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I fixed the overshoot problem by adding cap on Drain Source but my problem still exits.
always the MOSFET or IGBT gets short circuit at start of the control, not during the control. why?
the last time I have tested (DC link volatge was 150V) the circuit worked fine but as soon as I turned the...
do you mean your igbt gets short circuit even without giving any pulse?
In this case, put a 1k resistor on Gate emitter across each IGBT. maybe your problem would fix.
I have used IR2111 as gate driver and it gives 650ns deadtime. isn't that enough?
seller gave me this datasheet...
I have used 7n40 MOSFET transistor instead of Fg25n120 IGBT transistor and the output was just fine.
DC link voltage was 200*sqrt(2), the maximum VDS was 350V and output was 170 V RMS. But when I use Fg25n120 again, IGBTs got short circuit in one leg.
So does my IGBT has a problem? under what...
I tested inverter with both open loop and closed loop control.
I attached the result.
the DC Link voltage is 105 Volt.
this is the VCE with open loop control.
this is the VCE with closed-loop control.
this is ADC input for closed loop control.
Oh, I forgot to say that my inductor gets warm even at no load. is it ok?
inductor model is t184-26 iron powder and the switching frequency is 15Khz.
on more thing, I didn't use the current sensor. wouldn't that be a problem?
the bootstrap diode is 1n4937.
all gate resistors are 15 ohms
I corrected the schematic in post #5.
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I corrected the schematic at post #5.
I use unipolar switching pattern.
I use IR2111 as gate drive and its deadtime is 650ns.
sorry, I missed changing some values.
here is the schematic.
I should say that I have no problem with open loop control with Vin=200 V (I didn't test higher voltages). but the IGBTs get short with closed loop control. for input 130 Volt, I have no problem and the output is just fine.
Hello,
I am designing a 390 DC to 220 AC 1KW single phase inverter.
I am using a proportional resonance control with LPC1768 Microcontroller.
in low output voltage, I get a pure sine wave and I have no problem, but when the input increases above 150 Volts, my IGBT get short circuit.
these are...
I soldered two 1uf film cap as close as possible to fets across Vin.
There are two 4700uf bulk caps and two 220 nf cermic caps on Vin.
its 600uH t184-26 core.
I have efficiency problem. Has it something to do with spike?
This is Vds when the input power is about 400 Watt.
This is Vds when the input power is about 600 Watt.
This is Vds when the input power is about 800 Watt.
There are about 5 Volts across the Fet on conducting duration. and it increases by time.
The Fets are irfp260n in this test. is it...
Hi,
I finally somewhat resolved the spike issue.
by changing the Gate-Source resistor, gate resistor and snubber values.
But now I have efficiency probelm.
the efficiency is about 60 percent.
for example, when the output power is 128 watt, the input power is 204 watt.
I measured the Vds and...
The blue trace is ICs supply voltage in both images.
the left image, purple and yellow traces are Vgs.
the right image, purple and yellow traces are Vds.
I have soldered 2uf film cap on the bottom layer right by the FETs, but it didn't work.
these are FETs. (marked as yellow)
There are electrolytic and ceramic caps right by each three ICs, so I don't think it is a decoupling problem.
these are Vgs and Vds and ICs supply voltage.
How can i be sure that ICs supply voltage effects on MOSFETs or vice versa?
what caps do you mean?
Do you mean input caps for example c3 and c4 in this circuit?
and how close should they be?
- - - Updated - - -
If it is a timing issue, why Vgs and Vds are ok at no load?
It is the SG3525 and HCPL3120 supply voltage. the supply voltage has no spike at no load.
It...
HI,
I redesign the PCB layout.
this is the new PCB layout.
these are the Gate-Source and Drain-source voltage at no load.
these are the Gate-Source and Drain-source voltage at 75 watts.
but the problem has not been resolved.
this is the IC power supply.
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