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Dive into the research topics where Christopher Ian Hill is active.

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Featured researches published by Christopher Ian Hill.


conference of the industrial electronics society | 2010

Accelerated simulation of complex aircraft electrical power system under normal and faulty operational scenarios

Serhiy Bozhko; T. Wu; Christopher Ian Hill; G.M. Asher

The more-electric aircraft concept (MEA) is one of the major trends in modern aircraft electric power system (EPS) engineering. The concept results in a significantly increased number of onboard loads driven by power-electronics. Development of appropriate EPS architectures, ensuring the power system integrity and assessment of overall system quality and performance under possible normal and abnormal scenarios requires extensive simulation activity. At the same time, the increased use of tightly-controlled motor drives and power electronic converters can make the simulation of the large-scale EPS impractical due to enormous computation time or numerical non-convergence due to the model complexity. Hence, there is a strong demand for accurate but time-efficient modeling techniques for MEA EPS simulations. This paper reports the development of a functional models library capable of maintaining good accuracy up to a specified frequency range. The library is applied to study the performance of a twin-generator example EPS under both normal and faulty regimes. The attained improvement in simulation time confirms the performance of the developed functional models for the study of complex MEA EPS architectures.


IEEE Transactions on Power Electronics | 2017

Comparative stability analysis of droop control approaches in voltage-source-converter-based DC microgrids

Fei Gao; Serhiy Bozhko; Alessando Costabeber; C. Patel; Patrick Wheeler; Christopher Ian Hill; Greg Asher

Droop control has been widely applied in dc microgrids (MGs) due to its inherent modularity and ease of implementation. Among the different droop control methods that can be adopted in dc MGs, two options have been considered in this paper: I-V and V-I droop. I-V droop controls the dc current depending on the dc voltage while V-I droop regulates the dc voltage based on the output current. The paper proposes a comparative study of V-I/I-V droop control approaches in dc MGs focusing on steady-state power-sharing performance and stability. The paper presents the control scheme for current-mode (I-V droop) and voltage-mode ( V-I droop) systems, derives the corresponding output impedance of the source subsystem, including converters dynamics, and analyzes the stability of the power system when supplying constant power loads. The paper first investigates the impact on stability of the key parameters including droop gains, local control loop dynamics, and number of sources and then performs a comparison between current-mode and voltage-mode systems in terms of stability. In addition, a generalized analytical impedance model of a multisource, multiload power system is presented to investigate stability in a more realistic scenario. For this purpose, the paper proposes the concept of “global droop gain” as an important factor to determine the stability behaviour of a parallel sources based dc system. The theoretical analysis has been validated with experimental results from a laboratory-scale dc MG.


ieee transactions on transportation electrification | 2015

Modal Analysis of a PMSG-Based DC Electrical Power System in the More Electric Aircraft Using Eigenvalues Sensitivity

Fei Gao; Xiancheng Zheng; Serhiyi Bozhko; Christopher Ian Hill; Greg Asher

This paper deals with the modeling and small-signal stability analysis of a dc-distribution electrical power system (EPS) sourced by a permanent magnet synchronous generator (PMSG). The topology employed here is one of the main candidates for future more electric aircraft (MEA). A detailed mathematical model is developed and comprehensive EPS modal analysis is performed. Eigenvalue sensitivity and participation factor are utilized to assess the effect of machine and control parameters, as well as system operating conditions, on EPS stability. Furthermore, this paper also presents comparative analysis of system models with and without the inclusion of system cabling. This crucial analysis shows that the tendencies in stability behavior can be significantly different with and without cabling. It is, therefore, shown that system simplification, by removal of cabling, can deliver remarkably misleading results. Time domain simulations are carried out to support the theoretical analysis. The comprehensive analysis presented in this paper provides EPS designers with an extremely useful methodology for the selection of appropriate EPS parameters at the early design stages.


IEEE Transactions on Power Systems | 2016

Dynamic Phasor Modeling of Multi-Generator Variable Frequency Electrical Power Systems

Tao Yang; Serhiy Bozhko; Jean-Mark Le-Peuvedic; Greg Asher; Christopher Ian Hill

The dynamic phasor (DP) concept has been widely used in modeling electrical power systems. So far, the DP concept has been restricted to modeling systems with one single electrical source at a fixed fundamental frequency, either one generator or an ideal three-phase AC source. This paper aims to extend the DP modeling methodology to a wider application area. Two major achievements have been introduced: 1) application of DPs for multi-source, multi-frequency systems; 2) modeling of systems with time-varying frequencies. These two techniques enable the use of DPs to study nearly all types of electrical power systems (EPS). The developed theory is validated using a twin-generator system from the More Open Electrical Technologies (MOET) project. The accuracy and effectiveness of the developed models is confirmed by comparing the simulation results of detailed switching models and DP models under both balanced and unbalanced conditions.


conference of the industrial electronics society | 2014

Aircraft starter-generator system based on permanent-magnet machine fed by active front-end rectifier

Serhiy Bozhko; Seang Shen Yeoh; Fei Gao; Christopher Ian Hill

This paper deals with the control design for an aircraft electric starter-generator system that utilizes recent advances in modern power electronics allowing the use of novel machine types together with the introduction of controlled power electronics into the main path of energy flow. The paper describes the developed system and focuses on control design including flux weakening control of high-speed permanent magnet machine and droop control of the system output dc-link current. The analytical design results and the expected system performance are confirmed by time-domain simulations.


international electric machines and drives conference | 2011

Accelerated electromechanical dynamic modelling of a distributed generation power pack

Christopher Ian Hill; Pericle Zanchetta; Serhiy Bozhko

Distributed diesel generation is widely used to supply electric power in a variety of applications. These applications range from backup power supply systems and combined wind-diesel generation to providing power in places where grid connection is either technically impractical or financially uneconomic. Modelling and optimisation of such systems as a whole is extremely difficult due to the long-time load profiles needed and the computational difficulty of including small time-constant electrical dynamics with large time-constant mechanical dynamics. This paper presents the development of novel, fast, reduced-order models of a distributed diesel generation power pack. These models are shown to achieve a massive improvement in the computational time required for long-time simulations while still maintaining an extremely high level of dynamic accuracy. It is demonstrated how these models are derived, used and verified against benchmark models created using established techniques. Throughout the paper the modelling set as a whole, including multi level detail, is presented, detailed and finally summarised into a crucial tool for general system investigation and multiple target optimisation.


international conference on electrical systems for aircraft railway ship propulsion and road vehicles | 2016

More electric aircraft starter-generator system with utilization of hybrid modulated model predictive control

Seang Shen Yeoh; Tao Yang; Luca Tarisciotti; Christopher Ian Hill; Serhiy Bozhko; Pericle Zanchetta

The current trend for future aircraft is the adoption of the More Electric Aircraft (MEA) concept. The electrical based starter-generator (S/G) system is one of the core ideas from the MEA concept. The PI based control scheme has been investigated in various papers for the permanent magnet based S/G system. Different control schemes are to be considered to improve the control performance of the S/G system. A type of non-linear control called Model Predictive Control (MPC) is considered for its capability to accomplish fast dynamic control performance. The Modulated Model Predictive Control (variant of MPC with an intrinsic modulator) was presented that showed considerably better control performance than the standard MPC. A control scheme is presented in this paper that utilises PI controllers for the outer loop and Modulated Model Predictive Control for the inner loop that covers operation for both starter and generator modes. Simulation analyses are carried out to compare between the proposed control and a full cascaded PI control scheme. The proposed control is also subjected to parameter variation tests for performance evaluation.


international symposium on industrial electronics | 2015

More Electric Aircraft Electro-Mechanical Actuator Regenerated Power Management

Christopher Ian Hill; Serhiy Bozhko; Tao Yang; Paolo Giangrande; Chris Gerada

Under certain conditions Electro-Mechanical Actuators are able to regenerate, rather than consume electrical power. Within the More Electric Aircraft this possibility must be carefully considered in order to ensure safe and stable operation of the electrical systems. This paper assesses various strategies for the management of regenerated power in the More Electric Aircraft. A range of options are considered and the advantages/disadvantages of each are discussed. This includes considerations of safety and stability but also weight, component minimization, cost and potential utilization of the regenerated energy. Key aspects which are investigated in this paper are the effect of increased DC bus voltage on the management of regenerated energy and an assessment of the feasibility of returning energy to the engine inertia. It is shown that increased DC link voltage has distinct advantages when employed in combination with current architectures. However if a fundamental change to system architecture is utilized then this brings very significant benefits.


international conference on electrical systems for aircraft railway ship propulsion and road vehicles | 2015

Automated stability assessment of more electric aircraft electrical power systems

Christopher Ian Hill; Kongpan Areerak; Tao Yang; Serhiy Bozhko; Milijana Odavic

This paper has details the theoretical background, development and application of a newly developed Automated Stability Assessment Tool for More Electric Aircraft Electrical Power Systems. This tool is shown to provide an easy to use and extremely flexible way for system designers to analyze Electrical Power System stability. It is shown how system parameters can be easily varied in order to investigate their impact on Electrical Power System stability. This methodology could therefore save significant time and money, both by accelerating the design process, and by helping design engineers to select the lowest cost components needed to ensure Electrical Power System stability.


ieee transactions on transportation electrification | 2017

Flux-Weakening Control of Electric Starter–Generator Based on Permanent-Magnet Machine

Serhiy Bozhko; Mohamed Rashed; Christopher Ian Hill; Seang Shen Yeoh; Tao Yang

This paper presents the control analysis and design for a permanent-magnet machine (PMM) operated in the flux-weakening (FW) mode for an aircraft electric starter–generator (SG) application. Previous literature has focused on FW control of PMMs in the motoring (starting) mode; however, the system stability and control in the generating mode have been inadequately studied. This paper reports detailed, rigorous control analysis and design for a PMM-based aircraft electric SG operated in the FW mode. It is shown that an unstable area of operation exists. A novel control scheme which eliminates this instability is proposed. The key analytical findings of the paper are verified by experimental investigation. This paper therefore concludes that the presented technique is able to ensure system stability under all modes of operation. Furthermore, it is noted that the findings of this work are also valuable for any two-quadrant PMM drive with frequent change between starting and generating regimes under current-limiting operation.

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Serhiy Bozhko

University of Nottingham

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Tao Yang

University of Nottingham

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Chris Gerada

University of Nottingham

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Fei Gao

University of Nottingham

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Mohamed Rashed

University of Nottingham

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Greg Asher

University of Nottingham

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