Patent Publication Number: US-2017359102-A1

Title: Wireless power transmitting apparatus and wireless charging system comprising the same

Description:
TECHNICAL FIELD 
     The present invention relates to a wireless power transmitting apparatus and a wireless charging system which includes the wireless power transmitting apparatus. 
     BACKGROUND ART 
     Wireless charging technology is a technology which is able to wirelessly supply and receive power without a connector for delivering the power. There is wireless charging technology such as an electromagnetic induction method using a coil, a wireless power transferring method converts electric energy into microwaves and delivers the microwaves, and a method using resonance. 
     The electromagnetic induction method is a method in which power is transferred between a first coil and a second coil using electricity-generating properties as a result of moving a magnet toward the coils to generate an induction current. That is to say, it is a method in which a magnetic field is generated at a transmitting end, and instead of a magnet, the magnetic field generates energy at a receiving end, in which this phenomenon is called a magnetic induction phenomenon. Because the efficiency of energy transfer of the electromagnetic induction method is excellent, the electromagnetic induction method has been used widely and has been adapted to various devices. 
     A resonance method uses resonating properties of sound, such as when a tuning fork is resonated, a wine glass next to the tuning fork is resonated with the same frequency as that of the tuning fork. Nevertheless, the resonance method resonates an electromagnetic wave containing electric energy, instead of resonating the sound. 
     RF/Micro wave radiation method is a power transferring method in which power energy is converted into microwaves which is advantageous for wireless transfer and delivering energy. In the aforementioned method, a concept of a signal is not that which is used for wireless communication such as a radio or a wireless telephone, but a concept of sending electric energy; i.e. not a signal sent with a carrier wave in normal communication, but the wireless power transfer which only sends a carrier wave. 
     In wireless charging, when an apparatus for wireless power charging is detected at a wireless power transmitting side, the power for the charging is transferred so as to supply the power to the apparatus and it is identified whether the apparatus is for wireless charging. If the apparatus is identified as an apparatus for wireless charging, power transfer is negotiated and then a wireless power receiving apparatus starts to be charged. Next, the wireless power transmitting apparatus supplies the power to the corresponding wireless power receiving apparatus, however, there is a problem in that there is no means for identifying directly whether the charging of the wireless power receiving apparatus is completed so that after completing of charging, the power continues to be supplied to the wireless power receiving apparatus. The efficiency of the power which is supplied after completion of charging is significantly lowered and results in unnecessary waste of power. 
     DISCLOSURE 
     Technical Problem 
     Embodiments of the present invention provide a wireless power transmitting apparatus capable of monitoring a charging state of a wireless power receiving end at a wireless power transmitting end in real time and determining a fully-charged state on its own and a wireless charging system including the wireless power transmitting apparatus. 
     Furthermore, embodiments of the present invention provide a wireless power transmitting apparatus capable of preventing unnecessary loss of power by controlling an amount of transmitting power when wireless charging has been completed and a wireless charging system including the wireless power transmitting apparatus. 
     Furthermore, embodiments of the present invention provide a wireless power transmitting apparatus capable of preventing misjudgment of the completion of charging, which may be caused by environmental factors such as high temperature at a wireless power receiving end and a wireless charging system including the wireless power transmitting apparatus. 
     Technical Solution 
     According to one embodiment of the present invention, a wireless power transmitting apparatus is disclosed which includes: a detecting unit which detects at least one of current and voltage of a wireless power transmitting coil; and a charge monitoring unit which determines when wireless charging has been completed in the case that at least one of the detected current and voltage is shown to be below a charge threshold value over a set amount of time. 
     A control unit may further be included which regulates transmitting voltage when the wireless charging has been completed. 
     The control unit may regulate the transmitted voltage using the detected current value when the wireless charging has been completed. 
     The control unit may regulate the transmitted voltage based on a reduction rate of the detected current value when the wireless charging has been completed. 
     An alarm unit may be configured to further be included which outputs an alarm to the outside when the wireless charging has been completed. 
     The charge monitoring unit receives received power from a wireless power receiving apparatus, and when the received power value is shown to be below a reception threshold value during the set period of time, it may be determined that the wireless charging has been completed. 
     The charge monitoring unit may determine whether the wireless charging has been completed by comparing the received power value with the reception threshold value when at least one of the detected current and voltage is shown to be below the charging threshold value over a set amount of time. 
     A control unit may further be included which regulates transmitted voltage when the wireless charging has been completed. 
     The control unit may regulate the transmitted voltage based on the received power value when the wireless charging has been completed. 
     The control unit may regulate the transmitting voltage based on a reduction rate of the received power value when the wireless charging has been completed. 
     The charging threshold value may be set to 90% or less of a charge value in a state in which the charging is in progress. 
     Advantageous Effects 
     The wireless power transmitting apparatus and the wireless charging system including the wireless power transmitting apparatus of the present invention are able to monitor a charging state of a wireless power receiving end at a wireless power transmitting end and determine a fully-charged state on their own. 
     Further, it is possible to prevent unnecessary loss of power by controlling an amount of transmitting power when wireless charging is completed. 
     Further, it is possible to prevent misjudgment of charge completion which may be caused by environmental factors such as high temperature at a wireless power receiving end. 
    
    
     
       DESCRIPTION DRAWINGS 
         FIG. 1  is a block diagram of components of a wireless charging system according to an embodiment of the present invention, 
         FIG. 2  is a conceptual diagram of a wireless charging system according to an embodiment of the present invention, 
         FIG. 3  is a block diagram of components of a wireless power transmitting apparatus according to an embodiment of the present invention, 
         FIG. 4  is a drawing for explaining operation of a wireless power transmitting apparatus according to an embodiment of the present invention, and 
         FIG. 5  is a drawing for explaining operation of a wireless power transmitting apparatus according to another embodiment of the present invention. 
     
    
    
     MODES OF THE INVENTION 
     While the invention is open to various modifications and alternative embodiments, specific embodiments thereof are shown by way of example in the drawings and will be described. However, it should be understood that there is no intention to limit the invention to the particular embodiments disclosed, but on the contrary, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. 
     It will be understood that, although the terms including ordinal numbers such as “first,” “second,” etc. may be used herein to describe various elements, these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, a second element could be termed a first element without departing from the teachings of the present inventive concept, and similarly a first element could be also termed a second element. The term “and/or” includes any and all combination of one or more of the associated items listed. 
     When an element is referred to as being “connected to” or “coupled with” another element, it can not only be directly connected or coupled to the other element, but also it can be understood that intervening elements may be present. In contrast, when an element is referred to as being “directly connected to” or “directly coupled with” another element, there are no intervening elements present. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the present inventive concept. As used herein, the singular forms “a,” “an,” and “the,” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof 
     Unless otherwise defined, all terms including technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this inventive concept belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
     Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, and regardless of the numbers in the drawings, the same or corresponding elements will be assigned with the same numbers and overlapping descriptions will be omitted. 
       FIG. 1  is a block diagram of components of a wireless charging system according to an embodiment of the present invention, and  FIG. 2  is a conceptual diagram of a wireless charging system according to an embodiment of the present invention. 
     Referring to  FIG. 1  and  FIG. 2 , a wireless charging system  10  includes a power source  100 , a wireless power transmitting apparatus  200 , a wireless power receiving apparatus  300 , and a load terminal  400 . 
     The wireless power transmitting apparatus  200  is connected to the power source  100  and receives power from the power source  100 . The wireless power transmitting apparatus  200  wirelessly transmits power to the wireless power receiving apparatus  300 . In this case, the wireless power transmitting apparatus  200  may transmit power using an electromagnetic induction method or a resonance method. Although the power source  100  and the wireless power transmitting apparatus  200  are illustrated as separated elements, the structure is not limited thereto. The power source  100  may be included in the wireless power transmitting apparatus  200 . 
     The wireless power receiving apparatus  300  wirelessly receives power from the wireless power transmitting apparatus  200 . The wireless power receiving apparatus  300  may also receive power using the electromagnetic induction method or the resonance method. Furthermore, the wireless power receiving apparatus  300  provides the received power to the load terminal  400 . The load terminal  400  may be a battery or a device with a built-in battery. The load terminal  400  and the wireless power receiving apparatus  300  are illustrated as separated elements, the structure is not limited thereto. The load terminal  400  may be included in the wireless power receiving apparatus  300 . 
     The wireless power transmitting apparatus  200  may include a transmitting coil  210  and a monitoring unit  220 . The wireless power receiving apparatus  300  may include a receiving coil  310  and a rectifying unit  320 . 
     The power source  100  may generate an alternating current (AC) power having a predetermined frequency and supply it to the transmitting coil  210  of the wireless power transmitting apparatus  200 . 
     Further, the alternating current generated by the transmitting coil  210  may be delivered to the receiving coil  310  which is inductively coupled to the transmitting coil  210 . On the other hand, the power delivered to the transmitting coil  210  may be delivered to the wireless power receiving apparatus  300  having the same resonance frequency as the wireless power transmitting apparatus  200  through a frequency resonance method. The power may be transferred between two impedance matched LC circuits through resonance. 
     The power delivered to the receiving coil  310  may be rectified through the rectifying unit  320  and delivered to the load terminal  400  using the electromagnetic induction method or the resonance method. 
     The monitoring unit  220  may monitor the charging state of the wireless power receiving apparatus. 
       FIG. 3  is a block diagram of components of the monitoring unit according to an embodiment of the present invention. 
     Referring to  FIG. 3 , the monitoring unit  220  according to an embodiment of the present invention may be configured to include a detecting unit  221 , a charge monitoring unit  222 , a control unit  223 , and an alarm unit  224 . 
     The detecting unit  221  may detect at least one of current and voltage of the wireless power transmitting coil  210 . The detecting unit  221  may be configured to include, for example, a current transformer, an electric transformer, and a transformer and to detect current which is flowing through the transmitting coil  210  or voltage which is applied to the transmitting coil  210  and deliver it to the charge monitoring unit  222 . 
     The charge monitoring unit  222  may determine that wireless charging is completed when time during which at least one of the detected current and voltage is kept below a charging threshold value exceeds a first predetermined time. When the charging is completed, current flowing through the transmitting coil  210  is decreased as compared to the time that the charging is in progress. When at least one of the current and voltage which is detected at the detecting unit  221  falls below the charging threshold value, the charge monitoring unit  222  may determine whether the wireless charging has been completed by determining duration during which the detected current or voltage falls below the charging threshold value. 
     The charging threshold value, for example, may be set to  90 % or less of a charging current value or charging voltage value, and may be set differently depending on a type of the wireless power receiving apparatus. The charging threshold may be set differently based on the respective current and voltage. The charge monitoring unit  222  may independently compare the detected current value and the detected voltage value with each respective charging threshold value for the current and the voltage and determine the detected current value and the detected voltage value. In addition, the first predetermined time is for determining duration during which at least one of the current and the voltage of the receiving coil  210  is shown to be below the charging threshold value, and may be set differently depending on a type of the wireless power receiving apparatus  300 . 
     However, in contrast, the charge monitoring unit  222  may compare the received power value which is received from the wireless power receiving apparatus  300  with the reception threshold value, and when the time in which the received power value is kept below the threshold value exceeds a second predetermined time, it may be determined that wireless charging is completed. In this case, the second predetermined time may be set differently from the case in which it is determined whether the wireless charging has been completed using the detected current value and voltage value. 
     In addition, when a time in which at least one of the current and the voltage is kept below the charging threshold value exceeds the first predetermined time, the charge monitoring unit  222  may compare the received power value which is received from the wireless power receiving apparatus  300  with the reception threshold value, and when the time in which the received power value is kept below the threshold value exceeds a second threshold time, it may be determined that wireless charging has been completed. That is to say, when all of the detected voltage value, the detected current value, and the received power value satisfy the corresponding conditions, it may be determined that wireless charging has been completed. This can prevent any errors that may occur, due to the high temperature state, noise, or surrounding environmental factors, when determining whether the wireless charging has been completed based only on the detected current value and the detected voltage value. 
     The control unit  223  may regulate the transmitting voltage when the wireless charging has been completed. The control unit  223  may, for example, when the wireless charging has been completed, regulate the transmitting voltage by controlling the power source, or regulate the transmitting voltage so as to not apply the transmitting voltage to the transmitting coil by turning off the power source. 
     The control unit  223  may regulate the transmitting voltage using the detected current value when the wireless charging has been completed, and in this case, the transmitting voltage may be regulated by taking into consideration a reduction rate of the detected current value. That is to say, when the wireless charging has been completed, an amount of the power which can be received at the wireless power receiving apparatus  300  is decreased. The control unit  223  is able to transmit an amount of the power which is adapted to the amount of the power that can be received by the wireless power receiving apparatus  300  by decreasing the amount of the transmitting voltage in proportion to the detected current value. 
     In addition, the control unit  223  may regulate the transmitting voltage using the received power value which is received from the wireless power receiving apparatus  300  when the wireless charging has been completed, and in this case, the transmitting voltage may be regulated by taking into consideration a reduction rate of the received power value. 
     The alarm unit  224  may output an alarm to the outside based on the control of the control unit  223  when the wireless charging has been completed. 
       FIG. 4  is a drawing for explaining operation of a wireless power transmitting apparatus according to an embodiment of the present invention. 
     Firstly, the wireless power transmitting apparatus detects a wireless power receiving apparatus. The wireless power transmitting apparatus may detect the wireless power receiving apparatus, for example, when the wireless power receiving apparatus is placed on the substrate, or when the wireless power receiving apparatus is located within a certain distance (S 401 ). 
     The wireless power transmitting apparatus identifies the type of detected wireless power receiving apparatus. After identifying the detected wireless power receiving apparatus, the wireless power transmitting apparatus loads a charging threshold value, a predetermined time, and a reception threshold value of the corresponding apparatus. In the case of detecting a new wireless power receiving apparatus, a new charging threshold value, a new predetermined time, and a new reception threshold value can be set (S 402 ). 
     The wireless power transmitting apparatus sends a wireless power for charging the detected wireless power receiving apparatus (S 403 ). 
     The detecting unit detects at least one of current and voltage flowing through the receiving coil and delivers the detected current or voltage to the charge monitoring unit (S 404 ). 
     The charge monitoring unit determines whether at least one of the detected current and voltage is shown to be below the charging threshold value (S 405 ). 
     When at least one of the detected current and voltage is shown to be below the charging threshold value, the charge monitoring unit determines whether the duration during which at least one of the detected current and voltage is shown to be below the charging threshold value exceeds the first predetermined time, and if the first predetermined time is exceeded, it is determined that the charging of the wireless power receiving apparatus has been completed (S 406 ). 
     When it is determined that the charging of the wireless power receiving apparatus has been completed, the control unit regulates voltage which is applied to the transmitting coil, and controls the alarm unit so as to be able to output an alarm to the outside (S 407 ). 
       FIG. 5  is a drawing for explaining operation of a wireless power transmitting apparatus according to another embodiment of the present invention. 
     Firstly, the wireless power transmitting apparatus detects a wireless power receiving apparatus. The wireless power transmitting apparatus may detect the wireless power receiving apparatus, for example, when the wireless power receiving apparatus is placed on the substrate, or when the wireless power receiving apparatus is located within a certain distance (S 501 ). 
     The wireless power transmitting apparatus identifies the type of the detected wireless power receiving apparatus. After identifying the detected wireless power receiving apparatus, the wireless power transmitting apparatus loads a charging threshold value, a predetermined time, and a reception threshold value of the corresponding apparatus. In the case of detecting a new wireless power receiving apparatus, a new charging threshold value, a new predetermined time, and a new reception threshold value can be set (S 502 ). 
     The wireless power transmitting apparatus sends wireless power for charging the detected wireless power receiving apparatus (S 503 ). 
     The detecting unit detects at least one of current and voltage flowing through the receiving coil and delivers the detected current or voltage to the charge monitoring unit (S 504 ). 
     The charge monitoring unit determines whether at least one of the detected current and voltage is shown to be below the charging threshold value (S 505 ). 
     When at least one of the detected current and voltage is shown to be below the charging threshold value, the charge monitoring unit determines whether the received power value which is received from the wireless power receiving apparatus is shown to be below the reception threshold value (S 506 ). 
     The charge monitoring unit determines whether the duration during which at least one of the detected current and voltage is shown to be below the charging threshold value and the duration during which the received power value which is received from the wireless power receiving apparatus exceeds the first predetermined time and the second predetermined time, and if one of the predetermined times has been exceeded respectively, it is determined that the charging of the wireless power receiving apparatus has been completed (S 507 ). 
     When it is determined that the charging of the wireless power receiving apparatus has been completed, the control unit regulates voltage which is applied to the transmitting coil, and controls the alarm unit so as to be able to output an alarm to outside (S 508 ). 
     The term “unit” used herein refers to software or hardware such as FPGA programmable gate array) or ASIC, and components which are refers to as “unit” perform certain roles. However, the term “unit” is not limited to software or hardware. A “Unit” may be configured to be placed in a storage medium which is capable of addressing and may be configured to operate one or more processors. Accordingly, by way of an example, a “unit” includes components such as software components, object-oriented software components, class components and task components, and functions, attributes, procedures, subroutines, segments of a program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. Functions provided within the components and “units” may combine to be a smaller number of components and “units” or be separated as additional components and “units”. Moreover, the components and “units” may be made to operate one or more CPUs within a device or a secured multimedia card. 
     Although exemplary embodiments of the present invention have been referenced and described above, it will be understood that it is possible for those of ordinary skill in the art to implement modifications and variations on the present invention without departing from the concept and scope of the present invention listed in the following appended claims.