Microchip Technology has recently launched an IC that has been specifically designed for EV motor control applications called the LX34070. The IC includes a fast sample rate and differential outputs, it also incorporates features that make it functional-safety-ready for ISO 26262 compliance in the Automotive Safety Integrity Level–C (ASIL–C) classification.
“The LX34070 inductive position sensor enables lighter, smaller, more reliable motor control solutions that meet stringent safety requirements, reduce overall system costs, and can operate seamlessly and precisely in the noisy environment of an automobile’s DC motors, high currents and solenoids,” said Fanie Duvenhage, vice president of Microchip’s mixed signal and linear analog business unit. “Designers can use the LX34070 to further streamline EV motor control designs by pairing it with other functional-safety-ready Microchip devices including our 8-bit AVR® and PIC® microcontrollers, our 32-bit microcontrollers, and our dsPIC® digital signal controllers.”
The company claims that compared to the commonly used magnetic resolver and Linear Voltage Differential Transducers (LVDTs), the LX34070, which is an inductive position sensor solution offers numerous advantages. Furthermore, it is significantly cheaper than the other 2 techniques. It utilizes PCB traces, unlike the transformer-based magnetic windings and coil structures, the LX34070 device has negligible size and mass compared to alternatives that weigh as much as a pound. The IC also offers better accuracy as it does not depend on magnet strength, and the device improves robustness by actively rejecting stray magnetic fields. These features allows designer to have better control and gives them greater flexibility over where they can place the thin, lightweight PCB-based LX34070 solution in their EV motor control designs.
The working is based on the principle of electromagnetic induction, the PCB-based inductive position sensors use a primary coil to generate an AC magnetic field that couples with two secondary coils. A small metal target object disturbs the magnetic field so that each secondary coil receives a different voltage whose ratio is used to calculate absolute position.