Electrotechnical Systems

145Simulation of Power Electronics Devices

small capacitance, respectively, form the resonant circuit. The transistor K7 with the

antiparallel diode D7 and the capacitor C

cl

form the clamping circuit.

Suppose rst that the clamping circuit is absent. Under resonant oscillations, the

voltage U

c

decreases from some peak value down to zero and tries to attain a negative

value, but it is impossible because of the antiparallel diodes of the inverter bridge. At

that moment, it is possible to change the state of the switches “soft,” with zero volt-

age across them, that is, without losses. However, before that it is necessary to store

some amount of energy ...