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Pure sinewave SPWM inverter

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WHen I set the voltage from the power supply using the pot to about 14V or 15V and connect it to the dc-dc converter the voltage drops to about 12.5V What could be the problem?

It used to occur when the transformer was connected when I was testing on the breadboard but now it even occurs when I take out the transformer on the PCB and still drops when the transformer is in......Also, the IR2110 that I am gonna remove from the circuit gets hot and the transformer from the power supply gets heats up as well..... All that is in the dc-dc converter are caps, an inductor, resistors, 5V regulator, diodes (1N4937, 1N4933 and UF4007 all fast recovery diodes) , the SG3525, MOSFETs

Please help!!!!!

I just did some tests and I took out the IR2110 and I get the 15V well a little bit more than like about 15.5V but I assume its due to me having various caps in the circuit.....really dont know why the IR2110 is heating up but am just as you said take it out and bridge the output of the SG3525 to where the ouput of the IR2110 was....
 
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ALERTLINKS said:
IR2110 is damaged.
Click to expand...



When I placed in transformer in the circuit the voltage drops from 15 to 13.3V. Also, what voltage values should I be getting from the SG3525????


I am getting 0.61V from output A and 0.52V from output B. What could be wrong?

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The transformer is definitely the reason why the voltage is dropping because when I take it out I get 6V from each output of the SG3525 and I get the requisite square wave on the oscilloscope and when the transformer is in I get 0.5V and 0.6V and the 15V from power supply drops to about 13V....
 
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SG3525 is connected to gates of FETs which drive transformer. If FETs are OK, then it should not overload the IC.
 

--BawA-- said:
Check the output waveform of sg3525 on oscilloscope...(pin11 and pin14)
Click to expand...

For the Inverter section can I use fast recovery diodes or general purpose diodes can be used since in this stage low frequency is being employed. Also for the boot strap capacitor can I use a 47uF @ 35V electrolytic instead of 22uF?

I strongly believe the ferrite core is the problem in my dc-dc converter. I will have to get another core but for nw I am using the 12V with the inverter.....
 

Fast recovery diodes are better because frequency is near 20KHz. 50Hz is only modulated on it . 47uF capacitor is OK.
 
ALERTLINKS,
The inverter is working with 12Vd and I get 12VAC and when I vary the input voltage the output AC on the multimeter changes and I removed the filters so I get a square wave at the output. So I jsut need now to sort out the dc-dc converter.

Now, I get Vgs= 2.15Vdc for high-side and Vgs=4.95Vdc for low-side..

Question: Do I have to use a non-polarized cap? or can I use an electrolytic cap to do output filtering ?
 
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I get a square wave at the output
Click to expand...
If SPWM is used, without LC-filter, output should be 20KHz pulse train modulated with 50Hz AC . It should deliver full current even with 12V supply. Use a car-12V bulb as load and see if it lights bright, FETs don't heat-up too much and there is no DC offset on either side.
I get Vgs= 2.15Vdc for high-side and Vgs=4.95Vdc for low-side..
Click to expand...
Note that if a 12V pulse train of 50% duty cycle is observed with muti-meter, it will show averaged voltage i.e. near 6V. Peak voltage can be observed with an oscilloscope after calibration.
Do I have to use a non-polarized cap?
Click to expand...
As output is AC, non-polar capacitor is required.
 

hello ALTERLINks,
Your discussion about above noted thread is very useful,hw r u?.plz send some useful circuit along bit simulation for conversion of 48/96 volts dc to 12 volt dc @20 A alongwith cell no..Regards
 

ALERTLINKS said:
If SPWM is used, without LC-filter, output should be 20KHz pulse train modulated with 50Hz AC . It should deliver full current even with 12V supply. Use a car-12V bulb as load and see if it lights bright, FETs don't heat-up too much and there is no DC offset on either side.

Note that if a 12V pulse train of 50% duty cycle is observed with muti-meter, it will show averaged voltage i.e. near 6V. Peak voltage can be observed with an oscilloscope after calibration.

As output is AC, non-polar capacitor is required.
Click to expand...


I got an inductor from a ups but it is mounted on something with 4 pins i.e. 4 wires from inductor connected to it. However, I am not sure how to connect it and I know its an inductor because I use a 5Vdc supply connected it Line and gnd to 2 pins and used a multimeter at the other 2 pins and got out the 5V. How do I connect it to h-bridge and load + capacitor??

Also, do can you give me a schematic with a schmitt trigger to convert a 110 V-AC sinewave to square wave which will then go to MCU to measure its period?
 

I think it is mains-line filter, not suitable for high frequency.
 

ALERTLINKS said:
I think it is mains-line filter, not suitable for high frequency.
Click to expand...

I am using it for the SPWM inverter section in which it should be in series with the load and the load in parallel with the cap.

with the LC filter I still get a square wave. Do I need a min load to see the pure sinewave on the oscilloscope????
 

have you calculated the cutoff frequency of the filter and impedence offered by the inductance at fundamental frequency?
Kryptone said:
with the LC filter I still get a square wave. Do I need a min load to see the pure sinewave on the oscilloscope????
Click to expand...
if you are using asynchronous scheme for SPWM generation , then you have to use some load at the output to see the sine wave.
 

How do I determine the value of the inductor since I do not have an inductance meter?????
 

--BawA-- said:
have you calculated the cutoff frequency of the filter and impedence offered by the inductance at fundamental frequency?

if you are using asynchronous scheme for SPWM generation , then you have to use some load at the output to see the sine wave.
Click to expand...

How do I calculate the impedance of the inductor. could this be a factor why in my dc-dc converter the ferrite transformer was pulling down the voltage of the supply????

the core I am using is from jameco electronics:
https://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_2160681_-1

20 and 22 gauge wires
 

--BawA-- said:
https://www.66pacific.com/calculators/toroid_calc.aspx
Click to expand...

how do I boost the current of the spwm inverter section?
I require 110VAC, 50/60 Hz and about 10-15A

Also, why is the use of high dc voltage inverter preferred over the low dc voltage?

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how do I boost the current of the spwm inverter section?
I require 110VAC, 50/60 Hz and about 10-15A

Also, why is the use of high dc voltage inverter preferred over the low dc voltage?
 
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Kryptone said:
how do I boost the current of the spwm inverter section?
I require 110VAC, 50/60 Hz and about 10-15A

Also, why is the use of high dc voltage inverter preferred over the low dc voltage?

- - - Updated - - -

how do I boost the current of the spwm inverter section?
I require 110VAC, 50/60 Hz and about 10-15A

Also, why is the use of high dc voltage inverter preferred over the low dc voltage?
Click to expand...

can't I using power transistors in parallel to boost the current at the output? If so how would I connect them at the output of inverter or would this have be done at the input supply to the dc-dc converter?
 

BaWa or ALERTLINKS,


I have connected the dc-dc converter of 181 Vdc to the inverter, the noise from the transformer has stopped and there is no flickering and I get an ac output but it is low like about 20 V-AC and a 20W bulb connected at the output with 14.9V input and about 12 V-AC with 12V input with no load I get about 22 V-AC. What could be the problem????

Please help!!!!!!!

I am wondering if the impedance of the inductor could be the problem? I dont know the value of the inductor I got it from a UPS board and it has 4 pins so i just used 2 diagonal pins
 
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