System and method for operational acoustic optimization of a variable speed compressor and refrigerator
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Solution Overview
Problem
Variable speed compressors generate significant tonal noise during the alignment phase due to the switching frequency of the power supply, which falls within the human audible range, causing discomfort and is more annoying than other noise sources.
Innovation Solution
A system and method that utilize a control block to establish a first switching frequency higher than the audible range during the alignment phase and switch to a second frequency within the audible range after alignment, minimizing noise perception during this phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the switching frequency is set within the audible range (20 Hz to 20 kHz) to meet motor efficiency and thermal management requirements, then the compressor achieves acceptable operating performance, but significant tonal noise is generated during the alignment phase causing discomfort
Solution Approach 1:
The patent applies dynamics by making the switching frequency adjustable rather than fixed. The control block dynamically changes the switching frequency based on the operational phase: using a first frequency (above audible range) during the alignment phase to reduce noise, and switching to a second frequency (within audible range) during normal operation to maintain motor efficiency and thermal management performance.
Solution Approach 2:
The patent changes the parameter of switching frequency based on operational conditions. During the alignment phase, the switching frequency is set above the audible range (e.g., >20 kHz) to eliminate tonal noise. During normal operation, the frequency is adjusted to an optimal value within the audible range to ensure motor efficiency and inverter thermal management, thus optimizing performance based on operational needs.
2Object-affected harmful factors
If the switching frequency is increased above the audible range during alignment phase to reduce tonal noise, then noise perception is minimized, but thermal management of the inverter may be compromised
Solution Approach 1:
The patent segments the operational timeline into distinct phases: alignment phase and normal operation phase. During the alignment phase, the switching frequency is set above the audible range to minimize tonal noise. During normal operation, the frequency is optimized for thermal management and efficiency. This temporal segmentation allows each phase to have optimized parameters without compromising overall system performance.
Solution Approach 2:
The patent performs preliminary action by conducting the alignment operation at a frequency above the audible range before entering normal operation. This preliminary alignment phase, though temporarily using a frequency that may affect thermal management, is kept brief and is followed by switching to the optimal frequency for sustained operation, thus achieving both noise reduction and thermal management goals.
3Device complexity
If a fixed switching frequency is used to simplify control, then device complexity is reduced, but acoustic performance cannot be optimized during different operational phases
Solution Approach 1:
The control block is designed to dynamically adjust the switching frequency based on the operational phase detected by the control logic. Although this increases control complexity slightly, it enables significant acoustic performance improvement during the alignment phase while maintaining optimal motor efficiency during normal operation, representing a worthwhile trade-off for enhanced overall system performance.
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 solution effectively reduces tonal noise generated during the alignment phase of variable speed compressors, making it imperceptible or barely perceptible to humans without impacting the compressor's performance or thermal management.
Implementation Method 1
a variable speed compressor comprising a synchronous motor (6), a frequency inverter (3) and a control block (5), the frequency inverter being electrically connected to the synchronous motor (6) and an electrical network (4)
Data Source
AI summary
A system for operational acoustic optimization of a variable speed compressor (2) includes a motor (6), a frequency inverter (3), and a control block (5). The frequency inverter (3) is electrically connected to the synchronous motor (6), an electrical network (4), and the control block (5). The control block (5) is configured to control the speed of the motor (6) and to establish a first switching frequency (F1) and a second switching frequency (F2) of the frequency inverter (3). The frequency inverter (3) is configured to start the variable speed compressor (2) by supplying motor (6) with a signal (9) with the first switching frequency (F1) for the duration of a time period (T1) corresponding to at least one alignment operation period of the motor (6) and to supply the motor (6) with a signal (9) with the second switching frequency (F2) after the time period (T1).