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Spwm using pic 16f877A

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Akshaydpal

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hi,
i am working on pure sine wave inverter using pic 16f877A i have created a basic program for it.

Code: 
unsigned char x[51]={0,16,32,48,63,79,94,109,123,137,150,162,174,186,196,206,215,223,231,237,242,247,250,253,254,255,255,253,251,247,243,237,231,224,215,206,197,186,175,163,150,137,123,109,94,79,64,48,32,16,0};
void main()
{
unsigned char i;
TRISC.F2=0;
TRISC.F1=0;
PWM1_Init(5000);
PWM2_Init(5000);
PWM1_Start();
PWM2_Start();
while(1)
{
for(i=0;i<51;i++)
{
PORTC.F1=0;
PWM1_Set_Duty(x[i]);
}
for(i=0;i<51;i++)
{
PORTC.F2=0;
PWM2_Set_Duty(x[i]);
}

}
}
this is for 10khz switching. during simulation in proteus it is giving some pulses during off time as well . i dont know why it is giving that extra pulses.
i had developed it on breadboard as well in DSO it is giving out similar pulses during off time.
images are attached kindly help me . im a newbi in this area.


<a title="output2.JPG" href="http://obrazki.elektroda.pl/7319165600_1495789490.jpg"><img src="http://obrazki.elektroda.pl/7319165600_1495789490_thumb.jpg" alt="output2.JPG" /></a>



<a title="complete ckt.JPG" href="http://obrazki.elektroda.pl/4297777100_1495789540.jpg"><img src="http://obrazki.elektroda.pl/4297777100_1495789540_thumb.jpg" alt="complete ckt.JPG" /></a>

mosfet driver used is ir2110 and mosfet irf840n

this inverter ckt is not giving output in proteus simulation but i had shown the pwm output from pic and driver but when i tested those without mosfet on bread board pwm from pic was giving unwanted pulses during off time as shown in simulation output . and the driver output got me all confused the low side is boosted to 12 v but high side is approx 5-6 v. low side ias some how similar to pic pwm out put but not the high side it is like all time high .


power supply used is rectified and filtered ac from 220 v supply sepped down to 30 v and rectified with 3 different ckt for 5v , 5v and 12v.

- - - Updated - - -

<a title="TEK00003.PNG" href="http://obrazki.elektroda.pl/2497868300_1495792526.png"><img src="http://obrazki.elektroda.pl/2497868300_1495792526_thumb.jpg" alt="TEK00003.PNG" /></a>



<a title="TEK00005.PNG" href="http://obrazki.elektroda.pl/6105827700_1495792578.png"><img src="http://obrazki.elektroda.pl/6105827700_1495792578_thumb.jpg" alt="TEK00005.PNG" /></a>



pwm output on dso
 
Last edited by a moderator:

Hi,

most probably this is cross talk between scope channels. Maybe caused by a badly chosen GND for the scope probes.

Klaus
 


this my ir2110 ckt am i doing something wrong im not getting proper out put please sugeest some changes needed

- - - Updated - - -

i made a little modification in above ckt




low side output


high side output



plese tell me what am i doing wrong not getting high side output
 

Hi,

To get high side output:
You need to connect VS with a resistor to GND. Start with 500 ohms then you may use lower ohmic resistors.

Klaus
 
Thanks KlausST

do you mean like this



i hve modified the image according to mu understanding.

also high side out put to be seen accross HO pin and COM(GND) ?? Is this correct ?

- - - Updated - - -



thanks klausST i got the out put . now im moving towards power stage . i will return with power stage testing problems .

ur a great teacher thanks alot.
 

hi,

while simulating this circuit in proteus it gives some error im unable to understand how to rectify this the circuit and ther error is attached. plese tell me what is the error and how to rectify this the input to the inverter h bridge is 20v dc ir2110 vcc is 15v dc



error

 

hello
please change bootstrap diode with uf4007 or equivalent. bootstrap capacitor is also too large for high frequency usually small value is recommended try 2.2uf.
 
HI abc_de

i am not able to find uf4007 in proteus.Can u plese suggest some replacement for it also changed the bootstrap capacitor to 2.2uf but still same issue.



- - - Updated - - -

hi

i got uf4004 n im getting result for few min but then it gave this error and stopped
 

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