Week 09
Field Weakening
I use my PSIM report and PI calculation file to revisit the DC-motor model, cascaded current-speed loops, and field weakening.
What I connect in this unit
Up to base speed, flux can remain fixed while armature voltage raises speed; beyond that point, back EMF reaches the voltage limit. Field weakening reduces flux to permit higher speed, and with current limited the available torque falls toward a constant-power region.
Concept map
- Base speed
- Voltage limit
- Flux reduction
- Constant-power region
Technical anchor
Reducing Phi roughly inversely with speed keeps E = k_e Phi omega below V_max; then P = T omega remains approximately constant and torque falls with 1/omega.
How I review it
Plot current and voltage limits across speed, identify feasible torque below and above base speed, and include minimum-flux, overspeed, and commutation constraints.
Connection to the full course
Unit 9 of 12. Unit numbers follow the control structure in the saved design files and do not claim attendance weeks.