I am trying to build a bldc controller. I have the following schematic enter image description here I should mention that for the gate drivers I used ir2101 ICs. Everything works fine but when I connect the motor (350w hoverboard motor, the VBAT+ is 36 volts) the motors spins but I have to disconnect it because the mosfets get really hot. Without the motor the mosfets don't heat at all.

Any suggestions would be appreciated.

EDIT: the problem was because of low side gates didn't turn off fast enough. If you have the same problem try to put an "anti-paralel diode" on the low side MOSFETS. The diode should be a Schottky one (fast diode).

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    \$\begingroup\$ What current is the motor drawing? \$\endgroup\$ – Phil G Dec 6 '18 at 20:29
  • \$\begingroup\$ 5 up to 9 Amps. \$\endgroup\$ – pantarhei Dec 6 '18 at 20:32
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    \$\begingroup\$ Oh, there's so many possibilities. Do you have heat sinks on the FETs? Are you limiting the duty cycle so that the high-side parts always get gate drive? Are you actually driving the FETs with no motor attached? Have you tried driving three resistors in a Y or delta connection to see what happens? Add your answers to your question, in the form of a narrative of what you've done so far. \$\endgroup\$ – TimWescott Dec 6 '18 at 21:40
  • \$\begingroup\$ Can you check if the gates are getting driven to the right voltage? If the gates are not driven high enough, FETS will dissipate a lot of power \$\endgroup\$ – Pangus Dec 6 '18 at 21:46
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    \$\begingroup\$ Show oscillograms! \$\endgroup\$ – winny Dec 12 '18 at 9:53

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