Abstract:
A power transforming device with a power-saving circuit loop is connected between a voltage source and an electric/electronic appliance, and has a micro-controller unit (MCU), a mode-switching circuit, a conversion circuit, and an output circuit. The mode-switching circuit has a switching element. The conversion circuit has an isolating element and a winding. The isolating element and one end of the winding are connected to the switching element. The output circuit has a switching element having one contact connected with the winding and another contact connected with the switching element of the mode-switching circuit. The MCU controls the isolating element and the switching elements to boost or buck down an input voltage according to the value of the input voltage, and directly outputs the input voltage without additionally consuming energy when voltage transforming operation is not required.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a power transforming device, and more particularly to a power transforming device with a power-saving circuit loop performing electromagnetic conversion only when voltage transformation is required. 
         [0003]    2. Description of the Related Art 
         [0004]    When buying home electric/electronic appliances, most people are inclined to choose those with Energy Star Certification. Energy Star is an international standard established by U.S.A for energy efficient consumer products. According to surveys of consumer shopping habits, more than seventy percent of consumers would purchase products with Energy Start Certification, and a majority of consumers think that such type of products are more durable. Once an electric/electronic product has any recognized energy-saving sticker thereon, it represents that the product possesses higher energy efficiency, and can save more energy and money for operation. 
         [0005]    With reference to  FIG. 9 , a conventional power transforming device has an auto-transformer  60 , a first switch  61 , a second switch  62 , and an output switch  63 . 
         [0006]    The auto-transformer  60  has a winding. A first end of the winding is connected to a live line N of a power source, and a second end of the winding is connected between the first switch  61  and the second switch  62 . The winding has a first tap  601  thereon. The second switch is further connected to the output switch  63 . 
         [0007]    The first switch  61  has a common terminal (COM), a normally closed terminal (NC), and a normally open terminal (NO), wherein the common terminal is connected to the live line of the power source, and the normally closed terminal (NC) and the normally open terminal (NO) are respectively connected to the second end and the first tap  601  of the winding. 
         [0008]    The second switch  62  has a common terminal (COM), a normally closed terminal (NC), and a normally open terminal (NO), wherein the normally closed terminal (NC) and the normally open terminal (NO) are respectively connected to the second end and the first tap  601  of the winding. 
         [0009]    The output switch  63  has a common terminal (COM), a normally closed terminal (NC), and a normally open terminal (NO), wherein the common terminal (COM) constitutes a power output terminal, and the normally open terminal is connected to the common terminal (COM) of the second switch  62 . 
         [0010]    As shown in  FIG. 9 , the first switch  61  and the output switch  63  are controlled in a manner that the common terminal (COM) of the first switch  61  is connected with the normally closed terminal (NC) thereof, and the common terminal of the output switch  63  is connected with the normally closed terminal (NC) thereof, and the conventional power transforming device is operated under a turn-off mode. 
         [0011]    In comparison with the turn-off mode, when the auto-transformer  60  is operated under a voltage boosting mode, the common terminal (COM) of the first switch  61  is connected with the normally open terminal (NO) thereof so that a primary winding is formed by a portion of the winding from the first tap  601  to the first end. The common terminal (COM) of the second switch  62  is connected with the normally closed terminal (NC) thereof so that a secondary winding is formed by the entire portion of the winding from the second end to the first end. The common terminal (COM) of the output switch  63  is connected with the normally open terminal (NO) thereof to output voltage. As the primary winding is a part of the secondary winding and the secondary winding has more turns than the primary winding, the output voltage is boosted. 
         [0012]    When the auto-transformer  60  is operated under a voltage bucking mode, the common terminal (COM) of the first switch  61  is connected with the normally closed (NC) terminal thereof so that a primary winding is formed by the entire portion of the winding from the second end to the first end. The common terminal (COM) of the second switch  62  is connected with the normally open terminal (NO) thereof so that a secondary winding is formed by a portion of the winding from the first tap  601  to the first end. The common terminal (COM) of the output switch  63  is connected with the normally open terminal (NO) thereof to output voltage. As the secondary winding is a part of the primary winding and the primary winding has more turns than the secondary winding, the output voltage is bucked down. 
         [0013]    With reference to  FIGS. 10 and 11 , another conventional power transforming device is substantially the same as the foregoing conventional power transforming device except that the winding further has a second tap  602  located between the first tap  601  and the first end of the winding. The normally closed terminal (NC) and the normally open terminal (NO) of the first switch  61  are respectively connected to the second end and the second tap  602  of the winding. The normally closed terminal (NC) and the normally open terminal (NO) of the second switch  62  are respectively connected to the second end and the first tap  601  of the winding. 
         [0014]    Similarly, the conventional power transforming device is operated under a turn-off mode as shown in  FIG. 10  with the common terminal (COM) of the output switch  63  connected with the normally closed terminal (NC) to turn off the power transforming device, and is operated under a direct-output mode as shown in  FIG. 11  with the common terminal (COM) of the output switch  63  connected with the normally open terminal (NO) thereof, the common terminal of the second switch  62  connected with the normally closed terminal thereof, and the common terminal of the first switch  61  connected with the normally closed terminal. During the direct-output mode, there is no voltage bucking and boosting operation as the primary and secondary windings have the same turns. 
         [0015]    When the auto-transformer  60  is operated under a voltage boosting mode, similarly, the common terminal of the first switch  61  is connected to the normally open terminal (NO) thereof so that a primary winding is formed by a portion of the winding from the second tap  602  to the first end. The common terminal (COM) of the second switch  62  is connected to the normally closed terminal (NC) or the normally open terminal (NO) thereof so that a secondary winding is formed by a portion of the winding from the second end or the first tap  601  to the first end. The common terminal (COM) of the output switch  63  is connected with the normally open terminal (NO). As the secondary winding has more turns than the primary winding, the output voltage is boosted. 
         [0016]    When the auto-transformer  60  is operated under a voltage bucking mode, the common terminal of the first switch  61  is connected to the normally closed terminal (NC) thereof so that a primary winding is formed by the entire portion of the winding from the second end to the first end. The common terminal (COM) of the second switch  62  is connected to the normally open terminal (NO) thereof so that a secondary winding is formed by a portion of the winding from the first tap  601  to the first end. The common terminal (COM) of the output switch  63  is connected with the normally open terminal (NO). As the primary winding has more turns than the secondary winding, the output voltage is bucked down. 
         [0017]    The foregoing conventional power transforming devices can all be connected to electric/electronic appliances, and are extensively applied to protect the boosting/bucking loop or the output loop. However, one end of such type of auto-transformer  60  needs to be constantly connected to the loops. Extra electromagnetic energy and power consumption are generated by the auto-transformer  60  whenever the auto-transformer  60  performs the voltage boosting/bucking operation or directly outputs the input voltage. 
       SUMMARY OF THE INVENTION 
       [0018]    An objective of the present invention is to provide a power transforming device with a power-saving circuit loop connected between a voltage source and an electric/electronic appliance, and boosting or bucking down an input voltage according to the value of the input voltage, and directly outputting the input voltage without additionally consuming energy when voltage transforming operation is not required. 
         [0019]    To achieve the foregoing objective, the power transforming device with a power-saving circuit loop has a mode-switching circuit, a conversion circuit, an output circuit, and a micro-controller unit (MCU). 
         [0020]    The mode-switching circuit has a voltage input terminal and a switching element. The switching element has a first contact and a second contact. 
         [0021]    The conversion circuit has an auto-transformer and an isolating element. 
         [0022]    The auto-transformer has at least one tap, one of which is connected to the second contact of the switching element. 
         [0023]    The isolating element has a common terminal, a normally closed terminal, and a normally open terminal. The common terminal is connected to the first contact of the switching element. The normally open terminal is connected to one end of the auto-transformer. 
         [0024]    The output circuit has a switching element and a voltage output terminal. 
         [0025]    The switching element has a third contact and a fourth contact. The third contact is connected with one of the at least one tap. The fourth contact is connected with the common terminal of the isolating element. 
         [0026]    The MCU is connected to the switching element of the mode-switching circuit, the isolating element of the conversion circuit, the switching element of the output circuit, and the voltage input terminal of the mode-switching circuit, and has at least one voltage threshold. 
         [0027]    The MCU first compares an input voltage with the voltage threshold, and controls the isolating element and the switching elements of the mode-switching circuit and the output circuit to switch their contacts for the input voltage to pass through the auto-transformer to perform a voltage boosting or bucking operation, so that an output voltage can be stably outputted and comply with the voltage threshold. When power transforming operation is not required, the isolating element can be used to isolate the auto-transformer from a power transforming loop, thereby reducing energy consumption and enhancing power utilization efficiency. 
         [0028]    Other objectives, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]      FIG. 1  is a first circuit diagram of a first embodiment of a power transforming device with a power-saving circuit loop in accordance with the present invention operated under a turn-off mode; 
           [0030]      FIG. 2  is a second circuit diagram of the power transforming device in  FIG. 1  operated under an energy-saving mode; 
           [0031]      FIG. 3  is a third circuit diagram of the power transforming device in  FIG. 1  operated under a bucking mode; 
           [0032]      FIG. 4  is a fourth circuit diagram of the power transforming device in  FIG. 1  operated under a boosting mode; 
           [0033]      FIG. 5  is a first circuit diagram of a second embodiment of a power transforming device with a power-saving circuit loop in accordance with the present invention operated under an energy-saving mode; 
           [0034]      FIG. 6  is a second circuit diagram of the power transforming device in  FIG. 5  operated under a bucking mode; 
           [0035]      FIG. 7  is a third circuit diagram of the power transforming device in  FIG. 5  operated under a boosting mode; 
           [0036]      FIG. 8  is a fourth circuit diagram of a power transforming device in  FIG. 5  operated under another boosting mode; 
           [0037]      FIG. 9  is a circuit diagram of a conventional power transforming device operated under a turn-off mode; 
           [0038]      FIG. 10  is a circuit diagram of another conventional power transforming device with two taps during a turn-off mode; and 
           [0039]      FIG. 11  is another circuit diagram of the conventional power transforming device in  FIG. 10  during a direct-output mode. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0040]    With reference to  FIGS. 1 and 2 , a power transforming device with a power-saving circuit loop in accordance with the present invention is connected between a voltage source and an electric/electronic appliance, and has a mode-switching circuit  10 , a conversion circuit  20 , an output circuit  30 , and a micro-controller unit (MCU)  40 . 
         [0041]    The mode-switching circuit  10  has a voltage input terminal, that is, a live/neutral line (L/N) of a power source, and a switching element  11 . The switching element  11  has a first contact  11 A and a second contact  11 B. In the present embodiment, the switching element  11  is a relay (Relay 1 ). The foregoing voltage input terminal is a common terminal (COM) of the Relay 1 . 
         [0042]    The conversion circuit  20  has an isolating element  21  and an auto-transformer  22 . The auto-transformer  22  has a winding. The winding has a first end connected to the neutral line of the voltage source, a second end, and a first tap  221  between the first end and the second end. The isolating element  21  has a common terminal (COM), a normally closed terminal  21 A, and a normally open terminal  21 B. The normally open terminal  21 B is connected to the second end of the winding. The first tap  221  is connected to the second contact  11 B of the switching element  11  to constitute a primary winding. In the present embodiment, the isolating element  21  is another relay (Relay 2 ). The common terminal (COM) of the Relay 2  is connected with the normally closed terminal  21 A thereof and an open circuit exists between the normally closed terminal  21 A and the auto-transformer  22  so as to isolate the auto-transformer  22 . 
         [0043]    The output circuit  30  has a switching element  31  and a voltage output terminal, that is, the live/neutral line (L/N) of the power source. The switching element  31  has a third contact  31 A and a fourth contact  31 B. The third contact  31 A is connected with the first tap  221  of the winding to constitute a secondary winding. The fourth contact  31 B is connected to the first contact  11 A of the switching element  11  and the common terminal (COM) of the isolating element  21  to constitute a power transforming loop. In the present embodiment, the switching element  31  is a relay (Relay 3 ) and the voltage output terminal is a common terminal (COM) of the Relay 3 . 
         [0044]    The MCU  40  is connected to the switching element  11  of the mode-switching circuit  10 , the isolating element  21  of the conversion circuit  20 , an excitation coil of the switching element  31  of the output circuit  30 , and the voltage input terminal of the mode-switching circuit  10 , and has a voltage threshold. The MCU  40  first compares an input voltage value with the voltage threshold. If the input voltage value differs from the voltage threshold, the MCU  40  controls the Relay 1 , Relay 2  and Relay 3  to vary a ratio of the turns of the secondary winding over the turns of the primary winding, thereby boosting or bucking down the input voltage to output a voltage meeting a desired voltage threshold and stably outputting the voltage. Otherwise, the MCU  40  controls the Relay 1 , Relay 2  and Relay 3  to operate the power transforming device in an energy-saving mode. 
         [0045]    When there is no voltage outputted from the voltage output terminal or the power transforming device is operated under a turn-off mode as shown in  FIG. 1 , the MCU  40  controls the common terminal (COM) of the Relay 1  to be connected with the first contact  11 A thereof, the common terminal of the isolating element  21  to be connected with the contact  21 A, and the common terminal (COM) of the Relay 3  to be connected with the third contact  31 A. 
         [0046]    When input voltage is directly outputted to the output terminal or the power transforming device is operated under an energy-saving mode as shown in  FIG. 2 , the MCU  40  controls the common terminal (COM) of the Relay 1  to be connected with the first contact  11 A thereof, the common terminal of the isolating element  21  to be connected with the contact  21 A, and the common terminal (COM) of the Relay 3  to be connected with the fourth contact  31 B. An open circuit exists between the normally closed terminal  21 A of the isolating element  21  and the auto-transformer  22  so as to isolate the auto-transformer  22  from the power transforming loop. The states of the Relay 1  and Relay 3  allow an input voltage equal to the voltage threshold to be directly outputted to the voltage output terminal without going through the auto-transformer  22 , and the power transforming device therefore saves more power because no power is consumed by the auto-transformer  22 . 
         [0047]    With reference to  FIG. 3 , when the power transforming device is operated under a bucking mode, the MCU  40  controls the Relay 1 , Relay 2  and Relay 3  in a manner that the common terminal (COM) of the Relay 1  is connected with the first contact  11 A thereof, the common terminal (COM) of the Relay 2  is connected with the normally open terminal  21 B thereof, and the common terminal of the Relay 3  is connected with the third contact  31 A, so that a primary winding is formed by the entire portion of the winding and a secondary winding is formed by a portion of the winding from the first tap  221  to the first end. As the primary winding has more turns than the secondary winding, an input voltage higher than the voltage threshold is bucked down to the voltage threshold and is outputted to the voltage output terminal. 
         [0048]    With reference to  FIG. 4 , when the power transforming device is operated under a boosting mode, the MCU  40  controls the Relay 1 , Relay 2  and Relay 3  in a manner that the common terminal (COM) of the Relay 1  is connected with the second contact  11 B thereof, the common terminal (COM) of the Relay 2  is connected with the normally open terminal  21 B thereof, and the common terminal of the Relay 3  is connected with the fourth contact  31 B, so that a primary winding is formed by a portion of the winding from the first tap  221  to the first end and a secondary winding is formed by the entire portion of the winding. As the primary winding has fewer turns than the secondary winding, an input voltage lower than the voltage threshold is boosted to the voltage threshold and is outputted to the voltage output terminal. 
         [0049]    With reference to  FIG. 5 , a second embodiment of a power transforming device with a power-saving circuit loop in accordance with the present invention is substantially the same as the foregoing embodiment except that the winding further has a second tap  222  located between the first tap  221  and the first end of the winding. The power transforming device is operated under an energy-saving mode, and the MCU  40  controls Relay 1 , Relay 2  and Relay  3  in a manner that the common terminal (COM) of the Relay 1  is connected with the first contact  11 A thereof, the common terminal (COM) of the Relay 2  is connected with the normally closed terminal  21 A thereof, and the common terminal (COM) of the Relay 3  is connected with the fourth contact  31 B. An open circuit exists between the normally closed terminal  21 A of the isolating element  21  and the auto-transformer  22  so as to isolate the auto-transformer  22  from the power transforming loop. The states of the Relay 1  and Relay 3  allow an input voltage equal to the voltage threshold to be directly outputted to the voltage output terminal without going through the auto-transformer  22 , and the power transforming device therefore saves more power because no power is consumed by the auto-transformer  22 . 
         [0050]    With reference to  FIG. 6 , when the power transforming device in  FIG. 5  is operated under a bucking mode, the MCU  40  controls the Relay 1 , Relay 2  and Relay 3  in a manner that the common terminal (COM) of the Relay 1  is connected with the first contact  11 A thereof, the common terminal (COM) of the Relay 2  is connected with the normally open terminal  21 B thereof, and the common terminal of the Relay 3  is connected with the third contact  31 A, so that a primary winding is formed by the entire portion of the winding and a secondary winding is formed by a portion of the winding from the first tap  221  to the first end. As the primary winding has more turns than the secondary winding, an input voltage higher than the voltage threshold is bucked down to the voltage threshold and is outputted to the voltage output terminal. 
         [0051]    With reference to  FIG. 7 , when the power transforming device in  FIG. 5  is operated under a boosting mode of, the MCU  40  controls the Relay 1 , Relay 2  and Relay 3  in a manner that the common terminal (COM) of the Relay 1  is connected with the second contact  11 B thereof, the common terminal (COM) of the Relay 2  is selectively connected with the normally closed terminal  21 A or the normally open terminal  21 B thereof, and the common terminal of the Relay 3  is connected with the third contact  31 A, so that a primary winding is formed by a portion of the winding from the second tap  222  to the first end and a secondary winding is formed by a portion of the winding from the first tap  221  to the first end. As the primary winding has fewer turns than the secondary winding, an input voltage lower than the voltage threshold is boosted to the voltage threshold and is outputted to the voltage output terminal. 
         [0052]    With reference to  FIG. 8 , when the power transforming device in  FIG. 5  is operated under another boosting mode, the MCU  40  controls the Relay 1 , Relay 2  and Relay 3  in a manner that the common terminal (COM) of the Relay 1  is connected with the second contact  11 B thereof, the common terminal (COM) of the Relay 2  is connected with the normally open terminal  21 B thereof, and the common terminal of the Relay 3  is connected with the fourth contact  31 B, so that a primary winding is formed by a portion of the winding from the second tap  222  to the first end and a secondary winding is formed by the entire portion of the winding. As the primary winding has fewer turns than the secondary winding, an input voltage lower than the voltage threshold is boosted to the voltage threshold and is outputted to the voltage output terminal. 
         [0053]    According to the foregoing embodiments, the MCU  40  first compares an input voltage with a voltage threshold built in the MCU  40 , and controls the three relays (Relay 1 , Relay 2  and Relay 3 ) for the input voltage to pass through the first tap  221 , the second tap  222  and the second end of the winding of the auto-transformer  22  to enter the bucking mode and the boosting mode, thereby outputting a voltage in compliance with desired voltage thresholds. When the input voltage is equal to the voltage threshold and the bucking mode and the boosting is not applied, the isolating element  21  is used to isolate the auto-transformer  22  from the power transforming loop to eliminate the energy consumed by the auto-transformer  22  and enhance the power utilization efficiency. 
         [0054]    Even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only. Changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.