5 Control questions

1. What submachines does the semiconductor transformer of direct-current consist of self-excited and their setting is which?

2. What submachines does the semiconductor transformer of direct-current consist of with a power-amplifier and their setting is which?

3. You will explain principle of action of semiconductor transformer self-excited with the unrectangular (linear) and rectangular loop of hysteresis mandrel of transformer.

4. You will explain principle of action of semiconductor transformer with a power-amplifier.

5. Why in transistor transformers is the rectangular form of variable tension used and what factors this form depends on?

6. That is external (loading) description of transistor transformer? you will explain her.

7. Why the transistor transformers of direct-current have relatively high к. п. of д. ? will Explain reasons of his increase at diminishing of frequency of transformation of transformer.

8. Are dignities and lacks of transistor transformers of direct-current which?

9. Bring a chart over of construction of transformer with a коммутирующим transformer. you will explain the features of her work. Give comparative description of different charts of transformers of permanent tension self-excited.

10. Is it possible in composition power part of transformer to use the transistors of other structure? If yes, then what changes is it necessary to produce in a chart, to apply these transistors?

11. You will represent the temporal diagrams of currents and tensions in the chains of chart, indicated by a teacher.

12. You will explain the features of work of the investigated chart in the mode of short circuit in the chain of loading.

6 The Laboratory task. Table of contents of work

6.1 To study theoretical material on the recommended literature. Setting, features of structural, functional, circuit technology construction of transistor transformers of permanent energy, and also processes of their functioning.

6.2 To investigate the chart of transistor transformer self-excited at four variants of loading : active character (k = 1), inductive character (k = 2), capacity character (k = 3) and at the use of L-type LC -фильтра (k = 4) :

6.2.1 To take off external (loading) descriptions of transformer (at k = 1.4).

6.2.2 To define output resistances and percent lowering of output tensions of transformer.

6.2.3 To define output-input of transformer ratios.

6.2.4 Experimentally to define dependence of changes of frequency of transformation of transformer at the change of current of loading from a minimum to the maximum.

6.2.5 To investigate the processes of functioning of transformer :

• pulsations are in the entrance and output chains of transformer;

• electric processes (currents and tensions) are in elements and chains of transformer.

6.3 To formulate conclusions on results the executed work

7 Methods of implementation

7.1 To the point 6.1. Program and order of study of theoretical questions.

To study setting, features of structural, functional, circuit technology construction of transistor transformers of direct-current and processes of their functioning for [2.1.2.5] and to materials of this laboratory work.

To study the features of circuit technology execution of laboratory model (см. of разд. 3).

To get for a teacher control questions on the studied material and to prepare answers on them. To specify for a teacher a form and volume of their presentation in a report.

NOTE. Further implementation of work is shut out without permission of teacher. By an obligatory condition to admittance for implementation of work there is getting a clear idea of features of circuit technology execution of the laboratory setting.

7.2 To the point 6.2. Research of transistor transformer of direct-current self-excited.

The required variant of the k loading of transformer is provided by commutation of switches of SW1, SW2 (fig. 3.1). At the reserved conducting state of switch of SW3 work of transformer is provided on-loading, and at broken a secret - in the mode of idling.

7.2.1К to the point 6.2.1. Research of external (loading) descriptions of transformer.

External description is dependence of tension on loading from a current which passes through her : Uн = f (Iн).

Gradually increasing the current of loading to the maximal value, to fix 5.7 his values, evenly breaking up a range measuring. To measure at these values of current of Iн of size of Iп, Uп, Uн, Тпр. To bring the got values in a table. 7.1(k), where k is a variant of loading of transformer (k = 1, 2, 3, 4).

Table 7.1(k) are Results of researches

№ измер.

Experienced data

Calculation data

Iн, A

Uн, B

Uп, B

Iп, A

Тпр, with

∆Uн, In

∆Iн, And

rпр, Ohm

Pп, W

Pн, W

fпр, Hertzs

η, %

1 2 …

The methods of determination of external description following:

• to disconnect loading, transferring the switch of SW3 in the broken a secret non-conducting state;

• to begin a design, pushing the button "Start";

• to take off tension of single Uн of хх motion of transformer. To bring a result in a table. 7.1(k);

• to connect resistance of Rн of loading, transferring the switch of SW1 in the reserved, conducting state;

• changing resistance of Rн of loading (using the movable indicator of "Rн" - см. рис. 3.1, right bottom corner) from a minimum (maximum) to the maximum(for example, Rн = 1, 2, 5, 10, 25, 50 and 100 Ohm), to take statements: voltmeters of PV1, PV2 - accordingly, tension of Uп on the output of source of G1 and Uн is tension in the chain of loading of transformer; ammeters of PА1, PА2 is a соот-ветственно current of Iп, consumed from the source of G1, and current of Iн in the chain of loading of transformer. To bring a result in a table. 7.1(k);

• on results research to build external descriptions.

Like to execute research for other variants of the k loading of transformer.

7.2.2 To the point 6.2.2. Determination of output resistances of the percent lowering of output tension of transformer.

Output resistance of transformer is determined on a formula

r_пр = U_н/ I_н = (U_{н max} – U_н) / (I_{н max} – I_н),

where Uн max, Iн max are maximal values accordingly of tension and current of loading.

Percent lowering of Uн% of output tension of transformer in transition from idling with tension of Uн хх to the nominal loading with output tension of Uн of nomas determined in a kind

.

7.2.3 To the point 6.2.3. Determination of output-input of transformer ratio.

An output-input of transformer ratio is determined through the values of powers on the output of Рн (Рн = IнUн) and on the entrance of Рп (Рп = IпUп) :

= P_н / P_п.

7.2.4 To the point 6.2.4. Experimental determination of frequency of transformation.

The experimental value of working frequency of transformer is determined on an oscillogram (u_W1(t) (TV1, U1 - in accordance with table. 3.3) or u_W2(t) (TV1, U2)). For this purpose it is necessary to measure duration of period of Тпр of the looked after curve on the mask of oscillograph, using the values of size of n multiplier "Time/Division" of the same name switch of oscillograph. The measureable temporal interval of T is determined by work of T = ln of two sizes : lengths l measureable time domain on the screen for horizontals in divisions and values of size of n time on a division in this position of switch "Time/Division". In this case

fпр = 1/Tпр=1/(l n).

7.2.5 To the point 6.2.5. Research of processes of functioning of transformer.

The oscillograms of the looked after sizes it is necessary to represent on an interval 1,5.2 period. The entrance of oscillograph must be commuted on the reception of signals of direct-current by the c account of permanent constituent (except for the cases of research of variables of constituents, for example tensions of uп(t) on the entrance of tension of uн(t) on the output of transformer, tensions of uС1(t),.).

Research of pulsations is in the entrance and output chains of transformers

The methods of research of pulsations in the entrance and output chains of impulsive transformers suppose implementation of next steps (to bring the results of measuring in a table. 7.2 (k)) :

• to set resistance of Rн = Rном in the chain of loading of ПЭЭ, using the movable indicator of "Rн" (см. рис. 3.1);

• to begin a design, pushing the button "Start" is a fig. 3.1;

• to take statements of voltmeters of PV1, PV2 and ammeters of PА1, PА2. Results of measuring of Uп, Uн and Iп, Iн to bring in a table. 7.2 (k);

• to measure the scope Uп~ and frequency of fпu pulsation of tension in a foodchain - in the entrance chain of transformer on the oscillogram of tension of uп(control point of "G 1, U" in accordance with a table. 3.3);

• to measure the scope Iп~ of pulsation of current in a foodchain - in the entrance chain of transformer on the oscillogram of iп(G1, I);

• to measure the scope Uн~ and frequency of fнu pulsation of tension in the chain of loading of transformer on the oscillogram of tension of uн(control point of Rн, U in accordance with a table. 3.3);

• to measure ∆IR~ of pulsation of current in resistance of Rн on the oscillogram of current of iн(Rн, I is a table. 3.3);

• researches on this methods to execute for four variants the k loading of transformer at the currents of loading of Iном and 0,5Iном - to bring the results of researches in a table. 7.2 (k).

Drawing on the results of experiment (table. 7.2 (k)), to expect and fill calculation part of table 7.3 (k) taking into account next correlations.

The results of experiment allow to define the coefficients of pulsations and rationed frequencies :

Table 7.3 (k) are Results of researches

№ п/п	Experimental part
	Iн, And	Iп, And	Uп, B	Uн, B	Rн, Ohm	fпu, кГц	∆Uп~, In	∆Iп~, And	fнu, кГц	∆Uн~, In	∆IR~, And
1 2 …

Coefficients of pulsations on an entrance (current of Kпп and tensions of KппU), in the chain of loading (current of KпнR and tensions of KпнU) of transformer settle accounts in a kind

Table 7.4 (k) are Results of calculations

№ п/п	Calculation data
			Kпв	KпвU	KпнU	KпнR
1 2 …

Research of electric processes of transformers

At the image of oscillograms it is necessary correctly to specify a timebase. Changing resistance of Rн of loading, to set the basic value of current of loading of Iн = Iн Nome. To look after and reflect the change of form of temporal diagrams in oscillograms at the currents of loading of Iн of nomas and 0,5Iн nomas, saving their peak and temporal correlations.

To look after and sketch the oscillograms of electric processes in elements and chains of transformer in accordance with the table of 3.3:

• a variable making tensions of uС2(t) on the condenser of С2;

• current of iVT1(t) collector of transistor of VT1;

• current of iVD1(t) diode of VD1;

• current of iL1(t) throttle of L1;

• variables constituents of tensions of uн(t) on loading of Rн and uп(t) on the entrance of transformer and т. of д.

Diagrams must be represented in one scale on a horizontal.

7.3 To the point 6.3. Conclusions on results work. Registration of report taking into account the requirements of division 6 the real laboratory work.

Conclusions on the done work must contain briefly and the clearly formulated positions essence of the looked after phenomena or got graphic dependences opens up in which. Conclusions must not establish external signs, and to explain them, setting unity of theory and experiment, explaining the fundamental difference of one case from other (for example, constancy of working frequency of transformer with external self-exciting and change of her in a transformer self-excited at the change of current loading and etc.).