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United States Patent Application	20090133418
Kind Code	A1
Lee; Chen Ta ;   et al.	May 28, 2009

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Claims

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1. A plug-in circuit, disposed on a cooling system, wherein the cooling system comprises an external terminal and an alternating current (AC) compressor, the plug-in circuit comprising:an AC to AC inverter, coupled to and between the external terminal and the AC compressor, for converting an external AC voltage received by the external terminal to an internal AC voltage to supply the AC to the AC compressor; andan inverter control circuit, coupled to the AC to AC inverter, for outputting a control signal to AC to AC inverter to control frequency of the internal AC voltage according to an external parameter.

2. The plug-in circuit according to claim 1, wherein the external parameter comprises environment's temperature.

3. The plug-in circuit according to claim 2, wherein the inverter control circuit controls the AC to AC inverter in a fixed frequency of the internal AC voltage when the environment's temperature varies within a preset range.

4. The plug-in circuit according to claim 2, wherein the inverter control circuit controls to increase the frequency of the internal AC voltage a preset value at each preset time when the environment's temperature is higher than a first boundary limit of temperature of a preset range, the inverter control circuit controls to decrease the frequency of the internal AC voltage the preset value at each preset time when the environment's temperature is lower than a second boundary limit of temperature of the preset range.

5. The plug-in circuit according to claim 1, wherein the inverter control circuit is coupled to the AC compressor and the external parameter is refrigerant pressure.

6. The plug-in circuit according to claim 5, wherein the inverter control circuit controls to decrease the frequency of the internal AC voltage a preset value at each preset time when the refrigerant pressure is lower than a first boundary limit of pressure of a preset range, the inverter control circuit controls to increase the frequency of the internal AC voltage the preset value at each preset time when the refrigerant pressure is higher than a second limit of pressure of the preset range.

7. The plug-in circuit according to claim 5, wherein the inverter control circuit controls the AC to AC inverter in a fixed frequency of the internal AC voltage when the refrigerant pressure varies within a preset range.

8. The plug-in circuit according to claim 1, wherein the AC to AC inverter sets the frequency of the internal AC voltage to a preset frequency when the frequency of the internal AC voltage is higher than or equal to a preset frequency.

9. The plug-in circuit according to claim 1, wherein the cooling system further comprises a indoor unit coupled to the inverter control circuit, wherein the indoor unit is used for detecting an indoor temperature to output a start-on signal to the inverter control circuit, wherein the start-on signal is disabled when the indoor temperature is lower than a preset value, and then the AC compressor is disabled.

10. The plug-in circuit according to claim 1, wherein the inverter control circuit is coupled to the AC compressor for detecting a temperature or a refrigerant pressure of the AC compressor, when the refrigerant pressure of the AC compressor is higher than a protected pressure, the inverter control circuit controls the AC to AC inverter to stop the AC compressor, when the temperature of the AC compressor is higher than a protected temperature, the inverter control circuit controls the AC to AC inverter to stop the AC compressor.

11. A cooling system, comprising:an external terminal, receiving an external alternating current (AC) voltage;an AC compressor;an AC to AC inverter, coupled to and between the external terminal and the AC compressor for converting an external AC voltage to an internal AC voltage to supply to the AC compressor; andan inverter control circuit, coupled to the AC to AC inverter, for outputting a control signal to the AC to AC inverter to control frequency of the internal AC voltage according to an external parameter.

12. The cooling system according to claim 11, wherein the external parameter is environment's temperature.

13. The cooling system according to claim 12, wherein the inverter control circuit controls the AC to AC inverter in a fixed frequency of the internal AC voltage when the environment's temperature varies within a preset range.

14. The cooling system according to claim 12, wherein the inverter control circuit controls to increase the frequency of the internal AC voltage a preset value at each preset time when the environment's temperature is higher than the first boundary limit of temperature of a preset range, the inverter control circuit controls to decrease the frequency of the internal AC voltage the preset value at each preset time when the environment's temperature is lower than the second boundary limit of temperature of the preset range.

15. The cooling system according to claim 11, wherein the inverter control circuit is coupled to the AC compressor and the external parameter is refrigerant pressure.

16. The cooling system according to claim 15, wherein the inverter control circuit controls to decrease the frequency of the internal AC voltage a preset value at each preset time when the refrigerant pressure is lower than a first boundary limit of pressure of a preset range, the inverter control circuit controls to increase the frequency of the internal AC voltage the preset value at each preset time when the refrigerant pressure is higher than a second boundary limit of pressure of the preset range.

17. The cooling system according to claim 15, wherein the inverter control circuit controls the AC to AC inverter in a fixed frequency of the internal AC voltage when the refrigerant pressure varies within a preset range.

18. The cooling system according to claim 11, wherein the AC to AC inverter sets the frequency of the internal AC voltage to a preset frequency when the frequency of the internal AC voltage is higher than or equal to a preset frequency.

19. The cooling system according to claim 11, wherein the cooling system further comprises a indoor unit coupled to the inverter control circuit, wherein the indoor unit is used for detecting an indoor temperature to output a start-on signal to the inverter control circuit, wherein the start-on signal is disabled when the indoor temperature is lower than a preset value, and then the AC compressor is disabled.

20. The cooling system according to claim 11, wherein the inverter control circuit is coupled to the AC compressor for detecting a temperature and a refrigerant pressure of the AC compressor, when the refrigerant pressure of the AC compressor is larger than a secured pressure or the temperature of the AC compressor is larger than a secured temperature, the inverter control circuit controls the AC to AC inverter to stop the AC compressor.

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Description

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BACKGROUND OF THE INVENTION

[0001]1. Field of the Invention

[0002]The present invention relates to a cooling system, and more particularly, to a plug-in circuit and a cooling system thereof.

[0003]2. Description of the Related Art

[0004]In recent years, due to the development of technology, a cooling system, such as an air conditioner, a refrigerator, a freezer and so on, becomes an indispensable electric appliance in the present days. However, the power consumption of the cooling system is also the largest among the electric appliances in the present days.

[0005]FIG. 1 illustrates a circuit block diagram depicting a conventional air conditioner without inverter control. Referring to FIG. 1, the circuit is illustrated utilizing an air conditioner with splitting type as the example. The air conditioner includes an indoor unit 11 and an outdoor unit 12, wherein the outdoor unit 12 includes an alternating current (AC) compressor 121 and a control circuit 122. The coupling relationship of the circuit of the air conditioner is shown as FIG. 1. Thereinafter, the operational concept thereof is described. First, assume the indoor temperature is 30 degrees in Celsius, and then user uses a remote control to control the indoor unit 11 to set up an indoor temperature, such as 25 degrees in Celsius. Next, the control circuit 122 starts to supply the power voltage to the AC compressor 121, wherein the AC compressor will be kept to operate at 100% power consumption. In general, the indoor unit 11 has a built-in temperature detector.

[0006]Assuming the indoor is lower than 25 degrees in Celsius through the continuous operation of the circuit, the temperature detector of the indoor unit 11 disables a start-on signal transmitted to the control circuit 122, and then the control circuit 122 cuts off the AC power voltage supplied to the AC compressor 121 to disable the AC compressor 121. When the indoor temperature is higher than 25 degrees in Celsius, the temperature detector of the indoor unit 11 enables the transmitted start-on signal, and then the AC compressor 121 is operated again.

[0007]However, the cooling system without inverter control usually generates unstable noise due to the stop-and-go AC compressor, and the indoor temperature of user's feeling varies a lot, sometimes cold, sometimes warm. In addition, a large start-on current is so demanding when the AC compressor is operating. Therefore, it causes extremely large power consumption when the AC compressor starts on and off frequently.

[0008]Due to the above-mentioned drawback, a direct current (DC) inverter control is provided in the prior art. Nevertheless, due to the high cost of the DC inverter circuit, the price of the air conditioner with inverter control remains high. The customers of the air conditioner with DC inverter control may need 5 to 10 year to pay back their expense. If users bought air conditioner with DC inverter control is unfortunately damaged, the customer has to pay a lot payment for repairing it. Thus, a lot of people still do not want to buy the air conditioner with DC inverter control.

SUMMARY OF THE INVENTION

[0009]In view of the above-mentioned problems, the present invention is directed to a plug-in circuit and a cooling system thereof for increasing the efficiency of a compressor, reducing the power consumption of the cooling system and extending the operating life of the compressor.

[0010]To achieve the above-mentioned objective and others, a cooling system is provided in the present invention. The cooling system includes a plug-in circuit, an external terminal and an AC compressor. The plug-in circuit includes an AC to AC inverter and an inverter control circuit. The AC to AC inverter is coupled to and between the external terminal and the AC compressor for converting an external AC voltage received by the external terminal to an internal AC voltage to supply to the AC compressor. The inverter control circuit is coupled to the AC to AC compressor for outputting a control signal to the AC to AC inverter to control frequency of the internal AC voltage according to an external parameter.

[0011]According to the plug-in circuit and the cooling system thereof in the embodiment of the present invention, the external parameter is environment's temperature. When the environment's temperature is higher than the first boundary limit of temperature of a preset range, the inverter control circuit increases the frequency of the internal AC voltage to a preset value at each preset time. When the environment's temperature is lower than the second boundary limit of temperature of a preset range, the inverter control circuit will decrease the frequency of the internal AC voltage to a preset value at each preset time. In another embodiment, the inverter control circuit is coupled to the AC compressor and the external parameters are refrigerant pressures of the AC compressor. When the refrigerant pressure of the AC compressor is lower than the first boundary pressure of a preset range, the inverter control circuit controls to decrease the frequency of the internal AC voltage a preset value at each preset time. When the refrigerant pressure of the AC compressor is higher than the second boundary pressure of a preset range, the inverter control circuit controls to increase the frequency of the internal AC voltage the preset value at each preset time.

[0012]The essence of the present invention is to add an extra AC to AC inverter between the conventional AC compressor and the conventional external terminal. Under an external environment, such as an environment's temperature or the refrigerant pressure of the AC compressor, is varied, the AC driving voltage supplied into the AC compressor is adjusted to an adapted frequency. Thus, the efficiency of the AC compressor is increased significantly, and the power consumption of the cooling system is relatively reduced. In addition, the operating life of the AC compressor can be lasted longer since the AC compressor is not stop-and-go so frequently.

[0013]Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given in terms of illustration only, since various changes and modifications within the concept and scope of the invention will become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]The present invention will become more fully understood from the detailed description given hereinafter and the accompanying drawings which are given in terms of illustration only, and thus are not limited of the present invention, and wherein:

[0015]FIG. 1 illustrates a circuit block diagram depicting a conventional air conditioner without inverter control.

[0016]FIG. 2 illustrates a circuit block diagram depicting a cooling system according to an embodiment of the present invention.

[0017]FIG. 3 illustrates a circuit block diagram depicting a cooling system according to an embodiment of the present invention.

EMBODIMENT OF THE INVENTION

[0018]FIG. 2 illustrates a circuit block diagram depicting a cooling system according to an embodiment of the present invention. Referring to FIG. 2, the cooling system includes a plug-in circuit 20, an external terminal 21, an AC compressor 22 and an indoor unit 23, wherein the plug-in circuit includes an AC to AC inverter 201 and an inverter control circuit 202. The AC to AC inverter 201 is coupled to and between the external terminal 21 and the AC compressor 22. The inverter control circuit 202 is coupled to the AC to AC inverter 201. The AC to AC inverter 201 is used for converting an external AC voltage, such as 220V, received by the external terminal 21 to an internal AC voltage IAC to supply to the AC compressor 22. The inverter control circuit 202 is used for control the frequency of the internal AC voltage IAC outputted from the AC to AC inverter 201. Thereinafter, an embodiment is illustrated as the example.

[0019]Assuming the cooling system is an air conditioner with splitting type, the user sets the target temperature to 25 degrees in Celsius and the indoor temperature is 27 degrees in Celsius. When the air conditioner starts, the inverter control circuit 202 detects that the indoor temperature is 27 degrees in Celsius. Since the temperature difference between the indoor temperature and the target temperature is not very large, the compressor does not need to operate at full speed, and operation in half speed is sufficient enough. Therefore, the inverter control circuit 202 outputs the control signal Cs to the AC to AC inverter 201 to set the frequency of the internal AC voltage IAC to 30 Hz. When the indoor temperature increases to 28 degrees in Celsius, the inverter control circuit 202 controls the AC to AC inverter to increase the frequency of the internal AC voltage IAC 2 Hz at every 30 seconds. When the indoor temperature reaches 24 degrees in Celsius, the inverter control circuit 202 controls the AC to AC inverter to decrease the frequency of the internal AC voltage IAC at every 30 seconds.

[0020]The inverter control circuit 202 has a fuzzy control interval in the embodiment of the present invention. When the indoor temperature is between 24 to 26 degrees in Celsius, the inverter control circuit 202 is kept the AC to AC inverter 201 in a fixed frequency of the internal AC voltage. And, the frequency of the internal AC voltage generally is not higher than 60 Hz for protecting the AC compressor 22. In addition, since the embodiment is a plug-in circuit extra added to the conventional air condition without inverter control, the indoor unit 23 generally has a signal line to output a start-on signal EN. In the embodiment, the signal line is coupled to the inverter control circuit 202. When the indoor temperature is lower than 24 degrees in Celsius, the start-on signal is disabled, and the inverter control circuit 202 controls the AC to AC inverter to stop the AC compressor.

[0021]It should be noted that although the above-mentioned embodiment is to utilize detecting the indoor temperature as the example. manufacturers have different design for the inverter control circuit 202. Therefore, the application of the present invention should not be limited to this possible related form. In other words, it conforms to the essence of the present invention as long as the inverter control circuit 202 controls the frequency of the internal AC voltage according to the external parameter. In order that people having ordinary skill in the art may implement the embodiment, another embodiment is described in the following.

[0022]FIG. 3 illustrates a circuit block diagram depicting a cooling system according to an embodiment of the present invention. Referring to FIG. 3, the difference between the above-mentioned circuit and the circuit in FIG. 3 is the inverter control circuit 202 coupled to the AC compressor 22 to detect the temperature and the refrigerant pressure of the AC compressor 22. Generally speaking, in an open space, such as a department store or a supermarket, it cannot be accurate to detect the environment temperature. Therefore, it is able to control the frequency of the AC voltage supplied to the AC compressor by detecting the refrigerant pressures in this embodiment.

[0023]Assuming that user sets the pressure to 60 pound per square inch (psi), the inverter control circuit 202 controls the AC to AC inverter 201 in a fixed frequency of the internal AC voltage IAC, when the inverter control circuit 202 detects the low refrigerant pressure between 62 and 68, When the inverter control circuit 202 detects that the lower refrigerant pressure is higher than 68 psi, the inverter control circuit 202 controls the AC to AC inverter 201 to increase the frequency of the internal AC voltage IAC a preset value, such as 2 Hz, at every 30 seconds. When the low refrigerant pressure is higher than a boundary value, such as 71 psi, the inverter control circuit 202 controls the AC to AC inverter 201 to increase the frequency increasing rate of the frequency of the internal AC voltage to 1.5 times of level. When the low refrigerant pressure is lower than 62 psi, the inverter control circuit 202 controls the AC to AC inverter 201 to decrease the frequency of the internal AC voltage IAC the preset value, such as 2 Hz, at every 30 seconds. When the low refrigerant pressure is lower than a boundary value, such as 59 psi, the inverter control circuit 202 controls the AC to AC inverter 201 to increase the frequency decreasing rate of the frequency of the internal AC voltage to 1.5 times of level.

[0024]To sum up, the essence of the present invention is to add an extra AC to AC inverter between the conventional AC compressor and the conventional external terminal. Under the opening external environment outside, such as an environment's temperature or the refrigerant pressure of the AC compressor, is varied, the AC driving voltage supplied into the AC compressor is adjusted to an adapted frequency. Thus, the efficiency of the AC compressor is increased significantly, the power consumption of the cooling system is relatively reduced and, the operating life of the AC compressor is extended since the AC compressor is not stop-and-go so frequently. In addition, since the circuit in the embodiment of the present invention is a plug-in type which means the circuit can be added on the previous air conditioner. Therefore, the cost of the circuit of the embodiment in the present invention is comparatively lower than the cost of the air conditioner with inverter control.

[0025]While certain exemplary embodiments have been described and shown in the attached drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention, and that this invention should not be limited to the specific construction and arrangement shown and described, since various other modifications may occur to those ordinarily skilled in the art.

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