Analysis and Mitigation of Valve Switching Losses in Switched Inertance Converters

2015 ◽  
Author(s):  
Travis K. Wiens
Keyword(s):  
Pressure Drop ◽  
Trade Flow ◽  
The Other ◽  
Energy Losses ◽  
Switching Loss ◽  
Highly Efficient ◽  
Switching Losses ◽  
Overall Performance ◽  
Valve Switching ◽  
Flow Valve

Switched inertance converters use digital valves to exploit the inertia of a flow in order to trade flow for pressure or vice versa. These components can be used to efficiently match load and supply pressures, avoiding the energy wasted by using resistive valves. While theoretical switched inertance converters can be highly efficient, practical implementations suffer from a number of energy losses. One of these losses is the valve switching loss: the energy wasted due to the flow experiencing a pressure drop across the partially open valve as the digital valve shifts from one position to the other. This paper quantifies the effect of this loss on the valve’s overall performance. Two novel strategies for mitigating this effect are introduced: a shaped inertance tube design and positioning of the tank-flow valve along the length of the inertance tube.

scholarly journals A High-Efficiency Three-Level ANPC Inverter Based on Hybrid SiC and Si Devices

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1159 ◽  
Author(s):  
Zhijian Feng ◽  
Xing Zhang ◽  
Jianing Wang ◽  
Shaolin Yu
Keyword(s):  
Silicon Carbide ◽  
High Efficiency ◽  
The Other ◽  
Switching Frequency ◽  
Parallel Operation ◽  
Switching Loss ◽  
Hybrid Scheme ◽  
Excellent Performance ◽  
Switching Losses ◽  
The Cost

Silicon carbide (SiC) devices have excellent performance, such as higher switching frequency and lower switching loss compared with traditional silicon (Si) devices. The application of SiC devices in inverters can achieve higher efficiency and power density. In recent years, the production process of SiC devices has become more mature, but the cost is still several times that of traditional Si devices. In order to balance cost and efficiency, replacing only some of the Si devices with SiC devices in a topology is a better choice. This paper proposed a high-efficiency hybrid active neutral point clamped (ANPC) three-level inverter which has only two SiC devices and the other devices are Si devices. A specific modulation strategy was applied to concentrate switching losses on the SiC devices and reduce the on-state loss through parallel operation during freewheeling intervals. Theoretical efficiency curves and experimental verification of the proposed hybrid scheme with Si-only and SiC-only schemes were carried out.

Pressure Drop Measurements for Air Flow Through Open-Cell Aluminum Foam

2004 ◽  
Author(s):  
Nihad Dukhan ◽  
Angel Alvarez
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Flow Rate ◽  
Aluminum Foam ◽  
Flow Direction ◽  
The Other ◽  
Turbulent Regime ◽  
Thick Sample ◽  
Open Cell ◽  
Two Samples

Wind-tunnel pressure drop measurements for airflow through two samples of forty-pore-per-inch commercially available open-cell aluminum foam were undertaken. Each sample’s cross-sectional area perpendicular to the flow direction measured 10.16 cm by 24.13 cm. The thickness in the flow direction was 10.16 cm for one sample and 5.08 cm for the other. The flow rate ranged from 0.016 to 0.101 m3/s for the thick sample and from 0.025 to 0.134 m3/s for the other. The data were all in the fully turbulent regime. The pressure drop for both samples increased with increasing flow rate and followed a quadratic behavior. The permeability and the inertia coefficient showed some scatter with average values of 4.6 × 10−8 m2 and 2.9 × 10−8 m2, and 0.086 and 0.066 for the thick and the thin samples, respectively. The friction factor decayed with the Reynolds number and was weakly dependent on the Reynolds number for Reynolds number greater than 35.

Superior Short Circuit Performance of 1.2kV SiC JBSFETs Compared to 1.2kV SiC MOSFETs

2019 ◽  
Vol 963 ◽  
pp. 797-800 ◽  
Author(s):  
Ajit Kanale ◽  
Ki Jeong Han ◽  
B. Jayant Baliga ◽  
Subhashish Bhattacharya
Keyword(s):  
High Temperature ◽  
Short Circuit ◽  
Switching Loss ◽  
Switching Circuit ◽  
Inductive Load ◽  
Circuit Performance ◽  
Switching Performance ◽  
Turn On ◽  
Switching Losses ◽  
High Side

The high-temperature switching performance of a 1.2kV SiC JBSFET is compared with a 1.2kV SiC MOSFET using a clamped inductive load switching circuit representing typical H-bridge inverters. The switching losses of the SiC MOSFET are also evaluated with a SiC JBS Diode connected antiparallel to it. Measurements are made with different high-side and low-side device options across a range of case temperatures. The JBSFET is observed to display a reduction in peak turn-on current – up to 18.9% at 150°C and a significantly lesser turn-on switching loss – up to 46.6% at 150°C, compared to the SiC MOSFET.

scholarly journals On the Practical Evaluation of the Switching Loss in the Secondary Side Rectifiers of LLC Converters

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5915
Author(s):  
Manuel Escudero ◽  
Matteo-Alessandro Kutschak ◽  
Francesco Pulsinelli ◽  
Noel Rodriguez ◽  
Diego Pedro Morales
Keyword(s):  
Resonant Frequency ◽  
High Voltage ◽  
Low Voltage ◽  
Hysteresis Loss ◽  
Resonant Converters ◽  
Switching Loss ◽  
Operating Modes ◽  
Switching Losses ◽  
Series Resonant ◽  
Secondary Side

The switching loss of the secondary side rectifiers in LLC resonant converters can have a noticeable impact on the overall efficiency of the complete power supply and constrain the upper limit of the optimum switching frequencies of the converter. Two are the main contributions to the switching loss in the secondary side rectifiers: on the one hand, the reverse recovery loss (Qrr), most noticeably while operating above the series resonant frequency; and on the other hand, the output capacitance (Coss) hysteresis loss, not previously reported elsewhere, but present in all the operating modes of the converter (under and above the series resonant frequency). In this paper, a new technique is proposed for the measurement of the switching losses in the rectifiers of the LLC and other isolated converters. Moreover, two new circuits are introduced for the isolation and measurement of the Coss hysteresis loss, which can be applied to both high-voltage and low-voltage semiconductor devices. Finally, the analysis is experimentally demonstrated, characterizing the switching loss of the rectifiers in a 3 kW LLC converter (410 V input to 50 V output). Furthermore, the Coss hysteresis loss of several high-voltage and low-voltage devices is experimentally verified in the newly proposed measurement circuits.

scholarly journals Performance Research of Seven Level Multi-Level Inverter with Reduced Switches using Various PWM Techniques

2019 ◽  
Vol 8 (2S8) ◽  
pp. 1149-1154
Keyword(s):  
High Power ◽  
Harmonic Distortion ◽  
Total Harmonic Distortion ◽  
Switching Topology ◽  
Switching Loss ◽  
Medium Voltage ◽  
Switching Losses ◽  
Multi Level ◽  
Low Efficiency ◽  
Performance Research

A inverter is basically a device that usually converts DC to AC voltage without causing any power loss, applicable to only low to medium voltage applications. But in case of medium to high power applications, it has demerits like high switching losses, reduced cost and low efficiency. To overcome these demerits a Multilevel inverter applicable to high voltage and high-power applications which have low total harmonic distortion (THD) is introduced. This paper is mainly focused on seven-level inverter with five switches and four dc sources. with low total harmonic distortion, less switching loss without adding any complexity to the circuit. The switching topology is integrated with various SPWM techniques like Phase Disposition (PD), Phase Opposition Disposition (POD) and Anti Phase Opposition Disposition (APOD). For better performance of the inverter above three PWM techniques will be compared and analyzed to find the low THD configuration. The simulation of switching topology is done by MATLAB/Simulink.

Paradoxes of Distribution Reforms in Maharashtra

Mapping Power ◽  
2018 ◽  
pp. 176-192 ◽  
Author(s):  
Kalpana Dixit
Keyword(s):  
Open Access ◽  
Public Participation ◽  
The State ◽  
The Other ◽  
Industrial Flight ◽  
Overall Performance

Maharashtra is locked into a fragile equilibrium of unsustainable subsidies and high cost supply—a pattern initiated by the Enron project and repeated more recently—but mitigated by the fact that the state achieved household electrification earlier than most others, is relatively wealthy and can afford direct subventions, and has plentiful industrial consumers for cross-subsidies. However, Maharashtra’s equilibrium is threatened by the prospect of industrial flight from the grid; the state faces increasing pressure from open access on one hand, which will dilute the ability to cross subsidize, and high cost power on the other. Reforms increased transparency in a way that has made public participation more active, but the state has failed to make the kinds of managerial and organizational improvements that would have improved the overall performance of the sector.

A Novel Control Strategy for Pilot Controlled Proportional Flow Valve With Internal Displacement-Flow Feedback

2018 ◽  
Vol 140 (11) ◽  
Author(s):  
He Wang ◽  
Xiaohu Wang ◽  
Jiahai Huang ◽  
Jun Wang ◽  
Long Quan
Keyword(s):  
Pressure Drop ◽  
Flow Rate ◽  
Control Strategy ◽  
Pid Controller ◽  
Back Propagation ◽  
Back Propagation Neural Network ◽  
Internal Displacement ◽  
Valve Opening ◽  
Proportional Flow ◽  
Flow Valve

The present study is focused on the construction of a well-performing pilot controlled proportional flow valve with internal displacement-flow feedback. A novel control strategy for the valve is proposed in which the flow rate through the valve is directly controlled. The linear mathematical model for the valve is established and a fuzzy proportional–integral–derivative (PID) controller is designed for the flow control. In order to obtain the flow rate used as feedback rapidly and accurately in real-time, back propagation neural network (BPNN) is employed to predict the flow rate through the valve with the pressure drop through the main orifice and main valve opening, and the predicted value is used as the feedback. Both simulation and experimental results show that the predicted value obtained by BPNN is reliable and available for the feedback. The proposed control strategy is effective with which the flow rate through the valve remains almost constant when the pressure drop through the main orifice increases and the valve can be applied to the conditions where the independence of flow rate and load is required. For the valve with the proposed control strategy, the nonlinearity is less than 5.3%, the hysteresis is less than 4.2%, and the bandwidth is about 16 Hz. The static and dynamic characteristics are reasonable and acceptable.

Performance of Oil Separator According to the Depth of the Outlet Tube

2015 ◽  
Author(s):  
Seongil Jang ◽  
Joon Ahn ◽  
Si Hyung Lim
Keyword(s):  
Energy Efficiency ◽  
Energy Consumption ◽  
Pressure Drop ◽  
Separation Efficiency ◽  
Lubricating Oil ◽  
Tube Length ◽  
Working Fluid ◽  
Energy Losses ◽  
Refrigeration System ◽  
Outlet Tube

Recent years have witnessed a growing concern over saving energy because of global warming issues and energy price hikes caused by increased oil prices. The need to improve energy efficiency to reduce energy consumption has been raised. Refrigeration systems are also expected to have their energy efficiency improved. A refrigeration system’s the compressor uses lubricating oil. Lubricating oil, along with refrigerant, circulates in a refrigeration system. During this process, the pressure drop increases, and the heat transfer coefficient decreases. Moreover, insufficient lubricant may incur a decrease in performance and damage to a compressor. Therefore, an oil separator is used to separate the lubricant and return it to the compressor. Since an oil separator causes an additional pressure drop, energy consumption should be decreased by increasing the oil separator’s separation efficiency and decreasing the pressure drop. The recent increase in development of large-scale buildings such as skyscrapers and large supermarkets has also increased the demand for large refrigeration machines. At the same time, refrigeration piping is becoming longer, and refrigerant must circulate up to the highest points. A high-pressure head and long piping configuration inevitably increase the quantity of lubricant left on the pipe wall, which in turn increases the loss of lubricants. The increased length and fall height for lubricants to circulate with refrigerant increase the related energy loss. In order to use a compressor in a high-head long-piping refrigeration system, the separation efficiency of the oil separator must be improved. Doing so will also reduce energy losses. Even with an improved separation efficiency, however, an increased pressure drop means additional energy losses. Thus, an oil separator with high separation efficiency and low pressure drop should be designed. So using the Numerical analysis, designed a new oil separator. A series of numerical simulation has been carried out to study peformance of a cyclone type oil separator, which is designed for the compressor of a refrigeration system. Working fluid is R22, which is a typical refrigerant, and mineral oil droplet is supplied. Depending on the outlet tube length, separation efficiency varies from 98.74 to 99.25%. Considering both of the separation efficiency, outlet tube length of the separator has been designed as 158 mm and oil separator length is 310mm.

Further Work on Analyzing Accuracy and Overall Performance of Torque Tools for Assembling Bolted Flanged Joints

2019 ◽  
Author(s):  
Clay D. Rodery ◽  
Scott Hamilton ◽  
Neil Ferguson
Keyword(s):  
The Other ◽  
The Past ◽  
Bolt Stress ◽  
Overall Performance ◽  
Accuracy And Repeatability

Abstract Over the past two years, the accuracy and repeatability of equipment used to assemble bolted flanged joints have been studied, and progress has been reported in past papers. One of the findings has been that pneumatic torque wrenches demonstrated a broader plus/minus range on bolt stress from the targeted value (e.g., lack of accuracy) than manual or hydraulic torque wrenches. What was notable, however, was that the repeatability of the bolt stress that was achieved did remain consistent with the other types of torque wrenches. Since the repeatability has been shown to be consistent, attention has turned to investigating and determining the reason for the perceived lack of accuracy. One aspect that might account for this is the calibration of the pneumatic torque wrenches. This paper outlines and documents the research that has recently taken place to identify the parameters that are key elements in improving the accuracy of pneumatic torque wrenches that might form the basis of development of a standard for calibration of powered torqueing equipment.

scholarly journals B-74 Using Rates of Low Scores to Assess Agreement between ANAM4 TBI-MIL and a Traditional Battery of Neuropsychological Tests

2019 ◽  
Vol 34 (6) ◽  
pp. 1022-1022
Author(s):  
B Ivins ◽  
J Arrieux ◽  
W Cole ◽  
K Schwab
Keyword(s):  
Traumatic Brain Injury ◽  
Neuropsychological Tests ◽  
Poor Performance ◽  
The Other ◽  
Neurological Assessment ◽  
Us Military ◽  
The Us ◽  
Valid Data ◽  
Overall Performance ◽  
Assessment Metrics

Abstract Objective The Automated Neurological Assessment Metrics (Version 4) Traumatic Brain Injury Military (ANAM4 TBI-MIL) battery is widely used by the US military to assess cognitive function. We compare intra-individual agreement between ANAM4 TBI-MIL and a battery of traditional neuropsychological tests using rates of low scores. Methods Complete and valid data from 246 healthy soldiers and 177 soldiers ≤7 days from sustaining mild TBI (mTBI) were used in this analysis. All soldiers were consecutively administered ANAM4 TBI-MIL and a traditional test battery consisting of: TOPF, WAIS-IV, CVLT-II, RCFT, DKEFS, and CPT-II. We performed base rate analyses of both batteries to determine the proportions of soldiers who had various numbers of scores that were 1.0+, 1.5+, and 2.0+ standard deviations below the normative mean. We used those rates to place Soldiers into a “low score hierarchy” ranging from the least poor (i.e. ~≥10th %ile) to the worst overall performance (i.e. ~≤10th %ile). We then compared agreement between the batteries at each of those levels. Results More soldiers with mTBI had low scores than healthy soldiers on both batteries. Of the soldiers who performed at the worst level on one battery, 88.1% from ANAM and 100% from traditional had some level of poor performance on the other battery. However, of the soldiers who performed at the worst level on either battery, only 58.3% from ANAM and 50.0% from traditional also performed at the worst level on the other battery. Conclusion These batteries similarly identify poor performance to a degree, though with some potentially meaningful differences still present.

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