Patent Publication Number: US-2016248277-A1

Title: Resonant type high frequency power supply device and switching circuit for resonant type high frequency power supply device

Description:
FIELD OF THE INVENTION 
     The present invention relates to a resonant type high frequency power supply device and a switching circuit for the resonant type high frequency power supply device that perform power transmission at a high frequency. 
     BACKGROUND OF THE INVENTION 
     In a conventional resonant type high frequency power supply device shown in  FIG. 14 , a high frequency FET (Field Effect Transistor) for RF (Radio Frequency) is used as a power element Q 1 . A drive circuit of transformer type  101  and an RF power amplifier circuit  102  are used to drive this high frequency FET, and a multi-output type power supply circuit  103  is further used to drive the RF power amplifier circuit  102  (for example, refer to nonpatent reference 1). 
     RELATED ART DOCUMENT 
     Nonpatent Reference 
     
         
         Nonpatent reference 1: Transistor Technology, February 2005, Chapter 13 
       
    
     SUMMARY OF THE INVENTION 
     Problems to be Solved by the Invention 
     However, a problem with the conventional configuration disclosed by nonpatent reference 1 is that because the drive circuit of transformer type  101 , the RF power amplifier circuit  102  and the multi-output type power supply circuit  103  are used to drive the power element Q 1 , the circuit configuration is complicated and the component count increases, and hence the device is upsized and the cost also increases. A further problem is that because the power consumption in each of the above-mentioned circuits  101  to  103  is large, the power consumption in the whole of the resonant type high frequency power supply device also becomes large, and this results in a reduction in the power conversion efficiency. 
     The present invention is made in order to solve the above-mentioned problems, and it is therefore an object of the present invention to provide a resonant type high frequency power supply device and a switching circuit for the resonant type high frequency power supply device that achieve simplification, downsizing and a cost reduction thereof and also achieve high efficiency with low power consumption and that can operate at a high frequency exceeding 2 MHz, by driving a power element without using a drive circuit of transformer type, an RF power amplifier circuit and a multi-output power supply circuit. 
     Means for Solving the Problem 
     In accordance with the present invention, there is provided a resonant type high frequency power supply device provided with a power element that performs a switching operation, the resonant type high frequency power supply device including: a high frequency pulse drive circuit that transmits a pulse-shaped voltage signal at a high frequency exceeding 2 MHz to the power element to drive the above-mentioned power element; a variable pulse signal generating circuit that transmits a pulse-shaped voltage signal at a high frequency exceeding 2 MHz to the high frequency pulse drive circuit to drive the above-mentioned high frequency pulse drive circuit; and a bias power supply circuit that supplies driving power to both the variable pulse signal generating circuit and the high frequency pulse drive circuit. 
     Advantages of the Invention 
     Because the resonant type high frequency power supply device in accordance with the present invention is configured as above, the resonant type high frequency power supply device achieves simplification, downsizing and a cost reduction thereof and also achieves high efficiency with low power consumption, and can operate at a high frequency exceeding 2 MHz, by driving the power element without using a drive circuit of transformer type, an RF power amplifier circuit and a multi-output power supply circuit. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is a diagram showing the configuration of a resonant type high frequency power supply device in accordance with Embodiment 1 of the present invention (in a case in which a power element has a single configuration); 
         FIG. 2  is a diagram showing another example of the configuration of the resonant type high frequency power supply device in accordance with Embodiment 1 of the present invention (in a case in which a hybridized element is used); 
         FIG. 3  is a diagram showing another example of the configuration of the resonant type high frequency power supply device in accordance with Embodiment 1 of the present invention (in a case in which a hybridized element is used); 
         FIG. 4  is a diagram showing another example of the configuration of the resonant type high frequency power supply device in accordance with Embodiment 1 of the present invention (in a case in which a hybridized element is used); 
         FIG. 5  is a diagram showing another example of the configuration of the resonant type high frequency power supply device in accordance with Embodiment 1 of the present invention (in a case in which a hybridized element is used); 
         FIG. 6  is a diagram showing another example of the configuration of the resonant type high frequency power supply device in accordance with Embodiment 1 of the present invention (in a case in which a hybridized element is used); 
         FIG. 7  is a diagram showing another example of the configuration of the resonant type high frequency power supply device in accordance with Embodiment 1 of the present invention (in a case in which a hybridized element is used); 
         FIG. 8  is a diagram showing another example of the configuration of the resonant type high frequency power supply device in accordance with Embodiment 1 of the present invention (in a case in which a hybridized element is used); 
         FIG. 9  is a diagram showing another example of the configuration of the resonant type high frequency power supply device in accordance with Embodiment 1 of the present invention (in a case in which a hybridized element is used); 
         FIG. 10  is a diagram showing another example of the configuration of the resonant type high frequency power supply device in accordance with Embodiment 1 of the present invention (in a case in which a hybridized element is used); 
         FIG. 11  is a diagram showing another example of the configuration of the resonant type high frequency power supply device in accordance with Embodiment 1 of the present invention (in a case in which the power elements have a push-pull configuration); 
         FIG. 12  is a diagram showing another example of the configuration of the resonant type high frequency power supply device in accordance with Embodiment 1 of the present invention (in a case in which a variable resonance condition LC circuit is disposed); 
         FIG. 13  is a diagram showing another example of the configuration of the resonant type high frequency power supply device in accordance with Embodiment 1 of the present invention (in a case in which a variable resonance condition circuit is disposed); and 
         FIG. 14  is a diagram showing the configuration of a conventional resonant type high frequency power supply device. 
     
    
    
     EMBODIMENTS OF THE INVENTION 
     Hereafter, the preferred embodiments of the present invention will be explained in detail with reference to the drawings. 
     Embodiment 1 
       FIG. 1  is a diagram showing the configuration of a resonant type high frequency power supply device in accordance with Embodiment 1 of the present invention. In  FIG. 1 , a power element Q 1  represents a circuit in a case of a single configuration. 
     The resonant type high frequency power supply device is comprised of the power element Q 1 , a resonance circuit element (capacitors C 1  and C 2  and an inductor L 2 ), an inductor L 1 , a high frequency pulse drive circuit  1 , a variable pulse signal generating circuit  2  and a bias power supply circuit  3 , as shown in  FIG. 1 . 
     A resonant type transmission antenna (a transmission antenna for power transmission)  10  is a resonant type antenna for power transmission having LC resonance characteristics (which is not limited only to a noncontact type one). This resonant type transmission antenna  10  can be of any of magnetic resonance type, electric resonance type, and electromagnetic induction type. 
     The power element Q 1  is a switching element that performs a switching operation in order to convert a direct voltage Vin, which is an input, into an alternating voltage. As this power element, Q 1 , not only an FET for RF but also an element, such as an Si-MOSFET, an SiC-MOSFET or a GaN-FET, can be used. 
     The resonance circuit element (the capacitors C 1  and C 2  and the inductor L 2 ) is an element that causes the power element Q 1  to perform resonant switching in the switching operation. By using this resonance circuit element which consists of the capacitors C 1  and C 2  and the inductor L 2 , the resonance condition can be caused to match that of the resonant type transmission antenna  10 . 
     The inductor L 1  works to hold the energy of the DC input voltage Vin temporarily, every time when the power element Q 1  performs the switching operation. 
     The high frequency pulse drive circuit  1  is a circuit that transmits a pulse-shaped voltage signal at a high frequency exceeding 2 MHz to a G terminal of the power element Q 1 , to drive the power element Q 1 . This high frequency pulse drive circuit  1  is a circuit which is provided a totem pole output circuit by using an FET or such a device to be able to perform a high-speed ON/OFF output. 
     The variable pulse signal generating circuit  2  is a circuit that transmits a pulse-shaped voltage signal at a high frequency exceeding 2 MHz, such as a logic signal, to the high frequency pulse drive circuit  1 , to drive the high frequency pulse drive circuit  1 . This variable pulse signal generating circuit  2  is comprised of an oscillator for frequency setting and logic ICs such as an inverter and a flip-flop, and has functions such as a function of changing a pulse width and a function of outputting reverse pulses. 
     The bias power supply circuit  3  supplies driving power to both the variable pulse signal generating circuit  2  and the high frequency pulse drive circuit  1 . 
     Next, the operation of the resonant type high frequency power supply device configured as above will be explained. 
     First, the input direct voltage Vin is applied to a D terminal of the power element Q 1  through the inductor L 1 . The power element Q 1  then converts the voltage into a positive voltage in an alternating form by performing the ON/OFF switching operation. At the time of this conversion operation, the inductor L 1  works to hold the energy temporarily, thereby helping the conversion of the direct voltage to the alternating voltage. 
     In this embodiment, in the switching operation of the power element Q 1 , in order to minimize a switching loss due to the product of an Ids current and a Vds voltage, the resonant switching condition is set to conduct a ZVS (zero voltage switching) to the resonance circuit device which consists of the capacitors C 1 , C 2  and the inductor L 2 . By performing this resonant switching operation, the alternating voltage centered on an RTN voltage is outputted as an output voltage Vout. 
     The driving of the power element Q 1  is performed by inputting the pulse-shaped voltage signal, which the high frequency pulse drive circuit  1  which has received the arbitrary pulse-shaped voltage signal from the variable pulse signal generating circuit  2  outputs, to the G terminal of the power element Q 1 . At that time, the driving frequency of the power element Q 1  serves as the operating frequency of the resonant type high frequency power supply device, and is determined by a setting made on the oscillator circuit disposed in the variable pulse signal generating circuit  2 . 
     As mentioned above, because the resonant type high frequency power supply device in accordance with Embodiment 1 is configured in such a way as to output the pulse-shaped voltage signal by using the high frequency pulse drive circuit  1 , the variable pulse signal generating circuit  2  and the bias power supply circuit  3  in order to drive the power element Q 1 , simplification, downsizing and a cost reduction can be achieved on the resonant type high frequency power supply device that performs a high frequency operation exceeding 2 MHz, without using a drive circuit of transformer type  101 , an RF power amplifier circuit  102  and a multi-output power supply circuit  103  for use in a conventional technology. Further, 90% or more high power conversion efficiency characteristics can be provided with low power consumption. 
     In the example shown in  FIG. 1 , an element (a switching circuit for the resonant type high frequency power supply device)  4  in which some components are hybridized can be used.  FIG. 2  shows an element  4  in which the power element Q 1  and the high frequency pulse drive circuit  1  are hybridized,  FIG. 3  shows an element  4  in which the power element Q 1  and the capacitor C 1  are hybridized,  FIG. 4  shows an element  4  in which the power element Q 1 , the capacitor C 1 , and the high frequency pulse drive circuit  1  are hybridized,  FIG. 5  shows an element  4  in which the power element Q 1 , the capacitor C 1 , the high frequency pulse drive circuit  1  and the variable pulse signal generating circuit  2  are hybridized,  FIG. 6  shows an element  4  in which the power element Q 1  and the capacitor C 2  are hybridized,  FIG. 7  shows an element  4  in which the power element Q 1 , the capacitor C 2  and the high frequency pulse drive circuit  1  are hybridized,  FIG. 8  shows an element  4  in which the power element Q 1  and the capacitors C 1  and C 2  are hybridized,  FIG. 9  shows an element  4  in which the power element Q 1 , the capacitors C 1  and C 2  and the high frequency pulse drive circuit  1  are hybridized, and  FIG. 10  shows an element  4  in which the power element Q 1 , the capacitors C 1  and C 2 , the high frequency pulse drive circuit  1  and the variable pulse signal generating circuit  2  are hybridized. 
     Further, although the circuit in the case in which the power element Q 1  has a single configuration is shown in  FIG. 1 , this embodiment is not limited to this example. For example, as shown in  FIG. 11 , the present invention can be similarly applied to a case in which the power element Q 1  has a push-pull configuration. 
     Further, although the explanation about  FIG. 1  is made by assuming that the constants of the resonance circuit element (the capacitors C 1  and C 2  and the inductor L 2 ) are fixed and hence the resonance condition is fixed, this embodiment is not limited to this example. For example, as shown in  FIG. 12 , a variable resonance condition LC circuit  5  that causes the resonance condition to be variable can be alternatively used. Further, for example, as shown in  FIG. 13 , a variable resonance condition circuit  6  that causes the resonance condition according to the above-mentioned resonance circuit element (the capacitors C 1  and C 2  and the inductor L 2 ) to be variable can be disposed separately. 
     Further, while the invention has been described in its preferred embodiment, it is to be understood that various changes can be made in an arbitrary component in accordance with the embodiment, and an arbitrary component in accordance with the embodiment can be omitted within the scope of the invention. 
     INDUSTRIAL APPLICABILITY 
     The resonant type high frequency power supply device and the switching circuit for the resonant type high frequency power supply device in accordance with the present invention achieve simplification, downsizing and a cost reduction thereof and also achieve high efficiency with low power consumption, and can operate at a high frequency exceeding 2 MHz, by driving the power element without using a drive circuit of transformer type, an RF power amplifier circuit and a multi-output power supply circuit. Therefore, the resonant type high frequency power supply device and the switching circuit for the resonant type high frequency power supply device are suitable for use as a resonant type high frequency power supply device and a switching circuit for the resonant type high frequency power supply device that perform power transmission at a high frequency, etc. 
     EXPLANATIONS OF REFERENCE NUMERALS 
       1  high frequency pulse drive circuit,  2  variable pulse signal generating circuit,  3  bias power supply circuit,  4  hybridized element (switching circuit for resonant type high frequency power supply device),  5  variable resonance condition LC circuit,  6  variable resonance condition circuit, and  10  resonant type transmission antenna (transmission antenna for power transmission).