JP7626512B1 - Wireless power supply system having tuning adjustment circuit - Google Patents

Abstract

[summary]
[Problem] Wireless charging is performed using existing electronic devices.
[Solution] The power supply unit has a power supply coil. The power receiver has a power receiving coil, a power receiving circuit section, and a load. Electrical energy is supplied from the power supply unit to the power receiver by electromagnetic induction using the resonance phenomenon. The power supply coil is periodically turned on (driving state) and off (resonating state) by a switch circuit. The resonant frequency of the power receiver is approximately the sum of the driving state time and the resonant state time. The resonant frequency of the power supply unit is approximately the resonant state time period, and the resonance capacitor and coil are adjusted by a tuning adjustment circuit. A flyback changeover switch is provided to switch between utilizing the diode in the switch circuit or taking a shortcut. A voltage stabilization circuit is provided to stabilize the input voltage. A receiving side frequency adjustment circuit is provided.

Description

The present invention relates to wireless power supply, and in particular to wireless power supply that supplies power through resonant inductive coupling.

In the field of wireless power supply technology, many devices based on various methods and systems have been proposed. Among these, the method using electromagnetic induction is widely known. Among these, the method using resonance technology due to electromagnetic induction is representative and is called by various names. This invention is based on the technology using magnetic coupling using an LC resonant circuit.

Patent Document 1 discloses a wireless power supply method and power supply system that allows for the expansion of the use of a wider range of frequencies in wireless power supply that can supply power over a relatively long distance by coupling through electromagnetic resonance. The electromagnetic resonance wireless power supply method is a wireless power supply in which the power transmission circuit of a power transmission device and the power receiving circuit of a power receiving device are coupled by electromagnetic resonance, and is characterized in that the power transmission device uses two different frequency components f1 and f2 for the power source 2, sets the resonant frequency of the power transmission circuit to f1 and/or f2, periodically changes the conditions of the power transmission circuit to an unstable electrical transient state of current or voltage, and sets the resonant frequency of the power receiving device to (f2-f1) or (f1+f2) due to the beat phenomenon, and supplies power at the frequency of (f2-f1) or (f1+f2) to the load.

Patent Document 2 discloses a very simple wireless power feeder that uses a loop coil as a power transmission device. The power transmission loop coil provided in the power transmission device extracts electrical energy from a DC power source and generates periodically changing electromagnetic field resonance energy in space. The power receiving loop coil provided in the power receiver extracts the periodically changing electromagnetic field resonance energy from space as electrical energy and supplies power to a load. The power transmission loop coil and the power receiving loop coil are electromagnetically resonantly coupled, and power is supplied wirelessly from the power transmission device to the power receiver.

Patent document 3 discloses a wireless power supply system that includes multiple relay devices and suppresses a decrease in power transmission efficiency caused by the relay devices. The system includes a power transmission device that transmits the supplied power, multiple relay devices that relay the power transmitted from the power transmission device, a power receiver that receives the power relayed by the relay devices, and a control device that controls the relay devices so that power is transmitted through the transmission path that provides the highest power transmission efficiency among multiple transmission paths that transmit the power from the power transmission device to the power receiver via the relay devices.

Patent document 4 discloses a technology for increasing the power transmission efficiency of a magnetic resonance type wireless power supply system. The magnetic resonance type wireless power supply system includes an AC power source, a voltage conversion coil connected to the AC power source, a power transmission side LC circuit, a power receiving side LC circuit, an impedance conversion coil, a load connected to the impedance conversion coil, and a transmission efficiency adjustment capacitor connected in parallel to the load. The power transmission side LC circuit has a power transmission side coil and a power transmission side capacitor arranged near the voltage conversion coil and excited by electromagnetic induction between the voltage conversion coil. The power receiving side LC circuit has a power receiving side coil and a power receiving side capacitor that resonate with the power transmission side coil. The impedance conversion coil is arranged near the power receiving side LC circuit and excited by electromagnetic induction between the power receiving side coil. The transmission efficiency adjustment capacitor has a capacity that increases the transmission efficiency of power from the AC power source to the load.

Patent Document 5 describes a wireless power supply system that includes a power supply having a power supply coil that generates magnetic flux and a power supply circuit section that supplies power to the power supply coil to generate magnetic flux, and a power receiver having a power receiving coil that receives the magnetic flux emitted from the power supply coil and a power receiving circuit section that recovers energy generated in the power receiving coil by electromagnetic induction, and supplies electrical energy from the power supply to the power receiver by electromagnetic induction using a resonance phenomenon, in which the power receiving circuit section of the power receiver has a power receiving side resonance capacitor that forms a power receiving side resonance circuit so as to resonate with the power receiving coil in combination with the power receiving coil at a power receiving side resonance period, and the power supply circuit section of the power supply has a power supply side parallel The present invention discloses a wireless power supply system having a parallel resonant circuit, comprising: a power supply side resonant capacitor that forms a resonant circuit; a switch circuit that alternates between a switch-on state in which a drive current flows through a power supply coil of the power supply device and a switch-off state in which the drive current is cut off, with the switch circuit being set to the power receiving side resonant period; a control circuit that inputs a drive pulse signal that controls on and off of the switch circuit and adjusts the timing of inputting the drive pulse signal; and a power supply side tuning adjustment circuit that finely adjusts the capacitance of the power supply side resonant capacitor or the inductance of the power supply coil, and adjusts the sum of the power supply side resonant period and the pulse width of the drive pulse signal to match the power receiving side resonant period.

JP 2017-163647 A JP 2017-028998 A JP 2017-028770 A JP 2014-176122 A Patent No. 7141156

Some electronic devices use built-in batteries. When such batteries are discharged and worn out, it is common to attach the electronic device to a dedicated charger in order to recharge them.
Recently, a method of charging batteries using wireless power transfer has been proposed. This is realized by providing a dedicated coil and electric circuit in the charging device on the power transfer side and the electronic device on the power receiving side.

Resonant circuits are sometimes used for wireless power supply. The resonant circuit on the power supply side can be selected to be either a series resonant circuit or a parallel resonant circuit. A series resonant circuit is easy to send large amounts of energy, but it has a large loss. On the other hand, a parallel resonant circuit is the opposite, being used to send relatively small amounts of energy and characterized by being easy to create a stable resonant state.
In conventional wireless power supply, a series resonant circuit is generally used on the power supply side. Also, a method is adopted in which the resonant state is detected and the frequency is adjusted. This is because the resonant frequency varies depending on the position and posture of the power receiver side, and the ferrite coil of the power receiving device has a large variation in electrical performance depending on the material and winding condition, so if the resonant frequency is shifted, the power supply efficiency deteriorates, so a process is performed to adjust the resonant frequency on the power supply side.
The inventor of the present invention proposed in Patent Document 5 that a tuning adjustment circuit be provided on the power feeder side, on the premise that a parallel resonant circuit is employed on the power feeder side.

When attempting to wirelessly supply high power, such as 100 watts or more, using a parallel resonant circuit, if the receiver side is unloaded or lightly loaded in a resonant state, the voltage of both the supply coil and the receiver coil will rise, which can damage the DC-DC converter in the receiver.
An object of the present invention is to provide a wireless power supply system that does not increase the voltage on the receiver side (input voltage to the DC-DC converter).

The inventors of the present invention solved the problem by adopting a parallel resonant circuit on the power supply side, switching between the resonant method and the flyback method when supplying drive current to the power supply side, stabilizing the input voltage on the power supply side, adjusting the resonant frequency on the power receiving side, and devising the timing and adjustment method, as well as the method of adjusting the resonant frequency.

A wireless power supply system using a parallel resonant circuit according to the present invention includes a power supply unit having a power supply coil that generates a magnetic flux and a power supply circuit unit that supplies power to the power supply coil to generate a magnetic flux, and a power receiver having a power receiving coil that receives the magnetic flux emitted from the power supply coil and a power receiving circuit unit that recovers energy generated in the power receiving coil by electromagnetic induction, and is a wireless power supply system that supplies electrical energy from the power supply unit to the power receiver by electromagnetic induction using a resonance phenomenon, wherein the power receiving circuit unit of the power receiver has a power receiving side resonance capacitor that forms a power receiving side resonance circuit so as to resonate with the power receiving coil at a power receiving side resonance period in combination with the power receiving coil, and the power supply circuit unit of the power supply unit includes: a power supply side resonance capacitor that forms a power supply side parallel resonant circuit so as to resonate with the power supply coil at a power supply side resonance period in combination with the power supply coil; The present invention is characterized in that it comprises a flyback changeover switch that switches between utilizing the diode in the switch circuit and shortcutting it; a control circuit that inputs a drive pulse signal that controls on/off to the switch circuit and adjusts the timing of inputting the drive pulse signal; and a power supply side tuning adjustment circuit that fine-tunes the capacitance of the power supply side resonant capacitor or the inductance of the power supply coil with the flyback changeover switch switched to the side that utilizes the diode, and adjusts the sum of the power supply side resonant period and the pulse width of the drive pulse signal to match the power receiving side resonant period.
This makes it possible to avoid voltage rise at the resonance maximum.

A wireless power supply system including a power supply unit having a power supply coil that generates a magnetic flux and a power supply circuit unit that supplies power to the power supply coil to generate a magnetic flux, and a power receiver having a power receiving coil that receives the magnetic flux emitted from the power supply coil and a power receiving circuit unit that recovers energy generated in the power receiving coil by electromagnetic induction, the wireless power supply system supplies electrical energy from the power supply unit to the power receiver by electromagnetic induction using a resonance phenomenon, the power receiving circuit unit of the power receiver comprising: The power supply circuit section of the power supply device includes a power supply side resonant capacitor that forms a power supply side parallel resonant circuit in combination with the power supply coil so as to resonate at a power supply side resonant period, a switch circuit that alternates between a switch-on state in which a drive current flows through the power supply coil of the power supply device and a switch-off state in which the drive current is cut off, with the cycle being the power supply side resonant period, a flyback changeover switch that switches between utilizing a diode in the switch circuit or shortcutting it, a voltage stabilization circuit that stabilizes an input voltage of the power supply device, and a voltage detection circuit that detects a voltage of the power supply device. the power supply side tuning adjustment circuit having a voltage sensor that detects a voltage of the power supply device, a current sensor that detects a current of the power supply device, a control circuit that inputs a drive pulse signal that controls on/off to the switch circuit, adjusts the timing of inputting the drive pulse signal, and operates the voltage stabilization circuit based on the detection results of the voltage sensor and the current sensor, and a power supply side tuning adjustment circuit that fine-tunes the capacitance of the power supply side resonant capacitor or the inductance of the power supply coil with the flyback changeover switch switched to the side that activates the diode, and adjusts the sum of the power supply side resonant period and the pulse width of the drive pulse signal to match the power receiving side resonant period.
This makes it possible to avoid voltage rise at the resonance maximum.

A wireless power supply system including a power supply unit having a power supply coil that generates a magnetic flux and a power supply circuit unit that supplies power to the power supply coil so as to generate a magnetic flux, and a power receiver having a power receiving coil that receives the magnetic flux emitted from the power supply coil and a power receiving circuit unit that recovers energy generated in the power receiving coil by electromagnetic induction, and supplies electrical energy from the power supply unit to the power receiver by electromagnetic induction using a resonance phenomenon, wherein the power receiving circuit unit of the power receiver includes a power receiving side resonance capacitor that forms a power receiving side resonance circuit so as to resonate with the power receiving coil at a power receiving side resonance period in combination with the power receiving coil, a rectifier circuit that rectifies a current generated in the power receiving coil, and a power receiving side frequency adjustment circuit that has a frequency adjustment element and controls whether to utilize or shortcut the frequency adjustment element when a voltage value output from the rectifier circuit becomes equal to or greater than a certain threshold value, and the power supply circuit unit of the power supply unit includes a power receiving coil that receives the magnetic flux emitted from the power supply coil and a power receiving circuit unit that recovers energy generated in the power receiving coil by electromagnetic induction, and the power receiving circuit unit of the power receiver includes a power receiving side resonance capacitor that forms a power receiving side resonance circuit so as to resonate with the power receiving coil at a power receiving side resonance period in combination with the power receiving coil, a rectifier circuit that rectifies a current generated in the power receiving coil, and a a switch circuit that alternates between a switch-on state in which a drive current flows through a power supply coil of the power feeder and a switch-off state in which the drive current is cut off, with the cycle being the power receiving side resonance cycle; a flyback changeover switch that switches between activating or shortcutting a diode in the switch circuit; a control circuit that inputs a drive pulse signal that controls on and off to the switch circuit and adjusts the timing of inputting the drive pulse signal; and a power supply side tuning adjustment circuit that fine-tunes the capacitance of the power supply side resonant capacitor or the inductance of the power supply coil with the flyback changeover switch switched to the side that activates the diode, and adjusts the sum of the power supply side resonance cycle and the pulse width of the drive pulse signal to match the power receiving side resonance cycle.
This makes it possible to avoid voltage rise at the resonance maximum.

A wireless power supply system including a power supply unit having a power supply coil that generates a magnetic flux and a power supply circuit unit that supplies power to the power supply coil to generate a magnetic flux, and a power receiver having a power receiving coil that receives the magnetic flux emitted from the power supply coil and a power receiving circuit unit that recovers energy generated in the power receiving coil by electromagnetic induction, the wireless power supply system supplies electrical energy from the power supply unit to the power receiver by electromagnetic induction using a resonance phenomenon, the power receiving circuit unit of the power receiver comprising: the power supply circuit section of the power supply device has a power supply side resonant capacitor which forms a power supply side parallel resonant circuit in combination with the power supply coil so as to resonate at a power supply side resonant cycle, a rectifier circuit which rectifies a current generated in the power receiving coil, and a power receiving side frequency adjustment circuit which has a frequency adjustment element and controls whether to utilize or shortcut the frequency adjustment element when a voltage value output from the rectifier circuit reaches or exceeds a certain threshold value, a switch circuit which alternately repeats, with the power receiving side resonant cycle as a period, a switch-on state in which a drive current flows through the power supply coil of the power supply device and a switch-off state in which the drive current is cut off, and a control circuit that inputs a drive pulse signal that controls on/off to the switch circuit and adjusts the timing of inputting the drive pulse signal; and a power supply side tuning adjustment circuit that fine-tunes the capacitance of the power supply side resonant capacitor or the inductance of the power supply coil with the flyback changeover switch switched to the side that activates the diode, and maintains a drive pulse signal period adjustment state in which the period of the drive pulse signal is adjusted to match the power receiving side resonance period, and the flyback changeover switch can be used as the shortcut side with the power supply side tuning adjustment circuit maintaining the drive pulse signal period adjustment state.
This makes it possible to avoid voltage rise at the resonance maximum.

In the wireless power supply system using the parallel resonant circuit, the power supply circuit unit of the power supply device includes a power supply device-side voltage stabilization circuit that increases and decreases an input voltage, a power supply capacity control circuit that changes the timing at which the drive pulse signal is input based on a plurality of thresholds of the voltage value of the voltage sensor of the power supply device or the current value of the current sensor of the power supply device, which change depending on a load state of the power receiver, and controls the power supply capacity by shifting a resonant frequency of the power supply device-side resonant circuit, and when the voltage value of the voltage sensor of the power supply device or the current value of the current sensor of the power supply device exceeds a predetermined threshold, controls the power supply device-side voltage stabilization circuit to increase or decrease the input voltage. and a power supply side voltage stabilization circuit control circuit that reduces the voltage output from the rectifier circuit of the power receiver, and the power receiving circuit section of the power receiver has a power receiving capacity control circuit that controls the power receiving capacity by a power receiving side frequency adjustment circuit that controls whether to utilize or shortcut the frequency adjustment element when a voltage value output from the rectifier circuit of the power receiver, which is generated in response to the load state of the power receiver, reaches or exceeds a certain threshold value, and the voltage output from the rectifier circuit of the power receiver, which is generated in response to the load state of the power receiver, is prevented from exceeding a certain voltage value by composite control of the power supply capacity control circuit, the power supply side voltage stabilization circuit control circuit, and the power receiving capacity control circuit.
This makes it possible to avoid voltage rise at the resonance maximum.

The wireless power supply system is characterized in that, when the flyback changeover switch is switched to a side that activates the diode, the power supply side tuning adjustment circuit acts so that the power receiving side resonance period (t3) satisfies 0.9(t1+t2)=<t3=<1.1(t1+t2) with respect to the off time of the switch circuit, i.e., the sum of the time (t2) in the resonant state of the power supply device and the time (t1) in the driven state, and the power supply side tuning adjustment circuit acts so that, when the flyback changeover switch is switched to a side that shortcuts the diode, the power receiving side resonance period (t3) satisfies 0.6(t2)=<t3=<1.1(t2) with respect to the time (t2) in the resonant state of the power supply device.
This makes it possible to avoid voltage rise at the resonance maximum.

The wireless power supply system is characterized in that, when the flyback changeover switch is switched to the side that activates the diode, the drive time of the power supply device, i.e., the time that the drive pulse is on, is 40% or less of the period of the resonant frequency of the power receiver, and the power supply side tuning adjustment circuit, when the flyback changeover switch is switched to the side that shortcuts the diode, the drive time of the power supply device, i.e., the time that the drive pulse is on, is 50% or less of the period of the resonant frequency of the power receiver, and the wireless power supply system further includes a drive time adjustment circuit that adjusts the drive time within that range so that the power supply efficiency taking into account the power supply range, power supply distance, and specifications of the power supply coil and the power receiving coil and the output power of the power receiver are increased.
This makes it possible to avoid voltage rise at the resonance maximum.

The wireless power supply system is characterized in that the power supply coil of the power supply device is composed of a coil with 1 to 12 turns, and the coil size of the power supply coil is larger than the size of the power receiving coil of the power receiver.
This makes it possible to avoid voltage rise at the resonance maximum.

Moreover, in the wireless power supply system, the tuning adjustment circuit determines a power supply range, a power supply distance, and specifications of the power supply coil and the power receiving coil so that a coupling coefficient K between the power supply coil of the power supply device and the power receiving coil of the power receiver is in a range of K=0.3 (30%) or less or is close to that range, and a desired power supply efficiency and output power of the power receiver are equal to or greater than a predetermined level, and adjusts the inductance of the power supply coil so as to achieve a drive time that increases the power supply efficiency.
This makes it possible to avoid voltage rise at the resonance maximum.

Furthermore, in the wireless power supply system, the receiving coil of the receiver is a coil with three contact points in total: two points at both ends of the coil and one point drawn out from the middle of the number of turns, and the output voltage value or current value is adjusted according to the ratio of the number of turns drawn out.
This makes it possible to avoid voltage rise at the resonance maximum.

Furthermore, in the wireless power supply system, the receiving coil of the receiver is a coil with three contact points in total: two points at both ends of the coil and one point drawn out from the middle of the number of turns, and is a receiving coil with three contact points formed by overlapping two α-winding coils formed according to the ratio of the number of turns drawn out and connecting one of the drawn-out wires together.
This makes it possible to avoid voltage rise at the resonance maximum.

In the wireless power supply system of the present invention, the method of driving the power supply device and the method of adjusting the resonant frequency make it possible to suppress the increase in voltage on the receiver side when implementing high-power wireless power supply, even though the wireless power supply uses a parallel resonant circuit on the power supply device side.

1 is a diagram showing a basic circuit configuration of a wireless power supply system according to the present invention. FIG. 11 is a basic waveform diagram on the power supply side when the flyback changeover switch is OFF. FIG. 11 is a basic waveform diagram on the power supply side when the flyback changeover switch is ON. The circuit diagram of the receiver (A) is shown. The circuit diagram of the receiver (B) is shown. FIG. 2 is a diagram of a receiving coil of a power receiver. FIG. 1A is an explanatory diagram of the frequency adjustment function. An explanatory diagram of the frequency adjustment function (B).

Hereinafter, the best mode for realizing the system of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a diagram showing a basic circuit configuration of a wireless power supply system according to the present invention.
The wireless power supply system according to the present invention is configured by a combination of a power supply device 10 and a power receiver 2. The power supply device 10 supplies electrical energy to the power receiver 2.
As shown in FIG. 1 , the power receiver 2 is composed of a power receiving coil 1 , a power receiving side resonance capacitor 3 , a rectifier circuit 4 , a load 5 such as a battery, and a power receiving side frequency adjustment circuit 8 .
The power receiving side resonant capacitor 3 is composed of one or more capacitors connected in parallel. The power receiving side frequency adjusting circuit 8 is composed of a frequency adjusting element, which is a capacitor or an inductor element, and a FET switching element.
There are several characteristic features on the power receiver 2 side.
First, the power receiver 2 is equipped with a load 5 such as a battery.
Secondly, the size, material and electrical specifications of the receiving coil 1 provided in the receiver 2 and the power supplying coil 11 of the power supplying device 10 are designed according to the power supply range, power supply distance and power supply capacity.
Thirdly, the power receiving coil 1 and the power receiving side resonant capacitor 3 of the power receiver 2 are configured as a so-called resonator (LC resonant circuit) and are configured to have good characteristics at a predetermined resonant frequency. (The same applies to the power feeding coil 11 and the power feeding side resonant capacitor 14 of the power feeder.)
Fourth, when the power receiver 2 is a parallel resonant circuit, the rectifier circuit may be a half-wave rectifier.
In the present invention, the allowable deviation of the resonant frequency is large, so that it is possible to deal realistically with the problem of variation in electrical performance of the manufactured products, i.e., the problem of yield. Therefore, it is also possible to determine the resonant frequency for each model.

The power supply device 10 includes a power supply coil 11, a resonance capacitor 14 that configures a resonance circuit together with the power supply coil 11, a switch circuit 12 for turning on and off power to the power supply coil 11, a control circuit 17 for operating the switch circuit 12, and a voltage stabilization circuit 19. The resonance capacitor 14 is configured of one or more capacitors in parallel. A frequency adjustment circuit 15 (e.g., a circuit including a PLL circuit) that creates the timing for switching on and off is connected to the control circuit 17. A resonance state sensor 16 that detects the resonance state is included in the control circuit 17. This is configured, for example, by a phase detection circuit. A current sensor 19 and a voltage sensor 20 are connected to the resonance state sensor 16. The power supply device 10 is also provided with a power supply 18 that supplies power to the power supply coil 11 and supplies power required for each circuit.
The features of the power supply device 10 are as follows.
First, the power supply coil 11 and the resonance capacitor 14 form a parallel resonance circuit.
Secondly, there is only one switch circuit. When this switch is turned on, it is in a drive state, and when it is turned off, it is in a resonant state.
Thirdly, the control circuit 17 uses the timing of the frequency adjustment circuit 15 to control the switch circuit 14, thereby controlling the timing of the drive state and the resonance state.
Fourthly, it has a resonance state sensor 16 that detects the resonance state (mainly the frequency shift), and the control circuit 17 performs control to stop power supply or adjust the resonance frequency based on the detection result of the resonance state sensor 16.

FIG. 1 shows a basic circuit diagram (similar to a block diagram). In the basic circuit, a power supply coil 11 is provided, which generates a magnetic flux and causes electromagnetic induction. At least the electric circuit of the power supply device 10 is provided with a power supply side resonance capacitor 14 and a power source 18, which creates a resonance relationship with the power receiving coil 1 of the power receiver 2 at a certain frequency. The frequency at this time is called a resonance frequency, and generally, a frequency between several tens of kHz and 300 kHz, which is said to be a long wave that has little effect on the human body, is used. If this is taken as the reference resonance frequency, the reference resonance frequency used in the present invention is not particularly limited. On the other hand, an important feature of the present invention is that the resonance frequency on the power supply side and the resonance frequency on the power receiving side, which will be described later, are usually set to the same resonance frequency, but are set to a shifted resonance frequency based on a predetermined timing time.
The resonant frequency varies slightly depending on the positional relationship and state of the power receiver 2. For example, the situation changes depending on the position and inclination of the power receiving coil 1 of the power receiver 2. Therefore, if the power receiving coil 1 is within the range of the magnetic flux sent from the power feeding coil 11, energy can be supplied. At this time, the magnetic coupling state between the coil windings is generally indicated by a coefficient indicating the degree of coupling called a coupling coefficient (K). The present invention is also characterized by the method of determining the predetermined coupling coefficient that enhances the power feeding efficiency.
The inclusion of the power receiving coil 1 in the magnetic flux affects the power feeder 10 in the form of a shift in the resonant frequency. If the resonant frequency shifts, the efficiency of energy supply decreases.
Therefore, the shifted frequency and phase are detected by a resonance state sensor 16 (for example, a circuit including a phase detection circuit), and the resonance frequency of the power supply coil 11 is adjusted according to the detected frequency and phase. For example, the adjustment can be performed by changing the resonance capacitor 14.
This adjustment, also called tuning, can be done during manufacturing or automatically controlled by an adjustment circuit during operation, but collectively it is called a tuning adjustment circuit. The resonance capacitor is composed of one or more capacitors, and the simplest tuning method is to connect several types of capacitors in parallel in advance, and adjust the frequency to the desired resonance frequency by pattern cutting unnecessary capacitors during manufacturing to make them ineffective. There is also a method of manually adjusting the frequency by placing a trimmer capacitor, variable capacitor, etc.
In addition, as a method of automatically controlling the frequency during operation using an adjustment circuit, several pairs of capacitors and switches are connected in parallel in advance, and the adjustment circuit controls the switches connected in series to each capacitor to set the desired resonance frequency. Another method is to attach a servo motor to the adjustment knob of the variable capacitor, and have the adjustment circuit control the servo motor to set the desired resonance frequency.
On the other hand, the receiving side is often adjusted during manufacturing, but a method in which the inductance of the receiving coil is measured in advance and a capacitor that matches it is installed in the unused part can also be considered a tuning adjustment circuit in a broad sense.
Connecting capacitors in parallel reduces the internal resistance and helps to reduce heat generation.
In addition, the frequency adjustment circuit 15 can adjust the power supplying capacity (power) by lengthening or shortening the time of the driving state by using a circuit with a built-in PLL (phase-locked loop) circuit, for example. In some cases, it is also possible to change the resonance frequency by providing a plurality of power supply coils 11 and switching between them. Here again, the present invention is characterized in that the adjustment value of the optimal resonance frequency by frequency adjustment is a shifted resonance frequency based on a predetermined timing time described later.

Various factors must be taken into consideration when adjusting the frequency (or phase). Therefore, it is preferable to provide a control circuit 17 that performs program control using a microcontroller (an integrated circuit including a processor, a memory, and peripheral circuits) or a programmable logic device (an integrated circuit that can define and change an internal logic circuit). The control circuit 17 is connected to a resonance state sensor 16 (phase detection circuit). The resonance state sensor 16 detects a frequency shift or a phase shift and transmits the signal to the control circuit 17. As a result, when an object other than the specified power receiver 10 approaches, the resonance state sensor 16 detects an abnormal frequency or phase and transmits the signal to the control circuit 17, which then acts on the power source 18 to stop power supply.
The wireless power supply system of the present invention is configured with the basic circuit shown in Fig. 1. The position of the resonance capacitor 14 of the power supply device 10 is connected in parallel with the power supply coil 11. The circuit in which this resonance capacitor 14 is arranged is generally called a parallel resonance circuit. On the other hand, in a commonly used wireless power supply system, a series resonance circuit is formed, and the position of this resonance capacitor is arranged in series with the coil.
This parallel resonant circuit is characterized in that when SW1 is turned on and a stable resonant state is established, and then SW1 is turned off, the power feeder 10 continues to resonate with the power receiver 2 while the energy stored in the power receiving coil 1 and the capacitor 3 is released. Here, based on the transition of the resonant state detected by a resonance state sensor 16 connected in parallel with the power feeding coil 11, a control circuit 17 realizes power supply of an appropriate frequency through timing control of the drive state by a resonance capacitor and a frequency adjustment circuit (PLL circuit) 15. This resonance state sensor 16 is a sensor that detects the resonant state, and detects transitions in voltage and current, phase detection of the resonant frequency, etc.

It is difficult to know the phase shift of the resonant frequency of the receiver 2 in Figure 1 clearly. However, by simulating various situations obtained from the resonance state sensor 16 in advance and programming based on that, it is possible to process a simple decision as to whether to raise or lower the resonant frequency, or leave it as it is. Then, by detecting the transition of the results after that adjustment, it is possible to determine whether it is suitable or not, and control it by trial and error.

Furthermore, when the control circuit 17 is used to adjust the resonant capacitor, a special component such as a finely controlled variable capacitor (a capacitor whose capacitance can be changed by moving one of the electrodes) would be ideal; however, there are currently few practical components available, so even if it is used as a fixed frequency without adjustment, it is possible to present specification values that are sufficient to meet the needs.
Another possible method is to switch between multiple coils.
The resonance frequency can also be adjusted by adjusting the drive time.

1 is configured with an N-channel MOSFET and a Schottky barrier diode. Also, a detailed example of the rectifier circuit 4 of the power receiver 2 is configured with a capacitor, a voltage stabilizing circuit 6, and a Schottky barrier diode 7. The Schottky barrier diode 7 may be a rectifier diode. These are just examples, and a suitable configuration may be used depending on the product specifications.
In order to achieve the objective of suppressing the rise in voltage on the power receiver side when wireless power supply of high power such as 100 watts or more is implemented, a flyback switch is provided as one feature of the present invention, which switches between using or short-circuiting the Schottky barrier diode that calibrates the switch circuit 12. When the Schottky barrier diode element is used, it is called the "resonance method", and when the Schottky barrier diode element is short-circuited, it is called the "flyback method". The flyback switch 13 (SW2) may be provided as an electronic switch and switched, or may be manually shorted using a jumper pin or the like. In some cases, when only the flyback method is used, it is also possible to implement a short pattern without implementing a diode.
The basic waveform diagram on the power supply side in the case of the resonance method (when SW2 = OFF) is shown in Figure 2, which will be described later. In the case of the flyback method, the waveform diagram is shown in Figure 3, "Basic waveform diagram on the power supply side when SW2 = ON." Figures 2 and 3 will be described in detail later, but in the case of the resonance method, the power supply range is such that part of the inner diameter of the power supply coil is included in the inner diameter of the power receiving coil, making it possible to supply power and allowing a large power supply distance. On the other hand, voltage control is difficult, and when the power receiving device is unloaded or lightly loaded, or when the power supply distance changes suddenly, the effect of resonance can cause a sudden voltage rise as if it is running out of control.
In the case of the flyback method, power can be supplied within the range where the entire receiving coil fits inside the inner diameter of the power supply coil, and both the power supply range and power supply distance are smaller than those of the resonant method. On the other hand, voltage control is easy, and although a voltage rise occurs when the receiving device is unloaded or lightly loaded, it is easy to control because there is a certain rule.
In the "resonance method," the optimum resonance frequency difference between the power source and the power receiver is derived through actual measurement or simulation. A resonance capacitor can be installed to match that resonance frequency. This is the same for the "flyback method."
In addition, according to this method, the inductance of the coil does not need to be high, and if possible, a low resistance coil will meet the requirements and have a high effect of reducing loss. Therefore, by combining a coil with 1 to 12 turns made of low resistance wire material and a matching resonance capacitor, it is possible to achieve a greater effect. In particular, if the power supply coil on the power supply side is larger than the power receiving coil, it becomes possible to supply power to multiple power receivers with high efficiency.

In order to achieve the objective of suppressing the rise in voltage on the receiver side when implementing wireless power supply of high power such as 100 watts or more, a voltage stabilization circuit 19 is provided in the power supply device circuit as one of the features of the present invention. The control circuit operates a voltage stabilization circuit (e.g., a DC-DC converter) to adjust the input voltage, thereby manipulating the capacity of wireless power supply. If there is an increase in the coil voltage of the power supply device or the input current value of the power supply device when the receiver side is unloaded by manipulating the input voltage, the increase in the output voltage of the power receiver can be stopped by lowering the input voltage.

In order to achieve the objective of suppressing the rise in voltage on the receiver side when implementing wireless power supply of high power such as 100 watts or more, a frequency adjustment circuit 8 is provided on the receiver 2 side as one of the features of the present invention. When the voltage value output from the rectifier circuit 4 (output voltage of the receiver) reaches or exceeds a certain threshold value, the FET is turned on to control whether the frequency adjustment element is utilized or shortcutted. The frequency adjustment element is a capacitor or an inductor element. Either of these elements is related to the resonance frequency input as a parallel resonant circuit.
When the FET is turned on, the resonance frequency is shifted forward or backward when the frequency adjustment element is energized or cut off. By switching the FET on, the resonance frequency shifts from a constant output voltage, reducing the power supply capacity and controlling it so that it cannot rise above a certain voltage.

FIG. 2 is a diagram for explaining the basic waveform diagram (when SW2=OFF) on the power supply side of the present invention. That is, it is a waveform diagram of the resonance method. In this diagram, the waveform of the drive current is omitted. Also, the resonance coil current is omitted, and the receiving coil voltage is drawn. The resonance coil voltage is omitted, and the power supply coil voltage is drawn.
2, there is a drive voltage pulse 201, the pulse waveform for controlling the switch circuit 14, which is depicted as a rectangular figure. This drive voltage pulse 201 is the waveform of a signal given to the switch circuit 12 from the control circuit 17 in FIG. 1, and is a pulse generated by the control circuit 17 to control the switch circuit 12 from the timing of the frequency adjustment circuit 15. When the drive voltage pulse 21 is high, the switch is turned on. In other words, when the switch is turned on, power from the power source 18 is supplied to the power supply side resonant capacitor 14, so that the switch is in a driven state. This drive time 28 (t1) is called the drive pulse width 25.
The time when the switch is turned off and not driven is a resonant state, that is, a resonant time 29 (t2) is referred to as a power supply side resonant period 26 (t2).
1, when the power supply coil 11 and the resonance capacitor 14 form a parallel resonant circuit, it is safe to say that the power supply device 10 continues to supply energy as long as it is in a resonant state with the power receiver 2, whether in a driven state or a resonant state. That is, the tuning adjustment circuit is adjusted so that the receiver-side resonance period 27 (t3), which is the sum of the time (t2) when the power supply device is in a resonant state and the time (t1) when it is in a driven state, satisfies 0.6(t1+t2)=<t3=<1.1(t1+t2).
On the other hand, from the viewpoint of the power supply device, energy is actually supplied instantly when the device is in the driving state.
While the switch circuit 14 is switched on, that is, while the drive voltage pulse 201 is being supplied, the power supply coil voltage 203 is kept close to zero (it can also be said that the drive voltage pulse 201 is supplied at a timing close to zero). As a result, the power receiving coil voltage 202 shows a distorted waveform during the drive time 28. During the drive time 28, the power supply coil voltage 203 is in a zero state and a drive current flows. The drive current is a waveform at a point on the way from the switch circuit 12 to the power supply side resonant capacitor 14 in FIG. 1. The power supply side resonant capacitor 14 appears as an AC waveform that is shifted in phase by 90 degrees from the resonant coil current, but the drive current is a conversion of part of the power energy stored in the resonant capacitor 14.
When a current flows, it is converted into magnetic flux output from the power supply coil 11 and acts on the power receiving coil 1 of the power receiver 2, causing electromagnetic induction and allowing energy to be recovered, so it appears as if energy has been transferred. This reduction in the amount of recovered energy is observed as a distortion in the power receiving coil voltage 202.

On the other hand, the present invention also exhibits advantageous features in terms of switch loss. During the drive time 28, the power supply coil voltage 203 is in a state close to zero, but if a voltage is applied when the switch circuit 12 is switched at this time, so-called switching loss occurs due to switching. Since this occurs due to the overlap of current and voltage, the present invention has the effect of minimizing switching loss by switching the power supply coil voltage 203 in a state close to zero. Furthermore, since the drive current flowing here does not exceed the power supply coil current, a high current peak waveform is not generated. As a result, it is possible to suppress switching loss and stress, and since these losses can be said to be heat losses, it also leads to the effect of less heat generation. Although it is similar to the general switching performed in a state of zero voltage, the ZVS method, the present invention is a new method that is effectively utilized in the power supply means of wireless power supply.
In the graph of Fig. 2, the drive pulse is turned on before the power supply coil voltage 203 becomes zero. This is because there is a switching delay, and the drive pulse is turned on before the voltage becomes zero, i.e., near the zero value. Furthermore, the value is slightly different from zero because the switching circuit has a resistance value, and this resistance value is output as a voltage. In any case, this explanation has shown the essential idea of the method.
The length of the drive pulse width 25 of the drive voltage pulse 201 during the drive time 28 and the strength of the power feeding coil voltage 203 result in the power energy supplied to the power receiver 2, i.e., the power feeding capacity. In other words, if the power to be supplied to the power receiver 2 is to be increased, this is achieved by lengthening the drive pulse width 25 and increasing the power feeding coil voltage 203. If the power is to be decreased, the opposite is true.
However, simply lengthening the drive pulse width 25 does not suffice, because the coupling with the power receiving coil of the power receiver 2 becomes stronger, and if the coupling becomes too strong, efficiency decreases. Also, increasing the voltage of the power feeding coil voltage 203 requires the withstand voltage of various electronic components, which is not practical, and therefore there is a certain limit to it. Naturally, this determines the limit of the design value of the power desired by the power receiver. In addition to the drive pulse width 25, the specifications of the power feeding coil 11 and the power receiving coil 1 also have a large effect, and the specifications of the power feeding range and the power feeding distance also have an effect, so the voltage value of the power feeding coil voltage 203 and the specifications of the drive pulse width 25 are determined by balancing these overall parameters.

Once the specifications for the drive pulse width are determined, the design value of the resonator of the power feed coil 11 and power feed side resonant capacitor 14 of the power feeder 10, i.e., the resonant frequency, can be determined. The resonant frequency of the power feeder 10 is determined by the periodic time of the power feed side resonant period 26. On the other hand, in the power receiver 2, it is determined by the periodic time of the power receiving side resonant period 27, which is the sum of the drive pulse width 25 and the periodic time of the power feed side resonant period 26. For this reason, the present invention is characterized in that the resonant frequency of the power feeder 10 and the resonant frequency of the power receiver 2 are adjusted to have a predetermined deviation.
Regarding how to determine the pulse width in the drive pulse width 25 during the drive time 28, it is known that high power supply efficiency can be achieved by setting the duty ratio to approximately 1/4 or less of the resonant frequency of the receiver 2, i.e., the resonant period. The power supply capacity (power that can be supplied) is almost maximum when the drive pulse width 25 has a duty ratio of approximately 16%. At 16% to 25%, power consumption increases but the increase in power supply capacity is small. Also, if it is too low, the power supply capacity does not increase. As a result, by controlling the duty ratio of the drive pulse width 25 to approximately 5% to 16%, it is possible to control the power supply capacity (power that can be supplied) to be lowered or raised.
For example, by controlling the duty ratio according to information on the output power of the power receiver side or information on required power, it is possible to supply power according to the power required by the power receiver side.
For example, the receiver can adjust the light output of a lighting device or control the duty ratio according to the battery charge state (power is reduced when the battery is fully charged, etc.).
If the driving time is extended too long or the coupling coefficient is high, the balance of the resonance state will be lost, and for example, the resonance coil voltage will increase abnormally, which will cause damage to electronic components. In the present invention, it is also important to determine this coupling coefficient appropriately, and it is said that the range of power supply efficiency in which energy can be efficiently sent is approximately K = 0.05 to 0.3 (5% to 30%). Among these, the peak value is around K = 0.16 (16%). In other words, it is sufficient to determine the specifications of the driving pulse width, the specifications of the power supply coil 11 and the power receiving coil 1, the power supply range, and the power supply distance so as to obtain this coupling coefficient.
Furthermore, the coupling coefficient is closely related to the power supply distance. The higher the coupling coefficient, the higher the power supply efficiency. The position where power supply efficiency is high is when the power supply distance is zero. The closer the distance between the power supply coil 11 and the power receiving coil 1 is, the higher the coupling coefficient becomes, and the farther the distance is, the lower the coupling coefficient becomes. In this invention, power supply efficiency is high when the coupling coefficient is relatively low, around K = 0.05 to 0.3 (5% to 30%), so high power supply efficiency can be achieved when the power supply coil 11 and the power receiving coil 1 are placed at a certain distance.

3 is an explanatory diagram of the basic waveform diagram of the power supply side of the present invention (when SW2=ON). That is, it is a waveform diagram of the flyback system. When SW2=ON, the diode is short-circuited and the flyback system is used. Compared with the waveform of the resonance system when SW2=OFF, the power supply coil voltage appears only in the positive direction. The drive pulse width 25 and drive time 28 can be lengthened. Basically, they can be set to a maximum of slightly less than half a cycle of the power supply side resonance cycle 26.
The longer the drive time (drive pulse width), the more current flows through the coil, generating magnetic flux in the power supply coil 11, and the magnetic flux also passes through the power receiving coil 1 of the power receiver 2 in a resonant state, causing current to flow. However, it cannot be said that simply setting the drive voltage pulse 201 for the full half cycle is sufficient. At a certain time (width), the power supply capacity reaches a plateau. Therefore, making it slightly shorter than the half cycle provides better power supply efficiency.
In the case of the flyback system, the relationship between the power supply side resonance period and the receiving side resonance period is not such that the sum of the resonance time and the drive time is the receiving side resonance period, but it is sufficient to make 0.6(t1+t2)=<t3=<1.1(t1+t2) true for the time (t1+t2) obtained by adding the time (t2) in the resonant state to the time (t1) in the drive state, based on the optimum value of a simulation performed in the resonance system. Alternatively, the interval of the drive voltage pulses 201 becomes the power supply side resonance period 26, and this should be adjusted to match the power receiving side resonance period 27.

Figure 4 is an explanatory diagram of circuit diagram A of the receiver of the present invention. This is a circuit that has a contact, i.e., a midpoint tap, at the midpoint of the receiving coil 1. By doing so, the receiving coil voltage drops and the receiving coil current increases accordingly. In other words, the output voltage of the receiving device can be lowered without impairing the power supply capacity. A resonant capacitor is connected in parallel to both ends of the receiving coil. The inductance at both ends of the coil is measured, and a capacitor capacity that matches the specified resonant frequency is selected and implemented. The midpoint position of the receiving coil is preferably the midpoint of the number of turns, but if it is moved closer to the GND side, the current value increases, and if it is moved closer to the positive side, the voltage value increases. Regardless of which way it is moved, the voltage x current = voltage can be adjusted to within an approximate value. This circuit diagram A is a circuit in which a rectifier diode is attached to the wire drawn from the midpoint tap.

Figure 5 is an explanatory diagram of circuit diagram B of the power receiving device of the present invention. This circuit diagram B is a circuit characterized by the fact that the wire drawn from the midpoint tap is dropped to GND. In this case, it is necessary to connect the GND of the capacitor that acts as a buffer to the GND of the midpoint tap. This has almost the same effect as circuit diagram A.

Figure 6 is an explanatory diagram of the receiving coil of the power receiving device of the present invention. When performing a midpoint tap from this receiving coil, it is possible to achieve this by attaching a lead wire from the position of the midpoint of the number of turns of the coil, or by pulling out the lead wire halfway through winding the coil and then starting to wind it again, but in both cases, the wire for the midpoint tap must go over the coil. In that case, the height of the coil increases by the amount of the winding coil that goes over the coil, which affects the assembly of the product. Therefore, in the case of two coils with α windings, the ideal coil winding method is as follows. The first layer is made into an α winding. The second layer is made into an α winding. The size and number of turns of the coils of the first and second layers are the same. Next, combine one of the wires from the first layer and one of the wires from the second layer. The winding of the first layer and the winding of the second layer are overlapped. In this way, the wire for the midpoint tap does not go over the coil, and the coil can be neatly formed. Furthermore, by making the first and second layers of windings have different numbers of turns and changing the turns ratio from the so-called midpoint tap, it is possible to change the voltage and current values output from the receiving coil.

7 is an explanatory diagram of the frequency adjustment function of the present invention. In the case of a parallel resonant circuit, the closer to the resonant state, the higher the voltage applied to the coil becomes. In order to prevent the voltage from exceeding a certain value, a method is required to immediately lower the input voltage of the power supply device. The present invention presents a method of controlling the input voltage to be increased or decreased through a voltage stabilization circuit 19, for example, a DC-DC converter, while monitoring the voltage and current of the power supply coil.
Also, a method of switching to a flyback system that is easier to control voltage by turning on the flyback changeover switch 13 (SW2) and shorting the diode is presented.
Furthermore, a method is presented in which a frequency adjustment circuit 8 is provided in the power receiver 2, and when the output voltage exceeds a certain level, the frequency adjustment element is turned on or off to shift the resonant frequency to another frequency. When the resonant frequency shifts, the power supply capacity decreases, so the coil voltage, i.e., the output voltage of the power receiver 2, can be reduced.
Also, shortening the driving voltage pulse time (width) reduces the current flowing through the power supply coil, which has the effect of reducing the power supply capacity.
In addition, by adjusting the interval of the drive voltage pulse, the resonant frequency of the power supply side can be changed slightly. This has the effect of shifting the resonant frequency and reducing the power supply capacity. The "power supply side frequency adjustment switching" in Figure 7 is realized by adjusting the time (width) and interval of the drive voltage pulse.
This voltage rise occurs when the battery connected to the power receiving side is in a no-load or light-load state, typically when it is fully charged. If the voltage becomes too high, it will exceed the maximum input voltage of the DC-DC converter attached to the power receiving device, causing damage. In addition, DC-DC converters with high input voltages are generally expensive, so it is not desirable to use them. This invention can solve this problem.
7, the vertical axis represents the output voltage of the power receiving device, the second vertical axis represents the input current value of the power feeding device, and the horizontal axis represents the distance between the power feeding coil and the power receiving coil. This shows the situation when the power receiving coil gets closer to the power feeding coil as it goes to the right on the horizontal axis.
The power supply has at least two kinds of resonance frequencies. The resonance frequency corresponds to the "power supply side resonance period" and is controlled by the interval of the drive voltage pulse.
In the explanatory diagram A of the frequency adjustment function of the present invention, if there is a load and a resonant state occurs, a current value will flow as energy. In particular, if there is a load on the power receiving device, a large input current value will flow from the power supply device. First, power is supplied with the resonant frequency of the power supply device shifted. In this state, the frequency is set so that the voltage of the power receiving coil does not increase above a certain value even when the power receiving device is unloaded.
When the input current value of the power supply device exceeds the set current value, this indicates that there is a load on the power receiving device, so the resonant frequency of the power supply device is changed to an optimal frequency. Next, when the output voltage of the power receiving device of the power receiving device exceeds the set voltage value, the frequency adjustment circuit turns on the FET, and the frequency adjustment element shifts the resonant frequency of the power receiving device. At this time, it is better to use a circuit that provides a certain amount of hysteresis. This reduces the power receiving capacity, which reduces the increase in the output voltage of the power receiving device.

FIG. 8 is an explanatory diagram B of the frequency adjustment function of the present invention in the case of no load.
Next, the behavior when there is no load. When the power receiving device is unloaded, the input current value of the power supply device becomes smaller. Since it does not exceed the set current value, there is no frequency adjustment switching on the power supply side. The resonant frequency of the power supply device continues to be shifted. When the power receiving device is unloaded or lightly loaded, the output voltage of the power receiving device rises more rapidly than when there is a load. When the output voltage of the power receiving device exceeds the set voltage value, the FET is turned on by the frequency adjustment circuit, and the resonant frequency of the power receiving device shifts due to the action of the frequency adjustment element. This reduces the power receiving capacity and reduces the increase in the output voltage of the power receiving device. However, if the distance approaches beyond a certain distance, there is a distance at which the output voltage of the power receiving device rises rapidly, and this distance can be set as the optimal distance. Because the difference in the resonant frequency becomes large on both the power supply side and the power receiving side, the power supply capacity drops to the lowest level, and the voltage rise can be suppressed.
In the configuration of the present invention, the loss caused by the shift in the resonant frequency in the flyback system only reduces the power supply capacity or power receiving capacity, and does not become heat loss. Although the FET of the power receiving device is a certain heat generation factor, when it is turned on and there is no load, the current flowing is low, so the impact is small.

The wireless power supply system of the present invention provides a solution to the conventional wisdom that wireless power supply is not suitable for parallel resonant circuits, and is a groundbreaking product that makes it possible to achieve high-power charging of 100 watts or more, and can be used in all industries that require charging as a power source for electric bikes, electric cars, etc.

REFERENCE SIGNS LIST 1 receiving coil 2 receiver 3 receiving-side resonant capacitor 4 rectifier circuit 5 load 6 voltage stabilization circuit 7 Schottky barrier diode 8 receiving-side frequency adjustment circuit 10 power supply 11 power supply coil 12 switch circuit 13 flyback changeover switch 14 power supply-side resonant capacitor 15 frequency adjustment circuit 16 resonance state sensor 17 control circuit 18 power supply 19 voltage stabilization circuit 20 voltage sensor 21 current sensor 25 drive pulse width 26 power supply-side resonant period 27 receiving-side resonant period 28 drive time 29 resonant time 201 drive voltage pulse 202 receiving coil voltage 203 power supply coil voltage

Claims (12)

a power feeder including a power feed coil that generates a magnetic flux and a power feed circuit unit that supplies power to the power feed coil so as to generate the magnetic flux;
A wireless power supply system including a power receiver having a power receiving coil that receives a magnetic flux emitted from the power supply coil and a power receiving circuit unit that recovers energy generated in the power receiving coil by electromagnetic induction, the wireless power supply system supplying electrical energy from the power supply unit to the power receiver by electromagnetic induction using a resonance phenomenon,
The power receiving circuit unit of the power receiver includes:
a power receiving side resonant capacitor that forms a power receiving side resonant circuit in combination with the power receiving coil so as to resonate at a power receiving side resonant period;
The power supply circuit unit of the power supply device
a power supply side resonant capacitor that forms a power supply side parallel resonant circuit in combination with the power supply coil so as to resonate at a power supply side resonant period;
a switch circuit including a diode for alternately repeating a switch-on state in which a drive current flows through a power supply coil of the power supply device and a switch-off state in which the drive current is cut off, with the power receiving side resonance period being a period;
a flyback changeover switch for switching between utilizing a diode in the switch circuit and shortcutting the diode;
a control circuit that inputs a drive pulse signal for controlling ON/OFF of the switch circuit and adjusts a timing for inputting the drive pulse signal;
and a power supply side tuning adjustment circuit that performs fine adjustment of the capacitance of the power supply side resonant capacitor or the inductance of the power supply coil with the flyback changeover switch switched to the side that activates the diode, and adjusts the sum of the power supply side resonant period and the pulse width of the drive pulse signal so that it matches the power receiving side resonant period. a power feeder including a power feed coil that generates a magnetic flux and a power feed circuit unit that supplies power to the power feed coil so as to generate the magnetic flux;
A wireless power supply system including a power receiver having a power receiving coil that receives a magnetic flux emitted from the power supply coil and a power receiving circuit unit that recovers energy generated in the power receiving coil by electromagnetic induction, the wireless power supply system supplying electrical energy from the power supply unit to the power receiver by electromagnetic induction using a resonance phenomenon,
The power receiving circuit unit of the power receiver includes:
a power receiving side resonant capacitor that forms a power receiving side resonant circuit in combination with the power receiving coil so as to resonate at a power receiving side resonant period;
The power supply circuit unit of the power supply device
a power supply side resonant capacitor that forms a power supply side parallel resonant circuit in combination with the power supply coil so as to resonate at a power supply side resonant period;
a switch circuit that alternately repeats a switch-on state in which a drive current flows through a power supply coil of the power supply device and a switch-off state in which the drive current is cut off, with the power receiving side resonance period being a period;
a flyback changeover switch for switching between utilizing a diode in the switch circuit and shortcutting the diode;
a voltage stabilization circuit that stabilizes an input voltage of the power supply device;
A voltage sensor that detects a voltage of the power supply device;
A current sensor that detects a current of the power supply device;
a control circuit that inputs a drive pulse signal for controlling ON/OFF of the switch circuit, adjusts a timing for inputting the drive pulse signal, and operates the voltage stabilization circuit based on detection results of the voltage sensor and the current sensor;
and a power supply side tuning adjustment circuit that performs fine adjustment of the capacitance of the power supply side resonant capacitor or the inductance of the power supply coil with the flyback changeover switch switched to the side that activates the diode, and adjusts the sum of the power supply side resonant period and the pulse width of the drive pulse signal so that it matches the power receiving side resonant period. a power feeder including a power feed coil that generates a magnetic flux and a power feed circuit unit that supplies power to the power feed coil so as to generate the magnetic flux;
A wireless power supply system including a power receiver having a power receiving coil that receives a magnetic flux emitted from the power supply coil and a power receiving circuit unit that recovers energy generated in the power receiving coil by electromagnetic induction, the wireless power supply system supplying electrical energy from the power supply unit to the power receiver by electromagnetic induction using a resonance phenomenon,
The power receiving circuit unit of the power receiver is
a power receiving side resonant capacitor that forms a power receiving side resonant circuit in combination with the power receiving coil so as to resonate at a power receiving side resonant period;
A rectifier circuit that rectifies a current generated in the power receiving coil;
a power receiving side frequency adjustment circuit that has a frequency adjustment element and controls whether to utilize or shortcut the frequency adjustment element when a voltage value output from the rectifier circuit becomes equal to or greater than a certain threshold value;
The power supply circuit unit of the power supply device
a power supply side resonant capacitor that forms a power supply side parallel resonant circuit in combination with the power supply coil so as to resonate at a power supply side resonant period;
a switch circuit that alternately repeats a switch-on state in which a drive current flows through a power supply coil of the power supply device and a switch-off state in which the drive current is cut off, with the power receiving side resonance period being a period;
a flyback changeover switch for switching between utilizing a diode in the switch circuit and shortcutting the diode;
a control circuit that inputs a drive pulse signal for controlling ON/OFF of the switch circuit and adjusts a timing for inputting the drive pulse signal;
and a power supply side tuning adjustment circuit that performs fine adjustment of the capacitance of the power supply side resonant capacitor or the inductance of the power supply coil with the flyback changeover switch switched to the side that activates the diode, and adjusts the sum of the power supply side resonant period and the pulse width of the drive pulse signal so that it matches the power receiving side resonant period. a power feeder including a power feed coil that generates a magnetic flux and a power feed circuit unit that supplies power to the power feed coil so as to generate the magnetic flux;
A wireless power supply system including a power receiver having a power receiving coil that receives a magnetic flux emitted from the power supply coil and a power receiving circuit unit that recovers energy generated in the power receiving coil by electromagnetic induction, the wireless power supply system supplying electrical energy from the power supply unit to the power receiver by electromagnetic induction using a resonance phenomenon,
The power receiving circuit unit of the power receiver includes:
a power receiving side resonant capacitor that forms a power receiving side resonant circuit in combination with the power receiving coil so as to resonate at a power receiving side resonant period;
The power supply circuit unit of the power supply device
a power supply side resonant capacitor that forms a power supply side parallel resonant circuit in combination with the power supply coil so as to resonate at a power supply side resonant period;
A rectifier circuit that rectifies a current generated in the power receiving coil;
a power receiving side frequency adjustment circuit that has a frequency adjustment element and controls whether to utilize or shortcut the frequency adjustment element when a voltage value output from the rectifier circuit becomes equal to or greater than a certain threshold value;
a switch circuit that alternately repeats a switch-on state in which a drive current flows through a power supply coil of the power supply device and a switch-off state in which the drive current is cut off, with the power receiving side resonance period being a period;
a flyback changeover switch for switching between utilizing a diode in the switch circuit and shortcutting the diode;
a control circuit that inputs a drive pulse signal for controlling ON/OFF of the switch circuit and adjusts a timing for inputting the drive pulse signal;
a power supply side tuning adjustment circuit that performs fine adjustment of the capacitance of the power supply side resonant capacitor or the inductance of the power supply coil with the flyback changeover switch switched to the side that activates the diode, and maintains a drive pulse signal period adjustment state in which the period of the drive pulse signal is adjusted to match the power receiving side resonant period,
13. A wireless power supply system having a parallel resonant circuit, comprising: a power supply side tuning adjustment circuit that maintains a drive pulse signal period adjustment state; and a flyback changeover switch that can be used as a shortcut side. A wireless power supply system including the parallel resonant circuit according to claim 3,
The power supply circuit unit of the power supply device
A power supply side voltage stabilization circuit that raises and lowers the input voltage;
a power supply capacity control circuit that changes a timing for inputting the drive pulse signal based on a plurality of thresholds of a voltage value of the voltage sensor of the power supply device or a current value of the current sensor of the power supply device, the thresholds varying according to a load state of the power receiver, and controls the power supply capacity by shifting a resonant frequency of the power supply side resonant circuit;
a power supply side voltage stabilization circuit control circuit that controls the power supply side voltage stabilization circuit to lower an input voltage when a voltage value of the voltage sensor or a current value of the current sensor of the power supply exceeds a predetermined threshold value,
The power receiving circuit unit of the power receiver is
A power receiving capacity control circuit is provided that controls the power receiving capacity by a power receiving side frequency adjustment circuit that controls whether to utilize or shortcut the frequency adjustment element when a voltage value output from the rectifier circuit of the power receiver, which is generated according to a load state of the power receiver, becomes equal to or exceeds a certain threshold value;
A wireless power supply system using a parallel resonant circuit, characterized in that the voltage output from the rectifier circuit of the receiver, which is generated in response to the load state of the receiver, is prevented from exceeding a certain voltage value through composite control of the power supply capacity control circuit, the power supply side voltage stabilization circuit control circuit, and the power receiving capacity control circuit. A wireless power supply system including the parallel resonant circuit according to claim 4,
The power supply circuit unit of the power supply device
A power supply side voltage stabilization circuit that raises and lowers the input voltage;
a power supply capacity control circuit that changes a timing for inputting the drive pulse signal based on a plurality of thresholds of a voltage value of the voltage sensor of the power supply device or a current value of the current sensor of the power supply device, the thresholds varying according to a load state of the power receiver, and controls the power supply capacity by shifting a resonant frequency of the power supply side resonant circuit;
a power supply side voltage stabilization circuit control circuit that controls the power supply side voltage stabilization circuit to lower an input voltage when a voltage value of the voltage sensor or a current value of the current sensor of the power supply exceeds a predetermined threshold value,
The power receiving circuit unit of the power receiver is
A power receiving capacity control circuit is provided that controls the power receiving capacity by a power receiving side frequency adjustment circuit that controls whether to utilize or shortcut the frequency adjustment element when a voltage value output from the rectifier circuit of the power receiver, which is generated according to a load state of the power receiver, becomes equal to or exceeds a certain threshold value;
A wireless power supply system using a parallel resonant circuit, characterized in that the voltage output from the rectifier circuit of the receiver, which is generated in response to the load state of the receiver, is prevented from exceeding a certain voltage value through composite control of the power supply capacity control circuit, the power supply side voltage stabilization circuit control circuit, and the power receiving capacity control circuit. A wireless power supply system including the parallel resonant circuit according to any one of claims 1 to 6,
When the flyback changeover switch is switched to a side that activates the diode, the power supply side tuning adjustment circuit
The power receiving side resonance period (t3) acts so as to satisfy 0.9(t1+t2)=<t3=<1.1(t1+t2) with respect to the time (t1+t2) obtained by adding the time (t2) in the resonance state of the power supply device to the time (t1) in the drive state of the power supply device while the switch circuit is off, that is, the time (t1+t2) obtained by adding the time (t2) in the resonance state of the power supply device to the time (t1) in the drive state of the power supply device;
When the flyback changeover switch is switched to a side that shortcuts the diode, the power supply side tuning adjustment circuit
A wireless power supply system having a parallel resonant circuit, characterized in that the receiver-side resonant period (t3) acts such that 0.6(t2) = < t3 = < 1.1(t2) holds true with respect to the time (t2) that the power supply device is in a resonant state. A wireless power supply system including the parallel resonant circuit according to any one of claims 1 to 6,
When the flyback changeover switch is switched to the side that activates the diode, the drive time of the power feeder, i.e., the time when the drive pulse is on, is 40% or less of the period of the resonant frequency of the power receiver,
When the flyback changeover switch is switched to the side that short-cuts the diode, the power supply side tuning adjustment circuit sets the drive time of the power supply device, i.e., the time during which the drive pulse is turned on, to 50% or less of the period of the resonant frequency of the power receiver,
The wireless power supply system of the parallel resonant circuit further comprises a drive time adjustment circuit that adjusts the drive time so that the drive time becomes a drive time that increases the power supply efficiency and the output power of the power receiver, taking into account the power supply range, power supply distance, and specifications of the power supply coil and power receiving coil, within the above range. A wireless power supply system including the parallel resonant circuit according to any one of claims 1 to 6,
A wireless power supply system having a parallel resonant circuit, wherein the power supply coil of the power supply device is composed of a coil having 1 to 12 turns, and the coil size of the power supply coil is larger than the size of the power receiving coil of the power receiver. A wireless power supply system including the parallel resonant circuit according to any one of claims 1 to 6,
The tuning adjustment circuit includes:
a coupling coefficient K between the power supply coil of the power supply device and the power receiving coil of the power receiver is in a range of K=0.3 (30%) or less, or is close to this range, and a power supply range, a power supply distance, and specifications of the power supply coil and the power receiving coil are determined so that a desired power supply efficiency and an output power of the power receiver are equal to or greater than a predetermined level, and an inductance of the power supply coil is adjusted so that a drive time at which power supply efficiency is increased is achieved. A wireless power supply system including the parallel resonant circuit according to any one of claims 1 to 6,
The receiving coil of the power receiver is
A wireless power supply system using a parallel resonant circuit, characterized in that the coil has three contact points in total: two at both ends of the coil and one point drawn out from the middle of the number of turns, and the output voltage or current value can be adjusted by changing the ratio of the number of turns drawn out. A wireless power supply system including the parallel resonant circuit according to claim 11,
The receiving coil of the receiver is a coil with three contact points in total: two points at both ends of the coil and one point drawn out from the middle of the number of turns, and two α-winding coils formed according to the ratio of the number of turns drawn out are overlapped and one of the drawn out wires is connected to each other, resulting in a receiving coil with three contact points.