电机与拖动课件第4盏穆异步电机的电力拖动.ppt

电动运行状态 n = ( 1－s ) n0 = ( 1－0.026 3 ) ×1 500 r/min = 1 460.55 r/min (2) p = 1 时 sM = sN /(?MT－ ?MT2－1 ) = 0.04/(2－ 22－1 ) = 0.149 = 0.149× － －1 = 0.026 3 ( )2 29.2 10 29.2 10 s = sM － －1 TM T ( )2 TM T n0－ nN nN sN = 3 000－ 2 880 3 000 = = 0.04 sM= sM Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 60 2? TN = PN nN = × N·m = 12.61 N·m 60 2×3.14 3.8×103 2 880 TM = ?MT TN = 2×12.61 N·m = 25.22 N·m n = ( 1－s ) n0 = ( 1－0.030 8 ) ×3 000 r/min = 2 907.6 r/min = 0.149× － －1 = 0.030 8 ( )2 25.22 10 25.22 10 s= sM － －1 TM T ( )2 TM T Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. n0 T n O nM UN TL TL 四、笼型异步电动机的变压调速 TL 1. 调速方向 U1(＜UN)↓ →n↓ 2. 调速范围 D 较小。 U1 n0 T n O nM UN U1 3. 调速的平滑性 若能连续调节U1， n 可实现无级调速。 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 4. 调速的稳定性 稳定性差。 U1 ? →δ ? 5. 调速的经济性 经济性较差。 (1)需要可调交流电源。 (2)cos?1 和? 均较低。 6. 调速时的允许负载 既非恒转矩调速，又非恒功率调速。 因为 T∝U1P2 所以 U1 ? →T (n) ? → P2?? Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 【例 4.4.3 】 三相笼型异步电动机，PN = 15 kW， UN = 380 V，nN = 960 r/min，?MT = 2。试求： (1) U1 = 380V，TL = 120 N·m 时的转速； (2) U1 = 300V，TL = 100 N·m 时的转速。 解： (1) U1 = 380V，TL = 120 N·m 时 n0－ nN n0 sN = 1 000－ 960 1 000 = = 0.04 60 2? TN = PN nN = × N·m = 149.28 N·m 60 2×3.14 15×103 960 TM = ?MT TN = 2×149.28 N·m = 298.56 N·m Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Asp