Aihsan, Muhammad Zaid
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Torque ripple minimization in direct torque control at low-speed operation using alternate switching technique Aihsan, Muhammad Zaid; Jidin, Auzani; Alias, Azrita; Ahmad Tarusan, Siti Azura; Md Tahir, Zuraidi; Sutikno, Tole
International Journal of Power Electronics and Drive Systems (IJPEDS) Vol 13, No 1: March 2022
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijpeds.v13.i1.pp631-642

Abstract

Direct torque control (DTC) of induction motor is prominent to offer instant torque and flux control with a simple control structure. However, this scheme suffers from two major drawbacks namely high torque ripple and variable switching frequency of the inverter, especially during low-speed operation. During the low-speed condition, the positive torque slope is very steep and torque overshoot occurs frequently resulting in the torque ripple become of great significance. This paper proposes a new and effective technique to reduce the torque ripple by integrating the alternate switching technique to the inverter switching status to limit the torque slope surge. By varying the frequency and duty cycle of the alternate switching, the rate of surge can be controlled resulting in the chances of overshoots, and selection of reverse voltage vector can be avoided. The feasibility of the proposed technique has been validated using MATLAB/Simulink software and through experimental results. The results show the proposed alternate switching technique minimizes over 40% reduction in the torque ripple while maintaining the simple structure of DTC.
Analysis of cascaded H-Bridge multilevel inverters using SPWM with multi-sinusoidal reference Alias, Azrita; Halim, Wahidah Abdul; Azri, Maaspaliza; Lazi, Jurifa Mat; Aihsan, Muhammad Zaid
International Journal of Power Electronics and Drive Systems (IJPEDS) Vol 16, No 3: September 2025
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijpeds.v16.i3.pp1740-1751

Abstract

Multilevel inverters have become the preferred choice for medium voltage and high-power applications due to their superior waveform quality, reduced stress on switching components, and overall enhanced performance. Among these, the cascaded H-bridge inverter stands out for its simpler control and modulation techniques, as well as its greater efficiency compared to other multilevel inverter topologies. This paper presents the design and performance evaluation of a cascaded H-bridge multilevel inverter (CHMI) for five, seven, nine, eleven, thirteen, and fifteen levels, utilizing sinusoidal pulse width modulation (SPWM) in MATLAB Simulink. The proposed technique, the multi-sinusoidal reference, is implemented by comparing multiple sinusoidal wave signals with a carrier triangular signal, with the resulting comparison pulses used to control the inverter's switching. The output results indicate that as the number of levels in multilevel inverters increases, the total harmonic distortion (THD) decreases, and the output voltage improves.
Experimental validation of virtual flux concept in direct power control with dynamic performance Hariri, Muhammad Hafeez Mohamed; Yusoff, Nor Azizah Mohd; Aihsan, Muhammad Zaid; Sutikno, Tole
International Journal of Power Electronics and Drive Systems (IJPEDS) Vol 16, No 4: December 2025
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijpeds.v16.i4.pp2509-2520

Abstract

The virtual-flux direct power control (VFDPC) technique is a sensorless control approach aimed at improving the performance of grid-connected power converters. The approach involves simulating the grid voltage and AC-side inductors similar to an AC motor drive system, a principle deriving from direct torque control (DTC). The basic idea of VFDPC is to indirectly estimate the voltage at the converter's input through the concept of virtual flux, enabling the real-time calculation of instantaneous active and reactive power without necessitating direct voltage measurements. An essential element of the VFDPC approach is the implementation of a lookup table, used as a decision-making tool that identifies the most suitable voltage vector (a particular output state of the converter) in accordance with real-time power conditions. This provides instantaneous and smooth control of power flow, leading to enhanced operational stability. This approach allows for continual optimization of the converter's output, enabling VFDPC to significantly decrease total harmonic distortion (THD) while preserving reliable steady-state and dynamic performance. Experimental validation demonstrates that incorporating real-time feedback into virtual flux estimates improves the precision of voltage prediction and the responsiveness of the power control system. Consequently, VFDPC exhibits enhanced adaptability for various grid and load situations, presenting an appropriate choice for current power systems that demand efficient, reliable, and sensorless operation.