Question

高分求英译汉此篇文章

这是一本国外电机学教材上节选的文章。要翻译了交给老师。麻烦达人帮忙翻译下。要求不高，只要不是机器翻译的。能看的顺畅就行。小弟分不多，只有一百多分。

14.19 Variable-speed drives

We have already seen that for a given load, an in-
crease in rotor resistance will cause the speed of an
induction motor to fall. Thus, by varying the exter-
nal resistors of a wound-rotor motor we can obtain
any speed we want, so long as it is below synchro-
nous speed. The problem is that the power dissipated
as heat in the resistors makes for a very inefficient
system, which becomes too costly when the motors
have ratings of several thousand horsepower. We get
around this problem by connecting the slip-rings to
an electronic converter. The converter changes the
power at low rotor frequency into power at line fre-
quency and feeds this power back into the 3-phase
system (Fig.14.17). As a result,such a variable-
speed control system is very efficient,in the sense
that little power is lost in the form of heat.

14.20 Frequency converter

A conventional wound-rotor motor may be used as
a frequency converter to generate a frequency dif-
ferent from that of the utility company. The stator of the wound-rotor machine is connected to the utility
line, and the rotor is driven at an appropriate speed
by a motor M(Fig.14.18). The rotor supplies power
to the 3-phase load at a voltage E2 and frequency f2,
both of which depend upon the slip. Thus, accord-
ing to Eqs.13.3 and 13.4, we have
f2=sf (13.3)
E2=sEoc (13.4)

In general,the desired frequency is two or three
times that of the utility company. According to Eq.
13.3,in order to attain this frequency the slip must
be positive and greater than 1.As a result, the shaft
must be rotated against the direction of the revolv-
ing flux.
The operation of the frequency converter is
then identical to that of an induction motor oper-
ating as a brake. However, the power Pjr, usually
dissipated as heat in the rotor, is now available to
supply power to the load. The converter acts as a
generator, and the active power flow is as shown
in Fig.14.19.Note how similar this is to the
power flow when an induction motor runs as a
brake (Fig.14.16).
都说了不要机器翻译……

Answer 1

14.19变速驱使我们已经看到某个负荷 在谈到皱痕转子电阻会使感应马达速度下降. 因此,不同的对外向-莱利一电阻绕线电机我们可以获得我们想要的任何速度, 只要是低于同步速度臭氧. 问题是,在电力消退热电阻起来很低效制度 而变得太昂贵,当汽车评级几千马力. 围绕这一问题,我们得到的连接不慎戒指电子器. 转炉转子低功率频率变化的权力变成邻线-淬火、饲料这回力 到三相系统(fig.14.17). 由于这种变速控制系统是非常有效率,因为在小功率损失 形式的热量. 14.20变频器常规绕线电机可作为变频器产生频率位元 从当年的事业公司. 定子的绕线机连接的公用线 而转子速度在适当的驱动马达米(fig.14.18). 电力供应转子的三相负荷时电压E2和频率的F2、 两者都取决于滑动. 因此,协议易为eqs.13.3和13.4, 我们的F2=丝素E2=(13.3)(13.4)seoc一般预期的频率是两三倍,公用事业公司. 据情商. 13.3,为了达到这个频率哥必须大于改善学生积极结果 要针对旋转轴的方向revolv莺通量. 变频器的运作是那么相同,感应电动机手术电机作为刹车. 但是,电力PJR-D,通常在转子热消退,现已向负载供电. 转炉作为发电机、 有源和流动所示fig.14.19.note这是何其相似的潮流时 异步电机作为刹车挤提(fig.14.16).