Abstract:
A non-contact power system transfers power and signals simultaneously. The signals control the non-contact power system. And an operational frequency is operated on a resonant frequency so that there is no voltage alternating on power switch and power loss is reduced.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a non-contact power system; more particularly, relates to obtaining changes in gap size and output load through electromagnetic coupling to automatically adjust frequency for stable output voltage. 
   DESCRIPTION OF THE RELATED ARTS 
   A contact power system transfers power by contacting a plug and a socket, where a spark may happen on contacting the plug and the socket. In addition, the contact point may be worn out, oxidized or covered by dust and is not well contacted so that a transfer rate may be reduced and the lifetime of the system is shortened, not to mention the inconvenience of plugging the plug into the socket. 
   A non-contact power system has a great potential to be applied to pits, devices for oil mining, medical machines and dust-free room. The non-contact power system is also applied to an electric toothbrush, an electric shaver, a wireless mouse, a mobile telephone, etc. And, the technique concerning applying the non-contact power system to electric vehicles is developed for years, such as non-contact power chargers for electric vehicles developed in USA and Japan. 
   In these years, a technique of wireless power charger for the electric vehicle is mature. And it is still under development concerning power converters and conversion efficiency. A design of an electromagnetic coupler inside the wireless power system provides a bi-directional transference of power and signals; and the wireless power system is monitored and controlled through data comparison. 
   Additionally, assuring data accuracy in a transference and avoiding signals from interferences are essential in designing an electromagnetic coupler. However, to stabilize the system and control its performance, changes on load and gap in the system need to be acquired. Yet the separation in the structure makes current statuses of the load and the gap hard to be precisely known. 
   As a result, concerning a contact power system, a spark may be produced on contacting a plug and a socket; a contact point may be worn out, oxidized or covered by dust and is not well contacted and so a transfer rate may be reduced and the lifetime of the system is shortened; and plugging a plug into a socket may be inconvenient in some situations. In the other hand, concerning a no n-contact power system, current statuses of load and gap is hard to be precisely known. Hence, the prior arts do not fulfill users&#39; requests on actual use. 
   SUMMARY OF THE INVENTION 
   The main purpose of the present invention is to obtain changes in gap size and output load, to transfer power and signals simultaneously and to automatically adjust frequency to obtain a stable output voltage 
   To achieve the above purpose, the present invention is a non-contact power system with load and gap detection, comprising a non-contact transformer, a primary device and a secondary device, where the non-contact transformer comprises a first core and a second core; the first core and the second core each comprises one energy coil and two signal coil; the primary device is connected with the first core and comprises an input stage module, a power stage module and a feed-back control module; the in put stage module comprises an alternating current (AC) power source, an electro-magnetic interference (EMI) noise filter and surge absorber, an AC/DC (direct current) converter and a bridge rectifier; the power stage module comprises a half-bridge series resonant converter and a driving circuit; the feed-back control module comprises a gap detection circuit, a load detection circuit and a micro control unit; the secondary device is connected with the second core and comprises an output stage module; and the output stage module comprises a center-tapped rectifier, a capacitor filter and a load unit. Accordingly, a novel non-contact power system with load and gap detection is obtained. 

   
     BRIEF DESCRIPTIONS OF THE DRAWINGS 
     The present invention will be better understood from the following detailed description of the preferred embodiment according to the present invention, taken in conjunction with the accompanying drawing, in which 
       FIG. 1  is the structural view showing the preferred embodiment according to the present invention; and 
       FIG. 2  is the enlarged view showing a core of the preferred embodiment. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The following description of the preferred embodiment is provided to understand the features and the structures of the present invention. 
   Please refer to  FIG. 1  and  FIG. 2 , which are a structural view showing a preferred embodiment and an enlarged view showing a core of the preferred embodiment according to the present invention. As shown in the figures, the present invention is a non-contact power system  1  with load and gap detection, comprising a non-contact transformer  11 , a primary device  12  and a secondary device  13 , where the non-contact transformer  11  comprises a first core  111  and a second core  112 ; the first core  111  comprises a first energy coil  1111 , a first signal coil  1112  and a second signal coil  113 ; the first core  111  is connected with the primary device  12 ; the second core  112  comprises a second energy coil  121 , a third signal coil  1122  and a fourth signal coil  1123 ; the second core  112  is connected with the secondary device  13 ; the first energy coil  1111  and the second energy coil  1121  have the same winding direction; and the third energy coil  1122  and the fourth energy coil  1123  have opposite winding directions. When using the present invention, magneto resistance is produced. The first signal coil  1112  is at the upper side of the first core  111  and has the same winding direction as the first energy coil  1111 . The second signal coil  1112  is at the lower side of the first core  111  and has a reverse winding direction to the first energy coil  1111  to balance off energy. Or, the second signal coil  1113  has the same winding direction as the first energy coil  1111  to enhance energy. And the first core  111  and the second core  112  each can be further added with one energy coil and two signal coils. An area enclosed by the first energy coil  1111  of the first core  111  and the second energy coil  1121  of the second 0 core  112  is twice larger than an area enclosed by the first and the second signal coils  1112 ,  1113  of the first core  111  and the third and the fourth signal coils  1114 ,  1115  of the second core  112 . That is, the magneto resistance at the upper side and the lower side of the first core  111  and the second core  112  is only a half to the magneto resistance in the middle. An alternating magnetic flux is produced at the coil of the first core  111  by alternating a power switch. The magnetic flux is uniformly distributed at two opposite sides of the first core  111 . Hence the alternating magnetic flux of the first energy coil  1111  has the lowest impact on the first and the second signal coils  1112 ,  1113  and thus the signal recognition is improved for the signal coil. As a result, by surrounding a core with coils according to the present invention, changes in load and gap of a non-contact power system are acquired. 
   The primary device  12 , comprising an input stage module  121 , a power stage module  122  and a feed-back control module  123 , provides a power source for the non-contact power system  1 , where the input stage module  121  comprises an alternating current (AC) power source  1211 , an electro-magnetic interference (EMI) noise filter and surge absorber  1212 , an AC/DC (direct current) converter  1213  and a bridge rectifier  1214 . Therein, the AC power source  1211  provides an AC power to the EMI noise filter and surge absorber  1212 ; the EMI noise filter and surge absorber  1212  keeps the power source stable and avoids interferences by noises. Then the power source is transferred to the power stage module  122  by the bridge rectifier  1214 . In the other hand, the AC power source  1211  provides AC power to the AC/DC converter  1213  for transforming the AC power into a DC power; and then the transformed DC power is transferred to the power stage module  122  and the feed-back control module  123 . 
   The power stage module  122  comprises a half-bridge series resonant converter  1221  and a driving circuit  1222 . The half-bridge series resonant converter  1221  receives the power source transferred from the bridge rectifier  1214  of the input stage module  121 ; receives signals transferred by the driving circuit  1222 ; and transfers energy to the first energy coil  111  of the non-contact transformer  11 . The half-bridge series resonant converter  1221  operates a frequency on a resonant frequency for no voltage alternating on power switch to reduce power loss. 
   The feed-back control module  123  comprises a gap detection circuit  1231 , a load detection circuit  1232  and a micro control unit  1233 . The gap detection circuit  1231  and the load detection circuit  1232  of the feed-back control module  1233  receive signals transferred from the second signal coil  112  and the third signal coil  113  respectively. Then the signals are transferred to the micro control unit  1233 . The micro control unit  1233  obtains its power from the input stage module  121 ; and processes signals transferred from the gap detection circuit  1231  and the load detection circuit to be outputted to the driving circuit  1222 . 
   And then, the signals are transferred from the primary device  12  to the secondary device  13  to be outputted, where the signals are transferred to the secondary device  13  in a resonant way between the first core  111  and the second core  112  in the non-contact transformer  11 . The secondary device  13  comprises an output stage module  131 ; the output stage module  131  comprises a center-tapped rectifier  1311 , a capacitor filter  1312  and a load unit  1313 ; the output stage module  131  receives power transferred from the non-contact transformer  11  and outputs a stable voltage through the center-tapped rectifier  1311  and the capacitor filter  1312 . 
   Hence, the present invention has the following advantages: 
   1. The present invention uses a non-contact transformer having an EE core so that a non-contact power system transfers power and signal at the same time. 
   2. A secondary device requires no sensor or feed-back controller at output. 
   3. A first core and a second core in the non-contact transformer senses changes in load and gap size according to a size and a distribution of its magnetic field 
   4. The first core and the second core in the non-contact transformer detect the size of the gap with a sum of voltage of signal coils and detect the changes in load with a subtraction of voltage of energy coils. 
   5. A half-bridge series resonant converter of a power stage module enhances power transference in a resonant way. 
   6. The present invention automatically figures out a best power with a stable voltage according to the changes between the gap and the load. 
   To sum up, the present invention is a non-contact power system with load and gap detection, where electromagnetic coupling is used to obtain changes in gap size and load output; power and signals are transferred at the same time through a core in a non-contact transformer; and frequency can be automatically adjusted to obtain a stable voltage. 
   The preferred embodiment therein disclosed is not intended to unnecessarily limit the scope of the invention. Therefore, simple modifications or variations belonging to the equivalent of the scope of the claims and the instructions disclosed herein for a patent are all within the scope of the present invention.