SLLU364 may   2023 MCT8315A

 

  1.   1
  2.   Abstract
  3. 1Revision History
  4.   Trademarks
  5. 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
  6. 3Essential Controls
    1. 3.1 Recommended Default Values based on application
    2. 3.2 Device and Pin Configuration
      1. 3.2.1 Speed input mode
    3. 3.3 Algorithm configuration – Motor speed
      1. 3.3.1 Maximum motor electrical speed (Hz)
    4. 3.4 Control Configuration
      1. 3.4.1 Cycle by cycle current limit (ILIMIT)
    5. 3.5 Testing for successful startup into closed loop
    6. 3.6 Fault handling
      1. 3.6.1 Abnormal Speed [ABN_SPEED]
      2. 3.6.2 Loss of Sync [LOSS_OF_SYNC]
      3. 3.6.3 No Motor Fault [NO_MTR]
      4. 3.6.4 Cycle by cycle current limit [CBC_ILIMIT]
  7. 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 Monitoring power supply voltage fluctuations for normal motor operation
    3. 4.3 Control configurations
      1. 4.3.1  Initial speed detection of the motor for reliable motor resynchronization
      2. 4.3.2  Unidirectional motor drive detecting backward spin
      3. 4.3.3  Preventing back spin of rotor during startup
      4. 4.3.4  Faster startup timing
      5. 4.3.5  Improving speed regulation
      6. 4.3.6  Stopping motor quickly
      7. 4.3.7  Faster deceleration
      8. 4.3.8  Preventing supply voltage overshoot during motor stop and deceleration
      9. 4.3.9  Protecting against rotor lock or stall condition
      10. 4.3.10 Maximizing thermal efficiency and increasing thermal performance
      11. 4.3.11 Mitigating Electromagnetic Interference (EMI)
      12. 4.3.12 Improving Motor efficiency
      13. 4.3.13 Limiting and regulating supply power

4.3.13 Limiting and regulating supply power

MCT8315A provides options to limit and regulate supply power. This feature can be utilized in battery powered motor driver applications such as cordless vacuum cleaners, power tools etc.

Follow below steps to limit supply power. In this mode, supply power is only limited to reference power and not actively regulated.

Step 1: Configure CONST_POWER_MODE to "Power limit control".

Step 2: Configure MAX_POWER. This sets the maximum power that MCT8315A can draw from the DC input supply at 100% duty command.

Step 3: Configure CONST_POWER_LIMIT_HYST. This sets the hysteresis band for the power reference. For example, if MAX_POWER is set to 25 W and device draws 25 W at 100% duty command and CONST_POWER_LIMIT_HYST is set to 5%, input power is limited to 25 W at 95% speed command.

CONST_POWER_LIMIT_HYST can be configured in applications where there are oscillations in speed around MAX_POWER. If speed oscillation is observed, the reccomendation is to increase the CONST_POWER_LIMIT_HYST.

Step 4: MCT8315A uses the same PI controller parameters as in the speed loop mode. Kp and Ki coefficients are configured through SPD_POWER_KP and SPD_POWER_KI. Tuning SPD_POWER_KP and SPD_POWER_KI is experimental. The reccomendation is to manually tune both parameters till the desired results are achieved.

Follow below steps to regulate supply power. In this mode, supply power is always actively regulated.

Step 1: Configure CLOSED_LOOP_MODE to "Power loop".

Step 2: Configure CONST_POWER_MODE to "Closed loop power control".

Step 3: Configure MAX_POWER. This sets the maximum power that MCT8315A can draw from the DC input supply at 100% duty command.

For example, if MAX_POWER is configured to 25 W, MCT8315A draws 12.5 W from power supply at 50% duty command.

Step 4: MCT8315A uses the same PI controller parameters as in the speed loop mode. Kp and Ki coefficients are configured through SPD_POWER_KP and SPD_POWER_KI. Tuning SPD_POWER_KP and SPD_POWER_KI is experimental. The reccomendation is to manually tune both parameters till the desired results are achieved.