Hi,
I completed an Electrical Eng degree a couple years ago, during I took power electronics. However, I have never been big on electronics, more the power side of things.
I am currently building a BLDC controller which I may eventually just use an arduino for, but for the mean time I'm using a raspberry pi zero. But this is just background.
I'm happy with my code to interface with the hall sensors, however I'm struggling with the inverter. I first tried using three single H-bridges with a common neutral, but I don't think the control circuitry liked it. So I'm having to build my own inverter.
Using the IR2304 mosfet driver (I'm using IRF3205 NMOS). I built the attached circuit and connected it all up and it all seemed to work, however, I noticed that for the totem poles, instead of being 'high, low, off' for instance, it was always 'high, low, high'. I.e. there were always two ON, rather than the unused poles switches being OFF, the upper switch was always ON. (there is a chance it was 'high, low, low' and I misread or am mis-remembering, but you get the point)
I tried everything to get it to turn OFF, with no success. I then conducted an autopsy to see what the problem was.
The first thing I noticed was that the output to the load was Vcc, and not the 12V or 24V I was putting across the DC bus.
I then removed the three IC chip modules from the mosfets and looked at each chip output individually.
I have observed that Vs is ALWAYS equal to Vcc. I am not sure if this is supposed to be the case.
Also, VB is ALWAYS equal to Vcc. "..."
The upper mosfet, driven by HO. Doesn't HO have to be some voltage such as Vcc larger than Vs for the upper mosfet to turn ON? Because wouldn't the above point mean that the upper mosfet is always OFF if they're the same voltage?
The i/o functionality diagram on page 4, is this with reference to the COM pin?
I tested the chips circuits individually just using a multimeter, but needless to say the HO does not match the diagram if it's referenced to COM.
Notes:
I didn't use any resistor on the gate of the MOSFETS, as I have seen 22Ohms used by people. I'm not sure what the effects of this could be.
I used a 12V battery and a boost converter to output 15V to Vcc.
There is probably more observations I could say, but can't think of anything at this point.
Thanks in advance for help!
Cheers
I completed an Electrical Eng degree a couple years ago, during I took power electronics. However, I have never been big on electronics, more the power side of things.
I am currently building a BLDC controller which I may eventually just use an arduino for, but for the mean time I'm using a raspberry pi zero. But this is just background.
I'm happy with my code to interface with the hall sensors, however I'm struggling with the inverter. I first tried using three single H-bridges with a common neutral, but I don't think the control circuitry liked it. So I'm having to build my own inverter.
Using the IR2304 mosfet driver (I'm using IRF3205 NMOS). I built the attached circuit and connected it all up and it all seemed to work, however, I noticed that for the totem poles, instead of being 'high, low, off' for instance, it was always 'high, low, high'. I.e. there were always two ON, rather than the unused poles switches being OFF, the upper switch was always ON. (there is a chance it was 'high, low, low' and I misread or am mis-remembering, but you get the point)
I tried everything to get it to turn OFF, with no success. I then conducted an autopsy to see what the problem was.
The first thing I noticed was that the output to the load was Vcc, and not the 12V or 24V I was putting across the DC bus.
I then removed the three IC chip modules from the mosfets and looked at each chip output individually.
I have observed that Vs is ALWAYS equal to Vcc. I am not sure if this is supposed to be the case.
Also, VB is ALWAYS equal to Vcc. "..."
The upper mosfet, driven by HO. Doesn't HO have to be some voltage such as Vcc larger than Vs for the upper mosfet to turn ON? Because wouldn't the above point mean that the upper mosfet is always OFF if they're the same voltage?
The i/o functionality diagram on page 4, is this with reference to the COM pin?
I tested the chips circuits individually just using a multimeter, but needless to say the HO does not match the diagram if it's referenced to COM.
Notes:
I didn't use any resistor on the gate of the MOSFETS, as I have seen 22Ohms used by people. I'm not sure what the effects of this could be.
I used a 12V battery and a boost converter to output 15V to Vcc.
There is probably more observations I could say, but can't think of anything at this point.
Thanks in advance for help!
Cheers
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