This paper reports an energy-efficient permanent magnet (PM) zero-holding-energy magnetic contactor (ZMC) that consumes no energy while maintaining an open or closed state. Conventional solenoid magnetic contactor (MC) technology has several critical drawbacks, including high continuous energy consumption, continuous vibration, and low reliability. The proposed ZMC substantially reduces energy consumption and heat generation, produces no vibration, and provides increased reliability. Traditional MC analysis typically requires computationally expensive finite element analysis (FEA). To reduce the analysis costs, a recently proposed fast and accurate nonlinear transient path energy method (NT-PEM) is utilized to significantly reduce analysis time and costs. Analysis accuracy was verified experimentally using a fabricated ZMC prototype. The economic and environmental benefits of the proposed ZMC confirm its significant potential as an energy-efficient eco-friendly alternative to traditional MC technology. ZMC is particularly promising for vehicular micro-grids due to the prolongation of the lifetime of batteries owing to reduced energy consumption.

Energy-Efficient Eco-Friendly Zero-Holding-Energy Magnetic Contactor for Industrial and Vehicular Applications

Improving the efficiency and end-use of energy distribution can significantly reduce global energy consumption. As the magnetic contactor (MC) is the most common switchgear used for control in most grids, minimizing its energy consumption has motivated the development of a permanent magnet (PM) MC that exhibits several advantages over conventional solenoid MCs. However, analyzing the transient magnetic behavior of a PM MC requires computationally expensive 3D finite element analysis (FEA). Herein, a modified version of a recently proposed nonlinear transient path energy method (NT-PEM) is proposed as an analytical alternative to FEA. Within the modification to NT-PEM, a new topology for nonlinear dynamic magnetic equivalent circuit (ND-MEC) is proposed with a methodology for accurate evaluation of stray and leakage flux path parameters. For coil leakage reluctances, a novel path function based on a conchoid’s arc is proposed. For stray reluctances, a path function based on the average length of an elliptical arc is proposed. This path function, along with the proposed permeability correction for nonlinear core reluctance calculation routines, led to a four-fold reduction in NT-PEM analysis time from the original version of the proposed method. The feasibility of the proposed NT-PEM is verified via comparison with commercial 3D FEA and experimental data obtained from a PM MC with a single coil and single PM. NT-PEM and FEA equally displayed accurate results, indicating that NT-PEM is a promising computationally efficient alternative to FEA owing to significantly reduced analysis time, which is essential when considering numerous designs and design parameters.

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Analysis of Nonlinear Dynamics of Permanent Magnet Magnetic Contactor via Novel Computationally Efficient Analytical Method Considering Stray and Leakage Fluxes

This paper presents in details a study, in order to detect an electrical serial arc, on a DC network, by using an electric antenna. An electric signature, linked to the arc phenomenon and independent of the circuit impedance, is identified as a good marker for the detection. An electric antenna is proposed, in order to detect this signature: the detection principle is explained and studied by both experiments and simulation, and an optimized design is proposed. The chosen antenna is tested by creating a serial arc on an airborne terminal block. At last, perspectives are given in order to assess the detection performances and robustness.

Study of electric arc behavior by radiated field analysis for HVDC airborne application

As described in this paper, we proposed the adoption of polyacrylic acid (PAA) with H2O, which becomes PAA + H2O mixture gel, as an ablation medium for arc quenching in a low-voltage DC circuit breaker. It is well known that H2O is a highly arc-quenching medium, but it has been difficult to use H2O in liquid phase directly as an arc-quenching medium. The arc performance of PAA + H2O mixture gel was studied using numerical and experimental approaches. Numerical thermofluid simulation was conducted to obtain the arc temperature and gas flow distribution at different H2O mixing ratios in PAA + H2O gel. To consider ablation of PAA + H2O gel, a method of alternately arranging PAA and H2O in the ablation wall was also proposed. Calculation results demonstrate that increasing the H2O mixing ratio in PAA + H2O mixture gel makes the arc narrower in the temperature and electrical conductivity distributions. The experimentally obtained results also indicate that arcs confined in PAA + H2O mixture gel with higher H2O mixture become narrower than those in PAA or other materials. Moreover, arcs confined by PAA + H2O mixture gel with higher H2O mixing ratio enhance the arc resistance rapidly. The results suggest that PAA + H2O mixture gel can have higher arc-quenching performance than pure polymers.

Numerical study of polymer-ablation arc with polyacrylic acid + H2O mixture

Conventional switchgear such as relays and magnetic contactors (MC) continuously consume energy to maintain an open and/or closed state, contributing to unnecessary energy consumption, dissipation, and heating. The minimization of such losses has become an important topic in recent years, leading to the development of more energy-efficient technologies such as permanent magnet (PM) MCs. However, concerns regarding the safety and reliability of PM MCs hindered the development of a zero-holding-energy PM MC (ZMC) due to the loss of the controllability in emergency scenarios (such as power outages). This paper presents a novel piezoelectric emergency subsystem (PES) that monitors the state of the input power source and opens the ZMC in emergency circumstances. The proposed PES consumes no energy upon charging its piezoelectric element, thus allowing the holding energy of the complete ZMC-PES system to remain zero without affecting the normal operating regimes of the ZMC. Because the application of the PES causes the ZMC to act as a normally-open MC, the ZMC-PES system can be conveniently controlled using traditional solenoid MC control strategies, enabling an easy transition from the conventional to the proposed technologies. The feasibility of the proposed PES is verified using data obtained from a fabricated prototype of a complete ZMC-PES system. The proposed system is promising not only for industrial grids, but also for vehicular microgrids as in electric aircrafts and ships where energy efficiency translated into the increased battery lifetime.

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Novel Piezoelectric Emergency Opening Sub-System to Improve the Safety and Reliability of Zero-Holding-Energy Permanent Magnet Magnetic Contactors

The characteristics of arc in DC contactors are a major factor affecting the breaking performance of small-sized contactors. Based on the magneto hydrodynamics (MHD) model, this paper obtains the temporal and spatial distribution of arc temperature by taking DC arc as its research objective and H 2 , N 2 and He as arc extinguishing media. A removable arc chamber was adopted to build up a DC experimental circuit, in which a double-contact structure made of pure copper was selected, with a contact diameter of 10mm and a contact spacing of 2mm, to measure the influence of magnetic field, pressure and breaking speed on the characteristics of DC arc. The simulation and experimental results suggest that H2 has a stronger arc extinguishing capability than N2 and He when used as an arc extinguishing medium for switches; the increase in pressure contributes to the reduction in arcing time but the reduction is not monotonic, and a pressure of 3–4atm is desirable; the increase in magnetic flux density and breaking speed can effectively shorten the arcing time, and a breaking speed of 0.5m/s and magnetic flux density of 50mt are desirable.

Study on factors influencing the characteristics of arc in DC contactors

In this paper, a 72.5kV vacuum arc extinguishment chamber is studied through establishing 3D field domain models based on the structures of 1/2 and 1/3 turn coil longitudinal magnetic field contacts with different numbers of slots, at the same time, 3D static simulation and eddy current field simulation were conducted using the finite element method and physical environment method to analyze the influence of different numbers of slots and coil structure on the distribution of longitudinal magnetic field and lag time. To reflect the coupling effect between electric field, magnetic field and air current field, a vacuum arc magnetic fluid model was established after analyzing the existing vacuum arc models and characteristics of vacuum arc under different breaking conditions. After analyzing the instability of vacuum arc, we obtained a non-linear third order ordinary differential equation for electric arc in vacuum breakers. Through adjusting the parameter values relating to vacuum arc in the equation, it is found that the system exhibits a chaotic behavior.

Wenxiang Shang

Papers

Study on factors influencing the characteristics of arc in DC contactors

Research of the chaos characteristic of the vacuum circuit breaker with coupled physical field simulation