1、什么是变频器？编辑本段回目录
变频器一般是利用电力半导体器件的通断作用将工频电源变换为另一频率的电能控制装置。
2、PWM和PAM的不同点是什么？编辑本段回目录
PWM是英文Pulse Width Modulation(脉冲宽度调制)缩写，按一定规律改变脉冲列的脉冲宽度，以调节输出量和波形的一种调值方式。
PAM是英文Pulse Amplitude Modulation (脉冲幅度调制) 缩写，是按一定规律改变脉冲列的脉冲幅度，以调节输出量值和波形的一种调制方式。
3、电压型与电流型有什么不同？编辑本段回目录
变频器的主电路大体上可分为两类：电压型是将电压源的直流变换为交流的变频器，直流回路的滤波是电容；电流型是将电流源的直流变换为交流的变频器，其直流回路滤波石电感。
4、为什么变频器的电压与电流成比例的改变？编辑本段回目录
异步电动机的转矩是电机的磁通与转子内流过电流之间相互作用而产生的，在额定频率下，如果电压一定而只降低频率，那么磁通就过大，磁回路饱和，严重时将烧毁电机。因此，频率与电压要成比例地改变，即改变频率的同时控制变频器输出电压，使电动机的磁通保持一定，避免弱磁和磁饱和现象的产生。这种控制方式多用于风机、泵类节能型变频器。
5、电动机使用工频电源驱动时，电压下降则电流增加；对于变频器驱动，如果频率下降时电压也下降，那么电流是否增加？
频率下降（低速）时,如果输出相同的功率,则电流增加,但在转矩一定的条件下,电流几乎不变。
6、采用变频器运转时，电机的起动电流、起动转矩怎样？
采用变频器运转，随着电机的加速相应提高频率和电压，起动电流被限制在150%额定电流以下(根据机种不同，为125%~200%)。用工频电源直接起动时，起动电流为6~7倍，因此，将产生机械电气上的冲击。采用变频器传动可以平滑地起动(起动时间变长)。起动电流为额定电流的1.2~1.5倍，起动转矩为70%~120%额定转矩；对于带有转矩自动增强功能的变频器，起动转矩为100%以上，可以带全负载起动。
7、V/f模式是什么意思？
频率下降时电压V也成比例下降，这个问题已在回答4说明。V与f的比例关系是考虑了电机特性而预先决定的，通常在控制器的存储装置（ROM）中存有几种特性，可以用开关或标度盘进行选择
8、按比例地改V和f时，电机的转矩如何变化？
频率下降时完全成比例地降低电压，那么由于交流阻抗变小而直流电阻不变，将造成在低速下产生地转矩有减小的倾向。因此，在低频时给定V/f,要使输出电压提高一些,以便获得一定地起动转矩,这种补偿称增强起动。可以采用各种方法实现,有自动进行的方法、选择V/f模式或调整电位器等方法
9、在说明书上写着变速范围60~6Hz，即10：1，那么在6Hz以下就没有输出功率吗？
在6Hz以下仍可输出功率，但根据电机温升和起动转矩的大小等条件，最低使用频率取6Hz左右，此时电动机可输出额定转矩而不会引起严重的发热问题。变频器实际输出频率（起动频率）根据机种为0.5~3Hz.
10、对于一般电机的组合是在60Hz以上也要求转矩一定，是否可以？
通常情况下时不可以的。在60Hz以上（也有50Hz以上的模式）电压不变，大体为恒功率特性，在 高速下要求相同转矩时，必须注意电机与变频器容量的选择。
11、所谓开环是什么意思？
给所使用的电机装置设速度检出器（PG），将实际转速反馈给控制装置进行控制的，称为“闭环 ”，不用PG运转的就叫作“开环”。通用变频器多为开环方式，也有的机种利用选件可进行PG反馈.
12、实际转速对于给定速度有偏差时如何办？
开环时，变频器即使输出给定频率，电机在带负载运行时，电机的转速在额定转差率的范围内（1%~5%）变动。对于要求调速精度比较高，即使负载变动也要求在近于给定速度下运转的场合，可采用具有PG反馈功能的变频器（选用件）。
13、如果用带有PG的电机，进行反馈后速度精度能提高吗？
具有PG反馈功能的变频器，精度有提高。但速度精度的植取决于PG本身的精度和变频器输出频率的分辨率。
14、失速防止功能是什么意思？
如果给定的加速时间过短，变频器的输出频率变化远远超过转速（电角频率）的变化，变频器将因流过过电流而跳闸，运转停止，这就叫作失速。为了防止失速使电机继续运转，就要检出电流的大小进行频率控制。当加速电流过大时适当放慢加速速率。减速时也是如此。两者结合起来就是失速功能。
15、有加速时间与减速时间可以分别给定的机种，和加减速时间共同给定的机种，这有什么意义？
加减速可以分别给定的机种，对于短时间加速、缓慢减速场合，或者对于小型机床需要严格给定生产节拍时间的场合是适宜的，但对于风机传动等场合，加减速时间都较长，加速时间和减速时间可以共同给定。
16、什么是再生制动？
电动机在运转中如果降低指令频率，则电动机变为异步发电机状态运行，作为制动器而工作，这就叫作再生（电气）制动。
17、是否能得到更大的制动力？
从电机再生出来的能量贮积在变频器的滤波电容器中，由于电容器的容量和耐压的关系，通用变频器的再生制动力约为额定转矩的10%~20%。如采用选用件制动单元，可以达到50%~100%。
18、请说明变频器的保护功能?
保护功能可分为以下两类：
（1） 检知异常状态后自动地进行修正动作，如过电流失速防止，再生过电压失速防止。
（2） 检知异常后封锁电力半导体器件PWM控制信号，使电机自动停车。如过电流切断、再生过电压切断、半导体冷却风扇过热和瞬时停电保护等。
19、为什么用离合器连续负载时，变频器的保护功能就动作？
用离合器连接负载时，在连接的瞬间，电机从空载状态向转差率大的区域急剧变化，流过的大电流导致变频器过电流跳闸，不能运转。
20、在同一工厂内大型电机一起动，运转中变频器就停止，这是为什么？
电机起动时将流过和容量相对应的起动电流，电机定子侧的变压器产生电压降，电机容量大时此压降影响也大，连接在同一变压器上的变频器将做出欠压或瞬停的判断，因而有时保护功能（IPE）动作，造成停止运转。
21、什么是变频分辨率？有什么意义？
对于数字控制的变频器，即使频率指令为模拟信号，输出频率也是有级给定。这个级差的最小单位就称为变频分辨率。
变频分辨率通常取值为0.015~0.5Hz.例如，分辨率为0.5Hz，那么23Hz的上面可变为23.5、24.0 Hz，因此电机的动作也是有级的跟随。这样对于像连续卷取控制的用途就造成问题。在这种情况下，如果分辨率为0.015Hz左右，对于4级电机1个级差为1r/min 以下，也可充分适应。另外，有的机种给定分辨率与输出分辨率不相同。
22、装设变频器时安装方向是否有限制。
变频器内部和背面的结构考虑了冷却效果的，上下的关系对通风也是重要的，因此，对于单元型在盘内、挂在墙上的都取纵向位，尽可能垂直安装。
23、不采用软起动，将电机直接投入到某固定频率的变频器时是否可以？
在很低的频率下是可以的，但如果给定频率高则同工频电源直接起动的条件相近。将流过大的起动电流（6~7倍额定电流），由于变频器切断过电流，电机不能起动。
24、电机超过60Hz运转时应注意什么问题？ 超过60Hz运转时应注意以下事项
(1)机械和装置在该速下运转要充分可能（机械强度、噪声、振动等）。
（2） 电机进入恒功率输出范围，其输出转矩要能够维持工作（风机、泵等轴输出功率于速度的立方成比例增加，所以转速少许升高时也要注意）。
(3) 产生轴承的寿命问题，要充分加以考虑。
（4） 对于中容量以上的电机特别是2极电机，在60Hz以上运转时要与厂家仔细商讨。
25、变频器可以传动齿轮电机吗？
根据减速机的结构和润滑方式不同，需要注意若干问题。在齿轮的结构上通常可考虑70~80Hz为最大极限，采用油润滑时，在低速下连续运转关系到齿轮的损坏等。 26、变频器能用来驱动单相电机吗？可以使用单相电源吗？
机基本上不能用。对于调速器开关起动式的单相电机，在工作点以下的调速范围时将烧毁
辅助绕组；对于电容起动或电容运转方式的，将诱发电容器爆炸。变频器的电源通常为3相，但对于小容量的，也有用单相电源运转的机种。
27、变频器本身消耗的功率有多少？
它与变频器的机种、运行状态、使用频率等有关，但要回答很困难。不过在60Hz以下的变频器效率大约为94%~96%，据此可推算损耗，但内藏再生制动式（FR-K）变频器，如果把制动时的损耗也考虑进去，功率消耗将变大，对于操作盘设计等必须注意。
28、为什么不能在6~60Hz全区域连续运转使用？
一般电机利用装在轴上的外扇或转子端环上的叶片进行冷却，若速度降低则冷却效果下降，因而不能承受与高速运转相同的发热，必须降低在低速下的负载转矩，或采用容量大的变频器与电机组合，或采用专用电机。
29、使用带制动器的电机时应注意什么？
制动器励磁回路电源应取自变频器的输入侧。如果变频器正在输出功率时制动器动作，将造成过电流切断。所以要在变频器停止输出后再使制动器动作。
30、想用变频器传动带有改善功率因数用电容器的电机，电机却不动，清说明原因
变频器的电流流入改善功率因数用的电容器，由于其充电电流造成变频器过电流(OCT),所以不能起动，作为对策，请将电容器拆除后运转，甚至改善功率因数，在变频器的输入侧接入AC电抗器是有效的。
31、变频器的寿命有多久？
变频器虽为静止装置，但也有像滤波电容器、冷却风扇那样的消耗器件，如果对它们进行定期的维护，可望有10年以上的寿命。
32、变频器内藏有冷却风扇，风的方向如何？风扇若是坏了会怎样？
对于小容量也有无冷却风扇的机种。有风扇的机种，风的方向是从下向上，所以装设变频器的地方，上、下部不要放置妨碍吸、排气的机械器材。还有，变频器上方不要放置怕热的零件等。风扇发生故障时，由电扇停止检测或冷却风扇上的过热检测进行保护 33、滤波电容器为消耗品，那么怎样判断它的寿命？
作为滤波电容器使用的电容器，其静电容量随着时间的推移而缓缓减少，定期地测量静电容量，以达到产品额定容量的85%时为基准来判断寿命。
34、装设变频器时安装方向是否有限制。
应基本收藏在盘内，问题是采用全封闭结构的盘外形尺寸大，占用空间大，成本比较高。其措施有：
（1）盘的设计要针对实际装置所需要的散热；
（2）利用铝散热片、翼片冷却剂等增加冷却面积；
（3） 采用热导管。
此外，已开发出变频器背面可以外露的型式。
35、想提高原有输送带的速度，以80Hz运转，变频器的容量该怎样选择？
设基准速度为50Hz,50Hz以上为恒功率输出特性。像输送带这样的恒转矩特性负载增速时，容量 需要增大为80/50≈1.6倍。电机容量也像变频器一样增大
1, what is transducer? Transducer is the use of power semiconductor devices will be the role of off-frequency power conversion for another frequency energy control devices.
2, PWM and Pam different points? English Pulse Width Modulation PWM (pulse width modulation) used by some of the pulse width is changed pulse to regulate the export volume and a tone waveform value. English Pulse Amplitude Modulation Pam (pulse rate modulation) acronym is based on a law change in the pulse rate pulse to regulate the export of money and a waveform modulation.
3, voltage-and current-what different? Transducer main circuit could be roughly divided into two categories : voltage-voltage sources will be used to exchange transducer DC, the DC circuit is the filter capacitance; Current model is the DC current source of the transducer used for the exchange, the DC circuit filter stone inductance.
4, why transducer voltage and current proportional to the change? Asynchronous motor is the torque rotors of electrical and the magnetic flux flowing currents arising from the interaction between the rated frequency, but only if the voltage will lower frequency, then the magnetic flux on a large magnetic circuit saturation, will be seriously burned electrical. Thus, the frequency and voltage proportional to change, and change frequency transducer output voltage control, so that the magnetic flux maintain a certain electric motors, magnetic saturation and avoid weak magnetic phenomena. This means more control for the air-compressors, the largest energy-based transducer.
5, the use of the frequency power-driven electric motors, voltage drop, current increase; The transducer-driven, if the frequency has decreased, voltage drop, then the current is increased? Declining frequency (low-speed), if the same power output, the current increase in torque certain conditions, currents virtually unchanged.
6, a transducer operation, the start-up electrical currents, activation torque? Using transducer operation, with the acceleration of the electrical voltage and higher frequency, start-up current is limited to 150% rated current of the following (based on the different types of aircraft for 125%~200%). Using frequency power directly start, the start-up current for 6~7 times, and therefore will have a mechanical, electrical shocks. Transducer transmission can be used to smooth start (start time change long). Start-up current for the rated current 1.2~1.5 times for the start torque 70%~120% rated torque; With enhanced functions for the automatic torque transducer, up to 100% more torque, can bring the whole load up.
7, V/f model mean? Frequency, voltage drop V is proportional decline in answering this question has 4 statement. V f ratio relations with the electrical characteristics and is considered a pre-determined, usually in controller memory devices (ROM), a number of characteristics can be used for switching or an offer choice
8, V and f proportional to change, the torque changes in the electrical? Frequency fully proportional reduction in voltage, then the exchange impedance smaller and DC resistance unchanged, would have resulted in low-speed, and torque is reduced tendency. Therefore, when given in low frequency V/f, for export to some voltage, in order to obtain a start-up torque, such as enhanced compensation package. Can use various methods to achieve, the automatic methods, models or choose V/f adjustment potentiometer method
9, the specification asks gear shift in the scope 60~6Hz, 10:1, then there is no output in the following 6Hz? 6Hz still in the following output, but according to the size of the electrical Wensheng and start-up torque conditions, the minimum frequency for 6Hz about this exportable rated torque electric motors and the heat will not cause serious problems. Transducer actual output frequency (frequency start) According to 0.5~3Hz aircraft.
10, the portfolio is in the general electrical 60Hz above also requires a certain torque, can? Under normal circumstances, no. In 60Hz above (a 50Hz above model) voltage unchanged, largely to hang power characteristics in the same high-speed, torque requirements, it should be noted that the electrical and transducer capacity choices.
11, called the Central mean? Electrical devices used to speed up departure clearance vehicles (PG), the actual rotational speed control devices to control the feedback, known as "loop" Needless PG functioning on called "open link". Central to the more generic transducer, and some types of aircraft can use the pieces for PG feedback.
12, the actual rotational speed for a given rate of error, how do? Central opened, transducer output even given frequency electrical operation in a load, the electrical rated to guide the rotational speed in the context of (1%~5%) change. The relatively high precision for governor, even load changes also required to set the pace in the near occasion of the operation, could function with PG feedback transducer (choose pieces).
13, with a PG if the electrical, after feedback to improve the accuracy rate? With PG feedback functions transducer, accuracy is improved. However, the speed depends on the accuracy of Mr PG own accuracy and transducer output frequency resolution.
14, stall prevent functional mean? If given a short time to accelerate, transducer frequency changes far exceeds the output rotational speed (Mar angular frequency) changes transducer will be a flow of electric current and Tiaozha, stop functioning, which is called stall. To prevent stall for electrical continue to operate, we must departure clearance current size frequency control. When excessive speed up current accelerated rate due to slow. Slowdown, as well. Taken together to stall functions.
15, respectively, to accelerate time to time with the slowdown of the aircraft, and processing time slowdown common given aircraft, the meaning? Slowdown were to be added to the aircraft for a short time to accelerate and slow slowdown occasions, or for small machine tools needed to set strict time production rhythms occasion is appropriate, but for air-compressors transmission, and so on, the slowdown has had a longer time to accelerate and slow down time to time can be common.
16, what is renewable braking? Electric motors in order to reduce the frequency of operation, if, asynchronous electric motors into generators of operation as brakes work, which is called regeneration (Electric) braking.
17, the availability of greater power system? Electrical energy from renewable piling up in the filter capacitor transducer, the condenser capacity and impatient relationship to the transducer about renewable power system rated torque of 10%~20%. If a choice of brake modules can reach 50%~100%.
18, please indicate the transducer protection function? Protection functions can be divided into the following two categories : (1) After the state prosecution is automatically amended unusual movements, such as the current stall prevention, renewable overpotential stall prevention. (2) after the embargo was found that the power semiconductor devices PWM控制 signal to the electrical automatically. As a current cut, cut renewable overpotential, and instantaneous power semiconductor cooling fans overheating protection. 19, by using a load why, transducer protection functions movements? Using weak link load, in the instant connectivity, electrical transferred from the empty state to guide large regional drastic changes, a large electric current to flow transducer Guo current Tiaozha not functioning.
20, in the same factory in moving large Electrical and functioning transducer on the end, which is why? Electrical will start flowing and capacity relative to the start-up current, the electrical stator side of the transformers have a voltage drop, the electrical capacity at the big impact is large Yajiang connecting transformer in the same transducer will make Qianya or correct judgement stopped, and thus sometimes protection functions (IPE) movements, causing cessation of operation.
21, what frequency conversion resolution? What is the significance? For digital control of the transducer, even instructions for the frequency analog signal, and the output frequency is a class given. The reason for the smallest unit known as the frequency conversion resolution. Frequency conversion resolution usually Quzhi for 0.015~0.5Hz. For example, the resolution of 0.5Hz, then the above 23Hz may become 23.5, 24.0 Hz, and therefore there is a level of electrical movements follow. For such uses as a control on Juanqu cause problems. Under these circumstances, if a resolution of 0.015Hz for about one in four low-level electrical 1r/min for the following can be fully adapted. In addition, some types of aircraft to the resolution and output resolution will not be the same.
22, installation, the installation directions are restricted transducer. Transducer internal and back into the structure of the cooling effect, on the relationship of ventilation is important, therefore, in order for the type of unit, is hanging on the wall to the vertical spaces, the installation of vertical as possible.
23, not a soft start to the electrical directly into a fixed frequency transducer, the possibility? At low frequencies, can, but if given the frequency with the frequency of high-power direct start-up conditions similar. Will be too great start currents (6~7 times rated current), as a current transducer cut, the electrical is not up. 24, electrical attention over what should be 60Hz operation? More than attention to the following matters should be 60Hz operation (1) machinery and equipment in the speed of operation to be fully possible (mechanical strength, noise, vibration, etc.). (2) electrical power export to hang scope, the output torque to be able to maintain (air-compressors, pumps, etc. axle output proportional to the increase in speed meters, a rise, but also pay attention to the rotational speed). (3) have the life expectancy of bearings, to be fully considered. (4) For more electrical capacity, especially two very electrical, 60Hz operation to be more careful with the manufacturers to discuss.
25, transducer can turn electrical transmission? According to the slowdown in the structure and provide lubrication differently, a number of issues that require attention. In turn, the structure is usually the biggest limit to be considered 70~80Hz using oil lubricant, under continuous operation at low speed to gear damage.
26, transducer can be used to drive single-phase electrical? The use of power alone can? Basically, not machines. The governor of the electrical switching start-style single in the scope of work is the governor will be burned Auxiliary winding; Capacitance or capacitance to start operation mode will trigger capacitor explosions. Transducer 3 of the power normally, but the capacity for small, single-phase power is also useful functioning aircraft.
27, the transducer itself consumption power? Transducer with the aircraft, operation or use of the frequency, but very difficult to answer. But in the transducer efficiency approximately 60Hz 94%~96%, which may projected depletion, but containing renewable braking Type (FR-K) transducer, if the loss is taken into account braking, power consumption will become large, the operation of plate design must pay attention.
28, why can not 6~60Hz region-wide continuous operation? General electrical equipment used in the axial rotors, fan - or part of the leaves for cooling, if the lower speed cooling down effect, and thus can not afford high-speed operation with the same heat, the need to reduce the load of low-speed torque, or a large capacity and electrical transducer combinations, or use dedicated electrical.
29, the electrical brakes should be used to bring attention to? Brakes exciter circuit power should be drawn from transducer input side. If the transducer is exporting power, brakes moves will result in a current cut off. Therefore, we must stop exporting after the brakes in transducer moves.
30, want to use transducer transmission with power factor improvement in the electrical capacitor, the electrical is not moving, clear reasons Transducer into the current improvement in the power factor capacitor, because of their charging currents caused by current transducer (Oct), so we can not start as a response to the request capacitor removed after operation, and even improve the power factor in the transducer input AC power to resist lateral access devices to be effective.
31, transducer of a lifetime? Transducer is for static devices, but also as filter capacitor, cooling fans, consumption device, if they carry out regular maintenance, is expected to have more than 10 years of life.
32, a transducer containing cooling fans, wind direction? If the fans will be bad? For small capacity is the availability of cooling fans in the aircraft. There are fans of aircraft, the wind direction from the upward, the installation transducer place, and placed an image not smoking, exhaust mechanical equipment. Also, the transducer placed directly to heat parts. Fan malfunction, or by electric fans cooling fans to stop testing the 33% detection protection, filter capacitor for consumables, how to judge its life? Capacitor used as a filter capacitor, the electrostatic capacity over time and slowly decreased, regularly measuring electrostatic capacity to meet product of the rated capacity of 85% for the benchmark to judge life.
34, installation, the installation directions are restricted transducer. Collections in order to be fundamental, is a closed structure of the whole big plate outside dimensions, occupying a large space, the cost higher. The measures are : (1) offers practical devices designed to address the needs of heat release; (2) using aluminium heat release films, film cooling agent wing increase cooling area; (3) using hot catheter. In addition, the body can develop a transducer back patterns.
35, to enhance the existing conveyor speed to 80Hz operation, the capacity of the transducer how to choose? Located above the base rate for 50Hz,50Hz to hang power output characteristics. Hang torque characteristics such as travel load growth, the need for increased capacity for 80/50 ≈ 1.6 times. Electrical capacity is also increased, as transducer
