Programmable feed-forward regulation

Patent metadata

Field	Value
Publication number	US-10609796-B2
Application number	US-201615763809-A
Country	US
Kind code	B2
Filing date	Sep 27, 2016
Priority date	Sep 27, 2015
Publication date	Mar 31, 2020
Grant date	Mar 31, 2020

Abstract

Programmable drivers (or power supplies) for solid state light sources are disclosed, on which output regulation is improved to expand the dimming range to 1% and reduce and/or remove flicker. Additional fault conditions are set up to avoid latching, and thus provide for a controllable restart feature. Such drivers include an isolated half bridge resonant converter with an improved control approach designed to regulate very low current though primary side in a feed-forward loop. Such drivers include both digital and analog loops that improve the performance in steady state and/or during transients, particularly for a lighting load, in comparison to a single full digital control.

First claim

What is claimed is:

1. A regulation circuit comprising:
a forward loop connectable to a primary side of a transformer, the forward loop sampling a load current at the primary side of a transformer as a half waveform proportional to the load current, the forward loop providing a first output connectable to a controller configured to regulate a solid state driver; and
a feedback loop connectable to a secondary side of a transformer, the feedback loop providing a second output connectable to a controller configured to regulate the solid state driver;

wherein the forward loop comprises:
a half-bridge shunt circuit having a shunt circuit input and a shunt circuit output;
a first series resistor having a first lead connected to the output of the half-bridge shunt circuit and a second lead; and
a converter having an input connected to the second lead of the first series resistor and an output comprising the first output to regulate a solid state driver.

2. The regulation circuit of claim 1 , wherein the half-bridge shunt comprises:
a half bridge rectifier having a half-bridge rectifier input connected to the shunt bridge input, a half-bridge rectifier output connected to the shunt circuit output and a connection to ground; and
a shunt resistor having a first lead connected to the shunt circuit output and a second lead connected to ground.

3. The regulation circuit of claim 2 , wherein the half-bridge rectifier comprises:
a first schottky diode having an anode connected to the half-bridge rectifier input, and a cathode connected to the half-bridge rectifier output; and
a second schottky diode having an anode connected to ground and a cathode connected to the half-bridge rectifier input.

4. The regulation circuit of claim 1 , wherein the feedback loop comprises:
a Proportional Integral Derivative (PID) digital control programmable set point having a current sensing input capable of electrical communication with a first lead of a load, a voltage sensing input capable of electrical communication with a second lead of the load, a connection to an isolated ground, a user setting input, and an output;
a second series resistor having a first lead connected to the output of the PID digital control programmable set point, and a second lead;
an opto-coupler having a first input connected to the second lead of the second resistor, a second input connected to the isolated ground; a third input, and an output;
a pull-up resistor having a first lead connected to a reference voltage, and a second lead connected to the third input of the opto-coupler;
a filter having a first input connected to the output of the opto-coupler, a second input connected to ground, and an output; and
a third series resistor having a first lead connected to the output of the filter and a second lead comprising the second output of the feedback loop.

5. The regulation circuit of claim 1 , wherein the filter comprises:
a fourth resistor having a first lead connected to the first input of the filter, and a second lead connected to the second input of the filter;
a fifth resistor having a first lead connected to the first lead of the fourth resistor and a second lead connected to the output of the filter; and
a first capacitor having a first lead connected to the output of the filter and a second lead connected to the second lead of the fourth resistor.

6. The regulation circuit of claim 1 , further comprising a first voltage divider coupled to an anode of a third diode, the third diode having a cathode connectable to a reset input of the controller, the first voltage divider and the third diode setting a voltage for normal operation of the regulation circuit.

7. The regulation circuit of claim 6 , wherein the first voltage divider comprises:
a sixth resistor having a first lead connectable to a first side of the primary transformer and having a second lead; and
a seventh resistor having a first lead connected to the second lead of the sixth resistor and having a second lead connected to ground.

8. The regulation circuit of claim 1 , further comprising:
an eighth resistor having a first lead connectable to a Direct Current (DC) bus and a second lead;
a fourth diode having an anode connected to the second lead of the eighth resistor and a cathode connectable to the reset input of the controller; and
a ninth resistor having a first lead connected to the cathode of the fourth diode and having a second lead connected to ground, the eighth resistor, the fourth diode, and the ninth resistor setting a voltage for a startup condition of the regulation circuit.

9. The regulation circuit of claim 1 , further comprising a fault detection circuit coupled to a primary side of the transformer.

10. The regulation circuit of claim 1 , wherein the fault detection circuit includes a load open fault detection circuit and a load short fault detection circuit.

11. The regulation circuit of claim 10 , wherein the load open fault detection circuit comprises:
a second capacitor having a first lead connectable to a first side of a primary of the transformer and a second lead;
a third capacitor having a first lead connected to the second lead of the second capacitor and having a second lead connected to ground;
a fifth zener diode having a cathode connected to the second lead of the second capacitor and having an anode;
a sixth zener diode having a cathode connected to the anode of the fifth zener diode and having a cathode;
a tenth resistor having a first lead connected to the cathode of the fifth zener diode and having a second lead connected to ground;
a seventh diode having a anode connected to the first lead of the tenth resistor and having a cathode; and
an eleventh resistor having a first lead connected to the cathode of the third diode and having a second lead connected to an overcurrent protection input of the controller.

12. The regulation circuit of claim 11 , wherein, in a load open condition, an excessive voltage is detected by the second capacitor, the third capacitor, the fifth zener diode, the sixth zener diode as higher than normal voltage over the tenth resistor, wherein the voltage over the tenth resistor is high enough to cause the seventh diode to conduct, causing an over current status for a half-bridge shunt, that results in an instantaneous shut down of the controller.

13. The regulation circuit of claim 10 , wherein the load short fault detection circuit comprises:
the half-bridge shunt; and
the first voltage divider.

14. The regulation circuit of claim 13 , wherein during a load short fault condition the voltage at the first voltage divider drops below 0.3 volts and resets the controller.

15. The regulation circuit of claim 13 , wherein a normal window for operation is less than two volts and greater than 0.3 volts, wherein the normal window voltage is greater than 2 volts in an open load condition, and wherein the normal window voltage is less than 0.3 volts in a load short condition.

16. The regulation circuit of claim 1 , wherein the forward loop samples the load current at the primary side of a transformer on a cycle by cycle basis.

17. The regulation circuit of claim 1 , further comprising a load connectable to the feedback loop.

Assignees

• Osram Sylvania Inc

Inventors

• Olmos Eliseo Carcamo
• Lara Luis Manuel Leon

Classifications

• H05B47/23

  of two or more light sources connected in series · CPC title

• H05B47/235

  with communication between the lamps and a central unit · CPC title

• H05B37/038

  Electricity · mapped topic

• H05B41/2827 Primary

  using specially adapted components in the load circuit, e.g. feed-back transformers, piezoelectric transformers; using specially adapted load circuit configurations · CPC title

• H05B37/036

  Electricity · mapped topic