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An adaptive power supply regulator based on pulse skip modulation (PSM) with fast transient response is proposed in this paper. The controller of the adaptive regulator includes a clock generator, a delayline, two flip-flops, two comparators, a pulse width generator and a NAND gate. For output voltage segmentation is used, the maximum conduction duty ratio of the power switch is not limited by the...
Among the third world countries from Asia and Africa, power quality is one of the biggest problem still persists because unaffordable high tech solutions. Voltage control problem due to an adequate reactive power compensation and its improper control results in frequent cascade tripping of electrical supply system. In this paper efforts are made to provide a low cost solution to provide exact reactive...
Most of the domestic, industrial and agricultural loads are inductive in nature which results in lagging power factor further corresponding to power losses at substation level to consumer level. To avoid this, capacitor banks at large scale are installed at the substation (near to the source). As every boon comes with a bane, capacitor banks too causes high frequency and high current transients during...
According to the specifications in IEEE 1894-2015, a transient process measuring device (TPMD) is developed to be used in the distribution system, and a line selection technique utilizing large pulse current is presented on this basis. When a single-phase grounding fault occurs, the distribution system is able to be instantly switched from grounding with small current to grounding with large pulse...
This paper analyzes the transient performance of wind turbines with direct-driven permanent magnet synchronous generators (PMSGs) and compares PMSG models for power system transient stability studies. The control strategy of a PMSG is introduced firstly. Afterwards, the transient performance of a PMSG is analyzed in detail based on the PMSG's operating mechanism. To represent PMSGs in transient stability...
To obtain impulse impedance characteristics for grounding device of transmission tower, a small and portable instrument is developed. It can stable output the 8/20 µs and 10/350 µs standard lightning currents with simultaneous measurement of the response transient voltage waveshapes, which simulates the currents of direct and indirect lightning strikes, respectively. Tests were made to an standard...
The vacuum interrupter is generally accepted as reliable circuit breaker in the medium voltage power system , but the operating thoroughly a high inductive loads and capacitive loads caused a significant damages with severe erosion in the surfaces both of cathode and anode vacuum Interrupter . This paper remedies both of arcing currents, chopping currents and prevents a high transient voltages (TRV)...
In this work, we concentrate on extending our optimization method for IGBTs [1] in drives applications by incorporating diode parameters in addition to IGBT parameters. For this purpose, the fabrication process of the diode, including a platinum diffusion and it's parameters for lifetime adjustment [2], was added to the optimization loop. Consequently, the simulation of an IGBT turn-on event in the...
Parallel-connected IGBTs are prone to large-current destruction in high-power applications due to current unbalance between each IGBT branches. This paper proposes a novel control method to improve the current balance in order to protect the device against over current destruction. The method uses two control loops to confine the current rising speed as well as to reconcile the current change start...
Resistive random access memories based on redox phenomena (ReRAM) combine several advantages. Beside their good scalability, high endurance and fast switching speed they are also very energy efficient. This work presents a study of the SET kinetics of SrTiO3-based resistive switches covering the timescale from <10 ns up to 104 s. The power-dependence of the SET kinetics and the switching energy...
At inverter-fed traction drives stray currents due to parasitic capacitances in frequency converters and machine cause high frequency voltage components spreading into all conductive components of the drive system. These hf voltages are harmful and origin from the inverter side through fast switching power semiconductors with high levels of output voltage steepness. Additionally overvoltage at the...
An advanced gate drive unit for 1.2 kV IGBT modules has been developed. It includes two main features: limitation of the collector-emitter voltage slope and of the collector-emitter peak voltage. This is achieved through a feedback loop with a capacitive/resistive voltage divider coupled to the gate-emitter voltage of the IGBT. For the studied case a reduction of the switching losses of around 25%...
This paper investigates the switching performance of six-pack SiC MOSFET and Si IGBT modules for motor drive applications. Both the modules have same packaging and voltage rating (1.2 kV). The three bridge legs of the modules are paralleled forming a single half-bridge configuration for achieving higher output power. Turn-on and turn-off switching energy losses are measured using a standard double...
The class of resonant converters is very attractive due to its ability to achieve nearly lossless switching by using zero current or zero voltage switching (ZCS/ZVS) for the switching devices in the input bridge. Since most switched-mode power supplies (SMPS) today use MOSFETs as semiconductor devices, a ZVS operation is typically preferred. However, the ongoing trend towards higher switching frequencies...
This paper presents an overview of importance and significance of controlled switching in complex power networks. The main objective of controlled switching is to avoid transients in the system. In a power system network transients are the redistribution of stored energy among the system capacitance and inductance whenever there is a change of state. So controlled switching is the method to optimize...
This paper presents a frequency-domain (FD) approach to compute transient and steady-state responses of switched networks. Generally, the FD representation of switching functions, as given for example by PWM schemes, requires a large number of samples. The proposed method addresses this issue by using the numerical Laplace transform (NLT) with reduced number of samples. Firstly, the proposed approach...
The U.S. Coast Guard's 270-ft Medium Endurance Cutter (WMEC) is a powerhouse of the Coast Guard fleet filling a critical role in defense of the homeland. While the U.S. Navy has conducted extensive research into the use of zonal DC electrical distribution systems (DCDS) for their ships, no project has analyzed the installation of DCDS on a Coast Guard cutter which has a significantly different load...
Controlled switching is a solution for the reduction and elimination of high frequency transient currents and voltages that occur during the switching of reactive plant (shunt capacitor banks and reactors). This type plant may be frequently switched by system operators in order to maintain acceptable voltage limits and therefore if switching is uncontrolled, this may present significant power quality...
This paper proposes a Pulse Density Modulation (PDM) method with improved transient for high frequency converters such as Class E DC/DC or quasi-resonant boost converters. In contrast to frequency or duty cycle control, the conventional PDM control method provides high efficiency at any load when modulation frequency is low. However, efficiency drops significantly for higher modulation frequencies...
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