Application and evaluation of variable frequency energy-saving technology for reciprocating compressor in CBM Field

In this paper, we present a new technique to unify and intensify the magnetic fields that results in higher performance of Anisotropic Magneto-Resistive (AMR) current sensors and consequently develop a closed loop controller for 100W synchronous GaN buck converter at 1MHz. The closed loop operation of high switching frequency converters at high power has always been a big challenge due to lack of access to current information. The proposed method that also intensifies the magnetic fields through the sensor, significantly improves the bandwidth limits, and reduces electromagnetic interference (EMI) on AMR sensors, making them applicable for high switching frequency and high current power electronics converters. After verifying uniform distribution concept through simulation, we also implemented a prototype of AMR current sensors onto Printed Circuit Board (PCB) for verification of the concept at high frequency converter. We then present the design procedure and associated challenges of an integrated analogue peak current controller for creating the closed loop operation of a GaN buck converter at high switching frequency.

Thermodynamic modeling, CFD analysis and parametric study of a near-isothermal reciprocating compressor

A conventional unregulated fuel cell system requires a multi-stage operation in order to get three phase AC power supply for integration with load or grid. The output of fuel cell which is DC has to be converted into high frequency AC which has low efficiency due to high switching losses. In this paper high frequency power is regulated with the help of cascade connection of the series resonant converter and single phase to three phase cycloconverter. A series resonant converter decreases the switching loss because of zero current switching whereas a single phase to three phase cycloconverter converts the single phase high frequency output into low frequency three phase output required by grid. The proposed high frequency converter has high conversion efficiency and low cost. It is compact due to reduction of number of stages and eliminates intermediate filter. Analysis and simulation are presented for complete converter system using Matlab software and it has been demonstrated that the system is highly efficient with simple controller and higher power density.

As wide bandgap (WBG) semiconductors are gradually adopted for high switching frequency high power-density power converter, new challenges arise from control to hardware design. In this paper, an improved input current sampling method is proposed for three-phase rectifiers to avoid sampling noises when rectifiers are operated at high speed and high switching frequency. Experimental results obtained from a 450-kHz enhancement-mode Gallium Nitride (GaN) high-electron-mobility transistor (HEMT) based three-phase three-level Vienna-type rectifier demonstrate the good performance of the sampling method.

This paper presents a dynamic model for neon tubes. The model is derived from conventional Cassie's and Mayr's equations which are often used to model low-voltage and high-current arc discharges, such as electrical arcs in switching interrupters and HID lamps. In this paper, the effects of various types of energy dissipation mechanisms on conductance of the plasma channel are considered for high-voltage and low-current neon tubes. In particular, the Cassie's and Mayr's equations are modified such that the loss on the heat conduction of the neon tube can be accurate modeled. Some basic rules for the selection of parameters in the model are proposed. Simulation is performed using Pspice simulator. A high frequency switch mode supply is built to power the neon tube under test. Experimental results reveal that the developed neon tube dynamic model is applicable for both low and high frequency operations.

Soft switching for both primary and secondary side devices is available by using LLC converters. This resonant converter is an ideal candidate for today’s high frequency, high efficiency, and high power density applications like adapters, Uninterrupted Power Supplies (UPS), Solid State Transformers (SST), electric vehicle battery chargers, renewable energy systems, servers, and telecom systems. Using Gallium-Nitride (GaN)-based power switches in this converter merits more and more switching frequency, power density, and efficiency. Therefore, the present paper focused on GaN-based LLC resonant converters. The converter structure, operation regions, design steps, and drive system are described precisely. Then its losses are discussed, and the magnets and inductance characteristics are investigated. After that, various interleaved topologies, as a solution to improve power density and decrease current ripples, have been discussed. Also, some challenges and concerns related to GaN-based LLC converters have been reviewed. Commercially available power transistors based on various technologies, i.e., GaN HEMT, Silicon (Si) MOSFET, and Silicon Carbide (SiC) have been compared. Finally, the LLC resonant converter has been simulated by taking advantage of LTspice and GaN HEMT merits, as compared with Si MOSFETs.

This paper discusses optimal configuring and commissioning of laboratory system that consists of FC-302 high performance frequency converter and induction motor. In the beginning frequency converter control of induction motor is explained. Furthermore, the measurements of slip compensation parameter change influence on motor speed and motor load dependence are performed, as well as measurements of power factor correction attained by frequency converter. It is possible to compensate slip completely, so that motor speed is constant, regardless of motor load, which provides optimal control. Frequency converter partially compensates power factor of converter - motor system with capacitors of passive filter.

Power spectral analysis of fetal heart rate variability has been proposed to provide a non-invasive estimate of autonomic balance. However, there are few systematic data before birth. We therefore examined developmental changes in the frequency power spectrum at very low (0-0.04 Hz), low (0.04-0.15 Hz) and high frequencies (0.15-0.4 Hz), as well as the ratio of low- to high-frequency power (LF/HF), in chronically catheterized, healthy fetal sheep at 0.6 (n = 8), 0.7 (n = 7) and 0.8 gestational age (ga; n = 11). In a second study, 0.8 ga fetuses received either atropine (4.8 mg bolus, then 4.8 mg h(-1) for 30 min, n = 6) or 6-hydroxydopamine (20 mg ml(-1) at 2.5 ml h(-1) for 3 h; n = 9). Data were analysed by sleep state, defined by low-voltage-high-frequency (LV) or high-voltage-low-frequency (HV) EEG. Total spectral power increased with gestational age (P < 0.05), while LF/HF decreased from 0.6 to 0.7 ga. At 0.8 ga, heart rate and LF/HF were significantly higher during HV than LV sleep (P < 0.05). Consistent with this, although total spectral power was not significantly greater during HV sleep, there was a significant interaction between sleep state and frequency band (P = 0.02). Both atropine (P = 0.05) and 6-hydroxydopamine (P < 0.05) were associated with an overall reduction in spectral power but no significant effect on the LF/HF ratio. This study does not support substantial, consistent differences between the frequencies of sympathetic and parasympathetic activity in late-gestation fetal sheep.

Acousto Optic Modulator (AOM) is an interaction cell which, when excited with RF power, produces spectrum of colours from white light input. These interaction cells are used in several applications such as film recorders, Graphic arts, beam splitters, colour generators, optical defectors etc. To drive the AOM, an RF driver circuit is required. The RF driver is basically a high frequency converter and high power amplifier which can give a frequency of several MHz and power upto several watts. The conversion from low frequency to high frequency and amplifying to a few watts is not a new technique but it is difficult to amplify the signal with 100% duty cycle (without distortion). These applications require a linearly variable amplitude and high frequency generator which is very difficult to realise at around 300 MHz frequency. The power amplifiers presently available suffer from severe distortion as they are class-C amplifiers. Many power converters are available which convert AC power to drive DC motors using SCRs but those concepts can't be implemented in these applications because they are limited to a low frequency range. This paper describes the description of RF driver for AOM and design criteria for a specific application in film recorder. This design can also be used for applications where a highly linear, variable amplitude, frequency generation and linear power amplification is required at around 300 MHz frequency with 3W maximum power output.

High density high switching frequency power converter conducted EMC had been analysed, modelling the noise source and noise path, while providing accurate conducted EMC noise limits comparable to accredited noise measurements up to 100 MHz. The military specified DC-DC converters are applicable, spanning from 100 W handheld power managers up to 2 kW DC-DC battery chargers. The Step-Down converter, Step-Up converter and their multi-phase derivatives were analysed and modelled. Some techniques to reduce conducted EMI, such as phase dithering, were also analysed. Circuit layout high frequency effects as well as high frequency impedances of the power components were characterised. At first, a trapezoidal noise source and lumped element noise path model was adopted, showing the high frequency limitations of this technique. A mathematical model was also presented. Thereafter, a high frequency lumped element model including switching elements, was created by using equivalent impedance circuits obtained by measurement from an impedance analyser performed on individual components and traces. A time domain transient model circuit analysis was investigated to represent noncompliance circuit noise as measured with a LISN. Various affordable software packages were evaluated to be considered as a high frequency conducted EMC tool, noting accuracy and ease of use. The accuracy of these modelling tools was compared to accredited measurements. A compact LISN was manufactured and a measurement bench was set up and calibrated against an accredited LAB to perform these practical verification tests. Noise signals were recorded in a simultaneous digital manner so as to be able to perform a detailed post analysis as well as diagnostic calculations, such as common mode and differential mode separation, calibrated with an EMC ETS-Lindgren current probe. Good and workable model accuracies were achieved with the basic Step-Up and Step-Down circuits over the conducted emission frequency band and beyond. Prominent noise effects occur up to this frequency when high density and high switching speed converters are analysed.

Reciprocating compressors represent the most renowned and extensively utilized compressors within the positive displacement category. A compressor that takes input gas at pressures above atmospheric and delivers it very high pressures (&amp;gt; 100 bar) is specifically called a booster pump. These pumps commonly consist of two or more piston-cylinder units in series, connected through check valves that determine the final delivery pressure, and they are instrumental in a range of applications centered around the storage and delivery of gases and fuels. Despite the availability of various booster pumps in the global market, literature offers limited insights into their design specifics. The design intricacies of a booster pump, tailored to operate at specified output pressure and mass flow rate, are contingent upon the interplay of coupled flow dynamics and heat transfer phenomena within the system. These phenomena include fluid flow dynamics through check valves, heat transfer across cylinder walls, and mechanical properties of pump materials, alongside cyclic operational parameters. To address this gap, we have embarked on an experimental-computational investigation aimed at elucidating the transport processes occurring in a single-cylinder booster pump. This work focuses on computational investigations concerning gas compression and the actuation of check valves in a single-cylinder reciprocating booster. Momentum and energy conservation equations were solved on a dynamic mesh platform through Ansys Fluent. Adiabatic conditions were employed, and the numerical solver was partially validated by comparison with thermodynamic theory for simulations conducted in a closed adiabatic cylinder. Calculations were then extended for an open cylinder with inlet and outlet check valves. Simulations indicate that forced cooling plays an important role for the longevity of sealing parts.

This work proposes a modification of the Two Input Buck converter (TIBuck) working as a high efficiency driver for LEDs and transmitter for Visible Light Communication (VLC). Due to the lower harmonic components and lower voltage stress over the switches, the TIBuck converter is a suitable option for high frequency and fast response converter. The TIBuck converter outperforms the conventional buck converter in terms of efficiency and communication capability because of its lower switching losses and less filtering action required. The second voltage source needed by the TIBuck converter is provided by means of an auxiliary Buck converter, which also implements the average current control over the LEDs. The efficiency of the converter is improved by reducing the power that is been processed at high frequency. Most of the power is processed by an auxiliary Buck converter with lower switching frequency. As experimental results, a TIBuck converter is built based on a low frequency and a high frequency Buck converters connected in parallel regarding the load. The topology reaches a 94% of efficiency reproducing a 64-QAM with a bitrate up to 1.5 Mbps.

The design of a high frequency (L Band), low power (2.75mW) Phase Lock Loops with a 350nm Complementary Metal Oxide Semi Conductor (CMOS) technology has been represented. The comparison of Current Starved Voltage Controlled Oscillator (CSVCO) and Differential pair VCO is performed and analyzed for low power and high frequency analysis respectively. Each component of Phase Lock Loop (PLL) is designed with 350nm CMOS technology in Design Architect Integrated Circuit Station by Mentor Graphics (Eldo-Net) as simulator. In this paper both the standard configurations have been simulated under the same environment and results are analyzed for two most important Very Large Scale Integration (VLSI)constraints, Speed (High frequency range) and Power consumption. The high speed and locking performance of the Differential pair VCO has been evaluated against the lower power consumption benefit of CSVCO.

Design and analysis of Dadda multiplier with Common Boolean Logic

The paper presents the human blood reheating technique for medical purposes with high frequency induction heating system. The temperature is analyzed to determine the heat distribution in different positions of human blood within the non metallic tank. In the proposed induction heating system, the inductive applicator is a primary working coil of the modified half bridge high frequency inverter and the RBCs within the blood will be working as secondary element. The simulation shows that the heating area can be effectively controlled by using the cylindrical shield with adjustable space. However, the efficiency of heat can be increased by varying the radius size of cylinder thereby more flux appears and more eddy emf is induced. Hence the resulting eddy current increases the refrigerated blood of range 1oC- 6oC to 37oC. DOI: http://dx.doi.org/10.11591/telkomnika.v14i1.7262