机电传动控制考试题库河南理工大学.doc

In order to ensure normal teaching order, protecting students healthy growth, ensuring that national (property) is not lost, to prevent or minimize the occurrence of safety accidents, follow the prevent, rescue each other, ensure safety and reduce losses principle, according to the local conditions, make the management system. 1, the principal is the responsibility of school safety, school security under the leadership of President security work leading group. The head teacher to the leadership team is responsible for, implementation of the accountability system. 2, school monthly student knowledge about safety education, education should be diversified in the form every safety education for students of classes per week should be targeted. To carry on emergency issues dealing with education in General, self-help and mutual rescue knowledge. Emergency calls (such as 110, 119, 122, 120, and so on) use common sense in education. 3, the establishment of major accident reporting system. School students report major accident within an hour of education; student run and disappearances to report; report of the accident to a written report in triplicate, a correctional centre, a police station, a township peoples Government shall not conceal the accident. 4 week, teachers are on duty system, establish and improve the leadership values; strengthen the education, management of teaching activities in schools to ensure normal teaching order; responsible for school safety leadership always maintained close contact and district police stations, canvassing support from the police station on school safety and help. 5, strengthening teachers moral education, establish a dedicated love, improving education quality, observe the students psychological changes at any time and take preventive measures, no corporal punishment and covert corporal punishment on students, student out of the classroom, schools may not be. 6, units or departments use student Street propaganda or participate in the celebrations, as well as participating in other social work, without approval of the Correctional Centre, school principals consent, without organization. Without the approval of relevant departments, may organize students to participate in fire fighting, disaster relief and so on. 7, schools should educate students to obey the school rules and regulations, on time, on time home to prevent accidents. 8, school to school inspections on a regular basis, found hidden in time, and in severe cases, it is hard to eliminate immediately closed, and reported to the local peoples Government, education, and rule of law section. 9, the school should always check the internal walls, retaining walls, ponds, railings, handrails, doors, Windows, staircases and a variety of sports, extracurricular activities, facilities such as fire safety, infrastructure security, unsafe facility to immediately repair and demolition to ensure that teachers and students work, learn, live venues and facilities are safe and reliable. Song Lin Xiang Liu Jia ping elementary school March 2016 song Lin Xiang Liu Jia ping primary school fire safety systems to enhance fire safety, protection of public property and the life and property safety of teachers and students, school fire safety into day-to-day management, is developing the following fire safety system. 1, strengthen fire safety education of the whole school. According to the requirements of the Fire Services Act, so that everyone has of keeping fire control safety, protecting fire control facilities, fire prevention, reports of fire一、 问答题（回答要点，并简明扼要作解释。每小题4分，共20分）1 有一台三相异步电动机，正常运行时为接法，在额定电压 UN下启动时，其启动转矩Tst=1.2TN(TN为额定转矩)，若采用Y-换接启动，试问当负载转矩TL=35%TN时，电动机能否启动？为什么？采用Y-换接启动时，启动转矩故能够启动。2 试说明下图中几种情况下系统的运行状态是加速？减速？还是匀速？（图中箭头方向为转矩的实际作用方向）图（a）所示为加速 图（b）所示为减速 图（c）所示为减速 图（d）所示为减速3 对电动机的启动转矩有哪些主要要求？启动转矩大，电流小，平滑，安全可靠，简单方便，功耗小4 直流他励电动机启动时，若加上励磁电流前就把电枢电压加上，这时会产生什么后果（试从TL=0和TL=TN两种情况加以说明）？TL=0 时飞车，TL=TN时电枢电流很大。5 单相异步电动机为什么没有启动转矩？常采用哪些方法启动？因为单相交流电产生脉动磁场，不产生旋转磁场，所以，常采用电容分相式和罩极式两种启动方法。6 电流截止负反馈的作用是什么？试画出其转速特性n=f (Ia)，并加以说明；转折点电流I0，堵转电流Ia0，比较电压Ub如何选？作用是当电动机严重过载时，人为地造成“堵转”，防止电枢电流过大而烧坏电动机。转速特性如图所示。I0以前为稳定运行的硬特性区；I0以后为软特性，n迅速下降，而Ia确增加不多，起到了“限流”作用。其中：I0=KIaN=1.35IaN,Ia0=(22.5)IaN,UbKIaNR-Ub07 如下图所示，曲线1和2分别为为电动机和负载的机械特性。试问：电动机能否在A点稳定运行？为什么？能，因为当nnA 时，TMTL;反之当nTL8 有静差调节系统和无静差调节系统的含义是什么？依靠被调量（如转速）与给定量之间的偏差来进行调节，使被调量接近不变，但又必须具有偏差（即U0）的反馈控制系统，即有静差调节系。该系统中采用比例调节器。依靠偏差进行调节，使被调量等于给定量（即U=0）的反馈控制系统，即无静差调节系统。该系统中采用比例积分调节器。9 何谓恒转矩调速和恒功率调速？在调速过程中维持转矩不变的调速，叫恒转矩调速；在调速过程中维持功率不变的调速，叫恒功率调速。10如下图所示，图中各物理量的方向均是实际方向，试在圆内标明哪些作发电机（标G）运行？哪些作电动机（标M）运行？图（a）所示为G 图（b）所示为G 图（c）所示为M 图（d）所示为M12何谓整流器？何谓逆变器？何谓有源逆变器？何谓无源逆变器：试用简单电路图说明无源逆变器的工作原理。将交流电变成直流电的装置，称为整流器，反之称为逆变器；把直流电逆变为同频率的交流电反馈到电网去，称为有源逆变器；把直流电逆变为某一频率或可变频率的交流电供给负载，则称为无源逆变器，无源逆变器的工作原理如下图所示。13为什么直流电动机直接启动电流很大？因U=E+IR，启动时E=0，电枢加上额定电压，而电枢电阻很小，故很大。14积分调节器为什么能消除静态误差？只要系统受到干扰时出现偏差，U0，积分器就开始积分，它的输出使被调量变化，力图恢复受干扰前的数值，当完全恢复后，U=0时，积分调节器能维持此过程中积分的数值，所以可消除静差。15什么叫调速范围？什么叫静差度？这两项静态指之间有何关系？调速范围是指电动机在额定负载下最高转速和最低转速之比，即D=nmax/nmin ；静差率是指负载由理想空载转速到额定负载甩对应的转速降落与理想空载转速之比，即S=n/n0。D与S之间是相互关联的，调速范围是指在最低转速时还能满足给定静差率的转速可调范围；对静差率要求越小，允许的调速范围也越小。16有一台三相异步电动机，正常运行时为接法，在额定电压UN下启动时，其Tst=1.2TN,若采用Y-换接启动，试问当负载转矩TL=45%TN时，电动机能否启动？为什么？采用Y-换接启动时，启动转矩，所以不能启动。17一般同步电动机为什么要采用异步启动法？由于一般同步电动机的电源频率高（f=50Hz）,转子有惯性，来不及被定子的旋转磁场所吸引，所以没有启动转矩。故要采用异步启动法。二、 计算题1 有一直流电动机脉宽调速系统（PWM-M），若外加电压U（E）=100V，脉冲频率f=4000Hz，在脉冲周期内全导通时的理想空载转速n01=1000r/min,如果要求电动机的理想空载转速n02=400r/min,问：此系统在一脉冲周期内的导通时间（脉冲宽度）T1应是多少？因，且即故2有一电炉，其电阻R=14.85，为了调节加热温度，用一只晶闸管控制，供电电路为单相半波可控整流电路，接在电压的交流电源上，试求： 绘出可控整流电路图； 当控制角时，求加在电炉上的电压平均值Ud； 当控制角时，求通过电炉的电流平均值Id。3有台直流他励电动机，其铭牌数据为：。试求： 额定转矩TN； 额定电枢电流IaN； 额定电枢电流时的反电势； 直接启动时的启动电流； 若使启动电流为三倍的额定电流，则电枢应串入多大的启动电阻？此时的启动转矩为多少？因故则 4某一调速成系统在高速时的理想空载转速n01=1450r/min,低速时的理想空载转速n02=100r/min,额定负载时转速降nN=50r/min。 画出该系统的静特性； 求出调速范围D和低速时系统的静差度S2； nmax与S2一定时，扩大调速范围的方法是什么？调速系统中应采取什么措施保证转速的稳定性？由可知，在与一定时，扩大调速范围的方法是减少，调速系统应采用由转速负反馈组成的闭环系统。 5有一直流电动机脉宽调速系统（PWM-M），若外加电源电压U（E）=110V，脉冲频率f=5000Hz,在脉冲周期内全导通时的理想空载转速n01=1600r/min,如要电动机的理想空载转速n02=800r/min,问：此系统在一脉冲周期内的导通时间（脉冲宽度）T1应是多少？因，且即故6某一调速系统在高速时的理想空载转速n01=1850r/min,低速时的理想空载转速n02=150r/min,额定负载时的转速降nN=50r/min.。 求出调速范围D和低速时系统的静差度S2； 写出系统的调范围D、静差度S2，最高转速nmax和转速降nN四者之间的关系； 画出该系统的静特性； 在nmax与S2一定时，扩大调速范围的方法是什么？在与一定时，扩大调速范围的方法是减少7. 有一电阻炉，其电阻R=29.7，为了调节加热温度，用晶闸管组成单相半控桥式可控整流电路控制，接在电压的交流电源上，试求： 绘出可控整流电路图； 当控制角时，求加在电炉上的电压平均值Ud； 当控制角时，求通过电炉的电流平均值Id。8有台直流他励电动机，如图所示，其铭牌数据为：，试求： 额定励磁电流IfN； 励磁功率Pf； 额定转矩TN； 额定电枢电流IaN； 额定电枢电流时的反电势； 直接启动时的启动电流； 若使启动电流为三倍的额定电流，则电枢应串入多大的启动电阻？因故9有一直流电动机脉宽调速系统（PWM-M），若外加电源电压U（E）=220V，脉冲频率f=2000Hz,在脉冲周期内全导通时的理想空载转速n01=900r/min,如要电动机的理想空载转速n02=225r/min,问：此系统在一个脉冲周期内的导通时间（脉冲宽度）T1应是多少？10有一台三相鼠笼式异步电动机，其额定数据为：,接法，试求：额定输入电功率PIN；额定转差率SN；额定电流IN；输出的额定转矩TN；采用Y-换接启动时的启动电流和启动转矩。11电炉的电阻R=18.5,为调节加热温度，用晶闸管组成单相半控桥式可控整注电路控制，接在电压r的交流电源上，试求：绘出可控整流电路图；当控制角时，求加在电炉上的电压平均值Ud；当控制角时，求通过电炉的电流平均值Id。绘出u2、ud、id 、uvs的波形图。12有一台三相鼠笼式异步步电动机，其额定数据为：,接法，试求：6 定子极对数p; 额定输入电功率PIN； 额定转差率SN； 额定电流IN； 输出的额定转矩TN； 采用Y-换接启动时的启动电流和启动转矩。 当负载转矩为30Nm时，该电动机能否采用Y-换接启动。因故能启动 。13有一直流电动机脉宽调速系统（PWM-M），若外加电源电压U（E）=220V，脉冲频率f=4000Hz,在脉冲周期内全导通时的理想空载转速n01=450r/min,如要电动机的理想空载转速n02=45r/min,问：此系统在一脉冲周期内的导通时间（脉冲宽度）T1应是多少？编制本施工方案时，分析了本工程的工程特点，地质条件和设计要求，结合我公司其它工地施工经验及教训，本着创一流的质量Electricity lines, equipment inspections, found hidden in time for rectification, maintenance, and security. 9, do not use an open flame in the classroom, prohibit burning stove, lit candles, mosquito repellent, no smoking, and banning messy wiring. Without using any household appliances is not allowed. 10, live on campus faculty members, must lead by example, and educate families and children ready to fire. 11, household use of gas in schools, to master proper usage, pay attention to the leak-proof, explosion-proof, fireproof, closing valve after use to ensure security. 12, dining room must be qualified, and annual testing of pressure vessels, to regularly check, the canteen workers must be certified, strictly by operation operation, gas tank and stove safety distance of 1.5 meters, to prevent accidents. 13, the adverse consequences caused by ignoring fire safety regulations, will be punished, until investigated for legal responsibility. Song Lin Xiang Liu Jia ping elementary school March 2016 Xiang Liu Jia ping elementary school, pine slopes surrounding safety management system 1 teachers and students, the surrounding area of the school governance covers personal and food hygiene, cultural events and other aspects, integrated governance shall obtain wide support and full cooperation of the community. On the surrounding environment in schools should be closely monitored. 2, school work at the same time, should pay attention to the safety management of school environment, should take the initiative to contact the district police station, the village Committee, Correctional Centre, Township government, business management and other departments to do a good job management. 3, teacher on duty with the exception of inspections in schools, should also pay attention to environmental inspections near the campus, found that the jobless migrants from rural areas, for example, harassment of students and a variety of accidents, according to different situations reported school officials or the police station in a timely manner, to protect the safety of students. 4, every day before school, teachers remind students, pay attention to traffic safety. 5, should educate students to respect social ethics, and various regulations, maintaining public order, and fight the bad guys, and grasp the correct ways and means of maintaining and improving students self-care ability. 6, the establishment of emergency rescue teams of teachers in schools, on high alert and deployed. Song Lin Xiang Liu Jia ping elementary school March 2016 song Lin Xiang Liu Jia ping primary school teachers and students organizations out of