There are generally two methods for changing the size of the inductance in a power supply.
One: The method is to use a threaded soft ferrite to change the position of the iron core in the coil;
Two: Use a sliding switch to change the number of turns of the coil, thereby changing the inductance of the inductor. The disadvantage of these two methods is that there are movable parts, which can only be adjusted manually and cannot be controlled automatically. In the specific power supply equipment, the method of combining the iron core and the line is used to change the inductance of the inductor. There are the following three methods.
a: saturated inductance method
Two windings are wound on the iron core, one is the working winding, which is connected to AC; the other is the control winding, which is connected to DC. By changing the magnitude of the DC current in the control winding, the saturation degree of the iron core can be changed, thereby changing the equivalent inductance of the working winding. size. This method is relatively early, and the working principle of saturable inductors and magnetic amplifiers is based on this saturable inductance method.
b: Switch-controlled inductance method
A triac switch is connected in series in the inductor circuit, and the equivalent inductance of the inductor is changed by turning on and off the triac. A large number of research, development and production of sinusoidal energy divider AC stabilized power supply at home and abroad are based on this switch-controlled inductance method.
c: Orthogonal core control inductance method
Rotate one half of the C-type iron core by 90° and connect it to the other half. The working winding is wound on the half of the iron core, and the AC is connected; the other half of the iron core is wound around the control winding and the DC is connected. By changing the magnitude of the DC current, the inductance of the working winding can be continuously changed. It is used in switching power supply, inverter power supply, AC regulated power supply and power AC series compensator and phase shifter. Japan calls this orthogonal shape soft ferrite core, called SX-type core.
