Haruo Naitoh

Microprocessor-Based Adjustable-Speed DC Motor Drives Using Model Reference Adaptive Control

Model reference adaptive control (MRAC) is applied to microprocessor-based adjustable-speed dc motor drives. The algorithm of the MRAC is based on the linear model following control (LMFC) and is the combination of the adaptive controller with the LMFC. The MRAC-based speed controller allows the indistinctness and/or inaccuracy in the motor and load parameters in the system design stage. It also maintains the prescribed control performance in the presence of the motor parameter perturbations and the load disturbances. The experimental setup is constructed using a microprocessor. The experimental results confirm the useful effects of the MRAC-based speed controller.

A Microcomputer-Based Thyristor Leonard System Having Powerful RAS Functions

The microcomputer-based entirely digital scheme for the thyristor Leonard system is presented. The main processor used is a 16-bit microprocessor. Systematic and efficient use of the microprocessor and microcomputers successfully provides the thyristor Leonard system with the entire digital scheme. This scheme offers not only the high-performance adjustable-speed regulation of dc motors, but also other important functions and features required for the Leonard system, such as system sequencing, thyristor triggering, various compensations for improvement in electric performances, diagnostic, monitoring, and protection capabilities, drift-free characteristics, and so forth. The scheme also serves smoother communications between the microcomputer-based system and a programmable host controller, which supervise a number of Leonard systems. Compact design permits the hardware construction for the digital scheme to be accommodated on a single board.

Performance Improvement in Microprocessor-Based Digital PLL Speed Control System

A microprocessor-based digital PLL speed control system for motor drives is discussed on its load characteristics, stability, and speed control accuracy. The digital and hybrid simulations as well as the Z transform are used to analyze these items of discussion. As the results of the analysis, two compensating methods, that is, the current compensator and the speed feedback loop are proposed for enlargement of both static and dynamic operating load torque ranges of the PLL-controlled motor. This effect of the compensators is predicted through theoretical procedures, assessed by the hybrid simulator, and confirmed by experiments. The effects due to the current compensator and the speed feedback loop on the stability and the speed control accuracy of the PLL system are inspected with the aid of digital and hybrid simulations. These compensators do not virtually affect the stability of the PLL system. The speed control accuracy of the PLL system can be increased by virtue of the speed feedback loop. Design examples based on the discussion in this paper are provided and the authors conclude that the methods for performance improvement have substantial effects on the practical design for the microprocessor-based digital PLL speed control system.

Stability Analysis of Constant Margin-Angle Controlled Commutatorless Motor

The constant margin-angle control is a triggering control scheme applied to a load commutated inverter to eliminate the commutation failure and to increase the system power factor. The instability of the commutatorless motor operated with this control scheme is analayzed. Basically, two types of instability are found: one due to the negative equivalent resistance and the other due to the angle feedback. The methods to prevent such instability are also proposed and discussed. The analysis results are confirmed by digital simulation and experimental data.

Effects of Magnetic Saturation on the Performance of Thyristor Commutatorless Motors

The ratings and the other constants of motors are designed within a magnetically saturated region. Studies of motors, however, have dealt with and have been limited to the problems in a linear region for the sake of simplicity. A basic study of the operating performance of commutatorless motors in the magnetically saturated region is presented here. The magnetic saturation is evaluated in terms of the permeance of a magnetic circuit. Digital simulation based on this basic study reveals the effects of the magnetic saturation on the static characteristics of the commutatorless motors. The theory established in this paper for the analysis of the effects of the magnetic saturation can successfully be applied to other kinds of motors as well as to commutatorless motors.

Compensation of a GTO-NPC inverter for the damping of rolling mill torsional vibration by ETC (estimated torque feedback control)

A new control for torsional vibration damping for a rolling mill driven by a GTO-NPC inverter is presented. This paper proposes a spindle torque estimator implemented in a microcomputer. Negative feedback of the estimated torque prevents the torsion and damps the vibration.

Improvement of robustness of vector controlled induction motors using feedforward and feedback control

The authors propose a combined feedforward and feedback (FF/FB) control to improve robustness of vector controlled induction motors. This FF/FB system maintains the quick response of the slip frequency type and is insensitive to parameter variation in cooperation with field orientation control. Furthermore the authors propose a neural network based vector control as a final goal of the FF/FB system.