The FOC Algorithm uses an integrated
speed/Power control loop that helps maintain a constant speed/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/power
loop is limited by configuring iLIMIT in the closedLoop1 configuration in the
Register Map page of GUI. When output of the speed/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 Closed loop Torque Mode by setting controlMode in closedLoop1 to
10b.
- Adjust the torque reference to
spin the motor at 50% of rated Speeds.
- The current feedback gradually
settles down to the set Iqref to run at the target speed.
- Speed loop Kp [SPD_LOOP_KP] is
calculated using this equation: SpeedLoop Kp =
Current Reference in Torque Mode / Operating Speed in
Hz
- Speed loop Ki [SPD_LOOP_KI] is
calculated using this equation: Speed Loop Ki =
Speed Loop Kp × 0.1
- If the Speed continously
fluctuates without settling, adjust the Current Loop Kp and Ki such that motor
settles to constant speed for a given torque reference.
Note: Once satisfactory Kp and Ki
are recorded switch to controlMode 0b to operate the motor in closed loop
speed control. 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 Guidelines to Change Controller Gains
| Parameter |
Rise
Time |
Overshoot |
Settling Time |
Stead State Error |
Stability |
| Kp |
Decreases |
Increases |
Small Change |
Decreases |
Degrades |
| Ki |
Decreases |
Increases |
Increases |
Eliminates |
Degrades |