Speed control of a wye-connected induction motor utilizing delta connected triggerable biconductive devices

Claim 2

A dynamoelectric machine comprising: a. a polyphase winding having three line terminals and three neutral leads; b. three bidirectionally conductive and triggerable semiconductive means connected together in a closed-loop delta having three junctions; c. means respectively connecting said three neutral leads to said three junctions; d. means for connecting a three-phase power supply to said three line terminals; and e. trigger means coupled to said semiconductive means for selectively establishing conduction therein, said trigger means providing conduction initiating trigger pulses to predetermined ones of said bidirectionally conductive semiconductive means during the positive and negative half cycles of the three-phase energization waveform applied to each polyphase winding to produce current flow in opposite directions through sequential legs of said delta connected semiconductive means during alternate half cycles of sequential phases in said three-phase power supply and means for varying the phase relationship of said trigger pulses relative to the voltage at said line terminals to correspondingly vary the quantity of power supplied to said windings.

Claim 3

The machine of claim 1 wherein said trigger means comprises a variable time-delay pulse generator coupled to each of said semiconductive means and means synchronizing operation of said pulse generators with the voltage applied to the line terminals of the two-phase windings whose neutral leads are connectable by conduction of the respective semiconductive means to which said generators are coupled.

Claim 4

A variable speed polyphase induction motor comprising: a. a stator having first, second and third phase windings therein, each winding have two extremities; b. first bidirectionally conductive triggerable semiconductive means connected to one extremity of said first phase winding and to one extremity of said second phase winding, second bidirectionally conductive triggerable semiconductive means connected to said one extremity of said second phase winding and to one extremity of said third phase winding, and third bidirectionally conductive triggerable semiconductive means connected to said one extremity of said third phase winding and to said one extremity of said first phase winding, each of said semiconductive means being triggerable to establish the only path of current conduction between the winding extremities to which it is connected; c. means for energizing the second extremity of each of said windings with an individual phase of a three-phase power source, d. trigger means coupled to said semiconductive means for selectively establishing conduction in opposite directions in the semiconductive means connected to the opposite extremity of a phase winding during successive half cycles of the power source phase connected to the second extremity of the phase winding, said trigger Means comprising a first trigger pulse generator coupled to said first semiconductive means and connected to the other extremities of said first and second phase windings, a second trigger pulse generator coupled to said second semiconductive means and connected to said other extremity of said second phase winding and to the other extremity of said third phase winding, and a third trigger pulse generator coupled to said third semiconductive means and connected to said other extremity of said first phase winding, each of said trigger pulse generators having a variable time delay to alter the phase relationship of said generated pulses relative to the voltage applied between the other extremities to which said pulse generators are connected.

Claim 5

A variable speed polyphase induction motor comprising: a. a stator having first, second and third phase windings therein, each winding have two extremities; b. first bidirectionally conductive triggerable semiconductive means connected to one extremity of said first phase winding and to one extremity of said second phase winding, second bidirectionally conductive triggerable semiconductive means connected to said one extremity of said second phase winding and to one extremity of said third phase winding, and third bidirectionally conductive triggerable semiconductive means connected to said one extremity of said third phase winding and to said one extremity of said first phase winding, each of said semiconductive means being triggerable to establish the only path of current conduction between the winding extremities to which it is connected; c. means for energizing the second extremity of each of said windings with an individual phase of a three-phase power source, d. trigger means coupled to said semiconductive means for selectively establishing conduction in opposite directions in the semiconductive means connected to the opposite extremity of a phase winding during successive half cycles of the power source phase connected to the second extremity of the phase winding, said trigger Means comprising a first trigger pulse generator coupled to said first semiconductive means and connected to the other extremities of said first and second phase windings, a second trigger pulse generator coupled to said second semiconductive means and connected to said other extremity of said second phase winding and to the other extremity of said third phase winding, and a third trigger pulse generator coupled to said third semiconductive means and connected to said other extremity of said first phase winding, each of said trigger pulse generators having a variable time delay to alter the phase relationship of said generated pulses relative to the voltage applied between the other extremities to which said pulse generators are connected.