US 12,438,357 B2
Power failure detection circuit and control circuit for VRF system
Xiaojun Guo, Shanghai (CN); Hui Zhai, Shanghai (CN); Jian Ni, Shanghai (CN); and Zehang Yu, Shanghia (CN)
Assigned to CARRIER CORPORATION, Palm Beach Gardens, FL (US)
Filed by Carrier Corporation, Palm Beach Springs, FL (US)
Filed on Oct. 4, 2023, as Appl. No. 18/480,769.
Claims priority of application No. 23199545 (EP), filed on Sep. 25, 2023.
Prior Publication US 2025/0105619 A1, Mar. 27, 2025
Int. Cl. H02H 7/00 (2006.01); G01R 23/02 (2006.01); H02H 7/20 (2006.01)
CPC H02H 7/20 (2013.01) [G01R 23/02 (2013.01)] 20 Claims
OG exemplary drawing
 
8. A control circuit for a variable refrigerant flow VRF system, characterized by comprising:
a power failure detection circuit for detecting a power failure condition of a power supply and generating an output signal accordingly;
a fan control circuit for controlling a fan according to the output signal;
a micro-control unit interrupt generating circuit for generating an interrupt signal according to the output signal to provide to a micro-control unit; and
an energy storage unit for providing electrical energy for the micro-control unit to close an electronic expansion valve, wherein the power failure detection circuit comprises:
a rectifying circuit for full-wave rectifying an alternating current voltage so as to obtain a first voltage;
a switching circuit for converting the first voltage into a periodic voltage pulse; and
a judgment circuit for determining that there is the power failure condition of the power supply when the periodic voltage pulse is not received within a preset time period, and generating the output signal accordingly.