DRV11873 - Motor stops around 7200rpm

Hiroshi Katsunaga

Mastermind 6480 points

Other Parts Discussed in Thread: DRV11873, DRV11873EVM, DRV10983

Hello,

My customer has a question about DRV11873.

[Q]

They want to use the device to control the motor at around 7200rpm,but the motor always stops at around 7200rpm.

It can control the motor at around 10000rpm.

I watched the following post.

DRV11873EVM - Motor stops over 9500rpm (http://e2e.ti.com/support/applications/motor_drivers/f/38/t/314799.aspx)

The result is as follows when I use the formula of mention for that post.

FG = RPM * PP / 60 = 7200 * 12 / 60 = 1440Hz > Maximum speed limit 950Hz@FS=1

Is this a problem of maximum speed limit control ?

Can DRV11873 control the motor at around 7200rpm ?

[Motor Information]

- Manufacture name : NIDEC Corporation

- Series : Smart_28S series (http://www.nidec.com/en-IN/product/motor/category/A010/B010/P0000014/)

- Rated Speed : around 7200rpm

(Product information of the URL describe rated speed with 9200rpm～, but rated speed of the customer's custom motor can operate around 7200rpm.)

- Pole Pair (PP) numbers : 12

Best Regards,

Hiroshi Katsunaga

over 9 years ago

0 Rick Duncan over 9 years ago

TI__Guru** 114905 points

Hi Katsunaga-san,

If the pp = 6, FG at 7200RPM is 720Hz and the DRV11873 control the motor to 7200rpm.

Because the pp=12, the FG at 7200 RPM is 1440Hz and the DRV11873 cannot control the motor.

We will check for an alternative device.

0 Hiroshi Katsunaga over 9 years ago in reply to Rick Duncan

Mastermind 6480 points

Hi Rick-san,

Thank you for your fast response.

I understood your comment.

It would be extremely helpful if you suggest an alternative device.

Best Regards,

Hiroshi Katsunaga

0 Yisong Lu over 9 years ago in reply to Hiroshi Katsunaga

TI__Prodigy 355 points

Katsunaga-san,

I am sorry, there is no 'All-in-one' device in TI portfolio that meets this speed (1400Hz) requirement.

'All-in-one' means control logic, analog circuit, and mosfets are all integrated in one device.

0 Hiroshi Katsunaga over 9 years ago in reply to Yisong Lu

Mastermind 6480 points

Hi Lu-san,

Thank you for your fast response.

I'm OK.

I'd appreciate your help.

Best Regards,

Hiroshi Katsunaga

0 Hiroshi Katsunaga over 9 years ago in reply to Hiroshi Katsunaga

Mastermind 6480 points

Hi Lu-san,

The motor information of my customer had a mistake.

I correct it as follows.

[Motor Information]

- Manufacture name : NIDEC Corporation

- Series : Smart_28S series (http://www.nidec.com/en-IN/product/motor/category/A010/B010/P0000014/)

- Rated Speed : around 7200rpm

(Product information of the URL describe rated speed with 9200rpm～, but rated speed of the customer's custom motor can operate around 7200rpm.)

- Pole Pair (PP) numbers : 4

I want to ask you some questions again.

[Q1]

FG = RPM * PP / 60 = 7200 * 4 / 60 = 480Hz < 950Hz@FS=1

The motor always stops at around 7200rpm.

Can DRV11873 control the motor at around 7200rpm ?

[Q2]

Can DRV11873 stop control of the motor at around 7200rpm positively ?

Best Regards,

Hiroshi Katsunaga

0 Yisong Lu over 9 years ago in reply to Hiroshi Katsunaga

TI__Prodigy 355 points

Katsunaga-san,

Several conditions can make DRV11873 stop. Speed > 950Hz is positively one reason. Beside that, if the motor inductance is high, motor will stop at a lower speed.

We need the motor phase current waveform before motor stops to help you debug this issue.

Or, please consider DRV10983 which is sinusoidal control and works up to 1000Hz.

0 Hiroshi Katsunaga over 9 years ago in reply to Yisong Lu

Mastermind 6480 points

Hi Lu-san,

Thank you for your fast response.

And I'm really sorry that my response is late.

I got the motor phase current waveform from my customer.

I attached it.

3051.drv11873_cs.pdf

Could you put your comments ?

Best Regards,

Hiroshi Katsunaga

0 Yisong Lu over 9 years ago in reply to Hiroshi Katsunaga

TI__Prodigy 355 points

Katsunaga-san,

Are these waveform captured during motor normal operation, or just before it stop.

Could you double confirm the second curve is FG? FG should go high and low every electrical cycle, but it doesn't change in the waveform.

Does customer consider the option of DRV10983.

0 Hiroshi Katsunaga over 9 years ago in reply to Yisong Lu

Mastermind 6480 points

Hi Lu-san,

I confirmed the waveforms to my customer.

The blue lines are the RD waveforms.

The upper waveforms are the stop waveforms of 7,200rpm that it triggered RD.

The bottom waveforms are the normal waveforms of 6,000rpm.

I introduced DRV10983, but they want to clear up this issue in DRV11873.

What do you think ?

Best Regards,

Hiroshi Katsunaga

0 Yisong Lu over 9 years ago in reply to Hiroshi Katsunaga

TI__Prodigy 355 points

Katsunaga-san,

Could you help double comfirm that FS is connected to 1. The waveform you have captured looks like motor stops at around 500Hz which is the threshold when FS = 0.

0 Hiroshi Katsunaga over 9 years ago in reply to Yisong Lu

Mastermind 6480 points

Lu-san,

I confirmed the setting of FS when they measured the waveform.

The waveform was measured that FS was connected to 1.

Could you put your comments ?

Best Regards,

Hiroshi Katsunaga

0 Hiroshi Katsunaga over 9 years ago in reply to Hiroshi Katsunaga

Mastermind 6480 points

Lu-san,

How about after that ?

Could you put your comments ?

Best Regards,

Hiroshi Katsunaga

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DRV11873 - Motor stops around 7200rpm