The company's new product - frequency converter

Definition of Frequency Converter

A frequency converter, also known as a Variable-Frequency Drive (VFD), is a sophisticated power control device that integrates frequency conversion technology with microelectronics. Its primary function is to achieve precise control of AC motors by modulating the motor's working power supply frequency.

 

1. Principle of Variable Frequency Speed Regulation
The fundamental operating principle of a frequency converter is derived from the speed formula of a three-phase asynchronous motor ($n = 60f/p(1-s)$), where $n$ represents the motor speed, $f$ denotes the frequency of the stator power supply, $p$ signifies the number of pole pairs, and $s$ refers to the slip rate of the motor. From this formula, it is evident that the motor speed is directly proportional to the power supply frequency, inversely proportional to the number of pole pairs, and influenced by the slip rate. In practical applications, variations in the slip rate are relatively minor; hence, the motor speed is predominantly adjusted by altering the power supply frequency.

2. AC-DC-AC Conversion Process
The frequency converter operates through a three-stage process: rectification, filtering, and inversion. Initially, the input AC power is converted into DC power via the rectifier circuit. Subsequently, the filter circuit eliminates any ripples present in the DC power. Finally, the inverter circuit converts the smoothed DC power back into AC power for output. Throughout this process, the frequency converter can adjust its output voltage and frequency according to specific requirements, thereby enabling precise control of the motor speed.

3. Control and Protection Mechanism
In addition to facilitating variable frequency speed regulation, the frequency converter incorporates multiple protection functions, including overcurrent, overvoltage, and overload protection. Upon detecting abnormalities in either the motor or the frequency converter itself, the device automatically initiates protective measures such as shutdown and alarms to ensure safe equipment operation. Furthermore, the frequency converter can optimize its control based on external control signals and internally detected operational parameters, enhancing both the efficiency and energy-saving performance of the motor.