Power Switch Infrared Sensing for Delay-Free Junction Temperature
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Solution Overview
Problem
Existing methods for temperature measurement of semiconductor substrates in power switches, such as MOSFETs and IGBTs, suffer from time delays due to thermal capacitance differences, leading to premature or late protective shutdowns and limited power output, and are inaccurate and complex, especially at higher voltages.
Innovation Solution
An integrated infrared sensor is used within the power switch assembly to detect temperature directly and instantaneously, galvanically isolated from the semiconductor substrate, eliminating the need for additional hardware and allowing temperature measurement without current flow, thereby avoiding thermal destruction and enabling full operational range utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an NTC sensor is used to measure temperature indirectly, then temperature measurement is possible, but time delay occurs due to thermal capacitance differences between PCB, transistor housing, and sensor
Solution Approach 1:
The patent extracts the temperature sensing function from the indirect NTC sensor approach and implements it directly within the semiconductor substrate using an integrated sensor. This eliminates the thermal capacitance delays of external components (PCB, housing) by measuring temperature at the source - the semiconductor substrate itself - thereby resolving the time delay problem while maintaining measurement accuracy.
Solution Approach 2:
The sensor is nested directly within the semiconductor substrate structure, with the sensor embedded in the substrate and the chamber positioned between the sensor and substrate to provide galvanic isolation. This nested configuration enables direct temperature measurement at the heat source without external thermal pathways, eliminating the time delays inherent in indirect measurement methods.
2Measurement precision
If voltage drop and current flow measurement is used to derive temperature, then temperature can be determined, but hardware complexity increases and additional components are required
Solution Approach 1:
The patent merges the temperature sensing function with the existing semiconductor substrate and power switch circuitry. The sensor is integrated directly into the substrate, and the chamber structure serves dual purposes: providing galvanic isolation and enabling optical access for temperature measurement. This consolidation eliminates the need for separate voltage drop measurement circuits, current sensors, and associated isolation hardware, thereby reducing overall system complexity.
Solution Approach 2:
The patent replaces the electrical measurement approach (voltage drop and current flow measurements requiring galvanic isolation) with an optical-based infrared sensing system. The infrared sensor detects thermal radiation from the semiconductor substrate through the chamber, eliminating the need for complex electrical isolation circuits and additional measuring components while maintaining temperature measurement capability.
3Reliability
If NTC sensor is placed in close proximity to power switch, then temperature measurement is possible, but protective shutdown may be too late or too early causing premature aging or destruction
Solution Approach 1:
The patent extracts the temperature measurement function from the indirect NTC sensor location and implements it directly at the semiconductor substrate source. By placing the sensor within the substrate itself, the system obtains immediate temperature data without the thermal capacitance delays of external components, enabling protective shutdown decisions to be made based on real-time temperature conditions rather than delayed thermal signals.
Solution Approach 2:
The integrated sensor provides immediate feedback on the actual semiconductor substrate temperature to the control system. This real-time feedback enables the control system to make accurate protective shutdown decisions based on actual thermal conditions, preventing both premature shutdown (which would occur with delayed or inaccurate temperature data) and late shutdown (which would allow thermal destruction).
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 solution provides accurate, delay-free temperature detection, minimizing hardware failure rates and costs, while ensuring safe and efficient operation of power switches across their entire operational range.
Implementation Method 1
The temperature measurement is achieved by incorporating an infrared sensor (e.g., infrared receiver diode or transistor) into the switch in such a way that the infrared radiation from the silicon may be detected by the sensor.
Data Source
AI summary
A temperature measurement and a method for measuring the temperature of a semiconductor substrate, or semiconductor substrate, of a power switch assembly, which is delay free. The power switch assembly includes a circuit and a printed circuit board (PCB), where the circuit is mounted to the PCB. A lead frame is part of the circuit, at least one semiconductor substrate is part of the circuit and mounted to the lead frame, and a sensor is part of the circuit and mounted to the lead frame. A chamber is located between the sensor and the semiconductor substrate, such that the chamber galvanically isolates the sensor from the semiconductor substrate. The sensor detects the temperature of the semiconductor substrate.