An overview is presented of digital control problems arising in the use of microprocessors and the application of modern control theory, from both the theoretical and practical viewpoints. The discussion covers optimal control, robust control, feedback and feed-forward control, and active and passive adaptive control. Various application are described, drawing on the author's own experience. It is concluded that a robust optimal digital controller for motor control can be practically designed and implemented with currently available techniques and hardware. >

Application of modern control techniques to motor control

A digital position control system using a dc motor fed by a four-quadrant transistor chopper is presented. All control functions are handled by a microcomputer requiring only an incremental encoder for position and speed sensing. Two control approaches are considered: the classical control approach and the state feedback approach. For each approach, static and dynamic control performance is studied in terms of system parameters. Experimental-results are given and discussed.

Digital Position Servo System: A State Variable Feedback System

The cascaded loop configuration is the standard configuration for speed and current loops in DC motor drives of medium and large power. An alternative is the parallel loop scheme, which is used in some fast response servomotor drive applications. The parallel loop scheme features the independent operation of the two loops and the operation of only one loop at any given time. The latter characteristic is an advantage in microprocessor implementations because shorter computation and execution times are obtained, allowing processor time for other functions. Improvements in the dynamic response of the speed loop can also be obtained. The two configurations are compared in terms of dynamic response, algorithmic implementation, and execution times. The problems associated with the smooth transfer of control between speed and current loops in the parallel scheme are discussed, and an efficient solution is proposed. Experimental transient responses and execution times for both schemes are presented and compared. >

A comparison of microcomputer-based implementations of cascaded and parallel speed and current loops in DC motor drives

The conduction intervals of power semiconductors in static converters connected to the AC mains are dictated by the AC line voltages. Accurate and reliable synchronization signals must therefore be generated despite the significant distortion that can be present in the AC voltage. The authors propose a novel method for obtaining accurate zero-crossing signals, based on the use of switched-capacitor filters. The characteristic frequency of such filters depends on the frequency of an external control signal. Therefore, this frequency can be accurately set and made to track the input frequency variations. The scheme is presented and analyzed, and design criteria are derived. Experimental results demonstrate the superiority of the method over conventional filtering techniques. The scheme has been used successfully for phase-controlled thyristor converters and transistorized four-quadrant PWM (pulse-width modulated) AC/DC converters. >

A novel line synchronization scheme for static power converters

The single-chip microcomputer MC68701-based inverter gating system is proposed in this paper. The three-phase converter and inverter gatings occur independently and the current source inverter-fed induction motor controller with voltage feedback is also implemented in a single microprocessor. The accuracy of gating is about 1 deg in converter delay angle at line frequency 60 Hz and 0.19 percent in inverter frequency at output frequency 60 Hz. The proposed system is applied to 100-hp induction motor drive.

Design of Single-Chip Microprocessor-Based Controller for Current Source Inverter-Fed Induction Motor Drive

A single-chip microcomputer is used to design a fully digital dc servo system to replace the conventional analog circuits. This microcomputer performs three main tasks: the firing control of a three-phase full-wave thyristor dual converter; the compensation for the nonlinear and loading effect in the converter; and compensations of position loop and rate loop. With no current feedback and minimum components, this dc servo system provides fast transient response and high reliability.

/pdf/design-and-implementation-of-a-fully-digital-dc-servo-system-sqrss9vej5.pdf

Design and Implementation of a Fully Digital DC Servo System Based on a Single-Chip Microcomputer

https://ir.nctu.edu.tw:443/bitstream/11536/4977/1/A1982NK18100009.pdf

Pc Tang

Papers

Design and Implementation of a Fully Digital DC Servo System Based on a Single-Chip Microcomputer

Microprocessor-based design of a firing circuit for 3-phase full-wave thyristor dual converter