Matrix converter control system

In a three-pulse UFC system including three groups of three bilateral switches, each group being associated with a corresponding one of three AC output lines connected to a load, each bilateral switch in a group being associated with a corresponding one of three AC input lines of an AC power supply;

• the combination of:
• function generator means operating in synchronism with said AC input power supply for generating respective control signals for firing said switches in the respective groups and for establishing conduction time intervals in accordance with a switching polarity pattern for said groups in the respective AC input lines thereof;
• feedback means responsive to current flowing in said load from said AC output lines for providing a feedback current signal;
• means for providing an AC reference current signal for said load;
• comparator means responsive to said feedback means and said reference means for providing an error signal representing the difference between said feedback current signal and said current reference signal;
• and
• deadband hysteresis means having an upper and a lower limit in the response to said error signal in either direction relative to said reference signal for providing a corrective signal;
• said corrective signal being applied on the output of said function generator means for modulating said switching polarity pattern and for establishing through said bilateral switches on said AC output lines an output current in accordance with said corrective signal;
• thereby to force said load current to follow said reference signal.