What are the Applications of Filters?

There are many types of filters, and various filters have different performance characteristics. When selecting a filter, it is usually necessary to consider the actual environment of use and the performance requirements of the customer in order to make a correct, effective and reliable selection.

Filters are classified into analog filters and digital filters. Analog filters are used to process analog or continuous signals, while digital filters are used to process discrete digital signals.

filters

Analog filters can be widely used in distribution networks of industrial, commercial, and institutional groups, such as electric power systems, electrolytic plating enterprises, water treatment facilities, petrochemical enterprises, large shopping malls, and office buildings, precision electronics enterprises, power supply systems in airports/ports, medical institutions, etc.

Communication industry

In order to meet the operational needs of large-scale data center rooms, the capacity of UPS use in the communications power distribution system is rising significantly. According to the survey, the main harmonic source equipment of the communication low-voltage power distribution system is UPS, switching power supply, inverter air conditioner, etc...

Their generated harmonic content is high, and the displacement power factor of these harmonic source equipment is extremely high. Through the use of active filters can improve the stability of the communication system and distribution system, extend the service life of communication equipment and power equipment.

Semiconductor industry

The 3rd harmonic in most semiconductor industries is very serious, mainly because a large number of single-phase rectification equipment is used in the enterprise. 3rd harmonic is a zero-sequence harmonic, which has the characteristic of converging in the neutral line, leading to excessive pressure on the neutral line, and even the phenomenon of firing, which is a great production safety hazard.

Harmonics also cause circuit breaker tripping, delaying production time. 3rd harmonic forms a loop current in the transformer, accelerating the aging of the transformer. Severe harmonic pollution is bound to have an impact on the efficiency and life of equipment in the distribution system.

Petrochemical industry

Due to the production needs, there are a large number of pump loads in the petrochemical industry, and many of them are equipped with inverters. A large number of inverters makes the harmonic content in the distribution system of the petrochemical industry increase greatly.

At present, most of the inverter rectification links are applied 6 pulses to convert AC to DC, so the harmonics generated are mainly the 5th, 7th, and 11th. The main hazard is the harm to the power equipment and the deviation in the measurement. The use of active filters can be a good solution to this problem.

Chemical fiber industry

In order to significantly increase the melting rate and improve the melting quality of glass, as well as to extend the age of the furnace and save energy. The chemical fiber industry often uses electric flux heating equipment, with the help of electrodes to send electricity directly into the fuel-heated glass pool kiln. These devices generate a large number of harmonics, and the spectrum and amplitude of the three-phase harmonics vary relatively widely.

Steel/medium frequency heating industry

Medium frequency furnaces, rolling mills, electric arc furnaces, and other equipment commonly used in the steel industry can have a significant impact on the power quality of the power grid, causing frequent overload protection actions of capacitor compensation cabinets, serious heating of transformers, and power supply lines, a frequent fusing of fuses, etc., and even causing voltage dips and flicker.

Automobile manufacturing industry

The welding machine is an indispensable piece of equipment in the automobile manufacturing industry. Because of the random, rapid, and impact characteristics of the welding machine, the massive use of the welding machine causes serious power quality problems, resulting in unstable welding quality, the high degree of automation of the robot can not work due to voltage instability, and the reactive power compensation system can not be used normally.

DC motor harmonic control

Large DC motor sites need to first convert AC power to DC power through rectification equipment. Since the load capacity of such projects is large, there is serious harmonic pollution on the AC side, causing voltage distortion, which can seriously cause accidents.

The use of automated production lines and precision equipment

In automatic production lines and precision equipment, harmonics can affect their normal use and cause malfunctions in intelligent control systems, PLC systems, etc.

Hospital System

Hospitals have very strict requirements on the continuity and reliability of power supply. The automatic power restoration time for Class 0 places is T≤15S, for Class 1 places is 0.5S≤T≤15S, for Class 2 places is T≤0.5S, and the total harmonic distortion rate of voltage is THDu≤3%. X-ray machines, CT machines, and MRI are loads with extremely high harmonic content.

Theater/Stadium

Thyristor dimming system, large LED equipment, etc. are harmonic sources, which will generate a large number of third harmonics during operation, causing not only low efficiency of power equipment in the distribution system but also causing lighting strobe, producing noise and even malfunctions on communication, cable TV and other weak electrical circuits.

In recent telecommunications equipment and various control systems, digital filters are also extremely widely used, and some of the most successful areas of application are listed here.

Voice processing

Speech processing is one of the earliest applications of digital filters and one of the first areas to promote the development of digital signal processing theory. The field includes five main areas.

First, speech signal analysis. That is the analysis and calculation of waveform characteristics, statistical properties, model parameters, etc. of speech signals.

Second, speech synthesis. That is, the generation of speech using dedicated digital hardware or software running on a general-purpose computer.

Third, speech recognition. i.e., the use of dedicated hardware or computers to recognize what a person is saying, or to identify the person speaking.

Fourth, speech enhancement. That is the extraction of the masked speech signal from noise or interference.

Fifth, speech coding. Mainly used for speech data compression, a series of international standards for speech coding have been established and are used in large quantities for communication and audio processing.

Image processing

Digital filtering techniques are used successfully for restoration and enhancement of still and moving images, data compression, noise and interference removal, image recognition, and laminar X-ray photography, and also for visible image imaging of radar, sonar, ultrasound, and infrared signals.

Within the field of modern communication technology, there is hardly a branch that is not influenced by digital filtering techniques. Source coding, channel coding, modulation, multiplexing, data compression, and adaptive channel equalization are all widely used digital filters, especially in applications such as digital communication, network communication, image communication, and multimedia communication, where it is almost impossible to move an inch without a digital filter. Among them, software radio technology, which is considered to be the future development direction of communication technology, is based on digital filtering technology.

Television, radar

Digital TV instead of analog TV is an inevitable trend. The popularity of high-definition television is just around the corner, with its supporting video disc technology has formed a huge market industry; video phones and conference television products continue to update.

The achievements of video compression and audio compression technology and standardization work contributed to the booming development of the industry in the field of television, and digital filter and its related technology is an important basis for video compression and audio compression technology.

The radar signal occupies a very wide frequency band and the data transmission rate is very high, thus compressing the amount of data and reducing the data transmission rate are the primary problems facing the digital processing of radar signals. Tell the emergence of digital devices to promote the progress of radar signal processing technology.

In modern radar systems, the digital signal processing part is indispensable, because, from signal generation, filtering, and processing to the estimation of target parameters and target imaging display are inseparable from digital filtering technology. Digital filtering of radar signals is one of the very active research areas today. Sonar signal processing is divided into two major categories, namely active sonar signal processing and passive sonar signal processing. Active sonar systems involve many of the same theories and techniques as radar systems.

Music

Digital filters have opened up a new horizon for the field of music. Digital filtering technology has shown great power in editing and synthesizing music signals, as well as adding special effects such as cross-mixing reverberation and chorus to music. Digital filters can also be used for composing, recording and playback, or for restoring the sound quality of old audio tapes, etc.