MOSFET AND IGBT fail in pwm speed control for 260VDC 2200W universal motor

praondevou

Joined Jul 9, 2011
2,942
now i connect the ir2110 and used a 4ohm 2w gate resistance but when working @ frequency 144 hz no problem and when working on 2300hz or 14400 hz the ic get hot
i use this conf. but @ 9 i connect 12v +


edit: i did use only one mosfet the high one only it run the small motor but the ic is getting hot
I don't understand how you charge the bootstrap capacitor if u only use the high side mosfet...:confused: Through the motor? If u only have one mosfet, then use the low side. Connect HIN to GND.

Try to use a bigger value for the gate resistance.

What did you connect at Vb and Vcc? Is the circuit u posted exactly what u built except for the low side mosfet which u said u didn't use?
 

Thread Starter

kandilx

Joined Oct 21, 2011
69
I don't understand how you charge the bootstrap capacitor if u only use the high side mosfet...:confused: Through the motor? If u only have one mosfet, then use the low side. Connect HIN to GND.

Try to use a bigger value for the gate resistance.

What did you connect at Vb and Vcc? Is the circuit u posted exactly what u built except for the low side mosfet which u said u didn't use?
your first part considering the bootstrap i dont understand the problem, bu now i am trying the low side i did already try bigger values of resistance 80 ohm and 600ohm same problem what is new now is that the ic get hot @ all frequencies vb and vcc the same as in the previous pic
 

Thread Starter

kandilx

Joined Oct 21, 2011
69
Ok, then yes as Praondevou said, use the low side. Unless you have a specific reason to use the high side. Do you(have a specific reason)?
i working on it now but should i connect Vs on the 12v+ or what??
edit: i dont have any reason to use high side but i did in the beg connect to the low side but i didnt work i will try again
 

Thread Starter

kandilx

Joined Oct 21, 2011
69
ok now it worked on the small 12v motor at different frequencies with now remarkable problem , next step is the big motor i will be using 14400 Hz (1.44/(10kOhm x 0.01uF)) i will use diode across the motor terminal UF5408 , and a 3.9 Ohm 3w resistance connected in series
and FR607 across the MOSFET source and drain
in some circuits i did see some capacitors across the motor terminals is it necessary and if yes how to determine the size then ?
 

praondevou

Joined Jul 9, 2011
2,942
my other circuit was wrong. COM needs to be connected to gnd

and use the low side driver. VS is the reference for the high side , don't use it. connect SD to gnd too, the have pull-downs but I wouldn't let them open.
 

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strantor

Joined Oct 3, 2010
5,369
ok now it worked on the small 12v motor at different frequencies with now remarkable problem , next step is the big motor i will be using 14400 Hz (1.44/(10kOhm x 0.01uF)) i will use diode across the motor terminal UF5408 , and a 3.9 Ohm 3w resistance connected in series
and FR607 across the MOSFET source and drain
in some circuits i did see some capacitors across the motor terminals is it necessary and if yes how to determine the size then ?
The diode which you place across your motor terminals (freewheeling diode) should be rated at least for whatever current you plan to put through the motor, as the diode will be conducting the full amount of current flowing through the motor when the MOSFET is off. the UF5408 you mentioned is rated @ 3A. If you only plan to run the motor @ 3A then it should be fine, but something tells me you will be drawing a lot more than 3A through the motor, so you should use a bigger diode IMO. If your diode were to fail (open) then your MOSFET would take a nasty beating, as all the current generated by the motor back EMF would be passed through the MOSFET as avalanche energy and cause it to heat up and probably fail.

The other diode (FR607) which you plan to put across source and drain; what is it's purpose?
 

strantor

Joined Oct 3, 2010
5,369
How are you limiting current? If you have no current limiting then you must realize that with the motor at rest, it is almost a direct short, and simply pwm switching it will result in very high amps going through the mosfet. This could cause the mosfet to fail before there is time for the heat to reach the suface of the package where you can feel it. You may save yourself some mosfets by doung your testing with a resistor in series with the motor
 

Thread Starter

kandilx

Joined Oct 21, 2011
69
How are you limiting current? If you have no current limiting then you must realize that with the motor at rest, it is almost a direct short, and simply pwm switching it will result in very high amps going through the mosfet. This could cause the mosfet to fail before there is time for the heat to reach the suface of the package where you can feel it. You may save yourself some mosfets by doung your testing with a resistor in series with the motor
no current limiting i use, i operate @ 260Vdc 10amps so resistance 26 ohm but what its power then? 2200W ?
 

Thread Starter

kandilx

Joined Oct 21, 2011
69
my other circuit was wrong. COM needs to be connected to gnd

and use the low side driver. VS is the reference for the high side , don't use it. connect SD to gnd too, the have pull-downs but I wouldn't let them open.
i really dont see any difference between this one and the previous one as there is only one ground so com is already connected to it and vss too
 
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