Francis Labrique

Torque Control Strategy of Polyphase Permanent-Magnet Synchronous Machines With Minimal Controller Reconfiguration Under Open-Circuit Fault of One Phase

This paper deals with the torque control of polyphase segment surface-mounted-permanent-magnet synchronous machines. First, we introduce a Lagrangian formulation for computing the optimal sinusoidal currents allowing to develop a given torque, both in normal operation mode and in fault operation mode (loss of one phase). Then, we present a torque control architecture allowing to switch from normal to fault operation mode with a minimum reconfiguration of the controller. All the theoretical results are validated by simulation and experiments on a test bench.

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.

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.

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 KCL to Class D Amplifier

From a circuit point of view, the starting point of the students coming out of the secondary school is roughly limited to describing the flow of electrical charges through a simple loop. Nevertheless, one and a half years later, they can design, simulate, build and test the core of a Class D amplifier while meeting demanding learning objectives. This paper relates the story of a project conducted in the context of an undergraduate electrical engineering program. Circuits and system concepts are introduced from the beginning of the first year in a physics course, and are applied to a project during the second term. A circuit theory course and the Class D amplifier project are run in parallel during the second term of the second year. Effective learning is facilitated by a mixture of lectures covering the necessary concepts and self- directed laboratory experiments allowing active acquisition of problem solving skills. At the end of the project, enthusiastic students can listen to the sound of their MP3 player through the amplifier that results from their teamwork. A survey indicates that the outcomes of the project are in line with the expected results of a problem- and project-based learning environment.

Original articles: Optimal current waveforms for torque control of permanent magnet synchronous machines with any number of phases in open circuit

Polyphase permanent magnet synchronous motors are well suited for electromechanical actuation systems demanding a high level of reliability. They are indeed able to run on a reduced number of phases and therefore to make the actuation system fault tolerant. The paper introduces a Lagrangian formulation for determining the optimal waveforms of the phase currents allowing the motor to develop the needed torque with one or more than one phase lost in open circuit. The method is then adapted to find sub-optimal sinusoidal currents in fault tolerant mode for machines with sinusoidal EMFs. Eventually the paper compares for this type of machine the oversizing imposed for maintaining the performance unchanged in fault tolerant operation mode, with or without imposing to the currents to remain sinusoidal.

Control strategy with minimal controller reconfiguration of fault tolerant polyphase PMSM drives under open circuit fault of one phase

Segment polyphase motors gain interest in applications requiring high performance and high reliability due to their high fault tolerance. This paper sums up the generalization of the vector control strategy of such motor and presents a method to adapt with a minimal reconfiguration the control strategy in the case of an open phase failure. Simulations results validate the method.

Study and optimization of traveling wave generation in finite-length beams

This paper presents a detailed study of the generation of traveling waves in finite-length beams. The method used is the mode superposition. It consists in exciting, with two actuators, two standing waves space shifted of a quarter wavelength and time shifted of a quarter period. Thanks to an analytical model giving the general solution of the flexural wave, we define the ideal conditions ensuring the best quality of this wave across the beam. Then, through an optimization process, we get the excitation parameters, actuator positions and driving frequency, that allow to approach at most these conditions.

Control under normal and fault tolerant operation of multiphase SMPM synchronous machines with mechanically and magnetically decoupled phases

This paper deals with the control of multiphase surface mounted permanent magnet (SMPM) synchronous machines with mechanically and magnetically decoupled phases. As this type of machines is well suited for fault tolerant drives in critical applications as aerospace applications, the paper focuses on the power architecture and torque control strategies allowing to produce an almost ripple free torque both under normal and fault operation. The cases of a five-phase machine and of a six-phase machine are considered.