This example shows a six-pulse cycloconverter driving a static load.
Graham Dudgeon, Senior Consultant, The MathWorks, Inc. Igor Braverman, Senior Consultant, The MathWorks, Inc.
The system consists of three-phase to single-phase cycloconverter modules suitably arranged to implement a three-phase to three-phase architecture. Each module has a positive and negative cycle thyristor bridge connected in anti-parallel. To avoid circulating currents when one bridge is conducting, the anti-parallel bridge is blocked. A 5 degree 'dead zone' exists between the positive and negative cycle commutation. You can modify the dead zone value in File -> Model Properties -> Callbacks -> InitFcn. The output voltage waveforms are constructed by suitably modifying the firing angle of the thyristor bridges.
Start the simulation. Observe the load voltages from Scope 'Vabc_load' in System Measurements subsystem, and note that a 10Hz output has been constructed from a 60Hz input. A MATLAB® script executes on completion of the simulation to more clearly show the construction of phase-A output voltage from the three-phase input. The user may modify this execution as desired by editing File -> Model Properties -> Callbacks -> StopFcn. The user can adjust the output voltage magnitude and frequency by modifying 'Output voltage (V peak)' and 'Output frequency (Hz)' respectively.