High-order Circuit Research Articles

A Dual-Band Coil Array With Novel High-Order Circuit Compensation for Shielding Design in EV Wireless Charging System

For the wireless power transfer (WPT) system in electric vehicle (EV) applications, a serious concern lies in the leakage electromagnetic field (EMF) emission. In order to address this issue, this article presents a dual-band coil array (DB-CA) with novel high-order circuit (HOC) compensation. The most attractive feature of DB-CA is that both the first and third harmonics of leakage EMF can be reduced simultaneously, while the system still resonates at the same frequency. A detailed mathematical model is established to intuitively reveal the relevance between impedance design and shielding performance, as well as the constraints to achieve resonance. In addition, the novel HOC compensation is employed to decouple the shielding design at each harmonic. Both simulated and experimental results verify the effectiveness of DB-CA, and a 1-kW WPT prototype operating at 85 kHz is established. By applying DB-CA, the leakage EMF can be reduced by 3.88 dB at 85 kHz and 1.84 dB at 255 kHz, respectively. Meanwhile, the system resonant frequency still locates at 85 kHz, and the achieved zero phase angle condition is independent with load condition. It can provide significant guidance to the design of shielding configurations in EV Wireless Charging System.

HTS Wideband Bandpass Filter Based on Ladder Topology Circuit and Microstrip Transformation

This article presents a novel high-temperature superconducting ultra-wideband filter with a 108% fractional bandwidth. A high-order ladder topology circuit is utilized in the proposed filter to ensure a deep out-of-band rejection. Superconducting quasi-lumped elements are applied to reduce the insertion loss brought by the high-order circuit. The proposed filter derives from a low-pass filter (LPF) with a cut-off frequency at 2.7 GHz. Microstrip transformation is adopted in this LPF to achieve a lower stopband at 0.8 GHz. The proposed transformation provides a possibility to separately tune the lower and upper cut-off frequency in a microstrip filter. The measured results demonstrate a good agreement with circuit analysis and EM simulations, and show an excellent performance.

Topology Simplification and Parameter Design of Z/T/Γ-Source Circuit Breakers

Z/T/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Gamma $ </tex-math></inline-formula> -source circuit breakers used in flexible dc distribution systems have been rapidly developed due to their advantages of high speed and low cost. However, the precise model of the circuit breaker is generally a high-order circuit, which is difficult to solve. The lack of simplified topology and parameter design considering system parameters (line inductance, line resistance, and load capacitance) restricts their applications in practical engineering. Therefore, based on the equivalent mathematical model, a simplified topology that can represent Z/T/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Gamma $ </tex-math></inline-formula> -source circuit breakers is proposed and their working principles are revealed in this article. Considering system parameters, the parameters of Z/T/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Gamma $ </tex-math></inline-formula> -source circuit breakers are designed to take care of short circuit fault and step changes in load. Finally, simulation and experiment show that parameters designed by the proposed method can ensure the reliable operation for Z/T/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Gamma $ </tex-math></inline-formula> -source circuit breakers.

Design of a high-order narrowband superconducting balanced filter based on asymmetrically coupled stepped-impedance resonators

This study investigates a sixth-order narrowband superconducting balanced filter with high frequency selectivity and wide stopband based on asymmetrically coupled stepped-impedance resonators (SIRs). Three types of coupled SIR pairs with different characteristics are investigated. The differential-mode (DM) phase shifts, coupling coefficients, and common-mode (CM) levels of the three SIR pairs are then analyzed. The spurious frequencies of DM responses can be pushed far away from the fundamental frequency to widen the stopband by properly choosing the impedance ratio of the SIR and using dissimilar SIRs with dispersed harmonics. Moreover, an inherent CM suppression can also be obtained because of the different resonant frequencies in DM and CM equivalent circuits. Results also show that the electromagnetic coupling pair can contribute a weak coupling coefficient for narrowband design without increasing the circuit size. The structure of the electric coupling pair is beneficial for high-order circuit interconnection. The magnetic coupling pair possesses the highest CM rejection. Moreover, the weak coupling properties are well-utilized for narrowband design. For validation, a sixth-order balanced bandpass filter is designed using the three coupled SIR pairs, and a cross-coupling structure is further introduced to produce transmission zeros (TZs) and enhance the passband selectivity. The magnitude and phase delay of the DM transmission paths are analytically illustrated to explain the TZ production. Eventually, the proposed balanced filter is implemented by a high-temperature superconducting technique to reduce the insertion losses and is measured at the temperature of 77 K. The measured results show that the fractional bandwidth of the passband is 1.6$%$ with less than 0.37 dB in-band insertion loss. The $-60$ dB bandwidth/$-3$ dB bandwidth rectangle ratio is less than 1.45 while the in-band CM suppression is better than 40 dB. The $-$20 dBłinebreak stopband is up to about 5$f_{0}^{d}$ ($f_{0}^{d}$ is the DM fundamental frequency).

Load-Independent Voltage and Current Transfer Characteristics of High-Order Resonant Network in IPT System

Load-independent output characteristics of an inductive power transfer (IPT) system are of increasing interest in electric vehicle and LED lighting applications. All compensation networks in the IPT system are actually high-order resonant circuits. In a high-order resonant network, there are multiple resonant frequencies to get load-independent voltage output and current output. It is critical to analyze the resonant conditions to achieve high efficiency in both load-independent voltage output and current output modes. This paper proposed a general modeling method for arbitrary high-order resonant networks to get both the load-independent voltage and current transfer characteristics. A high-order circuit can be modeled as a combination of an LC network, a multistage T-circuit, and/or multistage $\Pi $ -circuit in series. The proposed method is verified by applying to voltage-fed double-sided inductor–capacitor–capacitor (LCC), series–series (SS), S-SP, LCC-S, and current-fed CLC-LC compensation networks in the IPT system. The MATLAB simulation and the experimental prototype of a constant voltage-fed double-sided LCC compensated IPT system with up to 3.3-kW power transfer are built. The efficiency of the double-sided LCC compensated IPT system is up to 92.9% and 90.6% when the IPT system operates at resonant frequencies that achieve constant current output and constant voltage output, respectively, which are compliance with the frequency requirement by SAE J2954 standard.

Differences in neurotropism and neurotoxicity among retrograde viral tracers

BackgroundNeurotropic virus-based tracers have been extensively applied in mapping and manipulation of neural circuits. However, their neurotropic and neurotoxic properties remain to be fully characterized.MethodsThrough neural circuit tracing, we systematically compared the neurotropism discrepancy among different multi-trans-synaptic and mono-synaptic retrograde viral tracers including pseudorabies virus (PRV), rabies virus (RV), and the newly engineered retro adeno-associated virus (rAAV2-retro) tracers. The (single-cell) RNA sequencing analysis was utilized for seeking possible attribution to neurotropism discrepancy and comparing cell toxicity caused by viral infection between glycoprotein-deleted RV (RV-∆G) and rAAV2-retro. Viral toxicity induced microglia activation and neuronal protein change were evaluated by immunohistochemistry.ResultsMulti-trans-synaptic retrograde viral tracers, PRV and RV, exhibit differential neurotropism when they were used for central neural circuit tracing from popliteal lymph nodes. Mono-synaptic retrograde tracers, including RV-∆G and rAAV2-retro, displayed discrepant neurotropic property, when they were applied to trace the inputs of lateral hypothalamic area and medial preoptic nucleus. rAAV2-retro demonstrated preference in cerebral cortex, whereas RV-∆G prefers to label basal ganglia and hypothalamus. Remarkably, we detected a distinct preference for specific cortical layer of rAAV2-retro in layer 5 and RV-∆G in layer 6 when they were injected into dorsal lateral geniculate nucleus to label corticothalamic neurons in primary visual cortex. Complementation of TVA receptor gene in RV-resistant neurons enabled EnvA-pseudotyped RV infection, supporting receptors attribution to viral neurotropism. Furthermore, both RV-∆G and rAAV2-retro exerted neurotoxic influence at the injection sites and retrogradely labeled sites, while the changes were more profound for RV-∆G infection. Finally, we demonstrated a proof-of-concept strategy for more comprehensive high-order circuit tracing of a specific target nucleus by combining rAAV2-retro, RV, and rAAV tracers.ConclusionsDifferent multi-trans-synaptic and mono-synaptic retrograde viral tracers exhibited discrepant neurotropism within certain brain regions, even cortical layer preference. More neurotoxicity was observed under RV-∆G infection as compared with rAAV2-retro. By combining rAAV2-retro, RV, and rAAV tracers, high-order circuit tracing can be achieved. Our findings provide important reference for appropriate application of viral tracers to delineate the landscape and dissect the function of neural network.

Analysis of the Capacitor-Aided Meat Grinder Circuits for an Inductive Pulsed Power Supply

The major strengths of inductors in energy density and power density make an inductive pulsed power supply (IPPS) a promising option for pulsed power supplies in an electromagnetic launch system. Among the circuits for an IPPS, the capacitor-aided meat grinder circuits constitute an important branch. An analytical method for the working processes of these circuits is proposed in this paper. The core of this method is the decoupling of a high-order circuit into the superposition of a resistor–inductor first-order equivalent subcircuit and a resistor–inductor–capacitor second-order equivalent subcircuit. The validity and accuracy of this method have been verified through comparison with a numerical simulation. The results show that this method possesses both satisfactory accuracy and excellent computational speed. With the same circuit parameters and time step, the time cost of this method is three orders of magnitudes lower than the time cost of a numerical simulation. Moreover, this method contributes to more intuitive understanding and more essential insight into the working principles of the capacitor-aided meat grinder circuits.

Improved Wheeler Cap Method Based on an Equivalent High-Order Circuit Model

The conventional Wheeler cap method usually produces accurate radiation efficiency of small antennas when the antennas under test (AUTs) operate as a simple series or a parallel RLC resonance circuit. However, this method often gives unreliable radiation efficiency if the AUT has a complicated operating principle such as circular polarization (CP), multiple resonances, or broad-band properties. In this paper, we propose an improved Wheeler cap method based on the equivalent high-order circuit model including transformers to provide accurate radiation efficiency, although the AUT does not operate as a simple resonance circuit. For building equivalent high-order circuit models, a method for estimating the initial values of a genetic algorithm (GA) is also proposed, which effectively reduces the searching space and improves the convergence of the optimization. To verify the proposed method, we measure the radiation efficiency of a CP microstrip antenna, a UHF RFID tag antenna, and a triple-resonance microstrip antenna.

Nonlinearity Analysis of Closed-Loop ΣΔ Micro-Mechanical Accelerometer

A high-order interface circuit based on sigma-delta (ΣΔ) modulation is advantageous to enhance the resolution and reduce the quantization noise of micro-accelerometer, while the performance is restricted by the effect of nonlinearity of op-amp, electrostatic force feedback and quantizer. A fifth-order closed-loop ΣΔ capacitive accelerometer is proposed in this paper and a theoretic nonlinearity of the accelerometer was investigated. The nonlinear behavioral models based on SIMULINK are given in the paper. The simulation and test result are presented through optimization based on the nonlinearity analysis at last.

High-order circuit-level thermal model of vertical-cavity surface-emitting lasers

A high-order equivalent circuit model of vertical-cavity surface-emitting lasers (VCSEL) is introduced by virtue of the rate equations. This model accounts for both thermal and spatial dependences of VCSEL characteristics. A four-term Bessel-series expansion for the VCSEL carrier number is utilised to achieve good accuracy. A zero-order Laguerre–Gaussian beam is utilised for describing the photo distribution to simplify the computation. A general diode sub-circuit, instead of a complicated polynomial expression, is adopted to model the current–voltage relationship. This model is fast, accurate and scalable. Moreover, it can be readily used in SPICE-like circuit simulators. Numerical examples are included to validate this model and show that this model exhibits much improved accuracy than the previously published models.

A Modified Wheeler Cap Method for Efficiency Measurements of Probe-Fed Patch Antennas With Multiple Resonances

We propose a modified Wheeler cap method to accurately measure the radiation efficiency of patch antennas with multiple resonances by modeling their impedance as a high-order circuit model. The radiation efficiency is obtained from the power consumption ratio between the radiation and loss conductances using a circuit model we developed. Our technique is validated by measuring the efficiencies of a circularly polarized microstrip patch antenna and a triple-band microstrip patch antenna. The measurement results are in close agreement with those produced by simulations, whereas the Wheeler cap method with a series-(or parallel-) resonant circuit model is shown to be unreliable.

A general class of voltage-mode and current-mode active-only filters

This paper presents voltage-mode and current-mode capacitorless and resistorless filters with a general class of circuit transfer functions using only operational amplifiers (OAs) and operational transconductance amplifiers (OTAs). The proposed circuits can realize various high-order circuit characteristics by a suitable choice of the current outputs of the OTAs. The circuit characteristics can be electronically tuned through adjustment of the transconductance gains of the OTAs. The cascade realizations of high-order filters are also discussed, using the proposed configurations. Some examples are given, together with simulated results by PSPICE. The circuit configurations are very suitable for implementation in both bipolar and CMOS technologies.

SYNCHRONIZATION OF HIGH-DIMENSIONAL CHAOS GENERATORS BY OBSERVER DESIGN

In this Letter a method for synchronizing hyperchaotic systems described by ordinary differential equations (ODEs) as well as functional differential equations (FDEs) is illustrated. The technique, which exploits the concept of observer from system theory, is at first applied for synchronizing an example of high-order circuit. A remarkable feature is that hyperchaos synchronization is achieved via a scalar signal. Successively, the tool is applied for synchronizing an example of high-dimensional chaos generator, represented by a cell equation in Cellular Neural Networks with delay. Finally, the advantages of the proposed approach are discussed in detail.

Alternative robust servo-control system and its digital control

An alternative approach to the design of a servomechanism for a continuous system is presented and its digital control is considered. The proposed design of the digital control system is based on the quadratic criterion function for a continuous system, and a smooth control input is given as the output of a high-order sample-hold circuit, which is derived from the characteristics of the reference signal and disturbances.

Computationally Efficient Method of Calculations Involving Lumped-Parameter Transmission-Line Models

Computations involving ladder networks may be tedious if many elements are present. Lumped-circuit iterative models are traditional approximations of transmission lines and have been used well before [1]. The number of sections used to approximate the transmission line is limited by the computational expense involved in analyzing a high-order circuit. This paper develops a closed-form expression for the voltage transfer ratio for ladder networks as a function of the number of sections. Presently, lumped-circuit models [1]-[5] are analyzed using loop-current or node-voltage equations, both time-consuming and costly. The closed-form expression developed in this paper allows one to perform rapid circuit calculations for two-conductor lines, even if the number of sections is large (e.g., 50 sections or more) with very little computational effort.