Isolation of secondary transformer winding current during auxiliary power supply generation

Patent metadata

Field	Value
Publication number	US-10122282-B2
Application number	US-201615336835-A
Country	US
Kind code	B2
Filing date	Oct 28, 2016
Priority date	Dec 14, 2011
Publication date	Nov 6, 2018
Grant date	Nov 6, 2018

Abstract

An electronic system and method include a controller to actively control power transfer from a primary winding of a switching power converter to an auxiliary-winding of an auxiliary power supply. The switching power converter is controlled and configured such that during transfer of power to the auxiliary-winding, the switching power converter does not transfer charge to one or more secondary-windings of the switching power converter. Thus, the switching power converter isolates one or more secondary transformer winding currents from an auxiliary-winding current. By isolating the charge delivered to the one or more secondary-windings from charge delivered to the auxiliary-winding, the controller can accurately determine an amount of charge delivered to the secondary-windings and, thus, to a load.

First claim

What is claimed is:

1. An apparatus comprising:
a flyback type switching power converter, wherein the switching power converter includes a transformer having a primary-winding, a secondary-winding, and an auxiliary-winding;
a first switch coupled to the primary-winding;
an auxiliary power supply that includes auxiliary power supply control circuitry coupled to the auxiliary-winding; and
a controller coupled to the first switch configured to provide a control signal and configured to (i) control the first switch and current in the primary winding and (ii) control the auxiliary power supply circuitry to isolate a transfer of energy from the primary-winding to the secondary-winding from a transfer of energy from the primary-winding to the auxiliary-winding,
wherein the auxiliary power supply having the auxiliary-winding provides auxiliary power to the controller that provides the control signal to control the transferring of energy from the primary-winding, and the secondary-winding delivers energy for a load of the switching power converter, and
a capacitor coupled to the controller and to a Zener diode, and a supply voltage node for the controller coupled to the Zener diode, wherein the capacitor and Zener diode are coupled to a current control node of the second switch.

2. The apparatus of claim 1 wherein the auxiliary power supply control circuitry comprises the auxiliary-winding, a diode coupled to a first terminal of the auxiliary-winding, and a second switch coupled to the diode.

3. The apparatus of claim 1 wherein the capacitor stores charge to maintain an approximately constant supply voltage for controller.

4. The apparatus of claim 1 wherein the controller depletes charge from the capacitor when the auxiliary power supply is not operating.

5. The apparatus of claim 1 , wherein the controller is configured to at least control a transfer of energy from the primary winding of the transformer to the secondary-winding of the switching power converter and to the auxiliary-winding for the auxiliary power supply during mutually exclusive periods of time.

6. The apparatus of claim 5 wherein the periods of time comprise successive switching cycles of a switch that controls the transferring of energy from the primary-winding.

7. The apparatus of claim 5 wherein the controller is configured to at least control a first value of a reflected voltage of the auxiliary-winding of the transformer to be lower than a reflected voltage of the secondary winding of the transformer during transfer of energy to the auxiliary-winding and controlling a second value of the reflected voltage of the auxiliary.

8. The apparatus of claim 1 wherein the controller is configured to
cause the first switch to conduct current flow in the auxiliary-winding of the transformer; and
cause the first switch to stop conducting current flow in the auxiliary-winding of the transformer and allow current to flow in the secondary-winding of the transformer.

9. The apparatus of claim 8 wherein the controller is configured to control the first switch to conduct current flow in the secondary-winding of the transformer until a pre-determined threshold is reached.

10. The apparatus of claim 1 wherein the controller is further configured to:
during a first period, control the transfer of energy from the primary-winding of the transformer to the secondary-winding; and
during a second period of time, control transfer of energy from the primary-winding to the auxiliary-winding, wherein the first time period and the second time period are mutually exclusive.

11. The apparatus of claim 1 wherein the controller receives a control signal from a dimmer to modify the transfer of energy to the load.

12. The apparatus of claim 11 wherein the dimmer is a triac-based dimmer.

13. The apparatus of claim 11 wherein the load is a lamp.

Assignees

• Philips Lighting Holding Bv

Inventors

• Melanson John L
• Drakshapalli Prashanth
• Maru Siddharth

Classifications

• H02M1/4258

  using a single converter stage both for correction of AC input power factor and generation of a regulated and galvanically isolated DC output voltage (H02M1/4241 takes precedence) · CPC title

• H02M3/33576

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

• H02M1/44

  Circuits or arrangements for compensating for electromagnetic interference in converters or inverters · CPC title

• H02M7/217

  using semiconductor devices only · CPC title

• H02M5/2576

  with digital control · CPC title