System and method for common-mode elimination in a multi-level converter

A multi-level converter comprising:

• a plurality of alternating current (AC) terminals connected to a three-phase AC source or load;
• at least three direct current (DC) terminals connected to a multi-level DC source or load;
• a plurality of solid-state switches that are selectively turned On and Off to connect each phase of the AC terminal to one of the plurality of DC terminals;
• a controller that receives voltage command signals and in response generates pulse-width modulation (PWM) control signals for provision to the plurality of solid-state switches to selectively control the On/Off state of the solid-state switches, wherein various switching configurations of the solid-state switches are organized by the controller into switching states that define a plurality of triangular regions, wherein the controller selects one of the plurality of triangular regions based on the voltage command signals and selects an origin switching state within the triangular region, wherein the controller increments the switching state in a first direction around the triangular regions during a first half-cycle of a switching period and decrements the switching state in a second direction around the triangular regions during a second half-cycle of the switching period, wherein the switching states utilized during the switching period dictate the PWM control signals provided to the plurality of switches employed in the three-level converter.

A multi-level converter for switching a plurality of alternating current (AC) terminals into electrical continuity with a plurality of direct current (DC) terminals, the multi-level converter comprising:

• a first set of solid-state switches connected between a first AC terminal and the plurality of DC terminals;
• a second set of solid-state switches connected between a second AC terminal and the plurality of DC terminals;
• a third set of solid-state switches connected between a third AC terminal and the plurality of DC terminals;
• a controller connected to provide pulse-width modulated (PWM) signals to the first, second, and third sets of solid-state switches to selectively connect the first, second, and third AC terminals to one of the plurality of DC terminals, wherein the controller utilizes a space vector diagram comprised of a plurality of triangular regions each defined by three switching states, wherein the controller selects one of the plurality of triangular regions based on desired terminal voltages and generates the PWM signals by traversing in a first direction the switching states in a first half-cycle of the switching period and traversing in a second direction the switching states in a second half-cycle of the switching period.