Universal pulse width modulation method for multi-level inverter

Abstract

A universal pulse width modulation method for a multi-level inverter includes the following steps: a, carrying out per unit of reference input voltages; b, calculating a two-level space vector pulse width modulation duty ratio; c, calculating in which layer a reference voltage vector is on; d, performing vector reverse mapping; e, inhibiting common-mode voltages; and f, generating pulse-width modulated waves. A voltage vector switching time duty ratio of an inverter is calculated by a simple two-level space voltage vector modulation algorithm, then vector compression is performed on the duty ratio, a mapping relation based on the voltage vector and level is established, and multi-level voltage conversion can be effectively achieved through the series of conversion. Through level conversion, the voltage vector that has a common-mode voltage inhibition capability can be output easily and quickly, and a specific pulse width modulation output state is selected to prevent generation of common-mode voltages, thereby effectively inhibiting common-mode components included in output voltages of a multi-level inverter.

Description

Technical field [0001] The invention belongs to the technical field of power electronics, and relates to a general pulse width modulation method for a multi-level inverter. Background technique [0002] In recent years, inverter power supply technology has been widely used in the field of AC motor drive. The inverter can effectively achieve motor frequency conversion and amplitude modulation voltage control. For medium and high power transmission devices, such as electric locomotives and ship propulsion, compared with traditional two-level voltage source inverters, the application of multi-level inverters has many advantages: lower power switch stress, lower Inverter output voltage harmonic distortion, lower output voltage pulsation and less electromagnetic interference. Research on multilevel inverters pays more attention to three topological structures: series H-bridge multilevel inverters, neutral point clamped multilevel inverters and dual inverters based on open-phase AC mo...

AI Technical Summary

Problems solved by technology

However, there are still some problems in the application of multi-level inverters that need to be further resolved: pulse width modulation technology implementation algorithm complex, large modulation technology calculation load, capacitor voltage imbalance on the DC side of the inverter, and the presence of common-mode voltage and Common mode current interference issues, etc.

[0004] In the existing multi-level inverter power supply technology, the common mode voltage problem will cause the motor shaft voltage, bearing current and induced electromagnetic interference. At present, relevant researchers have conducted a lot of research on this problem, but the current The solution techniques are more complex or computationally intensive

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