Six-Step Commutation

Six-step commutation, also known as trapezoidal control, is a fundamental technique used to drive Brushless DC (BLDC) motors by sequentially energizing their stator phases. The process involves dividing a single electrical revolution into six equal 60-degree segments, with a unique switching state assigned to each interval. During any specific step, two of the three motor phases are energized—one connected to the positive DC bus and the other to the negative—while the third phase remains floating. To maintain synchronization, the controller typically uses Hall-effect sensors to detect the rotor's magnetic position and trigger the transition to the next commutation state. This sequence creates a rotating magnetic field in the stator that pulls the permanent magnet rotor behind it, though the discrete switching inherently produces more torque ripple than sinusoidal methods.