Direct Torque And Flux Control Research Articles

Enhanced deadbeat predictive current control with novel generalized space vector modulation for five‐level inverter fed permanent magnet synchronous motor drive with reduced torque ripples and less computational burden

SummaryTraditional electric drive control methodologies, such as field oriented control (FOC) and direct torque and flux control (DTFC), predominantly rely on multiple proportional‐integral (PI) controllers that demand complex tuning. While model predictive current control (MPCC) omits PI controllers, it has inherent challenges including high computational burden and tempered dynamics. Although two‐level inverters (2LI) are prevalent in many applications, their performance wanes in high‐power applications like high performance industrial drives and marine propulsions. Multilevel inverters (MLIs) are more efficient, but combined with space vector modulation (SVM), they add computational complexity, particularly at higher levels, limiting drive sampling frequencies and causing torque ripples and harmonics, affecting performance. To address the above drawbacks, this manuscript presents a deadbeat predictive current control of five‐level inverter fed permanent magnet synchronous motor (PMSM) drive with a novel generalized SVM algorithm with reduced computational burden and improved performance. The proposed method is validated through MATLAB/Simulink‐based simulation study and experimental implementation. The results are presented and discussed. The results are compared with DTFC and MPCC where it is observed that the proposed method offers superior performance with reduced computational burden and streamlined implementation.

Modelling and Simulation of the Hybrid System PV-Wind

In this paper, we focused on modeling and simulation of a hybrid solar-wind energy system, consisting of a photovoltaic cell and a wind turbine driven by a Permanent Magnet Synchronous Generator (PMSG). The proposed system gives details of the hybrid solar-wind system. In the PV subsystem, there will be a photovoltaic energy subsystem, MPPT controller, and a DC-DC boost converter. The wind turbine subsystem includes a wind turbine energy subsystem, PMSG, and MPPT controller. The MPPT controllers were designed to extract the maximum power regardless of the weather conditions and temperatures. The P and O algorithm is introduced in the MPPT used in the PV energy subsystem and on the control of the machine side converter (MSC). The proposed wind turbine energy subsystem is based on Direct Torque and Flux Control (DTFC). The simulated results are demonstrated to show that the hybrid solar-wind generating system can realize a maximum power point tracking control of wind and solar power to satisfy the energy demand over an extensive range under unpredictable atmospheric conditions. The system has been demonstrated by MATLAB/Simulink and tested for variable weather conditions and temperatures.

A Discrete Linearization-Based Predictive Intelligence Technique for Direct Torque and Flux Control of Induction Motor Drive with Feedback Linearization

This article describes a linearization-based model predictive intelligence control (MPIC) approach incorporated with a feedback linearization (FBL)-based direct torque and flux control (DTFC) of induction motor (IM) drive. This FBL DTFC with MPIC is employed here to analyze the dynamic performance of the IM drive and is compared with the conventional MPIC-based DTFC technique. The intuitive FBL approach develops the decoupled components of torque and flux. Hence, the specific intuitive linearized model-based DTFC-SVM not only preserves all advantages of DTFC but also improves the transient response with a reduced settling time of 30 to 40% along with a substantial reduction in torque and flux ripple by around 78% and 68%, respectively. However, the stability problem to design such a controller is a significant issue, and therefore, it is examined by estimating that the control law is monotonically converging with time. Hence, the proposed solution is highly justifiable and flexible. This proposed controller-based feedback linearized drive is modeled and its dynamic response and robust performance are analyzed by using MATLAB/SIMULINK software as well as extensive experimental results. It is observed from the experimental result that there is a significant improvement in torque and flux ripple of around 78% and 67%, respectively.

A novel direct torque and flux control of permanent magnet synchronous motor with analytically-tuned PI controllers

<span lang="EN-US">This work presents a novel direct torque and flux control (DTFC) of permanent magnet synchronous motor (PMSM) with analytically-tuned proportional integral (PI) controllers. The proportional (K_p) and integral (K_i) gains of the PI controllers were accurately determined, from first principle, using the model of the control system. The PI flux and torque controllers were then developed in rotor reference frame. The designed PI controllers, together with the torque and flux controllers, were tested on a permanent magnet synchronous motor (PMSM). The results obtained were compared with results from conventional DTFC system using manually-tuned PI controllers. The total harmonic distortion (THD) of motor phase currents is 18.80% and 4.81% for the conventional and proposed models respectively. This confirms a significant reduction in torque ripples. The control system was tested for step torque loading and found to offer excellent performance both during load changes, speed reversal, and constant load conditions.</span>

Torque ripple minimization of multi-level inverter fed PMSM drive using modified MPTC

Abstract This paper focuses on investigating the steady-state and dynamic performance of the permanent magnet synchronous motor (PMSM) drive using modified model predictive torque control (MPTC) method with multi-level inverters (MLIs). The MPTC method is simple and easy to implement for motor control as they don’t involve cascaded PI controllers unlike required the conventional controllers, such as field oriented control (FOC) and direct torque and flux control (DTFC). The proposed modified MPTC method eliminates the use of weighing factors and it is a fusion of model predictive current control (MPCC) and MPTC. Initially, the proposed modified MPTC fed PMSM drive is implemented using two-level inverter. It provides better steady-state and dynamic performance, but the ripple contents of torque, flux, and currents are high. In order to reduce the ripple contents and improve the performance of the PMSM drive, a modified MPTC is implemented using three-level inverter. The proposed modified MPTC fed PMSM drive using two-level and three-level inverters are simulated in MATLAB/SIMULINK environment under different operating conditions, such as no-load, loading, speed reversal, step change in speed operations. In order to show the effectiveness and feasibility of the proposed method, it is also validated with the experimental results.

Cascaded Multi-Level Inverter with APOD Based PV System for Induction Motor using DTFC Control

In this paper cascaded multi-level inverter based APOD control is designed to achieve harmonic reduction based on induction motor (IM) application which is fed by switched inductor quasi-Z source inverter (SL-qZSI) is proposed. The control method of proposed induction motor is controlled by direct torque and flux control (DTFC). The proposed converter qZSI is achieving the DC link voltage with improvement and to maintain the constant power supply. The proposed control technique for induction motor directs to reliability improvement and the capability of soft starting. The multi-level inverter with cascaded system is using with APOD control to reduce the total harmonic distortion in the supply voltage. The DTFC achieves the reduced settling time and stator inrush current reductions are achieved. The results and proposed system is analyzed and verified using MATLAB/Simulink environment.

Sensorless flux adaption DTFC of an IPMSM based on an active flux‐based MTPA and an adaptive second‐order sliding mode observer

This study proposes a sensorless flux adaption direct torque and flux control (DTFC) for an interior permanent magnet synchronous motor (IPMSM), in which an maximum torque per ampere (MTPA) based on active flux and an adaptive second-order sliding mode observer (SOSMO) are adopted. Flux adaption DTFC is proposed based on the existing active flux concept. Thus, the stator current amplitude can be minimised in both steady state and transient state. Furthermore, to realise the sensorless control of the IPMSM, an adaptive SOSMO is proposed. Compared with constant gains SOSMO, the gains of the adaptive SOSMO can be adjusted adaptively with the motor speed changing. Then, the precision of position estimation is enhanced effectively in a wide speed range. Numerical simulations and experiments with a 60 kW IPMSM are implemented. In addition, the results validate the capability of the proposed sensorless flux adaption DTFC scheme.

Direct Torque and Flux Control of PV Connected Permanent Magnet Synchronous Machine

This paper presents a direct torque and flux control (DTFC) method of PV array fed permanent magnet synchronous machine in (d-q) frame. This method retains the traditional DTFC principle of decoupling torque and flux control to compensate the torque and flux errors in a smooth manner with conventional DTFC, while providing greater use of voltage source inverter using optimal switching. Also a feedback path using PI controller is introduces in this system to regulate the speed and to reduce the error. Here, we have presented satisfied results of DTFC method in PMSM with close loop speed controller. All the results are performed in MATLAB Simulink platform.

A Super-Twisting Sliding-Mode Stator Flux Observer for Sensorless Direct Torque and Flux Control of IPMSM

The scheme based on direct torque and flux control (DTFC) as well as active flux is a good choice for the interior permanent magnet synchronous motor (IPMSM) sensorless control. The precision of the stator flux observation is essential for this scheme. However, the performance of traditional observers like pure integrator and the low-pass filter (LPF) is severely deteriorated by disturbances, especially dc offset. Recently, a sliding-mode stator flux observer (SMFO) was proposed to reduce the dc offset in the estimated stator flux. However, it cannot eliminate the dc offset totally and will cause the chattering problem. To solve these problems, a novel super-twisting sliding-mode stator flux observer (STSMFO) is proposed in this paper. Compared with SMFO, STSMFO can reduce the chattering and fully eliminate the dc offset without any amplitude and phase compensation. Then, the precision of the stator flux and rotor position can be greatly improved over a wide speed region. The detailed mathematical analysis has been given for comparing it with another three traditional observers. The numerical simulations and experimental testing with an IPMSM drive platform have been implemented to verify the capability of the proposed sensorless scheme.

Direct torque and flux control of switched reluctance motor with enhanced torque per ampere ratio and torque ripple reduction

A smooth torque control of switched reluctance motor (SRM) is essential to avoid speed fluctuations causing stability problems in vehicular applications. This can be accomplished by an appropriate motor design and/or use of direct control of torque in SRM. It is reported that high RMS current is required to minimise the torque ripple in the conventional direct torque and flux control (DTFC), thereby reducing the torque per ampere ratio. To overcome this issue, a new DTFC technique with improved torque per ampere ratio while minimising torque ripple in an SRM traction drive is presented. Results demonstrated that the proposed DTFC technique reduces torque ripple with enhanced torque per ampere. Finally, the performance of the proposed scheme is compared with conventional DTFC of a four-phase (8/6) SRM to show the improvement in the traction drive.

Online Torque-Flux Estimation-Based Nonlinear Torque and Flux Control Scheme of IPMSM Drive for Reduced Torque Ripples

In order to have direct and better control of reducing the torque/flux ripples of interior permanent magnet synchronous motor (IPMSM), this paper presents an online torque and flux estimation-based nonlinear torque and flux control (NTFC) scheme of IPMSM drive considering motor electromagnetic developed torque and stator air-gap flux linkage as virtual state variables. For conventional nonlinear controller, the d-q-axis currents (id, iq) are considered as state variables that indirectly controls the torque/flux which may not be suitable for high-performance drives. On the other hand, conventional direct torque and flux control (DTFC) scheme suffers from significant torque ripples. The proposed work overcomes the major drawback of both the conventional nonlinear and DTFC schemes through the significant reduction in torque ripples. Stability of the proposed drive is also demonstrated through Lyapunov's stability criterion and global asymptotic stability is assured through the application of criterion supported by Barbalat's lemma. Reduced torque ripples and robustness of the proposed NTFC scheme is validated through comparative simulation and experimental results with classical nonlinear controller and DTFC-based IPMSM drive. The proposed NTFC scheme achieves the lowest possible torque ripples in steady state at different operating conditions.

Comparison of Various Strategies in DTFC Based Multilevel NPC Inverter Fed Induction Drive for Torque Ripple Reduction

Multilevel inverters have become popular in recent years in high power applications; they provide an effective solution for increasing power and minimizing the harmonics of AC waveforms. The fast response and robust method of conventional direct torque control are used in variable speed drives for the reduction of torque ripple. However, major problems occur at steady-state notable torque, flux, and current pulsations in direct torque control drives. This paper presents various strategies in the direct torque and flux control of induction motors for the reduction of torque ripple based on a multilevel neutral point clamped (NPC) inverter. This kind of inverter is used to achieve better harmonic reductions than the traditional two-level voltage source inverters and the related control scheme serves to minimize semiconductor losses. The performance of an induction motor depends upon a mathematical model that comprises the variations in parameters, common-mode voltage, noise, flux variation, and levels of harmonics in a machine. Here, the torque ripples and voltage saturations are the most substantial problems in electrical drive applications. To overcome this problem, the direct torque and flux control (DTFC) technique based on multilevel NPC inverter topology is developed. Moreover, the various control strategies-based DTFC is proposed for the minimization of torque ripple in IM drives. An improved control scheme is used to optimize the regulation of torque and speed with less torque response. This paper proposes the comparative study of the THD analysis of different control techniques (PI, fuzzy, ANFIS) that is effectively used for harmonic moderation in the design of different NPC multilevel inverter; this goal is achieved as shown from the comparison of simulation results using the MATLAB/SIMULINK environment.

Direct torque and flux control of interior permanent magnet synchronous machine in deep flux‐weakening region

Direct torque and flux control (DTFC) is known for its reduced torque and flux ripples compared to the classical direct torque control scheme. It can drive an interior permanent magnet synchronous motor (IPMSM) in usual control regimes while satisfying current and voltage limits of the system. However, deep flux-weakening control of an IPMSM under DTFC has not been investigated as extensively, especially operation along the maximum torque per voltage (MTPV) trajectory in the torque-flux plane. This study proposes a simple and effective control method, which incorporates MTPV trajectory in the conventional flux-weakening algorithm of DTFC. Performance of an IPMSM drive is analysed when operated with the proposed control method.

Direct Torque and Flux Control of a Four-Switch Three-Phase Inverter-Fed Synchronous Reluctance Motor Drives

This paper presents an application of direct torque and flux control (DTFC) for a four-switch three-phase inverter (FSTPI)-fed synchronous reluctance motor (SynRM) in which the saturation and iron losses' effects are involved in the machine control modeling. The DTFC switching technique for the SynRM fed by FSTPI in low-power and low-cost applications is implemented by imitating the six-switch three-phase inverter (SSTPI). By considering equal effective vectors depicted in SSTPI, the αβ stationary reference frame is represented by using six sectors. Similarly, the voltage space vector formation is constructed in FSTPI. Accordingly the SynRM performance under DTFC is precisely analyzed by considering the saturation and iron losses' effects. The DTFC behavior based on SSTPI- and FSTPI-fed SynRM is evaluated using Simulink benchmark. At different operating conditions, further simulation and experimental results of DTFC based on FSTPI dynamically confirm the effectiveness of the proposed control application on the SynRM.

A Switched Inductor Quasi Z source-H-bridge Multilevel Inverter for Soft starting Control of Induction Motor using Direct Torque and Flux Control

An impedance source multilevel inverter schemes applied for traction and industrial drives application. Because it has unique merits ofharmonics less, transformer less drives control application and also soft start capability of induction drives. This paper proposed a reduced source z source Hbridge multilevel inverter and it is applied for induction motor drive control. In order to improving performance of induction motor performance, the torque and speed control is achieved using Direct Torque and Flux Control (DTFC)via phase voltage and current magnitude control. The proposed control scheme of Direct Torque and Flux Control (DTFC) is calculated through phase voltage and phase current sensing and then stator torque and flux is to be calculated byseparate estimation scheme. In reduced source Z source H-bridge multilevel inverter schemes, z source circuit gives a soft start capability across induction motor drive by controlling power magnitude across DC-Link. Reduced source is achieved using capacitor balancing circuit using a common DC-source. A single carrier and multi-reference of Phase Opposition and Disposition (POD) pulse width modulation topology is uses for proposed reduced source z source Multilevel Inverter for soft start control of induction motor.

A novel technology for control of variable speed pumped storage power plant

Variable speed pumped storage machines are used extensively in wind power plant and pumped storage power plant. This paper presents direct torque and flux control (DTFC) of a variable speed pumped storage power plant (VSPSP). By this method both torque and flux have been applied to control the VSPSP. The comparison between VSPSP’s control strategies is studied. At the first, a wind turbine with the capacity 2.2 kW and DTFC control strategies simulated then a 250 MW VSPSP is simulated with all of its parts (including electrical, mechanical, hydraulic and its control system) by MATLAB software. In all of simulations, both converters including two-level voltage source converter (2LVSC) and three-level voltage source converter (3LVSC) are applied. The results of applying 2LVSC and 3LVSC are the rapid dynamic responses with better efficiency, reducing the total harmonic distortion (THD) and ripple of rotor torque and flux.

An Improved DTFC based Five Levels - NPC Inverter Fed Induction Motor for Torque Ripple Minimization

This paper presents a five level Neutral Point Clamped (NPC) inverter fed IM (Induction Motor) drive for variable speed application. In general the stator current is very highly affected by the harmonic components. It can be affecting the torque to produce high torque ripple in IM at maximum to low speed region. Since the drive performances are depends on mathematical model contains the parameters variations, noise, common mode voltage, flux variation and harmonic levels of the machine. Torque ripples and voltage saturations are the most significant problems in drive application. To overcome this problem the DTFC (direct torque and flux control) technique based five-level neutral-point-clamped (NPC-5L) approach is used. The proposed control scheme uses to stator current error as variable. Through the resistance estimated PI controller rules based the selection of voltage space vector modulation technique is optimized and motor performance level has been improved. The torque & speed are successfully controlled with less torque response. The results are compared and verified with conventional three phases VSI under different control technique by Matlab/Simulink.

High Ripples Reduction in DTC of Induction Motor by Using a New Reduced Switching Table

Abstract The direct torque and flux control (DTC) of electrical motors is characterized by ripples of torque and flux. Among the many solutions proposed to reduce them is to use modified switching tables which is very advantageous; because its implementation is easy and requires no additional cost compared to other solutions. This paper proposes a new reduced switching table (RST) to improve the DTC by reducing harmful ripples of torque and flux. This new switching table is smaller than the conventional one (CST) and depends principally at the flux error. This solution is studied by simulation under Matlab/Simulink and experimentally validated on a testbed with DSPACE1103. The results obtained of a DTC with RST applied to a three-phase induction motor (IM) show a good improvement and an effectiveness of proposed solution, the torque ripple decreases about 47% and 3% for the stator flux compared with a basic DTC.

Performance of a Sensorless Controlled Concentrated-Wound Interior Permanent-Magnet Synchronous Machine at Low and Zero Speed

This paper concerns the sensorless direct torque and flux control (DTFC) of a 14-pole/18-slot, fractional-slot concentrated winding interior permanent-magnet synchronous machine (IPMSM). The dynamic performance of the prototype machine at or near base speed was found to be comparable to a distributed wound IPMSM. However, the lowest operating speed of the machine under sensorless control scheme was only about 30% of the base speed. This paper demonstrates experimentally that this lack of performance can be overcome substantially by using the extended-flux linkage model and high-frequency (HF) injection methods. By using the extended-flux model, the lowest operable speed was reduced from 30% to 5% of the base speed. In order to operate the machine, at a standstill under sensorless control, the HF injection method was employed. Factors that affect the performance at zero speed were investigated systematically.

Online Loss-Minimization-Based Adaptive Flux Observer for Direct Torque and Flux Control of PMSM Drive

This paper presents a novel adaptive flux observer based direct torque and flux control (DTFC) of a permanent magnet synchronous motor (PMSM) drive. An online loss minimization algorithm (LMA) is developed to estimate the air-gap flux so that the motor operates at minimum loss condition while taking the general advantages of the DTFC scheme over the conventional vector control scheme. The proposed DTFC-based PMSM drive incorporating the LMA-based flux observer is implemented in real time using the DSP board DS1104 for a laboratory 5-hp motor. The performance of the proposed LMA-based DTFC control of the PMSM drive is tested in both simulation and experiment at different operating conditions.