Voltage Injection Cable Swap Detection for Electric Machines
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Solution Overview
Problem
Existing systems fail to effectively detect swapped cable connections in electric machines of hybrid-electric or all-electric vehicles, which can lead to improper phase rotation sequences and impact performance and safety.
Innovation Solution
A controller is programmed to inject a voltage with a predetermined phase rotation sequence into a three-phase electric machine, using discrete Fourier transform to compare sequence current magnitudes, and outputs a cable swapped diagnostic if the phase rotation sequence differs, thereby preventing operation or compensating for the swapped connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a voltage injection method is used to detect cable connections, then the detection accuracy is improved, but the system complexity increases due to additional control logic and signal processing requirements
Solution Approach 1:
The system performs voltage injection and phase rotation sequence detection during the power-on condition before normal operation begins. This preliminary action allows the controller to detect cable connection status and establish the correct phase sequence in advance, ensuring safe operation while integrating seamlessly into the existing control workflow without requiring complex real-time detection mechanisms during operation.
Solution Approach 2:
The patent replaces traditional mechanical or simple electrical connection testing with an electrical voltage injection method combined with discrete Fourier transform analysis. This substitution enables precise detection of phase rotation sequences and cable connection status through signal processing, achieving high measurement precision while maintaining controller-based implementation suitable for modern electric vehicle systems.
2Device complexity
If the controller monitors rotation direction by applying sufficient voltage to cause rotation, then the cable connection detection is simplified, but energy consumption increases and the machine rotates unintentionally
Solution Approach 1:
The system applies a voltage signal with sufficient frequency content to elicit a current response that reveals phase sequence information, but the voltage magnitude and frequency are controlled to prevent actual rotation of the electric machine. The discrete Fourier transform analyzes the current response at specific frequency components, extracting phase sequence information without requiring full rotational operation, thus consuming minimal energy while avoiding unintentional machine rotation.
Solution Approach 2:
The patent replaces mechanical rotation observation with electrical signal analysis. By injecting a voltage signal and analyzing the resulting current through discrete Fourier transform, the system determines phase rotation sequence electrically without requiring the electric machine to physically rotate. This substitution eliminates energy consumption associated with mechanical rotation while providing accurate cable connection detection.
3Reliability
If the system detects phase rotation sequence using current magnitude comparison, then the detection reliability is improved, but the difficulty of detecting and measuring increases due to signal processing requirements
Solution Approach 1:
The system measures the actual current response to the injected voltage signal, performs discrete Fourier transform to extract frequency components, and compares the magnitudes of positive and negative sequence current components. This feedback mechanism provides reliable phase sequence detection by continuously monitoring and comparing current magnitudes, allowing the controller to identify cable connection status and phase rotation sequence with high reliability through systematic signal processing.
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
This solution enables the detection of improper cable connections, ensuring the electric machine rotates in the intended direction, enhancing safety and performance by preventing potential issues related to swapped cables.
Implementation Method 1
The predetermined sequence current magnitudes may be based on an inductance of the three-phase electric machine. The predetermined sequence current magnitudes may be based on a magnitude of the voltage. The predetermined sequence current magnitudes may be based on a frequency of the voltage.
Implementation Method 2
The sequence current magnitudes associated with the current may be derived from a discrete Fourier transform of measurements of the current.
Data Source
AI summary
A vehicle includes an electric machine and a controller configured to inject a voltage into the electric machine. The controller measures the currents caused by the voltage and processes the currents using a discrete Fourier transform to determine positive and negative sequence currents. A phase rotation sequence is identified by comparing the sequence currents to expected positive and negative sequence currents that are associated with possible phase rotation sequences. The electric machine may be controlled according to the identified phase rotation sequence. A cable swapped diagnostic may be output when the phase rotation sequence is different than an expected phase rotation sequence.