S32K396_eTPU_ATO_Time for alignment between excitation and sin signal after CPU initialization?

[Zhougw]

After CPU initialization, excitation and sin/cos signal are not aligned, the alignment is controlled by eTPU.

How much time would eTPU take for alignment between excitation and sin/cos signal?

To put it another way, How much time should ASW task wait to get a correct angle and speed after CPU initialization?

for example: set exc_i_gain = 0.00012(the same as the value in dual motor demo code)

[nxa17216 · Accepted solution]

Hello,

the time which is needed for the complete successful Resolver ATO startup depends on how quickly will the feedback signals align to the signal buffers. for that the important parameter is start_offset. The better is this one tuned for the particular application the faster the alignment at the ATO startup would be. The figure below illustrates the importance of start_offset parameter. This is dependent on the application and external circuitry as well, so you need to tune this with respect to your application and HW used. You only need to tune this once and then you can use the best start_offset parameter you will find for you. 

Other aspect that could have influence on the time of the initialization phase is the range (amplitude) of the input feedback signals. In the first step before the alignment is started the signals needs to be detected by the ATO in the signal buffers. When the signals are low it might take more time to detect them and more iterations of signal detection. Other parts of startup procedure are quite stable. From the experiences the ATO start-up usually takes around 25 ms.