Calculation Of Starting Performance For Medium-sized High-voltage Motors Based On The Magnetic Network

The process of asynchronous motor starting has two characteristics: Oneproblem is that the stator and rotor cores is highly saturated caused by big rotorwinding current, so the stator and rotor saturated leakage reactance decrease; Theother is high frequency of rotor current causing a strong skin effect on theconducting bar of the rotor grooves, and the skin caused the current distributionnonuniform.The paper calulaed the saturation effect by the magnetic network method,the method regard the area in which flux leakage is equally distributed as apermeance or a magnetic potential source, to form a magnetic network, andconsidering the effect of the yoke saturation and the magnetic slot wedge on thebase of traditional magnetic network algorithm, also using real magnetizationcurve of ferromagnetic materials to check the magnetic flux density and magneticfield strength, and rotor saturated leakage reactance can be got by the current it-eration.Skin effect is calculated by multi-layered method in this paper. The multi-layered calculation is the method that the slot height is dispersed when assumingthat the magnetic line of force is parallel to the slot bottom. Compared with per-meating depth method, the multi-layered method is simple, the program is con-cise and the calculation result is more accurate.Saturation effect is calculated when the motor starts by the improved mag-netic network method for medium-sized high-voltage motor of two poles whosecalculation error is bigger by the magnetic circuit method. The leakage flux cir-cuit of the stator and rotor is detailedly analysed in a pole. When saturated effect of the yoke and effect of the slot wedge on the saturated leakage magnetic circuitare considered, the magnetic network model of a pole is set up. At last, the skineffect is calculated by the multi-layered method and the starting parameters areobtained.Finally, the saturated effect and the skin effect are calculated for the motorin Y series by the improved magnetic network method and the multi-layeredmethod. Compared with magnetic circuit method and the original magnetic net-work method, tests confirm that the improved magnetic network method is effec-tive.