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DRV10970: Driving Motor at speed lower than can be achieved at 10% duty using unorthodox means.

February 23, 2018, 1:42 pm
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Part Number: DRV10970

Long time reader first time poster,

I am using the DRV10970 to drive a Fallhaber 1509T006B motor. I am trying to make the motor spin as slowly as possible. At 10% duty the DRV10970 makes the motor spin at ~1000 RPM. In order to spin it slower than that I have configured an MSP430 to alternate between passing the DRV10970 an 100% and a 0% duty cycle about 150 times a second. (A pwm of a pwm in some ways). This method has allowed me to spin the motor as slowly as 150 RPM which is great.I was wondering if this would result in any damage to the DRV10970, especially if I were to do this for a long time, like for a year or two. 

Thank you,

Garrett

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RE: DRV8301-Q1: DRV8301 getting damaged when trying to start motor

February 23, 2018, 7:53 pm
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I just wanted to give an update on my situation. We decided to replace the DRV8301. We also decided to skip trying to do open loop control testing and used the Hall signals to get the rotors position. We are now currently using interrupts on the Hall signals so that the commutations take place when the Hall states change. We were able to get the motor to turn very slowly. However, we had replaced the three 100uF caps with 270uF caps and only ran the DC bus voltage up to 18V with the PWM duty cycle at 10%. So we expected to have the motor turn slowly initially (this is the reason we started at such a low duty cycle). However, we tried to increment the duty cycle by another 10% (using a button as an input to do this), but the FAULT pin would go low. We could power cycle and clear the fault and then repeat the same thing. Also, if we kept the duty cycle constant at 10% but tried to increase the voltage we would get a beeping sound (different than the screeching sound mentioned before) but no fault and no noticeable speed increase. We think we need more bulk capacitance and possible TVS diodes on the DC bus. We didn't get a chance to get any measurements or waveforms due to lack of time. Any suggestions?

-Brandon
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DRV8301-Q1: DRV8301 getting damaged when trying to start motor

February 23, 2018, 2:34 pm
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Part Number: DRV8301-Q1

Hello everyone,

I am using the DRV8301 on a custom board to run a 48V 1000kW BLDC motor.  We are trying to use 6-step commutation with a PWM frequency of 20kHz.  We are 100% sure we have the correct commutation sequence because the motor came with a unidirectional (we are designing new controller for bidirectional control) motor driver and we measured the voltage wave forms for the Halls and phases.  I am new to motor control but have done tons of research about sensorless and hall sensor based trapezoidal motor control for BLDC.  Our first goal was to get the motor turning using open loop control before we moved on the a closed loop control via Hall sensor inputs.  The way we decided to try and do this was to set the electrical frequency for the phases to give us a mechanical speed of approximately 2 revolutions per second.  We are running a continuous loop to step through the commutations in one direction.  We start the commutations with a 10% duty cycle and an input voltage of 48V on the DC bus.  We are not locking the motor to two phases as would be done in some sensorless techniques at start up before commutation.  We then begin to slowly increase the duty cycle by 10% increments, with the thought being that the mechanical revolution we are trying to obtain is slow enough that the rotor will have time follow the rotating stator flux.  However, as soon as we try to start the motor at a low duty cycle, the motor screeches (which I assume is from the rotor not being able to get to the excited phase fast enough).  Then the DRV8301 FAULT pin indicates a fault.  The DRV8301 will not come out of the fault even on a power cycle with the motor disconnected.  The motor has 11 pole pairs and has 120 degree Hall sensors, resulting in a commutation change at about every 5.5 degrees.  We believe that the DRV8301 is getting damaged but don't know what is actually causing the damage.  We assumed that if the motor did not move with the commutations, we would be able to slightly turn it by hand to get it to engage since we are trying to turn the motor at a low RPM, but before we can even touch the motor the DRV8301 gets damaged.  Any help or advice would be appreciated.  I am attaching the schematic, but if any more info is needed just ask.

Thank you,

Brandon

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RE: BOOSTXL-DRV8305EVM: doesn't work at low duty cycles

February 24, 2018, 3:57 am
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Dear Garrett

Thanks for your question.

Attached the requested Pictures. As you can see, at 10% duty cycle everything is ok.

With 1% duty cycle, GLA is not completly pulled low. GHA is Zero all the time.

If I see the flat ramp at GLA (10%) and the expected begining of it at GLA (1%), it seams not to discarge fast enough. What do you mean?

Another question, which doesn't matter with that Problem but which I asked me: Must all 3 INHx have the rising flank at exact the same time? My timers has only 2 pwm Outputs. So for 3 PWMs, I have to use 2 timers which are not synchronized. Is that a Problem? (see last Picture of INHA + INHB)

INHA + GLA: 1% duty

INHA + GHA: 1% duty

INHA + GHA: 10% duty

INHA + GLA: 10% duty

INHA + INHB: 10% duty

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BOOSTXL-DRV8305EVM: doesn't work at low duty cycles

February 10, 2018, 2:04 am
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Part Number: BOOSTXL-DRV8305EVM

Dear all

I am using an BOOSTXL-DRV8305EVM-Evaluation board together with a Particle Photon, 120 MHz-Microcontroller (3.3V).

I configured the DRV8305 via SPI to 3-PWM-Mode in a open loop mode. For that, I give out a three sine PWM signals generated from a lookup table. PWM frequency: 28 kHz; Resolution 11 bit.

PVDD is 15V, the motor has an internal resistance of 0.3 Ohm.

As long as the duty cyle is high enough (appr. >10%), everything seems to work well. I can measure rising and falling Voltages from every Phase to ground. But I need a duty cycle of <1% that the motor doesn't burn at free wheeling at slow speeds (1 rpm). But with a duty cycle <10%, there are no voltages applied to the motor phases. Voltages from Phases to ground stays 0V. Either there is no error indicatet (red led on BOSSTXL isn't switched on).

What is the problem? Do I have to modify some configuration values?

Thanks a lot for your help.

Kind regards

Silvan

M.Sc.

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RE: DRV8301-Q1: DRV8301 getting damaged when trying to start motor

February 24, 2018, 2:14 pm
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Hi Brandon,

Measurements and waveforms will help considerably.

At 18V and 10%, have you measured the motor currents? Have you monitored PVDD when increasing the duty cycle?

You may need more bulk and possible TVS diodes.
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DRV8814: IC not working.

February 24, 2018, 9:48 pm
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Part Number: DRV8814

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Hi,
I use DRV8814 and you see my schematic. I don't want to use chopper properties of IC.
Therefore I connect Avref and Bvref pins to 3v3. A1, A0, B1, B0 pins connected to gnd.
This circuit not works.

CP1 and CP2 pin voltage nearly zero volts. VCP pin voltage around of 1.5 volts.
There are something wrong but I didn't find it. I tried different ICs but problem continue.

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RE: DRV10987: inductor for the SW pin of DRV10987

February 25, 2018, 12:54 am
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i dont need the buck regulator because i need 3.3v and the buck regulator only gives 5v, right?

so, i want to use the LDO 3.3V FOR EXTERNAL USE. while not using buck regulator and using LDO 3.3V do i still need to insert inductor in the SW pin of the DRV? or this inductor can be switch in resistor .

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DRV10987: inductor for the SW pin of DRV10987

February 19, 2018, 10:57 pm
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Part Number: DRV10987

hi,

i use the part DRV10987 as a driver to a circle motor. i got from the WEBENCH tool that in the SW pin i need to insert an inductor of 47uH. I dont have many space in the board. need the smallest inductor that fits.

which inductor do tou recomend? 

Maximum DC Current:1 A
the drv10987 voltage output is 30v.
thanks,
Liraz Abramovsky.
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RE: DRV8814: IC not working.

February 25, 2018, 7:24 am
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Hi Motor,

Would you please try to re-attach the schematic?

If VCP is 1.5V, please check VM. When nSLEEP is low, VCP should be approximately VM - 0.7V.
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DRV10983: testing DRV10983

February 25, 2018, 11:01 am
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Part Number: DRV10983

hello

I have to put some thought on how to test a DRV10983 over a range of bldc motors parameters

I could use different bldc motors for each test; but is it possible to test a DRV10983 against another DRV10983?

I would isolate them with a transformer, seems the DRV10983 can absorb some power, with a correct circuit design

do you think this is feasible?

also

does TI have a C source code file for the DRV10983 with the registers (something like DRV10983.h)

I've written one but would like to have different sources if possible

regards

enzo

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RE: DRV10987: inductor for the SW pin of DRV10987

February 25, 2018, 1:06 pm
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Liraz,

The 3.3V LDO can not support an external load unless the 5V buck regulator is used with an inductor.

Thanks,
Brian
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RE: DRV10983: testing DRV10983

February 25, 2018, 1:13 pm
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Enzo,

I'm not sure what/how your trying to use DRV10983 as both a source and a load. DRV10983 will not behave as a motor in a load condition so I don't think this is feasible.

We do not have a released header file.

Thanks,
Brian
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RE: DRV8825EVM: Supporting of Win 10 PC

February 25, 2018, 5:23 pm
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Hi Rick-san and Betty-san,

Thank you for your support.
I sent e-mail to Rick-san.

Best regards,
Shimizu
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DRV8812: May we have Bipolar Stepper Motor Driver with 4-Level Current Regulation that Vin can down to 6V(Vmax is 45V)?

February 25, 2018, 10:18 pm
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Part Number: DRV8812

Hi Sir 

May we have Bipolar Stepper Motor Driver with 4-Level Current Regulation that Vin can down to 6V(Vmax is 45V)?

I check website, there seems have no~~

                                                                       Bogey 

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RE: DRV8834: Decay mode

February 25, 2018, 10:48 pm
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Hello James-san,

Thank you for your reply.
I see when the current increases the DRV8834 will use slow-decay.
Which decay mode will use after resetting the DRV8834 (at initial position)?

The customer evaluated it. It use slow-decay at initial position and it use mixed-decay
at after 8 STEPs. Is this correct operation?

Regards,
Naoki Aoyama
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RE: DRV8885: Internal clock

February 25, 2018, 11:24 pm
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Hello James-san,

Thank you for your reply.

Sorry, I gave you wrong answer.
The customer already estimate EMI noise. There is poor margin at 200MHz.
The condition of the customer as follows.
VM=24V
Full scale current = 700mA - 800mA
Full Step and Mixed-decay.

Could you tell me what is the source of EMI noise as 200MHz?

Best Regards,
Naoki Aoyama
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DRV8885: Internal clock

February 20, 2018, 11:50 pm
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Part Number: DRV8885

Hello,

Our customer use the DRV8885, have a question.

The customer consider the EMI noise reduction.

Could you tell me how about the frequency of internal clock for the charge pump circuit and

the OCP digital counter?

Best Regards,

Naoki Aoyama

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RE: DRV110: Problems with Input Voltage at 8pin version

February 26, 2018, 12:14 am
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Okay, the Problem is solved. I have been sent a wrong part, and didn't realize it. Thanks Kevin for your fast support and stamina regarding that topic!
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DRV110: Problems with Input Voltage at 8pin version

February 8, 2018, 2:59 am
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Part Number: DRV110

Hello TI DRV110 Support,

I have ordered the DRV110 Evaluation Board plus 10 ICs of the 8pin Version of the DRV110. I wanted to test the DRV110 8pin IC, but I can't establish a proper Input voltage unfortunatelly.

When I measure directly with a multimeter in Diode-measurement-mode from Pin Vin to Pin Gnd, I measure round about 0.5V. And thats also the voltage when I connect an external voltage supply with (let's say) 15-20V to pin Vin. I also set a current limiting resistor inbetween, so that's not the problem.

I don't have these problems on the DRV110 Eval board. So I also tried to connect the voltage (V_limit) from the Eval Board to the Vin Pin of the 8pin DRV110. I failed too.

I'm really confused but there must be a possibility with that. Thanks in advance!

Cheers

Thomas

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