Planar resonator for wireless power transfer

Planar resonator for wireless power transfer

Technical field

The present invention relates to a non-contact power transfer system. More specifically, the present invention designs a planar resonator for wireless power transfer in a non-contact power transfer system.

Background technique

Non-contact power transfer is used in applications such as non-invasive pacemaker battery charging and hybrid vehicle battery charging. In this application, inductive coupling is used exclusively, so that current is induced from the power station to the load. In this kind of system, power transmission is achieved exclusively by relying on the coupled magnetic flux of the power station and the load.

For example, states such as California are already studying road systems that encourage the use of trams. In this system, the inductively coupled flat coil is embedded in the road, or energized the cable embedded in the road, so that the induction coil of the vehicle receives the induced current from the road coil in order to allow the battery to be charged and/or even propelled. Typically, this system requires that the distance between the flux collection surface of the buried coil and the vehicle be kept within 5 cm in order to provide sufficient power transfer through induction.

US Patent 5,608,771 to Steigerwald et al. discloses a non-contact power transfer system in which power is transferred from a fixed source to a rotating load by using a resolver. The system eliminates the brush and slip ring device. The coupling in this type of system is also inductive.

Another configuration is to use a clamping connection around the main conductor, which connection is not in physical contact with the conductor. The power transfer is still through induction.

In the separate field of security identification, there are personal and vehicle identification tags (such as EZ-Pass, Smart-Tag, and some bridges in the tunnel from Boston to Virginia and the fast-track automatic toll collection system on some Interstate 95). It does not provide power transfer, but is used in the form of wireless communication. Contrary to the inductive coupling of the power transfer system, these security tags and toll tags are capacitively coupled transceivers. Therefore, the prior art lacks a non-contact power transfer system that includes the capacitive coupling function of electric flux in addition to the inductive coupling of magnetic flux.

Summary of the invention

It is very advantageous to provide a wireless power transfer planar resonator that allows power transfer on a non-magnetic, non-conductive direct current insulator (material). Electrical and/or magnetic energy is stored on the insulator, and energy is transferred through the insulator. The resonant element exhibits the characteristics of an integrated inductor-capacitor transformer.

In the first aspect of the present invention, the planar resonator includes coils arranged in a single spiral structure. However, when used in a multi-spiral structure, the capacitance between the spirals can be used for energy transfer, resulting in a combination of electrical and magnetic energy transfer on the IOET. On the other hand, the spirals can be arranged opposite each other, so that a bottom plate is not required. For example, the connection can be wireless, so that the phone battery can be charged without a physical wire connecting the phone to the charger. For wireless energy transfer, PCB is typically an inappropriate IOET.

Depending on the physical configuration and/or material used, the planar resonator stores electrical and magnetic energy at the same time for impedance matching or transfers in electrical or magnetic forms or electrical and magnetic forms on the energy transfer interface (hereinafter referred to as "IOET") In addition to power, it also completes the soft switching in the auxiliary switching power electronic converter circuit. Except for inductive energy storage, electrical (capacitive) energy storage or their combination such as a magnetic transformer coupled with built-in LC resonance characteristics, the physical configuration and/or materials used can allow transformer behavior with or without capacitive energy transfer. . The planar resonator does not need to use IOET for energy transfer, for example, in a single spiral structure.

According to another aspect of the present invention, the insulating coupling interface and the resonance box are functionally integrated into a planar structure with power transfer isolation characteristics. The device can contain two separate structures on either side of the IOET, for example, a mobile phone and its charger. Since no electrical contact is required on the IOET, the size of the entire charging circuit can be reduced according to safety standards such as the insulation specification of IEC950. The physical structure may include a set of spiral coils on each side of the IOET, typically with a spiral as a conductor line on a separate substrate, such as a wire or a printed circuit board (FR-4).

One advantage of the present invention is that it facilitates the use of wearable electronic devices. For example, materials such as FR4 and wire circuits can be used to make the coil surface flexible. In addition to flexibility, the coil can be formed into any shape, thereby pushing a braided wire set in a fabric, or can be attached to a clothing with a cushion embedded with a conductor. In this way, for example, people can charge radios, mobile phones, and/or computers by carrying equipment similar to fabrics (only a few of the many wearable devices are listed). Therefore, the implementation of the present invention on a wearable electronic device can provide an interface between the wearable device and an external power source. It is also possible to transmit digital or analog signals through this interface, in order to upload or download digital signals, for example.

In another aspect of the invention, the planar power resonator may have a thin and/or relatively flat top coil surface. In wireless applications, IOET can include, for example, (i) a non-conductive/insulating film at the bottom of the top spiral (for isolation), (ii) air, and (iii) a non-conductive/insulating film at the top of the bottom spiral (for isolation) . The coils can be arranged in upper and lower structures arranged substantially axially. In addition, there may be an emulsifier at the bottom of the upper coil, and there is an air gap between the emulsifier and the top of the lower coil.

The spiral conductor may include a pcb spirally wound conductor. In addition, the battery charging circuit may be coupled with one of the first and second spiral conductors, and the load may be coupled with the other of the first and second spiral conductors. The coupling of the battery charging circuit may include capacitive coupling. The load can be coupled through magnetic coupling, where power is transferred through the magnetic flux coupling on the IOET.

According to an aspect of the present invention, through the magnetic flux coupling of the first and second spiral conductors on the IOET, the signal applied to the first spiral conductor can be transferred to the second spiral conductor.

The first and second spiral conductors and the IOET are preferably integrated into a flat (flat/thin) structure.

The planar resonator may further include a third spiral conductor, and the third spiral conductor and the first spiral conductor are designed into a double-wire spiral structure on the top surface of the IOET, and/or a fourth spiral conductor, On the bottom surface of the IOET, the fourth spiral conductor and the second spiral conductor are designed into a two-wire spiral structure. It should be understood that both the double-line top and the single-bottom, or the single-bottom and the double-line bottom are optional configurations. By removing and adding a conductive connection between the two spirals, the equivalent series or parallel resonator operation can be realized respectively.

Therefore, the two-wire spiral structure on the top and bottom surfaces of the IOET can be used to form a parallel resonator or a series resonator.

In addition, instead of the double-wire structure, a plurality of spiral conductors may also be arranged in a multi-wire structure on the top surface or the bottom surface, respectively. The spiral conductor may be designed such that the planar resonator contains parallel resonators, or series resonators.

The first plurality and the second plurality of spiral conductors may be designed such that the planar resonator includes a parallel resonator, or a series resonator. There may be a configuration with one capacitive plate. One end of the coil is connected to the insulator of the capacitor, and the other end is connected to the charging circuit. In this configuration, the planar resonator acts as an inductor and a capacitor in series, affecting the Q of the circuit.

The two-wire configuration can also be obtained by separating a second thin film of insulating material from two spirals that form a two-wire configuration on one side of the IOET. (That is, the insulating film is on the top of the top spiral; the other spiral is on the top of the insulating film.) The insulating film stores electrical energy and forms the capacitive part of the resonator, wherein the inductive part spirals from the set on the insulating film Obtained from self-coupling on either side. The film does not transfer energy, but stores energy, which can be transferred on the IOET.

Instead of spirally winding two wires in the same direction, one of the spirals can have the opposite winding direction. Therefore, the two spirals are not on the same physical plane in this case. When you need or want to have a flexible circuit, or when you want to have several coil layers to increase the magnetic capacity and capacitance of the resonator, you can take advantage of it. All of the above configurations have transmission line characteristics and multiple resonance frequencies. The distribution network of equivalent resistance, capacitance, inductance and coupled inductance can further simulate electrical behavior. By selecting the geometric structure and material properties of the interface and the spiral, the value of the distributed element can be controlled, thereby controlling the electrical behavior of its end structure, including resonance frequency, impedance, gain, and phase.

Description of the drawings

Figures 1A and 1B show a basic spiral used in the present invention, and a two-wire spiral configuration.

Figures 2A and 2B show an embodiment of a planar resonator according to the present invention, and cross-sectional slices of the spiral and IOET.

Figure 2C shows an alternative configuration in which the insulator and the spiral are arranged in the base material 240,241.

Figure 3 is a schematic cross-sectional view of a spiral wound around an IOET.

Fig. 4 shows an approximate equivalent circuit of the spiral configuration shown in Fig. 1A.

Fig. 5 shows an approximate equivalent circuit of the spiral configuration shown in Fig. 1B.

Figures 6 and 7 show schematic configurations of spirals that are designed so that the present invention functions as a series resonator and a parallel resonator.

8A and 8B respectively show a schematic diagram of a series structure and a diagram of the relationship between impedance and frequency.

A typical impedance curve is drawn around the first resonant frequency, and L and C indicate mainly inductive behavior or capacitive behavior, respectively.

Figures 8C, 8D and 8E show schematic diagrams of the parallel structure, diagrams of the relationship between impedance and frequency, and a schematic diagram of the capacitance used for energy storage between two spiral coils.

Figures 8F and 8G show two different configurations where energy can enter and exit the structure through electrical coupling.

9A to 9C respectively show a cross section of a planar resonator according to the present invention, a top view of two coils, and a reduced-order equivalent circuit.

Figure 10 shows the equivalent top and bottom parallel resonator circuits, illustrating how IOET works on the resonator, transferring electrical energy in the form of mixed electrical energy and magnetic energy.

Fig. 11 is a schematic diagram of an equivalent circuit of a series resonant battery charger according to the present invention.

FIG. 12 is a schematic diagram of a feedback transformer according to the instant invention. Specific implementation The following description is for illustration only and not as a limitation. Many different structures are also within the spirit of the present invention and the scope of the appended claims.

Figures 1A-1B show variations of a desperately integrated resonator according to one aspect of the present invention. The integrated resonator is obtained by storing electrical energy in a part of the structure (geometric) time energy function, and also storing magnetic energy in a part of the same function.

FIG. 1A shows an example of a basic spiral 100, and FIG. 1B shows a double-wire spiral 200. Of course, those of ordinary skill in the art should understand that the present invention is not limited to spirals and double-wire spirals, and any number of spiral windings (multi-wires) can be used as needed. As shown in FIG. 2, the plane 200 has a spiral 210 wound on the top surface of the energy transfer interface (IOET) 215, and another spiral (not shown) wound on the bottom surface 220 of the energy transfer interface (IOET) . The axis, inner diameter and outer diameter of the spiral on the top surface of the IOET approximately correspond to the spiral on the bottom surface of the IOET.

FIG. 2B shows a cross-section of the spiral 210 shown in FIG. 2A. It can be seen from the cross section that the spiral has conductors 225, 230 separated by IOET. Setting the IOET layer between the spirals with a magnetic coupling coefficient (that is, sharing the same magnetic flux) allows the integrated resonator to store electrical energy, which is part of the structure time energy function for storing magnetic energy.

It should be noted that when FIG. 2B shows an IOET with spiral conductors arranged up and down, the IOET need not be a substrate. As shown in FIG. 2C, the IOET is arranged between the substrates 240 and 241. The two base materials are either side of the interface 235. If 235 is an air gap, they are separated along the interface 235.

The IOET may have μr>1, or Er>1, where μr is the relative permeability of the material, and Er is the relative permittivity of the material.

Figure 3 shows an embodiment in which multiple parallel spirals or multi-wire spirals can be used. As shown in Figure 3A, "w" is equal to width and "t" is equal to thickness. The number of spiral turns and its size, as well as the connection and direction of rotation can be designed to achieve series, parallel, or series/parallel hybrid circuits.

Figures 4, 5, 6 and 7 show the spiral configuration and its equivalent circuit, where symbols such as A and B are used to distinguish the spirals. For example, FIG. 4 is the approximate equivalent circuit of FIG. 1A. As a first approximate value, the circuit can be further simplified into equivalent lumped capacitance and equivalent lumped inductance.

It should be noted that, for example, a more complex equivalent circuit model can include a transformer, and by thinking of it as a transmission line network, the complexity of this model can be extended to include higher-order effects.

With regard to Figures 6 and 7, the figures show a series resonator and a parallel resonator, respectively. It should be noted that the possible applications in Figure 6 are low-pass filters and parallel load resonant half bridges.

Regarding FIGS. 8A and 8B, a typical impedance curve is drawn around the first resonant frequency, and L and C indicate mainly inductive or capacitive behavior, respectively.

The operation of the series planar resonator in this part of the present invention is as follows: When the operating frequency is completely lower than the self-resonant frequency of the structure, there is a large amount of capacitance between each set of spirals. From the point of view of electrical energy, the series resonance The device can be thought of as a single-port network that behaves like a capacitor.

As shown in Fig. 8B, the impedance at the resonance frequency w is the smallest. At higher frequencies, the capacitance is distributed on and between the spiral windings with inductive characteristics, thereby acting as a two-port network that behaves more like a transmission line. The simplest equivalent lumped parameter circuit model includes an equivalent inductance in series with an equivalent capacitance. A more loaded and accurate model also includes a transformer, and by thinking of it as a transmission line network, the complexity of this model can be extended to include higher-order effects.

Regarding 8C and 8D, a simple equivalent circuit of a parallel resonator is shown. When the operating frequency is completely lower than the resonance frequency, the inductive behavior of the parallel resonator can be regarded as a two-port network. When the operating frequency is higher than the resonant frequency, the parallel resonator can be seen as a single-port network that behaves like a capacitor from the power point of view. The impedance is the largest at the resonance frequency.

In addition, as shown in Figures 8F and 8G, two different methods are provided to provide channels for receiving energy and outputting energy.

Figure 9A illustrates that the IOET 903 of the present invention is wider than an embodiment of a separator plate that separates two coils. As shown in the examples in Figures 9A and 9B, IOET is the space between two spirals. In this example, energy enters a coil from the insulator 905 and passes through the coil, acting as an air coil transformer. As shown in Figure 9B, there is capacitance between the coils, which can be used for energy transfer. Fig. 9C is an equivalent circuit showing the channels A1 to A4 shown in Fig. 9B. The importance of the IOET as the space between the coils is that, for example, it can be connected wirelessly, such as a wireless battery charger. In a particular example, the battery of a device (such as a mobile phone) can be charged without using physical wires to connect the power supply and the coil to transfer energy to the battery. The wireless connection allows this characteristic to be selected, assuming the frequency of the energy transferred and the coil, so that for example there is a capacitive connection between the battery and the charger.

Figure 10 shows the equivalent circuit of the top and bottom parallel resonators. It should be understood that IOET 1003 is not a collection of discrete capacitors, but a capacitance on the IOET between the top and bottom resonators. At a sufficiently high frequency, the capacity transfer will be in the form of electrical energy on the resonator. In this way, a capacitive connection is achieved, allowing the transfer of electrical energy.

Fig. 11 is a schematic diagram of an equivalent circuit of a series resonant battery charger according to the present invention. This special battery charger has a level shifter, but a charger without a level shifter can be used.

In this circuit, different spiral transformers can be used. Each spiral transformer can be simulated as a transformer with its own leakage inductance Ls and magnetizing inductance Lm, so that for a given load specification, a suitable resonant capacitance (Cr) can be calculated or simulated. In the measurement, the resonant capacitor was manually adjusted for the spiral transformer used. The partition plate can be modified into a flyback topology with a movable clamp (shown in Figure 12). When the input DC is provided from the node between C3 and C5, the resonant capacitor C2 and the rectifier diode are short-circuited, and D2 and D4 are Remove.

Fig. 12 is a schematic diagram of a flyback transformer according to the instant invention. Conduct an experiment to see if the flyback topology can be used instead of the series resonant topology. There are several advantages to using a flyback topology: one Schottky diode is required to replace the four used in the series resonant charger in Figure 10.

The loss of the rectifier diode is small (significant).

The operating frequency of the duty cycle control is fixed.

No resonant capacitor is required.

Without the resonant capacitor, it is easier to obtain charger versatility.

In the examples shown in FIGS. 11 and 12, it should be understood that various changes can be made within the spirit of the present invention and the scope of the appended claims.

The design parameters of a planar resonator include, but are not limited to, physical dimensions, including aspect ratio, relative length, conductor thickness, material properties, such as dielectric constant (or permittivity), permeability, and materials including media including IOET The loss factor, the number of spiral turns.

In addition, the planar resonator may include a device for connecting a battery charger or equipped with a device for connecting a battery charger.

Various modifications can be made to the present invention, and these modifications fall within the spirit of the present invention and the scope of the appended claims. For example, the number of layers of the resonator, the type of the IOET surface, the number and thickness of the spirals, descriptions of accessories such as batteries, etc., can be modified from the structure described in the specification and the drawings. The coil configuration can occupy more than one plane, especially when the resonator device is woven into a fabric.