Electric Ship Propulsion Research Articles

Energetska optimizacija serijskog hibridnog električnog brodskog porivnog sustava

The electric ship propulsion system due to its economic advantages and, first of all, better mechanical properties than internal combustion engines (influence on ship manoeuvrability) have gained popularity in recent years. This paper presents an investigation of a series hybrid electric propulsion system where two sources of power are used: a permanent magnet synchronous generator and energy storage battery to supply electric propulsion system, which is a permanent magnet synchronous motor. Controlling the power flow from multiple power sources in a series hybrid mechatronic system is important to increase the energy efficiency of the propulsion system. Developing a suitable power flow control method is difficult due to the nonlinear nature of the power sources in the series system. In this paper a method of energy optimization of the system has been verified which allows to improve energy efficiency by reducing reactive power in the system. In this paper, an analytical study of the mechatronic system of a serial hybrid electric ship propulsion system is carried out based on the analysis of the steady-state electromagnetic and energy relations. The proposed control with energy optimization was compared with the commonly used FOC control. The analytical studies have been confirmed by performing simulation studies in Matlab-Simulink program. The proposed optimization method allows its use not only in ship electric drives but also in other autonomous electric drives using the series topology of the hybrid system.

Second Life Management From Battery Storage System of Electric Waterborne Transport Applications: Perspectives and Solutions

In electric naval applications, battery storage management plays a key role. The second-life battery use is a fundamental part of the sustainable development of these waterborne transport systems. The article deals with the perspective and solutions of the second-life storage battery systems from the electric ship traction area. This paper presents an overview of the topic of second-life use, application, and future direction with a special focus on battery systems from electric propulsion ships. In particular, a modular converter-battery approach in the storage system structure arrangement is considered. The modular battery storage approach in electric naval propulsion applications is the target of SEABAT project. This proposed solution allows both controls of the electrical quantities of the storage output and monitoring of the battery’s electrical parameters to always have its health status available. The advantages of the modular multilevel battery-converter structure developed within the SEABAT project towards second-life use are presented and evaluated, leading to an estimated cost saving of 35% during the whole life time of the batteries. Besides, the integration of multiple battery technology with different degradation state is enabled. Moreover, the power converter features for second-life applications are explored and discussed. Furthermore, the manufacturing and disassembly processes aspects of the SEABAT converter-battery system (CBS) are also investigated to validate the effectiveness of the proposed modular storage solution. The SEABAT project targets a 246 kWh demonstrator with a 1000 V output.

Подхват асинхронного двигателя после потери питания транзисторного электропривода

The solution of the problem of connecting an asynchronous machine with a squirrel-cage rotor to a transistor converter after their disconnection in the absence of a rotor speed sensor is considered. This problem may arise in the drives of pumps, fans, in wind power plants and in other systems, if it is necessary to urgently breaking the mechanism or to ensure its uninterrupted operation. In the article, the problem is solved in relation to the ship's electric propulsion system. When the drive power is lost, the propeller and the rotor of the machine are first slowed down relatively quickly to a speed corresponding to the speed of the vessel. Then braking slows down due to the large inertia of the vessel. The significant duration of the process allows the use of an algorithm for determining the rotor speed, based on testing the machine by feeding the stator of an asynchronous motor from an inverter with low voltages with a frequency that varies within the specified limits. Mathematical and computer models of the system are constructed, numerical experiments are performed confirming the effectiveness of the considered solution.

Optimal Control of the Diesel–Electric Propulsion in a Ship with PMSM

The article presents and compares two different control methods for a permanent magnet synchronous motor (PMSM) for diesel–electric ship propulsion. The main focus of the article is on control optimization, which allows improving energy efficiency by reducing reactive power in the mechatronic propulsion system. The first method consists in modifying the commonly used field-oriented control (FOC) strategy to ensure zero reactive power in the inverter–PMSM system. Since a characteristic of ship propulsion systems, unlike those used on land, is the step load on the propulsion motor, the system’s performance in dynamic states is particularly important. Unfortunately, control strategies based on FOC do not take into account the dynamics of the system, since they apply only to steady states. Therefore, the authors of this paper, based on control theory methods, proposed an approach that also optimizes control in dynamic states, while minimizing reactive power in the steady state. The analytical studies were confirmed in simulation studies using the MATLAB Simulink package.

Simulation research on ship electric propulsion speed regulation system based on variable structure control and FPGA

In order to improve the operating effect of the ship electric propulsion speed control system, this paper combines variable structure control and FPGA to study the ship electric propulsion speed control system, and simulates and analyzes the system. Moreover, this paper adopts a modular design and divides the FPGA design into different modules such as AD sampling control, AD data processing, logic state acquisition and control, PWM pulse generation and control, RTC control, and DTS control. In addition, this paper constructs a ship electric propulsion speed regulation system based on variable structure control and FPGA. Finally, this paper conducts simulation research on the system and counts its corresponding data. The main parameters are control reliability and speed regulation effect. According to the simulation test results, the ship electric propulsion speed control system based on variable structure control and FPGA proposed in this paper can effectively improve the propagation speed control effect.

A Comparative Study of Fuzzy SMC with Adaptive Fuzzy PID for Sensorless Speed Control of Six-Phase Induction Motor

Multi-phase motors have recently replaced three-phase induction motors in a variety of applications due to the numerous benefits they provide, and the absence of speed sensors promotes induction motors with variable speed drives. Sensorless speed control minimizes unnecessary speed encoder cost, reduces maintenance, and improves the motor drive’s reliability. The performance comparison of the fuzzy sliding mode controller (FSMC) with adaptive fuzzy proportional integral derivative (AFPID) control methods for sensorless speed control of six-phase induction motors was analyzed in this study, and the proposed control system has an advantage for multiphase machines, specifically six-phase induction motors (IMs) in this study, as they are the current active research area for electric vehicles, hybrid electric vehicles, aerospace, ship propulsion, and high-power applications. The speed control of a six-phase induction motor was performed by using an AFPID controller and FSMC. The comparative performance analysis was based on sensorless speed control of the six-phase induction motor. A proportional integral derivative (PID) controller is commonly employed as it is used to eliminate oscillations, but it has several drawbacks, such as taking a long time to decrease the error and stabilize the system at constant speed. The fuzzy type-2 and PID controllers were hybridized so as to obtain the advantages of both to enhance the system performance. Finally, the comparison result revealed that the FSMC preforms significantly better by achieving good tracking performance. The control technique maintains the sliding mode approach’s robustness while providing reduced overshoots with a smooth control action, and the FSMC revealed good dynamic response under load variations when compared to the AFPID controller.

Multiple Instance Learning With Random Forest for Event Logs Analysis and Predictive Maintenance in Ship Electric Propulsion System

In this article, a novel weakly supervised machine learning approach is proposed for intelligent predictive maintenance (IPdM). It employs balanced random forest and multiple instance learning based on event logs from ships’ electric propulsion systems. The objectives are predicting failure likelihood, time to failure, and explainable predictions to ensure timely crew intervention. The IPdM approach uncovers, then learns, and classifies <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sequences of</i> events that represent early causes or symptoms to forecast imminent failures. In particular, this article contributes effective solutions to irregular, imbalanced, and unlabeled data issues where conventional methods become obsolete. First, the events occur at irregular intervals; they include alarms, warnings, and operational information collected across multiple units and control systems. Second, the datasets exhibit extreme imbalance due to few failures and multiple failure modes; this entails biased predictions. Third, the training datasets are weakly labeled; only the failure timestamp is known without any expert input on prior causes or early symptoms. Temporal random indexing is proposed to transform textual log messages into a numerical lower dimensional space where timeseries analyses are applicable. Balanced random-forest models are developed for unbiased classification and regression. The overall approach learns recursively the ungiven data labels while training the base learners. The IPdM approach is validated through millions of events of multithousand types collected from two years of seagoing vessels. It successfully forecasts actual propulsion failures and performs better when compared with contemporary methods.

Lifecycle energy solution of the electric propulsion ship with Live-Life cycle assessment for clean maritime economy

This study was planned to offer the roadmap for lifecycle clean shipping by addressing the fundamental question of ‘what are the promising energy solutions for the shipping sector?’. This goal was attempted to be achieved by a lifecycle comparative analysis of the viability of three zero-carbon fuels, ammonia, hydrogen, and inland electricity, based on the operational practicality as well as Well-to-Wake environmental impacts. Credible business scenarios were designed with a high-level screening of 27 short-route ferries currently engaged in 26 West-Scotland coastal routes. Then a series of comparative analyses between the diesel and the proposed alternative fuel sources was conducted. While carbon-free fuels are in the early stages of development in the UK, there are various views on how these fuels can be produced, distributed, and used onboard for the clean shipping economy. To determine the optimal energy solutions, all credible scenarios for the upstream pathways for these fuels were developed, based on the current and future prospected UK energy infrastructure and grids. Those scenarios were examined for West-Scotland shipping and extended to the UK targets. Their technical aspects for maritime application were also investigated in consideration of safety, regulation, infrastructural availability, supply chain constraints, barriers, and the downstream emission pathways to their uptake onboard. Ship conceptual designs were briefly conducted to evaluate the systems, technologies, and equipment required for onboard installation to utilise zero-carbon fuels. As a result of the study, when hydrogen was used as a fuel in fuel cells and electricity was supplied as a backup from batteries that store inland power and the solar PV system, GHG emissions were 25.7% of the conventional fossil fuel-using scenario. In addition, it was confirmed that GWP was 22.2% compared to MGO when ammonia was used as fuel without reforming into hydrogen and backup power was supplied from batteries and the solar PV system. It is believed that the analysis results can distinctively demonstrate the adequacy or the inadequacy of current maritime policies for decarbonising shipping. This research finally provides potential solutions for future UK maritime environmental protection and for enhancing the competitiveness of ship owners. In addition, this research concept can serve as a sample that suggests the direction of ideal research for future energy solutions in the marine sector.

Research on Application of High-Frequency Pulse Vibration in Ship Electric Propulsion System

Aiming at the problems existing in the method of using sensors to detect the rotor position of marine main propulsion motor at low speed, a sensorless rotor position identification method based on high-frequency pulse vibration signal is proposed. In this method, the low-pass filter is used to separate the high-frequency signal component, and the current component of d-axis to q-axis is demodulated. The control mode of PI action law is used to phase-locked processing of the demodulated signal, in which purpose is to obtain the rotor position signal. The design method is simulated and verified by MATLAB/Simulink software. The error between the estimated position and the actual position of the rotor in the simulation waveform is small, and the accuracy is high. The simulation results show that this method can achieve good results when applied to the ship electric propulsion system without position sensor, which provides a theoretical reference for the design of marine main propulsion motor control system.

Green Fuels (Green Hydrogen, Green LNG) in Maritime-Shipping for Centralized or Decentralized Heating, Electric Power Supply and Ship Propulsion

Nowadays heavy fuel oil and Diesel are mostly used on merchant and passenger ships. Soon international and especially national governmental regulations will increase recommendations for maritime shipping in Europe and worldwide. The main reasons are high air polluting emissions like ne dust, Nitrogen Oxide and Sulphur Oxide, as well as the recommendations of reducing the Greenhouse Gas Emissions like Carbon Dioxide. Green fuels allow to reduce those emissions. Therefore, the International Maritime Organization (IMO) create the Maritime Pollution contract (MARPOL). The MARPOL Annex VI gives the possibility to de ne strictly controlled air polluting areas for SOx and NOx (Emission-Controlled Areas, ECAs or SECAs). The state-of-the-art shows that hydrogen and LNG can be safely operated and used to supply electric generating systems and drive systems. Especialy cruise ships nowadays were constructed with LNG main propulsion engines. Conventional hydrogen or LNG are not CO2 free. With green hydrogen or ammonia and green LNG, based on renewable electrical energy, CO2 emissions could be reduced. The paper compares different green fuels to classical fuels in maritime applications, regarding pros and cons, emissions, safety aspects and the green renewable production of such fuels.

Position Estimation of Fault‐Tolerant Permanent Magnet Motor in Electric Power Propulsion Ship System

The electric power propulsion is becoming the important development direction of ship propulsion technology recent years, as it is conducive to the realization of automation, intelligence, reduced noise, enhanced propulsion efficiency, high power density, flexible arrangement, and energy saving. The good fault‐tolerant capacity and robustness of the fault‐tolerant permanent magnet motor (FTPMM) make it a potentially highly effective and economical propulsion motor in the electric power propulsion ship than other alternatives. In this paper, the structure and mathematical model of FTPMM are analyzed and the improved sliding mode observer (SMO) is constructed according to the deviation between the observed currents and actual currents. Combined with model reference adaptive control (MRAC) method and the phase‐lock loop (PLL), the switch function is replaced by the continuous Sigmoid function to reduce the chattering and finally the rotor position estimated accuracy is improved. When the motor winding open‐circuit and short‐circuit fault occur, the current vector fault‐tolerant control strategy is introduced into the improved SMO algorithm, and the rotor position is estimated accurately under faulty conditions. Finally, the proposed improved SMO position estimation algorithm under healthy and faulty conditions is verified in Matlab/Simulink. The FTPMM position sensorless technology would play a critical role in the electric power propulsion ship, and may have a profound impact on the high‐performance advanced ships and green shipping industry as well. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Comparative Analysis on AC and DC Distribution Systems for Electric Propulsion Ship

Decarbonization is an ongoing issue in the shipping industry, and electric propulsion systems are being proposed as alternative solutions to satisfy this requirement. To answer the fundamental questions of “Are electric propulsion systems the green solution?” and “Can DC distribution systems contribute to the decarbonization in shipping?”, this paper analyzed DC distribution system electrical characteristics, economic feasibility, and environmental evaluation for a full-scale AC-DC hybrid distribution electric propulsion system facility. By applying the actual ship’s operating profile as inputs, a DC distribution system with an active front end rectifier and a variable speed generator engine was proven to guarantee the same electric stability as the conventional AC distribution system. The life cycle assessment results achieved economic and life cycle environmental benefits of about 10% (8.9% for Case 1 and 12.4% for Case 2). These research findings offer meaningful insights into the DC distribution system to minimize fuel consumption and emissions toward cleaner shipping.

Application of composite energy storage device in ship electric propulsion system

Application of composite energy storage device in ship electric propulsion system

All-Electric Cargo Ships Data Analysis and Efficiency vs Fuel Ships Comparison

This paper scrutinizes the common belief that electric vessels are economically unadvantageous. To achieve this, data of most known all-electric cargo ships (available in the internet as of 2021) was gathered and missing information was estimated with due diligence, to put together a sample selection. Sample vessels’ parameters including principal dimensions, speed and battery capacity were used to calculate their relative cargo transport efficiency. Different routes and speeds were used, as electric ships efficiency was compared to that of fuel-powered vessels. Electric ships were shown to be about 50% more profitable on short routes and equally as profitable on medium routes (if they were slow steaming), reasons being reduced crew, lower maintenance requirements and higher propulsion efficiency. However, at long routes and/or high speeds oil-powered ships currently dominate because otherwise a big part of cargo space would be allocated to transporting batteries, whose energy density is much lower than fuel among other reasons. This paper derives Electric ships design guidelines and helps make an informed decision on whether to use an electric propulsion ship on a given route.

For better density and efficiency: Technique of novel high-voltage SiC based power converters

Medium-voltage power converters have been widely used in diverse applications, such as electric grids, electric ship propulsion, and railway traction. Improving the efficiency and power density of such converters is crucial for cost and availability concerns.

Research of current distribution by phases in asynchronous electric motor with a combined winding

THE PURPOSE. Consider the use of propeller electric installations as part of ship electrical complexes with a single electric power system. Highlight the rudder drives as a special type of electric propulsion of ships in northern latitudes. Investigate unified electric power systems with a propeller electric installation for the existence of power exchange oscillations in them. Propose methods and means for eliminating power oscillations in such systems.METHODS. To carry out the research, a single electric power system with electric rudder propellers of the world's only asymmetric icebreaker Baltika was considered. All the main elements of such system have been analyzed in detail. Experimental studies were carried out aimed at studying the operating modes of a unified electric power system.RESULTS. Experimental oscillograms of currents of parallel operating diesel-generator sets in different modes have been obtained. The existence of exchange and in-phase power oscillations during the operation of the unified electric power system of the icebreaker "Baltika" is noted. The data on the negative influence of power oscillations on the operation of the electrical complex of the icebreaker are presented.CONCLUSION. The use of ice-class sea vessels is an extremely important task for the Russian Federation. The installation of blocks that eliminate exchange and in-phase power oscillations will improve the reliability and efficiency of the use of marine vessels with electric rudder propellers when servicing hydrocarbon production on the Arctic shelf.

Live-Life cycle assessment of the electric propulsion ship using solar PV

This paper was born to introduce a novel methodology termed Live-Life Cycle Assessment using a simulation-based data generation technique that can remedy the inherent shortcomings of conventional practices of lifecycle assessment. To demonstrate its excellence, the proposed method was applied to one of the most challenging topics in the marine industry. That was to tackle the fundamental doubt of whether solar-electric propulsion ships could truly be the future energy solution of maritime transports by fulfilling new environmental conventions and goals around the world. The case study began with an existing hybrid short route ferry running on diesel and plug-in battery power. Credible PV systems for the case ship was modelled to produce ship performance data under various operational/environmental circumstances of the coastal zones across 29 countries in the platform of MATLAB/Simulink. As a key functionality of Live-Life Cycle Assessment, the produced data was directly fed, as inputs, into life cycle assessment to avoid conventional practices that heavily rely on outdated data libraries. Results of the case study clearly revealed and quantified the correlations of the performance of PV-battery systems with climate parameters such as temperature and irradiance of subject areas as well as national power production methods. For example, in terms of Global Warming Potential, the case ship with the PV system was estimated to reduce 40,812 kg CO2 eq. per year in Brazil (average temp.: 27.4 ℃, major energy source: hydro). Interestingly, the same vessel was found to achieve greater reductions in India (average temp.: 27.5 ℃, major energy source: coal) or Australia (average temp.: 20.1 ℃, major energy source: coal) where are overly laden with coal-based power plants. Therefore, their reduction levels were estimated at 152,887 kg CO2 eq. per year and 141,517 kg CO2 eq. per year respectively. This paper clearly shows the excellence of the proposed method to demystify/quantify the impacts of parametric variables on the performance of the PV-electric ship. Moreover, it highly suggests the Live-Life Cycle Assessment could be a solution as a new standard to respond to strong demand to obtain general observation of lifecycle benefits/harms of new technologies across all industries, not necessarily limited to the maritime sector.

A study on the development of job training curriculum for operation of electric propulsion ships

ABSTRACT In order to reduce the emission of pollutants from ships, the need to introduce eco-friendly ships is gradually increasing. Recently built ships are being applied with eco-friendly ship propulsion systems that can replace the existing propulsion systems. The number of ships to which an electric propulsion system, which is a kind of eco-friendly ship propulsion system, is applied is increasing. In addition, an electric propulsion system is attracting attention as a propulsion system suitable for autonomously operated ships to which the digital twin system is applied. Electric propulsion ships have many differences from ships to which the existing propulsion system is applied in terms of equipment and systems mounted thereon. Overseas, job training is being conducted for seamen who onboard electric powered ships for the safe operation of ships, but there is no systematic training course for electric powered ships in Korea. In this paper, we analyze in detail the current educational cases related to electric powered ships in various countries, and propose a curriculum and contents for the mandatory dutied of electric powered ships that can be applied in Korea based on the standard education curriculum of the International Maritime Organization.

Study on verification of AFE rectifier control for electric propulsion ship

Study on verification of AFE rectifier control for electric propulsion ship

A Study on Efficient Electric Propulsion System

In this study, induction motors, which are often used in mid- to large-size ships owing to their durability and price competitiveness, are considered for small electric propulsion ships with space constraints and large-torque requirements. The proposed power conversion system is efficient for propulsion motors in constrained spaces, exhibits a low switching loss, and does not require a speed sensor. It uses an active front-end converter and an induced motor sensorless speed control method with current error compensation. A hysteresis controller was used for reducing the switching loss, and senseless speed control of the induction motor was performed using the current error compensation method. Computer simulation was performed using a PSIM program, and it was verified that the presented electric propulsion system has the same operating characteristics as the system to which a sensor is attached.