Open Switch Analysis in Voltage Source Inverter
VSI switches faults are modeled using MATLAB as shown in Fig. 1. The model consists of 50V DC and RLC circuit as an arbitrary load. Fig. 1 shows three modules in the Simulink modeling of VSI consist of module fault generation, gate signal modules and pulse width modulation modules [5-8]. Figure below illustrated F1 indicate open-circuit fault and F2 is short-circuit faults. As mentioned [9], short-circuit faults are caused by bond wire rupture, impact ionization, gate circuit degradation and over-current.If short-circuit fault occurs in the VSI system, it will cause system shutdown. But, an open-switch fault does not cause a system shutdown but degrades the system performance.
Fig. 2 shown flow-chart of the analyses system which are consists of four phases. Phases 1 is design VSI circuit using Matlab/Simulink then generate fault for open-circuit and short-circuit. Four types of signal current was collected with different condition. From the signal current, two techniques that used which are spectrogram and STFT for analysis signal and parameter was calculated. The phase 2 is VSI system has six switches and each of switches have different condition of signal. The open-circuit and short-circuit switches faults can be identify depends on different signal current pattern. Then phase 3 is parameters estimation such as average, RMS, fundamental and TWD was calculated and summarize the error of current using bar graph for classify type of faults. Lastly phase 4 is summarizing bar graph and table of characteristic that used as a rule detection type of faults
Time Analysis Frequency Technique
Time-frequency Distributions (TFDs) are used to analyze or characterize signals whose energy distribution varies in time and frequency. TFDs such as STFT or spectrogram is popular and widely used in many applications such as speech, communications, acoustics and power electronic. This technique roughly reflects how frequency contents