MCF8329A: Short circuit fault with no errors reported

KAIYU LIN

Prodigy 20 points

Part Number: MCF8316A
Other Parts Discussed in Thread: MCF8329A

I have the following HW setup:

1. MCF8316AEVM

2. Maxon 449464 motor

3. 24V 3A bench power supply

Default registers preset loaded using Motor Studio and then MPET runs successfully with 60% default rated peak current, 6000RPM and 7 Pole Pairs configuration.

Next, I rotate the potentiometer counter-clockwise fully so the motor runs at 6000RPM loaded; PSU showing driver drawing about 1.4A.

Then I don't know what happens but the motor suddenly stops with no fault displayed in Motor Studio, this can happen anytime between 10 minutes and 1 hour, I haven't tried for longer run times.

When it stops, it can either go short (PSU hitting current limit and 24V dragged down) or it just stops in an idle condition (24V 40mA) unable to restart by turning the potentiometer (power cycle required).

No fault LEDs displayed on the evaluation board.

5 months ago

0 Joshua Horlander Cruz 5 months ago

TI__Genius 13195 points

Hello Kaiyu,

Can you set MTR_LCK_MODE, LOCK_ILIMIT_MODE, and HW_LOCK_ILIMIT_MODE to the first option? This will make the faults latch if any fault occurs which will make it easier to determine if a fault occurs.

If possible, can you provide a capture of the phase current of the motor just before it stops?

Also, what is the Algorithm State when the motor suddenly stops?

Regards,

Joshua

0 KAIYU LIN 5 months ago in reply to Joshua Horlander Cruz

Prodigy 20 points

Hi Joshua, I just realised that the PN I selected is wrong, I am working with the MCF8316A, not the MCF8329A. Would you be able to amend it? I'll do more testing to get you the requested info.

0 KAIYU LIN 5 months ago in reply to Joshua Horlander Cruz

Prodigy 20 points

I was setting up the oscilloscope while it happened therefore no phase current yet. These were the two reported faults:

0 KAIYU LIN 5 months ago in reply to Joshua Horlander Cruz

Prodigy 20 points

More and more often the MPET is failing with OCP.

0 Joshua Horlander Cruz 5 months ago in reply to KAIYU LIN

TI__Genius 13195 points

Hello Kaiyu,

1. Is the motor unloaded or loaded when attempting to spin the motor and/or during MPET?

2. Can you try using the IDP startup method to see if this helps with the LOCK_LIMIT fault? The motor start up method can be changed using the MTR_STARTUP bit field in MOTOR_STARTUP1.

3. At what point in the MPET process does the OCP fault occur?

Regards,

Joshua

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MCF8329A: Short circuit fault with no errors reported