SLLU335A August   2021  – January 2022 MCF8316A

 

  1. 1Revision History
    1.     Trademarks
  2. 2Introduction
    1. 2.1 Hardware and GUI Setup
      1. 2.1.1 Jumper Configuration
      2. 2.1.2 External Connections
      3. 2.1.3 Connecting to the GUI
        1. 2.1.3.1 Connect to computer
        2. 2.1.3.2 Connect to the GUI
        3. 2.1.3.3 Verify Hardware Connection
  3. 3Essential Controls
    1. 3.1 Recommended Default Values
    2. 3.2 Device and Pin Configuration
      1. 3.2.1 Speed Input Mode
    3. 3.3 Control Configuration - Motor Parameters
      1. 3.3.1 Maximum Motor Electrical Speed (Hz)
    4. 3.4 Control configuration - Closed Loop
      1. 3.4.1 Current Limit for Torque PI Loop
    5. 3.5 Testing for Successful Startup into Closed Loop
    6. 3.6 Fault Handling
      1. 3.6.1 MPET IPD Fault [MPET_IPD_Fault]
      2. 3.6.2 MPET BEMF Fault [MPET_BEMF_Fault]
      3. 3.6.3 Abnormal BEMF Fault [ABN_BEMF]
      4. 3.6.4 Lock Current Limit [LOCK_LIMIT]
      5. 3.6.5 Hardware lock Current Limit [HW_LOCK_LIMIT]
      6. 3.6.6 No Motor Fault [NO_MTR]
  4. 4Basic Controls
    1. 4.1 Device and Pin Configuration
      1. 4.1.1 Power Saver or Sleep Mode for Battery Operated Applications
      2. 4.1.2 Direction and Brake Pin Override
    2. 4.2 System Level Configuration
      1. 4.2.1 Tracking Motor Speed Feedback in Real Time
      2. 4.2.2 Improving Acoustic Performance
      3. 4.2.3 Protecting the Power supply
      4. 4.2.4 Monitoring Power Supply Voltage Fluctuations for Normal Motor Operation
    3. 4.3 Control Configurations
      1. 4.3.1  Motor Parameter Estimation to Minimize Motor Parameter Variation Effects
      2. 4.3.2  Initial Speed Detection of the Motor for Reliable Motor Resynchronization
      3. 4.3.3  Unidirectional Motor Drive Detecting Backward Spin
      4. 4.3.4  Preventing Back Spin of Rotor During Startup
      5. 4.3.5  Faster Startup Timing
      6. 4.3.6  Gradual and Smooth Start up Motion
      7. 4.3.7  Improving Speed Regulation
      8. 4.3.8  Stopping Motor Quickly
      9. 4.3.9  Preventing Supply Voltage Overshoot During Motor Stop.
      10. 4.3.10 Protecting Against Rotor Lock or Stall Condition
      11. 4.3.11 Maximizing Thermal Efficiency and Increasing Thermal Performance
      12. 4.3.12 Mitigating Electromagnetic Interference (EMI)
      13. 4.3.13 Faster deceleration

3.6.2 MPET BEMF Fault [MPET_BEMF_Fault]

This fault gets triggered when motor stalls while running in open loop for BEMF estimation. If this fault is triggered, then please follow the below suggestions.

Step 1: Increase MPET Open loop current reference [MPET_OPEN_LOOP_CURR_REF]

Step 2: Decrease MPET open loop slew rate [MPET_OPEN_LOOP_SLEW_RATE]

Step 3: If this fault persists, check motor datasheet for motor BEMF constant in mV/Hz and program Motor BEMF Constant [MOTOR_BEMF_CONST] in the “Control configuration – Motor Parameters” tab in All tuning settings section in the GUI.

Equation 3 and Equation 4 can be used to convert Ke in mV/rpm and torque constant to Ke in mV/Hz.

Equation 3. BEMF Constant in mVHz=BEMF Constant mVrpm×60Pole pairs
Equation 4. BEMF constant mVHz=Torque constantmNmA× 2πPole pairs 

Step 4: If the motor does not have a datasheet, then measure the voltage across any two phases of the motor using an oscilloscope by manually spinning the motor. A sinusoidal or trapezoidal voltage should appear on the oscilloscope. Measure the peak voltage EPH in milli-volts and time period TE in seconds as shown in Figure 3-4. Calculate BEMF constant Ke as shown in Equation 5.

GUID-88F1F1D6-D559-4582-AF17-D3B3660A0E65-low.gifFigure 3-4 Motor BEMF Constant
Equation 5. BEMF Constant Ke=EPH×TE√3