Engineer interviewinterview

Motor controller engineer Special Interview
Development story of high output density motor controller

Brand new design high output density motor controller achieves high power and mountability on forklift trucks.

Naohito Kanie
TOYOTA Material Handling Company Industrial Component Engineering Dept.
SC Engineering Office No.2 Group Manager

Introduction

Toyota Industries corporation, world's top manufacturer of forklift, adopts high output density motor controller on the forklift truck. Mr. Kanie, Group manager of motor controller design, was a member of the new motor controller development team and explained background and development story of the motor controller development.

A small and high-power motor controller is used for Toyota forklifts. What is the reason for developing a new motor controller with the feature of high power density?

The motor controllers for forklift trucks in the previous generation had been custom developed with the target of optimizing for each truck models. Forklift trucks has main controller in addition to the motor controller, and in the previous generation the main control and the drive/ pump controller were integrated into fully customized product.

On the other hand, in the forklift truck the components are increasing by expanding functions and it requires smaller controller for reduction of mounting space. Under such circumstances, other controller supplier started to provide commoditized and downsized products, and it was also mandatory for us.
Therefore, in this development, with the target of developing the world's highest power density forklift controller, we proceeded with a very aggressive target, 30% reduction in the volume compared to other controller supplier.

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

Of course, enough reliability and durability is mandatory for Toyota forklift. In addition to design quality, ensuring the quality of component is very important for improving the reliability of the controller, which is assembly of electronic components. In our company, the Electronics Division designs and manufactures high reliable in-vehicle electrical components for HEV and so on, so we utilized the know-how to ensure the quality of our controller for Toyota forklift trucks.

What is your ingenuity in the new motor controller development?

The motor controller is a product that conducts a large amount of current, so with downsized body it will easily cause the problem of heat. Without counter measures against the heat, the forklift cannot work enough continuously. Therefore, it was mandatory to devise the design how to suppress the heat generation and how to dissipate the generated heat.

In designing a MOS FET substrate that outputs motor current, we repeatedly calculated simulation to design an optimized layout for reducing losses. In addition to hardware design we have succeeded in reducing switching loss and heat generation by combining software control. The design of the heat dissipation has been optimized by changing the combination of the size and number of heatsink fins and performing various simulations.

At that time, the controller was designed by a really small design team, so the responsibility of one engineer was very wide, and I myself experienced a wide range of work from structural design, board design to overseas part selection.

How about user's feedback after development of high power density motor controller?

The truck engineer was very pleased that the truck layout was much easier by greatly reducing the size of the controller. In addition, we are proud that we have contributed to the high reliability of Toyota forklifts.

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

I am currently working with overseas development members, but unlike domestic development, I am struggling a little because of differences in the latest overseas standards, culture and communication methods. I’d like to get over these differences and work hard so that our controllers can be installed in trucks around the world.

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