电力电子系统建模与控制4 - 图文-

1、第4章DC-DC变换器的交流模型4.1 简介 4.1 简介4.1 简介4.1 简介4.1 简介 4.1 简介4.1 简介型:Buck-Boost控制-输出特性Buck-Boost交流等效电路模型4.2 基本的交流建模方法4.2 基本的交流建模方法4.2 基本的交流建模方法(终值=(初始值+(增长时长×(平均斜率(终值=(初始值+(增长时长×(平均斜率4.2 基本的交流建模方法电流波形:4.2 基本的交流建模方法4.2 基本的交流建模方法4.2 基本的交流建模方法4.2 基本的交流建模方法4.2 基本的交流建模方法4.2 基本的交流建模方法4.2 基本的交流建模方法4.2 基

2、本的交流建模方法数,因此该式实际是4.2 基本的交流建模方法4.2 基本的交流建模方法4.2 基本的交流建模方法4.2 基本的交流建模方法4.2 基本的交流建模方法4.2 基本的交流建模方法4.2 基本的交流建模方法4.2 基本的交流建模方法4.2 基本的交流建模方法4.3 反激变换器的小信号建模假定:4.3 反激变换器的小信号建模4.3 反激变换器的小信号建模4.3 反激变换器的小信号建模4.3 反激变换器的小信号建模由电感电压、电流波形:4.3 反激变换器的小信号建模由电容电流、电压波形:4.3 反激变换器的小信号建模4.3 反激变换器的小信号建模4.3 反激变换器的小信号建模dI直流项一

3、阶交流分量(线性分量二阶交流分量(非线性分量4.3 反激变换器的小信号建模4.3 反激变换器的小信号建模二阶交流分量(非线性分量dV直流项一阶交流分量(线性分量由电容平均方程:在静态工作点上进行扰动:整理得:j.Co M 2013年全国各地市中考英语试卷分类解析汇编:单项选择动词时态【2013江苏常州】7.Why are you worried?Im expecting a call from my daughter. She New for three days.A. has gone toB. has been toC. has been inD. has come in【答案】A【解析】

4、本题考查动词时态的用法。has gone to去某地未返回;has been to 曾经去过某地;has been in呆在某地;has come in已进来。由答语前半句“我正期待我女儿来的电话”可知她去纽约还未回来,故选A。【2013湖南娄底】27. What did you do last night?I _TV and read books.A. watchB. watchedC. have watched 【答案】B【解析】考查谓语动词的用法。根据上句中问的是过去时,故答语中也要用过去时,保持上下句的时态一致性,故答案为B。【2013 湖南衡阳】28. Look at these s

5、tamps. I them for five years.Wow, they are wonderful.A. keptB. have keptC. have bought【答案】B【解析】本题考查现在完成时的用法。由for five years可知本题是现在完成时态,且动词需要用持续性动词。故选B。【2013湖北宜昌】29. Do you know who took the students to the old peoples home, Tony?Well, Mr. Smith _.A. tookB. doesC. didD. do【答案】C【解析】考查动词的时态。根据问句中的took可

6、以判断为一般过去时,故回答中用助动词did来替代。所以选择答案C。【2013湖北孝感】36. Id like you to tell me s omething about Shen Nongjia.Im sorry, but neither Jack nor I _ there.A. have beenB. had beenC. have goneD. has gone【答案】A【解析】考查现在完成时的用法。答语意为“对不起,但是杰克和我都没去过那儿。”可知要使用现在完成时。have/has been to+地点,意为“去过某地”,现在已经回来了;have/has goneto+地点,意为“

7、去了某地或在去某地的路上”;答句是neither nor引导的两个并列主语,故选A。【2013湖北襄阳】37. We all went to the cinema except you last night. Why didn't you come?Because I that movie twice.A. have watchedB. had watchedC. was watchingD. would watch【答案】B【解析】选B。考查过去完成时的用法。根据上下文可知:我昨晚不去看电影,是因为我以前看过了。叙述的是“过去的过去”发生的事,故用过去完成时态,选B项。【2013天津

8、】33. Is Tom at home?No, he _ to town.A. has beenB. has goneC. goesD. will go【答案】B【解析】考查动词的时态。Tom在家吗?不在,他已经去镇里了。表“已经去了某地方,现在不在说话者说话的地方”用have/has gone to结构。故选B。【2013四川雅安】13. He for ten years.A. has been marriedB. marriedC. got marriedD. has married 【答案】A【解析】考查非延续性动词的用法。B、C两项,时态不对,可排除;marry是非延续性动词,在现在完

9、成时的肯定句中不能与表示一段时间的状语连用,可排除D项;married可作形容词,意为“结婚的”,所以选择答案A。【2013浙江杭州】22. Sally took a photo of her friends while they _ computer games.A. playB. are playingC. have playedD. were playing【答案】D【解析】本题考查动词的时态。根据句意“塞丽为朋友照相”和下文句意“当他们玩电脑游戏时”可知,两个动作同时发生,while后常接进行时。故选D。【2013重庆】37. It will be hard for us to get

10、 up in the morning if we _to bed too late.B. wentC. will goD. have gone【答案】A【解析】本题考查动词的时态。if引导的条件状语从句,主句用一般将来时,从句用一般现在时态。故选A。【2013重庆】31.Just a minute! My brother _his car in the garden.B. is washingC. washedD. will wash【答案】B解析:本题考查现在进行时态。由前句“等一会儿!”,可推知后句意为“我兄弟正在花园里洗车”,因此用现在进行时态。【2013重庆】27.I called y

11、ou yesterday evening.but you were not in.sorry,I _in the shop with my mother.B.will beC. wasD. have been【答案】C解析:本题考查一般过去时态。由上句“昨天晚上我打电话给你,但是你不在家”,可推知后句意为“对不起,我和我母亲在商店里”,故用一般过去时态。【2013湖南邵阳】30.Do you hear just now?A. what I saidB. what I'm sayingC. what I says【答案】A【解析】考查动词的时态。Just now意为“刚才”,常与一般过去

12、时连用。故选A。【2013 浙江湖州】24. Julia isnt going to the cinema with us because she _ the film.A. seesB. sawC. will seeD. has seen【答案】D【解析】考查动词时态朱丽叶将不去电影院了,因为她看过这部电影了。这表明过去“看”的动作对现在造成了结果,意思指,我现在知道这部电影的内容了,因此用现在完成时,故选D。【2013江苏南京】8. Millie, where is Miss Li? She a speech on Chinese art to the first-year student

13、s in the hall.A. givesB. gaveC. is givingD. has given【答案】C【解析】考查动词的时态用法。由问句“李老师在哪里?”可知应使用现在进行时,表示李老师现在正在做什么,所以选择答案C。【2013浙江绍兴】23.Can Peter play games with us, Mrs. Hawking? Wait a minute. He _a shower.A. is takingB. takesC. tookD. was taking【答案】A【解析】考查现在进行时态用法。根据答语wait a minute可知:“洗澡”这个动作正在进行,而且是在现在

14、的时间,故用现在进行时is taking表示,选A。12【2013江苏连云港】. Julie's father _ to London last month. He _ there three times.A. went; had goneB. has gone; has beenC. went; has beenD. has been; had gone【答案】C【解析】考查动词的时态。根据句意:“上个月朱莉的爸爸去伦敦。他已经去过那里3次了。”,前一句是一般过去时,后一句则是现在完成时,所以选择C。【2013江苏泰州】7. Here comes the bus! Where is

15、our principal? She can't go to the museum with us. She _ some visitors around our school.A. is showingB. showsC. has showedD. was showing【答案】 A【解析】考查动词的时态。由答句中的前句“她不可能与我们一起去博物馆”知,后句意为“她正带领一些参观者参观我们的学校”,因此用现在进行时态,所以选择答案A。【2013四川雅安】17. My sister has learnt English .A. for twelve years agoB. since she was fourC. twelve years agoD. at the age of four【答案】B【解析】考查现在完成时的时间状语。由谓语动词has learnt可知,应用表示一段时间的时间状语,A项表达错误;C、D两项用于一般过去时,所以选择答案B。【2013四川雅安】14. If farmers trees and forests, giant pandas nowhere to live.A. cut down; haveB. will cut down; will haveC. will cut don; haveD. cut