OFF-LINE MULTILEVEL PHASE VOLTAGE INVERTER Russian patent published in 2003 - IPC

FIELD: electrical engineering; controlling ac drives and secondary power supplies. SUBSTANCE: novelty is that known inverter which has parallel-connected circuits each incorporating two transistor switches 1, two similar diodes 2, and capacitor 3 is provided in addition with 2(Nϕ-1) transistor switches 1, where Nϕ is number of amplitude-quantizing levels of output voltage, connected in each parallel circuit to point of connection of transistor switches; connected to outputs of newly introduced transistors that function as additional inputs are respective additional 2(Nϕ-1) outputs of bipolar multilevel AC voltage source 6 with neutral voltage output relative to source 5 placed at potential of electric field intensity to ground equal to ϕ₀, and 2Nϕ outputs of different other-than-neutral voltages of source 6 placed at potential relative to voltage source 5 equal to with potential difference between adjacent outputs of voltage sources 5 and 6 being constant and equal to ΔU; newly introduced are also 2(Nϕ-1) similar capacitors 3 and neutral wire 4 that functions to connect neutral input of load 9 to neutral output of bipolar multilevel voltage source 5; leads of capacitors 3 are connected to respective adjacent 2(Nϕ+1) leads of bipolar multilevel DC voltage sources 5 and 6; point of connection of all transistor switches incorporated in parallel circuit forms output of phase 7 connected to input of m-phase load 8; all transistor switches 1 carry equal critical current and parallel-circuit transistor switch 1 connected to output of voltage source 6 placed at potential relative to neutral output of source handles critical switching voltage equal to that of parallel-circuit transistor switch 1 connected to output of voltage source 6 placed at potential to neutral output of source equal to ±ϕ_Nϕ, multiplied by i/N_ϕ. EFFECT: enhanced quality of inverter output voltage control with respect to level, frequency, and phase; reduced power loss in transistor switches. 8 dwg