Current Measurement Using Reference Current Calibration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing current measurement methods in information handling systems, such as Hall sensors and precision shunt resistors, are costly and inefficient, with shunt resistors wasting power and producing heat, and lacking precision for load current determination.
Innovation Solution
A system and method that uses a reference current with a distinguishable characteristic to calibrate the resistance of an electrical component, allowing for accurate load current measurement by isolating and measuring the voltage drop across the component, thereby eliminating the need for precision shunt resistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a precision shunt resistor is used to measure current, then measurement precision is improved, but power consumption increases and heat is generated
Solution Approach 1:
The patent introduces a reference current as an intermediary signal to indirectly measure the resistance of the shunt resistor. By measuring the voltage drop caused by this known reference current, the system calculates resistance without requiring the shunt resistor to continuously dissipate power for measurement purposes. This mediator approach allows precise resistance measurement while minimizing ongoing power consumption.
Solution Approach 2:
The system performs preliminary calibration by measuring the shunt resistor's resistance using the reference current before actual load current measurement. This preliminary action establishes the resistance value that will be used for subsequent current calculations, allowing the shunt resistor to operate at minimal power consumption during actual measurement phases while maintaining precision.
2Measurement precision
If a Hall sensor is used to measure current, then measurement precision is improved, but device cost increases
Solution Approach 1:
The patent creates a simplified copy of the measurement function by using basic voltage measurement circuitry to measure the voltage drop across the shunt resistor. Instead of using a complex Hall sensor that directly measures current, the system copies the essential measurement capability through ohm's law (V=IR), using inexpensive voltage sensors and calculation to achieve the same measurement objective.
Solution Approach 2:
The patent replaces the Hall sensor's magnetic field-based measurement mechanism with an electrical voltage measurement mechanism. By substituting the mechanical/magnetic Hall effect with electrical voltage measurement and calculation, the system achieves current measurement precision while dramatically reducing device complexity and cost.
3Device complexity
If a MOSFET Rdson is used to detect overcurrent, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The system performs preliminary calibration by measuring the actual resistance value of the MOSFET using the reference current method before using it for current detection. This preliminary measurement establishes the true resistance value, which is then used for accurate current calculations. This approach transforms the MOSFET from a component with assumed nominal resistance to one with precisely characterized resistance, improving measurement precision while maintaining low device complexity.
Solution Approach 2:
The patent implements feedback by continuously monitoring the voltage drop across the MOSFET and using the calibrated resistance value to calculate actual current flow. This feedback mechanism allows the system to achieve precise current measurement and overcurrent detection using the simple MOSFET structure, combining low complexity with high precision through active calibration and calculation.
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 reduces the expense and power wastage associated with current measurement, enhances efficiency, and prevents single-point failures in power systems by utilizing existing resistance for current measurement, while providing precise current detection across varying resistances.
Implementation Method 1
measuring the voltage drop across a component and determining a load current flowing through the component
Data Source
AI summary
Load current of a circuit is determined across a component of the circuit by calibrating the resistance of the component with a reference current having a distinguishable characteristic. For example, a reference current with swept frequency modulation is applied to the component so that the resistance of the component is determined from voltage drop associated with the reference current across the component. The component resistance is applied to a voltage drop associated with the load current to determine the load current. For example, a filter matched to the reference current frequency modulation isolates the reference current voltage drop so that a ratio of the reference current voltage drop and the load current voltage drop provides a ratio of the reference current and load current.