Equivalent circuit modeling in GaN wireless power transmission including stray inductance and capacitance by measuring radiated emission

We establish the method for estimating the stray elements of the GaN-WPT circuit by measuring the radiated emission around the GaN switching device. By controlling the circuit supply voltage, the spectrum peak shift due to the output capacitance of the GaN-HEMT is observed. It is found that these peak shift characteristics include the influence of both the stray wire inductance and stray capacitance. By the fitting using the series resonance model, the value of the stray inductance and stray capacitance can be estimated in the non-destructive measurement in the GaN-WPT circuit.

Equivalent Circuit Modeling and Analysis of Aerodynamic Vortex-induced Piezoelectric Energy Harvesting

Low-speed wind energy has potential to be captured for powering micro-electro-mechanical systems or sensors in remote inaccessible place by piezoelectric energy harvesting from vortex-induced vibration (VIV). Conventional theory or finite-element analysis mostly considers a simple pure resistance as interface circuit because of the complex fluid-solid-electricity coupling in aeroelastic piezoelectric energy harvesting. However, the output alternating voltage should be rectified to direct voltage to be used in practical occasions, where the theoretical analysis and finite-element analysis for complex interface may be cumbersome or difficult. To solve this problem, this paper presents an equivalent circuit modeling (ECM) method to analyze the performance of vortex-induced energy harvesters. Firstly, the equivalent analogies from the mechanical and fluid domain to the electrical domain are built. The linear mechanical and fluid elements are represented by standard electrical elements. The nonlinear elements are represented by electrical non-standard user-defined components. Secondly, the total fluid-solid-electricity coupled mathematical equations of the harvesting system are transformed into electrical formulations based on the equivalent analogies. Finally, the entire ECM is established in a circuit simulation software to perform system-level transient analyses. The simulation results from ECM have good agreement with the experimental measurements. Further parametric studies are carried out to assess the influences of wind speed and resistance on the output power of the alternating circuit interface and the capacitor filter circuit. At wind speed of 1.2 m/s, the energy harvester could generate an output power of 81.71 μW with the capacitor filter circuit and 114.64 μW with the alternating circuit interface. The filter capacitance is further studied to ascertain its effects on the stability of output and the settling time.

Equivalent-Circuit Modeling of Lossless and Lossy Bi-Periodic Scatterers by an Eigenstate Approach

The use of an eigenstate based equivalent circuit topology is proposed for the analysis and modeling of lossless and lossy bi-periodic scatterers. It can significantly simplify the design of this kind of surfaces, since it reduces the number of elements with respect to other general circuits. It contains at most only two admittances and two transformers depending on one unique transformation ratio. The real parts of these admittances can be assured to be non-negative, an interesting aspect in the modeling of lossy surfaces such as those present in asorbers. Moreover, due to the capability of decomposition into the eigenexcitations of the structure, the circuit provides important physical insight. Different cases of scatterers have been analyzed: symmetric and asymmetric, lossy and lossless. In all these cases, the modeling of the circuit admittances has been successfully achieved with a few RLC elements, positive and frequency independent. In the case of structures with symmetries, the transformation ratio directly reflects the physical orientation of the eigenexcitations of the scatterer. Furthermore, in the case of lossy scatterers but without symmetries, the resulting equivalent circuit reveals that their eigenexcitations are not linear polarizations, but elliptic polarizations whose properties are described by the complex transformation ratio.

Equivalent-Circuit Modeling of Lossless and Lossy Bi-Periodic Scatterers by an Eigenstate Approach

The use of an eigenstate based equivalent circuit topology is proposed for the analysis and modeling of lossless and lossy bi-periodic scatterers. It can significantly simplify the design of this kind of surfaces, since it reduces the number of elements with respect to other general circuits. It contains at most only two admittances and two transformers depending on one unique transformation ratio. The real parts of these admittances can be assured to be non-negative, an interesting aspect in the modeling of lossy surfaces such as those present in asorbers. Moreover, due to the capability of decomposition into the eigenexcitations of the structure, the circuit provides important physical insight. Different cases of scatterers have been analyzed: symmetric and asymmetric, lossy and lossless. In all these cases, the modeling of the circuit admittances has been successfully achieved with a few RLC elements, positive and frequency independent. In the case of structures with symmetries, the transformation ratio directly reflects the physical orientation of the eigenexcitations of the scatterer. Furthermore, in the case of lossy scatterers but without symmetries, the resulting equivalent circuit reveals that their eigenexcitations are not linear polarizations, but elliptic polarizations whose properties are described by the complex transformation ratio.