Hello. I am trying to build an electronic speed controller for a Brushless DC motor but I have a few questions.
I am going to attach a few pictures of circuits. Really, I just want to know if there is anything wrong with my circuit. While testing, I built the circuit without attaching a microcontroller to it yet, and just manually toggled the HIN and LIN pins of the driver chip. Now I thought that when the HIN and LIN of the driver chip (irs2011 recommended circuit attached below) were connected to LOW, 0 V, that both of the transistors would be off and the connection to the load or motor wire lead would be floating. Now the circuit operates normally when 5V is applied to HIN or LIN, the proper transistors cut on and the voltage is 11.1V and 0 V respectively. But when both LIN and HIN are 0V, it is still 11.1V. Am I correct at assuming that it should float? the datasheet doesn't say much at all.
I also keep burning these driver chips out for some reason. I've done replaced them several times. Can't figure out what I am doing wrong.
So what I think should happen is the phase A subcircuit's high transistor should turn on by HIN getting 5V, and phase B subcircuit's low transistor turning on by it's driver LIN getting 5V and the third driver, both LIN and HIN should be 0V. This would pull phase A high to 11.1 V, phase B low to 0V, and leave phase C floating so that current will flow from phase A through the motor exit into phase B and return to ground.
Now later I will create a circuit that will monitor the floating phase for zero crossings to determine when to switch to the next sequence in the drive pattern, but I am just trying to get this working right first and I don't think it is working correctly.
One more question, in my circuit I saw on someone else's they used snubbers across the low transistors. I didn't in my circuit even though it is on the schematic, but how do you determine the values? or are they even needed? Also I have a 1000uF and two 0.1uF caps across the transistors. I have seen this done in other circuits. I know there should be some capacitance but does it need to be across each set of transistors, or is it ok like I have it in my circuit?
Also, ignore the Current Sense circuit. I haven't connected or played around with it yet.
I am going to attach a few pictures of circuits. Really, I just want to know if there is anything wrong with my circuit. While testing, I built the circuit without attaching a microcontroller to it yet, and just manually toggled the HIN and LIN pins of the driver chip. Now I thought that when the HIN and LIN of the driver chip (irs2011 recommended circuit attached below) were connected to LOW, 0 V, that both of the transistors would be off and the connection to the load or motor wire lead would be floating. Now the circuit operates normally when 5V is applied to HIN or LIN, the proper transistors cut on and the voltage is 11.1V and 0 V respectively. But when both LIN and HIN are 0V, it is still 11.1V. Am I correct at assuming that it should float? the datasheet doesn't say much at all.
I also keep burning these driver chips out for some reason. I've done replaced them several times. Can't figure out what I am doing wrong.
So what I think should happen is the phase A subcircuit's high transistor should turn on by HIN getting 5V, and phase B subcircuit's low transistor turning on by it's driver LIN getting 5V and the third driver, both LIN and HIN should be 0V. This would pull phase A high to 11.1 V, phase B low to 0V, and leave phase C floating so that current will flow from phase A through the motor exit into phase B and return to ground.
Now later I will create a circuit that will monitor the floating phase for zero crossings to determine when to switch to the next sequence in the drive pattern, but I am just trying to get this working right first and I don't think it is working correctly.
One more question, in my circuit I saw on someone else's they used snubbers across the low transistors. I didn't in my circuit even though it is on the schematic, but how do you determine the values? or are they even needed? Also I have a 1000uF and two 0.1uF caps across the transistors. I have seen this done in other circuits. I know there should be some capacitance but does it need to be across each set of transistors, or is it ok like I have it in my circuit?
Also, ignore the Current Sense circuit. I haven't connected or played around with it yet.
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