DC-DC converter with multiple outputs

Patent metadata

Field	Value
Publication number	US-9806623-B2
Application number	US-201214360034-A
Country	US
Kind code	B2
Filing date	Jan 25, 2012
Priority date	Dec 9, 2011
Publication date	Oct 31, 2017
Grant date	Oct 31, 2017

Abstract

A multiple output DC-DC converter comprises a transformer, a primary circuit, a plurality of secondary circuits, and a controller. The transformer has a primary and at least one secondary winding. The primary circuit connects to a DC power supply source and includes the primary winding of the transformer and a primary switch connected in series. The plurality of secondary circuits includes the at least one secondary winding of the transformer, wherein each secondary circuit provides a DC power supply output, and at least one of the secondary circuits has a secondary switch. The controller monitors an output signal of each secondary circuit and controls operation of the primary and secondary switches based on the monitored signals. The controller co-ordinates operation of the secondary switch with the primary switch, such that the primary switch and the secondary switch are switched on simultaneously, or with a controlled offset.

First claim

The invention claimed is:

1. A multiple output DC-DC converter comprising:
a transformer having a primary winding and at least one secondary winding;
a primary circuit comprising:
an input that connects to a DC power supply source;
the primary winding of the transformer; and
a primary switch connected in series with the primary winding;

a plurality of secondary circuits, wherein each of the plurality of secondary circuits comprises the secondary winding of the transformer or a respective winding of a plurality of secondary windings of the transformer, and wherein each of the plurality of secondary circuits includes an output stage for providing a DC power supply output, wherein at least one of the secondary circuits comprises a secondary switch;
a digital controller that:
monitors a respective output signal of each of the plurality of secondary circuits, wherein the digital controller receives one bit of feedback data for each respective output signal per monitoring period;
generates, based on the monitored respective output signals and a respective digital representation of a desired on-off duty cycle for each of the at least one secondary circuits, a respective secondary digital control signal for each of the at least one secondary switch and a primary digital control signal; and
controls operation of the primary switch and the at least one secondary switch using control signals derived from the respective secondary digital control signals and the primary digital control signal;

wherein the digital controller co-ordinates operation of the at least one secondary switch with the primary switch, such that the primary switch and the at least one secondary switch are switched on at the same time, or with a controlled offset; and
wherein the combined operation of the primary switch and the at least one secondary switch provides an on-off duty cycle matched to load demands of the at least one secondary switch, and wherein the controlled offset is selectable per said secondary circuit.

2. The multiple output DC-DC converter according to claim 1 wherein the digital controller operates the primary switch with a duty cycle and the digital controller operates the secondary switch of the at least one secondary circuit with a duty cycle which is different to the duty cycle of the primary switch.

3. The multiple output DC-DC converter according to claim 1 , wherein the monitored output signals are indicative of loads of the secondary circuits and the digital controller operates the primary switch with a duty cycle matched to the secondary circuit having the greatest load.

4. The multiple output DC-DC converter according to claim 3 wherein, for at least one of the secondary circuits, the digital controller operates the secondary switch of the secondary circuit with a duty cycle which is shorter than the duty cycle of the primary switch.

5. The multiple output DC-DC converter according to claim 1 wherein, for at least one of the secondary circuits, the digital controller operates the secondary switch of the secondary circuit with a duty cycle based on the monitored output signal in that secondary circuit.

6. The multiple output DC-DC converter according to claim 1 wherein the transformer comprises the plurality of secondary windings, each secondary circuit comprises a respective one of the plurality of secondary windings and a primary winding/secondary winding turns ratio, and wherein at least two of the secondary circuits have a different primary winding/secondary winding turns ratio.

7. The multiple output DC-DC converter according claim 1 wherein at least two of the secondary circuits provide a different DC output voltage.

8. The multiple output DC-DC converter according claim 1 , wherein at least two of the secondary circuits provide the same DC output voltage.

9. The multiple output DC-DC converter according to claim 1 , wherein at least one of the secondary circuits outputs a voltage which varies over time.

10. The multiple output DC-DC converter according to claim 1 , wherein the digital controller comprises:
an input to receive an input signal from an output stage of one of the secondary circuits;
a comparator to compare the input signal with a reference signal and output a comparison result;
a digital filter to filter a set of comparison results of the comparator and provide a filtered output;
a store to store a sequence of filtered outputs; and
control logic to control at least one secondary switch of the multiple output DC-DC converter based on the filtered outputs.

11. A communication apparatus comprising:
a plurality of modules, each module having a DC power supply input;
a DC-DC converter comprising:
a transformer having a primary winding and at least one secondary winding;
a primary circuit comprising:
an input that connects to a DC power supply source;
the primary winding of the transformer; and
a primary switch connected in series with the primary winding;

a plurality of secondary circuits, wherein each of the plurality of secondary circuits comprises the secondary winding of the transformer or a respective winding of a plurality of secondary windings of the transformer, and wherein each of the plurality of secondary circuits includes an output stage for providing a DC power supply output, wherein at least one of the secondary circuits comprises a secondary switch;
a digital controller that:
monitors a respective output signal of each of the plurality of secondary circuits, wherein the digital controller receives one bit of feedback data for each respective output signal per monitoring period;
generates, based on the monitored respective output signals and a respective digital representation a desired on-off duty cycle for each of the at least one secondary circuits, a respective secondary digital control signal for each of the at least one secondary switch and a primary digital control signal; and
controls operation of the primary switch and the at least one secondary switch using control signals derived from the respective secondary digital control signals and the primary digital control signal;

wherein the digital controller co-ordinates operation of the at least one secondary switch with the primary switch, such that the primary switch and the at least one secondary switch are switched on at the same time, or with a controlled offset;
wherein the combined operation of the primary switch and the at least one secondary switch provides an on-off duty cycle matched to load demands of the at least one secondary switch, and wherein the controlled offset is selectable per said secondary circuit; and
the DC-DC converter comprising a plurality of DC power supply outputs, wherein each DC power supply output of the DC-DC converter is connected to a respective DC power supply input of one of the plurality of modules.

12. The communication apparatus according to claim 11 , further comprising a power management entity to determine a load demand of at least one of the plurality of modules and to cause the digital controller to activate the DC power supply outputs based on the determined load demand.

13. The communication apparatus according to claim 11 , further comprising a power management entity which is to determine a load demand of at least one of the plurality of modules and to cause the digital controller to scale the DC power supply outputs based on the determined load demand.

14. A method of providing multiple DC outputs at a multiple output DC-DC converter comprising a transformer having a primary winding and at least one secondary winding, the method comprising:
monitoring, by a digital cont

Assignees

• Grosso Renato
• Da Canal Alessandro
• Fanucci Luca
• Frello Antonio
• Rissotto Stefano
• Saponara Sergio
• ERICSSON TELEFON AB L M (publ)

Inventors

• Grosso Renato
• Da Canal Alessandro
• Fanucci Luca
• Frello Antonio
• Rissotto Stefano
• Saponara Sergio

Classifications

• H02M3/33576

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

• H02M3/33561 Primary

  having more than one ouput with independent control · CPC title

• H02M3/33515 Primary

  with digital control · CPC title