Alaa Hijazi

Observability-Index-Based Control Strategy for Induction Machine Sensorless Drive at Low Speed

This paper focuses on the observer-based methods for induction machine sensorless drive. It is well known that the use of speed observer is limited at a very low stator frequency due to speed unobservability. Some existing methods propose to avoid the zero-stator-frequency working points. These methods are nonetheless limited to high-torque operations. The first contribution of this paper is to analyze finely the speed observability, which leads to the definition of an observability index. The correlation between this index and the observer performance is analyzed and illustrated. The second contribution is to propose a control strategy that maximizes the observability index and improves the observer performance. The proposed strategy is tested first in open loop to evaluate the speed observer performance, and then, in closed loop to illustrate its pertinence for induction machine sensorless drive. All these results are validated by an experiment. The performed experimentation shows that the proposed control strategy gives better results than the existing method that avoid the zero-frequency working points. It offers a new path for induction machine sensorless drives.

Combinatorial approach for sizing and optimal energy management of HEV including durability constraints

This paper presents a combinatorial approach used to solve an optimization problem including component sizing and energy management control applied to an offroad hybrid electric vehicle with durability constraints. The problem under consideration is the optimization of the hybrid power supply system of an electric mini-excavator. It is composed of a fuel cell system and one energy storage system, i.e includes a lithium battery or a supercapacitors pack. The goal is to minimize the global cost of the machine during its entire working lifetime. In order to fulfill the requirements, an ageing model is included in the original problem to simulate the degradation of the battery and the fuel cell. The paper is focused on the reformulation of the nonlinear original problem into combinatorial subproblems. Then a branch and bound algorithm is applied to solve all sub-problems. Some results are presented to compare the different energy storages configurations.

Balancing circuit control for supercapacitor state estimation

In this paper, an original technique for monitoring the aging of supercapacitor energy storage system is proposed. The aging of supercapacitor is represented by the degradation of its internal parameters as the loss of capacitance and the increase of the Equivalent Series Resistance (ESR). This degradation is continuous until reaching the end of life criteria. The proposed approach is based on estimating the current ESR, of each storage system element with a fast control of the balancing circuit present at the terminal of each storage element. The fast control is applied for a short moment and could be applied at any storage system state with no incidence on the system. The information about this current parameter makes the state of health monitoring possible. The analysis is performed using simulation with realistic storage system models in order to demonstrate and validate the effectiveness and the accuracy of the proposed technique. The results presented covers storage system such as supercapacitor but could be also applied to batteries.

Optimal low-stator-frequency avoidance strategy to improve the performances of induction machine sensorless drives

This paper focuses on speed-sensorless drive of induction machine without signal injection. To ensure good performances of the speed observer without the disruptive effects of signal injection, it is possible to avoid the unobservable working points which lead to poor speed observation. To do so, the existing methods aim at avoiding the low stator frequencies. They are nonetheless difficult to use for real applications since they lack flexibility and do not take into account some industrial constraints. The approach presented in this paper consists in formulating all the working constraints in order to build a cost function. By minimizing this cost function, the proposed optimal avoidance strategy is more flexible and can be applied for any industrial application.

Adaptive sliding mode observer-differentiator for position and speed estimation of Permanet Magnet Synchronous Motor

In this paper, A supertwisting adaptive sliding mode observer - differentiator is proposed to estimate the speed and position of synchronous motor. Experimental tests have been carried out on a test bench and show the pertinence of the proposed scheme.

Online lithium-ion batteries health monitoring using balancing circuits

In this paper, an original online technique for the state of health monitoring of lithium-ion batteries energy storage systems is proposed. The aging of lithium-ion batteries is represented by the degradation of their internal parameters as the decrease of the capacitance and the increase of the Equivalent Series Resistance (ESR). This degradation is continuous over aging until reaching the storage system failure criteria. Thus, the original online technique is based on tracking the ESR representing the battery aging. The proposed approach uses a suitable balancing circuit connected to the terminal of the storage element to extract its actual parameter. The information about this actual parameter makes the state of health monitoring possible. The analysis is performed using simulation with realistic electrical model to demonstrate and validate the effectiveness and the accuracy of the proposed new approach.

Electro-thermal sizing of supercapacitor stack for an electrical bus: Bond graph approach

This paper is devoted to the study of electro-thermal sizing of supercapacitors stack. The application concern the alimentation of trolleybus in case of electrical microcuts that frequently occurs during circulation of the trolleybus. The goal is to size the number of supercapacitor to be implemented knowing the speed and acceleration profile of the trolleybus and to discuss about the thermal performance of the obtained stack. Based on bond graph approach, direct and inverse model of the kinematic chain of trolleybus is developed in order to deduce the consumption of an electrical bus and the braking energy in relation with the speed profile. Validation of direct model has been carried out with experimental results. Then, based on the Ragone plot of supercapacitors, we study the number of supercapacitors needed to recover braking energy and to supply the bus in the case of electrical microcuts. Finally, A bond graph thermal model of the stack is developed and the efficiency of this model is validated based on experimental results on a test bench.

Luenberger observer for SoC determination of lithium-ion cells in mild hybrid vehicles, compared to a Kalman filter

Li-ion batteries are continually developed for a wide range of use. New variants appear on the market, including Li-ion technologies that allow supplying very high electrical power. By consequence, the battery can be used as an energy buffer in vehicles. The autonomy is limited and it is necessary to determine the State of Charge of each element that makes up a battery, although these elements (Li-ion cells) are never fully discharged or charged. In this unusual context, a solution may be to use a Kalman filter at the cost of significant computing power. More computation-wise economical observers can beings used, in particular Luenberger observers. The results obtained for this type of specific use, give similar final results, with a significant gain on the computing power required.

Electrical parameter observation for induction machine sensorless drive using a sensitivity and observability based EKF

This paper focuses on an effective method for both stator and rotor resistance on-line observation of induction machine driven without mechanical speed sensor. These resistances change over a large range with both the temperature and the flux frequency, making on-line adaptation of these parameters necessary to reach a precise speed observer. To do so, the sensitivity of the speed observation with respect to each resistance and the observability of the resistances are analysed in order to define an observation strategy for the stator and rotor resistances for which the resistances are updated only when necessary. HIL experimentations show that the observation precision on the resistances is good and that the speed observation remains precise and stable despite electrical parameter variation.

On speed estimation of permanent magnet synchronous motor using adaptive robust position observer and differentiator

This article concerns a novel method for sensorless speed control of Permanent Magnet Synchrounous Motor based on adaptive supertwisting sliding mode algorithm. This algorithm is used for motor position observation and for the derivation of the position to deduce the speed. The stability is deduced based on the Lyapunov theory. The Experimental tests, carried out on a test bench, show the pertinence of the proposed scheme.