JP5587697B2 - Electric field coupling contactless power supply system - Google Patents

Description

  The present invention relates to an electric field coupling type non-contact power feeding system. More specifically, the present invention relates to an electric field coupling contactless power feeding system that can perform charging and the like in a contactless manner with respect to various loads such as a rechargeable battery provided in a mobile device or the like.

  In recent years, mobile devices having a built-in rechargeable battery (secondary battery) such as a mobile phone, a notebook computer, and a portable audio player have become widespread. In addition, in response to environmental problems such as global warming and energy resource problems, research and development of electric vehicles equipped with power storage devices such as batteries and capacitors have been actively conducted as a means of clean transportation using electric energy. Yes. In such a device, a power supply method for the battery is an important technical problem. There are two types of power supply methods: contact power supply and non-contact power supply. However, in terms of convenience, safety, and forgetting to unplug the power supply method, the battery will be charged rapidly in the future. The method is considered promising.

  There are three non-contact power feeding methods: an electromagnetic induction method, an electromagnetic resonance method, and an electric field coupling method. Among these, the non-contact power feeding system currently in practical use is mainly an electromagnetic induction system for supplying power from coil to coil. However, this electromagnetic induction method has problems such as a decrease in transmission efficiency due to positional deviation between coils, overheating when foreign matter enters between coils, and countermeasures against electromagnetic waves and harmonics. Therefore, recently, the development of a resonance-type non-contact power feeding system using an electric field or a magnetic field is increasing.

  The electromagnetic resonance method is a non-contact power feeding method that is most frequently studied at present, and it has been announced that transmission is possible even at a distance of 2 meters. The power transmission efficiency is still as low as 40%, but if this technology increases the efficiency, there is a possibility that it can charge a running car, and research and development is becoming active. However, this electromagnetic resonance method has a problem that it is heavy and expensive because it uses a ferrite or litz wire coil. Further, the transmission efficiency is drastically lowered due to the position shift, and there are various problems regarding safety, such as a problem of magnetic leakage.

  The electric field coupling method is considered to have a lower transmission power density than the electromagnetic induction method and the electromagnetic resonance method, and has not been studied much. However, according to the research of the present applicant (see, for example, Patent Document 1), there are problems such as overheating and electromagnetic waves at the time of entry of foreign matter, which are resistant to horizontal displacement and are problematic in the electromagnetic induction method currently in practical use. There is a merit that it does not occur. Furthermore, there is an advantage that the weight and cost of the device can be reduced because the ferrite and litz wire coil that are essential in the electromagnetic resonance method are not used. In addition, there is an advantage that even a device having a large output can be dealt with by simply expanding the contact area.

  In this electric field coupling method, an LC resonance phenomenon has been used so far in order to pass a current through a coupling portion having a capacitance. However, since the LC resonance is used, there is a problem that when the capacitance of the coupling portion is changed, the resonance point is shifted and the efficiency is lowered. This problem became more prominent as the Q of the circuit was increased to increase the efficiency. Further, since the inductance has a winding structure, there is a problem that a desired characteristic cannot be obtained due to the capacitance between the lines when the frequency is large and heavy and the frequency is increased.

  On the other hand, the present applicant has been researching active reactance. As an application example, the present applicant succeeded in improving the characteristics of the LC filter by using a negative active capacitor to increase the capacitance of the existing capacitance equivalently. (See Non-Patent Document 1).

JP 2009-89520 A

J. Kamada, Hiroto Funato, Seiji Ogasawara, “Proposal of Low Distortion Switching Power Amplifier Using Small Capacity Linear Amplifier and LC Filter”, D. 127, No. 5, pp.457-464 (2007)

  In the above-described electric field coupling type non-contact power feeding system, it is desirable to increase the transmission power during power feeding. However, in the example of Non-Patent Document 1, a linear amplifier is used to realize an active capacitor, and there is a problem that loss is large.

  Further, the method using a PWM inverter instead of a linear amplifier has a problem that there is a limit to the frequency that can be handled by the PWM inverter.

  The present invention has been made in order to solve the above-described problems, and an object thereof is to use an electric field coupling type non-contact type that can increase transmission power by using an active capacitor without using LC resonance. It is to provide a power feeding system (referred to as “electric field coupling non-contact power feeding system”).

An electric field coupling type non-contact power feeding system according to the present invention for solving the above problems includes a power feeding unit disposed in a power feeding region, and a power fed unit disposed in a power feeding region to supply power to a load. The power supply unit is disposed on the power supply region side of the boundary between the power supply region and the power-supplied region, and an active capacitor control unit that controls the active capacitor, an active capacitor, and the active capacitor. A first power transmission electrode and a second power transmission electrode that receive power supply from the power supply unit, and the power-supplied unit is not sandwiched by sandwiching the boundary with respect to the first power transmission electrode and the second power transmission electrode. A first power receiving electrode and a second power receiving electrode arranged to face each other in a contact manner, and one of the first power receiving electrode and the first power receiving electrode and the second power receiving electrode arranged to face the first power transmitting electrode And the first result A capacitor is configured, and a second coupling capacitor is configured by the second power transmitting electrode and the other one of the first power receiving electrode and the second power receiving electrode disposed opposite to the second power transmitting electrode, It is connected in series to either the first coupling capacitor or the second coupling capacitor, and the phase of the square wave voltage V acc of the active capacitor is made to be the phase of the square wave voltage Vs of the power supply unit by the active capacitor control unit. And the active capacitor operates as a negative capacitance.

According to the present invention, the active capacitor which is a switching signal generator synchronized with the power supply signal from the power supply unit is provided, and the phase of the square wave voltage V acc of the active capacitor is delayed from the phase of the square wave voltage Vs of the power supply unit. (For example, 90 °) and the active capacitor operates as a negative capacitance, the combined voltage V1 is stepped, and the number of rising times of the voltage is doubled. That is, since the number of conduction times of the current Icj can be doubled, the current value supplied to the load can be doubled (√2 times), and the output power can be doubled. As a result, transmission efficiency can be improved. Such an electric field coupling non-contact power feeding system according to the present invention can simplify the configuration circuit, and does not require particularly complicated control. Further, the circuit has the advantage that the capacitance itself can be increased and the impedance can be reduced without being affected by the frequency.

  In the electric field coupling contactless power feeding system according to the present invention, the active capacitor may include a DC power source, or may include a capacitor instead of the DC power source.

  In the electric field coupling contactless power feeding system according to the present invention, one or more active capacitors are connected in series.

  According to the electric field coupling contactless power feeding system according to the present invention, transmission power can be increased without using LC resonance to improve transmission efficiency, the circuit configuration can be simplified, and no complicated control is required. It can be. Furthermore, this circuit configuration has the advantage that the capacitance itself can be increased and the impedance can be reduced without being affected by the frequency.

It is a block diagram which shows the basic composition of the electric field coupling non-contact electric power feeding system which concerns on this invention. It is a block diagram which shows an example of the electric field coupling non-contact electric power feeding system which concerns on this invention. It is the voltage waveform and current waveform of each part of the electric field coupling non-contact electric power feeding system shown in FIG. It is a block diagram which shows another example of the electric field coupling non-contact electric power feeding system which concerns on this invention. It is explanatory drawing of the active capacitor of FIG. It is the voltage waveform and current waveform of each part of the electric field coupling non-contact electric power feeding system shown in FIG. 5 is a voltage waveform Vcs at a capacitor Cs constituting the active capacitor of FIG. It is an initial charge waveform which shows the voltage change at the time of starting from the initial value zero in the voltage Vcs in the capacitor Cs. It is a block diagram which shows another example of the electric field coupling non-contact electric power feeding system which concerns on this invention. It is a phase characteristic of the electric field coupling non-contact electric power feeding system shown in FIG. FIG. 10 is a voltage waveform and a current waveform of each part of the electric field coupling contactless power feeding system shown in FIG. 9. FIG. It is an example of the switching waveform at the time of using the active capacitor formed by connecting four active capacitors in series. It is a block diagram of the circuit used in the experiment example. It is an experimental waveform obtained by the circuit which removed the active capacitor from the circuit used in an experimental example. It is an experimental waveform obtained with the circuit of the experimental example. It is a structural example at the time of removing an active capacitor from the electric field coupling non-contact electric power feeding system which concerns on this invention. It is the voltage waveform and current waveform of each part of the electric field coupling non-contact electric power feeding system shown in FIG. It is an operation waveform according to mode of a capacitor insulation power supply device.

  Hereinafter, an electric field coupling non-contact power feeding system according to the present invention will be described with reference to the drawings. Note that the present invention is not limited to the following embodiments.

[Basic configuration]
As shown in FIG. 1, an electric field coupling non-contact power feeding system (hereinafter sometimes abbreviated as “non-contact power feeding system”) 1 according to the present invention includes a power feeding unit 4 disposed in a power feeding region 2 and a power fed region. 3 is a system for supplying power to the load 8 from the power supply unit 4 via the power supply unit 5. The specific configuration of the power supply area 2 and the power supply area 3 is arbitrary. For example, an internal space of a general house, an internal space of a building such as an office building, an internal space of a vehicle such as a train or an airplane, or an outdoor space Can be mentioned.

(Power supply unit)
The power supply unit 4 is disposed in the power supply region 2 and may be one having a power supply unit 11 in the power supply unit (see FIG. 1), or power is supplied from a power supply unit outside the power supply unit. (Not shown) may be used. The power feeding unit 4 may be a fixed body that is permanently immovable or a movable body that is movable. Further, when not in use, the power supply region 2 may be removed or may be moved to an arbitrary position in the power supply region.

  Specifically, as shown in FIGS. 1 and 2, the power supply unit 4 includes a power supply unit 11, an active capacitor 21, an active capacitor control unit 25 that controls the active capacitor 21, a power supply region 2, and a power supply. A first power transmission electrode 33 and a second power transmission electrode 34 which are arranged on the power supply region side of the boundary portion 6 with the region 3 and receive power supply from the power supply unit 11 are provided.

The active capacitor 21 provided in the power feeding unit 4 is connected in series to either the first coupling capacitor 31 or the second coupling capacitor 32 as shown in FIGS. The active capacitor 21 is controlled by the active capacitor control unit 25 so that the phase of the square wave voltage V acc of the active capacitor 21 is delayed from the phase of the square wave voltage Vs of the power supply unit 11 (for example, 90 °). Yes. Thereby, the active capacitor 21 operates as a negative capacitance.

  The active capacitor 21 is preferably a one-pulse active capacitor that can be realized by switching once in one cycle of the power source. Application of such a one-pulse active capacitor is premised on the use of a square-wave voltage power supply and a choke input rectifier.

Here, the continuous mode and the discontinuous mode will be described using the operation waveforms for each mode of the capacitor insulated power supply device of FIG. As shown in FIG. 18A, the continuous mode in which Ic continuously flows is when _VIN is larger than the maximum voltage Vmax stored in the insulating capacitor. At this time, Ic becomes a square wave current, the transmission efficiency is high, and there is no problem. On the other hand, as shown in FIG. 18B, the discontinuous mode in which Ic flows discontinuously is a case where _VIN and Vmax are equal. In the non-contact power feeding, since it is difficult to increase the capacitance of the junction (the first coupling capacitor 31 and the second coupling capacitor 32), the period of Ic = 0 tends to be long, and the transmission efficiency to the load 8 is increased. There is a problem that goes down. In the case of realizing insulation by a capacitor, the insulation capacitor may be selected so as to be in a continuous mode. However, in the case of contactless power feeding, it is difficult to realize a large junction capacitance. Therefore, in the present invention, in the discontinuous mode, the feed capacity is increased using a one-pulse active capacitor.

  The power supply unit 11 is a DC power supply source. For example, the DC power source 12 may be a storage battery, or may be configured as an AC / DC converter that converts AC power transmitted through a transmission line into DC power. In addition, in the example of FIG. 2, although it represents with the aspect of one storage battery, it is not limited to such an aspect, What was comprised by the some storage battery may be used, and the storage battery and the AC / DC converter were provided side by side. It may be a thing.

  In the power supply unit 11, as shown in FIG. 2 and the like, the DC power supply 12 is switched diagonally by an inverter to generate a square wave. The switching unit 13 is a general one, and includes a transistor, a diode connected in parallel to each transistor, and a switching control unit. Since this invention is an electric field coupling non-contact electric power feeding system, a junction part (the 1st coupling capacitor 31 and the 2nd coupling capacitor 32) is a capacitance. Therefore, the higher the frequency, the lower the capacitance impedance and the more power is supplied to the load. Therefore, in the present invention, the power source is preferably a square wave that can be switched by simple switching of the switch. The power supply unit 11 having such a square wave power supply may supply any voltage value. However, practically, the power supply unit 11 has several V (eg, 1V, 2V, 5V, etc.) to several hundred V (eg, 100V, 200V, etc.). ) Can be supplied. The frequency is not particularly limited, and may be a low frequency of less than 1 Hz, but is practically 1 kHz or more. A high frequency can be as high as several hundred MHz depending on a device to be used, but is usually several MHz.

(Powered part)
The power-supplied part 5 may be one that is fixedly used in the power-supplied region 3 (stationary body), or one that moves in the power-supplied region 3 (movable or movable body). .). The function and the specific configuration of the power-supplied unit 5 are not particularly limited. For example, as a stationary body, an installation place is fixed and home appliances or desktop computers that do not normally move, or are movable, but when charging, Examples include mobile phones, laptops, portable audio players, and cordless vacuum cleaners that do not move on the ground. In addition, examples of the movable body or the moving body include a mobile robot such as a transfer robot, an electric vehicle, and the like.

  Specifically, as shown in FIG. 1 and FIG. 2, the power-supplied part 5 is disposed to face the first power transmission electrode 33 and the second power transmission electrode 34 in a non-contact manner with the boundary part 6 interposed therebetween. A first power receiving electrode 35 and a second power receiving electrode 36 are provided. A load 8 is connected to the power supplied unit 5.

(Boundary part)
A part that partitions the power supply region 2 and the power supplied region 3 is referred to as a “boundary portion 6” (also referred to as a boundary surface). For example, when the power supply area 3 is a living room of a building and the power supply area 2 is a floor portion or a wall portion of the living room, the floor surface or the wall surface becomes a boundary portion. As shown in FIG. 1, the boundary portion 6 includes a first coupling capacitor 31 and a second coupling capacitor 32. The first coupling capacitor 31 includes a first power transmission electrode 33 and any one of a first power reception electrode 35 and a second power reception electrode 36 disposed to face the first power transmission electrode 33. Similarly, the second coupling capacitor 32 includes a second power transmission electrode 34 and one of the first power reception electrode 35 and the second power reception electrode 36 disposed opposite to the second power transmission electrode 34.

(load)
The load 8 is driven by the electric power supplied via the power-supplied unit 5 and exhibits a predetermined function. For example, when the power-supplied unit 5 is a mobile phone, a notebook computer, a portable audio player, a cordless vacuum cleaner, or the like, the rechargeable battery (secondary battery) is applicable. Further, when the power supplied unit 5 is a home appliance, a desktop computer, or the like, a built-in drive power supply unit or the like is applicable. In addition, when the power-supplied unit 5 is a mobile robot such as a transfer robot, an electric vehicle, or the like, a motor or a control unit built in the robot or the like corresponds to this. In addition, the specific configuration of the load 8 is arbitrary. For example, a communication device that performs transmission and reception of communication signals with a device external to the power-supplied unit 5 wirelessly or by wire, and information processing related to various types of information is performed. Examples include information processing equipment.

  The load 8 may be provided integrally with the power supplied unit 5 or may be provided separately from the power supplied unit 5. Further, in FIG. 1 and the like, only one load 8 is shown, but power may be supplied to a plurality of loads connected in series or in parallel to each other.

  As shown in FIG. 1, the electric field coupling non-contact power feeding system 1 configured as described above can supply power from the power feeding unit 4 to the power supplied unit 5 in a non-contact manner. This non-contact power supply is performed using the coupling portions (the first coupling capacitor 31 and the second coupling capacitor 32) arranged via the boundary portion 6. Each of the coupling capacitors 31 and 32 includes a first transmission electrode 33 and a second power transmission electrode 34 provided in the power supply unit 4, and a first power reception electrode 35 and a second power reception electrode 36 provided in the power supply unit 5. (Boundary surface) 6 is arranged so as to be opposed to each other in a non-contact manner with 6 therebetween. The power transmitting electrodes 33 and 34 and the power receiving electrodes 35 and 36 constituting the coupling capacitors 31 and 32 are flat conductors, respectively, and are arranged so as to be substantially parallel to each other.

  In the present invention, at least two such coupling capacitors 31 and 32 are provided and arranged in the power transmission path, and electric field type power transmission is performed via the two coupling capacitors 31 and 32. In addition, according to the structure of this invention, it is not necessary to expose each power transmission electrode 33,34 of the electric power feeding part 4 to the to-be-powered area | region 3, and it has the effect that the safety | security and durability of an electric power supply system can be improved. . In addition, by arranging a plurality of power transmission electrodes 33 and 34, even when the power-supplied unit 5 moves, power can be continuously supplied to the power-supplied unit 5. It also has the effect of ensuring the degree of freedom.

[Circuit configuration having an active capacitor]
First, the circuit configuration (see FIG. 16) of the non-contact power feeding system 101 not connected to the active capacitor 21 will be described, and then the circuit configuration (see FIG. 2) of the non-contact power feeding system 1A according to the present invention will be described.

(Circuit without active capacitor connection)
FIG. 16 is an example of the non-contact power feeding system 101 configured by a circuit that does not connect an active capacitor. In this circuit, the inverter of the power supply unit 111 outputs a high-frequency square wave voltage Vs, and transmits energy to the power-supplied unit 105 through the electric field of the capacitor Cj of the non-contact junction (junction capacitors 131 and 132). Then, the current is rectified by the choke input rectifier circuit included in the power-supplied unit 105, and the DC current Iload is supplied to the load 108. The choke input rectifier circuit is connected with a diode Df for current circulation in consideration of the effect of dead time.

  FIG. 17 shows the voltage waveform and current waveform of each part of the circuit structure shown in FIG. The waveform of FIG. 17 shows that the input DC voltage E output from the power supply unit 111 is 40 V, the switching period T is 100 μs (switching frequency 10 kHz), the coupling unit capacitance Cj is 333 nF × 2, the inductance L is 1.35 mH, and the load resistance R is This is an example of 10Ω. At this time, the current Icj flowing through the coupling portion is set to the discontinuous mode. This discontinuous mode is as described with reference to FIG. In the waveform graph of FIG. 17, Vs in (A) is a square wave voltage output from the power supply unit 111, Vcj in (B) is a voltage applied to the junction capacitors 131 and 132, and (C) Icj is a current flowing in the junction capacitors 131 and 132, Iload in (D) is a current flowing in the load 108, pload in (E) is instantaneous power supplied from the power supply unit 111, and (G) Wload is the load average power.

  The current Icj flows only when there is a potential difference between Vs and 2 × Vcj. When the current Icj flows, the capacitor Cj of the junction capacitors 131 and 132 is charged or discharged. When the voltage Vcj increases or decreases and the voltages Vs and Vcj become equal again, the current Icj is circulated by the load 108, and Icj is It stops flowing.

  As shown in FIG. 17, in the discontinuous mode, power is supplied from the power source to the load 108 only when the current Icj is conducted. Therefore, when the conduction time of Icj is short, the load power Wload is low and transmission is performed. Inefficiency.

  Here, the boundary condition between the continuous mode and the discontinuous mode is obtained. If the current conduction time of one time is ΔT and the switching period is T, the switch is switched twice in one period, and therefore the following formula (1) is in the discontinuous mode.

  The current of the capacitor is expressed by the following formula (2).

  Substituting Equation (2) into Equation (1) results in Equation (3) below, and a discontinuous mode is established under these conditions.

  The load current Iload is determined by the following equation (4), the average voltage Vout applied to the load 108, and the resistance value R thereof.

  Since Vout is also determined by the ratio of ΔT in the period T, the following equation (5) is obtained.

  Formula (4) becomes following formula (6) from formula (2) and formula (5).

  Substituting the above-mentioned circuit element parameters into equation (6) yields I = 1.03 A, which substantially matches the value in FIG. Note that f is a switching frequency, and f = 1 / T.

FIG. 2 is a block diagram showing a non-contact power feeding system 1A according to the present invention having one active capacitor 21. As shown in FIG. The active capacitor 21 is connected in series with the first coupling capacitor 31. Then, as shown in FIGS. 3A and 3B, the active capacitor 21 has a phase of the square wave voltage Vacc of the active capacitor 21 (see FIG. 3B) by the active capacitor control unit 25 (see FIG. 1). Is controlled to be delayed by, for example, 90 ° from the phase of the square wave voltage Vs output from the power supply unit 11 (see FIG. 3A). Such control causes the active capacitor 21 to operate as a negative capacitance.

In this example, the phase of Vacc is delayed by 90 ° from the phase of the square wave voltage Vs. In principle, the phase delay is 90 °, but the phase may be shifted as long as the currents are not continuous (that is, as long as they do not overlap) (that is, the phase may be other than 90 °).

In the example of FIG. 2, the square wave voltage Vacc of the inverter of the active capacitor 21 is equal to the square wave voltage Vs output from the power supply unit 11 (see FIGS. 3A and 3B). The two voltages (Vacc and Vs) may be the same value or different values as shown in FIG. 3, but the same value is advantageous in terms of device selection and is easy to be integrated into an IC. (When the capacitor 24 is used instead of the DC power source 22 as shown in FIG. 4 described later, the voltage is always the same). When both voltages (Vacc and Vs) are set to different values, they can be set to arbitrary values as long as they are not in the continuous mode.

  In the graph of FIG. 3, V1 in (C) is a combined voltage of Vs and Vacc, Vcj in (D) is a voltage applied to the junction capacitors 31 and 32, and Icj in (E) is a junction capacitor. 31, 32, Iload in (F) is current flowing in the load 8, pload in (G) is instantaneous power supplied from the power supply unit 11, and Wload in (G) is load average power It is.

  By performing the control as shown in FIG. 3 with the circuit of FIG. 2, the composite voltage V1 becomes stepped (see FIG. 3C), and the number of times the voltage rises is doubled (see FIG. 3D). . As a result, the number of conduction times of the current Icj is doubled (see FIG. 3E).

  The boundary conditions of the continuous mode and the discontinuous mode and the load current Iload are twice the number of ΔTs in the above equations (1) and (5), so the boundary conditions are as shown in the following equation (7): The load current is expressed by the following formula (8), and the load current value is doubled by the active capacitor connection.

When the load current Iload is calculated under the circuit conditions of FIG. 17, it is 1.4 A, and it can be seen that equation (8) is established. Since the output power is I ² R, it can be seen that when the active capacitor 21 is connected, the output power is doubled, and an improvement in transmission efficiency can be confirmed.

  Here, it was confirmed by the following that the active capacitor 21 was operating as a negative capacitor. That is, considering that Vacc is positive in the counter electromotive force direction, it can be seen that Icj is delayed by approximately 90 ° from Vacc. The characteristic that the current is delayed by 90 ° from the voltage indicates that it is an inductance characteristic. However, it can be said that the circuit shown in FIG. 16 operates as a negative capacitance because there is no change in characteristics due to frequency and the power supply power is increased without causing vibration even during a transient. is there.

(Circuit in which the DC power source that constitutes the active capacitor is replaced with a capacitor)
FIG. 4 is a circuit configured by replacing the DC power source 22 constituting the active capacitor 21 shown in FIG. Since the active capacitor 21 shown in FIG. 2 operates as a capacitor, the DC power supply 22 can be replaced with the capacitor 24 (see FIG. 5).

  When the capacitor 24 is replaced, voltage fluctuation becomes a problem. Therefore, the voltage fluctuation of the capacitor 24 of the active capacitor 21 is considered. The same current as the junction capacitance Cj flows through the capacitor 24. Since the voltage variation is inversely proportional to the capacitance, if the capacitance Cs of the capacitor 24 is k times the junction capacitance Cj (capacitance in each of the junction capacitors 31 and 32), the voltage variation becomes 1 / k. Since the voltage variation of the junction capacitance Cj is twice the power supply voltage E, the voltage variation of the capacitance Cs of the capacitor 24 is 2E / k. When the junction capacitance Cj is 166 nF, the power supply voltage E is 40 V, and the capacitance Cs of the capacitor 24 is 20 μF, the variation of the capacitance Cs is 0.7 V, which is a sufficiently small value. Note that k may be any value as long as it does not become unstable, but is at least 1 and an arbitrary value from several tens (10, 20, 50, etc.) to several hundreds (100, 200, 500, etc.). Can take.

  FIG. 6C shows a current waveform of the capacitance Cs of the capacitor 24. Thus, it can be seen that positive and negative currents flow alternately in Cs, and the average power is zero. FIG. 7 shows the fluctuation of the voltage Vcs of Cs. It can be seen that the voltage Vcs fluctuates every time it is charged and discharged, but does not have a fluctuation range that hinders operation.

(Cs voltage maintenance and initial charge)
In an actual circuit, there is a loss of each part. For this reason, it is conceivable that the voltage Vcs of the capacitance Cs of the capacitor 24 varies. There is also a need for initial charging. However, the circuit according to the present invention shown in FIG. 3 has a preferable characteristic that the voltage Vcs of the capacitor Cs is automatically initially charged to the same level as the power supply voltage Vs and maintained as it is.

  6A and 6C, the current Ics of the capacitor 24 flows in the positive direction when the power supply voltage Vs of the power supply unit 11 fluctuates. On the other hand, as shown in FIGS. 6B and 6C, the current Ics in the capacitor 24 flows in the negative direction when the power supply voltage Vacc of the power supply unit 11 changes.

  Here, since the amplitude of Ics shown in FIG. 6C is determined by the load current, it can be said that if the inductor L is sufficiently large, it is almost constant. As shown in FIG. 2E, the time during which Icj flows once is proportional to the voltage fluctuation at that time. Since the amplitude of the power source square wave Vs and the amplitude of Vacc are equal, the widths of the currents flowing in both positive and negative directions are equal. However, for example, if Vcs is smaller than the power supply voltage Vs and the amplitude of Vacc is smaller than the amplitude of Vs, the current flow width in the negative direction is smaller than the current flow width in the positive direction, and the average current becomes smaller. Become positive. That is, the capacitor Cs of the active capacitor 21 is charged. Then, at the point where Vcs becomes equal to the power supply voltage Vs, the average of Ics becomes zero and is balanced. Since the constituent circuit of the active capacitor 21 according to the present invention has such a mechanism, even if Vcs is zero, it is initially charged up to the voltage value E of the power supply voltage Vs, and further, the voltage value E automatically. Can be held.

  FIG. 8 shows a voltage change when the voltage Vcs at the capacitance Ccs of the active capacitor 21 is started from the initial value (zero) under the parameter conditions of FIG. As shown in FIG. 8, it can be seen that the voltage is automatically maintained after being charged up to the voltage value E of the power supply voltage Vs. The circuit according to the present invention is characterized in that such an operation can be realized without any feedback control of Vcs.

(Other embodiments)
FIG. 9 is a configuration diagram showing still another example of the non-contact power feeding system 1C according to the present invention. 10 shows the phase characteristics of the electric field coupling contactless power feeding system 1C shown in FIG. 9, and FIG. 11 shows the voltage waveform and current waveform of each part of the electric field coupling contactless power feeding system 1C shown in FIG. The circuit of FIG. 9 is a circuit in which another active capacitor (21B) is further connected in series to the active capacitor (21A) shown in FIG. Switching can be performed so that the switching timing of the power supply voltage Vs and V _C1 and V _C2 of each of the active capacitors 21A and 21B is as shown in FIGS. Such a switching pattern can be arbitrarily set.

  As shown in FIGS. 10 (A) and 11 (G), the number of conduction times of the junction current Icj is further increased twice from FIG. 3 (E), the average voltage of Vout is also increased, and the current Iload flowing through the load 8 is large. became. The amplitude of the voltage V1 also increases by ± 50V. As described above, when the active capacitors 21 are increased, the junction current Iload can be constantly flowing. When Vout = E, Iload = E / R, and the load current is maximum.

Here, it is confirmed that the active capacitor 21 operates in the same manner as the negative capacitor. When the combined voltage of the voltages V _C1 and V _C2 of the two active capacitors 21A and 21B is Vc-sum, the combined voltage and the phase of the flowing current are compared. In FIG. 10B, in order to make it easy to understand, each waveform is approximated with a sine wave at the same time. Then, it turns out that a voltage and an electric current have shifted | deviated about 90 degrees. This means that the active capacitor behaves the same as a negative capacitance.

(Still another embodiment)
FIG. 12 is an example of a switching waveform when an active capacitor in which four active capacitors are connected in series is used. As described above, when the number of active capacitors 21 increases, the switching pattern becomes special. The reason is that the average power must be zero. Therefore, a switching pattern is selected so that the average power of the active capacitor is zero.

  Here, there are two conditions for determining the switching pattern. The first condition is that the center of each active capacitor at the time of positive voltage comes to the fall of the power supply voltage Vs, and the second condition is all the rise and fall of the power supply voltage and each active capacitor voltage. The interval is constant. FIG. 12 is an example satisfying these two conditions.

  First, the average power does not become zero unless the first condition is satisfied. Further, regarding the second condition, if the switch is switched before the voltage of Vout becomes zero, there arises a problem that the interval is not constant. In addition, when current conduction overlaps, there is a problem that the discharge amount of one capacitor increases and the voltage cannot be kept constant. Therefore, it is essential to set the switching so as to satisfy the above two conditions.

  In FIG. 11 described above, these two conditions are satisfied. By setting so as to satisfy these conditions, there is an advantage that control is easy because switching of the switches of each active capacitor is performed only once during one cycle of the power source. Even if the number of active capacitors is increased, a switching pulse that satisfies these two conditions may be set. For example, when the number of active capacitors is n, the ON period is expressed by the following formula (9).

  As a result, n switching patterns can be formed, and switching may be performed in accordance with the fall of the power supply voltage at the center of each ON period. As an example, a case where four active capacitors are connected in series is set. In the above formula (9), when 4 is substituted for n and 1 to 4 is substituted for k, as shown in FIGS. 12 (B) to (E), T / 5, 2T / 5, 3T / 5, 4 patterns of 4T / 5 are made. Therefore, switching as shown in FIG. 12 may be performed.

  Hereinafter, specific experimental results of the electric field coupling contactless power feeding system according to the present invention will be described using experimental examples. The present invention is not limited to the following experimental examples.

(Experimental example)
13 is a block diagram of the circuit used in the experiment, FIG. 14 is an experimental waveform obtained by removing the active capacitor from the circuit of FIG. 13, and FIG. 15 is obtained by the circuit of FIG. This is an experimental waveform. As can be seen by comparing FIG. 14 and FIG. 15, it can be seen that by connecting the active capacitor 21, the number of current conductions in one cycle is increased, and the load current Iload is also increased, and an active capacitor is provided. It was confirmed that the transmission efficiency was improved.

  Table 1 shows circuit parameters in this experiment.

  As described above, in the contactless power supply system 1 according to the present invention, a circuit using the one-pulse active capacitor 21 is used as a new electric field coupling contactless power supply method. By connecting such an active capacitor 21, the current passing time in the discontinuous mode is increased, the load current is increased, and the effect of improving the transmission efficiency can be exhibited. As described above, it was confirmed that the load current increased by √2 times (about 1.4 times), and the improvement in transmission efficiency was confirmed. The circuit having the active capacitor 21 constituting the present invention can be constituted by a simple circuit having only a capacitor in the DC portion, and the control is also very simple control that gives a switching pattern whose phase is shifted by 90 °. It was possible to improve the transmission efficiency. Such a circuit can be said to be a circuit that can be easily integrated.

1, 1A, 1B, 1C, 1D Electric field coupling non-contact power feeding system 2 Power feeding area 3 Powered area 4 Power feeding part 5 Powered part 6 Boundary part 8 Load 11 Power supply part 21 Active capacitor 24 Capacitor 25 Active capacitor control part 31 1st Coupling capacitor 32 Second coupling capacitor 33 First power transmission electrode 34 Second power transmission electrode 35 First power reception electrode 36 Second power reception electrode

V acc inverter voltage V1 combined voltage of the voltage Vs power supply unit in the capacitance Cs of the capacitance C which constitute the inverter voltage Vcs active capacitor of active capacitor Icj active capacitor current

DESCRIPTION OF SYMBOLS 101 Contactless electric power feeding system which does not connect an active capacitor 102 Electric power feeding area | region 103 Power feeding area | region 104 Electric power feeding part 105 Power feeding part 106 Boundary part 108 Load 111 Power supply part 112 DC power supply 131,132 Junction capacitor

Claims (4)

A power supply unit arranged in the power supply region, and a power supply unit arranged in the power supply region to supply power to the load,
The power supply unit is disposed on the power supply region side of a power supply unit, an active capacitor, an active capacitor control unit that controls the active capacitor, and a boundary between the power supply region and the power supply region, and the power supply unit A first power transmission electrode and a second power transmission electrode that receive power from
The power-supplied portion includes a first power receiving electrode and a second power receiving electrode that are arranged to face each other in a non-contact manner with respect to the first power transmitting electrode and the second power transmitting electrode with the boundary portion interposed therebetween,
A first coupling capacitor is configured by the first power transmission electrode and any one of the first power reception electrode and the second power reception electrode arranged to face the first power transmission electrode, the second power transmission electrode, and the second power transmission electrode. A second coupling capacitor is configured with either one of the first power receiving electrode and the second power receiving electrode disposed opposite to the power transmitting electrode,
The active capacitor, the first coupling capacitor and the are connected in series to either of the second coupling capacitor, a square of the by active capacitor control section of the square-wave voltage V acc of the active capacitor phase the power supply unit An electric field coupling contactless power feeding system, wherein the active capacitor is controlled to be delayed from the phase of the wave voltage Vs, and the active capacitor operates as a negative capacitance.   The electric field coupling contactless power feeding system according to claim 1, wherein the active capacitor includes a capacitor.   The electric field coupling non-contact electric power feeding system of Claim 1 with which the said active capacitor is provided with DC power supply. The electric field coupling non-contact electric power feeding system of any one of Claims 1-3 which connects the said active capacitor 1 or 2 or more in series.

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