The structure and function of the Variable frequency Drive

2021-07-16 14:19:08 jact_elec

The structure and function of the Variable frequency Drive

Variable frequency Drive is a power control device that uses variable frequency technology and microelectronics technology to control AC motors by changing the frequency of the motor's working power supply.

The inverter adjusts the voltage and frequency of the output power supply by the opening and closing of the internal IGBT, and provides the required power supply voltage according to the actual needs of the motor, thereby achieving the purpose of energy saving and speed regulation.

In addition, the inverter has many protection functions. , Such as overcurrent, overvoltage, overload protection and so on. With the continuous improvement of industrial automation, frequency converters have also been widely used.

Basic composition of frequency converter

The frequency converter is usually divided into 4 parts: rectifier unit, high-capacity capacitor, inverter and controller.

Rectifier unit: converts alternating current with a fixed operating frequency into direct current.

High-capacity capacitors: store the converted electrical energy.

Inverter: An electronic switch is composed of a high-power switching transistor array, which converts direct current into square waves of different frequencies, widths and amplitudes.

Controller: Work according to the set program, control the amplitude and pulse width of the output square wave, make the superimposed AC power similar to sine wave, and drive the AC motor.

The function of the Variable frequency Drive

The energy-saving effect of the frequency converter is mainly manifested in the application of fans and water pumps.

In order to ensure the reliability of production, all kinds of production machinery have a certain margin when they are designed with power drives.

When the motor cannot run under full load, in addition to meeting the power drive requirements, the excess torque increases the consumption of active power and causes a waste of electrical energy.

The traditional speed regulation method of fans, pumps and other equipment is to adjust the air supply and water supply by adjusting the inlet or outlet baffle and valve opening.

The input power is large, and a large amount of energy is consumed in the baffle and valve closure process. in. When using variable frequency speed regulation, if the flow requirement is reduced, the requirement can be met by reducing the speed of the pump or fan.

The function of the motor using the Variable frequency Drive is to adjust the speed and reduce the starting current. In order to generate variable voltage and frequency, the equipment first converts the AC power of the power supply into DC power. This process is called rectification.