Patent Application
20080030916
The system is comprised of demagnetizing coil(s) and a microcontroller based power control. The power control sends bursts of energy in succession to demagnetizing coil(s) thereby demagnetizing ferromagnetic materials by exposing them to alternating decaying magnetic fields.
Included in the microcontroller based power control are visual indicators to show present status of input power, coil energy, and temperature condition. Also included in the control are resistor(s), rectifier(s) diode(s), filter capacitor(s), optocoupler(s), fuse(s), filter(s), power supply(s) and triac(s).
Input power is fed through input line power connector at 1 protected by the fuse at 2 and filtered by AC filter at 3.
The demagnetizer has 3 different visual indicators for present input AC power indicated by green LED at 13. The power supply for this diode consists of resistor at 11, rectifier diode at 12 and filter capacitor at 14. The red LED at 6 is indicating that the demagnetizer coil(s) at 10 are energized. Power supply consists of resistor at 4, rectifier diode at 5, and filter capacitor at 7.
If the coil(s) exceed the maximum allowable temperature, the thermal switch at 19 opens and the power is being rerouted through resistor at 20, rectifier diode at 21, and filter capacitor at 23 which constitute power supply for yellow LED at 22 indicating overheating condition.
The demagnetizing coil(s) are being energized when triac at 15 conducts. Firing pulse for triac are supplied by optocoupler at 17 and current limiting resistor at 16. The driving signal for optocoupler is delivered by the microcontroller at 24 and fed through current limiting resistor at 18. Microcontroller is supplied by the non-isolated 5VDC capacitive power supply at 25.
The switching logic is created by microcontroller. By sensing the zero crossing point of the input sine wave through resistor at 27, microcontroller sends out a burst of triggering pulses to energize demagnetizing coil(s). The pulses that are used to fire triac are synchronized with incoming sine waves. This way the microcontroller can turn on the demagnetizing coil(s) at 10 exactly at zero crossing of the sine wave reducing switching, losses and improve efficiency and establish balance between positive and negative sine wave.
Length of the burst pulse depends on the demagnetizing coil(s) at 10 being used and will vary from coil to coil. The pulse has to be long enough to allow magnetic field to build up. When triac at 15 stops conducting, which corresponds to OFF time of the burst, the energy stored in the coil(s) at 10 will be transferred to the capacitor at 9. When the energy transfer is complete, the capacitor will return this energy back to the coil(s). During this process the voltage waveform applied to the coil(s) is a smooth exponentially decaying sine wave. This part of circuit is known as tank circuit.
The energy received by the capacitor at 9 is smaller then energy supplied by the coil(s) at 10. This is mainly due to resistive losses in the coil(s) and resistor at 8 which also limits inrush current of the capacitor at 9. Each time the energy transfer occurs, there is certain percentage of that energy that is lost. This is known as damping factor, meaning the energy is constantly reducing which gives us desired effect of decaying magnetic field.
Since these bursts are sent in succession, the demagnetizing process is ongoing, as long as pushbutton at 26 is depressed. If the pushbutton is released in the middle of burst ON time, microcontroller will continue to control the coil(s) until one whole burst cycle is completed. This way the applied burst sine wave to the coil(s) will be always symmetrical, meaning that positive part of the sine wave is equal to the negative part of the sine wave. This is essential for best demagnetizing results.
This application claims the benefit of PPA Ser. No. 60/883,389, filed Jul. 27, 2006 by the present inventor(s).
| Number | Date | Country | |
|---|---|---|---|
| 60833389 | Jul 2006 | US |
