How to setup Incremental Encoder using eTPU Function?

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How to setup Incremental Encoder using eTPU Function?

Contributor I

hi, I'm engineer in south korea.

I doing make a inverter for operating a motor.

that's parameters are follows.

- Inverter power : 90[W]

- MCU : MPC5553MVZ132

- Position sensor : Incremental Encoder(2048[ppr])

- Motor Pole : 8[Pole]

- Motor Max speed : 2000[RPM]

that's  eTPU setting are follows.


First of all, when I was operate this inverter with other encoder(2000[ppr]), that worked correctly.

and All parameters except pulse count are same.

In this situation, i have some problem.

That Motor rotate very well under about 1200[rpm] but can't rotate over about 1200[rpm] and hunting with Fig. 1.

you can see, IU hunting is sync with index pulse.



I was check that 

 1. Enc pulse : 2048[ppr]

 2. Enc pulse wave

 3. Electric Theta and eTPU pluse count(from "fs_etpu_qd_get_pc(QD0_PRIMARY)")

 4. some parameter turning in "fs_etpu_qd_init"   

how to solve these problem?

plz... comment

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NXP Employee
NXP Employee

Hi Jo Zujo,

thank you for using our eTPU library.
Could, you, please, specify in more detail what problem are you facing?
You are stating that you used different encoder before. Did you use it together with this eTPU QD function before? Or did you use another way of processing A and B signal from rotary encoder?
If I understand it correctly now you replaced the encoder sensor with another one and when running the motor you cannot run it over 1200 rpm, correct? Could, you, please, share datasheet of the encoder you are using right now and having problem with?
How does the signals A nad B from encoder look like for case under 1200 rpm where you run with no problem and how does it look like when you are seeing problem? Have the wave forms changed (apart from frequency of pulses that is expected to be higher for high speed of course)?
Could you, please, specify what is the IU signal at your figure? I guess this is not an A or B output from encoder signal. What do you mean by hunting here? Your figure is hard to read, could you, please, provide some with better resolution?
Many thanks


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