Single-Package Power Meter Using TMR Sensors
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Solution Overview
Problem
Current power measurement technologies face challenges in providing low-cost, high-resolution, and galvanically isolated solutions for accurately measuring power consumption across a wide range of load and environmental conditions, with existing sensors being prone to electrical transients and requiring complex front-end electronics.
Innovation Solution
A single-package power meter utilizing tunneling magnetoresistive (TMR) magnetic sensors combined with capacitive voltage sensing, which converts current and voltage signals into digital form for processing by a microprocessor, ensuring galvanic isolation and simplifying electronics design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If Hall Effect sensors are used for current measurement, then cost is reduced compared to current transformers, but measurement resolution is insufficient
Solution Approach 1:
The patent transitions from Hall Effect sensors to TMR (tunnel magnetoresistance) sensors, changing the sensing mechanism parameter to achieve both high resolution and cost-effectiveness. TMR sensors provide superior measurement resolution while maintaining solid-state integration and affordability.
Solution Approach 2:
The patent replaces mechanical current transformers with solid-state TMR sensors, eliminating moving parts and mechanical complexity while achieving higher resolution and lower cost through integrated circuit fabrication techniques.
2Measurement precision
If AMR or GMR devices are used for current measurement, then measurement resolution is improved, but signal amplitude is low requiring complex front end electronics
Solution Approach 1:
The patent changes the sensing technology parameter from AMR/GMR to TMR, which provides inherently higher signal amplitude. This parameter change eliminates the need for complex front-end electronics while maintaining high measurement resolution.
Solution Approach 2:
The patent extracts and eliminates the complex front-end electronics requirement by selecting TMR sensors that provide sufficient signal amplitude directly, removing the unnecessary complexity of additional amplification and signal conditioning circuits.
3Ease of operation
If discrete transducers with analog outputs are used, then voltage and current information can be provided to microprocessor, but integration into single package is difficult and cost increases
Solution Approach 1:
The patent merges the TMR sensors, ADC (analog-to-digital converter), and microprocessor into a single integrated package. This consolidation provides voltage and current information digitally while achieving single-package integration and reduced cost through unified fabrication.
Solution Approach 2:
The patent replaces discrete analog transducers with an integrated digital system combining TMR sensors and ADC in a single package, eliminating the need for separate analog components and simplifying integration with the microprocessor.
4Ease of operation
If sensors are connected directly to power supply network, then measurement is straightforward, but immunity to electrical transients is reduced
Solution Approach 1:
The patent replaces direct electrical connection with magnetic field coupling through TMR sensors. This substitution maintains measurement simplicity while providing galvanic isolation that protects against electrical transients and improves reliability.
Solution Approach 2:
The patent introduces magnetic field coupling as an intermediary between the power supply network and the measurement system. This intermediary provides galvanic isolation, protecting the integrated circuit from electrical transients while enabling accurate current 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 solution provides a reliable, cost-effective, and high-resolution power measurement system with enhanced immunity to power transients, capable of accurately computing and communicating power parameters, thus reducing system complexity and increasing reliability.
Implementation Method 1
the use of tunneling magnetoresistive (TMR) devices to measure current passing through an electrical conductor
Implementation Method 2
a second magnetic sensor means disposed proximate to the voltage shunt coil, which is connected in parallel to the load, such that the second magnetic sensor means detects the magnetic field generated by the current following through the voltage shunt coil
Implementation Method 3
through the use of a capacitive coupled voltage divider connected in parallel with the load
Data Source
AI summary
A single-package power meter is disclosed for measuring the power consumed by a load connected to an electrical conductor. The power meter is galvanically isolated from the electrical conductor through the use of magnetic sensors or through the combination of magnetic sensors and capacitors. Instantaneous power consumed at the load and other desired parameters are determined by measuring the voltage of the load and current flowing through the electrical conductor. Current is measured using a magnetic sensor to detect the magnetic field associated with the current flowing through the electrical conductor. Voltage is measured by one of two possible techniques involving magnetic sensors to measure the current flowing through a coil connected in parallel with a load, or through the use of a capacitively coupled voltage divider connected in parallel with the load. An application specific integrated circuit is further disclosed that controls the bias currents of the sensors for autoranging purposes and also for computing desired parameters, such as power consumption.