An apparatus for controlling power converters comprises a pulse generator (including a microcomputer (10, 11)) for sup­plying a pulse pattern to semiconductor devices (31-36, 51-56) of a power converter (such as an inverter (5) or a converter (3)) using the pulse width control scheme. The pulse generator is provided with a function of decimating pulses so that the pulse pattern may form a predetermined function provided that the pulse width is shorter than a limit value (Limit). As a result, the input and output waveforms of the power converter can be made sinusoidal and can be released from the constraint of the minimum pulse width of power conversion semiconductor devices.