Veröffentlichungen
- 80.M. Linke, R. Kennel and J. Holtz, "Sensorless speed and position control of synchronous machines using alternating carrier injection" in IEEE International Electric Machines and Drives Conference, 2003. IEMDC'03, 2003, pp. 1211-1217 vol.2.
Abstract:
High frequency carrier injection is a promising approach solving high performance sensorless drive demands. Position control at low and zero speed is only possible using anisotropic effects considered in high-frequency models. The usually open loop carrier signal injection is impacted by nonlinear inverter properties like the dead-time effect. This paper discusses the influence of the dead time effect on the carrier signal excitation comparing alternating and revolving injection principles. To overcome disturbing effects an alternating injection procedure is proposed using a predefined injection angle. The approach reduces the effects of the inverter distortion voltages. As a result it is possible to track even small saliencies typical for surface mounted permanent magnet synchronous machines. For processing the high frequency current for position estimation, there is no additional hardware necessary within a standard drives with field oriented control. The paper presents theoretical analysis and experimental results. - 79.D. Hansen, J. Holtz and R. Kennel, "Cutter distance sensor for an adaptive position-/torque control in cross cutters" in Conference Record of the 2002 Annual Pulp and Paper Industry Technical Conference (Cat. No.02CH37352), 2002, pp. 54--61.
Abstract:
Cross cutters are important equipment in the paper industry. A well-known design is to use mechanically coupled cutters providing synchronous motion. To improve dynamic behavior of cross cutters and to reduce maintenance effort it would be advantageous to operate the cutters by separately controlled servo drives. This idea requires very exact knowledge concerning cutter positions to ensure proper operation and to avoid any crash. This paper presents a progressive sensor measuring the distance between the cutter knives and distinguishing between knives approaching or touching each other directly on the one hand and normal cutting operation with material between the knives on the other hand. Measuring results obtained by a test example of the sensor are presented. - 78.M. Linke, R. Kennel and J. Holtz, "Sensorless position control of permanent magnet synchronous machines without limitation at zero speed" in IEEE 2002 28th Annual Conference of the Industrial Electronics Society. IECON 02, 2002, pp. 674-679 vol.1.
Abstract:
Sensorless position control of surface mounted permanent magnet synchronous machines (SMPMSM) still is a challenge. High performance position control at low and zero speed is only possible using anisotropic effects being considered not in the fundamental-frequency machine models, but in extended high-frequency models. This paper presents a new high-frequency injection method estimating the rotor position, which overcomes the small signal to noise ratio inherent to methods of this type published so far. This enables to track even small saliencies typical for SMPM synchronous machines. A small high-frequency voltage signal is injected into the rotor d-axis with no influence on the torque producing q-current. The demodulation of the responding high-frequency current signal is independent on machine parameters. Therefore the proposed method is independent on machine parameters and simply adaptable to different machines. As only the high frequency current has to be processed for position estimation, there is no additional hardware necessary besides that for standard drives with field oriented control. - 77.S. Soter and R. Lach, "Noise minimization of three-phase current machines by variation and modification of control scheme and power electronics" in PCIM Europe, 2002.
- 76.S. Soter, S. Buchhold and R. Lach, "Niederspannungswechselrichter mit hohem Wirkungsgrad" in 17. Symposium Photovoltaische Solarenergie, 2002.
- 75.S. Soter and S. Buchhold, "Low Voltage Converter for Feeding the Net with Fuel Cell Power" in PCIM Asia 2002, 2002.
- 74.J. Holtz, "Sensorless control of induction motor drives", Proceedings of the IEEE, vol. 90, no. 8, pp. 1359--1394, 2002.
Abstract:
Controlled induction motor drives without mechanical speed sensors at the motor shaft have the attractions of low cost and high reliability. To replace the sensor the information on the rotor speed is extracted from measured stator voltages and currents at the motor terminals. Vector-controlled drives require estimating the magnitude and spatial orientation of the fundamental magnetic flux waves in the stator or in the rotor. Open-loop estimators or closed-loop observers are used for this purpose. They differ with respect to accuracy, robustness, and sensitivity against model parameter variations. Dynamic performance and steady-state speed accuracy in the low-speed range can be achieved by exploiting parasitic effects of the machine. The overview in this paper uses signal flow graphs of complex space vector quantities to provide an insightful description of the systems used in sensorless control of induction motors. - 73.S. Soter and S. Buchhold, "Converter for Mains Supply - Low-Priced and Intelligent" in 10th International Power Electronics and Motion Control Conference, Dubrovnik, 2002.
- 72.R. P. Burgos, E. P. Wiechmann and J. Holtz, "Complex state variables modeling and nonlinear control of PWM voltage- and current-source rectifiers" in IEEE 2002 28th Annual Conference of the Industrial Electronics Society. IECON 02, 2002, pp. 187-192 vol.1.
Abstract:
This paper proposes the use of complex state variables to model and control PWM voltage- and current-source rectifiers, a technique originally developed for AC machines based on space vector theory. This technique employs complex signal flow graphs to model systems of differential equations, hence rendering them intelligible by visual inspection. Moreover, it allows nonlinear control laws to be directly obtained from converter models, further simplifying the control system design. Feedback linearization is herein used, a nonlinear strategy of great simplicity and intuitiveness. Under the proposed control schemes both rectifiers attained fully decoupled d-q axes dynamics, thus enabling them as VAr compensators, and also achieved a constant dynamic response totally independent from the drive operating point. The latter is highly desirable for high-performance drives featuring continual accelerations and decelerations. The paper includes a detailed modeling and nonlinear control law design-procedure for both PWM rectifiers, together with experimental results from 10 kVA TMS320C32 DSP-based laboratory prototypes used for evaluation purposes. - 71.S. Soter and S. Buchhold, "Adaptable inverter for injection of fuel cell and photovoltaic power" in Proceedings of the Power Conversion Conference-Osaka 2002 (Cat. No.02TH8579), 2002, pp. 1453-1455 vol.3.
Abstract:
Due to environmental conditions it is becoming more and more important to apply renewable energies and efficient technologies. For power injection of photovoltaic and fuel cell energy an inverter is needed. The presented modular and flexible prototype works with different energy sources such as photovoltaic, fuel cell and battery. It is possible to adjust active and reactive power as well as current shape separately within limits to improve power quality. The power electronics works very well and is able to convert 20 to 80 VDC into 110 VAC/60 Hz or 230 VAC/50 Hz with a high flexibility and efficiency.
