The top FET Vgs may not be high enough to turn on the FET completely. What is the value of R17?

 

R17 is of 820ohm 2W.

 

I don't know what MCU you are using to drive the BLDC Motor. You will be using PWM (6x) to drive the BLDC Motor using FET drivers. I also assume that you are using Timer Interrupt to change the PWM duty in run time.

Initially when the MCU is started the PWM pins should be configured as input pins and after starting the Timer ISR to assign PWM duty values you have to configure PWM pins as output pins otherwise if the high side and low side Mosfets both turn ON at the same time then Mosfets will blow up.

 

With the component values you have given, simulation shows that max Vgs for the top FETs is only about 4.8V (dependent on FET threshold turn-on voltage).

Edit: Does the software switch off the motor drive in the situation that power is applied to the motor but no rotation has been detected in a certain time interval?

 

With U2 wired as shown, R17/18/19 pull the gate voltage down towards VBB instead of letting it rise to VM+~12V. This is probably why your motor current is limited. The pull down can be prevented by putting a respective series diode between the U2 outputs and R17/18/19 (anode to resistor). Or you could simply omit R17/18/19. Note, however, that with R11=10k the gate charging is very slow, which will lead to FET heating.

 

Hello Alec_t,

Does the software switch off the motor drive in the situation that power is applied to the motor but no rotation has been detected in a certain time interval?

I have given delay and then started motor in my code.

I have tried decreasing the value of R11 . But then the R11 is heating so much.

My operation is from 18V-32V then what could be the value of R11 so that R11 would not heat?

 

Hello Alec_t,



I have given delay and then started motor in my code.

I have tried decreasing the value of R11 . But then the R11 is heating so much.

My operation is from 18V-32V then what could be the value of R11 so that R11 would not heat?

Provide your circuit. I will post the fixed circuit.

 

what could be the value of R11 so that R11 would not heat?

You might have to replace R11/12/13 with active pull-ups if gate charge time and resistor heating are both problematic.