Propulsion Motor Research Articles

CONTROL OF ELECTRIC SHIPS’ PROPULSION MOTORS WHEN MOVING ON CURVILINEAR TRAJECTORY

Purpose. The aim of the work is to search for the optimal control of the electric ships’ propeller motors (PM) while moving on curvilinear trajectory. The indices characterizing the vessel were selected as the criteria of optimality. Methodology. Optimal control laws of PM providing electric ships’ best maneuverability can be found by joint consideration of the electric propelling plant (EPP), propellers and hull. Results. A method of calculating the transient regimes of the electric ships’ propulsion complexes during maneuver has been developed. A new method of forming the PM control laws is proposed. The nature of the target functions is revealed and a method of optimizing the parameters of control signals is developed. Optimization calculations have been carried out and the optimal control of the electric ships’ propeller motors when moving along curvilinear trajectory has been found. Optimization has been carried out by the criterion of minimum energy consumption and by the criterion of minimum ship’s distance. The optimization efficiency is illustrated. Scientific novelty. The method of searching for the optimal control laws is constructed according to the system principle, which allows optimizing the control of the propulsion motors by the final result. Practical value. The proposed recommendations can be used in the design of electric propelling plants and in their operation.

An acoustic remote sensing method for high-precision speed estimation of micro-UUVs

Understanding the dominant sources of acoustic noise in unmanned underwater vehicles (UUVs) is important for passively tracking UUVs and for designing quieter propulsion systems. This work describes how the speed of a vehicle can be passively measured by the unique high frequency acoustic signature of a brushless DC motor propulsion system. First, the causes of high frequency tones were determined through direct measurements of two micro-UUVs and an isolated thruster. From this analysis, the vehicle noise was mapped to speed and the common and dominant features of noise were established: strong tones at the motor's pulse-width modulated frequency and its second harmonic, each of which is a carrier with sidebands at frequency intervals equivalent to the propeller rotation frequency multiplied by the poles of the motor. Field experiments were performed where the speed of two micro-UUVs was predicted by measuring the sidebands of the two dominant tones. When the mapping of rotational to translational speed of the UUV was known, this method produced speed predictions with 0.004 m/s accuracy. These findings are applicable to many off-the-shelf vehicles available today which rely on brushless DC motors and can be easily integrated into passive acoustic security systems for target motion analysis. [Work supported by the Department of Defense NDSEG program, ONR, and Draper.]

Phase‐current waveform for switched reluctance motors to eliminate input‐current ripple and torque ripple in low‐power propulsion below magnetic saturation

In recent decades, switched reluctance motors (SRMs) have been attracting increasing attention as a promising type of traction motors for electric vehicle propulsion, owing to their robust construction, elimination of permanent magnets. However, their phase inductance profile contains significant high-order harmonics, which generates input-current and torque ripples under SRM drive with the conventional square phase-current waveform. This study solves this problem by proposing a novel phase-current waveform in replacement of this square waveform. The proposed waveform is a predetermined waveform that can be stored as a look-up table in the inverter controller and can be magnified or attenuated to adjust the output torque, similarly as the conventional square waveform. Certainly, SRMs generally exhibit magnetic non-linearity due to magnetic saturation, which complicates the analysis. Therefore, the proposed waveform is analytically derived under the assumption that the magnetisation of the motor remains below the saturation level because vehicle propulsion tends to require a torque output far smaller than the maximum rating of the motor in normal vehicle travel. The proposed phase-current waveform is experimentally tested in comparison with the conventional square phase-current waveform. Consequently, the proposed waveform revealed smaller ripples in both the input-current and torque, supporting the effectiveness of the proposed phase-current waveform.

Effects of optogenetic activation of the enteric nervous system on gastrointestinal motility in mouse small intestine.

Recently, it was demonstrated that optogenetics could be used to stimulate enteric calretinin neurons, leading to increased colonic transit in vitro and in vivo. The aim of the current study was to determine if similar approaches could be used to stimulate the isolated mouse small intestine, with the aim of potentially also improving transit in the small bowel. Cre-Lox recombination was used to generate transgenic mice expressing the light-sensitive ion channel channelrhodopsin-2 (ChR2) in calretinin neurons. Spontaneous migrating motor complexes were recorded from isolated terminal small intestine in both CalCre+ mice expressing ChR2 in calretinin-expressing neurons and experimental controls, CalCre-. Trains of blue light pulses (20ms, 5Hz, 20s) evoked a brief local contraction of circular muscle, but never a premature MMC, irrespective of light intensity (1-40mV/mm2) or the region of ileum stimulated. However, MMCs were readily evoked by calretinin neuron activation in colon, consistent with our previous study. Light-evoked contractions of the terminal small bowel were hexamethonium-resistant (300μM), but blocked by tetrodotoxin (0.6μM). Light-evoked smooth muscle contraction did not change the pacemaker frequency underlying MMCs. Focal illumination of the small intestine does not appear as effective at inducing propulsive motor activity as has been demonstrated in the colon of the same colony mice. This study suggests caution should be exercised when assuming optogenetic technology is equally effective at increasing GI transit in the small intestine as in the large intestine of mice.

Comparison Between Coreless and Yokeless Stator Designs in Fully-Superconducting Propulsion Motors

Hybrid electric propulsion could be the solution to the ambitious environmental targets of the aerospace industry. Fully-superconducting machines have the potential to deliver the step-change in specific torque, power, and efficiency capabilities required for large civil transport aircraft applications. However, fully-superconducting machines are still in their infancy. This article investigates the electromagnetic design of two different stator design concepts for an ac fully-superconducting machine for an aerospace distributed fan motor application. A benchmark aerospace specification of 1 MW was chosen and the design of a conventional permanent-magnet machine was used to assess the performance of the two equivalent fully-superconducting ac motor designs. Following the guidelines from an experimental study of the losses in a small ac stator prototype with MgB2 coils, a fully-superconducting air-cored stator design and a new yokeless stator design are proposed. Both ac superconducting machine designs use superconducting bulk magnets mounted on a rotor core and an MgB2 superconducting stator winding. This article discusses the key design issues of the two stator layouts in relation to the current aerospace targets for efficiency and power density.

전기추진선박의 제어전원 및 보조장치 전원공급용 DC/AC 인버터의 입력전압변동 시험평가 및 분석

The main power supply of electric vehicles and ships is generally composed of a battery, a generator and a fuel cell, and a propulsion motor and inverter are used as a driving device. In addition to the main power supply for electric power-driven driving, additional auxiliary power supply for control system and auxiliary system is required, and power conversion devices (inverters and converters) are used for this purpose. Power conversion devices for auxiliary power supply receives power from main power supply such as battery, generator and fuel cell and performs the AC or DC power conversion. The voltage variation of main power supply depends on the usage conditions of electric propulsion system. The power conversion devices for auxiliary power supply shall not cause output stop even if the voltage of main power supply suddenly changes to the allowable voltage range. The output of the power conversion devices for auxiliary power supply shall have an operating capability to produce a stable output within the permitted voltage range. This paper deals with the test evaluation and analysis for the input voltage fluctuation of the DC/AC inverter(power conversion devices) in auxiliary power supply of electric ship..

Performance Analysis of Axial-Injection, End-Burning Hybrid Rocket Propulsion System

Although several investigations have been performed regarding the fundamental physics of axial-injection, end-burning hybrid rocket motors, investigations into the mission performance of a propulsion system based on this hybrid rocket motor configuration are limited. This Paper provides analysis of the performance characteristics of axial-injection, end-burning hybrid rocket motors based on the results from experimental tests in the literature. Notional propulsion systems were sized using the observed regression rates and characteristic velocities. These propulsion systems were then evaluated to determine the Delta-V that could be provided by an axial-injection, end-burning hybrid motor propulsion system using a plastic fuel and gaseous oxygen or nitrous oxide as the propellants. These Delta-V calculations were performed for different sizes of satellites. Finally, the calculated Delta-Vs were compared to those required for different maneuvers to evaluate the usefulness of axial-injection, end-burning hybrid rocket motors. Results from the analysis indicated that the provided specific impulse ranged from the mid-200 to -300 s depending on chamber pressure and expansion ratio, while the Delta-V values were in the several hundred meters/second range depending on the satellite mass. Overall, the Delta-V provided were sufficient for a variety of orbital maneuvers including altitude adjustments, orbit phasing, orbit maintenance, and deorbiting.

Making the Case for Switched Reluctance Motors for Propulsion Applications

This paper makes the case that Switched Reluctance Motor (SRM) is an exceptionally attractive technology to respond to the increasing demand in propulsion applications for high-efficiency, high-performance, and low-cost motors with a more secure supply chain. The paper also presents methods to effectively reduce torque ripple and acoustic noise, which have been the major issues impeding the widespread use of SRMs. Finally, SRM designs for two propulsion motors, one for an e-bike and the other for a hybrid electric vehicle application, are presented which have been proposed to replace permanent magnet machines.

Superconducting motors for aircraft propulsion: the Advanced Superconducting Motor Experimental Demonstrator project

The European Union-funded Advanced Superconducting Motor Experimental Demonstrator (ASuMED) project started in May 2017 with the purpose of demonstrating the benefits of a new, fully superconducting motor for reaching the targets established by the Flightpath 2050 plan. The project aims at a motor power density of 20kW kg−1 using a high-temperature superconducting (HTS) stator. The rotor will use HTS stacks operating like permanent magnets. A highly efficient cryostat for the motor combined with an integrated cryogenic cooling system and associated power converter will be used. This article provides a general overview of the prototype that is currently being assembled and that will be tested soon.

Researches regarding the Applications of Permanent Magnet Motors for Vehicle Propulsion

In this paper the author presents a laboratory bench used to test Permanent Magnet (PM) motors for vehicle propulsion. The general schemas for the bench, the PM motor types tested, the traction characteristics and some experimental results are evaluated. These techniques are appropriate for teaching students in practical laboratory applications regarding electrical and hybrid vehicles. Students are able to improve their practical skills and also to develop research projects jointly with the teaching staff.

Гребной электродвигатель переменного тока на основе бесконтактной машины двойного питания

Гребной электродвигатель переменного тока на основе бесконтактной машины двойного питания

Voltage-Based Current-Compensation Converter Control for Power Electronic Interfaced Distribution Networks in Future Aircraft

Superconductors have a potential application in future turboelectric distributed propulsion (TeDP) aircraft and present significant new challenges for protection system design. Electrical faults and cooling system failures can lead to temperature rises within a superconducting distribution network, which necessitates a reduction or temporary curtailment of current to loads to prevent thermal runaway occurring within the cables. This scenario is undesirable in TeDP aircraft applications where the loads may be flight-critical propulsion motors. This article proposes a power management and control method that exploits the fast-acting measurement and response capabilities of the power electronic interfaces within the distribution network to maximize current supply to critical loads, reducing the impact of a temperature rise event in the superconducting distribution network. This new algorithm uses the detection of a resistive voltage in combination with a model-based controller that estimates the operating temperature of the affected superconducting cable to adapt the output current limit of the associated power electronic converter. To demonstrate the effectiveness of this method and its impact on wider system stability, the algorithm is applied to a simulated voltage-source converter supplied aircraft dc superconducting distribution network with representative propulsion motor loads.

Superconducting Synchronous Motors for Electric Ship Propulsion

This paper develops a notional design for a 36 MW, 120 rpm motor for ship propulsion. The design exhibits high torque density (66 Nm/kg) and high efficiency (99%). This synchronous motor uses LTS (low temperature superconducting) field coils to create a minimum of 2 T magnetic field in the air gap of the motor. The motor is substantially lighter, more compact, and far more cost effective than other compared approaches. A significant feature of the LTS motor is reduction in radial forces between the field and armature by two orders of magnitude compared to a conventional motor. The motor promises significant cost and performance improvement. Conductor requirements, options, and electromagnetic features such as quench protection and cryogenic support options are discussed.

Improved control of propeller ventilation using an evidence reasoning rule based Adaboost.M1 approach

Marine propeller ventilation, which can occur in extreme seas, reduces energy efficiency of the ship, and can result in significant safety hazards during navigation. A major maritime challenge is to predict water levels during extreme seas and manage an appropriate control strategy for the propulsion system with fast response times. Here we report application of an evidence reasoning (ER) rule-based Adaboost.M1 approach to rapidly estimate propeller ventilation levels thereby improving propulsion management. The ER rule was used as the weak learner of Adaboost.M1 to extract torque signal from the propulsion motor and current signal from the propulsion inverter. First, K-means clustering was used to select the reference value sets of each weak learner. Second, the extracted signals were transformed into multiple pieces of identification evidence, which were combined through ER to estimate the ventilation level by present weak learner. Parameters of the weak learner were then updated according to the estimation results. Finally, the weak learners that had completed training were combined into a strong learner to estimate final ventilation levels. Experimental results showed that the estimation accuracy of the weak learner provided by the ER rule for Adaboost.M1 approach was more than 50%, which resulted in the accurate estimation by the strong learner. This approach provides an important technical advance to allow more effective switching control strategies for marine electric propulsion systems under different sea conditions.

Loss characteristics of HTS coated conductors in field windings of electric aircraft propulsion motors

High-temperature superconducting (HTS) coated conductors (CCs) are widely regarded as a promising candidate to enable very high power density motors. These machines operate at high rotational speeds, with some designs going up to 12 000 rpm. HTS CCs are applied to the field windings of these motors to increase the magnetic loading and hence the power density. Even though the superconducting field windings operate with a DC current, due to the magnetic field environment, losses are present. This paper examines the dynamic and total loss characteristics of YBCO-coated conductors in the frequency range relevant to high-speed motors for electric aircraft propulsion. A multi-layer model was created using the H-formulation and the losses for each layer were highlighted. For the first time, it was shown that the DC transport current region in the HTS layer shrinks as the frequency of the applied field increases due to the increased magnetisation current around the edges of the CC, which reduces the dynamic loss per cycle as the frequency increases. To fully understand the loss distribution in the HTS CC, the total loss in the conductor was investigated. For an applied magnetic field of 100 mT and 800 Hz, more than 30% of the total loss occurs in the copper layer due to the decreased penetration depth of the magnetic field and the skin effect. Results show that to accurately model and understand the losses in superconducting field windings, a multi-layer model should be used, since a significant proportion of loss shifts towards the copper stabilizers. Over all, it was shown that both the dynamic loss as well as magnetisation loss play a crucial role in the estimation of the loss in superconducting field windings.

Review on the Effects of High Heeled on Body Posture Based on Medical Images

Purpose: From a motor control perspective, the balance and propulsion are needed to proceed smoothly, and using high heeled shoes based on two conditions led to more difficult and complex gait. High heeled alter the natural form of body and present a chain reaction of disadvantageous affected that throughout the entire body from the toe to spine. Therefore, the purpose of this review provides a comprehensive guide of understanding HH gait. Methods: Electronic database which includes PubMed, Embase, Medline, Amed, and Cinahl were searched for controlled trials comparing high heeled shoes with barefoot or flat shoes, which include changes of the lower limb and upper limb. The kinematic change of body was the primary outcome measure. The comparison was conducted with mean differences and 95% confidence intervals. Result: Major findings were focused on the joint of the ankle, knee, hip, pelvis, and spine. The results of collecting articles show that a significant difference in ankle and knee joint during the gait when high heels and barefoot are compared. There are still conflicting results in terms of lumbar lordosis, and few studies indicate that the pelvic anteversion increased significantly. Conclusion: On direction for future research should establish an effective method to estimate the result of the HH effect on body posture.

Field Prediction and Validation of a Slotless Segmented-Halbach Permanent Magnet Synchronous Machine for More Electric Aircraft

High-performance propulsion motors for more electric aircraft (MEA) are highly appreciated in transportation electrification. For the widely adopted permanent magnet synchronous machines (PMSMs) for MEA propulsion, the segmented Halbach magnetization has distinct merit that it contributes to sinusoidal air-gap magnetic fields for smooth operation. However, it is hard to fast predict the field distribution and machine performance due to the model complexity. Based on the subdomain method, this article first proposes an exact analytical model for slotless PMSM with the segmented Halbach PMs. Then, the model is applied in the fast computation of the magnetic field and performance prediction. Subsequently, the analytical results are compared with the finite element method (FEM), including the flux density, flux linkage, induced voltage, and steady-state torque at different loads. Also, the computation burden and prediction error are included to validate the model’s rapidity and accuracy. Finally, by prototype fabrication and unique field measurement methods, the flux density distribution is originally validated.

A Study on Speed Control Method of Propulsion Motor for Small Ships with AFE Converter

Research of electric propulsion system have been conducted to minimize the occurrence of marine environmental pollution and maintenance costs in small ships such as coastal passenger ships, cruise ships and fishing boats. Speed control methods induction motor that are widely used in large electric propulsion ships has low control characteristics in the low speed range, and therefore, the performance of the steering is very deteriorated in ships with a large number of the entry and departure of port. Therefore, in this paper, the vector control algorithm with the AFE rectifier is applied to induction motor and speed control performance at low speed range has been improved. and it was verified through computer simulation using PISM program.

On the nature of high-amplitude propagating pressure waves in the human colon.

Characterization of high-amplitude propagating pressure waves (HAPWs or HAPCs) plays a key role in diagnosis of colon dysmotility using any type of colonic manometry. With the introduction of high-resolution manometry, more insight is gained into this most prominent propulsive motor pattern. Here, we use a water-perfused catheter with 84 sensors with intervals between measuring points of 1 cm throughout the colon, for 6-8 h, in 19 healthy subjects. The catheter contained a balloon to evoke distention. We explored as stimuli a meal, balloon distention, oral prucalopride, and bisacodyl injection, with a goal to optimally evoke HAPWs. We developed a quantitative measure of HAPW activity, the "HAPW Index." Our protocol elicited 290 HAPWs. 21% of HAPWs were confined to the proximal colon with an average amplitude of 75.3 ± 3.3 mmHg and an average HAPW Index of 440 ± 58 mmHg·m·s. 29% of HAPWs started in the proximal colon and ended in the transverse or descending colon, with an average amplitude of 87.9 ± 3.1 mmHg and an average HAPW Index of 3,344 ± 356 mmHg·m·s. Forty-nine percent of HAPWs started and ended in the transverse or descending colon with an average amplitude of 109.3 ± 3.3 mmHg and an average HAPW Index of 2,071 ± 195 mmHg·m·s. HAPWs with and without simultaneous pressure waves (SPWs) initiated the colo-anal reflex, often abolishing 100% of anal sphincter pressure. Rectal bisacodyl and proximal balloon distention were the most optimal stimuli to evoke HAPWs. These measures now allow for a confident diagnosis of abnormal motility in patients with colonic motor dysfunction.NEW & NOTEWORTHY High-amplitude propagating pressure waves (HAPWs) were characterized using 84 sensors throughout the entire colon in healthy subjects, taking note of site of origin, site of termination, amplitude, and velocity, and to identify optimal stimuli to evoke HAPWs. Three categories of HAPWs were identified, including the associated colo-anal reflex. Proximal balloon distention and rectal bisacodyl were recognized as reliable stimuli for evoking HAPWs, and a HAPW Index was devised to quantify this essential colonic motor pattern.

Position Estimation of a PMSM in an Electric Propulsion Ship System Based on High-Frequency Injection

To improve the operating performance of electric propulsion ships, the permanent magnet synchronous motor is commonly used as the propulsion motor. Additionally, position estimation without sensors can further improve the application range of the propulsion motor and the estimated results can represent the redundancy of measured values from mechanical sensors. In this paper, the high-frequency (HF) injection algorithm combined with the second-order generalized integrator (SOGI) is presented on the basis of analyzing the structure of the electric propulsion ship and the vector control of the motors. The position and rotor speed were estimated accurately by the approximate calculation of q-axis currents directly related to the rotor position. Moreover, the harmonics in the estimated position were effectively reduced by the introduction of the second-order generalized integrator. Then, the rotor position estimation algorithm was verified in MATLAB/Simulink by choosing different low speeds including speed reversal, increasing speed, and increasing load torque. Finally, the correctness of the proposed improved high-frequency injection algorithm based on the second-order generalized integrator was verified by the experimental propulsion permanent magnet synchronous motor (PMSM) system at low speed.