Reduced-order models of series resonant inverters in induction heating applications

From the controller design framework, a simple analytical model that captures the dominant behavior in the range of interest is the optimal. When modeling resonant circuits, complex mathematical models are obtained. These high-order models are not the most suitable for controller design. Although some assumptions can be made for simplifying these models, variable frequency operation or load uncertainty can make these premises no longer valid. In this work, a systematic modeling order reduction technique, Slowly Varying Amplitude and Phase (SVAP), is considered for obtaining simpler analytical models of resonant inverters. SVAP gives identical results as the classical model-order residualization technique from automatic control theory. A slight modification of SVAP, Slowly Varying Amplitude Derivative and Phase (SVADP) is applied in this paper to obtain a better validity range. SVADP is validated for a half-bridge series resonant inverter (HBSRI) and for a high- order plant, a dual-half bridge series resonant inverter (DHBSRI) giving analytical second-order transfer functions for both topologies. Simulation and experimental results are provided to show the validity range of the reduced-order models

Implementación en FPGA de un sistema de medida de impedancia armónica de circuitos resonantes en serie basado en el algoritmo lock-in

En esta ponencia se presenta un sistema digital implementado en FPGA (field programmablegate array) cuya función es la medida en tiempo real de la impedancia del primer armónico deuna carga de una cocina de calentamiento por inducción. La etapa inversora de la cocinaimplementa la topología semipuente resonante serie de media frecuencia (25 kHz – 75 kHz)cuyo circuito de carga consiste en un condensador en serie con el sistema inductor‐recipiente(inductor planar acoplado con un recipiente). En una primera aproximación, la impedancia delcircuito puede modelarse como una red equivalente R‐L‐C, sin embargo, la impedanciaequivalente depende de múltiples factores tales como el material del recipiente, alineamientoentre el recipiente y el inductor, temperatura o frecuencia de trabajo. Por dicha razón, unacaracterización en tiempo real de la carga es deseable para realizar un correcto control de laetapa inversora. El sistema de identificación calcula la impedancia del primer armónico de lacarga aplicando el algoritmo lock‐in de fase dual a la corriente que atraviesa el inductor y a latensión de salida del inversor. Dicho algoritmo ha sido descrito en VHDL (very high speedintegrated circuit hadware description language) e implementado en una FPGA de Xilinx. Laprecisión del algoritmo ha sido verificada mediante simulación a través de una herramienta desimulación mixta (analógica‐digital). Finalmente, el sistema ha sido verificadoexperimentalmente

The Discovery and Mass Measurement of a New Ultra-Short-Period Planet: K2-131b

FWN – Publicaties zonder aanstelling Universiteit LeidenStars and planetary system

Reduced-Order Model of a Half-Bridge Series Resonant Inverter for Power Control in Domestic Induction Heating Applications

When modeling resonant inverters considering the harmonic balance method, the order of the obtained transfer functions is twice the state variables number. This is explained because two components are considered for each state variable. In order to obtain a simpler transfer function model of a halfbridge series resonant inverter, different techniques of model order reduction have been considered in this work. Thus, a reduced-order model has been obtained by residualization providing much simpler analytical expressions than the original model. The proposed model has been validated by simulation and experimentally. The validity range of the proposed model is extended up to a tenth of the switching frequency. Taking into account the great load variability of induction heating applications, the proposed reduced-order model will allow the design of advanced controllers such as Gain-Scheduling