WO2015155774A1

WO2015155774A1 - Wireless power outlet

Info

Publication number: WO2015155774A1
Application number: PCT/IL2015/050377
Authority: WO
Inventors: Arik Rofe; Ilya GLUZMAN; Elieser Mach
Original assignee: Powermat Technologies Ltd
Current assignee: Powermat Technologies Ltd
Priority date: 2014-04-10
Filing date: 2015-04-08
Publication date: 2015-10-15
Anticipated expiration: 2016-10-10

Abstract

A wireless power outlet configured to transmit power to a wireless power receiver is provided. The wireless power outlet comprises a metal shielding comprising a substantially circular base and a core protruding therefrom, a primary inductive coil constituted by two substantially circular windings one atop the other and giving rise to an internal space, the core being received within the space, and a power source comprising a driver configured to provide an oscillating driving voltage to the primary inductive coil. The base has a diameter which is at least about 10% larger than an outer diameter of the windings, the circular windings comprise a wire having between 165 and 175 thin wire strands, and the space formed within the winding has a diameter between 20 and 21mm.

Description

WIRELESS POWER OUTLET

FIELD OF THE INVENTION

The present disclosure relates to wireless power outlets, and to methods of transferring power thereby.

BACKGROUND OF THE INVENTION

The use of a wireless non-contact system for the purposes of automatic identification or tracking of items is an increasingly important and popular functionality.

Inductive power coupling allows energy to be transferred from a power supply to an electric load without a wired connection therebetween. An oscillating electric potential is applied across a primary inductor. This sets up an oscillating magnetic field in the vicinity of the primary inductor. The oscillating magnetic field may induce a secondary oscillating electrical potential in a secondary inductor placed close to the primary inductor. In this way, electrical energy may be transmitted from the primary inductor to the secondary inductor by electromagnetic induction without a conductive connection between the inductors.

When electrical energy is transferred from a primary inductor to a secondary inductor, the inductors are said to be inductively coupled. An electric load wired in series with such a secondary inductor may draw energy from the power source wired to the primary inductor when the secondary inductor is inductively coupled thereto.

SUMMARY OF THE INVENTION

According to one aspect of the presently disclosed subject matter, there is provided a wireless power outlet configured to transmit power to a wireless power receiver, the wireless power outlet comprising:

• a metal shielding comprising a substantially circular base and a core protruding therefrom; a primary inductive coil constituted by two substantially circular windings one atop the other and giving rise to an internal space, the core being received within the space; and

a power source comprising a driver configured to provide an oscillating driving voltage to the primary inductive coil;

wherein:

• the base has a diameter which is at least about 10% larger than an outer diameter of the windings;

• the circular windings comprise a wire having between 165 and 175 thin wire strands; and

• the space has a diameter between 20 and 21mm.

The wire may be litz wire.

The wire may consist of 170 strands.

The diameter of each of the strands may be provided such that it is no more than twice the skin depth of the conductive material of the wire, at an operating AC current and frequency of the wireless power outlet.

Each of the windings may be formed having nine turns.

The shielding may be made from a material selected from magnesium ferrite and nickel.

The core may be substantially circular and configured to be snuggly received within the space formed within the winding.

The core may be substantially circular and have a diameter of about 20mm.

The base may have a thickness of about 2.75mm.

The shielding may have a thickness of about 6mm.

The wireless power outlet may have a quality-factor of at least about 140.

The wireless power outlet may be configured to operate in a range between about lOOkHZ and about 500kHz.

The wireless power outlet may further comprise a controller configured to direct operation thereof. BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the embodiments and to show how it may be carried into effect, reference will now be made, purely by way of example, to the accompanying drawings.

With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of selected embodiments only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects. In this regard, no attempt is made to show structural details in more detail than is necessary for a fundamental understanding; the description taken with the drawings making apparent to those skilled in the art how the several selected embodiments may be put into practice. In the accompanying drawings:

Fig. 1 is a schematic illustration of a wireless power outlet according to the presently disclosed subject matter;

Fig. 2 is a top view of a primary inductive coil of the wireless power outlet illustrated in Fig. 1 ; and

Figs. 3A and 3B are top and side views, respectively, of a shielding of the wireless power outlet illustrated in Fig. 1.

DETAILED DESCRIPTION

As illustrated in Fig. 1, there is provided a wireless power outlet 410, such as an inductive power outlet, a resonant power outlet, or the like, constituting an inductive transmitter adapted to transmit electrical power wirelessly to a secondary unit (such as a wireless power receiver, e.g., an inductive receiver; not illustrated) remote therefrom. The wireless power outlet 410 comprises a primary inductive coil 412 connected to a resonant circuit 414 constituting a power source and comprising, inter alia, a driver 416. The driver 416 is configured to provide an oscillating driving voltage to the primary inductive coil 412. The wireless power outlet 410 may further comprise a controller 418, such as a microcontroller unit, to direct operation thereof. For example, the controller 418 may be configured to implement the different phases described below. The wireless power outlet 410 may be designed to operate in any suitable range, for example about 100kHz to about 500kHz. The wireless power outlet 410 as described herein may be configured to communicate with a suitable receiver. Such a receiver may, inter alia, be configured to transmit signals to the wireless power outlet 410, which the wireless power outlet is configured to decode and take suitable actions based thereon. For example, the receiver may be configured to transmit some or all of the following:

• Inc signals, indicating that the frequency of power transfer should be incremented;

• Dec signals, indicating that the frequency of power transfer should be decremented;

• No-ch signals, indicating that power transfer should not be changed;

• EOP signals, indicating that the power transfer should be ended; and

• other signals indicating receiver status, receiver information, etc.

It will be appreciated that the above is a partial list, and the receiver may be configured to transmit any other suitable signal per the requirements of a designer or suitable specification.

According to one example, as illustrated in Fig. 2, the primary inductive coil 412 comprises two windings 420, arranged one atop another as layers. Each of the windings 420 comprises a single low-resistance wire 422 which is coiled, forming a substantially circular shape and giving rise to an internal space 424 therewithin. The wire 422 may be formed having nine turns, or any suitable number of turns. The primary inductive coil 412 (i.e., the windings 420) has an outer diameter Dl and an inner diameter (i.e., the diameter of the space 424) D2. The outer diameter may be as per need, for example no less than 53.5mm. The inner diameter may be as small as possible, e.g., between 20 and 21mm, for example about 20.5mm.

The wire 422 may comprise a plurality of thin wire strands, individually insulated and twisted and/or woven together. The strands may be organized in several levels, e.g., groups of twisted wires twisted together. According to some modifications, the wire 422 may be a litz wire, e.g., having a low AC-resistance (i.e., impedance). The litz wire may be provided according to any suitable design, many of which are known in the art and available in a wide variety of configurations.

According to some modifications, the litz wire comprises between 165 and 175 strands, e.g., 170 strands. It has been found that a litz wire with this number of strands has an advantage over other designs of litz wires, in that it results in an optimal quality-factor compared to using other tested litz wires. Increasing the number of strands in a multi-strand wire, such as litz wire, tends to lower the resistance (and thus increasing quality-factor), while increasing the minimum inner diameter possible when forming a winding 420, as well as proximity effects, e.g., owing to parasitic capacitance (both of which tend to increase the quality-factor). It has been found that a litz wire of 170 strands, or approximately thereof, optimizes the quality-factor when all other design considerations of the wireless power outlet remain the same.

According to other medications, the diameter of each of the strands of the litz wire is no more than twice the skin depth associated with its conductive material. This maximizes the amount of material of the strands which conduct the current through the primary inductive coil 412.

One having ordinary skill in the art may be determine the skin depth for a material given the intended AC current and frequency of the wireless power outlet 410. For example, it may be approximated by:

δ = ^/(ω-μ μο)]¹¹²

where:

• <5 is the skin depth;

• p is the resistivity of the material;

• co is the angular frequency of the current (i.e., 2π times the frequency);

• μ_τ is the relative magnetic permeability of the conductor; and

• μο is the permeability of free space.

According to some modifications, the primary inductive coil 412 may comprise a single winding 420, e.g., to reduce parasitic capacitance which may arise. In order to provide such a primary inductive coil, care must be taken that winding 420 is designed so as to provide an appropriate inductance.

As illustrated in Figs. 3A and 3B, the wireless power outlet 410 may further comprise a shielding 426 below the primary inductive coil 412. The shielding 426 comprises a base 428, which may be substantially circular, and a core 430 (so called as it constitutes of metallic core of the windings 420) protruding upwardly therefrom. It may be made of any suitable material for the frequency range in which the wireless power outlet 410 operates, such as a metal. According to some modifications, it is made from a ferrite material, such as magnesium ferrite. According to other modifications, for example at relatively higher frequencies, the material of the shielding 426 may be nickel.

The diameter of the base 428 may be at least 10% greater than the outer diameter of the windings 16. According to some modifications, the diameter of the base 428 is at least about twice the outer diameter of the windings. The diameter of the core 430 is suitable to fit within, e.g., be snuggly received within, the space 424 formed within the windings 420, and may be, e.g., 20mm. The overall thickness of the shielding 426 (i.e., the thickness of the base 428 and core 430 together) may be about 6mm.

The windings 420 are disposed such that the core 428 of the shielding 426 is received within the space 424 therewithin. This provides a better magnetic conductance compared to what would be provided if the space 424 was filled with air. Furthermore, it may provide a magnetic snag, facilitating alignment of a receiver.

Depending, e.g., on an intended power level and thermal management strategy, the wireless power outlet 410 may comprise an optional metal carrier (not illustrated) below the shielding 426 (i.e., on the side thereof opposite the windings 420). The metal carrier may be provided according to any suitable design, as is well known in the art.

The windings 420, shielding 426, and optional carrier may be co-disposed such that central axes thereof are coincident with one another.

It has been found that a wireless power outlet 410 designed as per the above has an increase quality-factor compared to other designs. For example, a quality- factor of about 140 may be realized. The increased quality-factor increases the optimal magnetic efficiency of the wireless power outlet 410, even when a couple having a low coupling factor is formed with a suitable receiver, for example which may result from relatively high coil to coil distances.

One having ordinary skill in the art may determine the quality-factor for the wireless power outlet 410 according to any suitable method. For example, it may be given by:

Q = (OoLIR

where:

• Q is the quality-factor;

• a>o is the resonance frequency in radians per second; • L is the inductance of the primary inductive coil 412; and

• R is the resistance of the primary inductive coil.

The driver 416 may operate with an input voltage of between 18.5V and 19.5V. According to some examples, the driver 416 is configured to operate at an input voltage of 18V. The resistance of the driver may be 30 milliohms. According to some examples, it may be up to 150 milliohms. It may be further configured to operate with a default duty cycle of 50% +/- 5% in a half-bridge mode. At the high end of the operational range (i.e., the highest frequency at which the wireless power outlet 410 is designed to operate), the duty cycle may vary between 10% and 50%. The driver 416 may be further configured to vary the phase offset between 10% and 100% in a full-bridge mode.

The wireless power outlet 410 may be configured to sense a power carrier voltage signal associated with the primary inductive coil 412, e.g., using a magnitude detector (not illustrated), as is known in the art. In the event that the value of the voltage signal exceeds a predefined level, the wireless power outlet 410 may be configured to stop its power signal and enter a Standby phase, as will be described below.

The wireless power outlet 410 may comprise protection mechanisms, e.g., for over-voltage, over-temperature, over-decrement, and/or over-current occurrences conditions.

The wireless power outlet 410 may be further configured to detect a suitable receiver (not illustrated) placed thereof. Accordingly, it may comprise a detection unit (not illustrated) configured to implement an analog pinging method, e.g., using a periodic short pulse applied to the primary inductive coil 412. By measuring the resultant interference on the primary coil, the presence of a receiver can be detected. The pinging pulse's characteristics may be as follows:

• a short pulse comprising a pack of 3 rectangular wave pulses at a frequency of 175±10kHz with a duty cycle of 10+1%;

• the time between sequential packets is 25 -250ms; and

• a detection is determined if the voltage difference between the voltage measured on the primary inductive coil 412 measured with and without a suitable receiver present is higher than 2.7V. The wireless power outlet 410 may be configured to operate in one of a Standby phase, a Digital Ping phase, an Identification phase, a Power Transfer phase, and an End of Power phase. Each of these phases may be as described below.

In the Standby phase, the wireless power outlet 410 monitors a Tx charging surface (i.e., the surface thereof where the receiver is to be placed) thereof to detect a possible receiver placement. The monitoring may be done by using the detection unit as described above.

If the Standby phase is reached due to an error state as described below, the wireless power outlet 410 may be configured to wait for receiver removal before proceeding to monitoring the surface for receiver placement.

If a receiver placement is detected, e.g., by the detection unit, the wireless power outlet 410 may be configured to continue to the Digital Ping phase. The time for the phase change may be between 23 and 250ms, e.g., 200ms.

The wireless power outlet 410 may be configured to implement detection of a receiver using an analog ping as described above.

Once a receiver is detected, the wireless power outlet 410 may be configured to enter the Digital Ping phase, in which it engages with a possible receiver and identifies whether or not it is a valid (i.e., compatible) receiver. It accomplishes this by generating a digital ping signal as described below. If sufficient power is delivered to the receiver by the generated digital ping, the receiver will respond by suitably modulating the power signal.

The Digital Ping phase may comprise the following two-stage procedure:

• In a first stage, the wireless power outlet 410 is configured to produce digital pings designed to induce a maximal voltage on a reference receiver having an inductance of 4.7μΗ and with no load attached thereto, and operating with a coupling factor of 0.4, in the range of 4-6V.

• If no response is received from the receiver for at least a predetermined number of consecutive digital pings in the first stage, the wireless power outlet 410, a second stage, is configured to produce digital pings designed to induce a maximal voltage on the reference receiver with no load attached thereto, and operating with a coupling factor of 0.55, in the range of 8-10V. If the wireless power outlet 410 receives a valid response from the receiver during the Digital Ping phase, it is configured to continue to the Identification phase without removing the power signal.

If an EOP signal is received from the receiver during the Digital Ping phase, the wireless power outlet 410 is configured to continue to the End of Power phase.

If no response was detected during a predetermined period of time, the wireless power outlet 410 is configured to return to the Standby phase.

The wireless power outlet 410 may be configured to advertise its Tx-type during the Digital Ping phase. Advertising of the Tx-type may be performed by frequency modulation of the power carrier signal.

The Digital Ping phase may be delayed for a time period of between 23 and 250ms, for example 200ms, after a suitable receiver has been detected (i.e., after the last active analog ping signal).

The Digital Ping phase may be characterized by the following:

The duration of the digital ping may be between 26.0 and 28.0ms.

In the first part of the digital ping, a frequency sweep from a minimum frequency (which may be between 285kHz and 315kHz, for example 300kHz) is generated. The duration of the frequency sweep is between 1 and 4ms.

After the frequency sweep, the wireless power outlet 410 advertises its type. The advertising may comprise frequency modulation of the power carrier signal. The modulation may use Manchester coding with a modulation depth between 5 and 10kHz, and have a symbol length between 475 and 525μπι, for example 500μπι. A 12-bit identification code (8 bits of data & 4 bits of CRC calculation) is transmitted cyclically between 1 and 4ms after the start of the Digital Ping signal and after the sweep period is over. Transmission of the code is repeated for between 19 and 22ms. The frequency is not modulated for a period no longer than 1ms between each of the retransmissions of the identification code. The last retransmission of the identification code may begin after 15ms, measured from the start of the digital ping.

After the advertising period, the wireless power outlet 410 remains at a frequency of between 220 and 226, for example at 223, for a time period of between 5 and 7ms. During this time, the wireless power outlet 410 may read data sent from the receiver.

• A valid response from the receiver comprises at least a predetermined number, which may be between 5 and 15, of consecutive Dec signals. Any other signal received is interpreted by the wireless power outlet 410 as invalid response. After the reception of the valid data signals from the receiver, the wireless power outlet 410 transitions to the identification phase. If no valid response is received by the wireless power outlet 410 during the first Digital Ping period, the power signal is stopped, and it waits between 30 and 300ms, for example 150ms, before starting a subsequent Digital Ping.

• The wireless power outlet 410 generates a total of 5 retries of the Digital Pings signals if no valid response is received from the receiver in each of those retries. If no response is received from the receiver during any one of the Digital Pings signals, the wireless power outlet 410 transitions to the Standby phase.

The 8 bits of data of the identification code may be characterized in that the five most significant bits carry a type code (i.e., MSB0-MSB4, wherein MSB4, which is the most significant bit of the type code, and thus of the identification code) is always set to 0), and the three least significant bits thereof carry a capability code.

The two most significant bits of the capability code carry information relating to extended signaling (ES) support, wherein:

• ObOO represents standard signaling;

• ObOl represents unidirectional ES support;

• 0b 10 represents bidirectional ES support; and

• Obi 1 represents continuous bidirectional ES support.

The least significant bit of the capability code indicates RXID verification.

The 4 bits of data of the CRC calculation are in accordance with the CRC-4 defined in ITU Telecommunication Standardization Sector (ITU-T) standard for synchronous frame structures designated G.704.

In the Identification phase, which begins upon completion of the Digital Ping phase (i.e., when the predetermined number of consecutive Dec signals are received), the wireless power outlet 410 is configured to identify an RXID (i.e., a unique MACID of a receiver) returned by the receiver, and to verify that it is a compliant device. The wireless power outlet 410 may be configured so as to not support an Identification phase, in which case it continues with the Power Transfer Phase.

The Identification phase comprises a Minimal Ping Frequency sub-phase, a Stabilization sub-phase, and an optional RXID retry attempt.

In the Minimal Ping Frequency sub-phase, the wireless power outlet 410 provides a constant power signal with an operational frequency between 220 and 226kHz, e.g., 223kHz. The wireless power outlet 410 is configured to determine that the Minimal Ping Frequency sub-phase is completed, and proceed with the Stabilization sub-phase, if one of the following situations occurs:

• A time period, measured from the first Dec signal received during the Digital Ping phase, of t_wait4Rx = 35ms is exceeded.

• A signal other than Dec signal is received from the receiver.

During the stabilization sub-phase, the receiver stabilizes the power it receives from the wireless power outlet 410. The wireless power outlet 410 is configured to adjusts its operational frequency according to the DEC, INC and/or No-ch signals received from the receiver, as described below with reference to the Power Transfer phase.

After the time period t_wai,4_Rx elapses, the wireless power outlet 410 is configured to read the RXID data or adjust its operational frequency according to signals received from the receiver (e.g., as described below with reference to the Power Transfer phase).

The wireless power outlet 410 is configured to receive the RXID preamble byte, followed by the rest of the RXID data sequence, for a predetermined time period of between 230 and 250ms after the reception of the predetermined number of consecutive signals Dec signals from the receiver.

Upon receipt of the last byte of the RXID message, the wireless power outlet 410 is configured to calculate the CRC during a predetermined amount of time, e.g., 20ms. If the CRC is valid, the wireless power outlet 410 is configured to transition to the Power Transfer phase.

The wireless power outlet 410 is configured to perform retries of the identification phase if one of the following scenarios occurs:

• any of the RXID bytes are missing an ST or SP bit; • the RXID preamble byte is not 0x00;

• the message ID byte is not compliant;

• during the RXID message transmission, a Data Loss (data timeout) occurrence is detected;

• CRC calculation is followed with an invalid CRC result;

• the wireless power outlet does not receive the preamble byte during the predetermined time period of between 230 and 250ms.

If the wireless power outlet 410 begins one or more RXID retry attempts, it removes the power carrier by moving into the Standby phase and waiting for a wait period of at least 250ms. According to some modifications, the wait period may range between at least 30ms to at least 300ms. After the wait period, the wireless power outlet 410 restarts the Digital Ping phase, thereby forcing the receiver to repeat the Identification phase. The wireless power outlet 410 may be configured to attempt five RXID retry attempts. According to some modifications, the wireless power outlet 410 is be configured to attempt one RXID retry attempt.

After exhausting the retries and if not successful, the wireless power outlet 410 is configured to remove the power carrier and wait for receiver removal, and subsequently transition to the Standby phase.

When the receiver is placed in full alignment, the time period from receiver detection (i.e., last Analog Ping) to the beginning of the Power Transfer phase shall be no longer than 1000ms. When the receiver is placed within a supported misalignment distance (as described below), the transition shall be no longer than 5000ms.

During the Power Transfer phase, the wireless power outlet 410 is configured to regulate its delivered power by adjusting the operation frequency according to the receiver's requests, e.g., by changing its primary coil current. This is done in response to Dec signals or Inc signals.

If an EOP signal is received from the receiver, or the temperature exceeds a maximum predefined value (as described below), the wireless power outlet 410 is configured to cease the power signal and continue to the End of Power phase.

The wireless power outlet 410 may be configured to perform each adjustment within 50μ8 from reception of a valid request from the receiver. The wireless power outlet 410 may be configured to use a shall use a Fast First-Order Tracking (FFOT) algorithm to control its operational frequency according to feedback provided by the receiver in order to meet the required power input.

The receiver is configured to request an increase, decrease, or no change in the delivered power.

The wireless power outlet 410 is configured to decimate every two Dec signals, such that only one of every two Dec signals creates a change in operation point. Furthermore, it is configured to decimate every five Inc signals, such that only one of every five Inc signals creates a change in operation point. According to some modifications, the wireless power outlet 410 is configured to decimate every six Inc signals, such that only one of every six Inc signals creates a change in operation point

When receiving a Dec signal, the wireless power outlet 410 is configured to decimate every two successive Dec signals, and, after the 2^nd signal, to decrease its operation frequency by between 1.4 and 4.0kHz. This change is only performed if the new operation point is no less than a predefined minimum operation frequency of between 196.0 and 200.0kHz, for example 198.0kHz.

When receiving an Inc signal after a non-Inc signal, the wireless power outlet 410 is configured to increase its operation frequency. If the Inc signal is followed by additional Inc signals, the wireless power outlet is configured to decimate a predetermined number (which may be five or six) successive Inc signals, and only after receiving the predetermined number of Inc signals to increase its operation frequency by between 1.4 and 4.0kHz. This change is only performed if the new operation point is no greater than a predefined maximum operation frequency of between 296.0 and 304.0kHz, for example 200.0kHz.

The wireless power outlet 410 is configured to maintain its current operation point upon receipt of a No-ch signal (i.e., a signal from the receiver indicating that power transfer should not be changed).

The wireless power outlet 410 may be configured to move to its minimum operational frequency (maximal power transfer) irrespective of its starting frequency upon receipt of 100 consecutive Dec signals.

The wireless power outlet 410 may be configured to move to its maximum operational frequency (minimal power transfer) irrespective of its starting frequency upon receipt of 180 consecutive Inc signals. The wireless power outlet 410 may be configured to transition to the End of Power phase if it receives an EOP signal from the receiver, in which case it removes the power carrier for a predetermined period of time of between 5 and 280 minutes, e.g., 15 minutes. After the predetermined period of time expires, the wireless power outlet 410 is configured to step into the Digital Ping phase and try to reengage with the receiver.

In addition, the wireless power outlet 410 may be configured to transition to the End of Power phase if the temperature exceeds a predetermined level, as described below. The wireless power outlet 410 is configured in this case to remove the power carrier and monitor its temperature and detection sensors until the measured temperature returns to below the predetermined level, then to proceed to the Digital Ping Phase.

In addition, the wireless power outlet 410 may be configured to transition to the End of Power phase if other predetermined error conditions are detected.

The wireless power outlet 10 may be further configured to proceed to the Standby Phase if the receiver removal occurs during any part of the End of Power phase.

The wireless power outlet 410 may be configured to detect foreign objects placed on its charging surface, for example by using a combination of different sensors.

The wireless power outlet 410 may be configured to measure the primary coil peak voltage during all phases of operation and, if it exceeds a predetermined value, to stop the power signal and wait for receiver removal. It subsequently transitions to the Standby phase. In addition, it may be configured to measure the primary coil current and, if it exceeds a predetermined maximum current value, to stop the power signal and wait for receiver removal, after which it transitions to the Standby phase.

The wireless power outlet 410 may be further configured to implement a backup mechanism of temperature measurement during all phases, according to which the wireless power outlet transitions to the End of Power phase if the temperature exceeds a predetermined value, and wait until the temperature drops to below the predetermined value.

The wireless power outlet 410 may be further configured to receive and decode Consumed Power reports from the receiver and, if a Consumed Power report indicates that the power consumed by the receiver is lower than a predetermined amount, to assume that a foreign object has been placed on its charging surface. It may then stop the power signal and wait for receiver removal, after which it transitions to the Standby phase.

The wireless power outlet 410 may determine that a Data-Loss condition has occurred when fewer than five sequences of at least two legal signals are received during a time period of 300ms.

The wireless power outlet 410 may determine that an Over- Decrement condition occurs when it receives more than a predetermined number (e.g., between 500 and 1000) of Dec signals from the receiver, while it operates in its maximal energy transfer operational point. This may occur, e.g., when the wireless power outlet 410 cannot provide sufficient power to the receiver during the Identification Phase or during the Power Transfer Phase, possibly due to a coil to coil misalignment or mismatch in the power requirements of the receiver and inductive power outlet.

The wireless power outlet 410 may be configured to transit to the End of Power phase when an Over-Temperature condition of over 60 °C is detected on a charging surface thereof.

The wireless power outlet 410 may be configured to transition to the Standby phase when an error scenario is detected. Error scenarios may include, but are not limited to, any one or more of the following:

• no valid data received from the receiver during the Digital Ping phase and all retries procedures have been exhausted;

• an Over- Voltage condition occurs;

• an Over-Current condition, as described above, occurs;

• an Over-Input Voltage condition occurs;

• a Data-Loss condition, as described above, occurs;

• an Over-decrement condition, as described above, occurs; and

• an invalid receiver ID (RXID) is received.

According to some examples, the wireless power outlet 410 may be configured to generate a retry procedure if a Data Loss condition is detected during the Power Transfer phase. The retry procedure may comprise the wireless power outlet 410 stopping the power signal for a period between 30 and 300ms, e.g., 150ms, and then restarting the Digital Ping phase. The retry procedure is done once for each occurrence of a Data Loss condition, and may be limited in number (e.g., five occurrences of a Data Loss condition per receiver placement session, i.e., between receiver placement and receiver removal). If the wireless power outlet 410 detects a the removal of the receiver, it may transition to the Standby phase and not restart the Digital Ping. The wireless power outlet 410 is configured to stop the power signal and wait for receiver removal, and then subsequently transition to the Standby phase, if the occurrence of a Data Loss condition continues after the retry procedure and the receiver is still placed on the wireless power outlet.

The wireless power outlet 410 may be configured such that power consumption thereof while no receiver is placed thereon, averaged across the periods of standby and analog ping bursts, does not exceed 1W.

It may be further configured such that the average power consumption thereof while a receiver is placed thereon, but is not actively supplying power thereto shall not exceed:

1W - [(2W x Carrier_Active_Time)/hour] where Carrier_Active_Time is the active time of the power carrier during a one hour period (summation of the digital ping periods until reception of an EOP signal and power carrier removal).

The wireless power outlet 410 may be configured to ensure that, during the full charge cycle, it will continually indicate to the user ongoing charging and any removal of the receiver.

The wireless power outlet 410 may be configured so as to not generate any audible noise exceeding 30dB SPL when measured at a distance of lm therefrom.

The wireless power outlet 410 may be configured so as to not interfere with the operation of the device powered thereby.

The wireless power outlet 410 may be configured to support a minimum power delivery from the primary inductive coil 412 of 8.5W for Power Classes from 0-5W.

The wireless power outlet 410 may be configured to support operation (i.e., charging) of a reference receiver when placed on top thereof with minimum misalignments.

According to some examples, the wireless power outlet 410 supports a misalignment wherein the following conditions are met: • the distance between the primary inductive coil 412 and the Tx charging surface of the wireless power outlet is up to 4mm;

• a gap between the Tx charging surface and the receiver is up to 3mm;

• the receiver has a spacer of up to 0.8mm between a secondary inductive coil there and an Rx charging surface (i.e., the surface thereof which is placed on the Tx charging surface); and

• the distance, measured in a plane parallel to the charging surface, between the centers of the primary inductive coil 412 and of the secondary inductive coil is up to 6mm.

According to other examples, for example wherein a receiver is specifically designed to operate with the wireless power outlet 410 (sometimes called an "enhanced receiver"), the wireless power outlet supports a misalignment wherein the following conditions are met:

• the distance between the primary inductive coil 412 and the Tx charging surface of the wireless power outlet is up to 4mm;

• a gap between the Tx charging surface and the receiver is up to 7mm;

• the receiver has a spacer of up to 0.8mm between the secondary inductive coil and the Rx charging surface; and

• the distance, measured in a plane parallel to the charging surface, between the centers of the primary inductive coil 412 and of the secondary inductive coil is up to 12mm.

It will be appreciated that the above represent minimum requirements. According to either of the above examples, the wireless power outlet 410 may support operation of a reference receiver when any one or more of the distances is greater than that listed above.

The wireless power outlet 410 may be configured to transmit a TACR (transmitter advanced capabilities reporting) message to indicate its extended capabilities. The capabilities field may include, e.g., values indicating one or more of the power levels supported, extended range support, extended signaling support, WPTN (wireless power transfer network) support, and multimode support.

The wireless power outlet 410 may be configured to support extended power operation for Power Class 0 and up to Power Class 5 power levels. It may be configured, e.g., when operating at the Class 5 power levels, to from using a half bridge topology to a full bridge topology for its power carrier driver.

Those skilled in the art to which this invention pertains will readily appreciate that numerous changes, variations and modifications can be made without departing from the scope of the invention mutatis mutandis.

Technical and scientific terms used herein should have the same meaning as commonly understood by one of ordinary skill in the art to which the disclosure pertains. Nevertheless, it is expected that during the life of a patent maturing from this application many relevant systems and methods will be developed. Accordingly, the scope of the terms such as computing unit, network, display, memory, server and the like are intended to include all such new technologies a priori.

The terms "comprises", "comprising", "includes", "including", "having" and their conjugates mean "including but not limited to" and indicate that the components listed are included, but not generally to the exclusion of other components. Such terms encompass the terms "consisting of and "consisting essentially of.

The phrase "consisting essentially of means that the composition or method may include additional ingredients and/or steps, but only if the additional ingredients and/or steps do not materially alter the basic and novel characteristics of the composition or method.

As used herein, the singular form "a", "an" and "the" may include plural references unless the context clearly dictates otherwise. For example, the term "a compound" or "at least one compound" may include a plurality of compounds, including mixtures thereof.

The word "optionally" is used herein to mean "is provided in some embodiments and not provided in other embodiments". Any particular embodiment of the disclosure may include a plurality of "optional" features unless such features conflict.

Whenever a numerical range is indicated herein, it is meant to include any cited numeral (fractional or integral) within the indicated range. The phrases "ranging/ranges between" a first indicate number and a second indicate number and "ranging/ranges from" a first indicate number "to" a second indicate number are used herein interchangeably and are meant to include the first and second indicated numbers and all the fractional and integral numerals therebetween. It should be understood, therefore, that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the disclosure. Accordingly, the description of a range should be considered to have specifically disclosed all the possible subranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1, 2, 3, 4, 5, and 6 as well as non- integral intermediate values. This applies regardless of the breadth of the range.

It is appreciated that certain features of the disclosure, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the disclosure, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination or as suitable in any other described embodiment of the disclosure. Certain features described in the context of various embodiments are not to be considered essential features of those embodiments, unless the embodiment is inoperative without those elements.

Although the disclosure has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the disclosure.

All publications, patents and patent applications mentioned in this specification are herein incorporated in their entirety by reference into the specification, to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present disclosure. To the extent that section headings are used, they should not be construed as necessarily limiting.

Claims

CLAIMS:

1. A wireless power outlet configured to transmit power to a wireless power receiver, the wireless power outlet comprising:

• a metal shielding comprising a substantially circular base and a core protruding therefrom;

• a primary inductive coil constituted by two substantially circular windings one atop the other and giving rise to an internal space, said core being received within the space; and

• a power source comprising a driver configured to provide an oscillating driving voltage to said primary inductive coil;

wherein:

• said base has a diameter which is at least about 10% larger than an outer diameter of said windings;

• said circular windings comprise a wire having between 165 and 175 thin wire strands; and

• said space has a diameter between 20 and 21mm.

2. The wireless power outlet according to claim 1, wherein said wire is litz wire.

3. The wireless power outlet according to any one of claims 1 and 2, wherein said wire consists of 170 strands.

4. The wireless power outlet according to any one of the preceding claims, wherein the diameter of each of said strands is no more than twice the skin depth of the conductive material of the wire, at an operating AC current and frequency of the wireless power outlet.

5. The wireless power outlet according to any one of the preceding claims, wherein each of said windings is formed having nine turns.

6. The wireless power outlet according to any one of the preceding claims, wherein said shielding is made from a material selected from magnesium ferrite and nickel.

7. The wireless power outlet according to any one of the preceding claims, wherein said core is substantially circular and is configured to be snuggly received within said space.

8. The wireless power outlet according to any one of the preceding claims, wherein said core is substantially circular and has a diameter of about 20mm.

9. The wireless power outlet according to any one of the preceding claims, wherein said base has a thickness of about 2.75mm.

10. The wireless power outlet according to any one of the preceding claims, wherein said shielding has a thickness of about 6mm.

11. The wireless power outlet according to any one of the preceding claims, having a quality-factor of at least about 140.

12. The wireless power outlet according to any one of the preceding claims, configured to operate in a range between about lOOkHZ and about 500kHz.

13. The wireless power outlet according to any one of the preceding claims, further comprising a controller configured to direct operation thereof.