Q: How to design the power stage for a BLDC motor driver (MOSFET selection and gate drive)?
Answer
MOSFET selection for BLDC driver: (1) VDS: 2x supply voltage (e.g. 50V for 24V system). (2) Rds_on: <10 mOhm to minimize conduction loss. (3) Qgd (gate-drain charge): <10 nC for fast switching (reduces switching loss). (4) Current rating: continuous = Imotor x 0.707 (RMS) burst = 2x. Gate drive design: use half-bridge driver IC (e.g. IR2110 DRV8301) with 10-15 V gate drive voltage. Gate resistor (Rg): 10-47 Ohm for MOSFET 100-330 Ohm for IGBT. Add Schottky diode (30BQ100) across MOSFET for reverse recovery. Bootstrap circuit for high-side MOSFETs: bootstrap capacitor (0.1-1 uF ceramic) + diode (BAS70). Layout: keep switching loops (DC+ -> MOSFET -> Motor -> GND) as small as possible. Use Kelvin source connection for clean gate drive. Add TVS diodes (30V) across motor terminals for inductive kick protection.
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