A power converter

Abstract

A mechanism for sensing power conversion information about a power conversion performed by a power converter. The power converter includes a first substrate with at least one planar coil printed thereon. Another planar coil is magnetically coupled to this planar coil, to form a transformer. A planar antenna, printed upon a second substrate, is positioned to receive a leakage electromagnetic field from one of the planar coils, and produce electrical flow responsive thereto. A detector also on the second substrate monitors this electrical flow to produce the power conversion information and control a second-stage power conversion portion between the another planar coil and an output of the power converter.

Description

[0001] 2025PF80010

[0002] 1

[0003] A power converter

[0004] FIELD OF THE INVENTION

[0005] The present invention relates to the field of power conversion.

[0006] BACKGROUND OF THE INVENTION

[0007] There is an increasing reliance upon power converters for converting and regulating a power to an electrical load, such as solid-state lighting devices (e.g., LEDs). There is also a growing demand for smaller and more efficient power converter, e.g., for use in more compact lighting solutions. Planar transformers have emerged as a promising option for achieving this miniaturization of power converters.

[0008] However, reducing the size of power converters presents several challenges. It requires not only the use of smaller components but also the simplification of circuitry. In particular, there is need for compact and reliable feedback or detection circuits for monitoring one or more properties of the power conversion, e.g., for use in performing control of the power converters.

[0009] Traditional approaches often necessitate complex circuits with components on both the primary and secondary sides of the driver, complicating the design and increasing the overall size.

[0010] This demand is particularly evident in lighting applications, such as those that employ leading edge (LE) or trailing edge (TE) phase-cut dimming. In such examples, precise detection of dimmer conduction angles is important for accurately translating them into appropriate dimming levels. This dimmer conduction angle is often delivered across an isolation barrier of an isolated converter so the secondary side of the isolated converter can effectively use it to fine tune the LED current. US 2014 / 0361701 Al discloses a solution that has an extra coil on the secondary side to directly detect signal on the primary coil and the secondary coil of the transformer to monitor the operation status of the driver. However, the traditional transformer is large and heavy, and adding a further extra coil makes it even bulkier.

[0011] Planar transformers are becoming increasingly more popular, but the planar transformer has no extra coil available for use. So, a simplified and smart method is preferred.2025PF80010

[0012] 2

[0013] It has been appreciated that there is therefore a need for improved feedback or detection circuitry of power converters.

[0014] EP2030208B1 discloses a transformer with planar primary wings, planar secondary winding, and planar sensing windings to detect faults.

[0015] EP4213170A1 discloses a structure of a planar transformer.

[0016] SUMMARY OF THE INVENTION

[0017] The inventors have recognized that there is a particular problem in power converters that make use of a transformer with planar coils in monitoring any parameters of the power conversion. In particular, the planar coils do not facilitate ease of positioning an auxiliary winding for contactless sensing of any such parameters. A solution to this problem is proposed that makes use of a second substrate with a planar antenna to overlap a planar coil.

[0018] More particularly, the present disclosure proposes a mechanism that overlaps a planar coil of a (planar) transformer with a planar antenna for a detection circuit. The planar antenna (e.g., another planar coil) senses the leakage magnetic level in either the primary planar coil or the secondary planar coil when current flows therethrough. The detection circuit processes the sensed leakage magnetic level to determine power conversion information (e.g., indicating a conduct angle of phase cut dimming and / or other parameters). In this way, the detection circuit is able to contactlessly derive information from the (planar) transformer, providing a more compact device with fewer circuitry components.

[0019] The invention is defined by the claims.

[0020] According to examples in accordance with an aspect of the invention, there is provided a power converter. The power converter comprises a power conversion circuit and a detection circuit.

[0021] The power conversion circuit comprises: a first substrate; a primary planar coil for connection to an input interface; and a secondary planar coil for connection to an output interface, wherein the secondary coil is magnetically coupled to the primary planar coil and galvanically isolated from the primary planar coil, wherein at least one of the primary planar coil and the secondary planar coil is printed upon the first substrate.

[0022] The power converter further comprises a second-stage power conversion portion connected between the secondary planar coil and the output interface.

[0023] The detection circuit comprises: a second substrate, separate to the first substrate; a planar antenna printed upon the second substrate; and a detector;2025PF80010

[0024] 3

[0025] The second substrate is positioned proximate to the first substrate such that at least a portion of the planar antenna overlaps with the primary planar coil and / or the secondary planar coil printed upon the first substrate and receives a leakage electromagnetic field produced by an electrical flow therethrough, such that the electrical flow through the primary planar coil and / or the secondary planar coil, printed upon the first substrate, induces a corresponding electrical flow through the planar antenna.

[0026] The detector is configured to monitor the electrical flow through the planar antenna to determine power conversion information relating to a power conversion performed using the power converter.

[0027] The power converter further comprises a control circuit electrically connected to the detection circuit, wherein the control circuit is configured to control a power flow from the output interface responsive to the power conversion information by controlling an operation of the second-stage power conversion portion responsive to the power conversion information.

[0028] The proposed power converter enables contactless sensing of power conversion information through magnetic coupling between planar coils on separate substrates. The present disclosure exploits the recognition that there will be an inherent leakage of a magnetic field from the primary planar coil(s) and from the secondary planar coil(s) during power conversion. The planar antenna may exploit this inherent leakage to detect one or more properties of a power conversion using the power converter (i.e., power conversion information) through appropriate positioning of a (second) substrate carrying the planar antenna. In particular, the second substrate may be positioned over / below the first substrate such that the planar antenna picks up the inherent magnetic field created by the power conversion using the first and second planar coils. The overlapping between the planar antenna and the planar coils ensures a sufficiently detectable signal is transferred. Depending on the real requirements, the dimension of the overlapping may vary as long as the signal is detectable. Additionally, the power conversion information may form at least a part of feedback used by a control circuit in controlling power conversion. This provides a more reliable and robust mechanism for performing power conversion. It is recognized that the proposed approach allows information about the power conversion to be derived without requiring direct electrical contact with the primary side of the power converter. Thus, it is preferable, for the second-stage power conversion portion between the secondary planar coil and the output interface an improved accuracy in controlling the final output at the output interface.

[0029] In some examples, the primary planar coil and the secondary planar coil are printed on the first substrate. The planar antenna may be an auxiliary planar coil printed upon2025PF80010

[0030] 4

[0031] the second substrate. Both of these variations provide a more compact power converter. Forming the planar antenna from an auxiliary planar coil provides a highly sensitive sensor for monitoring the leakage electromagnetic field.

[0032] In some examples, the primary planar coil is stacked vertically above or below the secondary planar coil, wherein the primary planar coil and the secondary planar coil are printed on different stacked layers of the first substrate; and the second substrate is positioned such that at least a portion of the planar antenna is vertically above or below the primary planar coil and / or the secondary planar coil printed upon the first substrate within a vertical distance threshold.

[0033] Vertical stacking of the coils for a planar transformer allows for a more compact overall design. This arrangement also improves the magnetic coupling between the coils, improving power transfer efficiency and signal detection. The planar placement of the coils also facilitates the placement / orientation of the planar antenna to harvest or react to sufficient electromagnetic leakage.

[0034] In some examples, the power conversion circuit comprises a magnetic core configured to cover the primary planar coil and the secondary planar coil and adapted to pass a varying magnetic flux from the primary planar coil to the secondary planar coil; the primary planar coil and / or the secondary planar coil printed upon the first substrate comprises an extended portion that extends out of the coverage of the magnetic core; and the second substrate is positioned such that the planar antenna at least partially overlaps the extended portion of the primary planar coil and / or the secondary planar coil printed upon the first substrate.

[0035] The portion of the primary and / or secondary planar coil(s) covered by the magnetic core allows for improved magnetic coupling with the coil due to maintaining core coverage for efficient power transfer. The extended one or both coils provide just enough electronic magnetic leakage for detection. Based on the study of the inventors, the electronic magnetic leakage is not significant (e.g., to significantly affect the power transfer). This design balances power conversion efficiency with effective signal detection.

[0036] In some examples, the magnetic core may extend through a center of the primary planar coil and / or the secondary planar coil. This configuration may enhance the magnetic coupling between the coils and improve overall power transfer efficiency of the power converter.

[0037] In some examples, the magnetic core may not overlap or cover the planar antenna. Thus, the magnetic core may be designed to primarily cover the primary and secondary planar coils on the first substrate, while leaving the planar antenna on the second2025PF80010

[0038] 5

[0039] substrate outside its coverage area. This configuration may result in a stronger leakage field in the vicinity of the planar antenna, potentially enhancing its ability to detect and monitor the current flow induced by the primary and / or secondary coils.

[0040] The second-stage power conversion portion comprise a second-stage power conversion portion switch arrangement connected between the secondary planar coil and the output interface, wherein the control circuit is configured to control the operation of the second-stage power conversion portion via controlling an operation of the second-stage switching arrangement responsive to the power conversion information.

[0041] The power converter may comprise, e.g., as the power conversion circuit, a first-stage comprising a first-stage switch arrangement connected between the input interface and the primary planar coil.

[0042] In some examples, the control circuit comprises a control interface configured to receive a control signal from an external device; and the control circuit is configured to control an operation of the second-stage power conversion portion switching arrangement responsive to the power conversion information and the received control signal.

[0043] The first-stage switch arrangement may be configured to be switchable between: a charging state, in which the switch arrangement connects the input interface to the primary planar coil to thereby feed the primary planar coil with current from the input interface and produce the electromagnetic field; a freewheeling state, in which the switch arrangement disconnects the input interface from the primary planar coil to thereby feed the secondary planar coil with current from the magnetic coupling of the primary planar coil and the secondary planar coil and produce the electromagnetic field; and a dormant state, in which the input interface is without power such that no or negligible power flows through the primary planar coil and no or negligible power flows through the secondary planar coil.

[0044] In some examples, the first-stage comprises a flyback conversion circuit. In particular, the first-stage switch arrangement and the primary and secondary planar coils may form or define a flyback conversion circuit.

[0045] In some examples, the second-stage power conversion portion switch arrangement is current-controlled, and the first-stage switch arrangement is voltage-controlled.

[0046] The power conversion circuit may further comprise a control circuit driver configured to drive or power the control circuit using power induced on the planar coil by a current flow through the primary planar coil and / or the secondary planar coil printed upon the first substrate. This allows for efficient powering of the control circuit that is galvanically2025PF80010

[0047] 6

[0048] isolated from the primary planar coil and makes use of a leakage magnetic field, providing a more efficient power converter.

[0049] In some examples, the detector is configured to monitor the electrical flow through the planar antenna to determine, as a first portion of the power conversion information, whether or not power is being supplied to the primary planar coil from the input interface.

[0050] In some examples, detector is configured to monitor an envelope of the electrical flow through the planar antenna and determine whether or not power is being supplied to the primary planar coil from the input interface, in a frequency of AC mains, by comparing the monitored envelope to a predetermined threshold.

[0051] In some examples, envelope detection of the current flow through the planar antenna may facilitate phase angle detection in power converters, particularly for applications involving phase-cut dimming. The envelope of the electrical flow may correspond to the overall shape of the waveform, which can be indicative of the conduction angles in phase-cut dimming scenarios.

[0052] When phase-cut dimming is applied, the input voltage waveform is partially cut off, creating distinct on and off periods within each AC cycle. These periods may be reflected in the electrical flow through the primary planar coil, which in turn induces a corresponding current in the planar antenna. By monitoring the envelope of this induced electrical flow, the detector is able to identify the timing and duration of the conduction periods.

[0053] In another embodiment, the detector is configured to process the determined electrical power in the auxiliary planar coil to determine, as a second portion of the power conversion information, an amplitude of power converted by the power conversion circuit.

[0054] A wide variety of other properties of the power conversion may be determined or monitored by the detector. For instance, the electrical flow in / on the planar antenna will reflect or be responsive to the shape of operation waveform inside the planar power conversion circuit. Moreover, the driver switching frequency and / or duty circle could be sensed by monitoring the electrical flow through the planar antenna coil directly. The electrical flow through the planar antenna could be also used to estimate other information such as current level.

[0055] There is also proposed a solid-state lighting driver comprising: any herein proposed power converter; the input interface, for connection to an input power supply; and the output interface, for connection to a solid-state light source.2025PF80010

[0056] 7

[0057] There is also proposed a solid-state lighting device comprising any herein proposed solid-state lighting driver and the sold-state light source connected to the output interface.

[0058] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter.

[0059] BRIEF DESCRIPTION OF THE DRAWINGS

[0060] For a better understanding of the invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings, in which:

[0061] Figure 1 provides a cross-sectional view of a portion of a proposed power converter;

[0062] Figure 2 provides a perspective view of a portion of the proposed power converter;

[0063] Figure 3 provides another perspective view of the portion of the proposed power converter;

[0064] Figure 4 provides a cross-sectional view of a portion of another proposed power converter;

[0065] Figure 5 illustrates a detection circuit for use in a proposed power converter; Figure 6 is a circuit diagram of an exemplary power converter; and Figure 7 illustrates exemplary waveforms.

[0066] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0067] The invention will be described with reference to the Figures.

[0068] It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the apparatus, systems and methods, are intended for purposes of illustration only and are not intended to limit the scope of the invention. These and other features, aspects, and advantages of the apparatus, systems and methods of the present invention will become better understood from the following description, appended claims, and accompanying drawings. It should be understood that the Figures are merely schematic and are not drawn to scale. It should also be understood that the same reference numerals are used throughout the Figures to indicate the same or similar parts.

[0069] The invention provides a mechanism for sensing power conversion information about a power conversion performed by a power converter. The power converter includes a2025PF80010

[0070] 8

[0071] first substrate with at least one planar coil printed thereon. Another planar coil is magnetically coupled to this planar coil, to form a transformer. A planar antenna, printed upon a second substrate, is positioned to receive a leakage electromagnetic field from one of the planar coils, and produce electrical flow responsive thereto. A detector monitors this electrical flow to produce the power conversion information.

[0072] The term vertical, as used herein, means substantially orthogonal to the surface of a substrate. The term lateral, as used herein, means substantially parallel to the surface of a substrate. Also, terms describing positioning or location (such as (vertically) above, (vertically) below, top, bottom, etc.) are to be construed in conjunction with the orientation of the structures illustrated in the diagrams.

[0073] In the context of the present disclosure, a substrate is an element formed from one or more layers of any suitable substrate or material for mounting and / or supporting electronic devices, such as FR-4, alumina, silicon, glass, silicon nitride and so on. A wide variety of other examples are known in the art. An alternative label for a substrate, in the context of a power converter, is a board.

[0074] Figure 1 provides a cross-sectional view of elements of a proposed power converter 100.

[0075] The power converter 100 comprises a power conversion circuit 110 comprises a first substrate 111, a primary planar coil 112 and a secondary planar coil 113.

[0076] The primary planar coil 112 is designed for connection to an input interface. The secondary planar coil 113 is designed for connection to an output interface. Alternative labels for a planar coil include planar winding or planar turns.

[0077] The secondary coil is magnetically coupled to the primary planar coil and galvanically isolated from the primary planar coil. In this way, the primary planar coil 112 and the secondary planar coil 113 together form a transformer. In particular, a varying electrical flow through the primary planar coil 112 induces a corresponding varying electrical flow through the secondary planar coil 113 (and vice versa).

[0078] At least one of the primary planar coil 112 and the secondary planar coil 113 is printed upon the first substrate 111.

[0079] Example mechanisms for printing or etching a planar coil upon a substrate are well established and known in the art, e.g., as set out in Dai, N., et al. "A comparative study of high-frequency, low-profile planar transformer technologies." Proceedings of 1994 IEEE Applied Power Electronics Conference and Exposition-ASPEC'94. IEEE, 1994.2025PF80010

[0080] 9

[0081] In preferred examples, both planar coils are printed upon the first substate. In particular, the first substrate, the primary planar coil and the secondary planar coil may be formed as elements of a printed circuit board. Thus, the power conversion circuit may be or comprise a printed circuit board comprising the first substrate, the primary planar coil and the secondary planar coil. The planar coils may, for instance, be formed on or in different layers of the first substrate.

[0082] In other examples, one of the primary and secondary planar coils are mounted (e.g., via a surface-mounting mechanism such as soldering) to the first substrate.

[0083] The power conversion circuit 110 may further comprise a magnetic core 115 configured to cover the primary planar coil 112 and the secondary planar coil 113. The magnetic core 115 is configured to pass a varying magnetic flux from the primary planar coil to the secondary planar coil.

[0084] The present disclosure advantageously recognizes that the structure of the power conversion circuit 110 will result in a leakage electromagnetic field (i.e., a leakage electric and / or magnetic field) as power / electricity flows through the coils. In particular, the magnetic coupling between the primary 112 and secondary 113 planar coils will result in some electromagnetic field leakage as a change in current through one planar coil induces a change in current through the other planar coil.

[0085] The present disclosure proposes to position a planar antenna 122, printed upon a second substrate 121, so that at least a portion of the planar antenna 122 overlaps with the primary and / or secondary planar coil (printed upon the first substrate). Put another way, at least a portion 122A of the planar antenna lies vertically above the primary and / or secondary coil, i.e., such that a projection of the portion of the planar antenna in a direction perpendicular to the plane in which the planar antenna lies will intersect with the primary and / or secondar coil.

[0086] In particular, the position of the planar antenna is aligned to receive a leakage electromagnetic field produced by an electrical flow through the primary planar coil and / or the secondary planar coil printed upon the first substrate. In this way, that an electrical flow through the primary planar coil and / or the secondary planar coil, printed upon the first substrate, induces a corresponding electrical flow through the planar antenna.

[0087] Put another way, the planar antenna effectively picks up an electromagnetic signal produced by the primary and / or second planar coils as a result of energy / power transfer between the two planar coils. The electromagnetic signal is a manifestation of the leakage electromagnetic field produced by electrical flow through the planar coil(s), and the leakage electromagnetic field is a direct product of the power transfer / conversion performed using the2025PF80010

[0088] 10

[0089] power converter. Thus this facilitates monitoring of one or more properties of the power transfer / conversion performed using the power converter 100.

[0090] More specifically, the present disclosure proposes the concept of a detection circuit 120 comprising the second substrate 121, the planar antenna 122 and a detector 123. The detector 123 is configured to monitor the electrical flow through the planar antenna to determine power conversion information relating to a power conversion performed using the power converter.

[0091] In the illustrated example, the second substrate 121 has been positioned such that the planar antenna 122 partially overlaps the secondary planar coil 113, and more specifically to face the secondary planar coil 113. In alternative examples, the second substrate may be positioned to at least partially overlap and / or face the first planar coil 112.

[0092] In particular, the primary planar coil 112 may be (as illustrated) stacked vertically above or below the secondary planar coil. For instance, the primary planar coil and the secondary planar coil may be printed on different stacked layers of the first substrate.

[0093] The second substrate is positioned such that at least a portion of the planar antenna is vertically above or below the primary planar coil and / or the secondary planar coil printed upon the first substrate

[0094] In preferred examples, the distance between the planar antenna and the first and / or secondary planar coil is no greater than a vertical distance threshold DT. The vertical distance threshold is selected such that the planar antenna is sufficiently close to the primary / secondary planar coil to pick up on the leakage field.

[0095] The value of the vertical distance threshold DT is dependent on the magnitude of the leakage electromagnetic signal as well as the sensitivity of the detector. In some particular applications, the value of the vertical distance threshold DT may be no greater than 10 mm, e.g., no greater than 5 mm. This increases a magnitude of electrical flow through the planar antenna 122 responsive to a power flow through the primary / secondary planar coils for improved sensitivity and accuracy in determining the power conversion information.

[0096] In some examples, the planar antenna may be configured to receive a leakage magnetic field produced by an electrical flow through only a single one of the primary planar coil and the secondary planar coil.

[0097] In particular, the planar antenna may be shielded (e.g., by the first substrate 111) and / or sufficiently distanced from a particular one of the primary planar coil 112 and the secondary planar coil 113 such that a power flow through said particular one induces a leakage magnetic field having no or negligible magnitude at the planar antenna. In this way, the planar2025PF80010

[0098] 11

[0099] antenna may be able to monitor the electrical flow through a single one of the planar coils. This can be advantageous for facilitating the sensing or monitoring of particular properties or parameters of the power conversion using the planar coils (e.g., a duty cycle, as later detailed).

[0100] This approach allows for specific detection of an electrical flow through only one of the planar coils, which may be advantageous in monitoring the power conversion performed by the power converter.

[0101] In the context of the present disclosure, an antenna is any circuit component configured to convert an electromagnetic signal into a measurable electrical signal. A planar antenna is any such circuit component that lies substantially in a same, shared plane.

[0102] One example of a suitable planar antenna for use in the present disclosure is a planar coil or planar coil, which can be labelled an auxiliary planar coil.

[0103] The auxiliary planar coil may connect between a ground / reference voltage and the detector. A changing intensity / magnitude of the leakage magnetic field will induce a corresponding change in the electrical flow (specifically: a change in current) through the auxiliary planar coil. This facilitates monitoring of the power conversion performed by the power converter.

[0104] In some instances, the auxiliary planar coil may comprise a coil of no more than 5 turns, e.g., a coil of between 2 and 4 turns. This advantageously recognizes that a leakage magnetic field can be sensed with a relatively low number of turns, thereby saving on material usage and space (e.g., surface area) occupied by the planar antenna.

[0105] Another suitable example of a planar antenna that may be used in the present disclosure is a planar Hall effect sensor, such as those proposed by Ejsing, L., et al. "Planar Hall effect sensor for magnetic micro-and nanobead detection." Applied Physics Letters 84.23 (2004): 4729-4731 or Elzwawy, Amir, et al. "Current trends in planar Hall effect sensors: evolution, optimization, and applications." Journal of Physics D: Applied Physics 54.35 (2021): 353002.

[0106] Other suitable examples of planar antennae are well known to the skilled person, such as those suggested by Chen, Zhi Ning, et al. "Planar antennas." IEEE microwave magazine 7.6 (2006): 63-73.

[0107] In order to have good detection effect, it is better if the planar antenna takes an enclosed shape. Therefore besides circular / helix coil, a rectangle coil or triangle coil or other polygon coil would also work. However, unenclosed shape may also apply.2025PF80010

[0108] 12

[0109] Figures 2 and 3 illustrate perspective views of a portion of the proposed power converter 100. For the sake of illustrative clarity, the illustration of the (optional) magnetic core has been omitted.

[0110] These Figures demonstrate how the primary 112 and secondary planar coils 113 may be printed on the same first substrate 111, e.g., upon different stacked layers of the first substrate. In Figure 2, the substrate 121 is made illustratively translucent to show the coil 113 overlapping and underneath the antenna 121; and in the Figure 3, the substrate 111 is made illustratively translucent to show the antenna 122 overlapping and above the coil 112.

[0111] It will be appreciated that, in practice, the power converter may comprise one or more further components or elements for performing power conversion, including one or more: switch arrangements, rectifiers (e.g., for AC-DC conversion), resonant tanks, capacitors, inductors and so on.

[0112] Turning back to Figure 1, it is noted that the magnetic core 115 covers (a respective portion) of the primary planar coil and the secondary planar coil. In particular, the magnetic coil 115 extends to cover a central portion of each planar coil, as well as two sides of each planar coil. There is therefore a portion of each planar coil that is exposed. The second substrate 121 is positioned such that the planar antenna overlaps (e.g., is vertically above / below) the exposed portion of at least one of the primary and secondary planar coils.

[0113] Figure 4 illustrates a modified version of the proposed power converter with improved sensitivity for the planar antenna.

[0114] In particular, the primary 112 and / or secondary 113 planar coils may (e.g., each) comprise an extended portion 410 that extends outside of the coverage of the magnetic core. For instance, a change in electrical flow through this extended portion may introduce no or negligible change in magnetic flux into the magnetic core. However, this extended portion will continue to produce an inherent electromagnetic field, which may function as the leakage electromagnetic field. Accordingly, the second substrate 121 may be positioned such that the planar antenna 122 at least partially (e.g., partially or completely) overlaps the extended portion(s) 410.

[0115] More particularly, the extended portion of the primary and / or secondary planar coils may cause the magnetic core 115 to be positioned off-center with respect to said primary and / or secondary coil. Thus, the primary and / or secondary coils may be asymmetrical with respect to the magnetic core.2025PF80010

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[0117] Figure 4 illustrates an example in which (e.g., only) the secondary planar coil 113 comprises such an extended portion 410. A portion 112A of the planar antenna 122 is positioned to overlap this extended portion.

[0118] This provides a mechanism for more easily coupling a leakage signal to the planar antenna. The greater the size of the overlap area, between the planar antenna and the portion of the planar coil(s), the easier it is for the antenna to pick up on the leakage signal.

[0119] The extended portion 410 of the primary 112 and / or secondary 113 planar coil(s) allows for improved magnetic coupling with the planar antenna while maintaining core coverage for efficient power transfer. This design balances power conversion efficiency with effective signal detection.

[0120] In some examples, the magnetic core may extend through a center of the primary planar coil and / or the secondary planar coil. This configuration may enhance the magnetic coupling between the coils and improve overall power transfer efficiency.

[0121] In some examples, the magnetic core is configured to not overlap or cover the planar antenna. Thus, the magnetic core may be designed to primarily cover the primary and secondary planar coils on the first substrate, while leaving the planar antenna on the second substrate outside its coverage area. This configuration results in a stronger leakage field in the vicinity of the planar antenna, functioning to improve its ability to detect and monitor the current flow induced by the primary and / or secondary coils.

[0122] The power converter may, for instance, comprise one or more suitable or known forms of power conversion circuitry, such as switched mode power supplies; cycloconverters; choppers; power inverters and so on. Exemplary switched-mode power supplies include boost converters; buck converters; book boost converters; flyback converters; Cuk converters; and / or matrix converters.

[0123] Components galvanically connected to the primary planar coil can be labelled primary side components. A portion of the power converter galvanically connected to the primary planar coil may be labelled a primary side. Components galvanically connected to the secondary planar coil can be labelled secondary side components. A portion of the power converter galvanically connected to the secondary planar coil may be labelled a secondary side. The primary side and secondary side components may together comprise or constitute a first-stage which is effectively an isolated converter.

[0124] Thus, although not visible in Figures 1 to 3, the power conversion circuitry may comprise a first-stage switch arrangement (which controls an electrical flow from the input interface through the primary planar coil).2025PF80010

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[0126] The power conversion circuitry may take a two-stage architecture, in which the power conversion circuitry further comprises a second-stage power conversion portion which is effectively a second-stage with a second-stage power conversion portion (second-stage) switch arrangement (which controls an electrical flow from the first-stage to the output interface via the second-stage power conversion portion / second-stage). This will be later described together with Figure 6.

[0127] Where the power conversion circuitry comprises a first-stage switch arrangement, said first-stage switch arrangement may be configured to be switchable between a charging state and a freewheeling state when there is input power into the device. In the charging state, the first-stage switch arrangement connects the input interface to the primary planar coil to thereby feed the primary planar coil with current from the input interface and produce the electromagnetic field. In the freewheeling state, the switch arrangement disconnects the input interface from the primary planar coil to thereby feed the secondary planar coil with current from the magnetic coupling of the primary planar coil and the secondary planar coil and produce the electromagnetic field.

[0128] The first-stage may be operated in a dormant state, in which the input power is not provided to the input interface (i.e., the input interface is without power) such that no or negligible power flows through the primary planar coil and no or negligible power flows through the secondary planar coil. This is often done by the phase cut dimmer enter conduction state.

[0129] Thus, the difference between the freewheeling state and the dormant state is that, in the dormant state, the magnetic field held by the primary and secondary planar coils has collapsed, e.g., to have no or negligible amplitude. In other words, in the dormant state, substantially no or negligible current flows through the primary and secondary coils.

[0130] As previously explained, the detector 123 is configured to monitor the electrical flow through the planar antenna to determine power conversion information relating to a power conversion performed using the power converter.

[0131] As a simple example, the detector may be configured to monitor an (e.g., average) electrical current inducted in the planar antenna as the power conversion information. This monitored current changes responsive to a current flow in the primary / secondary planar coil.

[0132] As a more complex example, the detector may be configured to monitor a duty cycle of current flow in the primary / secondary planar coil. This may, for instance, be indicative of a desired output power to a load that draws from the power converter.2025PF80010

[0133] 15

[0134] In one scenario, the power converter comprises a flyback converter (which itself comprises the power conversion circuitry as an aspect of the power converter) for driving a lighting element.

[0135] The operation of a switch arrangement (e.g., a switch) of the flyback converter is controlled responsive to a desired dimming level for the lighting element. More specifically a control unit may be configured to periodically activate and deactivate the switch arrangement responsive to the dimming level. For instance, in a phase cutting control scheme, the switch arrangement will be activated at the start of each half-cycle of an input AC signal and activated when a defined phase has elapsed since the start of said half-cycle.

[0136] When the switch arrangement is activated, it switches at a switching frequency and electrical power will flow through the primary and secondary coils (e.g., switching, at the switching frequency, between the charging state and a freewheeling state previously mentioned). When the switch arrangement is deactivated (i.e., controlled to operate in the dormant state due to no input power at all), no switching occurs, and no electrical power will flow through the primary and secondary coils. As the planar antenna is configured to respond to a leakage electromagnetic field, a non-zero electrical power will be induced in the planar antenna only when electrical power flows through the primary / secondary planar coils.

[0137] The duty cycle of the activation of the switch arrangement is controlled responsive to a desired dimming level, e.g., to define the value of the defined phase for a phase cutting control scheme.

[0138] A number of types of power conversion information are detectable in this scenario.

[0139] For instance, the envelope of the electrical flow through the planar antenna indicates the duty cycle of the (de)activation of the switch arrangement, and therefore the desired dimming level and / or defined phase (for a phase cutting control mode). Similarly, if a phase cutting control scheme is employed As another example, the electrical flow induced in the planar antenna will also indicate the switching frequency of the flyback converter.

[0140] Figure 5 illustrates a portion of a simple exemplary detector 123, for improved contextual understanding. For the purposes of the illustrated example, the planar antenna 122 is embodied as a planar coil, which is diagrammatically represented as a winding / inductor.

[0141] In some examples, the detector 123 is configured to process a signal SPA produced by the planar antenna to produce the power conversion information.

[0142] In some instances, the signal processing circuitry 123 comprises detection circuitry 510 configured to convert an electrical flow induced in the planar antenna into a2025PF80010

[0143] 16

[0144] measurable electrical value, such as a voltage Vs, which is indicative of the power conversion information. For instance, the measurable electrical value may be responsive to the power conversion information and / or be processable to derive the power conversion information therefrom.

[0145] For instance, the detection circuitry 510 may comprise a resistor-capacitor pair Rl, Cl (being a resistor R1 and a capacitor Cl connected in parallel) connected between the planar antenna and a ground / reference voltage. A voltage Vs across the resistor-capacitor pair will respond to a change in electrical current through the planar antenna, thereby representing a property of the power conversion and being indicative of the power conversion information.

[0146] In some examples, the detector 123 may comprise a digital processor 520 configured to process one or more signals produced by the planar antenna 122 or signals derived therefrom, e.g., the voltage Vs produced by the exemplary detection circuitry 510 outlined above. Thus, the analogue-domain signal provided by the planar antenna may be effectively transformed into the digital domain (e.g., using an ADC of the digital processor) and processed digitally to calculate the power conversion information. Examples parts of power conversion information have been previously mentioned.

[0147] The digital processor 520 may be embodied as a microcontroller, digital signal processor (DSP), field-programmable gate array (FPGA), or application-specific integrated circuit (ASIC). Within this processor, different sections of code or logic blocks may be designated to perform the functions for producing the power conversion information.

[0148] The digital processor 520 may also be configured to perform any other desired functionality of the overall power converter, e.g., control functionality, feedback functionality, communication functionality and so on. Some working examples are provided later in this disclosure.

[0149] Any herein disclosed power converter may comprise a control circuit. The control circuit is configured to control a power flow from the input interface to the output interface. In particular, the control circuit may control the operation of one or more switch arrangements in the power conversion circuitry.

[0150] In particular examples, the control circuit is configured to control the power flow from the input interface to the output interface responsive to the power conversion information.

[0151] More preferably, the control circuit is configured to control the operation of a second-stage power conversion portion switch arrangement of the second-stage power2025PF80010

[0152] 17

[0153] conversion portion (e.g., and no first-stage switch arrangement) responsive to the power conversion information.

[0154] The control circuit may be positioned or printed upon the second substrate. This advantageously positions the detection circuit and the control circuit upon a same substrate, e.g., allowing for a digital processor of the detection circuit to perform a control function and reducing a length of wires or conductors between the detection circuit and the control circuit. More particularly, this reduces a number of cross-substrate connections from the first substrate to the second substrate (and vice versa), compared to if the control circuit were not positioned on the second substrate. This second substrate can also integrate or mount other low voltage control component such as wireless communication thus the whole device is more modular and reliable.

[0155] In some examples, the power conversion circuit comprises two or more power conversion portions connected in series, i.e., cascaded together. The first-stage power conversion portion (alternatively labelled a first-stage) may comprise the primary and secondary planar coils, together with a first-stage switch arrangement. The second-stage power conversion portion power conversion portion (alternatively labeled a second-stage power conversion portion) may be connected between the secondary planar coil and the output interface, and comprise a second-stage power conversion portion switch arrangement.

[0156] In such examples, the control circuit may be configured to control the operation of the second-stage power conversion portion via the second-stage power conversion portion switch arrangement.

[0157] Figure 6 is a circuit diagram illustrating an exemplary power converter 600, illustrating some further optional components of the power converter.

[0158] The power converter comprises a power conversion circuit 605 comprising a primary planar coil 112 for connection to an input interface 691; and a secondary planar coil 113 for connection to an output interface 692. At least one of these planar coils is printed onto a first substrate (not illustrated in Figure 6). The planar coils are magnetically coupled together.

[0159] A load 690 is connected to the output interface 692. The load 690 may, for instance, be a solid-state lighting element (e.g., an LED arrangement comprising one or more LEDs).

[0160] In the illustrated example, the power conversion circuit 605 comprise a first-stage power conversion portion 610 (i.e., a first-stage), comprising the primary 112 and secondary 113 planar coils, in the form of a flyback converter. The first power conversion portion comprises a first-stage switch arrangement SWFB, having a flyback switch, a rectifying2025PF80010

[0161] 18

[0162] element (here: a diode DI) and a storage capacitor Cs. These are arranged in the form of a basic flyback converter, and other examples are known.

[0163] The first-stage power conversion portion 610 may be replaced by any other form of switched mode power supply having a transformer (with a primary and secondary planar coil magnetically coupled together) and a first-stage switch arrangement.

[0164] The first-stage power conversion portion 610 is configured to convert an AC input signal SAC (received at the input interface) into an intermediate DC voltage, across the storage capacitor Cs.

[0165] The power conversion circuit 605 also comprises a second-stage power conversion portion power conversion portion 620 (i.e., a second-stage power conversion portion) cascaded or connected between the secondary planar coil 113 (of the power conversion circuit 610) and the output interface 692. The second-stage power conversion portion power conversion portion comprises a second-stage power conversion portion switching interface SWB.

[0166] In the illustrated example, the second-stage power conversion portion 620 is arranged as a buck converter, e.g., further comprising a buck impedance LB, a buck freewheeling diode D2, and an output capacitor Co. The second-stage power conversion portion may be replaced by any other form of switched mode power supply having a second-stage power conversion portion switch arrangement.

[0167] The power converter 600 also comprises a detection circuit 630 comprising a planar antenna 122; and a detector 123. These may be embodied as previously disclosed. The detection circuit 630 is configured to generate power conversion information.

[0168] Figure 7 illustrates exemplary waveforms for improved understanding. A first waveform SAC* illustrates a rectified phase cut version of the AC input signal SAC. A second waveform V(122) illustrates the electrical flow through the planar antenna 122, demonstrating how the envelope of this electrical flow maps or follows the electrical flow of the phase cut version of the AC input signal SAC. This facilitates identification of the phase cut angle of the first-stage switch arrangement. If zoomed in, the high frequency duty cycle of the second waveform V(122) can also shows the duty cycle of the first-stage switch arrangement SWFB.

[0169] Turning back to Figure 6, the power converter 600 may comprise a control circuit 640. The control circuit 640 is configured to control an operation of one or more components of the power converter to control a power flow from the input interface 691 to the output interface 692.2025PF80010

[0170] 19

[0171] In particular, the control circuit 640 may be configured to receive the power conversion information from the detection circuit 630. The control circuit 640 may be configured to control the operation of the second-stage power conversion portion switch arrangement SWB responsive to the power conversion information.

[0172] Thus, in some examples, the control circuit comprises a second-stage power conversion portion control unit 641 configured to control an operation of the second-stage power conversion portion switch arrangement SWB responsive to the power conversion information.

[0173] By way of example, the power conversion information may carry information about an electrical current flow in the secondary planar coil 113. This may be used to control the switching operation of the second-stage power conversion portion switch arrangement, e.g., to achieve a desired output voltage.

[0174] The control board 640 may also have an interface to receive external control information 646 and control the switching operation of the second-stage power conversion portion switch arrangement SWB according to both the power conversion information 620 and the external control information 646.

[0175] In some examples, the control circuit comprises a first-stage control unit 642 configured to control an operation of the first-stage switch arrangement SWFB responsive to a control signal Sc received from an external device (such as an external (e.g., manually-operable) dimming switch, router, remote control device and / or a mobile device). A wide variety of external devices suitable for providing a control signal Sc for defining an operation of a first-stage control unit are well known in the art, and are not detailed for the sake of conciseness.

[0176] In particular, the first-stage control unit may control the switching performed by the switch arrangement SWFB responsive to the control signal Sc. As a working example, the control signal may define a phase for phase-cutting control scheme, which may be employed by the first control unit 641 to controllably activate and deactivate the switch arrangement SWFB.

[0177] In some examples, the second-stage power conversion portion control unit 642 and the first-stage control unit 641 are galvanically isolated from one another. This reduces a risk of power surges at the primary side affecting the operation of the secondary side of the power converter.

[0178] Previous examples have described how the detection circuit 630 may comprise a digital processor. In such examples, the digital processor may be further configured to2025PF80010

[0179] 20

[0180] perform the function of at least the second-stage power conversion portion control unit 641 (when present).

[0181] In some examples, the first-stage switch arrangement is voltage-controlled and the second-stage power conversion portion switch arrangement is current-controlled. The control circuit may be appropriately adapted to perform this function, e.g., comprising appropriate feedback circuitry for the switch arrangements. The control mechanical and the circuit component to implement voltage feedback-control and current feedback-control are well known in the art thus this description will not elucidate further.

[0182] In any herein described power converter, in some examples, energy received on the planar coil is used to power or drive the control circuit. Thus, in some examples, the power converter further comprises a control circuit driver configured to drive or power the control circuit 640 using power induced on the planar coil by a current flow through the primary planar coil and / or the secondary planar coil printed upon the first substrate.

[0183] There is also proposed a chip package comprises any herein proposed power converter and a housing and / or casing enclosing or covering the proposed power converter. The housing and / or casing may appropriately position or carry the first substrate and the second substrate, such that the planar antenna is positioned in close proximity to the primary and / or secondary planar coils.

[0184] There is also proposed a solid-state lighting driver comprising any herein proposed power converter; the input interface, for connection to an input power supply (e.g., a mains power supply); and the output interface, for connection to a solid-state light source.

[0185] There is also proposed a solid-state lighting device comprising said solid-state lighting driver the sold-state light source connected to the output interface.

[0186] The term “and / or” in a list of elements is intended to refer to any combination of two or more elements as well as each element individually. Thus, a “first element” and / or a “second element” refers to the first element alone, the second element alone and both the first and second element.

[0187] Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. If the term "adapted to" is used in the claims or description, it is noted the term "adapted to" is intended to be2025PF80010

[0188] 21

[0189] equivalent to the term "configured to". If the term "arrangement" is used in the claims or description, it is noted the term "arrangement" is intended to be equivalent to the term "system", and vice versa. Any reference signs in the claims should not be construed as limiting the scope.

Claims

2025PF8001022CLAIMS:

1. A power converter (100, 600), comprising:a power conversion circuit (110, 605) comprising:a first substrate (111);a primary planar coil (112) for connection to an input interface (691); and a secondary planar coil (113) for connection to an output interface (692), wherein the secondary coil is magnetically coupled to the primary planar coil and galvanically isolated from the primary planar coil, wherein at least one of the primary planar coil and the secondary planar coil is printed upon the first substrate;a second-stage power conversion portion (620) connected between the secondary planar coil (113) and the output interface (692),a detection circuit (120, 630) comprising:a second substrate (121), separate to the first substrate;a planar antenna (122) printed upon the second substrate; and a detector (123);wherein:the second substrate is positioned proximate to the first substrate such that at least a portion (122A) of the planar antenna overlaps with the primary planar coil and / or the secondary planar coil printed upon the first substrate and receives a leakage electromagnetic field produced by an electrical flow therethrough, such that the electrical flow through the primary planar coil and / or the secondary planar coil, printed upon the first substrate, induces a corresponding electrical flow through the planar antenna; andthe detector is configured to monitor the electrical flow through the planar antenna to determine power conversion information relating to a power conversion performed using the power converter,further comprisinga control circuit (640) electrically connected to the detection circuit, wherein the control circuit is configured to control a power flow from the output interface responsive to the power conversion information by controlling an operation of the second-stage power conversion portion responsive to the power conversion information.2025PF80010232. The power converter of claim 1, wherein the primary planar coil (112) and the secondary planar coil (113) are printed on the first substrate (111), andthe planar antenna is an auxiliary planar coil printed upon the second substrate.

3. The power converter of any one of claims 1 or 2, wherein:the primary planar coil is stacked vertically above or below the secondary planar coil, wherein the primary planar coil and the secondary planar coil are printed on different stacked layers of the first substrate; andthe second substrate is positioned such that at least a portion of the planar antenna is vertically above or below the primary planar coil and / or the secondary planar coil printed upon the first substrate within a vertical distance threshold.

4. The power converter of any one of claims 1 to 3, wherein:the power conversion circuit comprises a magnetic core (115) configured to cover the primary planar coil and the secondary planar coil and adapted to pass a varying magnetic flux from the primary planar coil to the secondary planar coil;the primary planar coil and / or the secondary planar coil printed upon the first substrate comprises an extended portion (410) that extends out of the coverage of the magnetic core;the second substrate is positioned such that the planar antenna at least partially overlaps the extended portion of the primary planar coil and / or the secondary planar coil printed upon the first substrate.

5. The power converter of claim 1, wherein the second-stage power conversion portion comprises a second-stage power conversion portion switch arrangement (SWB) connected between the secondary planar coil and the output interface, wherein the control circuit is configured to control the operation of the second-stage power conversion portion by controlling an operation of the second-stage power conversion portion switching arrangement, responsive to the power conversion information.

6. The power converter of claim 1, wherein the power conversion circuit is a first-stage and comprises a first-stage switch arrangement (SWFB) connected between the input interface and the primary planar coil, wherein:2025PF8001024the control circuit comprises a control interface (645) configured to receive a control signal from an external device; andthe control circuit is configured to control an operation of the second-stage power conversion portion switching arrangement responsive to the power conversion information and the received control signal.

7. The power converter of claim 6, wherein the first-stage switch arrangement is configured to be switchable between:a charging state, in which the first-stage switch arrangement connects the input interface to the primary planar coil to thereby feed the primary planar coil with current from the input interface and produce the electromagnetic field;a freewheeling state, in which the first-stage switch arrangement disconnects the input interface from the primary planar coil to thereby feed the secondary planar coil with current from the magnetic coupling of the primary planar coil and the secondary planar coil and produce the electromagnetic field; anda dormant state, in which the input interface is without power such that no or negligible power flows through the primary planar coil and no or negligible power flows through the secondary planar coil.

8. The power converter of claim 7, wherein the first-stage comprises a flyback conversion circuit.

9. The power converter of any one of claims 1 to 8, wherein the second-stage power conversion portion switch arrangement is current-controlled and the first-stage switch arrangement is voltage-controlled.

10. The power converter of any one of claims 1 to 9, further comprising a control circuit driver configured to drive or power the control circuit using power induced on the planar coil by a current flow through the primary planar coil and / or the secondary planar coil printed upon the first substrate11. The power converter of any one of claims 1 to 10, wherein the detector is configured to monitor the electrical flow through the planar antenna to determine, as a first2025PF8001025portion of the power conversion information, whether or not power is being supplied to the primary planar coil from the input interface, and / orthe detector is configured to process the determined electrical power in the auxiliary planar coil to determine, as a second portion of the power conversion information, an amplitude of power converted by the power conversion circuit.

12. The power converter of claim 11, wherein the detector is configured to monitor an envelope of the electrical flow through the planar antenna and determine whether or not power is being supplied to the primary planar coil from the input interface, in a frequency of AC mains, by comparing the monitored envelope to a predetermined threshold.

13. A solid-state lighting driver comprising:the power converter of any one of claims 1 to 12;the input interface, for connection to an input power supply; and the output interface, for connection to a solid-state light source.

14. A solid-state lighting device comprising the solid-state lighting driver of claim 13 and the sold-state light source connected to the output interface.

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