The FOC Algorithm uses an integrated
speed control loop /Power Control Loop that helps maintain a constant speed/
Constant power over varying operating conditions. The Kp and Ki coefficients are
configured through speedLoopKp and speedLoopKi in the "System
Configurations" section on the Motor Tuning page. The output of the speed
loop / power Loop is used to generate the current reference for torque control. The
output of the speed loop /power Loop is limited by configuring iLIMIT in the
closedLoop1 configuration in the Register Map page of GUI. When output of the speed
loop / Power Loop saturates, the integrator is disabled to prevent integral
wind-up.
To tune the Kp and Ki values for speed
loop:
- Configure the motor to spin
continuously in open loop by setting closedloopDis to 1b. Disable the
automatic handoff by setting autoHandOffEn to 0b.
- Set the closed loop hand off
threshold to around 50% of maximum speed using olClHandOffThr.
- Set the iqRampEn bit to
1b in the userInputMotorStartUp1 register.
- The current reference gradually
decreases and settles down to the lowest possible Iqref to run at the given
threshold speed.
- Speed loop Kp [SPD_LOOP_KP] is
calculated using this equation: SpeedLoop Kp =
Current Reference at olClHandOffThr in Amps / olClHandOffThr in
Hz
- Speed loop Ki [SPD_LOOP_KI] is
calculated using this equation: Speed Loop Ki =
Speed Loop Kp × 0.1
- Enable closed loop by clearing
the closedloopDis to (0b) in the configuration in the Register Map page
of the GUI.
Note: The tuning of
speed loop Kp and Ki is experimental. If the above recommendation does not
work, manually tune speed loop Kp and Ki until the desired results are
achieved.
Table 6-1 shows general guidelines to change controller gains.
Table 6-1 Steady State and
Transient Response Trends With Increase in PI Loop Gain Coefficients
| Parameter |
Rise
Time |
Overshoot |
Settling Time |
Stead State Error |
Stability |
| Kp |
Decreases |
Increases |
Small Change |
Decreases |
Degrades |
| Ki |
Decreases |
Increases |
Increases |
Eliminates |
Degrades |