To solve the problems of large current stress, difficult soft-switching of all switches, and slow dynamic response of dual active bridge converters, a multi-objective unified optimal control strategy based on triple-phase-shift control was proposed. The forward power flow global modes of triple-phase-shift control were analyzed, and three high-efficiency modes were selected to establish the analytical models of current stress and soft-switching. Combined with these models, the optimal solutions in different modes were derived by using the cost function-optimization equation to overcome the limitation of the Lagrange multiplier method, such that the DAB converter achieved the minimum current stress, and all switches operated in the soft-switching state over the entire power range. At the same time, the virtual power component was introduced in the phase-shift ratio combination, which improved the dynamic response of output voltage under the input voltage or load steps changed by power control. The theoretical analysis and experimental results show that the proposed control strategy can optimize the performance of the DAB converter from three aspects, such as current stress, soft-switching, and dynamic response, which achieves multi-objective optimization of the steady-state and dynamic performance of DAB converters.
LLC resonant converters are widely used in various fields due to high power density and high efficiency. However, when a switch failure happens in LLC, the converter is unable to maintain the normal output voltage gain while achieving high efficiency at resonant point. To make it more compatible with fault occasion, this paper proposes an improved LLC topology that ensures the output voltage remains unaffected when a primary switch failure occurs. Moreover, it can operate near the resonant point, maintaining a high level of efficiency. Additionally, an optimized burst control is added to effectively suppress the overvoltage and oscillation of the resonant capacitor during the fault tolerance transition. Simulation verifies the effectiveness of the proposed method.
Insertion loss (IL) is the main performance index of electromagnetic interference (EMI) filter, and the accuracy of its model directly affects the parameter design of EMI filter. In order to improve the prediction accuracy of insertion loss of EMI filters, accurately describe system behavior and predict EMI filter filtering performance. This paper uses artificial neural network to model the insertion loss of differential mode EMI filters, aiming to provide guidance for the design and optimization of EMI filters.
Aimed at the problems of horizontal misalignment and poor controllability of output power during battery charging,a reconfigurable wireless charging system(WCS)is proposed in this paper.The constant current/constant volt-age charging and zero voltage switching(ZVS)state for a full-bridge inverter are realized through reasonably switching power transmission channels when the mutual inductance and equivalent load resistance vary widely.First,the circuit topology of the system is analyzed,and an expression for the relationship among system parameters,charging current/voltage and ZVS state is derived,thus explaining the rationality of system reconfiguration and power controllability.Sec-ond,a magnetic coupler with sandwich coils(MCSC)is built,and its horizontal misalignment performance is analyzed,which provides a theoretical basis for the design of high misalignment tolerance of the system.Third,the workflow of WCS is analyzed,and a closed-loop controller is designed to realize constant current/constant voltage charging and ZVS state under a wide range of misalignment and load fluctuation.Finally,a WCS for UAV was built,and experimental results show that when the maximum output power was 126 W and the system efficiency was higher than 85%,the horizontal misalignment range was shifted to a circle with a diameter of 340 mm.
In practical applications,the relative position change between the two coupling coils of a wireless power transfer system will change the system parameters,resulting in system detuning as well as a lower power transmission ef-ficiency.For the problem of system detuning,a variable capacitance tuning control strategy is proposed.By controlling the charge and discharge time of the capacitor,the capacitance is equivalent to a variable capacitance,so that the e-quivalent capacitance value and the coil inductive reactance value can meet the resonant condition requirements.As a result,the system is always maintained in a resonant state,and the highest transmission efficiency between the transmit-ting and receiving coils of system will be kept.A simulation model was established,and an experimental prototype of magnetically-coupled resonant wireless power transfer system based on a series-series resonance compensation topology was built.The variable capacitance tuning control experiments were carried out,and experimental results show that the protype can realize stable and reliable wireless power transfer with a resonant frequency of 100 kHz and an input voltage of 20 V,thus verifying the effectiveness of the proposed variable capacitance tuning control method.
Aimed at the problem that the output current and voltage from a magnetic coupling resonant LCC-S wireless charging system are easily affected by external disturbance or its own parameter disturbance during its working process,as well as the problem of how to respond to disturbances quickly and accurately,a secondary-side two-stage closed-loop control method of constant-current and constant-voltage based on active disturbance rejection control(ADRC)is proposed.First,the relationship between the output characteristics of LCC-S resonant network and system parameters is studied through the circuit analysis.Second,the state equation model of a secondary-side Buck converter is established to achieve the closed-loop precise regulation of system output,and the tracking differentiator,extended state observer and nonlinear state error feedback in ADRC are designed accordingly.Finally,an experimental platform of wireless charging based on ADRC was built.The control effect is compared between the ADRC and PI controllers under multi-parameter disturbance,and results show that the former shows a better dynamic regulation capability.
Aimed at the problem of limited available resonant frequencies in shared channel transmission and in-ability to ensure the carrier transmission efficiency in the simultaneous wireless power and information transfer(SWPIT)technology,a three-frequency resonant SWPIT technology based on double-LCC circuit is proposed to achieve 3FSK modulation.Compared with the traditional 2FSK modulation circuit,the proposed circuit has the following advantages.First,three-frequency resonant frequency bands are adopted and all the system carriers use resonant frequencies,which avoids the defects such as a low utilization rate of system resonant frequency and a low transmission efficiency.Second,the system is enabled to operate normally at three frequencies,thus achieving full duplex and improving the working ef-ficiency.The work includes an analysis of resonant conditions for low-and high-order circuit resonators,parameter de-sign and frequency selection,and demodulation of signals.In addition,150 kHz,177 kHz and 48 kHz experimental platforms were built by Simulink simulation and an experimental prototype,thereby verifying the feasibility of the pro-posed 3FSK energy modulated technology.The experimental prototype showed that at three frequencies,the output volt-age on the receiving side was stable and its amplitude was 4/π times that of DC input voltage,achieving the goal of con-stant-voltage output.
The problem of transverse misalignment is the main challenge faced by wireless power transfer(WPT)systems applied in the field of electric vehicles(EVs).To improve the anti-misalignment capacity of static wireless charg-ing systems for EVs,a WPT system based on relay coil switching was proposed in this paper.First,the mathematical models of two-and three-coil WPT systems were established.Second,the anti-misalignment capacity of these WPT sys-tems was studied.By combining the advantages of the two-and three-coil structures,the overall anti-misalignment capac-ity of the system was improved.Finally,a prototype was built for experimental verification,and results showed that when the transverse misalignment was not more than 50%of the coil size,the system's output efficiency reached over 85%.
A UAV wireless charging coupling mechanism based on dual coupling coils is designed to meet the wireless charging requirements of medium and large UAVs,which has a high transmission energy efficiency and certain offset resistance while satisfying the lightweight design on the UAV side.The dual receiver coils are mounted at the bot-tom bracket positions on both sides of the UAV,and the dual transmitter coils are mounted on a trapezoidal transmitter platform with the same tilt angle as the UAV bracket to reduce the large range of UAV deflections.Meanwhile,a cas-cading series connection is used to ensure the uniformity of wireless charging.A series-series(S-S)compensation structure is also used.The finite element simulation is applied to compare and analyze the influence of different parameters of coupling coils on the transmission efficiency,and the design of coupling coils is optimized based on the principle of light weight.A UAV wireless charging experimental system was built,and results show the proposed coupling mechanism can effectively charge the UAV battery at 1.2 kW power with a transmission efficiency of 95.554%.The mass of the UAV-side coupling mechanism was 320 g,which meets the requirements of lightweight design of UAV coupling mechanism and also has certain offset resistance.
The magnetic coupling resonant wireless power transmission technology has gradually become a hot issue in the field of wireless power transmission owing to its advantages such as a long transmission distance and a high transmission efficiency.However,the design and optimization of a magnetic coupling resonant system relies on the accurate calculations of parameters and system performance.In this paper,the partial element equivalent circuit(PEEC)method is proposed to solve these problems.First,the basic theory of PEEC and the calculation method for partial parameters are introduced.Then,a PEEC model of the coupling coil is established,and the self-inductance and mutual inductance of planar rectangular spiral coils are calculated.The calculation results are compared with experimental results to verify the efficiency and accuracy of the PEEC method.On this basis,a two-coil system and a single resonance magnetic coupling resonant wireless power transmission system are established,respectively,and the transmission characteristics of these two systems are studied and analyzed using the PEEC method combined with the circuit method.Moreover,the accuracy and rapidity of the proposed method were verified by comparing the calculated results with those obtained using the finite element method.
At present,inductive wireless power transfer and capacitive wireless power transfer are becoming re-search hotspots.Since the power transmission is usually accompanied by information transmission,the undersea wireless information transmission gradually attracts attention and is able to develop further.A wireless power and information transmission system with shared channel is proposed,which allows power and information to be transferred through the same signal channel.In one switching cycle,power and data are transmitted in the first and second half of cycle,re-spectively.Data is modulated using the frequency-shift keying(FSK)method.The frequency for power delivery is set as 285.02 kHz.Using the binary frequency-shift keying(2FSK)modulation method,the frequencies of two signal carriers are set as 1 and 2 MHz,respectively.A water tank experimental platform was built with 35%salt water to simulate sea wa-ter,and simulation and experimental results verified the theoretical analysis and calculation well,indicating the feasibil-ity of the wireless power and information transmission system with shared channel in supplying power and transmitting data for undersea electrical equipment.
The magnetron is used by most of the existing high-power wireless power transfer(WPT)systems as radio frequency(RF)power supply.However,its narrow bandwidth and big mass are not conducive to system integration despite its high output power.To solve this problem,a solid-state microwave power source(MPS)with adjustable power and frequency was designed,which realized a wide bandwidth range and a wide output power range by using broadband amplifiers and feedback regulation.The system was integrated into a box with a size of 28 cm×19 cm×10 cm,and it had advantages such as a small volume,high reliability,a good heat dispersion performance and a small mass,showing its engineering application value to systems of WPT or RF energy harvesting in the environment(simulating the RF energy generation equipment in the environment,such as a base station and WIFI).Finally,the measurement results at room temperature show that the solid-state MPS designed had an adjustable frequency range of 0.7-2.8 GHz,with a frequency step of 1 MHz and a maximum frequency offset less than 0.3 MHz.In addition,it had an adjustable power range of 20.0-39.5 dBm,with a maximum output power error of±0.5 dB.The design method proposed provides guidance for the study and design of high-power MPSs.
Aimed at a coaxial rotating magnetic-coupling wireless power transfer(MC-WPT)system,a power and sig-nal parallel transfer method based on coaxial ring six-winding(CRSW)coupler is proposed.First,a mathematical model of the CRSW coupler is established,and the expression for the cross-coupling parameters of the power and signal channels is derived.Second,with the combination of finite element simulation,the positional relationship between each winding and the relationship of cross-coupling between the two channels are analyzed,and the conditions for achieving decou-pling are given accordingly.Third,the parameters and characteristics of compensation network for the power transmis-sion part of the system are analyzed and designed,and the signal transfer circuit including signal transmitting and re-ceiving parts is presented.Finally,an experimental prototype of the magnetic-coupling wireless power and signal transfer(MC-WPST)system was constructed,and results demonstrate that the proposed CRSW coupler exhibited a better sup-pression effect on the power crosstalk and switch noise in the fundamental frequency component.The signal transmission rate reached 19 200 bit/s based on amplitude shift keying when the system output power was 150 W.
To analyze the circuit characteristics of a parity time(PT)symmetrical system and provide theoretical guide-lines for the design of an actual system,the system is modelled based on the circuit theory and its working principle.It is proved that the working mechanism of the PT symmetrical system is a real eigenstate mechanism in essence.In addi-tion,the mathematical relationship among the system structure,its operation modes and its parameters is given,and a parameter criterion is provided for the design of the actual system.On this basis,the impedance and energy efficiency characteristics in different real eigenstates are compared and analyzed,which provides a theoretical basis for the selec-tion of the working mode of the actual system.
A multi-relay wireless power transfer(WPT)system can realize constant current(CC)or constant voltage(CV)output by switching its operating frequency to meet the needs of different electrical equipment.However,when the system operates at CV operating frequency,the voltage of some coils and resonant capacitors will rise abruptly,possibly leading to security risks.To solve this problem,an improved design method for the coupler and compensation capacitor of the multi-relay WPT system based on segmented compensation is proposed in this paper.First,the variation of ratios of compensation capacitor voltage to input DC voltage of the three-coil WPT system with frequency is studied.Then,the principle of segmented compensation is analyzed,and a coil voltage index for the multi-relay WPT system is defined as a criterion for the selection of the number of segments.Finally,an experimental platform of three-coil WPT system based on segmented compensation was established.Experiment results show that the proposed segmented compensation method can effectively reduce the voltage of resonance capacitor and improve the reliability and security of the system.
To address the issues of large volume and weight of a magnetic coupler for onboard wireless charging of electric vehicles as well as the susceptibility of ferrite fragmentation,a magnetic coupler with a composite shielding layer composed of ferrite magnetic sheets,nanocrystalline strips and aluminum foil was proposed in this paper.The performances of ferrite and four types of nanocrystalline magnetic cores were analyzed and compared by Maxwell,respectively.Based on machine learning,the optimal magnetic core structure of the magnetic coupler was obtained,and the structure of composite shielding layer and material composition ratio of each part were optimized.Compared with the traditional magnetic couplers composed of ferrite magnetic sheets and aluminum plates,the volume and weight of the magnetic coupler with the proposed composite shielding layer were reduced,while its mutual inductance and coupling coefficient were improved by 8.2%and 0.7%,respectively.In addition,its cost was reduced by 47%.Finally,a 2.5 kW experimental platform with a transmission distance of 12 cm was built for verification.
For practical conditions where both the load and coupling coefficient may vary obviously,a novel non-linear topology of wireless power transfer(WPT)based on ferro-resonance is proposed.First,the working principle is qualitatively analyzed using the Duffing equation and phasor analysis method.Second,the finite element software for cir-cuit simulation is used to verify the principle.Finally,a prototype of nonlinear topological WPT system with power up to 566 W and efficiency up to 93.5%was built.Experimental results show that the proposed nonlinear LCC-LCC topology can tolerate the drastic changes in coupling coefficient from 0.1 to 0.5 and load resistance from 72 Ω to infinity under 200 V secondary output voltage,indicating an excellent anti-misalignment capability and load stability.With a novel principle and a simple structure,the proposed topology has the potential to be applied in engineering.
To address the issues of low transmission efficiency and significant output voltage fluctuations caused by dynamic changes in load in a magnetic-coupling wireless power transfer(WPT)system,a constant-voltage no-communication WPT method based on linear active disturbance rejection control(LADRC)is proposed.A phase-locked loop is employed at the input of the system to track the resonant frequency,and a disturbance observation method is utilized to achieve minimum input power tracking.Meanwhile,a phase-shifted half-controlled rectifier circuit control strategy based on LADRC is implemented at the output to ensure constant-voltage output and efficient transmission,without the need of communication between the input and output.Simulation results demonstrate that a constant output voltage is maintained at the reference value under changes in load and the reference voltage,while the transmission efficiency of the system remains around 90%.
早在一个多世纪以前, 现代交流电之父尼古拉·特斯拉就梦想着能将电力无线传送到世界每个角落.经过了无数前辈的不断发展,结合电力电子、控制、材料等领域的新技术,无线充电技术取得了显著的进展.
The data acquisition and information processing of an underwater wireless power transfer(WPT)system are systematically studied in this paper.For this system,its transmission of power and information is affected to a certain degree considering the complex and changeable underwater environment.Since the marine environment is disturbed by some environmental factors such as temperature and pressure,the medium of underwater power transfer is uncertain,which will affect the electromagnetic field coupling between the power transmitting terminal and the power receiving ter-minal.As a result,the stability of underwater WPT will be affected,leading to changes in the transmission power and transmission efficiency of the WPT system under seawater conditions.Therefore,it is necessary to acquire the underwater marine environment information in real time and analyze the influences on circuit parameters and transmission efficiency of the underwater WPT system.An information acquisition and processing system based on a variety of sensors was built to realize real-time marine data acquisition,thus effectively solving the problem of underwater data acquisition and im-proving the data acquisition and data processing efficiency.The influences of the relative permeability,electrical con-ductivity,and relative permittivity of seawater on the system information and energy transfer are studied.In particular,the influences of temperature and pressure on WPT are analyzed in detail.
