
20-16 Power Electronics and Motor Drives
20.5 Resonant DC Link Converters with ZVS
To avoid the switching losses in the converter, a resonant circuit is connected between the DC source
and the PWM inverter. e basic principle is illustrated by the simple circuit shown in Figure 20.21a.
e resonant circuit consist of the L–C–R components. e load of the inverter is modeled by the I
o
cur-
rent source. I
o
is assumed to be constant in one cycle of the resonant circuit.
Switch S is turned o at t = 0 when i
L
= I
L0
> I
o
. First, assuming a lossless circuit (R = 0), the equations
for the resonant circuit are as follows:
i I
V
Z
t I I t
L o
DC
L o
= + + −
0
0