Diagnostic of Inverter Three Levels Associated with Asynchronous Machine

Diagnostic of Inverter Three Levels Associated with Asynchronous Machine

Mendaz Kheira 1, Bounoua Houria 1 , Flitti Mohammed 2

1Djilali Liabes University, School of Engineering Sciences, IRECOM Laboratory, Electrical Engineering department, Sidi bel abbes, 22000, Algeria

2 University of Tiaret, Engineering Sciences Department, ICEPS Laboratory,

Electrical Engineering department, TIARET, 14000, Algeria

Abstract

This article presented the diagnostic of the inverter +E

three level associate with the three-phase asynchronous

Phase R Phase S Phase T

squirrel-cage machines. Witch show the faults of the switches for this inverter and their influence on the

G1 D1 G1 D1

G1 D1

answers speed and torque.

D5 D5 D5

C1

1. Introduction

   The voltage source inverters is consisting a non controllable function in the power electronic, it is used in the variable methods application. The strategy obtaining by this technique is based on the study of speed variation in induction machine.

   G2 D2

   0

   G3

   C2 D3

   G2 D2

   G3

   D3

   G2 D2

   G3

   D3

   R

   S MAS T

   The strong evolution of this function was based, on the one hand, on the development of semi- conductor components entirely commandables, powerful, robust and fast, and on the other hand, on the quasi generalized use of the techniques known as pulse width modulated [1] [2].

2. Principle Operation of the Inverter Three Levels

   The figure (1) represents the general diagram of the one of topologies of the three-phase inverters on three levels. The source of voltage continuous is consisted association in series of two groups of condensers of filtering delivering an intermediate potential with half voltage (Ud/2=E).

   D6

   D6 D6 D4

   G4 D4 D4

   G4 G4

   -E

   Figure1. General diagram of the power circuit

   Each half-arm of the inverter is composed of two switches in series with their common point connected by a diode in the middle of the source continuous. The direction of the diode depends on the polarity of the half-arm.

   To analyze the potentials generated by the three-phase inverter three states, it is interesting to show the whole of the combinations of potentials between the three phases like their evolutions during one period. The presentation of the intrinsic possibilities of this structure constitutes a reference of analysis for the strategies of piloting.

   The figure (2) has an equivalent structure of the three-phase inverter three states in which the functions

   of semiconductors are symbolized by switches. Each arm of the inverter is schematized by three switches independently making it possible to connect the three terminals R, S, T with the three potentials of the +E source, 0, – E. Thus, the full number of combinations of the operating conditions of this type of inverter is of 27 (3*3*3).

   This number is to be compared with that of the three- phase inverter in two states which is of 8 (2*2*2). [2] [4] [6]

   To describe the various configurations of operation of the converter, let us look at initially the values which can take a simple voltage, for example. The simple voltage is entirely defined by the state of the four switches of the first arm of the inverter, made up each one by a switch which can be a transistor, a GTO or an IGBT and a diode in parallel:

   +E k G D , k

   G

   • D , k

     G D , k

     G

   • D

   Ud/2

   1 1 1 2

   2 2 3

   3 3 4

   4 4 (2)

   0

   Ud/2

   The possible configurations of only one arm of switch is of 24=16 states which one can represent by a quadruplet of 0 or 1 following the state of the switches, k1 , k2 , k3 , k4 only the three following configuration are

   implemented:

   -E S

   1st configurationG G G G

   1 1 0

   0:

   R URS

   UST T

   1 2 3 4

   VRN VSN VTN

   N

   Figure2. Equivalent structural of the three-phase inverter has three states.

   The figure (2.1-a) presents the state of the switches of first arm of the three-phase inverter of voltage has three levels. G1andnG2 are opened, G3 andG4 are blocked, the point R is connected to the noted higher

   Let us specify that the Neutral N of the receiver

   point +, the voltage VR0 E

   should not be connected to the point of the source. The potentials of the terminals R, S, T referred compared to

   2nd configurationG1G2G3G4 0 1 1

   0 :

   the point medium 0 are noted as follows: [2] [6]

   The figure (2.1-b) watch the setting has zero of the first

   V ,V ,V withV

   V V 0

   arm of the inverter, G1andG3 are opened, G1andG4

   R0 S 0 T 0

   R0 S 0 T 0

   are blocked, the point R is connected to the point

   Let us recall that the respective sums of the simple voltage is made up of the receiver are null. According to its potentials, the relations of the receiver are written.

   Simple voltage:

   medium 0, the voltageVR0 0 .

   3rd configurationG1G2G3G4 0 0 1 1 :

   The figure (2.1-c) illustrates the state of the switches for the third configuration of operation of the inverter

   three levels,

   G1andG2

   are blocked,

   G3 andG4

   are

   opened, the point R is connected to the noted lower

   Phase voltage:

   (1)

   point -, the voltage

   VR0 E

   Phase R

   Short-circuit of E1 :

   +E

   G1 D1

   1 1 1 0, 1 0 0 0, 1 0 1 0

   D5

   C1

   G2 D2

   R

   0

   0

   G3

   C2 D3

   D6

   G4 D4

   Short-circuit of E2 :

   0

   0

   1

   1

   1

   1

   1 , 0

   1 , 0

   0

   0

   0

   0

   1 , 0

   1 , 0

   1

   1

   0

   0

   1

   1

   Is they cause the disconnection of a phase of the engine: 0 0 0

   -E

   (a):1st configuration.

   Either they do not make it possible to ensure the connection of the phase of medium point some or direction of the current circulating in this phase:

   Phase R

   0 1 0 0, 0 0 1 0

   +E

   G1 D1

   D5

   C1

   G2 D2

   R

   0

   G3

   C2 D3

   D6

   G4 D4

   -E

   1. :2nd configuration

      Phase R

      +E

      G1 D1

3. Diagnostics Faults of Inverter Multi Levels

   D5

   D5

   The application domains of the three-phase inverters of voltage most known in industry are undoubtedly that of the electric drives at variable speed. The three-phase inverters, in spite of their qualities, which have pusses to reach thanks to the development of the power electronics, and the use quasi-generalized of the techniques known as of pulse width modulation, can present a structural fault such as the fault of closing of the semiconductors. This type of induced dysfunction of the constraints can be damages for the systems of production if the personnel are not informed and that a spurious shutdown is produced. Since, the equipment of protection intervenes only at the last stage of fault; it is thus obvious, that the investment in the field of the detection of the dysfunctions appears a solution

   C1 impossible to circumvent. [2] [3] [5]

   G2 D2

   R

   0

   G3

   C2 D3

   D6

   G4 D4

   -E

   1. :3rd configuration

   3.1. Diagnostics Faults of Inverter Three Levels

   In the inverter three levels, the voltage of phase, nine levels exist under normal unctioning, but their levels of voltage seem to be different with each fault from commutation. In the event of fault of commutation of K11, the voltage of phase for the positive period has

   Figure 2. The differents configurations for1sd arm of inverter three levels.

   only Vdc

   3

   (Vdc 2E) it because the current of phase

   Other sequences to be avoided because: Is they cause short-circuit of the continuous voltage:

   crosses the K12 switch in the state of P (positive). When

   the faults of the inverter three levels occur, the current overflowing in the point medium poses a great effect in the radial force/discharge of the condensers.

   Short-circuit of E1andE2 : 1 1 1 1, 1 0 0 1

4. Result Simulation

The simple tension of the inverter three levels (three states) takes the values ±2E, ±E, 0 what can be translated by the improvement of the form of wave of the output voltage of the inverter three states. The figures (3) show the voltage waveforms simple and

160

140

120

speed(rd/s)

speed(rd/s)

100

80

60

40

20

0

0 0.5 1 1.5 2 2.5 3

time(s)

phase at the exit of the inverter three states; one notice a clear improvement of the form of the voltage Van in the shape of staircase compared to the conventional inverter then figure (5) represented the result of statoric and rotoric current without fault. The figure (4) represents the speed then the torque which can have variations in permanent regime then stabilization in transitory regime. For a fault of the K11 switch of the inverter 3 states, the figure (6) illustrates the control of voltage disequilibrium when the fault of commutation occurs.

The figure (7) represents leads of asynchronous machine before and during the fault, which are translated by an augmentation of speed and the oscillations of the torque. After this oscillation the torque augments and we have a diminution of speed.

(a)

15

electromagnetique torque (Nm)

electromagnetique torque (Nm)

10

5

0

-5

-10

-15

-20

-25

-30

0 20 40 60 80 100 120 140 160

speed(rd/s)

(b)

15

10

The currents I

sa, Ira

resulting from the faults of the K11 0

electromagnetic torque(Nm)

electromagnetic torque(Nm)

5

5

switches illustrated by the figure (8) that show how the faults of this switches, induces a disequilibrium on these currents.

-5

-10

-15

-20

-25

-30

80

0 0.5 1 1.5 2 2.5 3

time(s)

60

40

voltage Van(V)

voltage Van(V)

20

0

-20

-40

-60

-80

0 0.01 0.02 0.03 0.04 0.05 0.06

time(s)

(c)

Figure4. Speed, electromagnetic torque and speed=t (torque) results of inverter three levels without fault

Figure3. The voltage results Vab and Van of inverter three levels without fault

50

40

30

current Isa(A)

current Isa(A)

20

10

0

-10

-20

-30

-40

(a)

0 0.5 1 1.5 2 2.5 3

time(s)

30

electromagnetique torque(Nm)

electromagnetique torque(Nm)

20

10

0

-10

-20

-30

0 20 40 60 80 100 120 140 160 180

speed(rd/s)

Figure7. Speed, electromagnetic torque and

40

30

20

current Ira(A)

current Ira(A)

10

0

-10

-20

-30

-40

-50

(b)

0 0.5 1 1.5 2 2.5 3

time(s)

speed=t (torque) results of inverter 3 level with fault in switch K11 at t (1.4, 1.6)

(a)

50

40

30

current Isa(A)

current Isa(A)

20

10

Figure5. The current Isa, Ira result of inverter three levels without fault

0

-10

250

200

150

voltage Van (V)

voltage Van (V)

100

50

-20

-30

-40

0 0.5 1 1.5 2 2.5 3

time(s)

(b)

0

-50

-100

-150

-200

-250

1.4 1.42 1.44 1.46 1.48 1.5 1.52 1.54 1.56 1.58 1.6

time(s)

Figure 6. The voltage results Van of inverter three levels with fault in switch K11 a t (1.4, 1.6)

(a)

180

160

140

speed (rd/s)

speed (rd/s)

120

100

80

60

40

20

0

0 0.5 1 1.5 2 2.5 3

time(s)

30

electromagnetic torque(Nm)

electromagnetic torque(Nm)

20

10

0

-10

-20

-30

0 0.5 1 1.5 2 2.5 3

time(s)

(b)

(c)

40

30

20

current Ira(A)

current Ira(A)

10

0

-10

-20

-30

-40

-50

0 0.5 1 1.5 2 2.5 3

time(s)

Figure 8. The current Isa, Ira result of inverter 3 level with fault in switch K11 at t (1.4, 1.6).

Conclusion

The developed of a new structure of the voltage inverters with three levels, like their principle of operation associated with an asynchronous machine, show that the results obtained give a clear improvement of the performances of the unit inverter machine compared to the conventional inverter. After proposed the diagnosis method of fault of the inverter three, which proposes the following advantage, the diagnostic of fault can easily identifies each fault of commutation.

REFERENCES

1. G. Seguier, F. Labrique, les convertisseurs de lélectronique de puissance, volume 04, technique et documentation-Lavoisier, 1989

2. B. Ouhid, Sur la contribution de lanalyse des onduleurs multi niveaux, mémoire de magister, 2005.

3. B. Raison, Détection et localisation de défaillances sur un entrainement électrique, Thèse de doctorat, Institut National Polytechnique de Grenoble, France, 2000.

4. J.Noel fiorina, onduleurs et harmonique (cas des machines.Flux, magazine, n° 43 – trimestriel – octobre 2003 – cedrat – cedrat technologies – magsoft corp.

5. J. Sprooten., J.C. Maun, Internal fault analysis of induction charges non lineaires, CT édition juin 1992.

6. K. Mendaz «Développement de nouvelle méthodes numérique pour lanalyse dans la conversion des systèmes électromagnétiques de grande capacité», Mémoire de magister ; université de Sidi Bel Abbes 2008.