What is an inverter?
An inverter is a device that converts direct or alternating current into alternating current with adjustable frequency and voltage.
Working principle of inverter
- The basic working principle of the inverter is also quite simple. First, a single-phase or three-phase AC power source is rectified and filtered into a flat DC power source. This stage is performed by a diode bridge rectifier and a capacitor. As a result, the cosphi power factor of the inverter system is independent of the load and has a value of at least 0.96. This DC voltage is converted (reversed) into a symmetrical 3-phase AC voltage. This stage is currently done through the IGBT (isolated gate bipolar transistor) system by pulse width modulation (PWM). Thanks to the advancement of microprocessor technology and current power semiconductor technology, the pulse switching frequency can reach the ultrasonic frequency range to reduce motor noise and reduce the loss on the motor iron core.
- The 3-phase AC output voltage system can change the amplitude and frequency values steplessly depending on the controller. Theoretically, there is a certain rule between frequency and voltage depending on the control mode. For loads with constant torque, the voltage-frequency ratio is constant. However, for pump and fan loads, this rule is a quaternary function. Voltage is a quaternary function of frequency. This results in a torque characteristic that is a quadratic function of speed suitable for the pump/fan load requirements since the torque itself is a quadratic function of voltage.
- The power conversion efficiency of the inverters is very high because of the use of power semiconductor components manufactured according to modern technology. As a result, the energy consumed is approximately equal to the energy required by the system.
- In addition, today’s inverters have integrated many different types of control suitable for most different types of loads. Nowadays, the inverter has integrated PID unit and is suitable for many different communication standards, very suitable for control and monitoring in SCADA system.
Advantages of Inverters
Today, inverters are no longer an expensive luxury only available to businesses with abundant financial resources, the benefits that inverters bring to you far outweigh the costs you have to pay. Therefore, inverters are gradually becoming indispensable equipment in every factory. The benefits of using an inverter include
+ Change the motor speed flexibly, meeting technology requirements.
+ Efficiently save energy, protect electrical equipment in the same system.
+ Protect the engine, reduce mechanical wear.
+ Increase production efficiency and productivity.
THE POPULAR INVERTER BRAND CURRENTLY
1. Inverter made in Europe
- ABB Inverters: established in 1988 in Zurich, Switzerland. ABB is one of the popular inverter brands. Currently, ABB operates in 5 fields: electrical equipment, power system, automation and transmission, process automation and low voltage electrical equipment.
- Siemens Inverters: Established in 1847 in Berlin – Germany, Siemens is a global electrical and electronic technology corporation. Siemens operates in more than 200 countries and focuses on the fields of electrification, automation and digitalisation.
- SCHNEIDER Inverter: is a series of inverters of French origin, with factories in France, China and Indonesia, this is one of the most popular European brand inverter lines market today.
- DANFOSS Inverter: is a series of inverters of Danish origin, with outstanding waterproof index, manufactured in Denmark and China.
2. Inverter made in Japan
Some Japanese inverter manufacturers such as Yaskawa, Mitsubishi, FuJi, Panasonic, Hitachi, Toshiba… are manufactured in Japan and China. Although Japanese inverter companies are quite expensive, they are trusted by good quality, stable operation, especially some types with specialized functions.
3. Inverter made in Korea
The popular Korean manufacturer of inverters in market today is LS. This inverter has a relatively low cost compared to Japanese and European inverter.
4. Inverter made in Taiwan
Typical representatives of inverters from Taiwan are Delta and Shihlin. These are two quite popular inverter lines in market, manufactured in Taiwan and China.
5. Inverter made in China
In the past, Chinese inverters were often equated with low-quality, low-priced goods. However, with the development of modern technology and investment in research and development, the quality of Chinese inverters today is not inferior to other brands. There are many Chinese inverter series such as INVT, Sumo, Inovance, Veichi, Sinee, Gtake, ENC, Powtran, Alpha, Sunfar, Rexrorth, Lion, Hedy, Saj, Chziri, Micno, Chinsc, Senlan… average to very cheap.
