8.4.3 Motor Start Sequence
Figure 17 shows the motor-start sequence implemented in the DRV10987 device.
Figure 17. Motor Starting-Up Flow
Accelerate StateThe DRV10987 device accelerates the motor according to the settings of StAccel and StAccel2. After applying the accelerate settings, the MSS advances to the Speed>Op2ClsThr judgment.
Align StateThe DRV10987 device performs the align function (see Align). After the align completes, the MSS transitions to the Accelerate state.
Brake StateThe device performs the brake function (see Motor Brake).
BrkEn JudgmentThe 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.
ClosedLoop StateIn this state, the DRV10987 device drives the motor based on feedback from the commutation control algorithm.
DIR Pin Change JudgmentIf the DIR pin is changed during any of above states, DRV10987 device stops driving the motor and restarts from the beginning.
Forward Judgment The MSS determines whether the motor is spinning in the forward or the reverse direction. If the motor is spinning in the forward direction, the DRV10987 device executes the resynchronization (see Motor Resynchronization) process by transitioning directly into the ClosedLoop state. If the motor is spinning in the reverse direction, the MSS proceeds to the Speed>RvsDrThr.
IPDEn JudgmentThe 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.
IPD StateThe DRV10987 device performs the IPD function. The IPD function is described in Initial Position Detect (IPD). After the IPD completes, the MSS transitions to the accelerate state.
ISD StateThe MSS determines the initial condition of the motor (see Initial Speed Detect (ISD)).
ISDen JudgmentAfter power-on, the DRV10987 MSS enters the ISDen judgment where it checks to see if the initial speed detect (ISD) function is enabled (ISDen = 1). If ISD is disabled, the MSS proceeds directly to the BrkEn Judgment. If ISD is enabled, the motor start sequence advances to the ISD state.
Power-On StateThis is the initial power-on state of the motor start sequencer (MSS). The MSS starts in this state on initial power-up or whenever the DRV10987 device comes out of standby mode.
RvsDrEn JudgmentThe 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 StateThe DRV10987 device 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.
Speed<ISDThr JudgmentIf the motor speed is lower than the threshold defined by ISDThr[1:0], then the motor is considered to be stationary and the MSS proceeds to the BrkEn judgment. If the speed is greater than the threshold defined by ISDThr[1:0], the start sequence proceeds to the Forward judgment.
Speed>Op2ClsThr JudgmentThe motor accelerates until the drive rate exceeds the threshold configured by the Op2ClsThr[4:0] settings. When this threshold is reached, the DRV10987 device enters into the ClosedLoop state.
Speed>RvsDrThr JudgmentThe motor start sequencer checks to see if the reverse speed is greater than the threshold defined by RvsDrThr[1:0]. If it is, then the MSS returns to the ISD state to allow the motor to decelerate. This prevents the DRV10987 device from attempting to reverse drive or brake a motor that is spinning too quickly. If the reverse speed of the motor is less than the threshold defined by RvsDrThr[1:0], then the MSS advances to the RvsDrEn judgment.
Time>BrkDoneThr JudgmentThe MSS applies brake for a time configured by BRKDoneThr[2:0]. After brake state, the MSS advances to the IPDEn judgment.