Nidec Corporation announced that it has achieved the world’s highest-level space factor for round winding wires used for its traction motors, and has launched the mass production of motors by using the technology.
Nidec’s second-generation E-Axle model (“E-Axle Gen.2”), which has an optimized slot shape and uses newly developed, unique coil insertion equipment, has successfully improved the coil space factor*1 by 6% compared with its predecessor, E-Axle Gen.1. In addition, the E-Axle Gen.2 model, with enhanced output characteristics, has a motor section 10% smaller than the previous model.
*1. Coil space factor: The rate of copper wires to a stator’s space (slot) to accommodate a coil. As part of a motor’s feature, its output increases, as does the number of copper wires inside its stator. However, to make the motor compact, a coil must be placed efficiently, without creating an empty space.
A common way to improve the space factor is to use the hairpin method, which employs rectangular wires that can fit into a square slot more easily than round ones, though, on the other hand, this method requires a complex production process and a massive amount of capital investment. To counter this issue, Nidec, aiming to produce high-performance and yet low-price E-Axle units (the concept behind the development of E-Axle Gen.2), continued to use inexpensive round winding wires, while developing a new wire-winding technology to reduce the loading application rate during coil insertion by 80% compared with the conventional technology. Thus, the Company successfully lessened the damage to the coil during its insertion process, achieving both high performance and low cost.
