Condensing unit frequency conversion fan start control method and control device

Abstract

The invention provides a method for controlling starting of a variable-frequency fan of a condensing unit. The method comprises the following steps of detecting condensing pressure of a compressor to obtain condensing pressure P (n), obtaining fan frequency F (n) through calculation according to the condensing pressure P (n), and judging if the fan needs to be started according to a comparison result of the fan frequency F (n) and a preset frequency. The invention further provides a device for controlling starting of the variable-frequency fan of the condensing unit. The device comprises a pressure sensor, a fan mainboard and a controller, and the controller comprises a collecting module, a calculating module, a judging module, a storing module and a communication module. If the fan needs to be started is judged according to comparison of the calculated fan frequency and the preset frequency so that the fan can be started with the frequency corresponding to high condensing pressure, difference of high pressure and low pressure of the compressor is guaranteed, safety starting of the compressor is facilitated, and normal use of the variable-frequency fan of the condensing unit is guaranteed.

Description

technical field [0001] The invention relates to the field of air conditioning control, in particular to a method for controlling the start-up of a frequency conversion fan of a condensing unit and a control device used therein. Background technique [0002] In the prior art, the frequency conversion fan of the air conditioner is started directly according to the required frequency corresponding to the high voltage of the system. The condensing unit is special in starting. When the ambient temperature is very low, the starting pressure is relatively low, the corresponding starting frequency is relatively low, and it is difficult to start the frequency conversion fan. [0003] And even if it is started at a lower pressure, since the oil return of the compressor depends on the high and low pressure difference (that is, the difference between the discharge pressure and the suction pressure of the compressor), the oil return will be less when the pressure difference is low, which...

AI Technical Summary

Problems solved by technology

Condensing units start special. When the ambient temperature is very low, the starting pressure is relatively low, the corresponding starting frequency is relatively low, and the frequency conversion fan is difficult to start.

[0003] And even if it is started at a lower pressure, since the oil return of the compressor depends on the high and low pressure difference (that is, the difference between the discharge pressure and the suction pressure of the compressor), the oil return will be less when the pressure difference is low, which will damage the compressor. When the condensing fan is turned on at low ambient temperature, the condensing pressure (system high pressure, that is, the exhaust pressure) will be low, and the high and low pressure difference will be low, resulting in less oil return from the compressor, which is not good for the compressor.

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