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Pavel Karlovsky
Department of Electric Drives and Traction, Czech Technical University in Prague, 160 00 Prague, Czech Republic

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Journal article
Published: 23 March 2021 in Applied Sciences
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The current and torque ripple of inverter-fed induction motor drives is an inherent problem of control strategies working with switching frequencies in the range of multiple kilohertz, such as direct torque and, more recently, predictive torque control. If the drive operates in a wide-speed and wide-torque range and is equipped with a machine with an accessible terminal block whose winding is nominally connected in delta, then the current and torque ripple can be reduced by utilizing the delta-star winding changeover technique. When the winding configuration is switched from delta to star, the instantaneous motor phase voltage peak is lowered, and its total harmonic distortion is reduced. However, the control strategy must be adjusted according to the actual winding topology, mainly due to the difference in the coordinate transformations of the measured currents and the difference between the phase voltage vectors obtained from the inverter. This paper proposes a predictive torque control of an induction motor drive with a switchable delta-star winding configuration. The paper is supported by theoretical background, and the key idea is verified by simulations in MATLAB/Simulink and experiments conducted on a dSPACE-controlled 5.5-kW laboratory drive. The simulations validated the presented equations and show the effects of not respecting the actual winding topology. The experiments mainly focused on analyzing the total harmonic distortion of the currents and consumed electrical power in multiple operating points.

ACS Style

Ondrej Lipcak; Pavel Karlovsky; Pavel Kobrle; Jan Bauer. Current Ripple Reduction of Predictive Torque-Controlled Induction Motor Drive Using Delta-Star Switchover. Applied Sciences 2021, 11, 2863 .

AMA Style

Ondrej Lipcak, Pavel Karlovsky, Pavel Kobrle, Jan Bauer. Current Ripple Reduction of Predictive Torque-Controlled Induction Motor Drive Using Delta-Star Switchover. Applied Sciences. 2021; 11 (6):2863.

Chicago/Turabian Style

Ondrej Lipcak; Pavel Karlovsky; Pavel Kobrle; Jan Bauer. 2021. "Current Ripple Reduction of Predictive Torque-Controlled Induction Motor Drive Using Delta-Star Switchover." Applied Sciences 11, no. 6: 2863.

Research article
Published: 24 September 2020 in IET Power Electronics
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This study proposes a new method leading to a reduction in the current and torque ripple of an induction motor (IM) drive controlled by predictive torque control (PTC). The method lies within the optimisation of a DC-link voltage magnitude by the PTC cost function. Using a three-phase silicon-controlled rectifier, the DC-link voltage can be adjusted in such way that the current and torque ripple, caused mainly by treating the inverter as a source of only eight voltage vectors, is significantly reduced. The DC-link optimisation algorithm is integrated into the PTC that is used for the torque and flux control. In another prediction stage, the influence of the DC-link voltage on the torque and flux ripple is directly evaluated and then optimised by a second cost function. The theoretical analysis of the DC-link voltage influence on the drive behaviour is supported by simulation and experimental results conducted on a 5.5 kW IM drive, which confirm the benefits of the PTC with the DC-link voltage optimisation, especially if the drive operates in a region below the nominal speed.

ACS Style

Pavel Karlovsky; Ondrej Lipcak; Jan Bauer; Jiri Lettl. Predictive torque control of induction motor with integrated DC‐link voltage optimisation. IET Power Electronics 2020, 13, 3396 -3406.

AMA Style

Pavel Karlovsky, Ondrej Lipcak, Jan Bauer, Jiri Lettl. Predictive torque control of induction motor with integrated DC‐link voltage optimisation. IET Power Electronics. 2020; 13 (15):3396-3406.

Chicago/Turabian Style

Pavel Karlovsky; Ondrej Lipcak; Jan Bauer; Jiri Lettl. 2020. "Predictive torque control of induction motor with integrated DC‐link voltage optimisation." IET Power Electronics 13, no. 15: 3396-3406.

Conference paper
Published: 11 August 2020 in Lecture Notes in Electrical Engineering
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Most of the control algorithms of variable speed drives with induction motor require the knowledge of the stator voltage vector applied to the motor terminals. This vector is usually reconstructed from the known microcontroller’s PWM signals or the commanded voltage for the inverter is used within the control algorithm. However, these solutions require a DC-link voltage sensor and compensation of the nonlinear inverter behavior. In this paper, stator voltage estimator based on the Extended Kalman filter is proposed. This approach requires neither the knowledge of the DC-link voltage nor the nonlinear model of the inverter. Only the knowledge of the stator currents and the rotational speed is needed. The proposed estimator is verified within the simulation of predictive-torque control of induction motor drive in Matlab Simulink where the comparison of the applied and the estimated voltage vector is presented along with their harmonic analysis. The accuracy of the estimated voltage vector shows its suitability for further inverter nonlinearities investigation.

ACS Style

Pavel Karlovsky; Ondrej Lipcak; Jiri Lettl. Estimation of Stator Voltage of Inverter-Supplied Induction Motor Using Kalman Filter. Lecture Notes in Electrical Engineering 2020, 64 -73.

AMA Style

Pavel Karlovsky, Ondrej Lipcak, Jiri Lettl. Estimation of Stator Voltage of Inverter-Supplied Induction Motor Using Kalman Filter. Lecture Notes in Electrical Engineering. 2020; ():64-73.

Chicago/Turabian Style

Pavel Karlovsky; Ondrej Lipcak; Jiri Lettl. 2020. "Estimation of Stator Voltage of Inverter-Supplied Induction Motor Using Kalman Filter." Lecture Notes in Electrical Engineering , no. : 64-73.

Journal article
Published: 30 March 2020 in TRANSACTIONS ON ELECTRICAL ENGINEERING
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Recently, the induction motor drives have become very popular in the area of controlled drives. Nowadays, a great effort is put on increasing their efficiency. The most widely used control method is the direct torque control (DTC). However, this method suffers from the torque ripple and current waveform distortion. The modification using predictive algorithms is becoming a popular approach. This paper presents a predictive control on the dSPACE DS1103 system and compares the method with DTC.

ACS Style

Pavel Karlovský; Jiří Lettl. Predictive Control of Induction Motor Drive Using dSPACE Platform. TRANSACTIONS ON ELECTRICAL ENGINEERING 2020, 6, 1 .

AMA Style

Pavel Karlovský, Jiří Lettl. Predictive Control of Induction Motor Drive Using dSPACE Platform. TRANSACTIONS ON ELECTRICAL ENGINEERING. 2020; 6 (2):1.

Chicago/Turabian Style

Pavel Karlovský; Jiří Lettl. 2020. "Predictive Control of Induction Motor Drive Using dSPACE Platform." TRANSACTIONS ON ELECTRICAL ENGINEERING 6, no. 2: 1.

Journal article
Published: 28 March 2020 in Electronics
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Today’s modern control strategies of an induction motor (IM) drive require a power source with an adjustable output voltage frequency and amplitude. The most commonly used converter topology is a two-level voltage-source inverter (VSI). However, the utilization of a VSI introduces additional voltage and current distortion, which leads to additional power losses in the machine’s magnetic circuit. Both the transistor switching frequency and the type of the inverter control determine the total harmonic distortion (THD) of the motor’s phase currents. In this paper, the influence of the inverter DC-link voltage on the iron losses of an IM controlled by a predictive torque control (PTC) is presented. It is shown that if the IM drive operates below the rated speed, it is possible to modify the PTC algorithm to reduce the additional iron losses caused by the non-harmonic inverter output voltage. The control of the DC-link voltage is achieved by using a silicon-controlled rectifier. Experiments were conducted on a 5.5 kW IM controlled by PTC, and the results are compared against a sinusoidal voltage supply created by a synchronous generator.

ACS Style

Pavel Karlovsky; Ondrej Lipcak; Jan Bauer. Iron Loss Minimization Strategy for Predictive Torque Control of Induction Motor. Electronics 2020, 9, 566 .

AMA Style

Pavel Karlovsky, Ondrej Lipcak, Jan Bauer. Iron Loss Minimization Strategy for Predictive Torque Control of Induction Motor. Electronics. 2020; 9 (4):566.

Chicago/Turabian Style

Pavel Karlovsky; Ondrej Lipcak; Jan Bauer. 2020. "Iron Loss Minimization Strategy for Predictive Torque Control of Induction Motor." Electronics 9, no. 4: 566.

Conference paper
Published: 13 April 2019 in Lecture Notes in Electrical Engineering
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In a small autonomous power system, the electric power is usually produced by means of an electric machine operated as a generator. The often used one is an induction generator. The generator supplies the DC-link through the controlled converter (voltage source inverter – VSI). The appliances connected to the same DC-link consume power and therefore the DC-link capacitor is discharged. To maintain the decreasing DC-link voltage level, the same power amount must be delivered by the generator. In case of the induction generator, its control is specific as no external source for machine excitation is present. To obtain the torque value desired by the DC link voltage PID controller, the generator is usually controlled by the field-oriented control (FOC) method or direct torque control (DTC) method. However, the model predictive control (MPC) method has been utilized for electric machine control in recent time. The paper explores the possibility of employing the predictive torque control (PTC), which is often used implementation of MPC in this type of applications. The PTC method ability to control the DC-link voltage in a small autonomous power system has been verified experimentally on a laboratory system with induction generator.

ACS Style

Pavel Karlovsky; Jiri Lettl. Capability of Predictive Torque Control Method to Control DC-Link Voltage Level in Small Autonomous Power System with Induction Generator. Lecture Notes in Electrical Engineering 2019, 769 -777.

AMA Style

Pavel Karlovsky, Jiri Lettl. Capability of Predictive Torque Control Method to Control DC-Link Voltage Level in Small Autonomous Power System with Induction Generator. Lecture Notes in Electrical Engineering. 2019; ():769-777.

Chicago/Turabian Style

Pavel Karlovsky; Jiri Lettl. 2019. "Capability of Predictive Torque Control Method to Control DC-Link Voltage Level in Small Autonomous Power System with Induction Generator." Lecture Notes in Electrical Engineering , no. : 769-777.

Conference paper
Published: 01 August 2018 in 2018 IEEE 18th International Power Electronics and Motion Control Conference (PEMC)
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Most of the railway traction vehicles are moved thanks to the transfer of traction, braking force by small contact area between wheels and rail (steal to steal contact). The ability of force transfer by contact area or also the sum of the contact area physical properties is called adhesion. In order to utilize maximum transferable force, a slip controller has to be added into traction drive control structure. Slip control method based on the adhesion slope characteristic detection requires addition of sweep signal into reference torque command. The sweep signal should have particular frequency and amplitude to ensure proper signal detection and thus slip controller function. This is simple for low power drives with relatively high modulation frequency of the traction inverter, but becomes complicated for high power drive with low switching frequency of the semiconductor devices. The paper studies possibility of the Model Predictive Control (MPC) strategy application to support the slip controller function. The considered slip controller is based on the speed and current response of the torque reference signal injection. Therefore, the controller requires high torque control accuracy. Results of MPC are compared with the Direct Torque Control (DTC) strategy that is often used for control of high power drives with induction motor (IM).

ACS Style

Pavel Karlovský; Jan Bauer. Wheel slip determination capability of locomotive driven by model predictive control. 2018 IEEE 18th International Power Electronics and Motion Control Conference (PEMC) 2018, 1 -6.

AMA Style

Pavel Karlovský, Jan Bauer. Wheel slip determination capability of locomotive driven by model predictive control. 2018 IEEE 18th International Power Electronics and Motion Control Conference (PEMC). 2018; ():1-6.

Chicago/Turabian Style

Pavel Karlovský; Jan Bauer. 2018. "Wheel slip determination capability of locomotive driven by model predictive control." 2018 IEEE 18th International Power Electronics and Motion Control Conference (PEMC) , no. : 1-6.

Journal article
Published: 08 July 2018 in Energies
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This paper describes a switching pattern generated in case of induction motor drive predictive torque control (PTC) compared to a switching pattern of direct torque control (DTC). PTC is a modern control method for electric drives based on model predictive control (MPC). DTC is a very powerful method and is today an industrial standard for controlling an induction motor drive. Its usage is wide-spread, mainly in high-power applications. However, the method suffers from a few disadvantages. One of the causes of the control method’s problematic behavior is choosing the switching combinations in the flux sector. Another inconvenience is the common selection table not including all voltage vectors in given sector. By these factors, the ripples of flux vector trajectory and torque waveforms are influenced. The longer the sample time is, the more significant the influence of factors becomes, because only a few steps occur within one turn of the magnetic flux vector. Based on the detailed analysis, the reasons of the different performance of both systems are explained. The analysis performed by simulation in Matlab Simulink environment has proved that, while DTC might choose voltage vector that pushes system away from the reference values, the MPC always chooses the most proper vector. The experimental results measured on the real drive confirm the appropriate vector selection, just in case of the predictive control method.

ACS Style

Pavel Karlovsky; Jiri Lettl. Induction Motor Drive Direct Torque Control and Predictive Torque Control Comparison Based on Switching Pattern Analysis. Energies 2018, 11, 1793 .

AMA Style

Pavel Karlovsky, Jiri Lettl. Induction Motor Drive Direct Torque Control and Predictive Torque Control Comparison Based on Switching Pattern Analysis. Energies. 2018; 11 (7):1793.

Chicago/Turabian Style

Pavel Karlovsky; Jiri Lettl. 2018. "Induction Motor Drive Direct Torque Control and Predictive Torque Control Comparison Based on Switching Pattern Analysis." Energies 11, no. 7: 1793.

Conference paper
Published: 01 June 2018 in 2018 10th International Conference on Electronics, Computers and Artificial Intelligence (ECAI)
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The induction motor drive with variable speed is a very common drive in many applications. To ensure the induction motor drive speed control, the sophisticated control methods must be utilized. In the paper, the Model Predictive Control (MPC) is employed. This method is usually used in order to control the induction motor flux amplitude and torque values. The induction motor is powered by the semiconductor voltage source inverter. Switching the semiconductor devices and current flow cause arise of losses in inverter. To decrease the losses, the modified MPC method is derived in the paper. In the Matlab Simulink environment reached simulation results show a reduction in losses at the newly modified control strategy compared to the conventional MPC method.

ACS Style

Pavel Karlovský; Jiri Lettl. Loss Reduction in Induction Motor Drive Using Model Predictive Control. 2018 10th International Conference on Electronics, Computers and Artificial Intelligence (ECAI) 2018, 1 -4.

AMA Style

Pavel Karlovský, Jiri Lettl. Loss Reduction in Induction Motor Drive Using Model Predictive Control. 2018 10th International Conference on Electronics, Computers and Artificial Intelligence (ECAI). 2018; ():1-4.

Chicago/Turabian Style

Pavel Karlovský; Jiri Lettl. 2018. "Loss Reduction in Induction Motor Drive Using Model Predictive Control." 2018 10th International Conference on Electronics, Computers and Artificial Intelligence (ECAI) , no. : 1-4.

Conference paper
Published: 01 June 2017 in 2017 9th International Conference on Electronics, Computers and Artificial Intelligence (ECAI)
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The proper control of induction motor drive is an important task in many applications. Usually, the motor is supplied from voltage source inverter and the required voltage is calculated according to the actual and past states of the motor. Unlike this, the predictive methods calculate also the future state and adjust the voltage accordingly. The model predictive control method calculates the effects of all possible future states in the next step and chooses the best action according to desired criteria. In the paper, this method is employed in the induction motor drive and the influence of the switching frequency on the torque and flux waveform ripples are examined in simulation environment Matlab Simulink.

ACS Style

Pavel Karlovský; Jiri Lettl. Influence of switching frequency on torque ripples in model predictive control of induction motor drive. 2017 9th International Conference on Electronics, Computers and Artificial Intelligence (ECAI) 2017, 1 -4.

AMA Style

Pavel Karlovský, Jiri Lettl. Influence of switching frequency on torque ripples in model predictive control of induction motor drive. 2017 9th International Conference on Electronics, Computers and Artificial Intelligence (ECAI). 2017; ():1-4.

Chicago/Turabian Style

Pavel Karlovský; Jiri Lettl. 2017. "Influence of switching frequency on torque ripples in model predictive control of induction motor drive." 2017 9th International Conference on Electronics, Computers and Artificial Intelligence (ECAI) , no. : 1-4.

Conference paper
Published: 01 May 2017 in 2017 18th International Scientific Conference on Electric Power Engineering (EPE)
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Direct torque control (DTC) is one of the best performing strategies for induction motor control in many applications. However, this method suffers from a few disadvantages. Very important one is the presence of ripples in the torque waveform. The main reason of their presence is the inaccurate model of the motor. This paper utilizes Luenberger observer to calculate the model of the motor instead of the classical one. The DTC strategies with its original model and with Luenberger observer are created on dSPACE ds1103 platform. The results from experiment on a specific induction motor drive are shown. The paper shows better performance of the DTC with model based on Luenberger observer. The ripples in torque waveforms were lowered while switching frequency of the transistors remained the same.

ACS Style

Pavel Karlovský; Jiří Lettl. Improvement of DTC performance using luenberger observer for flux estimation. 2017 18th International Scientific Conference on Electric Power Engineering (EPE) 2017, 1 -5.

AMA Style

Pavel Karlovský, Jiří Lettl. Improvement of DTC performance using luenberger observer for flux estimation. 2017 18th International Scientific Conference on Electric Power Engineering (EPE). 2017; ():1-5.

Chicago/Turabian Style

Pavel Karlovský; Jiří Lettl. 2017. "Improvement of DTC performance using luenberger observer for flux estimation." 2017 18th International Scientific Conference on Electric Power Engineering (EPE) , no. : 1-5.

Journal article
Published: 01 January 2017 in Procedia Engineering
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ACS Style

Pavel Karlovský; Jiří Lettl. Application of MRAS Algorithm to Replace the Speed Sensor in Induction Motor Drive System. Procedia Engineering 2017, 192, 421 -426.

AMA Style

Pavel Karlovský, Jiří Lettl. Application of MRAS Algorithm to Replace the Speed Sensor in Induction Motor Drive System. Procedia Engineering. 2017; 192 ():421-426.

Chicago/Turabian Style

Pavel Karlovský; Jiří Lettl. 2017. "Application of MRAS Algorithm to Replace the Speed Sensor in Induction Motor Drive System." Procedia Engineering 192, no. : 421-426.

Conference paper
Published: 29 September 2016 in 2016 International Conference on Applied Electronics (AE)
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Considering the disadvantages of induction motor drive such as torque ripple and current waveform distortion when using direct torque control (DTC) method, the method substitution might improve the drive behaviour. The authors suggest instead of the DTC method using the predictive method based on similar principles. In the paper, both methods are examined. Then on the induction motor drive yet controlled by DTC algorithm, the predictive method is implemented and performances of both control strategies are compared.

ACS Style

Pavel Karlovsky; Jiri Lettl. Improvement of induction motor drive performance using predictive control method instead of DTC method. 2016 International Conference on Applied Electronics (AE) 2016, 121 -124.

AMA Style

Pavel Karlovsky, Jiri Lettl. Improvement of induction motor drive performance using predictive control method instead of DTC method. 2016 International Conference on Applied Electronics (AE). 2016; ():121-124.

Chicago/Turabian Style

Pavel Karlovsky; Jiri Lettl. 2016. "Improvement of induction motor drive performance using predictive control method instead of DTC method." 2016 International Conference on Applied Electronics (AE) , no. : 121-124.

Conference paper
Published: 01 June 2016 in 2016 8th International Conference on Electronics, Computers and Artificial Intelligence (ECAI)
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In most cases, using of an optical sensor represents the most common solution to obtain the induction motor actual speed. As in some cases the use of the speed sensor carries number of problems, an effort to find a solution that does not require a speed sensor is obvious in recent time. The paper presents some results of employing MRAS (Model Reference Adaptive System) method for sensorless induction motor shaft speed determination. The working principles and the possible algorithm mathematical derivation are described. Results of the drive performance simulation in MatLab/Simulink environment are presented. Finally, the algorithm is verified on the real induction motor drive utilizing dSPACE platform. Obtained results demonstrate good function and performance of the system.

ACS Style

Pavel Karlovsky; Radek Linhart; Jiri Lettl. Sensorless determination of induction motor drive speed using MRAS method. 2016 8th International Conference on Electronics, Computers and Artificial Intelligence (ECAI) 2016, 1 -4.

AMA Style

Pavel Karlovsky, Radek Linhart, Jiri Lettl. Sensorless determination of induction motor drive speed using MRAS method. 2016 8th International Conference on Electronics, Computers and Artificial Intelligence (ECAI). 2016; ():1-4.

Chicago/Turabian Style

Pavel Karlovsky; Radek Linhart; Jiri Lettl. 2016. "Sensorless determination of induction motor drive speed using MRAS method." 2016 8th International Conference on Electronics, Computers and Artificial Intelligence (ECAI) , no. : 1-4.