SLLU335A August 2021 – January 2022 MCF8316A
For applications that require better speed regulation, it is recommended to tune Speed loop PI controllers [SPD_LOOP_KP] and [SPD_LOOP_KI]. Kp coefficient of speed loop [SPD_LOOP_KP] controls the settling time and speed overshoots. Ki coefficient of Speed loop [SPD_LOOP_KI] controls speed overshoot and ensures regulation of speed at set value and drives the error to zero. Speed loop PI controller gains can either be auto-tuned by MCF8316A or tuned manually.
Auto Tuning: MCF8316A auto calculates Speed loop PI controller gains by setting [SPD_LOOP_KP] and [SPD_LOOP_KI] to zero.
Manual Tuning: Follow below steps to tune Speed loop PI controller gains manually
Step 1: Disable Speed loop [SPEED_LOOP_DIS]
Step 2: Disable closed loop [CLOSED_LOOP_DIS]
Step 3: Issue non-zero speed command to start the motor (refer to Section 3.5, step 1 on how to issue non-zero speed command). Motor will spin in open loop.
Step 4: Allow the open loop current to settle down and then measure the peak open loop current.
Step 5: Enter 110% of measured peak phase current as the Iq reference when speed loop is disabled [FORCE_IQ_REF_SPEED_LOOP_DIS]
Step 6: Enable closed loop [CLOSED_LOOP_DIS]. Now the motor will enter closed loop in torque mode.
Stp 7: Adjust the Iq reference [FORCE_IQ_REF_SPEED_LOOP_DIS] such that the motor speed reaches the maximum speed.
Step 8: Speed loop Kp [SPD_LOOP_KP] is calculated using Equation 6.
Step 9: Speed loop Ki [SPD_LOOP_KI] is calculated using equationEquation 7.
Step 10: Enable speed loop [SPEED_LOOP_DIS]
Tuning speed loop Kp and Ki is experimental. If the above recommendation doesn’t work, then we recommend to manually tune Speed loop Kp and Ki till the desired results are achieved.