• State TI Thinks Resolved
  • Locked Locked
  • Replies 5 replies
  • Answers 3 answers
  • Subscribers 30 subscribers
  • Views 472 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LDC5072-Q1: Need clarification on the function of the part

Shanjai kanna s
Prodigy 190 points
Part Number: LDC5072-Q1

Dear Team,

We are using LDC5072-Q1 in motor inverter design. Since LDC5072-Q1 is external to the controller board, we are intended to add filter circuit for differential output sine and cosine signal. Assuming, we are using 5MHz of LC oscillator resonant frequency. Then, what will be the frequency of differential output sine and cosine signal from LDC5072-Q1?

  • 0
    TI__Mastermind 18545 points

    Hello, 

    The sine and cosine signals change with the angle of the motor rotation so the frequency will be dependent on your motor speed. You can design the additional filter based on the max motor speed in your system but keep in mind the number of complete sinusoidal cycles your coil/target design will give for one complete motor rotation. 

    Best Regards, 

    Justin Beigel

  • 0 in reply to Justin Beigel
    Prodigy 190 points

    Hello,

    The frequency of sine and cosine signals is f=N*p/120, isn't it?

    where, N=speed of motor in r.p.m, p=No. of poles of the motor

    Would you please confirm?

  • 0 in reply to Shanjai kanna s
    TI__Mastermind 18545 points

    Hello, 

    The sine and cosine are based on the number of electrical rotations seen by the LDC5072-Q1 so it depends more on the number of petals in your target shape than poles of the motor. 

    So if you just use petals of your target instead of poles in the motor, you will be good with your equation. 

    Best Regards,

    Justin Beigel

  • 0
    Prodigy 190 points

    Thanks for your update!

    Then, the frequency of sine and cosine signals is f=N*x/60,

    where, N=speed of motor in r.p.m, x=No. of poles target metal of IPS sensor

    Please confirm the above formula.

    And also, would you please explain any requirement to select the number of target metal of IPS sensor?

    Is number of target metal equal to number of pole pair of motor?

  • 0 in reply to Shanjai kanna s
    TI__Mastermind 18545 points

    Hello, 

    Yes, your formula is correct. 

    For choosing the number of petals on the target, if you increase the number of petals it increases the electrical rotations to mechanical rotations ratio which can give you more resolution on the mechanical angle. The number of petals does not have to match the number of pole pairs in the motor but it can if you want to design it that way. We have the LDC5072-Q1-SENSOR-DESIGN-TOOL along with the Sensor Design Tool Getting Started and Troubleshooting Guide that has lots of information about this topic. 

    Best Regards, 

    Justin Beigel