Outdoor Fan Motor Frequency Control to Prevent AC Resonance
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Solution Overview
Problem
Existing air conditioner outdoor fan motor control methods result in sympathetic vibrations and noise due to identical frequencies, limiting frequency range and precision in fan motor control, leading to continuous noise and instability.
Innovation Solution
A method where the first and second outdoor fan motors operate at different frequencies, with a controller adjusting their speeds based on measured pressures and preset ranges to prevent resonance and enhance control precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the upper outdoor fan motor and the lower outdoor fan motor run at the same frequency simultaneously, then the control system is simple, but sympathetic vibration and noise are generated
Solution Approach 1:
The patent changes the operating frequency parameter of the fan motors from identical to different values. The controller makes the upper and lower outdoor fan motors operate at different frequencies, which eliminates the sympathetic vibration and noise caused by identical frequency operation, while maintaining relatively simple control system architecture.
2Ease of operation
If the upper outdoor fan motor and the lower outdoor fan motor run at the same frequency simultaneously, then the control is easy, but the total running frequency range is too small to realize precise control
Solution Approach 1:
The patent expands the frequency parameter space by allowing upper and lower fan motors to operate at different frequencies. This increases the total available frequency range from a single shared range to a combined range, enabling more precise control of air volume while keeping the control method relatively straightforward.
3Object-generated harmful factors
If the upper outdoor fan motor and the lower outdoor fan motor run at different speeds, then sympathetic vibration is reduced, but the phase difference is reduced with time and sympathetic vibration is formed again
Solution Approach 1:
The patent implements periodic frequency adjustment where the controller continuously varies the operating frequencies of the upper and lower fan motors in a periodic manner. This ensures that the frequency difference between the two motors is maintained dynamically, preventing the phase synchronization that would lead to sympathetic vibration, while keeping the system operation stable.
Data Source
Figure 1~2
AI summary
A method for controlling outdoor fan motors of an air conditioner comprises the following steps: determining a required rotation speed of a first outdoor fan motor (120) and that of a second outdoor fan motor (130) according to the operating condition of the air conditioner, and separately outputting control signals to the first outdoor fan motor (120) and to the second outdoor fan motor (130) for controlling respective working frequencies corresponding to respective required rotation speeds; the working frequencies of the two motors being different at the same time instant; measuring an air exhaust pressure of the air conditioner during cooling or an air suction pressure during heating; and comparing the measured air exhaust pressure or the air suction pressure with a preset pressure, and controlling the rotation speed of the first outdoor fan motor (120) and that of the second outdoor fan motor (130) according to a comparison result. In the method, the two motors have different frequencies and are separately controlled, accordingly noises generated during the operation of the air conditioner units are reduced, and the motors can operate in a wider range of frequency, so that air volume can be more precisely regulated, the pressure and the temperature of the units are controlled within a reasonable range, and the operation effect of the units is stabilized.