High-speed Generator Research Articles

Analysis and optimization of a high-speed generator’s cooling structure based on Taguchi method

To increase the power density of the original generator, it is desired to boost the generator’s power to 1.2 times its original capacity. However, the cooling structure of the original generator cannot meet the heat dissipation requirements of the upgraded power level. It necessitates a redesign of the cooling structure. For the stator, water pipes through the stator core yoke are added; for the rotor, a novel rotor cooling structure is designed. The structure includes the groove bottom vent beneath the rotor excitation winding and the radial auxiliary grooves on the sides. The airflow passes through the groove bottom vent and then follows the radial auxiliary grooves until it reaches the air gap. It can efficiently remove the heat from the rotor excitation winding. The results of the new scheme are discussed. When comparing the new scheme with the original one, the highest temperature of the stator winding decreases by 20.6k, while the one of the rotor excitation winding does by 23.7K. To further improve the cooling structure, the Taguchi method is employed. The optimization variables include the area of the stator back vent, the number of radial auxiliary grooves, and the height of the groove bottom vent. The optimization objectives are the highest temperature of the stator winding, the highest temperature of the rotor excitation winding, the air friction loss, and the inlet-outlet static pressure difference. By analyzing the variance and range of the results, the improved scheme is obtained. Comparing the improved scheme with the new one, the temperature distribution difference between them is negligible. The improved scheme reduces the air frictional loss by 10.7%, but increases the inlet-outlet static pressure difference by 8.0%.

Multidisciplinary Design and Optimization of High-Speed Hybrid Excitation Starter Generator for Aircraft Power System

Multidisciplinary Design and Optimization of High-Speed Hybrid Excitation Starter Generator for Aircraft Power System

Exhaust Gas Flow Study of Electric Turbo Compounding (ETC) to Determine the Potential Electrical Energy Recovery from Exhaust Emission

Electric turbo compounding (ETC) emerges as a pivotal energy recovery solution, seamlessly combining an advanced turbocharger with a high-speed generator to harvest electrical energy from exhaust gas dynamics. This research delves into the practical application of ETC in vehicles, employing a comprehensive approach blending simulation techniques with experimental validation. The investigative process involves meticulous data collection on vehicle muffler dimensions, subsequent device modelling based on this data, and rigorous flow simulations, followed by thorough analysis. The study's key findings highlight a noteworthy 9% increase in engine back pressure at 850 rpm, counterbalanced by a 7% reduction at 2000 rpm. Despite the integration of the ETC mechanism, electric current measurements remain consistently within the range of 1.4 to 1.6 amperes at 1200-2000 rpm. This research not only unveils the tangible effects of ETC on engine performance but also underscores its viability as an efficient energy recovery solution in the automotive sector, setting the stage for advancements in sustainable transportation.

Generation of multi-photon Fock states at telecommunication wavelength using picosecond pulsed light

Multi-photon Fock states have diverse applications such as optical quantum information processing. For the implementation of quantum information processing, Fock states should be generated within the telecommunication wavelength band, particularly in the C-band (1530-1565 nm). This is because mature optical communication technologies can be leveraged for transmission, manipulation, and detection. Additionally, to achieve high-speed quantum information processing, Fock states should be generated in optical pulses with as short a duration as possible, as this allows embedding lots of information in the time domain. In this paper, we successfully generate picosecond pulsed multi-photon Fock states (single-photon and two-photon states) in the C-band with Wigner negativities for the first time, which are verified by pulsed homodyne tomography. In our experimental setup, we utilize a single-pixel superconducting nanostrip photon-number-resolving detector (SNSPD), which is expected to facilitate the high-rate generation of various quantum states. This capability stems from the high temporal resolution of SNSPDs (several tens of picoseconds in our case and also in general) allowing us to increase the repetition frequency of pulsed light from the conventional MHz range to the GHz range, although in this experiment the repetition frequency is limited to 10 MHz due to the bandwidth of the homodyne detector. Consequently, our experimental setup is anticipated to serve as a prototype of a high-speed optical quantum state generator for ultrafast quantum information processing at telecommunication wavelength.

Loophole-Free Test of Local Realism via Hardy's Violation.

Bell's theorem states that the quantum mechanical description of physical quantities cannot be fully explained by local realistic theories, laying a solid basis for various quantum information applications. Hardy's paradox is celebrated as the simplest form of Bell's theorem concerning its "All versus Nothing" approach to test local realism. However, due to experimental imperfections, existing tests of Hardy's paradox require additional assumptions of the experimental systems, and these assumptions constitute potential loopholes for faithfully testing local realistic theories. Here, we experimentally demonstrate Hardy's nonlocality through a photonic entanglement source. By achieving a detection efficiency of 82.2%, a quantum state fidelity of 99.10%, and applying high-speed quantum random number generators for the measurement setting switching, the experiment is implemented in a loophole-free manner. During 6h of running, a strong violation of P_{Hardy}=4.646×10^{-4} up to 5 standard deviations is observed with 4.32×10^{9} trials. A null hypothesis test shows that the results can be explained by local realistic theories with an upper bound probability of 10^{-16348}. These testing results provide affirmative evidence against local realism, and establish an advancing benchmark for quantum information applications based on Hardy's paradox.

Updates on Impact Ionisation Triggering of Thyristors

High voltage (HV) generators are used in multiple industrial and scientific facilities. Recent publications have demonstrated that triggering industrial thyristors (relatively slow switching devices) in overvoltage mode, also called impact ionization mode, significantly enhances their dU/dt and dI/dt characteristics. This novel triggering methodology necessitates the application of substantial overvoltage between the thyristor’s anode and cathode, delivered with a swift slew rate exceeding 1 kV/ns. The adoption of compact pulse generators constructed from commercially available off-the-shelf components (COTS) opens up avenues for deploying this technology across various domains, including the implementation of high-speed kicker generators in particle accelerators. In our methodology, we employed commercially available high-voltage SiC MOSFETs along with a custom-designed fast gate driver. This driver was conceptualized based on the recent development of gate boosting techniques, featuring a driving voltage exceeding 600 V. The gate driver for these MOSFETs comprises three key components: a level-shifter with NMOS and PMOS transistors, a compact Marx generator with two avalanche transistors, and a GaN HEMT in a high input and low output impedance configuration. The proposed gate-boosting driver achieves a slew rate exceeding 1 kV/ns for the driving pulse. Furthermore, we demonstrate that with this driver, a 1.7 kV rated SiC MOSFET can produce an output pulse of 1.45 kV and a maximum slew rate of ≈2.5 kV/ns. This gate-boosting driver aims to minimize commutation times, achieves a slew rate of over 1 kV/ns, and handle higher loads, making it ideal for impact ionization triggering of industrial thyristors.

Multidisciplinary Design Methodology for Micro-Gas-Turbines—Part I: Reduced Order Component Design and Modeling

Abstract Ultramicrogas turbines (UMGTs) for electric power generation up to 1 kW are a viable replacement technology for lithium batteries in drones due to their high energy density. Previous research has shown that small-scale effects disqualify conceptual design practices applied to larger gas turbines owing to highly coupled, nonlinear component interactions. To fill this gap, we propose an interdisciplinary conceptual design and analysis framework based on reduced order models. To this end, the current work is divided into two parts covering component design and system integration, analysis, and optimization. In Part I, automated conceptual design of all engine subcomponents is elaborated facilitating interdependent reduced order models for compressor, turbine, combustor and high-speed generator while also considering additive manufacturing constraints. In a second step, the reduced order performance models are compared to computational fluid dynamics (CFD) Reynolds-averaged-Navier–Stokes (RANS) simulations of various turbomachinery geometries as well as experimental data of combustor and high-speed generator prototypes, showing good agreement and thus validating the component modules. In conclusion, the first part of this work elaborates an automated and efficient method to conceptual design of all components required for a functional UMGT. Since the strategy is applicable independent of component arrangement and engine layout, the proposed methods offer a universal framework for small gas turbine generators.

Rotor design optimization of a 4000 rpm permanent magnet synchronous generator using moth flame optimization algorithm

The goal of this paper is to optimize the rotor design parameters of 4000 rpm permanent magnet synchronous generator. The factors namely embrace, offset, outer diameter, and magnet thickness are selected as the design parameters those will be optimized in order to hold the magnetic flux density (MFD) distribution and the flux density on stator teeth and stator yoke within a desirable range while maximizing efficiency. The numerical simulations are carried out in the Maxwell environment for this purpose. The mathematical relationships between the responses and the factors are then derived using regression modeling over the simulation data. Following the modeling phase, the moth flame optimization is applied to these regression models to optimize the rotor design parameters. The motivation is determining mathematical relation between the important design parameters of the high speed generator and the measured responses, when standard M530-50A lamination material is used and then to demonstrate the utility of MFO to the readers on this design problem. The optimum factor levels for embrace, offset, outer diameter, and magnet thickness are calculated as 0.68, 30, 161.56, and 8.92 respectively. Additionally, confirmations are done by using Maxwell and the efficiency is calculated as 94.85%, and magnetic distributions are calculated as 1.64, 0.26, and 0.93 Tesla for stator teeth flux density, stator yoke flux density, and MFD; respectively. The results show that the efficiency is maximized and the magnetic distributions are kept within an appropriate range.

Designing hardware for a robust high-speed cryptographic key generator based on multiple chaotic systems and its FPGA implementation for real-time video encryption

Recent advancements in communication technologies have highlighted the pivotal role of information security for all individuals and entities. In response, researchers are increasingly focusing on cryptographic solutions to ensure the reliability of confidential information. Recognizing the superiority of chaotic systems preference as entropy source of cryptographic systems, this paper proposes a novel true random number generator (TRNG) design by combining four different chaotic systems outputs, tailored for real-time video encryption application. These chaotic systems are continuous-time Lorenz and fractional-order Chen-Lee systems, as well as discrete-time Logistic and Tent maps. This study generates true random bit (TRB) sequences at a high bit rate (25 Mbps) through the hardware implementations of four distinct chaotic systems to have the best statistical randomness in the resulting output. Then, the cryptographic true random key bits (8-bit at 25 MHz frequency) are employed in the post-processing with real-time video data by using the XOR operation, a fundamental post-processing algorithm. The real-time video encryption application is executed on an experimental assembly, composed of a Field Programmable Gate Array (FPGA) development kit, an OV7670 camera module, a VGA monitor, and prototype circuit boards for the chaotic systems. To evaluate the effectiveness of the proposed encryption system, several security assessments are conducted. These include NIST SP 800 − 22 statistical tests, FIPS 140-1 standards, chi-square tests, histogram and correlation analysis, and NPCR and UACI differential attack resilience tests. Consequently, the findings suggest that the presented real-time embedded cryptosystem is robust and suitable for secure communications, particularly in the realm of video transmission.

Design and analysis of a semi-symmetrical double winding with same poles number high-speed permanent magnet generator

Design and analysis of a semi-symmetrical double winding with same poles number high-speed permanent magnet generator

Research on the influence of rotational speed on the performance of high-speed permanent-magnet generator

Research on the influence of rotational speed on the performance of high-speed permanent-magnet generator

A High-speed High-voltage Pulse Generator with Adjustable Falling Slope Based on Programable Multi Narrow Pulses Drive Method for Series MOSFETs

A High-speed High-voltage Pulse Generator with Adjustable Falling Slope Based on Programable Multi Narrow Pulses Drive Method for Series MOSFETs

A High-Speed True Random Number Generator Based on Unified Selector-RRAM

A High-Speed True Random Number Generator Based on Unified Selector-RRAM

A high-speed true random number generator based on Ag/SiNx/n-Si memristor

A high-speed true random number generator based on Ag/SiNx/n-Si memristor

Энергетический комплекс на базе высокооборотной электрической машины

Purpose: The purpose of this study is to develop the scientific basis for designing high-speed electric generators used in conjunction with gas micro-turbines. Methods: To solve the tasks set, the theories of electrical machines; the finite element method; automatic control theory; methods of mathematical analysis, mathematical and circuit modeling; numerical modeling on a PC using FEMM and Matlab Simulink software complexes have been used. The research has been carried out on experimental samples of a high-speed electric generator and confirmed by the results of tests as part of an energy complex based on a gas microturbine in 2019. Results: A complex of scientifically based technical solutions for the design of a high-speed electric generator with an energy complex control system based on a micro-gas turbine has been developed. As a result, a high-speed electric generator for a gas microturbine with a power of 100 kW and a rotation speed of 100,000 rpm has been developed and manufactured. When designing, an asynchronous type electric generator with a massive rotor has been selected. A feature of the developed design is the use of a five-phase stator winding. A control system of an experimental sample of a high-speed electric generator for micro-GTU has been developed. Practical significance: It lies in the development of methods and algorithms for designing high-speed generator equipment for micro-GTU. Recommendations have been developed for choosing the type and configuration of a high-speed electric generator for an electric complex based on a micro-gas turbine. A method is proposed for calculating the parameters of the substitution circuit of a highspeed electric generator, which allows us to determine the parameters of the substitution circuit according to the known configuration of the active layer at the design stage.

A Novel Current Harmonic Suppression Method for HSPMSG Based on the Hybrid Rectifier

This paper presents a novel current harmonic suppression scheme for the high-speed permanent magnet synchronous generator (HSPMSG). Aiming to effectively reduce current harmonics for the HSPMSG, this paper focuses on two areas: improving the rectifier power topology and developing a current loop controller. Firstly, a hybrid rectifier based on Silicon-Carbide/Silicon (SiC/Si) is designed to equivalently increase the switching frequency of the HSPMSG to address the problem of low carrier frequency ratio. In addition, an improved space-vector-modulation (ISVM) strategy based on the hybrid rectifier is proposed. However, the harmonic distortion caused by rectifier nonlinearity will deteriorate as the switching frequency is increased. For further suppressing harmonic disturbances caused by rectifier nonlinearity, a resonant-super-twisting (R-STW) controller is designed by combining the resonant controller and the super-twisting (STW) controller in this paper. The stability of the STW is demonstrated by Lyapunov stability theory and the resonant controller is discretized. Finally, a number of simulations and experiments based on a high-speed permanent magnet synchronous generator are carried out to verify the effectiveness of the control method proposed in this paper.

Parallel turbochargers for small-scale power generation

For countries with insufficient power supply and failing power grid infrastructure, it is usually also expensive to import microturbines. Local manufacturing or local assembling in these countries is therefore an attractive solution. Off-the-shelf turbochargers used in the motor vehicle industry are readily available at relatively low costs because of large-scale manufacturing in this sector. A turbocharger can be developed into a microturbine for power generation; however, coupling a turbocharger shaft directly to a high-speed generator or gearbox can be challenging and complex due to the high speeds and high temperatures involved, as well as the limited space available on the shaft for such a conversion. The novelty of this work was to investigate the effect of mounting two off-the-shelf turbochargers in parallel, where the second turbocharger’s compressor wheel is replaced with a generator. This allows for a higher pressure ratio over the power turbine. A parallel configuration may also have an advantage over a series configuration in terms of cost since the power turbine can be smaller in size. Two different parallel configurations were modelled, namely, a low-temperature turbine (LTT) and a high-temperature turbine (HTT), where the only difference was the position of the power turbine in parallel with the main shaft. Both configurations were modelled at steady state up to compressor pressure ratios of 2, with and without a recuperator, and with and without pressure losses. It was found that the recuperated LTT configuration outperformed the recuperated HTT configuration in terms of efficiency when pressure losses were introduced. Results showed that the optimum LTT combination generated up to 4.06 kW of power at 87 kPa ambient pressure, with a thermal efficiency of 13.26 %, when coupled with a 90 % effective recuperator. For the same case, the HTT configuration produced a maximum efficiency of 8.66 % with a power output of 5 kW.

A Novel Experiment Approach for Measurement Breakup Length, Cone Angle, Sheet Velocity, and Film Thickness in Swirl Air-Blast Atomizers

<div>Measuring the dynamic parameters of liquid fragments generated in the near-field of atomizing sprays poses a significant challenge due to the random nature of the fragments, the instability of the spray, and the limitations of current measuring technology. Precise determination of these parameters can aid in improving the control of the atomization process, which is necessary for providing suitable spray structures with appropriate flow rates and droplet size distributions for various applications such as those used in heat engines. In piston and gas turbine engines, controlling spray characteristics such as penetration, cone angle, particle size, and droplet size distribution is crucial to improve combustion efficiency and decrease exhaust emissions. This can be accomplished by adjusting the structural and/or operating parameters of the fuel supply system. This article aims to measure the breakup length, spray cone angle, axial velocity, breakup time, and liquid sheet film thickness for a swirl air-blast atomizer used in a gas-steam engine. The measurement was conducted using a shadowgraph imaging system developed specifically for this study, consisting of a high-speed camera, a lens, and a light source. While lasers are commonly used as light sources in the literature, this study utilized a special LED high-speed pulse light generator, which is cheaper, easier to handle, and provides a more uniform background. Images were processed using a MATLAB code developed for this study. Although the breakup zone is naturally random and the breakup location significantly varies with time, the novel method developed in this study helps quantify critical parameters under different operating conditions.</div>

Use of Synchronous Generators for Gas Turbine Power Plants

The combination of gas turbine engines and low-speed generators that are part of power plants is a large-mass unit with low specific indicators of the mass-to-unit power ratio. (Research purpose) The research purpose is developing a new kinematic scheme of a gas turbine engine with a high-speed synchronous electric generator, higher reliability and long service life, reduced weight and size characteristics of the power plant. (Materials and methods) Established that small gas turbine power and general-purpose power plants are not produced in Russia, research work was not systematic. It was determined that synchronous generators and gas turbine engines are used on two-shaft kinematic systems that reduce the rotation frequency of the generator rotor, where a large diameter of the free turbine entails a higher level of vibration, and due to the high level of sliding leads to a lower torque of the power plant at low rpm. (Results and discussion) It has been shown that the use of single-channel kinematic schemes contributes to simpler control, this opens up a wide prospect for their use in power plants for the purpose of supplying electricity to consumers and mobile agricultural vehicles. A new kinematic scheme of a high-speed generator has been developed, in which the rotor and stator interact with each other according to the type of sliding bearing. (Conclusions) The advantages of using a single-shaft kinematic scheme for the joint operation of a gas turbine engine with a high-speed synchronous generator have been revealed, which are expressed in a smaller moment of straining of the rotor and the absence of a sliding coefficient between the shafts. It was stated that as a result of using the proposed design of the power module, the reliability of the generator increases, the operating speed increases due to the use in the design of the polished outer surface of the rotor and the polished inner surface of the stator, working according to the type of sliding bearing, with forced oil supply at a pressure of 2-5 kilograms per square centimeter, at the same time, heat removal from the stator winding improves.

A 12-Bit 2 GS/s Single-Channel High Linearity Pipelined ADC in 40 nm CMOS.

This paper presents a single-channel 12-bit, 2 GS/s pipelined analog-to-digital converter (ADC) for wideband sampling receivers. The design adopts a novel source follower input buffer with multiple feedback loops to improve sample linearity and extend bandwidth. Additionally, an improved two stages charge pump amplifier topology is introduced, which doubles the Gain Bandwidth Product (GBW) without consuming additional power. To address the back-end ADC and background calibration, a multi-level dither strategy is employed, utilizing a new high-speed and low-cost uniform distribution pseudorandom code generator. The prototype ADC fabricated in 40 nm CMOS process achieves 68.24 dB SFDR up to Nyquist frequency with a sampling rate of 2 GS/s. Measurement results demonstrate a bandwidth exceeding 5 GHz, resulting in a Schreier FOMs of 152.4 dB.