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- Predictive Torque Control of SynRM Drives with online MTPA Trajectory Tracking and Inductances EstimationPublication . Hadla, Hazem; Cruz, Sérgio; Varatharajan, AnantaramThis paper proposes a new predictive torque control algorithm for synchronous reluctance motor drives with the ability to track online the maximum torque per ampere trajectory. An additional term is included in the cost function of the predictive control algorithm which uses an adaptive weighting factor to improve the dynamic behavior of the drive system. As the derivative of torque with respect to the current angle depends on the values of the apparent and incremental inductances, the apparent inductances are estimated online based on the values of the flux linkage and current components while the incremental inductances are estimated using a recursive least squares (RLS) algorithm. Experimental results validate the proposed control algorithm and demonstrate a remarkable performance both in steady-state and during transients, as well as a reduction of the current ripple and audible noise.
- ENERGY MANAGEMENT ALGORITHM FOR END INSTALLATIONS WITH RENEWABLE PRODUCTION AND STORAGEPublication . Santos, Fernando; Hadla, HazemThis paper presents an algorithm to manage different renewable energy sourceswith storage. The objective of this algorithm is to regulate and control the outputcurrents of the DC-DC converters, which are directly connected to both the DC bus andthe inverter. Here, the inverter allows exchanging the energy between the DC bus andthe AC grid. The implementation of the proposed algorithm to end facilities in aliberalized market is also presented and tested. In addition, the benefits of suchimplementation, using eight dispatches, to the operators of the grid is demonstrated.The algorithm considers several situations of the consumption, energy production,various storage capacities, grid manager's demands, forecasts of production andconsumption loads. The results, which are obtained by the proposed algorithm, show agood regulation and control of the currents of the DC-DC converters, therefore a betterenergy management is achieved being this supported by an extensive theoretical analysis.
- Predictive Stator Flux and Load Angle Control of Synchronous Reluctance Motor Drives Operating in a Wide Speed RangePublication . Hadla, Hazem; Cruz, SérgioThis paper presents a new simplified finitecontrol- set model predictive control strategy for synchronous reluctance motors operating in the entire speed range. It is a predictive control scheme that regulates the stator flux and the load angle of the synchronous reluctance motor, incorporating the ability to operate the drive in the field-weakening region and respecting the motor voltage and current limits as well as the load angle limitation needed to operate this type of motor in the maximum torque per voltage region. The proposed control strategy possesses some attractive features, such as no need for controller calibration, no weighting factors in the cost function, good robustness against parameter mismatch, and smaller computational cost compared to more traditional finite-control-set model predictive control algorithms. Simulation and experimental results obtained using a high-efficiency synchronous reluctance motor demonstrate the effectiveness of the proposed control scheme.
- An encoderless high-performance synchronous reluctance motor drivePublication . Hadla, Hazem; Cruz, Sérgio; Oliveira, Álvaro; Cavaleiro, Diogo; Branco, RicardoThis paper presents an encoderless high-performance synchronous reluctance motor drive for traction applications. The control system is based on the active flux concept and a hybrid rotor position estimation algorithm is used, being this algorithm based on the injection of high-frequency signals at low speeds and on the position of the active flux vector for medium and high-speeds. A smooth transition algorithm between the two rotor position estimation methods is provided. Moreover, in order to improve the efficiency of the overall drive system, a loss minimization algorithm is proposed in order to reduce the motor copper losses when operating in steady-state. Experimental results obtained in the laboratory confirm the validity and adequacy of the proposed algorithms for the developed drive system.
- Active Flux Based Finite Control Set Model Predictive Control of Synchronous Reluctance Motor DrivesPublication . Hadla, Hazem; Cruz, SérgioThis paper presents two new finite control set model predictive control (FCS-MPC) strategies for synchronous reluctance motor (SynRM) drives, using the active flux concept. Both control strategies guarantee a fast and independent control of the torque and active flux of the SynRM, in order to obtain a high performance drive. The first strategy relies on a more conventional implementation of a FCS-MPC algorithm, which requires some effort to tune the weighting factors used in the cost function. The second control approach corresponds to a simplification of the first one, and allows a reduction of the calculation time associated to the predictions stage of the algorithm and, at the same time, avoids the use of weighting factors in the cost function. This allows to simplify the implementation of the control system, obtaining the same dynamic performance as with the first strategy. Experimental and simulation results verify the validity and effectiveness of the two proposed control schemes for SynRM drives. Furthermore, a state-of-the-art control technique like direct torque control is also considered in the paper, for performance comparison purposes.
- Parameter Identification for Simplfied Set Current Predictive Control of SynRM DrivesPublication . Hadla, Hazem; Santos, FernandoIn this work, a simplified finite set current predictive control (FS-CPC) is presented for the synchronous reluctance motor (SynRM) drive due to its fast response and simplicity. However, the prediction model of this control is obtained from a mathematical model of the motor which contains many parameters, and thus any parametric uncertainly might lead to inaccuracies of the predictive algorithm. Therefore, the online identification of the stator resistance, and inductances of the motor are implemented using the recursive least square (RLS) technique. The identification method is built in Matlab/Simulink, and the obtained simulation results reveal its strong accuracy and effectiveness. Thus, the estimation technique is seen as a good option to be selected and combined with the simplified FS-CPC of the SynRM.
- Predictive Load Angle and Stator Flux Control of SynRM Drives for the Full Speed RangePublication . Hadla, Hazem; Cruz, Sérgio Manuel Ângelo daNowadays, several types of electric motors are utilized in industrial applications, namely induction motors (IMs), permanent magnet synchronous motors (PMSMs) and synchronous reluctance motors (SynRMs). Owing to the high cost of PMSMs and due to the rotor losses of IMs, SynRMs can be considered an ideal choice for some applications. These motors have a simple structure, are robust, and have a low cost due to the absence of permanent magnets or windings in the rotor. To exploit the advantages of SynRM drives, an adequate control strategy is essential. In recent times, due to the development of fast and cheap microprocessors and FPGAs, the category of control strategies known as finite control set model predictive control (FCS-MPC) has attracted significant attention in both academia and industry. FCS-MPC has as main advantages, an intuitive and simple implementation, very fast dynamic response and the ability to tackle several constraints in a straightforward manner. Due to these advantages, it can be considered an ideal alternative to field-oriented control (FOC) and direct torque control (DTC) in high performance motor drives. In spite of its advantages, FCS-MPC has been barely proposed for the control of SynRM drives, especially if we consider that some applications require the drive system to operate in the full speed range. This thesis proposes three different FCS-MPC control strategies for high-performance SynRM drives. The first two control strategies combine the concepts of active flux and torque control in order to operate the SynRM in the constant torque region. The first control strategy, baptized as predictive active flux and torque control (PAFTC), regulates the active flux and the electromagnetic torque of the SynRM in an independent manner. It follows the standard implementation steps of FCS-MPC, namely by predicting the values of the state variables for all possible switching states of the inverter, and by using a cost function with a weighting factor which needs to be tuned. A second control approach, known as simplified PAFTC (S-PAFTC), is a simplified version of the PAFTC in the sense that the predictions of the state variables are replaced by the calculation of an equivalent reference voltage, performed only once in a sampling period. This procedure leads to a smaller computational time, when the control strategy is implemented in a digital control platform, and to the use of a cost function without any weighting factor, overcoming one of the challenging tasks in classical FCS-MPC strategies which is the choice of the optimal value(s) for the weighting factor(s). The simulation and experimental results obtained with these control strategies demonstrate the very good steady-state and dynamic response of the SynRM drive in the constant torque region. With the aim to safely operate the SynRM drive in the full speed range, while ensuring at the same time the exploitation of all its potentialities and limits, including its operation with optimal efficiency, a third control strategy, known as predictive load angle and stator flux control (PLASFC), is proposed for SynRM drives. The PLASFC, implemented in a stator flux reference frame, regulates the stator flux and the load angle of the SynRM in an independent manner. While the stator flux regulation is straightforward, the torque is regulated indirectly by controlling the load angle, bringing benefits in terms of a smooth transition between the different motor operating regions. Similarly to the S-PAFTC strategy, an equivalent reference voltage is calculated instead of predicting the values of the motor state variables for all possible switching states of the inverter, and the cost function does not include any weighting factor. In the PLASFC strategy, the SynRM is easily operated in the full speed range: constant torque region (including zero speed), constant power region and constant load angle region, the last two being part of what is usually known as field-weakening (FW) region. With this control strategy, the voltage, current and load angle limits are easily exploited by simple mathematical relations and saturation blocks. In addition, a loss minimization algorithm is developed and incorporated in this control strategy thus allowing to operate the SynRM with minimum copper losses for a given load torque. Furthermore, to improve the performance of the control system, some parameters namely the motor apparent inductances, are estimated online. Several simulation and experimental results presented demonstrate the excellent steady-state and dynamic performance of the SynRM drive when operating with the PLASFC strategy, thus clearly demonstrating the benefits of using FCS-MPC strategies in the field of electric drives in general and SynRM drives in particular.