A fault-tolerant modulation method for a common bus double-ended cascaded five-level inverter

Abstract

A fault-tolerant modulation method for a double-terminal cascaded five-level inverter with a common bus. The stator winding of the motor is opened, and the two ends of the stator winding are powered by two identical inverters, and the two inverters share a The DC bus is set to form a common bus double-ended cascaded five-level topology; in order to ensure that the reference voltage vector track is a circle, when a short-circuit fault occurs in the switching device, the maximum output voltage of the inverter will drop to half of the original, and only the inner six The polygon can use the switch state to synthesize the reference voltage vector, and use the rotation and per unit of the coordinate system to effectively simplify the five-level modulation method and reduce the hardware requirements of the system control; use the balance factor to ensure the fault-tolerant control, and realize the midpoint potential balance. The present invention is based on the high fault-tolerant characteristics of the double-ended cascaded five-level inverter. When the switching device fails, the fault-tolerant operation of the inverter is realized by reselecting the voltage vector; an optimization method is proposed for the double-ended cascaded system The 60° modulation method.

Description

technical field [0001] The invention relates to a fault-tolerant modulation method of an inverter, in particular to a fault-tolerant modulation method of a common-bus double-end cascaded five-level inverter. Background technique [0002] The double-terminal three-phase open-winding motor has the advantages of high output voltage level, large number of output levels, and strong fault tolerance. Key transmission occasions are very important. At present, some studies have been carried out on the double-terminal cascaded topology of open-winding motors at home and abroad. Since the stator windings of open-winding motors are opened, the common-mode voltage and zero-sequence voltage of double-terminal cascaded five-level inverters are different from those of single-inverted inverters. The converter is different. When the double-ended cascaded converter adopts a common bus structure, there is a large zero-sequence voltage, which will cause a large circulating current and cause loa...

AI Technical Summary

Problems solved by technology

At present, some studies have been carried out on the double-terminal cascaded topology of open-winding motors at home and abroad. Since the stator windings of open-winding motors are opened, the common-mode voltage and zero-sequence voltage of double-terminal cascaded five-level inverters are different from those of single-inverted inverters. The converter is different. When the double-ended cascaded converter adopts the common bus structure, there is a large zero-sequence voltage, which will cause a large circulating current and cause load current distortion.

[0003] In the prior art, it is mentioned that the fault-tolerant control of the double-ended cascaded three-level inverter of the common bus has been deeply studied when the switching device is triggered and lost. The additional transient state generated by the inductive energy storage enables the fault-tolerant operation of up to 6 switching devices in the system when the trigger is lost; there is also a simplified SVPWM method based on the decomposition of the reference voltage, and the dual-terminal cascaded five-level system with independent bus structure The inverter is modulated, and a five-level SVPWM fault-tolerant modulation method is proposed. When a fault occurs, one side of the inverter is cut off, and the single-side inverter is used to drive the open-winding motor, which cannot achieve fault-tolerant operation when two inverters fail. , meanwhile, switching complex

Images