ElmoMC SimplIQ Software Manual - Manual (Page 120)

SimplIQ Software Manual Commutation
MAN-SIMSW (Ver. 1.4)
8-10
8.4.3 Protections
The method described here can work reliably in many practical situations, although it does
not match every application. If the parameters of the method are not tuned properly, or if
the method does not match the application, the motor starting process will fail.
After setting MO=1, the algorithm will attempt to rotate the motor back and forth and find
the commutation angle. If the results are not reliable, because the oscillation amplitude is
too small or because the load behavior is not inertial, MO will reset automatically to zero
and the motor will not start.
8.4.4 Maximum Number of Iterations for Auto-phasing
The CA[27] parameter defines the maximum admissible number of iterations for the auto-
phasing process. If the process fails due to overload (the motion amplitude is less than
CA[24]), the auto-phasing may be repeated several times, doubling the current at each
iteration. If the peak current limit is reached during any attempt, the auto-phasing process
will stop even if CA[27] allows continuous iterations.
8.4.5 Starting the Motor without Digital Hall Sensors
The following parameters are relevant to starting the motor when digital Hall sensors are
not used.
Parameter Description
CA[18]
CA[19]
Encoder resolution and number of motor pole pairs.
CA[18] must be greater than CA[19] * 256.
CA[20] Must be set to 0 to indicate that no Hall sensors are present.
CA[21] Must be set to 1 to indicate that an encoder is present.
CA[15] Set the oscillation frequency as explained previously.
CA[24] Set the minimum acceptable oscillation amplitude to 4.
CA[26] Set the excitation amplitude as a percentage of the continuous current.
CA[27] Set the maximum number of iterations for the auto-phasing process.
MO MO=1 sets the motor to on. If the motor starts to fail, MO resets to 0.
WS[15] Reads the actual oscillation amplitude.
WS[16] Flag if a non-inertial behavior has been observed.
8.5 Continuous vs. Six-step Commutation
The basic commutation equation for a sinusoidal motor (repeated here for convenience) is:
T = K
T
* I * sin(θ
F
- θ
r
) (1)
where:
θ
F
is the field electrical angle.
θ
r
is the rotor electrical angle.