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Thanks to the heavy reduction of cost and volume, integrated On-Board Chargers (OBCs) represent an effective solution to provide a versatile and powerful charging system on board of electric and plug-in electric vehicles, combining the charging function with the traction drivetrain. Such integration foresees the use of the traction motor windings as reactive elements and the traction inverter as AC/DC converter. However, this integration brings several challenges on the table. At first, shaft torque production must be avoided to reduce the losses and mechanical stress. A second challenge is to improve the filtering capability of the motor windings in order to meet the grid standards in terms of current distortion and power factor correction. At last, the most critical issue is to meet the safety standards in terms of leakage current, since it represents a risk to human operators and could also hamper the smooth operation of the charger. Therefore, this paper aims at giving a comprehensive review of the challenges in designing integrated chargers. After reviewing the architectures available in literature, an exemplifying structure of integrated OBC will be analysed in terms of leakage current generation and compliance with the relevant standards, along with an introduction to those solutions which use the machine as isolation transformer. Conclusions are given on the prospect for making integrated on-board chargers safer and more reliable.

High penetration of distributed generation (DG) has led to frequent voltage fluctuations in the distribution network. This paper describes the design of a partially rated, power-electronic-assisted onload tap-changing (OLTC) autotransformer. Positive and negative compensation of the grid voltage can be achieved on feeders that have high distributed generation and/or loading. A novel design of taps comprised of several no-load switches and a single semiconductor-mechanical hybrid switch have been proposed, that requires reduced voltage rating and a number of switches. In steady state, the mechanical switch in the hybrid switch conducts the load current resulting in low steady-state losses. During the tap change process, the OLTC uses semiconductor switches, namely insulated-gate bipolar transistor /metal-oxide semiconductor field-effect transistor, thus achieving arc-free tap change and long lifetime of switches. The OLTC system has been customized for both low-voltage and medium-voltage three-phase distribution networks. An open-delta configuration for the medium-voltage application has been proposed that requires only two OLTC units to control all three line voltages. Simulations are carried out to verify the steady-state and transient operation of the proposed OLTC.

Subsea processing has been increasingly accepted by the offshore oil and gas industry as a solution to boost production and reduce cost. Accordingly, the subsea power demand is growing to support various processing loads, including pumps and compressors. Depending on the application, the power rating of a field ranges from tens of kilowatts to tens of megawatts, and the step-out distance ranges from a few kilometers to hundreds of kilometers. Considering the hostile and remote environment, a reliable subsea electrical-power system that is suitable for subsea deployment is clearly desired. This paper presents a modular direct-current electrical-power system that is designed for use in a subsea field with medium or long step-out distance. The proposed system consists of multiple modular converters in the subsea station to achieve the required power-conversion functions. It features high reliability, high flexibility, and reduced installation weight. The system operation and protection are presented, and the performance is verified by a laboratory-scale demonstration.

Subsea processing has been increasingly accepted by the offshore oil and gas industry as a solution to boost the production and reduce cost. Accordingly, the subsea power demand is growing in order to support the various processing loads including pumps and compressors. Depending on the application, the power rating of a field ranges from tens of kW to tens of MW. A reliable subsea electrical power system which is suitable for subsea deployment is desired. The hostile and remote subsea environment has imposed significant technical challenges on the electrical system. Due to the extremely limited accessibility, the electrical system needs to be very reliable and require minimum regular maintenance in its lifetime. The system should be able to detect and isolate local faults without shutting down the whole system in order to maximize the availability and avoid unplanned stops. The electrical system should also be as compact as possible and modularized, so that they can be installed and retrieved without heavy vessels and lifts which have very limited availability. A novel modular stacked DC (MSDC) development has been developed to address the above mentioned challenges. The proposed system consists of a number of power converter building blocks connected in series on both the on-shore station and the seabed stations. The dc-link current is controlled to be constant, and the dc-link voltage will vary according to the loading condition. This architecture renders simplified power distribution, fault-tolerant capability and feasibility for field extension. This paper will focus on fault protection of the MSDC system. A fast bypass circuit is proposed to isolate the faulty equipment in tens of micro-second without affecting the operation of the rest of the system. The concept has been verified by both simulation and experiments. The paper will also cover the cooling concept for the power electronics in the subsea power converter. A phase change approach has been investigated and tested in the lab. Latest testing results will be shown in the paper.

This paper presents a critical study about the identification of the optimum technology for the components to be used in a power-electronic driven electro-mechanical de-icing system for avionic applications involving harsh environment and requiring high-reliability. Preliminary design and functional testing of the electro-mechanical de-icing system is described. In particular, technology related aspects of optimum component selection for satisfying stringent performance and reliability requirements are discussed, in view of the particular features of the application. (6 pages)

This paper presents the preliminary design and functional testing of an electro-mechanical de-icing system for avionic applications. In particular, technology related aspects of optimum component selection for satisfying stringent performance and reliability requirements are discussed, in view of the particular features of the application.

Employing 'More Electric' architectures for the modern aircraft may lead to more beneficial environmental impacts and improved reliability as well as reduced maintenance cost for airline operators. Therefore, the aircraft industry, governmental organizations and research institutes have focused there attention towards ”power-by-wire” or ”More Electric” architectures in which electrical power moves aircraft flight surfaces. In this paper power electronic technology used in the ”power-by-wire” type nose landing gear system is investigated for future more electric aircraft. Furthermore, use of a dual-output power converter concept for an electromechanically actuated nose landing gear system is analyzed. The design, construction and testing of the above mentioned power converter with higher technology readiness level is described in detailed. Finally, the test results from the nose landing gear ground demonstration unit are presented.

This paper describes the design, construction and testing of a dual-output power converter concept where only the large components, such as the DC link capacitor and heat-sink, are shared between two actuators which are used sequentially in the deployment of aircraft landing gear. This mutual component approach combines the advantages of dual-use power converters with the flexibility of one power converter per application. Practical results of the converter operating are presented for a range of test conditions in order to validate the simulation study.

This paper presents a novel hybrid direct power converter (HDPC) which overcomes the two main disadvantages of matrix converters: limited voltage transfer ratio and low immunity to grid disturbance. The proposed converter is formed by integrating a reversible auxiliary boost converter in the dc link of the two-stage matrix converter. Therefore, the HDPC can provide unity voltage transfer ratio even in the case where the supply voltage is highly unbalanced. The proposed converter also preserves most of the inherent advantages of the conventional matrix converter such as: controllable input power factor, sinusoidal supply currents, and bidirectional power flow. A novel predictive current control technique for the HDPC is also proposed for minimum energy storage in the converter. Important aspects of design, control, and implementation of the new HDPC are presented including theoretical analysis and simulations. Experimental waveforms at unity voltage transfer using a laboratory prototype are presented to confirm the viability of the proposed idea.

Matrix converters have no boost capabilities. Their output voltage amplitude is therefore reduced compared to back-to-back inverter topologies. Moreover, they are sensitive to grid voltage fluctuations and disturbances and the voltage transfer ratio is further reduced under such grid perturbations. The present paper analyses the behaviour and limits of the two-stage matrix converters. It proposes and investigates three alternative topologies that modify the DC-link voltage of the two-stage matrix converter, by the means of additional circuitry, in order to increase the voltage transfer ratio above unity and to obtain immunity to grid disturbances. A high-performance control of the grid current is required to obtain a power factor close to unity. An effective control method is proposed for each converter. Feedforward model predictive controllers allow obtaining good performances. The performances of the topologies are finally analysed and compared.

Unbalanced supply voltages can be fully compensated in boost type power converters with active front end if sufficient energy storage is provided by the DC-link capacitor. In converters that have no energy storage, for example in a matrix converter, the maximum voltage transfer ratio will be reduced if one or more input lines is at a reduced voltage. Control techniques to compensate the effect of unbalanced voltage supply for matrix converters allow for a limited output voltage and power capabilities, which depends on the level of unbalance. This paper proposes the utilization of the clamp capacitor, which is normally needed only to protect a direct power converter (DPC), to extend the operating range of a two-stage DPC during unbalanced supply conditions preserving its theoretic maximum voltage transfer ratio capability. This solution is validated through simulations

The Hybrid ac/ac Direct Power Converter (HDPC) has the advantage of improved voltage transfer ratio and higher robustness against supply voltage unbalances over the Conventional Matrix Converters (CMC). The HDPC also has the inherent advantages of the CMC such as: adjustable input power factor, sinusoidal supply currents and no bulky energy storage elements which reduce the life time of the converter. This paper proposed a predictive current controller scheme for a HDPC based on 2-stage matrix converter providing unity voltage transfer ratios; even in the case the supply voltage is highly unbalanced. The proposed predictive current controller is simple in digital implementation, provides higher bandwidth control, requires no additional circuitry and maintains a constant switching frequency which allows synchronizing the switching of the HDPC for sinusoidal supply currents.

Variable voltage and variable frequency conversion of electrical energy from an AC source to an AC load is done in traditional power converters via a DC-link where an energy storage element (electrolytic capacitors) is situated. Despite its well-known benefits, it has the disadvantage of being bulky and to limit the converter lifetime. On the other hand, Direct Power Conversion (DPC) is an attractive concept, which doesn’t need an energy storage buffer, but has two main disadvantages: reduced voltage transfer ratio (

Direct power converters (DPC), which has no energy storage, the converter output voltage capability is affected when the input voltage is unbalanced. This paper proposes the utilization of the clamp capacitor, which is normally needed to protect a DPC, to extend the operating range of a two stage DPC during unbalanced supply, preserving its theoretical output voltage capability. A comprehensive simulation study with analytical explanations justifies the proposed method. Experimental results using a laboratory prototype confirms the viability of the proposed active compensation technique