IHS Markit forecasts that global revenue for the automotive magnetic sensors market will expand to $2.3 billion in 2030, more than double the $1.1 billion collected by the industry last year. The magnetic sensors space will benefit from a discernible acceleration in market demand as the effects of car electrification take hold.

In a 2001 paper, C.P.O Treutler from Bosch R&D outlined the key advantages of magnetic sensors: they allow contactless—and, consequently, wear-free measurement—of mechanical quantities such as angle of rotation and angular speed. They are also robust and inexpensive to manufacture.

The dominant magnetic sensor solution today remains the Hall effect IC, a technology that serves more than 60 applications in the passenger car. Hall-effect sensors and switches in 2017 accounted for 90% of the global revenue of magnetic sensors in automotive.

Hall sensors are notable for their robust performance, small size, and low cost. These devices can be deployed at high temperatures experienced under the hood and are compatible with CMOS electronics. While Hall devices measure their fields vertically, the trend has been to extend spatial resolution in the lateral directions using magnetic field “concentrators.” Such devices are dubbed 2D and 3D Hall ICs, and in many cases, are replacing linear Hall sensors and angle sensors, e.g., for chassis height measurements and electronic throttle control in the powertrain.

Increasingly, however, Hall is encountering competition from the magnetoresistive group of technologies, which include anisotropic magnetoresistive (AMR), giant magnetoresistive (GMR), and, more recently, tunneling magnetoresistive (TMR) device structures.

By and large, magnetoresistive technologies offer higher sensitivity, and major Hall Effect sensor suppliers such as Allegro Microsystems, Infineon, and NXP have also incorporated combinations of GMR, AMR, or TMR into their product offerings. And while making up just 10% of the global shipments of automotive magnetic sensors in 2017, magnetoresistive sensors accounted for a much larger share of revenue at 19% because of their initial higher cost compared to Hall ICs.

Magnetoresistive devices will be used mostly in sensing applications that value performance and safety-critical operations, such as those propelled by functional safety, especially in autonomous driving. Examples of these applications include wheel speed, throttle position, and steering.

With the electronics architectural landscape for vehicles changing dramatically in the next 15 years, automotive sensors are also undergoing their own evolution in response to new requirements on performance, safety, Big Data analysis, robustness, security, and economy.

The transformation in vehicle sensors can be attributed to two all-encompassing trends now sweeping the automotive space:

• The electrification of cars, specifically the propulsion unit; and

• The increasing progression of Advanced Driver Assistance Systems (ADAS) toward attaining the fully autonomous, self-driving vehicle.

The magnetic sensor industry will be a significant beneficiary of these new forces, says Dr. Richard Dixon, IHS Markit Senior Principal Analyst, MEMS & Sensors. As magnetic sensors become more intelligent with silicon-enabled functionality, their price will shift higher, largely because of their role in higher redundancy levels under ISO 262262 standards governing functional safety.

Compared to 2016 numbers, the additional value to suppliers resulting from the increasing value of magnetic sensors in key automotive systems will be as much as $340 million by 2022, IHS Markit calculates.

Automotive forecasts from IHS Markit also indicate that mild-hybrid vehicles will become the main choice for electrification, taking up a large section of the market by 2030.

Dr. Dixon says that six factors are shaping how sensors in general will meet the challenges that electric cars and autonomous vehicles present: raw performance; functional safety support; higher robustness; high intelligence; security; and—further out in time, to probably beyond 2030—the potential for new packaging concepts.

Wheel speed sensors, an important system underpinning anti-lock braking systems (ABS) and indirect tire-pressure-monitoring, increasingly need lower jitter performance. The requirements of the car are for more accurate position information in line with future self-parking scenarios, as well as higher precision measurement overall to support an algorithm calculating tire pressure. Magnetic sensors—typically Hall effect and anisotropic magnetoresistive (AMR) devices today—are beginning to transition to AMR sensing to meet increased performance challenges.

Where functional safety is involved, increasing the number of sensors from one to two or three can lead to a higher ASIL safety rating at the system level. Applications include angle sensing in steering systems, or in pedal or throttle positions, for example.

For Big Data applications, sensors must be able to collect a greater amount of information than in the past while also keeping more of the raw signal, compared to sensors today that filter the information.

What is unique to magnetic sensors is their vulnerability to stray magnetic fields. To meet a rise in demand for robustness in this regard, sensors in electric vehicles will need a new level of protection against stray magnetic fields, caused by the electromagnetic fields of the large electric traction motor. Companies are required to now meet a field specification of 4000 A/m, compared to 1000 A/m in the past, Dixon said.

Resources

• C.P.O Treutler (2001) “Magnetic sensors for automotive applications,” Sensors and Actuators A: Physical Volume 91, Issues 1–2, Pages 2-6 doi: 10.1016/S0924-4247(01)00621-5.