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

3.3.13 Faster deceleration

Decelerating the motor quickly requires motor mechanical energy to be extracted and disposed - input DC voltage increases if this energy is returned to the DC input supply. When active braking is enabled, energy taken from DC power supply is used to brake the motor - this prevents DC voltage spike during fast deceleration. The mechanical energy of the motor and energy taken from DC source, both are dissipated within the motor itself.

Follow below steps to decelerate the motor quickly.

Step 1: Enable active braking [ACTIVE_BRAKE_EN].

Step 2: Configure ACTIVE_BRAKE_CURRENT_LIMIT. This sets the maximum limit on the current sourced from the DC bus during active braking. Active brake current limit should be configured to a value lesser than the power supply current limit.

Step 3: Configure ACTIVE_BRAKE_BUS_CURRENT_SLEW_RATE. This sets the slew rate of the DC bus current starting from 0A to ACTIVE_BRAKE_CURRENT_LIMIT.

Step 4: Configure ACTIVE_BRAKE_MOD_INDEX_LIMIT. This sets the modulation index limit below which active braking will be applied. Above this modulation index, device will apply AVS if AVS is enabled. Setting a higher modulation index limit will decelerate the motor much faster.

Note:

Modulation index [VOLT_MAG] can be read back from ALGO_STATUS register.

Step 5: MCF8315A uses a PI controller to generate the D-axis reference current. Manually tune ACTIVE_BRAKE_KP and ACTIVE_BRAKE_KI if the active brake current looks unstable.