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EP-4736293-A1 - COMMUNICATION SLOTS IN A WIRELESS POWER SYSTEM

EP4736293A1EP 4736293 A1EP4736293 A1EP 4736293A1EP-4736293-A1

Abstract

This disclosure provides systems, methods and apparatuses for a managing timing of communication slots in a wireless power system. The communication slots are centered on zero-cross instances. The Power Transmitter and/or Power Receiver can use a phase locked loop (PLL) to determine the timing of the zero-cross instances. The wireless power system can determine when to begin a communication slot based on the timing of the zero-cross instance and the slot width. For example, the beginning of the communication slot can begin at a time that is half the slot width before the time of the zero-cross instance.

Inventors

  • GANESH, Jayanti
  • KANAKASABAI, VISWANATHAN
  • TATIKONDA, Subbarao
  • NARAYANA BHAT, Suma, Memana

Assignees

  • Dolby Intellectual Property Licensing, LLC

Dates

Publication Date
20260506
Application Date
20240627

Claims (14)

  1. 1. A method of a Power Transmitter, comprising: generating a wireless power signal for transmission to a Power Receiver based on an alternating current (AC) main power signal; determining a timing of a future zero-cross instance of the AC main power signal; calculating a start time for at least a first communication slot based on the timing of the future zero-cross instance and a duration (Tsiot) of the first communication slot such that approximately half of the Tsiot occurs before the future zero-cross instance; and configuring a communication unit to begin the first communication slot at the start time.
  2. 2. The method of claim 1, wherein determining the timing of the future zero-cross instance includes: calculating the timing of the future zero-cross instance based on an amount of time between a half cycle of the AC main power signal and a previous zero-cross instance.
  3. 3. The method of claim 1 or 2, further comprising: locking onto a frequency of the AC main power signal using a phase locked loop (PLL), wherein a phase output of the PLL indicates a phase value that changes in relation to a phase of the AC main power signal; and determining the timing of the future zero-cross instance based on an output of the PLL.
  4. 4. The method of claim 3. wherein determining the timing of the future zero-cross instance includes: measuring duration of at least a prior half cycle of the AC main power signal based on a period in which the phase output of the PLL changes from zero (0) to 7i radians or from 7i to 2TI radians; detecting an occurrence of a previous zero-cross instance when the output of the PLL is 0, 7t, or 2n radians; and calculating the timing of the future zero-cross instance based on the duration of at least the prior half cycle and the occurrence of the previous zero-cross instance.
  5. 5. The method of any one of claims 1 to 4, further comprising: determining the Tsiot based on an amount and periodicity of information to communicate to the Power Receiver.
  6. 6. The method of any one of claims 1 to 5, wherein the duration of the first communication slot is not dependent on a voltage and frequency of the AC main power signal.
  7. 7. The method of any one of claims 1 to 6, further comprising: communicating with the Power Receiver during one or more communication slots, wherein the one or more communication slots are centered on one or more corresponding zero-cross instances based on a slot width of the one or more communication slots.
  8. 8. A Power Transmitter comprising: a driver circuit configured to generate a wireless power signal for transmission to a Power Receiver based on an alternating current (AC) main power signal; a communication unit configured to communicate with the Power Receiver during one or more communication slots; and a controller configured to: determine a timing of a future zero-cross instance of the AC main power signal; calculate a start time for at least a first communication slot based on the timing of the future zero-cross instance and a duration (Tsiot) of the first communication slot such that approximately half of the Tsiot occurs before the future zero-cross instance; and configure the communication unit to begin the first communication slot at the start time.
  9. 9. The Power Transmitter of claim 8, wherein the controller is configured to: calculate the timing of the future zero-cross instance based on an amount of time between a half cycle of the AC main power signal and a previous zero-cross instance.
  10. 10. The Power Transmitter of claim 8 or 9, further comprising: a phase locked loop (PLL) configured to lock onto a frequency of the AC main power signal, wherein a phase output of the PLL indicates a phase value that changes in relation to a phase of the AC main power signal, and wherein the controller is configured to determine the timing of the future zero-cross instance based on the phase output of the PLL.
  11. 11. The Power Transmitter of any one of claims 8 to 10, wherein the controller is configured to: measure duration of at least a prior half cycle of the AC main power signal based on a period in which the output of the PLL changes from zero (0) to 71 radians or from TT to 2TI radians; detect an occurrence of a previous zero-cross instance when the output of the PLL is 0, 7i, or 2TI radians; and calculate the timing of the future zero-cross instance based on the duration of at least the prior half cycle and the occurrence of the previous zero-cross instance.
  12. 12. The Power Transmitter of any one of claims 8 to 11, wherein the controller is configured to determine the Tsiot based on an amount and periodicity of information to communicate to the Power Receiver.
  13. 13. The Power Transmitter of any one of claims 8 to 12, wherein the Tsiot is not dependent on the voltage and frequency of the AC main power signal.
  14. 14. The Power Transmitter of any one of claims 8 to 13, wherein the controller is configured to: cause the communication unit to communicate with the Power Receiver during one or more communication slots, wherein the one or more communication slots are centered on one or more corresponding zero-cross instances based on a slot width of the one or more communication slots.

Description

COMMUNICATION SLOTS IN A WIRELESS POWER SYSTEM TECHNICAL FIELD [0001] This disclosure relates generally to wireless power and some aspects relate to communication slots in a wireless power system. DESCRIPTION OF RELATED TECHNOLOGY [0002] A wireless power system includes a Power Transmitter (PTx) and a Power Receiver (PRx). Inductive coupling can enable wireless power transfer between a primary coil of the Power Transmitter and a secondary coil of the Power Receiver. The primary coil of the Power Transmitter produces an electromagnetic field during a pow er state of the wireless power system. The electromagnetic field induces a voltage in the secondary coil of the Power Receiver when the secondary coil is present in the electromagnetic field. The Power Receiver can use the induced voltage (either directly or via a rectifier) to powder a load. Example loads might include a motor, a heating element, electronics, or a power storage device, among other examples. In an example kitchen environment, a magnetic power source (such as a kitchen hob) might include one or more Power Transmitters. An appliance (such as a cordless kitchen appliance) might include a Power Receiver as well as the load. The appliance can be placed on a Power Transmitter such that the Power Receiver of the appliance can receive wireless power from the magnetic power source. [0003] For a wireless power system to work effectively, the Power Transmitter and the Powder Receiver communicate before and during a power transfer state (referred to as the power state). Example communications might include configuration, power negotiation, state control and power control messages, among other examples. During the power state, communication is limited to minimize interference with a wireless power signal. A communication slot refers to a period of time during the power state for communication to occur. To minimize disruption to the wireless power signal, the communication slots occur in relation to a zero-cross instance where the wireless power signal has less voltage. It is desirable to coordinate the timing of the communication slots with the timing of zerocross instances. BRIEF SUMMARY [0004] The systems, methods, and apparatuses of this disclosure each have several innovative aspects, no single one of which is solely responsible for the desirable attributes disclosed herein. [0005] In one aspect, a method of a Power Transmitter, includes generating a wireless power signal for transmission to a Power Receiver based on an alternating current (AC) main power signal, determining a timing of a future zero-cross instance of the AC main power signal, calculating a start time for at least a first communication slot based on the timing of the future zero-cross instance and a duration (Tsiot) of the first communication slot such that approximately half of the Tsiot occurs before the future zero-cross instance, and configuring a communication unit to begin the first communication slot at the start time. [0006] In one aspect, a Power Transmitter includes a driver circuit configured to generate a wireless power signal for transmission to a Power Receiver based on an alternating current (AC) main power signal. The Power Transmitter also includes a communication unit configured to communicate with the Power Receiver during one or more communication slots. The Power Transmitter also includes a controller configured to determine a timing of a future zero-cross instance of the AC main power signal, calculate a start time for at least a first communication slot based on the timing of the future zerocross instance and a duration (Tsiot) of the first communication slot such that approximately half of the Tsiot occurs before the future zero-cross instance, and configure a communication unit to begin the first communication slot at the start time. [0007] Details of one or more implementations of the subject matter described in this disclosure are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages will become apparent from the description, the drawings, and the claims. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS [0008] Like reference numbers and designations in the various drawings indicate like elements. Note that the relative dimensions of the figures may not be drawn to scale. [0009] FIG. 1 illustrates an example wireless power system. [0010] FIG. 2 illustrates communication slots during a power state of the wireless power system. [0011] FIG. 3A illustrates several examples of inconsistent timing of communication slots relative to zero-cross instances. [0012] FIG. 3B illustrates additional examples of communication slots relative to zerocross instances. [0013] FIG. 4 illustrates an alternating current (AC) main power signal and the corresponding zero-cross instances. [0014] FIG. 5 illustrates an example timing of communication slots centered on the zerocross instances in accordance with aspects of thi