Elevator DC motor drive with unity power factor, including regeneration

Claim 1

An elevator system, comprising: a DC elevator motor driving a sheave; an elevator car and a counterweight roped to said sheave; a DC matrix converter for directly connecting three-phase AC mains to said DC elevator drive motor, comprising a plurality of insulated gate bipolar switches, a first one of said switches connected between a first AC main and a first DC terminal of said elevator motor, and poled to conduct current in a first direction in said first main; a second one of said switches connected between said first AC main to a second DC terminal of said elevator motor, and poled to conduct current in a second direction in said first main, said second direction being opposite to said first direction; a third one of said switches connected between a second one of said AC mains and said first DC terminal, and poled to conduct current in said first direction in said second main; a fourth one of said switches connected between said second Ac main and said second DC terminal, and poled to conduct current in said second direction in said second main; a fifth one of said switches connected between a third one of said AC mains and said first DC terminal, and poled to conduct current in said first direction in said third main; and a sixth one of said switches connected between said third AC main and said second DC terminal, and poled to conduct current in said second direction in said third main; said system further comprising a converter control logic for providing signals to cause said switches to selectively conduct for fractions of a modulation period of time which is very short compared to the period of voltage on said AC mains, to conduct current at actual line voltage, V, for variable, shared fractions of time, so as to synthesize, directly, the desired DC voltage, Vdc=mV, at said DC output terminals when they are connected to said elevator motor, while maintaining a sinusoidal current input to the DC matrix converter.