Current Measurement Apparatus Using Current Multiplier for Power Efficiency
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Solution Overview
Problem
Current measurement technologies face challenges in achieving high accuracy and stability, particularly in high-current applications, due to temperature drift and the need for precise calibration, which increases power consumption and complexity.
Innovation Solution
The development of a current measurement apparatus that uses a current multiplier to increase the amplitude of a reference signal in a power-efficient manner, allowing for precise current measurement by multiplying the input current signal by a significant factor while reducing power consumption through efficient power management and impedance matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a current shunt with low resistance is used to minimize power dissipation, then power loss is reduced, but temperature drift causes resistance change leading to loss of measurement accuracy
Solution Approach 1:
The patent applies parameter changes by using a current multiplier circuit that changes the operating parameters of the measurement system. Specifically, it multiplies the current signal by a known factor (e.g., 10x) using operational amplifiers and feedback networks, allowing the use of higher-shunt resistance values without sacrificing accuracy, since the multiplication factor is precisely controlled and compensates for the shunt's temperature drift effects.
Solution Approach 2:
The current multiplier acts as an intermediary between the current shunt and the measurement circuitry. It introduces a controlled gain stage that mediates the relationship between the shunt voltage and the final measurement, allowing the system to tolerate larger resistance values in the shunt while maintaining measurement accuracy through the precise, stable multiplication factor provided by the operational amplifier circuit.
2Measurement precision
If factory calibration is performed to compensate for inaccuracies, then measurement precision is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent implements preliminary action by performing calibration at the time of manufacture and permanently storing the calibration factor in non-volatile memory (such as EEPROM or flash memory) within the integrated circuit. This preliminary calibration eliminates the need for complex, repeated calibration procedures during operation, as the calibrated parameters are baked into the device and remain stable throughout its operational life, thereby reducing ongoing device complexity and power consumption.
3Reliability
If a current transformer is used to measure AC current, then isolation from the current carrying conductor is achieved, but it can only measure AC current and requires precise knowledge of transfer function
Solution Approach 1:
The patent achieves universality by designing a current measurement system based on a universal current multiplier circuit that can accurately measure both AC and DC current components. The operational amplifier-based current multiplier, combined with appropriate shunt resistor selection, provides a single measurement system that handles multiple current types and applications, eliminating the need for separate AC-only current transformers while maintaining isolation benefits.
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 achieves a 20% to 85% improvement in power consumption efficiency and provides high precision current measurement with improved independence from load-induced power fluctuations, maintaining accuracy and stability over time.
Implementation Method 1
the current multiplier being configured such that: the first path carries a multiplier input current signal; the second path carries a multiplier output current signal which determines the reference input signal and which corresponds to the multiplier input current signal multiplied by a multiplier value determined by the current multiplier
Data Source
AI summary
Current measurement apparatus comprises a measurement arrangement and a signal source. The measurement arrangement is configured to measure a current signal drawn by a load. The signal source is operative to apply a reference input signal to the measurement arrangement whereby an output signal from the measurement arrangement comprises a load output signal corresponding to the load drawn current signal and a reference output signal corresponding to the reference input signal. The signal source comprises a current multiplier which defines first and second current paths and is configured such that: the first path carries a multiplier input current signal; the second path carries a multiplier output current signal which determines the reference input signal and which corresponds to the multiplier input current signal multiplied by a multiplier value determined by the current multiplier; and the multiplier input current signal and the multiplier output current signal are carried on their respective paths in a same direction relative to a power supply voltage. Power drawn through the second path as divided by the multiplier value is less than the power drawn through the first path.