DRV10987 Datasheet, PDF (32/69 Pages) Texas Instruments – DRV10987 12- to 24-V, Three-Phase, Sensorless BLDC Motor Driver

DRV10987
SLVSE89 – AUGUST 2017
www.ti.com
For motors with salient pole structures, aligning the motor BEMF voltage with the motor current may not achieve
the best efficiency. In these applications, the timing advance should be adjusted accordingly. Accomplish this by
operating the system at constant speed and load conditions and by adjusting t_adv until the minimum current is
achieved.
Phase
Voltage
Phase
Current
Phase
BEMF
t_adv
Figure 27. Advance Time (t_adv) Definition
The DRV10987 device has two options for adjusting the motor commutate advance time. When CommAdvMode
= 0, mode 0 is selected. When CommAdvMode = 1, mode 1 is selected.
Mode 0: t_adv is maintained to be a fixed time relative to the estimated BEMF zero cross as determined by
Equation 5.
t_adv = t_SETTING
(5)
Mode 1: t_adv is maintained to be a variable time relative to the estimated BEMF zero cross as determined by
Equation 6.
t_adv = t_SETTING × (U - BEMF) / U.[The symbol for voltage is V. The voltage on phase U should be V_U.]
where
• U is the phase voltage amplitude
• BEMF is phase BEMF amplitude
(6)
t_SETTING (in µs) is determined by the configuration of the TCtrlAdvShift [2:0] and TCtrlAdvValue [3:0] bits as
defined in Equation 7. For convenience, the available t_SETTING values are provided in Table 5.
t_SETTING = 2.5 µs × [TCtrlAdvValue[3:0]] << TCtrlAdvShift[2:0]
(7)
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