“Need for rotation speed/angle detection magnetic angle sensor ↑”


Non-contact magnetic angle sensor, stable and low power… reliability ↑
Infineon magnetic angle sensor installed in applications such as SAS and SBW

[Editor's Note] Recently released cars are equipped with so many semiconductors that they can be called electronic products, and the role of sensors is growing day by day in this electrification trend. Among them, the magnetic angle sensor is gaining attention in the market due to its various advantages such as low power and light weight. The magnetic angle sensor is used as a steering angle sensor based on high reliability, and is also equipped with SBW (Shift By Wire) that satisfies both design and convenience in vehicle operation. Our magazine met with Hyunjung Kim, manager of Infineon Technologies Korea, a global semiconductor solutions company, to hear about trends in automotive parts, magnetic angle sensors, and magnetic circuits.

▲ Infineon Technologies Korea Manager Hyunjung Kim

■ What are the recent trends in automobile parts?

As electrification of automobile parts and development of autonomous driving platforms accelerate, ‘safety’ is becoming more important.

Today's cars are more like electronic devices.

Many components used in existing powertrains, chassis, safety, and body are being developed using semiconductors, including sensors.

The safety of semiconductors is directly linked to the safety of drivers and pedestrians, and the development of semiconductors that take functional safety into account is required.

For this reason, functional safety is one of the most important topics in automotive components, and the demand for products that meet the ISO26262 standard and semiconductors that can satisfy high ASIL levels is also increasing during the development process.

■ I'm curious about the principle of the magnetic angle sensor.

Magnetic angle sensors are largely divided into products that use the Hall effect principle and products that use the MR (Magneto-resistive) principle, and the MR series is divided into AMR (Anisotropic Magneto Resistive), GMR (Giant Magneto Resistive), and TMR (Tunnel Magneto Resistive).

Magnetic angle sensors using the Hall effect detect the strength of a vertically applied magnetic field, and can typically use information about the strength of the magnetic field applied along the X and Y axes to calculate the angle at which the actual magnet has rotated.

Compared to the MR series, it has a wider range of magnetic fields that can be measured, and it has the advantage of providing relatively more freedom in magnetic circuit configuration because it can provide both magnetic field strength information and angle information.

Sensors using MR (Magneto-resistive) technology work on the principle that resistance changes depending on the influence of a magnetic field.

In general, it is more noise-resistant than a Hall sensor and enables precise sensing.

Also, because it has excellent sensitivity, it can detect weak magnetic fields, so it can detect magnets that are relatively far away, and it is also possible to reduce the size of the magnet.

■ Please explain the features and advantages of the magnetic angle sensor.

The magnetic angle sensor is a representative non-contact sensor, and has low power consumption and stability compared to other non-contact sensors.

It also fits the lightweight and miniaturization of automobile parts because it does not require any other parts other than magnets and sensors.

Due to the nature of the magnetic field, it does not affect non-magnetic materials.Because there is no contact, it is not affected by moisture and dust, and because it is a non-contact method, there is less risk of damage, making it a sensor with high reliability even in the harsh environment of an automobile.

■ What is the most important thing when designing a magnetic circuit?

Magnetic fields are very sensitive to changes in physical position, such as the air gap between the magnet and the sensor.

Therefore, in order to predict the magnetic field applied to the sensor, it is necessary to consider the change in the magnetic vector, including the strength of the magnetic field, in advance through simulation.

Additionally, when constructing complex magnetic circuits, algorithms that reinterpret changes in magnetic fields into changes in position must also be considered.

The magnetic circuit is not sensitive to impurities in non-magnetic materials, but it is affected by the presence of magnetic materials in the surroundings, so it is necessary to test the influence of surrounding stray fields, and conduct simulations assuming the worst case while considering the temperature characteristics of the magnet to secure a design margin.

■ Please explain an application using Infineon’s magnetic angle sensor.

Its representative application is the steering system such as SAS (Steering Angle Sensor), and recently it is also being used in rotary SBW (Shift By Wire), brake system, and wiper system.

In addition to this, there are many applications within a vehicle that involve rotational movement and can be used for detecting seat positions and rotary switches.

rong>■ Lastly, please say a word to the readers.

From the customer's perspective, Infineon aims for complete system solutions including sensors and services based on P2S (Product to System).

Infineon not only shares with customers various ways of using magnetic sensors and ideas, but also accepts feedback from customers and the market to create products and welcomes collaboration for various ideas and solutions using magnetic sensors.