Half bridge drive

Thread Starter

chaitanya_kale

Joined Dec 14, 2021
1
Hi,
while searching on internet related to motor drive circuit I've found one intrested circuit in that along with snubber on top and bottom side MOSFET, their is one resistor connected between drain and source of low side mosfet.
could somebody please guide me what is the purpose of Placing external resistors from drain to source of the MOSFETs.
 

RPLaJeunesse

Joined Jul 29, 2018
211
I suspect that for a full bridge such a resistor would provide a path to ground for any leakage current while power is applied but both FETs are off. This keeps the load pulled towards ground for safety. On a half bridge it would provide some minor magnetism in the motor winding that, and I am speculating here, may be required for motor excitation or sensing. FWIW I have never seen a half-bridge motor drive. Normally only used for DC-AC conversion as part of a (high frequency) switching power supply.
 
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