EPE Association: NORpie 2008 - Topic 07: ELECTRIC MACHINES AND DRIVES

NORpie 2008 - Topic 07: ELECTRIC MACHINES AND DRIVES
You are here: EPE Documents > 05 - EPE Supported Conference Proceedings > NORpie - Proceedings > NORpie 2008 > NORpie 2008 - Topic 07: ELECTRIC MACHINES AND DRIVES

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   Optimum supply for an inverter-fed cage induction motor at different load conditions
By M. Jahirul Islam; Antero Arkkio [View]
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Abstract: 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.

   A Discussion about a Start-up Procedure of a Doubly-Fed Induction Generator System
By J. L. Da Silva, R. G. de Oliveira, S. R Silva, B. Rabelo, W. Hofmann [View]
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Abstract: The present work proposes a start-up procedure for a doubly-fed induction generator (DFIG) driven by a wind turbine. In the DFIG topology the stator is connected direct to the grid while the rotor is connected to a back-to-back converter. This structure requires some care during grid synchronization to avoid undesired overloads. The main goal of a start-up procedure is to reduce the stresses on the electrical and mechanical components during synchronization. In this work, it is achieved by equalization among the induced stator voltage, the voltage over the filter capacitor and the grid voltage. A phase-locked-loop (PLL) computes the grid voltage phase displacement required for the system control orientation and synchronization procedures. Previous to the starting-up, the output currents set-points of the grid-side converter and rotor-side converter are computed in order to produce the same grid voltage over the filter capacitors and on the stator terminals. The whole procedure is summarized in seven different steps: turbine acceleration by the pitch control, DC-link pre-charge; initialization of the filter current controllers; filter synchronization; DC-Link voltage adjust; rotor current controllers' initialization and stator synchronization. The proposed start-up procedure was tested in a 4 kW test bench and the description of each step as well as simulation and experimental results are presented throughout the paper.

   Small-Signal Analysis of a Saturated Induction Motor
By Mikaela Ranta, Marko Hinkkanen, Anna-Kaisa Repo, Jorma Luomi [View]
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Abstract: 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.

   Functional Simulations of Power Electronics Components in Series-Hybrid Machinery for the needs of OEM
By Matti Liukkonen, Ari Hentunen, Jussi Suomela, Jorma KyyrÃ¤ [View]
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Abstract: This paper proposes method for rapid control pro-totyping of the series-hybrid transmission system. The rapid con-trol 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 prototyp-ing method is the original equipment manufacturer (OEM), where the objective is to build devices from subcontractorâ€™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.

NORpie 2008 - Topic 07: ELECTRIC MACHINES AND DRIVES
You are here: EPE Documents > 05 - EPE Supported Conference Proceedings > NORpie - Proceedings > NORpie 2008 > NORpie 2008 - Topic 07: ELECTRIC MACHINES AND DRIVES
	[return to parent folder]

	Optimum supply for an inverter-fed cage induction motor at different load conditions By M. Jahirul Islam; Antero Arkkio	[View] [Download]
Abstract: 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.

	A Discussion about a Start-up Procedure of a Doubly-Fed Induction Generator System By J. L. Da Silva, R. G. de Oliveira, S. R Silva, B. Rabelo, W. Hofmann	[View] [Download]
Abstract: The present work proposes a start-up procedure for a doubly-fed induction generator (DFIG) driven by a wind turbine. In the DFIG topology the stator is connected direct to the grid while the rotor is connected to a back-to-back converter. This structure requires some care during grid synchronization to avoid undesired overloads. The main goal of a start-up procedure is to reduce the stresses on the electrical and mechanical components during synchronization. In this work, it is achieved by equalization among the induced stator voltage, the voltage over the filter capacitor and the grid voltage. A phase-locked-loop (PLL) computes the grid voltage phase displacement required for the system control orientation and synchronization procedures. Previous to the starting-up, the output currents set-points of the grid-side converter and rotor-side converter are computed in order to produce the same grid voltage over the filter capacitors and on the stator terminals. The whole procedure is summarized in seven different steps: turbine acceleration by the pitch control, DC-link pre-charge; initialization of the filter current controllers; filter synchronization; DC-Link voltage adjust; rotor current controllers' initialization and stator synchronization. The proposed start-up procedure was tested in a 4 kW test bench and the description of each step as well as simulation and experimental results are presented throughout the paper.

	Small-Signal Analysis of a Saturated Induction Motor By Mikaela Ranta, Marko Hinkkanen, Anna-Kaisa Repo, Jorma Luomi	[View] [Download]
Abstract: 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.

	Functional Simulations of Power Electronics Components in Series-Hybrid Machinery for the needs of OEM By Matti Liukkonen, Ari Hentunen, Jussi Suomela, Jorma KyyrÃ¤	[View] [Download]
Abstract: This paper proposes method for rapid control pro-totyping of the series-hybrid transmission system. The rapid con-trol 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 prototyp-ing method is the original equipment manufacturer (OEM), where the objective is to build devices from subcontractorâ€™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.