Inductive resolver simplifies automotive electrification

An inductive sensing IC developed by Melexis is intrinsically immune to stray magnetic fields. As a result, the MLX90510 inductive interface IC enables high-speed resolver minimising the ECU effort required to get best-in-class accuracy under extreme mechanical and electrical conditions, claims the company. The EMC capabilities make it particularly suited to e-motor control, e-brake booster and e-power steering applications.

This is the company’s first open market inductive sensor IC. The MLX90510 offers accuracy up to ±0.36 degrees at up to 240,000 e-rpm. It is designed for demanding high speed sensing applications which require high accuracy, EMC and safety requirements, for example e-motor (e-axle), e-brake booster and e-power steering applications.

“An efficient electric powertrain requires the synchronization of the stator supply currents with the rotor position,” explains Lorenzo Lugani, product manager for inductive sensors at Melexis. He says the MLX90510’s digital architecture and rugged design reduce the cost of the ECU module.

The MLX90510 offers differential Sine and Cosine analogue outputs and comprises Melexis’ patented tracking loop technology. This brings advantages such as system propagation delay trimmed to 0ns with a maximum of ±120ns residual variations over the entire operating temperature range. 

Another benefit is that the input offset compensation and zero output-angle position adjustment are performed within the IC, lowering the effort on the ECU.

The three-phase-based coil design simplifies linearity optimisation, while decoupling the input and output is claimed to enable “unprecedented EMC performances”. The inductive resolver also ensures stable output amplitudes independently from the air gap related input signal strength.

The MLX90510 has a linearisation feature with up to 16 calibration points to manage non-linearities of sensor modes, for example, side-of-shaft.

The MLX90510 works in combination with a set of PCB-based coils whose scalable design can be easily adapted to the number of pole-pairs of the motor. Supporting multiple sensing modes for both on-axis (end-of-shaft) and off-axis (side-of-shaft or through-shaft) operation, the IC has over-voltage and reverse polarity protection (±24V on the supply and ±18V on the outputs). 

The sensor is AEC-Q100-qualified for extended temperature operation from -40 to +160 degrees C. IT adheres to ISO 26262 ASIL C functional safety guidelines to support up to ASIL D system-level integration. 

The MLX90510 is supplied in a RoHS TSSOP-16 package. Samples are available upon request.

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