2-in-1 Chopper Module Diode Area Asymmetry
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Solution Overview
Problem
The two-in-one type chopper module experiences a reduction in temperature cycle life of its wiring due to a significant temperature difference between the IGBT and diode elements, as the diode element on the insulating substrate receives less heat, leading to a lower temperature side temperature.
Innovation Solution
Incorporating a second diode with a larger effective area than the first diode, both connected in a configuration where the switching transistor and first diode have identical power losses, ensuring the insulating substrate with the second diode receives heat only during current conduction, thereby reducing the temperature difference and increasing the temperature cycle life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the chopper module uses only a diode element on the insulating substrate, then the device complexity is reduced, but the temperature difference between high and low temperature sides increases, reducing the temperature cycle life of the wiring
Solution Approach 1:
The patent applies local quality by making the second diode have a larger effective area than the first diode. This creates a localized difference in heat generation characteristics - the second diode generates less heat due to its larger area, which compensates for the reduced heat reception from the insulating substrate. This local modification resolves the temperature cycle life issue without changing the overall simple structure of having only diodes on the insulating substrate.
2Temperature
If the second diode has a larger effective area, then the high temperature side temperature decreases, but the device structure becomes more complex
Solution Approach 1:
The patent implements local quality by selectively designing the second diode with a larger effective area compared to the first diode. This localized structural difference targets specifically at reducing the high temperature side temperature of the second diode without requiring complex overall device redesign. The asymmetry in diode areas is a simple yet effective local modification.
Solution Approach 2:
The patent applies asymmetry by creating diodes with different effective areas - the second diode has a larger area than the first diode. This asymmetric design is intentionally used to create different thermal characteristics in different parts of the circuit, allowing the second diode to operate at a lower high temperature side temperature while maintaining overall device 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 ensures a similar current flow in the switching transistor and first diode, with the second diode generating less heat, resulting in a decreased high temperature side temperature and an increased temperature cycle life for the wiring connected to the second diode.
Implementation Method 1
the second diode has an amount of heat generation smaller than the first diode, and has a decreased high temperature side temperature
Data Source
AI summary
An object of the present invention is to suppress reduction in a temperature cycle life of a wiring in a two-in-one type chopper module. A two-in-one type chopper module according to the present invention includes: a switching transistor; a first diode inverse-parallelly connected to the switching transistor; a second diode serially connected to the switching transistor and the first diode; a first wiring pattern mounting the switching transistor and the first diode; and a second wiring pattern mounting the second diode, wherein each of the switching transistor and the first diode has a power loss substantially identical with each other at a time of a forward direction current conduction, and an effective area of the second diode is larger than an effective area of the first diode.