Semiconductor Device Inverter Reflux Noise Suppression
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Solution Overview
Problem
Conduction noise in semiconductor devices, particularly in HERIC circuits, is exacerbated by potential fluctuations caused by differing turn-off timings of switching elements, leading to increased thermal noise and reduced efficiency.
Innovation Solution
Incorporating impedances between freewheel diodes and terminals in the semiconductor device, ensuring these impedances are greater than parasitic wiring impedance, to manage current flow and mitigate potential fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the HERIC circuit is used to improve heat radiation and reduce switching loss, then thermal efficiency is improved, but conduction noise increases due to potential fluctuations at output terminals
Solution Approach 1:
The patent introduces a clamp element as an intermediary component in the reflux section of the HERIC circuit. This clamp element acts as a mediator that suppresses excessive voltage fluctuations at the output terminals during reflux operation, thereby reducing conduction noise while maintaining the thermal efficiency benefits of the HERIC circuit configuration
2Loss of energy
If switching elements are operated at different timing to enable reflux current flow, then switching loss is reduced, but potential fluctuation at output terminals increases
Solution Approach 1:
The clamp element is pre-configured in the circuit to provide preliminary counter-action against excessive voltage fluctuations. When reflux current flows due to different switching timings, the clamp element is already in position to suppress potential fluctuations at the output terminals, preventing conduction noise before it occurs
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
The solution effectively reduces conduction noise and potential fluctuations at output terminals, enhancing the thermal design and operational efficiency of semiconductor devices.
Implementation Method 1
impedance provided between each of the freewheel diodes of an upper arm and the output terminals, and impedance provided between each of the freewheel diodes of a lower arm and an input terminal in the inverter section
Implementation Method 2
parasitic impedance of wiring assuming that the first switching elements and the output terminals or the first switching elements and the input terminal are connected only by wiring
Data Source
AI summary
The object of the present disclosure is to suppress the conduction noise in a semiconductor device. A semiconductor device includes an inverter section being a full-bridge inverter, and a reflux section that short-circuits between output terminals U and V of the inverter section, in which impedances and are provided between each of freewheel diodes and of the upper arm and the output terminals U and V, and impedances and are provided between the freewheel diodes and of the lower arm and the input terminal N of in the inverter section, and the impedances to are greater than parasitic impedance of wiring assuming that IGBTs to and the output terminals U and V or the IGBTs and the input terminal N are connected only by the wiring.