Control unit for thyristors of a cycloconverter

摘要

A control unit for the thyristors of a cycloconverter is disclosed. The thyristors are supplied by a three phase network and the control unit is also responsive to such network. In particular, in the control unit a measuring voltage is derived from a phase voltage, and phase-shift means and smoothing means are provided to shift the phase of the measuring voltage so that its zero crossing is in the vicinity of the zero crossing of a phase voltage. The phase-shifted measuring voltage is then fed to a sawtooth integrator which generates a sawtooth voltage in dependence on the zero crossing of the applied phase-shifted measuring voltage. The sawtooth voltage is then used to generate firing commands for the thyristors.