Integrated Power Module Current Measurement via Shunt Resistor
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Solution Overview
Problem
Conventional power supply circuits face challenges in accurately measuring current due to the influence of wiring patterns, which also result in high costs due to the use of expensive Rogowski coils and inability to detect current magnitude effectively.
Innovation Solution
A power module is designed with a first switching device, a current-voltage conversion circuit, and a measurement circuit implemented in a single semiconductor package, utilizing different materials for the switching devices and incorporating a cascode connection and shunt resistor configuration to measure current based on potential differences, eliminating the need for Rogowski coils.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If a Rogowski coil is used to detect current, then current detection capability is improved, but cost increases
Solution Approach 1:
The patent replaces the expensive Rogowski coil with a shunt resistor, which is a much cheaper component. The shunt resistor is designed to be a simple resistive element that can be easily manufactured and integrated into the power supply circuit, eliminating the need for costly specialized current sensing coils while providing sufficient measurement capability for the application.
Solution Approach 2:
The patent extracts the current detection function from the complex Rogowski coil system and implements it through a simplified shunt resistor-based voltage measurement approach. By separating the current sensing function and implementing it through a different physical principle (Ohm's law voltage drop across a resistor rather than electromagnetic induction), the system achieves the same detection capability at much lower cost.
2Ease of manufacture
If a shunt resistor is used for current measurement, then cost is reduced, but measurement precision deteriorates due to wiring pattern influence
Solution Approach 1:
The patent merges the shunt resistor with the lower-voltage circuit board or substrate, integrating the current sensing element directly into the circuit board structure rather than using separate wiring. This integration eliminates or minimizes the wiring patterns that would otherwise introduce parasitic inductance, resistance, and capacitance, thereby maintaining measurement precision while using the cost-effective shunt resistor approach.
Solution Approach 2:
The patent introduces a voltage measurement mechanism as an intermediary to indirectly measure current through the voltage drop across the shunt resistor. By measuring voltage rather than current directly, and by ensuring the shunt resistor is properly integrated with minimal parasitic wiring, the system achieves accurate current measurement without the precision problems associated with direct shunt resistor wiring in conventional designs.
3Measurement precision
If current measurement accuracy is improved by better wiring, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent combines the shunt resistor integration with the circuit board design, merging the current sensing function into the existing PCB structure. This integration approach achieves accurate current measurement by minimizing parasitic wiring effects without requiring separate complex wiring patterns, dedicated measurement circuits, or additional shielding structures, thereby maintaining simplicity while improving precision.
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
This configuration allows for accurate current measurement with reduced errors from wiring patterns and lower costs, enabling precise detection of current magnitude without expensive components.
Implementation Method 1
a current-voltage conversion circuit into which current output from the first switching device flows; a measurement circuit that measures magnitude of the current based on a resistance value of the current-voltage conversion circuit
Implementation Method 2
the measurement circuit may measure the magnitude of the current output from the first switching device based on a potential difference between both ends of the current-voltage conversion circuit, the potential difference being generated by on-resistance of the current-voltage conversion circuit
Data Source
AI summary
A power module includes: a first switching device; a current-voltage conversion circuit into which current output from the first switching device flows; a measurement circuit that measures magnitude of the current; and an output terminal that outputs an output signal indicating the magnitude of the current measured by the measurement circuit. The measurement circuit measures the magnitude of the current output from the first switching device based on a resistance value of the current-voltage conversion circuit, and the first switching device and the measurement circuit are implemented in one semiconductor package.