Assumptions and final structure of series motor equations were presented. In the description, a magnetization curve, which significantly affects properties of the motor, was taken into account. Nonlinearly connected with magnetization curve is present in a induction voltage drop and in a rotation voltage, as well. Quantitive examinations were performed for a series motor PBSOa12x type. A share of current dependent induction voltage drop components was examined. It was assumed that additional, so-called “negative inductance”, which is a product of a current and partial, current derivative of inductance, can be omitted. This conclusion can be regarded as general. It refers to a typical motor taking into account construction and magnetic materials. So-called incremental equations of a motor were formulated, which describe it behaviour in a small deviation from an equilibrium point. Using a precise model, a simulation of a motor start fed from a DC controlled rectifier was performed. The simulated system was a closed one with a current limitation. The feeding voltage was an input signal.
Przedstawiono koncepcję sprężysto-plastycznego modelu częściowo nawodnionego gruntu. Model jest oparty na zmodyfikowanym równaniu powierzchni plastyczności Wheelera i Shivakumara. W przypadku zmiennej wartości ssania uogólnione prawo wzmocnienia wiąże przyrost plastycznej części wskaźnika porowatości z poziomem efektywnego naprężenia i ssania.
EN
The paper presents the concept of elasto-plastic model for partially saturated soil. The model operates equation of Wheeler and Shivakumar’s plastic surface. Generalized hardening rule, for changing value of suction, connects the increment of plastic part of void ratio with stress and suction levels.
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