Holding Brake Functional Testing via Current Vector Rotation
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Solution Overview
Problem
Existing methods for functional testing of holding brakes in electric motors are not reliable due to errors in commutation and motor control, leading to inconsistent torque application and inaccurate assessment of brake functionality, especially in multiphase motors.
Innovation Solution
The method involves rotating the current vector so that it is normal to the rotor flux direction, ensuring the desired torque is applied by varying phase currents, and dividing the electrical period into sectors for a defined dwell period to maintain adjusted torque during testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a motor current is applied to produce a certain torque for functional testing, then the holding brake can be tested, but the torque application is inconsistent due to commutation errors and control inaccuracies
Solution Approach 1:
The patent changes the parameter of current vector orientation by rotating it to be normal (perpendicular) to the rotor flux direction. This specific orientation ensures that the torque-producing component of the current is maximized and decoupled from flux-producing components, eliminating the influence of commutation errors and control inaccuracies on torque magnitude. The torque becomes directly proportional to the current magnitude regardless of commutation phase errors.
2Ease of operation
If the current vector is applied without considering its orientation relative to rotor flux, then the testing procedure is simple, but the actual torque applied differs from the assumed torque
Solution Approach 1:
The patent performs a preliminary action by rotating the current vector to a specific orientation (normal to rotor flux direction) before applying the current for torque production. This preliminary orientation step ensures that the subsequent current application produces the expected torque accurately, allowing for reliable functional testing without requiring complex real-time torque measurement and correction during the test.
3Adaptability or versatility
If the holding brake is tested with external loads present, then the test reflects real operating conditions, but the torque application becomes even more inconsistent due to load variations
Solution Approach 1:
The patent maintains the current vector orientation parameter change (normal to rotor flux) even when external loads are present. This orientation ensures that the torque-producing current component remains decoupled from flux-producing components, making the torque application consistent and predictable regardless of external load variations. The method can therefore be applied universally across different operating conditions while maintaining reliability.
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 enhances the reliability of holding brake functional testing by ensuring consistent torque application and accurate assessment, even with external loads, by rotating the current vector by at least 180° without loads and 360° with loads, and maintaining it within sectors to adjust torque effectively.
Implementation Method 1
phase currents are applied to the electric motor (1) in magnitude and angle for producing a current vector
Implementation Method 2
holding brakes are also provided in order to fix a moved axis of the machine in place
Data Source
AI summary
Method for functional testing of a holding brake of an electric motor. Method includes applying, while the holding brake is closed, phase currents to the electric motor in magnitude and angle for producing a current vector; varying, while the holding brake is closed, the phase currents so as to rotate the current vector to be normal to a rotor flux direction at least one time; and checking whether the holding brake slips when the phase currents are being applied.