Carrier Signal Injection Angle for Electric Machine Noise Reduction
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Solution Overview
Problem
Existing self-sensing methods for electric machines using high frequency signal injection often increase noise and vibration, limiting their effectiveness, especially at zero or near-zero speed operations, due to the alignment of carrier signals with constant flux or torque orientations.
Innovation Solution
A drive system that injects a carrier signal between the constant flux and constant torque injection angles to reduce noise and vibration while maintaining sensitivity for magnetic alignment information, allowing for effective self-sensing control of AC electric machines across various operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high frequency carrier signal is injected along constant flux or torque orientation for self-sensing, then magnetic alignment information is obtained, but noise and vibration increase significantly
Solution Approach 1:
The patent changes the injection angle parameter from traditional constant flux or torque orientation to an intermediate angle between these orientations. This parameter modification reduces the excitation of radial and torsional forces while maintaining sufficient magnetic alignment signature for self-sensing, thereby resolving the contradiction between measurement precision and noise/vibration generation.
2Extent of automation
If carrier signal injection is aligned with constant flux or torque orientation, then self-sensing control is achieved, but radial and torsional excitation increase causing vibration
Solution Approach 1:
The patent applies local quality by selectively modifying the injection angle in the carrier signal injection process. Instead of using uniform injection angles (constant flux or torque orientation), the system uses a locally optimized intermediate angle that reduces radial and torsional excitation in specific operating regions while maintaining self-sensing capability.
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 approach minimizes noise and vibration levels while ensuring robust self-sensing performance, enabling reliable operation of AC electric machines at reduced noise levels, even at low speeds, by optimizing the injection angle and frequency of the carrier signal.
Implementation Method 1
the carrier signal generates a carrier response signal that has sensitivity to magnetic alignment information of the AC electric machine at its operating point
Data Source
AI summary
A drive system for driving an AC electric machine includes an electric machine power converter that provides a primary current excitation vector having a magnitude and angle to drive the AC electric machine. A control system separate from or incorporated into the power converter causes the power converter to inject a carrier signal to the AC electric machine that is superimposed onto the current vector and that generates a carrier response signal that has sensitivity to magnetic alignment information of the AC electric machine at its operating point, the carrier response signal providing a measurable magnetic alignment signature of the AC electric machine. The control system causes the power converter to inject the carrier signal at an injection angle between a constant flux injection angle and a constant torque injection angle, to reduce noise and/or vibration of the AC electric machine caused by the injected carrier signal.