Articles
            
            
            
            
            
                            
                    
                        Improvement of Torque Capability of Direct Torque Control of Induction Machines 
                    
                    Auzani Jidin; 
New Lai Sim; 
Tole Sutikno                    
                     International Journal of Power Electronics and Drive Systems (IJPEDS) Vol 8, No 3: September 2017 
                    
                    Publisher : Institute of Advanced Engineering and Science 
                    
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                                DOI: 10.11591/ijpeds.v8.i3.pp1070-1079                            
                                            
                    
                        
                            
                            
                                
A control strategy for overmodulation operation of direct torque control hysteresis based in induction machine is proposed. The strategy is to extend the constant torque region as well as to improve the torque capability. The proposed overmodulation strategy is different to SVM based system where the reference stator voltage is available. In order for DTC hysteresis based system to be able to achieve that, several modifications have been applied so that the proposed overmodulation can be achieved by gradually transforming the PWM voltage waveform to six-step mode. Simulated results were provided to demonstrate the effectiveness of the strategy.
                            
                         
                     
                 
                
                            
                    
                        Multiphase Transformer Modelling using Finite Element Method 
                    
                    Nor Azizah Mohd Yusoff; 
Kasrul Abdul Karim; 
Sharin Ab Ghani; 
Tole Sutikno; 
Auzani Jidin                    
                     International Journal of Power Electronics and Drive Systems (IJPEDS) Vol 6, No 1: March 2015 
                    
                    Publisher : Institute of Advanced Engineering and Science 
                    
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                                DOI: 10.11591/ijpeds.v6.i1.pp56-64                            
                                            
                    
                        
                            
                            
                                
In the year of 1970 saw the starting invention of the five-phase motor as the milestone in advanced electric motor. Through the years, there are many researchers, which passionately worked towards developing for multiphase drive system. They developed a static transformation system to obtain a multiphase supply from the available three-phase supply. This idea gives an influence for further development in electric machines as an example; an efficient solution for bulk power transfer. This paper highlighted the detail descriptions that lead to five-phase supply with fixed voltage and frequency by using Finite-Element Method (FEM). Identifying of specification on a real transformer had been done before applied into software modeling. Therefore, Finite-Element Method provides clearly understandable in terms of visualize the geometry modeling, connection scheme and output waveform.
                            
                         
                     
                 
                
                            
                    
                        Integration of STATCOM and ESS for power system stability improvement 
                    
                    Ibrahim Alhamrouni; 
Rasyid Ismail; 
Mohamed Salem; 
Bazilah Ismail; 
Awang Jusoh; 
Tole Sutikno                    
                     International Journal of Power Electronics and Drive Systems (IJPEDS) Vol 11, No 2: June 2020 
                    
                    Publisher : Institute of Advanced Engineering and Science 
                    
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                                DOI: 10.11591/ijpeds.v11.i2.pp859-869                            
                                            
                    
                        
                            
                            
                                
The power system enters a state of voltage instability due to the inability of the power system to meet the demand for active power and reactive power due to the increase of system load. In order to stabilize the power system, the installation of STATCOM and ESS needs to be performed. The main objective of this study is to identify the suitable size and location of STATCOM and ESS for power system stability improvement. First, the IEEE 14 bus system was simulated using DIgSILENT software in ideal condition. Then, the system loadability was increased up to 200% of initial value to locate the weakest bus. This study includes the applicable location and sizing of STATCOM and ESS towards improving power system stability. The results showed that the application of STATCOM and ESS with the most reliable size can increase the bus voltage (p.u and kV) of IEEE 14 bus system thus improving the power system stability. For recommendation, the power system stability can be improved by installing multiple STATCOM and ESS at other load buses and applying a controller to both STATCOM and ESS to improve the effectiveness of generating and absorbency of active and reactive power in the power system.
                            
                         
                     
                 
                
                            
                    
                        Improved Stator Flux Estimation for Direct Torque Control of Induction Motor Drives 
                    
                    Yahya Ahmed Alamri; 
Nik Rumzi Nik Idris; 
Ibrahim Mohd. Alsofyani; 
Tole Sutikno                    
                     International Journal of Power Electronics and Drive Systems (IJPEDS) Vol 7, No 4: December 2016 
                    
                    Publisher : Institute of Advanced Engineering and Science 
                    
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                                DOI: 10.11591/ijpeds.v7.i4.pp1049-1060                            
                                            
                    
                        
                            
                            
                                
Stator flux estimation using voltage model is basically the integration of the induced stator back electromotive force (emf) signal. In practical implementation the pure integration is replaced by a low pass filter to avoid the DC drift and saturation problems at the integrator output because of the initial condition error and the inevitable DC components in the back emf signal. However, the low pass filter introduces errors in the estimated stator flux which are significant at frequencies near or lower than the cutoff frequency. Also the DC components in the back emf signal are amplified at the low pass filter output by a factor equals to . Therefore, different integration algorithms have been proposed to improve the stator flux estimation at steady state and transient conditions. In this paper a new algorithm for stator flux estimation is proposed for direct torque control (DTC) of induction motor drives. The proposed algorithm is composed of a second order high pass filter and an integrator which can effectively eliminates the effect of the error initial condition and the DC components. The amplitude and phase errors compensation algorithm is selected such that the steady state frequency response amplitude and phase angle are equivalent to that of the pure integrator and the multiplication and division by stator frequency are avoided. Also the cutoff frequency selection is improved; even small value can filter out the DC components in the back emf signal. The simulation results show the improved performance of the induction motor direct torque control drive with the proposed stator flux estimation algorithm. The simulation results are verified by the experimental results.
                            
                         
                     
                 
                
                            
                    
                        A Novel Optimal PI Parameter Tuning Strategy to Improve Constant Switching Performance of Direct Torque Control 
                    
                    Sundram Ramahlingam; 
Auzani Jidin; 
Tole Sutikno                    
                     International Journal of Power Electronics and Drive Systems (IJPEDS) Vol 7, No 2: June 2016 
                    
                    Publisher : Institute of Advanced Engineering and Science 
                    
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                                DOI: 10.11591/ijpeds.v7.i2.pp422-430                            
                                            
                    
                        
                            
                            
                                
This paper presents a novel method of optimal Propotional-Intergral (PI) controller’s parameter tuning strategy in-order to improve the Constant Switching Performance of 3-phase DTC shceme. The Direct Torque Control (DTC) sheme is acknowledged to provide fast decoupled control over the torque output and stator flux via a simple control structure. However, DTC sheme has two major downsides, which are the inconsistent inverter switching frequency and high torque output ripple. The main reason that contributes to these tribulations is the usage of hysteresis comparators in order to control the output torque. The realization of PI based controller method as replacement of hyterisis controller in DTC system able to provide significant solutions to over come the fall back while retaining the simple control structure of conventional DTC. The combination usage of higher sampling controller DS1004 and also 3-level CHMI in this system can further minimize the output torque ripple by providing higher resolution with lower digital error and greater number of vectors. This paper presents detail explanation and calculation of optimal PI parameter tuning strategy consecutively to enhance the performance of 3-level DTC system. In order to verify the feasibility of the proposed method experimentation, the proposed method is compared with convention DTC system via simulation and experiment results.
                            
                         
                     
                 
                
                            
                    
                        Proposed Voltage Vector to Optimize Efficiency of Direct Torque Control 
                    
                    Goh Wee Yen; 
Ali Monadi; 
Nik Rumzi Nik Idris; 
Auzani Jidin; 
Tole Sutikno                    
                     International Journal of Power Electronics and Drive Systems (IJPEDS) Vol 4, No 4: December 2014 
                    
                    Publisher : Institute of Advanced Engineering and Science 
                    
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Compared to field-oriented control (FOC) system, direct torque control (DTC) system has gained attractiveness in control drive system because of its simpler control structure and faster dynamic control. However, supplying the drive system with rated flux at light load will decrease the power factor and efficiency of the system. Thus, an optimal flux has been applied during steady-state in order to maximize the efficiency of drive system. But when a torque is suddenly needed, for example during acceleration, the dynamic of the torque response would be degraded and it is not suitable for electric vehicle (EV) applications. Therefore, a modification to the voltage vector as well as look-up table has been proposed in order to improve the performance of torque response.DOI: http://dx.doi.org/10.11591/ijpeds.v4i4.6918
                            
                         
                     
                 
                
                            
                    
                        Improved Torque Control Performance in Direct Torque Control using Optimal Switching Vectors 
                    
                    Muhd Zharif Rifqi Zuber Ahmadi; 
Auzani Jidin; 
Maaspaliza Azri; 
Khairi Rahim; 
Tole Sutikno                    
                     International Journal of Power Electronics and Drive Systems (IJPEDS) Vol 5, No 3: 2015 
                    
                    Publisher : Institute of Advanced Engineering and Science 
                    
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                                DOI: 10.11591/ijpeds.v5.i3.pp441-452                            
                                            
                    
                        
                            
                            
                                
This paper presents the significant improvement of Direct Torque Control (DTC) of 3-phases induction machine using a Cascaded H-Bidge Multilevel Inverter (CHMI). The largest torque ripple and variable switching frequency are known as the major problem founded in DTC of induction motor. As a result, it can diminish the performance induction motor control. Therefore, the conventional 2-level inverter has been replaced with CHMI the in order to increase the performance of the motor either in dynamic or steady-state condition. By using the multilevel inverter, it can produce a more selection of the voltage vectors. Besides that, it can minimize the torque ripple output as well as increase the efficiency by reducing the switching frequency of the inverter. The simulation model of the proposed method has been developed and tested by using Matlab software. Its improvements were also verified via experimental results.
                            
                         
                     
                 
                
                            
                    
                        Simple Switching Strategy for High-Torque Control Performance utilizing Neutral Point Clamped Multilevel Inverter 
                    
                    Nor Faezah Alias; 
Auzani Jidin; 
Atikah Razi; 
Tole Sutikno; 
Huzainirah Ismail                    
                     International Journal of Power Electronics and Drive Systems (IJPEDS) Vol 3, No 4: December 2013 
                    
                    Publisher : Institute of Advanced Engineering and Science 
                    
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Three-level Neutral Point Clamped (NPC) inverter allows the configuration of switching devices to operate at high voltage and produce lower current/voltage harmonics. It is known that, DTC of induction machine which employs hysteresis controller has major drawbacks namely larger torque ripple and variable switching frequency. This paper aims to propose a suitable voltage vector selection to provide better torque regulation and lower switching frequency by employing DTC with 3-level NPC multilevel inverter. A simple switching strategy was formulated using 7-level torque hysteresis and 2-level flux hysteresis controllers to give more options in selecting an appropriate voltage vector, inherently, according the motor operation conditions. The improvements offered were verified through simulations.DOI: http://dx.doi.org/10.11591/ijpeds.v3i4.5248
                            
                         
                     
                 
                
                            
                    
                        Identification of harmonic source location in power distribution network 
                    
                    Mohd Hatta Jopri; 
Aleksandr Skamyin; 
Mustafa Manap; 
Tole Sutikno; 
Mohd Riduan Mohd Shariff; 
Aleksey Belsky                    
                     International Journal of Power Electronics and Drive Systems (IJPEDS) Vol 13, No 2: June 2022 
                    
                    Publisher : Institute of Advanced Engineering and Science 
                    
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                                DOI: 10.11591/ijpeds.v13.i2.pp938-949                            
                                            
                    
                        
                            
                            
                                
This paper presents the experimental set-up of identification of harmonic source location in the power distribution network using time-frequency analysis, known as S-transform (ST) at the point of common coupling (PCC). S-transform offers high frequency resolution in analyzing the low frequency component and able to represent signal parameters in time-frequency representation (TFR) such as TFR impedance (ZTFR). The proposed method is based on IEEE Std. 1459-2010, ST, and the significant relationship of spectral impedances components (ZS) that been extracted from the ZTFR, consist of the fundamental impedance (Z1) and harmonic impedance (Zh). This experiment was conducted out on an IEEE 4-bus test feeder with a harmonic producing load in numerous different scenarios. The experimental was tested and verified for three consecutive months. The findings of this study reveal that the proposed method provides 100 percent correct identification of harmonic source location.
                            
                         
                     
                 
                
                            
                    
                        A Concept of Virtual-Flux Direct Power Control of Three-Phase AC-DC Converter 
                    
                    Nor Azizah Mohd Yusoff; 
Azziddin M. Razali; 
Kasrul Abdul Karim; 
Tole Sutikno; 
Auzani Jidin                    
                     International Journal of Power Electronics and Drive Systems (IJPEDS) Vol 8, No 4: December 2017 
                    
                    Publisher : Institute of Advanced Engineering and Science 
                    
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                                DOI: 10.11591/ijpeds.v8.i4.pp1776-1784                            
                                            
                    
                        
                            
                            
                                
This paper presents a proposed technique of virtual-flux direct power control (VF-DPC) as the improvement in control method from the basic of conventional direct power control (DPC) for front-end three-phase pulse width modulated (PWM) in ac-dc converter. Three sensors in order to measure the three phase input voltage have been eliminated in the proposed method of virtual flux (VF) regarding from the estimation technique. Theoritical principles of VF-DPC are discussed in this paper. The steady-state performance of VF-DPC and conventional DPC are evaluated and presented in this work to estinguish for the excellent performance. It is shown that the VF-DPC exhibits the several advantages, particularly in providing low total harmonic distortion with almost sinusoudal of input current and unity power factor (pf) operation under balanced three phase voltage supply. The simulation results from both methods through Matlab simulation have demonstrated the outstanding performance of the new proposed control technique from VF-DPC.