Power Semiconductor Lifetime Sensing via Diode Voltage Compensation
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Solution Overview
Problem
Existing methods for monitoring power semiconductor device degradation require circuit interruption or are susceptible to noise, making them unreliable and complex.
Innovation Solution
An electrical circuit arrangement using a first diode and a semiconductor switching device in series, with a second diode and calibration switching element, measures voltage differences to derive lifetime expectancy by decoupling from high voltages and compensating temperature effects, utilizing existing circuit resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If physical methods are used to measure temperature directly using thermal sensors or thermal imaging, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces physical/thermal measurement methods with electrical parameter monitoring. Instead of using thermal sensors or thermal imaging to directly measure temperature, the system monitors temperature-sensitive electrical parameters (such as forward voltage of the diode) that correlate with temperature and device degradation. This substitution of electrical measurement for physical measurement reduces circuit complexity while maintaining measurement capability.
2Device complexity
If methods monitor temperature-sensitive electrical parameters, then device complexity is reduced, but reliability deteriorates due to noise susceptibility and operation interruption requirements
Solution Approach 1:
The patent introduces a diode as an intermediary sensing element that is electrically coupled to the power semiconductor device. The diode's forward voltage serves as a mediator that reflects both temperature conditions and device degradation state. By monitoring the diode's electrical characteristics rather than directly measuring temperature or device parameters, the system achieves reliable degradation monitoring without interrupting normal operation and with reduced noise susceptibility.
Solution Approach 2:
The patent uses a second diode in a compensation path that replicates the electrical characteristics of the first diode. This creates a reference copy that experiences similar temperature conditions but is not subjected to the same measurement disturbances. By comparing the electrical parameters of the first diode (in the load path) with the second diode (in the compensation path), the system compensates for noise and temperature variations, thereby improving measurement reliability.
3Reliability
If a diode is used to decouple the voltage acquisition circuit from high voltages, then reliability is improved, but measurement precision deteriorates due to diode voltage drops
Solution Approach 1:
The diode serves as an intermediary element that provides voltage isolation while its own voltage characteristics are monitored and compensated for. The diode's forward voltage drop is not treated as an error to be eliminated but as a useful signal that contains information about temperature and device degradation. By measuring the diode's voltage characteristics and using them as the basis for degradation assessment, the system turns the isolation element's voltage drop from a source of measurement error into a valuable diagnostic parameter.
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
Provides highly reliable lifetime expectancy information with low circuit complexity by minimizing temperature-dependent offsets and sharing resources with existing gate driver circuits.
Implementation Method 1
The first diode decouples the voltage acquisition circuit from high voltages in the load path of the semiconductor switching device
Implementation Method 2
The voltage difference ΔV follows the on-resistance RDSOn of the semiconductor switching device and a drift of the voltage difference ΔV images a drift of the on-resistance RDSOn
Data Source
AI summary
An electrical circuit arrangement includes a first diode and a semiconductor switching device electrically connected in series between a first node and a second node. The semiconductor switching device controls a switch current that includes a forward current through the first diode and a load current. A second diode and a calibration switching element are electrically connected in series between the first node and the second node. A voltage acquisition circuit obtains a voltage difference between a first voltage between the first node and the second node when the semiconductor switching device is on and the calibration switching element is off and a second voltage between the first node and the second node when the calibration switching element is on and the semiconductor switching device is off.