DC transformer working principle - Solutions - Huaqiang Electronic Network

GW MB10F 0.8A 1000V rectifier bridge

Probe current voltage pin 420*4450 head diameter 5.0 over current current and voltage pin

The working principle of the DC transformer is the principle of the saturable reactor. The primary winding is equivalent to the DC control winding of the saturable reactor, and the secondary winding is equivalent to the AC winding.

As shown in Fig. 122-1(a), the primary winding N1 of the core passes the direct current I1, and the secondary winding N2 is connected to the alternating current voltage U2. Then, when the current I1 is changed, the total impedance of the winding N2 changes due to the change in the magnetic permeability in the core, thereby changing the current I2 taken from the AC network. This is the basic principle of DC transformers.

However, such a structure is also different from a DC transformer because the alternating current I2 is proportional to the measured direct current I1 only for one half-wave period.

Usually, the DC transformer uses two identical cores (A, B), and the primary and secondary windings on the core are formed by a DC flux and an AC flux in a core during a half-wave period of the AC voltage D2. The direction is the same, the flux in the other core and the DC flux are reversed; in the next half-cycle, the magnetic flux in the two cores is opposite, see Figure 122-1(b), (c). The two cores work alternately, the DC transformer works continuously throughout the cycle, and due to the opposite connection of the AC windings, the AC potentials in the two primary DC windings are opposite and cancel each other out.

The secondary current I2 of the DC transformer can be measured with an electromagnetic ammeter directly connected to the secondary circuit. However, the secondary current is usually rectified by a bridge solid-state rectifier, and can be measured by an ammeter with an equidistant scale, with high sensitivity and low loss.

DC transformers have two basic lines, serial and parallel. The series circuit can also add an intermediate AC transformer on the secondary side, and then rectify it to have a secondary current ratio, which is convenient for measuring large current. Figure 122-2 shows the shape of the BLZ type DC current transformer.

The anti-magnetic compensation type DC transformer adopts a series reverse connection line, and an anti-magnetic compensation winding is added on the added iron core.