DRV10983: Lock 2 on startup

Richard Buswell

Part Number: DRV10983
Other Parts Discussed in Thread: USB2ANY

Hi,

We are driving a small BDCM with an impeller. Normal operation is fine, but occasionally we get false starts where the motor rotates at low speed and lock2 comes on. This situation can be provoked by providing speed demand when the motor has been spinning and is still slowing down (nearly stopped) when the speed voltage is increased again. I have tried unchecking some of the lock detects but the problem persists. Taking the speed voltage to zero clears the condition.

over 7 years ago

0 Rick Duncan over 7 years ago

TI__Guru** 114905 points

Hi Richard,

Our experts have been contacted and should reply soon.

0 Krushal over 7 years ago in reply to Rick Duncan

TI__Expert 3010 points

Hi Richard,

Symptoms are pointing toward inaccurate configuration of Phase to Phase Kt value, can you please verify that this value is correctly programmed. Try changing this value, and check if problem goes away.

Another thing you can try is changing the tuning the value of 'T control Advance'. For startup failure try increasing open to close loop threshold.

Regards,
Krushal

0 Richard Buswell over 7 years ago in reply to Krushal

Prodigy 130 points

Hi,

Thanks - the Phase to Phase Kt value is critical to getting the motor to run at maximum speed - it is set at the motor manufacturer's specified value of 6.4 mV/Hz - I have tried changing it plus and minus, but then the motor doesn't run fast properly. Everything is running fine except at low speed - if I start it then reduce the speed to low it will get to a point where it only rotates at low speed pulling a relatively high current and will not respond to increasing the speed demand. The motor is not required to run at low speed in the application, but the problem is that it can get into this state on startup if the fan is rotating at the time it goes into startup. At low speeds the measured velocity constant goes up to about 100!

0 Krushal over 7 years ago in reply to Richard Buswell

TI__Expert 3010 points

HI Richard,

Can you please share phase current waveform at low speed. Can you please let us know at what speed is this occurring - in terms of electrical hz and % of max speed?

Regards,
Krushal

0 Richard Buswell over 7 years ago in reply to Krushal

Prodigy 130 points

Hi, I will do that - when I get a replacement dev. kit. I just blew the chip in the USB2ANY interface :-((

I have noticed that I can provoke the situation by stalling the motor - either by lightly touching the armature on startup, or stalling during open-loop, or if I stall it in closed loop it stops then usually starts rotating slowly. Anyway, more data when I get the kit.

0 Richard Buswell over 7 years ago in reply to Krushal

Prodigy 130 points

Hi, sorry for the delay due to some equipment repairs.
The phase current waveform is around 2 Hz at about 3 amp PP. Top speed is around 1.5 KHz. In slow speed lockup it will not respond to the speed demand signal (analogue). Setting the demand to zero will clear the problem.