Fault-tolerant modulation method for co-busbar double-end cascade type five-level inverters

Abstract

The invention discloses a fault-tolerant modulation method for co-busbar double-end cascade type five-level inverters. The method includes the steps that a stator winding of a motor is opened, the two ends of the stator winding are powered up by the two inverters which are completely the same, the two inverters share one set of direct-current busbar, and accordingly the co-busbar double-end cascade type five-level topology is formed; in order to ensure that the reference voltage vector track of each inverter is a circle, when short-circuit trouble happens to a switching device, the maximum output voltage of the inverter is lowered to be half of the voltage before, and only the inside hexagon available switching state is used for synthesizing the reference voltage vector; through rotation and per-unit treatment of a coordinate system, the five-level modulation method is effectively simplified, and the hardware requirement for system control is reduced; by the adoption of equilibrium factors, midpoint potential balance is achieved on the premise that fault-tolerant control is guaranteed. Based on the high-fault-tolerant characteristic of the double-end cascade type five-level inverters, when the switching device breaks down, fault-tolerant operation of the inverters is achieved by reselecting the voltage vector. An optimized 60-degree modulation method is provided according to the double-end cascade type system.

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 studie

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