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My inverter only produces about 8 volt output while the supply is as high as 20vdc, what's wrong with my inverter circuit ?

enter image description here

const int SpwmArry[] = 
 {500,500,750,500,1250,500,2000,500,1250,500,750,500,500}; // Array of SPWM values.
const int SpwmArryValues = 13; //Put length of an Array depends on SpwmArray numbers. 

// Declare the output pins and choose PWM pins only
const int sPWMpin1 = 10;
const int sPWMpin2 = 9;

// enabling bool status of Spwm pins
bool sPWMpin1Status = true;
bool sPWMpin2Status = true;

void setup(){ 
  pinMode(sPWMpin1, OUTPUT);
  pinMode(sPWMpin2, OUTPUT);
}

void loop(){

// Loop for Spwm pin 1
for(int i(0); i != SpwmArryValues; i++)
   {
     if(sPWMpin1Status)
     {
       digitalWrite(sPWMpin1, HIGH);
       delayMicroseconds(SpwmArry[i]);
       sPWMpin1Status = false;
     }
     else
     {
       digitalWrite(sPWMpin1, LOW);
       delayMicroseconds(SpwmArry[i]);
       sPWMpin1Status = true;
     }
   }

// Loop for Spwm pin 2 
for(int i(0); i != SpwmArryValues; i++)
{
   if(sPWMpin2Status)
   {
     digitalWrite(sPWMpin2, HIGH);
     delayMicroseconds(SpwmArry[i]);
     sPWMpin2Status = false;
   }
   else
   {
    digitalWrite(sPWMpin2, LOW);
    delayMicroseconds(SpwmArry[i]);
    sPWMpin2Status = true;
  }
 }
}
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  • 1
    \$\begingroup\$ Your high-side switches are not being driven correctly. It is the DIFFERENCE between gate and source voltage that turns on a MOSFET. Your gate supply is 18V referenced to GND. Since your low-side MOSFETs have source connected to GND this is fine. But your high-side MOSFETs have their source connected to a voltage that changes with voltage across the transformer coils. You need a high-side gate drive circuit. \$\endgroup\$ – DKNguyen Feb 22 at 4:55
  • 1
    \$\begingroup\$ Correct. So that means you lose Vgs (@ RdsOn) on the output as the source drops into conduction mode on each side. Also, the gate drive current is inadequate with slow 10k turn off and poor CTR on opto ICs so you probably also have shoot-thru. Better go look at designs that actually work \$\endgroup\$ – Sunnyskyguy EE75 Feb 22 at 5:43
  • \$\begingroup\$ Use an IR2110 IC to drive your MOSFETs. It can drive both high side and low side switches. \$\endgroup\$ – Niteesh Shanbog Feb 22 at 8:37
  • \$\begingroup\$ Little use in opto-couplers if you're using the same ground everywhere. You could build your own bootstrap-style high side driver with those optocouplers and some effort. \$\endgroup\$ – Unimportant Feb 22 at 8:45
  • \$\begingroup\$ @toor isn't it dangerous to put connection between the high side switch and low side switch? because i think it is the path for the current to flow \$\endgroup\$ – rahul Feb 22 at 10:26

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