Impedance Matching Range Research Articles

Magnetic coupling and amplitude truncation based bistable energy harvester

We present a two-degree-of-freedom bistable piezoelectric energy harvester (PEH) combining both magnetic coupling and amplitude truncation mechanisms to improve the electrical response when installed within compact spaces. The PEH processes a time-varying potential well and each beam has two electrical responses due to the interaction between two magnets. The collision-induced amplitude truncation behavior leads to high-frequency vibration responses, which reduces the matching impedance of the PEH. The Hamilton's principle and the Galerkin method was applied to establish the distributed parameter model for the system. By numerical calculations, the influence of the magnet distance and beam stiffness ratio on the static potential well, as well as the influence of excitation acceleration and stop gap on the voltage and power response were explored. A series of experiments were conducted to validate the voltage and power responses under sweep and fixed frequency excitations. The experimental and simulation results agree with each other. Due to the effect of magnetic coupling, the response frequency bandwidth of the cantilever beam widens by more than 7 Hz. The frequency-up effect generated by collision increases the response power of the system with the maximum of 307.8 mW at 103.6 Ω in experiments, and the combination of the two widens the impedance matching range of the system. This broadband structure with a wide impedance matching range and limited motion is more suitable for practical applications.

Conventional and pulsed hybrid triboelectric nanogenerator with tunable output time and wider impedance matching range

Sliding grating-structured triboelectric nanogenerators (SG-TENGs) can multiply transferred charge, reduce open-circuit voltage, and increase short-circuit current, which have wide application prospects in self-powered systems. However, conventional SG-TENGs have an ultrahigh internal equivalent impedance, which reduces the output voltage and energy under low load resistances (<10 MΩ). The Pulsed SG-TENGs can reduce the equivalent impedance to near zero by introducing a synchronously triggered mechanical switch (STMS), but its limited output time causes the incomplete charge transfer under high load resistances (>1 GΩ). In this paper, a conventional and pulsed hybrid SG-TENG (CPH-SG-TENG) is developed through rational designing STMS with tunable width and output time. The matching relationship among grid electrode width, contactor width of STMS, sliding speed, and load resistance has been studied, which provides a feasible solution for simultaneous realization of high output energy under small load resistances and high output voltage under high load resistances. The impedance matching range is extended from zero to at least 10 GΩ. The output performance of CPH-SG-TENG under low and high load resistances are demonstrated by passive power management circuit and arc discharge, respectively. The general strategy using tunable STMS combines the advantages of conventional and pulsed TENGs, which has broad application prospects in the fields of TENGs and self-powered systems.

Enhanced electromagnetic wave absorption properties of SiCN(Ni)/BN ceramics by in situ generated Ni and Ni3Si.

In this paper, the SiCN(Ni)/BN ceramic with excellent electromagnetic wave (EMW) absorption performance was successfully prepared. The Ni and Ni3Si were in situ formed by the introduction of nickel acetylacetonate (NA), which effectively improved the impedance matching performance of SiCN(Ni)/BN ceramics. The EMW absorption properties of the SiCN(Ni)/BN ceramics showed a trend of first increasing and then decreasing with the increase in content of NA. When the NA content reached 7 wt%, the impedance matching range of SiCN-7 was optimal. The minimum reflection loss (RLmin) of SiCN-7 reached -53.47 dB at 4.2 mm and the effective absorption bandwidth (EAB) was 2.32 GHz at 3.48 mm. Through the analysis of electrical conductivity, it was found that the proportion of polarization loss in dielectric loss was more than 99%. It is worth noting that the radar cross section (RCS) value of SiCN-7 absorber was lower than that of the perfect electrical conductor (PEC) plate in the range of -90-90°, and showed a larger coverage angle, indicating that it possessed a good practical application prospect in the field of electromagnetic wave absorption.

A Cascaded Topology and Control Method for Two-Phase Receivers of Dynamic Wireless Power Transfer Systems

In a dynamic wireless power transfer (DWPT) system for electric vehicles, bipolar transmitting rail is often implemented to improve the misalignment tolerance, but its constraint often lies in fluctuating output. This problem can be mitigated by applying two-phase receivers which, due to its structural characteristics in the impedance matching circuit, bring two new problems: limited range of impedance matching and low efficiency. This paper aims to tackle the two problems by introducing a cascaded topology and its control method. Firstly, the conventional topology of the two-phase receiver is thoroughly analyzed theoretically concerning impedance matching range and efficiency model. Secondly, a cascaded bridgeless rectifier-Buck (CBRB) as impedance matching with 0~ ∞Ω matching capabilities is put forward. Besides, the independent two-channel structure is also introduced leaving the output current ratio the key to efficiency optimization. Thirdly, the control method for the proposed topology using heuristic current ratio by adopting online estimation via auxiliary measurement coils is presented. Finally, experiments are verified on a 20 kW DWPT platform and the proposed topology and control method can raise the transfer efficiency by 3.3% compared with the conventional topology.

An Area Efficient Thermal Energy Harvester With Reconfigurable Capacitor Charge Pump for IoT Applications

This brief introduces an integrated energy harvester system targeting Internet of Things sensor applications such as a wireless temperature sensor. The proposed design provides 1-V regulated voltage boosting the input voltage (0.27–1 V) from a thermoelectric generator (TEG). To ensure the maximum power extraction, the proposed energy harvester includes multiple circuit level techniques. First, the reconfigurable capacitor charge pump distributes on-chip capacitors to required step-up stages. This approach optimizes the silicon area by utilizing 100% of on-chip capacitors regardless of charge pump conversion gain. Second, the design is capable of 3-D maximum power point tracking, matching a source impedance to input impedance of the energy harvester. Thus, the proposed design is able to extract power from a small form factor TEG, having low source impedance. The reconfigurable capacitor charge pump has the highest power density while delivering power up to $500~{\mu W}$ . Experimental results show end-to-end power efficiency of 64% @ 1–V output voltage, and an input impedance matching range of $1 {\Omega } - 5~{\mathbf{k}}{\Omega }$ . The energy harvester was fabricated in 130-nm CMOS standard technology with an active area of 0.835 mm2.

Impedance-Matching Range Extension Method for Maximum Power Transfer Tracking in IPT System

Maximum power transfer is an important index for an inductive power transfer (IPT) system to make full use of its power transfer capability, and such a capability is usually realized by impedance matching. Traditionally, impedance matching is implemented by placing a power electronics converter such as a dc–dc converter at the secondary side of an IPT system. However, the power electronics converter and its operation mode directly affect its impedance-matching range, which is very limited if a traditional power converter only operates at continuous conduction mode (CCM). To extend the impedance-matching range, this paper proposes a novel impedance matching method based on combined CCM and discontinuous conduction mode (DCM) operation of an impedance matching converter. The impedance-matching range is fully analyzed for CCM and DCM operation, respectively, by taking variation of coupling coefficient into consideration. The analysis results show that the impedance-matching range can be extended by more than double that of the traditional impedance matching method. In addition, a maximum power transfer tracking method is developed using the proposed impedance-matching range extension method, and the experimental results have verified the feasibility of the tracking method.

A Passive Mixer-First Receiver With Digitally Controlled and Widely Tunable RF Interface

A software-defined radio (SDR) receiver with baseband programmable RF bandpass filter (BPF) and impedance match is presented. The passive mixer-first architecture used here allows the impedance characteristics of the receiver's baseband circuits to be translated to the RF port of the receiver. Tuning the resistance at the baseband port allows for a real impedance match to the antenna. The addition of complex between I and Q paths allows for matching to the imaginary component of the antenna impedance. By implementing both real and imaginary components with resistors in feedback around low noise baseband amplifiers, noise figure is also kept low. Tunable sampling capacitors on the baseband side of the passive mixer translate to tunable-Q filters on the RF port which allow for very good out-of-band linearity. Furthermore, the concept of in-band and out-of-band must be redefined as the impedance match and BPF center frequency move with the LO frequency, such that matching and filtering track the receive frequency. Additionally, 8-phase mixing is shown to provide significant benefits such as impedance matching range, rejection of blockers at LO harmonics, and lower noise figure (NF). Measurements from the receiver implemented in 65 nm CMOS show 70 dB of gain, NF as low as 3 dB, and 25 dBm out-of-band IIP3. Furthermore, tunable impedance matching shows that S11 <;- 30 dB can be achieved at any receive frequency from 0.1-1.3 GHz.

π‐Section tunable matching network with patterned ferroelectric thin film

AbstractA prototype of a tunable impedance matching network in π‐configuration has been fabricated with ferroelectric varactors of patterned Barium‐Strontium‐Titanate Ba0.5Sr0.5TiO3 (BST) thin film. The matching circuit is designed based on a coplanar waveguide (CPW) transmission line and interdigital capacitors (IDC). The tunable impedance matching range and insertion loss are measured with varying voltage at the frequency range of 0.1–2 GHz. The insertion loss of designed circuit is 0.36 dB at 0.9 GHz. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 3251–3254, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23942

A low-loss SAW-TV-IF filter with an extended impedance matching range

A novel low-loss SAW (surface acoustic wave) filter for an intermediate frequency (IF) circuit in a color TV receiver has been developed. It consists of an apodized bidirectional and an unapodized group-type unidirectional transducer. The unidirectional transducer is designed to use different numbers of finger pairs in sending and reflecting electrodes for extension of the impedance-matching range. A thin-film capacitor for use as a phase shifter is monolithically fabricated on a 128 degrees Y-X LiNbO(3) substrate. A low insertion loss (11.3 dB) and impedance matching without adjustment are achieved at the same time without increasing the device chip size or number of electrical parts.

A Unidirectional SAW Transducer with Different Finger Pairs between Sending and Reflecting Electrodes

An intentionally imperfect unidirectional transducer has been studied for SAW TV IF filter. It is constituted of different finger pairs between sending and reflecting electrodes to extend impedance matching range. And a thin film phase shifter is monolithically fabricated on a substrate. As the result low insertion loss and no matching adjustment can be achieved at the same time, and that without any increase of chip size and electrical parts.