IGBT Temperature Sense Circuit Automatic Calibration
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Solution Overview
Problem
Existing IGBT temperature sense circuits face errors in accurately estimating junction temperatures due to variations in silicon diodes, leading to limited maximum current output and potential safety risks in electric vehicles, especially when current sensors fail or erroneously estimate temperatures at the end of life.
Innovation Solution
An IGBT temperature sense circuit with an automatic calibrator that adjusts the supply current to a diode temperature sensor, minimizing errors by compensating for offset variations in turn-on voltage characteristics across different samples, allowing for precise temperature measurement and operation adjustment of the IGBT chip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a poly-silicon diode is integrated on an IGBT chip to directly sense the junction temperature, then temperature sensing capability is improved, but measurement precision deteriorates due to variation between samples
Solution Approach 1:
The patent applies preliminary calibration action by measuring the turn-on voltage of each diode at a predetermined temperature (e.g., 25°C) before actual operation. This preliminary measurement establishes a baseline voltage value that is stored in memory. During operation, the controller compares the actual turn-on voltage against this baseline to calculate temperature, thereby compensating for sample-specific variations and improving measurement precision without sacrificing temperature sensing capability.
2Reliability
If a thermal model is used to calculate maximum output, then temperature protection is improved, but productivity deteriorates due to limited maximum current
Solution Approach 1:
The patent implements dynamic current adjustment by continuously monitoring the diode's turn-on voltage and calculating real-time temperature. Based on the calculated temperature, the controller dynamically adjusts the maximum allowable current output of the IGBT. This dynamic approach replaces static thermal models with flexible current limiting, maintaining reliable temperature protection while maximizing current output within safe thermal boundaries, thereby improving productivity without sacrificing reliability.
3Temperature
If temperature sensing is performed using diode voltage characteristics, then temperature measurement capability is improved, but reliability deteriorates due to offset variations in turn-on voltage
Solution Approach 1:
The patent implements feedback by continuously measuring the turn-on voltage of the diode, comparing it against the baseline voltage stored from preliminary calibration, and using the voltage difference to calculate temperature compensation. This feedback mechanism automatically adjusts for offset variations in turn-on voltage across different samples and operating conditions, maintaining reliable temperature estimation accuracy while preserving the temperature measurement capability of the diode-based sensing 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
The solution enables more accurate temperature sensing, increases the maximum current output of IGBTs, and enhances safety by stabilizing over-temperature protection, preventing thermal destruction and improving driver safety in eco-friendly electric vehicles.
Implementation Method 1
a poly-silicon diode is integrated on an IGBT chip to directly sense the junction temperature of the IGBT semiconductor chip
Data Source
AI summary
An IGBT temperature sense circuit is provided. The IGBT temperature sense circuit automatically calibrates a temperature sense of a diode to minimize an error based on element characteristics of a temperature sense diode, precisely senses the temperature and removes a limit of a maximum current (to increase the maximum current) of an output of an IGBT. A temperature sense circuit includes an automatic calibrator that is configured to supply current of a current source to a current to a diode and a diode temperature sensor that is configured to measure a voltage of one side terminal of the diode based on the current of the diode based on a change of a temperature and adjustment of an operation of a protection object device.