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This paper deals with the online parameter estimation of squirrel-cage induction machines using the Gradient Descent Method and coupled stator and rotor flux observers. Stator resistance, rotor resistance and mutual inductance can be estimated simultaneously in real time. For a non-ambiguous parameter tracking, an additional voltage is superimposed. The influence of inverter nonlinearity, current...
An important alteration of the equivalent loads profile has been observed in the electrical energy distribution systems, for the last years. Such fact is due to the significant increment of the electronic processors of electric energy that, in general, behave as nonlinear loads, generating harmonic distortions in the currents and voltages along the electric network. The effects of these nonlinear...
This paper presents an improved PWM strategy for three-phase inverters, especially suited for use at low ratios of switching frequency to fundamental output frequency. The method of third-harmonic injection is used to ensure maximum utilisation of the DC bus voltage. Implementation issues for the new modulation strategy are discussed. A comparison with a conventional, regularly sampled PWM is presented,...
This paper deals with a method to derive the junction temperature of an IGBT while the device is in operation. In order to achieve this the gate-emitter voltage, the collector current and the collector-emitter voltage are digitized on the driver board. Due to the fact that material parameters vary with temperature, the waveforms of the switching transients vary with temperature, too. Thus, there is...
Gate units of todaypsilas converters are in most cases voltage sources charging the input capacitance with a fixed gate resistor. Consequently, there is hardly no possibility to adapt quickly the gate unit to different semiconductor devices. During operation, there is no adaption process to adjust the switching transients to their actual optimum. The possibilities to implement new features or to adapt...
Gate units of todaypsilas converters are in most cases voltage sources charging the input capacitance with a fixed gate resistor. In some publications, fixed current sources are implemented to support the charging process with a supplementary gate current. These solutions are implemented in an analog way and are designed and respectively optimized for fixed parameters and devices. During operation,...
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