This case covers possible workarounds
for ripples missed during motor start-up due to inrush current as observed in Figure 3-2.
Adjust the T_MECH_FLT register to match the system response time more
accurately, as shown in Figure 3-3. The trade-off here is to sacrifice some accuracy during steady-state
performance.
Using current regulation
during inrush time also helps the algorithm track ripples more
accurately.
If using internal speed or
voltage regulation feature, enable soft-start and soft-stop (EN_SS = 1b).
If using DRV8214, program the
controller to change CS_GAIN_SEL dynamically when loading/unloading is
expected in DRV8214. For more details on functionality of CS_GAIN_SEL, refer
to the data sheet.
Under same operating
conditions and settings, the device consistently misses the same number of
ripples each time. From Figure 4-6, Figure 4-7, Figure 4-8, and Figure 4-9, shows that the device misses 4 ripples during each start up. This can
easily be accounted for simply by subtracting the missed ripples from the
target ripple count. Programming the control unit to offset for four ripples
enables position tracking with better accuracy.