Chi tiết bài viết Operating Principle of Inverters

What is an inverter? How does it work?

An inverter, also known as an AC motor controller, is a device used to control the speed and torque of both asynchronous and synchronous motors. The inverter converts DC voltage into AC voltage with adjustable amplitude and frequency through a converter, after rectifying single-phase or three-phase power into direct current. The output voltage characteristic curve of the inverter is typically set in V/f mode, where the voltage decreases proportionally with frequency. The V/f ratio is determined based on the motor's characteristics.

How will the starting current and starting torque behave when a motor is controlled by an inverter?

Typically, a motor will have a starting current that is 6-7 times the rated current when powered directly from the grid, resulting in a current spike.

A motor can start smoothly when controlled by an inverter, with frequency and voltage gradually increasing. The starting current should be below 150% of the rated current (125% - 200% for different models), and the starting torque should be between 70% and 120% of the rated torque. For inverters with the capability to automatically boost torque and starting torque above 100%, they can start under full load.

What methods can be used to adjust speed?

The speed can be adjusted by the following methods:

1. Potentiometer on the control panel

2. External analog current/voltage signals

3. Multifunction input terminals for multi-speed control

4. Communication methods using a master controller