Abstract : This paper introduces the PI and PID functions in frequency converters, a commonly used motor speed control device, as well as the PI and PID functions in instruments and meters. It also provides a detailed explanation of the adjustment of three key parameters—proportional gain, integral time, and derivative time—in practical applications. Keywords : PI, PID, proportional gain, integral time, derivative time, frequency converter, synchronous controller. PI and PID are short for proportional-integral control and proportional-integral-derivative control. In the development of automatic control, PI and PID control are the oldest and most enduring basic control methods. They remain widely used basic control methods to this day. [b]1 Adjustment of PI and PID in Frequency Converters 1.1 Application of PI Function in Speed ​​Regulation in Frequency Converters[/b] When the automatic speed regulator in a frequency converter performs high-response or high-precision control, it must be carefully adjusted. Therefore, appropriate proportional gain and integral time must be set. This ensures that the speed regulator achieves the expected effect when performing precise control. The proportional gain and integral time are obtained by the following formula. TM in the formula refers to the time required for the speed to rise from zero to the basic speed under rated torque. ASR uses the response angular frequency to set the speed control response. TM = (Total inertia of click and load squared) × 1.027 × (Base speed squared) / 375 × Power Kp = ASR response angular frequency × TM / 1000 ASR integral time Ti = 4 / (ASR response angular frequency × ASR integral time constant compensation coefficient % / 100) Where: TM - Machine time coefficient; ASR - Speed ​​regulator; Kp - Proportional gain. [b][align=center]For more details, please click: PI and PID Applications and Adjustments in Inverters and Instruments[/align][/b]