Frequency converter devices for controlling rotation speed of motors and pumps in manufacturing lines. These devices achieve precise motor speed control, energy-saving operation, and soft start functions by variably controlling AC power frequency and voltage. Includes application-specific products such as general-purpose inverters, vector control inverters, servo inverters, and harmonic-compatible types, used for speed control of conveyor lines, fans, pumps, and machine tool spindles. Features extensive lineup including single-phase and three-phase compatibility, capacity ranges from 0.1kW to several hundred kW, and models with communication functions, contributing to energy savings and productivity improvement in manufacturing sites. Enables automatic control system construction through PLC integration and is clearly distinguished from standalone motors or power supply devices.