Hervé Buyse

A methodology to determine gains of induction motor flux observers based on a theoretical parameter sensitivity analysis

A method to compute gains of induction machine flux observers, based on a theoretical sensitivity analysis taking the magnetic saturation into account, with the aim to minimize the observer sensitivity to electrical parameter uncertainties is proposed in this paper. It is shown for a reduced order observer, that the sensitivity to parameter uncertainties may be independent of the reference frame, when a modification is introduced in the classical determination of the slip frequency. It is also shown how to extend the proposed method to a full order observer. The theoretical study is completed by experiments on a 750 W induction machine (using DSP TMS320C31) which confirms the theoretical results.

Influence of digital current control strategy on the sensitivity to electrical parameter uncertainties of induction motor indirect field-oriented control

In indirect field-oriented control schemes, the current control strategy influences strongly the flux control sensitivity to electrical parameter uncertainties. This influence is shown in this paper with the help of a theoretical sensitivity analysis taking into account the saturation effect and considering different digital current control strategies. The performance obtained with a classical proportional-integral (PI) current controller is compared with the performance obtained with a novel current controller associating a feedforward action and a proportional feedback (called PFF controller). A control strategy without current measurement is also considered as a particular case of the PFF controller. It is shown that the flux control sensitivity is generally smaller when the currents are controlled by PFF controllers than by PI controllers. The theoretical study is completed by experiments on a 750 W induction motor (using a digital signal processor (DSP) TMS320C31) which confirm the theoretical results.

From smart sensors to smart actuators: Application of digital encoders for position and speed measurements in numerical control systems

Electrical actuators are generally applied in the field of robotics to control speed or position using a numerical control system; digital sensors are then preferred because of their compatibility with the control system. Binary or digital encoders, generally of the optical type, are well adapted, since they provide a position information in a digital form which allows speed calculation by numerical derivation. The aim of this paper is to define the application limits of these digital encoders considering their optimal use, taking into account an adequate signal processing but also particular application conditions.

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.

Fuzzy logic based field orientation in an indirect FOC strategy of an induction actuator

The aim of this paper is to propose a modification in the classical indirect field oriented control strategy to reduce its sensitivity to electrical parameter uncertainties. This modification is based on a theoretical sensitivity analysis and introduces in the control strategy a very simple fuzzy logic block to ensure the field orientation.

Current control in fully digital VSI fed SMPM synchronous motor drive systems

This paper presents a comprehensive analysis of the problems related to the implementation of the motor field oriented control in a fully digital control of a VSI fed PM synchronous motor drive system. All discrete effects involved in this process are taken into account; either they are related to the sampling introduced by the digital controller, or to the use of a PWM inverter as power amplifier. Experimental results confirm the theoretical analysis.

Electrical Actuation Systems with AC Motors an Example of Complex Automatic Control

Abstract Digitally controlled actuation systems with VSI fed AC motors are examples of complex hybrid systems combining digital and continuous variables : - synchronous or induction motors are non linear multivariable subsystems; - the control amplifier consisting in a power electronic converter feeding the motor can only produce a limited number of control vectors from which control variables are obtained by an appropriate sequence in order to follow the references generated by the digital regulator. It will be shown how the discrete and non linear characteristics of these systems can be taken into account even if the control is fully digital.

A simplified model of the multiple armature, polyphase self-controlled synchronous machine

The paper presents a simplified model of a round rotor, sinusoidally coupled, multiple armature, polyphase self-controlled synchronous machine. The machine-inverter combination can be considered as a conventional DC machine with shifted brushes. The multiple armature solution is compared with the single armature polyphase solution using criteria based on the optimum use of the semiconductor valves, the torque ripple and the damper losses.

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>>

Nonlinear stability analysis of a TCR system with an integral control loop of the reactive power

A stability analysis is made of a single-phase thyristor controlled reactor (TCR) system with an integral control loop for the reactive power. The nonlinear aspects of the dynamics of the system and their influence on its stability have been taken into account by using recurrence equations.<<ETX>>