SLYY235 June   2024 DRV7308

 

  1.   1
  2.   Overview
  3.   At a glance
  4.   How GaN increases inverter efficiency
  5.   Motor performance improvement with GaN power switches
  6.   Design considerations when using GaN in motor drives
  7.   Impact on system efficiency
  8.   Impact on audible noise
  9.   Conducted and radiated emission considerations
  10.   Impact on solution size
  11.   Protected and reliable system designs
  12.   Conclusion
  13.   Additional resources

Protected and reliable system designs

GaN needs faster and reliable overcurrent protection to eliminate saturation. Integrated protection eliminates the effect of parasitics and provides a faster response, on the order of a few hundreds of nanoseconds. The inverter and motor need overcurrent protection to eliminate thermal runaway during overload conditions.

230VAC line-powered motor drives can provide a rectified DC bus voltage of up to 450VDC, either from the voltage tolerance of the AC line or by using active power factor correction circuits. The inverters need to be designed for a 450V operating voltage. Some motor drives need to handle higher voltages for short durations in case the motor-generated back-electromotive force exceeds the supply voltage, or if there is inductive kickback. The inverters also may need to handle a higher off-state blocking voltage to prevent damage in the event of overvoltage scenarios such as input line-voltage surges or electric fast transient events.

The DRV7308 is designed with integrated drain-to-source voltage protection to protect the GaN FET during overcurrent events. It also has integrated overcurrent comparators for cycle-by-cycle current limiting, designed for a 450V operating voltage with a 650V off-state blocking voltage rating. Other protections monitor fault scenarios such as undervoltage, overcurrent and pin-to-pin short circuits.