Automotive Traction Inverter Current Sensors: HAH3 & HST Series

Automotive traction inverters require precise current sensing on motor phases, DC links, and rotor windings to ensure efficient torque control and safe operation. This article presents LEM's HAH3 tri-phase Hall effect sensors (±200 A to ±1500 A) designed for IGBT and SiC inverter modules, and the HST series with integrated busbar for compact DC link measurement up to ±1500 A. With 3% global accuracy, 50 kHz bandwidth, and ratiometric output, these sensors address the challenges of compact inverter design, cross-talk immunity, and high dV/dt ruggedness in modern xEV powertrains.

Motor Control Architecture for Traction Inverters

LEM offers a wide range of current sensors with different form factors specifically designed for traction inverters, allowing current sensing on the motor phases, on the DC link of the battery, and even on the rotor winding in case an externally field excited motor replaces the permanent magnet.

All current sensors available are core-based Hall effect current sensors, with a large offering of form factors to enable high level of integration and easy assembly into the inverter.

Phase Motor Current Sensing Solutions

Phase measurement in motor control applications is essential for monitoring and adjusting the timing and synchronization of the motor’s phases, ensuring efficient operation and accurate control of speed and torque. For phase measurement, LEM recommends the HAH3 Series.

HAH3 Series — Tri-Phase Open Loop Hall Current Sensor

  • Three phase open loop automotive Hall current sensor
  • Available measuring ranges: 800 A, 900 A, 1000 A, 1100 A, 1200 A
  • 3% global accuracy over temperature and lifetime
  • 50 kHz bandwidth with 2 µs fast response time
  • Ratiometric output (shares ADC power supply)
  • Rugged against high dV/dt
  • Compact footprint for IGBT and SiC inverter power modules

HAH3 Key Benefits

  • Excellent accuracy and very good linearity
  • Very low thermal offset drift and sensitivity drift
  • High frequency bandwidth and very fast delay time
  • No insertion losses and excellent cross talk immunity

HAH3DR Variants for Inverter Integration

HAH3DR S07/SPx — For IGBT and SiC Inverter Modules

Designed to perfectly fit standard inverter modules such as Infineon’s Hybridpack™ Drive package and other pin-to-pin compatible modules. Features press-fit connection to the gate driver board.

HAH3DR S0x — For Various Busbar Configurations

The HAH3DR-S06, S0A, S0D, S0E, S03/SP4 allow current measurement on different busbar shapes, thicknesses, and pitches. They feature a cable connector for direct connection to a control board located further away from the inverter.

The HAH3DR S00/SP4 offers a through-hole connection to the gate driver board if located right on top of the sensor.

HST Series — DC Link Current Sensors

The DC link is crucial in motor control applications for current sensors as it provides a stable voltage reference, enabling accurate current measurement and efficient motor operation. The HSTDR Series with integrated busbar is ideal for DC Link measurement.

HST Series — Integrated Busbar Hall Effect Sensor

  • Measuring range up to ±1500 A
  • < 3.5% global accuracy over temperature and lifetime
  • 40 kHz bandwidth with 3 µs fast response time
  • Package size: only 29 × 21 × 12 mm, 27 g
  • 75% smaller than traditional C-core sensors
  • Integrated busbar for small footprint and high performance
  • Fully calibrated package (core + busbar + sensing element)

HST Design Advantages

  • Small airgap offers excellent protection against cross talk
  • Measures accurately up to 1500 A without saturation
  • Optimized footprint, weight, and cost
  • Measuring range increased +50% compared to HSNDR
  • Best in class accuracy for compact traction inverters

Typical Applications

  • Starter Generators
  • Traction Inverters
  • HEV (Hybrid Electric Vehicle) applications
  • EV (Electric Vehicle) applications
  • DC / DC converters

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