SYSTEM AND METHOD FOR CONTROLLING QUASI-RESONANT INDUCTION HEATING DEVICES

• US 20190327791A1
• Filed: 04/23/2018
• Published: 10/24/2019
• Est. Priority Date: 04/23/2018
• Status: Active Grant

• Current Assignee: Whirlpool Corporation
• Original Assignee: Whirlpool Corporation
• Inventors: Baldo, Salvatore, Gallivanoni, Andrea, Parachini, Davide, Pastore, Cristiano Vito
• Granted Patent: US 11,140,751 B2
• Time in Patent Office: Days
• CPC Class Codes: H02M 7/06 using discharge tubes without control electrode or semiconductor devices without control electrode
• CPC Class Codes: H05B 6/062 for cooking plates or the like
• CPC Class Codes: H05B 6/065 using coordinated control of multiple induction coils
• CPC Class Codes: H05B 6/1209 induction cooking plates or the like and devices to be used in combination with them

Abstract

A control circuit for an induction heating device comprises a D.C. power supply, referenced to a ground connection and configured to supply power to the induction heating device. A switching device is configured to be selectively activated to control the induction heating device. The switching device is connected on one end to the ground connection. A resonant load is disposed between the D.C. power supply and the switching device, the resonant load comprises a capacitor and an inductor connected in a parallel configuration. At least one rectifying device is disposed in series with the resonant load and the switching device. The switching device is configured to control current from the D.C. power supply through the resonant load.

Claims

1. A control circuit for an induction heating device comprising:

a D.C. power supply, referenced to a ground connection, configured to supply power to the induction heating device;

a switching device configured to be selectively activated to control the induction heating device, the switching device being connected on one end to the ground connection;

a resonant load disposed between the D.C. power supply and the switching device, the resonant load comprising a capacitor and an inductor connected in a parallel configuration; and

at least one rectifying device disposed in series with the resonant load and the switching device, wherein the switching device is configured to control current from the D.C. power supply through the resonant load.

2. The control circuit according to claim 1, wherein the rectifying device is embodied as a diode.

3. The control circuit according to claim 1, wherein the rectifying device is arranged such that current is conducted directionally from the resonant load to the switching device.

4. The control circuit according to claim 1, wherein the rectifying device is disposed between the resonant load and the switching device.

5. The control circuit according to claim 4, wherein the rectifying device is a diode connected to the resonant load on an anode side and to the switching device on a cathode side.

6. The control circuit according to claim 5, wherein the diode prevents the reverse current passing from the switching device to the resonant load and the power supply in response to a voltage at the anode being less than zero.

7. The control circuit according to claim 1, wherein the rectifying device is disposed between the D.C. power supply and the resonant load.

8. The control circuit according to claim 7, wherein the rectifying device is a diode connected to the D.C. power supply on an anode side and to the resonant load on a cathode side.

9. The control circuit according to claim 8, wherein the diode prevents the reverse current passing from the resonant load to the power supply in response to a voltage at the cathode side being greater than a D.C. power supply voltage.

10. The control circuit according to claim 1, wherein the switching device and the rectifying device are combined forming a reverse-blocking switching device.

11. The control circuit according to claim 10, wherein the reverse-blocking switching device is a reverse-blocking IGBT.

12. The control circuit according to claim 1, wherein the rectifying device is configured to block reverse-current returning through the switching device into the resonant load and the D.C. power supply.

13. A method for controlling an induction heating device comprising:

supplying current from a D.C. power supply into an input node of a resonant load;

emitting the current from an output node of the resonant load;

directionally conducting the current in a unidirectional path from the output node of the resonant load to a switching node downstream along the unidirectional path from the output node; and

controlling a current conducted through the resonant load with a switching device.

14. The method according to claim 13 wherein the resonant load comprises a capacitor and an inductor connected in parallel between the input node and the output node.

15. The method according to claim 13, wherein the current is supplied from the power supply to the resonant load substantially without conductive interruption.

16. The method according to claim 13, further comprising:

blocking a reverse-current opposite the unidirectional path from passing through the switching device, the resonant load and the D.C. power supply.

17. The method according to claim 16, wherein the switching device is activated from the instant when the current flowing in the resonant load is zero until the voltage across the resonant load returns to less than the voltage of the D.C. power supply.

18. The method according to claim 17, wherein the diode prevents a reverse current from passing from a switching device at the switching node to the D.C. bus in response to the voltage at the output node or the switching node being less than zero.

19. A control circuit for an induction heating coil comprising:

a D.C. power supply, referenced to a ground connection, configured to supply power to the induction heating device;

a switching device configured to be selectively activated supplying driving current to the induction heating coil, the switching device being connected on one end to the ground connection;

a resonant load disposed between the D.C. power supply and the switching device, the resonant load comprising a capacitor and the induction heating coil connected in parallel; and

a rectifying device disposed in series between the D.C. power supply and the switching device.

20. The control circuit according to claim 19, wherein the rectifying device is embodied as a diode positioned either:

in series between the D.C. power supply and the resonant load;

or

in series between the resonant load and the switching device.