Ralph Kennel | TUM - Academia.edu (original) (raw)

Papers by Ralph Kennel

World Congress on Engineering, 2009

Bulletin of The Polish Academy of Sciences-technical Sciences, 2006

arXiv (Cornell University), Nov 25, 2012

2023 IEEE International Conference on Predictive Control of Electrical Drives and Power Electronics (PRECEDE)

IEEE Open Journal of Power Electronics

2022 IEEE 13th International Symposium on Power Electronics for Distributed Generation Systems (PEDG)

2019 21st International Middle East Power Systems Conference (MEPCON)

In this paper, a simplified robust method for encoderless finite control set predictive current c... more In this paper, a simplified robust method for encoderless finite control set predictive current control (FCSPCC) for synchronous reluctance motor (SRM) is suggested, discussed, and simulated. The predictive current control replaces the conventional PI current controllers used in field oriented control to a strategy that uses a discrete model for SRM which predicts the future values of the currents for all the possible switching vectors for two-level inverter. Furthermore, the cost function is performed to select the optimal switching vector to apply in the next sampling interval. Additionally, PCC establishes a convergence mechanism to follow the reference values of the desired speed. For encoderless control, Extended Kalman filter (EKF) is composed in the rotating reference frame to estimate the position and speed of the rotor and the currents for SRM. Those estimated values are fed back into the predictive model. To demonstrate its feasibility, the presented control is executed through MATLAB/Simulink during different speed area including zero and reversal speed. Simulation results show high robustness and reliability of the drive with low harmonic distortion (THD).

IEEE Transactions on Power Electronics

2021 23rd European Conference on Power Electronics and Applications (EPE'21 ECCE Europe)

In this study, the Imperialist Competitive Algorithm (ICA) is used to optimize the gains of the c... more In this study, the Imperialist Competitive Algorithm (ICA) is used to optimize the gains of the cascaded position controller. Brushless DC (BLDC) motor drives with FOC and trapezoidal control structure are implemented in Simulink environment to provide an evaluation function of ICA. In this paper, a brief discussion has been conducted regarding the selection of settings and coefficients of ICA. Simulation results show that the optimized speed and position controller tracks the target speed and target position appropriately. Also, the effectiveness of ICA is verified by performance comparison of ICA, PSO, and GA in this paper.

2021 IEEE 12th Energy Conversion Congress & Exposition - Asia (ECCE-Asia), 2021

This article proposes an assessment of constrained parallel structure predictive torque control (... more This article proposes an assessment of constrained parallel structure predictive torque control (PPTC) with parameter robustness improvement for induction machine (IM) drive fed by voltage source inverter (VSI). Due to the inherent weakness of weighting factor determination in conventional PTC scheme, the proposed PPTC employs the objective terms to be constrained in the boundaries, and then voltage vectors (VVs) are carried out in an adaptive selection mechanism. Therefore, the exploratory process of parameter tuning is not required. However, the parallel structure in its optimization stage is penalized by the parameter variation in the control plant. To solve this problem, a sliding-mode disturbance observer (SMDO) is used for the robustness enhancement of the proposed scheme to parameter mismatch. Experimental validations are conducted to confirm the effectiveness of the proposed disturbance observer and reduced parameter sensitivity of the robust PPTC methodology.

IEEE Transactions on Industrial Electronics, 2022

Finite control set model predictive control (FCS-MPC) has been widely recognized in the field of ... more Finite control set model predictive control (FCS-MPC) has been widely recognized in the field of electrical drive control during the past decades, due to its merits of quick dynamic response and low switching frequency. However, it is inherently penalized by high tracking deviations in the steady-state as well as exhaustive search among the switching sequences. To cope with this issue, a low-complexity gradient descent-based finite control set predictive current control (GD-FCSPCC) combined with a backtracking iteration approach is proposed in this article, aiming to improve the control performance by effectively tracking the reference value. First, FCS-PCC is reformulated as a quadratic programming (QP) problem from a geometric perspective. Consequently, the convexity of QP problem is proved to underlying the gradient descent, which minimizes the tracking deviations in an effective manner. Thus, the optimal solutions are selected by optimizing the reformulated objective functions. To reduce the number of the searched control inputs, a two-layer generalized decision-tree is employed. The procedures are repeated in several iteration periods optimized via a backtracking method, until the stopping criterion is satisfied. The effectiveness of the proposed GD-FCSPCC is experimentally validated on a 2.2 kW induction machine testbench.

IET Power Electronics, 2021

2019 IEEE International Symposium on Predictive Control of Electrical Drives and Power Electronics (PRECEDE), 2019

This work introduces an efficient finite-position-set model-reference adaptive system (FPS-MRAS) ... more This work introduces an efficient finite-position-set model-reference adaptive system (FPS-MRAS) estimator for sensor-less control of a doubly fed induction generator (DFIG) in a variable speed wind energy conversion system (WECS). The idea of the proposed FPS-MRAS is derived from the finite-control-set model predictive control (FCS-MPC) principle, i.e. a limited set of angles for the rotor position are employed to predict the rotor current of the DFIG. Subsequently, the optimal angle for the rotor position is the one that its prediction optimizes a pre-defined (novel) quality function. Accordingly, the constant-gain proportional-integral (CG-PI) regulator and its tedious tuning which is normally used in MRAS observers is not required. The estimation response of the suggested FPS-MRAS observer is investigated by experiments and compared with the performance of the classical MRAS under different operation conditions and at variations of the DFIG parameters.

2019 IEEE International Electric Machines & Drives Conference (IEMDC), 2019

This work closely investigates the generalized relationship among the four popular control method... more This work closely investigates the generalized relationship among the four popular control methods using Finite-Control-Set Model Predictive Control (FCS-MPC)concept for voltage source power converter fed PMSM drivers. The as-investigated control methods include: direct model predictive torque control (DMPTC)in dqdqdq frame, direct model predictive current control (DMPCC)in dqdqdq frame, direct model predictive current control (DMPCC)in alphabeta\alpha\betaalphabeta frame and direct model predictive flux control (DMPFC)in alphabeta\alpha\betaalphabeta frame. Our conclusion is that, for nonsaliency based PMSM, DMPTC, DMPCC (both in alphabeta\alpha\betaalphabeta and dqdqdq frames), DMPFC are theoretically equivalent in achieving the control targets. However, realization effort and computational demands, i.e., the amount calculation required, are different.

2018 International Power Electronics Conference (IPEC-Niigata 2018 -ECCE Asia), 2018

In this paper, a finite control set model predictive control (FCS-MPC) method for three-level neu... more In this paper, a finite control set model predictive control (FCS-MPC) method for three-level neutral-point-clamped (3L-NPC) rectifiers without the outer control loop is presented. The proposed control method is very simple as only a sliding manifold term is added into the cost function to regulate the dc-bus voltage directly. Instead of calculating the suitable dynamic references, only the steady-state references are required in this method. Besides, we have compared the conventional proportional-integration controller based MPC method (PI-MPC), MPC with dynamic references design method (DR-MPC), and the proposed MPC with a sliding manifold term method (SM-MPC) with simulation. The simulation results show that the proposed SM-MPC outperforms the PI-MPC in the condition of the step change in load and has advantage over the DR-MPC when the voltage reference changes.

2018 IEEE International Power Electronics and Application Conference and Exposition (PEAC), 2018

A sequential direct model predictive control (SDMPC) for the grid-tied three-level neutral-point ... more A sequential direct model predictive control (SDMPC) for the grid-tied three-level neutral-point clamped (3L-NPC) converters is proposed in this work. For the underlying 3L-NPC grid-tied power converter, control objectives are active/reactive current tracking and neutral-point voltage balance. The proposed solution utilized two cascaded cost functions, dealing with the above control objectives in a sequential manner without using weighting factors, such that the tedious parameter tuning process is eliminated. It is different from the classical direct model predictive control (CDMPC), which combines both control objectives into a single cost function with a tunable penalty coefficient, i.e., the weighting factor. A thorough comparison investigation between CDMPC and the proposed method was carried out. The simulation results showed that both methods achieve comparably good performance. While SDMPC considerably reduces the tuning efforts, and simplifies the engineering design process.