Flexible Control Technique Research Articles

Magnetically tightened multifunctional phase change materials

As a non-contact, real-time, accurate, and flexible control technique, the magnetic field has been widely utilized in a variety of applications, including industrial grab, robot drives, medical assistance, etc. However, non-magnetic phase change materials (PCMs) are difficult to manipulate with magnetic fields. Recently in <i>Nature Communications</i>, He et al. innovatively proposed magnetically tightened form-stable PCMs with the integrated multi-functions of being leakage-proof, having highly thermal/electrical conductivities, robust mechanical strength, dynamic assembly, and shape reconfiguration by introducing hard magnetic particles. Additionally, they developed free-standing temperature control and high-performance thermoelectric conversion systems based on magnetically tightened form-stable PCMs.

Control of Single-Phase Power Converters Connected to Low-Voltage Distorted Power Systems With Variable Compensation Objectives

This paper presents a flexible control technique for power electronics converters, which can function as an active power filter, as a local power supply interface, or perform both functions simultaneously. Thus, it can compensate for current disturbances while simultaneously injecting active power into the electrical grid, transforming the power converter into a multifunctional device. The main objective is to use all the capacity available in the electronic power converter to maximize the benefits when it is installed in the electricity grid. This objective is achieved by using the orthogonal current decomposition of the conservative power theory. Each current component is weighted by compensation coefficients ( $k_i $ ), which are adjusted instantaneously and independently, in any percentage, by means of load conformity factors ( $\lambda _i $ ), thus providing online flexibility with respect to the objectives of compensation and injection of active power. Finally, simulated and experimental results are presented to validate the effectiveness and performance of the proposed approach.

Dimmable electronic ballasts by variable power density modulation technique

Dimming can be accomplished commonly by switching frequency and pulse density modulation techniques and a variable inductor. In this study, a variable power density modulation (VPDM) control technique is proposed for dimming applications. A fluorescent lamp is operated in several states to meet the desired lamp power in a modulation period. The proposed technique has the same advantages of magnetic dimming topologies have. In addition, a unique and flexible control technique can be achieved. A prototype dimmable electronic ballast is built and experiments related to it have been conducted. As a result, a 36WT8 fluorescent lamp can be driven for a desired lamp power from several alternatives without modulating the switching frequency.

A multi-objective control strategy for grid connection of DG (distributed generation) resources

Abstract This paper presents a flexible control technique for connection of DG (distributed generation) resources to distribution networks, especially during ride-through on faulty grid. This strategy is derived from the abc/αβ and αβ/dq transformations of the ac system variables. The active and reactive currents injected by the DG source are controlled in the synchronously rotating orthogonal dq reference frame. The transformed variables are used to control the VSI (voltage source inverter) which connects the DG to the distribution network. Using a P.L.L. (phase locked loop) in circuit of proposed control technique, the angle of positive sequence has been detected, in order to synchronize the currents to the distribution network. The proposed control technique has the capability of providing active and reactive powers and harmonic currents to nonlinear loads with a fast dynamic response. Simulation results and mathematical analysis have been completed in order to achieve a reduced THD (total harmonic distortion), increased power factor and compensated load’s active and reactive powers. The analyses show the high performance of this control strategy in DG applications in comparison with other existing strategies.

An on-chip 96.5% current efficiency CMOS linear regulator using a flexible control technique of output current

This paper proposes an on-chip 96.5% current efficiency CMOS linear regulator using a flexible control technique of output current (FCOC). By the use of the FCOC technique, the proposed circuit realizes flexible output current drive according to the load current variation. Therefore, the proposed linear regulator ran supply stable output voltage using the FCOC technique. The linear regulator is fabricated by double-metal 1.2-/spl mu/m CMOS technology. The number of transistors is 46 and the die size is 0.423 mm/sup 2/. The fabricated linear regulator achieves a fluctuation of output voltage less than 6.81 mV/sub p-p/ at a frequency of output current f(I/sub out/) ranging from 1.8 Hz to 100 MHz. Moreover, the fabricated on-chip CMOS linear regulator can achieve 96.5% current efficiency.