IR2110 getting hot while connected as half bridge

[sam781]

@KlausST:
Thanks for your suggestion.... Here is my comments -

Why R3, R4 are 1k?
Try 10k or higher.

I'll replace 1k resistor with 10k or 22k.

Then you don´t need that huge 100uF capacitor for bootstrap voltage (although not wrong... You need well chosen electrolytic capacitors for 50kHz)

I used 10uF Tantalum capacitor (C1) for bootstrap voltage.

Picture in post#19:
It seems the transformer is saturating.
timing of scope seems to be 5us/div. If so ... saturation begins after 6us (rapidly increasing current, high power dissipation) .
twice 6 us = 12 us --> try PWM freq with 80kHz or more.

Actually, the waveform picture shared in post#19 is without transformer. Bridge output with and without transformer has been shared below with more clarity -

Without transformer-



With transformer-

With transformer connected with the bridge output, MOSFETs are becoming hot gradually.

- - - Updated - - -

While running the converter, I took the follwoing waveform -

 

[KlausST]

Hi,

If possible to change to 80 kHz PWM, then test it and check heating.

A good debug information is input voltage and input current and output voltage and output current.
With all the info you can calculate power dissipation in your circuit.

A power value gives more objective information than a subjective sense of heat.

Klaus

 

[sam781]

Okay, I'll check with 80kHz PWM.

How can I check current? Shiuld I rely on DMM to get the voltage and currnet? I donot have the specification of the DMM whether it can measure voltage and current beyond above 50Hz line frequency.

 

[KlausST]

Hi,

for first step the no_load input current is a good indicator.

input voltage and input current are DC. A DMM should work.

Klaus

 

[samEEEf]

Thanks KlausST
I've tested with different frequencies. The situation improves with the increase of frequency. So, core saturates at 50kHz. At 80kHz it seems okay. I tried with 100kHz and 120kHz aslo.

But still the waveform is slightly distorted.


It is observed if I connect the transformer. Similar distortion is observed at 120kHz PWM also. What could be the reason of such distortion?

 

[KlausST]

Hi,

Your picture shows the difference voltage of the bridge output pins?

Either the supply voltage is not stable or the drive voltage is not stable.

please check if 12V supply voltage is stable.
In post#21 picture2 there is a capacitor. Here you need a high quality one. A standard electrolytic capacitor is useless.
(i use parallel X7R ceramic capacitors from GND plane - next to drain of every highside MOSFET pin. Value: >= 100nF)
Look for
* low ESR
* high frequency
* ripple current
* peak voltage

mind that inductive and capacitive load will feed back power to this capacitor. You may need a (much) higher voltage rating than the DC supply output voltage. (depending on load and source)

Klaus

 

[samEEEf]

I'm using a sealed lead acid battery as the 12v source. Should the capacitor be non-electrolytic? I knew, Tantalum capacitor is good capacitor having low ERS and other quality characteristics. But it is electrolytic. Tantalum is also costly. Can I use polyester film type capacitor which is widely used in many applications; locally available capacitance is up to 0.63uF.

I doubt whether I will be able to find X7R ceramic capacitors here.

 

[KlausST]

Hi,

i don´t know where "here" is. But X7R capacitors are very common.
These capacitors are only for the the fast switching edges.

Your battery is stable for relatively slow loads (freq < 1kHz), but it can not provide high current pulses in the 100kHz range.
Therefore you need extra bulk capacitors. Fast capacitors. There is no "best" capacitor with a lot of capacity and high frequency capability. Because of that
one can parallel some capacitors of different types.
X7R are meant for the MHz region. Then you need capacitors for the low kHz up to some 100kHz region.
Tanatalum are good. or the above recommended electrolytic.

The polyester film capacitor may replace the X7R capacitors but not the electrolytic ones.

Good luck

Klaus

 

[kripacharya]

I've made the the attached circuit its giving the output but the MOSFET driver is getting hot after powering on. I've checked by changing C1 to 5uF and removing D2 and D3 but same result.

View attachment 111452

I notice that your topology is slightly different from what is published in the IR2110 spec sheet. Namely -- while you have High-Side Source and Low-Side Drain shorted, the app note shows the LOAD should be connected in between :



Just thought to point this out.

 

[sam781]

Thanks a lot kripacharya to show an important thing here

Actually, I was testing the one part of H bridge. Later I made the full bridge. Now, the issue is resolved. I've started working on filter. Thanks a lot everyone for your help to resolve the issue I faced so far...