Photographing the Commutation Spark from Universal Motor by External Laser Trigger Method.

Abstract

We have attempted to clarify the mechanism of generating commutation spark by means of the images photographed with a high-speed camera. In the photographing system with the high-speed camera, we have contrived a new external laser trigger method that uses a laser beam as trigger signal for shutting of camera. In the external laser trigger method, we provide the motor fan with a 1-mm hole. When the laser beam passes through this hole, a trigger signal is generated, and this trigger signal performs shuttering of the high-speed camera via an optical detector and a pulse generator. The new external laser trigger method has enabled us to photograph spark of any commutator segment of the motor in high-speed rotation. Moreover, it has also become possible to photograph the process from generation to extinction of commutation spark, making us capable of analyzing the commutation spark from photographed images.