SPRAD58B September   2022  – February 2026 AM2631 , AM2631-Q1 , AM2632 , AM2632-Q1 , AM2634 , AM2634-Q1 , UCC14130-Q1 , UCC14131-Q1 , UCC14140-Q1 , UCC14141-Q1 , UCC14240-Q1 , UCC14241-Q1 , UCC14340-Q1 , UCC14341-Q1 , UCC15240-Q1 , UCC15241-Q1 , UCC5870-Q1 , UCC5871-Q1 , UCC5880-Q1 , UCC5881-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1 Introduction
  5. 2 Architectures and Trends
    1. 2.1 Two-Level and Three-Level Inverters
    2. 2.2 E-Axles and X-in-1 Architecture
    3. 2.3 Other Trends in Traction Inverter Design
  6. 3 Key Technology to Enable Traction Inverters
  7. 4 Microcontroller and Power Management IC
    1. 4.1 C2000™ Family
    2. 4.2 Power Management IC
  8. 5 Isolated Gate Drivers
  9. 6 Low Voltage Isolated Bias Supply
  10. 7 High Voltage Isolated Bias Supply
  11. 8 DC Link Active Discharge
  12. 9 Motor Position Sensing
  13. 10Isolated Voltage and Current Sensing
    1. 10.1 Isolated Current Sensing
    2. 10.2 Isolated Voltage Sensing
  14. 11System Engineering and Reference Designs
  15. 12Conclusion
  16. 13References

2 Architectures and Trends

The architecture of a traction inverter varies with vehicle type. Plug-in hybrid electric vehicles (PHEVs) and battery electric vehicles (BEVs) have a three-phase voltage source traction inverter topology to drive the car, with power levels in the 100kW to 500kW range. While the single axle drive is the standard option here (front or rear), adding a second traction inverter + eMotor on the second axle is a popular option to create a so called dual-motor architecture. Additionally, in PHEVs, the integrated starter generator (ISG) used to start the combustion engine, or sometimes even to drive the car, features another inverter structure.

In between the battery pack and traction inverter, a DC link capacitor is placed to supply the inverter with a controlled DC voltage. The capacitor provides a low impedance path for high frequency currents while providing energy storage that maintains a low ripple voltage. This DC link capacitor must be discharged quickly in case of a shutdown, malfunction, or accident for first-responders to be able to handle the car safely, which leads to one of the central features of a traction inverter, the DC link active discharge.

In some cases, a DC-DC boost converter can be used to step up the battery voltage before leading into the DC link capacitor. This is the case for vehicles with low battery voltage levels, primarily in hybrid electric vehicles. Providing the power output for the traction inverter on such a low voltage (100+V) results in high currents through the wiring, which can be reduced by increasing the voltage level to 400+V at the output of the DC-DC boost converter. Additionally, a DC-DC boost converter stabilizes the DC link voltage and enables a scalable battery architecture. However, the converter can potentially add cost, size, and weight to the system and introduce conversion losses.