Power Converter Fuse Control for Selective Short-Circuit Isolation
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Solution Overview
Problem
In power conversion devices, when a short-circuit failure occurs in a switching element, existing systems blow all fuses corresponding to the phases, leading to a loss of power supply and inability to drive the load.
Innovation Solution
A power conversion device with parallel upper and lower arm circuits, each with a series-connected switching element and a fuse that blows at a predetermined rated current, includes a short-circuit failure location determination unit and a fuse blowout-time current control unit to selectively control current flow and blow only the fuse at the failure location.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fuse is provided between DC power supply and inverter circuit to prevent co-failure, then reliability is improved, but all fuses are blown regardless of failure location causing loss of power supply
Solution Approach 1:
The patent segments the fuse protection function by providing separate fuses for each phase (U-phase, V-phase, W-phase) instead of a single common fuse. This allows selective blowing of only the fuse corresponding to the failed switching element, maintaining power supply to healthy phases and enabling continued operation of the inverter circuit.
2Reliability
If a switching element is turned on to generate short-circuit current, then fuse blowout is achieved, but current control becomes difficult and excessive current may flow
Solution Approach 1:
The patent applies local quality by directing the short-circuit current flow specifically through the failed switching element's phase path. By controlling other switching elements to route current through the fuse of the failed phase, the system achieves effective fuse blowout while maintaining controlled current flow that prevents excessive current damage to healthy components.
Data Source
AI summary
A power conversion device includes a power conversion circuit in which upper and lower arm circuits in which switching elements are connected in series are connected in parallel for at least three phases, a plurality of fuses that are connected in series with the switching elements of the respective phases of the power conversion circuit and blown at a predetermined rated current or more, a short-circuit failure location determination unit that determines a short-circuit failure location of the switching element, and a fuse blowout-time current control unit that controls driving of another switching element different from the switching element so that a current flowing through the switching element determined to be the short-circuit failure location by the short-circuit failure location determination unit becomes equal to or more than the rated current of the fuse.