A modelling and simulation of a sensorless control of five-phase PMSM drives using multi-dimension space vector modulation

This paper introduces a new method to track the saturation saliency for position measurement of a five-phase PMSM motor fed by a five-phase inverter through measuring the dynamic current response of the motor line currents due to the IGBT switching actions. The new method uses only the fundamental PWM waveform obtained using the multi-phase space vector pulse width modulation (i.e there is no modification to the operation of the five-phase inverter) similar to the fundamental PWM method proposed for a three-leg inverter. Simulation results are provided to verify the effectiveness of the proposed strategy for saliency tracking of a five-phase PMSM motor driven by five-phase inverter over a wide speed ranges under different load conditions

Community power flow control for peak demand reduction and energy cost savings

The increase in penetration of renewable energy sources, such as solar or wind, and high peak load demand can cause grid network security issues. The incorporation of demand side management and energy storage devices can provide a solution to these problems. This paper presents a community power flow control (PFC) strategy which reduces peak grid demand, and increases self-consumption of renewable energy which produces energy cost savings in smart communities with grid-connected photovoltaic (PV) systems. The PFC aims to directly control high power consumption appliances and the charge/discharge of a community battery storage using measurement of the instantaneous power demands of the community. Historical data records of the community daily energy consumption and the available renewable energy are taken into account to manage the loads and battery storage. Simulation results show for a community of one hundred houses, with 114 kWp of PV arrays, and a 350kWh battery system that the percentage of the average peak power demand reduction over the year is 32%,whilethePV energy self-consumption increases by73%. This can produce an annual energy cost saving of up to £1100 when compared to the same community with only PV

A wide input-voltage range quasi-Z source boost DC-DC converter with high voltage-gain for fuel cell vehicles

A quasi-Z-source Boost DC-DC converter which uses a switched-capacitor is proposed for fuel cell vehicles. The topology can obtain a high voltage gain with a wide input-voltage range, and requires only a low voltage stress across each of the components. The performance of the proposed converter is compared with other converters which use Z-source networks. A scaled-down 400V/400W prototype is developed to validate the proposed technology. The respective variation in the output voltage is avoided when the wide variation in the input voltage happens, due to the PI controller in the voltage loop, and a maximum efficiency of 95.13% is measured

Interleaved switched-capacitor bidirectional DC-DC converter with wide voltage-gain range for energy storage systems

In this paper, an interleaved switched-capacitor bidirectional DC-DC converter with a high step-up/step-down voltage gain is proposed. The interleaved structure is adopted in the low-voltage side of this converter to reduce the ripple of the current through the low-voltage side, and the series-connected structure is adopted in the high-voltage side to achieve the high step-up/step-down voltage gain. In addition, the bidirectional synchronous rectification operations are carried out without requiring any extra hardware, and the efficiency of the converter is improved. Furthermore, the operating principles, voltage and current stresses, and current ripple characteristics of the converter are analyzed. Finally, a 1kW prototype has been developed which verifies a wide voltage-gain range of this converter between the variable low-voltage side (50V-120V) and the constant high-voltage side (400V). The maximum efficiency of the converter is 95.21% in the step-up mode and 95.30% in the step-down mode. The experimental results also validate the feasibility and the effectiveness of the proposed topology

A common ground switched-quasi-Z-source bidirectional DC-DC converter with wide-voltage-gain range for EVs with hybrid energy sources

A common ground switched-quasi-Z-source bidirectional DC-DC converter is proposed for electric vehicles (EVs) with hybrid energy sources. The proposed converter is based on the traditional two-level quasi-Z-source bidirectional DC-DC converter, changing the position of the main power switch. It has the advantages of a wide voltage gain range, a lower voltage stress across the power switches, and an absolute common ground. The operating principle, the voltage and current stresses on the power switches, the comparisons with the other converters, the small signal analysis and the controller design are presented in this paper. Finally, a 300W prototype with Uhigh=240V and Ulow=40~120V is developed, and the experimental results validate the performance and the feasibility of the proposed converter

Realising robust low speed sensorless PMSM control using current derivatives obtained from standard current sensors

This paper describes the implementation of a simple, robust and cost-effective sensorless control technique for PMSM machines. The method uses stator current derivative measurements made in response to certain PWM vectors. In this work the derivatives are created from measurements made with standard hall-effect sensors (at the start and end of switching vectors), meaning that specialist transducers, such as Rogowski Coils, are not required. However, under narrow PWM vectors high frequency (HF) oscillations can disrupt the current and current derivative responses. In previous work, the time that PWM vectors were applied to the machine for was extended to a threshold known as the minimum pulse width (tmin) in order to allow the HF oscillations to decay and a derivative measurement to be obtained. This introduces additional distortion to the motor current. It is shown here that an artificial neural network can be used to estimate derivatives using measurements from a standard current sensor before the HF oscillations have fully decayed, thus permitting a reduction of the minimum pulse width (and associated distortion)

Mathematical analysis of the equivalent impedance at the harmonic frequency for the proposed aircraft power system

The proposals for the `More Electric Aircraft' place a significant, increased demand on the electrical power distribution system. To increase safety and reduce aircraft maintenance times on the ground, there is a greater need to quickly identify and locate electrical faults within the electrical distribution system. The work presented in this study provides the mathematical basis for the use of power system harmonic impedance measurement for identifying and locating faults within power cables. The method is passive - that is, it does not require the injection of any test signals - and can potentially be embedded into a centralised equipment controller to provide intelligent, real time diagnostics. The method monitors the harmonic line-line self-impedance at strategic points in the distribution system; this is obtained by measuring load voltage and current. Faults can be identified and located within a few fundamental cycles, and therefore provides a `backup protection' system which does not require measurement of the line current. It also can provide details of the fault location and could therefore be a significant aid to aircraft maintenance. This study derives the theoretical basis of the scheme and provides simulation results for a proposed aircraft power system to demonstrate the validity of this approach to detect and locate faults within the system

Understanding well-being outcomes in primary care arts on referral interventions: a mixed method study

Background: Arts on Prescription programmes are designed to support mental health and well-being of patients with a variety of clinical needs within the community. Despite a number of studies reporting benefits, there are some patients that do not see improvements in well-being. Yet, there is limited research investigating the reasons for this. Methods: Using a sequential mixed-methods design the present study sought to understand why some participants (N=312) experienced an increase in well-being and others did not (N=95) after attending an Arts on Prescription intervention based in the South West of England between 2009 and 2016. Results: Quantitative comparisons between the two groups identified little differences, aside from age and baseline well-being (WEMWBS scores), with those that improved being slightly younger, and having lower well-being at the outset compared with those that did not improve. A process model depicting the perceived facilitative and inhibitive factors of attending the programme was developed from the qualitative findings. This model suggests that the social aspect of the course may be implicated in the participants differential outcomes; with those that showed a decrease in well-being reporting difficulties in interacting with others during the intervention. Further, the participants who reported an increase in well-being felt vulnerable to “relapse” when finishing the course due to uncertainties regarding future support and at their ability to maintain their well-being without the provision of the programme. Conclusions: This research suggests a need to promote communication amongst groups in such interventions with the hope that this will provide a more facilitative environment for all participants to benefit. Also, such programmes should consider follow-on options to ensure the participants feel supported and confident in managing their well-being once the course comes to an end. Findings will be pertinent to those commissioning primary care art interventions, ensuring that referral policies and pathways are designed for optimal effectiveness and for potentially tailoring social prescribing programmes to suit the participants specific needs

Investigating the impact of varying the number of distributed energy resources on controlling the power flow within a microgrid

The electrification of heat and transport in addition to integration of intermittent renewable resources into the existing electricity network is expected to occur in near future. Such a transformation is expected to force the operation of the electricity power system at different levels to its limits and would require reinforcement of the network assets at different levels. The incorporation of active management and control within microgrids and across the low voltage distribution network is thought as a cost effective solution which would facilitate wide scale integration of the emerging distributed energy resources. However since increasing the microgrid size at a certain DER penetration level would increase the total dispatchable power it is expected to affect the effectiveness of any control algorithm that operates at that level. This paper presents the findings obtained from of an investigation into the relationship between microgrid size and the effectiveness of a deterministic control algorithm implemented at that level