User Manual

Sinusoidal Commutation
Advanced Digital Motor Controller User Manual 115
Important Warning
Do not select an amperage value that is above the maximum nominal value pub-
lished in the motor’s datasheet.
Important Warning
Calibration data is specific to a motor+sensor set. Changing the motor and/or sen-
sor requires recalibration.
Sensor Min/Max Range
Analog sensors like Sin/Cos and Resolvers have voltage output swings that can vary from
one sensor to another. During Automatic Setup, the motor is forced into rotation and
the min and max voltages for each sensor output signal is captured over a full turn of the
sensor. These values then determine offsets and multiplier that are saved in calibration
memory and subsequently used to scale the signals as necessary to produce a correct
angle measurement.
The min/max range calibration is a one time operation for a given sensor.
Zero Reference Search for Absolute Sensors
All absolute sensors (Sin/Cos, Resolver, SSI) cannot be trusted to be mounted so that
their 0 degree reference position exactly matches this of the motor’s windings. During
Zero Reference search, the motor is driven over known angular positions. The sensor mea-
surement is compared with the expected rotor position and an Angle Adjustment vale is
computed and stored in configuration memory.
Important Notice
All angles values entered or displayed by the controller are in 0-511 value where 0 =
0 degrees or radians, and 511 is 360o or 2r radians.
Zero Reference Search for Incremental Encoders
Incremental Encoders do not output an absolute position value. The Zero Reference
search is therefore performed every time the controller is powered on. See also “Incre-
mental Encoder-Only” on page 103
Hall Sensors Position Mapping
Hall sensors are often not precisely located at the 0, 60, 120, 180, ... positions. While
some imprecision has little effect in trapezoidal mode, misalignment of even a few de-
grees will have disruptive effect when operating in sinusoidal mode. When used with Hall
sensors, the automatic setup procedure captures and maps the angle at which each of the
six hall transitions occurs within an electrical turn, regardless of their wiring order.
Linearity Correction Map
Sensor are not alway totally linear. This causes the sensed angle to be measured with
periodic errors along the sensor travel. During the automatic setup process, the controller
maps the values read from the sensor for every mechanical degree over a full turn. It then
build a correction table which is applied in real-time as the motor spins.