Engineer interviewinterview

Motor engineer Special Interview
Development story of high efficient Induction Motor

The high efficient induction motor achieves both of high power and long operation hours and also the motor contributes to realize sustainable society.

Tomohiro Kosaki
TOYOTA Material Handling Company Industrial Component Engineering Dept.
SC Engineering Office No.1 Working Team Leader

Introduction

Toyota Industries corporation, world's top manufacturer of forklift, adopts high efficient induction motor on the forklift truck. Mr. Kosaki, working team leader, was a member of the new motor development team and explained story of the motor development.

A high efficient induction motor is adopted for Toyota forklift. What is the reason for developing a new motor with the feature of high efficiency?

Toyota set the target of new forklift truck, GENEO Ecore 3wheel counter balance forklift truck launched in 2015, as 20% longer operation hour which is the industrial top level.
Because electric motors consume the largest percentage of electric power in electric forklifts, to achieve the target, the motor efficiency is very important we and decided to develop low loss and high efficient induction motor.

What direction was discussed for new motor development?

In this motor development, efficiency improvement was the most important development theme. Permanent magnet motors using rare earth permanent magnets, which are easier to increase efficiency, were an option, but due to the availability of materials and cost advantages, we decided our direction to optimize induction motors for our forklifts to the limit.

What was important point of the motor development for Toyota forklift truck?

The goal was not simply to increase the maximum efficiency, but to achieve high efficiency at a wide range of operating points (speed / torque points) required for traction motors. Also, as an effect of improving efficiency, heat generation due to loss is reduced and output density is increased. As a result, it was expected to improve acceleration and lifting performance.

This motor development was very big challenge how to improve efficiency of induction motor with a simple structure, high robustness, and easy maintenance that balances costs.

What is your ingenuity in the new motor development?

Realizing high efficiency with a wide range of operating points (speed / torque points) required new motor structure. It was very tough development to find the optimal balance by selecting motor cores and slot shapes from over a thousand combinations and analyzing them in large quantities.

In actual development process, the structure is selected by combining the simulation and prototype evaluation results, and efficiency and power density were improved by the very steady and repeated work.

The newly developed motor is the 5th generation structure of our induction motor, and it achieves high efficiency in a wide range of operating points through generations by utilizing the design assets developed by seniors so far. We developed the best motor for Toyota forklifts.

How about customer's feedback after adopting of high efficient induction motor?

By this development we contributed to actually achieve the 20% improvement in operating hour of the forklift truck, which was the original development goal, and I heard that the motor was one of the reasons for Rinova reach truck to win the METI Award for Excellence. In overseas improved acceleration and operability has been well received by operators with high output density.

What kind of development would you like to do in the future?

In the future, I'd like to expand the high efficient motor lineup and contribute to the realization of a sustainable society, not only with forklifts but also with other applications in the world, especially in Europe where the electrification market is expanding.

Creating the future of logistics and mobility with leading-edge electrification technology