Phase Initialization

Phase Initialization

When the system is first powered on, the controller must determine the initial commutation phase. NI motion controllers support several methods of phase initialization, including Hall effect sensors, shake and wake, and direct set.

Hall Effect Sensors

The controller can use Hall effect sensors to estimate the commutation phase based on the state of the sensors. After a Hall effect state transition occurs, the controller recalculates the phase angle based on the transition location. To obtain maximum torque at the beginning of the move, perform a move that is 1/6th of the magnetic cycle after system initialization. Refer to the hardware documentation for Hall effect sensor types and connection schemes.

Shake and Wake

"Shake and wake" is an initialization method where the motion controller outputs a specified voltage for a specified duration. This drives the system to the zero-degree phase position and allows you to establish the position as a baseline for all other phase positions.

During this process, the motor moves to the zero-degree position with high torque. Ensure the system is away from any limits before performing shake and wake initialization.

If the system has load or is moving against gravity, increase the shake and wake voltage. If there is significant jitter as the axis approaches zero, increase the duration.

Direct Set

Direct set is an initialization method where the controller sets the current position as the specified phase angle. This initialization method is recommended only for a custom system with known initial phase angle.

Whenever the axis is enabled, the controller must perform the phase initialization procedure to determine the phase.