WIRELESS POWER SYSTEM FOR PORTABLE DEVICES UNDER ROTATIONAL MISALIGNMENT

• US 20150372493A1
• Filed: 06/16/2015
• Published: 12/24/2015
• Est. Priority Date: 06/18/2014
• Status: Active Grant

• Current Assignee: WiPQTUS Inc.
• Original Assignee: WiPQTUS Inc.
• Inventors: Sankar, Ganapathy
• Granted Patent: US 10,122,220 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H02J 50/10 using inductive coupling
• CPC Class Codes: H02J 50/60 responsive to the presence of foreign objects, e.g. detection of living beings
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 50/90 involving detection or optimisation of position, e.g. alignment
• CPC Class Codes: H02J 7/00308 Overvoltage protection

Abstract

A wireless power transmitter (WPT) including a first, second, third circuit and a transmit coil for wirelessly delivering power to a wireless power receiver (WPR) including a receiver coil, rectifier, impedance network, protection circuitry, control logic, modulator/demodulator and ADC is provided. A method that enables WPT and WPR to deliver the required power to the WPR'"'"'s downstream load in planar, orthogonal and intermediate modes of WPR placement on WPT is provided. The WPR is integrated into the strap/frame or in the vital area of the device. To avoid a heated metal object safety issue, the WPT implements a metal object detect algorithm to detect metal objects and terminate transmission of power. To protect their circuitry from induced voltage spikes in excess of acceptable levels, the WPR includes a simple protection circuitry that naturally turns on and siphons out the excess power when the acceptable threshold levels are exceeded.

Claims

1. A wireless power system comprising a wireless power transmitter and a wireless power receiver capable of being operatively associated with said wireless power transmitter,

(A) said wireless power transmitter comprising:

(a) a first circuit comprising a switch network and receiving an input voltage from an external power source,

(b) a second circuit comprising a variable matching circuit, operatively associated with said first circuit to appropriately bias and allow said wireless power system to regulate transmitted power, said second

(c) d circuit being connected between said first circuit and a transmitter coil,

(d) said transmitter coil configured to wirelessly transmit power to said wireless power receiver, and

(e) a third circuit comprising a control logic block, an analog to digital converter (ADC) and a modulator/demodulator block and configured to provide a pulse width modulated signal to said first circuit, wherein said third circuit is configured to perform one or more of;

sensing the level of magnetic flux coupling between said transmitter coil of said wireless power transmitter and a receiver coil of said wireless power receiver;

driving of said first circuit to change a topology of said switch network;

driving of said second circuit to change said variable matching circuit'"'"'s impedance characteristics;

and constraining the frequency and duty cycle of said pulse width modulated signal to a range of values and varying said frequency and said duty cycle of said pulse width modulated signal within those respective ranges;

(B) said wireless power receiver for receiving and conditioning the wireless power from said wireless power transmitter, said wireless power receiver comprising;

(a) a receiver coil to receive wireless power,

(b) an impedance network to control amount of wireless power received,

(c) a rectifier to condition alternating current (AC) power into direct current (DC) power,

(d) a protection circuit to monitor certain internal dynamic circuit characteristics of the wireless power receiver and configured to take rapid appropriate action if the circuit characteristics are not within acceptable bounds,

(e) an analog to digital converter (ADC) block,

(f) a modulator/demodulator block to maintain operative communication between said wireless power receiver and said wireless power transmitter,

(f) a control logic to monitor internal dynamic circuit characteristics of said wireless power receiver and configured to communicate messages via said modulator/demodulator block to said wireless power transmitter;

said wireless power transmitter configured to sense said level of magnetic flux coupling under planar, orthogonal and intermediate modes of rotational misalignment and physical displacement in the X-plane, Y-plane and Z-plane,

said wireless power transmitter compensating for said level of magnetic flux coupling by performing one or more of;

driving of said first circuit to change a topology of said switch network;

driving of said second circuit to change said variable matching circuit'"'"'s impedance characteristics;

and constraining said frequency and said duty cycle of said pulse width modulated signal to a range of values and varying said frequency and said duty cycle of said pulse width modulated signal within those respective ranges;

whereby said change in one or more of

said topology of said switch network,

said impedance of variable matching circuit,

said frequency range of said pulse width modulated signal,

said duty cycle range of said pulse width modulated signal,

ensures that said wireless power system can satisfy said wireless power receiver'"'"'s downstream load compensating for said rotational misalignment and said physical displacement in the X-plane, Y-plane and Z-plane between said transmitter coil of said wireless power transmitter and said receiver coil of said wireless power receiver.

2. The wireless power system of claim 1 wherein in said wireless power transmitter, said switch network of said first circuit is configured as one of DC-AC inverter and AC-AC converter.

3. The wireless power system of claim 1 wherein in said wireless power transmitter, said first circuit is further comprising of a power conversion means operatively connected between said external power source and said switch network, said power conversion means configured as one of DC-DC converter to step-up or step-down or pass-through said input voltage based on signals received by said first circuit from said third circuit and AC-DC power supply to transform the AC mains power to a regulated DC voltage based on signals received by said first circuit from said third circuit.

4. The wireless power system of claim 1 wherein in said wireless power transmitter, said second circuit is further comprising of a tuning circuit operatively connected between said variable matching circuit and said transmitter coil and said tuning circuit is configured to adjust its circuitry to improve wireless power delivery based on signals received by said second circuit from said third circuit.

5. The wireless power system of claim 1 wherein said wireless power transmitter is further comprising of a plurality of transmitter coils and switches wherein one or more said transmitter coils may be activated to wirelessly transmit power to said wireless power receiver by activating the associated said switch based on signals received from said third circuit.

6. The wireless power system of claim 1 wherein said wireless power receiver is integral in a sensor containing portable device but positioned distant from the sensor containing area of said portable device.

7. The wireless power system of claim 1 wherein said wireless power receiver is integrated into a sensor containing portable device such that only said receiver coil thereof is distant from a sensor containing area of said portable device.

8. The wireless power system of claim 1 wherein said wireless power receiver is integrated into a Wearable device such that the receiver coil is integrated into one of strap and frame of said Wearable device.

9. The wireless power system of claim 1 wherein said wireless power receiver'"'"'s receiver coil is inbuilt natively into one of the components of portable device.

10. The wireless power system of claim 1 wherein in said wireless power receiver, said rectifier has a voltage multiplier topology.

11. The wireless power system of claim 1 wherein in said wireless power receiver, said rectifier topology is dynamically selected from the group consisting of an asynchronous topology, half-synchronous topology, fully synchronous topology and voltage multiplier topology.

12. The wireless power system of claim 1 wherein in said wireless power receiver, said rectifier is further comprising of one of a switched-capacitor/charge-pump circuit and a boost circuit post initial AC-DC rectification.

13. The wireless power system of claim 1 wherein in said wireless power receiver, said control logic is further configured to sense level of magnetic flux coupling between said transmitter coil of said wireless power transmitter and said receiver coil of said wireless power receiver, said control logic communicates messages via the modulator/demodulator block to the wireless power transmitter based of said level of magnetic flux coupling and power drawn by said downstream load, said control logic optionally updating said impedance network and said rectifier to compensate for the level of magnetic flux coupling.

14. The wireless power system of claim 1 wherein in said wireless power receiver, said control logic updates said impedance network and said rectifier to regulate said wireless power receiver'"'"'s received power to match the power drawn by said downstream load.

20. The wireless power system of claim 1 wherein in said wireless power receiver, said protection circuitry is comprising of a PMOS switch and a resistor, source terminal of said PMOS switch connected to the signal that is being protected, gate terminal of said PMOS switch driven with a voltage that is a gate threshold voltage below the maximum voltage permitted for said signal, the drain terminal of said PMOS switch connected to one end of said resistor and the other end of said resistor connected to ground potential of said wireless power receiver, wherein any voltage spikes in excess of said maximum threshold of said signal causes said PMOS switch to turn on and redirect excess power to said ground potential of said wireless power receiver via said resistor.

15. A method for establishing a sufficient and safe wireless power transfer from said wireless power transmitter to said wireless power receiver when said wireless power receiver contained in a portable device is placed on said wireless power transmitter in one of planar, orthogonal and intermediate modes, said method comprising:

said wireless power transmitter starting up on receiving power,

said wireless power transmitter probing its surface periodically for presence of said wireless power receiver,

said wireless power transmitter detecting the presence of said wireless power receiver when portable device containing said wireless power receiver is placed on said surface of said wireless power transmitter,

said wireless power transmitter providing power to detected said wireless power receiver,

said wireless power receiver starting up on receiving power,

said wireless power receiver sending messages to said wireless power transmitter,

said wireless power transmitter learning about said wireless power receiver such as its type, capabilities and internal circuit characteristics such as initial voltage from said messages received from said wireless power receiver,

said wireless power transmitter combining this information from said wireless power receiver with operational and circuit characteristics in said wireless power transmitter'"'"'s internal circuitry such as current, voltage, frequency, phase difference, etc., said wireless power transmitter detecting the level of magnetic flux coupling between said transmitter coil and said receiver coil,

said wireless power transmitter configuring its circuitry and operating limits based on information received from said wireless power receiver as well as the detected said level of magnetic flux coupling between said transmitter coil and said receiver coil,

said wireless power transmitter continuing to listen to said messages from said wireless power receiver and adjusting its operating point for appropriate power transfer to said wireless power receiver,

said wireless power transmitter terminating said power transfer and returning to probing its said surface periodically when said portable device containing said wireless power receiver is removed from said surface of said wireless power transmitter,

said wireless power transmitter executing metal object detect algorithm and on detection of foreign metal object, asserting a metal object alarm and aborting said power transfer if suitable user intervention is not observed in a certain interval of time, said wireless power transmitter periodically checking for removal of said foreign metal object from the said surface of said wireless power transmitter, said wireless power transmitter then returning to probing its said surface periodically on detection of removal of said foreign metal object from said surface of said wireless power transmitter,

said wireless power transmitter terminating said power transfer when receiving messages from said wireless power receiver to stop the power transfer, said wireless power transmitter periodically checking for removal of said portable device containing said wireless power receiver from the said surface of said wireless power transmitter, said wireless power transmitter then returning to probing its said surface periodically on detection of removal of said portable device from said surface of said wireless power transmitter.

16. The method of claim 15 wherein said wireless power receiver detecting the level of magnetic flux coupling between said transmitter coil and said receiver coil based of internal operational and circuit characteristics such as current, voltage, frequency, phase difference and said wireless power receiver configuring its circuitry to compensate for the level of coupling.

17. The method of claim 15 wherein said wireless power transmitter not detecting said level of magnetic flux coupling between said transmitter coil and said receiver coil(s), said wireless power transmitter configuring its circuitry and operating limits based on type, number and rated power requirements of said wireless power receiver(s) and not on said level of magnetic flux coupling between said transmitter coil and said receiver coil(s), said wireless power receiver(s) dynamically adjusting their said impedance networks and the topology of their said rectifier to regulate their received power to match the power requirements of the downstream load.

18. A method for avoiding heated metal safety issue caused by induced eddy currents when metal objects are placed in the magnetic flux coupling zone of said wireless power transmitter, wherein said wireless power transmitter implementing a metal object detect algorithm that said wireless power transmitter activates when said wireless power transmitter and said wireless power receiver are operating in stable power transfer,

said metal object detect algorithm periodically measuring the tank impedance as seen by said switch network of said wireless power transmitter,

said metal object detect algorithm periodically measuring other internal circuit characteristics of said wireless power transmitter,

said metal object detect algorithm measuring a change in said tank impedance,

said metal object detect algorithm ascertaining said change in said tank impedance is not due to change in position of said wireless power receiver by checking operating and circuit characteristics in said wireless power transmitter'"'"'s internal circuitry,

said metal object detect algorithm ascertaining said change in said tank impedance is not due to change in power drawn by said downstream load of said wireless power receiver by checking the total dynamic power absorbed messages received from said wireless power receiver,

said metal object detect algorithm measuring an increase in the power drawn by said wireless power system,

said metal object detect algorithm ascertaining said change in said tank impedance as abnormal and entering a foreign metal object detected state

said wireless power transmitter asserting a metal object alarm and aborting said stable power transfer if suitable user intervention is not observed in a certain interval of time.

19. The method of claim 18 wherein in said wireless power transmitter, said metal object detection algorithm measuring and using a change in one of current in said transmitter coil and voltage across said transmitter coil in place of said change in said tank impedance.