Compiler/DRV8889-Q1: DRV8889-Q1 to drive a stepper motor but the phase current is wrong.

fuwei zhang

Prodigy 50 points

Part Number: DRV8889-Q1

Tool/software: TI C/C++ Compiler

Hi:

I am using DRV8889 to derive a stepper motor. Use an oscilloscope to observe the phase current. please see below.

This is not a sine wave.....

About decay modes , I've tried all the setting and noting to help. what am I missing??

My DRV8889-Q1 setting is :

1. microstep mode : 1/8

2. Step frequency is 10KHz

3. current regulation is 18.75%

4. other setting is the default

My stepper motor is :

over 3 years ago

0 Wang5577 over 3 years ago

TI__Guru 56650 points

Fuwei,

What is the input voltage? Would you increase the input voltage and reduce the motor speed and check the winding current again?

0 fuwei zhang over 3 years ago in reply to Wang5577

Prodigy 50 points

Hi Wang:

Input voltage:

VM pin : 24V

VDSO pin : 3.3V

I've tried to reduce the motor speed. when the step pin frequency is 1.5KHz, the phase current look like a sine wave.

please see below.

my question is what if i need to increase the revs??

0 Wang5577 over 3 years ago in reply to fuwei zhang

TI__Guru 56650 points

Fuwei,

When the motor is spinning, it will generate a back EMF voltage to against the input voltage which can make the winding current not follow the sine waveform. The back EMF voltage is higher with a higher speed. To overcome the back EMF, you can increase the input voltage or reduce the speed. If you cannot do those changes, you may need to change the motor.

0 fuwei zhang over 3 years ago in reply to Wang5577

Prodigy 50 points

Hi Wang:

Thank you for your response.

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Compiler/DRV8889-Q1: DRV8889-Q1 to drive a stepper motor but the phase current is wrong.