Issue with controlling sensored BLDC motor

RenesasT said:

Hello dknguyen,

Pull down all 1,2,3,4,5,6 means they all will turn ON. The IC which I used is ULN2003 which is negative buffer IC.

Suppose I wanted to turn Mosfet 1 i.e Q1 ON. Then I should have send logic 0 i.e 0V from controller.

This is why I said, Shall I put pin 1,3,5 as pulled high. So that initially the MOSFETs will be in off state.

Please suggest on this first point.

Now second point is, If power is turned ON, then powering up of MCU and power goes to MOSFETS is different.

My point is, if power on of MCU and the power to the MOSFET is same instance or different.

If that is at the same instance, then I will give logic signals from controller during power ON. Then there is no need to pull up the things.

Click to expand...

My mistake. I mistook U2 for a non-inverting open collector buffer, but it appears to be an inverting open collector buffer. In that case, try the pull-ups resistors on U2 inputs. It *might* fix the problem, but it might not. It depends on whether U2 powers up fast enough to beat the MOSFET gate capacitances charging up.

Hello Jpanhalt,

Let me clarify you that, micro controller is generating PWM signals and also have control on timings.

As already told you. It is blasting randomly during power ON sometimes only. Suppose at first time it does not get blast, then if you put it turn ON for more than 10 hours then also it is not getting damaged.

Again while testing those issue. What I got to know that,

I have main switch for power and the dynamometer has its power switch.

main switch on- gives directly the set voltage.
main switch off- gives directly the 0V.

dynamo meter switch on- voltage is increasing and reached to set voltage after 3 sec.
dynamo meter switch off- voltage is decreasing and reached to 0V after 3 sec.

If I am using main switch then blast happens randomly.
If I am using dynamo meter switch then blast happens all the time at start.

Hope you have understood what I said.

Hello dknguyen,

Thats what I wanted to do it today. I will pull up all the i/p pins of U2 i.e ULN2003. I will do this today and will update you.

Please find the below information what I had seen while testing,

I have main switch for power and the dynamometer has its power switch.

main switch on- gives directly the set voltage.
main switch off- gives directly the 0V.

dynamo meter switch on- voltage is increasing and reached to set voltage after 3 sec.
dynamo meter switch off- voltage is decreasing and reached to 0V after 3 sec.

If I am using main switch then blast happens randomly.
If I am using dynamo meter switch then blast happens all the time at start.

Hope you have understood what I said.

delete

I need more time to look at ULN2003, which I don't have right now.

RenesasT said:

Hello dknguyen,

Thats what I wanted to do it today. I will pull up all the i/p pins of U2 i.e ULN2003. I will do this today and will update you.

Please find the below information what I had seen while testing,

I have main switch for power and the dynamometer has its power switch.

main switch on- gives directly the set voltage.
main switch off- gives directly the 0V.

dynamo meter switch on- voltage is increasing and reached to set voltage after 3 sec.
dynamo meter switch off- voltage is decreasing and reached to 0V after 3 sec.

If I am using main switch then blast happens randomly.
If I am using dynamo meter switch then blast happens all the time at start.

Hope you have understood what I said.

Click to expand...

I do not really understand.