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A design of a 3-phase inductive power and data transfer for multiple stationary loads is proposed. It focuses on stable load voltages while minimizing electromagnetic interference. Loads are contactless charging units of electric vehicles at car parks. Physical properties of the inductive couplers are modelled via 3-D FEM and lumped parameters are used for system studies. Design principles are verified at laboratory scale with a purpose built test stand.
In Sub-Saharan Africa less than 10% of the rural population has access to electricity [1]. Stand-alone power systems (SPS) can be a solution to the problem of the lack of electricity, which highlights challenges such as modules installation costs as well as the sufficient knowledge required for installing, maintaining and operating such systems. With this fact in mind, a 250 W Low Head turbine system was developed and optimized to have the advantage of the simplicity of installation and a construction from readily available materials. This design scores the electrical efficiency of 60%, reduces manufacturing unit coast to 130 € and takes into account the necessity of providing a clear and simple manual describing the manufacturing and installation. A better version of the load controller, using a microcomputer is under current development. Mounting of the system have been simplified to reduce the amount of construction material required to provide uninterrupted 230 V at 50 Hz AC or optional 12 V DC power supply. Current efforts aim on transferring the required mechanical and electrical knowledge for building, programming, installing and maintaining such system to schools in targeted countries. This project doesn’t only provide people in rural developing countries a gleam of hope to catch up with the developed countries, but also helps students to use their theoretical knowledge to realize practical applications.
Investigation of Shifted PWM Methods for a Dual Three-Phase System to Reduce Capacitor RMS Current
(2020)
Mild hybrid automotive topologies containing a 48V high power (>15 kW) electric drive system demand a high integration of power electronics and electrical machine. A multi-phase motor winding topology helps to keep the per-phase operating currents to a reasonable level. Close integration and multi-phase system have led to a drive system with dual 3-phase systems supplied by a common 48V DC-link, which allows to shift PWM patterns for reduction of DC-link capacitor ripple current and size. This paper derives some basic rules for combinations of common PWM methods for dual 3-phase systems without magnetic cross-coupling. Experimental measurements verify simulated results.
Least squares pose estimation of cylinder axes from multiple views using contour line features
(2015)
In this paper, a new method for a minimum-error pose estimation of cylinder axes based on apparent contour line features from multiple views is presented. Novel model equations for both single and particularly multiple views are derived, and based upon these, an iterative algorithm for least squares fitting the model to imaged cylinder contour line features is introduced. The good performance and fast convergence of the proposed algorithm is shown by solving exemplary fitting problems.
This article deals with the question to what extent the automotive standard for functional safety ISO 26262 is also applicable to motorbikes. It examines thereby, on the one hand where to find comparable criteria between cars and motorbikes from the standpoint of functional safety, and, on the other hand, where differences between the automobile and the motorbike must be considered. It shows the extent to which the safety-related automotive standard is applicable to motorbikes. Furthermore, the differences are determined, which must lead to the consequence of a new “state of the art” and to a new standard for motorbikes. On the example of a light function the new MSIL classification gets applied. In this article, the motorbike is viewed as a whole. For the most parts the standard is also valid for scooters.
Self-phase modulation in lithium niobate wave-guides with cascaded quadratic and cubic nonlinearities is characterized by comparison of amplitude and phase of input and output pulse envelopes and spectra. Cubic nonlinear susceptibility coefficients of lithium niobate were determined from the measured nonlinear phase shifts.
Detection and compensation of current sensor gain-faults regardless of the operating-point is a crucial aspect for safety-relevant servo-drives. This paper presents and investigates a new direct phase-gain re-balancing methodology, especially suited for interior permanent magnet machine (IPM) drives mostly operating at low speed-ranges including standstill. The proposed model-based approach utilizes high-frequency signal-injection (HFI) to facilitate fast and persistent sensor monitoring for any operating state of the drive. No additional sensing hardware is required. Extraction of the HFI-phase-current response enables detection and immediate compensation of sensor gain-faults. Implementation aspects of the proposed concept are discussed thoroughly. Experimental results are presented to prove and investigate robustness, reliability and fault-tolerant performance.
The flow of superfluid around a translationally oscillating sphere, levitating without mechanical support, can either be laminar or turbulent, depending on the velocity amplitude. Below a critical velocity that scales as and is temperature independent below 1 K, the flow is laminar (potential flow). Below 0.5 K, the linear drag force is caused by ballistic phonon scattering that vanishes as until background damping, measured in the empty cell, becomes dominant for K. Increasing the velocity amplitude above leads to a transition from potential flow to turbulence, where the large turbulent drag force varies as . In a small velocity interval % above , the flow is unstable below 0.5 K, switching intermittently between both patterns. From time series recorded at constant temperature and driving force, the lifetimes of both phases are analyzed statistically. We observe metastable states of potential flow which, after a mean lifetime of 25 min, ultimately break down due to vorticity created by natural background radioactivity. The lifetimes of the turbulent phases have an exponential distribution, and the mean increases exponentially with . We investigate the frequency at which the vortex rings are shed from the sphere. Our results are compared with recent data of other authors on vortex shedding by moving a laser beam through a Bose-Einstein condensate. Finally, we show that our observed transition to turbulence belongs to the class of "supertransient chaos" where lifetimes of the turbulent states increase faster than exponentially.
Wind turbines play a crucial role in the revolution towards renewable resources. They need to be economically competitive to be sustainable. This still requires to lower the cost of energy (COE). To this end, nonlinear model predictive control (NMPC) is used within this paper. As known from literature, NMPC significantly improves the energy extracting performance as well as the mitigation of tower loads of wind turbines. As it is shown in this paper, the drivetrain fatigue strength drops disproportionally in parallel, which either increases the demands on the turbine design or decreases the lifetime of drivetrain components. Without additional boundary conditions to the underlying optimal control problems (OCPs), the application of energy-maximizing NMPC might so even raise the COE. Only penalizing axial torque oscillations by quadratic terms decreases energy-extracting performance below the level of classical wind turbine controllers. This makes more sophisticated conditions necessary. In this paper, the increase of the drivetrain damage by NMPC is analyzed, and appropriate boundary conditions are derived, to balance the two contradicting objectives of energy maximization and drivetrain load mitigation. An NMPC approach based on indirect methods is used, to obtain a solution of the OCPs very efficiently. It applies the Hamilton equations and Pontryagin's maximum principle. Its accuracy and efficiency to solve OCPs was presented over the last decades.