Method and apparatus for producing power for an induction heating system

• US 6,316,755 B1
• Filed: 05/19/2000
• Issued: 11/13/2001
• Est. Priority Date: 07/16/1997
• Status: Expired due to Fees

• Current Assignee: Illinois Tool Works Inc.
• Original Assignee: Illinois Tool Works Inc.
• Inventors: Ulrich, Mark
• Primary Examiner(s): Leung, Philip H.
• Application Number:
  US09/574,872
• Time in Patent Office: 543 Days
• Field of Search: 219/660, 219/661, 219/665, 219/666, 219/608, 219/778, 219/779, 219/663, 323/247, 323/328, 363/74, 363/21
• US Class Current: 219/665
• CPC Class Codes: H05B 6/06 Control, e.g. of temperature, of power
• CPC Class Codes: H05B 6/08 using compensating or balancing arrangements

Abstract

An induction heating power supply is disclosed. It includes a power circuit having at least one switch and a power output. The output circuit includes an induction head. The output circuit is coupled to the power output. A controller has at least one feedback input connected to the output circuit, and has a control output connected to the switch. The controller predicts the switch zero crossing and preferably soft switches the switch. Current feedback is obtained from a coil placed between the bus bars. Each bus bar is comprised of multiple plates to increase current capacity.

Claims

1. A resonant power supply comprising:

an output tank;

at least two bus bars connected to the output tank, wherein the bus bars are disposed with a gap therebetween;

a coil disposed in the gap, thereby having a voltage induced therein by a current flow in the bus bars;

a feedback circuit connected to the coil; and

a controller disposed to control the current in the tank, and connected to the feedback circuit.

2. The apparatus of claim 1 wherein the feedback circuit includes a filter.

3. The apparatus of claim 1 wherein the bus bars are substantially parallel.

4. A resonant power supply comprising:

an output tank;

at least two bus bars connected to the output tank, wherein the bus bars are disposed with a gap therebetween;

a coil disposed in the gap, thereby having a voltage induced therein by a current flow in the bus bars; and

feedback means for providing feedback of the current flow; and

control means for controlling the current in the tank, and connected to the feedback means.

5. The apparatus of claim 4 wherein the feedback means includes a filter means.

6. The apparatus of claim 5 wherein the bus bars are substantially parallel.

7. A method of controlling a resonant power supply, comprising:

providing an output tank;

connecting at least two bus bars to the output tank, wherein the bus bars are disposed with a gap therebetween;

disposing a coil in the gap, thereby inducing a voltage therein by a current flow in the bus bars;

providing feedback of the voltage; and

controlling the current in the tank in response to the feedback.