hi I have been working since 2 years in designing a pure sine wave inverter with the following specifications:
h-bridge with 2 ir2110 and step up iron core transformer to 220v,with 19350hz sampling frequency.
I used the Microntroller pic18f2331 using assembly language.
Every thing was okay, I first began with 12VDc bus,the output signal was perfect in resistive load,and inductive load with high power factor like fan,but with low power factor like drills booster pumps, the pure sine wave signal is distorted a little, but this was also okay,I didn't face any problem neither at 12VDC nor at 24VDC, I always work with RCD suppressing snubber, and high input capacitance of about 24000uF for 24VDC, I tried a maximum load of 1200W for several hours, the mosfet's heat(irfp064N) was acceptable and no problem, I always use a 10 ohms resistor for the gate to avoid switching losses.the output is regulated very well with constant value 227.6 volts always.
note that i use filtering at the output by a capacitor of 4.7uF for 24VDC(1200VA ie 900watt)
the problem is:when using a DC bus of 48VDC, designing an iron core transformer of 28vac-225vac, the Mosfets irfp4710 were blown off when i put a transformer, but with different resistive loads, every thing was okay, good output signal.
I tried several issues to solve the problem, like:
1)stabilizing the secondary side of IR2110 by putting capacitor of high value to avoid voltage drop which may cause output garbage
2)cancelling snubbers.
3)trying anather transformer.
4)increasing dead time.
the mosfets exploded again and again,
I tried to use a smoothing inductor (which causes voltage drop and low efficienty inverter), the inverter works but with low voltage.
I don't know what to do but I think of lowering the sampling frequency inside my program!!!
if any one have an idea what to do, please help
N.B: I don't use ferrite because it is not available in the market in Lebanon, I prefere to use dc dc boost converter go up to 340, and then use LC filter.
h-bridge with 2 ir2110 and step up iron core transformer to 220v,with 19350hz sampling frequency.
I used the Microntroller pic18f2331 using assembly language.
Every thing was okay, I first began with 12VDc bus,the output signal was perfect in resistive load,and inductive load with high power factor like fan,but with low power factor like drills booster pumps, the pure sine wave signal is distorted a little, but this was also okay,I didn't face any problem neither at 12VDC nor at 24VDC, I always work with RCD suppressing snubber, and high input capacitance of about 24000uF for 24VDC, I tried a maximum load of 1200W for several hours, the mosfet's heat(irfp064N) was acceptable and no problem, I always use a 10 ohms resistor for the gate to avoid switching losses.the output is regulated very well with constant value 227.6 volts always.
note that i use filtering at the output by a capacitor of 4.7uF for 24VDC(1200VA ie 900watt)
the problem is:when using a DC bus of 48VDC, designing an iron core transformer of 28vac-225vac, the Mosfets irfp4710 were blown off when i put a transformer, but with different resistive loads, every thing was okay, good output signal.
I tried several issues to solve the problem, like:
1)stabilizing the secondary side of IR2110 by putting capacitor of high value to avoid voltage drop which may cause output garbage
2)cancelling snubbers.
3)trying anather transformer.
4)increasing dead time.
the mosfets exploded again and again,
I tried to use a smoothing inductor (which causes voltage drop and low efficienty inverter), the inverter works but with low voltage.
I don't know what to do but I think of lowering the sampling frequency inside my program!!!
if any one have an idea what to do, please help
N.B: I don't use ferrite because it is not available in the market in Lebanon, I prefere to use dc dc boost converter go up to 340, and then use LC filter.