DRV10975_15 Datasheet, PDF (19/57 Pages) Texas Instruments – DRV10975 12-V, Three-Phase, Sensorless BLDC Motor Driver

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DRV10975
SLVSCP2 – JANUARY 2015
is spinning too quickly. If the reverse speed of the motor is less than the threshold defined by
RvsDrThr[2:0], then the MSS advances to the RvsDrEn judgment.
RvsDrEn Judgment The MSS checks to see if the reverse drive function is enabled (RvsDrEn = 1). If it is, the
MSS transitions into the RvsDr state. If the reverse drive function is not enabled, the MSS
advances to the BrkEn judgment.
RvsDr State The DRV10975 drives the motor in the forward direction to force it to rapidly decelerate (see
Reverse Drive). When it reaches zero velocity, the MSS transitions to the Accelerate state.
BrkEn Judgment The MSS checks to determine whether the brake function is enabled (BrkDoneThr[2:0] ≠ 000).
If the brake function is enabled, the MSS advances to the Brake state.
Brake State The device performs the brake function (see Motor Brake).
Speed>BrkDoneThr Judgment The MSS waits until the motor has decelerated to a velocity that is less than the
brake threshold configured by BRKDoneThr[2:0]. When the motor velocity is below this threshold,
the MSS advances to the IPDEn judgment.
IPDEn Judgment The MSS checks to see if IPD has been enabled (IPDCurrThr[3:0] ≠ 0000). If the IPD is
enabled, the MSS transitions to the IPD state. Otherwise, it transitions to the align state.
Align State The DRV10975 performs align function (see Align). After the align completes, the MSS transitions
to the Accelerate state.
IPD State The DRV10975 performs the IPD function. The IPD function is described in IPD. After the IPD
completes, the MSS transitions to the Accelerate state.
Accelerate State The DRV10975 accelerates the motor according to the setting StAccel and StAccel2. After
applying the accelerate settings, the MSS advances to the Speed > Op2ClsThr judgment.
Speed>Op2ClsThr Judgment The motor accelerates until the drive rate exceeds the threshold configured by
the Op2ClsThr[4:0] settings. When this threshold is reached, the DRV10975 enters into the
ClosedLoop state.
ClosedLoop State In this state, the DRV10975 drives the motor based on feedback from the commutation
control algorithm.
DIR Pin Change Judgment If DIR pin get changed during any of above states, DRV10975 stops driving the
motor and restarts from the beginning.
9.4.3.1 ISD
The ISD function is used to identify the initial condition of the motor. If the function is disabled, the DRV10975
does not perform the initial speed detect function and treats the motor as if it is stationary.
Phase-to-phase comparators are used to detect the zero crossings of the motor’s BEMF voltage while it is
coasting (motor phase outputs are in high-impedance state). Figure 10 shows the configuration of the
comparators.
60 degrees
±
V
+
U
+
W
±
Figure 10. Initial Speed Detect Function
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