Isolated power converter for a thermal system

Patent metadata

Field	Value
Publication number	US-11038431-B2
Application number	US-202016868230-A
Country	US
Kind code	B2
Filing date	May 6, 2020
Priority date	Jun 15, 2016
Publication date	Jun 15, 2021
Grant date	Jun 15, 2021

Abstract

A power converter system provides adjustable power to a heater and includes an input rectifier and a full-bridge isolating converter. The input rectifier is configured to rectify a line power having a line energy. The full-bridge isolating converter configured to generate an isolated output voltage based on the rectified line power. The isolated output voltage is electrically isolated from the line energy.

First claim

What is claimed is:

1. A power converter system for providing adjustable power to a heater, the power converter system comprising:
an input rectifier configured to rectify a line power having a line energy;
a full-bridge isolating converter comprising a full-bridge rectifier, wherein the full-bridge isolating converter is configured to generate an isolated output voltage based on the rectified line power, wherein the isolated output voltage is electrically isolated from the line energy; and
a power controller configured to operate the full-bridge rectifier to generate the isolated output voltage, wherein:
the power controller is configured to perform a variable frequency control to generate an output voltage that is less than or equal to a voltage limited power setpoint as the isolated output voltage; and
the variable frequency control comprises reducing a switching frequency of the full-bridge rectifier from a standard frequency to a first frequency, reducing a pulse period of the full-bridge rectifier when the switching frequency is equal to the first frequency, and reducing the switching frequency from the first frequency to a second frequency when the pulse period is reduced.

2. The power converter system of claim 1 , wherein the full-bridge isolating converter further comprises:
a transformer electrically coupled to the full-bridge rectifier, wherein the transformer is configured to generate an isolated full-wave voltage; and
an output rectifier configured to rectify the isolated full-wave voltage to generate the isolated output voltage.

3. The power converter system of claim 1 , wherein the full-bridge rectifier includes a first pair of electronic switches and a second pair of electronic switches to drive the transformer with the rectified line power.

4. The power converter system of claim 2 further comprising a bridge sensor configured to detect an electric current through a primary winding of the transformer to detect flux walk.

5. The power converter system of claim 1 further comprising a filter configured to filter the isolated output voltage to output a desired output voltage.

6. The power converter system of claim 1 , wherein the input rectifier is configured to receive, as the line power, one of a single-phase alternating current (AC) or a direct current (DC).

7. A control system comprising:
the power converter system of claim 1 ; and
a primary system controller configured to determine a desired output voltage and control the power converter system to generate the desired output voltage.

8. A method of converting power to operate a load being supplied by line power having a line energy comprising:
rectifying the line power; and
switchably driving a transformer with the rectified line power to generate an adjustable electrically isolated full-wave voltage;
rectifying the electrically isolated full-wave voltage to obtain an isolated output voltage that is indicative of a desired output voltage applied to the load, wherein current is drawn from the line power in phase with the isolated output voltage; and
performing a variable frequency control when the desired output voltage is less than a voltage limited power setpoint to drive the transformer at a switching frequency less than that of when the desired output voltage is greater than the voltage limited power setpoint, wherein the variable frequency control includes reducing a switching frequency from a standard frequency to a first frequency, reducing a pulse period when the switching frequency is equal to the first frequency, and reducing the switching frequency from the first frequency to a second frequency when the pulse period is reduced.

9. The method of claim 8 further comprising filtering the isolated output voltage to obtain the desired output voltage.

10. The method of claim 8 further comprising:
detecting an electric current through a primary winding of the transformer; and
performing a corrective action when the electric current is greater than a flux current threshold.

11. The method of claim 8 further comprising:
detecting an applied voltage, wherein the applied voltage is at least one of the line power or the rectified line power; and
performing a corrective action when the applied voltage exceeds a predefined voltage range.

12. The method of claim 8 , wherein the line power is one of a single-phase alternating current (AC) or a direct current (DC).

13. The method of claim 8 , wherein switchably driving the transformer further comprises alternatingly driving a first pair of electronic switches and a second pair of electronic switches, wherein the first pair of electronic switches and the second pair of electronic switches form a full-bridge rectifier.

14. A power converter system for providing a desired output voltage to a heater, the power converter system comprising:
an input rectifier configured to rectify a line power having a line energy;
a transformer configured to generate an isolated full-wave voltage;
a full-bridge rectifier electrically coupled to the transformer and operable to drive the transformer to generate the isolated full-wave voltage based on the rectified line power;
an output rectifier configured to rectify the isolated full-wave voltage to generate an isolated output voltage indicative of the desired output voltage;
a bridge sensor configured to measure a bridge current flowing through the transformer; and
a power controller configured to operate the full-bridge rectifier to drive the transformer, wherein:
the power controller is configured to perform a variable frequency control to generate an output voltage that is less than or equal to a voltage limited power setpoint as the isolated output voltage; and
the variable frequency control comprises reducing a switching frequency of the full-bridge rectifier from a standard frequency to a first frequency, reducing a pulse period of the full-bridge rectifier when the switching frequency is equal to the first frequency, and reducing the switching frequency from the first frequency to a second frequency when the pulse period is reduced.

15. The power converter system of claim 14 , wherein the power controller is configured to determine a flux walk state in response to the bridge current being greater than or equal to a flux current threshold, and the power controller is configured to perform a corrective action in response to the flux walk state.

16. The power converter system of claim 14 further comprising a filter configured to filter the isolated output voltage to output the desired output voltage.

17. The power converter system of claim 14 , wherein the input rectifier is configured to receive, as the line power, one of a single-phase alternating current (AC) or a direct current (DC).

Assignees

• Watlow Electric Mfg

Inventors

• Ness Keith
• Rozek Geoffrey
• Breitlow Stanton H
• Hentges James
• Lemke John
• Bohlinger William
• Yender Matthew

Classifications

• H05B1/0266 Primary

  Cooktops · CPC title

• H02M3/33573

  Full-bridge at primary side of an isolation transformer · CPC title

• H02M3/33576 Primary

  having at least one active switching element at the secondary side of an isolation transformer · CPC title

• H02M7/219

  in a bridge configuration · CPC title

• H05B3/0019

  Circuit arrangements · CPC title