[go: up one dir, main page]

WO2012085119A2 - Récepteur de puissance sans fil pour recevoir un signal de puissance sur un couplage inductif, et amélioration du procédé de mise en œuvre d'un récepteur de puissance sans fil - Google Patents

Récepteur de puissance sans fil pour recevoir un signal de puissance sur un couplage inductif, et amélioration du procédé de mise en œuvre d'un récepteur de puissance sans fil Download PDF

Info

Publication number
WO2012085119A2
WO2012085119A2 PCT/EP2011/073643 EP2011073643W WO2012085119A2 WO 2012085119 A2 WO2012085119 A2 WO 2012085119A2 EP 2011073643 W EP2011073643 W EP 2011073643W WO 2012085119 A2 WO2012085119 A2 WO 2012085119A2
Authority
WO
WIPO (PCT)
Prior art keywords
load
resonator
wireless power
power receiver
receiver
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/EP2011/073643
Other languages
English (en)
Other versions
WO2012085119A3 (fr
Inventor
Harri Elo
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of WO2012085119A2 publication Critical patent/WO2012085119A2/fr
Publication of WO2012085119A3 publication Critical patent/WO2012085119A3/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

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
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of AC power input into DC power output; Conversion of DC power input into AC power output
    • H02M7/02—Conversion of AC power input into DC power output without possibility of reversal
    • H02M7/04—Conversion of AC power input into DC power output without possibility of reversal by static converters
    • H02M7/12—Conversion of AC power input into DC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/21—Conversion of AC power input into DC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/217—Conversion of AC power input into DC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M7/2176—Conversion of AC power input into DC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only comprising a passive stage to generate a rectified sinusoidal voltage and a controlled switching element in series between such stage and the output
    • 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
    • H02J50/12—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling of the resonant type

Definitions

  • a wireless power receiver for receiving a power signal over an inductive coupling, and an improvement in the method for operating a wireless power receiver
  • the present invention relates to wireless power transfer, in particular to rectification and regulation of regenerated alternating voltage by a wireless power receiver.
  • Wireless power transfer is a new, strongly emerging industry segment. The idea dates more than a Centillium back, from onset of electrical industry. There is an application of wireless power transfer, which has recently gained plenty of publicity: recharging of batteries of mobile devices. Examples of these devices are cell phones, MP3 players, cameras, electrical books and laptops. It should be pointed out wireless power transfer is not the only and not even the most efficient way of recharging. That is, there is always the usual way of plugging a wire in the device or the battery for supply of power.
  • inductive antenna which is also the inductive portion of an LC resonator.
  • Maximum efficiency of power transfer depends on coupling coefficient between the antennae, which in turn depends on geometry of system of the two antennae. Aiming at 70 %
  • NFC Near Field Communication
  • peers of an typical NFC transaction are an initiator, which generates a magnetic field, and a target, which usually does not generate a field.
  • the initiator is able to supply the target via the magnetic field, in which case one speaks about a passive target. Thereby, the initiator is in effect a wireless power
  • the prefered embodiment minimises component count, cost and size of the device, while maximising the performance.
  • Wireless power transfer is no exception: there is a need for technology, which fulfills the said design constrains, covering also domain of moderate efficiency.
  • An objective of the invention is to improve the efficiency of wireless power transfer, or to enable improving of the same, especially in a situation where the distance between the wireless power receiver from a circuit that transmits power to the wireless power receiver is in the order of (as large as) the antenna size, or larger.
  • This objective can be achieved with a wireless power receiver according to claim 1, and with the improved method according to claim 8.
  • a wireless power receiver that is suitable i) for receiving a power signal over an inductive coupling from a power
  • transmitting circuit that comprises a voltage generator and ii) for passing it to a load comprises:
  • a resonator for receiving a power signal over the inductive coupling, the resonator being suitable for converting a changing magnetic flux at its input port to an AC voltage at its output port;
  • energy storage means comprising at least one inductive component and at least one capacitive component for storing energy comprised in the power signal received by the resonator;
  • - a rectifying and regulating circuitry for rectifying and regulating the received power signal before passing it to a load .
  • the improvement in the wireless power receiver is characterized in that the rectifying and regulating circuitry comprises a buck regulator that is configured to carry out impedance matching between the load and the resonator.
  • the transmitting circuit comprising a voltage generator and to pass it to a load
  • the power receiver comprising:
  • resonator for receiving a power signal over the inductive coupling, the resonator being suitable for converting a changing magnetic flux at its input port to an AC voltage at its output port;
  • - energy storage means comprising at least one inductive component and at least one capacitive component for storing energy comprised in the power signal received by the resonator;
  • a rectifying and regulating circuitry for rectifying and regulating the received power signal before passing it to a load; and is improved by using in the rectifying and regulating circuitry a buck regulator that is configured to carry out impedance matching between the load and the resonator.
  • the inventor has found out that surprisingly good power transfer efficiency for wireless power transfer can be achieved by using a buck converter in the wireless power receiver for impedance matching .
  • the buck regulator is implemented with a control integrated circuit operating two changeover switches, the buck regulator can be controlled via the integrated circuit. This increases the control possibilities of the wireless power receiver and so also its versatility.
  • the buck regulator is configured to perform resistive and/or reactive load modulation, semiconductor switches, resistive components and/or reactive components maay be omitted which are conventionally used for implementation of a modulator.
  • efficiency or output power of the wireless power transfer system may be increased, compensating for resistive or reactive impedance mismatch, respectively.
  • the microcontroller of the rectifying and regulating circuitry is configured i) to switch off the load, ii) to make the buck regulator to operate on an internal load which is constant for a period of time for determining the optimal pulse position, and iii) to switch on the load and disable the internal load, disturbances caused by switching noise that might disturb the wireless power receiver can be better avoided.
  • circuitry is configured, in steady state, to use the buck regulator to measure pulse positions in regular intervals, in particular by measuring weighed pulse widths of adjacent bins, and whenever it seems beneficial to decrement or increment the bin index employed for power transmission, the operation efficiency of the wireless power receiver in steady state can be maintained over time.
  • microcontroller is configured to request more or less power based on temporal variations in loading conditions, in particular the requesting being done over a data transfer channel from the wireless power receiver to the power
  • the amount of power that is received by the wireless power receiver may be controlled by the wireless power receiver itself.
  • abrupt changes in loading conditions are handled by means of impedance matching and long term steady state is maintained by means of data transfer between the wireless power receiver and the power transmitting circuit .
  • FIG 1 is a simplifed schematic of a state of the art
  • wireless power transfer system is a simplifed schematic of a wireless power transfer system, which comprises the inventive circuit ; llustrates a combined rectifier and regulator; show different ways to implement a MOS switch; shows a controller inherent in circuitry of FIG 3; is a diagram of steady state waveforms associated with combined rectification and regulation; is a small signal equivalent of a wireless power transfer system; is a flow chart model of the wireless power receiver; illustrates implementation of an exhaustive search algorithm; is a small signal equivalent of a wireless power transfer system, which was used for comparing performance of a state of the art embodiment and tl invented embodiment of a wireless power receiver; provides a comparison between theoretical
  • FIG 15 shows some examples of receiver circuit topologies known from prior art compared with the wireless power receiver according to the present invention
  • FIG 16 illustrates simulated performance of different
  • FIG 17 illustrates the equivalent circuit for wireless
  • FIG 18 two rectifiers known from prior art and a buck
  • FIG 19 efficiency vs. load for two values of QK
  • FIG 20 a resonator which is loaded by a periodic current source
  • FIG 21 an adapted configuration of the wireless power
  • FIG 22 a transistor level implementation of the wireless power receiver.
  • regenerated signal are the essential functionalities of a wireless power receiver. It is the general object of this invention to introduce an embodiment with capability to
  • switch mode regulators are implemented by means of two semiconductor switches, one of which connects reactive components of the regulator to the input voltage, whereas the other switch provides a current path, while the input is detached.
  • the said switches are controlled by an integrated circuit, which monitors the output and adjust duty cycle of the control based on measured output voltage.
  • AC voltage may be both rectified and regulated by means of the same circuitry.
  • wireless power receivers which ordinarily comprise one piece of circuitry for rectification and an other one for regulation, this is an improvement.
  • the invention advises a way of practical implementation, which provides the closest match between the theoretical and the realisable efficiency: due to intelligent way of power acquisition, the receiving resonator may be loaded by the impedance which maximises the efficiency.
  • the other major advantage of the invention is likewise based on inventiveness of concurrent rectification and regulation.
  • reactances of individual components are random variables. Consequently, manufactured receivers are never identical to the nominal design.
  • the invented circuit provides a new degree of freedom: besides of width of current pulses, their temporal position is relevant. As the matter of fact, by controlling timing of the pulses in an appropriate manner, one is able to compensate for the said tolerances and thereby maximise both effiency and output power. In other words, a means of active power factor correction is introduced.
  • Yet an other advantage of the invention is related to data transmission functionality, which is usually a desired property of wireless power transfer systems.
  • data transmission functionality which is usually a desired property of wireless power transfer systems.
  • FIG 1 shows a simplifed schematic of a state of the art wireless power transfer system.
  • a transmitter 100 comprises an AC voltage generator 101, a capacitor 103 and an inductor 104. Together, capacitor 103 and inductor 104 compose an LC resonator. Resistor 102 represents inevitable losses of a practical inductor and capacitor.
  • a receiver 200 comprises likewise a lossy LC
  • the receiver 200 comprises a rectifier 210 and a regulator 220.
  • the receiver is coupled to the transmitter 100 in magnetic fashion via a mutual inductance 300. Strength of this coupling is characterised by means of coupling coefficient K.
  • the receiver 200 is loaded by a resistor 400, when ever enabled by a load enable switch 401.
  • the rectifier 210 is a diode bridge rectifier, which is composed of four diodes and an output capacitor 211.
  • the regulator 220 is a buck regulator, which comprises a changeover switch 221, an integrated control circuit 222, an inductor 223 and a capacitor 224.
  • the switch 221 may be implemented by means of a MOS transistor between the rectifier 210 and the inductor 223 and a diode, anode of which is grounded, while the cathode is
  • circuit elements of the switch 221 do not necessarily need to be discrete semiconductor devices, as they may be integrated in the control circuit 222.
  • FIG 2 shows a simplifed schematic of a wireless power transfer system, which comprises an inventive circuit implementing functionalities of both the rectifier and the regulator.
  • the transmitter 500, the mutual inductance 700 and the load 800 are identical to their counterparts in FIG 1.
  • resonator comprising an inductor 601, a capacitor 602 and a resistor 603 is the same as the one comprising the inductor 201, the
  • resistance 603 is Q2 times larger than resistance 203. It is to be emphasised this is a difference between the presentations, but not between the physical circuits.
  • FIG 2 shows an inventive circuit 610, which combines the said
  • the resonator is connected to a MOS transistor 614, an inductor 615 and a capacitor 616.
  • an integrated control circuit 611 of FIG 2 is the counterpart of the circuit 222 of FIG 1: it also measures the output voltage and controls switches at input of the regulator.
  • the circuit 611 measures voltage difference between output terminals of the resonator and determines the appropriate control signal based on knowledge of both the input and the output voltage of the combined rectifier and regulator 610.
  • an inductor 104 and capacitor 103 of the transmitter side LC resonator are connected in series with an AC voltage generator 101 and a resistor 102, which represents losses of the LC resonator.
  • the voltage generator 101 There are several known ways to implement the voltage generator 101. For instance, input terminals of the LC resonator may be periodically switched between some DC voltage and short circuit. As this switching is applied at resonant frequency of the LC resonator, the input signal is in effect a square wave, fundamental frequency of which is band pass filtered by the resonators and coupled to the receiver .
  • the capacitor 602 and the inductor 601 are connected in parallel with the resistor 603, which represents losses of the receiver side LC resonator.
  • Terminals of the LC resonator are connected to the changeover switches 612 and 613, which thereby connect the resonator to the buck converter composed of the transistor 614, the inductor 615 and the capacitor 616.
  • the control circuit 611 is connected to terminals of the LC resonator, to control electrodes of the switches 612 and 613, and to the output node, which connects the inductor 615 to the capacitor 616.
  • FIG 3 shows a more detailed view of the circuit 610, which conducts both rectification and regulation.
  • transistors There are various kind of transistors, all of which may be used as switches:
  • the changeover switch 612 is implemented by means of PMOS
  • the changeover switch 613 is implemented by means of NMOS transistors.
  • the load enable switch 801 is implemented by means of a PMOS transistor, which is integrated in the control circuit 611 in case of FIG 3.
  • An NMOS transistor conducts, as the gate voltage exceeds the source voltage by V T,NM0S , which is specific for the
  • the switch 613 behaves in a passive manner like diodes of a diode bridge.
  • PMOS transistors of the switch 612 are controlled by the control circuit 611. Therefore, inductor and capacitor of the buck converter load the resonator only by request of the control circuit, which monitors the output voltage and instantanous voltage over the resonator and determines sufficient position and duration of pulses applied on gates of the PMOS transistors.
  • the loop is closed and the buck converter is connected in parallel to the resonator. Consequently, a fragment of energy is transfered to the buck and finally to the load.
  • switches 612 and 613 not all of the details are shown in FIG 3: neither of the switches may be implemented simply by means of two MOS transistors.
  • MOS transistors are used as switches, a practical phenomen needs to be taken into account: in any enhancement type MOS transistor, there is always a diode embedded in the device. As signals with bipolar swing are controlled by means of MOS switches, these diodes are forward biased. This happens, as source voltage of an NMOS transistor exceeds its drain voltage or as drain voltage of an PMOS transistor exceeds its source voltage.
  • FIG 4a shows an approach in which two transistors 41 are connected in series in such a way that either of the bulk diodes (also known as body diodes) which is formed by the PN junction and is always reverse biased.
  • FIG 4c shows an approach in which two transistors 43 are connected in series in such a way that either of the bulk diodes is always reverse biased.
  • Fig 4b shows an approach in which a resistor 45 is connected between source and bulk electrodes of the transistor 46 in series in such a way that potential leakage current through the bulk diode is significantly reduced.
  • Fig 4d shows an approach in which a resistor 47 is connected between source and bulk electrodes of the transistor 48 in series in such a way that powetential leakage current through the of bulk diode is significantly reduced.
  • One of the approaches shown in FIG 4a to 4d needs to be employed in order to prevent undesired leakage of the switch.
  • FIG 5 shows an exemplary view of the control circuit 611. It comprises a microcontroller core 5005 with the following peripherals: an analog to digital conversion (ADC) unit 5001, a differential amplifier 5011, some data and program memory 5009, a NOR gate 5013, five discrete MOS transistors 5015, 5017, 5019, 5021, 5023, a digital to analog conversion (DAC) unit 5003 and a phase locked loop (PLL) 5007.
  • ADC unit converts the measured analog quantities, voltage between terminals of the resonator and over the load, into digital presentation format, which is readable for the microcontroller 611.
  • the ADC unit may comprise two separate converters or the inputs may be time division multiplexed for a single converter.
  • Voltages of individual terminals of the resonator are accessed via input signals AIN and BIN, difference of which is determined by means of the differential amplifier and supplied to the ADC unit.
  • the other input of the ADC unit is SUPPLY, which is also supply voltage of the control circuit. In case of a prior art buck regulator, this would be the only monitored signal.
  • the switch 613 behaves in a passive manner like diodes of a diode bridge, whereas PMOS transistors of the switch 612 are controlled by the control circuit 611.
  • the control circuit comprises two NMOS transistors, which control the switch 612 by driving signals AOUT and BOUT. Unless supply voltage of the
  • microcontroller core 5005 exceeds an implementation dependent treshold value, the microcontroller 611 is not able to operate and drive the NMOS transistors.
  • outputs of the microcontroller 611 are in high impedance state, the NMOS transistors controlling the switch 612 are driven by AIN and BIN and the whole "diode bridge" operates in a passive manner. That is, the control circuit implements two modes of operation: it is powered up in passive mode, but operates in active mode in the steady state. In the steady state, AIN and BIN are most of the time driven low by the microcontroller 611. Therefore, fragmented sine wave instead of a continuous one is delivered to the ADC unit.
  • a transistor may be a discrete device or integrated in a circuit.
  • transistors 614 and 801 are integrated in the control circuit.
  • the former drives signal C providing continuous current path for the output inductor 615.
  • the transistor 614 is driven in active mode by the NOR gate.
  • the transistor 801 implements the load enable switch .
  • the PLL synchronises internal timing of the microcontroller 611 to oscillation of the resonator.
  • the microcontroller 611 Based on analog to digital converted fragments of the sine wave, the microcontroller 611 calculates the phase error twice per period and delivers the result to the PLL, which is locked, as the phase error vanishes.
  • the memory block comprises non-volatile memory for the embedded program as well as volatile memory for intermediate calculation results and temporary variables. Also, portions or all of the executable code may be copied to the volatile memory on power up for shorter access times. Purpose of the DAC unit and the transistor connected to SUPPLY will be explained below.
  • FIG 6 shows an example of steady state waveforms associated with combined rectification and regulation.
  • the signals shown in FIG 6 are voltage over the resonator comprising components 601, 602 and 603, current flowing through the capacitor 602 and current flowing through the capacitor 615. The most interesting
  • instances of time are ⁇ and ⁇ 2 shown in FIG 6.
  • the microcontroller 611 drives BIN high, thereby driving BOUT low. In this case, the PMOS transistor connected to BOUT conducts.
  • the microcontroller 611 drives AIN high, thereby driving AOUT low. In this case, the PMOS transistor connected to AOUT conducts.
  • the output voltage is not shown in FIG 6.
  • the output signal is a sum of a DC voltage and switching frequency ripple, which in practice vanishes with sufficient value of output capacitance 616.
  • FIG 7 illustrates a problem related to practical implementation of wireless power transfer systems.
  • the circuit shown is a small circuit equivalent of coupled resonators of FIG 1 and 2.
  • the system of two resonators is reduced into simplified representation on right side of FIG 7.
  • the simplified system comprises a sine wave generator, transmitter and receiver side resistances and an impedance Z, which may be capacitive or inductive.
  • Z vanishes (gets shorted) maximising the output power.
  • the signal frequency may be calibrated during the manufacturing in a way that it equals the resonant frequency of the resonator.
  • the receiver has no control over the signal frequency, a more inventive solution is needed.
  • the receiving resonator has no means to determine whether it is loaded by an active source or a passive impedance. Therefore, the combined rectifier and regulator appears in general case as a complex load impedance, magnitude and phase of which depend on amplitude and position of the current pulses drawn from the resonator.
  • the said impedance is a parallel connection of a resistor and a capacitor, but in case the pulses are applied within the second and the fourth quardant, the effective load impedance is a parallel connection of a resistor and an
  • the inventive circuit provides a way to adjust resonant frequency of the resonator and compensate for the finite tolerances.
  • the actual resonant frequency is always higher or lower than the nominal resonant frequency. Too high resonant frequency is compensated by means of parallel capacitance, whereas too low resonant frequency is compensated by means of parallel inductance. That is, the appropriate quadrant for the load pulses is selected based on sign of difference between the nominal and the actual resonant frequency. After that, the resonant frequency may be fine tuned by adjusting position of the pulses within the selected
  • the effective load impedance depends on their width and amplitude. The width, in turn, depends on voltage swing over the resonator and the amplitude depends on the load resistance 800. Finally, amplitude of the resonating signal depends not only on effective load on the receiver, but also on signal amplitude and output impedance of the transmitter. Unless the pulse position is optimised and the effective resonant frequency thereby fine tuned, the loop impedance may be too high, as advised in FIG 7, and the receiver may fail to provide sufficient power to the output. This problem is solved by means of the DAC unit and the transistor driven by it in FIG 5. In beginning of a power transfer session, the microcontroller 611 disables the load by means of the transistor switch 801.
  • the control circuit may concentrate in determination of the optimal pulse position.
  • the load current should be fairly large, close or equal to the supported maximum load current, in order to emulate the most challenging conditions.
  • the internal load is disabled and the external one enabled.
  • the software executed by the microcontroller 611 divides each half cycle of the resonating signal in N bins.
  • Bin 0 is the first bin of the first and the third quadrant, whereas bin N - 1 is the last bin of the second and the fourth quadrant.
  • Current pulses, which are applied twice per period, are aligned to one of these N bins.
  • Choice of the bin determines phase of the effective load: bin 0 maximises capacitance, whereas bin N - 1 maximises inductance. Centers of the bins are located at temporal positions tn.
  • the microcontroller 611 may be configured to maintain impedance matching between the resonator and output power of the wireless power receiver, thereby confining
  • FIG 8 shows an exemplary flow chart modeling operation of the inventive wireless power receiver.
  • the flow chart is implemented by means of an algorithm executed by the microcontroller 611. As the receiver is brought in magnetic field of wireless power transmitter, charge and thereby also voltage of capacitor 616 starts to increase (step A801), as electrical charge is
  • Control circuit 611 is supplied by capacitor 616 and is therefore powered up and able to operate only after voltage of capacitor 616 reaches a certain level (e.g. 3 volt) .
  • the receiver operates in passive manner (step A803) until the supply voltage is sufficient for operation of the microcontroller 611.
  • the microcontroller 611 wakes up, it enables the internal load and disables the external load in a manner described above.
  • the software executed by microcontroller 5005 starts (step A805) an exhaustive search for the optimal bin for the current pulses. Comparison of two consequtive bins is based on width of current pulses in case of constant internal load, which is considered a stationary condition. Within the first and the third quadrant, width of the pulses is expected to decrease with increasing bin index, whereas the opposite is expected within the second and the fourth quadrant .
  • FIG 9 illustrates an exemplary implementation of the exhaustive search algorithm in more detail.
  • the default bin is N/2.
  • width of the current pulses, W N /2 is stored in memory.
  • adjacent bins N/2-1 and N/2+1 are tested in the same manner.
  • best impedance matching that far is achieved at bin N/2+1. Therefore, it does not make sense to test any other bins preceeding N/2. Instead, the search is extended further in the second quadrant.
  • weighed pulse width is compared to that of the previous bin.
  • unit of W n is radians.
  • weighed pulse width of bin N/2+5 is larger than that of N/2+4, the latter bin provides the best matching between the operating frequency and effective resonant frequency of the receiving resonator, and the search may be terminated .
  • n was considered the optimal bin after exhaustive search, weighed pulse width would be W n and weighed pulse widths associated with the neighbour bins, W n _i and W n+ i are expected to be larger than W n . In the steady state this is confirmed in regular intervals, by decrementing or incrementing bin index, waiting until the output voltage settles and determining whether the weighed pulse width really increases.
  • the said neighbour bin Given the neighbour bin yields a smaller weighed pulse width, the said neighbour bin should be used thereafter, until a new comparison justifies a new change of bin index.
  • the microcontroller 611 disables the internal load and enables the external load and waits until the output voltage settles e.g. within 5 % (step A807 in FIG 8) .
  • the receiver operates in steady state. However, as parameters like operating frequency may vary over time, the receiver needs to keep on monitoring impact of pulse position in order to ensure the timing remains optimal. Therefore, weighed pulse widths of the adjacent bins are measured in regular intervals in a manner shown in FIG 8: in step A809 bins for t n and t n _i are measured.
  • step A811 it is determined whether it is beneficial to decrement the bin index employed for power transmission from n to n-1. If yes, in step A809 the bin index is further decremented by one. If not, in step A813 the bin index is incremented by one.
  • step A815 it is determined whether it is beneficial to increment the bin index employed for power transmission from n to n+1. If yes, in step A813 the bin index is further
  • step A809 the software waits until a timer expires (e.g. after one second) and returns to step A809.
  • a timer interrupt may be made use of in implementing the said regular interval between individual updates of the optimal bin.
  • the transmitter needs to match its resonant frequency to the operating frequency. In case of the transmitter, this is fairly straightforward, as it controls the operating frequency. In case of FIG 8, we are assuming that the transmitter has determined and frozen the operating frequency by the time microcontroller 611 of the receiver wakes up and starts searching for the optimal pulse position. In the steady state, the transmitter keeps on monitoring the loop impedance and potentially adjusting the operating frequency. This is no problem from perspective of the receiver: it maintains
  • a data transfer channel at least a unidirectional one from the power receiver to the power transmitter.
  • the receiver is able to request for more or less power from the transmitter based on temporal variations in loading conditions.
  • the data transfer channel enables remote regulation of power transfer.
  • FIG 10 shows a simplified model of a wireless power transfer system, which was used for comparing performance of a state of the art diode bridge rectifier 1011 and the invented combined rectifier and regulator.
  • performance of a passive rectifier is compared to that of an active one.
  • the simulation was conducted with four different values of coupling coefficient K (0,003; 0,01; 0,03; and 0,1) to load 1013 (for which R L was 40 ⁇ , 7 ⁇ , 4 ⁇ and 3 ⁇ , respectively.
  • K amplitude of the input signal and the load
  • resistance RL were chosen such way that the output voltage was ca. 5 V in case of the active rectifier.
  • Magnitude of impedances of the reactances was 10 ⁇ at the resonance frequency, which was equal to the signal frequency and the same for both of the resonators.
  • Q value of the resonators was 100.
  • FIG 12 shows performance of the active rectifier by means of thick lines and loop impedance dependent performance of the passive rectifier by means of square, circle and triangle symbols. Evidently, efficiency of power transfer may be improved a lot by choosing the appropriate loop impedance, in case of which there is not much difference between the passive and the active rectifier implementation. Also, FIG 12 shows that there is no categorically optimal impedance level of a passive receiver. Instead, Z 0PT (QK) increases with decreasing QK .
  • synchronous rectifier in case of which each of the four diodes of the rectifier 210 in FIG 1 is replaced by a MOS transistor, but otherwise the circuit topology is remained the same. As was implied previously, this is the way MOS switches of FIG 3 work, before the microcontroller 611 is powered up.
  • a synchronous rectifier is by definition an active rectifier, given the transistors are controlled by a microcontroller 611 or a respective circuit.
  • ⁇ ( ⁇ ⁇ ) is similar to that of a diode bridge
  • each of the four transistors reverses its role twice per period, from cut off to conductive state and back, yielding transients similar to those in FIG 13.
  • FIG 14 illustrates the maximum efficiency of wireless power transfer. Almost all practical implementations are based on LC resonators, which are coupled in an inductive manner. Therefore, as can be seen in FIG 14, the maximum efficiency is strongly dependent on product of quality factor Q and coupling
  • the coupling coefficient depends on geometry of the system i.e. form factor of the inductive antennae and distance between them.
  • the receiver In most applications of wireless power transfer, besides of picking up magnetic flux generated by the transmitter and turning it into voltage, the receiver needs to rectify the recovered power in order to supply DC voltage to the load.
  • the said rectification process always consumes some power, but in most cases also introduces an effective load, which yields lower efficiency than the value shown in FIG 14.
  • FIG 15 shows some examples of receiver circuit topologies known from prior art compared with the wireless power receiver according to the present invention (in FIG 15 the rightmost circuit). Combination of a conventional diode bridge rectifier and a regulator (in FIG 15 the leftmost circuit) is still the most common way to implement a wireless power receiver.
  • FIG 16 illustrates simulated performance of the diode bridge rectifier, the combined rectifier/regulator and the optimal - so far never manifested - performance of the FET bridge.
  • dead-time is exactly zero, which is however never a practical case.
  • a finite dead-time needs to be applied twice per period in order to prevent short circuiting the resonator via two (/four) FETs unintentionally conducting simultanously.
  • the dead-time is not an issue.
  • a regulator is unavoidable.
  • efficiency of this regulator is 95 %, which may be an optimistic value. Based on these assumptions, theoretical efficiency of the FET bridge comes pretty close to the theoretical optimum, but only in case of one particular value of load resistance. In comparison, the novel circuitry synthesises a close to optimal load resistance, in effect hiding the actual load.
  • typical load impedance is a lot larger than resonator impedance, which is in order of 100 ⁇
  • the impedance is increased by increasing inductance (and decreasing capacitance). Volume of an inductor increases with its inductance yielding a form factor, which is less suitable for devices like cell phones.
  • the wireless power receiver can be used in particular in the following applications:
  • Q is quality factor of the resonators and K coupling coefficient between them.
  • the transmitter is supplying receiver impedance R(QK) 2 via its output resistance R.
  • the shown system does not actually transfer power to any meaningful load but it rather burns the supplied power in the resonators.
  • the load may however not be coupled directly to the resonator. Instead, the resonator is ordinarily loaded by combination of a rectifier, regulator and the actual load resistance. Regulation and rectification are ideally lossless operations - in best
  • the resonator is loaded by a periodic current source, period of which equals that of the transmitted signal convoying power. Based on simple arithmetics, i.e. Fourier series expansion of the current wave
  • Fundamental frequency in-phase component of the series expansion represents the real power transferred to the load.
  • Fundamental frequency quadrature phase component of the series expansion represents the reactive power i.e. in effect a parallel capacitance or inductance depending on phase shift between resonator voltage and the current pulses .
  • the resonator In the steady state , the resonator has no way to determine whether it is loaded by an active current source or a passive impedance. That is, the periodic current source is perceived as a lumped resistor connected in parallel to an optional capacitor or inductor. Magnitude and phase of the load impedance are dictated by amplitude, duration and phase of the current pulses.
  • the rectifier In the latter case, the rectifier is transparent exposing the load as such to the resonator, whereas an optimal effective load may be
  • the novel circuit may e.g. double or triple the output power with the same total power consumption of the system.
  • the "steady state” means that amplitude of the resonating signal remains roughly constant long enough to be considered
  • the regulator is able to handle bipolar input - and rectifies/regulates concurrently, by means of the very same circuitry.
  • the control circuit is able to synchronise switching frequency to oscillation of the resonator and synthetise optimal load for the particular resonator impedance and quality factor.
  • C(tco) and D(tco) are functions of a continuous angular variable and to is the instantanous phase of oscillation of the resonator.
  • the changeover switches By means of the changeover switches, the output inductor and capacitor are connected periodically in parallel to the resonator.
  • the control signal is synchronised to the oscillation, in effect constant amplitude and polarity is introduced to the output components - in the same manner, as in case of more conventional DC to DC conversion.
  • neither of the changeover switches conducts, and current path is provided via the right hand side on-off switch. See also the transistor level implementation of FIG 22.
  • four leftmost transistors may conduct e.g. 10 % of time instead unavoidable 50 % of the bridge rectifier case. Power reduction by a factor of 5 reduces size of the transistors by a factor 5.
  • Source impedance of the transmitter is not negligible in respect to the impedance introduced by the load.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Rectifiers (AREA)
  • Dc-Dc Converters (AREA)
  • Control Of Eletrric Generators (AREA)
  • Near-Field Transmission Systems (AREA)

Abstract

l'invention concerne un récepteur de puissance sans fil (6) pour recevoir un signal de puissance sur un couplage inductif (300) d'un circuit de transmission de puissance (100) comprenant un générateur de tension (101) et pour le transférer à une charge (800), le récepteur de puissance sans fil (6) comprenant : - un résonateur (601, 602, 603) pour recevoir un signal de puissance sur le couplage inductif (300), le résonateur (601, 602, 603) étant approprié pour convertir un flux magnétique variable sur son port d'entrée en une tension alternative sur son port de sortie ; - des moyens de stockage d'énergie (601, 602) comprenant au moins un composant inductif (601) et au moins un composant capacitif (602) pour stocker l'énergie comprise dans le signal de puissance reçu par le résonateur (601, 602, 603) ; et - des éléments de circuit de redressement et de régulation (610) pour redresser et réguler le signal de puissance reçu avant de le transférer à une charge (800). L'amélioration est caractérisée en ce que les éléments de circuit de redressement et de régulation (610) comprennent un régulateur Buck (611, 612, 613, 614, 615, 616) qui est configuré pour effectuer une adaptation d'impédance entre la charge (800) et le résonateur (601, 602, 603). La demande de brevet comprend également une revendication de brevet indépendante pour une amélioration du procédé de mise en œuvre d'un récepteur de puissance sans fil.
PCT/EP2011/073643 2010-12-21 2011-12-21 Récepteur de puissance sans fil pour recevoir un signal de puissance sur un couplage inductif, et amélioration du procédé de mise en œuvre d'un récepteur de puissance sans fil Ceased WO2012085119A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI20100427 2010-12-21
FI20100427A FI20100427L (fi) 2010-12-21 2010-12-21 Menetelmä ja laite samanaikaista tasasuuntausta, säätöä ja tehokertoimen korjausta varten

Publications (2)

Publication Number Publication Date
WO2012085119A2 true WO2012085119A2 (fr) 2012-06-28
WO2012085119A3 WO2012085119A3 (fr) 2012-10-11

Family

ID=43414954

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2011/073643 Ceased WO2012085119A2 (fr) 2010-12-21 2011-12-21 Récepteur de puissance sans fil pour recevoir un signal de puissance sur un couplage inductif, et amélioration du procédé de mise en œuvre d'un récepteur de puissance sans fil

Country Status (2)

Country Link
FI (1) FI20100427L (fr)
WO (1) WO2012085119A2 (fr)

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015127303A1 (fr) * 2014-02-23 2015-08-27 Apple Inc. Adaptation d'impédance pour systèmes de transfert de puissance inductive
WO2015127127A1 (fr) * 2014-02-23 2015-08-27 Apple Inc. Filtre d'ajustement dans un système de bobine couplé
GB2527312A (en) * 2014-06-17 2015-12-23 Advanced Risc Mach Ltd Harvesting power from ambient energy in an electronic device
WO2016050633A3 (fr) * 2014-09-30 2016-06-02 Drayson Technologies (Europe) Limited Système de transfert de puissance inductive
US9537353B1 (en) 2014-06-03 2017-01-03 Apple Inc. Methods for detecting mated coils
CN106464021A (zh) * 2014-05-20 2017-02-22 富士通株式会社 无线电力传输控制方法以及无线电力传输系统
CN106464022A (zh) * 2014-05-22 2017-02-22 富士通株式会社 受电器、无线电力传输系统以及kQ值计算方法
US9685814B1 (en) 2014-06-13 2017-06-20 Apple Inc. Detection of coil coupling in an inductive charging system
NO20161441A1 (en) * 2016-09-12 2017-10-23 Kongsberg Seatex As Method for control of a parallel resonant current-driven inductive coupler and parallel resonant current-driven inductive coupler
US9813041B1 (en) 2014-07-31 2017-11-07 Apple Inc. Automatic boost control for resonant coupled coils
US10014733B2 (en) 2014-08-28 2018-07-03 Apple Inc. Temperature management in a wireless energy transfer system
US10032557B1 (en) 2014-05-29 2018-07-24 Apple Inc. Tuning of primary and secondary resonant frequency for improved efficiency of inductive power transfer
US10193372B2 (en) 2014-09-02 2019-01-29 Apple Inc. Operating an inductive energy transfer system
US10211676B2 (en) 2015-08-25 2019-02-19 Otis Elevator Company Electromechanical propulsion system having a wireless power transfer system
US10389274B2 (en) 2017-04-07 2019-08-20 Apple Inc. Boosted output inverter for electronic devices
EP3528365A1 (fr) * 2018-02-19 2019-08-21 Naptilus Technology Lab, S.L. Appareil de syntoniseur et de redresseur pour récepteur de transfert de puissance sans fil
US10411516B2 (en) 2016-10-28 2019-09-10 General Electric Company System and method for actively controlling output voltage of a wireless power transfer system
US10523063B2 (en) 2017-04-07 2019-12-31 Apple Inc. Common mode noise compensation in wireless power systems
US10574096B2 (en) 2013-10-29 2020-02-25 Panasonic Corporation Wireless power transmission apparatus and wireless power transmission system
US10644531B1 (en) 2016-09-22 2020-05-05 Apple Inc. Adaptable power rectifier for wireless charger system
US10666084B2 (en) 2015-07-10 2020-05-26 Apple Inc. Detection and notification of an unpowered releasable charging device

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5135204B2 (ja) * 2008-12-26 2013-02-06 株式会社日立製作所 非接触電力伝送システム、および該非接触電力伝送システムにおける負荷装置
US8338991B2 (en) * 2009-03-20 2012-12-25 Qualcomm Incorporated Adaptive impedance tuning in wireless power transmission
WO2010115867A1 (fr) * 2009-04-09 2010-10-14 Siemens Aktiengesellschaft Transmission de puissance bidirectionnelle et sans contact pour la charge de véhicules électriques

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None

Cited By (45)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10574096B2 (en) 2013-10-29 2020-02-25 Panasonic Corporation Wireless power transmission apparatus and wireless power transmission system
US10116279B2 (en) 2014-02-23 2018-10-30 Apple Inc. Impedance matching for inductive power transfer systems
JP2017506485A (ja) * 2014-02-23 2017-03-02 アップル インコーポレイテッド 誘導電力伝送システムのインピーダンス整合
CN106030972B (zh) * 2014-02-23 2020-03-31 苹果公司 耦接线圈系统中的调节滤波器
CN106030957A (zh) * 2014-02-23 2016-10-12 苹果公司 针对感应式功率传输系统的阻抗匹配
CN106030972A (zh) * 2014-02-23 2016-10-12 苹果公司 耦接线圈系统中的调节滤波器
WO2015127127A1 (fr) * 2014-02-23 2015-08-27 Apple Inc. Filtre d'ajustement dans un système de bobine couplé
AU2015218896B2 (en) * 2014-02-23 2018-03-29 Apple Inc. Adjusting filter in a coupled coil system
US9923383B2 (en) 2014-02-23 2018-03-20 Apple Inc. Adjusting filter in a coupled coil system
AU2015218706B2 (en) * 2014-02-23 2018-01-04 Apple Inc. Impedance matching for inductive power transfer systems
JP2017506059A (ja) * 2014-02-23 2017-02-23 アップル インコーポレイテッド 結合コイルシステム内の調整フィルタ
WO2015127303A1 (fr) * 2014-02-23 2015-08-27 Apple Inc. Adaptation d'impédance pour systèmes de transfert de puissance inductive
US10693322B2 (en) 2014-05-20 2020-06-23 Fujitsu Limited Wireless power transfer control method and wireless power transfer system
EP3151377A4 (fr) * 2014-05-20 2017-05-31 Fujitsu Limited Procédé de commande de transmission de puissance sans fil et système de transmission de puissance sans fil
CN106464021B (zh) * 2014-05-20 2019-01-22 富士通株式会社 无线电力传输控制方法以及无线电力传输系统
KR101891426B1 (ko) * 2014-05-20 2018-08-24 후지쯔 가부시끼가이샤 무선 전력 전송 제어 방법 및 무선 전력 전송 시스템
US20170063168A1 (en) * 2014-05-20 2017-03-02 Fujitsu Limited Wireless power transfer control method and wireless power transfer system
CN106464021A (zh) * 2014-05-20 2017-02-22 富士通株式会社 无线电力传输控制方法以及无线电力传输系统
US10305333B2 (en) 2014-05-22 2019-05-28 Fujitsu Limited Power receiver, wireless power transfer system, and kQ-value calculation method
EP3151375A4 (fr) * 2014-05-22 2018-01-10 Fujitsu Limited RÉCEPTEUR DE PUISSANCE, SYSTÈME DE TRANSMISSION DE PUISSANCE SANS FIL, ET PROCÉDÉ DE CALCUL DE VALEUR kQ
CN106464022A (zh) * 2014-05-22 2017-02-22 富士通株式会社 受电器、无线电力传输系统以及kQ值计算方法
US10032557B1 (en) 2014-05-29 2018-07-24 Apple Inc. Tuning of primary and secondary resonant frequency for improved efficiency of inductive power transfer
US10594159B2 (en) 2014-06-03 2020-03-17 Apple Inc. Methods for detecting mated coils
US9537353B1 (en) 2014-06-03 2017-01-03 Apple Inc. Methods for detecting mated coils
US9685814B1 (en) 2014-06-13 2017-06-20 Apple Inc. Detection of coil coupling in an inductive charging system
US10110051B2 (en) 2014-06-13 2018-10-23 Apple Inc. Detection of coil coupling in an inductive charging system
US10879721B2 (en) 2014-06-13 2020-12-29 Apple Inc. Detection of coil coupling in an inductive charging system
GB2527312B (en) * 2014-06-17 2021-03-03 Advanced Risc Mach Ltd Harvesting power from ambient energy in an electronic device
GB2527312A (en) * 2014-06-17 2015-12-23 Advanced Risc Mach Ltd Harvesting power from ambient energy in an electronic device
US10651683B2 (en) 2014-06-17 2020-05-12 Arm Limited Harvesting power from ambient energy in an electronic device
US9813041B1 (en) 2014-07-31 2017-11-07 Apple Inc. Automatic boost control for resonant coupled coils
US10879745B2 (en) 2014-08-28 2020-12-29 Apple Inc. Temperature management in a wireless energy transfer system
US10014733B2 (en) 2014-08-28 2018-07-03 Apple Inc. Temperature management in a wireless energy transfer system
US10193372B2 (en) 2014-09-02 2019-01-29 Apple Inc. Operating an inductive energy transfer system
WO2016050633A3 (fr) * 2014-09-30 2016-06-02 Drayson Technologies (Europe) Limited Système de transfert de puissance inductive
US10666084B2 (en) 2015-07-10 2020-05-26 Apple Inc. Detection and notification of an unpowered releasable charging device
US10211676B2 (en) 2015-08-25 2019-02-19 Otis Elevator Company Electromechanical propulsion system having a wireless power transfer system
NO20161441A1 (en) * 2016-09-12 2017-10-23 Kongsberg Seatex As Method for control of a parallel resonant current-driven inductive coupler and parallel resonant current-driven inductive coupler
NO341373B1 (en) * 2016-09-12 2017-10-23 Kongsberg Seatex As Method for control of a parallel resonant current-driven inductive coupler and parallel resonant current-driven inductive coupler
US10644531B1 (en) 2016-09-22 2020-05-05 Apple Inc. Adaptable power rectifier for wireless charger system
US10411516B2 (en) 2016-10-28 2019-09-10 General Electric Company System and method for actively controlling output voltage of a wireless power transfer system
US11075545B2 (en) 2016-10-28 2021-07-27 General Electric Company System and method for actively controlling output voltage of a wireless power transfer system
US10523063B2 (en) 2017-04-07 2019-12-31 Apple Inc. Common mode noise compensation in wireless power systems
US10389274B2 (en) 2017-04-07 2019-08-20 Apple Inc. Boosted output inverter for electronic devices
EP3528365A1 (fr) * 2018-02-19 2019-08-21 Naptilus Technology Lab, S.L. Appareil de syntoniseur et de redresseur pour récepteur de transfert de puissance sans fil

Also Published As

Publication number Publication date
WO2012085119A3 (fr) 2012-10-11
FI20100427A7 (fi) 2012-06-23
FI20100427L (fi) 2012-06-23
FI20100427A0 (fi) 2010-12-21

Similar Documents

Publication Publication Date Title
WO2012085119A2 (fr) Récepteur de puissance sans fil pour recevoir un signal de puissance sur un couplage inductif, et amélioration du procédé de mise en œuvre d'un récepteur de puissance sans fil
EP3707801B1 (fr) Transfert de puissance sans fil capacitif au moyen de réseaux d'adaptation adaptatifs
USRE49955E1 (en) Wireless power transmitting apparatus and method thereof
Colak et al. A novel phase-shift control of semibridgeless active rectifier for wireless power transfer
US10298138B2 (en) Programmable power adapter
US10498160B2 (en) Efficiency maximization for device-to-device wireless charging
CN106852182B (zh) 具有固定调谐和功率限制的可变距离无线功率传输系统
US9502921B2 (en) Circuit for a system for contactless inductive power transmission
CN107852197A (zh) 用于使用同步整流器控制来调节输出功率的设备、系统和方法
US20230129480A1 (en) Electronic device and control method therefor
EP3195443B1 (fr) Transfert de puissance inductive sans fil
US10063085B2 (en) Power supplying apparatus and wireless power transmitter
US20170256958A1 (en) High frequency multi-level rectification
CN116231884B (zh) 一种电力接收装置、电力发送装置及电力传输方法
CN115833411B (zh) 用于无线功率接收的装置、控制电路以及传输的通信方法
Pang et al. Impedance buffer-based reactance cancellation method for CLC-S compensated wireless power transfer
TWI863918B (zh) 用於傳輸電力至具轉換器之電力負載之裝置
CN114144968B (zh) 用于将电力传输到电负载的转换器
Jiang et al. Bidirectional high-frequency inductive power transfer systems based on differential load-independent class e converters
KR20230038744A (ko) 변환기의 성능 향상
CN116707328B (zh) 整流器动态升压
Jiang et al. High-Frequency DC/DC Converter Based on Differential Load-Independent Class E Inverter
Celentano et al. A Primary-side Maximum Efficiency Transfer Solution in Wireless Power Transfer Systems: Theory and Validation
Mao et al. Flexible and Efficient 6.78 MHz High Power Wireless Charging Modules Using Controlled Magnetic Resonance Power Architecture
NZ579100A (en) A contactless power receiver and method of operation

Legal Events

Date Code Title Description
NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 11802420

Country of ref document: EP

Kind code of ref document: A2