SLVA654B June   2014  – March 2019 DRV8301 , DRV8301-Q1 , DRV8302 , DRV8303 , DRV8307 , DRV8308 , DRV8312 , DRV8323R , DRV8332

 

  1.   Hardware design considerations for an efficient vacuum cleaner using a BLDC motor
    1.     Trademarks
    2. 1  Suction Principle
    3. 2  Brushless DC Motors (BLDC)
      1. 2.1 Construction of BLDC Motors
      2. 2.2 Working of the BLDC Motor
        1. 2.2.1 Types of Control
          1. 2.2.1.1 Sensor Control
          2. 2.2.1.2 Sensorless Control
            1. 2.2.1.2.1 Sensorless Control: Using Zero Crossing of the Back EMF Signal
          3. 2.2.1.3 Calculations
    4. 3  Microcontrollers
    5. 4  Gate Driver and MOSFETs
    6. 5  Isolation
    7. 6  Power Management (6 to 60-V DC Power Supply)
    8. 7  CAP and QEP interfaces
    9. 8  Enhanced Controller Area Network (eCAN)
    10. 9  High-Resolution and Synchronized ADCs
    11. 10 DRV8323R
    12. 11 Feedback Stage
      1. 11.1 Torque or Commutation Loop
      2. 11.2 Speed Loop
      3. 11.3 Position Loops
    13. 12 Conclusion
    14. 13 About the Author
    15. 14 References
  2.   Revision History

11.1 Torque or Commutation Loop

The torque loop is used for sensorless applications to control the current through the motor. The torque is related to the current and therefore this feedback measures the current. A sense resistor measures the voltage and current sense amplifier senses the current and sends the signal to the ADC which digitizes the current and sends it to the controller. Measuring the motor current is often used as a safety feature. In case the motor is in a stalled position, the current increases dramatically. Because of this exceptional increase in current, the ADC values reach a current-limit level that causes the system to shut down.