Commutating filter for inductive load

Claim 1

A CONTROL CIRCUIT FOR A DIRECT CURRENT CONTROLLED SHUNT MOTOR HAVING A REVERSIBLE DIRECTION OF ROTATION COMPRISING: MEANS FOR RECTIFYING AND MODULATING A SQUARE WAVE CARRIER SIGNAL IN ACCORDANCE WITH A DIRECT VOLTAGE OF A POLARITY OF DETERMINATIVE OF THE DIRECTION OF ROTATION OF SAID MOTOR TO PRODUCE A SERIES OF PULSE OF A DURATION DETERMINED BY THE MAGNITUDE OF SAID DIRECT VOLTAGE AND OF A POLARITY DETERMINED BY THE POLARITY OF SAID DIRECT VOLTAGE; COMMUTATING FILTER MEANS HAVING FIRST AND SECOND TERMINALS COUPLED TO SAID RECTIFYING AND MOUDLATING MEANS; SAID FILTER MEANS COMPRISING FIRST AND SECOND TRANSFORMERS EACH HAVING A PRIMARY WINDING AND A SECONDARY WINDING, A FIRST RECTIFIER COUPLED IN SERIES WITH SAID PRIMARY WINDING OF SAID FIRST TRANSFORMER TO FORM A FIRST UNIDIRETIONAL CURRENT PATH BETWEEN SAID FIRST AND SECOND TERMINALS, A SECOND RECTIFIER COUPLED IN SERIES WITH SAID PRIMARY WINDING OF SAID SECOND TRANSFORMER TO FORM A SECOND UNIDIRECTIONAL CURRENT PATH BETWEEN SAID FIRST AND SECOND TERMINALS IN A DIRECTION OPPOSITE THAT OF SAID FIRST UNIDIRECTIONAL PATH, AND FIRST AND SECOND CONTROLLED RECTIFIERS EACH HAVING A UNIDIRECTIONAL CURRETN PATH AND A CONTROL ELECTRODE, THE CURRENT PATHS OF SAID FIRST AND SECOND CONTROLLED RECTIFIERS BEING COUPLED BETWEEN SAID FIRST AND SECOND TERMINALS IN OPPOSITE UNIDIRECTIONAL CONDUCTIVES, THE CONTROL ELECTRODE OF SAID FIRST CONTROLLED RECTIFIER BEING COUPLED TO SAID SECONDARY WINDING OF SAID FIRST TRANSFORMER, THE CONTROL ELECTRODE OF SAID SECOND CONTROLLED RECTIFIER BEING COUPLED TO SAID SECONDARY WINDING OF SAID SECOND TRANSFORMER; AND THE ENERGIZING WINDINGS OF SAID MOTOR BEING COUPLED IN PARALLEL BETWEEN SAID FIRST AND SECOND TERMINALS OF SAID FILTER MEANS.