SLLU374 November   2024 MCF8329A

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Hardware Design and Setup
    1. 2.1 Board Design
      1. 2.1.1 External MOSFET Selection
      2. 2.1.2 Gate Resistor Selection
      3. 2.1.3 Bootstrap and GVDD Capacitor Selection
      4. 2.1.4 Current Shunt Resistor Selection
      5. 2.1.5 VREG MOSFET Selection
      6. 2.1.6 Additional External Power Stage Components
  6. 3Connecting to the GUI
  7. 4Spinning Into Closed Loop
    1. 4.1 Essential Configuration
      1. 4.1.1 Loading Recommended Default Values
      2. 4.1.2 Setting Base Current
      3. 4.1.3 Setting Current Limits
      4. 4.1.4 Setting Voltage Limits
      5. 4.1.5 Input the Motor's Phase Resistance and Inductance
      6. 4.1.6 Maximum Electrical Speed (Hz)
      7. 4.1.7 Run MPET to Identify Motor Parameters
        1. 4.1.7.1 Skipping MPET Measurements
    2. 4.2 Testing for Successful Startup Into Closed Loop
  8. 5Basic Controls
    1. 5.1 Speed Input Mode
    2. 5.2 Preventing Back Spin of Rotor During Startup
    3. 5.3 Faster Startup Timing
    4. 5.4 Improving Speed Regulation
    5. 5.5 Limiting and Regulating Supply Power
    6. 5.6 MTPA Tuning
    7. 5.7 Motor Studio Optimization Wizards
  9. 6Fault Handling
    1. 6.1 MPET BEMF FAULT [MPET_BEMF_FAULT]
    2. 6.2 Abnormal BEMF Fault [ABN_BEMF]
    3. 6.3 Lock Current Limit [LOCK_LIMIT]
    4. 6.4 Hardware Lock Current Limit [HW_LOCK_LIMIT]
    5. 6.5 No Motor Fault [NO_MTR]
    6. 6.6 Abnormal Speed [ABN_SPEED]

5.4 Improving Speed Regulation

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 MCF8329A or tuned manually.

Auto Tuning: MCF8329A auto calculates the Speed loop PI controller gains when [SPD_LOOP_KP] and [SPD_LOOP_KI] are set to zero.

Manual Tuning: Use the following steps to tune Speed loop PI controller gains manually:

  1. Set the control mode [CTRL_MODE] to modulation index control (11b).
  2. Issue non-zero speed command to start the motor (refer to Section 4.2, step 1 on how to issue non-zero speed command). Motor will spin in open loop.
  3. Allow the open loop current to settle down and then measure the peak open loop current.
  4. Stop the motor and set the control mode [CTRL_MODE] to current control.
  5. Slowly increase the speed command until the motor speed reaches the max speed. Note down the Iq_ref value being reported in the IQ_REF_CLOSED_LOOP register.
  6. Speed loop Kp [SPD_LOOP_KP] is calculated using Equation 2.
    Equation 2. S p e e d   l o o p   K p   =   I q   r e f e r e n c e   a t   m a x i m u m   s p e e d M a x i m u m   E l e c t r i c a l   S p e e d   i n   H z  
  7. Speed loop Ki [SPD_LOOP_KI] is calculated using Equation 3.
    Equation 3. S p e e d   l o o p   K i = 0.1   × S p e e d   l o o p   K p
  8. Stop the motor and set the control mode [CTRL_MODE] to speed control.
Note: 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.