Multiple load control for variable frequency drive harmonic mitigation
a technology of harmonic mitigation and load control, applied in the direction of refrigeration components, transportation and packaging, light and heating equipment, etc., can solve the problems of system undesirable trade-offs, cost, complexity, efficiency, etc., and achieve the desired cooling capacity and reduce the input harmonic
Pending Publication Date: 2015-11-19
TRANE INT INC
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AI Technical Summary
Benefits of technology
This patent describes a system for controlling the input of power to a compressor and other loads in a refrigeration system. The system uses multiple frequency drives to control the output of the compressor, which in turn regulates the cooling capacity of the system. The system also includes a harmonic mitigation control parameter to reduce the unwanted harmonic input to the system. The technical effects of this patent are improved cooling capacity and reduced harmonic input to the refrigeration system, resulting in improved performance and reliability.
Problems solved by technology
While providing some benefits, these approaches suffer from a number of shortcomings including cost, complexity, efficiency, efficacy, and adaptability.
Heretofore these systems have faced undesirable trade-offs with respect to capacity control and harmonic mitigation.
Method used
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[0011]With reference to FIG. 1 there is illustrated an exemplary HVACR system 100 which includes a refrigerant loop comprising compressors 110 and 111, a condenser 120, and an evaporator 130. Refrigerant flows through system 100 in a closed loop from compressors 110 and 111 to condenser 120 to evaporator 130 and back to compressors 110 and 111. Various embodiments may also include additional refrigerant loop elements including, for example, valves for controlling refrigerant flow, refrigerant filters, economizers, oil separators and / or cooling components and flow paths for various system components.
[0012]Compressor 110 is driven by a drive unit 150 including a permanent magnet electric motor 170 which is driven by a variable frequency drive 155. In the illustrated embodiment, variable frequency drive 155 is configured to output a three-phase PWM drive signal, and motor 170 is a surface magnet permanent magnet motor. Use of other types and configurations of variable frequency drives ...
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Apparatuses, methods, and systems of multiple load control for variable frequency drive harmonic mitigation are disclosed. An exemplary embodiment includes a system including a plurality of loads including at least one compressor configured to compress refrigerant. The plurality of loads are driven by a plurality of electric motors. The plurality of electric motors are driven by a plurality of variable frequency drives. The plurality of variable frequency drives are electrically coupled to an AC source. In operation a desired cooling capacity of the system is determined, a harmonic mitigation control parameter is determined, and output of one or more of the variable frequency drives is activated, deactivated, adjusted or modulated to reduce the input harmonics and provide the desired cooling capacity.
Description
BACKGROUND[0001]A number of efforts have been made to mitigate power supply line input harmonics in variable frequency drive systems, including link chokes, line reactors, multiphase techniques, harmonic filters, active harmonic mitigation techniques, and combinations of these and other efforts. While providing some benefits, these approaches suffer from a number of shortcomings including cost, complexity, efficiency, efficacy, and adaptability. These issues may be of particular interest in heating, ventilation, air conditioning, or refrigeration (HVACR) applications which may include multiple loads driven by electric motors which are in turn driven by variable frequency drives. Harmonic mitigation is needed in such systems to improve losses and avoid system damage, yet the controls for such systems typically require one or more load drives to be turned on or off, or output controlled as a function of system capacity demand, such as a commanded system cooling capacity. Heretofore th...
Claims
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IPC IPC(8): F25B49/02
CPCF25B49/022B60H1/00428B60H1/3211B60H1/3222B60H2001/3292Y02T10/88
Inventor SYKORA, BENJAMIN JAMESWEST, NATHAN THOMASFOYE, DAVID MARSHALL
Owner TRANE INT INC