atmosphere/'ætməsfɪr/()
A.意图
B.气氛;大气;空气
C.控诉
D.意向
B、气氛;大气;空气
A.意图
B.气氛;大气;空气
C.控诉
D.意向
B、气氛;大气;空气
A.TM 标 10 万 ,R 标 5 万
B.TM 标 8 万, R 标 2 万
C.TM 标 8 万, R 标 4 万
D.TM 标 10 万, R 标 3 万
某三相异步电动机,PN=30 kW,nN=980 r/min,αMT=2.2,αst=2.0,求:(1)定子线电压U1L=UN时的TM和Tst;(2)U1L=0.8 UN时的TM和Tst。
The atmosphere certain gases mixed together in definite proportions.
A: consists of
B; is made up
C; composes of
Which of the following is true according to the passage?
A.The volume of the atmosphere is four times that of the world's.
B.The water in the oceans is the main source of rain and snow on land areas.
C.The atmosphere is mainly composed of the vapor carded over land by air currents.
D.The earth cannot support the water in the atmosphere if it falls down onto the earth suddenly.
A.statistics
B.atmosphere
C.concentration
D.supplement
(1) 在此系统中,当转速给定信号最大值Unm=15V时, n=nN=1500r/min;电流给定信号最大值Uim=10V时, 允许最大电流Icm=30A, 电抠回路总电阻R=1.4, PWM变换器的放大倍数Ks=30,电动机额定电流Is=20A, 电动势系数Ce=0.128V·min/r,现系统在Ln=5V, Idl=20A时稳定运行。求此时的稳态转速n=?ACR的输出电压Uc=?
(2)当系统在上述情况下运行时,电动机突然失磁(=0),系统将会发生什么现象?试分析并说明之。若系统能够稳定下来,则稳定后n=?Un=? Ui=? Id=? Uc=?
(3)该系统转速环按典型Ⅱ型系统设计,且按Mmin准则选择参数,取中频宽h=5,已知转速环小时间常数Tn=0.05s, 求转速环在跟随给定作用下的开环传递函数, 并计算出放大系数及各时间常数。
(4) 该系统由空载(IdL=0) 突加额定负载时, 电流Ⅰd和转速n的动态过程波形是怎样的?已知机电时间常数Tm=0.05s, 计算其最大动态速降△nmax和恢复时间t。