Magnetic amplifier

A magnetic amplifier comprising:

• a voltage converting means for inducing a pulse signal having a predetermined period and voltage level and converting this pulse signal to a sinusoidal voltage signal;
• an output voltage adjusting means for rectifying and smoothing an output voltage of said voltage converting means and supplying it for a load;
• an overvoltage detecting means for detecting an output voltage of said output voltage adjusting means and comparing it with a predetermined reference voltage, and, when an overvoltage is detected, supplying an overvoltage controlling current to adjust the overvoltage for the output of said voltage converting means;
• and
• an overcurrent damping means connected between said voltage converting means and said output voltage adjusting means for forming a discharge loop in which, when a sinusoidal voltage to be outputted from said voltage converting means has positive value, a flowing current is charged, and when the sinusoidal voltage to be outputted from said voltage converting means has negative value, the flowing current is discharged, while a discharge path is in direction opposite to a direction of the overvoltage controlling current,
• wherein said overcurrent damping means comprises:
• a first diode for rectifying an output voltage of said voltage converting means when the output voltage has positive band;
• a capacitor for charging and discharging the current passed through said first diode;
• a switching transistor with its drain connected to the input of said first diode for conducting when the output voltage of said voltage converting means has negative value and switchably controlling a discharge current of said capacitor to be flowed into the output of said voltage converting means;
• and
• a resistor connected between the output of said voltage converting means and capacitor for providing a path along which the discharge current is fed back.