Thermal performance evaluation for a microelectronics motor control system incorporating dynamic heat sources

A detailed transient thermal analysis for single-chip silicon Integrated Motor Control System with multiple dynamic heat sources with various applications in electronics packaging is performed using numerical simulations. The challenge resides in the transient thermal interaction between various dynamic heat sources, operating at high power surges for short time frames (in one case, the motor dissipates 120 W for 2.56 ms). Several operating steps are simulated, and the transient thermal behavior for each source is identified during the process. The peak motor temperature is reached during the intermediate step of the dynamic powering process. The low side motor reaches a peak temperature of ∼88.4°C after 2.1 s, while the final temperature reached by the motor after one full dynamic cycle (2.565 s) is ∼69.7°C. The DC current limit study indicates that the current over 1A will exceed the thermal budget. The case with a current limit of 0.5A reaches 135C after 4 cycles, below the 150°C limit. The upper power limit is ∼18 W (I∼0.5625) to keep the DC motor peak temperature below 150°C. Additional numerical studies for an equivalent system were also performed with only the high side driver actively dissipating 120 W for 2.56 μs. The peak temperature reached by the system during the first cycle (∼2.56 μs) is ∼65°C. An analytical study was performed to predict and evaluate the steady state (final) temperature after a large number of dynamic powering cycles, based on heating/cooling behavior and superposition principle.