IMPLEMENTATION OF FIELD-WEAKENING IN INTERIOR PERMANENT MAGNET MOTOR
Rafidah Alias, S. Khodijah, M. Syahril, Norkharziana Mohd Nayan University Malaysia Perlis School of Electrical System
[email protected]
Brushless DC (BLDC) Motor • Permanent magnet rotor with wound field stator • Brush → Electronic commutation • Hall sensor → Track rotor field •3 Phase →Y-windings / ∆-windings • BLDC BEMF → Trapezoidal / Sine
FIELD WEAKENING
Phase advance angle → phase current leads the angle of the phase back EMF
Transformer EMF in the phase voltage equation of BLDCM can restrain the increase of the phase BEMF
Figure 1 : Torque vs speed characteristics of conventional and phase advance method
BLDC → fixed commuta on (6 step) → hall sensor Physical hall sensor phase advancement (locked) BEMF zero crossing
PHASE ADVANCE
Figure 2 : PSIM simulation for phase advance BLDC
Simulated using PSIM Automatic switching (phase advance) Switching is accomplished by determining the switching speed
PHASE ADVANCE
Figure 3 : Torque speed characteristics for phase advance angles
OPTIMUM POINT TORQUE 2
1.5
1
35
0.5
Intersection (optimum)
20 0
0 4
6 RPM (K )
Figure 4 : Zoom in of torque speed characteristics
8
35 phase advance provide the most improvement Optimum point for 35 phase advance angle at 4700 rpm
OPTIMUM POINT SWITCHING TORQUE 2
Integration of phase advance method speed above 4700 rpm
35 phase advance
1.5
1
Torque vs speed curve characteristics improve:
0.5
Max speed (+500 rpm)
No phase advance
0 4
6 RPM (K )
Figure 5 : Full torque speed characteristics with phase advance switching
8
CONCLUSION
Phase advance optimum point switching → increase performance for speed above
optimum point → extended motor speed range and torque speed curve
Ongoing development → real me phase advance angle increment
driving system
END Thank You
