WPT system based on shielded capacitor plate data transmission and data parallel transmission method thereof

Abstract

The invention discloses a shielded capacitor plate data transmission-based WPT system and a data parallel transmission method thereof.According to the shielded capacitor plate data transmission-based WPT system and the data parallel transmission method thereof, an inductor and a shielded capacitor plate mixed data energy separation type channel is used for transmission, and due to the fact that an independent data transmission channel exists, modulation and demodulation do not need to be carried out on a carrier wave of electric energy transmission; the problem that electric energy modulation type constant-voltage and constant-current control is difficult is solved, and due to separated channel transmission, the signal crosstalk problem during parallel transmission of high-frequency data carrier energy signals is solved. Besides, the electromagnetic shielding plate is reasonably utilized, no extra shielding isolation circuit needs to be added, the cost and the space are greatly reduced, the impedance characteristic of the circuit is utilized, interference of electric energy to signals is reduced, the complexity of a channel is reduced, and the reliability of data transmission is improved. And the existence of the signal channel does not influence the transmission power of the system.

Description

Technical Field

[0001] The present invention belongs to the technical field of power electronics, and in particular relates to a WPT system based on shielded capacitor plate data transmission and a data parallel transmission method thereof. Background Art

[0002] As the power and frequency of wireless power transmission systems increase, in order to improve the power transmission efficiency and the anti-interference ability of the system, the power transmitter and receiver of wireless power transmission need to interact with each other in real time. Currently, there are several common ways to share channel energy data in parallel:

[0003] 1. The energy data parallel transmission method of power modulation modulates the voltage amplitude of the power sending end according to the different digital signals to be transmitted, and finally realizes the demodulation of the digital signal by detecting the output voltage amplitude at the pickup end. Since the signal is directly modulated in the power channel, constant voltage and constant current control are more difficult, and it is difficult to ensure the integrity of the signal during the constant voltage and constant current control process.

[0004] Second, based on the high-frequency data carrier, the shared channel energy data parallel transmission adopts frequency division multiplexing to inject the modulated signal into the public channel, uses the fundamental component to transmit electric energy, and the high-order component to transmit data. The high-frequency carrier and electric energy are transmitted simultaneously through the same coupling mechanism. The signal transmission rate is relatively high, but when the selected harmonic is designed to be zero or a certain value by changing the duty cycle or phase shift angle of the inverter, other harmonics still exist, which has a significant impact on signal extraction and further increases the difficulty of demodulation.

[0005] 3. Separate channel energy and data parallel transmission of multiple inductor channels. Since the separate channel needs to add additional inductor coils to transmit signals, it physically reduces the crosstalk between power and signals. However, the increase in cost and space caused by adding coils limits its application scenarios. In addition, when two independent coils receive power and data signals respectively, cross-coupling between the power and data receiving coils may cause certain crosstalk.

[0006] The above-mentioned common shared channel energy data parallel transmission only needs one channel to transmit power and signals, and the signal transmission rate is relatively high, but the crosstalk problem of power transmission on signal transmission is difficult to solve. It is necessary to add additional isolation circuits and adopt control algorithms to solve the crosstalk problem, which increases the circuit complexity and design difficulty. The separated channel energy data parallel transmission physically reduces the crosstalk between power and signals, but the additional data channel increases the cost of the system.

[0007] In the prior art, data is modulated and transmitted through the high-frequency electric field generated by the parasitic capacitance of the coupling coil and the metal shielding plate, while power is transmitted through the relatively low-frequency magnetic field generated by the coupling coil. Compared with the traditional method, this method does not require an additional coil, and because power is transmitted through the magnetic field and data through the electric field, the bandpass filter is easy to design. Experimental results show that the data transmission channel has almost no effect on power transmission, and has the advantages of good flexibility and large spatial position offset redundancy.

[0008] However, the data transmission link of the prior art is constructed by the parasitic capacitance of the aluminum plate and the coil. In this case, the multiplexing of the coil inductance and capacitance characteristics makes the power and data transmission channels not completely decoupled, and the data passes through part of the power transmission circuit, which inevitably leads to complex parameter design and relatively low signal quality. In terms of foreign body detection, when a metal foreign body appears in the energy transmission channel, although it will not affect the signal transmission of the aluminum plate electric field, it will still affect the parasitic capacitance of the inductor coil to a certain extent. The load is disturbed by the voltage of the foreign body and cannot be quickly fed back to the transmitting end by the coupled electric field signal channel generated by the parasitic capacitance of the aluminum plate and the coil. It is necessary to add a detection device to the primary and secondary sides of the coil inductance to decide whether to stop the power transmission. The detection speed is slow, and in an emergency, the inverter cannot be stopped immediately. In addition, in an emergency, such as when the coil is burned, an alarm message should be sent immediately to stop the power transmission, which is a difficult to solve disadvantage for the data transmission method that relies on the coil. Summary of the invention

[0009] To solve the above problems, the present invention provides a WPT system based on shielded capacitor plate data transmission and a data parallel transmission method thereof. In order to reduce the cost and the mutual crosstalk between power transmission and signal transmission and the complexity of the signal channel, the present invention proposes a two-way data transmission based on a shielded capacitor plate that makes reasonable use of the electromagnetic shielding plate, does not need to add an additional shielding isolation circuit, greatly reduces the cost and space, uses the circuit's own impedance characteristics, reduces the interference of power on the signal, reduces the complexity of the channel, and ensures that the existence of the signal channel does not affect the system transmission power.

[0010] To achieve the above object, the present invention is implemented according to the following technical solutions:

[0011] The invention provides a WPT system based on data transmission of a shielded capacitor plate. The system adds a signal transmission path using a shielded capacitor plate to an original WPT system that uses a coupling coil to transmit energy. The WPT system includes two channels for power transmission and signal transmission, wherein the signal transmission channel uses a four-resonance double suppression structure to realize dual full-duplex communication, and two data carriers are transmitted through an equivalent SS compensation structure formed by a parallel LC resonant network and a serial LC resonant network. The parallel LC resonant network is used to block one carrier while transmitting another carrier, and the serial LC resonant network is used to compensate for circuit reactive power and improve the transmission power of the capacitor plate. Positive and negative signals are injected into the shielded capacitor plate through a wave blocking resonant network and a resonant inductor, forming a high-frequency alternating potential difference on the coupling plates of the primary / secondary sides, generating a high-frequency electric field and exciting an alternating voltage on the primary / secondary side plates to form an interactive electric field. Under the action of the interactive electric field, a displacement current is generated to "flow through" the plate, and the two data carriers are transmitted to the primary / secondary side receiving shielded capacitor plate of the WPT system.

[0012] In one embodiment, the power transmission channel is specifically: the input DC power supply Vin passes through a full-bridge inverter circuit composed of four switch tubes to generate a sine wave with a frequency of ω0, and the power transmission part adopts an equivalent SS compensation structure, C P and C S is the primary transmitting coil L P and the secondary receiving coil L S The compensation capacitor is used to eliminate the self-inductance of the coil. The secondary side of the power transmission is rectified by diodes D1~D4 to form a load R L powered by;

[0013] The signal transmission channel is specifically:

[0014] In order to perform full-duplex transmission of signals, two signal source analog signal inputs U1 and U2 are set on the primary side and the secondary side of the signal transmission circuit respectively. The forward digital signal Date1 in and the reverse digital signal Date2in are modulated with a sine wave of a specified frequency through ASK modulation, and then injected into the signal transmission channel by a power amplifier;

[0015] The primary transmitting coil Lp and the secondary receiving coil Ls are located on the inner side of the shielding capacitor plate. S1 , C S2 is the equivalent mutual capacitance of the shielding capacitor plates, C P12 With C P34 are the equivalent self-capacitances of the transmitting and receiving ends of the shielding capacitor plates, respectively;

[0016] In order to demodulate the forward and reverse signals, the sinusoidal carriers of the forward and reverse signals are located in different frequency bands. The carrier frequency of the forward signal is set to ω1, and the carrier frequency of the reverse signal is set to ω2.

[0017] The forward signal is injected into the primary shielding capacitor plate through the wave-blocking resonant network L1, C1 and the primary resonant inductor Lpp, and the secondary side receives the shielding capacitor plate and then obtains the signal waveform at the sampling resistor R2 through the secondary resonant inductor Lss and the wave-blocking resonant network L3, C3; after the signal waveform is sampled from R2, it is rectified by half-wave to become a signal waveform containing only the positive half axis, and the noise outside the passband is filtered out by the RC filter, and the waveform after filtering is amplified by the operational amplifier and sent to the envelope detection, and the detected envelope signal is compared with the given value to obtain a digital signal;

[0018] The reverse signal is injected into the secondary shielding capacitor plate through the L4, C4 wave-blocking network and the secondary resonant inductor Lss, and then transmitted to the primary shielding capacitor plate through the displacement current, and transmitted to the sampling resistor R1 through the primary resonant inductor Lpp and the wave-blocking resonant network L2, C2 to obtain the signal waveform. After the signal waveform is sampled from R1, it is rectified by half-wave to form a signal waveform containing only the positive half axis. The noise outside the passband is filtered out by the RC filter, and the filtered waveform is amplified by the operational amplifier and sent to the envelope detection. The detected envelope signal is compared with the given value to obtain a digital signal.

[0019] In one embodiment, the primary transmitting coil Lp and the secondary receiving coil Ls and their compensation capacitor C P With C S The following formula needs to be satisfied:

[0020]

[0021] Wherein, ω0 is the angular frequency of the sine wave generated by the full-bridge inverter circuit composed of four switch tubes through the input DC power supply Vin; f0 is the frequency corresponding to the angular frequency ω0; L P is the inductance of the primary transmitting coil, C P is the capacitance of the primary compensation capacitor; L S is the inductance of the secondary transmitting and receiving coil, C S is the capacitance of the secondary side compensation capacitor.

[0022] In one implementation, the topological structure of the shielding capacitor plate adopts a parallel disk coupling structure, specifically:

[0023] The topological structure of the shielding capacitor plate transmitting end P1, P2 and receiving end P3, P4 adopts a parallel disk coupling structure. S1 is the equivalent mutual capacitance between P1 and P3, C S2 is the equivalent mutual capacitance between P2 and P4, C P12 With C P34 are the equivalent self-capacitances of the transmitting and receiving ends of the parallel capacitor plates, respectively.

[0024] In one embodiment, the geometric parameters of the WPT system include the sizes of the coil and the metal shielding plate. After the coil is determined, the size of the metal shielding plate is obtained by finite element analysis of the optimization function in ANSYS software.

[0025] In one embodiment, when the radius of the primary transmitting coil and the secondary receiving coil is R=57 mm, when the outer radius of the inner capacitor plate is R1=40.5 mm, the radius of the outer capacitor plate is R2=72.3 mm, and the difference between the inner diameter of the outer capacitor plate and the radius of the inner capacitor plate is lg=1 mm, the parasitic capacitance difference between the coil and the plate is almost zero, that is, the primary transmitting coil L P The parasitic capacitance between the shielding capacitor plates P3 (outer capacitor plate) and P4 (inner capacitor plate) of the secondary side is the same as that between the secondary side receiving coil L S It is the same as the parasitic capacitance between the shielding capacitor plates P1 (outer capacitor plate) and P2 (inner capacitor plate) on the primary side.

[0026] In one embodiment, the parallel LC resonant network is composed of four groups of parallel resonant networks, which are respectively composed of a parallel network of a resonant inductor L1 and a resonant capacitor C1, a parallel network of a resonant inductor L2 and a resonant capacitor C2, a parallel network of a resonant inductor L3 and a resonant capacitor C3, and a parallel network of a resonant inductor L4 and a resonant capacitor C4; the L1C1 parallel network and the L3C3 parallel network are at the same resonant frequency, and the L2C2 parallel network and the L4C4 parallel network are at the same resonant frequency; that is, the resonance point of the forward LC network is exactly the suppression point of the reverse LC network; the serial LC resonant network is composed of a compensation inductor L PP and L SS and coupling plate C S1 With C S2 Through the equivalent SS compensation structure, two signal sources can be applied to the WPT system at the same time, thus achieving full-duplex communication.

[0027] In one implementation, the frequency setting method of the forward signal carrier frequency and the reverse signal carrier frequency is as follows:

[0028] Set the forward transmission carrier frequency to ω1 and the reverse transmission carrier frequency to ω2, adjust the resonance point at the ω1 frequency to the suppression point (maximum impedance) at the ω2 frequency, and adjust the resonance point at the ω2 frequency to the suppression point at the ω1 frequency, so that one resonance point of one LC resonant network is exactly the suppression point of another LC resonant network.

[0029] In one implementation, the selection process of the equivalent SS compensation structure is as follows:

[0030] The full-duplex communication channel topology is equivalent to the CPT system circuit structure with equivalent SS compensation, and the input impedance is derived;

[0031] When the system is in a resonant state and the input impedance Zin is purely resistive, set the constraints that the compensation inductors L1 and L2 need to meet;

[0032] Set the frequencies of the forward signal carrier and the reverse signal carrier, adjust the resonance point at the ω1 frequency to the suppression point at the ω2 frequency (maximum impedance), and adjust the resonance point at the ω2 frequency to the suppression point at the ω1 frequency, that is, the resonance point of the forward LC resonance network is exactly the suppression point of the reverse LC resonance network;

[0033] The L1, C1 network and the L3, C3 network need to be connected in parallel resonance at the reverse carrier frequency ω2;

[0034] The L2, C2 network and the L4, C4 network need to be connected in parallel resonance at the forward carrier frequency ω1;

[0035] When transmitting forward signals, simplify the signal transmission network:

[0036] Connect the resonant network L1, C1 and the compensation inductor L pp Equivalent to the equivalent inductance L eq1 ;

[0037] Connect the resonant network L3, C3 and the compensation inductor L ss Equivalent to the equivalent inductance L eq2 ;

[0038] When L eq1 Inductance and L eq2 When the inductance value satisfies the constraints of L1 and L2, the system is in resonance;

[0039] The reverse signal transmission is similar, simplifying the signal transmission network:

[0040] Connect the resonant network L2, C2 and the compensation inductor L pp Equivalent to the equivalent inductance L eq3 ,

[0041] Connect the resonant network L4, C4 and the compensation inductor L ss Equivalent to the equivalent inductance L eq4 ;

[0042] When L eq3 Inductance and L eq4 When the inductance value meets the constraints of L1 and L2, the system is in a resonant state. The resonant network L1, C1, L3, C3, L2, C2, L4, C4 and L are designed accordingly. pp With L ss The numerical value of .

[0043] The present invention also provides a data parallel transmission method of a WPT system based on shielded capacitor plate data transmission, the method comprising: using ASK (Radial Shift Keying) to change the carrier amplitude according to different digital signals, converting the 01 digital signal sent by the host computer into an analog signal with voltage through a DA conversion module, and then using ASK modulation to modulate it with a sinusoidal carrier of a rated frequency, when the analog signal is a high voltage, the ASK modulation output carrier amplitude is A1 representing a digital signal 1, and when the analog signal is a low voltage, the ASK modulation module outputs a carrier amplitude of A0 representing a digital signal 0, thereby realizing signal modulation; and then achieving signal carrier outputs of different amplitudes after passing through a proportional amplification circuit;

[0044] On the receiving side, the modulated carrier is obtained by half-wave rectification and then by RC filter. The envelope wave of the carrier signal is obtained by non-coherent envelope detection to achieve demodulation of the carrier signal.

[0045] Finally, the envelope wave is compared with a given voltage signal through a comparator. When the envelope wave is greater than the comparison voltage, the comparator outputs 1, and when it is less than the comparison voltage, the comparator outputs 0. At this point, the analog signal is converted into a digital signal.

[0046] In one implementation, the process of acquiring a carrier signal by envelope wave demodulation includes:

[0047] The input carrier passes through a detection diode to obtain a positive half-cycle waveform, and through an RC parallel network, the charge and discharge constant τ is adjusted by changing the values ​​of the resistor R and the capacitor C to obtain a waveform carrier signal. The design of the RC parameters needs to meet two conditions: first, it should be ensured that the discharge speed of the capacitor C is slower than the drop speed of the single-cycle carrier voltage; second, the capacitor discharge time should be shorter than half of the time occupied by a digital signal in the carrier.

[0048] Beneficial effects of the present invention:

[0049] The present invention adopts a data energy separation channel transmission mixed with an inductor and a shielded capacitor plate. Due to the existence of an independent data transmission channel, there is no need to modulate and demodulate the carrier of the electric energy transmission, which solves the problem of difficult constant voltage and constant current control of electric energy modulation. Due to the separated channel transmission, the signal crosstalk problem during parallel transmission of high-frequency data carrier energy signals is solved. Since an electromagnetic shielding metal plate is used as a capacitor path for signal transmission, there is no need to add additional inductance, which solves the problems of high cost and large space of multi-inductor separation channel type. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The accompanying drawings are part of the present invention and are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but do not constitute an improper limitation of the present invention. Obviously, the accompanying drawings described below are only some embodiments. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

[0051] Figure 1 A schematic diagram of a WPT system based on shielded capacitor plate data transmission provided in accordance with an embodiment of the invention;

[0052] Figure 2 A diagram of a parallel disc coupling structure provided in an embodiment of the present invention;

[0053] Figure 3 A metal cross-section design diagram provided in an embodiment of the present invention;

[0054] Figure 4 An electric field strength analysis diagram provided in an embodiment of the invention;

[0055] Figure 5 A model diagram of a coupling mechanism provided in an embodiment of the invention;

[0056] Figure 6 A topological diagram of a full-duplex communication channel provided in an embodiment of the invention;

[0057] Figure 7 A circuit structure diagram of a CPT system with SS compensation provided in an embodiment of the invention;

[0058] Figure 8 A dual-channel frequency characteristic curve provided in an embodiment of the invention;

[0059] Fig. 9 An equivalent circuit model of forward signal transmission provided in an embodiment of the invention;

[0060] Fig.10 An equivalent circuit model of reverse signal transmission provided in an embodiment of the invention;

[0061] Fig.11 A signal carrier waveform diagram after ASK modulation provided in an embodiment of the invention;

[0062] Fig.12 A schematic diagram of the envelope detection provided in an embodiment of the invention;

[0063] Fig.13 A simulation circuit model diagram provided in an embodiment of the invention;

[0064] Fig.14 A bidirectional signal transmission waveform diagram provided in an embodiment of the invention;

[0065] Fig.15 A signal diagram of signal transmission and sampling resistance provided in an embodiment of the invention;

[0066] Fig.16 A signal diagram of half-wave rectification and RC filtering provided in an embodiment of the invention;

[0067] Fig.17 It is a signal diagram of envelope detection and comparator output provided in an embodiment of the invention.

[0068] It should be noted that these drawings and textual descriptions are not intended to limit the conceptual scope of the present invention in any way, but are intended to illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0069] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0070] The following is an explanation of the nouns mentioned above.

[0071] WPT system: Wireless power transfer (WPT) refers to the energy transmission between the transmitting and receiving units. It generally uses inductor coils or capacitor substrates to replace traditional transmission lines to complete wireless power transmission within a certain distance.

[0072] ECPT system: Electric-field Coupled Power Transfer (ECPT) is a wireless energy transmission technology that uses metal plates as coupling mechanisms and high-frequency electric fields as energy transmission media.

[0073] ICPT system: Inductive Coupled Power Transfer (ICPT) transfers energy from a transmitter to another receiver through the principle of electromagnetic induction. It is based on Faraday's law of electromagnetic induction and uses a changing magnetic field to generate current between two electromagnetic induction coils to achieve energy transmission.

[0074] Shielded capacitor plates: Since the wireless power transmission system will generate a large magnetic field and electric field leakage, which may cause harm to biological organisms, it is necessary to add a shielding layer at both ends of the power transmission coil. The shielding layer is generally a metal plate and can be regarded as a capacitor.

[0075] Crosstalk: Noise caused by mutual inductance and mutual capacitance between two transmission lines when energy and signal are transmitted simultaneously.

[0076] The embodiment of the present invention provides a WPT system based on shielded capacitor plate data transmission, referring to Figure 1 As shown, the system adds a signal transmission path using a shielded capacitor plate to the original WPT system that uses a coupling coil to transfer energy; the WPT system includes two channels for power transmission and signal transmission, wherein the signal transmission channel uses a four-resonance dual suppression structure to achieve dual full-duplex communication, and two data carriers are transmitted through an equivalent SS compensation structure formed by a parallel LC resonant network and a serial LC resonant network; the parallel LC resonant network is used to block one carrier while transmitting another carrier, and the serial LC resonant network is used to compensate for the circuit reactive power and improve the transmission power of the capacitor plate; the positive and negative signals are injected into the shielded capacitor plate through the wave blocking resonant network and the resonant inductor, forming a high-frequency alternating potential difference on the coupling plates of the primary / secondary side, generating a high-frequency electric field and exciting an alternating voltage on the primary / secondary side plates to form an interactive electric field; under the action of the interactive electric field, a displacement current is generated that "flows through" the plate, and the two data carriers are transmitted to the primary / secondary side receiving shielded capacitor plate of the WPT system.

[0077] Continue to refer to Figure 1 As shown in the figure, the system is divided into two channels: power transmission and signal transmission. In the power transmission channel, the input DC power supply Vin passes through a full-bridge inverter circuit composed of four switch tubes to generate a sine wave with a frequency of ω0. In order to intuitively describe the transmission mechanism of the signal part, the power transmission part only adopts the SS compensation structure, C P and C S is the primary transmitting coil L P and the secondary receiving coil L S The compensation capacitor is used to eliminate the self-inductance of the coil, so that the compensation network and the coil work in a resonant state, which can reduce the reactive power of the coil and improve the transmission efficiency of the system. The secondary side of the power transmission is uncontrolled rectified by diodes D1~D4 to form a load R L powered by.

[0078] In the signal transmission channel, in order to perform full-duplex transmission of signals, two signal source analog signal inputs U1 and U2 are set on the primary and secondary sides of the signal transmission circuit respectively. The forward digital signal Date1 in and the reverse digital signal Date2in are modulated with a sine wave of a specified frequency through the ASK modulation method, and then injected into the signal transmission channel by the power amplifier;

[0079] The primary transmitting coil Lp and the secondary receiving coil Ls are located on the inner side of the shielding capacitor plate. S1 , C S2is the equivalent mutual capacitance of the shielding capacitor plates, C P12 With C P34 are the equivalent self-capacitances of the transmitting and receiving ends of the shielding capacitor plates, respectively;

[0080] In order to demodulate the forward and reverse signals, the sinusoidal carriers of the forward and reverse signals need to be in different frequency bands. The carrier frequency of the forward signal is set to ω1, and the carrier frequency of the reverse signal is set to ω2.

[0081] The forward signal is injected into the primary shielding capacitor plate through the wave-blocking resonant network L1, C1 and the primary resonant inductor Lpp, and a high-frequency alternating potential difference is formed on the coupling plate of the primary side. The potential difference excites the generation of a high-frequency electric field and excites an alternating voltage on the secondary plate to form an interactive electric field. Under the action of the interactive electric field, a displacement current is generated that "flows through" the plate, and the two data carriers are transmitted to the secondary receiving shielding capacitor plate of the system; the secondary receiving shielding capacitor plate then obtains a signal waveform through the secondary resonant inductor Lss and the wave-blocking resonant network L3, C3 at the sampling resistor R2; after the signal waveform is sampled from R2, it is rectified by half-wave into a signal waveform containing only the positive half axis, the noise outside the passband is filtered out by an RC filter, the waveform after filtering is amplified by an operational amplifier and sent to the envelope detector, and the detected envelope signal is compared with a given value to obtain a digital signal;

[0082] The reverse signal is transmitted in the same way. The reverse signal is injected into the secondary shielding capacitor plate through the L4, C4 wave-blocking network and the secondary resonant inductor Lss, and then the signal is transmitted to the primary shielding capacitor plate through the displacement current, and then transmitted to the sampling resistor R1 through the primary resonant inductor Lpp and the wave-blocking resonant network L2, C2. The signal waveform sampled by R1 is output as a complete digital signal through half-wave rectification, RC filtering, operational amplifier, envelope detection, and comparator.

[0083] Furthermore, the primary transmitting coil Lp and the secondary receiving coil Ls and their compensation capacitor C P With C S The following formula needs to be satisfied:

[0084]

[0085] Wherein, ω0 is the angular frequency of the sine wave generated by the full-bridge inverter circuit composed of four switch tubes through the input DC power supply Vin; f0 is the frequency corresponding to the angular frequency ω0; L P is the inductance of the primary transmitting coil, C P is the capacitance of the primary compensation capacitor; L S is the inductance of the secondary transmitting and receiving coil, C S is the capacitance of the secondary side compensation capacitor.

[0086] Furthermore, the topological structure of the shielding capacitor plate adopts a parallel disk coupling structure, specifically:

[0087] The topological structure of the shielding capacitor plate transmitting end P1, P2 and the receiving end P3, P4 adopts a parallel disk coupling structure, and the primary coil Lp and the secondary coil Ls are located on the inner side of the plate, such as Figure 2 As shown, C S1 is the equivalent mutual capacitance between P1 and P3, C S2 is the equivalent mutual capacitance between P2 and P4, C P12 With C P34 are the equivalent self-capacitances of the transmitting and receiving ends of the parallel capacitor plates, respectively.

[0088] The size of parasitic capacitance in the data transmission channel is closely related to the size of the coupling structure. However, the geometric parameters of the existing WPT system, including the size of the coil and the metal shielding plate, are mainly determined when analyzing the power transmission channel and specific application scenarios. Therefore, the design of the metal plate division method is a key factor affecting the data transmission performance and magnetic shielding function.

[0089] In the ICPT system, due to electromagnetic shielding, metal obstacles will block the transmission of energy. In the ECPT system, the energy transmission is in the form of an alternating electric field. The energy transmission will not be blocked by metal obstacles, but the metal obstacles will be used as part of the coupling plate to complete the energy transmission. Therefore, the power transmission channel between the coupling plates will not affect its signal transmission capability, and there is no crosstalk between power and signal. At the same time, the electric field is basically confined to the coupling plates, and the electromagnetic interference in the system is greatly reduced.

[0090] Furthermore, the geometric parameters of the WPT system include the dimensions of the coil and the metal shielding plate. After the coil is determined, the dimensions of the metal shielding plate are obtained through finite element analysis using the optimization function in ANSYS software.

[0091] Metal cross section Figure 3 As shown, when the radius of the primary transmitting coil and the secondary receiving coil is R = 57mm, when the outer radius of the inner capacitor plate is R1 = 40.5mm, the radius of the outer capacitor plate is R2 = 72.3mm, and the difference between the inner diameter of the outer capacitor plate and the radius of the inner capacitor plate is lg = 1mm, the parasitic capacitance difference between the coil and the plate is almost zero, that is, the primary transmitting coil L P The parasitic capacitance between the shielding capacitor plates P3 (outer capacitor plate) and P4 (inner capacitor plate) of the secondary side is the same as that between the secondary side receiving coil L S The parasitic capacitance between the shielding capacitor plates P1 (outer capacitor plate) and P2 (inner capacitor plate) on the primary side is the same, which can significantly minimize the crosstalk between power and data transmission. At this time, the electric field strength in the 400mm×400mm area above the metal plate is analyzed as follows: Figure 4 As shown in Figure 2, the simulation coupling model is as follows: Figure 5 shown.

[0092] In the data transmission channel, two data carriers are transmitted through an equivalent SS compensation structure formed by a parallel LC resonant network and a serial LC resonant network. The parallel LC resonant network is composed of four groups of parallel resonant networks, namely, a parallel network of resonant inductor L1 and resonant capacitor C1, a parallel network of resonant inductor L2 and resonant capacitor C2, a parallel network of resonant inductor L3 and resonant capacitor C3, and a parallel network of resonant inductor L4 and resonant capacitor C4. The L1C1 parallel network and the L3C3 parallel network are at the same resonant frequency, and the L2C2 parallel network and the L4C4 parallel network are at the same resonant frequency; that is, the forward L C The resonance point of the network is exactly the suppression point of the reverse LC resonant network. The parallel LC resonant network is used to block the other carrier while transmitting one carrier. The compensation inductor L PP and L SS and coupling plate C S1 With C S2 Serial L C The resonant network is used to compensate the circuit reactive power and increase the transmission power of the capacitor plates.

[0093] By forming a high-frequency alternating potential difference on the coupling plate at the transmitting end, the potential difference excites the generation of a high-frequency electric field and excites an alternating voltage on the receiving plate, forming an interactive electric field. Under the action of the interactive electric field, a displacement current is generated that "flows" through the plate, transmitting the two data carriers to the receiving side of the system. Through the proposed topology, two signal sources can be applied to the system at the same time, thereby realizing full-duplex communication. Full-duplex communication does not require direction switching, so there is no time delay caused by the switching operation, which is very beneficial for applications that need to strictly consider communication delays. The full-duplex communication channel topology is as follows: Figure 6 shown.

[0094] Regarding the selection of the SS compensation network of the present invention, the above signal channel can be equivalent to Figure 7 , the selection process of the equivalent SS compensation structure is as follows:

[0095] The full-duplex communication channel topology is equivalent to the CPT system circuit structure with equivalent SS compensation, and the input impedance is derived;

[0096] When the system is in a resonant state and the input impedance Zin is purely resistive, set the constraints that the compensation inductors L1 and L2 need to meet;

[0097] Set the frequencies of the forward signal carrier and the reverse signal carrier, adjust the resonance point at the ω1 frequency to the suppression point at the ω2 frequency (maximum impedance), and adjust the resonance point at the ω2 frequency to the suppression point at the ω1 frequency, that is, the resonance point of the forward LC resonance network is exactly the suppression point of the reverse LC resonance network;

[0098] The L1, C1 network and the L3, C3 network need to be connected in parallel resonance at the reverse carrier frequency ω2;

[0099] The L2, C2 network and the L4, C4 network need to be connected in parallel resonance at the forward carrier frequency ω1;

[0100] When transmitting forward signals, simplify the signal transmission network:

[0101] Connect the resonant network L1, C1 and the compensation inductor L pp Equivalent to the equivalent inductance L eq1 ;

[0102] Connect the resonant network L3, C3 and the compensation inductor L ss Equivalent to the equivalent inductance L eq2 ;

[0103] When L eq1 Inductance and L eq2 When the inductance value satisfies the constraints of L1 and L2, the system is in resonance;

[0104] The reverse signal transmission is similar, simplifying the signal transmission network:

[0105] Connect the resonant network L2, C2 and the compensation inductor L pp Equivalent to the equivalent inductance L eq3 ,

[0106] Connect the resonant network L4, C4 and the compensation inductor L ss Equivalent to the equivalent inductance L eq4 ;

[0107] When L eq3 Inductance and L eq4 When the inductance value meets the constraints of L1 and L2, the system is in a resonant state. The resonant network L1, C1, L3, C3, L2, C2, L4, C4 and L are designed accordingly. pp With L ss The numerical value of .

[0108] Specifically, the full-duplex communication channel topology is equivalent to a CPT system circuit with equivalent SS compensation, C P12 and C P34 is the equivalent self-capacitance of the transmitter and receiver, C S is the equivalent mutual capacitance, where the input impedance Z can be obtained by derivation.in for:

[0109]

[0110] When the system is in resonance, the input impedance Z in For pure resistance, the compensation inductors L1 and L2 need to meet the following constraints:

[0111]

[0112] For signal transmission, the frequency of the forward signal carrier is different from that of the reverse signal carrier, so that the LC resonant network can block the carrier in the other direction while transmitting one carrier, thereby reducing the crosstalk between signals. The specific frequency design method is as follows:

[0113] Assume that the forward transmission carrier frequency is ω1 and the reverse transmission carrier frequency is ω2. The two carrier frequency responses are as follows: Figure 8 As shown, since the signal transmission channel is connected by a parallel LC resonant network and a series LC resonant network, there will be two resonance points at each frequency. In order to transmit two data carriers at the same time, the resonance point at the ω1 frequency is adjusted to the suppression point (maximum impedance) at the ω2 frequency, and the resonance point at the ω2 frequency is adjusted to the suppression point at the ω1 frequency, which means that one resonance point of one LC resonant network is exactly the suppression point of another LC resonant network.

[0114] The forward signal transmission channel of the above system consists of L2 / / C2, L PP , C S1 , C S2 , L SS , L4 / / C4, R2, and the reverse signal transmission channel is composed of L3 / / C3, L SS , C S1 , C S2 , L PP , L1 / / C1, R1, the relationship between frequency and L, C needs to satisfy:

[0115]

[0116] When the signal is transmitted in the forward direction, according to the superposition theorem, at the frequency of ω1, the modulation signal source U1 works alone, the signal source U2 and its series LC parallel network are regarded as open circuits, and the signal is sampled and demodulated through R2 to obtain a digital signal. At this time, the signal transmission equivalent circuit is as follows Fig. 9 As shown:

[0117] Where: L eq1 The primary compensation inductor L PP The equivalent inductance in series with the parallel network of L1C1,

[0118] L eq2 For the secondary side compensation inductor L SS Equivalent inductance in series with the parallel network of L3C3.

[0119]

[0120] When the signal is transmitted in the reverse direction, the modulation signal source U1 works alone at the frequency of ω2, and the signal source U2 and its series LC parallel network are regarded as open circuits. The signal is sampled and demodulated through R1 to obtain a digital signal. At this time, the signal transmission equivalent circuit is as follows Fig.10 As shown:

[0121] Where: L eq3 The primary compensation inductor L PP The equivalent inductance in series with the parallel network of L2C2,

[0122] L eq4 For the secondary side compensation inductor L SS Equivalent inductance in series with the parallel network of L4C4.

[0123]

[0124] Through the derivation of the above equivalent circuit model, the specific parameters of the topology of the wave-blocking network and the compensation structure can be designed.

[0125] Regarding signal generation, the modulation strategy of this design signal adopts the method of Radius Shift Keying (ASK), which changes the carrier amplitude according to the different digital signals. For binary digital signals, the carrier amplitude A1 represents the digital signal 1, and the carrier amplitude A2 represents the digital signal 0. The signal carrier waveform after ASK modulation is shown in the figure below: Fig.11 shown.

[0126] An embodiment of the present invention provides a data parallel transmission method of a WPT system based on shielded capacitor plate data transmission, the method comprising: using ASK (Radial Shift Keying) to change the carrier amplitude according to different digital signals, converting the 01 digital signal sent by the host computer into an analog signal with voltage through a DA conversion module, and then using ASK modulation to modulate it with a sinusoidal carrier of a rated frequency, when the analog signal is a high voltage, the ASK modulation output carrier amplitude is A1 representing a digital signal 1, and when the analog signal is a low voltage, the ASK modulation output carrier amplitude is A0 representing a digital signal 0, thereby realizing signal modulation; and then realizing signal carrier outputs of different amplitudes after passing through a proportional amplification circuit;

[0127] On the receiving side, the modulated carrier is obtained by half-wave rectification and then by RC filter. The envelope wave of the carrier signal is obtained by non-coherent envelope detection to achieve demodulation of the carrier signal.

[0128] Finally, the envelope wave is compared with a given voltage signal through a comparator. When the envelope wave is greater than the comparison voltage, the comparator outputs 1, and when it is less than the comparison voltage, the comparator outputs 0. At this point, the analog signal is converted into a digital signal.

[0129] Furthermore, the process of obtaining the carrier signal through envelope wave demodulation includes: the input carrier passes through a detection diode to obtain a positive half-cycle waveform, and through an RC parallel network, the charging and discharging constant τ is adjusted by changing the value of the resistor R and the capacitor C to obtain a waveform carrier signal. Among them, the design of the RC parameters needs to meet two conditions: first, it should be ensured that the discharge speed of the capacitor C is slower than the drop speed of the single-cycle carrier voltage; second, the capacitor discharge time should be shorter than half of the time occupied by a digital signal in the carrier. The principle of envelope detection refers to Fig.12 shown.

[0130] In order to analyze the impact of adding a signal loop on power transmission and verify the correctness of the theoretical analysis of power crosstalk and signal attenuation, the feasibility of the proposed method is demonstrated at the simulation level. A simulation model of the signal transmission path of the system is established on the Simulink platform of Matlab. Fig.13 The energy transmission part is composed of a full-bridge inverter circuit, a resonant network, a signal transmission loop and an equivalent load resistor, and the signal transmission circuit is mainly composed of an ASK signal transmitting module, a compensation network, a signal transmission loop and a signal receiving and demodulation module.

[0131] The digital signal selected in the simulation is a square wave, and the digital signal "1110101010110..." is sent continuously. The signal square wave in the simulation is 315MHz, which can achieve relatively fast text information transmission in serial communication. In the signal modulation part of the figure, the output waveform is determined by the digital signal. When the digital signal is 1, the output peak is 5V, and when the digital signal is 0, the output is 0V, realizing binary ASK modulation. The detection voltage is the voltage at both ends of the detection load. The signal receiving part is half-wave rectification, RC filtering, envelope detection and comparator output waveform from left to right. Among them, the bidirectional signal transmission waveform is as follows Fig.14 As shown, the signal transmission and the signal sampling resistor are as follows Fig.15 As shown, the signal after half-wave rectification and RC filtering is as follows Fig.16 As shown, the received signal after envelope detection and comparator output is as follows Fig.17 As shown in the simulation results, it can be seen that the comparator output waveform follows the modulation output, completing the forward and reverse transmission of the signal, verifying that the system has good transmission characteristics.

[0132] In the description provided herein, a large number of specific details are described. However, it is understood that embodiments of the present invention can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this description.

[0133] In addition, those skilled in the art will understand that, although some embodiments described herein include certain features included in other embodiments but not other features, the combination of features of different embodiments also means being within the scope of protection of the present invention and forming different embodiments. For example, in the above embodiments, those skilled in the art can use them in combination according to the known technical solutions and the technical problems to be solved by this application.

Claims

1. A WPT system based on shielded capacitor plate data transmission, characterized in that: The system adds a signal transmission path using a shielded capacitor plate to the original WPT system that uses a coupling coil to transfer energy; the WPT system includes two channels for power transmission and signal transmission, wherein the signal transmission channel uses a four-resonance dual suppression structure to achieve dual full-duplex communication, and two data carriers are transmitted through an equivalent SS compensation structure formed by a parallel LC resonant network and a serial LC resonant network; the parallel LC resonant network is used to block one carrier while transmitting another carrier, and the serial LC resonant network is used to compensate for the reactive power of the circuit and improve the transmission power of the capacitor plate; the positive and negative signals are injected into the shielded capacitor plate through the wave blocking resonant network and the resonant inductor, forming a high-frequency alternating potential difference on the coupling plates of the primary / secondary sides, generating a high-frequency electric field and exciting an alternating voltage on the primary / secondary plates to form an interactive electric field; Under the action of the interactive electric field, a displacement current is generated that "flows" through the plates, transmitting the two data carriers to the primary / secondary receiving shielding capacitor plates of the WPT system.

2. The WPT system based on shielded capacitor plate data transmission according to claim 1 is characterized in that: The power transmission channel is specifically: The input DC power supply Vin generates a sine wave with a frequency of ω0 through a full-bridge inverter circuit composed of four switch tubes. The power transmission part adopts an equivalent SS compensation structure. P and C S is the primary transmitting coil L P and the secondary receiving coil L S The compensation capacitor is used to eliminate the self-inductance of the coil. The secondary side of the power transmission is rectified by diodes D1~D4 to form a load R L powered by; The signal transmission channel is specifically: In order to perform full-duplex transmission of signals, two signal source analog signal inputs U1 and U2 are set on the primary side and the secondary side of the signal transmission circuit respectively. The forward digital signal Date1 in and the reverse digital signal Date2in are modulated with a sine wave of a specified frequency through ASK modulation, and then injected into the signal transmission channel by a power amplifier; The primary transmitting coil Lp and the secondary receiving coil Ls are located on the inner side of the shielding capacitor plate. S1 , C S2 is the equivalent mutual capacitance of the shielding capacitor plates, C P12 With C P34 are the equivalent self-capacitances of the transmitting and receiving ends of the shielding capacitor plates, respectively; In order to demodulate the forward and reverse signals, the sinusoidal carriers of the forward and reverse signals are located in different frequency bands. The carrier frequency of the forward signal is set to ω1, and the carrier frequency of the reverse signal is set to ω2. The forward signal is injected into the primary shielding capacitor plate through the wave-blocking resonant network L1, C1 and the primary resonant inductor Lpp, and the secondary side receives the shielding capacitor plate and then obtains the signal waveform at the sampling resistor R2 through the secondary resonant inductor Lss and the wave-blocking resonant network L3, C3; after the signal waveform is sampled from R2, it is rectified by half-wave to become a signal waveform containing only the positive half axis, and the noise outside the passband is filtered out by the RC filter, and the waveform after filtering is amplified by the operational amplifier and sent to the envelope detection, and the detected envelope signal is compared with the given value to obtain a digital signal; The reverse signal is injected into the secondary shielding capacitor plate through the L4, C4 wave-blocking network and the secondary resonant inductor Lss, and then transmitted to the primary shielding capacitor plate through the displacement current, and transmitted to the sampling resistor R1 through the primary resonant inductor Lpp and the wave-blocking resonant network L2, C2 to obtain the signal waveform. After the signal waveform is sampled from R1, it is rectified by half-wave to form a signal waveform containing only the positive half axis. The noise outside the passband is filtered out by the RC filter, and the filtered waveform is amplified by the operational amplifier and sent to the envelope detection. The detected envelope signal is compared with the given value to obtain a digital signal.

3. The WPT system based on shielded capacitor plate data transmission according to claim 1 is characterized in that: The primary transmitting coil Lp and the secondary receiving coil Ls and their compensation capacitor C P With C S The following formula needs to be satisfied: Wherein, ω0 is the angular frequency of the sine wave generated by the full-bridge inverter circuit composed of four switch tubes through the input DC power supply Vin; f0 is the frequency corresponding to the angular frequency ω0; L P is the inductance of the primary transmitting coil, C P is the capacitance of the primary compensation capacitor; L S is the inductance of the secondary transmitting and receiving coil, C S is the capacitance of the secondary side compensation capacitor.

4. The WPT system based on shielded capacitor plate data transmission according to claim 2 is characterized in that: The topological structure of the shielding capacitor plate adopts a parallel disk coupling structure, specifically: Shielding capacitor plate emitter P 1、 P2 and the receiving end P 3、 The topology of P4 adopts parallel disk coupling structure. S1 is the equivalent mutual capacitance between P1 and P3, C S2 is the equivalent mutual capacitance between P2 and P4, C P12 With C P34 are the equivalent self-capacitances of the transmitting and receiving ends of the parallel capacitor plates, respectively.

5. The WPT system based on shielded capacitor plate data transmission according to claim 4 is characterized in that: When the radius of the primary transmitting coil and the secondary receiving coil is R = 57mm, when the outer radius of the inner capacitor plate is R1 = 40.5mm, the radius of the outer capacitor plate is R2 = 72.3mm, and the difference between the inner diameter of the outer capacitor plate and the radius of the inner capacitor plate is lg = 1mm, the parasitic capacitance difference between the coil and the plate is almost zero, that is, the primary transmitting coil L P The parasitic capacitance between the outer capacitor plate P3 and the inner capacitor plate P4 of the shielding capacitor plate of the secondary side is the same as that between the outer capacitor plate P3 and the inner capacitor plate P4 of the shielding capacitor plate of the secondary side. S The parasitic capacitance is the same as the parasitic capacitance between the outer capacitor plate P1 and the inner capacitor plate P2 of the primary shielding capacitor plate.

6. The WPT system based on shielded capacitor plate data transmission according to claim 1 is characterized in that: The parallel LC resonant network is composed of four groups of parallel resonant networks, which are respectively composed of a parallel network of resonant inductor L1 and resonant capacitor C1, a parallel network of resonant inductor L2 and resonant capacitor C2, a parallel network of resonant inductor L3 and resonant capacitor C3, and a parallel network of resonant inductor L4 and resonant capacitor C4; the L1C1 parallel network and the L3C3 parallel network are at the same resonant frequency, and the L2C2 parallel network and the L4C4 parallel network are at the same resonant frequency; that is, the resonance point of the forward LC network is exactly the suppression point of the reverse LC network; the serial LC resonant network is composed of the compensation inductor L PP and L SS and coupling plate C S1 With C S2 Through the equivalent SS compensation structure, two signal sources can be applied to the WPT system at the same time, thus achieving full-duplex communication.

7. The WPT system based on shielded capacitor plate data transmission according to claim 1 is characterized in that: The method for setting the frequency of the forward signal carrier and the reverse signal carrier is as follows: Set the forward transmission carrier frequency to ω1 and the reverse transmission carrier frequency to ω2, adjust the resonance point at the ω1 frequency to the suppression point at the ω2 frequency, and adjust the resonance point at the ω2 frequency to the suppression point at the ω1 frequency, so that one resonance point of one LC resonant network is exactly the suppression point of another LC resonant network.

8. The WPT system based on shielded capacitor plate data transmission according to claim 6 is characterized in that: The selection process of the equivalent SS compensation structure is as follows: The full-duplex communication channel topology is equivalent to the CPT system circuit structure with equivalent SS compensation, and the input impedance is derived; When the system is in a resonant state and the input impedance Zin is purely resistive, set the constraints that the compensation inductors L1 and L2 need to meet; Set the frequencies of the forward signal carrier and the reverse signal carrier, adjust the resonance point at the ω1 frequency to the suppression point at the ω2 frequency, and adjust the resonance point at the ω2 frequency to the suppression point at the ω1 frequency, that is, the resonance point of the forward LC resonance network is exactly the suppression point of the reverse LC resonance network; The L1, C1 network and the L3, C3 network need to be connected in parallel resonance at the reverse carrier frequency ω2; The L2, C2 network and the L4, C4 network need to be connected in parallel resonance at the forward carrier frequency ω1; When transmitting forward signals, simplify the signal transmission network: Connect the resonant network L1, C1 and the compensation inductor L pp Equivalent to the equivalent inductance L eq1 ; Connect the resonant network L3, C3 and the compensation inductor L ss Equivalent to the equivalent inductance L eq2 ; When L eq1 Inductance and L eq2 When the inductance value meets the constraints of L1 and L2, the system is in resonance; The reverse signal transmission is similar, simplifying the signal transmission network: Connect the resonant network L2, C2 and the compensation inductor L pp Equivalent to the equivalent inductance L eq3 , Connect the resonant network L4, C4 and the compensation inductor L ss Equivalent to the equivalent inductance L eq4 ; When L eq3 Inductance and L eq4 When the inductance value meets the constraints of L1 and L2, the system is in a resonant state. The resonant network L1, C1, L3, C3, L2, C2, L4, C4 and L are designed accordingly. pp With L ss The numerical value of .

9. A data parallel transmission method of a WPT system based on shielded capacitor plate data transmission, characterized in that: The method comprises: The ASK (Radial Shift Keying) method is adopted to change the carrier amplitude according to the different digital signals. The 01 digital signal sent by the host computer is converted into an analog signal with voltage through the DA conversion module, and then modulated with the sinusoidal carrier of the rated frequency by ASK modulation. When the analog signal is a high voltage, the ASK modulation output carrier amplitude is A1, representing the digital signal 1, and when the analog signal is a low voltage, the ASK modulation module outputs the carrier amplitude A0, representing the digital signal 0, to achieve signal modulation; and then after the same proportion amplification circuit, the signal carrier output of different amplitudes is realized; On the receiving side, the modulated carrier is obtained by half-wave rectification and then by RC filter. The envelope wave of the carrier signal is obtained by non-coherent envelope detection to achieve demodulation of the carrier signal. Finally, the envelope wave is compared with a given voltage signal through a comparator. When the envelope wave is greater than the comparison voltage, the comparator outputs 1, and when it is less than the comparison voltage, the comparator outputs 0. At this point, the analog signal is converted into a digital signal.

10. The data parallel transmission method of the WPT system based on shielded capacitor plate data transmission according to claim 9 is characterized in that: The process of obtaining the carrier signal through envelope wave demodulation includes: The input carrier passes through a detection diode to obtain a positive half-cycle waveform, and through an RC parallel network, the charge and discharge constant τ is adjusted by changing the values ​​of the resistor R and the capacitor C to obtain a waveform carrier signal. The design of the RC parameters needs to meet two conditions: first, it should be ensured that the discharge speed of the capacitor C is slower than the drop speed of the single-cycle carrier voltage; second, the capacitor discharge time should be shorter than half of the time occupied by a digital signal in the carrier.

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