Comprehensive Guide to Designing Feedback Control Systems and Compensation Types
This guide delves into the design of feedback control systems, focusing on system structure, component selection, and parameter optimization. It discusses various compensation types such as Cascade, Feedback, Output, and Input Compensation, providing insights into their characteristics and applications. Special attention is given to Phase-Lead and Phase-Lag networks, including their corresponding transfer functions and Bode diagrams. The steps to design a Phase-Lag network using Bode diagrams are outlined, ensuring effective compensation to improve system performance.
Comprehensive Guide to Designing Feedback Control Systems and Compensation Types
E N D
Presentation Transcript
Modern Control SystemEKT 308 Design of Feedback Control Systems
Control System Design: Concerned with the arrangement , or the plan , of the system structure and the selection of suitable components and parameters. Compensator: Additional component or circuit that is inserted into a control system to compensate for deficient performance. Types of Compensation: Cascade Compensation ( figure 1.a) Feedback Compensation (figure 1.b) Output Compensation (figure 1.c) Input Compensation (figure 1.d)
Types of Compensation Figure 1: Types of compensation
Consider the following first order compensation transfer function • The compensation network is called phase-lead network if • |z| < |p|
Because zero occurs first on the frequency axis, we obtain a phase-lead characteristic, as shown in the following figure 3. Figure 3: Bode diagram of phase lead network.
Phase – Lag network Consider the following first order compensation transfer function • The compensation network is called phase-lag network if • |z| > |p|
Phase Lag Design using Bode Diagram Steps to design an appropriate phase lag network. Obtain Bode diagram for the uncompensated system. (Gain adjusted for desired error constant). Determine the phase margin. If insufficient, follow the remaining steps. Determine the frequency where the phase margin would be satisfied, if the magnitude curve crosses 0-db at this freq. (allow 5 degree safety) Place the zero one decade below the new cross over frequency. Measure the necessary additional attenuation at the new crossover freq
Phase lag design example Steps: Uncompensated Bode diagram is shown in figure 6.