Patent US10355526

Bi-directional inductive power transfer
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US10355526

1. A control method for an inductive power transfer (IPT) system having a primary side comprising a primary converter and a primary resonant circuit, and a secondary side comprising a secondary converter and a secondary resonant circuit, the method comprising the steps of: (9) (2)

controlling a relative phase angle of the secondary converter with respect to the primary converter while maintaining the secondary resonant circuit tuning to be the same as the primary resonant circuit tuning to control a transfer of power between the primary side and the secondary side; and

controlling a magnitude of power transfer by varying a secondary converter output voltage to maintain a required pickup output, wherein varying the secondary converter output voltage magnitude comprises varying a pulse width of the secondary converter output voltage.

2. The control method of claim 1 wherein the primary and secondary resonant circuits each further comprise a tuned inductor-capacitor-inductor (LCL) circuit. (0)

3. The control method of claim 1 wherein the relative phase angle may be varied between 0° and ±90° and is proportional to the magnitude of power transfer required to obtain the required pickup output. (0)

4. The control method of claim 1 wherein the method further comprises the step of controlling the relative phase angle to maintain a constant ±90° angle between the secondary and primary converters. (0)

5. The control method of claim 1, wherein the method further comprises the step of controlling a voltage of the primary converter to maintain a constant current through a primary conductive path unless all loads are removed from the system. (0)

6. The control method of claim 1, wherein the method further comprises the step of controlling a voltage of the primary converter to maintain a the minimum current through a primary conductive path sufficient for a pickup controller to maintain the required pickup output. (0)

7. The control method of claim 1, wherein the method further comprises the step of controlling a direction of power flow by causing the secondary converter to either lag or lead the primary converter by a required phase angle, thereby enabling bi-directional power transfer between the secondary side and the primary side of the IPT system. (0)

23. The control method of claim 1 wherein the relative phase angle comprises a phase angle between the secondary converter output voltage and a primary converter voltage. (0)

24. The control method of claim 1 wherein the secondary converter is at least one of a rectifier and an inverter. (0)

25. The control method of claim 1 wherein the secondary converter is configured to convert the secondary side converter output voltage to an output voltage. (0)

8. A pickup for an inductive power transfer (IPT) system, the pickup comprising: (5) (4)

a phase detector for detecting an indication of a phase of a voltage in a primary conductive path with which the pickup is inductively coupled in use;

a resonant circuit to receive power inductively from the primary conductive path;

a converter allowing adjustable phase; and

a controller adapted to control a power transfer between the primary conductive path and a load associated with the pickup, by controlling at least a phase angle of the converter with respect to that of the primary conductive path voltage while maintaining the resonant circuit tuning the same as a primary resonant circuit tuning and controlling a magnitude of power transfer by varying the converter output voltage to maintain a required pickup output, wherein varying the converter output voltage magnitude comprises varying a pulse width of the converter output voltage.

9. The pickup of claim 8 wherein the resonant circuit of the pickup comprises a tuned inductor-capacitor-inductor (LCL) circuit. (0)

10. The pickup of claim 8 wherein the phase detector is adapted to detect the phase of the primary conductive path voltage by detecting a phase of a voltage induced in the pickup. (0)

11. The pickup of claim 8 wherein the controller is adapted to vary the phase angle between 0° and ±90°, proportional to the magnitude of power transfer required to obtain the required pickup output. (0)

12. The pickup of claim 8 wherein the controller is adapted to maintain a constant ±90° phase angle between a converter output and the primary conductive path voltage. (0)

13. The pickup of claim 8 wherein the controller is further adapted to control a direction of power flow by causing the converter to either lag or lead the primary conductive path voltage by a required phase angle, thereby enabling bi-directional power transfer between the pickup and the primary conductive path. (0)

14. An inductive power transfer (IPT) system comprising: (8) (2)

a power supply adapted to control the alternating current in a primary conductive path; and

at least one pickup inductively coupled with the primary conductive path in use and comprising a converter and a resonant circuit electrically coupled to a load, the pickup being adapted to control the relative phase angle of the converter output with respect to that of a the voltage in the primary conductive path while maintaining the resonant circuit tuning at the same as a primary resonant circuit tuning to control a transfer of power between the primary conductive path and the load and control a magnitude of power transfer by varying a converter output voltage to maintain a required pickup output, wherein varying the converter output voltage magnitude comprises varying a pulse width of the converter output voltage.

15. The IPT system of claim 14 wherein the resonant circuit comprises a tuned inductor-capacitor-inductor (LCL) circuit. (0)

16. The IPT system of claim 14 wherein the IPT system comprises a single pickup and the power supply is adapted to supply a minimum alternating track current which is sufficient to supply the load. (0)

17. The IPT system of claim 14 wherein the IPT system comprises a plurality of pickups inductively coupled with the primary conductive path, and the power supply is adapted to supply a constant alternating current to the primary conductive path. (0)

18. The IPT system of claim 14 wherein the power supplied by the or each pickup to its respective load is controlled by the pickup and is determined by the relative phase angle between the converter output voltage and an output voltage of a primary converter of the power supply, wherein the magnitude of power transferred to the load is proportional to the relative phase angle in a range of 0° to ±90°. (0)

19. The IPT system of claim 14 wherein a voltage supplied by the or each pickup to the respective load is controlled by the pickup and determined by the pulse width of the converter, wherein the relative phase angle between the pickup and a primary converter is controlled to be equal to ±90°. (0)

20. The IPT system of claim 14 wherein the or each converter comprises a reversible inverter/rectifier, and a direction of power transfer is controlled by causing the converter output voltage to either lag or lead a primary converter output voltage by a required phase angle, thereby enabling bi-directional power transfer between the load and the primary conductive path. (0)

21. The IPT system of claim 14 wherein the or each pickup in the system is adapted to independently control a the direction of power flow to/from the respective load, thereby allowing bi-directional power flow between the load and one or more other pickups via the primary conductive path. (0)

22. The IPT system of claim 14 wherein the power supply further comprises a reversible inverter/rectifier, and power transferred from one or more pickups to the primary conductive path may be returned to a primary power source electrically coupled to the power supply, thereby allowing bi-directional power flow between one or more loads and the power source. (0)

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Patent US10355526

Bi-directional inductive power transfer

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