Single-Phase Bridge Rectifier
An uncontrolled single-phase bridge rectifier with a source inductance Ls and an
inductive load is shown in Fig. 4-26a. When the source changes polarity, source
current cannot change instantaneously, and current must be transferred gradually
from one diode pair to the other over a commutation interval u, as shown in
Fig. 4-26b. Recall from Chap. 3 that commutation is the process of transferring
the load current from one diode to another or, in this case, one diode pair to the
other. (See Sec. 3.11.) During commutation, all four diodes are on, and the voltage
across Ls is the source voltage Vm sin (t).
Assume that the load current is a constant Io. The current in Ls and the source
during the commutation from D1-D2 to D3-D4 starts at Io and goes toIo. This
commutation interval starts when the source changes polarity at t as is
expressed in