Integrated Current Sensor in Power Semiconductor Module
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Solution Overview
Problem
Existing current sensors for power semiconductor modules face inaccuracies due to temperature fluctuations, bulkiness, high costs, and limited measurement bandwidth, especially when measuring AC and DC currents, and require external installation which occupies space and complicates assembly.
Innovation Solution
An integrated current sensor system within the power semiconductor module using point field detectors and a decoupling circuit to accurately measure currents, minimizing cross-coupled magnetic fields and utilizing lead frames to shape magnetic fields for improved measurement accuracy and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external current sensors are used to measure current in power semiconductor modules, then current measurement capability is provided, but the module occupies additional space and assembly becomes complicated
Solution Approach 1:
The patent integrates the current sensor directly into the power semiconductor module by incorporating a magnetic field detector onto the same substrate as the power semiconductor devices. The detector is positioned to sense magnetic fields generated by current flow in the power devices, eliminating the need for separate external sensors and simplifying assembly while maintaining measurement capability.
2Measurement precision
If traditional current sensors are used, then current measurement is achieved, but measurement bandwidth is limited especially for AC and DC currents
Solution Approach 1:
The patent replaces traditional magnetic field-based sensing mechanisms with a capacitor-based sensing approach. The detector measures changes in capacitance caused by electric field variations around the power semiconductor devices during switching operations. This electrical field-based measurement method provides broader bandwidth for both AC and DC current measurements while maintaining accuracy, overcoming the limitations of magnetic field-based sensors.
3Measurement precision
If shunt resistors are used for current measurement, then current can be measured using Ohm's law, but the sensors are susceptible to inaccuracy due to temperature fluctuation and flux coupling
Solution Approach 1:
The patent replaces resistive current sensing with capacitive/electrical field-based sensing. Instead of measuring voltage drop across a shunt resistor (which is temperature-sensitive), the detector measures electric field variations caused by current flow. This substitution eliminates the temperature dependency inherent in resistive sensors while providing accurate current measurement through capacitance change detection.
4Measurement precision
If current transformers or Hall-effect transducers are used, then magnetic field based sensing is achieved, but the sensors are bulky and costly due to ferromagnetic cores
Solution Approach 1:
The patent replaces magnetic field-based sensing requiring ferromagnetic cores with electrical field-based sensing using a capacitor. The detector measures electric field variations directly in the vicinity of the power semiconductor devices during switching. This eliminates the need for bulky ferromagnetic cores, reducing sensor size and cost while maintaining the ability to sense current through field 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
The system provides accurate and efficient current measurement with reduced space requirements, improved assembly simplicity, and enhanced measurement bandwidth across a range of frequencies, addressing the limitations of traditional current sensors.
Implementation Method 1
a point field detector sensing a magnetic field generated in response to a current flowing in an electrical conductor within the power semiconductor module
Implementation Method 2
A lead frame conductor may be provided to shape the magnetic field to a desired field strength and a desired bandwidth
Implementation Method 3
A decoupling circuit may be provided to decouple a magnetic field generated in response to the current flowing in the electrical conductor within the power semiconductor module from a magnetic field generated in response to a second current conducted within the power semiconductor module
Data Source
AI summary
An improved system for measuring current within a power semiconductor module is disclosed, where the system is integrated within the power module. The system includes a point field detector sensing a magnetic field resulting from current flowing in one phase of the module. A lead frame conductor may be provided to shape the magnetic field and minimize the influence of cross-coupled magnetic fields from currents conducted in other power semiconductor devices within one phase of the module. Optionally, a second point field detector may be provided at a second location within the module to sense a magnetic field resulting from the current flowing in the same phase of the module. Each phase of the power module includes at least one point field detector. A decoupling circuit is provided to decouple multiple currents flowing within the same phase or to decouple currents flowing within different phases of the power module.