Abstract : Frequency converters (VDCs) are increasingly used in speed control systems due to their advantages such as simple structure, low cost, and ease of maintenance. Among these advantages, the V/F curve parameter setting is crucial for ensuring the static speed accuracy of the VDC speed control system. This paper theoretically analyzes the V/F function of AC motors and uses mathematical methods to calculate the parameters of the V/F curve of the VDC. Two V/F curves from a Delta VFD-A type VDC converter are used to simulate the voltage/frequency characteristics of AC motors at different power supply frequency ranges. Furthermore, an application example illustrates how setting the parameters of the V/F curve of the VDC can improve the speed accuracy of the VDC speed control system. Keywords: Frequency converter; V/F function; VDC speed control system; Least squares method; Static speed accuracy Since the 1980s, with the development of power electronic devices and pulse width modulation technology, AC speed control systems have gradually replaced DC speed control systems in industrialized countries. AC speed control systems, with their advantages of simple structure, low cost, and ease of maintenance, have gradually become the mainstream speed control system. Variable frequency speed control (VFD) is a method of changing the speed of an AC motor by altering the frequency of the power supply applied to the stator windings. Current AC motor VFD systems are mainly divided into two series: simple and inexpensive general-purpose types, and complex, high-performance types. The Delta VFD-A AC VFD system is a general-purpose AC motor driver, belonging to the general-purpose type. It is inexpensive, simple in structure, and easy to install, and is widely used in industrial control. With the continuous development of VFD technology, this model has become increasingly sophisticated in terms of function and performance, offering over 70 parameters that can be set according to different applications. It implements functions such as V/F curve analysis, start-up and braking time, starting torque compensation, slip compensation, and multi-speed setting. It also features 17 automatic fault detection and AVR functions, making it very convenient to use and adjust. Furthermore, with proper parameter adjustment, high static speed accuracy can be achieved. Among these, the V/F curve parameter setting is crucial for ensuring system speed accuracy. This model can set two V/F curves to simulate voltage/frequency characteristics at different frequency ranges. This article will explain the adjustment principles of parameters such as the V/F curve of the VFD007A43A inverter to achieve high speed accuracy, and demonstrate its speed accuracy and stability. [b][align=center]For details, please click: Delta VFD-A Type Inverter V/F Function Analysis and Application[/align][/b]