第三章 交流电机共同理论习题（中英）

第三章 交流电机共同理论

复 习 题

1. 感应电机与同步电机的基本差别是什么？ 2. 说明单相绕组磁动势基波的性质和特点？ 3. 说明三相绕组合成磁动势基波的性质和特点？

4. 交流电机中磁场的旋转速度与交流电流的频率之间有何关系？

5. 三相单层绕组，Q =24，2p =4，a =2，画出三相绕组的展开图并计算绕组因数。

q?Qp?3602?0.966,k?kk?0.966 答：q??2,???30?,ky1?1,kq1?Wy1q1?2pmQqsin2sin

6. 三相双层短距叠绕组，Q =24，2p =2，y1?因数。 答:

5?，a =1，画出A相绕组的展开图并计算绕组6Q1?360??q??4,???15?,???(??y)?30?,ky1?cos?0.966,2pm242 q?sin2?0.9577,k?0.966?0.9577?0.925kq1?W1?qsin2

7. 如何改变感应电动机的旋转方向？

8. 说明节距因数和分布因数的物理意义，交流电机中为何采用短距、分布绕组？

9. 在对称的两相绕组(绕组轴线空间差90?电角度)内通入对称的两相电流(时间上差90?)，试 分析产生的合成磁动势的基波。

10. 交流绕组中的谐波电动势是如何产生的？如何消除或削弱谐波电动势？ 11. 说明交流电机中谐波磁动势的原因？

12.一台三相同步发电机，2p=6，定子为双层叠绕组，Q1?54,y1?7,a=1,星形联接，每个线圈的匝数为10匝，试求：

(1)若在绕组中通入频率为50Hz、有效值为10 A的三相对称电流，其基波旋转磁势的幅值和转速。

(2)若每极磁通?m=0.11 Wb，其相电势的有效值。 答：

2pqNyQ3?360?f?50Hz,q??3槽,N1??90匝,??0.11Wb,???20?电角2pma543?20sin2?0.9598,k?cos20??0.9397??9槽,kq1?y1203sin2kW?kq1ky1?0.902,Ep1?4.44fNkW1??1982.4V

13. 一台三相感应电动机，2p=4，定子为双层叠绕组，Q1?24,y1?5,a=1,星形联接，每相串联匝数N?72。当通入对称三相电流，每相电流的有效值为20A时，试求三相合成磁动势的基波以及5、7次谐波的幅值以及转速。 答：

Qq??2槽,??30?电角,??6槽,??30?,ky1?0.9659,kq1?0.9659,kW1?0.9332pm3IN F1??0.9?11kW1?1007.64安匝2p60fn??1500r/minp14. 一台三相、Y接、50-Hz的2极同步电机，定子每相串联总匝数为2000匝，绕组因数kw=0.966，为要使电机的电枢端电压为6kV，每极磁通应该为多少？ 答：

EL?3E??6000V,E??3464.2V?4.44fNkw?1,?1?8.08?10?3web

15.一台2极、三相、Y接、60-Hz的同步发电机，定子每相串联总匝数为18匝，绕组因数kw=0.933。每极的基波磁通为3.31Wb，电机转速为3600 r/min。计算发电机空载端电压的有效值为多少？ 答：E??4.44fNkw?1?14.8kV,EL?3E??25.6kV

16. 一台2极、60Hz、Y接的三相同步发电机，定子每相串联总匝数为45匝，绕组因数kw=0.93，每极磁通为2.1Wb，电枢电流为20A。试求 (a) 电枢绕组感应电势的幅值和有效值各为多少？ (b) 电枢一相绕组基波磁动势的幅值为多少？ (c) 电枢三相绕组基波磁动势的幅值为多少？ 答：

(1)E?4.44fN1?kW1?23.412kV(2)F1?0.9E??2E?33.1kVI1N1?kW1?753.3安匝F1?2F1?1065.33安匝 p(3)F31?1.5F1?1130安匝F??2F31?1598安匝17. 如果在三相对称绕组中通入大小及相位均相同的电流，试分析三相合成基波磁动势的情况。

18. 三相感应电动机，定子绕组星形联结，若定子绕组有一相断线，将产生什么性质的磁动

势？

Questions and Problems

1. What are the major differences between synchronous machine and induction machine? 2. What are the natures of fundamental of mmf wave of a single-phase winding? 3. What are the natures of fundamental of mmf wave of a three-phase winding?

4. What is the relationship between the electrical frequency and magnetic field speed for an ac machine?

5. A three-phase single-layer winding, with the number of slots Q=24, the number of poles 2p = 4, the number of parallel circuits a=2. Sketch a developed diagram of the three-phase winding and calculate the winding factor?

6. A three-phase double-layer lap winding, with the number of slots Q=24, the number of poles 2p = 2, winding pitchy1?10, and the number of parallel circuit a=1. Sketch the developed diagram of phase A and calculate the winding factor?

7. How to reverse the rotation direction of an induction motor?

8. Indicate the physical meanings of the pitch factor and the distribution factor?

9. If two-phase currents (the phase difference is 90?) are flowing in two-phase windings (the space difference of the two winding-axis is 90 electrical degree), examine the fundamentals of the mmf wave.

10. Indicate the physical reasons of harmonic emf induced in AC windings? How to eliminate or weaken the harmonic induced emf ?

11. Indicate the physical reasons of harmonic mmf produced in AC machines?

12. A six-pole three-phase synchronous generator, which the stator has a three-phase double-layer lap winding, the number of slots Q=54, winding pitch y1 = 7, the number of parallel circuits a = 2, Y-connection, the number of turns of each coil is 10. If the flux per-pole is ?m = 0.11 Wb, hence calculate the rms of the emf of the winding of one phase.

13. A four-pole three-phase induction motor, which the stator has a three-phase double-layer lap winding, with the number of slots Q=24, winding pitch y1 = 5, the number of parallel circuits a = 1, Y-connection. If three-phase current of 50-Hz and 20-A (rms) flows in the winding, what is the rotation speed and amplitude of the fundamental of the mmf wave?

14. A three-phase, Y-connected, 50-Hz, two-pole synchronous machine has a stator with 2000 turns of wire per phase and winding factor kw=0.966. What rotor flux would be required to produced a terminal (line to line) voltage of 6 kV?

15. A two-pole, three-phase, Y-connected 60-Hz round-rotor synchronous generator has a armature winding with 18 turns per phase and winding factor kw=0.933. The fundamental flux per pole is 3.31Wb. The rotor is driven by a steam turbine at a speed of 3600 r/min. Compute the rms value of the open-circuit voltage generated in the armature.

16. A two-pole,60 Hz, three-phase, laboratory-size synchronous generator has a Y-connected armature winding, the armature winding consists of 45 turns per phase with a winding factor kw=0.93. The flux per pole is 2.1Wb ,the armature current Ia=20 A.

(a) Calculate the peak value and rms value of the induced voltage in armature-phase-winding. (b) Calculate the peak value of the fundamental mmf in armature-phase-winding.

(c) Calculate the peak value of the fundamental mmf in three-phase armature windings.

17. If currents of same rms and same phase position flow in a three-phase winding, examine the fundamental of the mmf wave.

18. A three-phase induction motor has a three-phase winding of Y-connection, if one-phase of the stator windings is broken; examine the fundamentals of the mmf in the machine.

本文来源：https://www.bwwdw.com/article/gj6f.html