SLLU363 may   2023 MCF8315A

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
    1. 1.1 Hardware and GUI Setup
      1. 1.1.1 Jumper Configuration
      2. 1.1.2 External Connections
      3. 1.1.3 Connecting to the GUI
        1. 1.1.3.1 Connect to computer
        2. 1.1.3.2 Connect to the GUI
        3. 1.1.3.3 Verify Hardware Connection
  5. 2Essential Controls
    1. 2.1 Recommended Default Values
    2. 2.2 Device and Pin Configuration
      1. 2.2.1 Speed Input Mode
    3. 2.3 Control Configuration - Motor Parameters
      1. 2.3.1 Maximum Motor Electrical Speed (Hz)
    4. 2.4 Control configuration - Closed Loop
      1. 2.4.1 Current Limit for Torque PI Loop
    5. 2.5 Testing for Successful Startup into Closed Loop
    6. 2.6 Fault Handling
      1. 2.6.1 MPET IPD Fault [MPET_IPD_Fault]
      2. 2.6.2 MPET BEMF Fault [MPET_BEMF_Fault]
      3. 2.6.3 Abnormal BEMF Fault [ABN_BEMF]
      4. 2.6.4 Lock Current Limit [LOCK_LIMIT]
      5. 2.6.5 Hardware lock Current Limit [HW_LOCK_LIMIT]
      6. 2.6.6 No Motor Fault [NO_MTR]
  6. 3Basic Controls
    1. 3.1 Device and Pin Configuration
      1. 3.1.1 Power Saver or Sleep Mode for Battery Operated Applications
      2. 3.1.2 Direction and Brake Pin Override
    2. 3.2 System Level Configuration
      1. 3.2.1 Tracking Motor Speed Feedback in Real Time
      2. 3.2.2 Improving Acoustic Performance
      3. 3.2.3 Protecting the Power supply
      4. 3.2.4 Monitoring Power Supply Voltage Fluctuations for Normal Motor Operation
    3. 3.3 Control Configurations
      1. 3.3.1  Motor Parameter Estimation to Minimize Motor Parameter Variation Effects
      2. 3.3.2  Initial Speed Detection of the Motor for Reliable Motor Resynchronization
      3. 3.3.3  Unidirectional Motor Drive Detecting Backward Spin
      4. 3.3.4  Preventing Back Spin of Rotor During Startup
      5. 3.3.5  Faster Startup Timing
      6. 3.3.6  Gradual and Smooth Start up Motion
      7. 3.3.7  Improving Speed Regulation
      8. 3.3.8  Stopping Motor Quickly
      9. 3.3.9  Preventing Supply Voltage Overshoot During Motor Stop.
      10. 3.3.10 Protecting Against Rotor Lock or Stall Condition
      11. 3.3.11 Maximizing Thermal Efficiency and Increasing Thermal Performance
      12. 3.3.12 Mitigating Electromagnetic Interference (EMI)
      13. 3.3.13 Faster deceleration

3.2.1 Tracking Motor Speed Feedback in Real Time

MCF8315A device provides information about the motor speed through the frequency generator (FG) pin, which is also known as a TACH (tachometer) out. In MCF8315A, the FG pin behavior is configured through FG_CONFIG. Configure FG_SEL to output FG signal only in closed loop, both open loop and closed loop, or only in open loop for the first try. Configure FG_DIV to number of motor poles so that the FG output matches the motor mechanical speed in Hz.

When FG_CONFIG is configured to 0 (FG active as long as motor is driven), the FG output is active as long as MCF8315A is driving the motor. FG is not active during a motor stop and coasting condition. In this mode, FG is released high when MCF8315A enters sleep or standby mode. This mode is useful in applications that require real time motor speed information as long as MCF is driving the motor.

When FG_CONFIG is configured to 1 (FG active till BEMF drops below FG_BEMF_THR), MCF8315A provides FG output until BEMF falls below FG_BEMF_THR. The FG output continues to indicate motor speed even if the motor is not being actively driven. This mode is useful in applications that require motor speed information above a certain speed, and rotor motion information during the coast and braking conditions.

For example, if the motor Ke is 5 mV/Hz and the application require measuring motor speed above 4 Hz, then the user can configure FG_BEMF_THR to 20 mV. Once when the motor speed reaches 4 Hz, the device outputs FG as the BEMF voltage is at 20 mV at 4 Hz.