Paul Sente

Efficient Control of a Piezoelectric Linear Actuator Embedded Into a Servo-Valve for Aeronautic Applications

Inside a direct-drive servo-valve (DDV), the motion of the spool controlling the direction of the hydraulic fluid flow is directly actuated by an electrical motor. Due to the small stroke needed, it is possible to use a linear amplified piezoelectric actuator directly connected to the spool. The aim of this paper is to investigate how to design the power and control electronics of a DDV based on a linear amplified piezoelectric actuator to take full advantage of such a motor. In particular, it will be shown that the voltage applied on the piezoelectric stacks may be successfully controlled by use of four-quadrant choppers with the benefits that the injected electrical charge stored in their capacity can be recovered. This leads to the low-consumption scheme presented which can be easily fed by a boost converter from the aircraft 28 Vdc.

Control of a direct-drive servo-valve actuated by a linear amplified piezoelectric actuator for aeronautic applications

In direct-drive servo-valves, the motion of the spool controlling the direction of the hydraulic fluid flow is directly controlled by an electrical motor. Owing to the small stroke needed, it is possible to use a linear amplified piezoelectric actuator directly connected to the spool. The aim of this paper is to investigate how to design the power and control electronics of a direct-drive servo-valve based on a linear amplified piezoelectric actuator in order to take full advantage of such a motor. In particular, it will be shown that the voltage applied on the piezoelectric stacks may be successfully controlled by use of four-quadrant choppers with the benefits that the injected electrical charge stored in their capacity can be recovered. This leads to the low consumption scheme presented which can be easily fed by a boost converter from the aircraft 28 VDC.

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.

Control under normal and fault operation of a PM synchronous motor with physically and magnetically decoupled phases

Thanks to their particular design, HDD servomotorsreg are a family of PM synchronous motors which offer, in addition to their higher torque to mass ratio, very interesting features for high reliability drives. Indeed, in these motors the phases are physically and magnetically decoupled so that an internal fault in one phase or the loss of feeding of one phase has no influence on the other ones. The aim of this paper is to describe a control strategy for this type of motors. The research reported in this paper was performed within the European Union FP6 project DRESS (Distributed and Redundant Electromechanical nose gear Steering System) for more electrical aircraft.

Simulink library for simulation of the permanent magnets synchronous machine drive

Reliability of electromechanical actuation systems as those used in aerospace applications may be improved by a proper choice of the motor, of its control strategy and of the architecture of the power electronics feeding the motor. This paper presents a Simulink library for the simulation of the motor and of its control electronics allowing to choose between three types of motor and between two types of vector control. The models allow the simulation of different fault conditions in order to identify the weak and strong points of each architecture. The research reported in this paper was performed within the European Union FP6 project DRESS (distributed and redundant electromechanical nose gear steering system) for more electrical aircraft (http://www.dress-project.eu).

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>>