Directly Detecting αβ Phase Currents by Utilizing a New Coreless Current Sensing Method, Termed as “Magnetic Clarke Transformation”

Kosuke Kajita･Shotaro Karasuyama (Honda Motor)

In the conventional method of detecting UVW phase currents, a core is used to strengthen the magnetic flux within its own phase.
The purpose of this paper is to propose a new current detection method, the "Magnetic Clarke Transformation," that directly detects αβ phase currents without the need to use cores by utilizing the magnetic flux from the surrounding phases.

Increasing the Ability to Freely Arrange the αβ-phase Current Sensors using a New Coreless Current Sensing Method, Termed as “Magnetic Clarke Transformation”

Shotaro Karasuyama･Kosuke Kajita (Honda Motor)

This paper proposes a new current sensing method, “Magnetic Clarke Transformation,” that directly detects αβ phase currents instead of UVW phase currents.
This method makes it possible to consolidate busbars by utilizing the coreless current sensors, but its limitations are due to new layout constraints.
This paper details a method for improving the placement of αβ-phase current sensors.

Development of Nd-reduced Magnet and Beyond NdFeB Magnet for Automotive Motors

Noritsugu Sakuma･Akihito Kinoshita･Hyuga Hosoi･Akira Kato･Tetsuya Shoji･Yusuke Umetani (Toyota Motor)

The rapid increase in demand for electric motors may result in a shortage of materials such as NdFeB magnets.We have developed Nd-reduced magnet and beyond NdFeB magnet that has made it possible to significantly reduce the amount of Nd used. These magnets were applied to a small motor, and efficiency and torque were evaluated at room temperature to high temperature.

A Study on the Application of Ferrite Magnets in EV Drive Motors

Ryosuke Minegishi･Shunji Oki･Tomoaki Kaimori (Nissan Motor)

We focused on ferrite magnets, which are available at a lower cost compared to neodymium magnets and examined the possibility of applying them to high-speed drive motors with small power and high gear ratios. We incorporated measures to utilize weak magnetic forces while ensuring centrifugal force strength with the increase in rotational speed, and discovered a motor shape using ferrite magnets that can reduce costs compared to neodymium magnet motors.

Visualization of Oil Behavior to the Coil End of an Oil-cooled Motor using X-ray Computed Tomography

Masataka Tanase･Akinobu Kochi･Masanori Shimizu (Toyota Motor)

In recent years, the heat generation density of motors for automobiles has increased due the side effect of downsizing. However, cooling with a large amount of oil decreases efficiency. Therefore, a more optimal cooling design is now required.
We visualized the dynamic oil behavior in the coil end, which was previously difficult to measure, using X-ray computed tomography. Additionally, we conducted a validation with CAE to establish efficient cooling design technology.