PATENT ABSTRACT
The present disclosure illustrates a bidirectional wireless charging device. The bidirectional wireless charging device comprises a transceiver chip which is configured to receive a switch signal. The transceiver chip comprises a power stage circuit and a control module. The power stage circuit is coupled to a coil, and the control module is coupled to the power stage circuit. The power stage circuit is configured to output a voltage to the coil, or to receive an induced voltage from the coil. The control module is configured to control the transceiver chip to enter a power mode or a charging mode based upon the switch signal. When the transceiver chip enters the power mode, the transceiver chip provides the voltage to the coil. When the transceiver chip enters the charging mode, the transceiver chip receives the induced voltage from the coil and charges a power storage unit.

PATENT DESCRIPTION
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The instant disclosure relates to a bidirectional wireless charging device; in particular, to a bidirectional wireless charging device with an integrated transceiver chip. 
     2. Description of Related Art 
     With the technology well developed, there are many kinds of personal mobile devices and wearable devices which connect with the Internet, provide people a so-called mobile life, and thus increase the convenience in our daily lives. However, the requirement of electric power for using these electric products also gradually increases. For solving this problem, there is a wireless charging device developed currently. The wireless charging device can be generally categorized as two kinds, wherein one is the wireless charging device using the Electromagnetic Induction Technology and another is the wireless charging device using the Electromagnetic Resonance Technology. Particularly, the wireless charging device using the Electromagnetic Induction Technology is more common. The advantage of the wireless charging device is that the electric device and the wireless charging device do not need wires to have a connection. 
     In the prior art, one wireless charging device merely has a signal direction wireless charging function. For example, the wireless charging device as a powering end can merely provide electric power, and the wireless charging device as a charging end can merely receive electric power. Generally, there is not the wireless charging device which can provide electric power outdoors, which means that the user&#39;s portable electric device may not be used anywhere anytime. For example, when the power of the wireless charging device runs out and the wearable device, such as a smart watch, has an urgent request for charging, if there was an electric device having sufficient power which could charge the smart watch, the above problem could be solved. 
     Therefore, in the prior art, there has been a kind of bidirectional wireless charging device developed. The bidirectional wireless charging device has a power providing function and a power receiving function. Thus, the bidirectional wireless charging device can be a powering end or a charging end under different circumstances. 
     However, the traditional bidirectional wireless charging device must have an emitter chip and its corresponding circuit (such as a control circuit, a modulation circuit, a power stage circuit and the like), and have a transceiver chip and its corresponding circuit (such as a control circuit, a modulation circuit, a power stage circuit, a rectifying circuit and the like). In other words, to realize the bidirectional wireless charging function, the area of inner circuit of the bidirectional wireless charging and the cost dramatically increase. 
     SUMMARY OF THE INVENTION 
     The instant disclosure provides a bidirectional wireless charging device. The bidirectional wireless charging device comprises a transceiver chip receiving a switch signal. The transceiver chip comprises a power stage circuit and a control module. The power stage circuit is electrically connected to a coil, and outputs a voltage to the coil or receives an induced voltage from the coil. The control module is electrically connected to the power stage circuit, and correspondingly makes the transceiver chip turn into a power mode or a charging mode according to the switch signal. The transceiver chip provides the voltage to the coil when the switch signal indicates that the transceiver chip turns into the power mode. The transceiver chip receives the induced voltage from the coil and charges a power storage unit of the bidirectional wireless charging device, when the switch signal indicates that the transceiver chip turns into the charging mode. 
     The instant disclosure further provides a bidirectional wireless charging system. The bidirectional wireless charging system comprises at least two bidirectional wireless charging devices. Each bidirectional wireless charging device comprises a transceiver chip receiving a switch signal. The transceiver chip comprises a first bidirectional wireless charging device and a second bidirectional wireless charging device. The first bidirectional wireless charging device and the second bidirectional wireless charging device respectively comprise a power stage circuit and a control module. The power stage circuit is electrically connected to a coil, and outputs a voltage to the coil or receives an induced voltage from the coil. The control module is electrically connected to the power stage circuit, and correspondingly makes the transceiver chip turn into a power mode or a charging mode according to the switch signal. The first bidirectional wireless charging device and the second bidirectional wireless charging device are either a charging end and a powering end according to the switch signal. When the first bidirectional wireless charging device is the powering end, the transceiver chip of the first bidirectional wireless charging device turns into the power mode and provides the voltage to the coil so as to make the first bidirectional wireless charging device provide a pulse width modulated signal to the second bidirectional wireless charging device. The pulse width modulated signal includes an electromagnetic energy. When the second bidirectional wireless charging device is the charging end, the transceiver chip of the second bidirectional wireless charging device turns into the charging mode, receives the induced voltage from the coil, and charges a power storage unit of the second bidirectional wireless charging device. 
     To sum up, the bidirectional wireless charging device provided by the instant disclosure can used as a powering end or a charging end to improve the convenience of the bidirectional wireless charging device. Moreover, compared with the traditional bidirectional wireless charging device, the transceiver chip of the bidirectional wireless charging device provided by the instant disclosure integrates the power mode operation module and the charging mode operation module into a single chip. Thereby, merely one control module and one power stage circuit are needed for the instant disclosure to provide the bidirectional wireless charging function, which effectively shrinks the circuit area, decreases the cost and also reduces the system complexity. 
     For further understanding of the instant disclosure, reference is made to the following detailed description illustrating the embodiments and examples of the instant disclosure. The description is only for illustrating the instant disclosure, not for limiting the scope of the claim. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings, in which like references indicate similar elements and in which: 
         FIG. 1  shows a schematic diagram of a bidirectional wireless charging system of one embodiment of the instant disclosure; 
         FIG. 2  shows a block diagram of a bidirectional wireless charging device of one embodiment of the instant disclosure; 
         FIG. 3A  a schematic diagram of a bidirectional wireless charging device of one embodiment of the instant disclosure; 
         FIG. 3B  a schematic diagram of a bidirectional wireless charging device of another embodiment of the instant disclosure; 
         FIG. 4  shows a schematic diagram of a bidirectional wireless charging device of one embodiment of the instant disclosure in the power mode; 
         FIG. 5  shows a schematic diagram of a bidirectional wireless charging device of one embodiment of the instant disclosure in the charging mode; 
         FIG. 6  shows a flow chart of a bidirectional wireless charging device of one embodiment of the instant disclosure in the power mode; and 
         FIG. 7  shows a flow chart of a bidirectional wireless charging device of one embodiment of the instant disclosure in the charging mode. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The aforementioned illustrations and following detailed descriptions are exemplary for the purpose of further explaining the scope of the instant disclosure. Other objectives and advantages related to the instant disclosure will be illustrated in the subsequent descriptions and appended drawings. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity. 
     It will be understood that, although the terms first, second, third, and the like, may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only to distinguish one element, component, region, layer or section from another region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the instant disclosure. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     Please refer to  FIG. 1 ,  FIG. 1  shows a schematic diagram of a bidirectional wireless charging system of one embodiment of the instant disclosure. The bidirectional wireless charging system comprises at least two bidirectional wireless charging devices. In this embodiment, the bidirectional wireless charging system comprises a first bidirectional wireless charging device  1 A, a second bidirectional wireless charging device  1 B and a third bidirectional wireless charging device  1 C. It is to be noted that  FIG. 1  is merely used to describe the bidirectional wireless charging system of one embodiment of the instant disclosure but does not limit the instant disclosure. In other embodiments, the bidirectional wireless charging system can merely comprise two bidirectional wireless charging devices or comprise more than two bidirectional wireless charging devices. 
     The first bidirectional wireless charging device  1 A, the second bidirectional wireless charging device  1 B and the third bidirectional wireless charging device  1 C can be a mobile phone, a tablet computer, a laptop, a wireless charger, a smart watch, a set-top box or other electric products having a wireless charging function. For an easy instruction and understanding of the instant disclosure, in the following description, the first bidirectional wireless charging device  1 A may be a mobile phone, the second bidirectional wireless charging device  1 B may be a wireless charger and the third bidirectional wireless charging device  1 C may be a smart watch. In addition, the first bidirectional wireless charging device  1 A, the second bidirectional wireless charging device  1 B and the third bidirectional wireless charging device  1 C are operated according to the Electromagnetic Induction Technology. However, it is not limited herein. The first bidirectional wireless charging device  1 A, the second bidirectional wireless charging device  1 B and the third bidirectional wireless charging device  1 C can also be operated according to the Electromagnetic Resonance Technology. 
     The second bidirectional wireless charging device  1 B may often be provided with commercial power and thus maintain sufficient power. When the first bidirectional wireless charging device  1 A has insufficient power, the user can operate the first bidirectional wireless charging device  1 A to send a switch signal to the second bidirectional wireless charging device  1 B. For example, the switch signal is an analogue signal indicating that the bidirectional wireless charging device turns into a power mode or a charging mode. For instance, the bidirectional wireless charging device receiving a high-level switch signal would turn into the power mode, and he bidirectional wireless charging device receiving a low-level switch signal would turn into the charging mode. After receiving the high-level switch signal, the second bidirectional wireless charging device  1 B turns into the power mode and starts to charge the first bidirectional wireless charging device  1 A. 
     In another case, when the stored power of the first bidirectional wireless charging device  1 A is insufficient to drive the first bidirectional wireless charging device  1 A, the user can also operate the second bidirectional wireless charging device  1 B to send a low-level switch signal to the first bidirectional wireless charging device  1 A. The switch signal has energy, so the first bidirectional wireless charging device  1 A can be turned on by the energy of the switch signal. After that, the first bidirectional wireless charging device  1 A would reply the second bidirectional wireless charging device  1 B with a high-level switch signal. After receiving the high-level switch signal, the second bidirectional wireless charging device  1 B starts to charge the first bidirectional wireless charging device  1 A. 
     When the stored power of the first bidirectional wireless charging device  1 A reaches a predetermined value (such as 90% of the maximum stored power of the first bidirectional wireless charging device  1 A), the first bidirectional wireless charging device  1 A sends a status signal to the second bidirectional wireless charging device  1 B, so that the second bidirectional wireless charging device  1 B ends the power mode and thus stops charging the first bidirectional wireless charging device  1 A. 
     Sometimes the user may bring the first bidirectional wireless charging device  1 A, the second bidirectional wireless charging device  1 B and the third bidirectional wireless charging device  1 C outside, and in this case the second bidirectional wireless charging device  1 B can&#39;t be provided with commercial power and can&#39;t maintain sufficient power. When the second bidirectional wireless charging device  1 B has insufficient power, the second bidirectional wireless charging device  1 B can&#39;t charge the third bidirectional wireless charging device  1 C. There may be a more urgent demand for using the third bidirectional wireless charging device  1 C, so the user would try not to run out the power of the third bidirectional wireless charging device  1 C. At this moment, the user can operate the third bidirectional wireless charging device  1 C to send a switch signal to the first bidirectional wireless charging device  1 A, so that the first bidirectional wireless charging device  1 A would turn into the power mode and start to charge the third bidirectional wireless charging device  1 C. 
     In other words, the first bidirectional wireless charging device  1 A, the second bidirectional wireless charging device  1 B and the third bidirectional wireless charging device  1 C provided in this embodiment can be used as a charging end or a powering end, so as to increase the convenience of the bidirectional wireless charging system. 
     In addition, the switch signal can be a Pulse Width Modulation signal (PWM signal) sent by a coil; however, it is not limited herein. For example, in other embodiments, the bidirectional wireless charging device  1  can send a switch signal wirelessly via a wireless transmission unit (not shown in  FIG. 1 ). 
     There is further instruction for a structure of the bidirectional wireless charging device in the following description. Please refer to  FIG. 2 ,  FIG. 2  shows a block diagram of a bidirectional wireless charging device of one embodiment of the instant disclosure. The bidirectional wireless charging device  1  can be one of the above mentioned first bidirectional wireless charging device, second bidirectional wireless charging device  1 B and third bidirectional wireless charging device  1 C. For a need to instruct easily, they are described as the bidirectional wireless charging device  1  in the following description. 
     The bidirectional wireless charging device  1  comprises a transceiver chip  10 , a coil  11 , a power processing unit  12  and a power storage unit  13 . The coil  11  is electrically connected to the transceiver chip  10 . The transceiver chip is electrically connected to the power processing unit  12  and the power storage unit  13 . The power processing unit  12  is electrically connected to the power storage unit  13 . 
     The coil  11  can be a cable coil or other inductor that can generate an induced voltage corresponding to a variable electromagnetic field. When the bidirectional wireless charging device  1  is used as a powering end, the coil  11  can convert the voltage into a PWM signal and send the PWM signal out. The PWM signal includes an electromagnetic energy, so a charging end can charge with the received electromagnetic energy. When the bidirectional wireless charging device is used as a charging end, the coil  11  can sense the PWM signal and convert the electromagnetic energy of the PWM signal into an induced voltage. 
     The transceiver chip  10  receives the switch signal and correspondingly controls and makes the bidirectional wireless charging device  1  turn into the power mode or the charging mode. Moreover, when the bidirectional wireless charging device  1  is used as a powering end, the transceiver chip  10  receives the voltage from the power processing unit  12  and the power storage unit  13 , and provides the voltage to the coil  11  so that the coil  11  generates a PWM signal. When the bidirectional wireless charging device  1  is used as a charging end, the transceiver chip  10  receives an induced voltage generated by the coil  11 , and rectifies and regulates the induced voltage to generate a regulated voltage. 
     The power processing unit  12  manages the stored power of the bidirectional wireless charging device  1 . For example, the power processing unit  12  determines when to transmit the regulated voltage outputted by the transceiver chip  10  to the power storage unit  13 , or makes the power storage unit  13  provide power to the transceiver chip  11 . 
     The power storage unit  13  is used to store power, for example, the battery of the bidirectional wireless charging device  1  or other power storage devices, such as a capacitor. 
     For further instruction, please refer to  FIG. 3A .  FIG. 3A  is a schematic diagram of a bidirectional wireless charging device of one embodiment of the instant disclosure. As described in the above embodiment, the bidirectional wireless charging device  1  comprises a transceiver chip  10 , a coil  11 , a power processing unit  12  and a power storage unit  13 . The relationship of connection between the transceiver chip  10 , the coil  11 , the power processing unit  12  and the power storage unit  13  for this embodiment can be referred to the description in the previous embodiment, and thus the redundant information is not repeated. The following description is merely for the difference between this embodiment and the previous embodiment. 
     The transceiver chip  10  further comprises a control module  101 , a power stage circuit  102 , a charging mode operation module  104  and a power mode operation module  103 . The control module  101  is electrically connected to the power stage circuit  102 . The power stage circuit  102  is electrically connected to the coil  11 . The charging mode operation module  104  is electrically connected to the control module  101  and the coil  11 . The power mode operation module  103  is electrically connected to the control module  101  and the coil  11 . 
     In conjunction with  FIG. 3 a    and  FIG. 3B ,  FIG. 3B  is a schematic diagram of a bidirectional wireless charging device of another embodiment of the instant disclosure. The transceiver chip  10  of the bidirectional wireless charging device  1  also comprises a control module  101 , a power stage circuit  102 , a charging mode operation module  104  and a power mode operation module  103 . The following is further instruction about the structure and function of the transceiver chip  10 . 
     The control module  101  comprises a control unit  1010 . The control unit  1010  is electrically connected to the power stage circuit  102 . The control unit  1010  controls and adjusts the voltage output by the power stage circuit  102 . 
     The power stage circuit  102  comprises a power switch, a pulse width modulation circuit, an isolated high-frequency transformer, a rectifying circuit and an output filter (not shown in  FIG. 3B ). The rectifying circuit can be, for example, a half-bridge rectifying circuit or a full-bridge rectifying circuit, to generate a rectified voltage. 
     When the bidirectional wireless charging device  1  is used as a power end, the power stage circuit  102  drives the power switch and provides a voltage to the coil  11 , so that the coil  11  is driven to have a resonance and output a PWM signal. When the bidirectional wireless charging device  1  is used as a charging end, the power stage circuit  102  receives an induced voltage from the coil  11  and generates a rectified voltage. The detailed structure and the working mechanism of the power stage circuit  102  would be able to be comprehended by one skilled in the art and further descriptions are therefore omitted. 
     The power mode operation module  103  comprises a demodulation unit  1030  electrically connected to the control unit  1010  and the coil  11 . The demodulation unit  1030  receives a PWM signal PWM′ output by another bidirectional wireless charging device which is used as a charging end via the coil  11 , and demodulates the received PWM signal PWM′. The PWM signal PWM′ includes a status message sent from the charging end. In detail, the status message comprises a quantity of the charging end (for example, the currently stored electric quantity of the charging end), an energy adjusting request, an energy maintaining request, a cut-off supply request or the like. The demodulation unit  1030  filters the high-frequency band out from PWM signal PWM′, maintains the amplitude, and uses the amplitude size as a status message sent by the charging end. After that, the demodulation unit  1030  outputs the demodulated status message to the control unit  1010 , so that the control unit  1010  correspondingly controls the voltage output by the power stage circuit  102  according to the demodulated status message. 
     For example, when the status message includes an energy adjusting request, the control unit  1010  would correspondingly adjust the voltage output by the power stage circuit  102  according to the currently stored power of the charging end. When the status message includes an energy maintaining request, the control unit  1010  would make the power stage circuit  102  maintain the provided voltage. 
     The charging mode operation module  104  comprises a voltage regulating unit  1040  and a modulation unit  1041 . The voltage regulating unit  1040  is electrically connected to the control unit  1010 , the power stage circuit  102  and the power processing unit  12 . The modulation unit  1041  is electrically connected to the control unit  1010  and the coil  11 . The voltage regulating unit  1040  receives the rectified voltage output by the power stage circuit  102 , regulates the rectified voltage and outputs the regulated voltage to charge the power storage unit  13  of the bidirectional wireless charging device  1 . The modulation unit  1041  is controlled by the control unit  1010 . The control unit  1010  controls and makes the modulation unit  1041  generate a PWM signal including a status message according to the regulated voltage value and the power currently stored in the bidirectional wireless charging device. 
     Please refer to  FIG. 4 .  FIG. 4  shows a schematic diagram of a bidirectional wireless charging device of one embodiment of the instant disclosure in the power mode. When another bidirectional wireless charging device  1 ′ (not shown in  FIG. 4 , such as the wireless charging device  1 ′ in  FIG. 5 ) has insufficient power (for example, the left power of the bidirectional wireless charging device  1 ′ is less than 20% of the maximum stored power but more than the minimum stored power), the user can operate the bidirectional wireless charging device  1 ′ to send a switch signal, such as a high-level switch signal. After receiving the switch signal, the bidirectional wireless charging device  1  turns into the power mode and becomes a powering end to start to provide power to the bidirectional wireless charging device V. In addition, in this embodiment, the high-level switch signal corresponds to the power mode but it is not limited herein. That is, in other embodiments, the low-level switch signal can also be set to correspond to the power mode. 
     Further, when the switching unit (not shown in  FIG. 4 ) of the control module  101  receives the high-level switch signal, the switching unit makes the circuit path corresponding to the power mode operation module  103  turn on (shown as the circuit path connected by the real line in  FIG. 4 ), and makes the circuit path corresponding to the charging mode operation module  103  turn off (shown as the circuit path connected by the dash line in  FIG. 4 .). The switching unit may be, for example, a multiplexer or a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) switch, so as to switch the corresponding circuit path according to the switch signal. 
     After the bidirectional wireless charging device  1  turns into the power mode, the power processing unit  12  controls the power storage unit  13  to provide power to the power stage circuit  102 . After that, the control unit  1010  of the control module  101  controls the power stage circuit  102  to output a voltage to the coil  11  so as to drive the coil to have the resonance and to output a PWM signal having the electromagnetic energy. As the charging end, the coil  11  of the bidirectional wireless charging device  1 ′ generates an induced voltage via the electromagnetic induction and start to charge. 
     When the stored power of the bidirectional wireless charging device  1 ′ reaches a predetermined value, the bidirectional wireless charging device  1 ′ would output a PWM signal including a cut-off supply request. After the demodulation unit  1030  of the power mode operation module  103  of the bidirectional wireless charging device  1  receives a PWM signal PWM′ via the coil  11 , it would demodulate the PWM signal PWM′ and output a demodulated status message. The control unit  1010  receives the status message and correspondingly controls the output power of the power stage circuit  102  according to the status message. For example, when the bidirectional wireless charging device  1  receives the status message indicating that the stored power of the bidirectional wireless charging device  1 ′ reaches a predetermined value (such as 90% of the maximum stored power of the bidirectional wireless charging device  1 ′, but it is not limited herein), the control unit  1010  of the bidirectional wireless charging device  1  makes the power stage circuit  102  stop charging the bidirectional wireless charging device  1 ′. 
     Please refer to  FIG. 5 .  FIG. 5  shows a schematic diagram of a bidirectional wireless charging device of one embodiment of the instant disclosure in the charging mode. Different from the embodiment shown in  FIG. 4 , the bidirectional wireless charging device  1 ′ shown in  FIG. 5  is used as the charging end. In addition, the bidirectional wireless charging device  1  shown in  FIG. 4  and the bidirectional wireless charging device  1 ′ shown in  FIG. 5  have the same structure but different operation modes. 
     Further, when the user tends to charge the bidirectional wireless charging device  1 ′, the user can make the bidirectional wireless charging device  1 ′ turn into the charging mode. At this moment, the switching signal generating unit (not shown in  FIG. 5 ) of the bidirectional wireless charging device  1 ′ would generate a high-level switch signal and a low-level switch signal. The high-level switch signal is sent to the bidirectional wireless charging device  1  (not shown in  FIG. 5 , such as the wireless charging device  1 ), so that the bidirectional wireless charging device  1  turns into the power mode. The low-level switch signal is sent to the control module  101 ′ of the bidirectional wireless charging device  1 ′, so that the bidirectional wireless charging device  1 ′ turns into the power mode. 
     After the switching unit (not shown in  FIG. 5 ) of the control module  101 ′ receives the switch signal, the switching unit makes the circuit corresponding to the charging mode operation module  104 ′ turn on (shown as the circuit path connected by the real line in  FIG. 5 ), but makes the circuit corresponding to the powering mode operation module  103 ′ turn off (shown as the circuit path connected by the dotted line in  FIG. 5 ). As mentioned above, the switching unit, such as a multiplexer or a MOSFET switch, is configured to correspondingly switch the circuit paths according to the switch signal. 
     The coil  11 ′ receives the PWM signal from the bidirectional wireless charging device  1 , and converts the electromagnetic energy of the PWM signal into an induced voltage. The power stage circuit receives and rectifies the induced voltage, and outputs a rectified voltage. 
     The voltage regulating unit  1040 ′ of the charging mode operation module  104 ′ receives and regulates the rectified voltage, and generates a regulated voltage. After that, the voltage regulating unit  1040 ′ outputs the regulated voltage to the control unit  1010 ′, so as to provide power for the operation of the bidirectional wireless charging device V. Moreover, the voltage regulating unit  1040 ′ outputs the regulated voltage to the power processing unit  12 ′, and the power processing unit  12 ′ uses the regulated voltage to charge the power storage unit  13 ′. 
     After receiving the regulated voltage, the control unit  1010 ′ makes the modulation unit  1041 ′ change the voltage amplitude of the coil  11  according to the regulated voltage value and the currently stored power of the bidirectional wireless charging device  1 ′, so that the coil  11 ′ generates a PWM signal PWM′ including a status message for informing the powering end about the current electric quantity of the bidirectional wireless charging device  1 ′, an energy adjusting request, an energy maintaining request or a cut-off supply request. 
     The steps for the bidirectional wireless charging device  1 ′ to generate a PWM signal PWM′ are as follows. After receiving the regulated voltage, the control unit  1010 ′ determines whether the power provided from the power storage unit  13 ′ to the bidirectional wireless charging device  1 ′ is within a normal range. If the power provided by the power storage unit  13 ′ is not within the normal range, it means that the power currently stored in the power storage unit is insufficient to support and maintain the operation of the bidirectional wireless charging device V. At this moment, the control unit  1010 ′ makes the modulation unit  1041 ′ change the voltage amplitude of the coil  11 ′, so as to generate a PWM signal PWM′ including an energy adjusting request or an energy maintaining request. If the power provided by the power storage unit  13 ′ is within the normal range, the control unit  1010 ′ further detects whether the power stored in the power storage unit  13 ′ reaches a predetermined value. When the control unit  1010 ′ determines that the power stored in the power storage unit  13 ′ reaches the predetermined value, the control unit  1010 ′ makes the modulation unit  1041 ′ generate a PWM signal PWM′ including a cut-off supply signal. 
     For example, when the power provided by the power storage unit  13 ′ is not within the normal range, the control unit  1010 ′ makes the modulation unit  1041 ′ generate a PWM signal PWM′ including an energy adjusting request, so as to request the powering end to provide a PWM signal PWM having more energy. 
     When the power provided by the power storage unit  13 ′ is within the normal range and the power stored in the power storage unit  13 ′ has not reached the predetermined value (such as 90% of the maximum stored power of the bidirectional wireless charging device  1 ′), the control unit  1010 ′ makes the modulation unit  1041 ′ generate a PWM signal PWM′ including an energy adjusting request, so as to request the powering end to output a PWM signal PWM having more energy. In another case, the control unit  1010 ′ can also makes the modulation unit  1041 ′ generate a PWM signal PWM′ including an energy maintaining request, so as to make the powering end keep outputting the current PWM signal PWM. 
     When the power provided by the power storage unit  13 ′ is within the normal range and the control unit  1010 ′ determines that the power stored in the power storage unit  13 ′ reaches the predetermined value, the control unit  1010 ′ makes the modulation unit  1041 ′ generate a PWM signal PWM′ including a cut-off supply signal, so as to make the powering end stop charging the bidirectional wireless charging device  1 ′. 
     In addition, the above embodiment is an example for describing the application of the instant disclosure, but it is not limited herein. The user can set the normal range of power provided by the power storage unit  13 ′ and set the predetermined value of power stored in the power storage unit  13 ′ based on need. 
     In other embodiments, the control unit  1010 ′ is also configured to make the modulation unit  1041 ′ generate a PWM signal PWM including a status message once every time interval, so as to inform the powering end of the current electric quantity of the bidirectional wireless charging device  1 ′, an energy adjusting request, or an energy maintaining request. Thereby, the powering end can dynamically adjust the electromagnetic energy provided to the bidirectional wireless charging device  1 ′. 
     For instance, when the status message output by the bidirectional wireless charging device  1 ′ indicates that the currently stored power of the bidirectional wireless charging device  1 ′ is less than 70% of the maximum stored power, the powering end would output a PWM signal PWM with more energy. When the status message output by the bidirectional wireless charging device  1 ′ indicates that the currently stored power of the bidirectional wireless charging device  1 ′ is about 70%-90% of the maximum stored power, the powering end would output a PWM signal PWM with less energy. When the status message output by the bidirectional wireless charging device  1 ′ indicates that the currently stored power of the bidirectional wireless charging device  1 ′ is more than 90% of the maximum stored power, the powering end would stop charging the bidirectional wireless charging device  1 ′. In addition, the above embodiment is an example for describing the application of the instant disclosure, but it is not limited herein. The user can set how the bidirectional wireless charging device  1  and bidirectional wireless charging device  1 ′ dynamically adjust the electromagnetic energy based on needs. 
     In this embodiment, the transceiver chip  10  of the bidirectional wireless charging device  1  merely comprises one power mode operation module  103  and one charging mode operation module  104 . In other embodiments, the transceiver chip  10  can also comprise a plurality of coils  11 , a plurality of power mode operation modules  103  and a plurality of charging mode operation modules  104 . The power mode operation modules  103  are electrically connected to the control module  101  and the corresponding coil  11  respectively, and the charging mode operation modules  104  are electrically connected to the control module  101 , the corresponding coils and the power stage circuit  102  respectively. Thereby, the bidirectional wireless charging device  1  can receive the electromagnetic energy from many powering ends at the same time or can provide the electromagnetic energy to many charging ends at the same time, which makes the bidirectional wireless charging device  1  have multiple bidirectional wireless charging functions. 
     It is worth mentioning that, in the above embodiment, the user needs to manually operate the bidirectional wireless charging device  1  to generate a switch signal and start the charging process. However, in other embodiments, the two bidirectional wireless charging devices  1  and  1 ′ in the bidirectional wireless charging system can automatically start the charging process. 
     In detail, in other embodiments, the user can set the bidirectional wireless charging devices  1  and  1 ′ to turn on the automatic charging function. When the distance between the bidirectional wireless charging devices  1  and  1 ′ is less than a preset distance, the bidirectional wireless charging devices  1  and  1 ′ would exchange their status messages to inform each other of the current electric quantity. When the current electric quantity of the bidirectional wireless charging device  1  is more than a first threshold value and the current electric quantity of the bidirectional wireless charging device  1 ′ is less than a second threshold value, the bidirectional wireless charging device  1  would start to charge the bidirectional wireless charging device  1 ′. 
     For example, when the current electric quantity of the bidirectional wireless charging device  1 ′ is less than 20% of the maximum stored power and the current electric quantity of the bidirectional wireless charging device  1  is more than 80% of the maximum stored power, the bidirectional wireless charging device  1  would automatically charge the bidirectional wireless charging device V. In addition, the above embodiment is merely an example for describing the application of the instant disclosure, but it is not limited herein. The skilled in the art can set the predetermined distance, a first threshold value and second threshold value based on the actual operation and needs. Moreover, the user can also choose to turn off the automatic charging function of the bidirectional wireless charging devices  1  and  1 ′, and thus in the instant disclosure the bidirectional wireless charging devices  1  and  1 ′ can optionally turn on their automatic charging function. 
     On the other hand, in other embodiments, the bidirectional wireless charging system can be set such that the bidirectional wireless charging device  1  periodically sends a switch signal to another bidirectional wireless charging device. When the bidirectional wireless charging device  1 ′ receives the switch signal and the bidirectional wireless charging device  1 ′ has insufficient power, the bidirectional wireless charging device  1 ′ would reply to this switch signal. After receiving the reply of the bidirectional wireless charging device  1 ′, the bidirectional wireless charging device  1  would turn into the power mode and start to charge the bidirectional wireless charging device  1 ′. 
     In short, the bidirectional wireless charging device provided in the embodiment of the instant disclosure can be used as a powering end or a charging end, so as to increase the convenience of the bidirectional wireless charging system. Moreover, the transceiver chip  10  of the bidirectional wireless charging device provided in the embodiment of the instant disclosure integrates the power mode operation module  103  and the charging mode operation module  104  into a single chip. Thereby, the bidirectional wireless charging device  1  merely needs one control module  101  and one power stage circuit  102  to realize the bidirectional wireless charging function. 
     Please refer to  FIG. 6 ,  FIG. 6  shows a flow chart of a bidirectional wireless charging device of one embodiment of the instant disclosure in the power mode. The steps of process shown in  FIG. 6  are applied to the above bidirectional wireless charging devices  1  and  1 ′. The Step S 601  is starting the powering process. The Step S 602  is making the bidirectional wireless charging device  1  turn into the power mode. The switch signal can be sent from the switch signal generating unit of the bidirectional wireless charging device  1  or from the switch signal generating unit of another bidirectional wireless charging device (such as the bidirectional wireless charging device  1 ′). The Step S 603  is that the bidirectional wireless charging device  1  starts to output the electromagnetic energy to the bidirectional wireless charging device  1 ′. 
     The Step S 604  is that the bidirectional wireless charging device  1  receives and demodulates a PWM signal PWM′ sent by the bidirectional wireless charging device  1 ′, so as to obtain a status message of the bidirectional wireless charging device  1 ′, which includes an electric quantity in formation of the charging end, an energy adjusting request, an energy maintaining request or a cut-off supply request. The Step S 605  is that the bidirectional wireless charging device  1  determines whether the status message includes a cut-off supply message. If the status message includes a cut-off supply message, it goes to the Step S 606 , and if the status message does not include a cut-off supply message, it goes to the Step S 607 . The Step S 606  is that the bidirectional wireless charging device  1  adjusts the power output by the power stage circuit according to the status message and that it returns to the Step S 603  so as to continue to charge the bidirectional wireless charging device V. The steps for the bidirectional wireless charging device  1  adjusting the power output by the power stage circuit are the same as the above embodiment, and thus the redundant information is not repeated. The Step S 606  is that the bidirectional wireless charging device  1  stops outputting the electromagnetic energy, and the Step S 607  is ending the powering process. 
     Please refer to  FIG. 7 ,  FIG. 7  shows a flow chart of a bidirectional wireless charging device of one embodiment of the instant disclosure in the charging mode. The steps of the process shown in  FIG. 7  are also applied to the above bidirectional wireless charging devices  1  and  1 ′. The Step S 701  is starting the charging process. The Step S 702  is that the bidirectional wireless charging device  1 ′ receives a switch signal and turns into the charging mode. The Step S 703  is that the bidirectional wireless charging device  1 ′ receives a PWM signal PWM from another bidirectional wireless charging device (such as the bidirectional wireless charging device  1 ), so as to charge based on the electromagnetic energy of the PWM signal PWM. The Step S 704  is that the bidirectional wireless charging device  1 ′ converts the electromagnetic energy into a regulated voltage and provides the regulated voltage to the power storage unit  13 ′ for charging. 
     The Step S 705  is that control unit  1010 ′ of the bidirectional wireless charging device  1 ′ determines whether the power provided from the power storage unit  13 ′ to the bidirectional wireless charging device  1 ′ is within a normal range. As described above, those skilled in the art can set this normal range of power provided by the power storage unit  13 ′ based on need. If the power provided by the power storage unit  13 ′ is within the normal range, it goes to the Step S 706 . If the power provided by the power storage unit  13 ′ is not within the normal range, it goes to the Step S 707 . 
     The Step S 706  is that the control unit  1010 ′ determines whether the power stored in the power storage unit  13 ′ reaches a predetermined value. If the control unit  1010 ′ determines that the power stored in the power storage unit  13 ′ reaches the predetermined value, it goes to the Step S 708 , otherwise it goes to the Step S 707 . As described above, those skilled in the art can set a predetermined value of power stored in the power storage unit  13 ′ based on need. The Step S 707  is that the control unit  1010 ′ makes the modulation unit  1041 ′ drive the coil  11 ′ to generate a PWM signal PWM′ including an energy adjusting request or an energy maintaining request, so as to inform the bidirectional wireless charging device  1  of its electric quantity information. After the bidirectional wireless charging device  1  receives the PWM signal PWM′, it adjusts the output power according to the status message of the PWM signal PWM′ and continues to provide the electromagnetic energy to the bidirectional wireless charging device  1 ′. 
     The Step S 708  is that the power stored in the power storage unit  13 ′ reaches the predetermined value, so the control unit  1010 ′ makes the modulation unit  1041 ′ drive the coil  11 ′ to generate a PWM signal PWM′ including a cut-off supply request. After that, the bidirectional wireless charging device  1 ′ outputs the PWM signal PWM′ to the bidirectional wireless charging device  1 , so that that bidirectional wireless charging device  1  stops charging the bidirectional wireless charging device  1 ′. The Step S 709  is ending the charging process. 
     To sum up, the bidirectional wireless charging device provided by the instant disclosure can be used as a powering end or a charging end to improve the convenience of the bidirectional wireless charging device. Moreover, compared with the traditional bidirectional wireless charging device, the transceiver chip of the bidirectional wireless charging device provided by the instant disclosure integrates the power mode operation module and the charging mode operation module into a single chip. Thereby, merely one control module and one power stage circuit are needed for the instant disclosure to provide the bidirectional wireless charging function, which effectively shrinks the circuit area, decreases the cost and also reduces the system complexity. 
     In addition, in the transceiver chip provided by the embodiment of the instant disclosure, the power mode operation module and the charging mode operation module are set to use one control module and one power stage circuit together, and the number of pins of the transceiver chip also decreases. In detail, in the power mode, part of the pins of the transceiver chip can be necessarily used for powering. When switching to the charging mode, the above part of the pins would be necessarily used with the change of the transceiver chip&#39;s mode. In other words, part of the pins of the transceiver chip is used both in the power mode and the charging mode. Thereby, the number of pins of the transceiver chip can be decreased, which effectively reduces the cost of the transceiver chip. 
     Moreover, the traditional bidirectional wireless charging device using the electromagnetic induction technology would lose some power after electromagnetic transduction because of the external circuit, which decreases the power obtained by the bidirectional wireless charging device. The bidirectional wireless charging device provided by the embodiment of the instant disclosure integrates the switching circuit, the rectifying circuit and the demodulation circuit into a single transceiver chip, which reduces the power loss and thus increases the efficiency of the bidirectional wireless charging device. 
     The bidirectional wireless charging device provided by the embodiment of the instant disclosure also provides an automatic charging function. When there is not sufficient power, the bidirectional wireless charging device would automatically search for a nearby bidirectional wireless charging device for charging, so that the user need not manually operate the bidirectional wireless charging device for charging. 
     The descriptions illustrated supra set forth simply the preferred embodiments of the instant disclosure; however, the characteristics of the instant disclosure are by no means restricted thereto. All changes, alterations, or modifications conveniently considered by those skilled in the art are deemed to be encompassed within the scope of the instant disclosure delineated by the following claims.