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

3.3.3 Unidirectional Motor Drive Detecting Backward Spin

For applications that require spinning the motor in a specific direction, prioritize knowing if the motor is coasting or spinning in the direction opposite to the intended direction of spin. MCF8315A reverse drive function acts to reverse decelerate the motor through zero speed and to accelerate after changing direction until the motor transitions into closed loop as shown in Figure 3-7.

GUID-0FAA3D6E-0BC5-4B02-8478-0975BAB2C07A-low.gifFigure 3-7 Reverse Drive Function

MCF8315A provides an option to apply brakes and stop the motor while the motor is coasting or spinning in reverse direction and then accelerate into closed loop after changing the direction.

In applications such as ceiling fans and pumps, the requirement is to spin the motor in specific direction for desired results. For such applications, the reccomendation is to follow the below recommendations.

Step 1: Enable ISD [ISD_EN]

Step 2: Enable Motor ISD Reverse drive [RVS_DR_EN]

Step 3: Enable reverse resynchronization [RESYNC_EN]

Step 4: Enable Active brake reverse drive [ACTIVE_BRAKE_REV_DRV_EN]

Step 5: Enter the Kp coefficient [ACTIVE_BRAKE_KP] and Ki coefficient [ACTIVE_BRAKE_KI] for Active braking loop. We recommend to start with Kp coefficient [ACTIVE_BRAKE_KP] as 700 and Ki coefficient [ACTIVE_BRAKE_KI] as 100.

Step 6: Set bus current limit during active braking [ACTIVE_BRAKE_CURRENT_LIMIT]

Note:

Follow the below recommendations if the motor fails to resynchronize in reverse direction.

  1. Increase the reverse deceleration speed threshold to transition to open loop

  2. Enable Open loop reverse drive configuration [REV_DRV_CONFIG]

  3. Increase the Reverse Drive Open Loop Current Reference [REV_DRV_OPEN_LOOP_CURRENT]

  4. Decrease open loop acceleration coefficient A1 and A2 during reverse drive

  5. If the device triggers Lock current limit [LOCK_LIMIT], then increase the open loop current limit during speed reversal [REV_DRV_OPEN_LOOP_CURRENT]