Current Measurement Coil Circuit for Ground Fault Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Older ovens only measure current per power phase, lacking ground fault detection systems, while newer ovens require current leakage detection, which typically necessitates an additional set of three-phase coils, increasing hardware requirements.
Innovation Solution
Implementing a system where multiple phase current measurement coils are placed in series to measure phase currents, with the summation of these currents amplified for ground fault detection, using existing coils and adding only small, inexpensive components, and employing differential amplifiers to handle currents separately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate three-phase coil is added for ground fault detection, then ground fault detection capability is improved, but device complexity and hardware requirements increase
Solution Approach 1:
The existing current measurement coils are made to serve dual purposes: measuring phase currents for normal operation and detecting ground faults by measuring the summation of all phase currents. This eliminates the need for separate ground fault detection coils while maintaining both functionalities
Solution Approach 2:
The patent combines the ground fault detection function with the existing current measurement system by electrically connecting all current measurement coils in series and measuring their combined output, thereby merging two functions into a single integrated system
2Device complexity
If current measurement coils are connected in series for ground fault detection, then ground fault detection is enabled without additional hardware, but measurement precision at low current levels may be affected
Solution Approach 1:
The patent changes the electrical connection configuration from parallel to series to enable ground fault detection without additional hardware, and uses amplification to compensate for any signal level changes, thereby maintaining measurement precision across different current levels
3Reliability
If the summation of phase currents is measured for ground fault detection, then ground fault detection accuracy is improved, but linearity of current measurement circuits may be affected
Solution Approach 1:
The patent ensures that all current measurement coils have identical characteristics and are connected in series, creating a homogeneous measurement system where the total voltage output is directly proportional to the sum of all phase currents, thereby maintaining linearity while enabling accurate ground fault detection
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
Enables ground fault detection without a separate three-phase coil, reducing hardware needs and improving precision at low current levels, while maintaining linear behavior in current measurement circuits.
Implementation Method 1
current measurement coils to measure the currents through respective phases... These coils effectively implement transformers that divide the current by a fixed factor
Implementation Method 2
the summation of these currents amplified for ground fault detection, using existing coils and adding only small, inexpensive components, and employing differential amplifiers
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A system for current measurement and ground fault detection is disclosed. In embodiments, the system includes a plurality of phase current measurement coils (202) configured to detect phase currents associated with at least one portion of a multiphase system. The system further includes a plurality of phase current measurement circuits (300) and a ground fault detection circuit (400) connected to the phase current measurement coils. The phase current measurement circuits are configured to measure the phase currents detected by the phase current measurement coils, and the ground fault detection circuit is configured to measure a summation of the phase currents detected by the phase current measurement coils.