SLUAAY2 December   2024 ISO5451 , ISO5451-Q1 , ISO5452 , ISO5452-Q1 , ISO5851 , ISO5851-Q1 , ISO5852S , ISO5852S-EP , ISO5852S-Q1 , UCC21710 , UCC21710-Q1 , UCC21717-Q1 , UCC21732 , UCC21732-Q1 , UCC21736-Q1 , UCC21737-Q1 , UCC21738-Q1 , UCC21739-Q1 , UCC21750 , UCC21750-Q1 , UCC21755-Q1 , UCC21756-Q1 , UCC21759-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1 Introduction
  5. 2 SiC and IGBT Characteristics
  6. 3 Failure Modes
  7. 4 Short-Circuit Protection Approaches
    1. 4.1 Short-Circuit Current-Based Protection Implementation
    2. 4.2 Short Circuit Voltage-Based Protection Implementation
  8. 5 DESAT Circuitry Design
    1. 5.1 DESAT Circuit Component Selection
    2. 5.2 Effect of Parasitic Elements
    3. 5.3 Effect of Rlim on DESAT Noise
  9. 6 Safe Shutdown
    1. 6.1 Safe Shutdown Mechanisms
    2. 6.2 Safe Shutdown Considerations
  10. 7 Short-Circuit Test Setup and Data
    1. 7.1 Short-Circuit Bench Measurement Setup
    2. 7.2 SC Board Setup for Data Collection
    3. 7.3 Different Circuit Configurations for SC Testing
    4. 7.4 Bench Measurement Results
    5. 7.5 Overall Summary of SiC vs IGBT Power Module SC Observation
  11. 8 Key Consideration in Designing SC Protection Circuit
  12. 9 Summary
  13. 10References

3 Failure Modes

In case of the IGBTs and SiC power modules, the common failure reasons are:

  • Dielectric break down failure
    • Both IGBTs and SiC have voltage limits at the Gate pin and the Drain/Collector pin with respect to the Source/Emitter, respectively. If the applied voltage to the power module exceeds the max supported voltage, it causes the power module to fail. So, the applied voltage and also system noise have to be controlled so that the voltage does not exceed the maximum supported Gate, Drain/Collector voltage of the power module.
  • Thermal runaway failure
    • Another common failure reason for the power module is thermal runaway. During high current operations, due to the internal resistance of the power module, the power module temperature increases. If the power module is placed in an extreme temperature environment or exceeds its maximum current limit continuously, thermal runaway failure may occur. So, the power module temperature needs to be controlled with an effective cooling mechanism and the operating current needs to be controlled to not exceed its rated operating current.
  • Over-current /short-circuit failure (SC)
    • Over-current and short-circuit failures are the common reasons for power module failure. In a multiphase system, there can be different types of Short-circuit failures and it can happen due to the reasons provided in Table 3-1.
Table 3-1 OC/SC Failure Conditions and the Failure Reasons
Failure Condition Reason for the Failure
Shoot-through on a phase Controller malfunction /noise interference
Phase to phase short circuit Insulation breakdown between the phases
Phase to earth short circuit Insulation breakdown between phase to casing

For the scope of the gate driver protection approach, focus on the following power module failure possibilities and how the gate driver can protect the power modules effectively.

  • Short-circuit/Over-current failure: due to noise/controller malfunction
  • Di-electric Over-voltage failure: during switching at high di/dt condition (mostly post SC Event)