What is an inverter?

An inverter is a device that converts alternating current at one frequency into alternating current at another frequency that can be adjusted. That is, the inverter is a device that changes the frequency of the current applied to the coil inside the motor and through it can control the motor speed steplessly, without the use of mechanical gearboxes. Inverters often use semiconductor components to sequentially switch the windings of the motor to generate a rotating magnetic field that rotates the rotor.

What is an inverter?

Working principle of inverter

First, a single-phase or three-phase power source is rectified and filtered into a flat DC power source. This stage is performed by a diode bridge rectifier and a capacitor. The power input can be single phase or 3 phase, but it will be at a fixed voltage and frequency (eg 380V 50Hz). The DC voltage above will be converted (reversed) into a symmetrical 3-phase AC voltage. Initially, the DC voltage generated will be stored in the capacitor bank. Next, through proper self-triggering, the IGBT converter (short for insulated gate bipolar transistor) acts like an ultrafast on and off switch to generate the inverter's output waveform. will generate a 3-phase AC voltage by PWM pulse width modulation.

What is an inverter?

Inverter classification

Inverters have many types, if divided by input power, we have 2 basic types: inverters for 1-phase motors and inverters for 3-phase motors. Among them, inverters for 3-phase motors are more widely used.

Guide to choosing types of inverters

To choose the right type of inverter for your application, it is necessary to clearly define the application needs, the purpose of use and balance the investment. In order to choose the type of inverter that best suits the requirements of use, it is necessary to note the following selection principles:

• Choose the right inverter for the motor type and motor capacity: find out what type of motor you need to install the inverter, synchronous or asynchronous, single phase or 3 phase, DC or AC, voltage included much… to choose the right inverter. The inverter power must be selected equal to or greater than the motor power
• Choose an inverter according to your application requirements: when choosing an inverter, you need to specify what your application is? What speed is required? Are there any special advanced control features required? Is there a requirement for system synchronization or communication? What are the characteristics of the working environment (wet, high temperature, dusty, flammable, explosive...). If there are no special requirements, it is possible to choose a general-purpose inverter such as GD20 or GD200A, but if there are special requirements, it is necessary to choose inverters with suitable features.
• Choose inverter according to actual load: Choosing inverter according to load is a very important thing. The first thing you must determine is the type of machine load: light load or heavy load, medium load and whether the operating mode is short-term or long-term, continuous or intermittent... then choose the type. suitable inverter.
• Choose an inverter that is convenient for the programmer when programming the controls, or choose a supplier that is able to support the programming of your applications.
• Select the inverter according to the specifications of the old inverter (in case of replacing another brand) or according to the required design specifications.
• And finally, don't forget to consider the financial factor.

Advantages of Inverters

Nowadays inverters are no longer an expensive luxury only for 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:

• Easily change the motor speed, reverse the motor rotation direction.
• The inrush current is reduced compared to direct starting, star-delta starting, so there is no voltage drop or difficulty in starting.
• The process of starting through the low-speed magnetic inverter helps to prevent the motor carrying a large load from starting suddenly, avoiding damage to the mechanical part, the bearing, and increasing the life of the motor.
• Significant energy savings compared to direct motor drive method.
• Inverters usually have electronic systems for overcurrent, overvoltage and undervoltage protection, creating a safe system for operation.
• Thanks to the working principle of inverting conversion through diodes and capacitors, the reactive power from the motor is very low, thus reducing the current significantly during operation, reducing the cost of installing compensating capacitors, and minimizing waste. power loss on the line.
• The inverter is integrated with communication modules that make controlling and monitoring from the center very easy.

What are the notes when using the inverter?

In the process of using the inverter, we need to pay attention to a number of issues to be able to ensure that the equipment is compatible and best. Specifically, we need to pay attention to a number of related issues such as:

• We need to base on the parts, stages, and production stages, then determine the required power for the engine. This will serve as a premise for choosing the right inverter, helping to avoid waste as well as ensuring sufficient capacity for that production process.
• The components inside the inverter are very sensitive to environmental conditions, so care should be taken to ensure the longevity as well as the accuracy and stability of the device.
• It is necessary to calculate between ways to change the engine speed accordingly. In addition to the inverter, we can completely adjust the speed and reverse by starting star, delta or soft start.
• The first time you interact and work with inverters, you need to spend a lot of time learning about the technical characteristics as well as the correct usage methods. Note about the process, how to use, install to ensure safety - good operation - high efficiency.

Above is some basic information and knowledge about what is inverter? Hope it will be necessary for those of you who are looking to learn.

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