I'm designing a motor controller for 3-phase BLDC motor. I'm using following components,
- Gate driver - IR2184
- MOSFET - IRF540N
The complete circuitry and output waveforms are available here.
I have developed circuitry on the PCB as you can see in figure 1 in the link given.
With resistive load I have perfect BLDC commutation waveforms that I can observe and it is clear from figure 3 in the link.
But when I use same circuitry for the BLDC hub motor with following specs,
- Power 250 W
- Rated voltage 36 V
- Max current limit 10 A
- Motor load - No load, motor is running free on a mounting
As from figure 4 it is clear that circuit is not behaving as expected with an inductive load as motor coils do not have any other path to release magnetic energy but by body diode of MOSFETs. Snubber seems a solution to this problem. I have googled for 3-phase inverter snubber design but I could not find material specifically targeting 3-phase inverter snubber design.
Could I get some direction in the design of snubber for 3-phase inverter?