Semiconductor Module Case Overheat Detection Logic
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Solution Overview
Problem
Existing intelligent power modules (IPMs) require a dedicated temperature detection IC for case overheat detection, which limits the ability to detect overheating at multiple spots, leading to potential undetectable overheating issues.
Innovation Solution
A semiconductor module with multiple switching elements and diodes, integrated control circuits that include comparators for chip temperature detection and a logical AND circuit to determine case overheat by combining outputs from multiple temperature detection diodes, eliminating the need for a dedicated temperature detection IC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a dedicated temperature detection IC is used for case overheat detection, then case temperature can be detected, but the number of components increases and multiple spot detection capability is limited
Solution Approach 1:
The patent merges the case temperature detection function with the existing chip temperature detection diodes. Instead of using a separate dedicated temperature detection IC, the control circuits utilize the temperature detection diodes already present on the IGBT chips to infer case temperature through logical AND operations on multiple detection results, thereby eliminating the need for additional dedicated detection components.
Solution Approach 2:
The temperature detection diodes, originally designed solely for chip temperature monitoring, are given a dual function by also serving as case temperature detection elements. The control circuits process signals from multiple diodes to determine both chip and case temperatures, making the existing components multi-functional and avoiding additional component additions.
2Device complexity
If temperature detection is performed at a single spot, then component count is reduced, but overheating at other spots may remain undetected
Solution Approach 1:
The patent divides the temperature detection function into multiple independent detection points by utilizing temperature detection diodes associated with each IGBT chip. Each control circuit monitors its corresponding IGBT's temperature detection diode, creating multiple distributed detection spots across the module, thereby improving comprehensive overheat detection coverage without requiring a single complex detection system.
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
Enhances case overheat detection accuracy by directly monitoring chip temperatures and reducing component count, allowing for simultaneous control and shutdown of all IGBTs in response to overheating, while improving detection reliability across multiple spots.
Implementation Method 1
Temperature detection diodes having PN junctions are formed at the centers of the surfaces (emitter terminals) of the IGBTs 101 to 106, with insulating layers in between. Thereby, with regard to the IGBTs 101 to 106, chip temperature that is close to junction temperature can be observed by monitoring temperature-dependent forward voltage of the temperature detection diodes.
Implementation Method 2
The constant current generated by the constant current source 141 always flows in the temperature detection diode 107, and forward voltage corresponding to chip temperature of each IGBT 101 to 106 is applied to the inverting input terminal of the overheat detection comparator 142.
Data Source
AI summary
Control ICs for controlling IGBTs include overheat detection comparators that determine an overheated state of the case, in addition to overheat detection comparators that determine an overheated state of chips of the IGBTs. Outputs of the overheat detection comparators are input into an AND circuit, and when all of the overheat detection comparators determine the overheated state of the case, the AND circuit outputs a protection operation signal of high level, and an alarm output circuit outputs an alarm signal. The overheated state of the chips and the overheated state of the case are detected on the basis of chip temperatures measured by temperature detection diodes which are provided with the IGBTs respectively, and therefore a temperature detection IC for case overheat protection is unnecessary, and detection accuracy of the case overheat improves.