Rotational Position Detector Shielding for Electric Motor Noise
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Solution Overview
Problem
In electric rotating machines, the proximity of the inverter circuit and rotational position detector leads to electromagnetic noise interference, causing erroneous rotor position detection due to external magnetic field interactions.
Innovation Solution
A shield member is mounted around the rotational position detector to absorb external magnetic fields, reducing noise levels and preventing malfunction by isolating the detector from external magnetic influences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the inverter circuit and rotational position detector are disposed in proximity to each other, then the device complexity is reduced and space is saved, but electromagnetic noise from the switching element interferes with the rotational position detector causing erroneous detection
Solution Approach 1:
A shield member is introduced as an intermediary element between the inverter circuit and the rotational position detector. This shield member absorbs or redirects electromagnetic noise from the switching element, preventing it from interfering with the rotational position detector while allowing both components to remain in close proximity, thus maintaining compact structure while improving detection reliability
2Productivity
If the switching element operates at high speed for efficient motor control, then productivity is improved, but sharp magnetic field changes generate electromagnetic noise that causes malfunction
Solution Approach 1:
The shield member is designed to utilize the electromagnetic noise generated by the switching element and redirect it away from the rotational position detector. Instead of simply blocking the noise, the shield member's structure (with openings facing the switching element) allows it to absorb and redirect the electromagnetic energy, converting the harmful noise into a controlled field that does not interfere with 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
The shield member significantly reduces magnetic field strength around the rotational position detector, minimizing noise interference and ensuring accurate rotor position detection without malfunction.
Implementation Method 1
a shield member that covers the circumference of the rotational position detector and that shields an external magnetic field is mounted onto the bracket... most of magnetic fields that are generated outside the rotational position detector are absorbed into the shield member
Data Source
AI summary
An electric rotating machine comprises: a stator; a rotor that includes a rotary shaft, and rotates coaxially with the stator; a bracket supporting and fixing the stator, and supporting rotatably the rotary shaft; a rotational position detector disposed on the side opposite to the load of the rotary shaft to detect a rotational position of the rotor; and a power part including a switching element disposed on the outer circumferential side of the rotational position detector. A shield member is disposed at the rotational position detector to cover the circumference and shield a magnetic field generated by the switching element.