Watchmaking Motors

Description

This lecture covers the application of single-phase motors in watchmaking, focusing on the dissymmetry and mutual couple in bipolar motors, as well as the interaction between magnet-stator geometry and current in the coil. It explains the functioning of quartz and mechanical watches, the equivalent magnetic scheme, and the torque constant estimation. The lecture also discusses energy-saving possibilities, step detection, and the autoquartz watch. Additionally, it explores the use of MEMs technology for micro MEMs motors in watches, the development of hybrid MEMS BLDC micromotors, and the characteristics of studied electromagnetic motors. The presentation delves into the differences between single-phase and three-phase motors, system requirements, and the optimization results for planar coils made of aluminum and copper.

Official source

https://mediaspace.epfl.ch/media/0_43118pyr

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Related concepts (67)

Stepper motor

A stepper motor, also known as step motor or stepping motor, is a brushless DC electric motor that divides a full rotation into a number of equal steps. The motor's position can be commanded to move and hold at one of these steps without any position sensor for feedback (an open-loop controller), as long as the motor is correctly sized to the application in respect to torque and speed. Switched reluctance motors are very large stepping motors with a reduced pole count, and generally are closed-loop commutated.

Electric motor

An electric motor is an electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a wire winding to generate force in the form of torque applied on the motor's shaft. An electric generator is mechanically identical to an electric motor, but operates with a reversed flow of power, converting mechanical energy into electrical energy.

Field coil

A field coil is an electromagnet used to generate a magnetic field in an electro-magnetic machine, typically a rotating electrical machine such as a motor or generator. It consists of a coil of wire through which a current flows. In a rotating machine, the field coils are wound on an iron magnetic core which guides the magnetic field lines. The magnetic core is in two parts; a stator which is stationary, and a rotor, which rotates within it.

Induction motor

An induction motor or asynchronous motor is an AC electric motor in which the electric current in the rotor needed to produce torque is obtained by electromagnetic induction from the magnetic field of the stator winding. An induction motor can therefore be made without electrical connections to the rotor. An induction motor's rotor can be either wound type or squirrel-cage type. Three-phase squirrel-cage induction motors are widely used as industrial drives because they are self-starting, reliable, and economical.

Quartz crisis

The quartz crisis was the upheaval in the watchmaking industry caused by the advent of quartz watches in the 1970s and early 1980s, that largely replaced mechanical watches around the world. It caused a significant decline of the Swiss watchmaking industry, which chose to remain focused on traditional mechanical watches, while the majority of the world's watch production shifted to Japanese companies such as Seiko, Citizen, and Casio which embraced the new electronic technology.