Current Control Apparatus for Electric Load with Integrated Detection Resistor
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Solution Overview
Problem
Conventional current control apparatuses for electric loads face challenges in accurately detecting and preventing overcurrents, especially during hetero-phase power supply faults or ground faults, leading to potential burnout accidents and reduced digital conversion accuracy.
Innovation Solution
A current control apparatus with a switching element and current detection resistor connected in series, utilizing a microprocessor with a differential amplifier circuit, detected error calibration, conversion estimating, and feedback control sections to accurately control the switching element's on/off ratio and calibrate for improved current detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a current detection resistor is connected in a conventional configuration with separate positive and negative wiring, then the apparatus can detect current, but it becomes vulnerable to burnout during hetero-phase ground faults and requires complex wiring
Solution Approach 1:
The patent combines the current detection resistor with the negative terminal of the power supply into an integrated component structure. This merging eliminates the need for separate negative wiring while maintaining current detection capability, and the integrated design ensures that during hetero-phase ground faults, the detection resistor remains protected from excessive voltage spikes that would cause burnout in conventional separate configurations
Solution Approach 2:
The patent introduces a protective circuit configuration where the integrated detection resistor acts as an intermediary element between the power supply and the load. This intermediary structure includes internal protection mechanisms that limit voltage exposure during ground faults, preventing burnout while still allowing accurate current measurement without requiring complex external protection wiring
2Measurement precision
If calibration is not performed, then the apparatus structure remains simple, but current detection accuracy deteriorates due to temperature drift and component variations
Solution Approach 1:
The patent implements a calibration procedure that is performed in advance during the manufacturing or initialization phase. During this preliminary action, calibration constants are determined and stored in the system's memory. These pre-determined constants compensate for temperature drift and component variations, enabling high current detection accuracy during normal operation without requiring complex real-time calibration mechanisms
Solution Approach 2:
The patent incorporates a feedback mechanism where the system uses the stored calibration constants to continuously correct current measurements. The microprocessor applies these constants to compensate for drift and variations, maintaining high measurement precision through automatic feedback correction rather than requiring complex manual calibration systems
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 enables precise current control, reduces the risk of burnout, and maintains high digital conversion accuracy by calibrating for factors influencing current detection, effectively addressing overcurrent detection and accuracy issues.
Implementation Method 1
a differential amplifier circuit part amplifying a difference voltage between voltages at opposite ends of the current detection resistor to generate a monitored voltage Ef substantially proportional to the load current
Data Source
AI summary
A current control apparatus for an electric load can prevent burnout at a short-circuit accident with high control precision. A switching element is interrupted by an overcurrent detection circuit upon occurrence of a load short circuit, but is transitionally limited in current by a current detection resistor. A differential amplifier amplifies a difference voltage between voltages at opposite ends of the current detection resistor to generate a monitored voltage Ef corresponding to a load current. A microprocessor controls the energization rate of the switching element so as to make an estimated load current Ime calculated from the monitored voltage Ef coincide with a target load current Is, and it calculates, upon calibration operation, calibration constants and estimates, during actual operation, a load current Ime from the monitored voltage Ef using the calibration constants.