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In this paper, a systematic procedure is presented, how to predict the AC resistance of litz-wire windings considering air gap fringing fields. For this purpose, an equivalent complex permeability model is derived for hexagonally packed wires. It is shown, how finite element method (FEM) can be used to determine the real as well as the imaginary part of the complex permeability with the copper filling...
Droop scheme has been widely applied to the control of Distributed Generators (DGs) in microgrids for proportional power sharing based on their ratings. For standalone microgrid, where centralized management system is not viable, the proportional power sharing based droop might not suit well since DGs are usually of different types unlike synchronous generators. This paper presents an autonomous droop...
Medium voltage, medium frequency transformers (MFTs) are much smaller in size and weight compared to conventional low frequency transformers. The MFTs are very attractive for applications where full control of the power flow and high power density are required, such as power electronic interface in smart grids and traction converter system. With reduced size, the optimal design of MFTs becomes more...
This paper presents the adaptation of a previously published CAD tool that was initially conceived for high power isolated dc-dc converters, to the multiobjective optimal design of a switch-mode power supply for space application. The main changes to the existing tool concern the magnetic elements (transformer and inductor), the reduction of voltage and current ratings of the semiconductor devices,...
In this paper, the optimisation possibilities of a quasi-resonant induction cooker are investigated. Simulations show that main losses of the induction cooker occur in the heating coil and the RC-IGBT (power switch). The performance of the coil can be improved mainly by minimising the coil resistance. The IGBT-optimisation is based on the reduction of tail current in soft switching mode. The tail...
The optimal choice of switches within a hysteresis controller with a d-q-related constraint is discussed in this paper. The hysteresis controller controls a bidirectional two-level three-phase standard inverter. This paper expands the options of switching processes to a former published d-q-hysteresis controller. Despite a separate active and reactive hysteresis constraint which is offered, further...
Ant Colony Optimization allows simultaneous tuning of a large number of control parameters and provides flexibility in the choice of the performance criterion. An off-line tuning methodology is proposed for PID-type controllers and their associated anti-windup subsystem for cascaded loop control structures. Insight is given on the design process, on parameter setting and on handling of soft and hard...
Active Voltage Control (AVC) is an implementation of classic Proportional-Derivative (PD) control and multi-loop feedback control to force an IGBT to follow a pre-set switching trajectory. Previously, AVC was mainly used for controlling series-connected IGBTs in order to enable voltage balance between IGBTs. In this paper, the nonlinear IGBT turn-off transient is further discussed and the turnoff...
Electric vehicles (EV) require energy storage with high power and high energy-density. A hybrid-storage-system combining battery (high energy density) and ultra-capacitor (high power density) to supply a motor is logical. This paper will present an efficient way of dimensioning the ultra-capacitor of this system. The optimal size is determined by applying real driving cycles to a dynamics simulation...
The use of active magnetic bearings (AMB) is increasing in high-speed applications, because their low friction operation allows higher rotational speeds than the traditional bearings. The inherent instability and complexity of the AMB rotor system with high nonlinearities pose challenges to the controller design. This leads to a problem of robust design. Robustness of LQG and loop-shaping H∞ controllers...
This paper presents a comparative study between two non-causal algorithms for the energy management problem of electric vehicles, endowed with batteries and supercapacitors(SCs). Toward that goal, an optimization-based energy problem is formulated, which targets the minimization of the source's energy losses throughout a given driving cycle. This problem is solved, firstly, with the help of a fast...
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