Figure 6-16
shows the motor-start sequence implemented in the
MCF8329A-Q1 device.
Power-On StateThis is the initial state of the Motor Start Sequence (MSS). The MSS starts in this state on
initial power-up or whenever the MCF8329A-Q1
comes out of standby or sleep mode.
DIR Change && DIR_CHANGE_MODE = 0b JudgementIn MCF8329A-Q1, if direction
change command is detected and DIR_CHANGE_MODE is
set to 0b during any state (including closed
loop), the device re-starts the MSS.
ISD_EN JudgementAfter power-on, the MCF8329A-Q1 MSS enters the ISD_EN judgement where
it checks to see if the initial speed detect (ISD)
function is enabled (ISD_EN = 1b). If ISD is
disabled, the MSS proceeds directly to the
BRAKE_EN judgement. If ISD is enabled, MSS
advances to the ISD (Is Motor Stationary)
state.
ISD StateThe MSS determines the initial condition (speed, direction of spin) of the motor (see Initial Speed Detect (ISD)). If motor is deemed to be stationary (motor BEMF < STAT_DETECT_THR), the MSS proceeds to BRAKE_EN judgement. If the motor is not stationary, MSS proceeds to verify the direction of spin.
Direction of Spin JudgementThe MSS determines whether the motor is spinning in the forward or the reverse direction. If the
motor is spinning in the forward direction, the
MCF8329A-Q1 proceeds to
the RESYNC_EN judgement. If the motor is spinning
in the reverse direction, the MSS proceeds to the
RVS_DR_EN judgement.
RESYNC_EN JudgementIf RESYNC_EN is set to 1b, MCF8329A-Q1 proceeds to Speed
> Open to Closed Loop Handoff (Re-sync)
judgement. If RESYNC_EN is set to 0b, MSS
proceeds to HIZ_EN judgement.
Speed > Open to Closed Loop Handoff (Re-sync) JudgementIf motor speed > FW_DRV_RESYN_THR, MCF8329A-Q1 uses the speed and
position information from the ISD state to transition to the closed loop
state (see Motor Resynchronization )
directly. If motor speed < FW_DRV_RESYN_THR, MCF8329A-Q1 transitions to open loop state.
RVS_DR_EN JudgementThe MSS checks to see if the reverse drive function is enabled (RVS_DR_EN = 1). If it is enabled, the MSS transitions to check speed of the motor in reverse direction. If the reverse drive function is not enabled, the MSS advances to the HIZ_EN judgement.
Speed > Open to Closed Loop Handoff (Reverse) JudgementThe MSS checks to see if the reverse speed is high enough for MCF8329A-Q1 to decelerate in closed loop. Till
the speed (in reverse direction) is high enough,
MSS stays in reverse closed loop deceleration. If
speed is too low, then the MSS transitions to
reverse open loop deceleration.
Reverse Closed Loop, Open Loop Deceleration and Zero Speed CrossoverThe MCF8329A-Q1 resynchronizes in the reverse direction, decelerates
the motor in closed loop till motor speed falls
below the handoff threshold. (see Reverse Drive).
When motor speed in reverse direction is too low,
the MCF8329A-Q1
switches to open-loop, decelerates the motor in
open-loop, crosses zero speed, and accelerates in
the forward direction in open-loop before entering
closed loop operation after motor speed is
sufficiently high.
HIZ_EN JudgementThe MSS checks to determine whether the coast (Hi-Z) function is enabled (HIZ_EN =1). If the coast function is enabled, the MSS advances to the coast routine. If the coast function is disabled, the MSS advances to the BRAKE_EN judgement.
Coast (Hi-Z) RoutineThe device coasts the motor by turning OFF all six MOSFETs for a certain time configured by HIZ_TIME.
BRAKE_EN JudgementThe MSS checks to determine whether the brake function is enabled (BRAKE_EN =1). If the brake function is enabled, the MSS advances to the brake routine. If the brake function is disabled, the MSS advances to the motor start-up state (see Section 6.3.9.4).
Brake RoutineMCF8329A-Q1 implements a brake by
turning on all three low-side MOSFETS for BRK_TIME.
Closed Loop StateIn this state, the MCF8329A-Q1 drives the motor with
FOC.
Note: User should
ensure adequate start up time to fully charge the bootstrap capacitors. One option
to charge the boot capacitor is by providing enough time with low side brake at
start up. Another option is to use the bootstrap precharging routine. The device
will initiate ISD only after bootstrap voltage crosses the UVLO threshold.