Power Semiconductor Over-Temperature Sensing With Current Pulses
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Solution Overview
Problem
Existing methods for sensing over-temperature in power semiconductors are complex, imprecise, or not compatible with real-time detection, leading to potential thermal runaway and irreversible failure.
Innovation Solution
A device and method using a current pulse source, current copier, emulating device, and comparator to sense over-temperature by comparing voltages across control electrodes and an emulating device, without requiring analog-to-digital conversion, allowing for fast and accurate detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If embedded diodes are used for temperature sensing, then temperature detection capability is provided, but the transistor available active area is reduced and the number of connections increases
Solution Approach 1:
The power semiconductor device itself serves as the temperature sensor by utilizing its intrinsic electrical parameters (such as threshold voltage or on-state voltage) that vary with temperature. This eliminates the need for separate embedded diodes or temperature sensing components, thereby preserving transistor active area and reducing connection requirements while maintaining temperature detection capability
Solution Approach 2:
The power semiconductor device performs dual functions: power switching/ amplification and temperature sensing. By exploiting the temperature dependence of its electrical characteristics, the same device structure serves both power processing and thermal monitoring purposes, avoiding additional components and connections
2Measurement precision
If thermocouples or negative temperature coefficient resistors are used for direct junction temperature measurement, then temperature measurement capability is achieved, but the bandwidth is limited and they cannot be placed close to the power semiconductor
Solution Approach 1:
The power semiconductor's own electrical parameters are used as the temperature sensor, eliminating the need for external thermocouples or resistors. This allows instantaneous temperature measurement at the junction location with unlimited bandwidth, as the measurement is performed electrically through the device terminals without requiring physical proximity constraints
Solution Approach 2:
The mechanical/physical temperature sensing methods (thermocouples, resistors requiring physical placement) are replaced with electrical parameter-based sensing. By measuring voltage or current characteristics that vary with temperature, the system achieves high-speed temperature detection without the bandwidth limitations and placement constraints of physical sensors
3Measurement precision
If optical measurements are used for temperature detection, then non-contact measurement is achieved, but digital treatment and calibration increase latency
Solution Approach 1:
Optical measurement systems requiring complex digital processing are replaced with direct electrical parameter measurement. By utilizing the inherent temperature dependence of electrical characteristics (such as threshold voltage shift), the system achieves temperature detection through simple voltage or current measurements that require minimal processing, thereby reducing latency while maintaining measurement accuracy
4Measurement precision
If measurement current is injected into active power semiconductor to measure on-state voltage, then temperature information is obtained, but measurement circuit complexity increases and precision may be insufficient causing false triggers
Solution Approach 1:
A periodic test signal (such as a brief gate pulse) is applied to the power semiconductor during normal operation to extract temperature information. By using periodic, controlled excitation signals rather than continuous measurement, the system obtains temperature data with sufficient precision while minimizing interference with normal operation and reducing the complexity of measurement circuits
Solution Approach 2:
The temperature information extracted from electrical parameters is fed back to adjust operating conditions or trigger protective actions. By implementing feedback mechanisms that monitor electrical characteristics and respond to temperature changes, the system achieves accurate temperature measurement with reduced circuit complexity, as the feedback loop naturally compensates for measurement variations and prevents false triggers
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
Enables low-complexity, accurate over-temperature sensing in power semiconductors, preventing thermal runaway without additional hardware and minimizing interference, with adjustable threshold settings for precise detection.
Implementation Method 1
the temperature of the power semiconductor may be observed by the injection of a measurement current into the active power semiconductor to measure the on-state voltage that is dependent of the temperature
Implementation Method 2
a comparator that compares the voltage across the control electrodes to the voltage across the emulating device
Data Source
AI summary
The present invention concerns a device and a method for sensing an over-temperature of a power semiconductor. The invention: provides a current pulse source through control electrodes of the power semiconductor, duplicates the current provided by the current pulse source and provides the duplicated current to an emulating device, compares the voltage across the control electrodes to the voltage across the emulating device, notifies the result of the comparison.