Effects Of Voltage Rise Time Research Articles

Influence of Rise Time and Fall Time on Surface Discharge Characteristics of PEEK Under Positive Repetitive Square Voltage

In this paper, the surface discharge current pulses of PEEK (polyether-ether-ketone) under positive repetitive square voltage are measured. The effects of voltage rise time and fall time on pulse parameters of discharge current, instantaneous voltage of discharge and time-lag of discharge are analyzed in detail. The results show that the amplitude of discharge current and the instantaneous voltage of discharge decrease, and the time-lag of discharge and the dispersion of time-lag increase with the increase of voltage rise time. With the increase of voltage fall time, the amplitude of discharge current decreases and the instantaneous voltage of discharge, the time-lag of discharge and the dispersion of time-lag increase. To analyze the influence mechanism of voltage rise time and fall time on surface discharge, the accumulation of surface charge under repetitive square voltage is regarded as a periodic process. Besides, the correlation between forward discharge and back discharge in the process of discharge is analyzed, and the development of discharge is analyzed by using the time-lag theory. Furthermore, the relationship between instantaneous discharge voltage and voltage slew rate is revealed, and the surface charge accumulation processes under different voltage rise times and fall times are compared to reveal the influence mechanism of rise time and fall time on the surface discharge under positive repetitive square voltage.

Effect of Voltage Rise Time on the Efficiency of Electrodynamic Dust Shield

Electrodynamic dust shield (EDS) has been proposed as a potential anti-dust solution for terrestrial solar photovoltaic (PV) power generation in dusty environments. EDS typically uses square wave alternating high voltage, but the actual voltage waveform on the EDS is trapezoidal, with the voltage rise time dependent on the high voltage source's current capacity, especially for real-world applications, where the EDS devices’ dimensions are large. It is therefore necessary to address the effect of voltage rise time on EDS efficiency. In this study, we measured the EDS efficiency by keeping the peak-to-peak voltage constant at 6 kVpp while varying the voltage rise time by adjusting the high voltage source's maximum output current from 0.2 to 40 mA, corresponding to voltage rise time from about 100 ms to a fraction of a millisecond. The EDS was operated in both the single-operation mode and the cyclic-operation mode. In the single-operation mode, voltage rise time affected the EDS efficiency in a complex manner and showed interactions with other factors. In the cyclic-operation mode, with the three faster voltage rise times the EDS efficiency was statistically indistinguishable at about 33%, but it became significantly lower, at 14%, with the slowest voltage rise. The finding shows that high voltage sources should be able to provide sufficiently fast voltage rises for EDS to be efficient in removing dust from solar PV modules.

Particle-in-Cell Demonstration of the Effect of Voltage Rise Time on Phase Synchronization in Two Parallel Relativistic Backward-Wave Oscillators

This paper demonstrates the effect of voltage rise time on phase synchronization in two parallel relativistic backward-wave oscillators (RBWOs) through 3-D particle-in-cell simulations. With a short rise time, the axially symmetrically mode is excited, the frequency spectrum is pure for both RBWOs, and phase synchronization between the two microwaves is realized. As the rise time increases, asymmetric modes appear in one or two channels, mode competition occurs, and phase synchronization cannot be achieved. This can be explained as the transient excitations in the RBWOs initiated by the current variation in beam head, whose magnitudes are inversely proportional to the rise time. It is suggested that phase synchronization can be obtained at a larger voltage rise time in the RBWOs with stronger resonant characteristics. Furthermore, an external signal can suppress the asymmetric mode and control the relative phase of output microwaves in the two RBWOs.

Transient performance of SiC MOSFETs as a function of temperature

This research was completed to study the effects of extreme transient conditions on Silicon Carbide MOSFET devices. Two different transient conditions that are common in power converters were studied in this paper. The first is effects of voltage rise time, or dV/dt, on these devices. The second is the effects of current pulses with short pulse width and high peak currents. Both of these tests were conducted at temperatures of 150 °C to determine the performance of these devices in high stress environments. For both of these experiments, testing apparatus had to be designed and built to create these specific conditions.

Magnetic-spiker excitation of gas-discharge lasers

A review is presented on the use of magnetic-spiker circuits to electrically excite rare-gas-halide and CO2 gas-discharge lasers. The design and operation of the diode, switch, overshoot, and charge modes of magnetic-spiker excitation will be described. Special emphasis has been placed upon understanding the dynamical behaviour and saturation properties of the magnetic core material at high frequencies. The effect of voltage risetime, preionization, pulse-forming network design, and prefire on laser performance is also described. Experimental data are presented on a new and very simple magnetic-spiker circuit called the modified overshoot mode. A relatively long optical pulse magnetic-spiker KrF laser is also desribed which uses self-timed corona preionization initiated by the spiker circuit. The use of magnetic-spiker excitation to produce high output laser energies, high repetition rates, and long optical pulses is discussed. Applications of magnetic-spiker lasers in the field of medicine, microelectronics and materials processing will be reviewed.