SLVAF66 June   2021 DRV3255-Q1 , DRV8300 , DRV8301 , DRV8302 , DRV8303 , DRV8304 , DRV8305 , DRV8305-Q1 , DRV8306 , DRV8307 , DRV8308 , DRV8320 , DRV8320R , DRV8323 , DRV8323R , DRV8340-Q1 , DRV8343-Q1 , DRV8350 , DRV8350F , DRV8350R , DRV8353 , DRV8353F , DRV8353R

 

  1. 1 Introduction to High-Power Motor Applications
    1. 1.1 Effects of a Poorly-Designed High-Power Motor Driver System
    2. 1.2 Example of the High-Power Design Process
  2. 2 Examining a High-Power Motor Drive System at a High Level
    1. 2.1 Anatomy of the Motor Drive Power Stage and How to Troubleshoot
    2. 2.2 Troubleshooting a High-Power System
  3. 3 High-Power Design Through MOSFETs and MOSFET Gate Current (IDRIVE)
    1. 3.1 MOSFET Gate Current
      1. 3.1.1 How Gate Current Causes Damage
      2. 3.1.2 Gate Resistors and Smart Gate Drive Technology
        1. 3.1.2.1 Gate Resistors
        2. 3.1.2.2 Smart Gate Drive and Internally-Controlled Sink and Source Gate Currents
        3. 3.1.2.3 Summary for Gate Resistors and Smart Gate Drive Technology
      3. 3.1.3 Example Gate Current Calculation for a Given FET
  4. 4 High-Power Design Through External Components
    1. 4.1 Bulk and Decoupling Capacitors
      1. 4.1.1 Note on Capacitor Voltage Ratings
    2. 4.2 RC Snubber Circuits
    3. 4.3 High-Side Drain to Low-Side Source Capacitor
    4. 4.4 Gate-to-GND Diodes
  5. 5 High-Power Design Through a Parallel MOSFET Power Stage
  6. 6 High-Power Design Through Protection
    1. 6.1 VDS and VGS Monitoring
      1. 6.1.1 Turning Off the FETs During an Overcurrent, Shoot-Through, or FET Shorting Event
    2. 6.2 Passive Gate-to-Source Pulldown Resistors
    3. 6.3 Power Supply Reverse Polarity or Power Supply Cutoff Protection
  7. 7 High-Power Design Through Motor Control Methods
    1. 7.1 Brake versus Coast
      1. 7.1.1 Algorithm-Based Solutions
      2. 7.1.2 External Circuit Solutions
      3. 7.1.3 Summary of Brake versus Coast
  8. 8 High-Power Design Through Layout
    1. 8.1 What is a Kelvin Connection?
    2. 8.2 General Layout Advice
  9. 9 Conclusion
  10. 10Acknowledgments

2.1 Anatomy of the Motor Drive Power Stage and How to Troubleshoot

Figure 2-1 High-Level Power Stage

Before developing troubleshooting guidelines, a library of external circuits, TI driver product features, or layout techniques, the typical gate driver system and its sub-functions must be understood.

Starting on the right side of Figure 2-1, one function of the motor driver power stage, otherwise known as inverter, phase, or half bridge, is to deliver current to the motor. Broken into its simplest parts, current flows from VDRAIN through the high-side FET and into the motor, assuming the low-side FET is off. Alternatively, if the low-side FET is on, and the high-side FET is off, current flows from the motor and through the low-side FET to GND. In the context of kilowatt motor drive application, up to hundreds of amps can flow through these FETs.

Moving to the left side of Figure 2-1, another function of the power stage is to translate the digital logic PWM input signals (for example, INHx and INLx) to signals at a higher analog voltage level, such as 24 V or 48 V. In this way, one part of the power stage is voltage translation from digital level signals to analog level signals. In addition, it is usually part of the functions of the motor driver to produce the voltage rails from the supplied motor driver supply voltage to translate the analog voltage levels. These analog voltages can be higher than VDRAIN, or the highest input voltage in the system. As such, linear regulators, charge pumps, or bootstrap architectures are used to achieve these voltages (for example, VCP and VGLS).

In the middle of Figure 2-1, another secondary function of the power stage is to condition or control the signals at the gates of the FET. Because MOSFETs can act as switches, resistors, or current sources depending on the gate voltage in relation to the drain and source voltages, all voltages of the FET must be controlled and monitored. Protection, signal conditioning techniques, and specialized circuits all fall under this function.

In summary, three functions of the motor drive power stage are:

  • Delivering current to the motor
  • Voltage translation from digital voltage levels to motor voltage level
  • Gate signal conditioning or protection