Output Voltage Of Generator Research Articles

A new generation of high performance large-scale and flexible thermo-generators based on (Bi,Sb) 2 (Te,Se) 3 nano-powders using the Spark Plasma Sintering technique

An original and rapid way to build efficient thermo-generator in one step based on n-type and p-type (Bi,Sb) 2 (Te,Se) 3 nano-materials embedded in a polymer matrix is described. n-Type and p-type nano-powders are obtained through a mechanical alloying process leading to particle size of about 50 nm. The flexible thermo-generator is assembled in one step by Pulsed Current Electrical Sintering (PECS) also known as Spark Plasma Sintering (SPS) from a stacking of: (1) p-type powder, (2) special design of an electrical insulating polymer matrix and (3) n-type powder. After polishing the two sides of the thermo-generators in order to reveal series of n-type and p-type thermo-elements, electrical connections of these plots are made. Due to the fast sintering treatment, the nanostructure of thermo-elements is conserved. The full thermoelectric characterizations of such thermo-generator have been investigated leading to a generated output voltage of 51 mV for 17 thermocouples (Δ T ∼ 14 °C).

Surface Flashover Phenomenon Under 180-ns Quasi-Square Wave With Voltage of Several Hundred Kilovolts

Experiments on the surface flashover under 180-ns quasi-square waves with voltage of several hundred kilovolts are reported. In the experiments, employing a 280-kV 180-ns full-width at half-maximum (FWHM) voltage on the load, no flashover occurred. When the voltage was up to 350 kV, even 420 kV, surface flashover along the insulator occurred, and it started at the top part of the applied voltage pulse, so the FWHM of the output voltage of pulse generator was reduced to 150 ns, even 120 ns. Also, the experiment results show that surface flashover channel could be recovered quickly if a heteropolarity voltage was applied on the flashover channel. Finally, the characteristics of the surface flashover are present, including the flashover time, flashover current, and resistance.

Switching Ripple Characteristics of Space Vector PWM Schemes for Five-Phase Two-Level Voltage Source Inverters—Part 2: Current Ripple

Flux harmonic distortion factors (HDFs) of two space vector pulse width modulation (SVPWM) schemes, aimed at sinusoidal output voltage generation with five-phase voltage source inverters, have been evaluated in Part 1 of this paper. Analytical considerations and numerical integration have been applied in order to determine the switching properties of the considered SVPWM methods. It has been shown that the SVPWM based on four large vectors leads to a considerably higher overall per-phase flux HDF than the method based on two large and two medium space vectors. The purpose of the second part of the paper is to relate flux HDFs to the current ripple and current total harmonic distortion and thus explore further switching characteristics of the two SVPWM techniques. The applied approach is based on simulation and experimentation, in conjunction with the subsequent fast Fourier transform of the waveforms, so that all the results for the ripple are obtained using a methodology completely different from the one in Part 1. Relationships that correlate the current ripple and the flux HDFs are established, and it is further shown that the current ripple can be easily calculated from the flux HDF values of Part 1 if the relevant leakage inductances of the two planes are known. Hence, the complete theory of Part 1 is fully verified by both simulation and experimentation. It is also shown that, in certain cases, the SVPWM based on four large vectors may lead to a smaller current ripple despite a considerably higher flux HDF.

Switching Ripple Characteristics of Space Vector PWM Schemes for Five-Phase Two-Level Voltage Source Inverters—Part 1: Flux Harmonic Distortion Factors

Multiphase variable-speed drives supplied from two-level voltage source inverters (VSIs) are, at present, contenders for numerous industrial applications. Various pulsewidth modulation (PWM) methods for multiphase VSIs, aimed at sinusoidal output voltage generation, have been developed using both carrier-based and space-vector approaches. An increased number of voltage space vectors, available for the synthesis of the output voltage, offer greater flexibility for the PWM scheme development, compared to the three-phase case. This paper presents comprehensive analytical analysis and comparison of switching ripple characteristics of two continuous space vector PWM (SVPWM) methods for a five-phase two-level VSI. Considered SVPWM schemes select a different set of four active space vectors per switching period in order to generate sinusoidal output voltages. This paper also presents the evaluation of the flux harmonic distortion factors of the SVPWM techniques. Correlation with corresponding current ripple and total harmonic distortion is established in Part 2 of this paper, where theoretical considerations are verified by simulations and through experimental investigation on a five-phase VSI-fed induction motor drive.

Self-Autonomous Wireless Sensor Nodes With Wind Energy Harvesting for Remote Sensing of Wind-Driven Wildfire Spread

The satellite-based remote sensing technique has been widely used in monitoring wildfire spread. There are two prominent drawbacks with this approach of using satellites located in space: (1) very low sampling rate (temporal resolution problem) and (2) lack of accuracy (spatial and spectral resolution problem). To address these challenges, a wireless sensor network deployed at ground level with high-fidelity and low-altitude atmospheric sensing for wind speed of local wildfire spread has been used. An indirect approach in sensing wind speed has been proposed in this paper as an alternative to the bulky conventional wind anemometer to save cost and space. The wind speed is sensed by measuring the equivalent electrical output voltage of the wind turbine generator (WTG). The percentage error in the wind speed measurement using the proposed indirect method is measured to be well within the ±4% limit with respect to wind anemometer accuracy. The same WTG also functions as a wind energy harvesting (WEH) system to convert the available wind energy into electrical energy to sustain the operation of the wireless sensor node. The experimental results show that the designed WEH system is able to harvest an average electrical power of 7.7 mW at an average wind speed of 3.62 m/s for powering the operation of the wireless sensor node that consumes 3.5 mW for predicting the wildfire spread. Based on the sensed wind speed information, the fire control management system determines the spreading condition of the wildfire, and an adequate fire suppression action can be performed by the fire-fighting experts.

J023034 発電機構を利用した高齢者用脚力スクリーニング装置の開発([J02303]医療福祉のメカトロニクス)

New measuring system of leg power for advanced aged has been proposed to support their healthy life. The measuring sytem utilizes 'electric generator (dynamometer)' instead of 'spring force'. It can mesures output voltage of generator that is generated by means of momentary pedaling movement of a leg of subject. The measured voltage is calibrated with torque meter. Then the muscle strength and power of the leg is estimated dyanamically by using this system. Experimental results show that the system can measure not only the leg power, but also leg strength without any physical stress on old-old subject.

Thermoelectric generator placed on the human body: system modeling and energy conversion improvements

This paper focuses on the production of electricity using a thermoelectric generator placed on the human body connected to a dc-dc converter. The small difference in temperature between the hot heat source (e.g. the human body, T b = 37 °C) and the cold heat source (e.g. ambient air, T a = 22 °C), associated with a poor quality thermal coupling (mainly with the cold source), leads to a very low temperature gradient at the thermoelectric generator terminals and hence low productivity. Under these use conditions, the present article proposes an analysis of various ways to improve productivity given a surface capture system. Furthermore, we demonstrated, in this particular context, that maximizing the recovered electric power proves to be a different problem from that of maximizing efficiency, e.g. the figure of merit Z . We therefore define a new factor Z E , depending on the physical characteristics of thermoelectric materials, that maximizes electric power in the particular case where the thermal coupling is poor. Finally, this study highlights the benefit of sub-optimization of the power extracted from the thermoelectric generator to further improve efficiency of the overall system. We show that, given the conversion efficiency of the dc-dc converter, the maximum power point of the overall system is no more reached when the output voltage of the thermoelectric generator is equal to half of its electromotive force.

A Novel Instantaneous Torque Control Scheme for Induction Generator Systems

In this paper, a novel instantaneous torque control is proposed to control the output voltage of a stand-alone induction generator. The output voltage regulation is achieved by the fast control of the space voltage vector based on the information of the output voltage and output current, which leads to a better system dynamic performance. The simulation and experimental results verify the effectiveness of the proposed scheme. The control scheme for the voltage buildup process is investigated as well.

Power Quality-Based Classification and Modelling of Small Loads and Generators

The paper presents an overview of existing methods of classification of small loads and generators, giving a new approach to this issue. This new approach divides loads according to their consumed current-time waveform distortion and generators according to generated output voltage wave shape, i.e. power quality issues. For each of the selected categories an adequate mathematical (mathematical relation) and computer simulation model has been developed. The model is verified by results of laboratory measurements. The proposed approach is more suitable for practical application than previously proposed classifications as it facilitates obtaining information about the level of higher harmonics, without knowledge of the internal device structure. Further, it can be easily applied in practical laboratory setups to facilitate teaching at both undergraduate and postgraduate levels.

Analysis of Output Current-Ripple RMS in Multiphase Drives Using Polygon Approach

Multiphase variable-speed drives, supplied from two-level voltage-source inverters (VSIs), are currently considered for a number of industrial applications. Although various multiphase pulsewidth-modulated (PWM) schemes had been recently developed, very little has been reported with regard to the impact of these schemes on harmonic losses (current ripple). This paper presents a general analytical analysis and comparison of harmonic losses of two basic continuous PWM (CPWM) schemes aimed at sinusoidal output-voltage generation. The analysis utilizes the concept of multiple polygon connections, which exist for multiphase systems, and covers all multiphase topologies with an odd phase number and single neutral connection. General harmonic distortion factors (HDFs) of sinusoidal PWM (SPWM) and harmonic injection PWM (HIPWM) are determined and compared for various phase numbers. Theoretical findings are verified by means of simulations and experimentally using a five-phase induction motor drive.

MODEL AND EXPERIMENTAL STUDY OF GIANT MAGNETOSTRICTIVE POWER GENERATION

A mathematical model of vibration power generation (VPG) with the giant magnetostrictive material (GMM) is proposed on the basis of the magneto-mechanical coupling model, Jiles-Atherton model and electromagnetic induction law. According to the model, the output voltage of a giant magnetostrictive power generator has been calculated under the condition of different vibration frequency, pre-stress and bias magnetic field. The calculating results show that the model can reveal the relationship between the input vibrating stress and output voltage. The experiment of a giant magnetostrictive power generator has been carried out, and the experimental results agree well with the calculating results.

A battery-based, low-noise voltage source

A highly stable, low-noise voltage source was designed to improve the stability of the electrode bias voltages of a Penning trap. To avoid excess noise and ground loops, the voltage source is completely independent of the public electric network and uses a 12 V car battery to generate output voltages of +/-15 and +/-5 V. First, the dc supply voltage is converted into ac-voltage and gets amplified. Afterwards, the signal is rectified, filtered, and regulated to the desired output value. Each channel can deliver up to 1.5 A. The current as well as the battery voltage and the output voltages can be read out via a universal serial bus (USB) connection for monitoring purposes. With the presented design, a relative voltage stability of 7 x 10(-7) over 6.5 h and a noise level equal or smaller than 30 nV/square root(Hz) is achieved.

Magnetic resonant harvesters and power management circuit for magnetic resonant harvesters

This paper deals with the design of a vibration minigenerator and its power management electronics. The minigenerator is used as the independent energy source for wireless temperature sensors in NH-90 helicopters. The power management electronics is useful for this purpose as there exists interdependence between the generator output voltage instability and the helicopter vibrations instability. In this respect, it should also be proper to mention the necessity of applying the battery. Further, the presented article provides a description of two principles of the management electronics, namely the power factor corrector and the simple energy storage with a DC/DC regulator. It has been experimentally confirmed the minigenerator together with the electronics can save up to 52% battery energy according to the flight options with the used devices. Using the more efficient generator and electronics it should be up to 100% of the battery energy.

On Power Quality of Variable-Speed Constant-Frequency Aircraft Electric Power Systems

In this paper, a comprehensive model of the variable-speed constant-frequency aircraft electric power system is developed to study the performance characteristics of the system and, in particular, the system power quality over a frequency range of operation of 400 Hz to 800 Hz. A fully controlled active power filter is designed to regulate the load terminal voltage, eliminate harmonics, correct supply power factor, and minimize the effect of unbalanced loads. The control algorithm for the active power filter (APF) is based on the perfect harmonic cancellation method which provides a three-phase reference supply current in phase with its positive-sequence fundamental voltage. The proposed APF is integrated into the model of a 90-kVA advanced aircraft electric power system under VSCF operation. The performance characteristics of the system are studied with the frequency of the generator's output voltage varied from 400 Hz to 800 Hz under different loading conditions. Several case studies are presented including dc loads as well as passive and dynamic ac loads. The power quality characteristics of the studied aircraft electric power system with the proposed active filter are shown to be in compliance with the most recent military aircraft electrical standards MIL-STD-704F as well as with the IEEE Std. 519.

Analysis of Output Current Ripple rms in Multiphase Drives Using Space Vector Approach

Multiphase variable-speed drives, supplied from two-level voltage source inverters (VSIs), are nowadays considered for various industrial applications. Although numerous pulsewidth modulation (PWM) schemes for multiphase VSIs, aimed at sinusoidal output voltage generation, have been developed, no detailed analysis of the impact of these modulation schemes on the output current ripple has ever been reported. This paper presents a comprehensive analytical analysis and comparison of the output current ripple caused by the application of three different continuous PWM schemes, using a five-phase VSI as an example. Main properties of sinusoidal PWM, fifth harmonic injection PWM, and space vector PWM are elaborated and analyzed using the harmonic flux concept. Space vector theory is applied in the analysis. As a result, harmonic distortion factors are obtained for each PWM scheme. Theoretical considerations are verified by simulations and experimental investigation using a custom-designed five-phase VSI-fed induction motor drive.

A Modified Sector Based Space Vector PWM Technique for Five‐Phase Drives

AbstractSpace vector PWM (SVPWM) is a popular and well‐known technique for standard three‐phase drives, which has been extended recently to multi‐phase voltage source inverters (VSIs). Several SVPWM techniques, which utilize the principle of vector space decomposition (VSD), have been developed for various operating modes. The VSD approach inherently relies on considerations in two‐dimensional (2‐D) subspaces, while SVPWM for a multi‐phase VSI is in essence a multi‐dimensional problem. Hence, an alternative approach to SVPWM, which is based on the direct multi‐dimensional space consideration in the space vector selection process rather than on space vector selection in 2‐D subspaces obtained by vector space decomposition, has been recently introduced. Good performance has been identified, but the method is complex and difficult for the real‐time implementation. This article therefore combines multi‐dimensional SVPWM approach with off‐line calculations to achieve required output voltage generation under non‐sinusoidal and/or unbalanced voltage requirements, which represent the most challenging operating conditions from the point of view of the vector selection for PWM. As a consequence, the implementation becomes rather simple in standard DSPs. The performance of the algorithm is verified by simulation and experimentation. © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Statistical Characteristics of the Output Voltage in Compact Marx Generators

Compact Marx generators are widely used as portable pulse generator in different industrial applications, where high power pulses with rise times of order of some tens of nanoseconds are needed. For those applications, closing switches with very short delay and jitter times have to be used. Considering the fact that the breakdown of spark gap is a statistical process, the delay times of the closing switches are statistical voltage-dependent parameters. As a result, the characteristics of the output voltage of the Marx generator, i.e. its amplitude and rise time, are also statistical parameters. In this paper, taking the statistical behaviour of the breakdown process in spark gaps into consideration, the statistical characteristics of the output voltage have been studied in detail.

Synchronous Generator Output Voltage Real-Time Feedback Control via $H_\infty$ Strategy

A new approach on synchronous generator (SG) output voltage control is presented. The originality of such a strategy is based on the excitation structure that integrates a permanent-magnet generator combined with a modern control method: the H infin. The main motivation of this paper is the debatable results obtained with the classical excitation structure controlled by a traditional PID controller. The SG model as well as the control strategy will be presented. The implementation in real time domain and a comparison with the classical structure will allow us to prove the efficiency of the proposed structure compared to the classical one as regards the reference tracking and signal quality.

Real-Time Calculation of Switching Angles Minimizing THD for Multilevel Inverters With Step Modulation

Multilevel inverters have been widely applied in industries. A family of optimal pulsewidth modulation (PWM) methods for multilevel inverters, such as step modulation, can generate output voltage with less harmonic distortion than popular modulation strategies, such as the carrier-based sinusoidal PWM or the space vector PWM. However, some drawbacks limit the application of optimal PWM. One of such crucial drawback is that the optimal switching angles could not be calculated in real-time and one has to rely on lookup tables with precalculated angles. We propose a novel real-time algorithm for calculating switching angles that minimizes total harmonic distortion (THD) for step modulation. We give a mathematical proof that the output voltage has the minimum THD. We implemented the algorithm on a digital signal processor and provide experimental results that verify the performance of the proposed algorithm.

Generalised space vector PWM for sinusoidal output voltage generation with multiphase voltage source inverters

The paper presents a generalised approach towards the development of the space vector pulse width modulation (SVPWM) for sinusoidal output voltage generation with two-level multiphase voltage source inverters (VSIs), where the number of phases is an odd number. The generalisation can greatly speed up the implementation since the tedious analysis of 2n voltage space vectors of an n-phase inverter in the corresponding (n − 1)/2 2-D planes can be completely avoided. Required dwell times for active space vectors are correlated with trigonometric properties of multiphase systems, which account for the actual phase number. Feasibility of the developed approach has been verified experimentally using the five-phase and seven-phase SVPWM schemes as examples.