Development of Brushless Smart Motor for Front Wipers 2019-01-0610
Along with the auto industry’s proactive engagement in autonomous driving and the development of hybrid electric vehicles (HEVs) and electric vehicles (EVs) driven by regulatory compliance for vehicle emissions control and fuel economy, there is a growing need for quieter, lighter, more compact and efficient designs of electronic components for automobiles. For wiper functions, the demand for improving wiping performance at high driving speeds and increasing wiped areas is on the rise. To fulfill all these needs, this project aimed to develop the world’s first brushless controlled wiper system, focusing on the following key elements: 1) power efficiency improvement and noise reduction through an effective sensing design and control methods of field weakening and wide-angle commutation, and 2) lightweight and compact design by reducing the weight and shaft length. The first challenge was to minimize power consumption in consideration of constant load changes during wiper operation as well as reducing the motor noise. With the correction method applied to the sensing design and the field weakening control and the wide-angle commutation control, the final design reduced the power consumption by 30% and the sound level by approximately 6 dB, compared to conventional brush motors. To achieve the second goal, we changed the magnetic circuit configurations, which reduced the rotor inertia. This outcome helped change the rotor assembly structure into a single-sided support design, eliminating the bearing placed on the end cover (the housing for the rotor and stator). These design considerations and the material change of the end cover helped reduce the motor length by 30% and the weight by 20%, contributing to a lighter design. Thus, we successfully developed the world’s lightest and smallest brushless wiper motor, featuring its cutting-edge structure and control design. The product was released into the market as the world’s first brushless wiper motor.