8?90)?sin(?90)?0.9848?9q?3?20sin1sin2?2?0.9598kq1??20sinqsin13?22P?3602?360?1???20?z36kN1?ky1?kq1?0.9452(3)ky1?sin(3y1?90?)?sin(3?80?)??0.86623q?1sin2?0.6667kq3?3qsin?12kN3?kq3ky3??0.667?0.866??0.5774ky3?sin(ky5?sin(5?80?)?0.64285?3?202?0.2176kq5? 5?203?sin2kN5?0.6428?0.2176?0.1399sin
y1ky7?sin(7?80?)??0.3427?3?202??0.1774kq7? 7?203?sin2kN7?(?0.342)?(?0.1174)?0.0607sin(4)E1?4.44fNkN1?1?4.44?50?108?0.9452?1.015?10?2?230.03(V)E3?4.44?3fNkN3?3?4.44?3?50?108?(?0.5774)?0.66?10?2?274.10(V)E5?4.44?5fNkN5?5?4.44?5?50?108?0.1399?0.24?10?2?40.25(V)E7?4.44?7fNkN7?7?9.17107E??E12?E32?E52?E72?...?360.19(V)EL?3E??405(V)4.18 一台汽轮发电机,2极,50Hz,定子54槽每槽内两根导体,a=1,y1=22槽,Y联接。已知空载线电压U0=6300V,求每极基波磁通量Ф1。
?V0?6300(V)?V?0?V03?6300?3637.41(V) 1.732E1?4.44fNkN1?54N?2pq2?1?2?3?aNc?11?1?18 ky1y1?sin(??90)?sin(2227?90)?0.9580sinq?1kq1?2??0.9555qsin12
q?z542mp?2?3?1?9?1?3601?4?166.7?kN1?ky1?kq1?0.9580?0.9555?0.9153??E1
1?4.44fNk?0.9945N1 4.19三相双层短距绕组,f=50Hz,2p=10,Z=180,y1=15,Nc=3,通φ1=0.113Wb,磁通密度B=(sinθ+0.3sin3θ+0.2sin5θ)T,试求: (1)导体电动势瞬时值表达式; (2)线圈电动势瞬时值表达式;
(3)绕组的相电动势和线电动势的有效值。
(1) q?z1802mp?2?3?5?6 ??z2p?18010?18 ?P?3605?3601?z?180?10?N?2pqaNc?180 kyy1?sin(1??90)?sin(1518?90)?0.9659 sinq?16?10kq1?2sin?2?0.9561qsin?123?sin102kN1?ky1?kq1?0.9235导体电动势有效值
a=1,每极基波磁 最大值
Ec1?2.22f?1?2.22?50?0.113?12.543Ec1m?3Ec1?17.74(V)2
??1?Bav1?l??Bm1?l?3?Bav3?l??3??2?Bm3?l?3?1Bm1??3Bm3Bm30.0339??1?3Bm13??3??5?Bm50.20.0226??1??0.113?5Bm155?Ec3?2.22f?3?2.22?50?0.0339?3.7629(V)Ec5?2.22f?5?2.22?50?0.0226?2.5086Ec3m?3Ec3?5.32(V)Ec5m?3Ec5?3.547(V)?el?el1?el3?el5?17.74sinwt?5.32sin3wt?3.547sin5wt(V) ?w?2?Pn160设t=0时??0,???wt
el?b(?)lv
(2)线圈电动势:
Ey1?4.44fNcky1?1?4.44?50?3?0.9659?0.113?50?72.69(V)Ey1m?2Ey1?1.414?72.69?102.8ky3?sin(3y1?90)?sin(
3?15?90)??0.707
?18Ey3?4.44fNcky3?3?4.44?50?3?(?0.707)?0.0339?50??15.96(V)Ey3m?2?15.96??22.57ky5?sin(5y1
??90)?sin(5?75)?0.2588Ey3m?5.51(V)
?ey?102.8sinwt?22.57sin3wt?5.51sin5wt
(3)
3?6?102?0.6440kq3??306?sin25?6?10sin2?0.1972kq5??506?sin2kN3?ky3?kq3??0.4553sinkN5?ky5?kq5?0.051?E1?4.44fNckN1?1?4.44?50?180?0.9235?0.113?4170(V)E3?616.77(V)E5?46.06(V)?E??E12?E32?E52?421.56(V)El?3E12?E32?7223(V)
22线圈中无三次谐波 故El?3E1?E3
4.20 一台三相同步发电机,定子为三相双层叠绕组,Y联接,2p=4,Z=36槽, y1=7τ/9,每槽导体数为6,a=1,基波磁通量Ф1=0.75Wb,基波电动势频率f1=50Hz,试求: (1)绕组的基波相电动势;
(2)若气隙中还存在三次谐波磁通,Ф3=0.1Wb,求合成相电动势和线电动势。 (1)?1?p?3602?360??20? z36z36??32mp2?3?2
z36????92p4q?ky1?sin(7?90?)?sin(?90?)?0.9397 ?9y1q?13?20sin2?2?0.9598kq1??20sinqsin13?22 kN1?ky1?kq1?0.9019sinN?2pq4?3Nc??3?36a1E1?4.44fNckN1?1?4.44?50?36?0.9019?0.75?5406(V)
(2) ky3?sin(3?70)??0.5
3?3?202?0.6667 kq3??3?203?sin2sinkN3?ky3?kq3??0.3333
E3?4.44fNkN3?3?4.44?50?36?0.3333?0.1?3?799.11(V)
E??E12?E32?5462(V)
El?3E1?9363(V)
注:因为星接,故线电势中无三次谐波
4.21 JO2-82-4三相感应电动机,PN=40kW,UN=38V,IN=75A,定子绕组采用三角形联接,双层叠绕组,4极,48槽,y1=10槽,每极导体数为22,a=2,试求:
(1)计算脉振磁动势基波和3、5、7等次谐波的振幅,并写出各相基波脉振磁动势的表达式;
(2)当B相电流为最大值时,写出各相基波磁动势的表达式;
(3)计算三相合成磁动势基波及5、7、11次谐波的幅值,并说明各次谐波的转向、极对数和转速;
(4)写出三相合成磁动势的基波及5、7、11次谐波的表达式;
(5)分析基波和5、7、11次谐波的绕组系数值,说明采用短距和分布绕组对磁动势波形有什么影响。 (1)I??IN3?75?43.3(A) 3 ?1?p?3602?360??15? z4848?44?3
48???124q?ky1?sin(10?90?)?sin(?90?)?0.9659 ?12y1q?14?15sin2?2?0.9577kq1??15sinqsin14?22 kN1?ky1?kq1?0.925sinN?2pq4?4Nc??11?88a2