Current Detection Apparatus for AC Rotating Machines
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Solution Overview
Problem
Current current detection apparatuses for AC rotating machines require significant space and experience high detection errors due to disturbance magnetic fields and temperature rise issues, especially in thermally harsh environments, limiting output torque and efficiency.
Innovation Solution
A current detection apparatus with magnetic sensors disposed to face each current path at specific positions, utilizing a d-axis and q-axis sum current transformation and positional relationships to cancel error components, reducing the number of sensors and correction conductors needed, thereby minimizing space requirements and detection errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two magnetic sensors are disposed for each phase to reduce detection error, then current detection precision is improved, but device complexity and space requirements increase
Solution Approach 1:
The patent combines multiple current detection functions into a single magnetic sensor by utilizing the spatial arrangement of current paths. The magnetic sensor detects combined magnetic fields from multiple phases, and through mathematical processing of the detection currents, the system achieves accurate current detection for each phase without requiring separate sensors for each phase.
Solution Approach 2:
A single magnetic sensor performs multiple detection functions by detecting magnetic fields from multiple current paths simultaneously. The sensor is positioned to face multiple current paths, enabling it to gather information from different phases, which are then processed to derive accurate current values for each phase.
2Measurement precision
If correction conductors are added to reduce detection error, then current detection precision is improved, but device complexity and space requirements increase
Solution Approach 1:
The patent replaces the mechanical approach of using correction conductors with a mathematical processing approach. Instead of physically adding correction conductors to cancel disturbance magnetic fields, the system uses mathematical algorithms to process the detection currents and eliminate errors, thereby achieving the same goal without additional physical components.
3Measurement precision
If correction conductors are mounted to reduce detection error, then current detection precision is improved, but temperature rise increases
Solution Approach 1:
The patent eliminates correction conductors entirely by substituting their function with mathematical processing. Since correction conductors carry current to generate compensating magnetic fields, removing them eliminates their resistive heating, thereby reducing temperature rise in the detection apparatus while maintaining detection precision through algorithmic error correction.
4Measurement precision
If more magnetic sensors are disposed to detect currents of multiple phases, then current detection precision is improved, but area occupied increases
Solution Approach 1:
The patent merges multiple detection functions into a single magnetic sensor by strategically positioning it to face multiple current paths. This consolidation reduces the number of sensors required from multiple sensors (one per phase) to a single sensor, thereby reducing the area occupied by the detection device while maintaining the capability to detect currents of multiple phases accurately.
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 achieves a current detection apparatus with reduced space requirements and lower detection errors, improving output torque accuracy and reducing temperature-related limitations, enhancing overall efficiency and reliability.
Implementation Method 1
a current detection apparatus that uses a magnetic sensor to detect a current of a winding
Data Source
AI summary
Magnetic sensors each disposed to face each of current paths for each of windings with 2n phases (n is a multiple of three) in an AC rotating machine are included, and when each of a DC component and an AC component in a d-axis sum current and a q-axis sum current obtained by performing a dq-transformation into a two-axis coordinate system on 2n detection currents on the assumption that all current amplitudes of the windings are the same is represented collectively with each of terms expressed by sine functions with different phases to one another, each of the current paths at each of 2n current path arrangement positions is arranged to have a positional relationship where error components are reduced by cancellation among coefficients included at least in one of the terms or by cancellation among values of the terms.