Norhazilina Bahari

Modeling and simulation of torque hysteresis controller for brushless DC motor drives

This paper presents modeling and simulation of a torque hysteresis controller for brushless DC motors. Brushless DC (BLDC) motors can offer great advantageous compared to other machines used in industrial applications due to its compactness, high torque density, simpler controller and lower maintenance. At first the mathematical modeling of BLDC motor that is suitable to analyze the dynamic performance will be given. A method of torque hysteresis controller will be adapted to drive the motor such that the current (or torque) ripple can be restricted within the predefined band-gap. Moreover, a new current blocking strategy is proposed to prevent the current drained from DC supply when the torque demand is set to zero, that can prolong the capacity voltage of batteries. Some simulation results were carried out using MATLAB/Simulink to verify the proper modeling as well as functionality of the controller.

Short-circuit switches fault analysis of voltage source inverter using spectrogram

The identification of faults in voltage source inverter is highly required to ensure the reliability of the inverter. Early detection of the faults can greatly assist in maintenance of the system by avoiding possibly harmful damage borne out. This paper presents the analysis of short-circuit switches fault of voltage source inverter (VSI) using time frequency distribution (TFD). The TFD which is spectrogram represents current signal of the VSI in time-frequency representation (TFR) that provides temporal and spectral information of the signal. From the TFR, parameters of the signal are estimated such as average current, root mean square (RMS), total harmonic distortion (THD), total waveform distortion (TWD) and total non-harmonic distortion (TnHD). The results shows that the analysis using spectrogram gives information of the current signal of the VSI to identify short-circuit switches and can be implemented for faults detection system.

HEPWM using differential evolution technique for three phase voltage source inverter

This paper presents the implementation of Differential Evolution (DE) algorithm to solve Harmonic Elimination Pulse-Width Modulation (HEPWM) problem. HEPWM is widely used in eliminating the low frequency harmonic of output voltage of the inverter. The DE is a simple and efficient evolutionary algorithm in solving the HEPWM transcendental equation. Operations of DE technique were elaborated and the best approach of mutation strategy has been analyzed. Switching angles of HEPWM were calculated offline using DE technique. Then, the switching angles were applied to three-phase voltage source inverter (VSI). Simulation of DE technique and VSI experiment set up were run in Matlab/Simulink.

Differential evolution technique in solving HEPWM switching angles of three-phase voltage source inverter

This paper presents the solution for odd and even number of switching angles of harmonic elimination pulse width modulation (HEPWM). HEPWM capable to eliminate low order harmonics of inverter output voltage by solving the transcendental equation of the switching angles. The optimum switching angles are calculated using differential evolution (DE) algorithm. DE is simple and effective algorithm. The calculated switching angles applied to the three-phase voltage source inverter (VSI) and harmonic performance of output voltage are examined using MATLAB/Simulink software. The Total harmonic Distortion (THD) of line to neutral of inverter is analyzed for different number of switching angles. The simulation result showed that the low order harmonics, namely 5th, 7th, 11th, 13th, 17th, 19th, 23th was eliminated individually by N=3,4,5,6,7 and 8.

Comparison of Open and Short-Circuit Switches Faults Voltage Source Inverter (VSI) Analysis Using Time-Frequency Distributions

Voltage source inverter (VSI) plays an important roles in electrical drive systems. Consistently, expose to hash environmental condition, the lifespan of the electronic component such as insulated-gate bipolar transistor (IGBT) may shorten and many faults related to the inverter especially switches can be occur. The present of VSI switches faults causing equipment failure and increased the cost of manufacturing process. Therefore, faults detection analysis is mandatory to identify the VSI switches faults. This paper presents the analysis of VSI switches faults using time-frequency distributions (TFDs) which are short times Fourier transform (STFT) and spectrogram. From time-frequency representation (TFR) obtained by using the TFDs, parameters of the faults signal are estimated such as instantaneous of average, root mean square (RMS), fundamental, Total Waveform Distortion (TWD), Total Harmonics Distortion (THD) and Total non-Harmonic Distortion (TnHD) of current signals. Then, based on the characteristics of the faults calculated from the signal parameters, VSI switches faults can be detected and identified. The performance of TFD for the faults analysis is also demonstrated to obtain the best TFD for switches faults detection and identification system. The results show that, STFT is the best technique to classify and identify VSI switches faults and can be implemented for automated system.

Voltage Source Inverter Fault Detection System Using Time Frequency Distribution

Open-switch and short-switch in a three-phase voltage source inverter (VSI) have a possibility to fault due to problems of switching devices.Any failure of the system in these applications may incur a cost and risk human live. Therefore, knowledgeon the fault mode behaviour of an inverter is extremely important from the standpoint of system design improvement, protection and fault detection. This paper presents detailed simulation results on condition monitoring and fault behaviour of VSI. The results obtained from the developed monitoring system allows user to identify the fault current. The developed system showed the capability in detecting the performance of VSI as well as identifying the characteristics of type of faults. This system provides a precaution and early detection of fault, thus reduces high maintenance cost and prevent critical fault from happening.