[comp] Sähkötekniikan korkeakoulu / ELEC

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Browsing [comp] Sähkötekniikan korkeakoulu / ELEC by Department "Department of Electrical Engineering"

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  • Design of master control unit for laboratory prototype of traction converter for locomotives
    (2008) Žák, Jan; Peroutka, Zdeněk; Ovaska, Seppo J.
     Faculty of Electronics, Communications and Automation | A4 Artikkeli konferenssijulkaisussa
    This paper deals with the prototype of a main traction converter with medium-frequency transformer for AC trolley wire-fed locomotives. The attention is paid to the new master control and diagnostic unit. The designed master control unit has been implemented in the LabVIEW environment. Our master control unit ensures an effective human interface between a user and the control hardware. In this case, the master unit makes possible both extensive control and diagnostic operations of the laboratory prototype of the traction converter. The master unit was tested extensively by experiments performed on a designed traction converter prototype of 12-kW rated power.
  • Functional simulations of power electronics components in series-hybrid machinery for the needs of OEM
    (2008) Liukkonen, Matti; Hentunen, Ari; Suomela, Jussi; Kyyrä, Jorma
     Faculty of Electronics, Communications and Automation | A4 Artikkeli konferenssijulkaisussa
    This paper proposes method for rapid control prototyping of the series-hybrid transmission system. The rapid control prototyping needs simulation submodels from all system components in order to develop supervisory control software. The same simulation models can also be used to optimize the drive train. The target framework for the rapid control prototyping method is the original equipment manufacturer (OEM), where the objective is to build devices from subcontractor's components. The machinery industry, as a target group, uses high power ratings for the creation of motion, which leads to high voltage and current values used in the system. Therefore, prototyping is started with careful simulations. This paper also seeks to create a general idea about the structure of the series-hybrid power transmission and assists the start of the process for designing the supervisory control.
  • Insertion loss and network parameters in the analysis of power filters
    (2008) Kostov, Konstantin S.; Kyyrä, Jorma J.
     Faculty of Electronics, Communications and Automation | A4 Artikkeli konferenssijulkaisussa
    The insertion loss (IL) is regarded as the best interference suppression characteristic of power filters or suppression components. The IL definitions are considered and as an alternative the paper suggests the use of network parameters. It is a known fact that the standard IL measurements do not provide reliable information about the operational performance of a suppressor. This is largely due to the source and load mismatch, which is typical in power lines. Arguments are presented, showing that network parameters allow for more complete and reliable characterization of power filters and components. The IL would not be abandoned, because the network parameters provide enough information to obtain not only the standard IL, but also the IL in a non 50 Ω system. A new treatment of "worst case" or minimum IL is proposed, which is also based on network parameters. Furthermore, input, output, or transfer impedances, simulation models, and other characteristics, can be obtained from the network parameters, but not from the currently published standard IL data.
  • Optimum supply for an inverter-fed cage induction motor at different load conditions
    (2008) Islam, M. Jahirul; Arkkio, Antero
     Faculty of Electronics, Communications and Automation | A4 Artikkeli konferenssijulkaisussa
    The effects of power supply on the energy efficiency of a form-wound cage induction motor are studied when the motor operates under light loads. The cage induction motor is modelled with the space and time discretized finite-element analysis. The resistive losses are taken into account accurately by modelling eddy currents in the form-wound multi-conductor stator winding and the rotor cage. The core losses are considered with conventional empirical equations. A pulse-width-modulated (PWM) voltage is used to supply the motor. The fundamental harmonic (FH) terminal voltage is decreased from its rated value and the slip is adjusted to achieve a particular load condition. The variation of the total electromagnetic as well as the stator resistive losses are analyzed to find the optimum supply.
  • Reference signal generator for active power filters using MGP-FIR filter designed by evolutionary programming
    (2008) Komrska, Tomáš; Ovaska, Seppo J.
     Faculty of Electronics, Communications and Automation | A4 Artikkeli konferenssijulkaisussa
    This paper describes a high-performance reference signal generator for active power filters extracting the fundamental signal component from distorted current signals. In order to achieve high-quality output as well as computationally effective algorithm, the generator employs an adaptive and predictive MGP-FIR (Multiplicative General Parameter) bandpass filter designed by evolutionary programming. Detailed procedures of MGP-FIR filtering and evolutionary optimization are first discussed; theoretical conclusions are verified by illustrative simulation results.
  • Small-signal analysis of a saturated induction motor
    (2008) Ranta, Mikaela; Hinkkanen, Marko; Repo, Anna-Kaisa; Luomi, Jorma
     Faculty of Electronics, Communications and Automation | A4 Artikkeli konferenssijulkaisussa
    Due to magnetic saturation, the small-signal admittance of an induction motor is dependent on the direction of the excitation signal. The angle-dependence of the admittance can be used in the estimation of the flux angle, and it should be taken into account when identifying motor parameters. In this paper, the small-signal admittance of a 2.2-kW induction motor is measured at different excitation frequencies and operating points. The measured admittances are compared to data obtained by means of finite element analysis (FEA). A small-signal model of the induction motor is fitted to the admittances to analyze the results. The admittances obtained from FEA and laboratory experiments correspond well to each other, particularly at low excitation frequencies.