SLVAES1A June   2020  – May 2022 DRV8300

 

  1.   Trademarks
  2. 1Motor Considerations and Why Brushless DC Motors?
  3. 2Motor Driver Architecture
    1. 2.1 Gate Driver vs Integrated FET Driver: Power, Voltage, and Current Requirements
    2. 2.2 Three Use Cases: Speed, Torque, or Position:
    3. 2.3 Control Methods: Trap, Sine, or FOC
      1. 2.3.1 Trapezoidal
      2. 2.3.2 Sinusoidal
      3. 2.3.3 Field-Oriented Control
    4. 2.4 Sensored Versus Sensorless
      1. 2.4.1 Sensored
      2. 2.4.2 Sensorless
    5. 2.5 Current Sense Amplifiers
    6. 2.6 Interface
    7. 2.7 Power Integration
    8. 2.8 100% Duty Cycle Support
  4. 3Texas Instruments' Brushless-DC Motor Drivers
    1. 3.1 Gate Drivers: DRV8x and DRV3x family
      1. 3.1.1 DRV8x Family
      2. 3.1.2 DRV3x Family
    2. 3.2 Integrated MOSFET: DRV831x Family
    3. 3.3 Control and Gate Driver: MCx Family
    4. 3.4 Full Integration: MCx831x and DRV10x Family
      1. 3.4.1 MCx831x Family
      2. 3.4.2 DRV10x family
  5. 4Conclusion
  6. 5Revision History

3.3 Control and Gate Driver: MCx Family

Figure 3-6 Control and Gate Driver Architecture for MCx Families

TI’s MCx family of control & gate drivers integrates control functionality into the driver for a device that can spin the motor without MCU assistance. Integrated control allows for code-free trapezoidal and field-oriented control via programmable EEPROM and configuring settings over a I2C or hardware interface. Control and gate driver devices are intended for >70W motor drive systems to provide a smaller BOM size for systems that traditionally use an external MCU for traditional motor control. These devices require external N-type power MOSFETs and 1 or more current sense resistor(s) for accurate trapezoidal or Field-oriented control.

The controller in MCx devices allows for speed control through an analog input, PWM input with varying duty cycle and frequency, or speed command. The MCx family of devices can come in I2C, SPI, or hardware interfaces to support a variety of low-cost MCUs for configuration. There is configurability for all stages of motor control, including pre-startup, startup, open-loop, closed-loop, and motor stop. To assist with configuring settings, GUIs and tuning guides are available for evaluation.

MCF (integrated Field-oriented control) devices offer a variety of unique features. The Motor Parameter Extraction Tool (MPET) automatically performs motor identification to determine electrical parameters such as motor resistance, inductance, and flux, and mechanical parameters such as moment of inertia and coefficient of friction. Additionally, MCF devices auto-tunes PI controller gains using the identified mechanical and electrical parameters to achieve speed and torque regulation and stability.

MCT (integrated trapezoidal control) devices support up to 3 kHz electrical frequency and have less than 50 ms of startup and 150 ms of deceleration time. The control algorithm supports 120° and 150° current modulation to improve acoustic performance and includes lead angle adjustment to optimize the motor efficiency. Additionally, MCT devices includes an Active Demagnetization feature to reduce power losses from low-inductance motors.

Table 3-1 Highlighted Control Features in MCF and MCT Devices
MCF Devices (integrated Field-oriented control) MCT Devices (integrated trapezoidal control)
Offline motor parameters measurement with Motor Parameter Extraction Tool (MPET) Supports up to 3 kHz electrical frequency
5-point configurable speed profile support Very fast startup time (< 50 ms)
Improved acoustic performance with automatic dead time compensation Fast Deceleration (< 150 ms)
Speed Loop with accuracy of 3% with internal clock and 1% with external clock reference at room temperature Supports 120° or 150° modulation to improve acoustic performance
Auto-tuned torque and speed PI controller gains Active Demagnetization to reduce power losses
Spread spectrum and slew rate for EMI mitigation Lead angle adjust to optimize efficiency

MCx device features include driver fault protections such as overtemperature, overvoltage, undervoltage, overcurrent, cycle-by-cycle current limit, etc. There are also controller fault protections for IPD, MPET, abnormal speed/BEMF, motor lock, speed/torque saturation, etc. Finally, MCx devices may include power integration options such as an LDO, adjustable buck regulator, and integrated bootstrap with trickle charge pump architecture for high-side MOSFET enhancement.