Load Impedance Matching Research Articles

A Novel LCLC Parallel Resonant Circuit for High-Frequency Induction Heating Application

A Novel LCLC Parallel Resonant Circuit for High-Frequency Induction Heating Application

Enhancing Wireless Charging for Electric Vehicles: Active Load Impedance Matching and Its Impact on Efficiency, Cost and Size

This paper presents an advanced Wireless Power Transfer (WPT) system for electric vehicles (EVs) featuring Active Load Impedance Matching (ALIM) at the rectification stage. Unlike traditional synchronous rectification, ALIM dynamically adjusts load impedance, optimizing energy transfer efficiency and reducing thermal stresses, system costs, and mass. The system incorporates two circuits optimized for distinct frequency bands: one operates below 10 kHz using standard copper wiring for cost-effectiveness, and the other at 85 kHz, which significantly reduces the mass of the onboard coil and magnetic circuit while ensuring interoperability according to SAE J2954 standard. Our approach enhances charging efficiency across various operating conditions, improves thermal management, and minimizes maintenance costs. Additionally, it enables partial compensation for vehicle misalignment and ground assembly impedance, further boosting efficiency and interoperability. Experimental results demonstrate a notable increase in efficiency and reduction in system mass, confirming the superiority of the ALIM-equipped WPT system over conventional solutions. This paper underscores the potential of ALIM to advance the scalability, efficiency, and economic viability of wireless EV charging technology, promoting broader adoption and sustainability in EV infrastructures. By providing a comprehensive solution that addresses key challenges in wireless charging, our work paves the way for more efficient and cost-effective EV charging systems.

Optimization of series-series compensated wireless power transfer system using alternative secondary side rectification

This paper focuses on the operational analysis of wireless power transfer (WPT) system, while the topology of the secondary side rectifier represents the main element, for which the properties of WPT system are being investigated. Initially the system description and technical specifications are given. Because WPT systems are designed for a certain type and value of the load (impedance matching) in order to achieve the highest possible efficiency, the definitions for those values are identified for individual topologies of the secondary side rectifiers. Consequently, the results are compared and discussed and followed by the simulation analysis to prove the operational behavior in time-domain for each of investigated alternative of rectifier. Several relationships have been identified in relation to secondary side electrical variables, and discussion for stress-optimization are given as well. The simulation results are verified by the experimental measurements, while individual solutions for secondary side rectifiers are evaluated from efficiency point of view followed by the recommendations of the operational conditions.

An improved auxiliary circuit for IPT systems to achieve inherent CC‐to‐CV transition and load fault‐tolerant operation

AbstractThree‐coil inductive power transfer (IPT) charging system can not only achieve inherent constant current (CC) to constant voltage (CV) transition but also tolerate load open‐circuit. However, due to the cross‐coupling between the auxiliary coil and the receiver coil, the output voltage in CV mode may deviate from the CV voltage significantly, which makes the design freedom of the three‐coil coupler low. By replacing the auxiliary coil with a transformer, an improved auxiliary circuit is proposed in this paper to address the cross‐coupling issue and to increase the design freedom of the loosely coupled transformer (LCT). The improved auxiliary circuit can achieve load short‐circuit and open‐circuit protection. Besides, the optimization design of LCT is easy to achieve by load impedance matching. The operating principle and parameters design of the improved auxiliary circuit are discussed. A 1 kW experimental prototype is built to verify the feasibility of the proposed method.

Optimal Design of a Novel Piezoelectric Vibration Energy Harvester

A novel piezoelectric vibration energy harvester structure is designed. The output voltage is employed as the objective function, and the structural parameters of the vibration energy harvester device are optimized by Taguchi method. The best parameter combination of A3(95mm), B3(45mm), C1(60mm), D2(35mm) and E1(50mm) is determined. Through the analysis of variance, it is concluded that parameter A has the most obvious effect on the response of the piezoelectric energy harvester, with the contribution rate reaching 26.02%, and the influences of B, C, D and E decrease successively. The finite element model of the piezoelectric vibration energy harvester is established, then the load impedance matching characteristics and acceleration dependence of voltage are discussed.

A Dual-Resonant Topology-Reconfigurable Inverter for All-Metal Induction Heating

Traditionally, domestic induction heating (IH) is designed to heat the ferromagnetic (FM) pan. However, it is incompetent to heat the non-FM (NFM) pan since the small equivalent resistance of the pan will easily result in overcurrent on the inverter. Inspired by the compensation network in the wireless power transfer (WPT), the series–parallel resonance (SPR) network with a relay switch is newly integrated into the IH technology to develop a dual-resonant topology-reconfigurable inverter for all-metal IH. The proposed system can be purposely configured to a half-bridge series resonant inverter with the pulse width modulation (PWM) to heat the FM pan, or a full-bridge SPR-based inverter with the phase shift control (PSC) to heat the NFM pan, respectively. Moreover, the output–input current gain of the SPR network equals the heating-coil quality factor, thereby readily eliminating the overcurrent issue of the inverter. For exemplification, a 1-kW prototype has been built with system efficiencies of 94.32% and 91.05% for heating FM and NFM pans, respectively. Finally, the proposed system can be evolved to achieve automatic load detection and impedance matching to ensure uninterrupted resonance. Both the calculated and measured results are given to validate the flexibility and feasibility of the proposed system.

New Adaptive Broadband Full-Bridge Converter Impedance Matching Network for Giant Magnetostrictive Transducer

This article proposes an adaptive broadband full-bridge converter impedance matching network (FCIMN) between a power amplifier and the giant magnetostrictive transducer (GMT). Compared with the conventional passive impedance matching methods, the proposed one can realize the load impedance matching of power amplifiers under a wide frequency range. In this article, first, the elementary principle of operation of FCIMN is introduced mathematically. After that, a control method is proposed to achieve adaptive broadband impedance matching, including dynamic active power calculation, reactive power calculation, segmented proportional–resonant controller and combined feedback and feedforward voltage control. On this basis, the parameter design method is proposed for the operating frequency range. Finally, the simulation and laboratory-scale experimental results are provided to validate the effectiveness of the proposed FCIMN, discussions, and control method. It clearly shows that the proposed FCIMN can adaptively match load impedance for the different GMTs, broadband range, and the power amplifier power utilization factor is significantly improved.

A New Adaptive Broadband Thyristor-Controlled Impedance Matching Network

In this article, we present an adaptive broadband thyristor-controlled impedance matching network (TCIMN) for increasing power utilization from a power amplifier to the loads. Different from the conventional passive impedance matching methods, the proposed one can achieve load impedance matching under a wide frequency range of power amplifiers. First, the operation principle of TCIMN is introduced mathematically. Based on that, the parameter design method is proposed based on the required frequency range. Moreover, the operating range and harmonic analyses are provided to give the TCIMN firing angle operating ranges under different frequencies and alleviate the potential harmonic problem caused by thyristors. To control the proposed TCIMN, the dynamic impedance identification is applied to match the load reactive power adaptively. Finally, the simulation and experimental results of a prototype are given to demonstrate the validity of the proposed TCIMN, analysis, and control method. The results clearly show that the proposed TCIMN can adaptively match the load impedance for the different loads and broadband frequency range. More importantly, the power amplifier power utilization factor is significantly improved without causing harmonic pollutions.

Designing 6–18 GHz Microstrip Filters with Removing Unwanted Upper and Lower Band Frequency Responses and with Arbitrary Load Impedance Matching

In this paper, Ultra-Wideband (UWB) filters at 6–18[Formula: see text]GHz are designed that can reduce undesired frequency responses at lower and upper frequency bands to less than [Formula: see text]20[Formula: see text]dB. Arbitrary load impedances are considered in the design of these filters. The structure of these filters is the combination of microstrip band-pass filters and Defected Ground Structures (DGSs) with multiple sections. The optimum circuit dimensions are calculated using a computer code which implements the Least Mean Squares (LMS) optimization method. Two design examples are included to illustrate this method. In these examples, eight-section DGS structures are employed to eliminate the unwanted upper frequency band responses. To ensure the correct performance of the designed filters, they are analyzed using full-wave methods and fabrication and the results of the measurement or full-wave analysis shows good agreement with the results of the computer code and the circuit model simulations.

A Single-Stage Inductive-Power-Transfer Converter for Constant-Power and Maximum-Efficiency Battery Charging

This article proposes a single-stage inductive-power-transfer (IPT) converter operating as a wireless constant-power (CP) and maximum-efficiency battery charger. By maintaining a constant output power rather than providing a constant output current throughout the dominant stage of battery charging, the IPT converter can make the utmost of its power capability, thus having a faster charging rate. The proposed single-stage IPT converter adopts series–series compensation and includes a switch-controlled capacitor (SCC) and a semiactive rectifier (SAR) in the secondary side. Manipulating the SCC and the SAR to emulate the optimum impedance of the resonator and the load, we propose a novel operation approach combining the merits of load-independent transfer characteristic and load impedance matching, to achieve a simple solution to CP charging and maximum efficiency throughout the charging process. Since the control scheme is based on fixed operating frequency and secondary-side real-time regulation, wireless feedback communication is not required. Moreover, soft switching and low voltage stress can be easily achieved in this IPT converter.

The Transfer Matrix Method: Analysis of Nonuniform Multiport Systems

A ubiquitous tool in science, physics, and engineering at large, the transfer matrix method (TMM) is particularly suited to deal with complex nonuniform systems (NUS). In the field of electrical engineering, the method is employed in a variety of disciplines that span the electromagnetic spectrum, from power frequencies through RF, millimeter-waves, and terahertz. In this work, three nested goals are pursued. The first is to present a general comprehensive review of the transfer matrix method utilizing two distinct languages: the state space (via the matricant) and the modal analysis (via matrix diagonalization). The second goal, focused on electrical engineering issues, is the application of TMM to the interdisciplinary theme of nonuniform multiconductor transmission lines (MTL) –a good example of a complex reciprocal multiport system. The third goal is to offer the reader novel research results in the context of MTL analysis. Making use of a simple microwave stripline-coupler structure new theoretical results are presented showing that, in some cases, load impedance matching of nonuniform MTLs, using only passive components, may not be physically possible (negative resistors being required), even if the global NUS is longitudinally and transversally symmetric, with or without losses.

Ultrasonic Lamb Waves for Wireless Power Transfer.

Ultrasonic guided plate waves (Lamb waves) can be used to transfer power along the length of metal plates, achieving longer distance wireless power transfer (WPT), while not being impeded by electromagnetic shielding from the metal plate. In this article, a fundamental study on the performance of Lamb wave WPT is presented, including modeling, simulations, and experimental verification. By using Macro-Fiber Composite (MFC), d33 -mode, piezoelectric transducers bonded to a [Formula: see text] mm aluminum plate using an epoxy, power transfer of 0.47 W with 56% overall power transfer efficiency was achieved at a 204-mm distance. The measured frequency response of the power transfer efficiency matches well with the simulated results, and the effects of complex load impedance matching and transducer sizing were investigated. It is shown that the location where the efficiency is maximized roughly corresponds to the zero-order symmetrical mode (S0) standing wave patterns due to reflections from the plate edges. For practical implementation, the effect of using different methods to temporarily or permanently bond the MFC transducers to the metal plate was also investigated, as well as the effect of electrically grounding the metal plate.

An Inductive-Power-Transfer Converter With High Efficiency Throughout Battery-Charging Process

An inductive power transfer (IPT) converter usually has an optimum efficiency only at a matched load. Because of wide load range variation during battery charging, it is challenging for an IPT converter to achieve the required output and maintain high efficiency throughout the charging process. In this paper, a series-series compensated IPT converter with an active rectifier is analyzed and implemented for battery charging. Appropriate operations are employed for constant-current charging and constant-voltage (CV) charging. A novel operation approach is proposed to achieve constant output voltage and to ensure load impedance matching during CV charging without the help of an extra dc-dc converter, which incurs loss. Both a frequency modulated primary inverter and a phase-angle modulated secondary active rectifier can achieve soft switching. High efficiency can be maintained during the whole battery-charging profile.

Nanosecond pulsed discharge-driven non-oxidative methane coupling in a plate-to-plate electrode configuration plasma reactor

In this work, we establish a set of reactor operation guidelines for efficient non-oxidative methane coupling (i.e., high olefins yield) in nanosecond pulsed discharges and plate-to-plate electrode configuration. The reactor performance analysis suggests that the operating conditions directly affect the bulk gas temperature, which in turn determines the plasma resistance and, subsequently, the energy channeled into the discharge. High performance is attained only at proper load-impedance matching, i.e. when operating in spark regime and applying i) moderate pulse frequencies (≤20 kHz) combined with moderate discharge gaps (≤3.5 mm) or ii) high pulse frequencies (>20 kHz) combined with high discharge gaps (>3.5 mm). Further, the electrode configuration itself significantly affects the reactor performance. When applying same operating conditions, the plate-to-plate configuration attains lower olefin (C2) yield than the co-axial one (~27% vs ~34%, respectively) since lesser energetic discharges are ignited (11 W vs 17 W), but ~20% lower energy is used due to lower electric energy dissipation into gas heating. The plate-to-plate configuration also features significantly higher performance stability and robustness in carbon formation, enabling an order-of-magnitude longer operating periods.

A W-Band Transformer-Based Power Amplifier with Anti-Pair Capacitors in 0.13-μm SiGe BiCMOS

This paper presents a W-band three-stage amplifier using 0.13-μm SiGe BiCMOS process, which is implemented with transformers for inter-stage matching and single-to-differential transformation. However, for balun operation, conventional transformer exhibits imbalance characteristic resulting from the complex parasitic effects arising in the millimeter-wave frequency range. An anti-pair capacitor structure is devised and applied to improve amplitude and phase balance and further benefit the RF performance. A two-way transformer-based parallel combiner embedded with several co-optimizing elements is designed to implement power combining and optimum load impedance matching. The amplifier achieves a peak gain of 28.2 dB at 93 GHz, with a 3-dB bandwidth from 85 to 96 GHz. The measured saturated output power (Psat) and maximum power added efficiency (PAE) at 94 GHz are 14.1 dBm and 9.2%, respectively. The power amplifier with only 0.6-mm2 area exhibits excellent gain and maintains competitive output power and PAE in W-band.

The design of a direct charge nuclear battery with high energy conversion efficiency

Direct charging nuclear batteries (DCNB) have the potential of being widely used to meet the special requirements in the area of aerospace and ocean. The current application of direct charging nuclear batteries is restricted by the low energy conversion efficiency, commonly less than 10%. This low efficiency is limited mainly by issues of low source efficiency and shunt factor among others, such as collection and geometry factors. Based on a numerical simulation and empirical calculations we here propose a design of DCNB by utilization of a sub-micrometer thickness radiation source to increase the source efficiency, both-side emission, and collection of decay particles to improve the collection and geometry factors, as well as impedance matching of batteries and load to improve the shunt factor, among other various optimizations. The energy conversion efficiency of DCNB with this design reaches over 20%. The successful deployment of the current design should vastly improve the energy conversion efficiency of DCNBs, and also establish a theoretical foundation for extending the scope of applications of DCNBs in the future.

Maximum Efficiency Tracking for Wireless Power Transfer Systems With Dynamic Coupling Coefficient Estimation

Maximum efficiency tracking is an important issue for wireless power transfer (WPT) system. Traditional maximum efficiency tracking method normally focuses on load impedance matching with fixed coupling condition. However, WPT system is a loosely coupling system, the coupling coefficient varies due to relative movement between the primary and secondary sides. Unknown to this variation may result in failure of the tracking. In this paper, a novel maximum efficiency tracking method is proposed with integrated dynamic coupling coefficient estimation. This method can take almost all requirements for maximum efficiency tracking into account including adaption for coupling coefficient and load variation, and output controllability. The tracking method is easy to implement because no additional circuitry or measurement is required. Experimental results have verified the correctness of the proposed coupling coefficient estimation method. And the maximum efficiency tracking results show the system can achieve a good performance against coupling coefficient and load variation with the proposed tracking method.

Study on Load Impedance Matching Characteristics of Magnetic Coupled Resonant Wireless Power Transfer System

The impedance matching problem of magnetic coupled resonant wireless power transfer system based on planar spiral coils is studied in this paper. Taken the coupling factors into account, the relationships between impedance matching, resonant frequency and transfer distance are analyzed. Supported by the simulation analyses and experimental evidences, it is indicated that the optimum matching resistances for transfer power and transfer efficiency are different. In details, the optimal matching resistance for output power decreases with the transfer distance, while that for the transfer efficiency does not vary with transfer distance. Thus, this research provides a valuable reference for the further research on adaptive impedance matching of magnetic coupled resonant wireless power transfer system.

The effect of metal load material and impedance matching on EMAT performance

The effect of metal load material and impedance matching on EMAT performance

2-6 GHz GaN HEMT Power Amplifier MMIC with Bridged-T All-Pass Filters and Output-Reactance-Compensation Shorted Stubs

This paper presents a 2-6 GHz GaN HEMT power amplifier monolithic microwave integrated circuit (MMIC) with bridged-T all-pass filters and output-reactance-compensation shorted stubs using the 0.25 mm GaN HEMT foundry process that is developed by WIN Semiconductors, Inc. The bridged-T filter is modified to mitigate the bandwidth degradation of impedance matching due to the inherent channel resistance of the transistor, and the shorted stub with a bypass capacitor minimizes the output reactance of the transistor to ease wideband load impedance matching for maximum output power. The fabricated power amplifier MMIC shows a flat linear gain of 20 dB or more, an average output power of 40.1 dBm and a power-added efficiency of 19-26 % in 2 to 6 GHz, which is very useful in applications such as communication jammers and electronic warfare systems.