Multi-Phase Motor Cable Fault Detection Using Bridge Circuit Switching
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Solution Overview
Problem
Existing methods for diagnosing faults in electric motor wiring harnesses, such as short circuits and interruptions, are inadequate as they fail to effectively detect damage without causing unnecessary torque or interference, especially in multi-phase systems prone to mechanical, chemical, and thermal stress.
Innovation Solution
A method and device that energize phases of an electric motor's connection line using specific switching patterns to measure current flows, detecting damage by reversing current direction and using a bridge circuit with high-side and low-side switches to identify short circuits and interruptions without generating torque, employing a rotor position signal to ensure accurate diagnosis without motor movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage is applied to check the connection line for short circuits and leakage currents, then detection capability is improved, but the risk of causing torque or interference increases
Solution Approach 1:
The patent applies preliminary action by performing rotor position detection before conducting the interruption diagnosis. This allows the system to identify the rotor position in advance and select switching patterns that energize phases in a way that does not generate torque, thereby preventing harmful effects before they occur
Solution Approach 2:
The patent changes the parameter of phase energization by selecting specific switching patterns based on rotor position. Instead of using standard operating switching patterns, the system uses specially selected patterns where the energized phases do not produce torque, thus allowing voltage application for detection without causing harmful interference
2Ease of operation
If standard switching patterns are used for diagnosis, then the diagnosis process is simplified, but incorrect diagnoses may occur due to torque generation
Solution Approach 1:
The patent applies feedback by using the rotor position signal to determine which switching pattern to use for the interruption diagnosis. The rotor position information feeds back into the switching pattern selection process, ensuring that the chosen pattern will not generate torque and thus preventing incorrect diagnoses
Solution Approach 2:
The patent makes the switching pattern selection dynamic by adapting it to the rotor position. Instead of using a fixed switching pattern, the system dynamically selects the appropriate pattern based on the current rotor position, ensuring accurate diagnosis without torque generation
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 approach allows for efficient and accurate detection of short circuits and interruptions in electric motor connection lines, preventing incorrect diagnoses and minimizing additional load or heating, while using existing components for normal operation, thus enhancing fault detection in multi-phase motors.
Implementation Method 1
Switching at least one switching pattern of at least two switches of the bridge circuit, with a first high-side switch of the bridge circuit connected to a first phase of the connecting line being switched on as the first switch of the switching pattern and a second low-side switch of the bridge circuit connected to a second phase of the connecting line being switched on as the second switch of the switching pattern; measuring a current flow resulting from the switching pattern
Implementation Method 2
detecting damage to the connecting line using a value of the at least one current flow
Data Source
Figure 1
Figure 2~3
AI summary
The invention relates to a method for testing a multi-phase connection cable (100) which connects a bridge circuit (104) to an electric motor (102), the method comprising a switching step, a measuring step and a detecting step. In the switching step, at least one switching pattern is switched by at least two switches (112, 114, 116, 118, 120, 122) in the bridge circuit (104). A first high-side switch (112) in the bridge circuit (104), said switch being connected to a first phase (106) of the connection cable (100), is switched on as the first switch (112, 114, 116, 118, 120, 122) of the switching pattern. A second low-side switch (118) in the bridge circuit (104), said switch being connected to a second phase (108) of the connection cable (100), is switched on as the second switch (112, 114, 116, 118, 120, 122) of the switching pattern. In the measuring step, a current flow resulting from the switching pattern is measured. In the detecting step, damage to the connection cable (100) is detected using a value of the at least one current flow.