CLIAMS:WE CLAIM:

1. A method for reducing power consumption of a digital scroll compressor, the method comprising the steps of:
monitoring the digital scroll which alternates periodically between a loading and unloading state to compress refrigerant as per requirement; and
supplying voltage to the digital scroll compressor depending upon the loading and unloading state of the digital scroll compressor,
wherein the voltage supplied to the digital scroll compressor is reduced during unloaded state of the digital scroll compressor.

2. The method as claimed in claim 1, wherein the monitoring step includes communicating the loading and unloading state to a voltage control module.

3. The method as claimed in claim 1, wherein the voltage supplied to the digital scroll compressor is reduced to a voltage required to keep running of the digital scroll compressor.

4. The method as claimed in claim 1 or claim 2, wherein the voltage reduced is less than the rated voltage required for operation of the digital scroll compressor.

5. The method as claimed in claim 1, wherein the voltage supplied is reduced by changing firing angle of a TRIAC 3 phase circuit provided in a voltage control module.

6. The method as claimed in claim 1, wherein the reduced voltage is provided by a capacitor provided in parallel to a TRIAC 3-phase circuit in a voltage control module, wherein the TRIAC 3-phase circuit is configured to switch-off at unloading state of the digital scroll compressor.

7. A system for reducing power consumption of a digital scroll compressor, the system comprising:
a controller connected to the digital scroll compressor for monitoring loading and unloading state of the digital scroll compressor; and
a voltage control module connected to the digital scroll compressor, the voltage control module supplies voltage to the digital scroll compressor depending upon the loading and unloading state of the digital scroll compressor.

8. The system as claimed in claim 7, wherein the voltage control module is a TRIAC 3 phase circuit.

9. The system as claimed in claim 7, wherein the voltage control module comprises a TRIAC 3 phase circuit and a capacitor having capacity to store voltage required for running the digital scroll compressor unloading state.

10. A digital scroll compressor comprising a voltage control module supplying voltage to the digital scroll compressor depending upon the loading and unloading state of the digital scroll compressor.

11. A digital scroll compressor as claimed in claim 10, wherein the voltage control module is connected to a controller for monitoring loading and unloading state of the digital scroll compressor.

12. A digital scroll compressor as claimed in claim 11, wherein the controller is a separate controller or a controller of refrigerant system operating the digital compressor based on demand of cooling.
Dated this 06th day of March, 2014

For Blue Star Limited
By their Agent

(Manish Saurastri)
Patent Agent No.: IN/PA 291
KRISHNA & SAURASTRI ASSOCIATES
,TagSPECI:FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
METHOD AND SYSTEM FOR REDUCING POWER CONSUMPTION OF A DIGITAL SCROLL COMPRESSOR;
BLUE STAR LIMITED A COMPANY INCORPORATED UNDER THE COMPANIES ACT, 1956, WHOSE ADDRESS IS KASTURI BUILDINGS, MOHAN T. ADVANI CHOWK, JAMSHETJI TATA ROAD, MUMBAI – 400 020, MAHARASHTRA, INDIA

THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

FIELD OF THE INVENTION
[001] The invention relates to compressors, and more particularly to reducing power consumption of digital scroll compressors.
BACKGROUND OF THE INVENTION
[002] VRF system works on the principle to adjust output of compressor to match the load by varying refrigerant flow. This is achieved using either variable speed compressor or by using digital scroll technology. In variable speed compressor inverter drive is used to change the speed of special design compressor. In case of digital scroll the variable flow is achieved by alternate loading and unloading compressor. The ratio of loaded and unloaded period decides the variable flow. However, during loaded state and unloaded state the compressor motor operates at full speed.
[003] In an example, consider a digital scroll compressor which is used for varying refrigerant flow in a refrigeration system by controlling the time duration of compression or loaded state and non-compression cycles or unloaded state. During the compression cycle, the motor runs at full-load, and during the non-compression cycle, the motor runs at no-load. The variation capacity is usually from 15% min. to 100%. Consider Figure 1, where Ta is the compression cycle and Tb is the non-compression cycle with the total cycle time being Tt = Ta +Tb. The total cycle time (Tt) may be a suitable value. In an example, the total cycle time may be from 15 to 20 sec.
[004] In 100% compression cycle, Ta = Tt and Tb = 0. By varying the ratio of Ta and Tb, the total capacity of the compressor can be varied from 15% to 100%. During the non-compression cycle, power consumed may be considered as a waste, as there is no compression being performed.
SUMMARY OF THE INVENTION
[005] In one aspect provides a system for reducing power consumption of a digital scroll compressor, the system comprising a controller connected to the digital scroll compressor for monitoring loading and unloading state of the digital scroll compressor, and a voltage control module connected to the digital scroll compressor. According to the present invention, the voltage control module supplies voltage to the digital scroll compressor depending upon the loading and unloading state of the digital scroll compressor.
[006] In another aspect, the present invention provides a method for reducing power consumption of a digital scroll compressor, the method comprising the steps of monitoring the digital scroll which alternates periodically between a loading and unloading state to compress refrigerant as per requirement. The voltage supplied to the digital scroll compressor according to the present invention is reduced during unloaded state of the digital scroll compressor.
[007] In one another aspect, the present invention provides a digital scroll compressor comprising a voltage control module supplies voltage to the digital scroll compressor depending upon the loading and unloading state of the digital scroll compressor.
[008] Accordingly, the present invention reduces power consumption of a digital scroll compressor during the non-compression cycle.
DEFINITIONS:
[009] Rated voltage: It is the nominal voltage at which any electrical equipment, in this case digital compressor motor, is designed to operate. The operation at the rated voltage shall provide the rated performance. Generally, the equipment can operate above or below the rated voltage, based on its design.

BRIEF DESCRIPTION OF THE DRAWINGS
[010] Reference will be made to embodiments of the invention, examples of which may be illustrated in the accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in the context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.
Figure 1 shows a compression and decompression cycle of a digital scroll compressor;
Figure 2 shows a system for reducing power consumption of a digital scroll compressor in accordance with an embodiment of the present invention;
Figure 3 shows preferred embodiments of voltage control module according to the present invention through 3A-3B; and
Figure 4 shows a flowchart of process according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION
[011] Various embodiments of the present invention provide a method and system for reduction in power consumption of a digital scroll compressor.
[012] Referring Figures 2, 3A and 3B shows a system (200) for reducing power consumption of a digital scroll compressor (250) connected to a refrigerant circuit. A refrigerant circuit is not as shown as it is very well known in the art. The system comprises a controller (230) and a voltage control module (210).
[013] The controller (230) as shown in the Figures 2, 3A and 3B is connected to the digital scroll compressor (250). The controller (230) operates and/or monitors loading and unloading state of the digital scroll compressor (250). In an embodiment, the controller can be a separate unit that will monitor loading and unloading state of the digital scroll compressor. Alternatively, the controller can be controller of the refrigeration system which operates and monitors loading and unloading state of the digital compressor according to the demand of cooling.
[014] According to the present invention, the controller (230) is further connected with the voltage control module (210) and communicates the loading and unloading state of the digital scroll compressor (250). The voltage control module (210) regulates the voltage supplied to the digital scroll compressor (250) depending upon the loading and unloading state of the digital scroll compressor (250). In this regard, during loading state of the digital scroll compressor the voltage control module will supply the rated voltage.
[015] During unloading state of the digital scroll compressor (250), the voltage control module (210) reduces the voltage supplied to the digital scroll compressor (250) to a predetermined voltage. The predetermined voltage level is lower than the rated voltage but enough to keep the digital scroll compressor running. In an embodiment, the voltage can be reduced up to a value for running the digital scroll compressor below the rated voltage of the digital scroll compressor. Based on the Inventors’ experimental experiences over this invention, it is found that the voltage can be reduced to 70% of rated voltage of the digital scroll compressor. However, according to the Inventors, the reduced voltage can be decided for each system by experiments as it depends upon various conditions such as manufacturer of the digital scroll compressor, refrigeration system etc. Advantageously, the present invention by reducing the voltage supplied to the digital scroll compressor during the unloaded state thereby reducing the power consumed by the digital scroll compressor.
[016] Figure 3A shows a system (300) comprising a preferable embodiment of a voltage control module (310) of the present invention. As shown in Figure 3A, the voltage control module (310) comprises a TRIAC 3 phase circuit (305). The TRIAC 3 phase circuit (305) receives a signal from the controller (230) indicating loading and unloading state of the digital scroll compressor (250). The TRIAC 3 phase circuit (305) accordingly changes its firing angle depending upon loading and unloading state of the digital scroll compressor (250), thereby change the voltage supplied to the digital scroll compressor (250). The firing angle of the TRIAC 3 phase circuit can be decided preferably by experiments for each refrigeration system and/or design of the digital scroll compressor wherein the TRIAC 3 phase circuit provides a rated or required voltage to the digital compressor at loading or compression cycle and reduced voltage less than the rated voltage at unloading or non-compression cycle of the digital scroll compressor. Further, it is well known about changing of firing angle of the TRIAC 3-phase circuit, hence not required to describe in detailed here.
[017] Figure 3B shows a system (400) comprising another preferable embodiment of a voltage control module (410) of the present invention. In this embodiment as shown in Figure 3B, the voltage control module (410) comprises a TRIAC 3 phase circuit (405) and a capacitor (415). The capacitor (415) has capacity to store voltage required for running the digital scroll compressor (250) during unloading state. According to the present invention, the TRIAC 3 phase circuit (405) and capacitor (415) are connected in parallel. In this voltage control module (410), the TRIAC 3 phase circuit (405) is configured to switch-OFF during the non-compression or unloading cycle. When the TRIAC 3 phase circuit (405) switches OFF, the capacitor (415) comes in series, completes the circuit and provides a reduced voltage to the digital scroll compressor (250) required for running the compressor at non-compression or unloading cycle. Advantageously, the capacitor (415) provides the reduced voltage less than the rated voltage of the digital scroll compressor which is predetermined based on experiments and/or design of the digital scroll compressor.
[018] Referring Figure 4 shows a method for reducing power consumption of a digital scroll compressor in accordance with an embodiment of the invention.
[019] At step ‘4A’, the controller monitors the loading and unloading state of the digital scroll compressor. It is to be understood by the person skilled in the art that the digital scroll compressor alternates periodically between a loading and unloading state to compress refrigerant and the cycles in some cases are of a few seconds. The loading and unloading of the compressor though periodic is as per demand. The controller is configured to continuously monitor and/or operate the loading and unloading state.
[020] At step ‘4B’, the controller communicates with the voltage control module supply information regarding the loading and unloading state of the digital scroll compressor.
[021] At step ‘4C’, the voltage control module based on the information received from the controller will reduce voltage supplied to the digital scroll compressor during unloaded state of the digital scroll compressor or supply rated voltage to the digital scroll compressor during the loaded state of the digital scroll compressor. According the present invention, the voltage supplied to the digital scroll compressor is reduced to a voltage required to keep running of the digital scroll compressor. According to the present invention, the voltage reduced is less than the rated voltage required for operation of the digital scroll compressor. The voltage supplied to the digital scroll compressor is a value for running the digital scroll compressor below the rated voltage of the digital scroll compressor. Based on the Inventors’ experimental experiences over this invention, it is found that the voltage can be reduced to 70% of rated voltage of the digital scroll compressor. However, according to the Inventors, the reduced voltage can be decided for each system by experiments as it depends upon various conditions such as manufacturer of the digital scroll compressor, refrigeration system etc.
[022] The present invention also provides a digital scroll compressor comprising a voltage control module supplies voltage to the digital scroll compressor depending upon the loading and unloading state of the digital scroll compressor. In another words, the voltage control module can be embedded in the digital scroll compressor. Further, the digital scroll compressor may comprise the voltage control module connected to a controller which is embedded with the voltage control module in the digital scroll compressor for monitoring loading and unloading state of the digital scroll compressor. Alternatively, voltage controller module of the digital scroll compressor can be connected to controller of the refrigeration system which operates and monitors loading and unloading state of the digital compressor according to the demand of cooling.
[023] According to the present invention, the loading and unloading state of the digital scroll compressor is monitored by a controller.
[024] According to the present invention, the voltage is varied by a voltage control module. Preferably, the voltage is varied by changing firing angle of the TRIAC 3-phase of the voltage control module. The voltage control module may include a TRIAC 3-phase and a capacitor adapted in parallel wherein reduced voltage supplied is provided by a capacitor required for running of the digital scroll compressor at unloading state when TRIAC 3-phase is configured to switch OFF.
[025] Advantageously, the present invention provides improvement in operating efficiency of a digital scroll compressor.
[026] A system for reducing power consumption of a digital scroll compressor according to the present invention is explain with an Example given below which is merely illustrative of preferred embodiments of the invention and does not limit the invention to the means referred in the example:
Example 1
[027] A system for reducing power consumption of a digital scroll compressor was connected to a typical refrigerant system comprising a digital compressor and tested. Based on the testing the power saving is calculated. The results obtained are given below in table 1:

Loading (%) Effective Power with Rated Voltage at no load Effective Power with Reduced Voltage at no load Power Saving
75% 0.925 P 0.89 P 4%
50% 0.85 P 0.78 P 8%
25% 0.775 P 0.67 P 14%
where, P is the power consumed by the digital scroll compressor at full load.

[028] Thus as shown in table, the system of the present invention reduces the power consumption of a digital scroll compressor based on the loading and unloading cycle of the digital scroll compressor which helps directly in reduction in the electricity consumption.
[029] While the present invention has been described with respect to certain embodiments, it will be apparent to those skilled in the art that the voltage supplied to compressor means voltage supplied to motor of the compressor. Further, various changes and modification may be made without departing from the scope of the invention as defined in the following claims: