User Manual

Table Of Contents

Brushless Motor Connections and Operation

112 Advanced Digital Motor Controller User Manual V2.0, July 8, 2019

Reference Search Power

During the automatic sensor setup phase, the controller will drive the motor coils with a

slow-changing three phase current, creating a rotating magnetic ﬁeld inside the motor. The

rotor’s magnets are attracted to the ﬁeld, causing the rotor to follow turn. For best accu-

racy the rotor is driven for a full turn in the forward direction, and another full turn in the

reverse direction.

For the reference search to work, the current that is injected into the motor must be

strong enough to pull the rotor in perfect alignment. The motor must not be loaded during

this sequence. For best results, the current should be set to half of the motor’s nominal

amps rating.

Enter the value in Amps s in the “Reference Seek Power” conﬁguration menu in the Rob-

orun PC utility.

Or by sending the conﬁguration command:

^SREF channel amps (in amps * 10)

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.