forward energy transfer: Figure 7 This is a schematic diagram of the working condition 1-1 of the variable topology bidirectional AC / AC-1 unit in the forward energy transfer mode. is positive, Working diagram when the current flows from top to bottom (↓); Figure 7 (a) in the equation is is positive, Q1 and Q2 are closed, and L11 and L12 are positively charged; Figure 7 (b) in the equation is is positive, Q1 and Q4 are closed, L11 and L12 continue to discharge, The current flows from top to bottom (↓).

[0026] Figure 8 The schematic diagram of the working condition 1-2 of the variable topology bidirectional AC / AC-1 unit in the forward energy transfer mode is shown in FIG. is positive, Working diagram when the current flows from bottom to top (↑); Figure 8 (a) in the equation is is positive, Q3 and Q4 are closed, and L11 and L12 are positively charged; Figure 8 (b) in the equation is is positive, Q2 and Q3 are closed, L11 and L12 are discharged in the forward direction. The current flows from bottom to top (↑).

[0027] Fig. 9 The schematic diagram of the working condition 1-3 of the variable topology bidirectional AC / AC-1 unit in the forward energy transfer mode is shown in FIG. is negative, Working diagram when the current flows from top to bottom (↓); Fig. 9 (a) in the equation is is negative, Q1 and Q2 are closed, and L11 and L12 are reversely charged; Fig. 9 (b) in the equation is is negative, Q2 and Q3 are closed, L11 and L12 are discharged in reverse direction. The current flows from top to bottom (↓).

[0028] Fig.10 The schematic diagram of the working conditions 1-4 of the variable topology bidirectional AC / AC-1 unit in the forward energy transfer mode is shown in FIG. is negative, Working diagram when the current flows from bottom to top (↑); Fig.10 (a) in the equation is is negative, Q3 and Q4 are closed, and L11 and L12 are reversely charged; Fig.10 (b) in the equation is is negative, Q1 and Q4 are closed, and L11 and L12 discharge in reverse direction; The current flows from bottom to top (↑).

[0029] During forward energy transmission, power factor correction and direct AC / AC conversion are achieved by controlling the various operating conditions of the variable topology bidirectional AC / AC-1 unit, and the excitation of the MN side of the wireless power transmission unit is realized. Power factor correction requirements With input current In the same phase, since the forward transmission time-varying topology bidirectional AC / AC-1 unit also needs to realize direct AC / AC excitation, it is not suitable to adopt switching frequency variable frequency control schemes such as hysteresis control, and direct AC / AC conversion control does not require the realization of sinusoidal waveform output. The forward transmission time-varying topology bidirectional AC / AC-1 unit realizes the high-frequency / low-frequency direct AC / AC voltage and frequency conversion AB side output.

[0030] Fig.11 The equivalent main circuit topology diagram of the energy forward transfer time-varying topology bidirectional AC / AC-2 unit; Energy forward transfer time-varying topology bidirectional AC / AC-2 unit converts high frequency AC Convert to low frequency AC Output; S1~S4 are controlled to complete direct AC-AC conversion, using direction-variable interactive rectification control, that is, In the positive half cycle, rectification control is implemented on S1~S4 to make the output of port EF positive. In the negative half cycle, rectification control is implemented on S1~S4 to make the output of port EF negative; The energy forward transfer time-varying topology bidirectional AC / AC-2 unit controls the duty cycle of S5 to achieve the second equivalent programmable capacitor C21 with programmable size, and the filter becomes The programmable LCL filter can meet the active impedance matching under different load conditions.

[0031] Fig.12 The equivalent main circuit topology diagram of the time-varying topology bidirectional AC / AC-1 unit with reverse energy transfer; Energy reverse transfer time-varying topology bidirectional AC / AC-1 unit converts high frequency AC Convert to low frequency Output; Q1~Q4 are controlled to complete direct AC-AC conversion, using direction-variable interactive rectification control, that is, In the positive half cycle, rectification control is implemented on S1~S4 to make the output of port CD positive. In the negative half cycle, rectification control is implemented on S1~S4 to make the output of port CD negative; The energy reverse transfer time-varying topology bidirectional AC / AC-1 unit controls Q5 and realizes the first equivalent programmable capacitor C11 programmable by controlling the duty cycle of Q5, and the filter becomes a capacitor programmable Type LCL filter to meet active impedance matching under different load conditions.

[0032] Fig.13 This is the equivalent main circuit topology diagram of the time-varying topology bidirectional AC / AC-2 unit with reverse energy transfer.

[0033] When energy is transferred in reverse, the variable topology bidirectional AC / AC-2 unit realizes the excitation function of the wireless power transmission unit, and the equivalent main circuit is composed of L11, L12 and S1~S4, S1 and S2 form a bridge arm with the intersection point O, and S3 and S4 form another bridge arm with the intersection point P; The reverse transmission time-varying topology bidirectional AC / AC-2 unit, as the excitation source of the wireless power transmission unit, completes two functions at the same time: power factor correction and direct AC / AC excitation, that is, it requires the completion of power factor correction control and direct AC / AC conversion control but does not necessarily require the realization of sinusoidal waveform output; the forward transmission time-varying topology bidirectional AC / AC-2 unit realizes the high-frequency / low-frequency direct AC / AC voltage and frequency conversion GH-side output.

[0034] Figure 14-17 Schematic diagram of various operating conditions of the time-varying topology bidirectional AC / AC-2 unit with reverse energy transfer.

[0035] Fig.14 The schematic diagram of the working condition 2-1 of the variable topology bidirectional AC / AC-2 unit with reverse energy transfer is shown in Figure 2-1. is positive, Working diagram when the current flows from top to bottom (↓); Fig.14 (a) in the equation is is positive, S1 and S2 are closed, and L21 and L22 are positively charged; Fig.14 (b) in the equation is is positive, S1 and S4 are closed, L21 and L22 continue to discharge, The current flows from top to bottom (↓).

[0036] Fig.15 The schematic diagram of the working of the variable topology bidirectional AC / AC-2 unit 2-2 is shown in Figure 2. is positive, Working diagram when the current flows from bottom to top (↑); Fig.15 (a) in the equation is is positive, S3 and S4 are closed, and L21 and L22 are positively charged; Fig.15 (b) in the equation is is positive, S2 and S3 are closed, L21 and L22 are discharged in the forward direction. The current flows from bottom to top (↑).

[0037] Fig.16 The schematic diagram of the working condition 2-3 of the variable topology bidirectional AC / AC-2 unit when the energy is reversely transferred, that is, the variable topology bidirectional AC / AC-2 unit is is negative, Working diagram when the current flows from top to bottom (↓); Fig.16 (a) in the equation is is negative, S1 and S2 are closed, and L21 and L22 are charged in reverse; Fig.16 (b) in the equation is is negative, S2 and S3 are closed, L21 and L22 discharge in reverse direction. The current flows from top to bottom (↓).

[0038] Fig.17 The schematic diagram of the working condition 2-4 of the variable topology bidirectional AC / AC-2 unit when the energy is reversely transferred, that is, the variable topology bidirectional AC / AC-2 unit is is negative, Working diagram when the current flows from bottom to top (↑); Fig.17 (a) in the equation is is negative, S3 and S4 are closed, and L21 and L22 are reversely charged; Fig.17 (b) in the equation is is negative, S1 and S4 are closed, and L21 and L22 discharge in reverse direction; The current flows from bottom to top (↑).

[0039] During reverse energy transmission, power factor correction and direct AC / AC conversion are achieved by controlling the various operating conditions of the variable topology bidirectional AC / AC-2 unit, and the excitation of the OP side of the wireless power transmission unit is realized. Power factor correction requirements With reverse input current In the same phase, since the reverse transmission time-varying topology bidirectional AC / AC-2 unit also needs to realize direct AC / AC excitation, it is not suitable to adopt variable frequency control schemes such as hysteresis control, and direct AC / AC conversion control does not require sinusoidal waveform output. The forward transmission time-varying topology bidirectional AC / AC-2 unit realizes the high-frequency / low-frequency direct AC / AC voltage-variable GH-side output.

[0040] Fig.18 This is the topological diagram of the main circuit of the system when energy is transferred in the forward direction; When the energy is transferred in the forward direction, the energy is transferred from AB to GH. Q5 of the variable topology bidirectional AC / AC-1 unit is always disconnected, C1 is not connected to the circuit, and the first variable topology structure LCL filter is changed to a dual-inductor structure. The variable topology bidirectional AC / AC-1 unit completes the power factor correction while realizing the direct AC-AC conversion from low-frequency AC to high-frequency AC, and performs high-frequency excitation on the MN end of the wireless power transmission. When the energy is transferred in the forward direction, S5 of the variable topology bidirectional AC / AC-2 unit is controlled, and the duty cycle of S5 is used to control the programmable capacitance of the second equivalent programmable capacitor C21, and the second variable topology structure LCL filter becomes The variable topology bidirectional AC / AC-2 unit realizes direct AC-AC conversion of high-frequency AC to low-frequency AC output, and completes active impedance matching under different load conditions by controlling the equivalent programmable capacitor C21.

[0041] Fig.18 The present invention discloses a circuit in which a bidirectional WPT AC-AC frequency conversion system circuit based on a variable topology bidirectional AC / AC adopts a power electronic AC switch based on MOSFET.

[0042] Although the wireless power transmission unit shown in the figure is a series-parallel topology, it can be used in actual use in any suitable topology, and the specific selection depends on actual needs. Q1~Q5 and S1~S5 are all power electronic AC switches. Since MOSFET has low on-state voltage drop and easy driving characteristics, power electronic AC switches based on MOSFET are preferred. As shown in the figure, they are composed of two identical metal-oxide semiconductor field effect transistors MOSFET connected in reverse series, that is, the source of the upper tube is connected to the drain of the lower tube, the drain of the upper tube and the source of the lower tube are the main current ports, and the gate drive control of the upper and lower tubes is separated.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A bidirectional WPT AC-AC frequency conversion system based on variable topology bidirectional AC / AC, characterized in that: It includes a variable topology bidirectional AC / AC-1 unit, a wireless power transmission unit, and a variable topology bidirectional AC / AC-2 unit connected in sequence; The variable topology bidirectional AC / AC-1 unit comprises: A first variable topology LCL filter composed of a first inductor L11, a second inductor L12 and a first equivalent programmable capacitor C11, wherein the first variable topology LCL filter is composed of a fifth power electronic AC switch Q5 and a first capacitor C1 connected in series, and the switching of the first equivalent programmable capacitor C11 is controlled by controlling the on and off of the fifth power electronic AC switch Q5, and the size of the first equivalent programmable capacitor C11 is adjusted by controlling the duty cycle of the fifth power electronic AC switch Q5; a first bridge arm formed by a first power electronic AC switch Q1 and a second power electronic AC switch Q2, wherein an intersection point between the first power electronic AC switch Q1 and the second power electronic AC switch Q2 is M; and A second bridge arm formed by a third power electronic AC switch Q3 and a fourth power electronic AC switch Q4, wherein an intersection point between the third power electronic AC switch Q3 and the fourth power electronic AC switch Q4 is N; Among them, one end of the first inductor L11 is connected to the first low-frequency AC The other end of the first inductor L11 is connected to point C, and point C is simultaneously connected to one end of the first equivalent programmable capacitor C11, one end of the first power electronic AC switch Q1, and one end of the third power electronic AC switch Q3. Port point B is connected to the other end of the first equivalent programmable capacitor C11 and one end of the second inductor L12, the other end of the second inductor L12 is connected to point D, and point D is connected to one end of the second power electronic AC switch Q2 and one end of the fourth power electronic AC switch Q4.

2. According to claim 1, a bidirectional WPT AC-AC frequency conversion system based on variable topology bidirectional AC / AC is characterized in that: The variable topology bidirectional AC / AC-2 unit comprises: a third bridge arm formed by a sixth power electronic AC switch S1 and a seventh power electronic AC switch S2, wherein an intersection point between the sixth power electronic AC switch S1 and the seventh power electronic AC switch S2 is O; a fourth bridge arm formed by an eighth power electronic AC switch S3 and a ninth power electronic AC switch S4, wherein an intersection point between the eighth power electronic AC switch S3 and the ninth power electronic AC switch S4 is P; and A second variable topology LCL filter composed of a third inductor L21, a fourth inductor L22 and a second equivalent programmable capacitor C21, wherein the second equivalent programmable capacitor C21 is composed of a tenth power electronic AC switch S5 and a second capacitor C2 connected in series, and the switching of the second equivalent programmable capacitor C21 is controlled by controlling the on and off of the tenth power electronic AC switch S5, and the size of the second equivalent programmable capacitor C21 is adjusted by controlling the duty cycle of the tenth power electronic AC switch S5; One end of the third inductor L21 is connected to the intersection E of the sixth power electronic AC switch S5 and the eighth power electronic AC switch S3, and the other end of the third inductor L21 is connected to the second low-frequency AC Point G is connected to one end of the second equivalent programmable capacitor C21, and the other end of the second equivalent programmable capacitor C21 is connected to one end of the seventh power electronic AC switch S2 and one end of the ninth power electronic AC switch S4, respectively. Point F is connected to one end of the fourth inductor L22, and the other end of the fourth inductor L22 is connected to the second low-frequency AC The port H point.

3. A bidirectional WPT AC-AC frequency conversion system based on variable topology bidirectional AC / AC according to claim 1, characterized in that: The first high frequency AC on one side of the wireless power transmission unit Connected to the MN of the variable topology bidirectional AC / AC-1 unit, the second high frequency AC on the other side of the wireless power transmission unit connected to the OP of the variable topology bidirectional AC / AC-2 unit; When energy is transferred in the forward direction, that is, when energy is transferred from AB to GH, the variable topology bidirectional AC / AC-1 unit performs power factor correction control while performing direct AC / AC conversion, and the wireless power transmission unit is used to transfer energy from MN to OP, and the variable topology bidirectional AC / AC-2 unit performs direct AC / AC voltage and frequency conversion GH side output; When energy is transferred in the reverse direction, that is, when energy is transferred from GH to AB, the variable topology bidirectional AC / AC-2 unit performs direct AC / AC conversion while performing power factor correction control, and the wireless power transmission unit is used to transfer energy from OP to MN, and the variable topology bidirectional AC / AC-1 unit performs direct AC / AC voltage and frequency conversion and AB side output.

4. A bidirectional WPT AC-AC frequency conversion system based on variable topology bidirectional AC / AC according to claim 1, characterized in that: When energy is transferred in the forward direction, the fifth power electronic AC switch Q5 of the variable topology bidirectional AC / AC-1 unit is always disconnected, the first capacitor C1 is not connected to the circuit, and the first variable topology structure LCL filter is changed to a dual-inductor structure. The variable topology bidirectional AC / AC-2 unit converts the first high-frequency AC Converted into a second low frequency AC Output; When energy is transferred in reverse, the tenth power electronic AC switch S5 of the variable topology bidirectional AC / AC-2 unit is always disconnected, the second capacitor C2 is not connected to the circuit, and the second variable topology structure LCL filter is changed to a dual-inductor structure. When energy is transferred in reverse, the variable topology bidirectional AC / AC-1 unit converts the second high-frequency AC Convert to the first low frequency Output.

5. A bidirectional WPT AC-AC frequency conversion system based on variable topology bidirectional AC / AC according to claim 1, characterized in that: The operating conditions of the variable topology bidirectional AC / AC-1 unit include: Working condition 1-1: is positive and The current flows from top to bottom; Working condition 1-2: is positive and The current flows from bottom to top; Conditions 1-3: is negative and The current flows from top to bottom; Conditions 1-4: is negative and The current flows from bottom to top; Among them, working condition 1-1, working condition 1-2, working condition 1-3 and working condition 1-4 each have sub-working condition a: the first inductor L11 and the second inductor L12 are both charged, and sub-working condition b: the first inductor L11 and the second inductor L12 are both discharged; Working condition 1-1-a sub-working condition: is positive, Q1 and Q2 are closed, L11 and L12 are positively charged; sub-condition 1-1-b of condition: is positive, Q1 and Q4 are closed, L11 and L12 continue to discharge, Current from top to bottom; sub-condition 1-2-a: is positive, Q3 and Q4 are closed, L11 and L12 are positively charged; sub-condition 1-2-b: is positive, Q2 and Q3 are closed, L11 and L12 are discharged in the forward direction. Current from bottom to top; sub-condition 1-3-a: is negative, Q1 and Q2 are closed, and L11 and L12 are reversely charged; sub-condition 1-3-b: is negative, Q2 and Q3 are closed, L11 and L12 are discharged in reverse direction. Current from top to bottom; working condition 1-4-a sub-working condition: is negative, Q3 and Q4 are closed, and L11 and L12 are reversely charged; sub-condition 1-4-b: is negative, Q1 and Q4 are closed, L11 and L12 are discharged in reverse direction. The current flows from bottom to top; During forward energy transmission, the various operating conditions of the variable topology bidirectional AC / AC-1 unit are switched to perform power factor correction and direct AC / AC conversion, and the MN side of the wireless power transmission unit is stimulated.

6. A bidirectional WPT AC-AC frequency conversion system based on variable topology bidirectional AC / AC according to claim 1, characterized in that: The operating conditions of the variable topology bidirectional AC / AC-2 unit include: Working condition 2-1: is positive and The current flows from top to bottom; Working condition 2-2: is positive and The current flows from bottom to top; Working condition 2-3: is negative and The current flows from top to bottom; Working conditions 2-4: is negative and The current flows from bottom to top; Among them, working condition 2-1, working condition 2-2, working condition 2-3 and working condition 2-4 each have sub-working condition a: the third inductor L21 and the fourth inductor L22 are both charged, and sub-working condition b: the third inductor L21 and the fourth inductor L22 are both discharged; Working condition 2-1-a sub-working condition: is positive, S1 and S2 are closed, L21 and L22 are positively charged; sub-condition 2-1-b: is positive, S1 and S4 are closed, L21 and L22 continue to discharge, Current from top to bottom; sub-condition 2-2-a: is positive, S3 and S4 are closed, L21 and L22 are positively charged; sub-condition 2-2-b of working condition: is positive, S2 and S3 are closed, L21 and L22 are discharged in the forward direction. Current from bottom to top; sub-condition 2-3-a: is negative, S1 and S2 are closed, L21 and L22 are reversely charged; sub-condition 2-3-b: is negative, S2 and S3 are closed, L21 and L22 discharge in reverse direction. Current from top to bottom; sub-condition 2-4-a: is negative, S3 and S4 are closed, L21 and L22 are reversely charged; sub-condition 2-4-b: is negative, S1 and S4 are closed, and L21 and L22 discharge in reverse direction; The current flows from bottom to top; During reverse energy transmission, the various operating conditions of the variable topology bidirectional AC / AC-2 unit are switched to perform power factor correction and direct AC / AC conversion, and the OP side of the wireless power transmission unit is stimulated.

7. A bidirectional WPT AC-AC frequency conversion system based on variable topology bidirectional AC / AC according to claim 1, characterized in that: When the energy is transferred in the forward direction, the variable topology bidirectional AC / AC-2 unit controls the duty cycle of the tenth power electronic AC switch S5 to program the size of the second equivalent programmable capacitor C21. The second variable topology structure LCL filter is " The "type" capacitor programmable LCL filter is used to meet the active impedance matching under different load conditions.

8. The bidirectional WPT AC-AC frequency conversion system based on variable topology bidirectional AC / AC according to claim 1 is characterized in that: When energy is transferred in reverse, the variable topology bidirectional AC / AC-1 unit controls the duty cycle of the fifth power electronic AC switch Q5 to program the size of the first equivalent programmable capacitor C11. The first variable topology structure LCL filter is " The "type" capacitor programmable LCL filter is used to meet the active impedance matching under different load conditions.

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