hero home image description

Automotive - Traction Inverters for Electric Vehicles

Traction Inverters for Hybrid and Electric Vehicles

Traction inverters convert dc power from an on-board high voltage (HV) battery into ac power to drive the main motor or motors of an electric vehicle. In addition, traction inverters perform functions such as voltage boosting, switch protection and regenerative braking. All of these functions require galvanic isolation to separate control systems from high voltage domains.
sunset car tire traction
  • Industry leading isolation solutions for traction inverters

​Why Isolation is Critical in Traction Inverters

Electric Vehicles (EVs) and Hybrid Electric Vehicles (HEVs) require a traction inverter to convert dc energy from the high-voltage battery or dc link bus to the three-phase ac energy used to drive the traction motor. Traction inverters are typically capable of transferring power in the 20 to 100 kW range, with switching voltages in the 200 V to 800 V range and currents in the hundreds of amperes.

The entire system can be monitored and controlled via an automotive bus such as CAN (“Comm” in the diagram below). The CAN bus is isolated with digital isolators like Si86xx and digital isolators with integrated dc-dc power converters like Si88xx.

The traction inverter function is accomplished using six switches: one high-side and one low-side switch for each phase. Isolation separates the controller domain from the high-voltage ac domain. The gate drive for these switches uses isolated gate drivers, such as Si8239x, Si823x, Si823Hx, Si827x., and Si828x. The output side of the isolated gate drivers require a supply (typically 15 to 30 Vdc for IGBTs) that is isolated from the low-voltage domain and can be provided by the built-in dc-dc converter in the Si828x driver family.

​ 

Getting optimal efficiency from the system may require peak ac voltages that exceed the vehicle’s HV battery voltage, so traction inverters are often preceded by a bidirectional dc-dc boost converter. This boost converter often contains two switches that require isolated gate drivers. The system voltages can be sensed before the booster and traction inverter and a measurement taken with a isolated sensor (“Sns” in the diagram below).

HEVs also include a generator that converts mechanical energy from the internal combustion engine (ICE) into electrical energy to recharge the battery when the ICE is running. A block diagram for the generator’s ac-dc converter looks the same as the traction inverter, with the motor (“M” in the diagram below) replaced with a generator and the power flowing from generator towards the HV battery. Isolated gate drivers are needed to drive the switches.

Block Diagram

 
  • Featured Products
  • Si86xx
  • Digital Isolators
  • Automotive Digital Isolator
  • Si88xx
  • Digital Isolators
  • Automotive Dig Isolator w/ Integrated dc dc
  • Si823Hx
  • Isolated Gate Drivers
  • Automotive 2.5 kV Dual Drivers
  • Si827x
  • Isolated Gate Drivers
  • Automotive Hi CMTI Single Isolated Driver
  • Si828x
  • Isolated Gate Drivers
  • Automotive Isolated Gate Drivers
  • Si8239x
  • Isolated Gate Drivers
  • Automotive Dual Iso Gate Driver
  • Si892x
  • Isolated Analog and ADCs
  • Automotive Isolated Analog Amplifier
  • Tools
  • Ask a Question
  • Consult with experts and engineers for help on your project.
  • blue arrow
  • Technical Documents
  • Explore application notes, block diagrams, data sheets, user guides, ADS model calculators, installation references, S parameters and more.
  • blue arrow
  • Product Lifecycle Status Lookup
  • Lookup the product lifecycle status of Skyworks part number
  • blue arrow
  • Green / Pb-Free Certificate
  • Look up product's green / pb-free status and download the Certificate of Conformance.
  • blue arrow
Female electronic engineer working on electrical components in the laboratory