The differences between inverter and VFD

1.1 Introduction to VFD

VFD is a power control device that uses frequency conversion technology and microelectronics technology to control AC motors by changing the frequency of the motor’s working power supply.

1.2 Working principle

Frequency conversion is developed from the field of modern power electronics technology and is a commonly used conversion device between direct current and alternating current. It can also change the frequency of our AC power to control the power control equipment of AC motors. The VFD is mainly composed of rectifier (AC to DC), filtering, inverter (DC to AC), braking unit, drive unit, a detection unit, micro-processing unit, etc.

The VFD adjusts the voltage and frequency of the output power supply by breaking 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 VFD has many protection functions , such as overcurrent, overvoltage, overload protection, and so on.

1.3 VFD function

1. Adjustable torque limit
2. Controlled stopping method
3. Energy saving
4. Reversible operation control
5. Reduce mechanical transmission parts

2.1 Introduction to the inverter

The inverter converts DC power (battery, storage battery) into AC power (usually 220V, 50Hz sine wave). It is composed of an inverter bridge, control logic, and filter circuit.

2.2 Working principle of the inverter

Convert alternating current to direct current. Then use electronic components to switch the direct current. Change to alternating current. The working process is generally divided into four major processes: rectifier circuit, smoothing circuit, control circuit, and inverter circuit.

2.3 Inverter characteristics

1. High conversion efficiency and fast start-up;
2. Good safety performance: The product has 5 protection functions: short circuit, overload, over/under voltage, and over-temperature;
3. Good physical properties: The product adopts an all-aluminum shell, with good heat dissipation performance, hard oxidation treatment on the surface, good friction resistance, and resistance to extrusion or impact by a certain external force;
4. Strong adaptability and stability with load.

3. The differences between inverter and VFD

1. The inverter is a component used to convert direct current into alternating current, and the VFD is a component used to change the frequency of alternating current;
2. The inverter converts DC power (battery, storage battery) into AC power (usually 220V, 50Hz sine wave), and the frequency can also be adjusted; the VFD converts the input AC power into the AC power output of the required frequency;
3. The VFD must have a frequency adjustment part, and the inverter only needs to have a fixed output frequency.