Thursday 10 December 2015

The general running principle of actuators?





The actuator has an electrical side and a mechanical side. The most important principle is that current in an electrical conductor move inside of a magnetical field. Such actuators has the ability to convert electrical energy to mechanical energy and vice versa. The energy conversion takes place in and around the rotor. It is easy to explain the conversion with the Lorentz-force law. The actuator is working in motor mode when electrical power is transformed to mechanical power. It is in generator mode as mechanical power is transformed to electrical power. When an actuator gets both electrical and mechanical energy input it is a dissipator (plugging mode). This mode can be used as a brake. Figure shows schematically the electrical mechanical converter with the possible energy flows. A magnetic field is necessarily for the conversion, which gives always losses of electrical, mechanical and magnetical nature. The mechanical losses are ventilation, the static and viscous friction; electrical losses are conduction (copper) losses. The magnetical losses can be iron losses (eddy current) or indirect from leakage fields. In chapter 2 the magnetical losses will be described. All the losses caused an irritating heat, which reduces the functions of the actuator.

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