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

4.3.1 Motor Parameter Estimation to Minimize Motor Parameter Variation Effects

The MCF8316A uses motor resistance, motor inductance and the motor Back-EMF constant to estimate motor position in closed loop operation. The MCF8316A has capability of automatically measuring motor parameters in offline state, rather than having the user enter the values themselves. Offline measurement of parameters takes place before normal motor operation. Variation in motor parameters can impact the accuracy of motor position estimation and therefore the motor commutation and rotation. It is recommended to estimate the motor parameters before motor startup to minimize the impact caused due to possible parameter variations.

The MCF8316A has Motor parameter extraction tool (MPET) which estimates the motor phase resistance, the motor phase inductance and the motor Back-EMF constant. Go to “Control Configuration - Motor parameter extraction tool (MPET)”.

Step 1: Enable Measure motor resistance [MPET_R], Measure motor inductance [MPET_L] and Motor BEMF constant [MPET_Ke].

Step 2: Enable MPET Start command [MPET_CMD]. Make sure the motor is stationary before enabling MPET start command.

Step 3: After successful motor parameter extraction, copy the estimated parameters to the respective shadow registers by enabling MPET write to shadow register flag.

Note:

  1. If the device triggers MPED_IPD_FAULT, increase the MPET IPD Current threshold till the rated current of the motor.

  2. If the device triggers MPED_IPD_FAULT, decrease MPET Open loop slew rate [MPET_OPEN_LOOP_SLEW_RATE].

  3. If the fault still persists, increase MPET Open loop current reference [MPET_OPEN_LOOP_CURRENT_REF] and decrease MPET Open loop speed reference [MPET_OPEN_LOOP_SPEED_REF]

Figure 4-5 shows the phase current waveform during motor parameter measurement. Figure 4-6 shows the IPD current waveform during R, L and Ke measurement. Bottom half of Figure 4-6 shows the IPD current waveform during R and L measurement. R is measured during the rising of phase current and L is measured during the falling of phase current. After R and L measurement, motor spins in open loop. Once the speed reaches MPET open loop speed reference [MPET_OPEN_LOOP_SPEED_REF], motor is coasted. BEMF voltage of all three phases are measured and Ke is calculated.
Figure 4-5 MPET - Phase current
Figure 4-6 IPD current waveform during Rand L measurement