Torque Compensation for Compressor Motor Vibration
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Solution Overview
Problem
Motor-driven compressors, particularly those using PMSM or IPMSM motors, face challenges in maintaining consistent speed and reducing mechanical vibrations at low speeds, leading to inefficiencies and potential damage due to cyclic torque loads, which existing field-oriented control methods fail to adequately address.
Innovation Solution
A processor-based system that extracts mechanical frequency components from motor speed, transforms them into the DQ domain, controls the frequency to zero, and generates a dampening signal for torque compensation, using filters and PI loops to minimize vibrations, allowing for efficient operation and reduced mechanical stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If field-oriented control is used to control motor speed, then speed control capability is improved, but mechanical vibrations and torque loads worsen at low speeds
Solution Approach 1:
The system performs preliminary action by extracting the mechanical frequency component from the estimated speed before it causes harmful vibrations. The mechanical frequency is identified and removed in advance through signal processing (FFT analysis and filtering), and the extracted component is used to generate a compensating torque signal that counteracts the vibrations before they fully manifest in the mechanical system.
Solution Approach 2:
The system implements feedback by continuously monitoring the estimated motor speed, extracting the mechanical frequency component, and using this information to generate a compensating torque signal. The compensating torque is fed back to the motor control system to counteract the vibrations, creating a closed-loop control mechanism that actively reduces mechanical oscillations based on real-time speed measurements.
2Loss of energy
If compressor operates at low speeds for extended periods, then energy efficiency is improved, but mechanical stress and potential damage worsen
Solution Approach 1:
The system uses feedback by continuously monitoring motor speed and mechanical vibrations, comparing actual performance against expected values, and adjusting the compensating torque signal accordingly. This closed-loop control ensures that the compressor can operate at low speeds for extended periods while actively counteracting mechanical stress through real-time vibration compensation, thereby maintaining both energy efficiency and mechanical durability.
3Reliability
If torque compensation is applied to reduce vibrations, then mechanical reliability is improved, but control system complexity worsens
Solution Approach 1:
The system replaces complex mechanical vibration damping mechanisms with an electrical control solution. Instead of using physical dampers or mechanical buffers, the invention uses signal processing (FFT, filtering) and electrical torque compensation to achieve vibration reduction. This substitution of mechanical systems with electrical/control-based solutions reduces physical complexity while maintaining or improving vibration damping effectiveness.
Data Source
AI summary
Embodiments of the present disclosure include a motor controller with a processor and a machine readable medium. The medium includes instructions that, when loaded and executed by the processor, cause the processor to receive an estimated or sensed speed of a motor, extract a mechanical frequency component from the estimated or sensed speed, transform the mechanical frequency into direct quadrature (DQ) domain at the mechanical frequency, control the mechanical frequency to zero, and generate a dampening signal for torque based upon the controlled mechanical frequency.