Happy Friday, everyone.

For brushless DC (BLDC) motors—whether in robotic joints or liquid-cooling pumps for servers—control is often separated into several control-loop layers: a torque (or current) loop, a speed loop, a position loop, and the overarching motion-control loop. The control loops further up the line supply input references to the ones further down the line, and ultimately each control loop depends on the one before and after it to maintain smooth, balanced, and efficient motion.

For the last month, Chuck Lewin, CEO of Performance Motion Devices, has been breaking down these functions in his series on BLDC motor control. His latest article focuses on the control loop closest to the power switches that physically drive the motor's windings: the current-control loop. For the power switches themselves, a number of companies have been pushing GaN—hard. EPC recently introduced a new evaluation board for GaN-based motor drives, based on its Gen-7 eGaN.

-James Morra, Senior Editor