Three-Level Converter NPC Bridge Arm Layout for Balanced IGBT Loss
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Solution Overview
Problem
Existing NPC three-level converters experience uneven loss distribution among IGBT devices, complicating heat sink design and increasing costs due to the need for separate heat dissipation designs for different NPC bridge arms.
Innovation Solution
The solution involves adjusting the number of NPC bridge arms based on the loss ratio between different arms, ensuring that the number of IGBT devices controlled by each third NPC bridge arm is adjusted to balance the losses, thereby distributing losses evenly across the converter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the number of NPC bridge arms in each unit is kept equal for simplicity, then the device structure is simple, but the losses of IGBT devices are unevenly distributed
Solution Approach 1:
The patent applies local quality by differentiating the number of NPC bridge arms across different units based on their specific loss characteristics. The first and second units each contain a first number of bridge arms, while the third unit contains a second number of bridge arms determined by the loss ratio, creating localized structural variations that optimize overall system performance.
Solution Approach 2:
The patent changes the structural parameter (number of NPC bridge arms) based on the loss ratio between different units. By adjusting this parameter according to measured or calculated loss ratios, the system achieves uniform loss distribution across all IGBT devices while maintaining practical device complexity.
2Loss of energy
If separate heat dissipation designs are created for different NPC bridge arms to address uneven losses, then the loss distribution becomes uniform, but the device complexity increases
Solution Approach 1:
The patent implements local quality by creating distinct NPC bridge arm configurations in different units. Units with higher losses contain more bridge arms to distribute the thermal load, while units with lower losses have fewer bridge arms, resulting in localized structural adaptations that achieve uniform loss distribution.
Solution Approach 2:
The patent segments the converter into multiple units with differentiated bridge arm configurations. This segmentation allows each unit to be optimized independently based on its loss characteristics, with the third unit having a different number of bridge arms to balance the overall system losses.
3Loss of energy
If more IGBT devices are added to balance losses, then the loss distribution becomes uniform, but the quantity of devices increases
Solution Approach 1:
The patent changes the number of NPC bridge arms in the third unit based on the loss ratio, which directly adjusts the number of IGBT devices required. This parameter adjustment achieves uniform loss distribution while optimizing the total quantity of devices by adding only the necessary number of bridge arms and IGBTs.
Solution Approach 2:
The patent applies local quality by concentrating additional IGBT devices only in the third unit where needed to balance losses, rather than uniformly distributing devices across all units. This localized approach achieves loss uniformity with minimal increase in total device quantity.
Data Source
AI summary
The present application provides a power component of a three-level converter, a three-level converter and a wind turbine. The power component of the three-level converter includes: a first NPC bridge arm unit including a plurality of first NPC bridge arms connected in parallel; a second NPC bridge arm unit including a plurality of second NPC bridge arms connected in parallel; and a third NPC bridge arm unit including a plurality of third NPC bridge arms connected in parallel. The number of the second NPC bridge arms is the same as the number of the first NPC bridge arms, and the number of the third NPC bridge arms is determined based on the ratio of the loss of the first NPC bridge arm to the loss of the third NPC bridge arm.