Air Conditioner Frost Detection Using Rotation-Speed Command Voltage
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Solution Overview
Problem
Existing air conditioner systems require a current detecting sensor to detect frost formation on outdoor heat exchangers during heating operations, leading to increased costs for frost detection and defrosting.
Innovation Solution
The system employs a rotation-speed command voltage to control the outdoor fan's rotation speed, allowing frost detection and defrost determination without the need for a current detecting sensor, using a control board to generate and adjust the rotation-speed command voltage based on actual rotation speed feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a current detecting sensor is provided to detect fan current for frost detection, then frost formation detection accuracy is improved, but device cost increases
Solution Approach 1:
The patent extracts the frost detection function from the current detecting sensor approach and implements it through the existing inverter board by monitoring rotation-speed command voltage, thereby eliminating the need for additional current detecting sensors and reducing device cost while maintaining detection accuracy
Solution Approach 2:
The inverter board is made multi-functional by enabling it to perform both motor control and frost detection functions. The same inverter board that controls the outdoor fan motor also detects frost formation by monitoring the rotation-speed command voltage, eliminating the need for separate dedicated detection sensors
2Reliability
If a current detecting sensor is provided to detect fan current for frost detection, then defrost operation reliability is improved, but ease of manufacture deteriorates
Solution Approach 1:
The patent removes the requirement for current detecting sensors from the manufacturing process and implements frost detection through the existing inverter board's voltage monitoring capability, thereby improving ease of manufacture while maintaining defrost operation reliability
Solution Approach 2:
The inverter board performs self-service by using its own existing voltage monitoring circuits to detect frost conditions, eliminating the need for separate detection sensors and simplifying the manufacturing process while ensuring reliable defrost operation
Data Source
Figure 1~2
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AI summary
An air conditioner 1 includes: an outdoor heat exchanger 14; an outdoor fan 12 for blowing air to the outdoor heat exchanger; an outdoor fan motor 20 that drives the outdoor fan; an outdoor fan inverter 21 that drives the outdoor fan motor; and a control unit 31 that generates a rotation-speed command voltage for controlling the rotation number of the outdoor fan motor. In addition, the control unit starts a defrost operation of the outdoor heat exchanger, based on the rotation-speed command voltage. In this manner, it is possible to achieve an outdoor device of an air conditioner in which there is no need to provide a current detecting sensor, and it is possible to detect frost formation over the heat exchanger during a heating operation and to perform a defrost operation at low costs.