Energy Efficiency in Low Voltage Hall Thrusters

Author(s):  
Jerry Ross ◽  
Lyon King
Author(s):  
Hugo Hens

Since the 1990s, the successive EU directives and related national or regional legislations require new construction and retrofits to be as much as possible energy-efficient. Several measures that should stepwise minimize the primary energy use for heating and cooling have become mandated as requirement. However, in reality, related predicted savings are not seen in practice. Two effects are responsible for that. The first one refers to dweller habits, which are more energy-conserving than the calculation tools presume. In fact, while in non-energy-efficient ones, habits on average result in up to a 50% lower end energy use for heating than predicted. That percentage drops to zero or it even turns negative in extremely energy-efficient residences. The second effect refers to problems with low-voltage distribution grids not designed to transport the peaks in electricity whensunny in summer. Through that, a part of converters has to be uncoupled now and then, which means less renewable electricity. This is illustrated by examples that in theory should be net-zero buildings due to the measures applied and the presence of enough photovoltaic cells (PV) on each roof. We can conclude that mandating extreme energy efficiency far beyond the present total optimum value for residential buildings looks questionable as a policy. However, despite that, governments and administrations still seem to require even more extreme measurements regarding energy efficiency.


Author(s):  
Nandhini Chandramoorthy ◽  
Karthik Swaminathan ◽  
Martin Cochet ◽  
Arun Paidimarri ◽  
Schuyler Eldridge ◽  
...  

Author(s):  
Ivan Nadtoka ◽  
◽  
Pyotr Osadchiy ◽  
Vladimir Tropin ◽  
◽  
...  

The features of applying the «open triangle» scheme in the structure of a rural low-voltage distribution network with a voltage of 220 V are studied from the standpoint of achieving a certain energy efficiency. The energy effect is estimated by the criterion of the relative value of the additional power losses in the conductors of a three-wire line of a 220 V network caused by reactive power and load asymmetry. The load is modeled by two power receivers connected to the phase-to-phase voltage, the general output of the power receivers is grounded, which forms the «open triangle» circuit. The energy characteristics of the active load, active load with capacitive corrective element, active load with capacitive and inductive corrective elements are analyzed; and also the most practical case – active-inductive load with various values of reactive power factors -0,1; 0,2; 0,3 and capacitive corrective element. An important feature of applying the «open triangle» scheme in the structure of a rural low-voltage distribution network with a voltage of 220 V, from the standpoint of achieving practically necessary and sufficient energy efficiency - not exceeding 10 % of the additional power losses, is the ability to compensate for reactive power and balancing the phase currents of the network line using only one corrective capacitor of relatively low power - about 50 % of the active power of one power receiver.


Author(s):  
Anis Ammous ◽  
Abdulrahman Alahdal ◽  
Kaiçar Ammous

The Low Voltage Direct Current (LVDC) system concept has been growing in the recent times due to its characteristics and advantages like renewable energy source compatibility, more straightforward integration with storage utilities through power electronic converters and distributed loads. This paper presents the energy efficiency performances of a proposed LVDC supply concept and others classical PV chains architectures. A PV source was considered in the studied nanogrids. The notion of Relative Saved Energy (RSE) was introduced to compare the studied PV systems energy performances. The obtained results revealed that the employment of the LVDC chain supply concept is very interesting and the use of DC loads as an alternative to AC loads, when a PV power is generated locally, is more efficient. The installed PV power source in the building should be well sized regarding to the consumed power in order to register a high system RSE.


2021 ◽  
Author(s):  
Mehdi Safarpour

<div>Operating at reduced voltages promises substantial energy efficiency improvement, however the downside is significant down-scaling of clock frequency. This paper propose vision chips as excellent fit for low-voltage operation. Low-level sensory data processing in many Internet-of-Things (IoT) devices pursue energy efficiency by utilizing sleep modes or slowing the clocking to the minimum. To curb the share of stand-by power dissipation in those designs, near-threshold/sub-threshold operational points or ultra-low-leakage processes in fabrication are employed. Those limit the clocking rates significantly, reducing the computing throughputs of individual processing cores. In this contribution we explore compensating for the performance loss of operating in near-threshold region ($V_{dd}=$0.6V) through massive parallelization. Benefits of near-threshold operation and massive parallelism are optimum energy consumption per instruction operation and minimized memory round-trips, respectively. The Processing Elements (PE) of the design are based on Transport Triggered Architecture. The fine grained programmable parallel solution allows for fast and efficient computation of learnable low-level features (e.g. local binary descriptors and convolutions). Other operations, including Max-pooling have also been implemented. The programmable design achieves excellent energy efficiency for Local Binary Patterns computations. </div><div>Our results demonstrates that the inherent properties of chip processor and vision applications allow voltage and clock frequency aggressively without having to compromise performance. </div>


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