The electric power converter includes a series converter connected in series
between an AC power supply 1 and a load 6, and having capacitors
30, 31 as a power supply for the converter, switching devices 12, 13,
and diodes 16, 17; and a parallel converter connected in parallel to the
AC power supply 1 and having the capacitors 30, 31, switching devices
10, 11, and diodes 14, 15. The series converter compensate the change
in the voltage of the AC power supply 1 to feed a certain voltage to the
load 6, and the parallel converter conducts charging and discharging operations
to compensate the changes in the voltages of the capacitors 30 and 31
caused by the compensating operations of the series converter. The converter
suppresses the change of the AC power supply voltage and feeds a certain voltage
to the load at a high efficiency and low running costs.