B. Robyns

Study and implementation of a simplified and robust position digital controller for a PM synchronous actuator

This paper presents a fully digital position control system for small power surface mounted PM synchronous actuators. The control algorithm relies on a simplified decoupling state feedback in order to obtain field orientation. There is no current measurement, and the current values needed to compute the control algorithm are predicted from a model. This makes it possible to use a fully digital position controller by using low cost 8 bit microprocessors with only a position sensor. Moreover, it is shown in this paper that it is preferable to use, in the decoupling state feedback, an estimated, instead of a measured, value of the current to ensure stability and to improve the robustness of the system regarding parameter uncertainties. Furthermore, as the actuator model is linearized by a decoupling state feedback, the robustness of the system has been further improved by using appropriate techniques evolved for linear systems to synthesize the position controller. The performance of the proposed control system is analyzed by a theoretical study and digital simulations. It has been implemented around two 8 bit MCS 8051 microcontrollers and tested on a 2 kW machine. >

Performance analysis of a simplified indirect field oriented control algorithm for small power induction actuators

The aim of this paper is to study the performance of a simplified indirect field oriented control algorithm suited for small power induction actuators. The main particularities of the control strategy under study are the use of a disturbance observer in the speed and position control loops, and the absence of any current measurement. The good performance of the proposed control strategy, particularly with regard to the flux control sensitivity to parameter uncertainties, is shown by theoretical results and digital simulations, and has been confirmed by experiments on a laboratory prototype.

Investigation on a fully digital control system for synchronous reluctance machines

The authors deal with the fully digital control of synchronous reluctance motors. A control algorithm based on the strategy consisting of keeping constant the d axis component of the stator currents, and controlling the torque by the q axis component of these currents is investigated. The effects of the sampling period, the delay due to computation time and the parameter uncertainties, on the stability and the robustness of the current control, are analysed. It is found that, with the proposed control algorithm, values of the sampling period which are compatible with the use of low cost microcontrollers may be chosen. Digital simulations confirm the theoretical study.<<ETX>>

Influence of parameter uncertainties on the performance of some induction actuator indirect field oriented control schemes

The aim of this paper is to compare the performance of two indirect field oriented control schemes. In the first one, the Park components of the stator currents are controlled by two PI regulators, and in the second one, these currents are not directly controlled and there is no current measurement. It is shown that the sensitivity of the flux control to parameter uncertainties is generally smaller in the control scheme without current controllers than in the control scheme with current PI controllers, in spite of the fact the latter offers a more precise current control. It is also shown that the control scheme without current measurement allows to develop a fully digital implementation on low cost microprocessors. Experiments on a laboratory prototype confirm the good performance of this simplified control scheme.<<ETX>>

Robust positional control with an induction actuator by using a PID controller associated with field orientation

A robust digital positional control system is presented for small power induction actuators. A simple control algorithm is obtained by performing field orientation through an estimated linearizing state feedback, avoiding any measurement or estimation of the rotor flux. The hardware implementation is organized around two 8-b microcontrollers and needs only a digital position encoder as the sensor. The good performance of the system has been validated by simulation and experiments on a laboratory prototype.<<ETX>>