Below are the steps to tune the motor
to achieve faster startup time using IPD as the motor startup method:
- Select IPD [MTR_STARTUP] as the
motor startup method.
- Increase IPD current threshold
[IPD_CURR_THR] to rated current of the motor. Use equation 4 to choose the
correct IPD_CURR_THR.
- Increase IPD clock value
[IPD_CLK_FREQ] to higher frequency up to a value where the device does not
trigger IPD frequency fault.
- Select IPD repeating times
[IPD_REPEAT] to 1 time.
- Configure IPD release mode
[IPD_RLS_MODE] to Tri state.
- Select Open loop current limit
[OL_ILIMIT] to be the same as cycle by cycle current limit [ILIMIT].
Note: If the device triggers cycle
by cycle current limit [CBC_ILIMIT], it is recommended to increase [ILIMIT]
upto the stall current of the motor. Configuring this to a value higher than
motor stall current might overheat or damage the motor.
- Increase Open loop acceleration
coefficient A1 [OL_ACC_A1] and Open loop acceleration coefficient A2
[OL_ACC_A2].
Note: A1 and A2
can be increased until open loop current reaches Lock detection current
threshold [LOCK_ILIMIT]. Open loop current can be measured using
oscilloscope.
Increasing Open loop acceleration coefficient A1 [OL_ACC_A1] and Open
loop acceleration coefficient A2 [OL_ACC_A2] might trigger LOCK_LIMIT or
CBC_ILIMIT. If this happens, reduce A1 and A2 until LOCK_LIMIT no longer
triggers.
For ultra-fast startup time (less than
100 ms) it is recommended to follow below steps:
- Disable auto-handoff
[AUTO_HANDOFF].
- Configure Open loop handoff
cycles [OL_HANDOFF_CYCLES] to 3.
- Configure INTEG_ZC_METHOD to
Integration.
- Enable Dynamic degauss
[DYN_DEGAUSS_EN].
- Configure open to closed loop
handoff threshold [OPN_CL_HANDOFF_THR] to a value lesser than or equal to 20
Hz.
For startup times above 100 ms, it is
recommended to follow below steps:
- Enable auto-handoff
[AUTO_HANDOFF].
- Configure Open loop handoff
cycles [OL_HANDOFF_CYCLES] to 6.
- Enable Dynamic degauss
[DYN_DEGAUSS_EN].
Note: If
Abnormal speed fault [ABN_SPEED] gets triggered, it is recommended to
decrease open loop acceleration constants [OL_ACC_A1] and [OL_ACC_A2] and
also retune IPD by increasing the IPD current threshold [IPD_CURR_THR] and
IPD repeat times [IPD_REPEAT].
- Increase Closed loop acceleration
rate [CL_ACC].
Note: Closed loop
acceleration rate [CL_ACC] can be increased until closed loop current
reaches Lock detection current threshold [LOCK_ILIMIT]. Closed loop current
can be measured using oscilloscope. Increasing closed loop acceleration rate
[CL_ACC] might trigger LOCK_LIMIT. If this happens, reduce closed loop
acceleration rate [CL_ACC] until no longer triggers.
Figure 2-2 shows the phase current, FG and Speed curve when the motor is started using IPD
as the startup method. Time taken for the motor to accelerate to 100% duty cycle is
around 35 ms.