CHAPTER 4

CIRCUIT DESCRIPTION

4.1 CIRCUIT DIAGRAM:The cyclo-converter generally consists of two converter group one of which is

called the positive converter and another one is negative converter. Generally the

switching device of positive converter group goes in conduction during positive half

cycle whereas the negative converter group goes in conduction during negative half

cycle of the input wave shape. The control circuit controls the operation of each

converter group and provides synchronization of the output signal with the input

signal.

Fig: 4.1 Circuit diagram of design & implementation of cyclo-converter using microcontroller

The single phase cyclo-converter is a 2 pulse cyclo-converter because there

are two phase controlled pulses per cycle of the output phase. Generally the

transformer is used for providing alternating output to the load and if a neutral return

is not required in a multiphase output application, the transformer can be removed to

simplify the circuit. The cyclo-converter has four thyristors divided into a positive and

negative bank of two thyristors each. The output voltage is controlled by phase

control of the positive and negative bank thyristors in accordance with the flow of

positive and negative current in the load respectively.

There are two groups of converter which can be defined as P and N. The P and

N converters control the positive and negative half cycles of the output voltage of the

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desired frequency respectively which is shown in the figure. The conduction intervals

of P and N converters are also marked in figure.

The positive converter operates whenever the load current is positive with the

negative converter remaining idle during this period. In a similar manner, the negative

load current is supplied by the negative converter with the positive converter remain.

4.2 ARDUINO PROGRAM FOR CYCLOCONVERTER:

#define half A0#define quarter A1#define input wave A2#define T1 3#define T2 4#define T3 5#define T4 6Int prev_v = 0;Int next_v = 0;Void setup ( ) { Pin Mode (A0, INPUT); Pin Mode (A1, INPUT); Pin Mode (3, OUTPUT); Pin Mode (4, OUTPUT); Pin Mode (5, OUTPUT); Pin Mode (6, OUTPUT); Serial. begin (9600); }Void loop ( ) { prev_v = Analog Read (input wave); Delay (1); next_v = analog Read (input wave); If (prev_v == 0 and next_v > 0)

{ If (half <= 1040 and half >=1010)

{ Digital Write (T1, HIGH); Delay (7); Digital Write (T1, LOW); Delay (3); Digital Write (T3, HIGH); Delay (7); Digital Write (T3, LOW) F/2 pulses

Delay (3); Delay (3);

Digital Write (T4, HIGH); Delay (3);

Delay (7);

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Digital Write (T4, LOW); Delay (3); Digital Write (T2, HIGH); Delay (7); Digital Write (T2, LOW); } } prev_v = analog Read (input wave); Delay (1); next_v = analog Read (input wave); If (prev_v == 0 and next_v > 0) { If (quarter <=1040 and quarter >= 1010) { Digital Write (T1, HIGH);

Delay (7); Digital Write (T1, LOW); Delay (3); Digital Write (T3, HIGH); Delay (7); Digital Write (T3, LOW); Delay (3); Digital Write (T1, HIGH); Delay (7); Digital Write (T1, LOW); Delay (3); Digital Write (T3, HIGH); Delay (7); Digital Write (T3, LOW); F/4

Delay (3); pulses Digital Write (T4, HIGH); Delay (7); Digital Write (T4, LOW); Delay (3); Digital Write (T2, HIGH);

Delay (7); Digital Write (T2, LOW); Delay (3); Digital Write (T4, HIGH); Delay (7); Digital Write (T4, LOW); Digital Write (T2, HIGH); Delay (7); Digital Write (T2, LOW); } } }

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4.3 PRACTICAL CIRCUIT:-

Fig: 4.2 practical kit of design and implementation of cycloconverter using micro controller

4.4 SNAPSHOTS OF CIRCUIT:

4.4.1 Thyristor:

In this, we are using two pairs of thyristors as shown in figure below. The

thyristors start conducting and triggering is given from Arduino board in the form of

program with a delay of 10 milli-seconds for output pulses

Fig: 4.3 Thyristors kit

4.4.2 Centre Tapped Transformer:

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Here the centre tapped transformer, is step down the supply voltage 230V to

(9-0-9V). From here the output voltage is supplied for both thyristor kit and Arduino

board.

Fig: 4.4 (9-0-9V) centre tapped transformer

4.4.3 Arduino Board:

The Arduino board is used for triggering the pulses for output pulses of F/2 &

F/4.here we have some basic program which is written in c language. It consisting of

an ATMEGA328 microcontroller. The use of this board for exact output waveforms.

Fig: 4.5 Arduino controller board

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