Q: What thermal management strategies are needed for motor drive electronics?
Answer
Motor driver thermal design: (1) Calculate power dissipation: P_loss = P_conduction + P_switching. Conduction loss = I_RMS^2 x Rds_on x 2 (half-bridge). Switching loss = 0.5 x V x I x (tr + tf) x fsw. (2) Thermal resistance path: junction -> case (Rth_jc) -> heatsink (Rth_cs) -> ambient (Rth_sa). Calculate heatsink requirement: Rth_sa = (Tj_max – Ta) / P_loss – Rth_jc – Rth_cs. (3) Use thermal interface material (TIM) between MOSFET/IC and heatsink (0.5-1.0 C/W). (4) Forced air: 10 CFM per 10W typical; fans sized by CFM vs pressure curve. (5) MOSFETs in parallel: balance Rds_on to distribute current evenly. (6) Thermal simulation: use manufacturer thermal models (ST TI Infineon provide SPICE and thermal models). (7) Thermal shutdown: set Tj_max = 150C for MOSFETs. (8) Current derating: reduce current above 80C ambient. Mount driver PCB vertically for natural convection.
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