Patent ID: 6577111
Filing Date: 2003-06-10
Classification: H02M

Abstract:
A method of controlling a magnetizing current in a transformer comprising a primary and a secondary, an output voltage and a peak primary voltage, comprising:determining a positive peak value of the magnetizing current using an external current sensor during a half-cycle in which the output voltage transitions from a positive maximum to a negative maximum; storing the positive peak value; determining a second positive peak value of the magnetizing current using an external current sensor during a second half-cycle in which the output voltage transitions from the positive maximum to the negative maximum; determining an onset of core saturation in a positive direction based on the positive peak value of the magnetizing current and the second positive peak value of the magnetizing current, by comparing the difference between the positive peak value of the magnetizing current and the second positive peak value of the magnetizing current with a predetermined threshold value; determining a control action based on the onset of core saturation; and implementing the control action to control the magnetizing current in the transformer.