What are the functions of the frequency converter?

2021-09-16 08:27:35 jact_elec

What are the functions of the frequency converter?

Frequency converter is an electrical equipment that converts industrial frequency power into AC power at any frequency and voltage. The use of the frequency converter is mainly to adjust the power of the motor to realize the variable speed operation of the motor.

The composition of the frequency converter mainly includes two parts: the control circuit and the main circuit. The main circuit also includes components such as a rectifier and an inverter.

Inverter function:

1. Frequency conversion energy saving

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

When the motor cannot run under full load, the traditional speed adjustment method for equipment such as fans and pumps 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 large The energy is consumed in the baffle and valve closure process. When using variable frequency speed regulation, if the flow requirements are interchanged, the requirements can be met by reducing the pump or fan.

In order to generate variable voltage and frequency, the device first converts the AC power of the power supply into direct current (DC).

This process is called rectification. A device that converts direct current (DC) into alternating current (AC), its scientific term is "inverter".

Generally, the inverter converts the DC power supply into a certain fixed frequency and certain voltage inverter power supply.

For inverters with frequency inverters, the voltage of the inverter is an analog sine wave, which is mainly used in inverter inverter speed regulators, also called variable frequency speed regulators.

For the variable frequency inverters, which are mainly used in the detection equipment of instruments and meters, which require high waveforms, the waveforms must be sorted and can output a standard sine wave, which is called a variable frequency power supply. The general variable frequency power supply is 15-20 times the price of the frequency converter.

As an electronic circuit, the inverter itself also consumes power (about 3-5% of the rated power). A 1.5-hp air conditioner itself consumes 20-30W of electricity, which is equivalent to a permanent light.

It is a fact that the inverter runs under the power frequency and has power saving function. But his pre-conditions are:

  • high power and load for fans/pumps

  • the device itself has a power saving function (software support)

  • long-term continuous operation

These are the three conditions that reflect the power saving effect.

2. Soft start energy saving

The hard start of the motor has a serious impact on the power grid, and the requirement for the power grid capacity must be too high.

The large current and vibration generated during the start will cause great damage to the circuit breaker and valve, which is unfavorable to the equipment and the penetration height.

After using the frequency conversion energy-saving device, the use of the frequency converter's soft start function will make the starting current start from zero, but it will not exceed the rated current, avoiding the impact on the power grid and the requirement for power capacity, and extending the service life of equipment and valves ,save equipment maintenance costs.

3. Power factor compensation and energy saving

Reactive power not only increases the line loss and heat generation of the equipment, but more importantly, the reduction of the power factor leads to the reduction of the active power of the grid.

A large amount of reactive power is consumed in the line, and the efficiency of equipment is low and the waste is serious.

Use frequency conversion speed control device Later, due to the effect of the filter capacitor inside the inverter, the reactive power loss is reduced and the active power of the grid is increased.

In theory, the frequency converter can be used in all mechanical equipment with motors.

When the motor starts, the current will be 5-6 times higher than the rated current, which will not only affect the consumption of the motor, but also consume energy.

When the system is designed, there will be a certain margin in the selection of the motor.

The speed of the motor is fixed, but in actual use, it sometimes runs at a certain or higher speed.

Therefore, it is very important to carry out frequency conversion transformation. Necessary.

The frequency converter can realize the soft start of the motor, compensate the power factor, achieve the purpose of energy saving and speed regulation by changing the input voltage frequency of the equipment, and can provide the equipment with protection functions such as overcurrent, voltage and overload.