Electrical Stress Analysis Research Articles

A New Approach to the Analysis of Electromagnetic FEM Simulations Results at Electric Field Singularities

A new methodology to the analysis of the results of Finite-Element Modeling (FEM) simulations at electric field singularities is proposed. The method, that can be easily applied in the post-processing phase of the electromagnetic FEM analysis workflow, is based on the weighted averaging of the calculated electric field magnitude within small volumes including the singularity point under investigation. In the paper, the proposed approach is applied to the electrical stress analysis of a high-voltage device modeled by means of a commercial electromagnetic FEM tool. In comparison to the conventional metric of the maximum field evaluation usually adopted for the analysis of electrical stress in insulators, our approach features several advantages: (i) the outcome of the analysis is independent of the numerical grid refinement at the singularity, thus allowing direct comparison of calculated electric field with the material dielectric strength; (ii) the method is robust against slight modifications of the geometrical shape of the singularity; (iii) on the other hand, for a given shape, the analysis outcome responds to significant variations of the singularity size or, in other words, of its sharpness; (iv) in the analysis of highvoltage devices, the approach can be applied for the estimation of the discharge volumes corresponding to different singularity types of different device geometries. In the paper, the new methodology is explained in details and is applied to simple but significant case studies.

Electrical Stress Analysis of Switching Transients in 115 kV High Voltage Substation

This paper presents electrical stress analysis from capacitor bank switching in a 115 kV substation. The actual data of all equipment in substation are used in the simulated circuit by using ATP/EMTP program. The cases study focused on the determination of proper value of series reactor, effect of circuit breaker pole discrepancy on inrush current, line model selection and load variation. Electrical stress from energizing inrush current as well as transient recovery voltage and rate of rise of recovery voltage imposed on power circuit breaker during capacitor bank has been analyzed. The obtained results are used as guidelines for analysis of the electric stresses on substation equipment while capacitor banks are energized. Moreover, those results can be used to select the proper rating of circuit breakers to withstand the electric stresses in the transmission network.

Current output hard‐switched full‐bridge DC/DC converter for wind energy conversion systems

A current output hard-switched full-bridge (HSFB) converter is presented with an intermediate high-frequency transformer as an option of a wind energy conversion system (WECS). The wind turbine simulator, based on an induction machine driving a three-phase permanent magnet synchronous generator, simulates practical wind turbine characteristics. A comparative analysis of electrical stresses on the switches of the boost converter and the current output HSFB converter is carried out at different wind speeds and maximum operational power point based on their mathematical models. The control system of the current output HSFB converter is illustrated. Then two dynamic responses of the combined mechanical and electrical systems of the WECS are investigated, under wind speed step changes. Simulation and experimental results demonstrate the feasibility and stability of a current output HSFB converter-based WECS.

Conductive atomic force microscopy studies on dielectric breakdown behavior of ultrathin Al2O3 films

Ultrathin films of Al2O3 prepared by atomic layer deposition have been subjected to local electrical stress analysis using conducting atomic force microscopy. The loss of local dielectric integrity through current leakage in these extremely thin films is studied using scanning spreading resistance imaging. Our experimental results shows that repeated voltage stress progressively increases number of leakage spots. While the density of leakage spots increase with higher applied bias for thin oxide films, initial increase and reduction in leakage spots are observed for thick films.

Stress Mechanism about Field Lightning Surge of High Voltage BJT Based Line Driver for ADSL System

In this paper, we have verified stress root caused by lightning surge in High voltage BJT based line driver of ADSL telecommunication and created failure mechanism. To reproduce damages in Line driver, we have applied STD surge waveform in operating condition, which is specified in IEC-6000-4-5, to component and board level. Visual isolation for Damage root was conducted with Real-time Electrical Stress Analysis (RTESA) utilizing Photon Emission Microscopy (PEM). The surge made with input of Tx output created junction breakdown of amplifier, which is made of HVBJT cells, and also caused current crowding from Vcc (supply voltage). In case of Positive pulse, current crowding was observed from between Collector and Vcc (+)12V. For negative pulse, at between Emitter and Vee (−)12V, current crowding was found. For both cases, device damage level was the same. All of these could be considered as transient latchup phenomenon created in BJT cell. Applying temporary clamping diode to line driver Tx, we have conducted Board level surge injection test. As a result, with the correlation between surge level from component level reproduction test and the one from system level, we have decided field lightning surge damage level and set up line driver protection margin.

Field Failure Mechanism Investigation of GaAs based HBT Power Amplifier Mmodule (PAM)

In this paper, field failure analysis of GaAs based HBT Power Amplifier Module (PAM) for Wireless Handset was conducted by utilizing Photoemission Spectrum analyzer (PSA) and Real-time Electrical Stress Analysis (RTESA) method. And, by repeating the failures intentionally, we could have created a failure mechanism. In Case of field failure PAM, among the balanced amplifiers, damaged HBT finger array were turned-on at degraded voltage (Vref=1.4V) as compared to normal applied reference voltage (Vref=3.0V), and high current was observed at reference voltage control circuit. Failure level was measured with Electrostatic Discharge (ESD) test. As a result, Vcc2 (Supply voltage) common mode ESD (PD & ND-mode) level were at the lowest as 1.6kV (Class I, Ref. JESD22-A114-B). In addition, all degraded reference voltage, DC characteristics, and Steady-state photoemission profile after ESD damage presented the same result as field failure sample. Also, ESD damage roots defined with failure mechanism could have verified as real-time photoemission 2D profile. We acquired results that PD and ND mode damage root thought real-time photoemission profile were different. There are various failure factors to cause PAM lifetime degradation. With this analysis in the report, as a conclusion, we could have proved that damages caused by ESD are the main reason for PAM field failure. Especially ESD which is inserted to GND in Vcc2 common mode (PD & ND-mode) was the major factor of PAM reliability degradation.

Analysis of Electrical stresses in AC Switches Used for Control of Small Power Motors Present in Household Appliances

This paper describes a study on electric and thermal stresses induced in bidirectional switches used for control of small power motors present in household appliances, in order to find out the possible weakness of the current solution generally made of a triac and to determine the requirements for new dedicated devices in the ASDTM technology. First, a behavioral analysis of these motors must be performed and the interactions between the switch and the load have to be well defined.