Adaptive Constant Current Engine Circuit for Remote Load Sensing
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Solution Overview
Problem
Existing technologies face challenges in accurately controlling a constant current in remote circuits due to complexity and cost associated with direct sensing, and inaccuracies caused by variations in electrical characteristics of the remote circuit when using indirect sensing.
Innovation Solution
A circuit and method employing a reference current conveyer, a sensing current conveyer, and a differential amplifier to generate a control voltage that maintains a constant current in a target load device, independent of variations in the common load voltage, using a feedback loop that compares sensed and reference currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct sensing of the current is used, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent introduces an intermediary sensing mechanism that indirectly measures the current through a proxy signal rather than direct measurement. The sensing circuit uses an operational amplifier to compare a sensed voltage (proportional to current) against a reference voltage, allowing accurate current measurement without direct electrical contact with the high-current path, thus reducing complexity while maintaining precision.
Solution Approach 2:
The patent creates a simplified copy or representation of the current signal through voltage proportional to current (using Ohm's law through a sense resistor). Instead of measuring the actual current directly, the system measures a copied voltage signal that represents the current, making the measurement process simpler and less intrusive on the main circuit.
2Device complexity
If indirect sensing of the current is used, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the sensed voltage is continuously compared against a reference voltage by an operational amplifier. The output of the op-amp adjusts to maintain the difference between these voltages at zero, creating a feedback loop that compensates for variations in the remote circuit. This feedback ensures that the indirect sensing remains accurate despite changes in electrical characteristics of the remote circuit.
Solution Approach 2:
The patent changes the measurement parameter from direct current measurement to voltage measurement. By measuring voltage (which is easier and more accurate to measure indirectly) and using the relationship V=IR, the system achieves accurate current sensing without the complexity of direct current measurement. The op-amp compares voltages rather than currents, improving measurement precision while keeping the circuit simple.
3Device complexity
If variations in remote circuit electrical characteristics are not compensated, then device complexity is reduced, but reliability deteriorates
Solution Approach 1:
The feedback loop continuously monitors the sensed voltage and adjusts the control signal to maintain constant current despite variations in the remote circuit. The operational amplifier compares the actual current representation against the reference, and any deviation caused by circuit variations triggers a corrective action, ensuring reliable and stable current control.
Solution Approach 2:
The patent makes the sensing system dynamic by using an operational amplifier that continuously adjusts its output based on the difference between sensed and reference voltages. This dynamic adjustment allows the system to adapt to real-time changes in the remote circuit's electrical characteristics, maintaining reliability without requiring a complex fixed compensation circuit.
Data Source
AI summary
An adaptive constant current engine (ACCE) to control a current of a target load device at a constant level is disclosed. The ACCE includes a closed feedback loop which generates a sensed current that represents a load current conducted by the target load device and then compares the sensed current to a reference current. Based on this comparison, the circuit can output a voltage to control the current conducted by the target load device. The disclosed ACCE adapts the comparison to an operating voltage of the target load device in order to provide electrical conditions at a reference node receiving a reference current that are the same as electrical conditions at a sensing node receiving a sensing current. Accordingly, the ACCE can generate very accurate comparisons regardless of variations in the operating voltage of the target load device.