Electromagnetic flow metering by means of remanent magnetism

One of the key features of electromagnetic flow meters is their long maintenance interval. Nevertheless, they rely on a power supply for generating the clocked DC field required for flow metering. With recent sensors being intended to operate wireless, a low power demand is requisite in order to guarantee long up times. For this purpose, a remanent magnetic material will be evaluated for its potential to save energy. In contrast to the common field generation by electromagnets, power will only be consumed during the short time of the field switch. Subsequently, the magnetic field will remain constant without any ongoing power supply and can be employed for flow metering. Compared to ferrit magnets, remanent materials are easier to commutate. Therefore, they are predestinated for the generation of clocked magnetic fields. How to design a sensor based on remanent materials, providing a sufficient magnetic field under minimal losses, is one of the key tasks of this contribution. A prototype will be designed and evaluated by means of a model. The sensor will be controlled by a newly developed logic circuit. The measurement accuracy is demonstrated to be independent of the physical principle applied for field generation. The low power demand of residual magnetism is validated for low field switching rates.