01 A major challenge facing automobiles in the pursuit of a cleaner future
The requirement to reduce CO2 emissions is driving global transportation equipment manufacturers to achieve increasingly lower emission standards, which means they must not only improve the efficiency of internal combustion engines, but also transition to alternative powertrains such as hybrid vehicles and pure electric vehicles.
These new powertrains have expanded the automotive industry's demand for electric motors. In particular, traction motors and starter / generators have further increased the demand for electric motors, building upon existing electric power steering, electric pumps, and electric parking brakes in conventional vehicles.
02 Existing sensing technologies and their limitations
Rotor position sensors can be used to improve motor performance under closed-loop control. Using rotor position sensors enables excellent torque control under all load conditions, including during startup, as well as high-precision angle control during braking and holding, and better rotational control at high speeds. This not only improves the overall efficiency of the motor but also reduces noise, vibration, and heat generation.
Specifically, these new sensors are designed to improve accuracy, reduce size and weight, and lower the overall BOM cost. Stray field immunity not only improves the reliability of sensors used in complex electromagnetic environments but is also another crucial requirement for developing better motors. Of course, motor position sensors not only need longer lifespan and durability but also need to operate in harsh environments such as high temperatures, humidity, and dust.
The automotive industry currently uses magnetic position sensors or rotary transformers that utilize Hall effect or xMR elements. Magnetic position sensors face limitations in terms of accuracy when used with multi-pole motors and are limited to shaft-end applications. While rotary transformers can be used with multi-pole motors using a through-shaft structure, they are expensive, bulky, and require more space.
03 The New Era of Motor Control
To meet the demand for high-precision detection in both shaft-end and through-shaft structures, Renesas Electronics developed the IPS2550 . This revolutionary new product is a position sensor for high-speed motors, featuring a sine / cosine output interface, supporting a maximum motor speed of 600 rpm , and an accuracy of 0.2% of full scale. The sensor has a standard two- layer printed circuit board, consisting of the IPS2550 , external passive components, and a metal target mounted on the motor shaft.
The IPS2550 is based on the physical principle of eddy current effect and uses three coil groups (one for transmitting and two for receiving ) .
The IPS2550 position sensor achieves a thickness reduction of up to 1/10 and a weight reduction of 1/100 , significantly lowering the BOM cost when using resolver solutions. The IPS2550 position sensor enables matching the number of sectors of the sensing coil with the number of poles, providing a state-of-the-art solution for multi-pole motors—something magnetic position sensors cannot do. This innovative approach improves accuracy while reducing weight, size, and overall system cost, representing a major technological advancement.
04 Challenges in Sensor Design
For sensors like the IPS2550, which rely on eddy current effects, sensor element design is crucial for achieving good accuracy. Renesas Electronics has developed a suite of tools for position sensor design. Furthermore, Renesas offers a database called the Customer Reference Board catalog (CRB) , which contains various sizes and pole number combinations, along with numerous sensor design examples that can be easily and quickly applied to motors. These reference designs are provided to customers as Garbar files for circuit board fabrication.
