A new inductive sensor IC claiming to be intrinsically immune to stray magnetic fields aims to serve e-motor control, e-brake booster, and e-power steering applications. The inductive interface IC enables high-speed resolver, which minimizes electronic control unit (ECU) effort to ensure higher accuracy under extreme mechanical and electrical conditions.
Figure 1 The inductive sensor is intended for use in EV motors, brakes, and steering. Source: Melexis
The MLX90510 sensor offers accuracy of <+/-0.36° for up to 240,000 e-rpm, which is highly suitable for electric powertrain that requires the synchronization of the stator supply currents with the rotor position. The sensor IC is designed for high-speed sensing applications with high accuracy, EMC, and safety requirements.
The on-chip offset and propagation delay compensation provide accurate stray field immune position sensing at speeds of up to 240,000 e-rpm. The input offset compensation and zero output-angle position adjustment are performed within the IC, which lowers the ECU workload. Moreover, decoupling between the input and output boosts the EMC performance.
The inductive sensing IC—employing Melexis’ tracking loop technology—offers differential sine and cosine analog outputs and is based on digital architecture and rugged design. It trims system propagation delay to 0 ns with a maximum of +/-120 ns residual variations over the entire operating temperature range.
Figure 2 A set of PCB coils supported by the inductive sensor facilitates scalable designs. Source: Melexis
The inductive sensor IC works in combination with a set of PCB-based coils so that it can be adapted to the number of pole pairs of the motor (Figure 2). Next, it supports multiple sensing modes for both on-axis (end-of-shaft) and off-axis (side-of-shaft or through-shaft) operation, which helps the IC maximize flexibility in inductive coil designs to serve the most demanding mechanical constraints.
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