PCB Trace Current Sensing with Temperature Compensation
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Solution Overview
Problem
High-density, high-power, space-restricted power modules require compact current sensing solutions to optimize space usage, as traditional methods like current sensing transformers and shunt resistors are inefficient and space-consuming.
Innovation Solution
A power module design utilizing a printed circuit board (PCB) trace with sense terminals that define resistance between them, allowing for current measurement through voltage sensing and temperature compensation to adjust overcurrent protection thresholds, eliminating the need for shunt resistors and minimizing power dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional current sensing methods (transformers, shunt resistors) are used, then current measurement is achieved, but space consumption increases and power dissipation increases
Solution Approach 1:
The patent merges the current sensing function with the existing PCB trace structure. The PCB trace itself serves as the sensing element, eliminating the need for separate shunt resistors or transformers. The sense terminals are coupled to the PCB trace at different locations, and the resistance of the trace between these locations is used for current measurement, thereby combining the trace's structural function with sensing function.
Solution Approach 2:
The PCB trace is given multiple functions: it serves as both the electrical connection path and the current sensing element. By measuring the voltage across the PCB trace resistance between two sense terminals, the same trace structure performs both power transmission and current measurement, reducing the need for additional dedicated sensing components.
2Measurement precision
If traditional current sensing methods (transformers, shunt resistors) are used, then current measurement is achieved, but power dissipation increases
Solution Approach 1:
The patent merges the current sensing function with the existing PCB trace structure. The PCB trace itself serves as the sensing element, eliminating the need for separate shunt resistors or transformers. The sense terminals are coupled to the PCB trace at different locations, and the resistance of the trace between these locations is used for current measurement, thereby combining the trace's structural function with sensing function.
Solution Approach 2:
The PCB trace serves itself by using its own inherent resistance for current sensing. Instead of requiring an external shunt resistor to create a voltage drop for measurement, the trace's natural resistance is utilized, eliminating the need for additional power-dissipating sensing components.
3Area of stationary object
If PCB trace resistance is used for current sensing, then space is reduced and power dissipation is reduced, but temperature compensation is required due to resistance changes
Solution Approach 1:
The patent incorporates a temperature compensation circuit that provides feedback to adjust the overcurrent protection threshold based on measured ambient temperature. This feedback mechanism compensates for the temperature-dependent changes in PCB trace resistance, ensuring accurate current measurement and overcurrent protection across varying temperature conditions.
Solution Approach 2:
The patent adjusts the overcurrent protection threshold parameter based on temperature measurements. By dynamically changing the threshold parameter according to ambient temperature, the system compensates for resistance variations in the PCB trace, maintaining measurement accuracy despite environmental changes.
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 approach enables efficient current sensing with reduced power dissipation and increased available space for other components, enhancing the power module's density and performance.
Implementation Method 1
a resistance between the first sense terminal and the second sense terminal is defined by a resistance of the PCB trace between the first location and the second location... determine a current through the PCB trace based on the measured voltage and the resistance between the first sense terminal and the second sense terminal
Implementation Method 2
the temperature compensation circuit adapted to adjust an overcurrent protection threshold of the power module based on a measured ambient temperature to compensate for changes in the resistance between the first sense terminal and the second sense terminal based on temperature
Data Source
AI summary
According to some aspects of the present disclosure, power modules having current sensing circuits, and corresponding sensing methods, are disclosed. Example power modules include a printed circuit board (PCB) having a PCB trace, a first sense terminal coupled to the PCB trace at a first location, and a second sense terminal coupled to the PCB trace at a second location such that a resistance between the first and second sense terminals is defined by a resistance of the PCB trace between the first location and the second location. The power module further comprises a control coupled to the first sense terminal and the second sense terminal, the control adapted to measure a voltage between the first sense terminal and the second sense terminal and determine a current through the PCB trace based on the measured voltage and the resistance between the first sense terminal and the second sense terminal.