Extended fundamental frequency analysis of the LCC resonant converter

Fundamental frequency techniques are used to analyze the series-parallel resonant converter under heavy load conditions, both with a continuous, but distorted parallel capacitor voltage waveform, and with a discontinuous capacitor voltage waveform. The analysis is validated with results from an experimental prototype. The application of the technique to the parallel-loaded L-C resonant converter is also considered.     

Effective optimization for fuzzy model predictive control

This paper addresses the optimization in fuzzy model predictive control. When the prediction model is a nonlinear fuzzy model, nonconvex, time-consuming optimization is necessary, with no guarantee of finding an optimal solution. A possible way around this problem is to linearize the fuzzy model at the current operating point and use linear predictive control (i.e., quadratic programming). For long-range predictive control, however, the influence of the linearization error may significantly deteriorate the performance. In our approach, this is remedied by linearizing the fuzzy model along the predicted input and output trajectories. One can further improve the model prediction by iteratively applying the optimized control sequence to the fuzzy model and linearizing along the so obtained simulated trajectories. Four different methods for the construction of the optimization problem are proposed, making difference between the cases when a single linear model or a set of linear models are used. By choosing an appropriate method, the user can achieve a desired tradeoff between the control performance and the computational load. The proposed techniques have been tested and evaluated using two simulated industrial benchmarks: pH control in a continuous stirred tank reactor and a high-purity distillation column.     

Investigation of electron beam melting and refining of titanium and tantalum scrap

In this paper obtained experimental and theoretical data for Ti and Ta electron beam melting regeneration from waste products are presented. Different technological regimes and methods are realized and the obtained results are discussed. Element analyses of the impurities’ concentration of the materials before electron beam melting and refining (EBMR) and of the ingots after EBMR are compared. Statistical approach is applied for optimization of process parameters for Ti. Material losses less than 1% and oxygen concentration less than 400 ppm after EBMR of Ti scrap are achieved at 11.5–12 kW beam power and 0.09–0.14 mm/s casting velocity. The optimal process conditions and purification data for Ti refining by minimization of all impurities’ concentrations and the material losses at the same time are obtained at 11.25 kW electron beam power and 0.0835 mm/s casting velocity. For the performed experiments the best purification of Ta (99.985) is obtained at 24 kW beam power and 0.029 mm/s casting velocity, the residence times on the front side of the feeding block and in the liquid metal pool are 2 min and 5 min, respectively.     

Study of the DC biasing effect on insertion losses in high-frequency interconnections

The paper deals with an experimental investigation of the behavior of high-frequency Si/SiO₂/Al based interconnects when an extra DC bias voltage is applied, by means of which the conductor line changes the surface properties of the semiconductor substrate. By superposing a DC bias to the high-speed signal applied to the line, the insertion losses caused by the semiconductor substrate show a significant decrease over the observed frequency range. In order to study this effect a number of test samples containing several microstrip asymmetric transmission lines were prepared and measured. The obtained results suggest a way of controlling the performance and energy propagation of interconnects on semiconductor substrates. The observed effect can be successfully applied in high-speed blocks with tunable parameters.     

Einflu? des Pectins auf die elektrokinetischen Eigenschaften von Pulpesuspensionen aus ?pfeln

Apple pulp suspensions to which different kinds of pectin in concentration up to 500 g.m^–3 was added were studied electrophoretically. It was shown that the natural pectin exerts an essential influence upon the adsorption ability of the pectin added, and upon the electrokinetic potential of the tissue particles respectively.

     

A Frequency Multiplication Resonant Inverter With Constant Frequency Phase Control

The schematic and analysis of a voltage-fed resonant inverter are presented in this paper. The topology of the inverter allows operation of the resonant tank at higher harmonics and multiples of the switching frequency. The resulting loss in voltage gain is compensated through the use of multiple commutation poles employing low-cost modestly rated MOSFETs. The proposed topology can control power throughput at a fixed frequency through pole phase-shift modulation. Zero voltage switching is maintained down to no load and within the entire input voltage range. Measurements from a multimegahertz 100-W inverter confirm the theoretical predictions, as well as the suggested design and control approach.     

LCC resonant converter control for high power factor rectification

A resonant current feedback loop is shown to provide a simple and effective method of control for the series-parallel-loaded LCC resonant converter in high power factor rectification systems     

Analysis, design, and resonant current control for a 1-MHzhigh-power-factor rectifier

Fundamental frequency analysis is used to examine the LCC series-parallel loaded resonant converter with a capacitive output filter when operating as a high-power-factor rectifier. Optimum values are identified for the Q factor and voltage conversion ratio such that zero-voltage switching is just maintained, while minimizing the resonant circuit conduction losses. A simple resonant current control loop is shown to provide an effective mechanism of active control, achieving a high-quality input current waveform over a wide load range. Results are presented from a 1 MHz 160 W prototype     

Distant energy transfer for artificial human implants

The powering of human implants via inductive coupling has been an object of interest for the past two decades. This paper discusses some of the issues concerning a distant energy link used for supplying artificial human implants, operating at the frequency of 13.56 MHz. A procedure for the design of an energy-receiving coil is given for general applications. A design procedure is also developed, with focus on coils used for supplying human implants. The correctness of the analysis of this later design procedure has been verified by experimental results. Measurements with a human tissue simulant also show little deviation from the predictions.