Many people are always confused about the difference between transformer and frequency converter. Today, let's have a look.
Transformer is a device that uses the principle of electromagnetic induction to change AC voltage. The main components are primary coil, secondary coil and iron core (magnetic core). In electrical equipment and wireless circuits, it is often used for voltage rise and fall, impedance matching, safety isolation, etc.
The frequency converter is mainly composed of rectifier (AC to DC), filter, inverter (DC to AC), braking unit, driving unit, detection unit, microprocessor unit, etc. The frequency converter adjusts the voltage and frequency of the output power supply by switching off the internal IGBT, and provides the required power supply voltage according to the actual needs of the motor, so as to achieve the purpose of energy saving and speed regulation. In addition, the frequency converter has many protection functions, such as overcurrent, overvoltage, overload protection, etc. With the continuous improvement of industrial automation, frequency converters have also been widely used.
The main work of transformer is voltage transformation, impedance transformation, isolation, voltage stabilization (magnetic saturation transformer), etc. the commonly used iron core shapes of transformer generally include E-type and C-type iron core. Its principle is simple, but the winding process of transformer will have different requirements according to different applications (different uses). Power transformers are widely used.
The difference between transformer and frequency converter is that frequency converter: through its adjustment, we can achieve the required power frequency (50Hz, 60Hz, etc.) to meet our special needs for power. Transformer: it is generally a "step-down device", which is common near residential areas or factories. Its function is to reduce the ultra-high voltage to the normal power consumption voltage of our residents to meet people's daily power consumption. Transformers have developed many products and functions with different functions according to different use environments!
Complex programmable logic device (CPLD) was developed in the mid-1980s with the continuous improvement of semiconductor component technology and the continuous improvement of user requirements for device integration.
There are many manufacturers of complex programmable logic devices (CPLD), with various varieties and structures, but most of them adopt the following two structures. One is CPLD based on product term. The logic unit of this CPLD follows the product term logic unit structure of simple PLD (pal, gal, etc.). At present, most CPLDs belong to this type.
The logic block in CPLD is similar to a small-scale PLD. Usually, a logic block contains 4 ~ 20 macro units, and each macro unit is generally composed of product term array, product term allocation and programmable registers.
So, what are the application scenarios of complex programmable logic devices?
The emergence of reconfigurable PLD (programmable logic device) based on SRAM (static random access memory) has created conditions for system designers to dynamically change the logic function of PLD in operating circuits.
PLD uses SRAM units to store configuration data. These configuration data determine the interconnection relationship and logic function within the PLD. Changing these data also changes the logic function of the device.
Since the data of SRAM is volatile, these data must be stored in non-volatile memory such as EPROM, EEPROM or Flash ROM other than PLD devices, so that the system can download them to the SRAM unit of PLD at an appropriate time, so as to realize in circuit Reconfigurability (ICR).
Mica capacitor refers to a capacitor with natural mica as the medium in the middle of the capacitor. Its shape is mostly square, with high pressure resistance and good performance. However, due to the influence of dielectric materials, mica capacitors cannot be made too large, and the cost is higher than other capacitors. Its production method is: using metal foil or spraying silver layer on mica sheet as electrode plate, the electrode plate and mica are laminated layer by layer, and then die cast in bakelite powder or sealed in epoxy resin.
The medium of mica capacitor is mica sheet, and the electrode has metal foil type and metal film type. Earlier mica capacitors were made of metal foil or silver sprayed on the surface of mica sheets to form electrodes, and then they were laminated according to the required capacity and then diffusely impregnated and molded in bakelite shell. At present, most of them are coated with a layer of silver electrode on the mica medium, and the core structure is assembled and stacked, and then installed into the shell to form a capacitor. The shell includes taojia shell, metal shell and plastic shell, and plastic shell is commonly used.
The external package of mica capacitor includes sealed mica capacitor and unsealed mica capacitor:
The sealing structure seals the core group in the metal or ceramic shell, and leads out the electrode through the insulator.
The non sealing structure is to embed the core group in the shell of organic polymer resin. The general requirements of the sealing material are: large volume resistance, good high-frequency characteristics, large adhesion with metal, small temperature coefficient, high mechanical strength and good moisture resistance. Most mica capacitors are encapsulated by plastic molding. This method has good moisture resistance and high reliability, and is the main encapsulation method of mica capacitors.
Mica capacitors have the following characteristics:
① The capacity range is not wide, generally between 10~51000pf.
② High stability, high reliability, and can be made into high-precision capacitors.
③ It is one of the high-frequency capacitors with excellent performance because of its small inherent inductance, not easy to aging and stable frequency characteristics.
④ The insulation resistance is high, generally up to 1000 ~ 7500m Ω.
⑤ The temperature characteristic is good, and the ambient temperature is generally within the range of -55 ℃ ~ +85 ℃
⑥ The dielectric loss is small, and the tangent value of loss angle is generally.
⑦ The price is relatively expensive, which has been gradually replaced by ceramic capacitors and organic film capacitors in recent years.
Mica capacitors are suitable for occasions requiring high stability and reliability and high-frequency and high-voltage electronic equipment.
Digital to analog converter is a kind of IC products. Digital to analog converter, also known as d/a converter, referred to as DAC, is a device that converts digital quantity into analog.
A converter is a device that converts one signal into another. Signal is the form or carrier of information. In automatic instrument equipment and automatic control system, one signal is often converted into another signal after comparison with standard quantity or reference quantity, so as to connect the two types of instruments. Therefore, the converter is often the intermediate link between two instruments (or devices).
In the integrated d/a converter, the resistance network is usually used to convert the digital quantity into the analog current, and then the operational amplifier is used to complete the conversion from the analog current to the analog voltage. At present, most d/a conversion integrated circuit chips include these two parts. If only the d/a chip with resistance network is included, it needs to be connected with an external operational amplifier to convert to analog voltage. According to the structure of resistance network, it can be divided into weighted resistance network DAC, T-shaped resistance network DAC, inverted T-shaped resistance network DAC, weighted current DAC and other forms.
The d/a converter is to convert the digital quantity d into the analog quantity V proportional to it, that is, v= R × D. Where R is the scale factor. The circuit forms of d/a digital to analog converter are various, and most of them use T-type resistance decoding network. Now the working principle is explained by the digital to analog conversion circuit of three bit binary number. Generally speaking, the output voltage is linearly proportional to the binary number D. By adjusting the feedback resistance R0 and the reference voltage Vref of the operational amplifier, the output voltage V that is linearly proportional to the n-bit binary number can be obtained.
The function of a/d conversion is to convert time continuous and amplitude continuous analog signals into time discrete and amplitude discrete digital signals. Therefore, a/d conversion generally goes through four processes: sampling, holding, quantization and coding. In actual circuits, some of these processes are combined. For example, sampling and holding, quantization and coding are often implemented simultaneously in the conversion process.
Capacitors are energy storage elements used in circuits for tuning, filtering, coupling, bypass, energy conversion, and delay. Capacitors are often called capacitors. According to its structure, it can be divided into three types: fixed capacitor, semi-variable capacitor and variable capacitor.
Solid aluminium electrolytic capacitor is short for conductive polymer solid aluminium electrolytic capacitor, and is one of the highest-grade products in capacitor products.
ESR (Equivalent Series Resistance) refers to the series equivalent resistance, which is an important indicator of capacitance. The lower the ESR, the faster the charge and discharge of capacitance. This performance directly affects the decoupling performance of power supply circuit of microprocessor. The advantage of low ESR of solid-state electrolytic capacitance in high frequency circuit is more obvious.
It can be said that the low ESR characteristics at high frequencies are the watershed between the performance differences of solid electrolytic capacitance and liquid capacitance. The ESR of solid-state aluminium electrolytic capacitance is very low, with very small energy dissipation. The very low ESR characteristic of the solid state capacitor under high temperature, high frequency and high power conditions can fully absorb the high amplitude voltage generated between the power cords in the circuit and prevent its interference to the system.
Currently, the power consumption of the CPU is very large, the main frequency is far beyond 1GHz, the peak current of the CPU reaches 80A or more, and the output filter capacitance is close to the critical point of operation. On the other hand, CPUs work in a variety of modes, most of the time in the process of working mode conversion. When the CPU changes from a low power state to a full load state, the large amount of energy required for instantaneous (generally less than 5ms) switching of this CPU comes from the capacitance in the CPU power supply circuit. At this time, the high-speed charging and discharging characteristics of the solid state capacitor can output the high peak current instantaneously, ensuring adequate power supply and ensuring the stable operation of the CPU.
The so-called CBB capacitor, we usually refer to the capacitor mainly made from metallized polypropylene film. There are many kinds of capacitors, such as CBB21, CBB22, CBB20, CBB81, CBB13, MMKP82, CBB60, etc. What are the advantages of CBB film capacitor and what are its common functions?
So what are the common CBB capacitors?
CBB20 axial capacitor, generally with flat circular or cylindrical appearance, is a kind of capacitor using metallized polypropylene film as dielectric and electrodes, wrapped with flame retardant tape and sealed with epoxy resin. It is suitable for AC and DC circuits of instruments, instrumentation, household appliances, etc. It is widely used in crossover lines of audio systems. For example, axial capacitors are often used in many microphones and audio systems, and also in some ultrasonic masks.
CBB21 and CBB22 metallized polypropylene film capacitors. CBB21 is different from CBB22 in the past. CBB21 cannot be used in high frequency circuits, but now material technology has made great progress. CBB21 and CBB22 capacitors have no difference. This is a film capacitor with metallized polypropylene film as dielectric and electrode, epoxy resin sealed film capacitor, and also a film capacitor with the largest usage in film capacitor.
CBB22 thin film capacitor, CBB21/22 capacitor usage is particularly large, it is widely used in instruments, instrumentation, TV and home appliances lines for DC pulse, pulse, and AC voltage reduction, especially for various types of energy-saving lamps and electronic rectifiers.
MMKP82 capacitor, MMKP82 is a double-sided metallized polypropylene film capacitor, because it uses double-sided steamed film, so it has smaller volume than CBB81 capacitor, the two functions are exactly the same, but the capacity of MMKP82 is smaller, more resistant to high temperature and humidity environment.
