Abstract:
A sensor for sensing a usage status of an electrical device and its associated method are disclosed. The sensor is disposed at a near-end of a power line of the electrical device. The sensor provided with a magnetic detector, an analog-to-digital converter and a controller. The magnetic detector is close to the power line to detect a magnetic field change around the power line to correspondingly generate an analog signal. The analog-to-digital converter (ADC) is used to receive the analog signal and convert the analog signal to a digital signal. The controller is used to receive the digital signal and generate an indication signal to accordingly learn at least one of statuses of being turned on and turned off the electrical device.

Description:
CROSS REFERENCE TO RELATED PATENT APPLICATION 
       [0001]    This patent application is based on U.S. provisional application No. 62/313,776 filed on Mar. 27, 2016; and this patent application also claims the foreign priority on the Taiwan, R.O.C. patent application No. 105141362 filed in Taiwan on Dec. 14, 2016, the entire contents of all of which are hereby incorporated by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a sensing technology, and more particularly, to a sensor for sensing a usage status of an electrical device and an associated method. 
       BACKGROUND OF THE INVENTION 
       [0003]    To determine a usage status of an electrical device, e.g., whether the electrical device is turned on or turned off, an additional component needs to be provided on an electrical appliance or mechanical device that consumes electrical power. In a conventional solution that uses an ammeter or a power measuring equipment, an existing power line needs to disconnected, and the ammeter or power measuring equipment is then connected in series thereto. However, the above method not only involves complex application details but also impairs an existing wire, hence resulting limitations for a user. Further, if a clamp meter is adopted, the clamp meter cannot be readily used in a two-wire application. In order to use the two-wire, the two-wire power line needs to be separated, which is equivalently decomposing the power line, in a way that user may be less willing to use such approach. There are some other methods having issues of high costs. 
       SUMMARY OF THE INVENTION 
       [0004]    The disclosure is directed to a sensor for sensing a usage status of an electrical device and an associated sensing method. The sensor and sensing method of the disclosure need not separate a multi-wire power line that may then stay intact, and is thus suitable for single-wire, two-wire or even three-phase power lines. 
         [0005]    For achieving the above, the present invention provides a sensor for sensing a usage status of an electrical device disposed at a near-end of a power line of the electrical device. The sensor provided with a magnetic detector, an analog-to-digital converter and a controller. The magnetic detector is close to the power line to detect a magnetic field change around the power line to correspondingly generate an analog signal. The analog-to-digital converter (ADC) is used to receive the analog signal and convert the analog signal to a digital signal. The controller is used to receive the digital signal and generate an indication signal to accordingly learn at least one of statuses of being turned on and turned off the electrical device. 
         [0006]    The present invention further provides a sensing method adapted for a sensor to sense a usage status of an electrical device. The sensor, disposed at a near-end of a power line of the electrical device, comprises a magnetic detector, an analog-to-digital converter (DAC) and a controller. The sensing method comprises the steps of: disposing the magnetic detector close to the power line to detect a magnetic field change around the power line and to accordingly generate an analog signal; receiving the analog signal and converting the analog signal to a digital signal by the ADC; and receiving the digital signal and generating an indication signal by the controller to according learn at least one of statuses of being turned on and turned off the electrical device. 
         [0007]    In the sensor and sensing method for sensing a usage status of an electrical device according to the disclosure, a usage status, e.g., being turned on or turned off, of the electrical device may be determined without modifying original power lines of an electrical appliance or mechanical device. Further, involving no risks of damaging power lines or wires, the sensor and sensing method may be easily installed or performed by a user, and are thus suitable for single-wire, two-wire or even three-phase power lines. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. In the drawings: 
           [0009]      FIG. 1  is a block diagram of a sensor for sensing a usage status of an electrical device according to a preferred embodiment; 
           [0010]      FIG. 2  is a section diagram of a sensor for sensing a usage status of an electrical device of the disclosure applied to a power line; and 
           [0011]      FIG. 3  is a block diagram of a sensor for sensing a usage status of an electrical device according to another preferred embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0012]    A sensor for sensing a usage status of an electrical device of the disclosure may be installed to a power line, or a wire through which a current passes, of an electrical device whose usage status is to be determined. A certain value of current is loaded when an electrical device is in use, and such load current produces a corresponding magnetic field. Thus, using a device with one or multiple elements that sense its magnetic field, a usage status of being turned on or turned off may be determined for that electrical device. Furthermore, regarding a value change in the load current, due to special current patterns of different electrical devices in use, special magnetic field changes are correspondingly generated. By determining these magnetic field changes in corresponding special patterns, the corresponding usage status of being turned on or turned off may be correctly determined. For example, an electrical appliance powered by an alternating current has a current load pattern of a sine wave, and this current in a sinusoidal pattern also produces corresponding magnetic field changes. Therefore, even in the presence of magnetic interference generated in an external environment, whether the alternating-current electrical appliance is in use may be confirmed through whether a sine wave is generated. 
         [0013]      FIG. 1  shows a block diagram of a sensor for sensing a usage status of an electrical device according to a preferred embodiment of the disclosure. As shown, a sensor  1  for sensing a usage status of an electrical device of the disclosure is disposed close to a power line  2  of an electrical device under test. Preferably, the sensor  1  may be connected on the power line  2  of the electrical appliance in socketed manner (as shown in  FIG. 2 , to be described in detail shortly). A position for disposing the sensor  1  for sensing a usage status of an electrical device may be, for example but not limited to, close to a power socket end of the power line  2 , close to a body end of the electrical device, or close to a center between the power socket end and the body end of the electrical device. The sensor  1  for sensing a usage status of an electrical device according to the disclosure is mainly for sensing magnetic field strength and/or changes induced by the current in the power line  2 . Thus, given that the magnetic field strength and/or changes of any position of the power line can be sufficiently sensed, the position and method for disposing the sensor  1  do not pose limitations on the application scope of the sensor  1  for sensing a usage status of an electrical device according to the disclosure. 
         [0014]    Again referring to  FIG. 1 , the sensor  1  for sensing a usage status of an electrical device according to the disclosure includes a magnetic detector  10 , an analog-to-digital converter (ADC)  12  and a controller  14 . The magnetic detector  10  detects a magnetic field strength or change inducted by the power line  2  under test. A result of the magnetic field strength sensed by the magnetic detector  10  may be outputted in form of an analog voltage or current signal  11 . Preferably, the magnetic detector  10  may be formed by a magneto-impedance sensor, a magneto-resistance sensor, a giant magneto-resistance sensor or a Hall sensor. The ADC  12  receives the analog signal  11  outputted from the magnetic detector  10 , and performs analog-to-digital conversion on the ADC signal  11  to output a corresponding digital signal  13  to the controller  14 . A bit count of the resolution required by the ADC is determined according to an application situation and a required precision, and may be 8, 10, 12 or 16 bits. The controller  14  receives the digital signal  13  outputted from the ADC  12 , and performs a control analysis on the digital signal  13  to output an indication signal that determines the usage status of the electrical device. In general, the controller is implemented by a microprocessor, which may be an 8-bit, 16-bit, 32-bit or 64-bit microprocessor, or even a microprocessor in a higher bit count. 
         [0015]      FIG. 2  shows a section diagram of the sensor  1  for sensing a usage status of an electrical device of the disclosure disposed at a power line. As shown in  FIG. 2 , the sensor  1  for sensing a usage status of an electrical device of the disclosure is provided in form of a ferrite bead structure. A ferrite beads is a passive component for suppressing high-frequency signals in a circuit. Further, a ferrite bead is a special choke mostly made of ferrite, and suppresses high-frequency noises by heat dissipation generated from its high-frequency current. A ferrite bead is sometimes referred to as a magnetic ring, an EMI filter or an iron core. A simplest bead ferrite structure is a loop inductor of ferrite, and such magnetic ring in a clamp shape may be directly fastened on the power line  2 . Other details of the ferrite structure are generally known to one person skilled in the art, and shall be omitted herein. 
         [0016]    As shown in  FIG. 2 , the denotation  20  represents the magnetic ring, and the denotation  22  represents an anti-magnetic interference outer cover that may be formed by ferrite. The components (including the magnetic detector  10 , the ADC  12  an the controller  14 ) of the sensor  1  for sensing a usage status of an electrical device shown in  FIG. 1  are integrated and provided on a signal collection board  24 , and both of the sensor  1  and the signal collection board  24  are placed close to the power line  2  of the electrical device. Alternatively, the sensor  1  may be embedded into the signal collection board  24 , as shown in  FIG. 2 . The signal collection board  24  is usually formed by a high-permeability material, of which ferrite is one example. As previously described, the magnetic detector  10  in the sensor  1  for sensing a usage status of an electrical device needs to be placed close to the power line  2  as much as possible. In the application, the term “close to” refers to, for example but not limited to, means such as being attached, mounted or embedded. 
         [0017]    Further, the sensor  1  for sensing a usage status of an electrical device of the disclosure and the power line  2  are both encircled in the magnetic ring  20 , which is further covered by the anti-magnetic interference outer cover  22 . Thus, the sensor  1  for sensing a usage status of an electrical device is enveloped, and external magnetic field interference is blocked by a shielding effect. As the ADC  12  or controller  14  in the sensor  1  for sensing a usage status of an electrical device of the disclosure processes digital signals and is less likely affected by electrical field or magnetic field interference, the ADC  12  or controller  14  may be alternatively placed outside the anti-magnetic interference outer cover  22 . In  FIG. 2 , a communication module  16  is further depicted. The communication module  16  receives an indication signal  15  outputted from the controller  14  in the sensor  1 . The indication signal  15  is processed by the communication module  16  and then transmitted for a backend data processing apparatus for further processing, analysis and/or control, such that the sensor for sensing a usage status of an electrical device of the disclosure may be more extensively applied. To ensure that the communication module  16  provides better transmission quality, preferably, the communication module  16  is disposed outside of the anti-magnetic interference outer cover  22 . 
         [0018]      FIG. 3  shows a block diagram of a sensor for sensing a usage status of an electrical device according to another preferred embodiment of the disclosure. As shown, a communication module  30  is disposed between the ADC  12  and the controller  14 . The communication module  30  is employed to transmit the digital signal  13  to the controller  14  for further processing. Preferably, the communication module  30  should be in compliance with telecommunication standards such as WiFi, Bluetooth, Zigbee or the like. 
         [0019]    Although induced magnetic fields of differently phased currents in a power line no matter having 1, 2, 3 or even more wires counteract one another, the disclosure is aimed to serve a main purpose of sensing a turned on or turned off status of an electrical device rather than detecting an accurate current value of the electrical device. Thus, residual magnetic fields and changes after induced magnetic fields of differently phased currents counteract one another are still sufficient for determining a turn on or turned off status of the electrical device. 
         [0020]    It should be noted that, the hardware in  FIG. 2  are for illustration purposes, and is one of numerous application examples non-limiting to the scope of the disclosure. 
         [0021]    While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not to be limited to the above embodiments. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation to encompass all such modifications and similar structures.