N. S. Ahmad , A. R. Abdullah and N. Bahari 195
0.1 0.2
0.3 0.4
0.5 0.6
0.7 0.8
0.9 1
1.1
Fig.10. Parameter Estimation for open-circuit fault
upper a Instantaneous Average Current, Iavet
b Instantaneous RMS Current, Irmst c Instantaneous RMS Fundamental Current,
Irmst d Instantaneous Total Waveform Distortion,
TWDt
5.3 Short Circuit Switches Fault in VSI Upper Fault
Fig. 11a shows signal short circuit switches fault where three-phase current indicate the fault also occur at
phase A where current signal is increase at 0.2 – 0.3 s. At
current signal at phase B and C is decrease when fault occur. Based on Fig. 11b, the TFR detect two frequency at faults
signal, where fundamental and fault frequency. From the contour, the spectrogram is show three-axis where the
detect fault at DC component is 0 Hz and 60 Hz for fundamental frequency.
Fig.11. a Signal of Short-Circuit Fault Upper
b Spectrogram Short-Circuit Fault Upper Fig. 12 a shows the average current, phase A is higher
compare phase B and C at 0.2 – 0.3 s. During the RMS
current, the phase A is phase faults occur where the value of current is higher compare with phase B and C as shows Fig.
12b. According Fig.12 c, the RMS fundamental for phase A is momentary decrease but other phase is higher
than phase fault occurring. While, value of TWD gives 1.4 percent and phase B and C is below than 1 percent as show
Fig. 12 d. 0.1
0.2 0.3
0.4 0.5
0.6 -0.5
0.5 1
Time sec
A m
p li
tu d
e Instantaneous Average Current, Iavet
C u
rr en
t, A
Time s a
Phase A
Phase B C
Instantaneous RMS Fundamental Current, Irmst
Phase A Phase B
Phase C
Time s c
C u
rr en
t, A
0.1 0.2
0.3 0.4
0.5 0.6
1 2
3 Instantaneous Total Waveform Distortion, TWDt
P er
ce n
ta g
e,
Phase A Phase B C
Time s d
0.1 0.2
0.3 0.4
0.5 0.6
-3 -2
-1 1
2 3
0.1 0.2
0.3 0.4
0.5 0.6
-3 -2
-1 1
2 3
0.1 0.2
0.3 0.4
0.5 0.6
-3 -2
-1 1
2 3
C u
rr en
t, A
P ha
se A
P ha
se B
P ha
se C
Time s a
Short-circuit Faults of the Upper Switch Signal
F re
q u
en cy
, H
z Time Frequency Representation
Time s b
0 Hz 60 Hz
0.1 0.2
0.3 0.4
0.5 0.6
0.9 0.95
1 1.05
1.1 1.15
Time s b
Instantaneous RMS Current, Irmst
C u
rr en
t, A
Phase C Phase A
Phase B
196 Open and Short Circuit Switches Fault Detection of Voltage Source Inverter Using Spectrogram
Fig.12. Parameter Estimation for short-circuit fault Upper
a Instantaneous Average Current, Iavet b Instantaneous RMS Current, Irmst
c Instantaneous RMS Fundamental Current, Irmst
d Instantaneous Total Waveform Distortion, TWDt
5.4 Short Circuit Switches Fault in VSI Lower Fault