Cascaded H-Bridge Inverter Phase Shift Transformer Design
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Solution Overview
Problem
Conventional cascaded H-Bridge medium voltage inverters face challenges in efficiently insulating input power between unit power cells, leading to high Total Harmonic Distortion (THD) in input current, which is unsuitable for applications requiring lower THD levels.
Innovation Solution
A multi-winding transformer with a modified phase shift configuration, where the number of phase shifts corresponds to the total number of unit power cells rather than just those per phase, is introduced to reduce THD in the cascaded H-Bridge medium voltage inverter, achieving a 1-2% input current THD character.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional multi-winding transformer with phase shifts corresponding to unit power cells per phase is used, then device complexity is reduced, but input current THD increases to 3-4%
Solution Approach 1:
The patent changes the phase shift parameters of the multi-winding transformer from conventional configurations (corresponding to unit power cells per phase) to a new configuration where phase shifts correspond to the total number of unit power cells. This parameter modification transforms the harmonic characteristics of the input current, reducing THD from 3-4% to 1-2% while maintaining the same transformer structure.
2Power
If cascaded H-Bridge inverter is used for medium voltage applications, then power capacity is increased to several MW, but input current THD increases to 3-4%
Solution Approach 1:
The patent modifies the transformer phase shift parameters to correspond to the total number of unit power cells rather than per-phase configurations. This parameter change enables cascaded H-Bridge inverters operating at several MW power capacity to achieve low input current THD (1-2%), making them suitable for medium voltage applications where low harmonic distortion is required.
3Adaptability or versatility
If conventional transformer configuration is used, then ease of manufacture is improved, but applicability to high voltage systems (3000V, 3300V, 4150V) is limited due to high THD
Solution Approach 1:
The patent changes the phase shift parameters of the transformer to correspond to the total number of unit power cells, enabling the same transformer design to be applied across multiple voltage systems (3000V, 3300V, 4150V). This parameter modification reduces input current THD to 1-2%, making the inverter system applicable to high voltage industrial applications while maintaining manufacturing simplicity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively reduces input current THD from 3-4% to 1-2%, enabling the use of cascaded H-Bridge medium voltage inverters in applications like 3000V, 3300V, and 4150V systems by optimizing the transformer's phase shifts, resulting in improved harmonic distortion reduction.
Implementation Method 1
a multi-winding transformer with a modified phase shift configuration, where the number of phase shifts corresponds to the total number of unit power cells
Data Source
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AI summary
The present disclosure proposes an input power of each unit power cell of a cascaded H-bridge inverter that is mutually insulated. To this end, the present disclosure includes a phase shift transformer configured to output a voltage of predetermined phase by receiving an AC input power having a fixed frequency, and a plurality of unit power cells serially-connected configured to output a voltage having a predetermined phase by receiving a voltage provided by the phase shift transformer, wherein the phase shift transformer is configured to include the number of phase shifts corresponding to the number of the plurality of unit power cells.