Isolation of secondary transformer winding current during auxiliary power supply generation

• US 10,122,282 B2
• Filed: 10/28/2016
• Issued: 11/06/2018
• Est. Priority Date: 12/14/2011
• Status: Active Grant

• Current Assignee: Signify Holding B.V. (Signify N.V.)
• Original Assignee: Philips Lighting BV (Koninklijke Philips N.V.)
• Inventors: Melanson, John L., Drakshapalli, Prashanth, Maru, Siddharth
• Primary Examiner(s): Behm, Harry
• Application Number:
  US15/336,835
• Publication Number:
  US 20170047850A1
• Time in Patent Office: 739 Days
• CPC Class Codes: H02M 1/0006 Arrangements for supplying an adequate voltage to the control circuit of converters
• CPC Class Codes: H02M 1/0048 Circuits or arrangements for reducing losses using snubbers H02M1/34
• CPC Class Codes: H02M 1/4258 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 Class Codes: H02M 1/44 Circuits or arrangements for compensating for electromagnetic interference in converters or inverters
• CPC Class Codes: H02M 3/33507 with automatic control of the output voltage or current, e.g. flyback converters H02M3/33561, H02M3/33569 take precedence
• CPC Class Codes: H02M 3/33523 with galvanic isolation between input and output of both the power stage and the feedback loop
• CPC Class Codes: H02M 3/33561 having more than one ouput with independent control
• CPC Class Codes: H02M 3/33576 having at least one active switching element at the secondary side of an isolation transformer
• CPC Class Codes: H02M 5/2576 with digital control
• CPC Class Codes: H02M 7/217 using semiconductor devices only
• CPC Class Codes: H05B 45/10 Controlling the intensity of the light
• CPC Class Codes: H05B 45/385 using flyback topology
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

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.

Claims

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.