Sensorless Control of Permanent Magnet Synchronous Motor Based on New Sliding Mode Observer with Single Resistor Current Reconstruction

To solve the chattering problem caused by discontinuous switching function in traditional sliding mode observer,a piecewise square root switching function with continuously varying characteristics is designed,and its stability is analyzed by using Lyapunov stability criterion.Secondly,according to the relationship among bus current,switching state and phase current,a single bus resistance sampling current reconstruction scheme without current sensors is adopted,which effectively reduces the cost of motor system.Finally,the feasibility and effectiveness of the proposed scheme are verified by simulation.

The forward and inverse problem of cardiac magnetic fields based on concentric ellipsoid torso-heart model

This paper constructs a concentric ellipsoid torso-heart model by boundary element method and investigates the impacts of model structures on the cardiac magnetic fields generated by both equivalent primary source--a current dipole and volume currents. Then by using the simulated magnetic fields based on torso-heart model as input, the cardiac current sources--an array of current dipoles by optimal constrained linear inverse method are constructed. Next, the current dipole array reconstruction considering boundaries is compared with that in an unbounded homogeneous medium. Furthermore, the influence of random noise on reconstruction is also considered and the reconstructing effect is judged by several reconstructing parameters.

Cardiac electrical activity imaging of patients with CRBBB or CLBBB in magnetocardiography

A new method for the imaging of cardiac electrical activity in patients with complete right bundle branch block （CRBBB） or complete left bundle branch block （CLBBB） is investigated using magnetocardiographic recordings of the surface of the body. This is based on the assumption that an equivalent single-current dipole moves along the unblocked bundle branch, whose position in the measurement plane is expressed in terms of the maximum and minimum, as well as the maximum gradient value of the measured magnetic field. The trajectory of the moving dipole on the measurement plane is indicative of theexcitation conduction of the CRBBB or CLBBB subject during ventricular depolarization and repolarization, which is deduced by comparing each change between the dipole moment and the maximum current density in a corresponding pseudo-current density map. In summary, this method can distinguish CRBBB from CLBBB subjects by means of the dipole depth and two dipole moment components. The possibility of visualizing the excitation conduction in a CRBBB or CLBBB subject during ventricular depolarization and repolarization is then discussed.