Research On Neutral Point Voltage Balancing Of The NPC Three Level Inverter

Since several years the use of three-level NPC inverters is considered as an appropriate application for the loads with high power consumption,such as electric motors in different electric vehicles,etc.Three-level inverters belong to the multilevel inverter topology,which has huge differences from two-level inverters,could be considered as its extension.Because greater range of operating voltages comparing with two-level topology multilevel inverters provide better output characteristics.Usually the output signal of them of them closer to a sinusoidal waveform.Because of various range voltage levels operations multilevel inverter has voltage stabilizations problems.It's the main problem of this kind of devices.One way to solve them is to integrate additional parts into topology,and the other one is to change topology significantly.The first way could be more acceptable,because of less amount of parts included into topology.This survey consists of several parts,thus there could be distinguished several parts groups.The first part includes: existing three-level invertor topology,proposal and mathematical model of the three-level three-phase NPC inverter,a comprehensive survey of existing three-level invertor control strategies.The second one includes: defining the influence of various circuit parameters on the three-level NPC inverter workflow.And the last group is devoted to the analysis of hardware solutions for neutral point voltages stabilization and decreasing fluctuations.