IMPROVED CORELESS POWER TRANSFORMER DESIGN.

Abstract

A resonant primary coil (22) and a resonant secondary coil (23) are different in the proposed improved coreless power transformer design, where the differences between the two resonant coils are achieved in two ways: (1) in the first difference, the two resonant coil windings are made to be different; for example, to have a different number of turns, turn spacing and / or different wire sizes and (2) the second difference is with the capacitance values ​​of the two parallel capacitors each used to resonate their respective coils.

Description

This application claims the benefit of provisional application serial no. 63 / 076,009 filed on September 9, 2020, which is incorporated herein by reference in its entirety. Background of the invention Field of invention The present invention relates generally to the field of power transformers. More specifically, the present invention relates to improvements in coreless power transformers. Discussion of the previous technique The increased efficiency of coreless power transformers can be achieved by allowing multiple resonant circuits within the transformer to have unequal component values. The basic coreless transformer disclosed in Angel J. Carvajal's thesis (dated February 2, 2018), entitled "First Principles Design of Coreless Power Transformers," showcased a 4-coil coreless transformer design. In this design, all four coils are magnetically coupled, and two of these coils form separate LC resonant circuits. These two LC circuits were designed to be identical, using the same inductors and capacitors, thus ensuring that the two individual resonant circuits had the same natural resonant frequencies. In this invention, the coreless power transformer exhibits higher power transfer efficiencies when the two coupled LC resonant circuits employed in the transformer are not equal in their inductance and capacitance values, and furthermore, the natural frequencies of the two resonant circuits do not need to be equal either. Thus, the implementation of unequal resonant inductors allows added degrees of freedom in the design of coreless transformers not included in Angel's 2018 thesis due to the added variation of the inductance, the capacitance of their respective LC circuits and different magnetic couplings between the 4 coils due to the added variation in the physical structure of the coils if compared when the two resonant coils were restricted to be equal. The report titled "Overview and Status: MIT-ProlecGE Collaboration" described specific examples of coreless transformer designs with unequal resonant circuit capacitance and inductance values. The S21 transfer efficiency factor values ​​were higher than 0.98, while the same resonant circuit designs typically exhibited maximum S21 values ​​of around 0.967, as outlined in the previously granted patent publication US 2019 / 0267843 A1. The report shown above was prepared after calculating a number of different unequal resonant circuit designs. The calculated designs include a number of coreless transformer designs that achieve S21 values ​​greater than 0.98. Investigations were also carried out on coreless transformer designs with unequal resonant circuits that cpoznn / rznz / E / YiAi exhibit S21 values ​​greater than 0.98. Two specific unequal coupled resonant circuit coreless power transformer designs, one for a near-operating frequency of 150 kHz and the other for a near-operating frequency of 300 kHz, were also investigated. The measured performance of these two coreless power transformers was also investigated. These unequal coupled resonant circuit coreless power transformers exhibited higher transfer efficiency factors than those obtained with the same resonant circuit designs reported in previously granted patent publication US 2019 / 0267843 A1. In many cases, efficient designs often have capacitance ratios of 1.2–1.6 for the capacitances in the two unequal resonant circuits. The natural resonant frequencies for the two resonant circuits often have ratios of 0.95–1.05, though these values ​​are illustrative and may vary. As for the merits, characteristics, and precise advantages of the prior art, none of them achieve or fulfill the purposes of the present invention. Brief description of the invention In one embodiment, the present invention provides a transformer system comprising: four magnetically coupled coils having a fixed separation geometry comprising: an excitation coil (21) that produces magnetic fields; a load coil (24); a first resonant coil (22); a second resonant coil (23); the following six magnetic couplings exist between the four magnetically coupled coils: a first magnetic coupling between the excitation coil (21) and the first resonant coil (22), a second magnetic coupling between the first resonant coil (22) and the second resonant coil (23), a third magnetic coupling between the second resonant coil (23) and the load coil (24), a fourth magnetic coupling between the excitation coil (21) and the second resonant coil (23),a fifth magnetic coupling between the first resonant coil (22) and the load coil (24) and a sixth magnetic coupling between the excitation coil (21) and the load coil (24), the excitation coil (21) producing magnetic fields and the first resonant coil (22) being magnetically coupled with the excitation coil (21) producing energy that is stored by the first resonant coil (22) and the second resonant coil (23) being magnetically coupled with the first resonant coil (22) to propagate the energy that is stored in the first resonant coil (22) to the second resonant coil (23) without using a magnetic core,wherein the second resonant coil (23) is then magnetically coupled with the loading coil (24) where energy is transferred to the loading coil (24) and wherein the first resonant coil (22) and the second resonant coil (23) are different in at least one or a combination of the following: (a) the first resonant coil (22) and the second resonant coil (23) have a different number of turns, (b) the first resonant coil (22) and the second resonant coil (23) have a different turn spacing and (c) the first resonant coil (22) and the second resonant coil (23) have different wire sizes. croznn / rznz / E / γΐΛΐ In another embodiment, the present invention provides a transformer system comprising: four magnetically coupled coils having a fixed separation geometry comprising: an excitation coil (21) that produces magnetic fields; a load coil (24); a first resonant coil (22); a second resonant coil (23); the following six magnetic couplings exist between the four magnetically coupled coils: a first magnetic coupling between the excitation coil (21) and the first resonant coil (22), a second magnetic coupling between the first resonant coil (22) and the second resonant coil (23), a third magnetic coupling between the second resonant coil (23) and the load coil (24), a fourth magnetic coupling between the excitation coil (21) and the second resonant coil (23),a fifth magnetic coupling between the first resonant coil (22) and the load coil (24) and a sixth magnetic coupling between the excitation coil (21) and the load coil (24), the excitation coil (21) producing magnetic fields and the first resonant coil (22) being magnetically coupled with the excitation coil (21) producing energy that is stored by the first resonant coil (22) and the second resonant coil (23) being magnetically coupled with the first resonant coil (22) to propagate the energy that is stored in the first resonant coil (22) to the second resonant coil (23) without using a magnetic core,wherein the second resonant coil (23) is then magnetically coupled with the loading coil (24) where energy is transferred to the loading coil (24) and wherein the capacitance values ​​of two parallel capacitors used to resonate the first resonant coil (22) and the second resonant coil (23) are different. In yet another embodiment, the present invention provides a method for implementing energy transfer with four magnetically coupled coils comprising: producing magnetic fields using an excitation coil (21); providing a magnetically coupled load coil (24); magnetically coupling the excitation coil (21) and a first resonant coil (22); magnetically coupling the first resonant coil (22) and a second resonant coil (23); magnetically coupling the second resonant coil (23) and the load coil (24); magnetically coupling the excitation coil (21) and the second resonant coil (23); magnetically coupling the first resonant coil (22) and the load coil (24);magnetically couple the excitation coil (21) and the loading coil (24) and take the first resonant coil (22) and the second resonant coil (23) to be different in at least one or a combination of the following ways: (a) the first resonant coil (22) and the second resonant coil (23) have a different number of turns, (b) the first resonant coil (22) and the second resonant coil (23) have a different turn spacing, and (c) the first resonant coil (22) and the second resonant coil (23) have different wire sizes, or (d) the capacitance values ​​of two parallel capacitors used to resonate either the first resonant coil (22) or the second resonant coil (23) are different. Brief description of the drawings Figure 1 shows a schematic diagram illustrating a representation of damping circuits of the inventive coreless 4-coil transformer. croznn / rznz / E / YiAi Figure 2 shows a schematic diagram illustrating the inventive coreless 4-coil transformer system with the coils fitted. Figure 3 depicts two example low-loss coreless transformer coil configurations with asymmetrical resonant coils. Figure 4 shows images of the physical arrangement of the four coils for the 150 kHz design. Figure 5 shows the winding arrangement as side cut views for the 150 kHz and 300 kHz transformer designs. Figure 6 shows images of coreless power transformers constructed at 150 kHz and 300 kHz with asymmetrical resonant coils. Figure 7 shows the calculated and measured performance of the transformer without an asymmetric core. Figure 8 depicts the 1 kW total power test establishment with a 300 kHz low loss coreless power transformer. Description of preferred modalities While this invention is illustrated and described in a preferred embodiment, the device can be produced in many different configurations, shapes, and materials. A preferred embodiment of the invention is also depicted in the drawings and will be described in detail herein, it being understood that this description is to be regarded as an example of the principles of the invention and the associated functional specifications for its construction, and is not intended to limit the invention to the illustrated embodiment. Those skilled in the art will consider many other possible variations within the scope of the present invention. The design of coreless power transformers with good transfer efficiency was demonstrated in the thesis by Angel J. Carvajal (dated February 2, 2018) entitled “First Principles Design of Coreless Power Transformers.” The work in this thesis provided a foundation in physics for the detailed calculations related to the windings of a multi-coil coreless transformer. This physics-based calculation allowed for the determination of the transformer's performance based on its physical components and their arrangement. The thesis also provided experimental confirmation of both the individual stages within the calculation and the overall performance of the transformer.In this thesis, the arrangement of coreless 4-coil transformers was revealed, where 2 of these 4 coils were coupled, in a resonant manner, and provided an improved magnetic link between a separate input excitation coil and a separate output load coil. To quantify the performance of a high-frequency transformer, the S-parameter transfer coefficient S21 provides a good measure of the transformer's efficiency. If operated under comparable real impedance conditions, the efficiency can be determined by squaring the S21 value 100 times to obtain percentage values. For example, in the thesis by croznn / rznz / E / YiAi In Carvajal's thesis, a calculated S21 value of 0.967 and a measured value of 0.96 were obtained. Therefore, the efficiency of the compared condition of the coreless transformer design example corresponds to 93.5% calculated and 92% measured. Note that higher energy efficiency corresponds to lower losses; in this case, the corresponding energy losses were 6.5% and 8%, respectively. Lower loss efficiency is a very valuable characteristic in power transformers because losses represent wasted energy lost as heat and represent a loss in revenue. The proposed improved design of coreless power transformers can increase these energy efficiency values ​​to 96% or more and, therefore, can reduce losses accordingly to 4% or less. This improved performance was achieved by adding enhancements to the physics-based analytical calculations presented in Carvajal's previously described thesis. New variables were included to account for the differences in the two resonant coils. A mechanism for automatically repeating these calculations is added, where the control parameters are varied in each cycle to maintain variations that produce improved S21 performance results. These calculations are repeated with any improvements retained, so that an improved design is developed after many cycles.The result of this added improvement to the basic physics calculations was the ability to analytically search through many design variations (even many hundreds) and establish those that performed best. The result of applying this enhanced analytical capability was the determination that certain transformer design properties produce better power transfer efficiencies and, therefore, fewer losses. The specific coreless power transformer property discussed herein relates to the two resonant coils. In Carvajal's thesis, the design for the two resonant coils was identical and included parallel capacitors of the same value in each coil. Thus, the resonant frequency and all parameters of each of these two resonant coils were established as equal. In the improved coreless transformer design presented herein, and in contrast to the two identical resonant coils, intentionally different resonant coils are employed. The 4-coil system 10 includes a source voltage (Vsource) with a source impedance (Rsource) denoted by a source element 6, two resonant coils denoted as the resonant primary coil 2 and the resonant secondary coil 3, an excitation coil 1, and a load coil 4 connected with the output load impedance (Rload) defined by a load 8, as shown in Figure 1. Each coil 1-4 is represented by its damped series inductance L1, L2, L3, L4 and the equivalent resistance circuit R1, R2, R3, R4, respectively. The resonant coils 2 and 3 each include their coil and a damped capacitor connected in parallel, C1 and C2. When a high-frequency signal feeds the excitation coil 1, the resulting magnetic field excites the resonant primary coil 2, which stores the energy in the same way as an LC tank circuit.The magnetic field of the excitation coil 1 also influences the resonant secondary coil 3 and the load coil 4 (though not to the same degree). A critical interaction occurs between the two resonant coils, which act as near-ideal low-loss resonators and propagate energy between them. All four coils are inductively coupled to each other to provide efficient energy transfer from the excitation coil to the load coil. The two resonant coils are different, allowing for a greater range of variation in the three respective coupling coefficients of each coil. This enables improved combinations of magnetic coupling coefficients for energy transfer from the excitation coil to the load coil, where the energy is then transferred to the load device. For a set of N coils in close proximity to each other, there will be (N-1) factorial coupling coefficients that describe all the magnetic links between all the coils. Therefore, since there are 4 coils in this system, there are six coupling coefficients that are determined by the geometry of each coil and its relative position with respect to the others: K12, K13, K14, K23, K24, and K34. Each Kxy refers to the coupling coefficient between coil-X and coil-Y. Figure 1 shows this damped equivalent circuit and the corresponding magnetic coupling coefficients. There are a large number of design options for the physical placement of the four coils in these systems. The four coils can be positioned in space in a plurality of ways. The resonant coils can be placed outside the excitation and load coils, or they can be fitted inside their respective excitation / load coils, or even all the coils can be fitted inside one another. As noted previously, all coils are coupled in the 4-coil system and the goal is to transfer energy efficiently from the excitation coil to the load coil. Figure 2 shows a schematic diagram illustrating an example of the 4-coil system 20 used according to the invention. While all coils are magnetically coupled, it is desirable to have the excitation coil 21 strongly coupled to the resonant primary coil 22, so that the resonant primary coil 22 can receive energy from the excitation coil 21 (having a higher K-value associated with its coupling). The same applies to coils 24 and 23. The loading coil 24 is strongly coupled to the second resonant coil to assist in extracting energy from the resonant secondary coil 23. To improve these couplings, coils 21 and 22 should be in close proximity or nested within each other, and coils 23 and 24 should be in close proximity or nested within each other. For the 4-coil system in Figure 2, the excitation coil 21 has a diameter of Y1 and a length of X1, while the resonant primary coil 22 has a diameter of Y2 and a length of X2. The excitation coil 21 comprises N1 turns of one wire element, and the loading coil has N4 turns of another wire element. The resonant primary coil 22 has N2 turns, and the resonant secondary coil 23 has N3 turns of their wire elements. Note that all four coils can have different wire elements. The resonant secondary coil 23 has a length of X3. Also, the distance between the resonant primary coil 22 and the resonant secondary coil 23 is the distance b. The wire radius of the wire associated with the resonant primary coil 22 is Ai and the center-to-center distance of the resonant primary coil 22 is 2Ci.The wire radius of the wire associated with the resonant secondary coil 23 is A2 and the center-to-center distance of the resonant primary coil 23 is 2C2. As noted above, the primary resonant coil 22 and the secondary resonant coil 23 differ in the present invention compared to what was described in Carvajal's thesis (which required similar resonant coils). The differences between the two resonant coils are achieved in two ways: (1) the two resonant coil windings are made to be different, for example, by having a different number of turns, a different turn spacing, and / or different wire sizes; and (2) the capacitance values ​​of the two parallel capacitors, each of which is used to resonate its respective coil, are also different.The amount of difference in the resonant coil and capacitance values ​​can vary, although the range of typical examples with differences in the number of turns less than 2 folds, a turn spacing less than 2 folds and a wire size less than 2 folds and parallel capacitor differences less than 3 folds. As an example, a 1 kW coreless transformer with an output-to-input voltage ratio of 4 and S21 values ​​of 0.98 or higher (low-loss designs) can be achieved with the first and second resonant coils having coil turns ratios that can fluctuate within a modest amount of difference. Example 1 kW designs featured turns ratios (first coil turns / second coil turns N3): (N2 / N3) of (8 / 11), (9 / 11), (8 / 12), (7 / 8), (7 / 9), (6 / 9), (6 / 8). Therefore, in these examples, the first coil had 6-9 turns, while the second coil had 8-12 turns. It is observed in these example designs that the difference in the two resonant coils was achieved when the number of turns in the second coil was larger than the number of turns in the first coil.Additionally, the coils may differ according to the spacing between adjacent turns in the coil, and this spacing difference can change by 10% or more. The ratio of resonant parallel capacitance values ​​in these example 1 kW high efficiency low loss designs defined as (first coil capacitance Cr / second coil capacitance C2) = (C1 / C2) fluctuates through 1.62, 1.52, 2.20, 1.83, 1.60, 2.39, 2.54, 2.22, 2.05, 1.32, 1.67, 1.34, 2.10, 1.93, 2.03, 1.32, 1.50, 1.51, 1.17, 1.59, 1.28, 1.88, 1.29, 1.30. Therefore, in these example designs, this parallel capacitance value ratio (C1 / C2) had a variation close to one to about 2.5. The resonant coil inductance values, L, are determined by the number of turns, the spacing between turns, the wire diameter, and the coil radius. In the previous 1 kW design examples, these inductance values ​​varied, and the resulting difference in inductance values ​​for the first (L2) and second (L3) resonant coils can be expressed as the ratio of inductances (the inductance of the first coil, L2, to the inductance of the second coil, L3). Typically, this inductance ratio (L2 / L3) was less than one, so the inductance of the second coil was greater than the inductance of the first coil. However, in other designs, this ratio can be greater than one. The resonant frequency fr of an isolated low-loss LC tank circuit (inductor-capacitor) is related to the product of the corresponding values ​​L and C. fr = 1 / (2TnÍLC)[Hz] For these low-loss example designs, the different L and C values ​​of the two resonant coils resulted in different resonant frequencies. The amount of frequency difference between the two resonant coils in a transformer can be expressed as the ratio of the two frequencies (the frequency of the first coil / frequency of the second coil), and for the low-loss example designs, this frequency ratio was typically in the range of 0.8–1.2. The low-loss example designs had resonant capacitance ratios (C1 / C2) of around 1.3 and resonant inductance ratios (L2 / L3) of around 0.77, although they could also have larger and smaller ratio values ​​than these. The technical basis for the improved low-loss performance when the two resonant coils in a coreless transformer are different appears to be associated with the inherent asymmetry of the transformer windings caused by the need for a non-unity transformer voltage ratio—a ratio that increases or decreases the output voltage relative to the input voltage. Typical output / input voltage ratios for a step-down transformer can be as small as 2 or as large as 20 or more. A step-down transformer would have opposing winding ratios. In either case, to achieve a substantially larger output voltage relative to the input voltage, windings with more turns are used in the transformer's output / load winding compared to its input / excitation winding. Thus, the preferred overall structure of the coreless transformer includes a magnetically coupled excitation coil with three other coils, including a first resonant coil, which is also magnetically coupled with three other coils, including a second resonant coil. This second resonant coil is magnetically and resonantly different from the first resonant coil. An output coil is magnetically coupled with the other three coils, including the second resonant coil. The output coil is connected to the load device. The input coil is excited at the design frequency, typically by switched-mode electronic output power devices, such as an H-bridge excitation circuit or a sinusoidal power source.A larger desired output voltage compared to the input voltage causes asymmetrical coil characteristics where the output coil has more turns than the input coil and the second resonant coil has more turns than the first resonant coil. Two example low-loss coreless transformer arrangements are shown in Figure 3. Both employ coil formers with an OD of 20.32 cm (8 inches) and are designed for 1 kW of power with a voltage ratio of 4:1. Both employ the second resonant coils with more turns than the first resonant coil. croznn / rznz / E / YiAi It is also observed that, as revealed in Carvajal's thesis, there are six magnetic coupling coefficients that link to the four coils in the coreless transformer, and that these six magnetic coupling coefficients remain part of the coreless design for transformers with asymmetric resonant coils. Typical values ​​for the magnetic coupling coefficients are often close: K12 = 0.7, K13 = 0.3, K14 = 0.3, K23 = 0.3, K24 = 0.3, and K34 = 0.7, although they can fluctuate substantially differently from these. In addition to functioning in asymmetric coreless transformer designs, specific designs were developed for two examples with a power rating of 1 kW. One of these two was designed for operation at a frequency of approximately 150 kHz, and the second was designed for operation at a frequency of approximately 300 kHz. These demonstrated that the asymmetric resonant coil design procedure was valid regardless of the operating frequency. Both implemented resonant coils with different numbers of turns: 9 and 12 turns for the 150 kHz design, and 7 and 10 turns for the 300 kHz design. These two 1 kW coreless transformer designs were built and tested experimentally. The test results confirmed the improved low-loss performance achieved with the asymmetric resonant coils. Figure 4 shows images of the physical arrangement of the 4 coils for the 150 kHz design, and Figure 5 represents the winding arrangement as side cut views for the 150 kHz and 300 kHz transformer designs. Figure 6 shows images of the coreless power transformers constructed at 150 kHz and 300 kHz with asymmetrical resonant coils. The calculated and measured values ​​for the parameter coefficient S21 are given in Figure 7, for both the 150 kHz and 300 kHz designs. There is excellent agreement between the calculated and measured experimental values. The setup for the full 1 kW power test of the 300 kHz low-energy coreless power transformer is shown in Figure 8. This image shows the excitation power electronics, measuring probes, the 1 kW high-frequency resistive load, and the 300 kHz coreless transformer. The standard off-the-shelf power supplies used to provide DO power to the excitation power electronics are not shown in the image. Conclusion A system and method for the effective implementation of an improved coreless transformer design have been shown in the preceding embodiments. While several preferred embodiments have been shown and described, it is understood that this description is not intended to limit the invention, but rather to cover all modifications and alternative constructions that fall within the spirit and scope of the invention, as defined in the appended claims. For example, the present invention is not limited by size, materials, or specific manufacturing techniques.

Claims

1. A transformer system comprising: four magnetically coupled coils having a fixed separation geometry comprising: an excitation coil (21) producing magnetic fields; a load coil (24); a first resonant coil (22); a second resonant coil (23); the following six magnetic couplings existing between the four magnetically coupled coils: a first magnetic coupling between the excitation coil (21) and the first resonant coil (22), a second magnetic coupling between the first resonant coil (22) and the second resonant coil (23), a third magnetic coupling between the second resonant coil (23) and the load coil (24), a fourth magnetic coupling between the excitation coil (21) and the second resonant coil (23),a fifth magnetic coupling between the first resonant coil (22) and the load coil (24) and a sixth magnetic coupling between the excitation coil (21) and the load coil (24), the excitation coil (21) producing magnetic fields and the first resonant coil (22) being magnetically coupled with the excitation coil (21) producing energy that is stored by the first resonant coil (22) and the second resonant coil (23) being magnetically coupled with the first resonant coil (22) to propagate the energy that is stored in the first resonant coil (22) to the second resonant coil (23) without using a magnetic core, wherein the second resonant coil (23) is then magnetically coupled with the load coil (24) where the energy is transferred to the load coil (24),and wherein the first resonant coil (22) and the second resonant coil (23) differ in at least one or a combination of the following: (a) the first resonant coil (22) and the second resonant coil (23) have a different number of turns, (b) the first resonant coil (22) and the second resonant coil (23) have a different turn spacing, and (c) the first resonant coil (22) and the second resonant coil (23) have different wire sizes.

2. The transformer system according to claim 1, wherein each of the differences in (a), (b), or (c) are less than 2 folds.

3. The transformer system according to claim 1, wherein the first resonant coil (22) has N2 turns and the second resonant coil (23) has N3 turns, wherein N3>N2.

4. The transformer system according to claim 1, wherein the first resonant coil (22) has N2 turns and the second resonant coil (23) has N3 turns, wherein N2 is taken to be in the following range: 6 < N2 < 9 and N3 is taken to be in the following range: 7 < N3 < 12. croznn / rznz / E / YiAi 5. The transformer system according to claim 1, wherein the difference in the different turn separation between the first resonant coil (22) and the second resonant coil (23) is at least 5%.

6. The transformer system according to claim 1, wherein the transformer system operates at an operating frequency taken in the following range: 100-300 kHz.

7. The transformer system according to claim 1, wherein the first resonant coil (22) and the excitation coil (21) are inductively coupled.

8. The transformer system according to claim 1, wherein the second resonant coil (23) and the load coil (24) are inductively coupled.

9. The transformer system according to claim 1, wherein the excitation coil (21), the first resonant coil (22), the second resonant coil (23) and the load coil (24) each have a circuit representation damped by the circuit elements L, C and R and their mutual magnetic couplings.

10. The transformer system according to claim 1, wherein the magnetic coupling between the four magnetically coupled coils is used to determine the performance of the transformer system.

11. A transformer system comprising: four magnetically coupled coils having a fixed separation geometry comprising: an excitation coil (21) producing magnetic fields; a load coil (24); a first resonant coil (22); a second resonant coil (23); the following six magnetic couplings existing between the four magnetically coupled coils: a first magnetic coupling between the excitation coil (21) and the first resonant coil (22), a second magnetic coupling between the first resonant coil (22) and the second resonant coil (23), a third magnetic coupling between the second resonant coil (23) and the load coil (24), a fourth magnetic coupling between the excitation coil (21) and the second resonant coil (23),a fifth magnetic coupling between the first resonant coil (22) and the load coil (24) and a sixth magnetic coupling between the excitation coil (21) and the load coil (24), the excitation coil (21) producing magnetic fields and the first resonant coil (22) being magnetically coupled with the excitation coil (21) producing energy that is stored by the first resonant coil (22) and the second resonant coil (23) being magnetically coupled with the first resonant coil (22) to propagate the energy that is stored in the first resonant coil (22) to the second resonant coil (23) without using a magnetic core, wherein the second resonant coil (23) is then magnetically coupled with the load coil (24) where the energy is transferred to the load coil (24),and where the capacitance values ​​of two parallel capacitors used to resonate the first resonant coil (22) and the second resonant coil (23) are different.

12. The transformer system according to claim 11, wherein the difference in capacitance values ​​is less than 3 folds.

13. The transformer system according to claim 12, wherein the difference in capacitance values ​​is between 1-2½ folds.

14. The transformer system according to claim 11, wherein the transformer system operates at an operating frequency taken in the following range: 100-300 kHz.

15. The transformer system according to claim 11, wherein the first resonant coil (22) and the excitation coil (21) are inductively coupled.

16. The transformer system according to claim 11, wherein the second resonant coil (23) and the load coil (24) are inductively coupled.

17. The transformer system according to claim 11, wherein the excitation coil (21), the first resonant coil (22), the second resonant coil (23) and the load coil (24) each have a circuit representation damped by the circuit elements L, C and R and their mutual magnetic couplings.

18. The transformer system according to claim 11, wherein the magnetic coupling between the four magnetically coupled coils is used to determine the performance of the transformer system.

19. A method of implementing energy transfer with four magnetically coupled coils comprising: producing magnetic fields using an excitation coil (21); providing a magnetically coupled load coil (24); magnetically couple the excitation coil (21) and a first resonant coil (22); magnetically couple the first resonant coil (22) and a second resonant coil (23); magnetically couple the second resonant coil (23) and the load coil (24); magnetically couple the excitation coil (21) and the second resonant coil (23); magnetically couple the first resonant coil (22) and the load coil (24);magnetically couple the excitation coil (21) and the loading coil (24), and take the first resonant coil (22) and the second resonant coil (23) to be different in at least one of or a combination of the following: (a) the first resonant coil (22) and the second resonant coil (23) have a different number of turns, (b) the first resonant coil (22) and the second resonant coil (23) have a different turn spacing, and (c) the first resonant coil (22) and the second resonant coil (23) have different wire sizes, or (d) the capacitance values ​​of two parallel capacitors used to resonate either the first resonant coil (22) or the second resonant coil (23) are different.

20. The method according to claim 19, wherein each of the differences in (a), (b), (c) or (d) are less than 2 folds.

21. The method according to claim 19, wherein the first resonant coil (22) has N2 turns and the second resonant coil (23) has N3 turns, wherein N3>N2.

22. The method according to claim 19, wherein the first resonant coil (22) has N2 turns and the second resonant coil (23) has N3 turns, wherein N2 is taken to be in the following range: 6 < N2 < 9 and N3 is taken to be in the following range: 7 < N3 < 12.

23. The method according to claim 19, wherein the difference in the different turn separation between the first resonant coil (22) and the second resonant coil (23) is at least 5%.

24. The method according to claim 19, wherein the transformer system operates at an operating frequency taken in the following range: 100-300 kHz.

25. The method according to claim 19, wherein the first resonant coil (22) and the excitation coil (21) are inductively coupled.

26. The method according to claim 19, wherein the second resonant coil (23) and the loading coil (24) are inductively coupled.

27. The method according to claim 19, wherein the excitation coil (21), the first resonant coil (22), the second resonant coil (23) and the loading coil (24) each have a circuit representation damped by the circuit elements L, C and R and their mutual magnetic couplings.

28. The method according to claim 19, wherein the magnetic coupling between the four magnetically coupled coils is used to determine the performance of the transformer system.

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