Realisation of convertor control using sample-and-delay method

The design and principle of operation of a sample-and-delay circuit are described in the paper. The voltage controlled phase-delay circuit has a wide dynamic range of usable linearity. It has been successfully applied to a convertor model as a phase-delay controller for the control of constant current. An approximate method is given for the estimation of the dynamic behaviour of the closed-loop system. It is also shown that the same controller can be used in a new constant-extinction-angle control system, which has the possibility of reduced susceptibility to disturbances in the commutation voltage.