DRV10983: DRV10983 Over Current and Motor lock condition

Hi Kavya,

Thanks for posting your question in MD forum. Can you check the dead time? If the dead time is set too low, this will cause shoot through on DRV10983. The recommend minimum dead time is 440 ns for 24-V VCC and 360 ns for 12-V VCC.

Regards,

Vishnu

Hi Vishnu,

Thanks for the reply.

Dead time has been set to max 640ns. But still receive the same Over curr and Current lock limit status from driver.

Regards,

Kavya S

Hi Kavya,

Are you using DRV10987EVM or your own custom board? If you are using custom board can you share the schematic? Can you measure the resistance across U, V and W pin? 

Regards,

Vishnu.

Also, can you capture the phase current waveform? What is the current limit set to?

Hi Vishnu,

Over Current and motor lock condition is resolved has we had used wrong supply to motor.

Below are some of the observation while driving the motor

1. Motor specification 

1. Phase to phase resistance = 9.4, So R Centre Tap is 4.7. 

2. BEMF = VCC/Maximum Speed(no load) 

9760 (rpm) /  60 / 2 (4 pole) = 325Hz

9( Vcc) / 325 = 27.6 mv/Hz

3. Max motor continuous current 0.478A

2. Below are the DRV10983 driver register setting for open loop control

0x20 -> 0xE8 // Rm = 0x68

0x21 -> 0x1F //BEMF = 0x1F

0x23 -> 0x00 // SysOpt1 =0x00

0x24 ->0x18 //SysOpt2 open Curr = 0.2A, OpencurrRt = 0.7 Vcc/s

0x25 ->0xFD//SysOpt3 StAccel1= 2.1, StAccel2= 0.22, CC=1

0x26 -> 0x18//openlthrs = 12Hz, Align time =5.3

0x27-> 0xF4//  Lock enables

0x28 -> 0x01// Open Loop enable

With these configuration the motor spins at open loop  with 12HZ at 370mA

3. Below are the configuration to run in closed loop

0x22 -> 0xBA 

0x29-> 0xDF

0x28-> 0x00

0x01->0x80 // Speed cmd

0x00->0x32// Speed cmd

0x28 ->0x00 // Closed loop enable

With these closed loop configuration the motor stops.

The read back of Motor speed register {0x11:0x12} gives {0x00 : 0x0B}.

What parameter needs to be configured to run the motor in closed loop please suggest.

Please help on this asap.

Regards,

Kavya S

Hi Kavya,

Good to know that you were able to resolve the Over Current and motor lock condition issue. I checked your BEMF calculation. Is Vcc that you mentioned the  power supply to the device? If that is true then your BEMF is not accurate. Please check this video to measure the BEMF of your motor. Device checks the programmed BEMF constant Kt with the estimated value during open loop to closed loop transition. If the programmed value is incorrect, device will trip Abnormal Kt fault and will not enter closed loop. Also, the open to closed loop is set to 12 Hz which I think is very low. Please increase this to around 80-100 Hz. Align time is set to 5.3 sec which is long. You can reduce the align time to 1-2 sec if the motor inertia is not too high. Please keep monitoring the estimated Kt around the handoff frequency and make sure the estimated Kt is close to measured Kt. 

Regards,

Vishnu.

Hi Vishnu,

I need some clarification on the motor drive application. We are using Maxon EC 241916 motor which has nominal voltage of 9V.

The datasheet specifies drv10983 is designed for 12- to 24-V motor drive applications. The motor specified above can be used.

Please suggest asap.

Regards,

Kavya S

Hi Kavya,

12 to 24 V is the input voltage Vcc. Min motor voltage that DRV10983 can support is 8V so the device should be able to drive your motor at 9V motor voltage.

Regards,

Vishnu.