Robust passivity-based control of switched-reluctance motors

International audienceWe propose a state-feedback controller for switched-reluctance motors as a preliminary step towards the solution of the sensorless control problem (without measurement of rotor variables). We establish global exponential stability. Furthermore, our controller renders the closed-loop system robust to external disturbances that is, input-to-state stable. Although there exist some works on sensorless control of switched-reluctance motors, these consist mainly on ad hoc solutions without theoretical foundation. The few theoretically-validated results in the literature are established under more stringent conditions such as knowledge of the load torque

Velocity-sensorless tracking control and identification of switched-reluctance motors

International audienceWe present a solution to the speed sensorless control problem for switched-reluctance motors under parametric uncertainty. Our main results guarantee velocity tracking control for velocity references with constant reference acceleration under the assumption that the load torque, the rotor inertia, the resistance and inductances are unknown. Under a persistency of excitation condition on a function which depends only on reference trajectories, we guarantee uniform global asymptotic stability therefore, we establish conditions for the identification of the physical parameters of the system. Our theoretical findings are supported by illustrative simulation results

Exponential stabilization of switched-reluctance motors via speed-sensorless feedback

International audienceWe solve the control problem of switched-reluctance motors without velocity measurements. Our controller is composed of a loop in the mechanical dynamics which consists of a PI2 D controller and a "tracking" controller closing an inner loop with the stator currents dynamics. The PI2 D controller consists in a linear proportional derivative controller in which the measurement of velocities is replaced by approximate derivatives of angular position. Then a double integrator is added, composed of an integral of the angular position errors and a second integral correction term in function of the approximate derivative. We show global exponential stability and illustrate the performance of our controller in numerical simulations

A novel PID-based control approach for switched-reluctance motors

International audienceWe propose a control strategy for switched-reluctance motors with unknown load, which consists in two separate control loops, for the rotor (mechanical) dynamics and the stator (electrical) dynamics. The novelty of the approach resides in using an alternative rotor model which corresponds to that of an harmonic oscillator hence, it is linear in the rotation coordinates. The control law is of proportional-integral-derivative type and it is implemented through a virtual control input, generated via the mechanical torque of electrical origin. A second control loop is closed around the stator dynamics via a current tracking controller. As far as we know, we establish for the first time global exponential stability considering that the load torque is unknown

Chattering-Free Robust Adaptive Sliding Mode Speed Control for Switched Reluctance Motor

This study describes an adaptive sliding mode control (ASMC) for the control of switched reluctance motor (SRM). The main objective is to minimize torque ripples with controller effort smoothness while the system is under perturbation by structured uncertainties, unknown parameters, and external disturbances. The control algorithm employs an adaptive approach to remove the need for prior knowledge within the bound of perturbations. This is suitable for tackling the chattering problem in the sliding motion of ASMC. In order to achieve control effort smoothness and more effective elimination of chattering, the algorithm then incorporates proper modifications in order to build a chattering-free robust adaptive sliding mode control (RASMC) using Lyapunov stability theory. A final advantage of the algorithm is that system stability and error convergence are guaranteed. The effectiveness of the proposed controller in improving robustness and minimizing ripples is demonstrated by numerical simulation. Experimental validation is used to demonstrate the efficiency of the proposed scheme. The results indicate that RASMC provides a superior performance with respect to speed tracking and disturbance rejection over the conventional sliding mode control (CASMC) in the face of uncertainties in model and dynamic loads

Speed-sensorless control of switched-reluctance motors with uncertain payload

International audienceWe present a controller for switched-reluctance motors without velocity measurements and provide, to the best of our knowledge, the first result establishing global exponential stability. Our controller is composed of an "internal" tracking control loop for the stator dynamics and an "external" control loop based on the so-called PI2 D controller. The latter consists in a linear proportional derivative controller in which the mea- surement of velocities is replaced by approximate derivatives. Furthermore, a double integrator is added to compensate for the load uncertainty. We illustrate our theoretical findings with numerical simulations

Reducing the sampling frequency for the control of the switched reluctance machine

This paper presents two solutions for dramatically reduce the sampling frequency and therefore the CPU demand while keeping the same performance in terms of torque ripple and efficiency on a SRM. The problem of a low sampling frequency with a regular control is first highlighted. Then, two different solutions are proposed for the self switching's function. Such solutions tries to magnetize the stator phase at an accurate instant in order to reduce the inherent torque ripple. Simulations results on a 8/6 SRM corroborate the validity of the proposed solutions and show the improvements of its performance.Peer ReviewedPostprint (author’s final draft

Velocity Regulation in Switched Reluctance Motors under Magnetic Flux Saturation Conditions

We propose a controller for velocity regulation in switched reluctance motors under magnetic flux saturation conditions. Both hysteresis and proportional control are employed in the internal electric current loops. A classical PI velocity controller is employed in the external loop. Our control law is the simplest one proposed in the literature but provided with a formal stability proof. We prove that the state is bounded having an ultimate bound which can be rendered arbitrarily small by a suitable selection of controller gains. Furthermore, this result stands when starting from any initial condition within a radius which can be arbitrarily enlarged using suitable controller gains. We present a simulation study where even convergence to zero of velocity error is observed as well as a good performance when regulating velocity in the presence of unknown step changes in external torque disturbances