Harmonic

About: Harmonic is a research topic. Over the lifetime, 44833 publications have been published within this topic receiving 495922 citations. The topic is also known as: overtone & partial.

The Continuous Class-F Mode Power Amplifier

Abstract: This paper presents, for the first time the theoretical introduction and experimental validation of the "Continuous Class-F Mode Power Amplifier" that provides for a new design space for the design of high efficiency and broadband power amplifiers. Starting from the standard class-F mode, this work shows that it is possible to maintain constant or even improved output power and efficiency for coupled variations of fundamental and second harmonic impedances. The investigation was carried out on GaAs pHEMT devices and demonstrates that a near constant efficiency between 82% and 87% can be achieved along with a constant output power of 20dBm, over a wide range of fundamental and second harmonic loads.

A novel harmonic power filter

Abstract: A novel harmonic power filter system consisting of passive LC filters and voltage source pulsewidth-modulated (PWM) converters is described. This filter system has the merits of both conventional passive LC filters and conventional active power filters. The operating principle and a control scheme for the system are described. Compensation characteristics are discussed from both a theoretical and experimental point of view. The practicability and validity of compensation for large-capacity thyristor converters is experimentally demonstrated. >

Piezoelectric MEMS energy harvesting systems driven by harmonic and random vibrations

Abstract: Switching power conditioning techniques are known to greatly enhance the performance of linear piezoelectric energy harvesters subject to harmonic vibrations. With such circuits, little is known about the effect of mechanical stoppers that limit the motion or about waveforms other than harmonic vibrations. This work presents SPICE simulations of piezoelectric micro energy harvester systems that differ in choice of power conditioning circuits and stopper models. We consider in detail both harmonic and random vibrations. The nonlinear switching conversion circuitry performs better than simple passive circuitry, especially when mechanical stoppers are in effect. Stopper loss is important under broadband vibrations. Stoppers limit the output power for sinusoidal excitations, but result in the same output power whether the stoppers are lossy or not. When the mechanical stoppers are hit by the proof mass during high-amplitude vibrations, nonlinear effects such as saturation and jumps are present.

A Sensorless Rotor Temperature Estimator for Induction Machines Based on a Current Harmonic Spectral Estimation Scheme

Abstract: This paper proposes a sensorless rotor temperature estimator for small- to medium-sized mains-fed induction machines. With measurements obtained only from voltage and current sensors, the proposed estimator can capture the rotor temperature online. The rotor speed is first extracted from the stator current harmonic spectrum based on the estimated rotor slot and eccentricity harmonic frequencies. Then the inductances are estimated according to the induction machine equivalent circuit developed from the rotor flux field orientation. The stator winding resistance at ambient temperature is the only motor parameter needed as input in this stage. Once the inductances are obtained, they are fed into the rotor resistance estimation algorithm to yield an estimate of the rotor resistance. Finally, the rotor temperature is calculated from the linear relationship between the temperature and rotor resistance. The experimental results from different motors are shown to validate the proposed algorithms. The whole scheme is efficient and reliable and is therefore suitable for implementation in a motor overload protection relay to provide thermal protection against rotor overheating.

A three-phase active power filter operating with fixed switching frequency for reactive power and current harmonic compensation

Abstract: The performance and dynamic characteristics of a three-phase active power filter operating with fixed switching frequency are presented and analysed. The proposed scheme employs a pulse width modulation voltage source inverter and has two important characteristics. First, it operates with fixed switching frequency, and, second, it can compensate the reactive power and the current harmonic components of nonlinear loads. Reactive power compensation is achieved without sensing the computing the reactive component of the load current, thus simplifying the control system. Current harmonic compensation is done in the time domain. The principles of operation of the proposed active power filter along with the design criteria of the power and control circuit components are discussed in detail. Experimental results obtained from a 5 kVA prototype confirm the feasibility and the features of the proposed system. >