A simple low cost energy efficient magnetizer for industrial applications

Permanent magnets with high energy products are widely used in a variety of electromagnetic devices. The process of magnetization requires generation of intense magnetic fields in close proximity with the magnetic material to be magnetized. The fields however need to be produced for a short time of the order of a millisecond. The intense magnetic field is produced by passage of a very heavy current through a coil or set of coils consisting of a few turns of copper wire or tube for a short duration, though in general, iron is used as a core material and coreless coils in some applications. Design of the core and winding shape, gauge of wire, and number of turns are determined by the desired magnetization profile. The permanent magnet material in an impulse magnetizer is typically magnetized by the discharge current of a large capacitor bank. The magnetizer generates short duration magnetic fields in the range of 100-200 Gauss within the sample coil. The capacitor bank is first charged to the desired voltage (corresponding to the desired field). It is then discharged through the coil very quickly using a high capacity SCR as a switch. Because very high current levels are involved, the coil and all circuitry are totally contained in a single case. The proper protection circuit is provided for SCR circuit. A novel technique for magnetizing the permanent magnets is presented. Simulated waveforms of voltages and currents are presented. The simulated results are verified with the hardware results.