Patent Publication Number: US-9425643-B2

Title: Wireless charging system with double detecting circuits

Description:
TECHNICAL FIELD 
     The present invention relates to a charging system, and more particularly, to a wireless charging system. 
     BACKGROUND 
     Also known in the art, wireless charging is so-called as an inductive charging, non-contact induction charging which is completed by near-field sensing for inductively coupling, and the power supply device transfers power energy to electric receiver devices. The electric receiver devices receive the power energy for charging its battery, and also for its own operational use. Because the charger transfers power energy to the electric receiver devices by inductive coupling, between the charger and the electric receiver devices are without wires connection and without conductive contacts exposed. 
     Specifically, the wireless charger has a coil, wherein AC electromagnetic field is generated by the AC via the coil. There is another coil in the electric receiver device for receiving the AC electromagnetic field, and converted into electrical energy for charging its battery for providing power to the device. This scheme is the same as the transformer which a primary winding and a secondary winding are put on the charger and the electric receiver device, respectively. If the distance between the charger and the electric receiver device is farther, it would need to add a resonant inductive coupling. 
     Wireless charging has the advantages as followings: (i) security: no need of energized contacts to avoid the risk of electric shock; (ii) durability: power transmission components without exposing, and therefore will not be eroded by moisture, oxygen in the air. Because no contacts exist, so there is no mechanical wear and flashover in connection or separation of components; (iii) making medical implant devices more security: in the implanted medical device, it does not damage to the human body&#39;s tissue as charging the implanted medical device in the human body, and without the need for wires to charge through the skin and other tissues of the body, eliminating the risk of infection; (iv) convenient: no need for wire connection while charging, as long as the charger is put nearby. Technically, a charger can charge for a plurality of electric receiver devices, in the case where a plurality of electric receiver devices are used without multiples chargers (may be omitted), without a plurality of electrical sockets, and without a plurality of wires wound around each other. 
     However, control of the current wireless charging system depends on its capturing signal, and the captured signal may be confusing because of various factors, and therefore it needs a new system to ensure clear signals to be obtained. 
     SUMMARY OF THE INVENTION 
     To address the above-mentioned issues, the invention provides a wireless charging system with double detecting circuits which utilizes the characteristic that possibility for detection points of circuit loops with noise signals simultaneous is very low to ensure a clear signal to obtain. 
     According to one aspect of the invention, it provides a wireless charging system with double detecting circuits, comprising an inductive loop including an induction coil and a capacitor, wherein the induction coil and the capacitor are connected in series. A power loop includes a power source and a driving circuit, wherein the power source is connected to an input terminal of the driving circuit, two output terminals of the driving circuit are connected to the capacitor and the induction coil respectively. A control loop includes a processor, a detection circuit, coupled to the processor and a detection point of the inductive loop so that the processor can detect an induced electric field of the inductive loop, wherein a first current or a first voltage of the inductive loop is created by the induced electric field as an induced waveform over time, an auxiliary detection circuit, connected to an auxiliary detection point of the power loop to detect the induced electric field, wherein a current or a voltage of the power loop induced by the induced electric field represents an auxiliary induced waveform over time, as the induced waveform is not applicable determined by the processor based on a protocol, the induced waveform is replaced by the auxiliary induced waveform; a control line, coupled to the processor and the power source so that the processor can control a power supply of the power source outputted to the inductive loop; an auxiliary control line, coupled to the processor and the power source so that the processor can control a phase or a frequency of the driving circuit to control the power supply for the inductive loop. The processor determines a condition of the electrical receiver device based on the induced electric field, to adjust the power supply of the power loop outputted to the inductive loop. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The components, characteristics and advantages of the present invention may be understood by the detailed descriptions of the preferred embodiments outlined in the specification and the drawings attached: 
         FIG. 1  illustrates a schematic view of one example of a wireless charging system, and an electric receiver device according to one embodiment of the present invention; 
         FIG. 2  illustrates a flow chart that the wireless charging system of the invention detects the electric receiver device and determines whether to increase the power supply for the electric receiver device for charging or not; 
         FIG. 3A  illustrates a current or a voltage of the power loop induced by the induced electric field representing an induced waveform over time; 
         FIG. 3B  illustrates a graph of the induced waveform with respect to time after filtering, and an area covered by the induced waveform; 
         FIG. 3C  illustrates a graph that a maximum peak of the induced waveform of the induced electric field is over a pre-determined peak value; 
         FIG. 3D  illustrates a graph that a maximum peak of the induced waveform of the induced electric field is under a pre-determined peak value; 
         FIG. 4A  illustrates a schematic view of one example of a wireless charging system using a full-bridge driving circuit; 
         FIG. 4B  illustrates a schematic view of one example of a wireless charging system using a half-bridge driving circuit; 
         FIG. 5  illustrates a schematic view of one example of a wireless charging system of the  FIG. 4A  using a voltage-type driving circuit; 
         FIG. 6  illustrates a schematic view of one example of a wireless charging system of the  FIG. 4A  using a single output current-type driving circuit; 
         FIG. 7  illustrates a schematic view of one example of a wireless charging system of the  FIG. 4A  using a double output current-type driving circuit; 
         FIG. 8  illustrates a flow chart of performing of the wireless charging system with a double detection lines according to one embodiment; 
         FIG. 9  illustrates a flow chart of performing of the wireless charging system with a double detection lines according to another embodiment; 
         FIG. 10  illustrates a flow chart of performing of the wireless charging system with a double detection lines according to yet another embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Some preferred embodiments of the present invention will now be described in greater detail. However, it should be recognized that the preferred embodiments of the present invention are provided for illustration rather than limiting the present invention. In addition, the present invention can be practiced in a wide range of other embodiments besides those explicitly described, and the scope of the present invention is not expressly limited except as specified in the accompanying claims. 
       FIG. 1  is a schematic view of one example of a wireless charging system  100 , and an electric receiver device  190  according to one embodiment of the present invention. A rechargeable battery can be embedded into the electric receiver device  190 , for example a mobile phone, tablet, flashlight, electric shaver, electric toothbrush, battery containing charger, notebook, juice machine, etc., which has an energy receiving coil constituted by a resonance resistance  192 , a resonant capacitor  194 , and a resonant inductor  196 . 
     As shown in  FIG. 1 , the wireless charging system  100  of the present invention may include an inductive loop  110  comprising an induction coil  116  and a capacitor  114 , wherein the induction coil  116  and the capacitor  114  are connected in series. When the electric receiver device  190  is approaching to the inductive loop  110 , electromagnetic induction is generated between the inductive loop  110  and the energy receiving coil of the electric receiver device  190 , and thereby energy transmitting from the induction coil  116  of the inductive loop  110  to the resonant inductor  196  of the electric receiver device  190 , so that the electric receiver device  190  will be able to achieve the purpose for charging. The inductive loop  110  is connected to a power loop  120 , and the power loop  120  includes a power supply to provide power to the inductive loop  110 . 
     The wireless charging system  100  of the present invention further comprises a control loop  140  including a processor  144 , a detection circuit  132  by which the processor  144  is connected to the inductive loop  110 , for the processor  144  to detect (process) an induced electric field of the inductive loop  110  and its variation as the electric receiver device  190  is close to the inductive loop  110 . A waveform  320   a  with respect to time of a first current or a first voltage of the inductive loop  110  created by the induced electric field is shown in  FIG. 3A . 
     In addition, the control loop  140  further comprises a control line  142 . The processor  144  is connected to the power loop  120  by the control line  142 , to control a power supply of the power loop  120  outputted to the inductive loop  110 . Based on the detected induced electric field, the processor  144  determines whether the electric receiver device  190  is close enough to the inductive loop  110  or not, to adjust the power supply of the power loop  120  outputted to the inductive loop  110 ; including, without increasing the power supply as the electric receiver device  190  is not close enough to the inductive loop  110 , and reducing or terminating the power supply as the electric receiver device  190  is removed. 
     Optionally, the detection circuit  132  of the control loop  140  includes a filter  134 , and an input terminal of the filter  134  is connected to a detection point of the inductive loop  110  in  FIG. 1 , for example a first detection point (A) between the power loop  120  and the capacitor  114 , or a second detection point (B) between the power loop  120  and the induction coil  116 , or a third detection point (C) between the capacitor  114  and the induction coil  116 . Also, an output terminal of the filter  134  is connected to the processor  144 . As the processor  144  has an excellent processing performance, the filter  134  may be omitted. 
       FIG. 3A  illustrates a graph of an induced waveform  320   a  with respect to time of a first current or a first voltage of the inductive loop  110  created by the induced electric field.  FIG. 3B  illustrates a graph of the induced waveform  320   a  of the  FIG. 3A  with respect to time after filtering, and an area  322  covered by the induced waveform  320   a . As shown in  FIG. 3A  and  FIG. 3B , the induced waveform  320   a  in  FIG. 3A  is filtered by the filter  134  for changing from a sawtooth waveform to an induced waveform  320   b , as shown in  FIG. 3B . 
       FIG. 4A  is a schematic diagram of the wireless charging system in  FIG. 1  using a full-bridge driver circuit. In order to further improve the performance of detection,  FIG. 4A  adds some elements as compared to the structure of  FIG. 1 . 
     As shown in  FIG. 4A , the detection circuit  132   a  of the control loop  140  includes a filter  134   a , wherein an input terminal of the filter  134   a  is connected to a detection point of the inductive loop  110 , such as a first detection point (A) between a driving circuit  124   a  and a capacitor  114 , or a second detection point (B) between the driving circuit  124   a  and an induction coil  116 , or a third detection point (C) between the capacitor  114  and the induction coil  116 . And, an output terminal of the filter  134   a  is connected to the processor  144 . The detection circuit  132   a  of the control loop  140  also includes a detector  136   a , and the detector  136   a  may be disposed (configured) on the first detection point (A), the second detection point (B), or the third detection point (C) of the inductive loop  110  for detecting current of the inductive loop  110 . As the processor  144  has an excellent processing performance, the filter  134  may be omitted. 
     In addition, a control line  142   a  of the processor  144  can be connected to a power source  122  of the power loop  120 , and the processor  144  is used for controlling output power of the power source  122 . Furthermore, the power loop  120  also includes a driving circuit  124   a , and the power source  122  is connected to an input terminal of the driving circuit  124   a . Two output terminals of the driving circuit  124   a  are connected to the capacitor  114  and the induction coil  116 , respectively. In addition, the control loop  140  may further include an auxiliary control line  142 , and the processor  144  is connected to control the driving circuit  124   a  via the auxiliary control line  142 , and thereby controlling phase or frequency of the driving circuit ( 124   a ), so as to control the power supply providing to the inductive loop  110 . 
     For various electric receiver devices  190 , the induced waveforms  320   a  may have great differences therebetween due to different properties of electromagnetic induction. For example, amplitude of the induced waveform  320   a  may be too large or too small so that it is outside of the detectable range. Meanwhile, the induced waveform  320   a  may be adjusted to the detectable range by controlling the phase or frequency of the driving circuit  124   a  by the processor  144 . 
       FIG. 2  illustrates a flow chart that the wireless charging system  100  of the invention detects the electric receiver device  190  and determines whether to increase the power supply for the electric receiver device  190  for charging or not. Please refer to  FIG. 2 , in step  202 , it activates the wireless charging system  100  of the invention. Then, in step  204 , the processor  144  notifies the detection circuit  132   a  to detect the inductive loop  110  to create the induced waveform  320   a  shown in  FIG. 3A . 
     In step  206 , it judges whether shape of the induced waveform  320   a  changes or not, to determine variation of the induced electric field. As the induced electric field changes, in step  208 , it determines whether a maximum peak value or an average peak value of the induced waveform  320   a  is over a pre-determined (set) value, or whether an area  322  of the induced waveform  320   a  is over an pre-determined (set) value of area, or whether variation of the frequency of the induction wave is over an pre-determined (set) value of frequency. For example,  FIG. 3C  shows a graph that a maximum peak of the induced waveform  320   c  of the induced electric field is over (greater than) a pre-determined peak value  310 , and  FIG. 3D  shows a graph that a maximum peak of the induced waveform  320   d  of the induced electric field is under (smaller than) a pre-determined peak value  310 . As it is over the pre-determined value, in step  210 , the processor  144  controls to increase output power of the power source  122  to the inductive loop  110 . Or, the processor  144  may control phase or frequency of the driving circuit  124   a  via the auxiliary control line  142   b  to increase output power of the power source  122  to the inductive loop  110 . 
     Finally, in step  212 , as the processor  144  determines the electric receiver device  190  is already fully charged, the power supply is then decreased or terminated, and then back to the step  204 , continuing to detect variation of the induced waveform  320   a  of the induced electric field. When the wireless charging system  100  of the invention is without the electric receiver device  190  approaching to, the step  204  can be performed per a period of time. 
     When the induced waveform  320   a  feedback from the detection circuit  132   a  with a noise signal does not meet the protocol specification so that it can not be used to determine whether the electric receiver device is approaching or not. As shown in  FIG. 4A , in another embodiment, the power loop  120  further includes an auxiliary detection point. For example, the auxiliary detection point locates on a non-ground circuit of a first auxiliary detection point (P) between the power source  122  and the driving circuit  124   a , or a ground circuit of a second auxiliary detection point (Q). Because possibility for the detection point of the inductive loop  120  and the auxiliary detection point of the power loop  120  with noise signals simultaneous is very low, it can improve the ability of determination for approach of an electrical receiver device by simultaneously detecting the detection point and the auxiliary detection point. 
     In other words, the control loop  140  of the wireless charging system  100  further includes an auxiliary detection circuit  132   b  connected to the power loop  120 , for example, connected to the first auxiliary detection point (P) of the power loop  120  to detect the induced electric field. A current or a voltage of the power loop  120  induced by the induced electric field represents an auxiliary induced waveform over time. Then, the processor  144  examines the induced waveform  320   a  by a protocol, for example comparing a waveform of the protocol specification with the induced waveform  320   a . As the processor  144  determines that the induced waveform  320   a  is not applicable, the induced waveform  320   a  may be replaced by the auxiliary induced waveform. 
     Similar with the detection circuit  132   a , the auxiliary detection circuit  132   b  further includes a filter  134   b , wherein an input terminal of the filter  134   b  is connected to the first auxiliary detection point (P) or the second auxiliary detection point (Q) of the power loop  120 . An output terminal of the filter  134   b  is connected to the processor  144 . Similarly, the auxiliary induced waveform may be filtered by the filter  134   b  for changing from a sawtooth waveform to a curve waveform. As the processor  144  has an excellent processing performance, the filter  134   b  may be omitted. 
     Similar with the detection circuit  132   a , the auxiliary detection circuit  132   b  of the control loop  140  also includes an auxiliary detector  136   b , and the auxiliary detector  136   b  may be disposed (configured) on the power loop  120 , at an auxiliary detection point between the power source  122  and the driving circuit  124   a , for example the first auxiliary detection point (P) or the second auxiliary detection point (Q), to detect current of the power loop  120 . 
     As shown in  FIG. 4A , a wireless charging system may include an inductive loop  110 , a power loop  120  and a control loop  140 . The inductive loop  110  comprises an induction coil  116  and a capacitor  114 , wherein the induction coil  116  and the capacitor  114  are connected in series. The power loop  120  includes a power source  122  and a driving circuit  124   a . The power source  122  is connected to an input terminal of the driving circuit  124   a , and two output terminals of the driving circuit  124   a  are connected to the capacitor  114  and the induction coil  116 . 
     The control loop  140  includes a processor  144 , a detection circuit  132   a , an auxiliary detection circuit  132   b , a control line  142   a , and an auxiliary control line  142   b . The detection circuit  132   a  is coupled to the processor  144  and connected to a detection point of the inductive loop  110 , for example a first detection point (A) between the driving circuit  124   a  and the capacitor  114 , or a second detection point (B) between the driving circuit  124   a  and the induction coil  116 , or a third detection point (C) between the capacitor  114  and the induction coil  116 , for the processor  144  to detect (process) an induced electric field of the inductive loop  110 . A first current or a first voltage of the inductive loop  110  induced by the induced electric field represents an induced waveform over time. 
     The auxiliary detection circuit  132   b  is connected to an auxiliary detection point of the power loop  120 , for example, connected to the first auxiliary detection point (P) or the second auxiliary detection point (P) to detect the induced electric field. A current or a voltage of the power loop  120  induced by the induced electric field represents an auxiliary induced waveform over time. As the processor  144  determines that the induced waveform is not applicable by a protocol, the induced waveform may be replaced by the auxiliary induced waveform. 
     The processor  144  is connected to the power source  122  by the control line  142   a  so that the processor  144  can control a power supply of the power source  122  outputted to the inductive loop  110 . The processor  144  is connected to the driving circuit  124   a  by the control line  142   b  so that the processor  144  can control a phase or a frequency of the driving circuit  124   a  to control the power supply of the inductive loop  110 . 
     Based on the detected induction electric field, the processor  144  determines whether the electric receiver device is in a condition to adjust the power supply of the power loop  120  outputted to the inductive loop  110 ; and the condition including a variation of the induced electric field due to approaching of the electric receiver device or power dissipation of the electric receiver device, etc. 
     Optionally, the detection circuit  132   a  includes a filter  134   a , and an input terminal of the filter  134   a  is connected to the inductive loop  110 . Also, an output terminal of the filter  134   a  is connected to the processor  144 . The auxiliary detection circuit  132   b  includes an auxiliary filter  134   b , and an input terminal of the auxiliary filter  134   b  is connected to the power loop  120 . Also, an output terminal of the auxiliary filter  134   b  is connected to the processor  144 . 
     Optionally, the filter  134   a  and the auxiliary filter  134   b  may be not directly connected to the processor  144 ; the filter  134   a  and the auxiliary filter  134   b  are connected to the processor  144  via a common circuit. An output terminal of the filter  134   a  and an output terminal of the auxiliary filter  134   b  are connected to an input terminal of the common circuit, and an output terminal of the common circuit is connected to the processor  144 . 
     Optionally, the detection circuit  132   a  includes a detector  136   a  configured in the inductive loop  110  and connected to the induction coil  116  and the capacitor  114  in series. The auxiliary detection circuit  132   b  includes a detector  136   b  configured in the power loop  110  and connected to the driving circuit  124   a  and the power source  122 . 
     The driving circuit is for example a full-bridge driver circuit  124   a  shown in  FIG. 4  A or a half-bridge driver circuit  124   b  shown in  FIG. 4  B. The half-bridge driver circuit  124   b  is used for adjusting the frequency, but not phase. 
       FIG. 5  is a schematic view of one example of a wireless charging system of the  FIG. 4A , wherein the detector is a voltage-type detector. As shown in  FIG. 5  and  FIG. 4A , the detector  136   a  is a voltage-type detector, wherein a signal input terminal  502  is connected to a first detection point (A), a second detection point (B) or a third detection point (C) of the inductive loop  110 , and wherein a signal output terminal  504  is connected to the filter  134   a  to detect voltage of the inductive loop  110 , and its voltage signal may be transmitted to the processor  144  via the detection circuit  132   a.    
     Optionally, the voltage-type detector may be used in the auxiliary detection circuit  132   b  to connect to the first auxiliary detection point (P) of the power loop  120 . The first detection point (A), the second detection point (B) or the third detection point (C) of the inductive loop  110 , or the first auxiliary detection point (P) of the power loop  120  may be connected by two voltage-type detectors at the same point, and subsequently connected to their respective filters to create different amplifications of voltage for providing the processor  144  to select preferable voltage signal. The two voltage-type detectors connected to their respective filters have a cost benefit than that of a single voltage-type detector connected to a single filter, because the whole cost of two filters with a lower modulation ratio reaching a higher modulation ratio of the single filter is less than that of the single filter. In other words, there are two detection lines, and each connected to the identical detection point, and each of connecting filter has a different modulation ratio to provide auxiliary induced waveform with different modulation ratio to the processor. 
       FIG. 6  is a schematic view of one example of a wireless charging system of the  FIG. 4A , wherein the detector is a single output current-type detector. As shown in  FIG. 6  and  FIG. 4A , the detector  136   b  is a single output current-type detector located at the first auxiliary detection point (P) or the second auxiliary detection point (Q) of the power loop  120 , wherein a first signal input terminal  602  is connected to the driving device  124   a , a second signal input terminal  606  is connected to the power source  122 , and a signal output terminal  604  is connected to the auxiliary filter  134   b  to detect current of the power loop  120 , and its current signal may be transmitted to the processor  144  via the auxiliary detection circuit  132   b.    
     Optionally, the single output current-type detector may be used in the detection circuit  132   a  located at a detection point of the induction loop  110 , for example first detection point (A), the second detection point (B) or the third detection point (C). The first detection point (A), the second detection point (B) or the third detection point (C) of the inductive loop  110 , or the first auxiliary detection point (P) and the second auxiliary detection point (Q) of the power loop  120  may be disposed by two single output current-type detectors at the same point, and subsequently connected to their respective filters to create different modulation ratios of current for providing the processor  144  to select preferable current signal. 
       FIG. 7  is a schematic view of one example of a wireless charging system of the  FIG. 4A , wherein the detector is a double output current-type detector. As shown in  FIG. 7  and  FIG. 4A , the detector  136   a  is a double output current-type detector located at a detection point of the induction loop  110 , for example first detection point (A), the second detection point (B) or the third detection point (C), wherein a first signal input terminal  702  of the detector  136   a  is connected to the capacitor  114 , a second signal input terminal  706  is connected to the driving device  124   a ; or the first signal input terminal  702  of the detector  136   a  is connected to the induction coil  116 , a second signal input terminal  706  is connected to the capacitor  114 ; and a first signal output terminal  704  and a second signal output terminal  708  are connected to the filter  134   a  to detect current of the induction loop  110 , and its differential current signal may be transmitted to the processor  144  via the detection circuit  132   a.    
     Optionally, the double output current-type detector may be used in the auxiliary detection circuit  132   b  located at the first auxiliary detection point (P) or the second auxiliary detection point (Q) of the power loop  120 . The first detection point (A), the second detection point (B) or the third detection point (C) of the inductive loop  110 , or the first auxiliary detection point (P) of the power loop  120  may be connected by two double output current-type detectors at the same point, and subsequently connected to their respective filters to create different amplifications of current for providing the processor  144  to select preferable current signal. 
       FIG. 8  is a flow chart of performing of the wireless charging system with a double detection lines. Please refer to the  FIG. 4B  and the  FIG. 8 , the processor  144  of the wireless charging system of the invention performs the following steps. Firstly, in step  802 , it starts a process of determining an induced waveform. Next, in step  804 , it simultaneously reads the induced waveform detected by the detection circuit  132   a  and the auxiliary induced waveform detected by the auxiliary detection circuit  132   b . Then, in step  806 , it examines to determine whether the induced waveform is correct or not by a protocol. If the answer is “yes” in the step  806 , then followed by step  810 , the induced waveform detected by the detection circuit  132   a  is applied and recording (stored) as “read successful” one, “read failure for the induced waveform” zero, “number of error” zero. If the answer is “no” in the step  806 , then followed by step  808 , it determines whether the auxiliary induced waveform is correct or not. If the answer is “yes” in the step  808 , then followed by step  812 , the auxiliary induced waveform detected by the auxiliary detection circuit  132   b  is applied and recording (stored) as “read successful” one, “read failure for the induced waveform” zero, “number of error” zero. If the answer is “no” in the step  808 , then followed by step  814 , it is recording (stored) as “read successful” zero, “read failure for the induced waveform” one, “number of error” plus one. After the steps  810 ,  812  and  814 , the process is terminated in step  816 . 
       FIG. 9  is a flow chart of performing of the wireless charging system with a double detection lines according to another embodiment. Please refer to the  FIG. 4B  and the  FIG. 9 , the processor  144  of the wireless charging system of the invention performs the following steps. Firstly, in step  902 , it starts a process of determining an induced waveform. Next, in step  904 , it simultaneously reads the induced waveform detected by the detection circuit  132   a  and the auxiliary induced waveform detected by the auxiliary detection circuit  132   b . Then, in step  906 , it examines to determine whether the first channel of the detection circuit  132   a  is applied to connect or not. If the answer is “yes” in the step  906 , then followed by step  908 , it determines whether the induced waveform is correct or not. If the answer is “yes” in the step  908 , then followed by step  912 , the induced waveform detected by the detection circuit  132   a  is applied and recording (stored) as “read successful” one, “read failure for the induced waveform” zero, “number of error” zero. If the answer is “no” in the step  908 , then followed by step  914 , a second channel of the auxiliary detection circuit  132   b  is then applied. 
     If the answer is “no” in the step  906 , then followed by step  910 , it determines whether the auxiliary induced waveform is correct or not. If the answer is “yes” in the step  910 , then followed by step  918 , the auxiliary induced waveform detected by the auxiliary detection circuit  132   b  is applied and recording (stored) as “read successful” one, “read failure for the induced waveform” zero, “number of error” zero. If the answer is “no” in the step  910 , then followed by step  916 , the first channel of the detection circuit  132   a  is then applied. 
     After changing the channel in the steps  914  and  916 , it proceeds to step  920  recording (storing) as “read successful” zero, “read failure for the induced waveform” one, “number of error” plus one. After the steps  912 ,  918  and  920 , the process is terminated in step  922 . 
       FIG. 10  is a flow chart of performing of the wireless charging system with a double detection lines according to yet another embodiment. Please refer to the  FIG. 4B  and the  FIG. 10 , the processor  144  of the wireless charging system of the invention performs the following steps. Firstly, in step  1002 , it starts a process of determining an induced waveform. Next, in step  1004 , it examines to determine whether the first channel of the detection circuit  132   a  is applied to connect or not. If the answer is “yes” in the step  1004 , then followed by step  1005 , it reads an induced waveform detected by the detection circuit  132   a . Next, in step  1008 , it determines whether the induced waveform is correct or not. If the answer is “yes” in the step  1008 , then followed by step  1012 , the induced waveform detected by the detection circuit  132   a  is applied and recording (stored) as “read successful” one, “read failure for the induced waveform” zero, “number of error” zero. If the answer is “no” in the step  1008 , then followed by step  1014 , a second channel of the auxiliary detection circuit  132   b  is then applied. 
     If the answer is “no” in the step  1004 , then followed by step  1006 , it reads an auxiliary induced waveform detected by the auxiliary detection circuit  132   b . Next, in step  1010 , it determines whether the auxiliary induced waveform is correct or not. If the answer is “yes” in the step  1010 , then followed by step  1018 , the auxiliary induced waveform detected by the auxiliary detection circuit  132   b  is applied and recording (stored) as “read successful” one, “read failure for the induced waveform” zero, “number of error” zero. If the answer is “no” in the step  1010 , then followed by step  1016 , the first channel of the detection circuit  132   a  is then applied. 
     After changing the channel in the steps  1014  and  1016 , it proceeds to step  1020  recording (storing) as “read successful” zero, “read failure for the induced waveform” one, “number of error” plus one. After the steps  1012 ,  1018  and  1020 , the process is terminated in step  1022 . 
     It will be understood that the above descriptions of embodiments are given by way of example only and that various modifications may be made by those with ordinary skill in the art. The above specification, examples and data provide a complete description of the structure and use of exemplary embodiments of the invention. Although various embodiments of the invention have been described above with a certain degree of particularity, or with reference to one or more individual embodiments, those with ordinary skill in the art could make numerous alterations to the disclosed embodiments without departing from the spirit or scope of this invention.