Power Semiconductor Temperature Sensing With a Shared Emitter Terminal
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Solution Overview
Problem
Conventional power semiconductor circuits require separate temperature and current sensors, increasing space requirements and the number of terminals, and do not accurately measure the internal temperature of the semiconductor components.
Innovation Solution
Integrate a temperature sensor, such as a temperature diode, within the power semiconductor element, with its cathode connected to the emitter electrode, allowing temperature measurement via a single terminal, and use internal resistances for current measurement, eliminating the need for additional terminals and space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate temperature sensor chip is mounted on the housing or heat sink, then the temperature measurement is simplified, but the temperature measured is not the actual internal temperature of the semiconductor component
Solution Approach 1:
The temperature sensor is integrated directly into the semiconductor component structure, merging the sensing function with the power component itself. This eliminates the need for separate sensor chips mounted on housings or heat sinks, and enables direct measurement of the actual internal temperature where the power loss occurs.
2Measurement precision
If a temperature sensor is arranged inside the module next to the IGBT chip, then the internal temperature can be measured, but the space requirement increases and the area for the semiconductor component is reduced
Solution Approach 1:
The temperature sensor is merged with the IGBT chip structure itself, using the same semiconductor substrate. This integration eliminates the need for additional space within the module, as the sensing elements are formed directly on the power component chip rather than requiring separate mounting areas.
Solution Approach 2:
The semiconductor chip serves dual functions: as the power switching element (IGBT) and as the temperature sensing element. The same chip structure that handles power conversion also provides temperature measurement capability, eliminating the need for dedicated sensor space.
3Measurement precision
If separate terminals are provided for temperature and current measurement, then the measurements can be performed independently, but the number of terminals increases
Solution Approach 1:
The emitter electrode serves multiple functions: as the main power output terminal and as the reference terminal for both temperature and current measurements. By using the existing emitter electrode as a common reference point, the patent enables independent temperature and current measurements without requiring additional dedicated terminals.
Solution Approach 2:
The measurement functions for temperature and current are combined by using the same emitter electrode as reference. The temperature sensor shares the emitter electrode connection, and the current measurement also uses the emitter electrode as reference, merging the terminal usage while maintaining measurement independence through different measurement paths.
4Measurement precision
If 1/2000 to 1/1000 of the IGBT cells are placed on a separate terminal for current measurement, then the excess current can be determined, but the cells are not available for the actual IGBT task and additional space is required
Solution Approach 1:
Instead of extracting actual IGBT cells for current measurement, the patent extracts only the sensing function by using the voltage drop across the emitter electrode. This virtual sensing approach extracts measurement capability without removing functional IGBT cells, maintaining full productive capacity while enabling precise current measurement.
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 accurate temperature and current measurement with a single terminal, reducing space and terminal count, and allows for detection of excess temperature and current, protecting the semiconductor component.
Implementation Method 1
measuring a voltage Vf between a measurement terminal and a first emitter terminal in the off-state of the power semiconductor element; determining a temperature T as a function of the temperature voltage Vf
Implementation Method 2
the internal resistance RF of the at least one bond wire (45) and/or of the at least one DCB conductor track (50) is used as measurement resistance Rsense, by means of which a collector current iC or a load current iL can be determined
Data Source
AI summary
A power semiconductor circuit includes: a power semiconductor element having a gate electrode configured to actuate the power semiconductor element, a collector electrode, and an emitter electrode electrically connected to a first emitter terminal; and a temperature sensor having a first measurement point with a measurement terminal and a second measurement point electrically connected to the emitter electrode, so that a voltage which drops over the temperature sensor is measurable between the measurement terminal and the first emitter terminal for the temperature measurement. Corresponding methods for determining a temperature of a power semiconductor element and for determining a sign of a load current in a bridge circuit are also described.