162.

F. Senicar, A. Bartsch, B. Krüger and S. Soter, "Enhanced bandwidth current controller for FPGA based inverter drives - a detailed analysis and implementation" in IECON 2012 - 38th Annual Conference of the IEEE Industrial Electronics Society, 2012, pp. 1775--1780.

Abstract:
This paper presents the optimization of the current control loop implemented in a field programmable gate array (FPGA) based inverter. The bandwidth of the current controller is significantly enhanced by reducing the delay times to its theoretical minimum. The optimizations are at first analyzed on a theoretical basis and afterwards verified on the actual target system. It is discussed, that the optimized current controller can be implemented without any drawbacks in terms of available output voltage. It is shown, that the significant reduction of delay times can be implemented in practice, greatly enhancing the bandwidth of the current controller, thus allowing a much higher controller gain.

161.

A. Uphues, K. Nötzold, R. Wegener and S. Soter, "PR-controller in a 2MW grid side windpower converter" in 2012 IEEE International Conference on Industrial Technology, 2012, pp. 1073--1078.

Abstract:
To regulate the current in grid connected power converters mostly proportional integral (PI) controller in synchronous reference frame are used. To improve their known drawbacks such as complexity of control structure because of the dq-transformation and the poor behavior concerning low order harmonics compensation, proportional resonant (PR) controller gained a large popularity. This paper describes the differences between using PI-controller and PR-controller in a 2MW grid connected power converter for wind turbines. The control theory of PR filters and implementing them as delta based infinite impulse response (IIR) filters in a fixed-point microcontroller is presented. The PR-controller with harmonic compensation has been tested in a 2MW power converter.

160.

J. Holtz, "Power Electronics-A Continuing Challenge", IEEE Industrial Electronics Magazine, vol. 5, no. 2, pp. 6--15, 2011.

Abstract:
The age of power semiconductors began when thyristors made their first appearance. They gradually replaced the saturable inductors that were used so far for switched power conversion. The problems related to the nonlinearities of magnetic amplifiers were then easily overcome by naturally commutated thyristor converters. Even so, constructing a line-controlled thyristor converter was still a laborious task. Implementing a current control ler, for instance, required us to design and assemble an analog signal amplifier using many discrete transistors, those novel electronic components. Offset and drift of an amplifier varied with temperature, requiring repeated manual adjustments. Little did we know about parasitic capacitances or stray inductances. Hence, what was meant to be a dc amplifier tended to operate as a high-frequency oscillator.

159.

C. Junge, T. Ruhland, S. Gruber, R. Wegener and S. Soter, "Controlled input-output-shaft synchronisation by a linear drive actuated hydraulic clutch-brake-combination" in 2011 IEEE AFRICON, 2011, pp. 1--5.

Abstract:
The focus of this paper is the control to accelerate and decelerate a drive shaft exactly with a hydraulic clutch-brake-combination (CBC). The CBC is actuated by a permanent magnet linear synchronous machine (PMLSM) with an integrated hydraulic cylinder. The servo-converter-controlled-PMLSM is able to generate the pressure for the CBC. A superposed control cascade with a pressure control and a special synchronization control is implemented to vary the transmitted torque and therefore the accurate acceleration and deceleration of the drive shaft within a preset angle. This development ensures a controlled synchronization of the input-output shaft by a CBC in a specific point of time within a preset mechanical angle.

158.

T. Rösmann and S. Soter, "Mechanically commutated self control of PM- synchronous machines" in 2011 IEEE Energy Conversion Congress and Exposition, 2011, pp. 1555--1559.

Abstract:
In this paper a new method and device is presented that enables a PM-motor to be directly powered with an electrical DC backup source. The presented method uses discrete voltage vectors for motor control as they are well known from Direct Torque Control and Direct Self Control (DSC). The most distinctive difference of the presented method is that it works via a mechanical commutator device without any micro- or power electronics. In opposition to DTC and DSC where flux and torque are controlling the selection of voltage states, the presented method uses the mechanical rotor position to control the discrete voltage vectors. Based on that, the presented method is called MCSC, which means mechanically commutated self control. A simple and robust construction of the commutation device guarantees a low failure probability and the possible integration into the motor housing. Only in emergency case the commutator is activated for a short period of time in order to move the motor into a safe position, stopped with limit switches. Therefore the device can be designed for motors lifetime although carbon brushes are used and a regular maintenance is not necessary as it is known from brushed DC machines.

157.

S. Gruber, C. Junge, R. Wegener and S. Soter, "Overview of a special Developed Linear Drive Concept with integrated Hydraulic Cylinder für Clutch-Brake-Combinations in Eccentric Presses" in Proceedings / LDIA 2011, the Eighth Symposium on Linear Drives for Industry Applications, July 3 - 6, 2011, Eindhoven, The Netherlands, Eindhoven: {TU Eindhoven}, 2011.

156.

R. Kennel, T. Boller and J. Holtz, "Replacement of electrical (load) drives by a hardware-in-the-loop system" in International Aegean Conference on Electrical Machines and Power Electronics and Electromotion, Joint Conference, 2011, pp. 17--25.

Abstract:
This paper presents an interesting approach for hardware-in-the-loop testing of voltage source inverters for drive applications. For this purpose the inverter under test is not connected to a real machine, but to a second inverter instead, which behaves like an electrical machine. The power capability of the so-called "Virtual Machine" is increased by sequential switching of parallel connected standard inverters. The parallel connected inverters can be of the same type as the inverter under test. Hence there exists no power limit for drive inverter testing with respect to the product range of the manufacturer.

155.

C. Prasse, A. Kamagaew, S. Gruber, K. Kalischewski, S. Soter and M. Hompel, "Survey on energy efficiency measurements in heterogenous facility logistics systems" in 2011 IEEE International Conference on Industrial Engineering and Engineering Management, 2011, pp. 1140--1144.

Abstract:
Basically there are two ways to improve the energy efficiency of heterogeneous material flow systems - modification of technical components and control with intelligent strategies. In order to reduce the consumed energy the design, configuration and control strategy of different conveyor systems have to be analyzed by mechanical and electrical measurements. To quantify the need of energy under conditions as close as possible to reality a testing facility with different conveyor elements and electrical drives with power monitoring capabilities was installed in order to give a database for further research activities. On the one hand the acquired data can be used to optimize the efficiency of the total drive train. On the other hand they conduce to develop new intelligent control strategies for an energy efficient operation of heterogeneous facility logistics system. Eventually, the design of a monitoring system in a testing facility is the topic of this contribution.

154.

R. Wegener, K. Nötzold, A. Uphues, R. Griessel and S. Soter, "Test bench for multi-MW grid side wind power converter" in 2011 IEEE AFRICON, 2011, pp. 1--5.

Abstract:
This paper deals with an integrated full power test bench for the grid side of a wind power converter. The speciality is the high side voltage and current measurement to use the stray inductance as an additional filter element. The presented test bench is enhanced for fault ride through measurement capabilities with a full power grid simulator.

153.

H. Abu-Rub, J. Holtz, J. Rodriguez and G. Baoming, "Medium-Voltage Multilevel Converters---State of the Art, Challenges, and Requirements in Industrial Applications", IEEE Transactions on Industrial Electronics, vol. 57, no. 8, pp. 2581--2596, 2010.

Abstract:
This paper gives an overview of medium-voltage (MV) multilevel converters with a focus on achieving minimum harmonic distortion and high efficiency at low switching frequency operation. Increasing the power rating by minimizing switching frequency while still maintaining reasonable power quality is an important requirement and a persistent challenge for the industry. Existing solutions are discussed and analyzed based on their topologies, limitations, and control techniques. As a preferred option for future research and application, an inverter configuration based on three-level building blocks to generate five-level voltage waveforms is suggested. This paper shows that such an inverter may be operated at a very low switching frequency to achieve minimum on-state and dynamic device losses for highly efficient MV drive applications while maintaining low harmonic distortion.