Multi-level inverter and power supply system

A power supply system, comprising a direct current power source, a load and a multi-level inverter, wherein the multi-level inverter converts a direct current generated by the direct current power source into an alternating current, so as to provide the alternating current for the load;

• wherein the multi-level inverter comprises:
• two N-level inverter units, wherein each of the N-level inverter units is configured to convert a direct current into an alternating current, and pulse width modulation waves of the two N-level inverter units that are staggered by a phase of 180 degrees, so that output waveforms of alternating currents generated by the two N-level inverter units are staggered by half a cycle, wherein N is an integer greater than or equal to 3;
• a direct current power source module, configured to generate the direct current, wherein an output end of the direct current power source module is connected to input ends of the two N-level inverter units, and configured to supply power to the two N-level inverter units;
• a transformer, comprising a primary side and a secondary side, wherein an inductor of the primary side and an inductor of the secondary side are coupled, one end of the inductor of the primary side and one end of the inductor of the secondary side are connected to output ends of the two N-level inverter units respectively, so that the two N-level inverter units are reversely coupled, and the other end of the inductor of the primary side and the other end of the inductor of the secondary side are connected, so as to output W levels at a junction between the inductor of the primary side and the inductor of the secondary side, wherein W=2N−1;
• and
• a filter, configured to filter out a voltage ripple at the junction between the two coupled inductors of the transformer, wherein one end of the filter is connected to the junction between the two coupled inductors of the transformer, and the other end of the filter is grounded.