94.

J. Pontt, J. Rodriguez, P. Newman, A. Liendo and J. Holtz, "Network friendly low-switching frequency high-power three-level PWM rectifier" in 2005 European Conference on Power Electronics and Applications, 2005, pp. 9 pp--P.9.

Abstract:
High-power converters for regenerative drives and distributed generation need a network-friendly operation with low switching frequency for high reliability and performance. This paper presents a multipulse connection of two three-level NPC PWM rectifiers with the selective harmonics elimination technique (SHE) and a novel optimal method for minimal current distortion.

93.

J. Holtz and H. Pan, "Acquisition of rotor anisotropy signals in sensorless position control systems", IEEE Transactions on Industry Applications, vol. 40, no. 5, pp. 1379--1387, 2004.

Abstract:
Sensorless position control of induction motors relies on the detection of rotor anisotropies. The repetitive transient excitation through the switched voltages of the pulsewidth-modulated inverter provides the test signals to identify the spatial orientation of the anisotropies that indicate the rotor position. The position information is contained in the inverter output voltages. These are measured against the neutral point of the star connected stator winding. The signals are heavily corrupted by disturbances. These originate from the propagation of traveling waves on a long motor cable and from the influence of high-frequency common-mode currents. The paper describes how a clean position signal is extracted in the presence of such noise.

92.

A. Wirsen and S. Soter, "Berührungslose Drehmomenterfassung - Turbosätze altern unter strengeer Beobachtung", SENSOR report, vol. 2004, no. 4, 2004.

91.

J. Holtz, J. Quan, J. Pontt, J. Rodriguez, P. Newman and H. Miranda, "Design of fast and robust current regulators for high-power drives based on complex state variables", IEEE Transactions on Industry Applications, vol. 40, no. 5, pp. 1388--1397, 2004.

Abstract:
High-power pulsewidth-modulated inverters for medium-voltage applications operate at switching frequencies below 1 kHz to keep the dynamic losses of the power devices at a permitted level. Also, the sampling rate of the digital signal processing system is then low, which introduces considerable signal delays. These have adverse effects on the dynamics of the current control system and introduce undesired cross coupling between the current components i/sub d/ and i/sub q/. To overcome this problem, complex state variables are used to derive more accurate models of the machine and the inverter. From these, a novel current controller structure employing single-complex zeros is synthesized. Experimental results demonstrate that high dynamic performance and zero cross coupling is achieved even at very low switching frequency.

90.

J. Holtz and H. Pan, "Elimination of saturation effects in sensorless position-controlled induction motors", IEEE Transactions on Industry Applications, vol. 40, no. 2, pp. 623--631, 2004.

Abstract:
Owing to the variable magnetic coupling between the stator windings and the discrete rotor bars of an induction motor, a quasicontinuous rotor position signal can be acquired by instantaneous measurement of the total leakage inductance of the three stator phases. The signals are sampled in synchronism with the regular commutations of the pulsewidth-modulation process, thus making the injection of additional high-frequency carriers obsolete. The acquired position signal exhibits high spatial resolution and high dynamic bandwidth. Magnetic saturation also influences the total leakage inductances and, hence, constitutes a disturbance for position identification. This paper presents a detailed analysis of the saturation effects and proposes methods to eliminate their undesired impact on the position signal. Experimental results of closed-loop sensorless position control at full load and high dynamic performance are presented.

89.

S. Soter and F. Bertling, "Adjustable converter for injection of fuel cell power as a part of a virtual power plant" in PESC04, Piscataway, N.J: IEEE, 2004, pp. 1988-1990 Vol.3.

Abstract:
This research project deals with the development of a solid, intelligent converter with a good value. The energy of fuel cells or other low-voltage energy-sources (40 to 80 VDC) is feeded decentral into the public net (230 VAC/50 Hz or 110 VAC/60 Hz). Because of the requirements of the serial product (e.g. low price, reliability, range of use) a prototype of a converter with high frequency transformer was built. The latest electronic devices and a digital signal processor as central controller have been applied to achieve high efficiency and flexible power injection. It is possible to obtain improvements of the local voltage quality and stability by adjusting active and reactive power as well as power factor and current shape.

88.

R. Lach, S. Soter and R. Wegener, "Experimental determination of systemeigenfrequencies on electrical drives" in 11th International Power Electronics and Motion Control Conference, Riga: {Riga Technical University}, 2004.

87.

R. Lach and S. Soter, "Individual Approach to an Efficient Minimization of Vibration an Noise Stimulation for Inverter-Fed Drives" in PCIM Asia 2004, 2004.

86.

R. Lach and S. Soter, "Sound source location measuring system for a systematic design modification of electrical machines" in PCIM Europe, 2004.

85.

S. Soter and R. Lach, "Von der Sonne zur eigenen Photovaltaik-Anlage: Verbraucher-Informationen im Internet" in 19. Symposium Photovoltaische Solarenergie, 2004.