Power Converter Commutating Means for Backflow Current Management
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Solution Overview
Problem
Highly-efficient elements with large electric-current capacity face challenges due to high costs and crystal defects, making it difficult to implement them in power converting devices for high-power applications, such as air-conditioning compressors, leading to inefficiencies and increased losses from backflow recovery electric currents.
Innovation Solution
A power converting device with commutating means that redirects backflow electric current to a different path, reducing recovery losses and incorporating protection mechanisms to ensure reliability and safety during component failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If highly-efficient elements with large electric-current capacity are used, then efficiency is improved, but cost increases and crystal defects occur
Solution Approach 1:
The patent introduces a commutating means as an intermediary component between the backflow preventing element and the power supply. This commutating means (comprising switching elements and inductors) redirects recovery electric current through an alternative path, preventing it from flowing through the backflow preventing element. This resolves the contradiction by enabling the use of efficient elements while protecting them from damaging recovery currents through the intermediary commutation circuit.
2Loss of energy
If new highly-efficient elements are implemented, then efficiency is improved, but it takes time to become popular due to high costs and crystal defects
Solution Approach 1:
The patent implements protection mechanisms beforehand to cushion against potential failures of new highly-efficient elements. The commutating means is configured to detect abnormal conditions (such as excessive recovery current) and automatically redirect current through alternative paths before damage occurs. This prior cushioning approach enables safer adoption of new elements by preventing crystal defects and failures, thereby improving manufacturing feasibility while maintaining efficiency benefits.
3Reliability
If backflow preventing elements are used to stop reverse current, then protection is provided, but recovery electric current loss increases
Solution Approach 1:
The patent segments the current path into two separate routes: one for normal operation through the backflow preventing element, and another for recovery current through the commutating means. By dividing the current flow paths, the system maintains the protective function of the backflow preventing element while eliminating energy loss through alternative commutation paths. This segmentation allows both backflow prevention and low loss to coexist.
Data Source
Figure 1~2
Figure 3
Figure 4(a)~4(c)
AI summary
A power converting device includes a rectifying circuit 2 that rectifies voltage of an alternating-current power supply 1; smoothing means 8 that smoothes output voltage from the rectifying circuit 2; short-circuiting means 4 that is disposed more closely to the alternating-current power supply 1 than the smoothing means 8 and that short-circuits the alternating-current power supply 1 and controls at least one of electric current and voltage; a reactor 3 that is disposed more closely to the alternating-current power supply 1 than the short-circuiting means 4; one or more backflow preventing elements 5 that prevent electric current from flowing backward from a load 9 side toward the alternating-current power supply 1; commutating means 7 for performing a commutation operation for causing electric current to flow toward a different path that is connected in parallel with the one or more backflow preventing elements 5; malfunction detecting means 105 for detecting a malfunction of the commutating means 7; and switching control means 103 that performs operation control of the commutating means 7 in accordance with detection by the malfunction detecting means 105.