How to generate spwm wave by the exc channel of the resolver on the etpu module base on MPC5777C

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How to generate spwm wave by the exc channel of the resolver on the etpu module base on MPC5777C

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Harry0001
Contributor II

I have configuated the squre wave output to the resolver by the the exc channel of the etpu.But the circuit board what i used now is based on the spwm wave of the exc output other than the square wave.Thus i has to change the wave output type in the software.

So what i need is the spwm wave output generated on the 300khz carrier wave.and the spwm frequency is 10khz.The core used is MPC5777C,and the module is the etpu module.How to configuate the SPWM wave output in the resolver part of the etpu module?If it is infeasiable,is there other ways to make it come true?

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Yongbing_Nan
NXP Employee
NXP Employee

The generation of the exciting square wave signal of the resolver is linked with the soft resolver algorithm, and is not independent. The existing eTPU motor library can only generate square wave signals, and cannot generate the exciting signal through SPWM.

 

Yongbing_Nan_1-1674007071658.png

 

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Harry0001
Contributor II

Thanks!we had tried it by this way,but we think the best way is to generate the sin wave directly by the software other then modify the hardware circuit,as the reliability of the hardware circuit based on the sine wave has been verified for many times,if we modify the circuit we cannot guaranteed the reliability of the circuit.The application is a real project but not a demo project.

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johndiener
Contributor IV

Hello,

Are you using the NXP RESOLVER eTPU function (new motor control set)? That function does control the excitation output and as you note, generates a square wave (typically close to 10khz).  If your hardware for some reason requires something different, and yet you want to use the NXP RESOLVER eTPU function, you would likely need to modify the default eTPU software to meet your needs.  But it is not clear to me what your system hardware is, or whether you are using the NXP eTPU resolver software solution.

John Diener
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Harry0001
Contributor II

yes,I am using the  NXP RESOLVER eTPU function.Now our team had to change the hardware circuit to make the squre wave to sin wave.I want to know if we do not change the hardware,which means the circuit of the board is based on the sin wave design.in this case how can i generate the sine wave exc signal directly when i also used the resolver etpu function.Does it necessary to modify the etpu binary code to finish the change?

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johndiener
Contributor IV

I cannot say based on the limited information provided whether what you want to do is feasible or not. But to the explore the possibility you would need to modify the baseline eTPU resolver code. So you need (1) the source code, and (2) some eTPU development tools (you could get a free evaluation copy from ASH WARE). You would then need to look into modifying the excitation wave generating code, making sure that it still supported the existing synchronization and phase shifting capabilities (the existing code phase shifts excitation output based upon feedback from the SDADC data to ensure the sample period aligns with the sine wave period). An interesting project, but again, I can't really comment on feasibility without knowing quite a bit more.

John Diener
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davidtosenovjan
NXP TechSupport
NXP TechSupport

It is expected to have excitation amplifier on the eTPU PWM output to create sine wave for the resolver.

davidtosenovjan_1-1673439414855.png

davidtosenovjan_0-1673439287912.png

 

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