Control device for power converter

A control device for a power converter of the type in which an AC side thereof is connected through a reactor to an AC power supply while the DC side thereof is connected to a smoothing capacitor and a load, whereby power rectification and power inversion is carried out by pulse width modulation control in a bi-directional manner, said control device comprising a vector operation circuit which responds at least to a voltage signal of said AC power supply and a voltage signal on the DC side of said power converter for producing an amplitude signal and a phase signal of the voltage on the AC side of said power converter so that the current flowing through said reactor and the AC power supply voltage have a predetermined phase relationship;

• a DC component detector for detecting a DC component in the current flowing through said reactor;
• and a DC component compensation circuit which responds to the output signal derived from said DC component detector for operating at least one of the amplitude signal and the phase signal derived from said vector operation circuit so that the DC component in the current flowing through said reactor becomes zero, whereby the pulse width modulation control of said power converter is performed in response to said amplitude signal and/or phase signal operated by said DC component compensation circuit.

A pulse width modulation pulse generator for performing pulse width modulation control of a power converter including switching means in response to the amplitude data and phase data of a voltage produced on the AC side of said power converter, said pulse generator comprising:

• a memory device having addresses that correspond sequentially to a phase angle of an AC reference signal whose frequency is maintained at a predetermined value and whose amplitude varies from zero to a predetermined level and in which data is stored corresponding to the amplitude value of the AC reference signal whose instantaneous value, at the phase angle corresponding to the address wherein said data is to be stored, is equal to an instantaneous value of a carrier signal whose frequency is maintained at a predetermined frequency higher than that of the AC reference signal and whose amplitude is identical to a maximum value of a variation range of the amplitude of the AC reference signal, a readout means for sequentially reading out the data stored in the memory devices, and a comparator means for comparing the readout data from the memory device with a modulation degree data corresponding to the magnitude of the AC side voltage of the power converter, thereby generating a modulation pulse signal.