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.

Miniaturized Microstrip Wilkinson Power Divider With Harmonic Suppression

Abstract: A microstrip Wilkinson power divider with harmonic suppression and size reduction is presented in this letter. The proposed power divider not only effectively reduces its occupied area to 36.5% of the conventional design at 2.65 GHz but also has higher order harmonics suppression. From the measured results, a 29 dB suppression for the third harmonic and a 34 dB suppression for the fifth harmonic are achieved while maintaining the characteristics of a conventional Wilkinson power divider. Based on a 15 dB return-loss criteria, the measured fractional bandwidth is 48%. At an operation frequency of 2.65 GHz, the insertion losses are better than 3.4 dB, the return loss is 27 dB, and the isolation is better than 22 dB.

Control of square-wave inverters in high power hybrid active filter systems

Abstract: This paper presents a new control scheme for a hybrid parallel active filter (HPAF) system intended for high-power applications-up to 100 MW nonlinear loads-to meet IEEE 519 recommended harmonic standards. The active filter inverter is realized with small-rated (1%-2% of the load rating) square-wave inverters operating at the dominant harmonic frequencies. The proposed system achieves harmonic isolation at desired dominant harmonic frequencies, such as the fifth and seventh, even in the presence of supply voltage harmonic distortions. A novel method of active filter inverter DC-bus control, as proposed here, achieves power balancing by exchanging energy at the fundamental frequency and at the dominant harmonic frequency (such as the fifth). The proposed square-wave inverter-based HPAF system provides improved filtering characteristics as compared to the conventional passive filter and is expected to be cost effective for high-power nonlinear loads compared to the conventional passive filter or other active filtering solutions. The concept of harmonic isolation at dominant harmonic frequencies by square-wave inverters with the proposed control scheme is validated by simulation results.

Decentralized Sliding Mode Control of WG/PV/FC Microgrids Under Unbalanced and Nonlinear Load Conditions for On- and Off-Grid Modes

Abstract: This paper presents a new decentralized robust power/current/voltage/frequency control strategy for islanded and grid-connected modes to enhance power-sharing and small- and large-signal stability of a wind/photovoltaic/fuel cell microgrid and improve its performance for nonlinear and unbalanced loads. First, the distributed energy resources are modeled for unbalanced voltage condition. Then, in order to improve power sharing, regulate voltage and active/reactive powers injected by these resources, and moreover, harmonic and negative-sequence current control in the presence of nonlinear and unbalanced loads, three separate controllers for positive-sequence voltage and power control and negative sequence current control are designed based on the sliding mode control, Lyapunov function theory, and fractional-order sliding mode control, respectively. The theoretical concept of the proposed control strategy, including the mathematical modeling of microgrid components, basic theorems, controller design procedure, and robustness/closed-loop stability analysis, is outlined. Also, this direct power/current/voltage/frequency control scheme is governed by a hierarchical control scheme that exploits a voltage compensation scheme and harmonic virtual impedance loop. To show the effectiveness of the proposed control scheme, offline time-domain simulation studies are performed on a wind/photovoltaic/fuel cell microgrid with nonlinear and unbalanced loads in MATLAB/Simulink environment and the results are verified by OPAL-RT real-time digital simulator.

High power time domain measurement system with active harmonic load-pull for high efficiency base station amplifier design

Abstract: A measurement system combining vector corrected waveform measurements with active harmonic load-pull extends, for the first time, real-time experimental waveform engineering up to the 30 W power level. This novel harmonic load-pull approach is demonstrated on a 4 W LDMOS device. A 20% increase in maximum output power to 4.7 W without degrading gain and efficiency was realized.

Phase-matched frequency doubling at photonic band edges: efficiency scaling as the fifth power of the length.

Abstract: By exploiting the unique properties of periodic stratified media we demonstrate simultaneously phase matching and enhancement of the optical field under second order nonlinear interaction. This leads to a second harmonic efficiency growth faster than the fifth power of the structure length, far better than the usual quadratic behavior associated with second order nonlinear effects.