JP6679040B2 - Non-contact power feeding system, power transmission unit and non-contact power feeding method - Google Patents

Description

  The present invention relates to a non-contact power feeding system, a power transmission unit used in this non-contact power feeding system, and a non-contact power feeding method using these, and in particular, non-contact (wireless) power supply to a power receiving unit that drives an AC load by an electromagnetic induction method. The present invention relates to a non-contact power feeding system, a power transmission unit, and a non-contact power feeding method for transmitting.

For example, in the technical field of power supply to a carrier or the like of an automated warehouse, non-contact power is further supplied from a first power supply line to a second power supply line, and DC power is output from the second power supply line. A power transmission unit is proposed (see Patent Document 1).
In addition, there is also a charging device that outputs direct-current power to contactlessly charge a battery (rechargeable battery) that is a power source of an AGV (Automated Guided Vehicle) used for transporting parts in a manufacturing plant. It has been proposed (see Patent Document 2). However, a contactless power supply system that wirelessly transmits electric power to an AC output power receiving unit that drives an AC load is not known.

JP, 2006-211183, A JP, 2008-137451, A

  The present invention has been made in view of the above problems, and transmits high-frequency power to a power receiving unit that drives an AC load in a non-contact (wireless) manner, and transmits power even if the impedance of the AC load fluctuates rapidly. An object of the present invention is to provide a contactless power supply system capable of achieving a good balance between protection of circuit elements of the unit and high transmission efficiency, a power transmission unit used in this contactless power supply system, and a contactless power supply method using the same. .

  A first aspect of the present invention includes (a) a power receiving unit that has a power receiving coil, converts power input from the power receiving coil to generate an alternating current, and supplies the alternating current to an alternating current load; b) A power supply coil that supplies power of a higher frequency than an alternating current in a contactless manner, a drive circuit that includes a switching element and supplies a current to the power supply coil, a power monitoring device that measures the power supplied to the power supply coil, and a gate of the switching element. A drive signal generation circuit that supplies a drive signal, and an output from the power monitoring device are used to search for an optimum frequency on the transmission efficiency-frequency curve, and the frequency of the drive signal is determined by this optimum frequency. A gist of the present invention is a contactless power feeding system including a power transmission unit having a frequency control circuit for controlling.

  A second aspect of the present invention has a power receiving coil, converts electric power input from the power receiving coil to generate an alternating current, and supplies the alternating current to an alternating current load. Also relates to a power transmission unit that supplies high-frequency power in a contactless manner. That is, the power transmission unit according to the second aspect of the present invention includes: (a) a power feeding coil tightly coupled to the power receiving coil; (b) a drive circuit that includes a switching element and applies a high-frequency current to the power feeding coil; A power monitoring device that measures the power supplied to the power feeding coil, (d) a drive signal generation circuit that supplies a drive signal to the gate of the switching element, and (e) transmission efficiency-frequency using the output from the power monitoring device. The optimum frequency is searched for on the curve, the frequency of the drive signal is determined by the optimum frequency, and a frequency control circuit for controlling the drive signal generation circuit is provided.

  A third aspect of the present invention has a power receiving coil, converts the electric power input from the power receiving coil to generate an alternating current, and supplies the alternating current to an alternating current load. The present invention relates to a non-contact power feeding method of non-contactly supplying power of a higher frequency than an alternating current from a power feeding coil. That is, in the contactless power feeding method according to the third aspect of the present invention, (a) a current having a higher frequency than an alternating current is passed from the driving circuit of the power feeding coil to the power feeding coil, and the power supplied to the power feeding coil is measured. And (b) searching the optimum frequency of the drive signal input to the gate of the switching element included in the drive circuit on the transmission efficiency-frequency curve using the measured power, and (c) Generating a drive signal at an optimum frequency to drive the switching element.

  ADVANTAGE OF THE INVENTION According to the non-contact electric power feeding system which concerns on this invention, the power transmission unit used for this non-contact electric power feeding system, and the non-contact electric power feeding method using these, even if the impedance of an alternating current load changes rapidly, the circuit element of a power transmission unit is protected. And high transmission efficiency can be achieved in a well-balanced manner.

It is a circuit diagram including a block diagram which explains typically the outline of the power transmission unit concerning an embodiment of the invention. FIG. 3 is a block diagram schematically illustrating an outline of a power receiving unit used in combination with the power transmitting unit according to the embodiment of the present invention. It is a block diagram explaining the structure of the frequency control circuit in the power transmission unit which concerns on embodiment of this invention. It is a flow chart explaining the whole flow of control processing in a power transmission unit concerning an embodiment of the invention. It is a flow chart explaining processing of transmission power control processing mode in a power transmission unit concerning an embodiment of the invention. It is a graph figure explaining the process which changes the transmission efficiency frequency performed in the process of the transmission power control process mode in the power transmission unit which concerns on embodiment of this invention. It is a flow chart explaining processing of protection frequency calculation mode in a power transmission unit concerning an embodiment of the invention. It is a graph figure explaining the process which changes the protection frequency performed in the process of the protection frequency calculation mode in the power transmission unit which concerns on embodiment of this invention. 9A is a waveform diagram of the voltage measured at both ends of the power feeding coil in the non-contact power feeding system according to the embodiment of the present invention, and FIG. 9B is the non-contact according to the embodiment of the present invention. It is a wave form diagram of the voltage measured by the both ends of the receiving coil in a power feeding system. It is a circuit diagram including a block diagram which explains typically the outline of the 1st modification of the power transmission unit concerning the embodiment of the invention. FIG. 9 is a circuit diagram including a block diagram for schematically explaining the outline of a second modification of the power transmission unit according to the embodiment of the present invention. It is a circuit diagram including a block diagram which explains typically the outline of the 3rd modification of the power transmission unit concerning the embodiment of the invention.

  Next, an embodiment of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and the relationship between the thickness and the plane dimension, the ratio of the thickness of each member, and the like are different from the actual ones. Therefore, the specific thickness and dimensions should be determined in consideration of the following description. In addition, it is needless to say that dimensional relationships and ratios are different between drawings.

  Further, the embodiments described below exemplify an apparatus and a method for embodying the technical idea of the present invention, and the technical idea of the present invention includes the material, shape, structure, The layout is not specified as below. Various changes can be added to the technical idea of the present invention within the technical scope defined by the claims described in the claims. Furthermore, the directions of “left and right” and “up and down” in the following description are merely definitions for convenience of description, and do not limit the technical idea of the present invention. Therefore, for example, if the paper surface is rotated 90 degrees, "left and right" and "up and down" are read interchangeably, and if the paper surface is rotated 180 degrees, "left" becomes "right" and "right" becomes "left". Of course,

<Structure of power transmission unit and contactless power supply system>
As shown in FIG. 1, a contactless power feeding system according to an embodiment of the present invention includes a power transmission unit 1a having a power feeding coil L1 and a power receiving coil L2, and an AC load such as an inductive load X for supplying power at a commercial frequency. And a power receiving unit 2 for outputting to. High frequency power is supplied from the power feeding coil L1 to the power receiving coil L2 in a non-contact manner. Considering transmission efficiency, the frequency of the high frequency is preferably 10 kHz or higher, more preferably 30 kHz or higher, and further preferably about 450 kHz to 100 kHz. The high frequency may be 100 kHz or higher. The frequency of the alternating current output by the power receiving unit 2 is not limited to the commercial frequency, and alternating current outputs of various frequencies lower than the high frequency transmitted from the power feeding coil L1 to the power receiving coil L2 may be output.

  The power feeding coil L1 is housed in a storage box, which is formed in a spiral disc shape and is made of a dielectric material such as plastic (not shown). In the vicinity of the power feeding coil L1 housed in the storage box, a spiral disk-shaped power receiving coil L2 is arranged in non-contact with the power feeding coil L1 so as to face the power feeding coil L1 with a space d therebetween. The power receiving coil L2 is also housed in a storage box made of a dielectric material.

  The distance d between the power feeding coil L1 and the power receiving coil L2 is arranged in the vicinity of about 0.8 cm to 1.2 cm, and the power feeding coil L1 and the power receiving coil L2 are tightly coupled. With the high frequency current I flowing through the power feeding coil L1 as the primary current, electromotive force is generated in the power receiving coil L2 by electromagnetic induction, and high frequency power is transmitted in a contactless manner. The high-frequency power supplied to the power receiving coil L2 causes the power receiving unit 2 to output power at a commercial frequency, and the inductive load X is driven.

In the configuration illustrated in FIG. 1, the power transmission unit 1a according to the embodiment of the present invention is a drive circuit configured by circuit elements such as a high-side switching element Q _H1 and a low-side switching element Q _{L1 and} passing a current through the power feeding coil L1. 14, a power monitoring device 16 that measures the power supplied to the power feeding coil L1, a drive signal generation circuit 13 that supplies a drive signal to the gates of the high-side switching element Q _H1 and the low-side switching element Q _L1 , and a drive circuit. 14 and a rectifying circuit 12 that supplies a DC power supply voltage to the drive signal generating circuit 13, and a frequency control circuit that determines the frequency of the drive signal generating circuit 13 using the output of the power monitoring device 16 and controls the drive signal generating circuit 13. 17 is provided.

As illustrated in FIG. 1, the circuit elements of the power transmission unit 1a, a high-side switching element Q _H1 and low-side switching element Q _L1 of the drive circuit 14, composed of, for example, an insulated gate field effect transistor (MOSFET), etc. However, the structure is not limited to the MOSFET, and can be constituted by a more general MISFET, IGBT, static induction transistor (SIT), static induction thyristor, or the like. In FIG. 1, the high-side switching element Q _H1 is a p-channel MOSFET and the low-side switching element Q _L1 is an n-channel MOSFET. The drain of the high side switching element Q _{H1 and} the drain of the low side switching element Q _L1 are connected to each other to form an inverter circuit.

The frequency control circuit 17 searches for the optimum frequency on the transmission efficiency-frequency curve (η- _fe curve) using the output from the power monitoring device 16, determines the frequency of the drive signal by this optimum frequency, and determines the drive signal. The generation circuit 13 is controlled. The rectifier circuit 12 is connected to an external power source via the connection terminal 11. The connection terminal 11 is supplied with commercial AC power of 50 Hz or 60 Hz at a voltage of 100 V or 200 V as a power supply.

  Further, as shown in FIG. 2, the power receiving device 20 including the rectifier circuit 22, the drive signal generation circuit 23, and the drive circuit 24 is connected to the power receiving coil L2. Power reception coil L2 and power reception device 20 configure power reception unit 2 that forms a pair with power transmission unit 1a according to the embodiment of the present invention. AC power is output from the drive circuit 24 of the power receiving unit 2, an inductive load X is connected to the drive circuit 24, and an AC current flows through the inductive load X. Since the power receiving unit 2 side is a circuit having a commercial frequency, di / dt is small even when impedance change occurs in the inductive load X, and experience shows that the switching element forming the drive circuit 24 is hardly destroyed. .

In the rectifier circuit 12 of the power transmission unit 1a, a first diode D1 and a second diode D2 connected in series, and a first capacitor C1 and a second capacitor C2 connected in series are connected in parallel with each other. Is configured.
Of the two terminals extending from the connection terminal 11, one terminal is grounded and the other terminal is connected to an intermediate point between the first diode D1 and the second diode D2. The midpoint between the first capacitor C1 and the second capacitor C2 is grounded. The rectifier circuit 12 converts the high frequency voltage V input via the connection terminal 11 into a DC voltage of, for example, about 110 V and outputs the DC voltage to the drive circuit 14.

The source of the high side switching element Q _H1 is connected to an intermediate point between the first diode D1 and the first capacitor C1 of the rectifier circuit 12. The source of the low-side switching element _QL1 is connected to the intermediate point between the second diode D2 and the second capacitor C2 of the rectifier circuit 12.
The drive signal generation circuit 13 is connected to the gates of the high-side switching element Q _H1 and the low-side switching element Q _L1 of the drive circuit 14, respectively. Although not shown, the drive signal generation circuit 13 is configured to generate a drive signal using the DC voltage output from the rectifier circuit 12.

The drive signal generation circuit 13 generates a drive signal that is a high-frequency signal having a peak voltage of about 15 V, for example, and outputs the generated drive signal to the gates of the high-side switching element Q _H1 and the low-side switching element Q _L1. .
By inputting the drive signal from the drive signal generation circuit 13 to the drive circuit 14, ON / OFF of each gate of the high side switching element Q _H1 and the low side switching element Q _L1 forming the drive circuit 14 is switched, A high frequency rectangular pulse voltage as shown in FIG. 9A is output from the midpoint between the drain of the first p-type switching element PMOS1 and the source of the first n-type switching element NMOS1.

One end of the feeding coil L1 is connected to an intermediate point between the drain of the high-side switching element Q _{H1 and} the drain of the low-side switching element _QL1 to form an output node. The other end of the power feeding coil L1 is grounded. Therefore the high frequency voltage V is outputted from the midpoint of the drain of the drain and low-side switching element Q _L1 of the high-side switching element Q _H1 the feeding coil L1, the high-frequency current I flows in the feeding coil L1.

The power monitoring device 16 measures the high frequency voltage V input to the power feeding coil L1 and the high frequency current I flowing in the power feeding coil L1 with time, and the measured values of the high frequency voltage V and the high frequency current I are sent to the frequency control circuit 17. Output.
As shown in FIG. 3, the frequency control circuit 17 includes an efficiency-based frequency calculation unit 17a, an output power acquisition unit 17b, a transmission power determination unit 17c, a protection frequency calculation unit 17d, an optimum frequency setting unit 17e, and a voltage comparison unit 17f. . The frequency control circuit 17 can be configured by a microprocessor having a CPU, a RAM, a ROM memory, an I / O circuit, and the like.

The efficiency-dependent frequency calculation unit 17a, on the η- _fe curve obtained in advance as shown in FIG. 6, from the point of efficiency, the first value of the efficiency-dependent frequency f _e in the processing of the transmission power control mode described later. And the efficiency-dependent frequency f _e is changed according to the magnitude of the high-frequency voltage V.
The output power acquisition unit 17b obtains the product of the values of the high frequency voltage V and the high frequency current I input from the power monitoring device 16 to calculate and acquire the primary power P in the power feeding coil L1. The transmission power determination unit 17c determines whether or not the transmission power increases due to the changed efficiency-dependent frequency _fe in the processing of the transmission power control processing mode.

The protection frequency calculation unit 17d uses the calculated primary electric power P to change the impedance of the inductive load X on the power receiving unit 2 side to generate spike noise as shown in FIG. 9A. The protection frequency f _p , which is a frequency for outputting a safe and stable electric power to the power feeding coil L1 to protect the driving circuit 14 from being destroyed by being reversely flowed from the side and being superimposed, Calculate according to size.

The optimum frequency setting unit 17e sets and sets the optimum frequency f _v , which is a frequency that balances the improvement of the transmission efficiency and the protection of the drive circuit 14 in a well-balanced manner, using the efficiency-dependent frequency f _e and the protection frequency f _p . The optimum frequency f _v is output to the drive signal generation circuit 13. The drive signal generation circuit 13 generates the input optimum frequency f _v as a drive signal and outputs it to the gates of the high side switching element Q _H1 and the low side switching element Q _L1 of the drive circuit 14, respectively.

Further, a storage device (not shown) is connected to the frequency control circuit 17. In this storage device, the data of the η- _fe curve as shown in FIG. 6 which is obtained in advance and the initial value f ₀ set to the efficiency-dependent frequency f _e are stored. The initial value f ₀ is set to a value calculated by measurement, simulation or the like in consideration of surely preventing the drive circuit 14 from being broken according to the inductive load X.

Further, in this storage device, the data of the breakdown voltage-frequency curve ( _Vfv curve) as shown in FIG. 8 which is obtained in advance in accordance with the impedance characteristic of the inductive load X regarding the output voltage and the protection frequency is also stored . It is stored. Incidentally, _{eta-f e} curve and _{V-f v} curve can also create and store in real time situ (in-situ) during the feeding process.
The storage device also stores the amount of change Δf _e set for use in the process of changing the value of the efficiency-based frequency f _e . Further, in order to prevent the sudden load fluctuation on the inductive load side from destroying the drive circuit 14 by a large spike voltage generated in the power feeding coil L1 as shown in FIG. The breakdown threshold voltage Vth set in accordance with the impedance characteristic of is stored.

For example, when the inductive load X is a motor of a conveyor used for transferring components mounted in the AGV, in order to drive the inductive load X, for example, a commercial power supply of AC100V is used to transmit power to the primary side. High-frequency electric power is supplied from the unit 1a to the secondary power receiving unit 2 connected to the motor by an electromagnetic induction method.
However, for example, in the case of non-contact power supply to an AGV battery, on the power receiving unit 2 side, when the motor as the inductive load X is started or when the conveyor is temporarily stopped, several times the rated load is momentarily applied. The above large current is required. When the frequency of the drive signal that drives the drive circuit 14 of the power transmission unit 1a is changed so that a large voltage is output from the primary side to cover this large current, a high-frequency power is different from the commercial frequency on the secondary side. Since the influence of noise becomes significantly large on the primary side that handles the above, the high-side switching element Q _H1 and the low-side switching element QL _{1 of} the drive circuit 14 cannot withstand and burn out.

In particular, when the load connected to the power receiving unit 2 is an inductive load (inductance load) X such as a motor, a sharp spike-like voltage as shown in FIG. The high-side switching element Q _H1 and the low-side switching element Q _{L1 of} the drive circuit 14 are more likely to be destroyed and more likely to be destroyed. However, if the frequency of the drive signal is changed so as to protect the drive circuit 14, the transmission efficiency to the power receiving unit 2 side may be significantly reduced. That is, when power is supplied to the inductive load X that fluctuates abruptly in a non-contact manner, in the drive signal that drives the drive circuit 14 on the power transmission unit 1a side, the efficiency-based frequency _fe that leads to the maximum transmission efficiency and the drive circuit 14 It does not always match the protection frequency fp set to protect the high-side switching element Q _H1 and the low-side switching element Q _L1 from destruction. The frequency control circuit 17 solves this problem by using the flowchart shown in FIG.

<Operation of power transmission unit>
In the power transmission unit 1a according to the embodiment of the present invention, as shown in FIG. 4, in step S1, the frequency control circuit 17 determines whether or not a constant value is set for the protection frequency f _p .
When a fixed value is not set for the protection frequency f _p , for example, the first process after the start of power supply to the inductive load X and no value is input as the protection frequency f _p , Control goes to step S2. On the other hand, when a constant value is set for the protection frequency f _p , for example, when the process of the protection frequency calculation mode described later has already been executed and the value of the constant protection frequency f _p is set, Go to S3.

Next, in step S2, the efficiency-dependent frequency calculation unit 17a of the frequency control circuit 17 sets the efficiency-dependent frequency f _e to the value of the initial value f ₀ stored in the storage device, and the process proceeds to step S4. On the other hand, in step S3, the efficiency-dependent frequency calculation unit 17a sets the value of the protection frequency f _p that has already been set in the efficiency-dependent frequency f _e , and the process proceeds to step S4.

(Transmission power control mode)
Next, in step S4, the frequency control circuit 17 executes processing in the transmission power control mode. Specifically, as shown in FIG. 5, first, in step S41, the output power acquisition unit 17b of the frequency control circuit 17 includes a high frequency voltage V and a high frequency current I output from the drive circuit 14 to the power feeding coil L1. Next power is acquired via the power monitoring device 16.

Next, in step S42, the efficiency-dependent frequency calculation unit 17a of the frequency control circuit 17 changes the value of the efficiency-dependent frequency _fe in accordance with the acquired primary power on the η- _fe curve shown in FIG. And when the transmission efficiency eta obtained does not match the maximum transmission efficiency eta _01, as transmission efficiency eta approaches the maximum transmission efficiency eta _01, slight change that is set to the value of the current efficiency relies frequency f _{e (i)} The amount Δf _e is added or subtracted to change the current value of the efficiency dependent frequency f _{e (i)} .

In FIG. 6, since the current efficiency-dependent frequency f _e is lower than the maximum efficiency frequency f _e01 corresponding to the maximum transmission efficiency η ₀₁ , the value of the transmission efficiency η increases toward the maximum efficiency frequency f _e01. , A state in which a change amount Δf _e is added to the current efficiency-dependent frequency f _{e (i)} to change the frequency is illustrated. On the other hand, when the current efficiency-dependent frequency f _{e (i)} is higher than the maximum efficiency frequency f _e01 corresponding to the maximum transmission efficiency η ₀₁ , the value of the transmission efficiency η decreases toward the maximum efficiency frequency f _e01. In addition, the change amount Δf _e is subtracted from the current efficiency-based frequency f _{e (i)} to change the frequency.

That is, the process of changing the value of the efficiency-dependent frequency f _{e at} the i-th time is generalized by Expression (1), assuming that the value of the change amount Δf _e can be set to both positive and negative values:

_{f e (i + 1) =} f e (i) + Δf e ......... (1)

Next, in step S43, the output power acquisition unit 17b acquires again the primary power including the high frequency voltage V and the high frequency current I output to the power feeding coil L1.

Next, in step S44, the transmission power determination unit 17c of the frequency control circuit 17 increases the primary power obtained in step S43 from the primary power obtained immediately before changing the value of the i-th efficiency-dependent frequency _fe. Then, it is compared whether or not the transmission efficiency η is improved.
When the primary power increases, it is determined that the change in the value of the efficiency-dependent frequency f _{e (i)} at the i-th time immediately before is appropriate, the process proceeds to step S42, and the subsequent processes are repeated to further improve the transmission efficiency. Improve η.

On the other hand, if it does not increase, it is determined that the change in the value of the efficiency-dependent frequency f _{e (i)} at the i-th time immediately before is inappropriate and the transmission efficiency η does not increase, and then the (i-1) -th time It is determined that the change in the value of the efficiency-based frequency _fe is appropriate, and the process proceeds to step S45.
Next, in step S45, the optimum frequency setting unit 17e of the frequency control circuit 17 sets the value of the efficiency-dependent frequency f _{e (i-1) as} the current value of the optimum frequency f _{v (j)} . Then, the processing of the transmission power control mode is ended, and the process proceeds to step S5 in FIG.

Next, in step S5, the frequency control circuit 17 determines whether or not to perform the process in the protection frequency calculation mode. The process of the protection frequency calculation mode may be executed along with the process of the transmission power control mode every time the process of the transmission power control mode is executed in step S4, or the process of the transmission power control mode is executed a predetermined number of times. After that, it may be executed at regular intervals such that it is executed once. Alternatively, the administrator of the contactless power supply system may be configured to execute the operation at a desired timing.
Therefore, when the process of the protection frequency calculation mode is not executed immediately but is executed later, the process proceeds to step S4 and the process of the transmission power control mode is executed again. On the other hand, if the protection frequency calculation mode process is to be executed immediately, the process proceeds to step S6 to start the protection frequency calculation mode process.

(Protection frequency calculation mode)
First, in step S51 of FIG. 7, the protection frequency calculation unit 17d of the frequency control circuit 17 sets the value of the protection frequency f _{p as} the value of the current optimum frequency f _{v (j)} set in the processing of the transmission power control mode. Enter.
Next, in step S52, the output power acquisition unit 17b acquires the primary power including the high frequency voltage V and the high frequency current I output to the power feeding coil L1.

Next, in step S53, the voltage comparison unit 17f compares the current value of the high frequency voltage V output to the power feeding coil L1 with the value of the breakdown threshold voltage V _th stored in the storage device. When it is determined that the high frequency voltage V is equal to or higher than the breakdown threshold voltage V _th , the process proceeds to step S54. On the other hand, when it is determined that the high frequency voltage V is _lower than the breakdown threshold voltage V _th , the process of the protection frequency calculation mode is ended and the process proceeds to step S7 in FIG.

When it is determined in the preceding step S53 that the high frequency voltage V is equal to or higher than the breakdown threshold voltage V _th , the protection frequency calculation unit 17d of the frequency control circuit 17 changes the value of the protection frequency f _p in step S54. Specifically, by using a V-f _p curve as shown in FIG. 8, the high frequency voltage V corresponding to the current value f _{v (j)} of the protection frequency f _p approaches the minimum voltage V _p02. , The minute change amount Δf _p set to the current value of the protection frequency f _p is added or subtracted to change the value of the protection frequency f _p .

That is, the process of changing the value of the protection frequency f _p is generalized to Expression (2), assuming that the value of the change amount Δf _p can be set to both positive and negative values:

f _p = f _{v (j)} + Δf _p (2)

There are various types of relationships between the high-frequency voltage V that can protect the high-side switching element Q _H1 and the low-side switching element _QL1 from destruction and the protection frequency f _p , depending on the impedance characteristics of the inductive load X. In the figure 8, the pattern A high-frequency voltage V is gradually reduced according to the protection frequency f _p is increased, the pattern B a high frequency voltage V is gradually increased according to the protection frequency f _p is high, according to the protection frequency f _p becomes higher There are illustrated three main patterns, that is, the pattern C in which the high frequency voltage V gradually decreases to the minimum voltage V _p02 and then gradually increases. In the following operation of the power transmission unit according to the embodiment of the present invention, the case of pattern C will be used for convenience of description.

As shown in FIG. 8, the current protection frequency _{f p} values _{f v (j)} is higher than the maximum protection frequency _{f p02,} and higher than the breakdown threshold voltage _{V th.} Therefore, as current protection frequency _{f p} values _{f v (j)} is less than breakdown threshold voltage _{V th,} by subtracting the amount of change Delta] f _p from the current protected frequency _{f p} values _{f v (j),} the maximum The value is changed so as to decrease toward the protection frequency f _p02 . The change amount Δf _p can be calculated using a value obtained by subtracting the breakdown threshold voltage V _th from the current value f _{v (j)} of the protection frequency f _p .

On the other hand, in the pattern C, when the value f _{v (j)} of the current protection frequency f _p is lower than the maximum protection frequency f _p02 and lower than the breakdown threshold voltage V _th , the current protection frequency f _p as the value _{f v (j)} is less than breakdown threshold voltage _{V th,} by adding the amount of change Delta] f _p of the current protection frequency _{f p} values _{f v (j),} the value toward the maximum protection frequency _{f p02} Change to increase. The change amount Δf _{p at} this time can be calculated using a value obtained by subtracting the value f _{v (j)} of the current protection frequency f _p from the breakdown threshold voltage V _th .

Then, after updating the value of the protection frequency f _p , the process of the protection frequency calculation mode is ended, and the process proceeds to step S7 in FIG. Even in the case of the other patterns A and B, as in the case of the above-described pattern C, the current value f _{v (j)} of the protection frequency f _p is set to be less than the breakdown threshold voltage V _th. , May be changed appropriately.
Next, in step S7, the frequency control circuit 17 inputs and sets the updated value of the protection frequency f _p as the final optimum frequency f _vlast of the drive signal generated by the drive signal generation circuit 13.

Next, in step S8, the frequency control circuit 17 determines whether or not to execute the processing in the transmission power control mode. When the process of the transmission power control mode is executed, the process _proceeds to step S1 and the subsequent processes are appropriately repeated to update the optimum frequency f _vlast . On the other hand, when the process of the transmission power control mode is not executed, the series of processes of the power transmission unit 1a according to the embodiment of the present invention is ended. Then, the frequency control circuit 17 outputs the optimum frequency f _vlast to the drive signal generation circuit 13. By sequentially performing this series of processes during power feeding, the high frequency power transmitted from the power feeding coil L1 to the power receiving coil L2 is optimized according to the load fluctuation on the output side of the power receiving unit 2.

According to the contactless power supply system of the embodiment of the present invention, the process of the transmission power control mode and the process of the protection frequency calculation mode are appropriately combined, and the optimum frequency is output according to the state of the high frequency voltage output to the power supply coil L1. f _v is sequentially changed and updated, the driving circuit 14 is driven at the updated optimum frequency f _vlast , and the process of changing the high frequency power output to the power feeding coil L1 is repeated.

Therefore, while the power receiving unit 2 is supplying electric power of the commercial frequency to the inductive load X such as a motor, the impedance of the load such as starting and stopping of the inductive load X, or the load due to the presence or absence of a load in the AGV or the like. Even if the impedance variation occurs and the spike-shaped voltage flows backward and is superimposed on the high frequency output voltage to the power feeding coil L1 as shown in FIG. 9A, the frequency control is performed. Since the circuit 17 changes the optimum frequency f _v to adjust the output voltage and changes the frequency value so that the transmission efficiency η becomes optimum, the effect of the spike voltage due to the back electromotive force can be quickly reduced. Therefore, it is possible to balance the circuit protection of the power transmission unit 1a and the high transmission efficiency and supply power.

That is, in the contactless power supply system according to the embodiment of the present invention, power transmission unit 1a can stably transfer a large amount of high-frequency power in a contactless manner even if the impedance of the load of inductive load X changes.
FIG. 9A shows an oscilloscope when a fan is used as the inductive load X, the optimum frequency f _v is changed while varying the AC load by the fan, and the inductive load X is supplied with the commercial frequency. It is a voltage waveform of the both ends of the feeding coil L1 observed in FIG. Further, FIG. 9B is a voltage waveform across the power receiving coil L2 on the power receiving unit 2 side. A commercial power source of AC 100 V and 50 Hz was supplied to the connection terminal 11, and a high frequency voltage V of about 80 V was output to both ends of the power feeding coil L1.

  As shown in FIG. 9A, in the waveform of the power feeding coil L1 that outputs a high frequency, a large noise of di / dt caused by the impedance variation of the load is multiply reflected and a plurality of spike components are superimposed. As shown in FIG. 9B, the influence of noise on the waveform of the power receiving coil L2 is relatively small. Therefore, rather than matching the characteristic impedance of the transmission line when the inductive load X is seen from the power receiving coil L2, the power feeding coil L1 From the figure, it can be seen that the mismatch of the characteristic impedance of the transmission line when looking at the power receiving coil L2 is larger.

Since the power receiving unit 2 side has a commercial frequency, di / dt is small, the characteristic impedance matching of the transmission line when the inductive load X is seen from the power receiving coil L2 is relatively good, and the waveform of the power receiving coil L2 has a reverse current component. It can be seen that the effect of noise (reflection component) is relatively small. Then, the optimum frequency f _v of the drive signal in the measurement of FIGS. 9A and 9B was about 45 kHz. On the other hand, when the optimum frequency f _v is changed from 45 kHz, spike noise superimposed on the high-frequency waveform of the feeding coil L1 sharply increases, and the high-side switching element Q _H1 and the low-side switching element Q of the drive circuit 14 are increased. _L1 is destroyed. As already described, since the power receiving unit 2 is a circuit having a commercial frequency, di / dt is small even if impedance change occurs in the inductive load X, and experience shows that the switching element of the drive circuit 24 is There is almost no destruction.

(Other embodiments)
Although the present invention has been described by the embodiments disclosed above, it should not be understood that the descriptions and drawings forming a part of this disclosure limit the present invention. From this disclosure, it should be considered that various alternative embodiments, examples, and operation techniques will be apparent to those skilled in the art.

(First modification)
In the power transmission unit 1a shown in FIG. 1, the drive circuit 14 is configured by using the p-channel MOSFET as the high-side switching element Q _H1 and the n-channel MOSFET as the low-side switching element QL ₁ , but the present invention is not limited to this and, for example, as shown in FIG. 10, it is also possible to configure the high-side switching element _{Q H2} and low-side switching element _{Q L2} using only n-channel MOSFET.

Drive circuit 14a in the power transmission unit 1b according to the first modification, an inverter circuit is configured by connecting the high side switching element Q _H2 and low-side switching element Q _L2.
Further, the drive signal generation circuit 13 switches ON / OFF of the gates of the high-side switching element Q _H2 and the low-side switching element _QL2 , respectively, and outputs the high frequency voltage V to the power feeding coil L1. A drive signal is output to the respective gates of Q _H2 and the low side switching element Q _L2 .

  The structure and operation of the power transmission unit 1b according to the first modification other than the drive circuit 14a are equivalent to those of the power transmission unit 1a illustrated in FIG. 1 having the same or similar names and reference numerals, and thus duplicated. The description is omitted. According to the power transmission unit 1b according to the first modified example, similarly to the power transmission unit 1a according to the embodiment of the present invention, even if the impedance of the AC load suddenly changes, the protection of the drive circuit 14a on the power transmission side is high. It is possible to achieve a good balance with transmission efficiency.

(Second modified example)
Further, for example, as shown in FIG. 11, the drive circuit 14b can be configured by using two p-channel MOSFETs and two n-channel MOSFETs. The power transmission unit according to the second modification is different from the power transmission unit 1a according to the embodiment of the present invention shown in FIG. 1 in the structures of the rectifier circuit 12 and the drive circuit 14b.

Driving circuit 14b in the power transmission unit according to the second modification is constructed by connecting the high side switching element _{Q H3a,} the high-side switching element _{Q H3b,} the low-side switching element _{Q L3a} and low-side switching element _{Q L3b} the H-bridge has been that the high side switching element _{Q H3a} and high side switching elements _{Q H3b} a p-channel MOSFET, also low-side switching element _{Q L3a} and low-side switching element _{Q L3b} is an n-channel MOSFET.

The feeding coil L1 is connected to the position of the bridge of the drive circuit 14b, and the high frequency voltage V is input from the drive circuit 14b. The power monitoring device 16 is connected to the power feeding coil L1. Note that, in FIG. 11, the power receiving device and the inductive load connected to the power receiving coil L2 are omitted for convenience of space.
Further, in the power transmission unit according to the second modification, the rectifier circuit 12 includes a first diode D1 and a second diode D2 connected in series, and a third diode D3 and a fourth diode connected in series. D4 and the third capacitor C3 are connected in parallel with each other.

  One of the two terminals extending from the connection terminal 11 is connected to the intermediate point between the first diode D1 and the second diode D2. The other terminal is connected to the intermediate point between the third diode D3 and the fourth diode D4. The rectifier circuit 12 converts the high frequency voltage V input via the connection terminal 11 into a DC voltage and outputs the DC voltage to the drive circuit 14b.

Further, the power transmission unit according to the second modified example is provided with the first drive signal generation circuit 13a and the second drive signal generation circuit 13b. First driving signal generating circuit 13a is connected to the gates of the high side switching element Q _H3a and low-side switching element Q _L3a forming one series circuit of the H-bridge. The second drive signal generation circuit 13b is connected to the gates of the high side switching element Q _H3b and low-side switching element Q _L3b constituting the other series circuit of the H-bridge.

First driving signal generating circuit 13a and the second drive signal generation circuit 13b, the high-side switching element _{Q H3a,} the high-side switching element _{Q H3b,} low-side switching element _{Q L3a} and respective gates of the low-side switching element _{Q L3b} Of the high side switching element Q _H3a , the high side switching element Q _H3b , the low side switching element Q _L3a and the low side switching element Q _L3b so that the high frequency voltage V is output to the power feeding coil L1. The drive signal is output to the gate of.

The first drive signal generation circuit 13a and the second drive signal generation circuit 13b are both connected to the frequency control circuit 17, and the frequency control circuit 17 includes the first drive signal generation circuit 13a and the second drive signal generation circuit. The set optimum frequency f _v is output to each of 13b. The first drive signal generation circuit 13a and the second drive signal generation circuit 13b generate each of the input optimum frequencies f _v as drive signals and output them to the drive circuit 14b.

  The structure and operation of the power transmission unit according to the second modification other than the drive circuit 14b are equivalent to those of the power transmission units 1a illustrated in FIGS. 1 and 10 and having the same or similar names and reference numerals. Therefore, duplicate description will be omitted. According to the power transmission unit according to the second modified example, similarly to the power transmission unit 1a according to the embodiment of the present invention, even if the impedance of the AC load changes abruptly, the drive circuit 14b on the power transmission side is protected and the transmission is high. It is possible to achieve a good balance between efficiency and efficiency.

(Third modification)
Further, for example, as shown in FIG. 12, the drive circuit 14c can be configured by using only four n-channel MOSFETs. That is, the power transmission unit according to the third modification is different from the power transmission unit 1a according to the embodiment of the present invention shown in FIG. 1 in the structures of the rectifier circuit 12a and the drive circuit 14c.

Drive circuit 14c in the power transmission unit according to the third modified example is constituted by connecting the high side switching element _{Q H4a,} the high-side switching element _{Q H4b,} the low-side switching element _{Q L4a} and low-side switching element _{Q L4b} the H-bridge Has been done. The feeding coil L1 is connected to the bridge position of the drive circuit 14c, and the high frequency voltage V is input from the drive circuit 14c. Note that in FIG. 12, the power receiving device and the inductive load connected to the power receiving coil L2 are omitted for convenience of space.

In the power transmission unit according to the third modification, the first drive signal generation circuit 13a is connected to the respective gates of the high side switching element Q _H4a and the low side switching element _QL4a that form one series circuit of the H bridge. ing. The second drive signal generation circuit 13b is connected to the gates of the high side switching element Q _H4b and low-side switching element Q _L4b constituting the other series circuit of the H-bridge.

First driving signal generating circuit 13a and the second drive signal generation circuit 13b, the high-side switching element _{Q H4a,} the high-side switching element _{Q H4b,} low-side switching element _{Q L4a} and respective gates of the low-side switching element _{Q L4b} Of the high-side switching element Q _H4a , the high-side switching element Q _H4b , the low-side switching element Q _L4a, and the low-side switching element Q _L4b so that the high-frequency voltage V is output to the power feeding coil L1. The drive signal is output to the gate of.

  Regarding the structure and the operation of the power transmission unit according to the third modification other than the drive circuit 14c, the respective devices having the same or similar names and reference numerals in the respective power transmission units shown in FIGS. Since they are equivalent, duplicate description will be omitted. According to the power transmission unit according to the third modified example, similarly to the power transmission unit 1a according to the embodiment of the present invention, even if the impedance of the AC load changes abruptly, the drive circuit 14c on the power transmission side is protected and high transmission is achieved. It is possible to achieve a good balance between efficiency and efficiency.

  In the above description, the case where the electromagnetic wave having a higher frequency than the alternating current output by the power receiving unit 2 is supplied from the power feeding coil L1 to the power receiving coil L2 in a non-contact manner has been described as an example. The frequency of the electromagnetic wave transmitted is not necessarily limited to the case where the frequency is higher than the alternating current output by the power receiving unit 2. When an electromagnetic wave having a lower frequency than the alternating current output by the power receiving unit 2 is supplied from the power feeding coil L1 to the power receiving coil L2, for example, the frequency supplied from the power feeding coil L1 to the power receiving coil L2 is 30 to 100 kHz, and the power receiving unit 2 is The frequency of the output alternating current may be 200 kHz to 10 MHz.

  Further, the non-contact power supply system according to the present invention can be configured by combining the technical ideas of the respective embodiments and modifications as shown in FIGS. 1 and 10 to 12 with each other. As described above, the present invention includes various embodiments and the like not described in the present specification and the drawings, and the technical scope of the present invention is the matters specifying the invention according to the scope of claims reasonable from the above description. It is determined only by.

1a, 1b Power transmission unit 2 Power reception unit 11 Connection terminals 12, 12a Rectifier circuit 13 Drive signal generation circuit 13a First drive signal generation circuit 13b Second drive signal generation circuit 14, 14a, 14b, 14c Drive circuit 16 Power monitoring device 17 Frequency Control Circuit 17a Efficiency-Dependent Frequency Calculation Unit 17b Output Power Acquisition Unit 17c Transmission Power Determination Unit 17d Protection Frequency Calculation Unit 17e Optimal Frequency Setting Unit 17f Voltage Comparison Unit 20 Power Receiver 22 Rectifier Circuit 23 Drive Signal Generation Circuit 24 Drive Circuit C1 No. 1st capacitor C2 2nd capacitor C3 3rd capacitor D1 1st diode D2 2nd diode D3 3rd diode D4 4th diode L1 feeding coil L2 receiving coil V high frequency voltage I high frequency current X inductive load ( AC load)
QH1 High side switching element QL1 Low side switching element QH2 High side switching element QL2 Low side switching element QH3a High side switching element QH3b High side switching element QL3a Low side switching element QL3b Low side switching element d Interval

Claims (7)

A power receiving unit having a power receiving coil, converting the electric power input from the power receiving coil to generate an alternating current, and supplying the alternating current to an inductive load ;
A power feeding coil that supplies an electromagnetic wave to the power receiving coil in a non-contact manner by an electromagnetic induction method, a drive circuit that includes a switching element and supplies a current for generating the electromagnetic wave to the power feeding coil, and measures the power supplied to the power feeding coil. From a power monitoring device, a drive signal generation circuit that supplies a driving signal to the gate of the switching element, a storage device that stores data of a transmission efficiency-frequency curve obtained in advance, and the power monitoring device when the frequency is changed. The output of the storage device is changed to approach the maximum value of the transmission efficiency-frequency curve read from the storage device , an optimum frequency is searched for on the transmission efficiency-frequency curve , and the drive is performed by the optimum frequency. A power transmission unit having a frequency control circuit that determines the frequency of a signal and controls the drive signal generation circuit;
Bei example, the power monitoring device is a voltage input to the feeding coil, over time to measure the high-frequency current flowing through the high-frequency voltage and the feed coil varies with the impedance characteristics of the inductive load, measured The non-contact power feeding system , wherein the values of the high-frequency voltage and the high-frequency current thus generated are output to the frequency control circuit as the power data .   The contactless power supply system according to claim 1, wherein the power supply coil supplies an electromagnetic wave having a frequency different from the alternating current to the power reception coil. An electromagnetic wave is supplied in a non-contact manner to a power receiving unit that has a power receiving coil, converts electric power input from the power receiving coil to generate an alternating current, and supplies the alternating current to an inductive load by an electromagnetic induction method. A power transmission unit,
A power feeding coil tightly coupled to the power receiving coil,
A drive circuit that includes a switching element and supplies a current for generating the electromagnetic wave to the power feeding coil,
The voltage input to the power feeding coil, the high frequency voltage that changes depending on the impedance characteristics of the inductive load and the high frequency current flowing in the power feeding coil are measured over time, and the measured high frequency voltage and high frequency current A value, as the data of the power supplied to the power feeding coil, a power monitoring device that outputs to the frequency control circuit ,
A drive signal generation circuit that supplies a drive signal to the gate of the switching element;
A storage device that stores data of a transmission efficiency-frequency curve that is obtained in advance;
The optimum frequency on the transmission efficiency-frequency curve is set so that the change in the power data when the frequency is changed is a change that approaches the maximum value of the transmission efficiency-frequency curve read from the storage device. A frequency control circuit that searches, determines the frequency of the drive signal according to the optimum frequency, and controls the drive signal generation circuit;
A power transmission unit comprising:   The power transmission unit according to claim 3, wherein the power feeding coil supplies an electromagnetic wave having a frequency different from the alternating current to the power receiving coil. The frequency control circuit,
The transmission efficiency-efficiency dependent frequency calculation unit for calculating the efficiency dependent frequency by changing the frequency of the high frequency on the frequency curve,
A voltage measured on the power feeding coil is equal to or lower than a breakdown threshold voltage that protects the switching element, and a protection frequency calculation unit that calculates the protection frequency by changing the efficiency-dependent frequency,
An optimum frequency setting unit that sets the protection frequency as an optimum frequency that is the final frequency of the drive signal,
The power transmission unit according to claim 3, further comprising: The frequency control circuit,
The power transmission unit according to claim 5, wherein the process of calculating the efficiency-dependent frequency and the process of calculating the protection frequency are repeatedly executed to determine the optimum frequency. A power receiving unit that has a power receiving coil, converts the electric power input from the power receiving coil to generate an alternating current, and supplies the alternating current to an inductive load. A non-contact power feeding method of supplying the non-contact to the power receiving coil,
The feeding coil from a driving circuit of the power supply coil, and to step the flow of current for generating the electromagnetic wave,
The voltage input to the power feeding coil, the high frequency voltage that changes depending on the impedance characteristics of the inductive load and the high frequency current flowing in the power feeding coil are measured over time, and the measured high frequency voltage and high frequency current A value is data of the electric power supplied to the power feeding coil,
Reading the data of the previously determined transmission efficiency-frequency curve stored in the storage device;
The optimum frequency of the drive signal input to the gate of the switching element included in the drive circuit, the change of the data of the power when the frequency is changed, a change that approaches the maximum value of the transmission efficiency-frequency curve. To search on the transmission efficiency-frequency curve so that
Generating the drive signal at the optimum frequency to drive the switching element;
A non-contact power feeding method comprising:

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