RADIO FREQUENCY HEATING APPARATUS USING DIRECT-DIGITAL RADIO FREQUENCY POWER CONTROL AND FINE-TUNE POWER CONTROL

• US 20160113068A1
• Filed: 10/02/2015
• Published: 04/21/2016
• Est. Priority Date: 10/21/2014
• Status: Active Grant

• Current Assignee: Ultraflex International, Inc.
• Original Assignee: Ultraflex International, Inc.
• Inventors: Metodiev, Mario, Schmitt, Philip Charles, Bonev Bonev, Stanimir
• Granted Patent: US 10,624,158 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H05B 6/06 Control, e.g. of temperature, of power

Abstract

A radio frequency inductive heating apparatus includes a control device, a plurality of radio frequency devices, a plurality of transformers, a resonant tank circuit, a heating element, a first power supply, and a second power supply. The radio frequency devices are selectively activated by the control device, and each of the plurality of radio frequency devices is coupled to the primary winding of one of the plurality of transformers. The secondary winding of each of the plurality of transformers is coupled to the resonant tank circuit, and the heating element is coupled to the resonant tank circuit. The plurality of radio frequency devices includes a first radio frequency device and a second radio frequency device. The first radio frequency device is coupled to the first power supply, and the second radio frequency device is operatively coupled to the second power supply. A corresponding method is also disclosed.

Claims

1. A radio frequency inductive heating apparatus, which comprises:

a control device;

a plurality of radio frequency devices, the plurality of radio frequency devices being selectively activated by the control device;

a plurality of transformers, each of the plurality of radio frequency devices being operatively coupled to one of the plurality of transformers;

a resonant tank circuit, the plurality of transformers being operatively coupled to the resonant tank circuit;

a heating element, the heating element being operatively coupled to the resonant tank circuit;

a first power supply; and

a second power supply, the plurality of radio frequency devices comprising a first radio frequency device and a second radio frequency device, the first radio frequency device being operatively coupled to the first power supply, the second radio frequency device being operatively coupled to the second power supply.

2. The radio frequency inductive heating apparatus, as defined by claim 1, wherein the plurality of radio frequency devices receives a radio frequency signal from the control device, the radio frequency signal providing an operating frequency associated with the plurality of radio frequency devices, the operating frequency being based on a resonant frequency associated with the resonant tank circuit.

3. The radio frequency inductive heating apparatus, as defined by claim 1, wherein the second power supply is a variable power supply, an output voltage associated with the first power supply being greater than an output voltage associated with the second power supply.

4. The radio frequency inductive heating apparatus, as defined by claim 1, wherein at least one of the plurality of radio frequency devices is selectively activated by the control device based on a power set signal and a feedback signal, the power set signal representing a desired voltage associated with the resonant tank circuit, the feedback signal representing an electrical parameter associated with the resonant tank circuit.

5. The radio frequency inductive heating apparatus, as defined by claim 1, wherein at least one of the plurality of radio frequency devices comprises a full bridge inverter, the full bridge inverter receiving a first phase signal and a second phase signal, a phase difference between the first phase signal and the second phase signal being selectively adjusted to modify an output voltage associated with the at least one of the plurality of radio frequency devices.

6. The radio frequency inductive heating apparatus, as defined by claim 1, wherein the plurality of transformers comprises a first transformer and a second transformer, the first transformer comprising a first turns ratio, the second transformer comprising a second turns ratio, the first turns ratio being unequal to the second turns ratio.

7. The radio frequency inductive heating apparatus, as defined by claim 1, wherein the plurality of radio frequency devices further comprises a first radio frequency device and a plurality of second radio frequency devices, the plurality of transformers comprising a first transformer and a plurality of second transformers, the first radio frequency device being operatively coupled to the first transformer, each of the plurality of second radio frequency devices being operatively coupled to one of the plurality of second transformers.

8. The radio frequency inductive heating apparatus, as defined by claim 7, wherein each of the plurality of second transformers comprises a turns ratio equal to one of n:

1 and (n−

1);

1, n representing a quantity of second radio frequency devices.

9. The radio frequency inductive heating apparatus, as defined by claim 7, wherein each of the plurality of second transformers comprises a turns ratio equal to 2ⁿ:

1, n representing an increasing positive integer.

10. The radio frequency inductive heating apparatus, as defined by claim 7, further comprising a first power supply and a second power supply, the plurality of second radio frequency devices comprising a first radio frequency device and a second radio frequency device, the first radio frequency device being operatively coupled to the first power supply, the second radio frequency device being operatively coupled to the second power supply.

11. The radio frequency inductive heating apparatus, as defined by claim 10, wherein the second power supply is a variable power supply, an output voltage associated with the first power supply being greater than an output voltage associated with the second power supply.

12. The radio frequency inductive heating apparatus, as defined by claim 10, wherein an output voltage associated with the first power supply is twice an output voltage associated with the second power supply.

13. The radio frequency inductive heating apparatus, as defined by claim 10, wherein at least one of the first power supply and the second power supply comprises a rectifier.

14. A method of providing radio frequency inductive heating, the method comprising:

activating a plurality of radio frequency devices selectively by a control device;

coupling each of the plurality of radio frequency devices operatively to one of a plurality of transformers;

coupling each of the plurality of transformers operatively to a resonant tank circuit;

coupling a heating element operatively to the resonant tank circuit;

coupling a first radio frequency device operatively to a first power supply; and

coupling a second radio frequency device operatively to a second power supply.

15. The method of providing radio frequency inductive heating, as defined by claim 14, further comprising receiving a radio frequency signal from the control device by the plurality of radio frequency devices, the radio frequency signal providing an operating frequency associated with the plurality of radio frequency devices, the operating frequency being based on a resonant frequency associated with the resonant tank circuit.

16. The method of providing radio frequency inductive heating, as defined by claim 14, wherein the second power supply is a variable power supply, an output voltage associated with the first power supply being greater than an output voltage associated with the second power supply.

17. The method of providing radio frequency inductive heating, as defined by claim 14, further comprising activating the at least one of the plurality of radio frequency devices selectively by the control device based on a power set signal and a feedback signal, the power set signal representing a desired voltage associated with the resonant tank circuit, the feedback signal representing an electrical parameter associated with the resonant tank circuit.

18. The method of providing radio frequency inductive heating, as defined by claim 14, wherein at least one of the plurality of radio frequency devices comprises a full bridge inverter, the method further comprising:

receiving, by the full bridge inverter, a first phase signal and a second phase signal; and

modifying a phase difference between the first phase signal and the second phase signal selectively to modify an output voltage associated with the at least one of the plurality of radio frequency devices.

19. The method of providing radio frequency inductive heating, as defined by claim 14, wherein the plurality of transformers comprises a first transformer and a second transformer, the first transformer comprising a first turns ratio, the second transformer comprising a second turns ratio, the first turns ratio being unequal to the second turns ratio.

20. The method of providing radio frequency inductive heating, as defined by claim 14, wherein the plurality of radio frequency devices further comprises a first radio frequency device and a plurality of second radio frequency devices, the plurality of transformers comprising a first transformer and a plurality of second transformers, the method further comprising:

coupling the first radio frequency device operatively to the first transformer; and

coupling each of the plurality of second radio frequency devices operatively to one of the plurality of second transformers.

21. The method of providing radio frequency inductive heating, as defined by claim 20, wherein each of the plurality of second transformers comprises a turns ratio equal to one of n:

1 and (n−

1);

1, n representing a quantity of second radio frequency devices.

22. The method of providing radio frequency inductive heating, as defined by claim 20, wherein each of the plurality of second transformers comprises a turns ratio equal to 2ⁿ:

1, n representing an increasing positive integer.

23. The method of providing radio frequency inductive heating, as defined by claim 20, wherein the plurality of second radio frequency devices comprises a first radio frequency device and a second radio frequency device, the method further comprising:

coupling the first radio frequency device operatively to a first power supply; and

coupling the second radio frequency device operatively to a second power supply.

24. The method of providing radio frequency inductive heating, as defined by claim 23, wherein the second power supply is a variable power supply, an output voltage associated with the first power supply being greater than an output voltage associated with the second power supply.

25. The method of providing radio frequency inductive heating, as defined by claim 23, wherein an output voltage associated with the first power supply is twice an output voltage associated with the second power supply.

26. The method of providing radio frequency inductive heating, as defined by claim 23, wherein at least one of the first power supply and the second power supply comprises a rectifier.