Delta Tau GEO BRICK LV User Manual

 

 

For the 3-phase hall sensors, the decode must be set to times-6 decode, which derives six counts per 
signal cycle, one for each signal edge.  This requires a variable value of 11 or 15.  The difference between 
these two values is the direction sense – which direction of motion causes the counter to count up.  
Remember that for a feedback sensor, the sensor’s direction sense must match the servo-loop output’s 
direction sense – a positive servo output must cause the counter to count in the positive direction – 
otherwise a dangerous runaway condition will occur when the servo loop is closed. 

The most common use of these hall sensors with a Turbo PMAC2 is to establish an approximate absolute 
position for the phase commutation algorithms.  In this case, motor variable Ixx81 contains the address of 
the flag register for these U, V, and W inputs.  Ixx91 must be set to a value from $800000 to $FF0000; 
the actual value is dependent on the direction and phasing of the sensors relative to the motor 
commutation cycle. 

If the hall sensors are connected to the encoder inputs on Turbo PMAC and therefore to the encoder 
counter, the count information should be processed in the conversion table with the 1/T-extension method 
(method digit $0) as for a quadrature encoder.  The sub-count estimation of this method is particularly 
important here because of the low resolution of the sensors.  For details of setting up the encoder 
conversion table to process hall sensors used as encoders, consult the section Setting up the Encoder 
Conversion Table section in this manual and the specification for variables I8000 – I8191 in the Software 
Reference Manual. 

If the hall sensors are used for ongoing commutation feedback, probably it will be 
better to use the extended result data from the conversion table instead of the raw 
counter information that usually is used with encoders.  This will provide smoother 
commutation.  In this case, there will be 6 * 32 = 192 counts per commutation 
cycle instead of just 6. 

If the hall sensors are connected to the encoder inputs on a MACRO Station and therefore to the encoder 
counter, the count information should be processed in the Station’s conversion table with the 1/T-
extension method (method digit $0), just as for a quadrature encoder.  The sub-count estimation of this 
method is particularly important here because of the low resolution of the sensors.  The resulting 
enhanced position information is passed back to the Turbo PMAC, where it is processed by the Turbo 
PMAC’s encoder conversion table as unshifted parallel data (usually method digit $2, mode switch bit = 
1), because it already has fractional count information, before use by the Turbo PMAC servo and/or 
commutation algorithms.   

For details of setting up the encoder conversion table to process hall sensors used as encoders, consult the 
MACRO Station manuals, the section Setting up the Encoder Conversion Table section in this manual 
and the specification for variables I8000 – I8191 in the Software Reference Manual. 

For purposes of the motor’s servo loop and associated functions, the hall sensors will provide six counts 
per electrical cycle; a 4-pole motor would therefore have 12 counts per revolution.  If using the 1/T-
extended count data for the commutation, the commutation cycle size (Ixx71/Ixx70) will be 192 counts.