MARCH 25-28
Diagnosis of Open Circuit Fault in PWM Inverter Fed Induction Motor Y. Soufi Electrical Department, Faculty of Science Engineering University of Tébessa, Tebessa, Algeria E-mail:
[email protected] T. Bahi Electrical Department, Faculty of Science Engineering University of Annaba, Annaba, Algeria E-mail:
[email protected] M. F. Harkat Electronic Department, Faculty of Science Engineering University of Annaba, Annaba, Algeria E-mail:
[email protected] Copyright © 2010 MC2D & MITI
Abstract: Thanks to strong technological development of semi conductors, the three phase PWM inverter fed induction motor is widely used in industry in variable speed system in the different field of industry. However, the rapid and accurate diagnosis of any system employing electrical drive system remains one of the current problems. For this purpose, many publications have investigated the detection a fault in electrical machines supplied directly on line or supplied by pulse width modulation (PWM) voltage source inverter. However, much fewer research results have been published when the induction motor is fed by inverter voltage, particularly, where a semi driver and default, work may have considered their study in the field diagnostic. This work present a method of diagnosing a defect of semiconductor when open circuit fault occure .The proposed method is achieved by using open circuit in the inverter. The obtained simulation results show clearly the possibility of extracting signatures to detect and isolate faults.
Keywords: Fault diagnosis, Isolation, Inverter, Simulation. 1. Introduction The power electronics inverter has been widely used for the variable speed control of the threephase induction motors in the fields of industry. The inverter is one of the most brittle parts in the drive system, once abrupt faults occur, the whole system will lose the ability to work
properly and even bring a series of severe disasters. In order to improve the reliability, the studies on the robust drive system for AC motors are being focused related to fault diagnosis techniques [1]. A three-phase voltagesource usually supplies the induction motor used variable-speed AC drives can be used in so many different applications. There are many
published techniques, several methods were presented and discussed in the literature and many commercially available tools to monitor induction motors to insure a high degree of uptime reliability. In spite of these tools, many companies are still faced with unexpected system failures and reduced motor lifetime. Studies of behaviours during abnormal conditions and the possibility to diagnose these conditions have been a challenging topic for many electrical machine researchers [N. Mehala, R. Dahiya “5 IDT].For the study of transistor open circuit fault, The majority of the methods presented detected the defect by the follow-up of evolution of current and its analysis in the frequential field or by the analysis of the evolution of space vector current in αβ plan [1]-[2]-[3]-[4]-[5]. Other methods were directed towards the minimization of time between the appearance of the defect and its detection. This type of defect has for principal cause a failure of signals PWM generator: thermal defect of the driver or loss of feeding [17]. In this work, we present a method for detection and isolation faults of an association converter induction machine: this method uses the phase current of the motor. It consist to analyze the evolution of three phase’s currents to order to find out according to their appears aim which is appears the default and according to different current into two others. The obtained simulation results show clearly the possibility of extracting signatures to detect and locate faults with the methods cited above. The results are useful and this work gives for the users of this field the possibility to choose the method appropriate to the considered system in order to develop and progress this research disciplinary. 2. System and Mathematical Model The three phase voltage inverter is based on three cells of commutation .Where DC voltage inverter input and presents the logic state corresponding to the conducting. In a three phase’s system, the vector components are separate from each other by an angle of 120°. Each commutation cell can be regarded as a phase of the inverter. This system is controlled by a Pulse Width Modulation (PWM) generator module. The command of the complementary switch of the same cell is assumed unchanged initially. Based on this command, a mean variable voltage is applied to the motor at each commutation period. We study the effect of the damage of every switch of the inverter respectively.[YOUCEF IREMOS+ Bowin]
3. Inverter Model The operation of the three phase voltage inverter used for electrical drive is based on the relationship between the input and output of the inverter depending on the mode of operation. This amendment called switching is performed by a suitable control circuit that provides temporal switches. In our case, we use the strategy of pulse width modulation. About inverter modeling, it is considered that cells (TRi=Ki) Transistors and Diodes Di) are switching instant and each switch to two Boolean statements. The inverter can be regarded as an ideal converter. However, the state "1" represents the mode works and the "0" stop mode of the device.
1 if K i is ON S 0 if K i is OFF
(1)
Using the concept of switching function switches, the relationship between input and output of the inverter is expressed by the following equation:
TF S1
S2
S3
(2)
Where TF is the transfer function, Vd is the input voltage, and Vio are the output voltages of the inverter with i = a, b and c. In case of failure of semi-conductor Ki (i =1: 6) open circuit phase (a, b or c) the engine is connected to the positive electrode of the voltage across the current flowing through the diode Di. The voltage (Vjn) depends on the state of semi conductor and the direction of the current phase. The switching function corresponding to the failures have led to table 1. Table 1: Expressions of Switching Functions K1 fault
K4 fault
1 if ian 0 S1 ' 1 if ian 0 , K 4 1 1 if i 0 , K 0 an 4
1 if ian 0 S1 ' ' 1 if ian 0, K1 1 1 if i 0, K 0 an 1
K2 fault
K5 fault
1 if ibn 0 S 2 ' 1 if ibn 0, K 5 1 1 if i 0, K 0 bn 5
1 if ibn 0 S2 ' ' 1 if ibn 0, K2 1 1 if i 0, K 0 bn 2
K3 fault
K6 fault
1 if icn 0 S 3 ' 1 if icn 0 , K 6 1 1 if i 0 , K 0 cn 6
1 if icn 0 SW3 ' ' 1 if icn 0, K3 1 1 if i 0, K 0 cn 3
4. Simulation Results and Interpretation
300 200 100 0 0
0.5
1 Time(s)
1.5
2
20 10
0 Isa -10
Isb Isc
0
1.1
1.2 1.3 Time(s)
-10 -20
0
0.5
1 Time(s)
1.5
2
20 Stator current(A)
Healthy 10
10
Stator current(A)
Electromagnetic Torque(N.m)
-100
Isa Isb isc
-10
1.1
-10
0
0.5
1 Time(s)
1.5
2
Figure.1. Waveforms of the drive system without fault
1.5
0
-20
-20
1.4
TR1 fault
10
0
Stator current(A)
Speed(rad/s)
400
In Fig. 2, we have presented the phases currents, when the higher semi-conductor TR1 in fault. The Fig. 3, shows the wave forms when TR4 in fault. Comparing between the two faults of (TR1 and TR4), we notice that for TR1 fault represented in figure 2, that the current phase_a takes the negative value or the currents phase_b and phase_c takes positive values. Contrary to results represented in figure 3 corresponding to TR4 fault, the current phase_a takes the positive values and currents phase_b and phase_c takes negative values which is the opposite situation to TR1 fault case. In this situation, the first method of fault detecting is used; it permits detection and isolation of the faulty semi conductor in the first leg. Stator current(A)
Using the model of the system and MatLab simulation, we have presented on figures 1, the results for the case of inverter without fault. This figure shows respectively the speed, electromagnetic torque, stator currents. We notice that after a time of starting of 0.6 second, the previous values are stable at their permanent values.
1.2 1.3 Time(s)
1.4
1.2 Time(s)
1.4
TR4 fault 10 0 Isa Isb Isc
-10
1
Figure.2. Current waveforms with TR 2 fault
1.5
Stator current(A)
TR2 fault
10
5. Conclusion 0 Isa Isb Isc
-10
Stator current(A)
1.1
1.2 1.3 Time(s)
1.4
1.5
TR5 fault 10 0 Isa Isb Isc
-10 -20
1.1
1.2 1.3 Time(s)
1.4
References [1] Yufan Guan, Dan Sun and Yikang He, “Mean Current Vector Based Online RealTime Fault Diagnosis for Voltage Source Inverter fed Induction Motor Drive,” in Proc. IEEE 2007, pp: 1114-1118. [2] André M. S. Mendes and A. J. Marques Cardoso, "Fault-Tolerant Operating Strategies Applied to Three-Phase Induction-Motor Drives" , IEEE transactions on industrial electronics, vol. 53, no 6, December 2006, pp: 1807-1817.
Figure.3.. Current waveforms with TR1 or TR5 fault
Stator current(A)
TR3 fault 10 0 Isa Isb Isc
-10
Stator current(A)
1
1.1
1.2 1.3 Time(s)
In this paper, we proposed a diagnosis method for the open circuit faults of semiconductors in an inverter fed induction machine. In order to validate this approach, a mathematical model was used for its simulation. The diagnosis used technique in this study permit through the analysis of the stator currents of each phase to extract signatures for detection and location of the semiconductors in case of open circuit failure. Indeed, the evolution of currents of each stator phase and the obtained simulation results are promising and precise to detect and isolate the fault of conductor electrical drive system that has been studied
[3] Debaprasad Kastha and Bimel K. Bose, " Investigation of Fault Modes of Voltage – Fed Inverter System for Induction Motor Drive " , IEEE transactions on industry applications, vol. 30, no 4, July/August 1994, pp :1028-1038.
1.4
TR3 fault 10
[4] Ok-Sun Yu, Nam-Ju Park and Dong-Seok Hyun, " A Novel Fault Detection Scheme for Voltage Fed PWM Inverter ", IEEE 2006, pp: 2654-2659.
0 Isa Isb Isc
-10 -20 1.1
1.2 1.3 Time(s)
1.4
1.5
Figure.4.. Current waveforms with TR1 or TR5 fault
[5 ] F. Zidani, D. Diallo, M.E.H. Benbouzid and R. Nait-said, "A fuzzy-based approach for diagnosis of fault modes in a voltage –fed PWM inverter induction motor drive",
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machine drive: a reliability,’’ July 2008.
trend
towards
[16] M.R. Mamat, M. Rison and M.S. Khanniche, "Fault Detection of 3-Phase VSI using Wavelet-Fuzzy Algorithm", American Journal of Applied Sciences , Vol 3, No 1 , pp. 1642-1648, 2006. [17] M. Trabelsi, M. Boussak, M. Gossa, "Open Circuit Faults Diagnosis of PWM Inverter-Fed Induction Motor by Stator Current Signature Analysis", 10th International conference on Sciences and Techniques of Automatic control & computer engineering, pages 1798-1810
