Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
  • H02J7/0042—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries characterised by the mechanical construction
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F38/00—Adaptations of transformers or inductances for specific applications or functions
  • H01F38/14—Inductive couplings
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
  • H02J50/10—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
  • H02J50/40—Circuit arrangements or systems for wireless supply or distribution of electric power using two or more transmitting or receiving devices
  • H02J50/402—Circuit arrangements or systems for wireless supply or distribution of electric power using two or more transmitting or receiving devices the two or more transmitting or the two or more receiving devices being integrated in the same unit, e.g. power mats with several coils or antennas with several sub-antennas
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
  • H02J50/70—Circuit arrangements or systems for wireless supply or distribution of electric power involving the reduction of electric, magnetic or electromagnetic leakage fields
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
  • H02J50/90—Circuit arrangements or systems for wireless supply or distribution of electric power involving detection or optimisation of position, e.g. alignment
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
  • H02J50/60—Circuit arrangements or systems for wireless supply or distribution of electric power responsive to the presence of foreign objects, e.g. detection of living beings

Definitions

• This invention relates to inductively coupled power transfer methods and systems. More particularly, although not exclusively, the invention relates to systems and methods for detecting devices and driving selected transmitter coils in multiple transmitter coil arrays.
• the power transmitter includes an array of transmitter coils beneath a charging surface that can accommodate a number of devices to be charged (commonly referred to as "charging mats").
• Charging mats a number of devices to be charged
• Many systems use small transmitter coil areas which means that the charging devices have to be tightly coupled to a small area.
• flexible alignment is required to allow the device to be charged anywhere on the charging surface. Doing this requires a method to detect the presence of the device to be charged.
• an inductively coupled power transfer system including an inductively coupled power transmitter having one or more transmitter coils proximate a charging surface and a device including an inductively coupled power receiver, a method of activating the inductively coupled power transmitter comprising: a. detecting a force applied by a device due to its placement on a charging surface to detect the presence of a device; and b. activating the inductively coupled power transmitter to transfer power to the device when a device is detected.
• an inductively coupled power transfer system including an inductively coupled power transmitter having a plurality of transmitter coils proximate a charging surface and a device including an inductively coupled power receiver, a method of activating the inductively coupled power transmitter comprising: a. detecting the presence of a device proximate to the charging surface utilizing one or more detection coils having an area much greater than that of each transmitter coil; and b. activating the inductively coupled power transmitter to transfer power to the device when a device is detected.
• an inductively coupled power transmitter having one or more transmitter coils suitable for transferring power to an inductively coupled power receiver of a device and a force detector that detects the presence of a potential device by monitoring forces applied to a surface of the power transmitter and activates the inductively coupled power transmitter upon detection of a potential device.
• an inductively coupled power transmitter having one or more transmitter coils suitable for transferring power to an inductively coupled power receiver of a device and a proximity detector that detects the presence and location of a potential device by monitoring the proximity of devices to a surface of the power transmitter and activates the inductively coupled power transmitter upon detection of a potential device.
• an inductively coupled power transmitter having one or more transmitter coils suitable for transferring power to an inductively coupled power receiver of a device and one or more detection coils each having an area much greater than that of the transmitter coils for detecting the presence of a potential device and activating the inductively coupled power transmitter.
• an inductively coupled power transfer system including an inductively coupled power transmitter having a plurality of transmitter coils proximate a charging surface and a device including an inductively coupled power receiver positioned on the charging surface, a method of selectively energizing selected transmitter coils comprising selecting a plurality of transmitter coil combinations and selecting the combination providing the coupling between the power transmitter and the power receiver meeting a selection criteria.
• an inductively coupled power transmitter for an inductively coupled power transfer system including a plurality of transmitter coils proximate a charging surface and a controller for selectively driving and monitoring the transmitter coils wherein the controller selectively energizes a plurality of combinations of transmitter coils and monitors the coupling between the power transmitter and a power receiver and during power transfer drives the combination of transmitter coils that has the coupling with the power receiver meeting a selection criteria.
• Figure 1 shows an inductively coupled power transmitter with devices to be charged placed thereon
• Figure 2 shows the inductively coupled power transmitter of figure 1 with the charging surface removed to reveal the transmitter coils with a receiver coil of a device to be charged overlaid;
• Figure 3 shows the inductively coupled power transmitter of figure 2 with the receiver coil in another orientation
• Figure 4 shows the inductively coupled power transmitter of figure 2 with the receiver coil in another orientation
• Figure 5 shows the inductively coupled power transmitter of figure 2 with transmitter coils driven with opposite polarity
• Figure 6 shows the inductively coupled power transmitter of figure 2 including a detection coil around the periphery
• Figure 7 shows the inductively coupled power transmitter of figure 2 including a pair of detection coils.
• FIG 1 there is shown an inductively coupled power transfer system including an inductively coupled power transmitter 1 supporting devices in the form of a phone 5 and camera 6 on charging surface 3. It will be appreciated that the invention may be applied to a wide range of power receiving devices. It will also be appreciated that devices 5 and 6 will typically include an inductively coupled power receiver including a pickup coil and a power receiving circuit and a rechargeable battery such as described in the applicant's prior application USSN 61/720,108.
• the inductively coupled power transmitter 1 includes a base 2 supported on legs 4 (optional) that contains a power transmitting circuit 7 (typically an inverter driving the transmission coils with a microcontroller and a switching circuit to selectively activate coils to be driven).
• a power transmitting circuit 7 typically an inverter driving the transmission coils with a microcontroller and a switching circuit to selectively activate coils to be driven.
• Figure 2 shows the charging surface 3 removed to expose the underlying transmission coils 8 to 19 to aid description of the operation of the power transmitter. Whilst 12 coils are shown in this embodiment it will be appreciated that the number of transmission coils could be anything from a few to hundreds. The coils may advantageously be arranged in a honeycomb pattern to achieve greater coil density but are shown as a simple array in the figures for simplicity.
• the power transmitter may be activated by detecting a force associated with a device being placed on the charging surface 3. "Activated" in this sense means to wake up the power transmitter from a standby state if inactive or to cause it to perform further detection if the power transmitter is already active.
• one or more load cells may be provided (for example in one or more feet 4) that supplies a signal to power transmitting circuit 7.
• a change in an applied static force due to a device being placed on or removed from the charging surface 3 may trigger the transmitting circuit to perform further detection using the transmission coils. This may be a single scanning step or a coarse scan followed by a fine scan etc.
• an accelerometer may be included in power transmitting circuit 7 (or some other position).
• An applied dynamic force due to a device being placed on or removed from the charging surface 3 may trigger the transmitting circuit to perform further detection using the transmission coils as above.
• a large detection coil 21 may be provided to detect the presence of one or more devices.
• a single coil 21 encompasses all transmitter coils 8 to 19.
• the detection coil 21 is much larger than the area of a power transmitter coils 8 to 19, at least three times the area of a single coil.
• the detection coil 21 is driven by the transmitter circuit to detect devices on charging surface 3.
• the detection coil 21 could also be used for near field communications with devices.
• the time taken for a number of zero crossings may be measured and a significant change may be used to activate the power transmitter.
• the number of zero crossings that occur in a period of time say 10ms may be counted.
• This method can lower the quiescent power draw of the power transmitter when no receivers are present whilst still allowing rapid detection of a power receiver.
• two detection coils 22 and 23 are employed. This localizes the scanning disturbance to one area of the charging surface and assists in locating the position of a detected device (i.e., full scanning is only required within the coil 22 or 23 that makes a positive detection).
• the charging surface 3 may incorporate a capacitive or resistive touch type sensor that can detect the presence and location of a device on the charging surface. This approach has the advantage that positional information may be obtained to assist in determining the transmitter coil combination to be driven as described below.
• the above detection methods can be used to detect whether a receiver has been added or removed in the charging area, which can trigger other tests to determine which receivers are still present and which charging coils to energise.
• the following methods may be employed to determine a selected combination of transmitter coils to drive to supply power to a power receiver.
• the receiving coil 20 is seen to be elliptical and it will be appreciated that receiving coils may have a range of geometries including generally rectangular, circular etc.
• the receiving coil 20 is elongate and larger than the transmitter coils 8 to 19.
• a scan may be performed using the transmitter coils to evaluate coupling between selected transmitter coils and a receiver coil (or several coils if there are several devices or a receiver has several coils).
• a detailed scan may be conducted for every scan or a coarse scan may be performed to determine the general location of a receiver coil and a detailed scan may then be performed within the general location to determine a combination of coils to be driven for each receiving coil.
• An effective technique for performing such evaluation is by measuring inrush current as described in USSN 61/696,341 annexed hereto.
• the inrush current is measured for all possible coil combinations and the combination meeting the selection criterion is selected. Due to the geometries of the transmitter and receiver coils in this embodiment combinations of three transmitter coils are assessed.
• the selection criterion is the coil combination having the highest inrush current. In the example shown in Figure 2 coils 10, 14 and 18 will have the highest inrush current and this combination will be driven. In the example shown in figure 3 coils 14, 18 and 19 will produce the greatest inrush current and so will be driven. In the example shown in Figure 4 coils 14, 15 and 18 will produce the greatest inrush current and so will be driven. It will be appreciated that depending upon the geometries of the transmitter coils and receiver coil(s) a wide range of transmitter coil geometries may be employed as the combination of transmitter coils to supply power to a receiver coil.
• the geometry of transmitter coil configurations may be restricted for a first coarse scan and once the general location of a receiving coil is established a detailed scan in that general location may be conducted.
• the geometry of the coil configurations may initially be restricted to linear arrays of three transmitter coils in one orientation (e.g. coils 8, 12, 16 etc.).
• the general location is established by finding the coil combinations with the highest inrush current then the inrush current of all possible coil combinations in the general location may be tested to find the best transmitter coil combination.
• the first coarse scan may proceed in a number of levels. Initially a number of widely spaced coils across the transmitter coil array may be tested and coils proximate the coil with the highest inrush current may then be tested so as to scan the transmitter coil array in ever increasing detail.
• the inrush current of all individual transmitter coils may be measured to find the general location of the receiver coil and then the best combination of coils determined. This could be as above where the inrush current of all possible coil combinations in the general location is tested to find the best coil combination. Alternatively the three coils with the highest inrush current could be selected. Alternatively the coil with the highest inrush current could be selected, then all adjacent coils tested in combination with the selected coil and finally the selected pair of coils may be tested in combination with all surrounding coils to find the three best coils.
• FIG. 5 shows a modification to the transmitter coil drive configuration described above.
• coils 10, 14 and 18 were determined to be the coils producing the highest inrush current.
• coils 10, 14 and 18 are driven with a common polarity and adjacent coils 9, 13, 17, 11 , 15 and 19 are driven with an opposite polarity (i.e. an out of phase alternating drive signal). In this way a stronger magnetic flux may be generated to increase power transfer.
• a further device being placed on charging surface 3 may be detected by a force associated with placement of the device or using a detection coil 21 or 22 and 23 or other similar means.
• a further device could be sensed using the transmitter coils 8 to 19 but this interrupts charging whilst the transmitter coils transferring power must be powered down.
• a hybrid approach may be adopted where both methods are employed but the transmitter coils are only scanned infrequently to minimise disruption of charging.
• the inverter driving the switching coils may be switched off and inrush current tests conducted for the coils or combinations of coils to be tested.
• the coil combinations with the best coupling are selected by the switching circuit and the inverter powered on again. This ensures that the power dropout to the power receivers is kept to a minimum.
• the active transmitter coils may be kept active except for one coil of the combination at a time so that the difference attributable to that coil may be assessed.
• the inrush current for one specific device can be measured without powering down all other devices in the meantime.
• the length of time that the inverter is switched off before the inrush test is executed may be varied. As the inrush test needs the receiver capacitance to be discharged to a fairly low level, the inverter needs to be switched off long enough for the capacitance to discharge, but short enough to minimise the voltage dropout at the receiver. This can be realised by running the test multiple times and increasing the power off time until a positive inrush test result is obtained.
• the test frequencies used for current inrush tests may be selected to ensure the maximum inrush current for a tuned receiver at different heights above the charging surface (for example tests may be run for minimum and maximum height values at between say 270kHz and 300kHz). If the inrush current is above a certain threshold, then it may indicate that a receiver is present.
• a foreign object test may also be conducted to detect any metal object placed on the charging surface and to avoid activating coils proximate it. When testing inrush current over a range of frequencies a metal object will have a relatively flat profile unlike a power receiver that will have a discernable peak over the frequency range.
• the optimal number, shape and position of the enabled transmitter coils to turn on may vary for different receiver coil sizes (eg. tablet, phone, camera etc.). By increasing the number of enabled transmitter coils until the inrush current or power draw stops increasing an effective transmitter coil combination may be determined in each case.
• To determine the status of devices charging the steady state current of the inverter may be periodically measured to determine a change in the power draw of all coupled receivers. The initial current draw through the inverter may be measured and used as a reference value. Periodically (say every second or so) the inverter current may again be measured and compared to the reference value. If the difference is above a pre-defined threshold then the transmitter coils may be scanned to measure inrush current to determine which receivers require power transfer.
• the new measurement may be stored as the new reference value (which will help track small current variances as the batteries charge), or the initial reference value may be maintained.
• the current change could indicate either a receiver being removed or a battery charge state changing. This can help minimise voltage dropouts using the inrush tests and minimise the number of times the full detection method is required (and hence further voltage dropouts).
• the current change test above won't be able to detect a receiver being added to the charging area, so using the detector coil or other activation technique described above will indicate whether a new receiver has been added. Upon detection of a new device a full current inrush test may be performed to find the specific locations of all the power receivers on the charging area.
• the power output by the power transmitter may be modified until an optimum is reached.
• the transmitter may keep increasing magnetic field strength generated by active transmitter coils until one or more power receiver stops accepting more power.
• the transmitter may start at a maximum value and keep decreasing magnetic field strength generated by active transmitter coils until power draw drops or a maximum efficiency point is reached.
• a power transmitter for an ICPT system having simple and power efficient activation with reduced noise and EMIs.
• a method for optimising the combination of transmission coils for a given coil geometry and orientation is also provided.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Computer Networks & Wireless Communication (AREA)
• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Charge And Discharge Circuits For Batteries Or The Like (AREA)

Priority Applications (7)

Applications Claiming Priority (2)

Related Child Applications (2)

Publications (1)

Family

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Family Applications (1)

Country Status (6)

Cited By (10)

Families Citing this family (29)

Citations (7)

Family Cites Families (86)

• 2013
  • 2013-11-05 EP EP13824213.6A patent/EP2915233A1/en not_active Withdrawn
  • 2013-11-05 CN CN201910316576.1A patent/CN110098642A/zh active Pending
  • 2013-11-05 WO PCT/NZ2013/000196 patent/WO2014070026A1/en not_active Ceased
  • 2013-11-05 US US14/440,456 patent/US10840748B2/en not_active Expired - Fee Related
  • 2013-11-05 KR KR1020157012911A patent/KR102283473B1/ko not_active Expired - Fee Related
  • 2013-11-05 JP JP2015540633A patent/JP6696771B2/ja not_active Expired - Fee Related
  • 2013-11-05 CN CN201380057861.7A patent/CN104885324B/zh not_active Expired - Fee Related
  • 2013-11-05 KR KR1020217023554A patent/KR20210096686A/ko not_active Ceased
• 2020
  • 2020-01-21 JP JP2020007325A patent/JP6986104B2/ja not_active Expired - Fee Related
  • 2020-10-30 US US17/085,846 patent/US20210050750A1/en not_active Abandoned

Patent Citations (7)

Non-Patent Citations (1)

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