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3.6 Fault Handling
Below are the faults that can possibly get triggered based on the default register configuration specified in
3-1.
3.6.1 MPET IPD Fault [MPET_IPD_Fault]
This fault gets triggered when there is no motor connected to the phase pins of the device or when the MPET
IPD Current threshold [MPET_IPD_CURRENT_LIMIT] is set low for motors with high resistance. If this fault is
triggered, then please follow the below suggestions.
Step 1: After confirming this fault triggers consistently from multiple start up attempts, check if all the phases of
the motor are connected to the phase pins of the device.
Step 2: If the fault persists, increase the MPET IPD Current threshold [MPET_IPD_CURRENT_LIMIT]
Step 3: If the fault still persists, check motor datasheet for motor resistance and inductance. Open the "Control
configuration – Motor Parameters" tab in All tuning settings section in the GUI and program motor phase
resistance and motor phase inductance.
Step 4: If the motor does not have a datasheet, then measure the phase to phase resistance across any two
phases using a Digital Multimeter and calculate the phase resistance by dividing the phase to phase resistance
by 2 as shown in equation
resistance, R
as shown in
PH
motors.
R
Pℎase resistance =
PH
To know the motor inductance, measure the phase to phase inductance at 1 kHz across any two phases using
an LCR meter. Calculate the phase inductance by dividing the phase to phase inductance by 2. Motor phase
inductance refers to the inductance from the phase output to the center tap, L
motors with different phase-phase inductances, measure all three phase to phase inductances and calculate
their average and use this value as the phase to phase inductance. This measurement holds good for both star
wound and delta wound motors.
3.6.2 MPET BEMF Fault [MPET_BEMF_Fault]
This fault gets triggered when motor stalls while running in open loop for BEMF estimation. If this fault is
triggered, then please follow the below suggestions.
SLLU335A – AUGUST 2021 – REVISED JANUARY 2022
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Equation
2. The motor phase resistance refers to the equivalent phase to center tap
Figure
3-2. This measurement holds good for both star wound and delta wound
R PH_PH Pℎase to Pℎase resistance
2
Phase C
Figure 3-2. Motor Resistance
Phase C
Figure 3-3. Motor Inductance
Copyright © 2022 Texas Instruments Incorporated
Phase A
CT
R
PH_PH
Phase B
PH
Phase A
CT
L
PH_PH
Phase B
Essential Controls
as shown in
Figure
3-3. For
MCF8316A Tuning Guide
Table
(2)
9
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