AD2S1210 resolution setting

Hello

             Customer would like to meet 16000rpm ( 266.6rps). Do you have any suggestion or comments for 12bit or 14 bit resolution that more suitable for this specification?  It looks max rps of 12 bit and 14 bit should meet 266.6 rps. Thank you. 

 

Xtal:8.192Mhz

Pole pair: 4

Speed: 16000rpm (266.6rps)

       

BR

Patrick

Parents
  • +1
    •  Analog Employees 
    on Oct 26, 2020 11:12 AM 2 months ago

    Patrick,

    Can you comment on if the speed quoted already accounts for the speed multiplier of the pole pair (electrical speed) or if it is the mechanical speed of the monitored shaft?  Also is there a requirement for overspeed indication?

    Thanks  

    Sean

  • Hello Sean

                   The speed ex 16000rpm should be mechanical speed. Customer's motor is 4 Pole-Pairs. the resolver is 2 Pole-Pairs. So at motor run  a cycle, we should get SIN/COS speed become double, is it correct? Please refer to below waveform. above pic is  4 Pole-Pairs, below pic is 2 Pole Pairs. 

                    if correct, the motor run one cycle, the resolver get speed from 16000 rpm to 32000 rpm. If consider resolution setting, we need to depend 32000 rpm for our resolution setting, right? 

                     It is a little urgent, so need your help to clarify above questions, Thank you. 

    BR
    Patrick

  • Hello Sean

                  1. Customer's max speed looks 64000RPM. But encoder read speed can not meet 64000 RMP, right? Has any suggestion for encoder ex : has feature to divide max 64000RPM....

                  2. While measure 160000 RPM via encoder interface, There are different  PWM width as below waveform, Is it normal? What is the root cause for this phenomenon? 

                      3. The encoder description looks less on datasheet. What is max RPM support by encoder? It looks has only resolution for setting, right? If any document of encoder description, it will be better. Thank you. 

    BR

    Patrick 

  • Hello Sean

                 Do you have update for above question? Thank you. 

    BR

    Patrick

  • +1
    •  Analog Employees 
    on Nov 17, 2020 12:58 PM 2 months ago in reply to patrickchen@morrihan.com
      1. Customer's max speed looks 64000RPM. But encoder read speed can not meet 64000 RMP, right? Has any suggestion for encoder ex : has feature to divide max 64000RPM....

    Patrick you have two choices with respect to the encoder output to extend the range.  Firstly if you have already increased the master clock rate of the device then the max rotational frequency also increases proportional to that change as it does in the position/velocity reading case.   Second, you could alternatively change the resolution to 10-bit mode and extend the maximum rotational velocity through the mode change.

        2. While measure 160000 RPM via encoder interface, There are different  PWM width as below waveform, Is it normal? What is the root cause for this phenomenon? 

    This appears to be related to velocity ripple in your system configuration.

                      3. The encoder description looks less on datasheet. What is max RPM support by encoder? It looks has only resolution for setting, right? If any document of encoder description, it will be better. Thank you. 

    The encoder description is very sparse in the datasheet but you can assume the same dynamics for all resolution modes as with the primary data-path as they share the same source.  We are actually in the process of reviewing our training collateral for this product family and this will be valuable feedback to help us improve the support for this product.

  • Hello Sean

                For velocity ripple issue to cause encoder different pulse width, customer testing it on Hill and environment should be clean. . But while above 40000RPM speed, encoder signal will happen this issue. Do you have any suggestion for it? Thank you.  

    Speed: 40000RPM

    Ch2: AD2S1210  Sin

    Ch3: AD2S1210 Encoder A

    BR

    Patrick

  • +1
    •  Analog Employees 
    on Nov 20, 2020 12:59 PM 2 months ago in reply to patrickchen@morrihan.com

    Patrick,

    Please let me clarify that I was not suggesting the velocity ripple was generated outside the chip.  Instead there is a specified amount of ripple that will exist in the application as a function of incomplete rejection of the carrier through the tracking loop.  This error is specified in the datasheet in the Velocity Accuracy section (see note 4).

    Sean

Reply Children