The low-voltage inverter is low voltage AC inverter with adjustable output frequency lower than 690V voltage level.
Sinusoidal pulse width modulation (SPWM) is characterized by simple control circuit structure, low cost, and good mechanical properties and hardness, which can meet the requirements of smooth speed regulation of general transmission, and has been widely used in various fields of the industry. However, at low frequency, due to the low output voltage, the torque is significantly affected by the voltage drop of stator resistance, so that the maximum output torque decreases.
Voltage space vector (SVPWM), which is based on the overall generation effect of three-phase waveform, generates a three-phase modulation waveform at one time with the purpose of approaching the ideal circular rotating magnetic field track of the motor air gap and is controlled by approximating the circle by cutting polygons. After practice, it is improved, that is, frequency compensation is introduced to eliminate the error of speed control. The amplitude of flux is estimated by feedback to eliminate the influence of stator resistance at low speed. The output voltage and current are closed loop to improve dynamic accuracy and stability.
Direct torque control (DTC) method this technology to a large extent solves the above vector control deficiencies and has been rapidly developed with novel control ideas, concise and clear system structure, and excellent dynamic and static performance. At present, this technology has been successfully applied in the high-power ac drive of electric locomotive traction.
Matrix ac-ac control mode VVVF frequency conversion, vector control frequency conversion and direct torque control frequency conversion are all one of ac-dc frequency conversion. A selection of low voltage ac drives are offered at the variable frequency drive China Manufacturer, micnodrive.com.
The energy saving principle of low frequency inverter mainly includes the following: frequency conversion energy saving, power factor compensation energy saving and soft start energy saving.
In the application field, low voltage converter has been used in all walks of life in the world, such as metallurgy, chemical industry, paper making, machinery and other industries. Specific application is more extensive, small applications such as all walks of life blower, conveyor, feeder, mixer, grinding machine, grinder, paper cutter, calender, extruder, valve, compressor, cooling step, plastic machinery, elevator, all kinds of textile industry; Large application fields such as paper mill machine, mold factory injection molding machine, metallurgical mill rolling mill, as well as the chemical industry, such as fan, water pump, crane, pipeline and so on.
The application of low voltage drives in chemical, stone and textile industries varies greatly, and corresponding users can be found in products of various grades in these industries. Therefore, chemical, stone and textile industries are the most complex industries for low voltage ac inverters, and almost all brands have markets in chemical, stone and textile industries.
MICNO's series of low voltage VFD include... Using advanced technology, there are a variety of control methods, can also save energy to a greater extent.