Multiple output converter with continuous power transfer to an output and with multiple output regulation

• US 5,541,828 A
• Filed: 11/23/1994
• Issued: 07/30/1996
• Est. Priority Date: 12/15/1992
• Status: Expired due to Term

• Current Assignee: Lineage Power Corporation (GE Aerospace)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Rozman, Allen F.
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): BERHANE, ADOLF D
• Application Number:
  US08/344,754
• Time in Patent Office: 615 Days
• Field of Search: 363/20, 363/21, 363/22, 363/127, 363/131, 363/84, 363/95, 363/97, 363/67, 323/267
• US Class Current: 363/21.1
• CPC Class Codes: H02M 1/40 Means for preventing magnetic saturation
• CPC Class Codes: H02M 3/33569 having several active switching elements H02M3/3353 takes precedence

Abstract

A DC-DC converter, having multiple outputs, efficiently utilizes its power transformer to provide continuous power output to the outputs except during transitions of the power switches. Energy flow is continuous to one or more outputs during conduction of the power switch and then is transferred to the remaining outputs during its non-conduction. A feedback control, connected to sense only one of the outputs operate the power switch at a controlled duty cycle. Regulation of both outputs is enabled by equalizing transformer volt seconds of the non-conduction and conduction intervals of the power switch and by a clamping circuit which sustains the volt seconds in the power transformer during the non-conduction interval. In a particular embodiment, a converter circuit comprises a transformer having a primary winding and a secondary winding. An input is coupled to the primary winding, first and second switch devices are each coupled to the primary winding of the transformer, and a clamp capacitor is coupled to the transformer by at least one of the first and second switches. Portions of the secondary winding are coupled through separate rectifier devices and through separate output filter inductors to separate inputs. A single feedback circuit is coupled to one of the outputs and supplies drive signals to the first and second switches so as to cause the first and second switches to conduct current alternately.

Claims

1. A DC-DC converter, comprising:

a transformer having a primary winding and a secondary winding with first and second end terminals;

a primary circuit connected for coupling an input DC voltage to the primary winding, including a first switch connected in series with the primary winding and the input DC voltage; and

a clamping circuit including a storage capacitor and a second switch enabled to connect the capacitor to the primary winding when the first switch is non conducting;

a secondary circuit connected for connecting energy from the first end terminal of the secondary winding to a first and second output;

including;

a first output channel connected to the first end terminal and including in a first series connection a first rectifying diode and a first inductor and the first series connection connecting the first end terminal to the first output;

a second output channel connected to the first end terminal and including in a second series connection a second rectifying diode and a second inductor and the second series connection connecting the first end terminal to the second output;

a first and second capacitor connecting the first and second outputs to a return lead which is connected to the second end terminal of the secondary winding; and

a feedback circuit including means to sense one of the first and second outputs and including means to generate an error voltage representative of a deviation of the sensed output from a desired regulated value and a pulse width modulator responsive to the error voltage and connected to drive the first and second switches such that the primary winding experiences equal volt seconds during conduction and non-conduction intervals of the first switch in order to regulate both the first and second output, with energy transfer to the first output channel during conduction of the first switch and with energy transfer to the second output channel during conduction of the second switch.

2. A DC-DC converter, comprising:

A transformer having a primary winding and a secondary winding having a tap intermediate its first and second end terminals;

a primary circuit connected for coupling an input DC voltage to the primary winding, including a first switch connected in series with the primary winding and the input DC voltage; and

a clamping circuit including a storage capacitor and a second switch enabled to connect the capacitor to the primary winding when the first switch is non conducting;

a secondary circuit connected for connecting energy from the first end terminal of the secondary winding and the tap intermediate its first and second end terminals to a first and second output;

including;

a first output channel connected to the first end terminal and including in a first series connection a first rectifying diode and a first inductor and the first series connection connecting the first end terminal to the first output;

a second output channel connected to the tap intermediate the first and second end terminals and including in a second series connection a second rectifying diode and a second inductor and the second series connection connecting the tap to the second output;

a first and second capacitor connecting the first and second outputs to a return lead which is connected to the second end terminal of the secondary winding; and

a feedback circuit including means to sense one of the first and second outputs and including means to generate an error voltage representative of a deviation of the sensed output from a desired regulated value and a pulse width modulator responsive to the error voltage and connected to drive the first and second switches such that the primary winding experiences equal volt second during conduction and non-conduction intervals of the switch in order to regulate both the first and second output, with energy transfer to the first output channel during conduction of the first switch and with energy transfer to the second output channel during conduction of the second switch.

3. A DC-DC converter, comprising:

a transformer having a primary winding and a secondary winding having a tap intermediate its first and second end terminals;

a primary circuit connected for coupling an input DC voltage to the primary winding, including a first switch connected in series with the primary winding and the input DC voltage; and

a clamping circuit including a storage capacitor and a second switch enabled to connect the capacitor to the primary winding when the first switch is non conducting;

a secondary circuit connected for connecting energy from the first and second end terminals of the secondary winding to a first and second output;

including;

a first output channel connected to the first end terminal and including in a first series connection a first rectifying diode and a first inductor and the first series connection connecting the first end terminal to the first output;

a second output channel connected to the second end terminal and including in a second series connection a second rectifying diode and a second inductor and the second series connection connecting the second end terminal to the second output;

a first and second capacitor connecting the first and second outputs to a return lead which is connected to the tap of the secondary winding; and

a feedback circuit including means to sense one of the first and second outputs and including means to generate an error voltage representative of a deviation of the sensed output from a desired regulated value an a pulse width modulator responsive to the error voltage and connected to drive the first and second switches such that the primary winding experiences equal volt seconds during conduction and non-conduction intervals of the first switch in order to regulate both the first and second output with energy transfer to the first output channel during conduction of the first switch and with energy transfer to the second output channel during conduction of the second switch.

4. A DC-DC converter, comprising:

a transformer having a primary winding and a first and second secondary winding galvanically isolated;

a primary circuit connected for coupling an input DC voltage to the primary winding, including a first switch connected in series with the primary winding and the input DC voltage; and

a clamping circuit including a storage capacitor and a second switch enabled to connect the capacitor to the primary winding when the first switch is non conducting;

a secondary circuit connected for connecting energy from the first and second secondary windings to a first and second output, respectively;

including;

a first output channel connected to the first secondary winding and including in a first series connection a first rectifying diode and a first inductor and the first series connection connecting the first secondary winding to the first output;

a second output channel connected to the second secondary winding and including in a second series connection a second rectifying diode and a second inductor and the second series connection connecting the second secondary winding to the second output;

a first and second capacitor connecting the first and second outputs to a first and second return lead, each of which is connected to the first and second secondary winding, respectively; and

a feedback circuit including means to sense one of the first and second outputs and including means to generate an error voltage representative of a deviation of the sensed output from a desired regulate value and a pulse width modulator responsive to the error voltage and connected to drive the first and second switches such that the primary winding experiences equal volt seconds during conduction and non-conduction intervals of the first switch in order to regulate both the first and second output, with energy transfer to the first output channel during conduction of the first switch and with energy transfer to the second output channel during conduction of the second switch.

5. A DC to DC converter, comprising:

a power transformer having a primary winding and at least a secondary winding means as an output of the transformer;

a primary circuit connected for coupling an input DC voltage to the primary winding, including a first switch connected in series with the primary winding and the input DC voltage; and

a clamping circuit including a storage capacitor and a second switch enabled to connect the capacitor to the primary winding when the first switch is non conducting;

a secondary circuit connected for connecting energy from an output of the power transformer to a first and second output;

including;

a first output channel connected to the output of the power transformer and including in a first series connection a first rectifying diode and a first inductor and the first series connection connecting the output of the power transformer to the first output;

a second output channel connected to the output of the power transformer and including in a second series connection a second rectifying diode and a second inductor and the second series connection connecting the output of the power transformer to the second output;

a first and second capacitor connecting the first and second outputs to a return lead which is connected to the first and second capacitor connecting the first and second outputs to a return lead which is connected to the power transformer; and

a feedback circuit including means to sense one of the first and second outputs and including means to generate an error voltage representative of a deviation of the sensed output from a desired regulated value and a pulse width modulator responsive to the error voltage and connected to drive the first and second switches such that the primary winding experiences equal volt seconds during conduction and non-conduction intervals of the power switch in order to regulate both the first and second output, with energy transfer to the first output channel during conduction of the first switch and with energy transfer to the second output channel during conduction of the second switch.

6. A DC to DC converter, as claimed in claim 5, comprising:

the secondary winding means having a winding with a first and second end terminal and a tap intermediate the first and second end terminals; and

the first and second output channels being connected to the first end terminal and a return lead from the output being connected to the second end terminal.

7. A DC to DC converter, as claimed in claim 5, comprising:

the secondary winding means having a winding with first and second end terminals and a tap intermediate the first and second end terminals; and

the first and second output channels being connected to the first end terminal and the tap respectively and a return lead from the output being connected to the second end terminal.

8. A DC to DC converter, as claimed in claim 5, comprising:

the secondary winding means having a winding with first and second end terminals and a tap intermediate the first and second end terminals; and

the first and second output channels being connected to the first end terminal and the second end terminal, respectively and a return lead from the output being connected to the tap intermediate the first and second end terminals.

9. A DC to DC converter, as claimed in claim 5, comprising:

the secondary winding means having a first and second independent galvanically isolated secondary windings, each having first and second end terminals; and

the first and second output channels being connected to the first end terminal of each of the first and second isolated secondary windings, and a return lead from each of the first and second outputs being connected to the second end terminals of the first and second secondary windings, respectively.