230V to 110V ,200W SOLID STATE TRANSFORMER

Transformers are fundamental components of the power distribution system and are
relatively  inexpensive,  highly  reliable,  and  fairly  efficient.  However,  they  possess  some
undesirable properties including sensitivity to harmonics, voltage drop under load, (required)
protection  from  system  disruptions  and  overload,  protection  of  the  system  from  problems
arising  at  or  beyond  the  transformer,  environmental  concerns  regarding  mineral  oil,  and
performance under dc-offset load unbalances. These disadvantages are becoming increasingly
important  as  power  quality  becomes  more  of  a  concern.  With  the  advancement  of  power
electronics  circuits  and  devices,  the  all  solid-state  transformer  becomes  a  viable  option  to
replace the conventional copper and-  iron based transformer for a better power quality. The
solid-state switching technologies allow power conversion between different formats such as
dc/dc, dc/ac, ac/dc, and ac/ac with any desired frequencies.
Moreover in order to reduce the emission of greenhouse gas and replace the limited
energy  sources  like  coal,  oil  or  uranium,  the  number  of  renewable  energy  sources  is
constantly growing. This development results in a rising number of  distributed power plants,
which are principally subject to substantial energy fluctuations. In order to easily connect the
new energy sources to the grid and improve the power quality by harmonic filtering, voltage
sag correction and highly dynamic control of the power flow new power electronic systems  -so  called  Intelligent  Universal  /  Solid-State  Transformers  (SST)  –  are  required.  These
interconnecting  devices  would  enable  full  control  of  magnitude  and  direction  of  real  and
reactive power flow and could replace not controllable, voluminous and heavy line frequency
transformers.  Based on such devices a smart grid comparable to the internet, where a plug
and  play  connection  of  sources  and  loads,  distributed  energy  uploads  and  downloads  and
energy routing for transferring energy from the producer to the consumer, is possible
BLOCK DIAGRAM

CIRCUIT DIAGRAM

BRIDGE RECTIFIER AND BUCK CONVERTER

INVERTER


HARDWARE PICTURE


BULB WITH HIGH BRIGHTNESS IS THE OUTPUT OF BUCK STAGE AND  LESS BRIGHTNESS IS THE OUTPUT OF INVERTER STAGE


PROGRAM

BUCK STAGE
void setup()
{
setPwmFrequency(11, 1);
analogWrite(11,150);
}
void loop()
{
}
void setPwmFrequency(int pin, int divisor) {
byte mode;
if(pin == 5 || pin == 6 || pin == 9 || pin == 10) {
switch(divisor) {
case 1: mode = 0x01; break;
case 8: mode = 0x02; break;
case 64: mode = 0x03; break;
case 256: mode = 0x04; break;
case 1024: mode = 0x05; break;
default: return;
}
if(pin == 5 || pin == 6) {
TCCR0B = TCCR0B & 0b11111000 | mode;
} else 
DESIGN AND IMPLEMENTATION OF A SOLID STATE TRANSFORMER
86
EEE Dept. NSSCE, PALAKKAD
{
TCCR1B = TCCR1B & 0b11111000 | mode;
}
}
else if(pin == 3 || pin == 11) {
switch(divisor) {
case 1: mode = 0x01; break;
case 8: mode = 0x02; break;
case 32: mode = 0x03; break;
case 64: mode = 0x04; break;
case 128: mode = 0x05; break;
case 256: mode = 0x06; break;
case 1024: mode = 0x7; break;
default: return;
}
TCCR2B = TCCR2B & 0b11111000 | mode;
}
}