Wireless power transfer with generalized harmonic currents

Abstract

The present disclosure provides "Wireless power transfer with generalized harmonic currents". A wireless charging device has a primary side circuit including a voltage source, a switch, and a primary coil arranged to couple with a secondary coil. The primary side circuit forms a series resonant converter when transferring power from the primary coil to the secondary coil. The wireless charging device also includes a controller to selectively activate the switch to cause the transfer such that for each fundamental period, a pair of consecutive effective resonant periods have the same polarity.

Description

Technical Field

[0001] This disclosure relates to battery charging via wireless power transmission. Background Technology

[0002] The increasing electrification of automobiles has increased the demand for available charging stations that support vehicle electrification. These charging stations can provide either plug-in (wired) or wireless options. Summary of the Invention

[0003] A wireless charging device has a primary-side circuit including a voltage source, a switch, and a primary coil arranged to couple with a secondary coil, and configured to form a series resonant converter when transferring power from the primary coil to the secondary coil. The wireless charging device also includes a controller configured to selectively activate the switch to induce the transfer, such that for each fundamental cycle, a pair of consecutive effective resonant cycles have the same polarity.

[0004] A wireless charger has a primary-side circuit including a switch and a primary coil arranged to couple with a secondary coil, and configured to form a series resonant converter during power transmission. The wireless charging device also includes a controller configured to selectively activate the switch to induce transmission, such that for each fundamental cycle, the quotient of the total number of resonant cycles to the total number of effective resonant cycles has a non-integer value.

[0005] A wireless charger has a primary-side circuit including a switch and a primary coil arranged to couple with a secondary coil, and configured to form a series resonant transducer during power transmission. The wireless charger also includes a controller configured to selectively activate the switch to induce transmission, such that for each fundamental cycle, the quotient of the total number of resonant cycles and the total number of effective resonant cycles has an integer value greater than one, and the total number of effective resonant cycles is greater than one. Attached Figure Description

[0006] Figure 1 This is a schematic diagram of a wireless power transmission system.

[0007] Figure 2A yes Figure 1 A graph showing the startup timing of the switching elements.

[0008] Figure 2B It is based on Figure 2A The startup sequence is generated by the operation of the switching elements. Figure 1 The curves of Vab and Ip versus time.

[0009] Figure 2C It is based on Figure 2AThe startup sequence is generated by the operation of the switching elements. Figure 1 The curve of Vo versus time.

[0010] Figure 3A It is more suitable for power transmission via fundamental current. Figure 1 The waveforms of Vab and Ip are plotted.

[0011] Figure 3B and Figure 3C This compares power transmission via third-order fixed harmonic current and fifth-order fixed harmonic current, respectively. Figure 1 The waveforms of Vab and Ip are plotted.

[0012] Figure 4A and Figure 4B It is compared to power transmission via 3X generalized harmonic current. Figure 1 The waveforms of Vab and Ip are plotted.

[0013] Figures 5A to 5E It is compared to power transmission via 2X generalized harmonic current. Figure 1 The waveforms of Vab and Ip are plotted.

[0014] Figure 6A and Figure 6B It is compared to power transmission via 1.5X generalized harmonic current. Figure 1 The waveforms of Vab and Ip are plotted.

[0015] Figure 7A yes Figure 1 Another curve showing the startup timing of the switching element.

[0016] Figure 7B It is based on Figure 7A The startup sequence is generated by the operation of the switching elements. Figure 1 The curves of Vab and Ip versus time.

[0017] Figure 7C It is based on Figure 7A The startup sequence is generated by the operation of the switching elements. Figure 1 The curve of Is versus time.

[0018] Figure 7D It is based on Figure 7A The startup sequence is generated by the operation of the switching elements. Figure 1 The curve of Vo versus time. Detailed Implementation

[0019] Various embodiments of this disclosure are described herein. However, the disclosed embodiments are merely exemplary, and other embodiments may take various and alternative forms not explicitly shown or described. These drawings are not necessarily drawn to scale; certain features may be enlarged or minimized to show details of particular components. Therefore, the specific structural and functional details disclosed herein should not be construed as limiting, but merely as a representative basis for teaching those skilled in the art to use the invention in various ways. As will be understood by those skilled in the art, various features shown and described with reference to any of the drawings may be combined with features shown in one or more other drawings to produce embodiments not explicitly shown or described. The combinations of features shown provide representative embodiments for typical applications. However, various combinations and modifications of features consistent with the teachings of this disclosure may be desired for particular applications or implementations.

[0020] Wireless power transfer is a convenient and potentially autonomous device for charging electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs). Figure 1 A typical wireless power transmission circuit 10 with a series resonant converter (SRC) architecture is shown. The wireless power transmission circuit 10 includes a primary side 12 and a secondary side 14. The primary side 12 includes a voltage source 16, switching elements 18a-18d, a capacitor 20, and a primary coil 21. The primary coil 21 is represented as a primary-side leakage inductance 22, a magnetizing inductance 24, and a winding 26. The primary side 12 also includes a controller 27. The voltage source 16 and the switching elements 18a-18d are connected in parallel. The capacitor 20 and the primary-side leakage inductance 22 are connected in series. The magnetizing inductance 24 and the winding 26 are connected in parallel. The controller 27 controls the operation of the switching elements 18a-18d.

[0021] The secondary side 14 includes a secondary coil 28. The secondary coil 28 is represented by a winding 29 and a secondary leakage inductance 30. The secondary side 14 also includes a capacitor 32, a diode 34 forming a rectifier, a capacitor 36, and a resistor 38. The winding 29, the secondary leakage inductance 30, and the capacitor 32 are connected in series. The diode 34, the capacitor 36, and the resistor 38 are connected in parallel. As will be apparent to those skilled in the art, the primary coil 21 and the secondary coil 28 form a transformer 40.

[0022] Figure 2A-2C Typical operation of the wireless power transmission circuit 10 is illustrated. In this document, Vin is the voltage of voltage source 16, Vab is the voltage at the output terminals of switching elements 18a-18d, Ip is the current in primary coil 21, and Vo is the voltage across resistor 38. Figure 2A The controller 27 is described in detail for generating Figure 2BThe controller 27 alternately activates switching elements 18a, 18d and switching elements 18b, 18c. That is, when switching elements 18a, 18d are turned on, switching elements 18b, 18c are turned off, and vice versa. Therefore, Figure 2A-2C The wireless power transmission via the fundamental frequency is shown.

[0023] It may be desirable to operate the wireless power transmission circuit 10 at a high resonant frequency to reduce the size and cost of passive components. For EV / PHEV chargers with higher power levels (e.g., several kilowatts), high-current IGBTs instead of MOSFETs are typically used as switching elements 18a-18d (which can operate up to about 20 kHz). Therefore, the resonant / operating frequency is usually limited by the power devices.

[0024] Some have suggested wireless power transmission via odd-order harmonic currents (e.g., third, fifth, seventh, etc.). This is in contrast to transmission via... Figure 2A-2C Compared to the power transmission via the fundamental current shown, this technology's system resonant / operating frequency is Q times higher than the switching frequency of the power device (where Q equals the harmonic order). Therefore, it has a higher resonant frequency, reducing the size and cost of passive components while achieving a relatively low switching frequency. Furthermore, load regulation and input voltage regulation can be achieved by selecting different harmonic orders to keep soft switching within the entire operating range. Figures 3A-3C A comparison is shown between power transmission via the fundamental current and power transmission via the third and fifth harmonic currents.

[0025] Due to the harmonic selectivity of the SRC circuit, the resonant current frequency will remain constant under different voltage modes. Therefore, by rearranging the position and number of effective resonant periods with effective voltage output (Vab = +Vdc or -Vdc), we propose using a method other than the reference... Figures 3A-3C The discussion focuses on additional, unintended methods for wireless power transmission, using harmonic currents other than the fixed odd-order harmonic currents.

[0026] Since the concept of harmonics in this paper differs from the conventional concept of harmonics, we define the generalized harmonic order X as the total number of resonant periods divided by the total number of effective resonant periods over a fundamental period. Similarly, an effective resonant period refers to the resonant period with an effective voltage output.

[0027] Figure 4A and Figure 4B This illustrates wireless power transmission with different implementations of the 3X generalized harmonic order by rearranging the position of the effective voltage period relative to a fixed odd-order harmonic implementation. Figure 4AIn this system, a fundamental frequency period consists of six resonant periods and two effective resonant periods of opposite polarity. The effective resonant periods are adjacent to each other. Figure 4B In this system, a fundamental frequency cycle consists of eighteen resonant cycles and six effective resonant cycles (two groups of three). Within each group, the effective resonant cycles are again adjacent to each other, but this is not mandatory. All such implementations have the same power delivery and the same output voltage.

[0028] Similarly, different generalized harmonic orders are possible by rearranging the position and number of effective voltage cycles. Any NX generalized harmonic order with N greater than or equal to 1 is possible. The smaller the value of N, the more effective voltage states are available for power transmission, which will result in more transmitted power, less cycle current, and higher efficiency. The anticipated generalized harmonic order provides greater flexibility, which can be used for load regulation and voltage regulation, while keeping soft switching in the full operating range.

[0029] Figures 5A-5E This illustrates wireless power transmission with different implementations of the 2X generalized harmonic order by rearranging the position of the effective voltage period relative to a fixed odd-order harmonic implementation. Figure 5A In this system, a fundamental frequency period consists of four resonant periods and two effective resonant periods of opposite polarity. The effective resonant periods are adjacent to each other. Figure 5B In a fundamental frequency cycle, there are six resonant periods and three effective resonant periods. Two of these three effective resonant periods are adjacent to each other and have opposite polarities. Figure 5C In this system, a fundamental frequency cycle consists of six resonant periods and three effective resonant periods. These three effective resonant periods are adjacent to each other and have alternating polarities. Figure 5D In this system, a fundamental frequency cycle consists of six resonant periods and three effective resonant periods. Similar to... Figure 5B Two of the three effective resonant periods are adjacent to each other and have opposite polarities. However, with Figure 5B Unlike the third effective resonant period, adjacent effective resonant periods of opposite polarity occur before the third effective resonant period. These three effective resonant periods are adjacent to each other and have alternating polarities. Figure 5E In this system, a fundamental frequency cycle consists of eight resonant periods and four effective resonant periods. The effective resonant periods are adjacent to each other and have alternating polarity. All such implementations have the same power delivery and the same output voltage. Figure 2B Compared to the fundamental current, less power is transmitted to the secondary side 14, resulting in a lower Vo.

[0030] Figure 6A and Figure 6BThis illustrates wireless power transmission with different implementations of the 1.5X generalized harmonic order by rearranging the position of the effective voltage period relative to a fixed odd-order harmonic implementation. Figure 6A In this system, a fundamental frequency period consists of six resonant periods and four effective resonant periods. The effective resonant periods have opposite polarities in adjacent pairs. Figure 6B In this system, a fundamental frequency cycle consists of six resonant periods and four effective resonant periods. The effective resonant periods are adjacent to each other and have alternating polarities. All such implementations have the same power delivery and the same output voltage.

[0031] It is worth noting that, unlike fundamental and fixed odd-order harmonic power transmission, some implementations have continuous effective resonant periods of the same polarity. For example, Figure 5B The first two effective resonant periods have the same polarity. Figure 6A The same applies to the second and third effective resonant periods.

[0032] Figures 7A-7D It shows the method for generating Figure 5A The operation of the 2X generalized harmonic order wireless power transmission circuit 10 is described. Similarly, Vin is the voltage of voltage source 16, Vab is the voltage at the output terminals of switching elements 18a-18d, Ip is the current in the primary coil 21, and Vo is the voltage across resistor 38. Furthermore, Is is the current in the secondary coil 28. Figure 7A The controller 27 is described in detail for generating Figure 7B The new square wave Vab, Figure 7C AC current Is and Figure 7D A switching scheme that produces a roughly constant output Vo across resistor 38.

[0033] During the first and second quarters of a fundamental frequency cycle, controller 27 commands switching elements 18a and 18b to open and switching elements 18c and 18d to close. During the third quarter, controller 27 commands switching element 18a to close, switching element 18c to open, and keeps switching elements 18b and 18d in their current state. During the fourth quarter, controller 27 commands switching elements 18a and 18d to open and commands switching elements 18b and 18c to close. A similar switching scheme for wireless power transmission via the generalized harmonic order envisioned herein is readily apparent from the example above.

[0034] Conventional frequency modulation used in SRC architectures may sacrifice soft switching for load regulation or input voltage regulation. However, in the case of wireless power transmission via a generalized harmonic order presented in this paper, load regulation and input voltage regulation are achieved by selecting appropriate harmonics, while maintaining soft switching. Therefore, the SRC switch experiences near-zero losses across the entire operating range.

[0035] The disclosed processes, methods, logic, or strategies can be delivered to a processing device, controller, or computer and / or implemented by a processing device, controller, or computer, which may include any existing programmable electronic control unit or dedicated electronic control unit. Similarly, processes, methods, logic, or strategies can be stored in various forms as data and instructions executable by a controller or computer, including but not limited to information permanently stored on various types of articles of manufacture, which may include permanently non-writable storage media (such as ROM devices) and information alternatively stored on writable storage media (such as floppy disks, magnetic tapes, CDs, RAM devices, and other magnetic and optical media). Processes, methods, logic, or strategies can also be implemented in a software executable object. Alternatively, they may be embodied, wholly or partially, using suitable hardware components, such as application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), state machines, controllers, or other hardware components or devices, or a combination of hardware, software, and firmware components.

[0036] The terms used in this specification are descriptive rather than restrictive, and it should be understood that various changes may be made without departing from the spirit and scope of this disclosure and claims. For example, Figure 1 The SRC architecture can take various forms depending on operational and packaging requirements. In the context of vehicle charging, the primary side 12 and controller 27 can form part of a charging station. And the secondary side 14 can be carried by the vehicle. As mentioned earlier, Figure 4A-6B The generalized harmonic order is not exhaustive. For example, a 2.5X generalized harmonic order is possible. This order can have a fundamental period with 10 resonant periods and 4 effective resonant periods. Others are also conceivable, and so on.

[0037] As previously described, features of various embodiments can be combined to form other embodiments that may not be explicitly described or shown. While various embodiments may have been described as providing advantages or preference over other embodiments or prior art implementations in one or more desired characteristics, those skilled in the art will recognize that one or more features or characteristics may compromise the achievement of desired overall system properties, depending on the specific application and implementation. These properties include, but are not limited to, cost, strength, durability, lifecycle cost, merchantability, appearance, packaging, size, suitability, weight, manufacturability, ease of assembly, etc. Therefore, embodiments described as less desirable than those desired by other embodiments or prior art implementations for one or more characteristics are not outside the scope of this disclosure and may be desirable for a particular application.

Claims

1. A wireless charging device, comprising: A primary-side circuit, including a voltage source, a switch, and a primary coil arranged to couple with a secondary coil, configured to form a series resonant converter when transferring power from the primary coil to the secondary coil; and A controller is configured to selectively activate the switch to induce the transmission, such that for each fundamental period, a pair of consecutive effective resonant periods have the same polarity.

2. The wireless charging device of claim 1, wherein the controller is further configured to activate the switch to induce the transmission, such that during each of the fundamental cycles, the quotient of the total number of resonant cycles and the total number of effective resonant cycles has a non-integer value.

3. The wireless charging device of claim 1, wherein the controller is further configured to activate the switch to induce the transmission, such that during each of the fundamental cycles, another pair of consecutive effective resonant cycles have opposite polarities.

4. The wireless charging device of claim 3, wherein the controller is further configured to activate the switch to induce the transmission such that during each of the fundamental cycles, the other pair of consecutive effective resonant cycles are adjacent to each other.

5. The wireless charging device of claim 1, wherein the controller is further configured to activate the switch to induce the transmission, such that during each of the fundamental period, the pair of consecutive effective resonant periods are adjacent to each other.

6. A wireless charger comprising: A primary-side circuit, comprising a switch and a primary coil arranged to couple with a secondary coil, configured to form a series resonant converter when transmitting power; and A controller is configured to selectively activate the switch to induce the transmission, such that for each fundamental period, the quotient of the total number of resonant periods to the total number of effective resonant periods has a non-integer value.

7. The wireless charger of claim 6, wherein the controller is further configured to activate the switch to induce the transmission such that during each of the fundamental cycles, a pair of consecutive effective resonant cycles have the same polarity.

8. The wireless charger of claim 7, wherein the controller is further configured to activate the switch to induce the transmission such that during each of the fundamental cycles, the pair of consecutive effective resonant cycles are adjacent to each other.

9. The wireless charger of claim 6, wherein the controller is further configured to activate the switch to induce the transmission, such that during each of the fundamental cycles, a pair of consecutive effective resonant cycles have opposite polarities.

10. The wireless charger of claim 9, wherein the controller is further configured to activate the switch to induce the transmission, such that during each of the fundamental cycles, the pair of consecutive effective resonant cycles are adjacent to each other.

11. A wireless charger comprising: A primary-side circuit, comprising a switch and a primary coil arranged to couple with a secondary coil, configured to form a series resonant converter when transmitting power; and A controller is configured to selectively activate the switch to induce the transmission, such that for each fundamental period, the quotient of the total number of resonant periods and the total number of effective resonant periods has an integer value greater than one, and the total number of effective resonant periods is greater than one.

12. The wireless charger of claim 11, wherein the controller is further configured to activate the switch to induce the transmission, such that during each of the fundamental cycles, a pair of consecutive effective resonant cycles have the same polarity.

13. The wireless charger of claim 12, wherein the controller is further configured to activate the switch to induce the transmission, such that during each of the fundamental cycles, the pair of consecutive effective resonant cycles are adjacent to each other.

14. The wireless charger of claim 11, wherein the controller is further configured to activate the switch to induce the transmission, such that during each of the fundamental cycles, a pair of consecutive effective resonant cycles have opposite polarities.

15. The wireless charger of claim 14, wherein the controller is further configured to activate the switch to induce the transmission, such that during each of the fundamental cycles, the pair of consecutive effective resonant cycles are adjacent to each other.

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