Design and testing of 1 phase semi-controlled rectifier circuit (experiment scale): a part of green laboratory project

This paper discussed design and testing of one (1) phase semi-controlled full wave rectifier circuit (experiment scale) as a part of green laboratory project. The research method was divided by two stages: design and testing. The design stage included: component selection and calculation, conceptual design and circuit physical implementation. The three main components included 2 diodes, 2 thyristors (SCR), resistive (R) and inductive (L) load with varying values. The testing stage was physical rectifier circuit operation with R (220; 580; 1,500 ohm) and R-L (L=2.37 H) load. The voltage waveform, voltage and current were observed during this stage. The testing results (voltage and current) in rms value were compared with theoretical calculation for validation. The testing results showed that the rectifier circuit working optimally. The testing results were differed by small percentage with theoretical calculation. The output voltage was differed by 1.085%. The output current for R and R-L load were differed by 4.590% and 6.457%, respectively.

She-Pwm Low Cost Multi Level Inverter for Pv Based Water Pumping Applications

In this article different multi-level inverter (MLI) configuration is introduced by a decreased quantity of power elements. At the output side the MLI topology generates the seven level voltage waveform with minimum number of components. The said topology configuration requires less dc voltage and power semiconductor switches. It also reduces the voltage block on switches, which reduces the inverter topology complexity and costs. Such capabilities were discovered by contrasting the topology to traditional topologies from the above perspectives. Testing were carried out to demonstrate the efficacy of the generalized MLI topology in both simulation and hardware, and the findings are presented for better understanding.

CPS-SPWM Implementation Based on Multi - Controller Collaboration

In order to improve the modularization degree of cascaded H-bridge converter and reduce the development cost, a modularized carrier phase shifted sine pulse width modulation (CPS-SPWM) based on multi-controller is proposed in this paper, which can easily increase or decrease the number of submodules in cascaded H-bridge. In order to solve the problem of coordination in multi-controller structure, a two-stage control structure is proposed, which uses the master controller to carry out closed-loop control for multiple slave controllers, and uses the approximate natural sampling method to realize digital CPS-SPWM modulation, which reduces computation and makes full use of controller resources. The experimental result shows that the stepped voltage waveform output by the proposed method at the AC side is of high quality and H bridge submodule is easy to be increased and decreased.

Residual Stress and Tribological Performance of ZrN Coatings Produced by Reactive Bipolar Pulsed Magnetron Sputtering

In the past few decades, ZrN thin films have been identified as wear resistant coatings for tribological applications. The mechanical and tribological properties of ZrN thin layers depend on internal stress induced by the adopted deposition techniques and deposition parameters such as pressure, temperature, and growth rate. In sputtering deposition processes, the selected target voltage waveform and the plasma characteristics also play a crucial influence on physical properties of produced coatings. In present work, ZrN thin films, obtained setting different values of duty cycle in a reactive bipolar pulsed dual magnetron sputtering plant, were investigated to evaluate their residual stress through the substrate curvature method. A considerable progressive increase of residual stress values was measured at decreasing duty cycle, attesting the significant role of voltage waveform in stress development. An evident correlation was also highlighted between the values of the duty cycle and those of wear factor. The performed analysis attested an advantageous effect of internal stress, having the samples with high compressive stress, higher wear resistance. A downward trend for wear rate with the increase of internal residual stress was observed. The choice of suitable values of duty cycle allowed to produce ceramic coatings with improved tribological performance.

Off – Grid Power Supply Solution for Portable Cabins using Solar PV System for Qatar

In this project, a new system for power supply for remote areas has been proposed. In the proposed system, solar PV based system with battery storage for stand-along application has been discussed. In addition, the use of a multilevel inverter and high-gain DC/DC converter has been proposed. The proposed multilevel inverter generates a nine-level output voltage waveform with quadruple voltage gain. The proposed DC/DC converter is based on the concept of a switched-inductor with voltage lift switched-capacitor and has been verified for a voltage gain of 20. The experimental results confirmation the satisfactory performance for stand-alone applications of the proposed converters.

Artificial Jellyfish Search Algorithm-Based Selective Harmonic Elimination in a Cascaded H-Bridge Multilevel Inverter

This paper used an artificial jellyfish search (AJFS) optimizer suitable for selective harmonic elimination-based modulation for multilevel inverter (MLI) voltage control application. The main objective was to remove the undesired lower-order harmonics in the output voltage waveform of an MLI. This algorithm was motivated by the behavior of jellyfish in the ocean. Jellyfish have the ability to find the global best position where a large quantity of nutritious food is available. The paper applied AJFS algorithm on five, seven, and nine levels of CHB-MLI. The optimum switching angle was calculated for the entire modulation range for the desired lower-order harmonics elimination. The problem formulated to achieve the objective was solved in a MATLAB environment. The total harmonic distortion (THD) values of five-, seven-, and nine-level inverters for various modulation indexes were computed using AJFS and compared with the powerful differential evolution (DE) algorithm. The comparison of THD results clearly demonstrated superior THD in the output of CHB-MLI of the AJFS algorithm over DE and GA algorithm for low and medium values of modulation index. The experimental results further validated the better performance of the AJFS algorithm.

Influence of Synchronous Condensers on Operation Characteristics of Double-Infeed LCC-HVDCs

Considering the advantages that dynamic reactive power (var) equipment (such as synchronous condensers (SCs), which can control var independently and improve voltage stability), SCs are widely used in AC/DC hybrid power grid to provide emergency var and voltage support. In order to evaluate the dynamic var reserve capacity of SCs and analyze the influence of SCs on the operation characteristics of power system, a model with double-infeed line-commutated converter-based high-voltage direct currents (LCC-HVDCs) and SCs is established. Through theoretical derivation and PSCAD/EMTDC simulation, the effects of SCs on the operation characteristics of double-infeed LCC-HVDCs networks are studied. Then, the non-smooth voltage waveform of electromagnetic transient simulation is approximately transformed into smooth waveform by data fitting method. Finally, the processed voltage waveform is searched step by step to explore the boundary of voltage safety region to determine the dynamic var reserve capacity of SCs. The numerical results show that SCs can enlarge the voltage security region of the direct current (DC) subsystem, thus effectively improving the steady-state and transient security level of the double-infeed LCC-HVDCs networks.

A Single Source Switched-Capacitor 13-Level Inverter with Triple Voltage Boosting and Reduced Component Count

A new triple voltage boosting switched-capacitor multilevel inverter (SCMLI) is presented in this paper. It can produce 13-level output voltage waveform by utilizing 12 switches, three diodes, three capacitors, and one DC source. The capacitor voltages are self-balanced as all the three capacitors present in the circuit are connected across the DC source to charge it to the desired voltage level for several instants in one fundamental cycle. A detailed comparative analysis is carried to show the advantages of the proposed topology in terms of the number of switches, number of capacitors, number of sources, total standing voltage (TSV), and boosting of the converter with the recently published 13-level topologies. The nearest level control (NLC)-based algorithm is used for generating switching signals for the IGBTs present in the circuit. The TSV of the proposed converter is 22. Experimental results are obtained for different loading conditions by using a laboratory hardware prototype to validate the simulation results. The efficiency of the proposed inverter is 97.2% for a 200 watt load.