Matrix converters for sensorless control of PMSMs and other auxiliaries on deep-sea ROVs

The use of matrix converter technologies for the control of actuators and other auxiliaries onboard work-class, deep-sea, remotely operated vehicles (ROVs) is reported. Key requirements for such systems are the ability to sustain operation at high ambient pressures, up to 300 bar, commensurate with operation of ROVs at depths of 3000 m, and to minimise the number of external connections and cabling mass to improve reliability and reduce drag. Emphasis is given to 32 matrix converters for 3f–1f AC voltage/frequency for conversion control of system auxiliaries, with experimental results showing circuit functionality during pressure cycling consistent with typical operational duties, and the use of 33 matrix converters for control of actuators driven by brushless permanent magnet synchronous machines (PMSMs). A principal feature of the paper is the development of model-based sensorless control methodologies for driving PMSMs using matrix converters. In particular, it is shown that observer-based state estimation techniques normally employed for sensorless control of PMSMs using voltage source inverters, can be readily exported to matrix converter counterparts with minimal additional computational overhead. Experimental results from a 0.7 kW PMSM driven by a matrix converter, suitable for a subsea actuator pump, are included to demonstrate the ability of the sensorless techniques to provide reliable estimates of machine rotor position under transient load conditions, and the subsequent exploitation for matrix converter/motor combinations is discussed

Population inversion of a NAHS mixture adsorbed into a cylindrical pore

A cylindrical nanopore immersed in a non-additive hard sphere binary fluid is studied by means of integral equation theories and Monte Carlo simulations. It is found that at low and intermediate values of the bulk total number density the more concentrated bulk species is preferentially absorbed by the pore, as expected. However, further increments of the bulk number density lead to an abrupt population inversion in the confined fluid and an entropy driven prewetting transition at the outside wall of the pore. These phenomena are a function of the pore size, the non-additivity parameter, the bulk number density, and particles relative number fraction. We discuss our results in relation to the phase separation in the bulk.Comment: 7 pages, 8 Figure

Microgrid power electronic converters: state of the art and future challenges

This paper presents a review of the state of the art of power electric converters used in microgrids. The paper focuses primarily on grid connected converters. Different topologies and control and modulation strategies for these specific converters are critically reviewed. Moreover, future challenges in respect of these converters are identified along with their potential solutions

Robust repetitive feedback control of a three-phase grid connected inverter

This paper discusses the design of a repetitive feedback controller for a grid-connected two-level three-phase voltagesource inverter connected between a DC source and the grid through an LCL filter. The controller incorporates a classical two loop feedback of the output current and the capacitor current in addition to a repetitive feedback loop. The results show that the proposed technique improves the steady state error and the total harmonic distortion of output current in presence of utility harmonics

Integration of distributed generation into the grid: protection challenges and solutions

An effective introduction of distributed generation (DG) into existing distribution networks (DNs) calls for a review of traditional power system protection concepts and strategies. New issues such as activeness of DNs and bidirectional power flow require new protection solutions. This paper discusses protection issues and challenges arising from the integration of DG into the grid. It presents and critically reviews traditional and state of the art protection strategies. Moreover, some alternate protection strategies are proposed and their merits and demerits are discussed