Chopper circuit using transistor bridge - has capacitance divider connected across input and connected to transformer primary

摘要

The chopper circuit comprises four transistor (1-4) connected in a bridge circuit with the output transformer primary (5) in one diagonal and the d.c. input on the other. The switching losses in the transistors can be reduced by fixing the transformer primary mid-point potential. The primary mid-point (15) is connected to the mid-point (14) of two identical capacitors (12, 13) connected across the d.c. input terminals (10, 11). This holds the transformer mid-point voltage approximately constant and reduces the turn-off losses of the slowest transistor. Losses may be further reduced by adding an inductor (18) in the primary lead between the capacitor connection point and the bridge connection point.