Helmut Weiss

Fuzzy system control for combined wind and solar power distributed generation unit

For renewable energy generation in the distributed and co-generation (DCG) scheme, photovoltaics and wind power are already in service at many installations. Basically, these types of energy generation are very favourable for the environment but do not produce power on customers load demands, have long intervals of lacking power generation due to absence of power input (no sunshine, no wind), and especially exhibit high costs per installed power respectively per generated energy. So every cost saving and output increasing measure should be taken. Combining a photovoltaic power unit with a wind energy unit will reduce the zero-power intervals and can be composed to high extent of standard commercial variable speed drive elements. These are PWM voltage source inverters with active front end, and also standard induction machines can be taken. Only a few extensions are necessary, thus the total hardware system is rather cost effective. It is essential that a system control unit defines setpoint values for the sub-units and handles abnormal operating conditions. Here a fuzzy control system is proposed to accomplish these tasks. It means performing the standard power insertion into the line on the principle of maximum power tracking, preferable at a rather constant power input without flicker power, ensuring or improving line voltage quality with regard to reactive power and distortion power, or voltage waveform improvement, respectively. In addition, in case of a line interruption, the unit should be able to run independently from the line, establishing an insular power supply for the nearby customers and loads until the reconnection to the mains is done.

Three-Level Rectifier Fed Four-Level Inverter for Electric Drives

A special four-level three-phase diode clamped inverter fed by a correspondingly adapted untypical three-phase rectifier with two typical transformers is presented. The three-level rectifier is formed by consecutive connection of three rectifiers under the circuit of Scott for the bi-phase orthogonal voltage received from corresponding windings of two three-phase transformers. The inverter is realized by 4,5kV IGBT modules and provides a voltage of 6 kV (RMS) for a high power induction machine without transformer. The dependences of THD and integral values of THD of output voltage are simulated and shown for simple variants of three-carriers PWM and SVM.

Locomotive optimal adhesion control by wavelet analysis

A wavelet transform method processing wheel acceleration signal containing random noise is proposed in this paper. By multiresolution analysis, the original wheel acceleration signal is decomposed into approximation parts and detail parts at several levels. After this decomposition, the noise containing in the wheel acceleration signal is stored in the detail parts. From the noise-free approximation parts, the wheel acceleration tendency can be estimated and differentiated to identify the wheel slip tendency. A fuzzy adhesion controller is then proposed to locomotive anti-slip control. The simulation results show the application of wavelet transform to the slip tendency identification paves a new way to effectively avoid false slip identification, and enhance the fully utilization of adhesive force.

Decentralized supply system with renewable energy based on quasi-eight-level inverter

Renewable energy resources available locally are ideally suited for providing electricity supply in remote areas. This report describes design and layout of a special single phase supply system with high voltage quality and low power electronics expenditure through application of a special quasi-eight-level inverter output voltage shape at four-level-inverter circuit configuration. Simulation results are presented, a laboratory model is in finalizing state (to be described in full paper). In addition, an advanced strategy is presented for handling heavy load conditions and high power output motors.

Simulation study on adhesion control of electric locomotives based on multidisciplinary virtual prototyping

An electric locomotive is a complex electromechanical system composed of electro-magnetic, power electronics, mechanics and various control subsystems. The interactions between the different subsystems have to be considered when the adhesion control system is studied. The multi-body model of an electric locomotive was established with ADAMS (automatic dynamic analysis of mechanical systems). A hybrid adhesion control algorithm was designed using MATLAB. The multidisciplinary virtual prototyping of the locomotives was established with co-simulation of different simulation tools. The simulation results show that the hybrid adhesion controller can suppress wheel-to-rail slipping efficiently and some design problems may be solved with the multidisciplinary virtual prototyping. This approach provides a new and effective way to study more sophisticated adhesion control system further.

Four-Level Rectifier and Four-Level Inverter for Electric Drives

A four-level three-phase diode clamped inverter fed by a correspondingly adapted untypical three-phase rectifier with two typical transformers is presented. The four-level rectifier is formed by consecutive connection of three rectifiers under the circuit of Scott for the bi-phase orthogonal voltage received from corresponding windings of two three-phase transformers. The inverter is realized by 4,5 kV IGBT modules and provides a voltage of 6 kV (RMS) for a high power induction machine without transformer. The dependences of THD and THD of integral values of the output voltage are simulated and shown for simple variants of three-carriers PWM and SVM.

True zero-emission vehicle energy generation and measurement in students' educational project

Up-to-date education shall prepare students for work in industry in an optimal and efficient way. Through the project described students are taught basics of renewable energy problems, details of electric vehicles and their power supply and power train, several types of high-efficiency power conversion methods, system design and circuit layout, all with practical realization and actual test. Going through all phases between first design and final composition and evaluation students get a real knowledge of processes of actual work. The project balances introduction into theory, basic circuits and adapted and improved versions, work of students in a self-responsible way, their learning from errors, and finally yielding a nice result creating high motivation for further work on the topics covered: Students may really drive the electric vehicle on the road they work on during the project.

Low cost cogging torque elimination at PMSM by power electronics control

Highest efficiency can be obtained by a Permanent Magnet Synchronous Machine (PMSM) drive. Simple and cost effective PMSM designs with automatically wound stator coils and therefore without stater skewing exhibit high cogging torque values coming from slot-tooth and magnet geometry. Skewing is the standard measure to avoid unfavorable cogging torques and it is usually done at rotor side with induction machines but cannot be realized at PMSM in the same way. This paper identifies cogging torque for a specific PMSM with automatically-wound stator without skewing and presents efficient solutions for a complete elimination of inherent cogging torque by advanced power electronics control and suitable power electronics hardware.

Portable Three Phase Energy Consumption Acquisition System

Energy management becomes more and more important with respect to rapid increasing energy costs. Exact analysis of all installed electrical loads of a company is the basic requirement for starting and realising energy-saving measures. The proposed cost-effective mobile portable measuring system is composed of a standard notebook with PCMCIA slot, a data acquisition PCMCIA card and signal interfaces for current and voltage. We can measure (active) power of all power lines in an electrical distribution network regardless of voltage and current waveforms. Standard harmonics contents in current and voltage do not influence accuracy. All measured data will be saved on disk during the time of monitoring. These data can be analysed and interpreted easily using analysis software like DIAdem or simply EXCEL

Electric vehicle battery limiter und monitoring system implementation in educational process

Before students can be taught the sciences of engineering they first have to enroll to these studies. At an age of 18 the decision is done which influences the whole process. We consider a project under strict and intensive tutorship with interesting tasks offered to young people in decisive age leading to a higher number of engineering students who are necessary to solve the problems of our future. This project example describes steps for development of an battery monitor and balancer to be used in electric vehicles.