Fuentes del discurso intercultural

Syllabus:

Inverters – Single phase inverter – Basic series inverter – Basic

Inverters – Single phase inverter – Basic series inverter – Basic parallelparallel Capacitor inverter bridge inverter – Waveforms – Simple forced commutation circuits Capacitor inverter bridge inverter – Waveforms – Simple forced commutation circuits for bridge inverters – Mc Murray and Mc Murray – Bedford inverters - Voltage control for bridge inverters – Mc Murray and Mc Murray – Bedford inverters - Voltage control techniques for inverters Pulse width modulation techniques – Numerical problems.

techniques for inverters Pulse width modulation techniques – Numerical problems.

Objectives:

Objectives:



 Detailed Explanation of Inverters operation.Detailed Explanation of Inverters operation.



 Discussion of different modes of operation of an Discussion of different modes of operation of an InvertersInverters



 Commutation techniques of Inverters.Commutation techniques of Inverters.



 Discussion of different types of inverters (Mc Murray and Mc Discussion of different types of inverters (Mc Murray and Mc Murray – BedfordMurray – Bedford inverters).

inverters).



 Explanation of Voltage control techniques for InvertersExplanation of Voltage control techniques for Inverters



 Discussion of PWM technique.Discussion of PWM technique.



 Solving Numerical Problems.Solving Numerical Problems.

Schedule:

Schedule:



 Introduction Introduction to to Inverters Inverters - - 11



 SSiinnggllee pphhaassee IInnvveerrtteerr -- 11



 Basic Basic series series inverter inverter - - 11



 Basic Basic parallel parallel Capacitor Capacitor inverter inverter bridge bridge inverter inverter – – Waveforms Waveforms - - 11



 Simple Simple forced forced commutation commutation circuits circuits for for bridge bridge inverters inverters - - 11



 Mc Mc Murray Murray and and Mc Mc Murray Murray – – Bedford Bedford inverters inverters - - 11



 Voltage Voltage control control techniques techniques for for inverters inverters - - 11



 Pulse Pulse width width modulation modulation techniques techniques - 1- 1



 NNuummeerriiccaall pprroobblleemmss -- 11

Assignment Questions:

Assignment Questions:

1)

1)

Single phase half bridge inverter has a resistive load of R = 3 ohms and dcSingle phase half bridge inverter has a resistive load of R = 3 ohms and dc input voltage Edc = 50V.

input voltage Edc = 50V. CalculateCalculate

a.

a.

rms output voltage at fundamental rms output voltage at fundamental frequency E1frequency E1 b.

b. ththe oue outptput ut popowewerr c.

c. aveaveragrage and pee and peak cuak currrrent of eent of each tach thyrhyrististoror

2)

2)

A single phase full bridge inverter uses a uniform PWM with two pulses perA single phase full bridge inverter uses a uniform PWM with two pulses per ha

half lf cycyclcle e fofor r vovoltltagage e cocontntrorol. l. PlPlot ot ththe e didiststorortition on fafactctoror, , fufundndamamenentatall component, and lower order harmonics against modulation index.

component, and lower order harmonics against modulation index.

3)

3)

Draw and explain the simple SCR series inverter circuit employing class ADraw and explain the simple SCR series inverter circuit employing class A ty

type pe cocommmmututatiationon. . WiWith th ththe e hehelp lp of of imimpoportrtanant t wawavevefoformrms. s. StStatate e ththee limitations of this inverter.

limitations of this inverter.

4)

4) What are the difWhat are the differenferent pulse width mot pulse width modulatdulation technion techniques usiques used for invered for inverters.ters.

5)

5) WhicWhich of the scheh of the schemes givmes gives better qes better qualituality of voltagy of voltage and curre and current.ent.

6)

6)

CalCalculculate ate the the outoutput put frefrequequency ncy of of a a seserieries s invinverterter er circircuicuit t witwith h folfollowlowinging pa

pararamemeteters = rs = 1010mHmH, , C C = = 0.0.1 1 μFμF, , R R = = 40400 0 ohohmsms, , toftoff f = = 0.0.2 2 msmsecec. . AlAlsoso determine the attenuation factor.

determine the attenuation factor.

7)

7)

A single phase full bridge inverter uses a uniform PWM with two pulses perA single phase full bridge inverter uses a uniform PWM with two pulses per ha

half lf cycyclcle e fofor r vovoltltagage e cocontntrorol. l. PlPlot ot ththe e didiststorortition on fafactctoror, , fufundndamamenentatall component, and lower order harmonics against modulation index.

component, and lower order harmonics against modulation index.

8)

8)

The single phase modified Me Murray full-bridge inverter is fed by dc sourceThe single phase modified Me Murray full-bridge inverter is fed by dc source of 300V. The d.c. source voltage may fluctuate by ±15% . The current during of 300V. The d.c. source voltage may fluctuate by ±15% . The current during commutation may vary form 20 to 100A. Obtain the value of commutating commutation may vary form 20 to 100A. Obtain the value of commutating components, if the thyristor turn-off time is 20 μs. Also compute the value of  components, if the thyristor turn-off time is 20 μs. Also compute the value of  R.

R.

Objective Questions:

Objective Questions:

1. In a single-phase half (semi)-controlled bridge inverter, the gate signals to the 1. In a single-phase half (semi)-controlled bridge inverter, the gate signals to the main thyristors are given at an interval of 

main thyristors are given at an interval of  b. 90

b. 90 c. 120 c. 120 d. 180 d. 180

2. In a three-phase fully-controlled bridge inverter, the gate signals to the main 2. In a three-phase fully-controlled bridge inverter, the gate signals to the main thyristors are given at an interval of 

thyristors are given at an interval of  a. 60

a. 60 b. 90 b. 90 c. 120 c. 120 d. 180 d. 180

3. The frequency of output AC voltage is increased in an inverter by : 3. The frequency of output AC voltage is increased in an inverter by : a. Decreasing the input DC voltage

a. Decreasing the input DC voltage b. Increasing the input DC voltage b. Increasing the input DC voltage c. Decreasing the time period

c. Decreasing the time period between the triggering of the between the triggering of the successive thyristsuccessive thyristorsors d. Increasing the time period

d. Increasing the time period between the triggering of the successive thyristorsbetween the triggering of the successive thyristors

4. In a three-phase bridge inverter circuit, regarding the peak value of the output AC 4. In a three-phase bridge inverter circuit, regarding the peak value of the output AC voltage, it is

voltage, it is

a. The same as the input DC voltage a. The same as the input DC voltage b. Less than the input DC voltage b. Less than the input DC voltage c. More than the input DC voltage c. More than the input DC voltage d. It is not related to the input DC

d. It is not related to the input DC voltagevoltage

5. The total number

5. The total number of free-wheeling diodes in a three-phase fully-controlled bridgeof free-wheeling diodes in a three-phase fully-controlled bridge inverter will be

6. The total number

6. The total number of thyristors in a three-phase fully-controlled bridge inverter willof thyristors in a three-phase fully-controlled bridge inverter will be

7. In a single-phase bridge inverter, the gate signals to the main thyristors are given 7. In a single-phase bridge inverter, the gate signals to the main thyristors are given at an interval of 

8. Inverter is a power semiconductor converter, which is used for :power semiconductor converter, which is used for : a. AC to DC

a. AC to DC conversionconversion b. DC to

b. DC to AC conversionAC conversion c. DC to DC

c. DC to DC conversionconversion d. AC to AC conversion d. AC to AC conversion 9. The total number

9. The total number of thyristors in a single-phase fully-controlled bridge inverter willof thyristors in a single-phase fully-controlled bridge inverter will be

10. The total number of

10. The total number of thyristors in a single-phase half (semi)-controlled bridgethyristors in a single-phase half (semi)-controlled bridge inverter will be

d. 4 d. 4

11. The total number of

11. The total number of free-wheeling diodes in a single-phase fully-controlled bridgefree-wheeling diodes in a single-phase fully-controlled bridge inverter will be

12. The total number of

12. The total number of free-wheeling diodes in a single-phase half (semi)-controlledfree-wheeling diodes in a single-phase half (semi)-controlled bridge inverter will be

13. Two thyristors T1 and T2 a

13. Two thyristors T1 and T2 are used in a re used in a basic series inverter circuit to supply abasic series inverter circuit to supply a series R-L-C load from an input DC supply. If the time-delay between turn-off of T1 series R-L-C load from an input DC supply. If the time-delay between turn-off of T1 and torn-on of T2 is

and torn-on of T2 is increased, then, the inverter frequency willincreased, then, the inverter frequency will a. Remain constant

14. Two thyristors T1 and T2 a

14. Two thyristors T1 and T2 are used in a re used in a basic series inverter circuit to supply abasic series inverter circuit to supply a series R-L-C load from an input DC supply. If the time-period for oscillation of R-L-C series R-L-C load from an input DC supply. If the time-period for oscillation of R-L-C circuit is increased, then the inverter frequency will

circuit is increased, then the inverter frequency will ::

a. Remain constant

15. Two thyristors T1 and T2 a

15. Two thyristors T1 and T2 are used in a re used in a basic series inverter circuit to supply abasic series inverter circuit to supply a series R-L-C load from an input DC supply. When thyristor T1 is triggered, the load series R-L-C load from an input DC supply. When thyristor T1 is triggered, the load current

current

a. Will build up in positive half cycle a. Will build up in positive half cycle b. Will remain zero

b. Will remain zero

c. Will build up in negative half cycle c. Will build up in negative half cycle d. Will remain constant

d. Will remain constant

16. Two thyristors T1 and T2 a

16. Two thyristors T1 and T2 are used in a re used in a basic series inverter circuit to supply abasic series inverter circuit to supply a series R-L-C load from an

series R-L-C load from an input DC supply. When both the input DC supply. When both the thyristors are OFF, thethyristors are OFF, the load current

load current

a. Will build up in positive half cycle a. Will build up in positive half cycle b. Will remain zero

b. Will remain zero

c. Will build up in negative half cycle c. Will build up in negative half cycle d. Will remain constant

d. Will remain constant

17. Two thyristors T1 and T2 a

17. Two thyristors T1 and T2 are used in a re used in a basic series inverter circuit to supply abasic series inverter circuit to supply a series R-L-C load from an input DC supply. When thyristor T2 is triggered, the load series R-L-C load from an input DC supply. When thyristor T2 is triggered, the load current

current

a. Will build up in positive half cycle a. Will build up in positive half cycle b. Will remain zero

b. Will remain zero

c. Will build up in negative half cycle c. Will build up in negative half cycle d. Will remain constant

d. Will remain constant

18. In a basic parallel inverter, two thyristors T1 and T2 are used to switch the dc 18. In a basic parallel inverter, two thyristors T1 and T2 are used to switch the dc supply alternately to the

supply alternately to the two halves of the transformer primary. However, intwo halves of the transformer primary. However, in addition, for which condition of load

addition, for which condition of load will two feedback diodes become ewill two feedback diodes become essentialssential a. When the load is opened

a. When the load is opened b. When the load is shorted b. When the load is shorted

c. When the load is purely resistive c. When the load is purely resistive d. When the load is inductive

d. When the load is inductive

19. In a basic parallel inverter, two thyristors T1 and T2 are used to switch the dc 19. In a basic parallel inverter, two thyristors T1 and T2 are used to switch the dc supply alternately to the

supply alternately to the two halves of the transformer primary. When thyristor T1 istwo halves of the transformer primary. When thyristor T1 is turned on, the capacitor gets charged to the voltage of 

turned on, the capacitor gets charged to the voltage of  a.

a. 11 b.

b. 22 c. -2 c. -2 d. -1 d. -1

20. In a basic parallel inverter, two thyristors T1 and T2 are used to switch the dc 20. In a basic parallel inverter, two thyristors T1 and T2 are used to switch the dc supply alternately to the

supply alternately to the two halves of the transformer primary. When thyristor T2 istwo halves of the transformer primary. When thyristor T2 is turned on, the capacitor gets charged to the voltage of 

turned on, the capacitor gets charged to the voltage of  a.

a. 11 b.

b. 22 c. -2 c. -2 d. -1 d. -1

21. In a basic parallel inverter, two thyristors are used to switch the dc supply 21. In a basic parallel inverter, two thyristors are used to switch the dc supply alternately to the two

alternately to the two halves of the transformer primary. For this, which of halves of the transformer primary. For this, which of thethe following component is used to connect the input DC source to the mid point of the following component is used to connect the input DC source to the mid point of the transformer

transformer a. Resistance a. Resistance b. Inductor b. Inductor c. Capacitor c. Capacitor d. Diode d. Diode

22. In a basic parallel inverter, two thyristors are used to switch the dc supply 22. In a basic parallel inverter, two thyristors are used to switch the dc supply alternately to the two

alternately to the two halves of the transformer primary. For this, which of halves of the transformer primary. For this, which of thethe following component is used across the transformer primary

following component is used across the transformer primary a. Resistance

a. Resistance b. Inductor b. Inductor c. Capacitor c. Capacitor d. Diode d. Diode

23. In a basic parallel inverter, two thyristors T1 and T2 are used to switch the dc 23. In a basic parallel inverter, two thyristors T1 and T2 are used to switch the dc supply alternately to the

supply alternately to the two halves of the transformer primary. For this, where istwo halves of the transformer primary. For this, where is the load connected to get the alternating supply

the load connected to get the alternating supply a. Across one-half of the transformer primary a. Across one-half of the transformer primary b. In series with T2

b. In series with T2

c. Across the transformer secondary c. Across the transformer secondary d. In series with T1

d. In series with T1 24. In the McMurray -

24. In the McMurray - Bedford full-bridge inverter, total how many numbers of Bedford full-bridge inverter, total how many numbers of  thyristors will be required

thyristors will be required a. 2

a. 2 b. 4 b. 4 c. 6 c. 6 d. 8 d. 8

25. In the McMurray -

25. In the McMurray - Bedford full-bridge inverter, total how many numbers of Bedford full-bridge inverter, total how many numbers of  diodes will be required

diodes will be required a. 2

a. 2 b. 4 b. 4 c. 6 c. 6 d. 8 d. 8 26. In a

26. In a single-phase McMurray inverter, 4 main thyristors are used in a single-phase McMurray inverter, 4 main thyristors are used in a single-phasesingle-phase bridge configuration to supply a

bridge configuration to supply a load. How many numbers of auxiliary thyristors willload. How many numbers of auxiliary thyristors will be required for the commutation

be required for the commutation a. 1

a. 1 b. 2 b. 2 c. 3 c. 3 d. 4 d. 4

27. In the single-phase modified

27. In the single-phase modified McMurray full-bridge inverter, which of the followingMcMurray full-bridge inverter, which of the following component is added to the

component is added to the single-phase McMurray inverter :single-phase McMurray inverter : a. 4 auxiliary thyristors

a. 4 auxiliary thyristors

b. 4 auxiliary diodes b. 4 auxiliary diodes c. Additional 4 capacitors c. Additional 4 capacitors d. Additional 4 inductors d. Additional 4 inductors 28. In the modified

28. In the modified McMurray full-bridge inverter, total how many numbers of McMurray full-bridge inverter, total how many numbers of  thyristors (main +auxiliary) will be required

thyristors (main +auxiliary) will be required a. 2

a. 2 b. 4 b. 4 c. 6 c. 6 d. 8 d. 8

29. In the modified

29. In the modified McMurray full-bridge inverter, total how many numbers of McMurray full-bridge inverter, total how many numbers of diodesdiodes (main +auxiliary) will be required

(main +auxiliary) will be required a. 2

a. 2 b. 4 b. 4 c. 6 c. 6 d. 8 d. 8 30. In a

30. In a three-phase bridge inverter with sinusoidal PWM control, if the three-phase bridge inverter with sinusoidal PWM control, if the modulationmodulation index is increased from 0.5 to 0.8, then it results in

index is increased from 0.5 to 0.8, then it results in a. Decrease of output frequency

a. Decrease of output frequency

b. Decrease of RMS value of output AC voltage b. Decrease of RMS value of output AC voltage c. Increase of output frequency

c. Increase of output frequency

d. Increase of RMS value of output AC voltage d. Increase of RMS value of output AC voltage 31. In a

31. In a three-phase PWM bridge inverter with PWM control, which of three-phase PWM bridge inverter with PWM control, which of the followingthe following statements is true regarding the

statements is true regarding the output AC voltageoutput AC voltage a. Only RMS value can be controlled

a. Only RMS value can be controlled b. Only frequency of output

b. Only frequency of output AC voltage can be controlledAC voltage can be controlled c. Both RMS value and the frequency can be controlled c. Both RMS value and the frequency can be controlled d. No control of RMS value or frequency is possible d. No control of RMS value or frequency is possible

32. One of the main purpose of using a PWM control in a three-phase bridge inverter 32. One of the main purpose of using a PWM control in a three-phase bridge inverter is :

is :

a. Reduce the RMS value of the output AC voltage a. Reduce the RMS value of the output AC voltage b. Reduce the frequency of the

b. Reduce the frequency of the output AC voltageoutput AC voltage c. Reduce the harmonic content in

c. Reduce the harmonic content in the output AC voltagethe output AC voltage d. Reduce the number of devices in the inverter

d. Reduce the number of devices in the inverter

33. In sinusoidal PWM technique

33. In sinusoidal PWM technique for a three-phase bridge inverter, for the for a three-phase bridge inverter, for the generationgeneration of gating signals of

of gating signals of thyristors, which type of carrier wave and reference wave arethyristors, which type of carrier wave and reference wave are compared

compared

a. Sinusoidal reference wave is compared with

a. Sinusoidal reference wave is compared with sinusoidal carrier wavesinusoidal carrier wave b. Sinusoidal reference wave is compared with

b. Sinusoidal reference wave is compared with triangular carrier wavetriangular carrier wave c. Sinusoidal reference wave is compared with constant (DC)

c. Sinusoidal reference wave is compared with constant (DC) carrier wavecarrier wave d. DC reference wave is compared with

d. DC reference wave is compared with sinusoidal carrier wavesinusoidal carrier wave

34. In a single-pulse width control, the gating signals are generated by : 34. In a single-pulse width control, the gating signals are generated by : a. Comparing a rectangular reference signal

a. Comparing a rectangular reference signal with a rectangular carrier wavewith a rectangular carrier wave b. Comparing a rectangular reference signal

b. Comparing a rectangular reference signal with a sinusoidal carrier wavewith a sinusoidal carrier wave c. Comparing a sinusoidal reference signal with

c. Comparing a sinusoidal reference signal with a rectangular carrier wavea rectangular carrier wave d. Comparing a rectangular reference signal

d. Comparing a rectangular reference signal with a triangular carrier wavewith a triangular carrier wave

35. In PWM control of

35. In PWM control of inverters, the ratio of carrier frequency to reference or outputinverters, the ratio of carrier frequency to reference or output

35. In PWM control of inverters, the ratio of carrier frequency to reference or outputinverters, the ratio of carrier frequency to reference or output

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