Tamagawa VR-type Singlsyn resolvers in hybrid vehicle motors

In order to maximise the energy efficiency of the electric motor and generator system on hybrid vehicles, the current passing through the motor requires continual fine adjustment that relies on sensing the rotational position of the rotor. With motor speeds up to 30000rpm, extreme levels of shock and vibration, oil contamination, and elevated temperatures as high as 150degC within the motor casings, this application area suits a brushless and contactless resolver system. However, traditional resolvers have cost and operational limitations that have led the global automotive industry to the almost exclusive use of the technology applied in Tamagawa's Singlsyn VR-type resolvers for this demanding task.

Unlike traditional brushless resolvers - such as Tamagawa's Smartsyn series - that typically have three stator windings and a wound rotor, (effectively a rotary transformer), the Singlsyn optimises cost, space saving and reliability with a design that utilises a sheet steel magnetic rotor with no windings and a stator with only a single excitation winding and two further phase output coils. The rotor has a contoured profile with two or more "lobes" that interact with the output coils, and using the principle of variable reluctance (VR), Singlsyn tracks the magnetic permeance of the (sine/cosine) proportional relationship between the rotor/stator air gap over a 360 degree rotation. The number of stator points produces a corresponding multiplication factor, and when used with Tamagawa's Smartcoder resolver to digital converter in the ECU, high-speed, high-resolution and high-repeatability angular measurement is made possible. This absolute positional technology can also measure position at zero speed. Furthermore, thanks to their thin and particularly compact size, as well as high reliability and competitive cost, Singlsyn's are also used across other automotive vehicle applications in areas such as steering, braking, electric suspension and engine timing.

Higher levels of reliability

Tamagawa's long history in resolver technology spans more than 40 years in which the company has pioneered cost and size reduction as well as improving performance and dependability in the way that component design and manufacturing trends across all industries has progressed. Its Smartsyn resolvers reduced the size and number of component parts that military-standard designs had used from several decades earlier, but the automotive industry and the development of hybrid vehicles in mass production called for new technologies that required lowering the price point and demanded even higher levels of reliability for motor management. Tamagawa responded to the challenge with the Singlsyn, which now leads the world in this area of sensor technology. Its simplified design uses only a quarter of the component count of the Smartsyn - which had already scored over older technologies - in a much smaller envelope size and much reduced volume cost.

Mclennan Servo Supplies has worked with Tamagawa as a UK distributor for many years, representing the Japanese manufacturer across its full product range which includes servo and stepper motors, optical encoders as well as its range of brushless resolvers. This specialist area requires considerable presale support to evaluate and integrate Tamagawa's wide choice of Singlsyn VR-type resolvers to optimise hybrid vehicle performance. Mclennan is currently working with several designers and manufacturers for UK-led hybrid vehicle projects for trucks and lorries, taxis, buses, off-road and even high-performance supercar hybrids.

To learn more about Singlsyn VR-type resolvers, please go to www.mclennan.co.uk.