电大机电接口技术期末自测题 一、选择题 1. 要求电压比较器仅在输入电压过零，输出电压发生跳变。除此之外，输出电压保持不变。并希望输入电压大于零时输出为高电平。则应选用（ ）。

A．差动型电平检测器　　 　　　B．同相输入过零比较器 C．窗口比较器　　　　　　　　　　　　D．回差电压比较器 2. 317 为（ ）集成稳压器。

A．三端可调正电压输出　　　　　　　　B．固定型正电压输出 C．固定型负电压输出　　　　　　　　　D．三端可调负电压输出 3. 若希望电压比较器在输入小于＋５Ｖ时输出电压为高电平，而在输入大于＋５Ｖ时输出电压为低电平。则应选用（ ）。

A．反相端输入差动电平检测器　　　　　B．过零比较器 C．窗口比较器　　　　　　　　　　　　D．回差电压比较器 4. 模拟电压比较器同运算放大器的主要区别是：模拟电压比较器中的工作于（ ）。

Ａ．开环状态　　　　　　　　　　　　　B．负反馈状态 Ｃ．深度负反馈状态　　　　　　　　　　D．高电平状态 5. 单向晶闸管有三个引脚：A 、K 和G ，其中K 为（ ）。

Ａ．阳极　　　　　　　　　　　　　　　B．阴极 Ｃ．控制极　　　　　　　　　　　　　　D．门级 6. AD202/AD204是基于（ ）原理的隔离放大器。

Ａ．变压器耦合　　　　　　　　　　　　Ｂ．光电隔离 Ｃ．继电器隔离　　　　　　　　　　　　Ｄ．线性光电隔离 7. 运算放大器中的（ ）单元用于设置各级放大电路的静态工作点。

Ａ．输入级　　　　　　　　　　　　　　Ｂ．输出级 Ｃ．中间级　　　　　　　　　　　　　　Ｄ．偏置电路 8. 最早出现的电动机是（ ）。

Ａ．直流电动机　　　　　　　　　　　　Ｂ．交流电动机 Ｃ．步进电动机　　　　　　　　　　　　Ｄ．直线电动机 9. 三相异步电动机改变同步转速n0的方法是（ ）。

Ａ．调节转子电阻　　　　　　　　　　　B．调节定子电压 Ｃ．调节电源频率　　　　　　　　　　　D．调节转子电压 10. L290是一种( )芯片。

A．功率驱动芯片 B．步进电机环形分配器 C．细分电路 D．转速／电压变换器 二、简答题 1．什么是光电耦合器件？光电耦合器件有什么特点？ 2．隔离的实质是什么？有哪些常用的隔离？ 3．SPWM的基本思想是什么？产生SPWM控制信号的方法主要有哪三种？ 4．常用的隔离方式有哪几种?光电隔离的特点是什么? 5．三相步进电机的工作方式哪几种?其中“单”、“双”、“拍”各是什么意思? 6．单向晶闸管的导通条件是什么？ 7．什么是直流电动机？它有哪些优点？ 8．什么是步进电机？ 9．环形分配器的主要功能是什么？ 三、分析计算题 图1 1. 写出图1所示电路的传递函数。

四、设计电路 1、用7805设计一个输出电压为+7V的稳压电路。

机电接口技术期末自测题答案 一、选择题 1、B　　　2、A　　　3、A　　　4、A　　　5、B 6、A　　　7、D　　　8、A　　　9、C　　　10、D 二、简答题 1．什么是光电耦合器件？光电耦合器件有什么特点？ 光电耦合器件将发光元件和受光元件组合在一起，通过电-光-电这种转换，利用“光”这一环节完成隔离功能，使输入和输出在电气上是完全隔离的。根据受光元件的不同可分为晶体管输出型和晶闸管输出型两类。

光电耦合器具有三个特点：①信号传递采取电-光-电的形式，能够避免输出端对输入端可能产生的反馈和干扰，②抑制噪声干扰能力强；
③具有耐用、可靠性高和速度快等优点。　　 2．隔离的实质是什么？有哪些常用的隔离？ 答：隔离的实质是把引进的干扰通道切断，从而达到隔离现场干扰的目的。测控装置与现场信号之间、弱电和强电之间，常用的隔离方式有光电隔离、继电器隔离、变压器隔离、隔离放大器等。另外，在布线上也应该注意隔离。

3．SPWM的基本思想是什么？产生SPWM控制信号的方法主要有哪三种？ 答：SPWM的基本思想是：保持输出脉冲电压幅度不变，用调节脉冲的宽度和间隔实现其平均值接近正弦（同时改变U和f）。将此脉冲电压加到电机上，所得到的电流波形接近于正弦波。就硬件方面讲，产生SPWM控制信号的方法主要有三种：
　　（1）采用微处理器。

　　（2）采用专用大规模集成电路。

　　（3）采用微处理器和专用大规模集成电路相结合。

4．常用的隔离方式有哪几种?光电隔离的特点是什么? 答：常用的隔离方式有光电隔离、继电器隔离、变压器隔离、隔离放大器等。光电隔离是以光为媒介传输信号的器件，输入和输出在电气上是完全隔离的。具有较高的电气隔离和抗干扰能力。

5．三相步进电机的工作方式哪几种?其中“单”、“双”、“拍”各是什么意思? 答：三相步进电机一般有单三拍、六拍及双三拍等工作方式。“单”、“双”、“拍”的意思是：“单’’指定子绕组每次切换前后只有一相通电；
“双”指每次有两相定子绕组通电；
“拍”指从一种通电状态转到另一种通电状态。

6．单向晶闸管的导通条件是什么？ 答: 导通条件是指晶闸管从阻断到导通的条件，条件是晶闸管的阳极加上正向电压，同时在门极加上正向电压。晶闸管一旦导通，门极对晶闸管就不起控制作用。

7．什么是直流电动机？它有哪些优点？ 答：直流电动机是一种将直流电转换为机械能的装置，它的最大优点是调速性能好，可以在宽广的范围内实现无级调速；
另外，它的起动转矩大，过载能力强。直流电动机由定子和转子两大部分组成，在定子和转子之间是空气隙。

8．什么是步进电机？ 答：步进电机是一种电磁式增量运动执行元件，它可以将输入的电脉冲信号转换成相应的角位移或直线位移。因输入的是脉冲信号，运动是断续的，又称脉冲电机或阶跃电机。

9．环形分配器的主要功能是什么？ 答：环形分配器的主要功能是把来自变频信号源的脉冲序列按一定的规律分配后，经过功率放大器的放大加到步进电机驱动电源的各项输入端，以驱动步进电机的转动。同时步进电机有正反转的要求，所以这种环形分配器的输出既是周期的，又是可逆的。

三、分析计算题 2、解：不考虑符号，由图1可列出下面的方程 将后两个公式带入第一个公式，可得传递函数为：
四、设计电路 用7805设计一个输出电压为+7V的稳压电路。

请您删除一下内容，O(∩_∩)O谢谢！！！2015年中央电大期末复习考试小抄大全，电大期末考试必备小抄，电大考试必过小抄After earning his spurs in the kitchens of The Westin, The Sheraton, Sens on the Bund, and a sprinkling of other top-notch venues, Simpson Lu fi nally got the chance to become his own boss in November 2010. Sort of. The Shanghai-born chef might not actually own California Pizza Kitchen (CPK) but he is in sole charge of both kitchen and frontof- house at this Sinan Mansions＇stalwart.  “It’s certainly a responsibility to be the head chef, and then to have to manage the rest of the restaurant as well,“ the 31-year-old tells Enjoy Shanghai. “In hotels, for example, these jobs are strictly demarcated, so it’s a great opportunity to learn how a business operates across the board.“  It was a task that management back in sunny California evidently felt he was ready for, and a vote of confi dence from a company that, to date, has opened 250 outlets in 11 countries. And for added pressure, the Shanghai branch was also CPK’s China debut.  “For sure it was a big step, and unlike all their other Asia operations that are franchises, they decided to manage it directly to begin with,“ says Simpson.  Two years ago a private franchisee took over the lease, but the links to CPK headquarters are still strong, with a mainland-based ＇brand ambassador’ on hand to ensure the business adheres to its ethos of creating “innovative, hearth-baked pizzas“, a slice of PR blurb that Simpson insists lives up to the hype.  “They are very innovative,“ he says. “The problem with most fast food places is that they use the same sauce on every pizza and just change the toppings. Every one of our 16 pizza sauces is a unique recipe that has been formulated to complement the toppings perfectly.“  The largely local customer base evidently agrees and on Saturday and Sunday, at least, the place is teeming. The kids-eat-for-free policy at weekends is undoubtedly a big draw, as well as is the spacious second-fl oor layout overlooked by a canopy of green from Fuxing Park over the road.  The company is also focusing on increasing brand recognition and in recent years has taken part in outside events such as the regular California Week. Still, the sta are honest enough to admit that business could be better; as good, in fact, as in CPK’s second outlet in the popular Kerry Parkside shopping mall in Pudong.  “Sinan Mansions has really struggled to get the number of visitors that were envisaged when it first opened, and it hasn’t been easy for any of the tenants here,“ adds Simpson. “We’re planning a third outlet in the city in 2015, and we will probably choose a shopping mall again because of the better foot traffic.“ The tearooms once frequented by Coco Chanel and Marcel Proust are upping sticks and coming to Shanghai, Xu Junqian visits the Parisian outpost with sweet treats. One thing the century-old Parisian tearoom Angelina has shown is that legendary fashion designer Coco Chanel not only had style and glamor but also boasted great taste in food, pastries in particular. One of the most popular tearooms in Paris, Angelina is famous for having once been frequented by celebrities such as Chanel and writer Marcel Proust. Now Angelina has packed up its French ambience, efficient service, and beautiful, comforting desserts and flown them to Shanghai. At the flagship dine-in and take-out space in Shanghai, everything mimics the original tearoom designed from the beginning of the 20th century, in Paris, the height of “Belle Epoque“. The paintings on the wall, for example, are exactly the same as the one that depicts the landscape of southern France, the hometown of the owner; and the small tables are intentional imitations of the ones that Coco Chanel once sat at every afternoon for hot chocolate. The famous hot chocolate, known as L’Africain, is a luxurious mixture of four types of cocoa beans imported from Africa, blended in Paris and then shipped to Shanghai. It’s sinfully sweet, rich and thick as if putting a bar of melting chocolate directly on the tongue and the fresh whipped cream on the side makes a light, but equally gratifying contrast. It is also sold in glass bottles as takeaway. The signature Mont-Blanc chestnut cake consists of three parts: the pureed chestnut on top, the vanilla cream like stuffing, and the meringue as base. Get all three layers in one scoop, not only for the different textures but also various flavors of sweetness. The dessert has maintained its popularity for a century, even in a country like France, perhaps the world’s most competitive place for desserts. A much overlooked pairing, is the Paris-New York choux pastry and N226 chocolate flavored tea. The choux pastry is a mouthful of airy pecan-flavored whipped cream, while the tea, a blend of black teas from China and Ceylon, cocoa and rose petals, offers a more subtle fragrance of flowers and chocolate. Ordering these two items, featuring a muted sweetness, makes it easier for you to fit into your little black dress. Breakfast, brunch, lunch and light supper are also served at the tearoom, “a hub of many cultures“ and takes in “a mix of different styles of French cuisines“, according to the management team. The semi-cooked foie gras terrine, is seductive and deceptive. It’s generously served at the size and shape of a toast, while the actual brioche toast is baked into a curved slice dipped with fig chutney. The flavor, however, is honest: strong, smooth and sublime. And you don’t actually need the toast for crunchiness. This is the season for high teas, with dainty cups of fine china and little pastries that appeal to both visual and physical appetites. But there is one high tea with a difference, and Pauline D. Loh finds out just exactly why it is special. Earl Grey tea and macarons are all very well for the crucial recuperative break in-between intensive bouts of holiday season shopping. And for those who prefer savory to sweet, there is still the selection of classic Chinese snacks called dim sum to satisfy and satiate. High tea is a meal to eat with eye and mouth, an in-between indulgence that should be light enough not to spoil dinner, but sufficiently robust to take the edge off the hunger that strikes hours after lunch. The afternoon tea special at Shang-Xi at the Four Seasons Hotel Pudong has just the right elements. It is a pampering meal, with touches of luxury that make the high tea session a treat in itself. Whole baby abalones are braised and then topped on a shortcrust pastry shell, a sort of Chinese version of the Western vol-au-vent, but classier. Even classier is the dim sum staple shrimp dumpling or hargow, upgraded with the addition of slivers of midnight dark truffles. This is a master touch, and chef Simon Choi, who presides unchallenged at Shang-Xi, has scored a winner again. Sweet prawns and aromatic truffles — what’s not to love? His masterful craftsmanship is exhibited in yet another pastry — a sweet pastry that is shaped to look like a walnut, but which you can put straight into the mouth. It crumbles immediately, and the slightly sweet, nutty morsel is so easy to eat you’ll probably reach straight for another. My favorite is the dessert that goes by the name yangzhi ganlu, or ambrosia from the gods. The hotel calls it chilled mango cream with sago, pomelo and bird’s nest – made with ingredients that resonate with every female soul. It does taste like ambrosia, with the sweet-sour fragrance of the mango forming the first layer of taste and sensation, and the pomelo sacs and sago pearls providing the tactile contrast. The bird’s nest — it’s the ingredient that gilds the lily, since it is supposed to nourish and nurture a perfect complexion. For those unfamiliar with this exotic ingredient, the bird’s nest is not a bundle of twigs, but is, instead, the dried secretion that cave swifts use to build their nest. Technically, it’s bird saliva, but the Chinese believe that it has collagen-boosting properties essential to beauty. To me, it just tastes good, adding a slight gelatinous crunch to the back of the teeth. There is also a baked mushroom puff pastry that includes the highly prized Matsutake or pine mushroom. You also get a choice of teas, but I strongly recommend the aged Pu’er from Yunnan province. It is a mellow tea that will go perfectly with the rich little nuggets, and will warm you up on a cold afternoon. Incidentally, the general guide is green tea such as Longjing or Dragonwell for the hot season, semi-fermented teas like Wu-long or Iron Buddha for autumn, and more warming teas like Pu’er for winter. The Shang-Xi afternoon tea costs 228 yuan ($37) per person, and 388 yuan for the more opule