Objectives of Paper:

  • Reduction of vibration
  • reduction of acoustic noise

Sensorless control of PMSM at low speed:

  • Motor is excited by fluctuating voltage carrier signal Vinj Cos(wt)
  • High frequency impedance is measured.
  • Excitation signal is injected in stationary reference frame
  • Based on inductance variation due to rotor saliency.

How is it Done:


Multi-Resolution Controller:

  • The use of wavelet transform
  • Error Signal decomposition

Parameters tuning:


Online optimization problem formulation:

Gains   are used to tune high and medium frequency components of the error signal

Online optimization problem formulation:

0.01< {Kd1, Kd2, Kd3} <10


How Jy is calculated?



Procedure of Optimization with hardware in the loop:


Optimization Results:

Experimental Results:

Speed controller response to a step change in the reference speed from 10 to 30 deg/sec

fig: Before optimization fig: After optimization


FFT Analysis of the Accelerometer Results:

fig: Axial vibration before optimization                          fig: Axial after optimization


Noise Measurements of the PM Motor using Axial & Radial Accelerometer:


Audible Noise Measurement:



  • Axial & Radial Vibration are reduced (up to 10%)
  • Steady state Error is reduced (up to 5%)
  • Smooth operation of the motor is obtained
  • Motor produces less amount of audible noise (up to 18%)