Logo Leibniz Universität Hannover
Logo: Institute for Drive Systems and Power Electronics/Leibniz Universität Hannover
Logo Leibniz Universität Hannover
Logo: Institute for Drive Systems and Power Electronics/Leibniz Universität Hannover
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Main Fields of Research

 

in Electrical Machines and Drive Systems

Research work mainly refers to drive systems with induction or synchronous machines for industrial applications and to all kinds of small electrical machines and actuators.

Key Words

  • Time-efficient schemes for calculating the characteristics and performance of conventional machines (e.g. zero-sequence or subtransient impedance of salient pole synchronous machines) or novel machines (e.g. losses in the damper winding of high-speed converter-fed synchronous motors with permanent magnet excitation); development of combined analytical and numerical calculation methods
  • Development of micro actuators (rotating and linear motors)
  • Design and optimization of windings, e.g. with tooth-wound coils
  • Calculation of electromagnetic and mechanical stresses in drive systems during transient phenomena (for example start-up, three or two-phase terminal short circuits, voltage recovery, system transfer)
  • Calculation of electromagnetically excited vibrations (e.g. casing vibrations of twice the line frequency in two-pole cage induction motors) by use of analytical and numerical methods
  • Parasitic effects caused by harmonics in the current and spatial harmonic fields (e.g. magnetic tones, shaft voltages, unbalanced magnetic pull, additional losses, torque oscillations)
  • Diagnosis of defects and failures (e.g. rotor eccentricities, asymmetries within cage rotors, all types of winding defects) by use of specific measuring coils
  • Interactions between power electronic equipment and rotating electrical machines (procedures for optimization)
  • System perturbations and other EMC effects in connection with rotating electrical machines
  • Prediction and prevention of bearing voltages and bearing currents
  • Time-efficient calculation of efficiency maps and loss characteristics
  • Determination and optimisation of performance characteristics, energy consumption and  temperature rise in any duty cycle
  • Mechatronic systems, e.g. by use of linear direct drives
  • Novel cooling methods for drives with extremely high power density
  • Machine design that is especially suitable for sensorless position control 

in Power Electronics and Drive Control

Research activities comprise the application of power semiconductors, the design of power electronic systems as well as modulation and control methods for  micro actuators, industrial drives, power systems and automotive. 

Key Words

  • Characterisation and investigation of semiconductors (MOSFET, IGBT, SiC components) by measurements, using voltages of 3 V to 6500 V and currents of 0,1 A to 3000 A
  • Development of gate drives  for IGBTs, e.g. with digital signal processing and adaptive optimisation of the switching behaviour
  • Analysis, calculation and optimum dimensioning of power electronic circuits from the electrical and thermal point of view
  • Design and investigation of converters with novel SiC semiconductors for industrial and automotive applications
  • Converters with switched capacitors as drives for micro actuators
  • DC/DC converters for fuel cell systems for decentralised power generation
  • Electronic ballast for energy-saving lamps
  • Novel modulation methods for voltage source inverters with low pulse rate (SB-ZePoC)
  • Control of modular multilevel converters
  • Medium-voltage converters for connecting battery storage to medium-voltage grids
  • Line-side control concepts for wind generation plants with full converters in the  MW range
  • Highly dynamic control of generator/converter systems with islanding capability
  • Drive control for highly dynamic drives with sinusoidal output filters and very low switching frequencies
  • Encoderless control of synchronous machines at low speed
  • Highly dynamic position control for micro actuators (modified and adaptive analog sliding-mode control)
  • Drive systems for electric and hybrid vehicles