Reconstruction of the Magnetic Field in the Measuring Volume of an Electromagnetic Flow Sensor

A novel approach to obtain the magnetic field in the measuring volume of an electromagnetic flow sensor is introduced. It is a measurement-calculation coupled approach. Utilizing a characteristic that there is no exciting current in the measuring volume, the problem is simplified to solving a Laplace's equation of magnetic scalar potential in the volume. Through measuring the distribution of normal magnetic flux density on the boundary surface of the volume using a magnetic scanning device, the necessary boundary condition to solve the Laplace's equation is provided. Finally, the magnetic field is reconstructed through solving the Laplace's equation with the measured boundary condition. This approach is more efficient and accurate than existing approaches and do not need to know the inner structure of the magnetic exciting unit. Experimental validations on a conventional pipe flow measuring sensor and a late-model local velocity measuring sensor are both given. This reconstruction approach will be very useful in the studies of not only electromagnetic flow sensors but also many other mechatronics systems such as motors, bearing and maglev etc.