Kamel Ben Saad

On an internal multimodel control for non-linear systems: a comparative study

An approach to internal model controller synthesis for non-linear systems is proposed in this paper. This approach is based on the multimodel modelling of non-linear systems and the realisation of a specific inverse of each model. The inversion of each model is necessary in the internal model controller design. A comparative study is presented between two structures of internal multimodel controller for non-linear control system based on two different fusion methods. The first one is based on the switching methods and the second one is based on the residues techniques. The case of a non-linear system is presented to show the effectiveness of these control structures and to compare these structures of internal multimodel control of this non-linear system.

Robust Adaptive Control for a Class of Nonlinear Systems Using the Backstepping Method

This paper develops a robust adaptive control for a class of nonlinear systems using the backstepping method. The proposed robust adaptive control is a recursive method based on the Lyapunov synthesis approach. It ensures that, for any initial conditions, all the signals of the closed-loop system are regularly bounded and the tracking errors converge to zero. The results are illustrated with simulation examples.

Sliding Mode Control and Fuzzy Sliding Mode Control for DC-DC Converters

Switched mode DC-DC converters are electronic circuits which convert a voltage from one level to a higher or lower one. They are considered to be the most advantageous supply tools for feeding some electronic systems in comparison with linear power supplies which are simple and have a low cost. However, they are inefficient as they convert the dropped voltage into heat dissipation. The switched-mode DC-DC converters are more and more used in some electronic devices such as DC-drive systems, electric traction, electric vehicles, machine tools, distributed power supply systems and embedded systems to extend battery life by minimizing power consumption (Rashid, 2001). There are several topologies of DC-DC converters which can be classified into non-isolated and isolated topologies. The principle non-isolated structures of the DC-DC converters are the Buck, the Buck Boost, the Boost and the Cuk converters. The isolated topologies are used in applications where isolation is necessary between the input and the load. The isolation is insured by the use of an isolating transformer. The DC-DC converters are designed to work in open-loop mode. However, these kinds of converters are nonlinear. This nonlinearity is due to the switch and the converter component characteristics. For some applications, the DC-DC converters must provide a regulated output voltage with low ripple rate. In addition, the converter must be robust against load or input voltage variations and converter parametric uncertainties. Thus, for such case the regulation of the output voltage must be performed in a closed loop control mode. Proportional Integral and hysteretic control are the most used closed loop control solutions of DC-DC converters. This can be explained by the fact that these control techniques are not complicated and can be easily implemented on electronic circuit devises. Nowadays, the control systems such as microcontrollers and programmable logic devises are sophisticated and allow the implementation of complex and time consuming control techniques. The control theory provides several control solutions which can be classified into conventional and non-conventional controls. Many conventional controls, such as the PID control, were applied to DC-DC converters. The design of the linear controller is based on the linearized converter model around an equilibrium point near which the controller gives

HIL simulation of a DC-DC converter controller on a Zynq

Hardware-in-the-loop (HIL) is known as an efficient simulation approach allowing the test of control systems before implementation, where some of the control-loop components are implemented in real hardware device and some are simulated. Typical, ordinary Input/Output ports are used as an interface between the plant simulation and the embedded system under test. However, this kind of communication can create a time delay between control system and plant model, making the system unstable. As a solution, we propose in this paper to implement all the control-loop in a Xilinxs Zynq System-on-Chip (SoC). By building the plant in the Processor Subsystem (PS) and implementing the controller in Programmable Logic (PL), the ordinary I/O interface is avoided. As an example of system, a digital PI regulator applied to a Buck converter is studied. The controller structure is implemented in the (PL) and the buck converter is simulated in the (PS).

Position sensorless control of a permanent magnet stepping motor based on a nonlinear observer

This paper presents a position sensorless control of a stepping motor based on a proportional derivative control. The proposed control allows the elimination of the studied actuator position oscillations. The motor speed and position are determined from the motor position back EMF voltages which are estimated by a nonlinear Lipschitz observer by detecting the statoric voltages and currents. The proposed solution avoids the use of a position sensor which is expensive and cumbersome. The simulation results prove the efficiency of the proposed approach.

A BLDC fault diagnosis approach based on a super-twisting sliding mode observer

A short circuit between the stator winding turns is one of the most common faults affecting electrical motors. It can rapidly evolve to more serious faults causing significant degradation of the performance of the machine. This paper investigates inter-turns short circuit fault diagnosis in brushless direct-current (BLDC) motors. A fault diagnosis approach based on a super twisting sliding mode observer is presented. The effectiveness of the proposed diagnosis method is demonstrated by numerical simulations.

Influence of the variation of the boost converter parameters on the bifurcation phenomenon

This paper deals with bifurcation analyses in current programmed DC/DC Boost converter and exhibition of chaotic behavior. This phenomenon occurs due to variation of a set of the studied circuit parameters (input voltage and a reference current). Two different kinds of bifurcation paths have been observed as part of another bifurcation, arising from variation of suitable chosen parameter.