Pulsating High Freq Observer

I am simulating the determination of the angle from standstill for an IPMSM (Interior Permanent Magnet Synchronous Motor), Part A: Find Best Possible Initial Estimation in this paper https://www.mathworks.com/help/mcb/ref/pulsatinghighfreqobserver.html#mw_01b83fb0-efb3-43b4-bade-ac475b2324b1_vh. It mentions selecting the θi_est angle corresponding to the maximum current iq among iq1, iq2, and iq3 for Part B. Why do they do that? Can someone explain it to me?

Answer 1

[Hassaan]

1. Vector Space: In an IPMSM, the stator currents and voltages can be represented in a vector space (commonly referred to as the d-q axis), which rotates with the rotor magnetic field. The q-axis (quadrature axis) current iq is directly related to the electromagnetic torque production in the motor.
2. Maximum Torque Response: By identifying the angle corresponding to the maximum iq, the method is effectively targeting the position where the injected high-frequency signal has the strongest interaction with the rotor's magnetic field. This position is likely to be where the high-frequency impedance is the lowest, which is useful for estimating the rotor position accurately.
3. Initial Position Estimation: At standstill or low speeds, the precise rotor position is not observable through back-EMF. The angle corresponding to the maximum iq provides a good initial estimate of the rotor position, which is essential for starting the motor smoothly without position sensors.
4. Estimation Improvement: Selecting the angle corresponding to the maximum iq helps improve the estimation of the rotor position when the motor is not moving. This estimate can then be used as a starting point for sensorless control algorithms as the motor speeds up and other methods (like back-EMF observation) become more effective.

Without having the full context or the complete document, this is a general explanation based on the principles of motor control and sensorless operation of IPMSMs.

------------------------------------------------------------------------------------------------------------------------------------------------

If you find the solution helpful and it resolves your issue, it would be greatly appreciated if you could accept the answer. Also, leaving an upvote and a comment are also wonderful ways to provide feedback.

Professional Interests

• Technical Services and Consulting
• Embedded Systems | Firmware Developement | Simulations
• Electrical and Electronics Engineering

[loc nv]

Thank you for your feedback.

However, your answer does not seem to be very relevant to the content of my question. I am looking to determine the angle of flux when the motor is at standstill. In this paper (https://www.mathworks.com/help/mcb/ref/pulsatinghighfreqobserver.html#mw_01b83fb0-efb3-43b4-bade-ac475b2324b1_vh), there is a method described for determining this. What I want to ask here is why, based on the maximum value of the three values lq1(iq1 = iq_peak for θi_est = 0), iq2(iq2 = iq_peak for θi_est = 2π/3), iq3(iq3 = iq_peak for θi_est = -2π/3), the value of θi_est (Initial estimation of rotor position can be 0, 2π/3, or -2π/3) can be determined.

Do you know why? Thanks.