CN110422061B - Wireless bidirectional electric energy conversion topology and control method thereof - Google Patents

Abstract

The invention discloses a wireless bidirectional power conversion topology and a control method thereof, which adopts a parallel dual-input and dual-output system architecture, a combination of LCC-S and S-LCC as a hybrid compensation network, and a coil with multiple operating modes. The primary and secondary side coupling modules make it possible to select the best primary and secondary side coupling mechanism for coupling when the magnetic coupling mechanism has an offset distance. The proposed control method is to make the primary and secondary coils work in different modes by controlling the direction and presence of current in the two series-connected first unipolar coils and second unipolar coils in the primary and secondary coils. , and then switch the primary and secondary side coupling mechanisms, and select the primary and secondary side coupling mechanisms with the largest coupling coefficient of the offset distance of the primary and secondary side coils under different primary and secondary side coupling mechanisms as the optimal coupling mechanism, which greatly improves the primary and secondary side coils. Efficiency of energy transfer in the event of a positional offset and the stability and resistance to offset of the system.

Description

A wireless bidirectional power conversion topology and its control method

technical field

The invention belongs to the technical field of wireless bidirectional power transmission, and more particularly, relates to a wireless bidirectional power conversion topology and a control method thereof.

Background technique

Wireless charging technology is gaining popularity in the field of electric vehicles, which can be charged wirelessly through magnetic inductive coupling. Wireless charging has the advantages of high efficiency, safety, green, etc. It does not require mechanical connection, there is no aging and wear of the charging interface, there will be no problems such as poor contact or leakage, and it can be charged whenever it stops, and it can go away after charging, which is convenient fast.

Alignment between the primary and secondary magnetic coupling mechanisms is essential to ensure efficient charging at the expected power levels, and physical offsets can cause changes in key system parameters such as coil self-inductance, leakage inductance, and mutual inductance , which can lead to system instability, reduced power transfer, and increased power loss due to detuned operation. In order to solve the problems of system stability and poor anti-offset performance when there is offset between the primary and secondary side magnetic coupling mechanisms, the existing wireless bidirectional power conversion topology and its control method adopt some complex auxiliary control schemes and Circuit topologies, such as infrared guidance, often require additional auxiliary equipment, which is costly. In addition, the use of auxiliary control will generate control delay, reduce the reliability of the system, and can only improve the anti-offset performance in a narrow range. When the offset distance of the coupling mechanism is large, the anti-offset performance is relatively low. Difference.

To sum up, it is an urgent problem to provide a wireless bidirectional power conversion topology and a control method thereof with good offset resistance in a large offset range.

SUMMARY OF THE INVENTION

In view of the defects of the prior art, the purpose of the present invention is to provide a wireless bidirectional power conversion topology and a control method thereof, aiming to solve the problem that the magnetic coupling mechanism in the prior art is relatively large due to the use of an auxiliary control method to align the coupling mechanism. The problem of poor offset resistance in the offset range.

In order to achieve the above object, one aspect of the present invention provides a wireless bidirectional power conversion topology, including a primary side sending module, a primary side and secondary side coupling module, and a secondary side receiving module;

Among them, the primary side sending module and the secondary side receiving module are symmetrical about the primary side and the secondary side coupling module, the primary side sending module is coupled to the secondary side receiving module through the primary side side coupling module, and the output end of the primary side sending module is connected to the primary side coil. The input end of the coupling module is connected, and the output end of the primary and secondary side coil coupling module is connected with the secondary side receiving module;

The primary side sending module is used to convert DC power into AC power using a parallel dual input structure, and compensate the self-inductance and leakage inductance in the primary and secondary side coupling modules, and output stable AC power;

The primary and secondary side coupling module is used to couple the primary side sending module and the secondary side receiving module through a controllable coupling mechanism based on the principle of electromagnetic induction, and transmit power wirelessly;

The secondary side receiving module is used to convert the AC power with stable power after compensation into DC power by adopting a parallel dual output structure.

Further preferably, the primary side sending module includes a primary side high frequency full-bridge inverter circuit and a primary side compensation network, and the secondary side receiving module includes a secondary side full bridge rectification filter circuit and a secondary side compensation network; wherein, the primary side high frequency full bridge inverter circuit and the secondary side compensation network. The primary side compensation network is connected in series, and the secondary side full-bridge rectifier filter circuit is connected in series with the secondary side compensation network;

The primary side high-frequency full-bridge inverter circuit is used to adopt a parallel structure, combine the dual-input DC power through a common DC bus, and convert the DC power into AC power;

The primary side compensation network and the secondary side compensation network are composed of a hybrid compensation topology combining LCC-S topology and S-LCC topology, which are used to reduce the consumption of reactive power in the system, balance the influence of inductive reactance in the circuit, and further compensate for the coupling The influence of the misalignment of the mechanism prevents the coupling coefficient from dropping too fast and produces an approximately constant power output;

The secondary-side full-bridge rectifier and filter circuit is used to convert alternating current into dual-output direct-current by adopting a parallel structure, and the dual-output direct-current is combined and output through a common direct-current bus.

Further preferably, the primary-side high-frequency full-bridge inverter circuit and the secondary-side full-bridge rectification filter circuit respectively include a first inverter circuit and a second inverter circuit; wherein the first inverter circuit and the second inverter circuit are connected in parallel.

Further preferably, the primary and secondary side coupling modules are composed of primary and secondary side coils, and the primary side coils include the primary side first unipolar coils and the primary side second unipolar coils; the secondary side coils include the secondary side first unipolar coils. and the second unipolar coil on the secondary side; wherein the first unipolar coil on the primary side is connected in series with the second unipolar coil on the primary side, and the first unipolar coil on the secondary side is connected in series with the second unipolar coil on the secondary side.

Further preferably, the primary side coil includes a unipolar double coil working mode, a bipolar double coil working mode, and the secondary coil includes a unipolar single coil working mode, a unipolar double coil working mode, a bipolar working mode. Double coil working mode.

Further preferably, the shape of the primary and secondary side coils can be circular, rectangular and so on. By adding a magnetic core to guide the magnetic flux and shape the magnetic field, the distribution range of the magnetic field around the magnetic coupling mechanism can be effectively reduced.

Another aspect of the present invention provides a wireless bidirectional power conversion topology control method, comprising the following steps:

S1. Convert the DC voltage input from the primary side to a high-frequency AC voltage;

S2. Establish a finite element model for the primary and secondary coils with offset, and obtain the relationship between the offset distance and the coupling coefficient of the primary and secondary coils under different primary and secondary coupling mechanisms;

S3. Obtain the high-frequency AC voltage. Based on the relationship between the offset distance of the primary and secondary coils and the coupling coefficient, according to the offset of the primary and secondary coils, the optimal primary and secondary side coupling mechanism is obtained, which is coupled to the secondary side through electromagnetic induction. side, output high frequency AC voltage;

S4. Convert the high-frequency AC voltage obtained by the secondary side into a DC voltage for output.

Further preferably, the primary and secondary side coupling mechanisms include a primary side bipolar dual coil secondary side unipolar dual coil coupling mechanism, a primary side bipolar dual coil secondary side bipolar dual coil coupling mechanism, a primary side bipolar dual coil coupling mechanism. Bipolar dual coil secondary side unipolar single coil coupling mechanism, primary side unipolar dual coil secondary side unipolar dual coil coupling mechanism, primary side unipolar dual coil secondary side bipolar dual wire Coupling mechanism, primary side unipolar double coil secondary side unipolar single coil coupling mechanism.

Further preferably, the optimal coupling mechanism is the primary and secondary side coupling mechanism with the largest coupling coefficient of the offset distance of the primary and secondary side coils under different primary and secondary side coupling mechanisms.

Further preferably, the working mode of the primary and secondary side coils is controlled by controlling the direction and presence of current in the primary and secondary side coils, so that the wireless bidirectional power conversion topology is switched to different primary and secondary side coupling mechanisms.

Further preferably, when current is input to both the first polarity coil and the second polarity coil of the primary side or the secondary side, if the currents are in the same phase, the primary side coil or the secondary side coil works in the unipolar mode, and if the currents are in the opposite phase. , the primary coil or the secondary coil works in bipolar mode. Further, by controlling the presence or absence of current, the primary and secondary coils can be operated in a single-coil or dual-coil mode, thereby selecting the coupling number of the primary and secondary coils. Further, the single coil can only work in unipolar mode, and the double coil can work in unipolar or bipolar mode.

Through the above technical scheme conceived by the present invention, compared with the prior art, the following beneficial effects can be achieved:

1. The present invention proposes a wireless bidirectional power conversion topology, which adopts a parallel dual input and dual output system architecture, and a primary and secondary side coupling module composed of coils with multiple working modes, which can make the magnetic coupling mechanism not perfect. Alignment, when there is an offset distance, select the best primary and secondary side coupling mechanism for coupling, so as to effectively perform charging, the structure is simple and easy to implement, no additional control system is added, and no complex coupling mechanism is used. It solves the problem of poor offset resistance when the magnetic coupling mechanism is not perfectly aligned due to the fact that the magnetic coupling mechanism needs to be perfectly aligned to be effectively charged in the prior art.

2. The present invention proposes a control method for a wireless bidirectional power conversion topology. By selecting the direction of the current in the two series-connected first unipolar coils and second unipolar coils in the primary and secondary coils, the The primary and secondary coils work in unipolar and bipolar modes, and by selecting the number of secondary coils coupled, the secondary coils can work in single-coil or dual-coil mode, and by controlling the primary and secondary coils to work in different The mode can flexibly switch the primary and secondary side coupling mechanisms. Further, the primary and secondary side coupling mechanisms with the largest coupling coefficient of the offset distance of the primary and secondary side coils under different primary and secondary side coupling mechanisms are selected as the optimal coupling mechanism, which improves the original and secondary side coupling mechanism. Energy transfer efficiency and system stability when the side and secondary coils are offset.

3. The wireless bidirectional power conversion topology proposed by the present invention adopts the combination of LCC-S and S-LCC as a hybrid compensation network. The reduction of the mutual inductance reduces the output power. By selecting the correct coupling mechanism self-inductance and mutual inductance parameters, the influence of the increase or decrease of the main mutual inductance can be offset, and the output power can be kept relatively constant within a certain range.

Description of drawings

1 is a schematic diagram of a wireless bidirectional power conversion topology provided by the present invention;

2 is a schematic structural diagram of the primary coil provided by the present invention operating in a bipolar dual coil mode;

3 is a schematic diagram of the magnetic field generated by the primary coil provided by the present invention operating in a bipolar dual coil mode;

4 is a schematic structural diagram of the primary coil provided by the present invention operating in a unipolar dual coil mode;

5 is a schematic diagram of the magnetic field generated by the primary coil provided by the present invention operating in a unipolar dual coil mode;

6 is a schematic structural diagram of the secondary coil provided by the present invention operating in a unipolar single coil mode;

7 is a schematic diagram of the finite element structure of the primary and secondary side coils provided by the present invention;

FIG. 8 is a relationship curve between the offset distance of the primary and secondary side coils and the coupling coefficient under different primary and secondary side coupling mechanisms provided by the present invention.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

In order to achieve the above purpose, the present invention provides a wireless two-way power conversion topology, as shown in FIG. 1 , including a primary side sending module 1, a primary side coupling module 2, and a secondary side receiving module 3; wherein, the primary side sending module and The secondary side receiving module is symmetrical about the primary side and the secondary side coupling module, the primary side sending module is coupled to the secondary side receiving module through the primary side side coupling module, the output end of the primary side side sending module is connected with the input end of the primary side coil coupling module, The output end of the primary and secondary side coil coupling module is connected with the secondary side receiving module;

The primary side sending module 1 is used to convert the direct current into the alternating current by adopting the parallel double input structure, and compensate the self-inductance and leakage inductance in the primary and secondary side coupling modules, and output the alternating current with stable power;

The primary and secondary side coupling module 2 is used to couple the primary side sending module and the secondary side receiving module through a controllable coupling mechanism based on the principle of electromagnetic induction, and transmit power wirelessly;

The secondary side receiving module 3 is used to convert the AC power with stable power after compensation into DC power by adopting a parallel dual output structure.

Specifically, the primary and secondary side coupling module 2 is composed of primary and secondary side coils. The primary side coil includes a primary side first unipolar coil L ₁ and a primary side second unipolar coil L ₃ ; The unipolar coil L ₂ and the second unipolar coil L ₄ on the secondary side; wherein, the first unipolar coil L ₁ on the primary side is connected in series with the second unipolar coil L ₃ on the primary side, and the first unipolar coil on the secondary side is connected in series. The coil L ₂ is connected in series with the secondary second unipolar coil L ₄ , wherein the mutual inductance between L ₁ and L ₃ is M ₁₃ , the mutual inductance between L ₁ and L ₄ is M ₁₄ , and the mutual inductance between L ₂ and L ₃ is M 14 . The mutual inductance between L ₃ and L ₄ is M ₃₄ , and the mutual inductance between L ₂ and L ₄ is _{M 24 .} Specifically, the primary and secondary coils all include a unipolar single coil working mode, a unipolar dual coil working mode, and a bipolar dual coil working mode. Specifically, the shape of the primary and secondary coils may be circular, rectangular, or the like. By adding a magnetic core to guide the magnetic flux and shape the magnetic field, the distribution range of the magnetic field around the magnetic coupling mechanism can be effectively reduced.

Specifically, the primary-side sending module includes a primary-side high-frequency full-bridge inverter circuit and a primary-side compensation network, and the secondary-side receiving module includes a secondary-side full-bridge rectification filter circuit and a secondary-side compensation network; wherein, the primary-side high-frequency full-bridge inverter circuit and the original side. The side compensation network is connected in series, and the secondary side full-bridge rectifier filter circuit is connected in series with the secondary side compensation network;

The primary side high-frequency full-bridge inverter circuit is used to adopt a parallel structure, combine the dual-input DC power through a common DC bus, and convert the DC power into AC power;

The primary side compensation network and the secondary side compensation network are composed of a hybrid compensation topology combining LCC-S topology and S-LCC topology, which are used to reduce the consumption of reactive power in the system, balance the influence of inductive reactance in the circuit, and further compensate for the coupling The influence of the misalignment of the mechanism prevents the coupling coefficient from dropping too fast and produces an approximately constant power output;

The secondary-side full-bridge rectifier and filter circuit is used to convert alternating current into dual-output direct-current by adopting a parallel structure, and the dual-output direct-current is combined and output through a common direct-current bus.

Specifically, the primary side high-frequency full-bridge inverter circuit includes a primary side first inverter circuit and a primary side second inverter circuit; wherein, the primary side first inverter circuit is connected in parallel with the primary side second inverter circuit, and the primary side first inverter circuit is connected in parallel with the primary side first inverter circuit. The inverter circuit is composed of switch tubes Q ₁ to Q ₄ , and the second inverter circuit of the primary side is composed of switch tubes Q ₅ to Q ₈ ; the primary side compensation network includes the primary side first compensation network and the primary side second compensation network; The first compensation network on the side includes the first compensation capacitor C _p1 on the primary side, forming an S compensation network, and the S compensation network plays a compensation role by resonating with the coil in series; the second compensation network on the primary side includes the second compensation inductance L _p1 on the primary side , the second series capacitor C _p2 on the primary side and the second parallel capacitor C _p3 on the primary side form an LCC compensation network. The LCC compensation network plays a compensation role by resonating with the coil in series. Specifically, one end of the first compensation capacitor C _p1 on the primary side is connected to the midpoint of a bridge arm of the first inverter circuit on the primary side, and the other end of the first compensation capacitor C _p1 on the primary side is connected to the first unipolar coil L on the primary side. ₁ is connected to form a resonant circuit; one end of the primary side second compensation inductance L _p1 is connected to the midpoint of a bridge arm of the primary side second inverter circuit, and the other end of the primary side second compensation inductance L _p1 is connected to the primary side second parallel capacitor C _p3 and one pole of the primary second series capacitor C _p2 are connected, the other pole of the primary second series capacitor C _p2 is connected to one end _of the primary second unipolar coil L3, and the primary second parallel capacitor C The other pole of _p3 is connected to the other end of the second unipolar coil L3 _on the primary side and the midpoint of the other bridge arm of the second inverter circuit on the primary side.

Specifically, the secondary-side full-bridge rectifier and filter circuit includes a secondary-side first inverter circuit and a secondary-side second inverter circuit; wherein the secondary-side first inverter circuit is connected in parallel with the secondary-side second inverter circuit, and the secondary-side first inverter circuit is connected in parallel. The inverter circuit is composed of switch tubes Q _s1 to Q _s4 , and the second inverter circuit of the secondary side is composed of switch tubes Q _s5 to Q _s8 ; the secondary side compensation network includes the secondary side first compensation network and the secondary side second compensation network; The first compensation network on the side includes the first compensation inductance L _s1 on the secondary side, the first series capacitor C _s1 on the secondary side, and the first parallel capacitor C _s2 on the secondary side, which together form an LCC compensation network. The LCC compensation network starts by resonating with the series coil. The second compensation network of the secondary side includes the second compensation capacitor C _s3 of the secondary side to form an S compensation network, and the S compensation network plays a compensation role by resonating with the series-connected coil. Specifically, one end of the secondary-side first compensation inductance L _s1 is connected to the midpoint of a bridge arm of the secondary-side first inverter circuit, and the other end of the secondary-side first compensation inductance L _s1 is connected to the secondary-side first parallel capacitor C _s2 and One pole of the first series capacitor C _s1 on the secondary side is connected, the other pole of the first series capacitor C _s1 on the secondary side is connected with one end of the first unipolar coil L ₂ on the secondary side, and the other pole of the first parallel capacitor C _s2 on the secondary side is connected with one end. One pole is connected to the other end of the first unipolar coil L ₂ on the secondary side and the midpoint of the other bridge arm of the first inverter circuit on the secondary side; one end of the second compensation capacitor C _s3 on the secondary side is connected to the second inverse The midpoint of a bridge arm of the transformer circuit is connected, and the other end of the second compensation capacitor C _s3 on the secondary side is connected with the second unipolar coil L ₄ on the secondary side to form a resonance circuit.

Specifically, the LCC-S topology includes a primary side LCC compensation network, a secondary side S compensation network, and the primary side second compensation network includes a primary side second compensation inductor L _p1 , the primary side second series capacitor C _p2 , the primary side first Two parallel capacitors C _p3 and secondary side second compensation capacitors C _s3 are formed. The S-LCC topology includes a primary S compensation network, a secondary LCC compensation network, a primary compensation capacitor C _p1 and a secondary compensation inductor L _s1 , a secondary first series capacitor C _s1 , and a secondary first compensation capacitor C s1 . A parallel capacitor C _{s2 is} formed. In the LCC-S topology, the output power increases as the mutual inductance decreases. Conversely, in the S-LCC topology, the output power decreases as the mutual inductance decreases. When coil misalignment occurs, the main couplings M ₁₂ and M ₃₄ will decrease, which results in a decrease in M ₃₄ /L _p1 and an increase in L _s1 /M ₁₂ . If the self-inductance and mutual inductance parameters of the coupling mechanism are selected correctly, the output power can be kept relatively constant within a certain range by canceling the effect of the increase or decrease of M ₁₂ and M ₃₄ . Specifically, when the position of the primary and secondary coils is shifted, the mutual inductance value is compensated to prevent the coupling coefficient from dropping too much, to ensure the constant output current, and to improve the energy transmission when the primary and secondary coils are shifted in position. Efficiency improves the electromagnetic environment when the transmitter coil and the receiver coil are shifted in position.

Another aspect of the present invention provides a method for controlling a wireless bidirectional power conversion topology, comprising the following steps:

S1. Convert the DC voltage input from the primary side to a high-frequency AC voltage;

S2. Establish a finite element model for the primary and secondary coils with offset, and obtain the relationship between the offset distance and the coupling coefficient of the primary and secondary coils under different primary and secondary coupling mechanisms;

S3. Obtain the high-frequency AC voltage. Based on the relationship between the offset distance of the primary and secondary coils and the coupling coefficient, according to the offset of the primary and secondary coils, the optimal primary and secondary side coupling mechanism is obtained, which is coupled to the secondary side through electromagnetic induction. side, output high frequency AC voltage;

S4. Convert the high-frequency AC voltage obtained by the secondary side into a DC voltage for output.

Specifically, the primary and secondary side coupling mechanisms include a primary side bipolar dual coil secondary side unipolar dual coil coupling mechanism, a primary side bipolar dual coil secondary side bipolar dual coil coupling mechanism, a primary side dual Polar double coil secondary side unipolar single coil coupling mechanism, primary side unipolar double coil secondary side unipolar double coil coupling mechanism, primary side unipolar double coil secondary side bipolar double coil Coupling mechanism, primary side unipolar double coil secondary side unipolar single coil coupling mechanism. Among them, since the wireless two-way power conversion topology is a symmetrical two-way topology, the primary side and the secondary side are only opposite, so the primary side bipolar dual coil secondary side unipolar dual coil coupling mechanism and the primary side unipolar dual coil coupling mechanism The coupling effect of the bipolar dual-coil coupling mechanism on the secondary side of the coil is the same. Further, the primary and secondary side coupling mechanisms are selected by controlling the primary and secondary side coils to work in different modes.

Specifically, the working mode of the primary and secondary side coils is controlled by controlling the direction and presence of current in the primary and secondary side coils, so that the wireless bidirectional power conversion topology is switched to different primary and secondary side coupling mechanisms. Specifically, by controlling the switching of the switch to control the direction and presence of the current in the coil, it is possible to switch to different primary and secondary side coupling mechanisms. Specifically, when currents are input to the first-polarity coil and the second-polarity coil of the primary or secondary side, if the currents are in the same phase, the primary or secondary coils work in unipolar mode, and if the currents are out of phase, Primary or secondary coils operate in bipolar mode. Further, by controlling the presence or absence of current, the primary and secondary coils can be operated in a single-coil or dual-coil mode, thereby selecting the coupling number of the primary and secondary coils. Further, the single coil can only work in unipolar mode, and the double coil can work in unipolar or bipolar mode.

Specifically, FIG. 2 is a schematic structural diagram of the primary coil provided by the present invention operating in a bipolar dual coil mode, wherein the arrows indicate the inflow direction of the current, and the _first polarity coils L1 and L1 on the primary side respectively A current in the opposite direction is passed through the second polarity coil L3 _of the primary side. At this time, the primary side coil works in a bipolar dual coil mode, and a schematic diagram of the generated magnetic field is shown in FIG. 3 . FIG. 4 is a schematic diagram of the structure of the primary coil provided by the present invention working in a unipolar dual coil mode, wherein the arrows indicate the inflow direction _of the current. The current in the same direction is passed into the bipolar coil L3. _At this time, the primary coil works in the unipolar dual coil mode, and the schematic diagram of the generated magnetic field is shown in FIG. 5 . Figure ₆ is a schematic diagram of the structure of the secondary coil provided by the present invention operating in a unipolar single coil mode, wherein the arrows indicate the inflow direction of the current, and the current is only passed into the secondary first polarity coil L2 , at this time the secondary coil works in the unipolar single coil mode.

Specifically, the finite element simulation is performed on the primary and secondary coils with offset to obtain the relationship between the offset distance and the coupling coefficient of the primary and secondary coils under different primary and secondary coupling mechanisms. Provided is a schematic diagram of the finite element structure of the primary and secondary coils, where the secondary coil is above the primary coil. In the embodiment of the present invention, the shape of the coil in the finite element model is set to be rectangular, the length of a single coil is 566mm, the width of 378mm, the operating frequency is set to 85KHz in the solution mode of the eddy current field, the transmission distance of the primary and secondary coils is 200mm, and a single coil turns Count 15 turns, the material is copper, the simulation environment is air, and the center point of the primary coil is used as the center point of the coordinate system to establish an xyz coordinate system, the z-axis is perpendicular to the primary and secondary coils, and the secondary coil is relative to the primary coil at x Offset in the direction. Set the offset range of the primary and secondary coils in the x-axis direction between -1m and 1m, where positive and negative represent the left/right offset of the secondary coil relative to the primary coil. Cut out an excitation add face for each coil and pass 20A of current. For the dual-coil mode, set the direction of the current flowing in each coil, and control the different connection modes of the in-phase and in-phase of the two coils, thereby switching the dual-coil to the unipolar and bipolar operating modes. By setting the presence or absence of the incoming current and the number of coils working, the relationship curve between the offset distance and the coupling coefficient of the primary and secondary coils under different primary and secondary side coupling mechanisms is obtained as shown in Figure 8, where the abscissa It represents the offset distance, and the ordinate represents the coupling coefficient. The larger the coupling coefficient, the better the coupling of the coil and the higher the charging efficiency.

Specifically, the optimal coupling mechanism is the primary and secondary side coupling mechanism with the largest coupling coefficient of the offset distance of the primary and secondary side coils under different primary and secondary side coupling mechanisms. The primary and secondary coupling mechanisms with the largest coupling coefficient corresponding to the current offset distance are selected as the optimal primary and secondary side coupling mechanisms. Specifically, within the offset distance where the coupling coefficient under the primary side unipolar double coil secondary side unipolar double coil coupling mechanism is greater than the coupling coefficient under other coupling mechanisms, a parallel inverter bridge is used to drive, control the primary side _A unipolar coil L1 is in phase with the currents _I1 and _I3 in the primary second unipolar coil L3, and the secondary _first unipolar coil L2 is in phase with the secondary _second unipolar coil L4 _. The currents I ₂ and I ₄ are in phase; within the offset distance where the coupling coefficient under the primary bipolar dual-coil secondary bipolar dual-coil coupling mechanism is greater than the coupling coefficient under other coupling mechanisms, a parallel inverter bridge is used. Drive, control the current I ₁ and I ₃ in the first unipolar coil L ₁ on the primary side and the second unipolar coil L ₃ on the primary side to be in reverse phase, and the first unipolar coil L ₂ on the secondary side and the second unipolar coil on the secondary side. The currents I ₂ and I ₄ in the unipolar coil L ₄ are out of phase; the coupling coefficient under the primary side unipolar double coil secondary side bipolar double coil coupling mechanism is greater than the offset of the coupling coefficient under other coupling mechanisms Within the distance, the parallel inverter bridge drive is used to control the currents _I1 and _I3 in the first unipolar coil L1 _on the primary side and the second unipolar coil L3 _on the primary side to be in phase, and the first unipolar coil on the secondary side is in phase. L ₂ is opposite to the currents I ₂ and I ₄ in the second unipolar coil L ₄ on the secondary side; under the primary side unipolar double coil secondary side unipolar single coil coupling mechanism, and the secondary side adopts the first unipolar coil The coupling coefficient of the polar coil is greater than the offset distance of the coupling coefficient of other coupling mechanisms, and the parallel inverter bridge is used to control the first unipolar coil L1 _on the primary side and the second unipolar coil L3 _on the primary side. The currents I ₁ and I ₃ are in the same phase, and the secondary side selects the first unipolar coil L ₂ to work; under the primary side unipolar double coil secondary side unipolar single coil coupling mechanism, and the secondary side adopts the second unipolar coil When the coupling coefficient of the sex coil is greater than the coupling coefficient of other coupling mechanisms, the parallel inverter bridge is used to control the first unipolar coil L1 _on the primary side and the second unipolar coil L3 _on the primary side. The currents I ₁ and I ₃ are in the same phase, and the secondary side selects the second unipolar coil L ₄ to work; under the primary side bipolar double coil secondary side unipolar single coil coupling mechanism, and the secondary side adopts the first unipolar coil The coupling coefficient of the coil is greater than the offset distance of the coupling coefficient of other coupling mechanisms, and the parallel inverter bridge is used to control the first unipolar coil L1 _on the primary side and the second unipolar coil L3 _on the primary side. The currents I ₁ and I ₃ are in reverse phase, and the secondary side selects the first unipolar coil L ₂ to work; under the primary side bipolar double coil secondary side unipolar single coil coupling mechanism, and the secondary side adopts the second unipolar coil The coupling coefficient of the coil is greater than the offset distance of the coupling coefficient of other coupling mechanisms, and the parallel inverter bridge is used to control the first unipolar coil L1 _on the primary side and the second unipolar coil L3 _on the primary side. The currents I ₁ and I ₃ are reversed, and the secondary side selects the second unipolar coil L ₄ to work.

Specifically, it can be seen from Fig. 8 that when the offset range of the primary and secondary coils in the x-axis direction is between -1m and 1m, when the offset distance is within the length range of -0.2m to 0.2m, the primary side is controlled _The currents _I1 and _I3 in the _first unipolar coil L1 and the primary second unipolar coil L3 are in opposite phases, and the secondary first unipolar coil L2 and the secondary _second unipolar coil L The currents I ₂ and I ₄ in ₄ are reversed, and the primary side bipolar dual coil secondary side bipolar dual coil coupling mechanism is selected. When the offset distance is in the range of -0.36m to -0.2m, the currents I ₁ and I ₃ in the first unipolar coil L ₁ of the primary side and the second unipolar coil L ₃ of the primary side are controlled to be in the same phase, The currents I ₂ and I ₄ in the first unipolar coil L ₂ on the secondary side and the second unipolar coil L ₄ on the secondary side are in reverse phase, and the primary side unipolar double coil is selected to couple with the secondary side bipolar double coil. mechanism. When the offset distance is in the range of -1m to -0.36m, the currents I ₁ and I ₃ in the first unipolar coil L ₁ of the primary side and the second unipolar coil L ₃ of the primary side are controlled to be in opposite phases, The currents I ₂ and I ₄ in the first unipolar coil L ₂ of the secondary side and the second unipolar coil L ₄ of the secondary side are in reverse phase, and the primary side bipolar double coil is selected to couple with the secondary side bipolar double coil. mechanism. When the offset distance is in the range of 0.2m to 0.36m, the currents I ₁ and I ₃ in the first unipolar coil L ₁ of the primary side and the second unipolar coil L ₃ of the primary side are controlled to be in phase, and the secondary side The first unipolar coil L ₂ and the currents I ₂ and I ₄ in the second unipolar coil L ₄ on the secondary side are in opposite phases, and the primary side unipolar dual coil secondary side bipolar dual coil coupling mechanism is selected. When the offset distance is in the range of 0.36m to 1m, the currents I ₁ and I ₃ in the first unipolar coil L ₁ of the primary side and the second unipolar coil L ₃ of the primary side are controlled to be in reverse phase, and the secondary side The currents I ₂ and I ₄ in the first unipolar coil L ₂ and the second unipolar coil L ₄ on the secondary side are in opposite phases, and the primary side bipolar dual coil secondary side bipolar dual coil coupling mechanism is selected. For wireless power transmission systems with different coupling mechanism sizes and different transmission distances, the value of the offset distance changes, and the corresponding primary and secondary side coupling mechanisms can be selected according to the corresponding maximum coupling coefficient.

The invention proposes a wireless two-way power conversion topology, selects the system architecture of parallel dual input and output, and combines LCC-S and S-LCC as a hybrid compensation network. By selecting the correct coupling mechanism self-inductance and mutual inductance parameters, the increase of the main mutual inductance can be offset. Or reduce the influence, when it is not perfectly aligned, the corresponding primary and secondary side coupling mechanisms can be selected according to the offset distance, so as to avoid the instability of the system caused by too much decrease in the coupling coefficient. In addition, the present invention also proposes a control method for this wireless bidirectional power conversion topology. By selecting the direction of the current flowing into the two series-connected coils, the coils can work in unipolar and bipolar operating modes. When the current is in phase, it works under the unipolar coupling mechanism, and when the current is in opposite phase, it works under the bipolar coupling mechanism. And by selecting the number of secondary coil couplings, the secondary coil can work in the single-coil or double-coil working mode, so that the best choice can be made according to the different anti-offset performance of the unipolar coil and the bipolar coil. switching range to avoid excessive drop in the coupling coefficient. According to the working modes of different coils, combined with the inherent characteristics of the compensation network topology, it can ensure the constant output current, improve the energy transmission efficiency and offset resistance when the transmitter coil and the receiver coil are offset, and the structure is simple and easy to implement, without adding extra The control system does not use complex coupling mechanisms.

Those skilled in the art can easily understand that the above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, etc., All should be included within the protection scope of the present invention.

Claims (6)

1. a wireless bidirectional power conversion topology circuit, is characterized in that, comprises primary side sending module, primary side coupling module and secondary side receiving module; The primary-side sending module and the secondary-side receiving module are centrally symmetric with respect to the primary-secondary-side coupling module, and the primary-side sending module is coupled to the secondary-side receiving module through the primary-secondary side coupling module, and the The output end of the primary side sending module is connected with the input end of the primary and secondary side coil coupling module, and the output end of the primary side coil coupling module is connected with the secondary side receiving module; The primary side sending module is used for converting direct current into alternating current by adopting a parallel dual input structure, and compensating for the self-inductance and leakage inductance in the primary and secondary side coupling modules, so as to output alternating current with stable power; The primary and secondary side coupling modules are used to couple the primary side sending module and the secondary side receiving module through a controllable coupling mechanism based on the principle of electromagnetic induction, and transmit power wirelessly; The secondary side receiving module is used for converting the alternating current with stable power after compensation into direct current by adopting a parallel dual output structure; The primary and secondary side coupling modules are composed of primary and secondary side coils. The primary side coils include a primary side first unipolar coil and a primary side second unipolar coil; the secondary side coils include a secondary side first unipolar coil and a secondary side coil. a second unipolar coil on the side; the first unipolar coil on the primary side is connected in series with the second unipolar coil on the primary side, and the first unipolar coil on the secondary side is connected in series with the second unipolar coil on the secondary side; The primary side coil includes a unipolar double coil working mode and a bipolar double coil working mode; the secondary coil includes a unipolar single coil working mode, a unipolar double coil working mode and a bipolar working mode Double coil working mode. 2 . The wireless bidirectional power conversion topology circuit according to claim 1 , wherein the primary side sending module comprises a primary side high-frequency full-bridge inverter circuit and a primary side compensation network; the secondary side receiving module comprises a secondary side full-bridge inverter circuit and a primary side compensation network. 3 . Bridge rectifier filter circuit and secondary side compensation network; The primary side high-frequency full-bridge inverter circuit is connected in series with the primary side compensation network, and the secondary side full-bridge rectifier filter circuit is connected in series with the secondary side compensation network; The primary-side high-frequency full-bridge inverter circuit is used for adopting a parallel structure, combining dual-input DC powers through a common DC bus, and converting the DC power into AC power; The primary side compensation network and the secondary side compensation network are composed of a hybrid compensation topology structure combining LCC-S topology and S-LCC topology, which are used to reduce the consumption of reactive power of the system, balance the influence of inductive reactance in the circuit, and further Ground compensation for the influence caused by the misalignment of the coupling mechanism, to avoid the coupling coefficient from falling too fast, resulting in an approximately constant power output; The secondary-side full-bridge rectifier and filter circuit is used to convert alternating current into dual-output direct-current by adopting a parallel structure, and the dual-output direct-current is combined and output through a common direct-current bus. 3 . The wireless bidirectional power conversion topology circuit according to claim 2 , wherein the primary side high-frequency full-bridge inverter circuit and the secondary side full-bridge rectifier filter circuit respectively comprise a first inverter circuit and a second inverter circuit. 4 . Inverter circuit; wherein, the first inverter circuit is connected in parallel with the second inverter circuit. 4. A wireless two-way power conversion topology control method, characterized in that, comprising the following steps: S1. Convert the DC voltage input from the primary side to a high-frequency AC voltage; S2. Establish a finite element model for the primary and secondary coils with offset, and obtain the relationship between the offset distance and the coupling coefficient of the primary and secondary coils under different primary and secondary coupling mechanisms; S3. Obtain the high-frequency AC voltage. Based on the relationship between the offset distance of the primary and secondary coils and the coupling coefficient, according to the offset of the primary and secondary coils, the optimal primary and secondary side coupling mechanism is obtained, which is coupled to the secondary side through electromagnetic induction. side, output high frequency AC voltage; S4. Convert the high-frequency AC voltage obtained by the secondary side into a DC voltage output; The primary and secondary side coupling mechanisms include primary side bipolar dual coil secondary side unipolar dual coil coupling mechanism, primary side bipolar dual coil secondary side bipolar dual coil coupling mechanism, primary side bipolar dual coil coupling mechanism. Dual-coil secondary unipolar single-coil coupling mechanism, primary unipolar dual-coil secondary unipolar dual-coil coupling mechanism, primary unipolar dual-coil secondary bipolar dual-coil coupling The mechanism and the primary side unipolar double coil secondary side unipolar single coil coupling mechanism. 5 . The wireless bidirectional power conversion topology control method according to claim 4 , wherein the optimal primary and secondary side coupling mechanism is that the offset distance of the primary and secondary side coils has the largest coupling coefficient under different primary and secondary side coupling mechanisms. 6 . The primary and secondary side coupling mechanism. 6 . The wireless bidirectional power conversion topology control method according to claim 4 , wherein the working mode of the primary and secondary coils is controlled by controlling the direction and presence of current in the primary and secondary coils, so that the wireless bidirectional The power conversion topology is switched to different primary and secondary side coupling mechanisms.

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